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A 
 
 DICTIONARY 
 
 OF 
 
 CHEMIS T R Y, 
 
 ON THE 
 
 BASIS OF MR NICHOLSON’S; 
 
 IN WHICH 
 
 THE PRINCIPLES OF THE SCIENCE ARE INVESTIGATED ANEW, 
 
 AND ITS APPLICATIONS TO THE PHENOMENA OF NATURE, MEDICINE, 
 MINERALOGY, AGRICULTURE, AND MANUFACTURES, 
 
 DETAILED. 
 
 By ANDREW URE, M.D. 
 
 I'ROI'T.SSOH, OF THE ANDERSONIAN INSTITUTION, MEMBER OF THE QEOLOGICAL SOCIETY, 
 
 &C. &C. 
 
 WITH AN 
 
 Btssntation ; 
 
 CONTAINING 
 
 INSTRUCTIONS FOR CONVERTING THE ALPHABETICAL ARRANGEMENT 
 
 INTO A SYSTEMATIC ORDER OF STUDY. 
 
 LUJNDON: 
 
 PHINTED FOR THOMAS & GEORGE UNDERWOOD; J. IlIGHLEY & SON 
 
 SIMPKIN & marshall, stat, oners’ court’; 
 
 GIASCOW I'in SI r DE : A * BI ' ACK ’ EDINBURGH : «• GRIFFIN & CO. 
 GLASGOW . AND J. CUMMING, DUBLIN. 
 
 l^¥l. 
 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
TO 
 
 THE RIGHT HONOURABLE 
 
 THE EARL OE GLASGOW, 
 
 BARON ROSS OF HAWKHEAD, 
 
 &C. &C. &C. 
 
 LOltD-LIEUTENANT OF AYRSHIRE. 
 
 My Lord, 
 
 When 1 inscribe this volume to your Lordship, it is 
 neither to offer the incense of adulation, which your virtues do not 
 need, and your understanding would disdain ; nor to solicit the 
 patronage of exalted rank to a work, which in this age and nation 
 must seek support in scientific value alone. The present dedication 
 is merely an act of gratitude, as pure on my part, as your Lordship’s 
 condescension and kindness to me have been generous and unvary- 
 ing. At my outset in life, your Lordship’s distinguished favour 
 cherished those studious pursuits, which have since formed my chief 
 pleasure and business; and to your Lordship’s hospitality I owe the 
 elegant retirement, in which many of the following pages were 
 written. Happy would it have been for their readers, could I have 
 transfused into them a portion of that grace of diction, and elevation 
 of sentiment, which I have so often been permitted to admire in 
 your Lordship’s family. 
 
 I have the honour to be, 
 
 My Lord, 
 
 Glasgow, 
 November 7. 1820. 
 
 \our Lordship’s most obedient 
 
 And very faithful Servant, 
 
 ANDREW URE. 
 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 ' 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
INTRODUCTION. 
 
 In this Introduction I shall first present a general view of the objects 
 of chemistry, along with a scheme for converting the alphabetical arrange- 
 ment adopted in this volume, into a systematic order of study. I shall then 
 describe the manner in which this Dictionary seems to have been original- 
 ly compiled, and the circumstances under which its present regeneration 
 has been attempted. This exposition will naturally lead to an account of 
 the principles on which the investigations of chemical theory and facts 
 have been conducted, which distinguish this Work from a mere compilation. 
 Some notice is then given of a Treatise on Practical Chemistry, publicly an- 
 nounced by me upwards of three years ago, and of the peculiar circum- 
 stances of my situation as a teacher, which prompted me to undertake it, 
 though its execution has been delayed by various obstructions. 
 
 The forms of matter are numberless, and subject to incessant change. 
 Amid all this variety which perplexes the common mind, the eye of science 
 discerns a few unchangeable primary bodies, by whose reciprocal actions 
 and combinations, this marvellous diversity and rotation of existence, are 
 produced and maintained. These bodies having resisted every attempt to 
 resolve them into simpler forms of matter, are called undecompounded , and 
 must be regarded in the present state of our knowledge as experimental 
 elements . It is possible that the elements of nature are very dissimilar ; it 
 is probable that they are altogether unknown ; and that they are so recon- 
 dite, as for ever to elude the sagacity of human research. 
 
 The primary substances which can be subjected to measurement and 
 weight, are fifty-three in number. To these, some chemists add the im- 
 ponderable elements, — light, heat, electricity, and magnetism. But their 
 separate identity is not clearly ascertained. 
 
 Of the fifty-three ponderable principles, certainly three, possibly four, 
 require a distinct collocation from the marked peculiarity of their powders 
 and properties. These are named Chlorine, Oxygen, Iodine (and Fluo- 
 rine . J ) These bodies display a pre-eminent activity of combination, an 
 intense affinity for most of the other forty-nine bodies, which they corrode, 
 penetrate, and dissolve ; or, by uniting with them, so impair their cohesive 
 force, that they become friable, brittle, or soluble in water, however dense, 
 refractory, and insoluble they previously were. Such changes, for exam- 
 ple, are effected on platinum, gold, silver, and iron, by the agency of 
 chlorine, oxygen, or iodine. But the characteristic feature of these archeal 
 elements is this, that when a compound consisting of one of them, and 
 one of the other forty-nine more passive elements, is exposed to voltaic 
 electrization, the former is uniformly evolved at the positive or vitreo- 
 
 e ectric pole, while the latter appears at the negative or resino- electric 
 pole. 
 
V1 INTRODUCTION. 
 
 1 he singular strength of their attractions for the other simple forms of 
 matter, is also manifested by the production of heat and light, or the phe- 
 nomenon of combustion, at the instant of their mutual combination. But 
 t ns phenomenon is not characteristic ; for it is neither peculiar nor neces- 
 saiy to their action, and, therefore, cannot be made the basis of a logical 
 ai rangement. Combustion is vividly displayed in cases where none of 
 these primary dissolvents is concerned. Thus some metals combine with 
 others with such vehemence as to elicit light and heat ; and many of them, 
 by their union with sulphur, even in vacuo , exhibit intense combustion. 
 1 otassium burns distinctly in cyanogen (carburetted azote), and splendid- 
 ly in sulphuretted hydrogen. For other examples to the same purpose, 
 see Combustible and Combustion. 
 
 And again, the phenomenon of flame does not necessarily accompany any 
 of the actions of oxygen, chlorine, and iodine. Its production may be re- 
 gulated at the pleasure of the chemist, and occurs merely when the mutual 
 combination is rapidly effected. Thus chlorine or oxygen will unite with 
 hydrogen, either silently and darkly, or with fiery explosion, as the opera- 
 tor shall direct. 
 
 Since, therefore, the quality of exciting or sustaining combustion is not 
 peculiar to these vitreo-electric elements ; since it is not indispensable to 
 their action on other substances, but adventitious and occasional, we per- 
 ceive the inaccuracy of that classification which sets these three or four 
 bodies apart under the denomination of supporters of combustion ; as if, for- 
 sooth, combustion could not be supported without them, and as if the sup- 
 port of combustion was their indefeisible attribute, the essential concomi- 
 tant of their action. On the contrary, every change which they can pro- 
 duce, by their union with other elementary matter, may be effected without 
 the phenomenon of combustion. See section 5th of article Combustion. 
 
 The other forty-nine elementary bodies have, with the exception of 
 azote (the solitary incombustible), been grouped under the generic name 
 of combustibles. But in reality combustion is independent of the agency of 
 all these bodies, and therefore combustion may be produced without any com- 
 bustible, Can this absurdity form a basis of chemical classification? The 
 decomposition of euchlorine, as well as of the chloride and iodide of azote, 
 is accompanied with a tremendous energy of heat and light ; yet no com- 
 bustible is present. The same examples are fatal to the theoretical part of 
 Black’s celebrated doctrine of latent heat. His facts are, however, invalu- 
 able, and not to be controverted, though the hypothetical thread used to 
 connect them be finally severed. 
 
 To the term combustible is naturally attached the idea of the body so 
 named affording the heat and light. Of this position, it has been often 
 remarked, that we have no evidence whatever. We know*, on the other 
 hand, that oxygen, the incombustible, could yield, from its latent stores, in 
 Black’s language, both the light and heat displayed in combustion ; for mere 
 mechanical condensation of that gas, in a syringe, causes their disengage- 
 ment. A similar condensation of the combustible hydrogen, occasions, I 
 believe, the evolution of no light. From all these facts, it is plain, that 
 the above distinction is unphilosophical, and must be abandoned. In truth, 
 every insulated or simple body has such an appetency to combine, or is 
 solicited with such attractive energy by other forms of matter, whether the 
 actuating forces be electo-attractive, or electrical, that the motion of the 
 particles constituting the change, if sufficiently rapid, may always produce 
 the phenomenon of combustion. 
 
 Of the forty-nine resino-polar elements, forty-three are metallic, and six 
 non-metallic. 
 
 The latter group may be arranged into three pairs : — 
 
INTRODUCTION. 
 
 VII 
 
 1st, The gaseous bodies, Hydrogen and Azote ; 
 
 2d, The fixed and infusible solids, Carbon and Boron ; 
 
 3d, The fusible and volatile solids, Sulphur and Phosphorus. 
 
 The forty-three metallic bodies are distinguishable by their habitudes 
 with oxygen, into two great divisions, the Basifiable and Acidifiable 
 metals. The former are thirty-six in number, the latter seven. 
 
 Of the thirty-six metals, which yield by their union with oxygen sali- 
 fiable bases, three are convertible into alkalis, ten into eaitlis,^ and twenty- 
 three into ordinary metallic oxides. Some ol the latter, however, by a 
 maximum dose of oxygen, seem to graduate into the acidifiable group, ol 
 
 at least cease to form salifiable bases. 
 
 We shall now delineate a general chart of Chemistry, enumerating its 
 various leading objects in a somewhat tabular form, and pointing out then 
 most important relations, so that the readers of this Dictionary may have 
 it in their power to study its contents in a systematic order. 
 
 CHEMISTRY 
 
 Is the science which treats of the specific differences in the nature of 
 bodies, and the permanent changes of constitution to which their mutual 
 actions give rise.f 
 
 This diversity in the nature of bodies is derived either from the aggre- 
 gation or composition of their integrant particles. The state of aggre- 
 gation seems to depend on the relation between the cohesive attraction of 
 these integrant particles, and the antagonizing force of heat. Hence, the 
 three general forms of solid, liquid, and gaseous, under one or other of 
 which every species of material being may be classed. 
 
 For instruction on these general forms of matter, the student ought to 
 read, 1$£, The early part of the article Attraction ; 2d, Crystalliza- 
 tion ; 3d, That part of Caloric entitled, “ Of the change of state pro- 
 duced in bodies by caloric, independent of change of composition.” He 
 may then peruse the introductory part of the article Gas, and Balance, 
 and Laboratory. He will now be sufficiently prepared for the study of 
 the rest of the article Caloric, as well as that of its correlative subjects, 
 Temperature, Thermometer, Evaporation, Congelation, Cry- 
 ometer, Dew, and Climate. The order now prescribed will be found 
 convenient. In the article Caloric, there are a few discussions, which 
 the beginner may perhaps find somewhat difficult. These he may pass 
 over at the first reading, and resume their consideration in the sequel. 
 After Caloric he may peruse Light, and the first three sections of Elec- 
 tricity. 
 
 r lhe article Combustion, will be most advantageously examined, after he 
 has become acquainted with some of the diversities of Composition ; viz. 
 with the three vitreo-polar dissolvents, oxygen , chlorine, and iodine; and 
 the six non-metallic resino-polar elements, hydrogen, azote, carbon, 
 boron, sulphur, and phosphorus. Let him begin with oxygen , and then 
 peruse, lor the sake of connexion, hydrogen, and tvatcr. Should he wish 
 to know how the specific gravity of gaseous matter is ascertained, he may 
 consult the fourth section of the article Gas. 
 
 I he next subject to which he should direct his attention is Chlorine ; 
 on which he will meet with ample details in the present Work. This 
 
 I here regard silica acting as a base to fluoric acid, in the fluosilicic compound ; but the 
 subject is mysterious. See Acid (Fluoric). 
 
 f I do not know whether this definition be my own, or borrowed. I find it in the syl- 
 a us of my Belfast Lectures, printed many years ago. Another definition has been given 
 in the Dictionary, article Chemistry. 
 
Vlll 
 
 INTRODUCTION. 
 
 article will bear a second perusal. It describes a series of the most splen- 
 did efforts ever made by the sagacity of man, to unfold the mysteries of 
 nature. In connexion with it he may read the articles Chlorous and 
 Chloric Oxides, or the protoxide and deutoxide of Chlorine. Let him 
 next study the copious article Iodine, from beginning to end. 
 
 Carbon, boron, sulphur, phosphorus, and azote, must now come under 
 review. Related closely with the first, he will study the carbonous oxide , 
 carburetted and subcarburctted hydrogen . What is known of the element 
 boron will be speedily learned; and he may then enter on the examination 
 of sulphur , sulphuretted hydrogen , and carburet of sulphur. Phosphorus and 
 phosphuretted hydrogen , with nitrogen or azote, and its oxides and chlorides , 
 will form the conclusion of the first division of chemical study, which re- 
 lates to the elements of most general interest and activity. The general 
 articles Combustible , Combustion , and Safe-lamp may now be read with ad- 
 vantage ; as well as the remainder of the article Attraction, which treats of 
 affinity. 
 
 Since in the present work the alkaline and earthy salts are annexed to 
 their respective acids , it will be proper, before commencing the study of 
 the latter, to become acquainted with the alkaline and earthy bases. 
 
 The order of reading may therefore be the following: first, The gene- 
 ral article alkali , then potash and potassium , soda and sodium , litliia and 
 ammonia. Next, the general article earth ; afterwards calcium and lime, 
 barium and barytes , strontia, magnesia , alumina , silica, glucina } zirconia, 
 yttria, and thorina. 
 
 Let him now peruse the general articles acid and salt ; and then the non - 
 metallic oxygen acids, with their subjoined salts, in the following order: — 
 sulphuric , sulphurous , hyposulphurous and hyposulphuric ; phosphoric , phos- 
 phorous and hypophosphorous ; carbonic and chloro- carbonous ; boracic ; and 
 lastly, the nitric and nitrous. The others may be studied conveniently 
 with the hydrogen group. The order of perusing them may be, the mu- 
 riatic (hydrochloric of M. Gay Lussac), chloric and perchloric ; the hydri- 
 odic , iodic and chloriodic ; the fluoric , fluoboric , and fluosilicic ; the prussic 
 (hydro cyanic of M. Gay Lussac), ferroprussic, chloroprussic, and sulphur o- 
 prussic. The hydrosulphurous and hydrotellurous , are discussed in this Dic- 
 tionary, under the names of sulphuretted hydrogen , and telluretted hydrogen. 
 These compound bodies possess acid powers, as well perhaps as arsenuret- 
 ted hydrogen. It would be advisable to peruse the article prussine (cy- 
 anogen ) either before or immediately after prussic acid. 
 
 As to the vegetable and animal acids, they may be read either in 
 their alphabetical order, or in any other which the student or his teacher 
 shall think fit. Thirty-eight of them are enumerated in the sequel of the 
 article Acid ; of which two or three are of doubtful identity. 
 
 The metallic acids fall naturally under metallic chemistry; on the 6tudy 
 of which I have nothing to add to the remarks contained in the general 
 article Metal. Along with each metal in its alphabetical place, its na- 
 tive state, or ores , may be studied. See Ores. 
 
 The chemistry of organized matter may be methodically studied by 
 perusing, first of all, the article vegetable kingdom, with the various pro- 
 ducts of vegetation there enumerated ; and then the article animal king- 
 dom, with the subordinate animal products and adipocere. 
 
 The article analysis may be now consulted; then mineral waters; 
 equivalents {chemical) ; and analysis of ores. 
 
 The mineralogical department should be commenced with the general 
 articles mineralogy, and crystallography ; after which the different species 
 and varieties may be examined under their respective titles. The enume- 
 ration of the genera of M. Mohs, given in the first article, will guide the 
 
INTRODUCTION. 
 
 ix 
 
 student to a considerable extent in their methodical consideration. Be- 
 longing to mineralogy, are the subjects, blow-pipe, geology, with its subor- 
 dinate rocks , ores , and meteor olite. 
 
 The medical student may read with advantage, the articles, acid {arseni- 
 ous), antimony, bile, blood, calculus (urinary), the sequel of copper, digestion, 
 gall-stones , galvanism, intestinal concretion, lead, mercury, poisons, respira- 
 tion , urine , 8$c. . . 
 
 The agriculturist will find details not unworthy of his attention, under 
 
 the articles, absorbent, analysis of soils, carbonate , lime, manure, and soils. 
 
 Among the discussions interesting to manufacturers are, acetic and other 
 adds , alcohol, alum , ammonia , beer , bleaching, bread, caloric, coal, and coal- 
 gas, distillation , dyeing, ether, fat, fermentation, glass, ink, iron , oi es, potash, 
 pottery, salt, soap, soda, steel, sugar, tanning, fyc. 
 
 The general reader will find, it is hoped, instruction blended with enter- 
 tainment, in the articles, aerostation, air , climate, combustion, congelation, 
 dev:, electricity, equivalents, galvanism, geology , light, meteorolite, rain, and 
 several other articles formerly noticed. 
 
 It may be proper now to say something concerning the execution of the 
 present Work. In the month of June, a gentleman from London, who had 
 become possessed of the copy-right of Nicholson’s Dictionary, waited on 
 me in Glasgow, requesting that I would superintend the revision of a new 
 edition, which he purposed immediately to send to the press. I stated to 
 him, that, however valuable Nicholson’s compilation might have been at its 
 appearance in 1808, the science of chemistry had undergone such altera- 
 tions since, as would require a Dictionary to be written in a great measure 
 anew. To this he replied, that the above work had enjoyed great popu- 
 larity; that he was certain a new edition of it would be well received ; that 
 he did not expect me to compose original articles or dissertations, but 
 merely to add, from recent publications, such notices of new discoveries 
 and improvements as might seem proper, and to retrench what appeared 
 obsolete or useless, taking care to comprise the whole in such a compass 
 as would render its price moderate, and thus place the book within the 
 reach of manufacturers, medical students, and general readers. The terms 
 offered appearing reasonable relative to the work required, I entered into 
 an engagement to revise the new edition in time for the winter classes. 
 
 Having assembled complete series of all the British scientific journals, 
 with several of the foreign, and the various chemical compilations from 
 Newman and Macquer to the present day, I commenced the stipulated 
 revision. I had advanced a very little way, however, when I became 
 alarmed at the dilemma in which 1 found myself placed. A large propor- 
 tion of the articles which I had reckoned on reprinting, as having under- 
 gone little change since 1808, were found to have been quite obsolete at 
 that period. Ihey had been evidently copied, with scarcely any alteration, 
 through Nicholsons quarto Dictionary, from Macquer and Newman, back 
 I believe to the era of Stahl, Becher, and Agricola. Under the article 
 acid [acetic), 86 pages of Crell’s Annals had been copied verbatim et seriatim 
 on the concentration of vinegar by charcoal, &c. A larger space was al- 
 lotted to the separation of silver, under the articles silver, parting, and as- 
 say, than was dedicated to all the gases and earths. The article Caloric 
 was meagre and vapid, vrhile desulphur ation or roasting of pyrites, brazil 
 wood, and safflower, occupied a far greater extent. Putrefaction consist- 
 ed ol extracts from Becher’s subterranean world, and other details belong- 
 ing to a former age of chemistry. 
 
 1 he contents of the 8vo Dictionary were made up from four sources. 
 
 1st, hi om his quarto Dictionary of 179J. The long article Ores, for 
 
X 
 
 INTRODUCTION. 
 
 example, was taken chiefly from Cramer, while the labours of Klaproth 
 and Vauquelin were seldom noticed. Large excerpts were also given from 
 obsolete Dispensatories, concerning substances of no chemical importance, 
 and destitute of all medicinal power. 
 
 ^ 2d, From the contemporary systems of Brogniart, Henry, Murray, 
 Thomson, &c. about another fourth was copied in continuous articles. 
 1 his formed the best part of the whole. 
 
 3d, Large excerpts were given from his own Journal, quite dispropor- 
 tionate to the rest of the work, and to the exclusion of numerous interest- 
 ing topics. Indeed a journalist, who compiles a system, has great tempta- 
 tions to fall into this practice. 
 
 4th, The fourth portion was composed by himself. This seems to have 
 constituted about one-twentieth of the Dictionary, and related chiefly to 
 physics, in which he was experimentally versant. These articles were 
 very respectable, and have been in some measure retained ; see Attrac- 
 tion, Balance , Hydrometer , and Laboratory . What follows the first 
 
 asterisk in Attraction, has been now added. Mr Nicholson was indeed a 
 man of candour, intelligence, and ingenuity. His original papers on 
 electricity, and mechanical science, do him much honour ; and the ab- 
 stracts of experimental chemical memoirs, which he occasionally drew up 
 for his Journal, were ably executed. Had he bestowed corresponding 
 pains on his 8vo Dictionary, my present task would have been greatly 
 lighter. 
 
 After making such a survey, the feelings under which I began to labour 
 were similar to those of an architect, who having undertaken to repair a 
 building, within a certain period, by replacing a few unsightly or moulder- 
 ing stones, finds himself, on his first operations, overwhelmed in its rubbish. 
 Reverence to public opinion, and anxiety to fulfil my engagement, how- 
 ever irksome, have induced me to make every possible exertion to restore 
 the edifice, and renew the decayed parts with solid materials. If it has 
 not all the symmetry, or compactness, of an original design, leisurely exe- 
 cuted, still I trust it will prove not altogether unworthy the attention of 
 the chemical world. 1 have investigated the foundation of almost every 
 fact or statement which it contains, and believe they merit general confi- 
 dence. Many inaccurate positions and deductions, in our most elaborate 
 modern system, I have taken the liberty of pointing out ; aware that the 
 influence of Dr Thomson’s name and manner is capable of giving consider- 
 able currency to his opinions, however erroneous they may be. His in- 
 dustry deserves the highest praise ; and his chemical experience would 
 entitle his decisions to deference, were they less precipitate, and less dog- 
 matical. Many of my embarrassments in compiling the present volume, 
 have arisen from his contradictory judgments, pronounced in the Annals 
 of Philosophy; see Acids Phosphoric, Prussic, &c. If under the in- 
 fluence of the feelings thus excited, a hasty expression has escaped me in 
 the ardour of composition, I hope it will not be imputed to personal ani- 
 mosity. I have always lived on amicable terms with this distinguished 
 chemist, and trust to continue so to do. Perhaps in commenting on his 
 opinions, I may have unconsciously caught the plain manner of his criti- 
 cisms. My sole object, however, was the establishment of truth. The 
 refutation of error was undertaken, only when its existence seemed in- 
 compatible with that object. On our other valuable systematic works, I 
 have made no critique, because Dr Fhomson’s is the most comprehensive, 
 professedly taken from original memoirs, and of highest authority. 
 
 I have long meditated to publish a method 
 which both its study and practice would l: 
 applications to the phenomena of nature, me 
 
 lical treatise on cnemistry, in 
 >e greatly simplified, and its 
 dicine, and the arts, faithfully 
 
INTRODUCTION. 
 
 XI 
 
 .Wailed In mv memoir on sulphuric acid, inserted in the Journal of 
 Science "and the Arts, for October 1817, is the following passage : I was 
 
 fed to examine the subject very minutely, in prepanng for publication a 
 general system of chemical instructions, to enable apothecaries, manu ac- 
 f ur i ng chemists, and dealers, to practise analysis with accuracy and des- 
 patch as far as their respective arts and callings require. I hope that 
 this work will soon appear. Meanwhile, the following details will afford a 
 specimen of the experimental researches executed with this view. I le 
 three years and a half which have elapsed since the above paper was com- 
 posed, would have enabled me to fulfil the promise, but for various un- 
 
 foreseen interruptions to my labours. . . . n 
 
 If the public, after this larger specimen of my chemical studies, shall deem 
 
 me qualified for the task, I may promise its completion within a year from 
 this date. The work will be comprised in four octavo volumes, and will con- 
 tain the results of numerous investigations into the various objects of prac- 
 tical chemistry, joined to a systematic view of its principles. By several 
 simple instruments, tables, and rules of calculation, chemical analysis, the 
 highest and most intricate part of the science, may, I apprehend, be, in 
 many cases, brought within the reach of the busy manufacture! ; while, by 
 the same means, such accuracy and despatch may be ensured, as to render 
 the analysis of saline mixtures, complex minerals, and mineral waters, the 
 work of an hour or two ; the proportions of the constituents being deter- 
 mined, to one part in the thousand. 
 
 In prosecution of this plan of simplifying analysis, I contrived, about 
 five years ago, an alkalimeter and acidimeter. Being then connected by 
 a biennial engagement with the Belfast Academical Institution, I was oc- 
 casionally called upon to examine the barillas and potashes so extensively 
 employed in the linen manufacture, the staple trade of Ireland. I was 
 sorry to observe, that while these materials of bleaching differed exces- 
 sively in their qualities, no means was possessed by those who imported or 
 who used them, of ascertaining their value ; and that a generous people, 
 with whom every stranger becomes a friend, frequently pa*id an exorbitant 
 price for adulterated articles. The method which I devised for analyzing 
 alkaline and acid matter, was laid before the Honourable Linen Board in 
 Dublin, and by them referred to a competent chemical tribunal. The 
 most decisive testimonies of its accuracy and importance were given by 
 that tribunal ; and it was finally submitted, by desire of the Board, to a 
 public meeting of bleachers assembled at Belfast. Unexceptionable docu- 
 ments of its practicability and value were thence returned to Dublin, 
 accompanied by an official request, that measures might immediately be 
 taken to introduce the method into general use. Descroizilles had seve- 
 ral years before described, in the Annales de Chimie, an alkalimeter, but so 
 clumsy, operose, and indirect, as to be not at all adapted to the purposes 
 of the linen manufacture. My instrument, indeed, was founded, as well 
 as his, on the old principle of neutralizing alkali with acid ; but in every 
 other respect it was different. 
 
 After spending about two months on this project, and no answer being 
 returned either to the public request of the bleachers, or to my own me- 
 monal, I set off on an intended tour to France, and have never since re- 
 sumed the negotiation.*' The terms on which I had offered the instru- 
 ment, wore merely honorary ; for the sum proposed, would not have re- 
 paid the expense of my journey and attendance. However important there- 
 
 I he Right Hon. John Foster, who look the chief direction of the Board, shewed me 
 
 3 * e attent,on ; b "t from the absence of many of its members in England, a quo- 
 rum could not be assembled at the time. 
 
Xl * INTRODUCTION. 
 
 fore the adoption of that instrument was to Ireland, it was of no pecuniary 
 importance whatever to me. Of the two hundred and ten thousand pounds 
 expended that year (1815-1816) on imported alkalis, a very large pro- 
 portion might have been saved by the application of my alkalimeter ; and 
 what is perhaps of more consequence, the alkaline leys used in bleaching, 
 would, by its means, have been rendered of a regulated strength, suited to 
 the stage of the process, and fabric of the cloth. What would we say of 
 a company, who imported spirituous liquors to an enormous amount, and 
 paid for them all as proof, though they were diluted with fifty per cent of 
 water? Now, though this neglect of the hydrometer would have a happy 
 moral influence on the consumer, it would be vastly absurd in the dealer. 
 No such apology can be offered for neglecting the alkalimeter. 
 
 The following is an extract from the Belfast News-Letter of July 9. 
 1816:— ; 
 
 “ I now submit the following document to public inspection, and hum- 
 bly ask, whether any such experiment has been ever made publicly be- 
 fore ; or whether there is described in any publication prior to my late 
 exhibition in Dublin, and in the Linen Hall of Belfast, an instrument by 
 which it can be performed? 
 
 “ This day, one of the porters of the Linen Hall, Belfast, was called 
 into the Library-room, at the request of Dr Ure, who, being quite un- 
 known to Dr Ure, and never having seen any experiments made with 
 acids and alkalis, he took the instrument at our desire, which, being 
 filled with coloured acid, by pouring it slowly on adulterated alkali, which 
 we had previously prepared, he ascertained exactly the per centage of 
 genuine alkali, in the mixture. — Belfast , 25th June 1816. 
 
 (Signed) John S. Ferguson, Chairman . 
 
 James M‘Donnel, M. D. 
 
 John M. Stoupe, 
 
 S. Thomson, M . Z). 
 
 44 The above experiment did not occupy the porter above five minutes. 
 I believe it is a new document, though, after the egg has been placed on 
 end, others will set to work to do the same. 
 
 44 Though the instrument was entirely the result of my own experiments 
 and calculations, I never claimed a greater share in its invention, than I 
 hope its peculiarity merits. The following excerpt from a letter addressed 
 to the Right Hon. John Foster, prior to any public discussion on its me- 
 rits, will satisfy the public on this head. 
 
 44 Dublin , June 12. 1816. 
 
 44 Sir, — In the letter which I had yesterday the honour of addressing 
 you, I omitted some scientific details, which I now beg leave to submit to 
 your consideration. That the quantity of alkali, present in any portion of 
 potash or barilla, is directly proportional to the quantity of acid requisite 
 to produce saturation, is a fact which has been known for upwards of a 
 century to every chemist, and forms a fundamental law of his science. In 
 establishing my instrument on this law, the principle ol it may be said not 
 to be new,” &c, 
 
 44 The practical application of the established laws of nature, or of the 
 general deductions of science, to the uses of life, is, perhaps, the most 
 beneficial and meritorious employment of the philosophic mind. Ihe 
 novelty which I lay claim to in my contrivance, is this, that it enables a 
 person versant neither in chemical researches nor in arithmetical computa- 
 tion , to determine by inspection of a scale, as simple as that of a thermo- 
 meter, the purity or value to one part in the hundred, of the alkalis, oil of 
 vitriol, and oxymuriate of lime, so extensively, and often so injudiciously 
 employed by the linen-bleacher.” 
 
INTRODUCTION. 
 
 • • • 
 Xlll 
 
 In my journey through England to France, I submitted my Essay on 
 Alkalimetry, &c. to Dr Henry, in the confidence ol friendship, and under 
 the injunction of secrecy. From the unreserved communication of ideas, 
 however which subsists between this chemist and Ins townsman Mr Dal- 
 ton he soon gave him a perusal of the Essay. In the then existing edi- 
 tion of Dr Henry’s Elements, Dcscroizilles’ plan tor testing alkalis was 
 alone given ; in the edition published since, be has inserted four supple- 
 mentary pages entitled, . ,, 
 
 “ Improved Alkalimeter and Acidinieter . 
 
 This instrument is essentially mine, very slightly disguised. He concludes 
 by saying, “ No chemical operation can be more simple, or more easily 
 managed, than the measurement of the strength of alkalis by acid liquors, 
 and of acids by alkaline ones, in the way which has been described This 
 is exactly Columbus’s egg, or Roger Bacon’s gunpowder; et sic facies 
 tonitru , si scias artificium. By comparing his new way taken from 
 my Essay, with the methods which he formerly gave, the world will see 
 whence the simplification originated. I offered to give him an abridged 
 account of my plan, for insertion in his Elements, after my negociation 
 about the alkalimeter was finished. Without consulting me on the sub- 
 ject, he publishes to the whole world, what he conceives to be the essence 
 of my improvement. 
 
 Two motives have hitherto withheld me from laying the instrument 
 before the public. First, a desire to render it as complete as possible ; 
 and secondly, an expectation, that the Honourable Board, who superin- 
 tend the linen manufactures of Ireland with extensive powers, might wish 
 that an instrument originally presented to them, and which is capable of 
 giving light and precision to all the processes of bleaching, should appear 
 under their auspices. 
 
 As it now exists, the instrument is greatly superior to that described by 
 Dr Henry. For the commercial alkalis and acids, I use only two test 
 liquids and one scale ; and these are such, that a man unacquainted with 
 science, may prepare the first, and verify the second. The instrument is 
 at once an alkalimeter, an acidimeter, a complete lactometer, a nitrometer 
 for estimating the value of nitre, an indigometer for ascertaining the dyeing 
 quality of indigo, and a blanchimeter for measuring the bleaching power 
 of oxymuriate (chloride) of lime and potash. With it, a busy manufac- 
 turer or illiterate workman, may solve all these useful problems in a few 
 minutes ; and many others, such as the composition of alloys of silver, 
 of copper, tin, lead, &c. the purity of white lead, and other pigments. It 
 is, moreover, a convenient hydrometer, comprehending in its range, light 
 and heavy liquids, from ether to oil of vitriol ; and is particularly adapted 
 to take the specific gravity of soils. 
 
 It may be said, that the solution of the above problems may be accom- 
 plished by any skilful chemist. But surely, in a manufacturing nation, 
 the person who brings the science of Klaproth, Sir H. Davy, Dr Wollas- 
 ton, and M. Cray Lussac, into the workshop of the manufacturer, is not a 
 useless member of the community. 
 
 The result of numerous researches made with that view, has shewn me 
 the possibility of rendering analysis in general, a much easier, quicker, 
 and more certain operation, than it seems hitherto to have been, in ordi- 
 nary hands, lo these practical applications of science, my attention has 
 been particularly directed, in conducting that department of Anderson’s 
 Institution, destined to diffuse among the manufacturers and mechanics 
 ol Glasgow and its neighbourhood, a knowledge of the scientific principles 
 oi their respective arts. In a public address, delivered to the members of 
 Hus class, on a gratifying occasion in April 18 IG, I remarked, “ That 
 
XIV 
 
 INTRODUCTION. 
 
 Europe affords no similar example of a class composed of several hun- 
 dred artisans, mechanicians, and engineers, weekly assembled,* with 
 exemplary decorum, to study the scientific principles of the usef ul arts ; 
 to have the great practical truths of philosophy, first revealed by Newton 
 and Lavoisier, made level to their various capacities by familiar descrip- 
 tions, models, and experiments. The original design of the mechanic’s 
 class was limited, as you know, to the exhibition and explanation of me- 
 chanical models. But a subject deserving particular attention, was that 
 of the chemical arts, in which many of you are engaged ; a knowledge of 
 the scientific principles of which, as taught in the Colleges, circumstances 
 permit few of you to acquire. You have listened to my chemical lessons 
 with the keenest interest ; and have applied your studies to conspicuous 
 advantage. Need I adduce, among other things, the unrivalled beauty of 
 the Adrianople madder dye, as executed on the most extensive scale, f by 
 individuals who have been my faithful pupils, for nearly the whole course 
 of my public career. By a steady prosecution of this expanded system of 
 instruction, your class has progressively increased in number and impor- 
 tance ; so that, within the last twelve years, I have delivered twenty-one 
 courses of lectures to upwards of six thousand students in this department 
 alone.” 
 
 It is much to be desired, that similar courses of prelections were insti- 
 tuted in all the large towns of the British empire. The deportment of 
 the mechanic’s class, amounting occasionally to five hundred members, 
 might serve as a pattern to more dignified assemblies. 1 have never seen 
 any University class so silent and attentive. Though the evening on which 
 the workmen meet, be that in which they receive their wages, and when, 
 therefore, they might be expected to indulge themselves in drinking, yet 
 no instance of intemperance has ever occurred to annoy the audience. 
 And even during the alarms of insurrection with which our city was dis- 
 turbed last winter, the artisans continued with unaltered docility and 
 punctuality to frequent the lectures. 
 
 Of the actual result of such a system of instruction, a stranger is pro- 
 bably the best judge. I shall therefore quote a few sentences from the 
 Scientific Tour through Great Britain, recently published by an accom- 
 plished member of the Institute of France, M. Ch. Dupin. 
 
 “ It is easier to visit the establishments and manufactures of Glasgow, 
 than those of any other city in the British empire. The liberal spirit of 
 the inhabitants, is, in this respect, carried as far as possible, among a 
 manufacturing people, who must naturally dread, and seek to prevent, 
 not only the loss of their preponderance, but their foreign rivalry. 
 
 “ The rich inhabitants of Glasgow, have founded the Andersonian In- 
 stitution, where are taught, in the evenings of winter, the elements of 
 mechanics, physics, and chemistry, as applied to the arts. I hose couises 
 are especially designed for young artisans, who have to pay only about 
 five shillings in the season (course of three months"). 
 
 c< r pbis trifling fee is exacted, in order that the class may include 
 only students actuated by the love of instruction, and willing to make 
 
 some small sacrifice for it. . . 
 
 « The Andersonian Institution has produced astonishing effects. It is 
 an admirable thing now, to see in many Glasgow manufactories, simple 
 workmen, who understand, and explain when necessary, the piinciples of 
 
 * Every Saturday evening at eight o’clock. 
 
 -f- Particularly at the establishment ot II. Montcith, Esq, 
 mechanics and chemistry co-operate, in a degree ot precision 
 to be unparalleled in the world. 
 
 , INI. P. where the sciences of 
 and elegance, which I believe 
 
INTRODUCTION. 
 
 xv 
 
 their operations, and the theoretical means of arriving at the most perfect 
 possible practical results.” 
 
 The philanthropist may perhaps wish to know, at what expense, of 
 patronage this useful department is carried on. I shall satisfy this desire, 
 by the following statement from the above mentioned public address. 
 
 J tt Xh e original design of the mechanic’s class, was limited, as you know, 
 to the exhibition and explanation of mechanical models. Rut the pro- 
 gress of machinery in your workshops, has now so far outrun the state of 
 the models left by the venerable Founder of the Institution, as to render 
 their display, with a very few exceptions, useless, except as historical 
 documents of the rudeness of the times in which they were framed. I 
 have, accordingly, for ten years, employed chiefly modern apparatus, pro- 
 cured at my own expense, and by rendering the instructions miscella- 
 neous, have adapted them better to the diversity of your pursuits. Be- 
 sides teaching the usual elements of mechanics and their general combi- 
 nations, I have made it my business to explain the properties of the at- 
 mosphere, on which the action of pumps depends ; the nature of hydro- 
 static equilibrium, and hydraulic impulse, as subservient to the construc- 
 tion of Bramah’s press, and water-wheels; the beautiful laws of heat so 
 admirably applied to perfect the steam-engine, by our illustrious fellow- 
 citizen ; nor have I declined, in compliance with your wishes, to lay be- 
 fore you from time to time, such views of the constitution of nature, in 
 electricity, optics, and astronomy, as might awaken the powers of your 
 minds, and reward your attention to the less attractive branches of 
 science. But a subject deserving particular attention, was that of the 
 chemical arts,” &c. (as above quoted). 
 
 The whole experimental means at present employed in carrying on this 
 Polytechnic School, have been derived from the exertions and sacri- 
 fices of the Professor, and the generous aid and contributions of his pupils. 
 They have supplied him with much valuable practical information on 
 their respective arts, with many curious models, and subsidiary instruments 
 of illustration ; while he, in return, has expended large sums of money, 
 in framing popular representations of the scientific discoveries and im- 
 provements, in which the present age is so prolific. 
 
 Io the mechanic’s class a library is attached, consisting of the best 
 treatises on the sciences and arts, with some valuable works on general 
 literature, such as, history, geography, travels, &c. of which they have the 
 exclusivejnanagement and perusal. The foundation of it was laid in the 
 year 1807, by a voluntary subscription, amounting, I think, to about 
 L.60 ; and several books which I collected from my friends, with about 
 100 volumes from my own library. Many members of the class have 
 contributed from time to time; and it has recently acquired conside- 
 rable extension, from the receipts of lectures which I delivered for its 
 benefit. 
 
 Besides the acknowledged and palpable effect of such a plan of tuition, 
 on the improvement of the useful arts, it has another operation, more 
 silent, but neither less certain, nor less important, namely, its influence 
 m meliorating the moral condition of the operative order of society. 
 
 i taste for science elevates the character, and creates a disrelish, and 
 ( isgust, at the debasement of intoxication. Philosophy dressed in an at- 
 t! acti ve garb, leads away from the temptations of the tavern. Thus, too, the 
 
XVI 
 
 INTRODUCTION. 
 
 ration of science, I have always taken occasion to point out the beneficent 
 design which the whole mechanism of nature displays. If the contemplation 
 of the miseries and crimes which stain the page of history, have led some 
 speculators to cavil at the government of a benevolent Creator ; the con- 
 templation of the harmonious laws, and benignant adjustments which the 
 science of nature discloses, must satisfy every candid student, of the pre- 
 sence and providence of a wise and beneficent Lawgiver. The first and 
 most exalted function of physics, then, is to dissipate the gloomy and be- 
 wildering mists of metaphysics. A second function of supreme importance, 
 is to point out the mysterious and impassable barriers to which the clearest 
 paths of physical demonstration ultimately lead the human mind; and thence 
 to inculcate docility, to the analogous mysteries of Revelation. 
 
 I hope that the preceding statements and remarks, will remove every 
 possible objection to the establishment of schools for teaching the elements 
 of science to artisans, and that they will induce other cities to follow the 
 example so happily set by Glasgow, of popularizing philosophy. 
 
 Having detailed the circumstances under which I have struggled to re- 
 generate this Dictionary, I hope the candid Public will make allowance for 
 occasional faults of expression and arrangement. All the articles to which 
 the asterisks are affixed, were, with trifling exceptions, printed from my 
 manuscript, written expressly for this work, within the last five months. 
 From the style of its typography, and the manner of stating proportions of 
 constituents, each page of this volume, is fully equivalent to two pages of 
 our octavo systems of Chemistry, and required rather more than four pages 
 of closely written manuscript. There is however a great advantage to the 
 reader of a scientific work, (which must necessarily be compiled from many 
 quarters), in an author being his own amanuensis. Every fact and detail 
 will thus be exposed to a much severer scrutiny, than if excerpts were 
 made by the scissars, or the pen of an assistant. Hence many of the pas- 
 sages which may seem, at first sight, to be merely copied from other works, 
 w iH be found to have corrections and remarks either interwoven with the 
 details, or enclosed in parentheses. Thus, for example, in transcribing Mr 
 Hatchett’s admirable analyses of the magnetic iron ores, computations will 
 be found within parentheses, deduced from Dr Wollaston’s equivalent scale. 
 Numerous insertions and corrections are made in the reprinted parts to 
 which no asterisk is affixed. M. Vauquelin’s general mode of analyzing 
 minerals is now introduced, Professor Gahn’s instructions relative to the 
 blow-pipe, a long passage under Arsenious Acid , and many other unnoted 
 insertions, such as Chlorophyle, Cholesterine, Comptonite . 
 
 The dissertations on Caloric , Combustion , Dew, Distillation , electricity , 
 Gas Light, Thermometer , tyc. which form a large proportion of the volume, 
 are ’beyond the letter and spirit of my engagement with the publisher. 
 I receive no remuneration for them, not even at the most model ate iatt of 
 literary labour. They are therefore voluntary contributions to the che- 
 mical student, and have been substituted for what I deemed frivolous and 
 uninteresting details on some unimportant dye-stuffs, and articles from old 
 
 dispensatories, such as althea, chamomile, &c. . 
 
 For whatever is valuable in the mineralogical department, the reader is 
 ultimately indebted to Professor Jameson. The chief part of the descrip- 
 tions of mineral species, is abridged from the third edition of his excel- 
 lent System. In compiling the early part ot the Dictionary, I collated 
 several mineralogical works, both British and foreign ; but I soon found 
 that this had been done to my hand by Professor Jameson with much 
 greater ability than I could pretend to rival ; and that he had enriched 
 the whole with many important remarks of his own. 
 
INTRODUCTION. 
 
 XVII 
 
 Much of the purely chemical part is drawn from that treasure of facts, 
 Sir H. Davy’s Elements. When the subject permitted me, I was happy 
 to repose on his never-failing precision, like the wave-tossed mariner in a 
 secure haven. With regard to the language used by him, Dr Wollaston, 
 M. Gay Lussac, and some other original investigators, I have used no 
 further freedom than was necessary to accommodate it to the context. 
 Their expressions can very seldom be changed with impunity. There are 
 other chemical writers again, whose thoughts acquire intellectual spring 
 only by great condensation. If the curious reader compare the article 
 Distillation, in this Dictionary, with that in the Supplement to the 
 Encyclopaedia Britannica, he will understand my meaning. 
 
 In the discussion on the Atomic Theory of Chemistry, under the 
 article Equivalents, reference is made to a table of the relative weights 
 of the atoms, or of the numbers representing the prime equivalents of 
 chemical bodies. On subsequent consideration, it was perceived, that 
 such a list would be merely a repetition of numbers already given in their 
 alphabetical places, and therefore most readily found ; whilst it would 
 have caused the omission of requisite tables of a different kind ; the space 
 allotted to the volume being entirely occupied. 
 
 In my paper on Sulphuric Acid, published in the 7th number of the 
 Journal of Science, I assigned the numbers 4, 5, 6, as respectively denot- 
 ing the prime equivalents of soda, sulphuric acid., and potash. Minute 
 researches, subsequently made, on the nitrates, (Journal of Science, No. 
 xii.) led me to regard 3.96, and 5.96, as better approximations for soda 
 and potash. Throughout this Dictionary, the numbers 3.95 and 5.95 
 have been used. It is, however, very possible that the number 6, origi- 
 nally assigned by Sir H. Davy for potash, may be correct ; as also 4 for 
 soda. 
 
 Dr Thomson has just published a paper in his Annals, (November 
 1820), “ On the true weight of the atoms of barytes, potash, soda,” &c. 
 In his experiments to determine these fundamental quantities, he has 
 adopted Richter’s original plan of reciprocal saturation of two neutro-saline 
 compounds. But the Doctor seems to have forgotten, that for want of 
 an initial experiment, none of his ratios is referable to the oxygen scale, 
 or to any atomic radix. He assumes the atom of barytes to be 9.75, and 
 that of potash to be 6 ; that of sulphuric acid being 5. He then proceeds 
 to shew that the atomic weight 13.25 of dry muriate of barytes (chloride 
 of barium), and 11, that of sulphate of potash, produce perfect reciprocal 
 decomposition, when their aqueous solutions are mixed. But had he 
 called the atom of barytes 9.7, with Sir H. Davy and Dr Wollaston, (the 
 chloride would become 13.2), and the atom of sulphate of potash 10.96, 
 as found in my experiments on nitric acid, he would have obtained, by 
 mixing the two, in these atomic proportions, as perfect an experimental 
 result as with his own numbers : For 13.25 : 1 1 : : 13.2 : : 10.96. 
 
 His atomic chain wants, in fact, its first link ; it floats'loosely ; and mav 
 therefore be accommodated to a variety of different numbers, provided the 
 arithmetical proportions be observed. He ought to have commenced with 
 a clear demonstration, that the atom of barytes is 9.7 5, and the atom of 
 potash 6, referred to oxygen as unity. 
 
 k?^ ever > suggested by Dr Prout, that the numbers repre- 
 
 b^r nf tf T ,g u S °i different atoms > multiples by a Me num- 
 , \ .1 hj , t de,10tln g hydrogen, is very ingenious, and most probably just. 
 
 demilfi M aS „ We aS f 0r experimental reasons, which I cannot here 
 
 and 4 ler U W ‘" lngl £, ad0 P t 9 : 75 *' or bar y tes - ^ for soda, 6 for potash, 
 a ul 4.5 for chlorine. 1 he atomic numbers given in this volume, for the 
 
 4**1 * 
 
xvffi 
 
 INTRODUCTION. 
 
 various simple and compound objects of chemistry, are directly deduced 
 irom a mean of the most exact experiments ; and I believe them to be more 
 worthy of confidence, than those deducible from theoretic considerations. 
 I bus, Dr lliomson, from these, assigns 3.625 for the atom of lime; from 
 experiment, it is certainly not so high. I have stated it from my own, at 
 3.5b. Dr Marcet’s analysis of the carbonate, would make it about 3.5. 
 n t ie ai tide Equivalents (Chemical), as well as under the individual 
 substances, the reader will find the primitive combining ratios, or atoms 
 as they aie hypothetically called, fully, and I trust fairly, investigated 
 from experiment. Ibis is the sheet-anchor of scientific research, which 
 we must never part with, or we shall drift into interminable intricacies. 
 We should continually bear in mind this aphorism of the master of Che- 
 mical Logic : 44 The substitution of analogy for fact is the bane of chemi- 
 cal philosophy; the legitimate use of analogy is to connect facts together, 
 and to guide to new experiments.”— Sir H. Davy, Journal of Science, 
 vol. i. 
 
 These analogical substitutions appear to be the predominant defect of 
 Dr Thomson’s otherwise valuable compilation. 
 
 The typographical economy of this work, precluded me from multiply- 
 ing references at the bottom of the page ; a plan which authors readily 
 adopt to shew the extent of their reading. The authorities for facts will 
 be generally found interwoven with the text. The desire to condense 
 much practical information, in a small compass, made me abridge many 
 historical details. The progressive steps of an investigation, however, 
 occasionally require to be traced, in order to make the existing state of 
 our knowledge more intelligible. Whenever this seemed necessary, I 
 have offered such a retrospect, and have endeavoured to take truth and 
 justice for my sole guides. As the only recompense which the man of 
 science usually receives or can expect, is the credit of his discoveries, 
 neither prejudice nor passion should be suffered to influence the compiler, 
 in awarding honour to whom honour is due. 
 
 One of the most elegant investigations which the Science of Chemistry 
 affords, is contained in M. Gay Lussac’s short letter to M. Clement, pub- 
 lished in the Annales de Chimie et de Physique for July 1815, and reprint- 
 ed in 1816, by M. Thenard in his valuable Traite de Chimie, iv. p. 238. 
 It is there demonstrated that sulphuric ether is composed of 
 
 2 volumes olefiant gas, 
 
 1 volume vapour of water, 
 
 condensed into one volume; or by weight in M. Gay Lussac’s numbers, of 
 
 0.978 X 2 = 1.956 olefiant gas, and 
 
 0.625 X 1 — 0.625 vapour of water, 
 
 . \ 
 
 2.581 sum theoretic density of vapour, 
 which differs from 2.586, the experimental density of ether vapour by only 
 f jL__ p ar ts. This fine coincidence is fully developed by the French Che- 
 mist. Now Dr Thomson was obviously familiar with that paper, for he 
 copies a good part of it, (though without acknowledgment), on the con- 
 stitution of alcohol, into his articles Brewing and Distillation, Supplement 
 to Encyclopaedia Britan ., as well as into his System published in October 
 1817, vol. iv. p. 385. See Fermentation in this Dictionary. 
 
 I was therefore equally surprised and amused at the following claim, 
 recently set up by him to M. Gay Lussac’s incontestable discovery. 
 
 44 The experiments which Mr Dalton has made on the analysis of ether, 
 shew in a very satisfactory manner, that the notion which I threw out in 
 my System of Chemistry, that sulphuric ether is a compound of two atoms 
 
INTRODUCTION. 
 
 xix 
 
 olefiant gas, and one atom vapour of water condensed into one volume, is 
 the true one.” “ Hence 2 volumes olefiant gas weigh 1.94-16 
 
 1 volume vapour of water 0.6250 
 
 **“*~*™ ■» 
 
 Total 2.5666 
 
 Specific gravity of ether vapour 2.5860.” — Annals of Philosophy , August 
 1820, p. 81. Historical Sketch , fyc. by Thomas Thomson , M D. fyc. 
 
 Now, though in that Sketch the Doctor seems to shew, that Mr Dalton 
 was unacquainted with M. Gay Lussac’s researches on ether, it was a 
 rather rash presumption to extend that analogy of ignorance to all other 
 British Chemists. The first of the Doctor’s periods, quoted above, is non- 
 sense, from his use of the favourite word atom , instead of volume , The 
 statement in the second is taken from M, Gay Lussac, and bears the ele- 
 gant impression of its author. 
 
 A few errors of the Press, which are marked at the end of the volume, 
 should be corrected by the reader, before commencing its perusal. Their 
 number will not be thought considerable, when it is stated, that the new 
 part of the work was printed from a rapidly written scroll ; and that each 
 proof-sheet was regularly returned to the printer in course of post, which 
 sometimes afforded me an interval of only four hours. Had less new 
 matter been introduced, these errata would have disappeared. 
 
 Glasgow, 
 November 7 . 1 820 . 
 
N.B. — The Articles with the asterisk (*), are inserted 
 by Dr Ure; the others, with the exceptions noticed in 
 the Introduction, are reprinted from Nicholson’s Octavo 
 Dictionary. 
 
A 
 
 DICTIONARY 
 
 OF 
 
 CHEMISTRY. 
 
 \ 
 
 ABS ABS 
 
 * /\ BSORBENT. An epithet introduced 
 into chemistry by the physicians, to de- 
 signate such earthy substances, as seemed to 
 check diarrhoea, by the mere absorption of the 
 redundant liquids. In this sense it is obso- 
 lete and unfounded. Professor Leslie has 
 shewn that the faculty of withdrawing mois- 
 ture from the air, is not confined to substan- 
 ces which unite with water in every propor- 
 tion, as the strong acids, dry alkalis, alka- 
 line earths, and deliquescent salts, but is pos- 
 sessed by insoluble and apparently inert bo- 
 dies, in various degrees of force. Hence the 
 term Absorbent merits a place in chemical 
 nomenclature. 
 
 I he substance whose absorbent power is 
 to be examined, after thorough desiccation 
 before a fire, is to be immediately transferred 
 into a phial, furnished with a well ground 
 stopper. When it is cooled, a portion of it 
 is transferred into a large wide-mouthed 
 bottle, where it is to be closely confined for 
 some time. A delicate hygrometer being 
 then introduced, indicates on its scale the 
 dryness produced in the inclosed air, which 
 should have been previously brought to the 
 point of extreme humidity, by suspending a 
 moistened rag within the bottle. The fol- 
 lowing table exhibits the results of his expe- 
 riments : — 
 
 Alumina causes a dryness of 
 
 84 degrees. 
 
 Carbonate of magnesia 
 
 75 
 
 Carbonate of lime 
 
 70 
 
 Silica - 
 
 40 
 
 Carbonate of barytes 
 
 32 
 
 Carbonate of strontites 
 
 23 
 
 Pipe clay - 
 
 85 
 
 Greenstone, or trap in powder, 80 
 
 ohelly sea sand 
 
 70 
 
 Clay indurated by torrcfaction 35 degrees. 
 
 Ditto strongly ignited - 8 
 
 Greenstone ignited - 23 
 
 Quartz do. - - 19 
 
 Decomposed greenstone - 86 
 
 Greenstone resolved into soil 92 
 
 Garden mould - - 95 
 
 The more a soil is comminuted by labour 
 and vegetation, the greater is its absorbent 
 power. This ingenious philosopher infers, 
 that the fertility of soils depends chiefly on 
 their disposition to imbibe moisture ; and 
 illustrates this idea by recent and by dis- 
 integrated lava. May not the finely di- 
 vided state most penetrable by the delicate 
 fibres of plants, derive its superior power of 
 acting on atmospherical vapour from the 
 augmentation of its surface, or the multipli- 
 cation of the points of contact ? 
 
 In similar circumstances 100 gr. of the 
 following organic substances absorb the fol- 
 lowing quantities of moisture : Ivory 7 gr. 
 boxwood 14, down 16, wool 18, beech 28. — 
 Leslie on Heat and Moisture .* 
 
 • Absorption. By this term chemists un- 
 derstand the conversion of a gaseous fluid 
 into a liquid or solid, on being united with 
 some other substance. It differs from con- 
 densation in this being the effect of mecha- 
 nical pressure, or the abstraction of caloric. 
 Thus, if muriatic acid gas be introduced into 
 water, it is absorbed, and muriatic acid is 
 formed ; if carbonic acid gas and ammonia- 
 cal gas be brought into contact, absorption 
 takes place, and solid carbonate of ammonia 
 is produced by the union of their ponderable 
 bases. 
 
 There is a case of condensation, which 
 has sometimes no doubt been mistaken for 
 
 A 
 
ACH 
 
 ACI 
 
 absorption, though none has taken place. 
 ^ hen an inverted jar containing a gas con- 
 fined by quicksilver is removed into a trough 
 of water, the quicksilver runs out, and is re- 
 placed by water. But as tho specific gravity 
 of water is so much inferior to that of quick- 
 silver, the column of water in the jar resists 
 the atmospheric pressure only with one 1 4 th of 
 the power of the quicksilver, so that the gas 
 occupies less room from being condensed by 
 the increased pressure, not from absorption. 
 
 Abstraction. In the process of distilla- 
 tion, the volatile products which come over, 
 and are condensed in the receivers, are some- 
 times said to be abstracted from the more 
 fixed part which remains behind. This term 
 is chiefly used when an acid or other fluid is 
 repeatedly poured upon any substance in a 
 retort, and distilled off, with a view to change 
 the state or composition of either. See Dis- 
 tillation. 
 
 * Acanticone. See Pistacite.* 
 
 * Acerates. The acer compestre, or 
 common maple, yields a milky sweetish sap, 
 containing a salt with basis of lime, possessed, 
 according to Scherer, of peculiar properties. 
 It is white, semi-transparent, not altered by 
 the air, and soluble in nearly 100 parts of 
 cold, or 50 of boiling water. * 
 
 * Aceric Acid. See Acid (Aceric).* 
 
 * Acescent. Said of substances which 
 become sour spontaneously, as vegetable and 
 animal juices, or infusions. The suddenness 
 with which this change is effected during a 
 thunder storm, even in corked bottles, has 
 not been accounted for. In morbid states of 
 the stomach, also, it proceeds with astonish- 
 ing rapidity. It is counteracted by bitters, 
 antacids, and purgatives.* 
 
 Acetates. The salts formed by the com. 
 bination of the acetic acid with alkalis, 
 earths, and metallic oxides. See the diffe- 
 rent bases. 
 
 * Acetic Acid. See Acid (Acetic).* 
 
 * Acetometer. An instrument for esti- 
 mating the strength of vinegars. It is des- 
 cribed under Acid (Acetic).* 
 
 Acetous. Of or belonging to vinegar. 
 See Acid (Acetic). 
 
 Achromatic. Telescopes formed ot a 
 combination of lenses, which in a great mea- 
 sure correct the optical aberration, arising 
 from the various colours of light, are called 
 achromatic telescopes. Some of these have 
 been made wonderfully perfect, and their ex- 
 cellence appears to be limited only by the 
 imperfections of the art of glass-making. 
 Theartificeof this capital invention of Dollond 
 consists in selecting, by trial, two such pieces 
 of glass, to form the object lenses, as separate 
 the variously coloured rays of light to equal 
 angles of divergence, at different angles of 
 refraction of the mean ray ; in which case it 
 is evident, that, if they be made to refract to- 
 wards contrary parts, the whole ray may be 
 
 caused to deviate from its course without 
 being separated into colours. The difficulty 
 of the glass-maker is in a great measure con- 
 fined to the problem of making that kind of 
 glass which shall cause a great divergence of 
 the coloured rays with respect to each other, 
 while the mean refraction is small. See 
 Glass; also Aflanatic. 
 
 * Acids. The most important class of che- 
 mical compounds. In the generalization of 
 facts presented by Lavoisier and the associat- 
 ed French chemists, it was the leading doctrine 
 that acids resulted from the union of a pecu- 
 liar combustible base called the radical, with 
 a common principle technically called oxygen, 
 or the acidifier. This general position was 
 founded chiefly on the phenomena exhibit- 
 ed in the formation and decomposition of 
 sulphuric, carbonic, phosphoric, and nitric 
 acids ; and was extended by a plausible 
 analogy to other acids whose radicals were 
 unknown. 
 
 “ I have already shewn,” says Lavoisier, 
 “ that phosphorus is changed by combustion 
 into an extremely light, white, flaky matter. 
 Its properties are likewise entirely altered 
 by this transformation ; from being insoluble 
 in water, it becomes not only soluble, but so 
 greedy of moisture as to attract the humidity 
 of the air with astonishing rapidity. By this 
 means it is converted into a liquid, consider- 
 ably more dense, and of more specific gravity 
 than water. In the state of phosphorus be- 
 fore combustion, it had scarcely any sensible 
 taste ; by its union with oxygen, it acquires 
 an extremely sharp and sour taste ; in a 
 word, from one of the class of combustible 
 bodies, it is changed into an incombustible 
 substance, and becomes one of those bodies 
 called acids. 
 
 “ This property of a combustible substance, 
 to be converted into an acid by the addition 
 of oxygen, we shall presently find belongs to 
 a great number of bodies. Wherefore strict 
 logic requires that we should adopt a com- 
 mon term for indicating all these operations 
 which produce analogous results. This is 
 the true way to simplify the study of science, 
 as it would be quite impossible to bear all 
 its specific details in the memory if they 
 were not classically arranged. For this rea- 
 son we shall distinguish the conversion of 
 phosphorus into an acid by its union with 
 oxygen, and in general every combination of 
 oxygen with a combustible substance, by the 
 term oxygenation ; from this I shall adopt the 
 verb to oxygenate ; and of consequence shall 
 say, that in oxygenating phosphorus, we con- 
 vert it into an acid. 
 
 “ Sulphur also, in burning, absorbs oxygen 
 gas ; the resulting acid is considerably heavier 
 than the sulphur burnt ; its weight is equal 
 to the sum of the weights of the sulphur 
 which has been burnt, and of the oxygen ab- 
 sorbed ; and, lastly, this acid is weighty, in- 
 
ACI 
 
 ACI 
 
 combustible, and miscible with water in all 
 proportions. 
 
 “ I might multiply these experiments, and 
 shew, by a numerous succession of facts, that 
 all acids are formed by the combustion of 
 certain substances; but I am prevented from 
 doing so in this place by the plan which I 
 have laid down, of proceeding only from facts 
 already ascertained to such as are unknown, 
 and of drawing my examples only from cir- 
 cumstances already explained. In the mean 
 time, however, the examples above cited may 
 suffice for giving a clear and accurate con- 
 ception of the manner in which acids are 
 formed. By these it may be clearly seen 
 that oxygen is an element common to them 
 all, and which constitutes or produces their 
 acidity ; and that they differ from each other 
 according to the several natures of the oxy- 
 genated or acidified substances. We must, 
 therefore, in every acid carefully distinguish 
 between the acidifiable base, which M. de 
 Morveau calls the radical, and “ the acidifying 
 principle or oxygen.” Elements, p. 115. 
 
 “ Although we have not yet been able either 
 to compose or to decompound this acid of 
 sea salt, we cannot have the smallest doubt 
 that it, like all other acids, is composed by 
 the union of oxygen with an acidifiable base. 
 We have, therefore, called this unknown 
 substance the muriatic base, or muriatic radi- 
 cal.” P. 122.5th Edition. 
 
 Berthollet’s sound discrimination led him 
 to maintain that Lavoisier had given too much 
 latitude to the idea of oxygen being the uni- 
 versal acidifying principle. “ In fact,” says 
 he, “ it is carrying the limits of analogy too 
 far to infer, that all acidity, even that of the 
 muriatic, fluoric, and boracic acids, arises 
 from oxygen, because it gives acidity to a 
 great number of substances. Sulphuretted 
 hydrogen, which really possesses the proper- 
 ties of an acid, proves directly that acidity 
 is not in all cases owing to oxygen. There 
 is no better foundation for concluding that 
 hydrogen is the principle of alkalinity not 
 only in the alkalis, properly so called, but 
 also in magnesia, lime, strontian, and barytes, 
 because ammonia appears to owe its alkalin- 
 ity to hydrogen. 
 
 these considerations prove that oxygen 
 may be regarded as the most usual principle 
 of acidity, but that this species of affinity for 
 the alkalis may belong to substances which 
 do not contain oxygen ; that we must not, 
 therefore, always infer, from the acidity of a 
 substance, that it contains oxygen, although 
 this may be an inducement to suspect its ex- 
 istence in it, still less should we conclude, be- 
 cause a substance contains oxygen, that it 
 must have acid properties; on the contrary, 
 the acidity of an oxygenated substance shews 
 that the oxygen has only experienced an in- 
 complete saturation in it, since its properties 
 remain predominant.” 
 
 Amid the just views which pervade the 
 early part of this quotation from Berthollet, 
 it is curious to remark the solecism with 
 which it terminates. For after maintaining 
 that acidity may exist independent of oxygen, 
 and that the presence of oxygen does not ne- 
 cessarily constitute acidity, he concludes by 
 considering acidity as the criterion of unsatu- 
 rated oxygen. 
 
 This unwarrantable generalization of the 
 French chemists concerning oxygen, which 
 had succeeded Stahl’s equally unwarrantable 
 generalization of a common principle of com- 
 bustibility in all combustible bodies, was first 
 experimentally combated by Sir H. Davy, 
 in a series of admirable dissertations publish- 
 ed in the Philosophical Transactions. 
 
 His first train of experiments were insti- 
 tuted with the view of operating by voltaic 
 electricity on muriatic and other acids freed 
 from water. Substances which are now 
 known by the names of chlorides of phos- 
 phorus and tin, but which he then supposed 
 to contain dry muriatic acid, led him to ima- 
 gine intimately combined water to be the 
 real acidifying principle, since acid properties 
 were immediately developed in the above 
 substances by the addition of that fluid, 
 though previously they exhibited no acid 
 powers. In July 1810, however, he advan- 
 ced those celebrated views concerning acidi- 
 fication, which, in the opinion of the best 
 judges, display an unrivalled power of scien- 
 tific research. The conclusions to which 
 these led him, were incompatible with the 
 general hypothesis of Lavoisier. He demon- 
 strated that oxymuriatic acid is, as far as our 
 knowledge extends, a simple substance, which 
 may be classed in the same order of natural 
 bodies as oxygen gas, being determined like 
 oxygen to the positive surface in voltaic com- 
 binations, and like oxygen combining with in- 
 flammable substances, producingheat and light. 
 The combinations of oxymuriatic acid with 
 inflammable bodies were shewn to be analo- 
 gous to oxides and acids in their properties 
 and powers of combination, but to differ from 
 them in being for the most part decomposable 
 by water : And finally, that oxymuriatic 
 
 acid has a stronger attraction for most in- 
 flammable bodies than oxygen. His pre- 
 ceding decomposition of the alkalis and earths 
 having evinced the absurdity of that nomen- 
 clature, which gives to the general and essen- 
 tial constituent of alkaline nature, the term 
 oxygen or acidifier ; his new discovery of 
 the simplicity of oxymuriatic acid, shewed 
 the theoretical system of chemical language 
 to be equally vicious in another respect. 
 Hence this philosopher most judiciously dis- 
 carded the appellation oxymuriatic acid, and 
 introduced in its place the name chlorine, 
 which merely indicates an obvious and per- 
 manent character of the substance, its green- 
 ish yellow colour. I he more recent inves- 
 
ACI 
 
 ACI 
 
 tigations of chemists on fluoric, hydriodic, 
 and hydrocyanic acids have brought power- 
 ful analogies in support of the chloridic 
 theory, by shewing that hydrogen alone can 
 convert certain undccompounded bases into 
 acids well characterized, without the aid of 
 oxygen. Dr Murray indeed has endeavour- 
 ed to revive and new-model the early opinion 
 of Sir H. Davy, concerning the necessity of 
 the presence of water, or its elements, to the 
 constitution of acids. He conceives that many 
 acids arc ternary compounds of a radical with 
 oxygen and hydrogen ; but that the two lat- 
 ter ingredients do not necessarily exist in them 
 in the state of water. Oil of vitriol, for in- 
 stance, in this view, instead of consisting of 
 81.5 real acid, and 18.5 water in 100 parts, 
 may be regarded as a compound of 32.6 
 sulphur -j- 65.2 oxygen, + 2.2 hydrogen. 
 When it is saturated with an alkaline base, 
 and exposed to heat, the hydrogen unites to its 
 equivalent quantity of oxygen, to form water 
 which evaporates, and the remaining oxygen 
 and the sulphur combine with the base. But 
 when the acid is made to act on a metal, the 
 oxygen partly unites to it, and hydrogen 
 alone escapes. 
 
 “ Nitric acid, in its highest state of concen- 
 tration, is not a definite compound of real 
 acid, with about a fourth of its weight of 
 water, but a ternary compound of nitrogen, 
 oxygen, and hydrogen. Phosphoric acid is 
 a triple compound of phosphorus, oxygen, 
 and hydrogen ; and phosphorous acid is the 
 proper binary compound of phosphorus and 
 oxygen. The oxalic, tartaric, and other 
 vegetable acids, are admitted to be ternary 
 compounds of carbon, oxygen, and hydro- 
 gen ; and are therefore in strict conformity 
 to the doctrine now illustrated. 
 
 “ A relation of the elements of bodies to 
 acidity is thus discovered different from what 
 has hitherto been proposed. When a series 
 of compounds exists, which have certain 
 common characteristic properties, and when 
 these compounds all contain a common ele- 
 ment, we conclude, with justice, that these 
 properties are derived more peculiarly from 
 the action of this element. On this ground 
 Lavoisier inferred, by an ample induction, 
 that oxygen is a principle of acidity. Ber- 
 thollet brought into view the conclusion, that 
 it is not exclusively so, from the examples of 
 prussic acid and sulphuretted hydrogen. In 
 the latter, acidity appeared to be produced 
 by the action of hydrogen. The discovery 
 by G ay Lussac, of the compound radical 
 cyanogen, and its conversion into prussic 
 acid by the addition of hydrogen, confirmed 
 this conclusion ; and the discovery of the 
 relations of iodine still further established it. 
 And now, if the preceding views are just, 
 the system must be still further modified. 
 While each of these conclusions are just to a 
 certain extent, each of them requires to be 
 
 limited in some of the cases to which they 
 are applied ; and w hile acidity is sometimes 
 exclusively connected with oxygen, sometimes 
 with hydrogen, the principle must also be ad- 
 mitted, that it is more frequently the result 
 of their combined operation. 
 
 “ There appears even sufficient reason to 
 infer, that, from the united action of these 
 elements, a higher degree of acidity is ac- 
 quired than from the action of either alone. 
 Sulphur affords a striking example of this. 
 With hydrogen it forms a weak acid. With 
 oxygen it also forms an acid, which, though 
 of superior energy, still dees not display 
 much pow'er. With hydrogen and oxygen 
 it seems to receive the acidifying influence 
 of both, and its acidity is proportionally ex- 
 alted. 
 
 “ Nitrogen, with hydrogen, forms a com- 
 pound altogether destitute of acidity, and 
 possessed even of qualities the reverse. With 
 oxygen, in two definite proportions, it forms 
 oxides; and it is doubtful if, in any propor- 
 tion, it can establish with oxygen an insulat- 
 ed acid. But with oxygen and hydrogen in 
 union it forms nitric acid, a compound more 
 permanent, and of energetic action.” 
 
 It is needless to give at more detail Dr 
 Murray’s speculations, which, supposing them 
 plausible in a theoretical point of view, seem 
 barren in practice ; at least their practical 
 tendency cannot be perceived by the Editor 
 of this work. It is sufficiently singular, that, 
 in an attempt to avoid the mysterious and 
 violent transformations, which, on the chlo- 
 ridic theory, a little moisture operates on 
 common salt, instantly changing it from 
 chlorine and sodium, into muriatic acid and 
 soda, Dr Murray should have actually mul- 
 tiplied, with one hand, the very difficulties 
 which he had laboured, with the other, to 
 remove. 
 
 He thinks it doubtful if nitrogen and oxy- 
 gen can alone form an insulated acid. Hy- 
 drogen he conceives essential to its energetic 
 action. What, we may ask then, exists in 
 dry nitre, which contains no hydrogen ? Is 
 it nitric acid, or merely two of its elements, 
 in want of a little water to furnish the re- 
 quisite hydrogen ? The same questions may 
 be asked relative to the sulphate of potash. 
 Since he conceives hydrogen necessary to 
 communicate full force lo sulphuric and ni- 
 tric acids, the moment they lose their water 
 they should lose their saturating power, and 
 become incapable of retaining caustic potash 
 in a neutral state. Out of this dilemma he 
 may indeed try to escape, by saying, that 
 moisture or hydrogen is equally essential to 
 alkaline strength, and that therefore the same 
 desiccation or de-hydrogenation which im- 
 pairs the acid power, impairs also that of its 
 alkaline antagonist. The result must evi- 
 dently be, that, in a saline hydrate or solu- 
 tion, we have the reciprocal attractions of a 
 
A Cl 
 
 strong acid and alkali, while, in a ury salt, 
 the attractive forces are those of relatively 
 feeble bodies. On this hypothesis, the diffe- 
 rence ought to be great between diy and 
 moistened sulphate of potash. Carbonic acid 
 he admits to be destitute of hydrogen ; yet 
 its saturating power is very conspicuous in 
 neutralizing dry lime. Now, oxalic acid, by 
 the last analysis of Berzelius, contains no 
 hydrogen. It differs from the caibonic only 
 in the proportion of its two constituents. 
 And oxalic acid is appealed to by Dr Murray 
 as a proof of the superior acidity bestowed 
 by hydrogen. 
 
 On what grounds he decides carbonic to 
 be a feebler acid than oxalic, it is difficult to 
 see. By Berthollet’s test of acidity, the 
 former is more energetic than the latter in 
 the proportion of 100 to about 58 ; for these 
 numbers are inversely as the quantity of each 
 requisite to saturate a given base. If he be 
 inclined to reject this rule, and appeal to the 
 decomposition of the carbonates by oxalic 
 acid, as a criterion of relative acid power, let 
 us adduce his own commentary on the sta- 
 tical affinities of Berthollet, where he as- 
 cribes such changes not to a superior attrac- 
 tion in the decomposing substance, but to the 
 elastic tendency of that which is evolved. 
 Ammonia separates magnesia from its mu- 
 riatic solution at common temperatures ; at 
 the boiling heat of water, magnesia separates 
 ammonia. Carbonate of ammonia, at tem- 
 peratures under 230°, precipitates carbonate 
 of lime from the muriate ; at higher tempera- 
 tures the inverse decomposition takes place 
 with the same ingredients. If the oxalic 
 be a more energetic acid than the carbonic, 
 or rank higher in the scale of acidity, then, 
 on adding to a given weight of liquid muri- 
 ate of lime, a mixture of oxalate and carbo- 
 nate of ammonia, each in equivalent quantity 
 to the calcareous salt, oxalate of lime ought 
 alone to be separated. It will be found, 
 on the contrary, by the test of acetic acid, 
 that as much carbonate of lime will precipi- 
 tate as is sufficient to unsettle these specula- 
 tions. 
 
 Finally, dry nitre, and dry sulphate of pot- 
 ash, are placed, by this supposition, in as 
 mysterious a predicament as dry muriate of 
 soda in the chloridic theory. Deprived of 
 hydrogen, their acid and alkali are enfeebled 
 or totally changed. With a little w'ater both 
 instantly recruit their powers. In a word, 
 the solid sulphuric acid of Nordhausen, and 
 the dry potash of potassium, are alone suffi- 
 cient to subvert this whole hypothesis of hy- 
 drogenation. 
 
 We shall introduce, under the head of 
 alkali, some analogous speculations by Dr 
 Murray on the influence of the elements of 
 water on that class of bodies. Edin. Phil. 
 Trans, vol. viii. part 2d. 
 
 After these observations on the nature of 
 
 AC1 
 
 acidity, we shall now state the general pro- 
 perties of the acids. 
 
 1. The taste of these bodies is for the most 
 part sour, as their name denotes ; and in the 
 stronger species it is acrid and corrosive. 
 
 2. They generally combine with water in 
 every proportion, with a condensation of 
 volume and evolution of heat. 
 
 5. With a few' exceptions they are volati- 
 lized or decomposed at a moderate heat. 
 
 4. They usually chango the purple colours 
 of vegetables to a bright red. 
 
 5. They unite in definite proportions with 
 the alkalis, earths, and metallic oxides, and 
 form the important class of salts. 1 his may 
 be reckoned their characteristic and indis- 
 pensable property. The pow r ers of the diffe- 
 rent acids were originally estimated by their 
 relative causticity and sourness, afterwards 
 by the scale of their attractive force towards 
 any particular base, and next by the quantity 
 of the base wdiich they could respectively 
 neutralize. But Berthollet proposed the 
 converse of this last criterion as the measure 
 of their pow ers. “ The power with which 
 they can exercise their acidity,” he estimates 
 “ by the quantity of each of the acids which 
 is required to produce the same effect, viz. to 
 saturate a given quantity of the same alkali.” 
 It is therefore the capacity for saturation of 
 each acid, which, in ascertaining its acidity, 
 according to him, gives the comparative force 
 of the affinity to wdiich it is owing. Hence 
 he infers, that the affinity of the different 
 acids for an alkaline base, is in the inverse 
 ratio of the ponderable quantity of each of 
 them which is necessary to neutralize an 
 equal quantity of the same alkaline base. 
 An acid is, therefore, in this view', the more 
 powerful, when an equal weight can saturate 
 a greater quantity of an alkali. Hence, all 
 those substances which can saturate the alka- 
 lis, and cause their properties to disappear, 
 ought to be classed among the acids; in like 
 manner, among the alkalis should be placed 
 all those which, by their union, can saturate 
 acidity. And the capacity for saturation be- 
 ing the measure of this property, it should 
 be employed to form a scale of the compara- 
 tive power of alkalis as well as that of acids. 
 
 However plausible, a priori , the opinion of 
 this illustrious philosopher may be, that the 
 smaller the quantity of an acid or alkali re- 
 quired to saturate a given quantity of its an- 
 tagonist principle, the higher should it rank 
 in the scale of power and affinity, it will not, 
 however, accord tyith chemical phenomena. 
 100 parts of nitric acid are saturated by about 
 36-J of magnesia, and by 52-J of lime. 
 
 Hence, by Berthollet’s rule, the powers 
 of these earths ought to bo as the inverse 
 
 of their quantities, viz. — — and -i— ; yet 
 
 3 52\ * 
 
 the very opposite effect takes place, for lime 
 separates magnesia from nitric acid. And, in 
 
ACI 
 
 ACI 
 
 the present example, the difference of effect 
 cannot be imputed to the difference of force 
 with which the substances tend to assume the 
 solid state. 
 
 We have therefore at present no single 
 acidifying principle, nor absolute criterion of 
 the scale of power among the different acids ; 
 nor is the want of this of great importance. 
 Fxperiment furnishes us with the order of 
 decomposition of one acido-alkaline com- 
 pound by another acid, whether alone, or 
 aided by temperature ; and this is all which 
 practical chemistry seems to require. 
 
 Before entering on the particular acids, 
 we shall here describe the general process by 
 which M. Thenard has lately succeeded in 
 communicating to many of them apparently 
 a surcharge of oxygen, and thus producing 
 a new class of bodies, the oxygenized acids, 
 which he has had the good fortune of form- 
 ing and making known to the chemical 
 world. The first notice of these new com- 
 pounds appeared in the Ann. de Chiinie et 
 Physique , viiu 306. for July 1818, since 
 which time several additional communica- 
 tions of a very interesting nature have been 
 made by the same celebrated chemist. He 
 has likewise formed a compound of water 
 with oxygen, in which the proportion of the 
 latter principle is doubled, or 616 times its 
 volume is added. The methods of oxygen- 
 izing the liquid acids and water, agree in 
 this, that deutoxide of barium is formed first 
 of all, from which the above liquids, by a 
 subsequent process, derive their oxygen. He 
 prescribes the following precautions, without 
 which success will be only partial : — 
 
 1. Nitrate of barytes should first be ob- 
 tained perfectly pure, and, above all, free 
 from iron and manganese. The most certain 
 means of procuring it is to dissolve the ni- 
 trate in water, to add to the solution a small 
 excess of barytes water, to filter and crys- 
 talize. 2. The pure nitrate is to be decom- 
 posed by heat. This ought not to be done 
 in a common earthenware retort, because it 
 contains too much of the oxides of iron and 
 manganese, but in a perfectly white porcelain 
 retort. Four or five pounds of nitrate of 
 barytes may be decomposed at once, and the 
 process will require about three hours. The 
 barytes thus procured will contain a consider- 
 able quantity of silex and alumina ; but it 
 will have only very minute traces of manga- 
 nese and iron, a circumstance of essential 
 importance. 5. The barytes, divided by a 
 knife into pieces as large as the end of the 
 thumb, should then be placed in a luted tube 
 of glass. This tube should be long, and 
 large enough to contain from 2^ to 3^ libs. 
 It is to be surrounded with fire, and heated 
 to dull redness, and then a current of dry 
 oxygen gas is to be passed through it. How- 
 ever rapid the current, the gas is completely 
 absorbed ; so that when it passes, by the 
 
 small tube, which ought to terminate the 
 larger one, it may be concluded that the 
 deutoxide of barium is completed. It is, 
 however, right to continue the current for 
 seven or eight minutes more. Then the 
 tube being nearly cold, the deutoxide, which 
 is of a light grey colour, is taken out, and 
 preserved in stoppered bottles. When this 
 is moistened it falls to powder, without much 
 increase of temperature. If in this state it 
 be mixed with seven or eight times its weight 
 of water, and a dilute acid be poured in, it 
 dissolves gradually by agitation, without the 
 evolution of any gas. The solution is neu- 
 tral, or has no action on turnsole or turme- 
 ric. When we add to this solution the re- 
 quisite quantity of sulphuric acid, a copious 
 precipitate of barytes falls, and the fdtered 
 liquor is merely water, holding in solution 
 the oxygenized acid, or dentoxide of hydro- 
 gen, combined with the acid itself. 
 
 The class of acids has been distributed into 
 three orders, according as they are derived 
 from the mineral, the vegetable, or the animal 
 kingdom. But a more specific distribution 
 is now requisite. They have also been ar- 
 ranged into those which have a single, and 
 those which have a compound basis or radi- 
 cal. But this arrangement is not only vague, 
 but liable in other respects to considerable 
 objections. The chief advantage of a classifi- 
 cation is to give general views to beginners in 
 the study, by grouping together such sub- 
 stances as have analogous properties or com- 
 position. These objects, it is hoped, will be 
 tolerably well attained by the follow ing divi- 
 sions and subdivisions. 
 
 Division 1st, Acids from inorganic nature, 
 or which arc procurable without having re- 
 course to animal or vegetable products. 
 
 Division 2d, Acids elaborated by means 
 of organization. 
 
 The first groupe is subdivided into throe 
 families, 1st, Oxygen acids ; 2d, Hydrogen 
 acids ; 5d, Acids destitute of both these sup- 
 posed acidifiers. 
 
 Family 1st.- 
 
 Section 1st, 
 
 1. Boracic. 
 
 2. Carbonic. 
 
 3. Chloric. 
 
 4. Perchloric. 
 
 5. Chloro- carbonic. 
 
 6. Nitrous. 
 
 7. Nitric. 
 
 8. Iodic. 
 
 -Oxygen acids. 
 
 Non-metallic. 
 
 • 9. Hypophosphorous. 
 
 10. Phosphorous. 
 
 11. Phosphoric. 
 
 12. Ilyposulphurous. 
 
 1 3. Sulphurous. 
 
 14. Sulphuric. 
 
 15. Hyposulphuric. 
 
 16. Cyanic? 
 
 Section 2d, Oxygen acids. — Metallic. 
 
 1. Arsenic. 6. Columbic. 
 
 2. Arsenious. 7. Molybdic. 
 
 3. Antimonious. 8. Molybdous. 
 
 4. Antimonic. 9. Tungstic. 
 
 5. Chromic. 
 
ACI 
 
 ACI 
 
 Family 2d.— Hydrogen acids. 
 
 1. Fluoric. 5. Hydroprussic. 
 
 2. Hydriodic. 6. Hydrosulphurous. 
 
 3. Hydrochloric. 7. Hydrotellurous. 
 
 4. Ferroprussic. 8. Sulphuroprussic. 
 
 Family 3d. — Acids without oxygen or 
 hydrogen. 
 
 1. Chloriodic. 3. Fluoboric. 
 
 2. Chloroprussic. 4. Fluosilicic. 
 
 Division 2d.— Acids of organic origin. 
 
 1. Aceric. 
 
 20. Margaric. 
 
 2. Acetic. 
 
 21. Melassic. 
 
 3. Amniotic. 
 
 22. Mellitic. 
 
 4. Benzoic. 
 
 23. Moroxylic. 
 
 5. Boletic. 
 
 24. Mucic. 
 
 6. Camphoric. 
 
 25. Oleic. 
 
 7. Caseic. 
 
 26. Oxalic. 
 
 8. Citric. 
 
 27. Purpuric. 
 
 9. Formic. 
 
 28. Pyrolithic. 
 
 10. Fungic. 
 
 29. Pyromalic. 
 
 1 1 . Gallic. 
 
 30. Pyrotartaric. 
 
 12. Kinic. 
 
 31. Rosacic. 
 
 13. Laccic. 
 
 32. Saclactic. 
 
 14. Lactic. 
 
 S3. Sebacic. 
 
 15. Lampic. 
 
 34. Suberic. 
 
 Id. Lithic. 
 
 35. Succinic. 
 
 17. Malic. 
 
 36. Sulphovinic? 
 
 18. Meconic. 
 
 57 . Tartaric. 
 
 19. Menispennic. 
 
 58. Zumic. 
 
 The acids of the last division are all decompos- 
 able at a red heat, and afford generally carbon, 
 hydrogen, oxygen, and in some few cases 
 also nitrogen. The mellitic is found like 
 amber in wood coal, and like it, is undoubt- 
 edly of organic origin. We shall treat of 
 them all in alphabetical order, only joining 
 those acids together which graduate, so to 
 speak, into each other, as hyposulphurous, 
 sulphurous, and sulphuric.* 
 
 * Acid (Aceric). A peculiar acid said to 
 exist in the juice of the maple. It is de- 
 composed by heat, like the other vegetable 
 acids.* 
 
 * Acid ( Acetic). The same acid which, in 
 a very dilute and somewhat impure state, is 
 called vinegar. 
 
 This acid is found combined with potash 
 in the juices of a great many plants ; parti- 
 cularly the sambucus nigra, phoenix dactilife- 
 ra, galium verum, and rhus typhinus. Sweat, 
 urine, and even fresh milk contain it. It is 
 frequently generated in the stomachs of dys- 
 peptic patients. Almost all dry vegetable 
 substances, and some animal, subjected in 
 close vessels to a red heat, yield it copiously. 
 It is the result likewise of a spontaneous fer- 
 mentation, to which liquid vegetable, and ani- 
 mal matters arc liable. Strong acids, as the 
 sulphuric and nitric, developc the acetic by 
 their action on vegetables. It was long sup- 
 posed, on the authority of Boerhaave, that 
 the fermentation which forms vinegar is uni- 
 formly preceded by the vinous. ‘This is a 
 
 mistake. Cabbages sour in water, making 
 sourcrout; starch in starch-makers’ sour wa- 
 ters ; and dough itself, without any previous 
 production of wine. 
 
 The varieties of acetic acids known in 
 commerce are four : 1 st, Wine vinegar ; 
 
 2d, Malt vinegar ; 3d, Sugar vinegar ; 4th, 
 Wood vinegar. We shall describe first the 
 mode of making these commercial articles, 
 and then that of extracting the absolute 
 acetic acid of the chemist, either from these 
 vinegars, or directly from chemical com- 
 pounds, of which it is a constituent. 
 
 The following is the plan of making vine- 
 gar at present practised in Paris. The wine 
 destined for vinegar is mixed in a large tun 
 with a quantity of wine lees, and the whole 
 being transferred into cloth-sacks, placed 
 within a large iron-bound vat, the liquid 
 matter is extruded through the sacks by 
 superincumbent pressure. What passes 
 through is put into large casks, set upright, 
 having a small aperture in their top. In 
 these it is exposed to the heat of the sun in 
 summer, or to that of a stove in winter. 
 Fermentation supervenes in a few days. If 
 the heat should then rise too high, it is 
 lowered by cool air, and the addition of fresh 
 wine. In the skilful regulation of the fer- 
 mentative temperature consists the art of 
 making good wine vinegar. In summer, 
 the process is generally completed in a fort- 
 night : in winter, double the time is requi- 
 site. The vinegar is then run off into bar- 
 rels, which contain several chips of birch- 
 wood. In about a fortnight it is found to 
 be clarified, and is then fit for the market. 
 It must be kept in close casks. 
 
 The manufacturers at Orleans prefer wine 
 of a year old for making vinegar. But if 
 by age the wine has lost its extractive mat- 
 ter, it does not readily undergo the acetous 
 fermentation. In this case, acetification, as 
 the French term the process, may be deter- 
 mined, by adding slips of vines, bunches of 
 grapes, or green woods. It has been assert- 
 ed, that alcohol, added to fermentable liquor, 
 does not increase the product of vinegar. 
 But this is a mistake. Stahl observed long 
 ago, that if we moisten roses or lilies with 
 alcohol, and place them in vessels in which 
 they are stirred from time to time, vinegar 
 w ill be formed. He also informs us, if after 
 abstracting the citric acid from lemon juice 
 by crabs’ eves (carbonate of lime), we add a 
 little alcohol to the supernatant liquid, and 
 place the mixture in a proper temperature, 
 vinegar will be formed. 
 
 Cliaptal says, that two pounds of weak 
 spirits, sp. gr. 0.985, mixed with 300 grains 
 of beer yeast, and a little starch water, pro- 
 duced extremely strong vinegar. The acid 
 was developed on the 5th day. The same 
 quantity of starch and yeast, without the 
 spirit, fermented more slowly, and yielded a 
 
ACI 
 
 ACI 
 
 weaker vinegar. A slight motion is found 
 to favour the formation of vinegar, and to 
 endanger its decomposition after it is made. 
 Chaptal ascribes to agitation the operation of 
 thunder; though it is well known, that when 
 the atmosphere is highly electrified, beer is 
 apt to become suddenly sour, without the 
 concussion of a thunder-storm. In cellars 
 exposed to the vibrations occasioned by the 
 rattling of carriages, vinegar does not keep 
 well. The lees, which had been deposited by 
 means of isinglass and repose, are thus jum- 
 bled into the liquor, and make the fermenta- 
 tion recommence. 
 
 Almost all the vinegar of the north of 
 France being prepared at Orleans, the manu- 
 factory of that place has acquired such cele- 
 brity, as to render their process worthy of a 
 separate consideration. 
 
 The Orleans’ casks contain nearly 400 
 pints of wine. Those which have been al- 
 ready used are preferred. They are placed 
 in three rows, one over another, and in the 
 top have an aperture of two inches diameter, 
 kept always open. The wine for acetifica- 
 tion is kept in adjoining casks, containing 
 beech shavings, to which the lees adhere. 
 The wine thus clarified is drawn off to make 
 vinegar. One hundred pints of good vine- 
 gar, boiling hot, are first poured into each 
 cask, and left there for eight days. Ten 
 pints of wine are mixed in, every eight days, 
 till the vessels are full. The vinegar is 
 allowed to remain in this state fifteen days, 
 before it is exposed to sale. 
 
 The used casks, called mothers, are never 
 emptied more than half, but are successively 
 filled again, to acetify new portions of wine. 
 In order to judge if the mother works, the 
 vinegar makers plunge a spatula into the li- 
 quid ; and according to the quantity of froth 
 which the spatula shews, they add more or 
 less wine. In summer, the atmospheric heat 
 is sufficient. In winter, stoves heated to 
 about 7 5° Fahr. maintain the requisite tem- 
 perature in the manufactory. 
 
 In some country districts, the people keep 
 in a place where the temperature is mild and 
 equable, a vinegar cask, into which they pour 
 such wine as they wish to acetify ; and it is 
 always preserved full, by replacing the vine- 
 gar draw'll off, by new wine. To establish 
 this household manufacture, it is only neces- 
 sary to buy at first a small cask of good vi- 
 negar. At Gaud a vinegar from beer is 
 made, in which the following proportions ot 
 grain are found to be most advantageous : — 
 1880 Paris lbs. malted barley. 
 
 700 wheat. 
 
 500 buckwheat. 
 
 These grains are ground, mixed, and boiled, 
 along with twenty-seven casks-full of river 
 water, for three hours. Eighteen casks of 
 good beer for vinegar are obtained. By a 
 subsequent decoction, more fermentable li- 
 
 quid is extracted, which is mixed w ith the 
 former. The whole brewing yields 3000 
 English quarts. 
 
 In this country, vinegar is usually made 
 from malt. By mashing with hot water, 
 100 gallons of wort are extracted in less than 
 two hours from 1 boll of malt. When the 
 liquor has fallen to the temperature of 75° 
 Fahr. 4 gallons of the barm of beer are add- 
 ed. After thirty- six hours it is racked off’ 
 into casks, which are laid on their sides, and 
 exposed, with their bung-holes loosely cover- 
 ed, to the influence of the sun in summer ; 
 but in winter they are arranged in a stove- 
 room. In three months this vinegar is ready 
 for the manufacture of sugar of lead. To 
 make vinegar for domestic use, however, the 
 process is somewhat different. The above 
 liquor is racked off' into casks placed up- 
 right, having a false cover pierced with holes 
 fixed at about a foot from their bottom. 
 On this a considerable quantity of rape, or 
 the refuse from the makers of British 
 wine, or otherwise a quantity of low 
 priced raisins, is laid. The liquor is turn- 
 ed into another barrel every twenty- four 
 hours, in which time it has begun to grow' 
 warm. Sometimes, indeed, the vinegar is 
 fully fermented, as above, without the rape, 
 which is added towards the end, to commu- 
 nicate flavour. Tw'o large casks are in this 
 case worked together, as is described long 
 ago by Boerhaavc, as follows. 
 
 “ Take two large w ooden vats, or hogsheads, 
 and in each of these place a wooden grate 
 or hurdle, at the distance of a foot from the 
 bottom. Set the vessel upright, and on the 
 grate place a moderately close layer of green 
 tw igs, or fresh cuttings of the vine. Then 
 fill up the vessel with the footstalks of grapes, 
 commonly called the rape, to the top of the 
 vessel, which must be left quite open. 
 
 “ Having thus prepared the two vessels, 
 pour into them the wine to be converted 
 into vinegar, so as to fill one of them quite 
 up, and the other but half full. Leave 
 them thus for twenty-four hours, and then 
 fill up the half filled vessel with liquor from 
 that which is quite full, and which will now 
 in its turn only be left half full. Four-and- 
 twenty hours afterwards repeat the same 
 operation, and thus go on, keeping the vessels 
 alternately full and half full during twentv- 
 four hours, till the vinegar be made. On 
 the second or third day there will arise in 
 the half filled vessel, a fermentative motion, 
 accompanied with a sensible heat, which will 
 craduallv increase from day to day. On the 
 contrary, the fermenting motion is almost 
 imperceptible in the full vessel ; and as the 
 two vessels are alternately full and half full, 
 the fermentation is by this means in some 
 measure interrupted, and is only renewed 
 everv other dav in each vessel. 
 
 “ When this motion appears to havq entirely 
 
ACI 
 
 ACI 
 
 ceased, even in the half filled vessel, it is a 
 sign that the fermentation is finished ; and 
 therefore the vinegar is then to be put into 
 casks close stopped, and kept in a cool 
 place. 
 
 A greater or less degree of warmth acce- 
 lerates or checks this, as well as the spiritu- 
 ous fermentation. In France it is finished 
 in about fifteen days, during the summer , 
 but if the heat of the air be very great, and 
 exceed the twenty-fifth degree of Reau- 
 mur’s thermometer, (88^° Fahr.) the half 
 filled vessel must be filled up every twelve 
 hours ; because, if the fermentation be not 
 so checked in that time, it will become vio- 
 lent, and the liquor will be so heated, that 
 many of the spirituous parts, on which the 
 strength of the vinegar depends, will be dis- 
 sipated, so that nothing will remain after the 
 fermentation but a vapid liquor, sour indeed, 
 but effete. The better to prevent the dissi- 
 pation of the spirituous parts, it is a proper 
 and usual precaution to close the mouth of 
 the half filled vessel, in which the liquor fer- 
 ments, with a cover made of oak wood. As 
 to the full vessel, it is always left open, that 
 the air may act freely on the liquor it con- 
 tains ; for it is not liable to the same incon- 
 veniences, because it ferments but very 
 slowly.” 
 
 Good vinegar may be made from a weak 
 syrup, consisting of 18 oz. of sugar to every 
 gallon of water. The yeast and rape are to 
 be here used, as above described. When- 
 ever the vinegar (from the taste and flavour) is 
 considered to be complete, it ought to be 
 decanted into tight barrels or bottles, and 
 well secured from access of air. A momen- 
 tary ebullition before it is bottled is found 
 favourable to its preservation. In a large 
 manufactory of malt vinegar, a considerable 
 revenue is derived from the sale of yeast to the 
 bakers. Vinegar obtained by the preceding 
 methods has more or less of a brown colour, 
 and a peculiar but rather grateful smell. 
 By distillation in glass vessels the colouring 
 matter, which resides in a mucilage, is sepa- 
 rated, but the fragrant odour is generally re- 
 placed by an empyreumatic one. The best 
 French wine vinegars, and also some from 
 malt, contain a little alcohol, which comes 
 over early with the watery part, and renders 
 the first product of distillation scarcely den- 
 ser, sometimes even less dense than water. 
 Jt is accordingly rejected. Towards the end 
 of the distillation the empyreuma increases. 
 Hence only the intermediate portions are 
 retained as distilled vinegar. Its specific 
 gravity varies from 1.005 to 1.015, while that 
 of common vinegar of equal strength varies 
 from 1.010 to 1.025. 
 
 A crude vinegar has been long prepared 
 for the calico printers, by subjecting wood 
 in iron retorts to a strong red heat. The 
 following arrangement of apparatus has been 
 
 found to answer well. A series of cast-iron 
 cylinders, about 4 feet diameter, and 6 feet 
 long, are built horizontally in brick work, so 
 that the flame of one furnace may play round 
 about two cylinders. Both ends project 
 a little from the brick work. One of them 
 has a disc of cast-iron well fitted and firmly 
 bolted to it, from the centre of which disc an 
 iron tube about 6 inches diameter proceeds, 
 and enters at a right angle the main tube of 
 refrigeration. The diameter of this tube 
 may be from 9 to 14 inches, according to the 
 number of cylinders. The other end of the 
 cylinder is called the mouth of the retort. 
 This is closed by a disc of iron, smeared 
 round its edge with clay- lute, and secured 
 in its place by wedges. The charge of wood 
 for such a cylinder is about 8 cwt. The 
 hard woods, oak, ash, birch, and beech, are 
 alone used. Fir does not answer. The heat 
 is kept up during the day-time, and the fur- 
 nace is allowed to cool during the night. 
 Next morning the door is opened, the char- 
 coal removed, and a new charge of wood is 
 introduced. The average product of crude 
 vinegar called pyrolignous acid is 35 gallons. 
 It is much contaminated with tar ; is of a 
 deep brown colour ; and has a sp. gr. of 
 1.025. Its total weight is therefore about 
 500 lbs. But the residuary charcoal is found 
 to weigh no more than one-fifth of the wood 
 employed. Hence nearly one-half of the 
 ponderable matter of the wood is dissipated 
 in incondensable gases. Count Rumford 
 states, that charcoal is equal in weight to 
 more than four-tenths of the wood from 
 which it is made. And M. Clement says 
 that it is equal to one-half. The Count’s 
 error seems to have arisen from the slight 
 heat of an oven to which his wood was expos- 
 ed in a glass cylinder. The result now given 
 is the experience of an eminent manufactur- 
 ing chemist at Glasgow. The crude pyro- 
 lignous acid is rectified by a second distilla- 
 tion in a copper still, in the body of which 
 about 20 gallons of viscid tarry matter are 
 left from every 100. It has now become a 
 transparent brown vinegar, having a consi- 
 derable empyreumatic smell, and a sp. gr. of 
 1.013. Its acid powers are superior to those 
 ot the best household vinegar, in the propor- 
 tion of 5 to 2. By redistillation, saturation 
 with quick-lime, evaporation of the liquid 
 acetate to dryness, and gentle torrefaction, 
 the empyreumatic matter is so completely 
 dissipated, that on decomposing the calcareous 
 salt by sulphuric acid, a pure, perfectly co- 
 lourless, and grateful vinegar rises in distilla- 
 tion. Its strength will be proportional to the 
 concentration of the decomposing acid. 
 
 Ihe acetic acid of the chemist may be 
 prepared in the following modes : 1st, Two 
 parts of fused acetate of potash with one of 
 the strongest oil of vitriol yield, by slow' dis- 
 tillation from a glass retort into a refriger- 
 
ACI 
 
 ACI 
 
 ated receiver, concentrated acetic acid. A 
 small portion of sulphurous acid, which 
 contaminates it, may he removed by redistil- 
 lation, from a little acetate of lead. 2d, Or 
 4 parts of good sugar of lead, with 1 part of 
 sulphuric acid treated in the same way, afford 
 a slightly weaker acetic acid. 3d, Gently 
 calcined sulphate of iron, or green vitriol, 
 mixed with sugar of lead in the proportion 
 of 1 of the former to l 2\ of the latter, and 
 carefully distilled from a porcelain retort into 
 a cooled receiver, may be also considered a 
 good economical process. Or without dis- 
 tillation, if 100 parts of well dried acetate of 
 lime be cautiously added to 60 parts of strong 
 sulphuric acid, diluted with 5 parts of water, 
 and digested for 24 hours, and strained, a 
 good acetic acid, sufficiently strong for every 
 ordinary purpose, will be obtained. 
 
 The distillation of acetate of copper or of 
 lead per se, has also been employed for ob- 
 taining strong acid. Here, however, the 
 product is mixed with a portion of the fra- 
 grant pyro-acetic spirit, which it is trouble- 
 some to get rid off'. Undoubtedly the best, 
 process for the strong acid is that first de- 
 scribed, and the cheapest the second or third. 
 When of the utmost possible strength its 
 sp. gravity is 1 .062. At the temperature of 
 50° F. it assumes the solid form, crystalliz- 
 ing in oblong rhomboidal plates. It has an 
 extremely pungent odour, affecting the nos- 
 trils and eyes even painfully, when its va- 
 pour is incautiously snuffed up. Its taste is 
 eminently acid and acrid. It excoriates and 
 inflames the skin. 
 
 The purified wood vinegar, which is used 
 for pickles and culinary purposes, has com- 
 monly a specific gravity of about 1.009 ; 
 when it is equivalent in acid strength to good 
 wine or malt vinegar of 1.014. It contains 
 about -I— of its weight of absolute acetic 
 acid, and -gqj of water. An excise duty 
 of 4d. is levied on every gallon of vinegar of 
 the above strength. This, however, is not 
 estimated directly by its sp. gr. but by the 
 sp. gr. which results from its saturation with 
 quick-lime. The decimal number of the sp. 
 gr. of the calcareous acetate, is nearly double 
 that of the pure wood vinegar. Thus 1.009 
 in vinegar, becomes 1.018 in liquid acetate. 
 But the vinegar of fermentation =1.014 will 
 become only 1.025 in acetate, from which, if 
 0.005 be subtracted for mucilage or extrac- 
 tive, the remainder will agree with the density 
 of the acetate from wood. A glass hydio- 
 meter of Fahrenheit’s construction is used 
 for finding the specific gravities. It consists 
 of a globe about 5 inches diameter, haA ing a 
 little ballast ball drawn out beneath, and a 
 stem above of about 3 inches long, contain- 
 ing a slip of paper with a transverse line in 
 the middle, and surmounted with a little cup 
 for receiving we'ights or poises. Fhe expe- 
 riments on which this instrument, called an 
 
 Acctcymctcr , is constructed, have been detailed 
 in the sixtli volume of the Journal of Science. 
 They do not differ essentially from those of 
 Mollerat. The following points were deter- 
 mined by this chemist. The acid of sp. gr. 
 1.063 requires c 2\ times its weight of crys- 
 tallized subcarbonate of soda for saturation, 
 whence M. Thenard regards it as a com- 
 pound of 1 1 of water, and 89 of real acid in 
 the 1 00 parts. Combined with water in the 
 proportion of 100 to 112.2, it does not 
 change its density, but it then remains liquid 
 several degrees below the freezing point of 
 water. By diluting it with a smaller quan- 
 tity of water, its sp. gr. augments, a circum- 
 stance peculiar to this acid. It is 1.079, or 
 at its maximum , when the water forms one- 
 third of the weight of the acid. — Ann. (le 
 Chimie , tom. 66. 
 
 The following table is given by Messrs 
 Taylor as the basis of their acetometer : — 
 
 Revenue proof acid, called by the manu- 
 facturer No. 24. 
 
 sp. gr. 1.0085 contains real acid in 100, 5 
 
 1.0170 
 
 - 
 
 - 
 
 - 
 
 10 
 
 1.0257 
 
 - 
 
 - 
 
 - 
 
 15 
 
 1.0320 
 
 - 
 
 - 
 
 - 
 
 20 
 
 1.0470 
 
 - 
 
 - 
 
 - 
 
 30 
 
 1.05-80 
 
 
 - 
 
 - 
 
 40 
 
 An acetic acid of very considerable strength 
 may also be prepared by saturating perfectly 
 dry charcoal with common vinegar, and then 
 distilling. The water easily comes oft) and 
 is separated at first ; but a stronger heat is 
 required to expel the acid. Or by exposing 
 vinegar to very cold air, or to freezing mix- 
 tures, its water separates in the state of ice, 
 the interstices of which are occupied by a 
 strong acetic acid, which may be procured by 
 draining. The acetic acid or radical vinegar 
 of the apothecaries, in which they dissolve a 
 little camphor, or fragrant essential oil, has 
 a specific gravity of about 1.070. It con- 
 tains fully 1 part of water to 2 of the crys- 
 tallized acid. The pungent smelling salt 
 consists of sulphate of potash moistened with 
 that acid. Acetic acid acts on tin, iron, 
 zinc, copper, and nickel ; and it combines 
 readily with the oxides of many other metals, 
 by mixing a solution of their sulphates with 
 that of an acetate of lead. 
 
 This acid, as it exists in the acetates of 
 barytes and lead, has been analyzed by M. 
 M. Gay Lussac and Thenard, and also by 
 Berzelius. 
 
 Gay Lussac found 50.224 carbone, 5.629 
 hydrogen, and 44.147 oxygen; or, in other 
 terms, 50.224 carbone, 46.911 of water, or 
 its elementary constituents, and 2.865 oxy- 
 gen in excess. 
 
 Berzelius. — 46.83 carb. 6.35 hydr. and 
 46.82 oxygen in the hundred parts. 
 
 Their methods are described under Ve- 
 getable (Analysis). By saturating known 
 
ACI 
 
 ACI 
 
 weights of bases with acetic acid, and ascer- 
 taining the quantity of acetates obtained after 
 cautious evaporation to dryness, Berzelius 
 obtained with lime (3.56) 6.5 for the prime 
 equivalent of acetic acid, and with yellow 
 oxide of lead 6.432. Recent researches, 
 which will be published in a detailed foim, 
 induce me to fix the prime ot acetic acid 
 at 6.63. It would seem to consist, by Ber- 
 zelius’s analysis, of 
 
 3 Primes of hydrogen 3.75 6.2 
 
 4 carbone 30. 46.9 
 
 5 oxygen 30. 46.9 
 
 63.75 100.0 
 
 The quantity of hydrogen is probably 
 much underrated. Acetic acid dissolves 
 resins, gum resins, camphor, and essential 
 oils. Its odour is employed in medicine to 
 relieve nervous headaches, fainting fits, or 
 sickness occasioned by crowded rooms. In 
 a slightly dilute state, its application has been 
 found to check hcmorrhagy from the nostrils. 
 Its anticontagious powers are now little 
 trusted to. It is very largely used in cali- 
 co printing. Moderately rectified pyrolig- 
 nous acid has been recommended for the 
 preservation of animal food ; but the em- 
 pyreumatic taint it communicates to bodies 
 immersed in it, is not quite removed by their 
 subsequent ebullition in water. See Acid, 
 (Pyrolignous) • 
 
 Acetic acid and common vinegar are some- 
 times fraudulently mixed with sulphuric acid 
 to give them strength. This adulteration 
 may be detected by the addition of a little 
 chalk, short of their saturation. With pure 
 vinegar the calcareous base forms a lim- 
 pid solution, but with sulphuric acid a white 
 insoluble gypsum. Muriate of barytes is a 
 still nicer test. British fermented vinegars 
 are allowed by law to contain a little sulphu- 
 ric acid, but the quantity is frequently ex- 
 ceeded. Copper is discovered in vinegars by 
 supersaturating them with ammonia, when 
 a fine blue colour is produced ; and lead by 
 sulphate of soda, hydrosulphurets, sulphuret- 
 ted hydrogen, and gallic acid. None of these 
 should produce any change on genuine vine- 
 gar. See Lead.* 
 
 * Acid (Oxy-acetic). Acetic acid dis- 
 solves deutoxide of barium without effer- 
 vescence. By precipitating the barytes with 
 sulphuric acid, there remains an oxygenized 
 acid, which, being saturated with potash, and 
 heated, allows a great quantity of oxygen gas 
 to escape. There is disengaged at the same 
 time a notable quantity of carbonic acid gas. 
 This shews that the oxygen, when assisted 
 by heat, unites in part with the carbon, and 
 doubtless likewise with the hydrogen of the 
 acid. It is in fact acetic deutoxide of hydrogen. 
 
 Salts consisting of the several bases, united 
 
 in definite proportions to acetic acid, are call- 
 ed acetates. They are characterized by the 
 pungent smell of vinegar, which they exhale 
 on the affusion of sulphuric acid ; and by 
 their yielding on distillation in a moderate 
 red heat a very light, odorous, and combusti- 
 ble liquid called pyro-acetate (spirit) ; which 
 see. They are all soluble in water ; many 
 of them so much so as to be uncrystallizable. 
 About 30 different acetates have been form- 
 ed, of which only a very few have been ap- 
 plied to the uses of life.* 
 
 The acetic acid unites with all the alka- 
 lis and most of the earths, and with these 
 bases it forms compounds, some of which are 
 crystallizable, and others have not yet been 
 reduced to a regularity of figure. The salts 
 it forms are distinguished by their great so- 
 lubility ; their decomposition by fire, which 
 carbonizes them ; the spontaneous alteration 
 of their solution ; and their decomposition 
 by a great number of acids, vrhich extricate 
 from them the acetic acid in a concentrated 
 state. It unites likewise with most of the 
 metallic oxides. 
 
 With barytes the saline mass formed by 
 the acetic acid does not crystallize ; but, 
 when evaporated to dryness, it deliquesces 
 by exposure to air. This mass is not decom- 
 posed by acid of arsenic. By spontaneous 
 evaporation, however, it will crystallize in 
 fine transparent prismatic needles, of a bitter- 
 ish acid taste, which do not deliquesce when 
 exposed to the air, but rather effloresce. 
 
 With potash this acid unites, and forms a 
 deliquescent salt scarcely crystallizable, call- 
 ed formerly foliated earth of tartar, and re- 
 generated tartar. The solution of this salt, 
 even in closely stopped vessels, is spontane- 
 ously decomposed : it deposits a thick, mu- 
 cous, flocculent sediment, at first gray, and 
 at length black ; till at the end of a few 
 months nothing remains in the liquor but 
 carbonate of potash, rendered impure by a 
 little coaly oil. 
 
 With soda it forms a crystallizable salt, 
 which does not deliquesce. This salt has 
 very improperly been called mineral foliated 
 earth. According to the new nomenclature 
 it is acetate of soda. 
 
 The salt formed by dissolving chalk or 
 other calcareous earth in distilled vinegar, 
 formerly called salt of chalk, or fixed vege- 
 table sal ammoniac, and by Bergman calx 
 acetata, has a sharp bitter taste, appears in 
 the form of crystals resembling somewhat 
 ears of corn, which remain dry w hen exposed 
 to the air, unless the acid has been super- 
 abundant, in which case they deliquesce. By 
 distilling without addition, the acid is sepa- 
 rated from the earth, and appears in the form 
 of a white, acid, and inflammable vapour, 
 which smells like acetic ether, somewhat 
 empyreumatic, and which condenses into a 
 reddish brown liquor. 
 
ACI 
 
 ACI 
 
 This liquor, being rectified, is very vola- 
 tile and inflammable : upon adding water it 
 acquires a milky appearance, and drops of oil 
 seem to swim upon the surface. After the 
 thick oil. W lien this earthy salt is mixed 
 with a solution of sulphate of soda, the cal- 
 rectifi cation, a reddish brown liquor remains 
 behind in the retort, together with a black 
 careous earth is precipitated along with the 
 sulphuric acid ; the acetic acid uniting with 
 the soda, makes a crystallizable salt, by the 
 calcination of which to whiteness, the soda 
 may be obtained. This acetic calcareous 
 salt is not soluble in spirit of wine. 
 
 Of the acetate of strontian little is known, 
 but that it has a sweet taste, is very soluble, 
 and is easily decomposed by a strong heat. 
 
 The salt formed by uniting vinegar with 
 ammonia, called by the various names of 
 spirit of Mindererus, liquid sal ammoniac, 
 acetous sal ammoniac, and by Bergman al- 
 kali volatile acetatum, is generally in a 
 liquid state, and is commonly believed not 
 to be crystallizable, as in distillation it pass- 
 es entirely over into the receiver. It ne- 
 vertheless may be reduced into the form of 
 small needle-shaped crystals, when this li- 
 quor is evaporated to the consistence of a 
 syrup. 
 
 Westendorf, by adding his concentrated 
 vinegar to carbonate of ammonia, obtained 
 a pellucid liquid, which did not crystallize ; 
 and which by distillation was totally expelled 
 from the retort, leaving only a white spot. 
 In the receiver under the clear fluid a trans- 
 parent saline mass appeared, which being se- 
 parated from the fluid, and exposed to gentle 
 warmth, melted and threw out abundance of 
 white vapours, and in a few minutes shot in- 
 to sharp crystals resembling those of nitre. 
 These crystals remain unchanged while cold, 
 but they melt at 1 20° and evaporate at about 
 250°. Their taste at first is sharp and then 
 sweet, and they possess the general properties 
 of neutral salts. 
 
 With magnesia the acetic acid unites, 
 and, after a perfect saturation, forms a vis- 
 cid saline mass, like a solution of gum ara- 
 bic, which does not shoot into crystals, but 
 remains deliquescent, has a taste sweetish at 
 first, and afterwards bitter, and is soluble in 
 spirit of wine. The acid of this saline mass 
 may be separated by distillation without ad- 
 dition. 
 
 Glucinc is readily dissolved by acetic acid. 
 This solution, as Vauquelin informs us, does 
 not crystallize ; but is reduced by evapora- 
 tion to a gummy substance, which slowly 
 becomes dry and brittle ; retaining a kind 
 of ductility for a long time. It lias a sac- 
 charine and pretty strongly astringent taste, 
 in which that of vinegar however is distin- 
 guishable. 
 
 Yttria dissolves readily in acetic acid, and 
 the solution yields by evaporation crystals of 
 
 acetate of yttria. These have commonly the 
 form of thick six-sided plates, and are not 
 altered by exposure to the air. 
 
 Alumine, obtained by boiling alum with 
 alkali, and edulcorated by digesting in an 
 alkaline lixivium, is dissolved by distilled 
 vinegar in a very inconsiderable quantity. A 
 considerable quantity of the earth of alum, 
 precipitated by alkali, and edulcorated by 
 hot water in Margraaf’s manner, is soluble 
 in vinegar, and a whitish saline mass is then 
 obtained, which is not crystallizable. From 
 this mass a concentrated acetic acid may be 
 obtained by distillation. Or to a boiling so- 
 lution of alum iu water gradually add a solu- 
 tion of acetate of lead till no further precipi- 
 tate ensues. The sulphate of lead having 
 subsided, decant the supernatant liquor, eva- 
 porate, and the acetate of alum may be ob- 
 tained in small needle-shaped crystals, hav- 
 ing a strong styptic and acetous taste. This 
 salt is of great use in dyeing and calico- 
 printing. See Alumina. 
 
 Acetate of zircone may be formed by pour- 
 ing acetic acid on newly precipitated zir- 
 cone. It has an astringent taste. It does 
 not crystallize ; but, when evaporated to dry- 
 ness, forms a powder, which does not attract 
 moisture from the air. It is verv soluble 
 
 V 
 
 both in water and alcohol ; and is not so 
 easily decomposed by heat as nitrate of zir- 
 cone. 
 
 The acetic acid has no action upon sili- 
 ceous earth ; for the needle-shaped crystals 
 observed by Durande in a mixture of vine- 
 gar with the earth precipitated from a liquor 
 of flints, do not prove the solubility of sili- 
 ceous earth, as Leonhardi observes. 
 
 Concerning the action of vinegar on al- 
 cohol, see Ether. This acid has no effect 
 upon fat oils, except that when distilled to- 
 gether, some kind of mixture takes place, 
 as the Abbe Rozier observes. Neither does 
 distilled vinegar act upon essential oils; but 
 Westendorf ’s concentrated acid dissolved 
 about a sixth part of oil of rosemary, or one 
 half its weight of camphor ; which latter so- 
 lution was inflammable; and the camphor 
 was precipitated from it by adding water. 
 
 Vinegar dissolves the true gums, and part- 
 ly the gum resins, by means of digestion. 
 
 Boerhaave observes, that vinegar by long 
 boiling dissolves the flesh, cartilages, bones, 
 and ligaments of animals. 
 
 Ann (Amniotic). On evaporating the 
 liquor amnii of the cow to one-fourth, Vau- 
 quelin and Buniva found, that crystals form 
 in it by cooling. These are contaminated 
 by a portion of extractive matter, from which 
 they may be freed by washing with a very 
 small quantity of water. These crystals arc 
 white and shining, slightly acid to the taste, 
 redden litmus paper, and are a little more 
 soluble in hot than cold water. They are 
 likewise soluble in alcohol. On ignited 
 
ACI 
 
 ACI 
 
 coals they swell, turn black, give out ammo- 
 nia and prussic acid, and leave a bulky coal. 
 With the alkalis this acid forms very soluble 
 salts, but it does not decompose the carbo- 
 nate without the assistance of heat. It does 
 not precipitate the earthy salts, or the nitrates 
 of mercury, lead, or silver. The acids pre- 
 cipitate it from its combinations with alkalis 
 in a white crystalline powder. Whether it 
 exist in the amniotic liquor of any other ani- 
 mal is not known. 
 
 Acid (Arsenic). The earlier chemists 
 were embarrassed in the determination of the 
 nature of the white sublimate, which is ob- 
 tained during the roasting of cobalt and 
 other metallic ores, known in commerce by 
 the name of arsenic: its solubility in water, 
 its power of combining with metals in their 
 simple state, together with other apparently 
 heterogeneous properties, rendered it difficult 
 to determine whether it ought to be classed 
 with metals or salts. Subsequent discoveries 
 have shown the relation it bears to both. 
 When treated with combustible matter, in 
 close vessels, it sublimes in the metallic form, 
 (See Arsenic); combustion, or any analo- 
 gous process, converts it into an oxide ; and 
 when the combustion is carried still further, 
 the arsenical basis becomes itself converted 
 into an acid. 
 
 We are indebted to the illustrious Scheele 
 for the discovery of this acid, though Mac- 
 quer had before noticed its combinations. 
 It may be obtained by various methods. If 
 six parts of nitric acid be poured on one of 
 the concrete arsenious acid, or white arsenic 
 of the shops, in the pneumato- chemical ap- 
 paratus, and heat be applied, nitrous gas will 
 be evolved, and a white concrete substance, 
 differing in its properties from the arsenious 
 acid, will remain in the retort. This is the 
 arsenic acid. It may equally be procured 
 by means of aqueous chlorine, or by heating 
 concentrated nitric acid with twice its weight 
 of the solution of the arsenious acid in muri- 
 atic acid. The concrete acid should be ex- 
 posed to a dull red heat for a few minutes. 
 In either case an acid is obtained, that does 
 not crystallize, but attracts the moisture of 
 the air, has a sharp caustic taste, reddens 
 blue vegetable colours, is fixed in the fire, 
 and of the specific gravity of 5 . 591 . 
 
 If the arsenic acid be exposed to a red 
 heat in a glass retort, it melts and becomes 
 transparent, but assumes a milky hue on 
 cooling. If the heat be increased, so that 
 the retort begins to melt, the acid boils, and 
 sublimes into the neck of the retort. If a 
 covered crucible be used instead of the glass 
 retort, and a violent heat applied, the acid 
 boils strongly, and in a quarter of an hour 
 begins to emit fumes. Ihese, on being re- 
 ceived in a glass bell, are found to be arseni- 
 ous acid ; and a small quantity of a transpa- 
 rent glass, difficult to fuse, will be found 
 
 lining the sides of the crucible. This is ar- 
 seniate of alumina. 
 
 Combustible substances decompose this 
 acid. If two parts of arsenic acid be mixed 
 with about one of charcoal, the mixture in- 
 troduced into a glass retort, coated, and a 
 matrass adapted to it ; and the retort then 
 gradually heated in a reverberatory furnace, 
 till the bottom is red ; the mass will be in- 
 flamed violently, and the acid reduced, and 
 rise to the neck of the retort in the metallic 
 state mixed with a little oxide and charcoal 
 powder. A few drops of water, devoid of 
 acidity, will be found in the receiver. 
 
 With sulphur the phenomena are diffe- 
 rent. If a mixture of six parts of arsenic 
 acid, and one of powdered sulphur, be di- 
 gested together, no change will take place ; 
 but on evaporating to dryness, and distilling 
 in a glass retort, fitted with a receiver, a 
 violent combination will ensue, as soon as 
 the mixture is sufficiently heated to melt the 
 sulphur. The whole mass rises almost at 
 once, forming a red sublimate,, and sulphur- 
 ous acid passes over into the receiver. 
 
 If pure arsenic acid be diluted with a 
 small quantity of water, and hydrogen gas, 
 as it is evolved by the action of sulphuric 
 acid on iron, be received into this transpa- 
 rent solution, the liquor grows turbid, and a 
 blackish precipitate is formed, which, being 
 well washed with distilled water, exhibits all 
 the phenomena of arsenic. Sometimes, too, 
 a blackish grey oxide of arsenic is found in 
 this process. 
 
 It sulphuretled hydrogen gas be employed 
 instead ot simple hydrogen gas, water and a 
 sulphuret of arsenic are obtained. 
 
 With phosphorus, phosphoric acid is ob- 
 tained, and a phosphuret of arsenic, which 
 sublimes. 
 
 The arsenic acid is much more soluble 
 than the arsenious. According to Lagrange, 
 two parts of water are sufficient for this pur- 
 pose. It cannot be crystallized by any means j 
 but, on evaporation, assumes a thick honey- 
 like consistence. 
 
 No acid has any action upon it: if some 
 of them dissolve it by means of the water 
 that lenders them fluid, they do not produce 
 any alteration in it. The boracic and phos- 
 phoric are vitrifiable with it by means of 
 heat, but without any material alteration in 
 their natures. It phosphorous acid be heat- 
 ed upon it for some time, it saturates it- 
 self with oxygen, and becomes phosphoric acid. 
 
 I he arsenic acid combines with the earthy 
 and alkaline bases, and forms salts very dif- 
 ferent from those furnished by the arsenious 
 acid. 
 
 All these arseniates are decomposable by 
 charcoal, which separates arsenic from them 
 by means of heat. 
 
 * Berzelius, from the result of accurate 
 experiments on the arseniates of lead and 
 
ACI 
 
 ACI 
 
 barytes, infers the prime equivalent of arsenic 
 acid to be 7.25, oxygen being 1.0; but Dr 
 Thomson, from his experiments on the arse- 
 mates ot potash and soda, conceives that the 
 double of the above number ought to be pre- 
 ferred, viz. 14.5. Ann. of Phil. vul. xv. 
 
 On the latter supposition, Berzelius’s in- 
 soluble salts will consist of two primes of 
 base and one of acid ; and the acid itself will 
 be a compound of 5 of oxygen = 5, -f- 9.5 
 of the metallic base == 14.5; for direct ex- 
 periments have shewn it to consist of 100 
 metal, and from 52 to 53 oxygen. But 
 152.5 : 100: : 14.5 : 9.5 nearly. 
 
 All its salts, witli the exception of those of 
 potash, soda, and ammonia, are insoluble in 
 water ; but except arseniate of bismuth, and 
 one or two more, very soluble in an excess 
 of arsenic acid. Hence, after barytes or 
 oxide of lead has been precipitated by this 
 acid, its farther addition redissolves the pre- 
 cipitate. This is a useful criterion of the 
 acid, joined to its reduction to the metallic 
 state by charcoal, and the other characters 
 already detailed. Sulphuric acid decompo- 
 ses the arseniates at a low temperature, but 
 the sulphates are decomposed by arsenic 
 acid at a red heat, owing to the greater fixity 
 of the latter. Phosphoric, nitric, muriatic, 
 and fluoric acids, dissolve, and probably con- 
 vert into subsalts all the arseniates. The 
 whole of them, as well as arsenic acid itself 
 when decomposed at a red heat by charcoal, 
 yield the characteristic garlic smell of the 
 metallic vapour. Nitrate of silver gives a 
 pulverulent brick- coloured precipitate, or, ac- 
 cording to Dr Thomson, a flesh red, with 
 arsenic acid. The acid itself does not dis- 
 turb the transparency of a solution of sul- 
 phate of copper ; but a neutral arseniate gives 
 with it a bluish green precipitate ; with sul- 
 phate of cobalt, a dirty red, and with sulphate 
 of nickel, an apple green precipitate. These 
 precipitates redissolve, on adding a small 
 quantity of the acid which previously held 
 them in solution. Orfila says, that arsenic 
 acid gives, with acetate of copper, a bluish 
 white precipitate, but that it exercises no 
 action either on the muriate or acetate of 
 cobalt; but with the ammonio-muriate it 
 gives a rose-coloured precipitate. Arsenic 
 acid ought to be accounted a more violent 
 poison than even the arsenious. According 
 to Mr Brodie, it is absorbed, and occasions 
 death by acting on the brain and the heart.* 
 
 The arseniate of barytes is insoluble, un- 
 crystallizable, soluble in an excess ot its acid, 
 and decomposable by sulphuric acid, which 
 precipitates a sulphate of barytes. 
 
 Of the arseniate of strontian nothing is 
 known, but no doubt it resembles that ot 
 barytes. 
 
 With lime-water this acid forms a preci- 
 pitate of arseniate of lime, soluble in an excess 
 
 of its base, or in an excess of its acid, though 
 insoluble alone. The acidulous arseniate of 
 lime allbrds on evaporation little crystals, de- 
 composable by sulphuric acid. The same 
 salt may be formed by adding carbonate of 
 lime to the solution of arsenic acid. This 
 acid does not decompose the nitrate or muriate 
 of lime ; but the saturated alkaline arseniates 
 decompose them by double affinity, precipi- 
 tating the insoluble calcareous arseniate. 
 
 If arsenic acid be saturated with magne- 
 sia, a thick substance is formed near the 
 point of saturation. This arseniate of mag- 
 nesia is soluble in an excess of acid ; and on 
 being evaporated takes the form of a jelly, 
 without crystallizing. Neither the sulphate, 
 nitrate, nor muriate of magnesia is decomposed 
 by arsenic acid, though they are by the satu- 
 rated alkaline arseniates. 
 
 Arsenic acid saturated with potash does 
 not easily crystallize. This arseniate, being 
 evaporated to dryness, attracts the humidity 
 of the air, and turns the syrup of violets 
 green, without altering the solution of lit- 
 mus. It fuses into a white glass, and with 
 a strong fire is converted into an acidule, 
 part of the alkali being abstracted by the 
 siLex and alumina of the crucible. If ex- 
 posed to a red heat with charcoal in close 
 vessels it swells up very much, and arsenic is 
 sublimed. It is decomposed by sulphuric 
 acid ; but in the humid way the decomposi- 
 tion is not obvious, as the arsenic acid re- 
 mains in solution. On evaporation, how- 
 ever, this acid and sulphate of potash are ob- 
 tained. 
 
 If arsenic acid be added to the preceding 
 salt, till it ceases to have any effect on the 
 syrup of violets, it will redden the solution 
 of litmus ; and in this state it affords very 
 regular and very transparent crystals, of 
 the figure of quadrangular prisms, termi- 
 nated by two tetra'edral pyramids, the an- 
 gles of which answer to those of the prisms. 
 These crystals are the arsenical neutral salt 
 of Macquer. As this salt differs from the 
 preceding arseniate by its erystallizability, its 
 reddening solution of litmus, its not decom- 
 posing the calcareous and magnesian salts 
 like it, and its capability of absorbing an ad- 
 ditional portion of potash, so as to become 
 neutral, it ought to be distinguished from 
 it by the term of acidulous arseniate of pot- 
 ash. 
 
 With soda in sufficient quantity to satu- 
 rate it, arsenic acid forms a salt crystalliza- 
 ble like the acidulous arseniate of potash. 
 Pelletier says, that the crystals are hexaedral 
 prisms terminated by planes perpendicular 
 to their axis. This neutral arseniate of soda, 
 however, while it differs completely from 
 that of potash in this respect, and in be- 
 coming deliquescent instead of crystallizable 
 on the addition of a surplus portion of arse- 
 
ACI 
 
 A Cl 
 
 nic acid, resembles the arseniate of potash in 
 its decomposition by charcoal, by acids, and 
 by the earths. 
 
 * Combined with ammonia, arsenic acid 
 forms a salt affording rhomboidal crystals 
 analogous to those of the nitrate of soda. 
 The arseniate of ammonia, which is pro- 
 duced likewise in the decomposition of ni- 
 trate of ammonia by arsenious acid, is de- 
 composable in two ways by the action of 
 heat. If it be gently heated, the ammonia 
 is evolved, and the arsenic acid is left puic. 
 If it be exposed to a violent and rapid 
 heat, part of the ammonia and part of the 
 acid reciprocally decompose each other ; 
 water is formed; azotic gas is given out; 
 and the arsenic sublimes in a shining me- 
 tallic form. Magnesia partly decomposes the 
 arseniate of ammonia, and forms a triple salt 
 with a portion of it. 
 
 Arsenic acid saturated with alumina forms 
 a thick solution, which, being evaporated to 
 dryness, yields a salt insoluble in water, and 
 decomposable by the sulphuric, nitric and 
 muriatic acids, as well as by all the other 
 earthy and alkaline bases. The arsenic *acid 
 readily dissolves the alumina of the crucibles 
 in which it is reduced to a state of fusion; 
 and thus it attacks silex also, on which it has 
 no effect in the humid way. 
 
 We know nothing of the combination of 
 this acid with zircone. 
 
 By the assistance of a strong fire, as Four- 
 croy asserts, arsenic acid decomposes the 
 alkaline and earthy sulphates, even that of 
 barytes ; the sulphuric acid flying off in 
 vapour, and the arseniate remaining in the 
 retort. It acts in the same manner on the 
 nitrate, from which it expels the pure acid. 
 It likewise decomposes the muriates at a 
 high temperature, the muriatic acid being 
 evolved in the form of gas, and the arsenic 
 acid combining with their bases, which it 
 saturates; while the arsenious acid is too 
 volatile to have this effect. It acts in the 
 same manner on the fluates, and still more 
 easily on the carbonates, with which, by the 
 assistance of heat, it excites a brisk efferves- 
 cence. Lagrange, however, denies that it 
 acts on any of the neutral salts, except the 
 sulphate of potash and soda, the nitrate of 
 potash, and the muriates of soda and am- 
 monia, and this by means of heat. It does 
 not act on the phosphates, but precipitates 
 the boracic acid from solutions of borates 
 when heated. 
 
 Arsenic acid does not act on gold or 
 platina ; neither does it on mercury or silver 
 without the aid of a strong heat; but it 
 oxidizes copper, iron, lead, tin, zinc, bismuth, 
 antimony, cobalt, nickel, manganese, and 
 arsenic. 
 
 This acid is not used in the arts, at least 
 directly, through indirectly it forms a part 
 
 of some compositions used in dyeing. It is 
 likewise one of the mineralizing acids com- 
 bined by nature with some of the metallic 
 oxides. 
 
 Acid (Arsenious). Fourcroy was the first 
 who distinguished by this name the white 
 arsenic of the shops, which Scheele had 
 proved to be a compound of the metal ar- 
 senic with oxigen, and which the authors 
 of the new r chemical nomenclature had con- 
 sequently termed oxide of arsenic. As, 
 however, it manifestly exhibits the proper- 
 ties of an acid, though in a slight degree, 
 it has a fair claim to the title ; for many 
 oxides and acids are similar in this, that 
 both consist of a base united with oxygen, 
 and the only difference between them is, 
 that the compound in which the acid pro- 
 perties are manifest is termed an acid, and 
 that in which they are not is called an 
 oxide. 
 
 This acid, which is one of the most vi- 
 rulent poisons knowm, frequently occurs in 
 a native state, if not very abundantly; 
 and it is obtained in roasting several ores, 
 particularly those of cobalt. In the chim- 
 neys of the furnaces where this operation 
 is conducted, it generally condenses in thick 
 semi-transparent masses ; though sometimes 
 it assumes the form of a powder, or of little 
 needles, in which state it was formerly called 
 flowers of arsenic. 
 
 The arsenious acid reddens the most 
 sensible blue vegetable colours, though it 
 turns the sirup of violets green. On ex- 
 posure to the air it becomes opaque, and 
 covered with a slight efflorescence. Thrown 
 on incandescent coals, it evaporates in 
 white fumes, with a strong smell of garlic. 
 In close vessels it is volatilized; and, if the 
 heat be strong, vitrified. The result of this 
 vitrification is a transparent glass, capable 
 of crystallizing in tetraedra, the angles of 
 which are truncated. It is easily altered by 
 hydrogen and carbon, which deprive it of its 
 oxygen at a red heat, and reduce the metal, 
 the one forming water, the other carbonic 
 acid, with the oxygen taken from it: as it 
 is by phosphorus, and by sulphur, which 
 are in part converted into acids by its ox- 
 ygen, and in part form an arsenical phos- 
 phuret or sulphuret with the arsenic reduced 
 to the metallic state. Hence Margraaf and 
 Pelletier, who particularly examined the 
 phosphurets of metals, have asserted they 
 might be formed with arsenious acid. Its 
 specific gravity is 3.7. 
 
 It is soluble in thirteen times its weight of 
 boiling water, but requires eighty times its 
 weight ot cold. The solution crystallizes, 
 and the acid assumes the form of regular 
 tetraedrons according to Fourcroy; but, ac- 
 cording to Lagrange, of octaedrons, and 
 these frequently varying in figure by differ- 
 
ACI 
 
 A Cl 
 
 cnt laws of decrement. It crystallizes much 
 better by slow evaporation than by sim- 
 ple cooling. 
 
 * The solution is very acrid, reddens blue 
 colours, unites with the earthy liases, and 
 decomposes the alkaline sulphurets. Arse- 
 nious acid is also soluble in oils, spirits, 
 and alcohol; the last taking up from 1 
 to 2 per cent. It is composed of 9.5 of 
 metal 3 oxygen ; and its prime equiva- 
 lent is therefore 12.5. I)r Wollaston first 
 observed, that when a mixture of it with 
 quick-lime is heated in a glass tube, at a cer- 
 tain temperature, ignition suddenly pervades 
 the mass, and metallic arsenic sublimes. Asar- 
 seniate of lime is found at the bottom of the 
 tube, we perceive thata portion of the arsenious 
 acid is robbed of its oxygen, to complete the 
 acidification of the rest.* 
 
 There are even some metals, which act 
 upon the solution, and have a tendency to 
 decompose the acid, so as to form a black- 
 ish precipitate, in which the arsenic is very 
 slightly oxidized. 
 
 The action of the other acids upon the 
 arsenious is very different from that which 
 they exert on the metal arsenic. By boiling, 
 sulphuric acid dissolves a small portion of it, 
 which is precipitated as the solution cools. 
 The nitric acid does not dissolve it, but 
 by the help of heat converts it into arsenic 
 acid. Neither the phosphoric nor the car- 
 bonic acid acts upon it; yet it enters into 
 a vitreous combination with the phosphoric 
 and boracic acids. The muriatic acid dis- 
 solves it by means of heat, and forms with 
 it a volatile compound, which water preci- 
 pitates ; and aqueous chlorine acidifies it com- 
 pletely, so as to convert it into arsenic acid. 
 
 The arsenious acid combines with the 
 earthy and alkaline bases. I he earthy arse- 
 niates possess little solubility, and hence the 
 solutions of barytes, strontian, and lime, 
 form precipitates with that of arsenious acid. 
 
 This acid enters into another kind of 
 combination with the earths, that formed 
 by vitrification. Though apart of this vola- 
 tile acid sublimes before the glass enters 
 into fusion, part remains fixed in the vitri- 
 fied substance, to which it imparts transpa- 
 rency, a homogeneous density, and consi- 
 derable gravity. The arsenical glasses ap- 
 pear to contain a kind of triple salt, since 
 the salt and alkalis enter into an intimate 
 combination at the instant of fusion, and 
 remain aftenvard perfectly mixed. All of 
 them have the inconvenience of quickly 
 growing dull by exposure to the air. 
 
 & With the fixed alkalis the arsenious acid 
 forms thick arseniates, which do not crys- 
 tallize; which are decomposable by fire, 
 the arsenious acid being volatilized by the 
 heat; and from which all the other acids 
 precipitate this in powder. These saline 
 compounds were formerly termed livers, be- 
 
 cause they were supposed to be analogous to 
 the combinations of sulphur with the alkalis. 
 
 With ammonia it forms a salt capable of 
 crystallization. If this be heated a little, 
 the ammonia is decomposed, the nitrogen is 
 evolved, while the hydrogen, uniting with 
 part of the oxygen of the acid, forms water. 
 
 Neither the earthy nor alkaline arseniates 
 have yet been much examined ; what is 
 knowm of them being only sufficient to dis- 
 tinguish them from the arseniates. 
 
 The nitrates act on the arsenious acid in a 
 very remarkable manner. On treating the 
 nitrates and arsenious acid together, the ni- 
 trous acid, or nitrous vapour, is extricated in 
 a state very difficult to be confined, as Kune- 
 kel long ago observed ; part of its oxygen is 
 absorbed by the arsenious acid ; it is thus 
 converted into arsenic acid, and an arseniate 
 is left in the retort. The same phenomena 
 take place on detonating nitrates with arse- 
 nious acid ; for it is still sufficiently com- 
 bustible to produce a detonation, in which no 
 sparks are seen, it is true, but with commo- 
 tion and effervescence ; and a true arseniate 
 remains at the bottom of the crucible. It 
 was in this way chemists formerly prepared 
 their fixed arsenic, which Avas the acidulous 
 arseniate of potash. The nitrate of ammonia 
 exhibits different phenomena in its decompo- 
 sition by arsenious acid, and requires consi- 
 derable precaution. Pelletier, having mixed 
 equal quantities, introduced the mixture into 
 a large retort of coated glass, placed in a re- 
 verberatory furnace, with a globular receiver. 
 He began with a very slight fire ; for the de- 
 composition is so rapid, and the nitrous va- 
 pours issue with such force, that a portion of 
 the arsenious acid is carried off undecompos- 
 ed, unless you proceed very gently. If due 
 care be taken that the decomposition pro- 
 ceeds more sloAvly, nitrous acid first comes 
 over ; if the fire be continued, or increased, 
 ammonia is next evolved ; and lastly, if the 
 fire he urged, a portion of oxide of arsenic 
 sublimes in the form of a w hite powder, and 
 a vitreous mass remains in the retort, xvhich 
 powerfully attacks and corrodes it. This is 
 arsenic acid. The chlorate of potash, too, 
 by completely oxidizing the arsenious a'dd, 
 converts it into arsenic acid, which, by the 
 assistance of heat, is capable of decompos- 
 ing the muriate of potash that remains. 
 
 The arsenious acid is used in numerous 
 instances in the arts, under the name of 
 white arsenic, or of arsenic simply. In 
 many cases it is reduced, and acts in its me- 
 tallic state. 
 
 Many attempts have been made to intro- 
 duce it into medicine ; but as it is known to 
 he one of the most violent poisons, it is pro- 
 bable that the fear of its bad effects may 
 deprive society of the advantages it might 
 afford in this way. An arseniate of potash 
 
 was extensively used by the late Dr Fowler 
 
 u 
 
ACI 
 
 ACI 
 
 of York, who published a treatise on it, in 
 intermittent and remittent fevers. He like- 
 wise assured the writer, that he had found it 
 extremely efficacious in periodical headach, 
 and as a tonic in nervous and other disorders ; 
 and that he never saw the least ill effect from 
 its use, due precaution being employed in 
 preparing and administering it. Externally 
 it has been employed as a caustic to extirpate 
 cancer, combined with sulphur, with bole, 
 with antimony, and with the leaves of crow- 
 foot ; but it always gives great pain, and is 
 not unattended with danger. Febure’s re- 
 medy was water one pint, extract of hem- 
 lock ^ j , Goulard’s extract tincture of 
 opium 3j, arsenious acid gr. x. With this 
 the cancer was wetted morning and evening ; 
 and at the same time a small quantity of a 
 w-eak solution was administered internally. 
 A still milder application of this kind has 
 been made from a solution of one grain in a 
 quart of water, formed into a poultice with 
 crumb of bread. 
 
 * It has been more lately used as an altera- 
 tive with advantage in chronic rheumatism. 
 The symptoms which shew the system to be 
 arsenijied are thickness, redness, and stiffness 
 of the palpebrce, soreness of the gums, ptya- 
 lism, itching over the surface of the body, 
 restlessness, cough, pain at stomach, and head- 
 ach. When the latter symptoms supervene, 
 the administration of the medicine ought to 
 be immediately suspended. It has also been 
 recommended against chincough ; and has 
 been used in considerable doses with success, 
 to counteract the poison of venomous ser- 
 pents. 
 
 Since it acts on the animal economy as a 
 deadly poison in quantities so minute as to 
 be insensible to the taste when diffused in 
 water or other vehicles, it has been often 
 given with criminal intentions and fatal ef- 
 fects. It becomes therefore a matter of the 
 utmost importance to present a systematic 
 view of the phenomena characteristic of the 
 poison, its operation, and consequences. 1 st, 
 It is a dense substance, subsiding speedily 
 after agitation in water. I find its sp. gr. to 
 vary from 3.728 to 3.730, which is a little 
 higher than the number given above ; 72 
 parts dissolve in 1000 of boiling water, of 
 which 30 remain in it, after it cools. Cold 
 w'ater dissolves, however, only or of 
 
 the preceding quantity. This water makes 
 the syrup of violets green, and reddens litmus 
 paper. Lime water gives a fine white preci- 
 pitate with it of arsenite of lime, soluble in 
 an excess, if the arsenious solution, sulphu- 
 retted hydrogen gas, and hydrosulphuretted 
 wator, precipitate a golden yellow sulphuret 
 
 of arsenic. By this means oTT of arse- 
 mous acid may be detected in water. This 
 sulphuret dried on a filter, and heated in a 
 glass tube with a bit of caustic potash, is de- 
 composed in a few minutes, and converted in- 
 
 to sulphuret of potash, which remains at the 
 bottom, and metallic arsenic of a bright 
 steel lustre, which sublimes, coating the sides 
 of the tube. The hydrosulphurets of alkalis 
 do not affect the arsenious solution, unless a 
 drop or two of nitric or muriatic acid be 
 poured in, when the characteristic golden 
 yellow precipitate falls. Nitrate of silver is 
 decomposed by the arsenious acid, and a very 
 peculiar yellow arsenite of silver precipitates ; 
 which, however, is apt to be redissolved by 
 nitric acid, aud therefore a very minute ad- 
 dition of ammonia is requisite. Even this, 
 however, also, if in much excess, redissolves 
 the silver precipitate. 
 
 As the nitrate of silver is justly regarded as 
 one of the best precipitant tests of arsenic, 
 the mode of using it has been a subject of 
 much discussion. The presence of muriate of 
 soda indeed, in the arsenical solution, ob- 
 structs, to a certain degree, the operation of 
 this reagent. But, that salt is almost always 
 present in the primes vice , and is a usual in- 
 gredient in soups, and other vehicles of the 
 poison. If, after the water of ammonia has 
 been added, by plunging the end of a glass 
 rod dipped in it into the supposed poisonous 
 liquid, we dip another rod into a solution of 
 pure nitrate of silver, and transfer it into the 
 arsenious solution, either a fine yellow cloud 
 will be formed, or at first merely a white 
 curdy precipitate. But at the second or 
 third immersion of the nitrate rod, a central 
 spot of yellow will be perceived surrounded 
 with the white muriate of silver. At the 
 next immersion this yellow cloud on the 
 surface w ill become very conspicuous. Sul- 
 phate of soda does not interfere in the least 
 with the silver test. The ammoniaco-sul- 
 phate, or rather ammoniaco-acetate of cop- 
 per, added in a somewhat dilute state to an 
 arsenious solution, gives a fine grass green 
 and very characteristic precipitate. This 
 green arsenite of copper, w r ell washed, be- 
 ing acted on by an excess of sulphuretted 
 hydrogen w r ater, changes its colour, and be- 
 comes of a brownish red. Ferro- Prussiate 
 of potash changes it into a blood red. Ni- 
 trate of silver converts it into the yellow ar- 
 senite of silver. Lastly, if the precipitate be 
 dried on a filter, and placed on a bit of burn- 
 ing coal, it w ill diffuse a garlic odour. The 
 
 cupreous test will detect yy^oXTO ^ ie 
 weight of the arsenic in water. The voltaic 
 battery, made to act by two wires on a little 
 arsenious solution placed on a bit of window r - 
 glass, developes metallic arsenic at the nega- 
 tive pole ; and if this wire be copper, it will 
 be whitened like tombac. Wo may here re- 
 mark, however, that the most elegant mode 
 of using all these precipitation reagents is 
 upon a plane of glass, a mode practised by Dr 
 Wollaston in general chemical research, to 
 an extent, and with a success, which would 
 be incredible in other hands than his. Con- 
 
ACI 
 
 ACI 
 
 centrate by heat in a capsule the suspected 
 poisonous solution, having previously filter- 
 ed it if necessary. Indeed, if it be very 
 much disguised with animal or vegetable 
 matters, it is better first of all to evaporate 
 to dryness, and by a few drops of nitric acid 
 to dissipate the organic products. The clear 
 liquid being now placed in the middle of the 
 bit of glass, lines are to be drawn out from 
 it in different directions. To one of these 
 a particle of weak ammoniacal water being 
 applied, the weak nitrate of silver may then 
 be brushed over it with a hair pencil. By 
 placing the glass in different lights, either 
 over white paper or obliquely before the eye, 
 the slightest change of tint will be perceived. 
 The ammoniaco-acetate should be applied to 
 another filament of the drop, dent-acetate of 
 iron to a third, weak ammoniaco-acetate of 
 cobalt to a fourth, sulphuretted water to a 
 fifth, lime water to a sixth, a drop of violet 
 syrup to a seventh, and the two galvanic 
 wires at the opposite edges of the whole. 
 Thus with one single drop of solution many 
 exact experiments may be made. But the 
 chief, the decisive trial or experimenlum 
 crucis remains, which is to take a little of the 
 dry matter, mix it with a small pinch of dry 
 black flux, put it into a narrow glass tube 
 sealed at one end, and after cleansing its 
 sides with a feather, urge its bottom with 
 a blow-pipe till it be distinctly red hot for a 
 minute. Then garlic fumes will be smelt, 
 and the steel-lustred coating of metallic ar- 
 senic will be seen in the tube about one- 
 fourth of an inch above its bottom. Cut the 
 tube across at that point by means of a fine 
 file, detach the scale of arsenic with the 
 point of a penknife ; put a fragment of it 
 into the bottom of a small wine glass along 
 with a few drops of ammoniaco-acetate of 
 copper, and triturate them well together for 
 a few minutes with a round-headed glass 
 rod. The mazarine blue colour will soon be 
 transmuted into a lively grass green, while 
 the metallic scale will vanish. Thus we dis- 
 tinguish perfectly between a particle of me- 
 tallic arsenic and one of animalized charcoal. 
 Another particle of the scale maybe placed be- 
 tween two smooth and bright surfaces of cop- 
 per, with a touch of fine oil ; and whilst they 
 are firmly pressed together, exposed to a red 
 heat. The tombac alloy will appear as a white 
 stain. A third particle may be placed on a hit 
 of heated metal, and held a little under the 
 nostrils, when the garlic odour will be recog- 
 nized. No danger can be apprehended, as the 
 fragment need not exceed the tenth of a grain. 
 It is to be observed, that one or two of the 
 precipitation tests may be equivocal from ad- 
 mixtures r of various substances. Thus tinc- 
 ture of ginger gives with the cupreous re- 
 agent a green precipitate ; — and the writer of 
 this article was at first led to suspect from that 
 appearance, that an empirical tincture, put 
 
 into his hands for examination, did contain 
 arsenic. But a careful analysis satisfied him 
 of its genuineness. Tea covers arsenic from 
 the cupreous test. Such poisoned tea be- 
 comes by its addition of an obscure olive or 
 violet red, but yields scarcely any precipi- 
 tate. Sulphuretted hydrogen, however, throws 
 down a fine yellow sulphuret of arsenic. 
 
 Another way of obviating all these 
 sources of fallacy, is to evaporate careful- 
 ly to dryness, and expose the residue to 
 heat in a glass tube. The arsenic sublimes, 
 and may be operated on without ambiguity. 
 Mr Orfila has gone into ample details on the 
 modifications produced by wine, coffee, tea, 
 broth, &c. on arsenical tests, of which a good 
 tabular abstract is given in Mr Thomson’s 
 London Dispensatory. But it is evident that 
 the differences in these menstrua, as also in 
 beers, are so great as to render precipitations 
 and changes of colour by reagents very un- 
 satisfactory witnesses, in a case of life and 
 death. Hence the method of evaporation 
 above described, should never be neglected. 
 Should the arsenic be combined with oil, 
 the mixture ought to be boiled with water, 
 and the oil then separated by the capillary 
 action of wick- threads. If with resinous 
 
 substances, these may he removed by oil of 
 turpentine, not by alcohol, (as directed by 
 Dr Black), which is a good solvent of ar- 
 senious acid. It may moreover be observed, 
 that both tea and coffee should be freed 
 from their taunin by gelatin, which does 
 not act on the arsenic, previous to the use 
 of reagents for the poison. When one 
 part of arsenious acid in watery solution is 
 added to 10 parts of milk, the sulphuretted 
 hydrogen present in the latter, occasions the 
 white colour to pass into a canary yellow' ; 
 the cupreous test gives it a slight green tint, 
 and the nitrate of silver produces no visible 
 change, though even more arsenic be added ; 
 but the hydrosulphurets throw down a golden 
 yellow, with the aid of a few' drops of an 
 acid. The liquid contained in the stomach 
 of a rabbit poisoned with a solution of 3 
 grains of arsenious acid, afforded a white 
 precipitate with nitrate of silver, greyish 
 white with lime water, green with the arn- 
 moniaco-sulphatc, and deep yellow with sul- 
 phuretted hydrogen water. 
 
 The preceding copious description of the 
 habitudes of arsenious acid in different cir- 
 cumstances, is equally applicable to the solu- 
 ble arsenites. Their poisonous operation, ns 
 well as that of the arsenic acid, has been sa- 
 tisfactorily referred by Mr Brodie to the 
 suspension of the functions of the heart and 
 brain, occasioned by the absorption of these 
 substances into the circulation, and their con- 
 sequent determination to the nervous system 
 and the alimentary canal. This proposition 
 was established by numerous experiments on 
 rabbits and dogs. Wounds were inflicted. 
 
ACI 
 
 A Cl 
 
 and arsenic being applied to them, it was 
 found that in a short time death supervened 
 with the same symptoms of inflammation ot 
 the stomach and bowels, as if the poison had 
 been swallowed. He divides the morbid af- 
 fections into three classes: 1st, Uiose de- 
 pending on the nervous system, as palsy at 
 first of the posterior extremities, and then of 
 the rest of the body, convulsions, dilatation 
 of the pupils, and general insensibility : 2d, 
 Those which indicate disturbance in the or- 
 gans of circulation ; for example, the feeble, 
 slow, and intermitting pulse, weak contrac- 
 tions of the heart immediately after death, 
 and the impossibility of prolonging them, as 
 may be done in sudden deaths from other 
 causes, by artificial respiration : 3d, Lastly, 
 Those which depend on lesion of the alimen- 
 tary canal, as the pains of the abdomen, 
 nauseas and vomitings, in those animals which 
 were suffered to vomit. At one time it is 
 the nervous system that is most remarkably 
 affected, and at another the organs of circu- 
 lation. Hence inflammation of the stomach 
 and intestines, ought not to be considered as 
 the immediate cause of death, in the greater 
 number of cases of poisoning by arsenic. 
 However, should an animal not sink under 
 i the first violence of the poison, if the inflam- 
 mation has had time to be developed, there 
 r: is no doubt that it may destroy life. Mr 
 Earle states, that a woman who had taken 
 [arsenic resisted the alarming symptoms which 
 uat first appeared, but died on the fourth day. 
 On opening her body the mucous membrane 
 of the stomach and intestines w r as ulcerated 
 to a great extent. Authentic cases of poison 
 are recorded, where no trace of inflammation 
 
 was perceptible on the primes via;. 
 
 The symptoms of a dangerous dose of 
 :arsenic have been graphically represented by 
 Dr Black : “ The symptoms produced by a 
 dangerous dose of arsenic begin to appear in 
 •a quarter of an hour, or not much longer, 
 after it is taken. First sickness, and great 
 distress at stomach, soon followed by thirst, 
 
 and burning heat in the bowels. Then come 
 
 Dn violent vomiting, and severe colic pains, 
 and excessive and painful purging. This 
 brings on faintings, with cold sweats, and 
 other signs of great debility. To this suc- 
 ceed painful cramps, and contractions of the 
 egs and thighs, and extreme weakness, and 
 ieath.” Similar results have followed the 
 incautious sprinkling of schirrous ulcers with 
 nowdered arsenic, or the application of arse- 
 nical pastes. 1’he following more minute 
 pecification of symptoms is given by Orfila : 
 An austere taste in the mouth ; frequent 
 wtyalism ; continual spitting ; constriction 
 *f the pharynx and (esophagus ; teeth set on 
 dge ; hiccups ; nausea ; vomiting of brown 
 •r bloody matter ; anxiety ; frequent faint- 
 ng fits ; burning heat at the precordia ; in- 
 animation of the lips, tongue, palate, throat, 
 
 stomach ; acute pain of stomach, rendering 
 the mildest drinks intolerable ; black stools 
 of an indescribable feetor ; pulse frequent, 
 oppressed and irregular, sometimes slow and 
 unequal ; palpitation of the heart ; syncope ; 
 unextinguishable thirst; burning sensation 
 over the whole body, resembling a consum- 
 ing fire ; at times an icy coldness ; difficult 
 respiration ; cold sweats ; scanty urine, of a 
 red or bloody appearance ; altered expression 
 of countenance ; a livid circle round the eye- 
 lids ; swelling and itching of the whole 
 body, which becomes covered with livid spots, 
 or with a miliary eruption ; prostration of 
 strength ; loss of feeling, especially in the 
 feet and hands ; delirium ; convulsions, 
 sometimes accompanied with an insupportable 
 priapism ; loss of the hair ; separation of the 
 epidermis; horrible convulsions ; and death.” 
 It is uncommon to observe all these fright- 
 ful symptoms combined in one individual ; 
 sometimes they are altogether wanting, as is 
 shewn by the following case, related by M. 
 Chaussier : A robust man of middle age 
 
 swallowed arsenious acid in large fragments, 
 and died without experiencing other symp- 
 toms than slight syncopes. On opening his 
 stomach, it was found to contain the arseni- 
 ous acid in the very same state in which he 
 had swallowed it. There was no appear- 
 ance whatever of erosion or inflammation in 
 the intestinal canal. Etmuiler mentions a 
 young girl’s being poisoned by arsenic, and 
 whose stomach and bowels were sound to all 
 appearance, though the arsenic was found in 
 them. In general, however, inflammation 
 does extend along the wdiole canal from the 
 mouth to the rectum. The stomach and duo- 
 denum present frequently gangrenous points, 
 escars, perforations of all their coats ; the 
 villous coat in particular, by this and all 
 other corrosive poisons, is commonly detach- 
 ed, as if it were scraped off or reduced into a 
 paste of a reddish brown colour. From 
 these considerations we may conclude, that 
 from the existence or non-existence of intes- 
 tinal lesions, from the extent or seat of the 
 symptoms alone, the physician should not 
 venture to pronounce definitively on the fact 
 of poisoning. 
 
 The result of Mr Brodie’s experiments 
 on brutes, teaches, that the inflammations of 
 th :* intestines and stomach are more severe 
 when the poison has been applied to an ex- 
 ternal wound, than when it has been thrown 
 into the stomach itself. The best remedies 
 against this poison in the stomach, are copi- 
 ous draughts of bland liquids of a mucilagi- 
 nous consistence to inviscatc the powder, 
 so as to procure its complete ejection by vo- 
 miting. Sulphuretted hydrogen condensed 
 in water, is the only direct antidote to its 
 virulence ; Orfila having found, that when 
 dogs were made to swallow that liquid, after 
 getting a poisonous dose of arsenic, they re- 
 
ACI 
 
 A Cl 
 
 covered, though their aesophagus was tied to 
 prevent vomiting ; but when the same dose 
 of poison was administered in the same cir- 
 cumstances, without the sulphuretted water, 
 that it proved fatal. When the viscera are 
 to be subjected after death to chemical inves- 
 tigation, a ligature ought to be thrown round 
 the oesophagus and the beginning of the 
 colon, and the intermediate stomach and in- 
 testines removed. Their liquid contents 
 should be emptied into a basin ; and there- 
 after a portion of hot water introduced into 
 the stomach, and worked thoroughly up 
 and down this viscus , as w r ell as the intes- 
 tines. 
 
 After filtration, a portion of the liquid 
 should be concentrated by evaporation in a 
 porcelain capsule, and then submitted to the 
 proper reagents above described. We may 
 also endeavour to extract from the stomach 
 by digestion in boiling water, with a little 
 ammonia, the arsenical impregnation, which 
 has been sometimes known to adhere in 
 minute particles with wonderful pertinacity. 
 This precaution ought therefore to be at- 
 tended to. The heat will dissipate the ex- 
 cess of ammonia in the above operation ; 
 whereas by adding potash or soda, as pre- 
 scribed by the German chemists, we intro- 
 duce animal matter in alkaline solution, 
 which complicates the investigation. 
 
 The matters rejected from the patient’s 
 bowels before death should not be neglected. 
 These, generally speaking, are best treated 
 by cautious evaporation to dryness ; but w r e 
 must beware of heating the residuum to 
 400°, since at that temperature, and perhaps 
 a little under it, the arsenious acid itself 
 sublimes. 
 
 Vinegar, hydroguretted alkaline*sulphu- 
 rets, and oils, are of no use as counterpoisons. 
 Indeed, when the arsenic exists in substance 
 in the stomach, even sulphuretted hydrogen 
 water is of no avail, however effectually it 
 neutralize an arsenious solution. Syrups, 
 linseed tea, decoction of mallows, or traga- 
 canth, and warm milk, should be administer- 
 ed as copiously as possible, and vomiting 
 provoked by tickling the fauces with a fea- 
 ther. Clysters of a similar nature may be 
 also employed. Many persons have escaped 
 death by having taken the poison mixed with 
 rich soups ; and it is well known, that when 
 it is prescribed as a medicine, it acts most 
 beneficially when taken soon after a meal. 
 These facts have led to the prescription of 
 butter and oils, the use of which is, however, 
 not advisable, as they screen the arsenical 
 particles from more proper menstrua, and 
 even appear to aggravate its virulence. Mor- 
 gagni, in his great work on the seats and 
 causes of disease, states, that at an Italian 
 feast the dessert was purposely sprinkled over 
 with arsenic instead of flour. Those of the 
 guests who had previously ate and drank lit- 
 
 tle, speedily perished ; those who had their 
 stomachs well filled, were saved by vomiting, 
 lie also mentions the case of three children 
 who ate a vegetable soup poisoned with 
 arsenic. One of them, who took only 
 two spoons-full, had no vomiting, and died ; 
 the other two, who had eaten the rest, vo- 
 mited, and got well. Should the poisoned 
 patient be incapable of vomiting, a tube of 
 caoutchoric, capable of being attached to a 
 syringe, may be had recourse to. The tube 
 first serves to introduce the drink, and to 
 withdraw it after a few instants. 
 
 The following tests of arsenic and corro- 
 sive sublimate have been lately proposed by 
 Brugnatelli : Take the starch of wheat 
 
 boiled in water until it is of a proper consis- 
 tence, and recently prepared ; to this add a 
 sufficient quantity of iodine to make it of a 
 blue colour ; it is afterwards to be diluted 
 with pure water until it becomes of a beau- 
 tiful azure. If to this, some drops of a 
 watery solution of arsenic be added, the 
 colour changes to a reddish hue, and finally 
 vanishes. The solution of corrosive subli- 
 mate poured into iodine and starch, produces 
 almost the same change as arsenic ; but if 
 to the fluid acted on by the arsenic w r e add 
 some drops of sulphuric acid, the original 
 blue colour is restored with more than its 
 original brilliancy, while it does not restore 
 the colour to the corrosive sublimate mix- 
 ture.* 
 
 Acm (Benzoic). This acid was first de- 
 scribed in 1608, by Blaise de Vigenere, in 
 his Treatise on Fire and Salt, and has been 
 generally known since by the name of flow- 
 ers of benjamin or benzoin, because it was 
 obtained by sublimation from the resin of 
 tlxis name. As it is still most commonly 
 procured from this substance, it has preserv- 
 ed the epithet of benzoic, though known to 
 be a peculiar acid, obtainable not from ben- 
 zoin alone, but from different vegetable bal- 
 sams, vanello, cinnamon, ambergris, the urine 
 of children, frequently that of adults, and 
 always, according to Fourcroy and Yauque- 
 lin, though Giese denies this, that of qua- 
 drupeds living on grass and hay, particularly 
 the camel, the horse, and the cow. There 
 is reason to conjecture that many vegetables, 
 and among them some of the grasses, con- 
 tain it, and that it passes from them into the 
 urine. Fourcroy and Vauquelin found it 
 combined with potash and lime in the liquor 
 of dunghills, as well as in the urine of the 
 quadrupeds above mentioned ; and they 
 strongly suspect it to exist in the anthoxan- 
 thum odoratum, or sweet-scented vernal - 
 grass, from which hay principally derives its 
 fragrant smell. Giese, however, could find 
 none either in this grass or in oats. 
 
 The usual method of obtaining it affords 
 a very elegant and pleasing example of the 
 chemical process of sublimation. For this 
 
ACI 
 
 ACI 
 
 purpose a thin stratum of powdered benzoin 
 is spread over the bottom of a glazed earthen 
 pot, to which a tall conical paper covering is 
 fitted : gentle heat is then to he applied to 
 the bottom of the pot, which fuses the ben- 
 zoin, and fills the apartment with a fragrant 
 smell, arising from a portion of essential oil 
 and acid of benzoin, which are dissipated in- 
 to the air, at the same time the acid itself 
 rises very suddenly in the paper head, which 
 may be occasionally inspected at the top, 
 though with some little care, because the 
 fumes will excite coughing. This saline 
 sublimate is condensed in the form of long 
 needles, or straight filaments of a white co- 
 lour, crossing each other in all directions. 
 When the acid ceases to rise, the cover may 
 be changed, a new one applied, and the heat 
 raised : more flowers of a yellowish colour 
 will then rise, which require a second sub- 
 limation to deprive them of the empyreuma- 
 tic oil they contain. 
 
 The sublimation of the acid of benzoin 
 may be conveniently performed by substi- 
 tuting an inverted earthen pan instead of 
 the paper cone. In this case the two pans 
 should be made to fit, by grinding on a stone 
 with sand, and they must be luted together 
 with paper dipped in paste. This method 
 seems preferable to the other, where the pre- 
 sence of the operator is required elsewhere ; 
 but the paper head can be more easily in- 
 spected and changed. The heat applied 
 must be very gentle, and the vessels ought 
 not to be separated till they have become 
 cool. 
 
 The quantity of acid obtained in these 
 methods differs according to the manage- 
 ment, and probably also from difference of 
 purity, and in other respects of the resin it- 
 self. It usually amounts to no more than 
 about one-eighth part of the whole weight. 
 Indeed Scheele says, not more than a tenth 
 or twelfth. The whole acid of benzoin is 
 obtained with greater certainty in the humid 
 process of Scheele : this consists in boiling 
 the powdered resin with lime-water, and 
 afterwards separating the lime by the addi- 
 tion of muriatic acid. Twelve ounces of 
 water are to be poured upon four ounces of 
 slaked lime ; and, after the ebullition is over, 
 eight pounds, or ninety-six ounces, more of 
 water are to be added : a pound of finely- 
 powdered benzoin being then put into a tin 
 vessel, six ounces of the lime-water are to be 
 added, and mixed w-ell w ith the powder ; 
 and afterwards the rest of the lime-water 
 in the same gradual manner, because the 
 benzoin would coagulate into a mass, if the 
 whole were added at once. This mixture 
 must be gently boiled for half an hour with 
 constant agitation, and afterw ards suffered to 
 cool and subside during an hour. The su- 
 pernatant liquor must be decanted, and the 
 residuum boiled with eight pounds more of 
 
 lime-water ; after which the same process is 
 to be once more repeated : the remaining 
 pow'der must be edulcorated on the filter by 
 affusions of hot water. Lastly, all the de- 
 coctions, being mixed together, must be eva- 
 porated to two pounds, and strained into a 
 glass vessel. 
 
 This fluid consists of the acid of benzoin 
 combined w r ith lime. After it is become 
 cold, a quantity of muriatic acid must be 
 added, with constant stirring, until the fluid 
 tastes a little sourish. During this time the 
 last-mentioned acid unites with the lime, 
 and forms a soluble salt, which remains sus- 
 pended, while the less soluble acid of ben- 
 zoin, being disengaged, falls to the bottom 
 in powder. By repeated affusions of cold 
 water upon the filter, it may be deprived of 
 the muriate of lime and muriatic acid, with 
 which it may happen to be mixed. If it be 
 required to have a shining appearance, it 
 may be dissolved in a small quantity of boil- 
 ing water, from which it will separate in 
 silky filaments by cooling. By this process 
 the benzoic acid may be procured from other 
 substances, in which it exists. 
 
 * Mr Hatchell has shewn, that, by digest- 
 ing benzoin in hot sulphuric acid, very beau- 
 tiful crystals are sublimed. This is perhaps 
 the best process for extracting the acid. If 
 w r e concentrate the urine of horses or cows, 
 and pour muriatic acid into it, a copious 
 precipitate of benzoic acid takes place. This 
 is the cheapest source of it.^ 
 
 As an economical mode of obtaining this 
 acid, Fourcroy recommends the extraction of 
 it from the water that drains from dunghills, 
 cowhouses, and stables, by means of the mu- 
 riatic acid, which decomposes the benzoate of 
 lime contained in them, and separates the 
 benzoic acid, as in Seheele’s process. He 
 confesses the smell of the acid thus obtained 
 differs a little from that of the acid extracted 
 from benzoin ; but this, lie says, may be re- 
 medied, by dissolving the acid in boiling 
 water, filtering the solution, letting it cool, 
 and thus suffering the acid to crystallize, and 
 repeating this operation a second time. 
 
 Mr Accum found the benzoic acid which 
 he obtained from venello-pods contaminated 
 w ith a yellow' colouring matter, from which 
 it could not be freed by repeated solutions 
 and crystallizations ; but by boiling with 
 charcoal powder, the acid was rendered per- 
 fectly pure. 
 
 The acid of benzoin is so inflammable, 
 that it burns with a clear yellow flame with- 
 out the assistance of a wick. The sublimed 
 flowers in their purest state, as white as or- 
 dinary writing-paper, were fused into a clear 
 transparent yellowish fluid, at the two hun- 
 dred-and- thirtieth degree of Fahrenheit’s 
 thermometer, and at the same time began to 
 rise in sublimation. It is probable that a 
 heat somewhat greater than ibis may be re- 
 
ACI 
 
 AC I 
 
 quircd to separate it from the resin. It is 
 strongly disposed to take the crystalline form 
 in cooling. The concentrated sulphuric and 
 nitric acids dissolve this concrete acid, and it 
 is again separated, without alteration, by add- 
 ing water. Other acids dissolve it by the 
 assistance of heat, from which it separates by 
 cooling, unchanged. It is plentifully solu- 
 ble in ardent spirit, from which it may like- 
 wise be separated by diluting the spirit with 
 water. It readily dissolves in oils, and in 
 melted tallow. If it be added in a small 
 proportion to this last fluid, part of the tal- 
 low congeals before the rest, in the form of 
 white opaque clouds. If the quantity of acid 
 be more considerable, it separates in part by 
 cooling, in the form of needles or feathers. 
 It did not communicate any considerable 
 degree of hardness to the tallow, which was 
 the object of this experiment. When the 
 tallow w f as heated nearly to ebullition, it 
 emitted fumes which affected the respiration, 
 like those of the acid of benzoin, but did not 
 possess the peculiar and agreeable smell of 
 that substance, being probably the sebacic 
 acid. A stratum of this tallow, about one- 
 twentieth of an inch thick, w r as fused upon a 
 plate of brass, together with other fat sub- 
 stances, with a view to determine its relative 
 disposition to acquire and retain the solid 
 state. After it had cooled it was left upon 
 the plate, and, in the course of some weeks, 
 it gradually became tinged throughout of a 
 blueish green colour. If this circumstance 
 be not supposed to have arisen from a solu- 
 tion of the copper during the fusion, it seems 
 a remarkable instance of the mutual action 
 of two bodies in the solid state, contrary to 
 that axiom of chemistry which affirms, that 
 bodies do not act on each other, unless one 
 or more of them be in the fluid state. Tal- 
 low itself, how'ever, has the same effect. 
 
 Pure benzoic acid is in the form of a light 
 powder, evidently crystallized in fine needles, 
 the figure of which is difficult to be deter- 
 mined from their smallness. It has a white 
 and shining appearance ; but when contami- 
 nated by a portion of volatile oil, is yellow 
 or brownish. It is not brittle as might be 
 expected from its appearance, but has rather 
 a kind of ductility and elasticity, and, on 
 rubbing in a mortar, becomes a sort of paste. 
 Its taste is acrid, hot, acidulous, and hitter. 
 It reddens the infusion of litmus, but not 
 syrup of violets. It has a peculiar aromatic 
 smell, but not strong unless heated. This, 
 however, appears not to belong to the acid ; 
 for Mr Giese informs ns, that on dissolving 
 the benzoic acid in as little alcohol as possi- 
 ble, filtering the solution, and precipitating 
 by w r ater, the acid will be obtained pure, and 
 void of smell, the odorous oil remaining dis- 
 solved in the spirit. Its specific gravity is 
 0.667. It is not perceptibly altered by the 
 air, and has been kept in an open vessel 
 
 twenty years without losing any of its weight. 
 None of the combustible substances have 
 any effect on it ; but it may be refined by 
 mixing it with charcoal powder and sublim- 
 ing, being thus rendered much whiter and 
 better crystallized. It is not very soluble 
 in water. Wenzel and Lichtenstein say four 
 hundred parts of cold water dissolve but one, 
 though the same quantity of boiling water 
 dissolves twenty parts, nineteen of which se- 
 parate on cooling. 
 
 The benzoic acid unites without much 
 difficulty with the earthy and alkaline bases. 
 
 The benzoate of barytes is soluble, crystal- 
 lizes tolerably well, is not affected by expo- 
 sure to the air, but is decomposable by fire, 
 and by the stronger acids. That of lime is very 
 soluble in water, though much less in cold 
 than in hot, and crystallizes on cooling. It 
 is in like manner decomposable by the acids 
 and by barytes. The benzoate of magnesia 
 is soluble, crystallizable, a little deliquescent, 
 and more decomposable than the former. 
 That of alumina is very soluble, crystallizes 
 in dendrites, is deliquescent, has an acerb 
 and bitter taste, and is decomposable by fire, 
 and even by most of the vegetable acids. 
 The benzoate of potash crystallizes on cooling 
 in little compacted needles. All the acids 
 decompose it, and the solution of barytes and 
 lime form with it a precipitate. The ben- 
 zoate of soda is very crystallizable, very solu- 
 ble, and not deliquescent like that of potash, 
 but it is decomposable by the same means. 
 It is sometimes found native in the urine of 
 graminivorous quadrupeds, but by no means 
 so abundantly as that of lime. The benzoate 
 of ammonia is volatile, and decomposable by 
 all the acids and all the bases. The solu- 
 tions of all the benzoates, when drying on the 
 sides of a vessel wetted w ith them, form den- 
 dritical crystallizations. 
 
 Trommsdorf found in his experiments, 
 that benzoic acid united readily with metal- 
 lic oxides. 
 
 From the chemical properties of this acid, 
 it appears to differ from the other vegetable 
 acids in the nature and properties of the prin- 
 ciples that constitute its radical. Its odour, 
 volatility, combustibility, great solubility in 
 alcohol, and little solubility in water, for- 
 merly occasioned it to be considered as an 
 oily acid ; and have led modern chemists 
 to conceive, that it contains a large quantity 
 of hydrogen in its composition, and that 
 it is in the superabundance of this combusti- 
 ble principle its difference from the other ve- 
 getable acids consists. Its solubility in the 
 pow-crful acids, and its subsequent separation, 
 indicate that its principles are not easily se- 
 parable from each other. Attempts have 
 been made to decompose it by repeated ab- 
 straction of nitric acid : the nitric acid rises 
 first, scarcely altered except toward the end 
 of the process, when nitrous gas comes over ; 
 
A Cl 
 
 ACI 
 
 and the acid of benzoin is afterwards sub- 
 limed with little alteration. By repeating 
 the process, however, it is said to become 
 more fixed, and at length to afford a few 
 drops of an acid resembling the oxalic in 
 its properties. 
 
 * Berzelius, from the benzoate of lead, de- 
 duces the weight of the prime equivalent of 
 benzoic acid to be 14.893; and it consists 
 per cent of 5.16 hydrogen, 74.41 carbon, 
 and 20.45 oxygen. 
 
 The benzoates are all decomposable by 
 heat, which, when it is slowly applied, first 
 separates a portion of the acid in a vapour, 
 that condenses in crystals. The soluble 
 benzoates are decomposed by the powerful 
 acids, which separate their acid in a crystal- 
 line form. The benzoate of ammonia has 
 been proposed by Berzelius as a reagent for 
 precipitating red oxide of iron from perfectly 
 neutral solutions. According to my experi- 
 ments, 21.5 of ammonia take 15.7 of crystal- 
 lized benzoic acid for neutralization.* 
 
 The benzoic acid is occasionally used in 
 medicine, but not so much as formerly ; and 
 enters into the composition of the campho- 
 rated tincture of opium of the London col- 
 lege, heretofore called paregoric elixir. 
 
 * Acid (Boletic). An acid extracted from 
 the expressed juice of the boletus pseudo ig- 
 niarius by M. Braconnot. This juice con- 
 centrated to a syrup by a very gentle heat, 
 was acted on by strong alcohol. What re- 
 mained was dissolved in water. When ni- 
 trate of lead was dropped into this solution, 
 a white precipitate fell, which, after being 
 well washed with water, was decomposed by 
 a current of sulphuretted hydrogen gas. Two 
 different acids were found in the liquid after 
 filtration and evaporation. One in perma- 
 nent crystals was boletic acid ; the other 
 was a small proportion of phosphoric acid. 
 The former was purified by solution in al- 
 cohol, and subsequent evaporation. 
 
 It consists of irregular four-sided prisms, 
 of a white colour, and permanent in the air. 
 Its taste resembles cream of tartar ; at the 
 temperature of 68° it dissolves in 1 80 times 
 its weight of water, and in 45 of alcohol. 
 Vegetable blues are reddened by it. Red 
 oxide of iron, and the oxides of silver and 
 mercury, are precipitated by it from their so- 
 lutions in nitric acid ; but lime and barytes 
 waters are not affected. It sublimes when 
 heated, in white vapours, and is condensed 
 in a white powder. Ann. de Chimie , ixxx. * 
 
 Acid (Boracic). Hie salt composed of 
 this acid and soda, had long been used both 
 in medicine and the arts under the name of 
 borax, when Homberg first obtained the acid 
 separate in 1702, by distilling a mixture of 
 boi ax and sulphate of iron. lie supposed, 
 however, that it w r as a product of the latter; 
 and gave it the name of volatile narcotic salt 
 of vitriol, or sedative salt. Lcmery the younger 
 
 soon after discovered, that it could be obtain- 
 ed from borax equally by means of the nitric 
 or muriatic acid; Geollroy detected soda in 
 borax; and at length Baron proved by a 
 number of experiments, that borax is a com* 
 pound of soda and a peculiar acid. Cadet 
 has disputed this; but he has merely showm, 
 that the borax of the shops is frequently 
 contaminated with copper ; and Struve and 
 Exchaquet have endeavoured to prove that 
 the boracio and phosphoric acids are the 
 same ; yet their experiments only show, that 
 they resemble each other in certain respects, 
 not in all. 
 
 To procure the acid, dissolve borax in hot 
 water, and filter the solution ; then add sul- 
 phuric acid by little and little, till the li- 
 quid has a sensibly acid taste. Lay it aside 
 to cool, and a great number of small shining 
 laminated crystals will form. These are 
 the boracic acid. They are to be washed 
 with cold water, and drained upon brown 
 paper. 
 
 Boracic acid thus procured is in the form 
 of thin irregular hexagonal scales, of a sil- 
 very wdiiteness, having some resemblance to 
 spermaceti, and the same kind of greasy feel. 
 It has a sourish taste at first, then makes a 
 bitterish cooling impression, and at last 
 leaves an agreeable sweetness. Pressed be- 
 tween the teeth, it is not brittle but ductile. 
 It has no smell ; but, when sulphuric acid 
 is poured on it, a transient odour of musk is 
 produced. Its specific gravity in the form 
 of scales is 1.479 ; after it has been fused, 
 1.805. Tt is not altered by light. Exposed 
 to the fire it swells up, from losing its water 
 of crystallization, and in this state is called 
 calcined boracic acid. It melts a little be- 
 fore it is red-hot, without perceptibly losing 
 any water, but it does not flow freely till it 
 is red, and then less than the borate of soda. 
 Ater this fusion it is a hard transparent glass, 
 becoming a little opaque on exposure to the 
 air, without abstracting moisture from it, and 
 unaltered in its properties, for on being dis- 
 solved in boiling water it crystallizes as be- 
 fore. I his glass is used in the composition 
 of false gems. 
 
 Boiling water scarcely dissolves one-fiftieth 
 part, and cold water much less. When this 
 solution is distilled in close vessels, part of 
 the acid rises with the water, and crystallizes 
 in the receiver. It is more soluble in alco- 
 hol, and alcohol containing it burns with a 
 gtcen flame, as docs paper dipped in a solu- 
 tion of boracic acid. 
 
 Neither oxygen gas, nor the simple com- 
 bustibles, noi the common metals, produce 
 any change upon boracic acid, as far as is at 
 present known. If mixed with finely pow- 
 dered charcoal, it is nevertheless capable of 
 vitrification ; and with soot it melts into a 
 black bitumen-like mass, which however is 
 soluble in water, and cannot easily be bum- 
 
ACI 
 
 ACI 
 
 ed to ashes, but sublimes in part. With the 
 assistance of a distilling heat it dissolves in 
 oils, especially mineral oils; and with these 
 it yields fluid and solid products, which im- 
 part a green colour to spirit of wine. When 
 rubbed with phosphorus it docs not prevent 
 its inflammation, but an earthy yellow matter 
 is left behind. It is hardly capable of ox- 
 id ing or dissolving any of the metals except 
 iron and zinc, and perhaps copper; but it 
 combines with most of the metallic oxides, 
 as it does with the alkalis, and probably with 
 all the earths, though the greater part of its 
 combinations have hitherto been little exa- 
 mined. It is of great use in analyzing stones 
 that contain a fixed alkali. 
 
 * Crystallized boracic acid is a compound of 
 .57 parts of acid and 43 of water. The ho- 
 nour of discovering the radical of boracic acid, 
 is divided between Sir H. Davy and M. M. 
 Gay Lussac and Thenard. The first, on ap- 
 plying his powerful voltaic battery to it, ob- 
 tained a chocolate-coloured body in small 
 quantity ; but the tAvo latter chemists, by 
 acting on it with potassium in equal quan- 
 tities, at a low red heat, formed boron and sub- 
 borate of potash. For a small experiment a 
 glass tube will serve, but on a greater scale 
 a copper tube is to be preferred. The pot- 
 assium and boracic acid, perfectly dry, should 
 be intimately mixed before exposing them to 
 heat. On withdrawing the tube from the 
 fire, allowing it to cool, and removing the 
 cork which loosely closed its mouth, we then 
 pour successive portions of water into it, till 
 we detach or dissolve the whole matter. The 
 water ought to be heated each time. The 
 whole collected liquids are allowed to settle; 
 when, after washing the precipitate till the 
 liquid ceases to affect syrup of violets, we 
 dry the boron in a capsule, and then put it 
 into a phial out of contact of air. Boron is 
 solid, tasteless, inodorous, and of a green- 
 ish brown colour. Its specific gravity is 
 somewhat greater than water. The prime 
 equivalent of boracic acid has been inferred 
 from the borate of ammonia, to be about 2.7 
 or 2.8; oxygen being 1.0; and it probably 
 consists of 2.0 of oxygen + 0.8 of boron. 
 But by M. M. G. Lussac and Thenard, the 
 proportions would be 2 of boron to 1 of oxy- 
 gen.* 
 
 The boracic acid has a more powerful at- 
 traction for lime, than for any other of the 
 bases, though it does not readily form borate 
 of lime by adding a solution of it to lime- 
 water, or decomposing by lime-water the 
 soluble alkaline borates. In either case an 
 insipid white powder, nearly insoluble, which 
 is the borate of lime, is however precipitated. 
 The borate of barytes is likewise an insoluble, 
 tasteless, white powder. 
 
 Bergman has observed, that magnesia, 
 thrown by little and little into a solution of 
 boracic acid, dissolved slowly, and the liquor 
 
 on evaporation afforded granulated crystals 
 without any regular form : that these crystals 
 were fusible in the fire without being decom- 
 posed : but that alcohol was sufficient to se- 
 parate the boracic acid from the magnesia. 
 If however some of the soluble magnesian 
 salts be decomposed by alkaline borates in a 
 state of solution, an insipid and insoluble 
 borate of magnesia is thrown down. It is 
 probable, therefore, that Bergman’s salt was 
 a borate of magnesia dissolved in an excess of 
 boracic acid ; which acid being taken up by 
 the alcohol, the true borate of magnesia was 
 precipitated in a white powder, and mistaken 
 by him for magnesia. 
 
 One of the best known combinations of 
 this acid is the native magnesio-calcareous 
 borate of Kalkberg, near Lunenburg : the 
 wurfelstein of the Germans, cubic quartz of 
 various mineralogists, and boracite of Kir- 
 wan. It is of a greyish white colour, some- 
 times passing into the greenish white, or 
 purplish. Its figure is that of a cube, incom- 
 plete on its twelve edges, and at four of its 
 solid angles ; the complete and incomplete 
 angles being diametrically opposite to each 
 other. The surfaces generally appear cor- 
 roded. It strikes fire with steel, and scratches 
 glass. Its specific gravity is 2.566, as de- 
 termined by M. Westrumb, who found it to 
 be composed of boracic acid 0.68, magnesia 
 0.1305, lime 0.11 ; with alumina 0.01, silex 
 0.02, and oxide of iron 0.0075, all of which 
 he considers as casual. Its most remarkable 
 property, discovered by Haiiy, is, that like 
 the tourmalin it becomes electric by heat, 
 though little so by friction ; and it has four 
 electric poles, the perfect angles always exhi- 
 biting negative electricity, and the truncated 
 angles positive. 
 
 Since the component parts of this native 
 salt have been know'n, attempts have been 
 made to imitate it by art ; but no chemist 
 has been able, by mixing lime, magnesia, 
 and boracic acid, to produce any thing but 
 a pulverulent salt, incapable of being dis- 
 solved, or exhibited in the crystallized form, 
 and with the hardness of the borate of Kalk- 
 berg. 
 
 It has lately been denied, however, that 
 this compound is really a triple salt. \ au- 
 quelin, examining this substance with Mr 
 Smith, who had a considerable quantity, 
 found the powder to effervesce with acids ; 
 and therefore concluded the lime to be no 
 essential part of the compound. They at- 
 tempted, by using weak acids much diluted, 
 to separate the carbonate from the borate; 
 but they did not succeed, because the acid 
 attacked the borate likewise, though feebly. 
 I\I. Stromager having afterwards supplied 
 Vauquelin with some transparent crystals, 
 which did not effervesce with acids, he mix- 
 ed this powder with muriatic acid, and. when 
 the solution was effected by means of heat, 
 
ACI 
 
 ACI 
 
 evaporated to dryness to expel the excess or 
 acid. By solution in a small quantity of 
 cold distilled water, he separated most of 
 the boracic acid ; and, having diluted 
 the solution, added a certain quantity of 
 oxalate of ammonia, hut no sign of the exist- 
 ence of lime appeared. To ascertain that 
 the precipitation of the lime was not pie- 
 vented by the presence of the small quantity 
 of boracic acid, he mixed with the solution 
 a very small portion of muriate 01 lime, and 
 a cloudiness immediately ensued through the 
 whole. Hence he infers, that the opacity 
 of the magnesian borate is occasioned by car- 
 bonate of lime interposed between its particles, 
 and that the borate in transparent crystals 
 contains none. 
 
 The borate of potash is but little known, 
 though it is said to be capable of supplying 
 the place of that of soda in the arts ; but 
 more direct experiments are required to esta- 
 blish this effect. Like that, it is capable of 
 existing in two states, neutral and with ex- 
 cess of base, but it is not so crystallizable, 
 and assumes the form of parallelopipeds. 
 
 With soda the boracic acid forms two dif- 
 ferent salts. One, in which the alkali is 
 more than triple the quantity necessary to 
 saturate the acid, is of considerable use in 
 the arts, and has long been known by the 
 name of borax ; under which its history and 
 an account of its properties will be given. 
 The other is a neutral salt, not changing the 
 syrup of violets green like the borate with ex- 
 cess of base ; differing from it in taste and 
 solubility; crystallizing neither so readily, 
 nor in the same manner ; not efflorescent 
 like it ; but like it fusible into a glass, and 
 capable of being employed for the same pur- 
 poses. This salt may be formed by saturat- 
 ing the superabundant soda in borax with 
 some other acid, and then separating the two 
 salts : but it is obviously more eligible, to 
 saturate the excess of soda with an additional 
 portion of the boracic acid itself. 
 
 Borate of ammonia forms in small rhom- 
 boidal crystals, easily decomposed by fire ; 
 or in scales, of a pungent urinous taste, 
 which lose the crystalline form, and grow 
 brown on exposure to the air. 
 
 It is very difficult to combine the boracic 
 acid with alumina, at least in the direct way. 
 It has been recommended, for this purpose, 
 to add a solution of borax to a solution of 
 sulphate of alumina ; but for this process the 
 neutral borate of soda is preferable, since, if 
 borax be employed, the soda that is in excess 
 may throw' down a precipitate of alumina, 
 which might be mistaken for an earthy 
 borate. 
 
 I he boracic acid unites witli silex by 
 fusion, and forms with it a solid and per- 
 manent vitreous compound. This borate of 
 silex, however, is neither sapid, nor soluble, 
 uor perceptibly alterable in the air ; and can- 
 
 not be formed without the assistance of a 
 violent heat. In the same manner triple 
 compounds may be formed with silex and 
 borates already saturated with other bases. 
 
 The boracic acid has been found in a 
 disengaged state in several lakes of hot mi- 
 neral waters near Monte llotondo, Berchiaio, 
 and Castellonuovo in Tuscany, in the pro- 
 portion of nearly nine grains in a hundred of 
 water, by M. Iloeffer. M. Mascagni also 
 found it adhering to schistus, on the borders 
 of lakes, of an obscure white, yellow, or 
 greenish colour, and crystallized in the form 
 of needles. He has likewise found it in 
 combination with ammonia. 
 
 Acid (Camphoric). M. Kosegarten found 
 some years ago, that an acid with peculiar 
 properties was obtained, by distilling nitric 
 acid eight times following from camphor. 
 Bouillon Lagrange has since repeated his 
 experiments, and the following is the ac- 
 count he gives of its preparation and pro- 
 perties. 
 
 One part of camphor being introduced 
 into a glass retort, four parts of nitric acid of 
 the strength of 36 degrees are to be poured 
 on it, a receiver adapted to the retort, and all 
 the joints well luted. The retort is then to 
 be placed on a sand-heat, and gradually 
 heated. During the process a considerable 
 quantity of nitrous gas, and of carbonic acid 
 gas, is evolved ; and part of the camphor is 
 volatilized, while another part seizes the 
 oxygen of the nitric acid. When no more 
 vapours are extricated, the vessels are to be 
 separated, and the sublimed camphor added 
 to the acid that remains in the retort. A 
 like quantity of nitric acid is again to be 
 poured on this, and the distillation repeated. 
 This operation must be reiterated till the 
 camphor is completely acidified. Twenty 
 parts of nitric acid at 36 are sufficient to 
 acidify one of camphor. 
 
 When the whole of the camphor is acidi- 
 fied, it crystallizes in the remaining liquor. 
 The whole is then to be poured out upon a 
 filter, and washed with distilled water, to 
 carry off the nitric acid it may have retained. 
 The most certain indication of the acidifica- 
 tion of the camphor is its crystallizing on 
 the cooling of the liquor remaining in the 
 retort. 
 
 To purify this acid it must be dissolved in 
 hot distilled water, and the solution, after 
 being filtered, evaporated nearly to half, or 
 till a slight pellicle forms ; when the cam- 
 phoric acid will be obtained in crystals on 
 cooling. 
 
 This experiment being too long to be ex- 
 hibited by the chemical lecturer, its place 
 may be supplied by the following. 
 
 A jar is to be filled over mercury with 
 oxygen gas from the chlorate of potash, 
 and a little water passed into it. On the 
 other hand, a bit of camphor and an atom 
 
ACI 
 
 A Cl 
 
 of phosphorus are to be placed in a little 
 cupel ; and then one end of a curved 
 tube is to be conveyed under the jar, and 
 the other end under a jar idled with water 
 in the pneumato-chemical apparatus. The 
 apparatus being thus arranged, the phospho- 
 rus is to be kindled by means of a red-hot 
 iron. The phosphorus inflames, and after- 
 wards the camphor. The flame produced by 
 the camphor is very vivid ; much heat is 
 given out ; and the jar is lined with a black 
 substance, which gradually falls down, and 
 covers the water standing on the quicksilver 
 in the jar. This is oxide of carbon. At the 
 same time a gas is collected, that has all the 
 characters of carbonic acid. The water con- 
 tained in the jar is very fragrant, and con- 
 tains camphoric acid in solution. 
 
 The camphoric acid has a slightly acid, 
 bitter taste, and reddens infusion of litmus. 
 
 It crystallizes ; and the crystals upon the 
 whole resemble those of muriate of ammonia. 
 (Kosegarten says they are parallelopipeds of 
 a snowy whiteness.) It effloresces on expo- 
 sure to the atmosphere ; is not very soluble 
 in cold water ; when placed on burning coals, 
 gives out a thick aromatic smoke, and is en- 
 tirely dissipated ; and with a gentle heat 
 melts, and is sublimed. The mineral acids 
 dissolve it entirely. It decomposes the sul- 
 phate and muriate of iron. The fixed and 
 volatile oils dissolve it. It is likewise soluble 
 in alcohol, and is not precipitated from it by 
 water ; a property that distinguishes it from 
 the benzoic acid. It unites easily with the 
 earths and alkalis. 
 
 To prepare the camphorates of lime, mag- 
 nesia, and alumina, these earths must be dif- 
 fused in water, and crystallized camphoric 
 acid added. The mixture must then be 
 boiled, filtered while hot, and the solution 
 concentrated by evaporation. 
 
 The camphorate of barytes is prepared by 
 dissolving the pure earth in water, and then 
 adding crystallized camphoric acid. 
 
 Those of potash, soda, and ammonia, 
 should be prepared with their carbonates dis- 
 solved in water : these solutions are to be sa- 
 turated with crystallized camphoric acid, 
 heated, filtered, evaporated, and cooled, by 
 which means the camphorates will be obtain- 
 ed. 
 
 If the camphoric acid be very pure, they 
 have no smell ; if it be not, they have al- 
 ways a slight smell of camphor. 
 
 The camphorates of alumina and barytes 
 leave a little acidity on the tongue ; the rest 
 have a slightly bitterish taste. 
 
 They are all decomposed by heat ; the 
 acid being separated and sublimed, and the 
 base remaining pure ; that of ammonia ex- 
 cepted, which is entirely volatilized. 
 
 If they be exposed to the blow-pipe, the 
 acid burns with a blue flame . that of am- 
 
 monia gives first a blue flame ; but toward 
 the end it becomes red. 
 
 The camphorates of lime and magnesia 
 are little soluble, the others dissolve more 
 easily. 
 
 The mineral acids decompose them all. 
 The alkalis and earths act in the order of 
 their affinity for the camphoric acid; which 
 is, lime, potash, soda, barytes, ammonia, 
 alumina, magnesia. 
 
 Several metallic solutions, and several 
 neutral salts, decompose the camphorates ; 
 such as the nitrate of barytes, most of the cal- 
 careous salta, &c. 
 
 The camphorates of lime, magnesia, and 
 barytes, part with their acid to alcohol. — 
 Lagrange's Manuel (Tun Cours cle Chimie, 
 
 Acid (Carbonic). This acid, being a 
 compound of carbon and oxygen, may be 
 formed by burning charcoal ; but as it exists 
 in great abundance ready formed, it is not 
 necessary to have recourse to this expedient. 
 All that is necessary is to pour sulphuric 
 acid, diluted with five or six times its weight 
 of water, on common chalk, which is a com- 
 pound of carbonic acid and lime. An effer- 
 vescence ensues ; carbonic acid is evolved in 
 the state of gas, and may be received in the 
 usual manner. 
 
 As the rapid progress of chemistry during 
 the latter part of the 18 th century, was in a 
 great measure owing to the discovery of this 
 acid, it may be worth wfiiile to trace the his- 
 tory of it somewhat particularly. 
 
 Paracelsus and Van Ilelmont were ac- 
 quainted with the fact, that air is extricated 
 from solid bodies during certain processes; 
 and the latter gave to air thus produced the 
 name of gas. Boyle called these kinds of 
 air artificial airs, and suspected that they 
 might be different from the air of the atmos- 
 phere. Hales ascertained the quantity of 
 air that could be extricated from a great va- 
 riety of bodies, and showed that it formed an 
 essential part of their composition. Dr Black 
 proved, that the substances then called lime, 
 magnesia, and alkalis, were compounds, con- 
 sisting of a peculiar species of air, and pure 
 lime, magnesia, and alkali. To this species 
 of air he gave the name of fixed air, because 
 it existed in these bodies in a fixed state. 
 This air or gas w r as aftenvards investigated, 
 and a great number of its properties ascer- 
 tained, by Dr Priestley. From these pro- 
 perties Mr Keir first concluded that it was 
 an acid ; and this opinion w r as soon confirm- 
 ed by the experiments of Bergman, Fontana, 
 and others. Dr Priestley at first suspected 
 that this acid entered as an element into the 
 composition of atmospherical air; and Berg- 
 man, adopting the same opinion, gave it the 
 name of aerial acid. Mr Bewley called it 
 mephitic acid, because it could not be respir- 
 ed w ithout occasioning death ; and this name 
 
ACI 
 
 ACI 
 
 was also adopted by Morveau. Mr Keir 
 called it calcareous acid ; and at last M. La- 
 voisier, after discovering its composition, gave 
 it the name of carbonic acid gas. 
 
 The opinions of chemists concerning the 
 composition of carbonic acid have under- 
 gone as many revolutions as its name. Dr 
 Priestley and Bergman seem at first to have 
 considered it as an element; and seveial ce- 
 lebrated chemists maintained that it was the 
 acidifving principle. Afterwards it was dis- 
 covered to be a compound, and that oxygen 
 gas was one of its component parts. Upon 
 this discovery the prevalent opinion of che- 
 mists w'as, that it consisted of oxygen and 
 phlogiston ; and when hydrogen and phlo- 
 giston came, according to Mr Kirwan’s 
 theory, to signify the same thing, it was of 
 course maintained that carbonic acid was 
 composed of oxygen and hydrogen : and 
 though M. Lavoisier demonstrated that it 
 was formed by the combination of carbon 
 and oxygen, this did not prevent the old 
 theory from being maintained ; because car- 
 bon was itself considered as a compound, 
 into which a very great quantity of hydrogen 
 entered. But after M. Lavoisier had de- 
 monstrated, that the weight of the carbonic 
 acid produced was precisely equal to the 
 charcoal and oxygen employed ; after Mr 
 Cavendish had discovered, that oxygen and 
 hydrogen when combined did not form car- 
 bonic acid, but w r ater, it was no longer possi- 
 ble to doubt that this acid w r as composed of 
 carbon and oxygen. Accordingly, all far- 
 ther dispute about it is at an end. 
 
 If any thing were still wanting, to put 
 this conclusion beyond the reach of doubt, it 
 was to decompose carbonic acid, and thus to 
 exhibit its component parts by analysis as 
 well as synthesis. This has been actually 
 done by Mr Tennant. Into a tube of glass 
 he introduced a bit of phosphorus and some 
 carbonate of lime. He then sealed the tube 
 hermetically, and applied heat. Phosphate of 
 lime was formed, and a quantity of charcoal 
 deposited. Now r phosphate of lime is com- 
 posed of phosphoric acid and lime, and 
 phosphoric acid is composed of phosphorus 
 and oxygen. The substances introduced in- 
 to the tube were phosphorus, lime, and car- 
 bonic acid, and the substances found in it 
 were phosphorus, lime, oxygen, and char- 
 coal. Ihe carbonic acid, therefore, must 
 have been decomposed, and it must have 
 consisted of oxygen and charcoal. This ex- 
 periment was repeated by Hr Pearson, who 
 ascertained, that the weight of the oxygen 
 and charcoal together was equal to that of 
 the carbonic acid which had been introduc- 
 ed ; and in order to show that it was the 
 carbonic acid which had been decomposed, 
 he introduced pure lime and phosphorus ; 
 and, instead of phosphate of lime and carbon, 
 he got nothing but phosphuret of lime. 
 
 These experiments were also confirmed by 
 Fourcroy, Vauquelin, Sylvestre, and Brong- 
 niart. Count Mussin-Puschkin too boiled 
 a solution of carbonate of potash on purified 
 phosphorus, and obtained charcoal. This he 
 considered as an instance of the decomposi- 
 tion of carbonic acid, and as a confirmation 
 of the experiments above related. 
 
 Carbonic acid abounds in great quantities 
 in nature, and appears to be produced in a 
 
 variety of circumstances. It composes 
 of the weight of limestone, marble, calcare- 
 ous spar, and other natural specimens of 
 calcareous earth, from w hich it may be ex- 
 tricated either by the simple application of 
 heat, or by the superior affinity of some 
 other acid ; most acids having a stronger ac- 
 tion on bodies than this. This last process 
 does not require heat, because fixed air is 
 strongly disposed to assume the elastic state. 
 Water, under the common pressure of the 
 atmosphere, and at a low temperature, ab- 
 sorbs somewhat more than its bulk of fixed 
 air, and then constitutes a w r eak acid. If the 
 pressure be greater, the absorption is aug- 
 mented. It is to be observed, likewise, that 
 more gas than water will absorb, should be 
 present. Heated water absorbs less ; and if 
 water impregnated w ith this acid be exposed 
 on a brisk fire, the rapid escape of the aerial 
 bubbles affords an appearance as if the water 
 w r ere at the point of boiling, wdien the heat 
 is not greater than the hand can bear. Con- 
 gelation separates it readily and completely 
 from w ater ; but no degree of cold or pres- 
 sure has yet exhibited this acid in a dense or 
 concentrated state of fluidity. 
 
 Carbonic acid gas is much denser than 
 common air, and for this reason occupies the 
 lower parts of such mines or caverns as con- 
 tain materials which afford it by decomposi- 
 tion. The miners call it choke-damp. The 
 Grotto del Cano, in the kingdom of Naples, 
 has been famous for ages on account of the 
 effects of a stratum of fixed air which covers 
 its bottom. It is a cave or hole in the side 
 of a mountain, near the lake Agnano, mea- 
 suring not more than eighteen feet from its 
 entrance to the inner extremity; where if a 
 dog or other animal that holds down its head 
 be thrust, it is immediately killed by inhaling 
 this noxious fluid. 
 
 Carbonic acid gas is emitted in large quan- 
 tities by bodies in the state of the vinous fer- 
 mentation, (see Fermentation), and on ac- 
 count of its great weight, it occupies the ap- 
 parently empty space or upper part of the 
 vessels in which the fermenting process is 
 going on. A variety of striking experiments 
 may be made in this stratum of elastic fluid. 
 Lighted paper, or a candle dipped into it, is 
 immediately extinguished ; and the smoke 
 remaining in the carbonic acid gas renders 
 its surface visible, w hich may be thrown into 
 
 waves by agitation like water. If a dish of 
 
 % 
 
ACI 
 
 ACI 
 
 Water be immersed in this gas, and briskly 
 agitated, it soon becomes impregnated, and 
 obtains the pungent taste of Pyrmont water. 
 In consequence of the weight of the carbonic 
 acid gas, it may be lifted out in a pitcher, 
 or bottle, which, if well corked, may be used 
 to convey it to great distances, or it may be 
 drawn out of a vessel by a cock like a liquid. 
 The effects produced by pouring this invisi- 
 ble fluid from one vessel to another, have a 
 very singular appearance ; if a candle or 
 small animal be placed in a deep vessel, the 
 former becomes extinct, and the latter ex- 
 pires in a few seconds, after the carbonic 
 acid gas is poured upon them, though the 
 eye is incapable of distinguishing any thing 
 that is poured. If, however, it be poured 
 into a vessel full of air, in the sunshine, its 
 density being so much greater than that of 
 the air, renders it slightly visible by the un- 
 dulations and streaks it forms in this fluid, 
 as it descends through it. 
 
 Carbonic acid reddens infusion of litmus ; 
 but the redness vanishes by exposure to the 
 air, as the acid Hies off. It has a peculiar 
 sharp taste, which may be perceived over 
 vats in which wine or beer is fermenting, as 
 also in sparkling Champaign, and the brisker 
 kinds of cider. Light passing through it is 
 refracted by it, but does not effect any sensi- 
 ble alteration in it, though it appears, from 
 experiment, that it favours the separation of 
 its principles by other substances. It wall 
 not unite with an overdose of oxygen, of 
 which it contains 72 parts in 100, the other 
 28 being pure carbon. It not only destroys 
 life, but the heart and muscle of animals 
 killed by it lose all their irritability, so as to 
 be insensible to the stimulus of galvanism. 
 
 Carbonic acid is dilated by heat, but not 
 otherwise altered by it. It is not acted up- 
 on by oxygen, or any of the simple combus- 
 tibles. Charcoal absorbs it, but gives it out 
 again unchanged, at ordinary temperatures ; 
 but when this gaseous acid is made to tra- 
 verse charcoal ignited in a tube, it is con- 
 verted into carbonic oxide. Phosphorus is 
 insoluble in carbonic acid gas; but, as al- 
 ready observed, is capable of decomposing 
 it by compound affinity, when assisted by 
 sufficient heat ; and Priestley and Cruick- 
 shank have shewn that iron, zinc, and seve- 
 ral other metals, are capable of producing 
 the same effect. If carbonic acid be mixed 
 with sulphuretted, phosphuretted, or carbur- 
 etted gas, it renders them less combustible, 
 or destroys their combustibility entirely, but 
 produces no other sensible change. Such 
 mixtures occur in various analyses, and par- 
 ticularly in the products of the decomposi- 
 tion of vegetable and animal substances. 
 The inflammable air of marshes is frequent- 
 ly carlmrettcd hydrogen intimately mixed 
 with carbonic acid gas, and the sulphuretted 
 
 hydrogen gas obtained from mineral waters 
 is very often mixed with it. 
 
 Carbonic acid appears from various ex- 
 periments of Ingenhousz to be of considera- 
 ble utility in promoting vegetation. It is 
 probably decomposed by the organs of plants, 
 its base furnishing part at least of the car- 
 bon that is so abundant in the vegetable 
 kingdom, and its oxygen contributing to re- 
 plenish the atmosphere with that necessary 
 support of life, which is continually dimi- 
 nished by the respiration of animals and 
 other causes. 
 
 * The most exact experiments on the neutral 
 carbonates concur to prove, that the prime 
 equivalent of carbonic acid is 2.7 5 ; and that 
 it consists of one prime of carbon = 0.75 
 + 2.0 oxygen. This proportion is most ex- 
 actly deduced from a comparison of the spe- 
 cific gravities of carbonic acid gas and oxy- 
 gen ; for it is well ascertained that the lat- 
 ter, by its combination with charcoal, and 
 conversion into the former, does not change 
 its volume. Now, 100 cubic inches of oxy- 
 gen weigh 33.8 gr. and 100 cubic inches of 
 carbonic acid 46.5, shewing the weight of 
 combined charcoal in that quantity to be 
 12.7. But the oxide of carbon contains only 
 half the quantity of oxygen which carbonic 
 acid does ; and we hence infer, that the 
 oxide of carbon consists of one prime of 
 oxygen united to one of carbon. This a 
 priori judgment is confirmed by the weight 
 2.75 deduced from the carbonates, as the 
 prime equivalent of carbonic acid. There- 
 fore we have this proportion : 
 
 If 33.8 represent two primes of oxygen, 
 or 2; 12.7 will represent one of carbon. 
 33.8:2:: 12.7:0.751, being, as above, the 
 prime equivalent or first combining propor- 
 tion of carbon. If the specific gravity of 
 atmospheric air be called 1.0000, that of car- 
 bonic acid will be 1.5236. 
 
 We have seen that water absorbs about its 
 volume of this acid gas, and thereby acquires 
 a specific gravity of 1.0015. On freezing 
 it, the gas is as completely expelled as by 
 boiling. By artificial pressure with forcing 
 pumps, water may be made to absorb two or 
 three times its bulk of carbonic acid. When 
 there is also added a little potash or soda, 
 it becomes the aerated or carbonated alkaline 
 waters, a pleasant beverage, and a not in- 
 active remedy in several complaints, particu- 
 larly dyspepsia, hiccup, and disorders of the 
 kidneys. Alcohol condenses twice its vo- 
 lume of carbonic acid. The most beautiful 
 analytical experiment with carbonic acid, is 
 the combustion of potassium in it, the for- 
 mation of potash, and the deposition of char- 
 coal. Nothing shews the power of chemical 
 research in a more favourable light, than the 
 extraction of an invisible gas from Parian 
 marble or crystallized spar, and its resolu- 
 
ACI 
 
 tion by such an experiment into oxygen and 
 carbon ; in the proportions above stated, 5 
 gr. of potassium should be used tor 3 cubic 
 inches of gas. If less be employed, the gas 
 will not all be decomposed, but a part will 
 be absorbed by the potash. From the above 
 quantities, 3-8ths of a grain of charcoal will 
 be obtained. If a porcelain tube, contain- 
 ing a coil of fine iron wire, be ignited in a 
 furnace, and if carbonic acid be passed back- 
 wards and forwards by means of a lull and 
 empty bladder, attached to the ends of the 
 tube, the gas will be converted into carbonic 
 oxide, and the iron will be oxidized. * 
 
 In point of affinity for the earths and 
 alkalis, carbonic acid stands apparently low 
 in the scale. Before its true nature was 
 known, its compounds with them were not 
 considered as salts, but as the earths and 
 alkalis themselves, only distinguished by the 
 names of mild, or effervescent , from their 
 qualities of effervescing with acids, and want- 
 ing causticity. 
 
 The carbonates are characterized by effer- 
 vescing with almost all the acids, even the 
 acetic, when they evolve their gaseous acid, 
 which, passed into lime water by a tube, de- 
 prives it of its taste, and converts it into chalk 
 and pure water. 
 
 The carbonate of barytes was formed arti- 
 ficially by Bergman and Scheele in 1776 ; 
 but Dr Withering first found it native at 
 Alston Moor in Cumberland in 1783. From 
 this circumstance it has been termed Withe- 
 rite by Werner. It has been likewise called 
 aerated heavy spar, aerated barosclenite, aera- 
 ted heavy earth or barytes, barolite , &c. Its 
 crystals have been observed to assume four 
 different forms, double six-sided, and double 
 four-sided pyramids ; six-sided columns ter- 
 minated by a pyramid with the same num- 
 ber of faces, and small radiated crystals, half 
 an inch in length, and very thin, appearing 
 to be hexagonal prisms, rounded toward the 
 point. The hexaedral prism is presumed to 
 be its primitive form. Its specific gravity, 
 when native, is 4.331, when prepared arti- 
 ficially it scarcely exceeds 3.763. 
 
 It may be prepared by exposing a solution 
 of pure barytes to the atmosphere, when it 
 will be covered with a pellicle of this salt by 
 absorbing carbonic acid; or carbonic acid 
 may be received into this solution, in which 
 it will immediately form a copious precipi- 
 tate ; or a solution of nitrate or muriate of 
 barytes may be precipitated by a solution of 
 the carbonate of potash, soda, or ammonia. 
 I he precipitate, in either of these cases, be- 
 ing well washed, will be found to be very 
 pure carbonate of barytes. It may likewise 
 be procured by decomposing the native sul- 
 phate of barytes by the carbonate of potash, 
 or of soda, in the dry way, with the assist- 
 ance of fire; but in this way the sulphate of 
 barytes is never completely decomposed, 
 
 ACI 
 
 and some of it remains mixed with the car- 
 bonate. 
 
 The carbonate of barytes is soluble only 
 in 4304 times its weight of cold water, and 
 2304 of boiling water, and this requires a 
 long time ; but water saturated with carbonic 
 acid dissolves 1 -830th. It is not altered by 
 exposure to the air, but is decomposed by 
 the application of a very violent heat, either 
 in a black lead crucible, or wffien formed in- 
 to a paste with charcoal powder. Sulphuric 
 acid, in a concentrated state, or diluted with 
 three or four parts of water, does not sepa- 
 rate the carbonic acid with effervescence, 
 unless assisted by heat. Muriatic acid does 
 not act upon it likewise, unless diluted with 
 w^ater, or assisted by heat. And nitric acid 
 does not act upon it at all, unless diluted. 
 It has no sensible taste, yet it is extremely 
 poisonous. 
 
 As this salt has lately been found, in large 
 quantities, near Murton in Cumberland, and 
 some other places in the vicinity, it might 
 probably be introduced into manufactures 
 with advantage, as for extracting the bases 
 of several salts. 
 
 It is composed of 2.75 parts of acid, and 
 9.75 of barytes. Its prime equivalent is 
 therefore the sum of these numbers — 12.5. 
 
 Carbonate off strontian w^as first pointed 
 out as distinct from the preceding species 
 by Dr Crawford in 1790, but Dr Hope 
 gave the first accurate account of it in the 
 Edinburgh Transactions. It has been found 
 native in Scotland, at Strontian in Argyll- 
 shire, and at Leadhills. It is usually in fine 
 striated needles or prisms, that appear to be 
 hexaedral, semitransparent, and of a white 
 colour slightly tinged with green. It is in- 
 sipid ; requires 1556 parts of boiling water 
 to dissolve it ; is not altered by exposure to 
 the air ; but when strongly heated in a cru- 
 cible loses part of its acid ; and this decom- 
 position is facilitated by making it into a 
 paste with charcoal powder. When the fire 
 is strongly urged, it attacks the crucible, and 
 melts into a glass, resembling the colour of 
 chrysolite, or pyramidal phosphate of lime. 
 If thrown in pow r der on well kindled coals, 
 or the flame of a candle, it exhibits red 
 sparks. The same phenomenon occurs, if 
 it be treated with the blow-pipe, which fuses 
 it into an opaque vitreous globule, that falls 
 to powder in the open air. Its specific gra- 
 vity is only 3.66, in which it differs striking- 
 ly from the carbonate of barytes ; as it does, 
 in not being poisonous, according to the ex- 
 periments made by Pelletier on various ani- 
 mals. 
 
 It consists of 6.5 strontites, +2.75 car- 
 bonic acid = 9.25. 
 
 Carbonate off lime exists in great abundance 
 in nature, variously mixed w ith other bodies, 
 under the names of marble , chalk, limestone , 
 st (da elites, <S tc. in which it is of more impor- 
 
ACI 
 
 ACI 
 
 tant and extensive use than any other of the 
 salts, except perhaps the muriate of soda. It 
 is often found crystallized, and perfectly 
 transparent. J he primitive form of its crys- 
 tals is the rhomboidal prism, with angles 
 ot 101-§ and 78^. Its integrant particles 
 have the same form. Beside this, however, 
 many varieties of its crystals have been 
 discovered and described by mineralogists. 
 The specific gravity of the marbles is from 
 2.65 to 2.85 ; of the crystallized carbonats, 
 about 2.7 ; of the stalactites, from 2.32 to 
 2.47 ; of the limestones, from 1.39 to 2.72. 
 
 It has scarcely any taste; is insoluble in 
 pure water, but water saturated with car- 
 bonic acid takes up 1- 1500th, though as the 
 acid flies off* this is precipitated. It suffers 
 little or no alteration on exposure to the air. 
 When heated it decrepitates, its water flies 
 off, and lastly its acid ; but this requires a 
 pretty strong heat. By this process it is 
 burned into lime. 
 
 It is composed of .3.56 lime -f* 2.75 car- 
 bonic acid = 6.31 ; or in 100 parts of 56.4 
 lime and 43.6 acid. 
 
 The carbonate or rather subcarbonate of pot- 
 ash w r as long known by the name of vegetable 
 alkali. It w r as also called fixed nitre , salt of' 
 tartar , salt of wormwood, Sec. according to 
 the different modes in which it was procured ; 
 and was supposed to retain something of the 
 virtues of the substance from which it was 
 extracted. This error has been some time 
 exploded, but the knowledge of its true na- 
 ture is of more recent date. 
 
 As water at the usual temperature of the 
 air dissolves rather more than its weight of 
 this salt, we have thus a ready mode of de- 
 tecting its adulterations in general ; and as 
 it is often of consequence in manufactures, 
 to know how much alkali a particular spe- 
 cimen contains, this may be ascertained by 
 the quantity of sulphuric acid it will satu- 
 rate. 
 
 This salt is deliquescent. 
 
 It consists of 5.94 potash -f 2.75 car- 
 bonic acid = 8.69. 
 
 The bi-carbonate af potash crystallizes, ac- 
 cording to Fourcroy, in square prisms, the 
 apices of which are quadrangular pyramids. 
 According to Pelletier they are tetraedral 
 rhomboidal prisms, with diedral summits. 
 The complete crystal has eight faces, two 
 hexagons, two rectangles, and four rhombs. 
 It has a urinous but not caustic taste ; changes 
 the syrup of violets green : boiling water 
 dissolves five-sixths of its weight, and cold 
 water one-fourth ; alcohol, even when hot, 
 will not, dissolve more than K 1200th. Its 
 
 specific gravity is 2.012. 
 
 When it is very pure and well crystallized 
 jt effloresces on exposure to a dry atmos- 
 phere, though it was formerly considered 
 as deliquescent. The fact is, that the com- 
 mon salt of tartar of the shops is a compound 
 
 of this carbonate and pure potash ; the lat- 
 ter of which, being very deliquescent, at- 
 tracts the moisture of the air till the whole 
 is dissolved. From its smooth feel, and the 
 manner in which it was prepared, the old 
 chemists called this solution oil of tartar per 
 deliquium. 
 
 The bi-carbonate of potash melts with a 
 gentle heat, loses its water of crystallization, 
 amounting to q, and gives out a portion 
 of its carbonic acid ; though no degree of 
 heat will expel the whole of the acid. Thus, 
 as the carbonate of potash is always prepared 
 by incineration of vegetable substances, and 
 lixiviation, it must be in the intermediate 
 state ; or that of a carbonate with excess of 
 alkali : and to obtain the true carbonate we 
 must saturate this salt with carbonic acid, 
 which is best clone by passing the acid in the 
 state of gas through a solution of the salt 
 in twice its weight of w'ater; or, if we want 
 the potash pure, we must have recourse to 
 lime, to separate that portion of acid which 
 fire will not expel. 
 
 Another mode, recommended by Berthol- 
 let, and which may be of use on some occa- 
 sions, is to add solid carbonate of ammonia 
 to a solution of potash not saturated, and 
 distil the mixture : when the ammonia may 
 be obtained in the form of gas, or caustic 
 liquor, w'hile the carbonate crystallizes in the 
 retort. 
 
 The bi-carbonate usually called super- 
 carbonate by the apothecaries, consists of 2 
 primes of carbonic acid = 5.500, 1 of pot- 
 ash = 5.940, and 1 of water = 1.125, in 
 all 1 2.565. 
 
 The carbonate of soda has likewise been 
 long known, and distinguished from the pre- 
 ceding by the name of mineral alkali. In 
 commerce it is usually called barilla , or soda ; 
 in which state, however, it alw r ays contains 
 a mixture of earthy bodies, and usually com- 
 mon salt. It may be purified by dissolving 
 it in a small portion of water, filtering the 
 solution, evaporating at a low f heat, and 
 skimming off the crystals of muriate of soda 
 as they form on its surface. When these 
 cease to form, the solution may be suffered 
 to cool, and the carbonate of soda will crys- 
 tallize. To obtain this salt perfectly pure 
 Klaproth dissolves common carbonate of so- 
 da in water, and saturates this solution with 
 nitric acid, taking care that the acid is a little 
 in excess. lie then separates the sulphuric 
 acid by nitrate of barytes, and the muriatic 
 acid by nitrate of silver. The fluid thus pu- 
 rified he evaporates to dryness, fuses the 
 nitrate of soda obtained, and decomposes it 
 by detonation with charcoal. lie then lix- 
 iviates the residue, and crystallizes the car- 
 bonate of soda. If it be adulterated with 
 potash, tartaric acid will form a precipitate 
 in a pretty strong solution of it. 
 
 It is found abundantly in nature. In 
 
 m 
 
ACI 
 
 ACI 
 
 Eavpt, where it is collected from the sur- 
 face of the earth, particularly after the desic- 
 cation of temporary lakes, it has been known 
 from time immemorial by the name of m- 
 trurn, natron, or natrum . This it has been 
 
 proposed to retain ; and accordingly the Lon- 
 don college has adopted the term natron . 
 Dr Bostock of Liverpool lately found, that 
 the efflorescence, which copiously covered 
 the decaying parts of the plaster of the salt- 
 water baths in that town, consisted of car- 
 bonate of soda. A carbonate of soda exported 
 from Tripoli, which is called Trona from 
 the name of the place where it is found, 
 and analyzed by Klaproth, contained of soda 
 37 parts, carbonic acid 38, water of crystal- 
 lization 22.5, sulphate of soda 2. This does 
 not effloresce. A great deal is prepared in 
 Spain by incinerating the maritime plant 
 sal sol a ; and it is manufactured in this coun- 
 try, as well as in France, from different 
 species of sea-wceds. It is likewise found 
 in mineral waters ; and also in some animal 
 fluids. 
 
 It crystallizes in irregular or rhomboidal 
 decaedrons, formed by two quadrangular 
 pyramids, truncated very near their bases. 
 Frequently it exhibits only rhomboidal la- 
 mime. Its specific gravity is 1.3591. Its 
 taste is urinous, and slightly acrid, without 
 being caustic. It changes blue vegetable 
 colours to a green. It is soluble in less than 
 its weight of boiling water, and twice its 
 weisrht of cold. It is one of the most efflo- 
 rescent salts known, falling completely to 
 powder in no long time. On the application 
 of heat it is soon rendered fluid from the 
 great quantity of its water of crystallization ; 
 but is dried by a continuance of the heat, 
 and then melts. It is somewhat more fusi- 
 ble than the carbonate of potash, promotes 
 the fusion of earths in a greater degree, and 
 forms a glass of better quality. Like that, 
 it is very tenacious of a certain portion of 
 its carbonic acid. It consists in its dry state 
 of 3.94 soda, + 2.7 5 acid, = 6.69. 
 
 * But the crystals contain 10 prime propor- 
 tions of water. They are composed of 22 
 soda, 4-15.3 carbonic acid, 4- 62.7 water in 
 1 00 parts, or of 1 prime of soda = 3. 94, 1 
 of carb. acid == 2.75, and 10 of water = 
 11.25, in whole 17.94. 
 
 r l he bi-carbonate of soda may be prepared 
 by saturating the solution of the preceding 
 salt with carbonic acid gas, and then eva- 
 porating with a very gentle heat to dryness, 
 when a white irregular saline mass is ob- 
 tained. The salt is not crystallizable. Its 
 constituents are 3.94 soda, 4- 5.50 carb. acid, 
 4- L125 water, == 10.565; or in 100 parts 
 37.4 soda, 4- 52 acid, 4- 10.6 water. The 
 intermediate native compound, the African 
 trona, consists, according to Mr R. Phillips, 
 of 5 carbonic acid, 4- 2 soda, 4~ 4 water ; or 
 
 in 100 parts 38 soda, 4- 40 acid, 4* 22 
 water.* See the article Soda. 
 
 The carbonate oJ‘ magnesia, in a state of 
 imperfect saturation with the acid, lias been 
 used in medicine for some time under the 
 simple name of magnesia. It is prepared 
 by precipitation from the sulphate of mag- 
 nesia by means of carbonate of potash. Equal 
 parts of sulphate of magnesia and carbonate 
 of potash, each dissolved in its own weight 
 of boiling water, are filtered and mixed to- 
 gether hot ; the sulphate of potash is sepa- 
 rated by copious washing with water ; and 
 the carbonate of magnesia is then left to drain, 
 and afterward spread thin on paper, and car- 
 ried to the drying stove. When once dried 
 it wall be in friable white cakes, or a fine 
 powder. 
 
 Another mode of preparing it in the 
 great will be found under the article Am- 
 monia. 
 
 To obtain carbonate of magnesia saturated 
 with acid, a solution of sulphate of magnesia 
 may be mixed cold with a solution of car- 
 bonate of potash ; and at the expiration of a 
 few hours, as the superfluous carbonic acid 
 that held it in solution flies off, the carbonate 
 of magnesia will crystallize in very regular 
 transparent prisms of six equal sides. It 
 may be equally obtained by dissolving mag- 
 nesia in water impregnated with carbonic 
 acid, and exposing the solution to the open 
 air. Dr Thomson says, the most regular 
 crystals will be obtained by mixing together 
 125 parts of sulphate of magnesia and 136 
 parts of carbonate of soda, both dissolved in 
 water, filtering the solution, and then setting 
 it aside for two or three days. 
 
 These crystals soon lose their transparen- 
 cy, and become covered with a white pow- 
 der. Exposed to the fire in a crucible, they 
 decrepitate slightly, lose their w'ater and 
 acid, fall to powder, and are reduced to one- 
 fourth of the original weight. When the 
 common carbonate is calcined in the great, 
 it appears as if boiling, from the extrication 
 of carbonic acid ; a small portion ascends 
 like a vapour, and is deposited in a white 
 powder on the cold bodies with which it 
 comes into contact ; and in a dark place, 
 toward the end of the operation, it shines 
 w'ith a blueish phosphoric light. It thus 
 loses half its weight, and the magnesia is 
 left quite pure. 
 
 As the magnesia of the shops is sometimes 
 adulterated w'ith chalk, this may be detected 
 by the addition of a little sulphuric acid 
 diluted with 8 or 10 times its weight of 
 water, as this will form w ith the magnesia a 
 very soluble salt, while the sulphate of lime 
 will remain undissolved. Calcined maerncsia 
 
 m * n 
 
 should dissolve in this dilute acid without 
 any effervescence. 
 
 The crystallized carbonate dissolves in for- 
 
 u 
 
ACI 
 
 ACI 
 
 ty-eight times its weight of cold water ; the 
 common carbonate requires at least ten times 
 as much, and first forms a paste with a small 
 quantity of the fluid. 
 
 Guyton Morveau has lately found the 
 carbonate of magnesia native, near Castella- 
 Monte, in a stone considered there as a clay 
 very rich in alumina. It is amorphous, as 
 white as ceruse, and as compact as the hard- 
 est chalk ; does not sensibly adhere to the 
 tongue; and has no argillaceous smell. Its 
 specific gravity, when all the bubbles of air 
 it contains have escaped, is 2.612. In the 
 fire it lost 0.585 of its weight, and became 
 sufficiently hard to scratch Bohemian glass 
 slightly. On analysis it was found to con- 
 tain magnesia 26.3, silex 14.2, carbonic 
 acid 46, water 12, iron an inappreciable 
 quantity. 
 
 The carbonate of ammonia , once vulgarly 
 known by the name of volatile sal ammoniac , 
 and abroad by that of English volatile salt , 
 because it was first prepared in this country, 
 was commonly called mild volatile alkali , be- 
 fore its true nature was known. 
 
 When very pure it is in a crystalline form, 
 but seldom very regular. Its crystals are so 
 small, that it is difficult to determine their 
 figure. Bergman describes them as acute 
 oetaedrons, the four angles of which are 
 truncated. Rome de Lisle had compressed 
 tetra’edral prisms, terminated by a di'edral 
 summit. Bergman obtained his by saturat- 
 ing warm water with the salt, stopping the 
 bottle closely, and exposing it to great cold. 
 The crystals commonly produced by sub- 
 limation are little bundles of needles, or very 
 slender prisms, so arranged as to represent 
 herborizations, fern leaves, or feathers. The 
 taste and smell of this salt are the same with 
 those of pure ammonia, but much weaker. 
 It turns the colour of violets green, and that 
 of turmeric brown. It is soluble in rather 
 more than twice its weight of cold water, 
 and in its own weight of hot water ; but 
 a boiling heat volatilizes it. When pure, 
 and thoroughly saturated, it is not percepti- 
 bly alterable in the air ; but when it has an 
 excess of ammonia, it softens and grows 
 moist. It cannot be doubted, however, that 
 it is soluble in air ; for if left in an open 
 vessel, it gradually diminishes in weight, and 
 its peculiar smell is diffused to a certain 
 distance. Heat readily sublimes, but does 
 not decompose it. 
 
 It has been prepared by the destructive 
 distillation of animal substances, and some 
 others, in large iron pots, with a fire in- 
 creased by degrees to a strong red heat, the 
 aqueous liquor that first comes over being 
 removed, that the salt might not be dissolv- 
 ed in it. Thus we had the salt of hartshorn, 
 salt of soot, essential salt of vipers, &c. If 
 the salt were dissolved in the water, it was 
 called spirit of the substance from which it 
 
 was obtained. Thus, however, it was much 
 contaminated by a fetid animal oil, from 
 which it required to be subsequently purified, 
 and is much better fabricated by mixing one 
 part of muriate of ammonia and two of car- 
 bonate of lime, both as dry as possible, and 
 subliming in an earthen retort. 
 
 Sir II. Davy has shewn that its component 
 parts vary, according to the manner of pre- 
 paring it. The lower the temperature at 
 which it is formed, the greater the propor- 
 tion of acid and water. Thus, if formed 
 at the temperature of 300°, it contains more 
 than fifty per cent of alkali ; if at 60°, not 
 more than twenty per cent. 
 
 There are three or four definite compounds 
 of carbonic acid and ammonia. The 1 st is the 
 solid sub-carbonate of the shops. It consists 
 of 55 carbonic acid, 30 ammonia, and 15 
 water ; or probably of 3 primes carbonic 
 acid, 2 ammonia, and 2 water; in all 14.76 
 for its equivalent. 2. But M. Gay Lussac 
 has shewn, that when 100 volumes of animo- 
 niacal gas are mixed with 50 of carbonic 
 acid, the two gases precipitate in a solid 
 salt, which must consist by weight of 561- 
 acid + 45~ alkali, being in the ratio of a 
 prime equivalent of each. 3. When the 
 pungent sub-carbonate is exposed in powder 
 to the air, it becomes scentless by the evapo- 
 ration of a definite portion of its ammonia. 
 It is then a compound of about 55 or 56 
 carbonic acid, 21.5 ammonia, and 22.5 water. 
 It may be represented by 2 primes of acid, 
 1 of ammonia, and 2 of water, =12. 4. Ano- 
 ther compound, it has been supposed, may 
 be prepared by passing carbonic acid through 
 a solution of the sub-carbonate till it be sa- 
 turated. This, however, may be supposed 
 to yield the same product as the last salt. 
 M. G. Lussac infers the neutral carbonate to 
 consist of equal volumes of the two gases, 
 though they will not directly combine in 
 these proportions. This would give 18.1 to 
 46.5 ; the very proportions in the scentless 
 salt. For 46.5 : 18.1 : : 55 : 21.42. 
 
 It is w r ell known as a stimulant usually 
 put into smelling-bottles, frequently with 
 the addition of some odoriferous oil. 
 
 Fourcroy has found, that an ammoniaco- 
 magmesian carbonate is formed on some oc- 
 casions. Thus, if carbonate of ammonia be 
 decomposed by magnesia in the moist way, 
 leaving these two substances in contact with 
 each other in a bottle closely stopped, a com- 
 plete decomposition wall not take place, but 
 a portion of this trisalt will be formed. The 
 same will take place, if a solution of carbo- 
 nate of magnesia in water, impregnated with 
 carbonic acid, be precipitated by pure ammo- 
 nia ; or if ammoniaco-magnesian sulphate, 
 nitrate, or muriate, be precipitated by carbo- 
 nate of potash or of soda. 
 
 The properties of this triple salt are not yet 
 known, but it crystallizes differently from 
 
ACI 
 
 A Cl 
 
 the carbonate of either of its bases, and lias its 
 own laws of solubility and decomposition. 
 
 The carbonate of glucine has been examin- 
 ed by Vauquelin, and is, among the salts of 
 that earth, that of which he has most accu- 
 rately ascertained the properties. It is in a 
 white, dull, clotty powder, never dry, but 
 greasy, and soft to the feel. It is not sweet, 
 like the other salts of glucine, but insipid. 
 It is very light, insoluble in water, perfectly 
 unalterable by the air, but very readily de- 
 composed by fire. 
 
 A saturated solution of carbonate of am- 
 monia takes up a certain portion of this car- 
 bonate, and forms with it a triple salt. This 
 property enabled Vauquelin to separate glu- 
 cine from alumina, and was one of the 
 means of his distinguishing that earth. 
 
 Carbonic acid does not appear to be much 
 disposed to unite with argillaceous earth. 
 Most clays, however, afford a small quantity 
 of this acid by heat ; and Fourcroy says, that 
 tile fat clays effervesce with acids. The 
 snowy white substance resembling chalk, and 
 known by the name of lac lunce , is found to 
 consist almost wholly of alumina saturated 
 with carbonic acid. A saline substance, con- 
 sisting of two six-sided pyramids joined at 
 one common base, weighing five or six grains, 
 and of a taste somewhat resembling alum, 
 was produced by leaving an ounce phial of 
 water impregnated with carbonic acid, and a 
 redundancy of alumina, exposed to sponta- 
 neous evaporation for some months. 
 
 Vauquelin has found, that carbonate of 
 zircone may be formed by evaporating mu- 
 riate of zircone, redissolving it in water, and 
 precipitating by the alkaline carbonate. He 
 also adds, that it very readily combines so as 
 to form a triple salt with either of the three 
 alkaline carbonates. 
 
 Acid (Caseic). The name given by 
 I roust to an acid found in cheese, to which 
 he ascribes their flavour. 
 
 Acid (Cetic). The name given by M. 
 Ghevreul to a supposed peculiar principle of 
 spermaceti, which he has lately found to be 
 the substance lie has called Margarine, com- 
 bined with a fatty matter.* 
 
 Acid (CiiLORioDicj. See Acid (IIydrio- 
 Dic). 
 
 Acid (Ciilorocarbonic). See Chlorine, 
 and C ii lo roc a r bo nous Acid. 
 
 Acid (C iilorocyanic). See Acid (Prus- 
 sic). 
 
 Acid (Chromic). This acid has been 
 examined principally by Vauquelin, who first 
 discovered it, and by count Mussin Posch- 
 kin ; yet we are better acquainted witli it 
 than with the metal that forms its basis. 
 However, as the chromate of iron has lately 
 been found in abundance in the department 
 of Var, in France, and in some other places, 
 we may expect its properties to be more am- 
 ]> y investigated, and applied with advantage 
 
 in the arts, as the chromates of lead and iron 
 are of excellent use in painting and enamel- 
 ling. 
 
 It was extracted from the red lead ore of 
 Siberia, by treating this ore with carbonate of 
 potash, and separating the alkali by means 
 of a more powerful acid. In this state it is 
 a red or orange-coloured powder, of a pecu- 
 liar rough metallic taste, which is more sen- 
 sible in it than in any other metallic acid. If 
 this powder be exposed to the action of light 
 and heat, it loses its acidity, and is converted 
 into green oxide of chrome, giving out pure 
 oxygen gas. The chromic acid is the first 
 that has been found to de- oxygenate itself 
 easily by the action of heat, and afford oxy- 
 gen gas by this simple operation. It appears 
 that several of its properties are owing to the 
 weak adhesion of a part at least of its oxygen. 
 The green oxide of chrome cannot be brought 
 back to the state of an acid, unless its oxygen 
 be restored by treating it with some other 
 acid. 
 
 The chromic acid is soluble in water, and 
 crystallizes, by cooling and evaporation, in 
 longish prisms of a ruby red. Its taste is 
 acrid and styptic. Its specific gravity is not 
 exactly known ; but it always exceeds that 
 of water. It powerfully reddens the tincture 
 of turnsole. 
 
 Its action on combustible substances is 
 little known. If it be strongly heated with 
 charcoal, it grows black, and passes to the 
 metallic state without melting. 
 
 Of the acids, the action of the muriatic oil 
 it is the most remarkable. If this be dis- 
 tilled with the chromic acid, by a gentle 
 heat, it is readily converted into chlorine. 
 It likewise imparts to it by mixture the pro- 
 perty of dissolving gold ; in which the chro- 
 mic resembles the nitric acid. This is owing 
 to the weak adhesion of its oxygen, and it is 
 the only one of the metallic acids that pos- 
 sesses this property. 
 
 '* The extraction of chromic acid from the 
 French ore, is performed by igniting it with 
 its own weight of nitre in a crucible. The 
 residue is lixiviated with water, which being 
 then filtered, contains the chromate of pot- 
 ash. On pouring into this a little nitric 
 acid and muriate of barytes, an instanta- 
 neous precipitate of the chromate of barytes 
 takes place. After having procured a cer- 
 tain quantity of this salt, it must be put in 
 its moist state into a capsule, and dissolved 
 in the smallest possible quantity of weak 
 nitijc acid. I he barytes is to lie then preci- 
 pitated by very dilute sulphuric acid, taking 
 care not to add an excess of it. When the 
 liquid is found by trial to contain neither 
 sulphuric acid nor barytes, it must be filter- 
 ed. It now consists of water, with nitric and 
 chromic acids. Ihe whole is to be evaporat- 
 ed to dryness, conducting the heat at the 
 end, so as not to endanger the decomposition 
 
AC1 
 
 of the chromic acid, which will remain in the 
 capsule under the form of a reddish matter. 
 It must be kept in a glass phial well corked. 
 
 Chromic acid, heated with a powerful 
 acid, becomes chromic oxide ; while the lat- 
 ter, heated with the hydrate of an alkali, be- 
 comes chromic acid. As the solution of the 
 oxide is green, and that of the acid yellow, 
 these transmutations become very remark- 
 able to the eye. From Berzelius’s experi- 
 ments on the combinations of the chromic 
 acid with barytes, and oxide of lead, its prime 
 equivalent seems to be 6.5 ; consisting of 3.5 
 chromium, and 5.0 oxygen.* See Chromium. 
 
 It readily unites with alkalis, and is the 
 only acid that has the property of colouring 
 its salts, whence the name of chromic has 
 been given it. If two parts of the red lead 
 ore of Siberia in fine powder be boiled with 
 one of an alkali saturated with carbonic 
 acid, in forty parts of water, a carbonate of 
 lead will be precipitated, and the chromate 
 remain dissolved. The solutions are of a 
 lemon colour, and afford crystals of a some- 
 what deeper hue. Those of chromate of 
 ammonia are in yellow laminae, having the 
 metallic lustre of gold. 
 
 The chromate of barytes is very little solu- 
 ble, and that of lime still less. They are 
 both of a pale yellow, and when heated give 
 out oxygen gas, as do the alkaline chro- 
 mates. 
 
 If the chromic acid be mixed with filings 
 of tin and the muriatic acid, it becomes at 
 first yellowish brown, and afterwards assumes 
 a bluish green colour, which preserves the 
 same shade after desiccation. Ether alone 
 gives it the same dark colour. With a solu- 
 tion of nitrate of mercury, it gives a precipi- 
 tate of a dark cinnabar colour. With a so- 
 lution of nitrate of silver it gives a precipitate, 
 which, the moment it is formed, appears of a 
 beautiful carmine colour, but becomes pur- 
 ple by exposure to the light. This combina- 
 tion, exposed to the heat of the blow-pipe, 
 melts before the charcoal is inflamed, and 
 assumes a blackish and metallic appearance. 
 If it be then pulverized, the powder is still 
 purple ; but after the blue flame of the lamp 
 is brought into contact with this powder, it 
 assumes a green colour, and the silver ap- 
 pears in globules disseminated through its 
 substance. 
 
 With nitrate of copper it gives a chcsnut 
 red precipitate. With the solution of sul- 
 phate of zinc, muriate of bismuth, muriate of 
 antimony, nitrate of nickel, and muriate of 
 platina, it produces yellowish precipitates, 
 when the solutions do not contain an excess 
 of acid. With muriate of gold it produces a 
 greenish precipitate. 
 
 When melted with borax, or glass, or acid 
 of phosphorus, it communicates to it a beau- 
 tiful emerald green colour. 
 
 If paper be impregnated with it, and ex- 
 
 ACI 
 
 posed to the sun a few days, it acquires a 
 green colour, which remains permanent in 
 the dark. 
 
 A slip of iron, or tin, put into its solu- 
 tion, imparts to it the same colour. 
 
 The aqueous solution of tannin produces 
 a flocculent precipitate of a brown fawn co- 
 lour. 
 
 Sulphuric acid, when cold, produces no 
 effect on it ; but when warm it makes it 
 assume a bluish green colour. 
 
 Acm (Citric). The juice of lemons, or 
 limes, has all the characters of an acid of 
 considerable strength ; but on account of the 
 mucilaginous matter with wdiich it is mixed, 
 it is very soon altered by spontaneous decom- 
 position. Various methods have been con- 
 trived to prevent this effect from taking 
 place, in order that this wholesome and 
 agreeable acid might be preserved for use in 
 long voyages, or other domestic occasions. 
 The juice may be kept in bottles under a 
 thin stratum of oil, which indeed prevents, 
 or greatly retards, its total decomposition ; 
 though the original fresh taste soon gives 
 place to one which is much less grateful. In 
 the East Indies it is evaporated to the con- 
 sistence of a thick extract. If this operation 
 be carefully performed by a very gentle heat, 
 it is found to be very effectual. When the 
 juice is thus heated, the mucilage thickens, 
 and separates in the form of flocks, part of 
 which subsides, and part rises to the surface : 
 these must be taken out. The vapours which 
 arise are not acid. If tire evaporation be 
 not carried so far as to deprive the liquid of 
 its fluidity, it may be long preserved in well 
 closed bottles ; in which, after some w eeks’ 
 standing, a farther portion of mucilage is se- 
 parated, without any perceptible change in 
 the acid. 
 
 Of all the methods of preserving lemon- 
 juice, that of concentrating it by frost appears 
 to be the best, though in the warmer climates 
 it cannot conveniently be practised. Le- 
 mon-juice, exposed to the air, in a tempera- 
 ture between 50° and 60°, deposits in a few 
 hours a white semi-transparent mucilaginous 
 matter, which leaves the fluid, after decanta- 
 tion and filtration, much less alterable than 
 before. This mucilage is not of a gummy 
 nature, but resembles the gluten of wheat in 
 its properties : it is not soluble in water 
 
 when dried. More mucilage is separated 
 from lemon-juice by standing in closed ves- 
 sels. If this depurated lemon-juice be ex- 
 posed to a degree of cold of about seven or 
 eight degrees below' the freezing point, the 
 aqueous part will freeze, and the ice may be 
 taken away as it forms ; and if the process 
 be continued until the ice begins to exhibit 
 signs of acidity, the remaining acid w ill be 
 found to be reduced to about one-eighth of its 
 original quantity, at the same time that its 
 acidity will be eight times as intense, as is 
 
ACI 
 
 ACI 
 
 proved by its requiring eight times the quan- 
 tity of alkali to saturate an equal portion of 
 it. This concentrated acid may be kept for 
 use, or, if preferred, it may be made into 
 a dry lemonade, by adding six times its 
 weight of fine loaf sugar in powder. 
 
 The above processes may be used when 
 the acid of lemons is wanted for domestic 
 purposes, because they leave it in possession 
 of the oils, or other principles, on which its 
 flavour peculiarly depends ; but in chemical 
 researches, where the acid itself is required 
 to be had in the utmost purity, a more ela- 
 borate process must be used. Boiling le- 
 mon-juice is to be saturated with powdered 
 chalk, the weight of which is to be noted, and 
 the powder must be stirred up from the bot- 
 tom, or the vessel shaken from time to time. 
 The neutral saline compound is scarcely 
 more soluble in water than selenite ; it there- 
 fore falls to the bottom, while the mucilage 
 remains suspended in the watery fluid, which 
 must be decanted off ; the remaining preci- 
 pitate must then be washed with warm wa- 
 ter until it comes off clear. To the powder 
 thus edulcorated, a quantity of sulphuric 
 acid, equal the chalk in weight, and diluted 
 with ten parts of water, must be added, and 
 the mixture boiled a few minutes. The 
 sulphuric acid combines with the earth, and 
 forms sulphate of lime, which remains behind 
 when the cold liquor is filtered, while the 
 disengaged acid of lemons remains dissolved 
 in the fluid. This last must be evaporated 
 to the consistence of a thin syrup, which 
 yields the pure citric acid in little needle-like 
 crystals. It is necessary that the sulphuric 
 acid should be rather in excess, because the 
 presence of a small quantity of lime will pre- 
 vent the crystallization. This excess is al- 
 lowed for above. 
 
 M. Dize, a skilful apothecary in Paris, 
 who has repeated this process of Scheele on 
 a very extensive scale, asserts, that an excess 
 of sulphuric acid is necessary, not only to 
 obtain the citric acid pure, but to destroy 
 the whole of the mucilage, part of which 
 would otherwise remain, and occasion its 
 spoiling. It is not certain, however, but 
 the sulphuric acid may act on the citric it- 
 self, and by decomposing it, produce the 
 charcoal that M. Dize ascribes to the decom- 
 position of mucilage; and if so, the smaller 
 the excess of sulphuric acid the better. He 
 also adds, that to have it perfectly pure it 
 must be repeatedly crystallized, and thus it 
 forms very large and accurately defined crys- 
 tals in rhomboidal prisms, the sides of which 
 are inclined in angles of 60° and 1 20°, termi- 
 nated at each end by tetraedral summits, 
 which intercept the solid angles. These, 
 however, will not be obtained when operat- 
 ing on small quantities. 
 
 Its taste is extremely sharp, so as to appear 
 caustic. Distilled in a retort, part rises 
 
 without being decomposed ; it appears to 
 give out a portion of vinegar ; it then evolves 
 carbonic acid gas, and a little carburetted 
 hydrogen ; and a light coal remains. It is 
 among the vegetable acids the one which 
 most powerfully resists decom posit ion by fire. 
 
 In a dry and warm air it seems to efflo- 
 resce ; but it absorbs moisture when the air 
 is damp, and at length loses its crystalline 
 form. A hundred parts of this acid are 
 soluble in seventy-five of water at G0°, ac- 
 cording to Vauquelin. Though it is less 
 alterable than most other solutions of vege- 
 table acids, it will undergo decomposition 
 when long kept. Fourcroy thinks it proba- 
 ble that it is converted into acetic acid before 
 its final decomposition. 
 
 It is not altered by any combustible sub- 
 stance ; charcoal alone appears to be capable 
 of whitening it. The most powerful acids 
 decompose it less easily than they do other 
 vegetable acids ; but the sulphuric evidently 
 converts it into acetic acid. The nitric acid 
 likewise, according to Fourcroy and Vau- 
 quelin, if employed in large quantity, and 
 heated on it a longtime, converts the greater 
 part of it into acetic acid, and a small por- 
 tion into oxalic. Scheele indeed could not 
 effect this; but Westrumb supposes, that it 
 was owing to his having used too much ni- 
 tric acid ; for on treating 60 grains of citric 
 acid with 200 of nitric he obtained 50 grains 
 of oxalic acid ; with 300 grains of nitric acid 
 he got 1 5 ; and with 600 grains no vestige of 
 oxalic acid appeared. 
 
 If a solution of barytes be added gradu- 
 ally to a solution of citric acid, a flocculent 
 precipitate is formed, soluble by agitation, 
 till the whole of the acid is saturated. This 
 salt at first falls down in powder, and then 
 collects in silky tufts, and a kind of very 
 beautiful and shining silvery bushes. It re- 
 quires a large quantity of water to dissolve it. 
 
 1 he citrate of lime has been mentioned 
 already, in treating of the mode of purifying 
 the acid. 
 
 I he citrate of potash is very soluble and 
 deliquescent. 
 
 I lie citrate of soda has a dull saline taste; 
 dissolves in less than twice its weight of 
 water ; crystallizes in six-sided prisms with 
 flat summits; effloresces slightly, but does 
 not fall to powder; boils up, swells, and is 
 reduced to a coal on the fire. Dime-w r ater 
 decomposes it, but does not render the solu- 
 tion turbid, notwithstanding the little solu- 
 bility of citrate of lime. 
 
 Citrate of ammonia is very soluble ; docs 
 not crystallize unless its solution be greatly 
 concentrated ; and forms elongated prisms. 
 
 Citrate of magnesia does not crystallize. 
 When its solution had been boiled down* 
 and it had stood some days, on being slight- 
 ly shaken it fixed in one white opaque mass, 
 which remained soft, separating from the 
 
ACI 
 
 sides of the vessel, contracting its dimen- 
 sions, and rising in the middle like a kind of 
 mushroom. 
 
 Its combination with the other earths has 
 not been much examined; and its action 
 upon metals has been little studied. Scheele 
 however found, that it did not precipitate the 
 nitric solutions of metals, as the malic acid 
 does. 
 
 All the citrates are decomposed by the 
 powerful acids, which do not form a preci- 
 pitate with them, as with the oxalates and 
 tartrates. The oxalic and tartaric acids de- 
 compose them, and form crystallized or in- 
 soluble precipitates in their solutions. All 
 afford traces of acetic acid, or a product of 
 the same nature, on being exposed to distil- 
 lation : this character exists particularly in 
 the metallic citrates. Placed on burning 
 coals they melt, swell up, emit an empyreu- 
 matic smell of acetic acid, and leave a light 
 coal. All of them, if dissolved in water, 
 and left to stand for a time, undergo decom- 
 position, deposit a flocculent mucus which 
 grows black, and leave their bases combined 
 with carbonic acid, one of the products of 
 the decomposition. Before they are com- 
 pletely decomposed, they appear to pass to 
 the state of acetates. 
 
 The affinities of the citric acid are arrang- 
 ed by Vauquelin in the following order: 
 barytes, lime, potash, soda, strontian, mag- 
 nesia, ammonia, alumina. Those for zir- 
 cone, glucine, and the metallic oxides, are 
 not ascertained. 
 
 The citric acid is found in many fruits 
 united with the malic acid ; which see for 
 the process of separating them in this case. 
 
 * From the composition of the citrate of 
 lead, as determined by Berzelius, it appears, 
 that dry citric acid has for its prime equiva- 
 lent 7.368, compared to yellow oxide of lead 
 14, and oxygen 1 . 0 . The crystals, accord- 
 ing to the same accurate chemist, consist of 79 
 real acid, and 21 water, in 100 parts. This 
 would make the equivalent of the crystallized 
 acid 9 . 3 . Its ultimate constituents are, by 
 the analysis of 
 
 Hydrogen. Oxygen. Carbon. 
 Gay Lussac and l 6<33Q + 33>gl j + 59.359 
 
 Tlienard, ) 
 
 Berzelius, - 3. 800 4 - 4 1 .36 9 + 54.83 1 
 
 Citric acid being more costly than tartaric, 
 may be occasionally adulterated with it. This 
 fraud is discovered, by adding slowly to the 
 acid dissolved in water a solution of sub- 
 carbonate of potash, which will give a white 
 pulverulent precipitate of tartar, it the citric 
 be contaminated with the tartaric acid. 
 When one part of citric acid is dissolved in 
 19 of water, the solution may be used as a 
 substitute for lemon-juice. If before solu- 
 tion the crystals be triturated with a little 
 sugar and a few drops of the oil of lemons, 
 
 ACI 
 
 the resemblance to the native juice will be 
 complete. It is an antidote against sea 
 scurvy; but the admixture of mucilage and 
 other vegetable matter in the recent fruit of 
 the lemon, has been supposed to render 
 it preferable to the pure acid of the che- 
 mist.* 
 
 Acid (Chloric). See Acid (Muriatic). 
 
 * Acid (Columbic). The experiments of 
 Mr Hatchett have proved, that a peculiar 
 mineral from Massachusetts, deposited in 
 the British Museum, consisted of one part 
 of oxide of iron, and somewhat more than 
 three parts of a white coloured substance, 
 possessing the properties of an acid. Its 
 basis was metallic. Hence he named this 
 Columbium, and the acid the Columbic. 
 Dr Wollaston, by very exact analytical com- 
 parisons, proved, that the acid of Mr Hat- 
 chett, was the oxide of the metal lately dis- 
 covered in Sweden by Mr Ekeberg, in the 
 mineral yttrotantalite, and thence called tan- 
 talum. Dr Wollaston’s method of separat- 
 ing the acid from the mineral is peculiarly 
 elegant. One part of tantalite, five parts of 
 carbonate of potash, and two parts of borax, 
 are fused together in a platina crucible. The 
 mass, after being softened in water, is acted 
 on by muriatic acid. The iron and man- 
 ganese dissolve, while the columbic acid re- 
 mains at the bottom. It is in the form of a 
 white powder, which is insoluble in nitric 
 and sulphuric acids, but partially in muria- 
 tic. It forms with barytes an insoluble salt, 
 of which the proportions, according to Ber- 
 zelius, are 24.4 acid, and 9.75 barytes. By 
 oxidizing a portion of the revived tantalum 
 or columbium, Berzelius infers the composi- 
 tion of the acid to be 100 metal and 5.485 
 oxygen.* 
 
 Acid (Cyanic). See Acid (Prussic). 
 
 Acid (Fluoric). The fusible spar which 
 is generally distinguished by the name of 
 Derbyshire spar, consists of calcareous earth 
 in combination with the acid at present un- 
 der our consideration. If the pure fluor, or 
 spar, be placed in a retort of lead or silver, 
 with a receiver of the same metal adapted, 
 and its weight of sulphuric acid be then 
 poured upon it, the fluoric acid will be dis- 
 engaged by the application of a moderate 
 heat. This acid gas readily combines with 
 water ; for which purpose it is necessary that 
 the receiver should previously be half filled 
 with that fluid. 
 
 * If the receiver be cooled with ice, and no 
 water put in it, then the condensed acid is 
 an intensely active liquid, first procured by 
 M. Gay Lussac. The best account of it, 
 however, has been given by Sir H. Davy. 
 It has the appearance of sulphuric acid, but 
 is much more volatile, and sends off white 
 fumes when exposed to air. Its specific 
 gravity is only 1.0609. It must be examin- 
 ed with great caution, for when applied to 
 
ACI 
 
 ACI 
 
 the skin it instantly disorganizes it, and pro- 
 duces very painful wounds. When potas- 
 sium is introduced into it, it acts with in- 
 tense energy, and produces hydrogen gas 
 and a neutral salt ; when lime is made to 
 act upon it, there is a violent heat excited, 
 water is formed, and the same substance as 
 fluor spar is produced. With water in a 
 certain proportion, its density increases to 
 1.25. When it is dropped into water, a 
 hissing noise is produced with much heat, 
 and an acid fluid not disagreeable to the 
 taste is formed if the water be in sufficient 
 quantity. It instantly corrodes and dissolves 
 glass. 
 
 It appears extremely probable, from all 
 the facts known respecting the fluoric com- 
 binations, that fluor spar contains a peculiar 
 acid matter ; and that this acid matter is 
 united to lime in the spar, seems evident 
 from the circumstance, that gypsum or sul- 
 phate of lime is the residuum of the distilla- 
 tion of fluor spar and sulphuric acid. The 
 results of experiments on fluor spar have 
 been differently stated by chemists. Sir H. 
 Davy states, that 100 fluor spar yield 175.2 
 sulphate of lime ; whence we deduce the 
 prime equivalent of fluoric acid to be 1.3260, 
 to lime 3.56, and oxygen 1.00. From 
 fluate of potash the equivalent comes out for 
 the acid, = 1.2495, potash being reckoned 
 5.95. Berzelius in his last series of experi- 
 ments gives from fluate of lime 1.374, for 
 the equivalent of fluoric acid. The dense 
 fluid obtained in silver vessels, may be re- 
 garded as hydrofluoric acid ; and, supposing 
 all the acid in oil of vitriol transferred to it, 
 would consist of 1.526, or 1.374 acid, + 
 1.125 water; which is a prime of each. 
 
 Dr Thomson, in his System of Chemistry, 
 fifth edition, vol. i. p. 205, deduces the 
 equivalent of fluoric acid from the decompo- 
 sition of fluate of lime by sulphuric acid, to 
 be 1.0095; and, from the lowness of this 
 number, he afterwards endeavours to prove 
 that fluoric acid cannot be a compound of 
 oxygen with a base. Now taking his own 
 data of 100 parts of fluor spar yielding, ac- 
 cording to Sir H. Davy’s latest experiments, 
 175.2 sulphate of lime ; and admitting that 
 these contain 73.582 of lime; leaving con- 
 sequently 26.418 for the proportion of acid 
 in 100 of fluor spar, we shall find 1.3015 to 
 be the equivalent or atom of fluoric acid. 
 For 73.582 : 3.625 : : 26.418 : 1.3015, tak- 
 ing his own number 5.625 for the atom of 
 lime. Hence the whole difficulties stated by 
 him in the following passage, page 206, dis- 
 appear : — “ If we suppose fluate of lime to 
 be a compound of fluoric acid and lime, its 
 composition will be, Fluoric acid, 1.0095 
 
 Lime, 3.625 
 
 from this we sec that the weight of an inte- 
 grant particle of fluoric acid must be 1.0095. 
 If it be supposed a compound of one atom of 
 
 oxygen, and one atom of an unknown in- 
 flammable basis, then as the weight of an 
 atom of oxygen is 1, the weight of an 
 atom of the inflammable base can be only 
 0.0095, which is only the thirteenth part of 
 the weight of an atom of hydrogen. On 
 that supposition, fluoric acid would be com- 
 posed of Inflammable basis, 1.00 
 Oxygen, 105.67 
 
 So very light a body, being contrary to all 
 analogy, cannot be admitted to exist without 
 stronger proofs than have hitherto been ad- 
 duced. On the other hand, if fluor spar be 
 in reality a fluoride of calcium, then its com- 
 position will be, Fluorine, 2.0095 
 
 Calcium, 2.625 
 
 So that the weight of an atom of fluorine 
 would be 2.0095, or almost exactly twice the 
 weight of an atom of oxygen. This is sure- 
 ly a much more probable supposition than 
 the former.” 
 
 It is not possible to find a more instruc- 
 tive example than the one now afforded 
 by this systematic chemist, of the danger 
 of prosecuting, on slippery grounds, hy- 
 pothetical analogies. The atom of fluoric 
 acid, when rightly computed with his own 
 data, is not 1.0095, but 1.3015, and hence 
 none of his consequences need be consi- 
 dered. It may consist of 1 of oxygen combin- 
 ed with 0.3015 of an unknown radical; or 
 there may, for aught we know, be a sub- 
 stance analogous to chlorine and iodine, to 
 be called therefore fluorine, whose prime 
 equivalent will be 2.3015. From the mode 
 in which liquid fluoric acid is produced, viz. 
 from a mixture of fluor spar and oil of vitriol, it 
 may obviously contain water, and may consist, 
 as we have seen, probably of a prime or atom 
 of real acid, and an atom of water. Hence 
 the phenomena occasioned by adding potas- 
 sium to it, present nothing different from 
 those exhibited by the same metal added 
 to concentrated hydro- nitric or hydro-sul- 
 phuric acid. Sir H. Davy indeed has been 
 induced in his last researches to infer, from 
 the action of ammoniacal gas on the liquid 
 fluoric acid, that it contains no water. 
 
 On this subject Dr Thomson has the follow- 
 ing aphorism : “ When any acid that contains 
 water is combined in this -manner with am- 
 moniacal gas, if we heat the salt formed, 
 water is always disengaged. Thus sulphuric 
 acid, or nitric acid, or phosphorous acid, 
 when saturated wdth ammoniacal gas and 
 heated, give out always abundance of water. 
 But fluate of ammonia, when thus treated, 
 gave out no water. Hence we have no evi- 
 dence that fluoric acid contains any w'ater.” 
 Ihe whole of this reasoning is visionary. 
 It has been proved in my experimental 
 researches on the ammoniacal salts, in- 
 serted in the tenth volume of the Annals 
 of Philosophy, that the sulphate and nitrate 
 of ammonia, in the driest state to which they 
 
ACI 
 
 ACI 
 
 can be brought by heat, short of their decom- 
 position, contain one atom or prime equiva- 
 lent ot water, which is indeed essential to 
 their very existence, and which water cannot 
 be separated by heat alone. If concentrated 
 oil ot vitriol be saturated with dry ammonia- 
 cal gas, a solid salt will be obtained, from 
 which heat alone will not separate the pro- 
 portion of water it contains, and which 
 amounts to 13.G per cent. A stronger heat 
 will merely separate a portion of the ammo- 
 nia from the acid, or volatilize both. In the 
 former case the acid retains its atom of 
 water. Hence we see, that no inference what- 
 ever can be drawn from the aminoniacal com- 
 bination with liquid fluoric acid, to negative 
 the probability that it may contain, from 
 the mode of its extraction, combined water, 
 like the sulphuric and nitric acids. The in- 
 ferences from the analogous actions of potas- 
 sium on the muriate and fluate of ammonia, 
 are all liable to the same fallacy. If the 
 combined water of the fluoric acid pass into 
 the salt, as with sulphuric acid it undoubt- 
 edly does, then hydrogen and fluate of pot- 
 ash ought to result, from the joint actions of 
 potassium and the hydro - fluoric acid. 
 
 The chocolate powder which is evolved at the 
 positive pole, and the hydrogen at the nega- 
 tive, when liquid fluoric acid was subjected 
 by Sir H. Davy to the voltaic power, can 
 justify no decisive opinion on this intricate 
 research. The mere coating of the platinum 
 wire may as well be regarded as a fluate 
 of platinum, as a fluoride. Nor does the de- 
 composition of the fluates of silver and mer- 
 cury, when heated in glass vessels with chlo- 
 rine, seem to prove any thing whatever. The 
 oxygen evolved, is obviously separated from 
 the oxides of silver or mercury when acted 
 on by chlorine ; and the dry fluoric acid 
 unites to the silica of the glass, forming sili- 
 cated fluoric gas, or fluo-silicic acid. 
 
 In thus shewing the inconclusiveness of Dr 
 Thomson’s four different arguments, to prove 
 that fluoric acid is a compound of an un- 
 known radical, fluorine, with hydrogen, and 
 not of an unknown radical, which might be 
 termed fluor, with oxygen ; one cannot help, 
 however, expressing a high admiration of Sir 
 H. Davy’s experimental researches on fluoric 
 acid, which were published in the second 
 part of the Philosophical Transactions for 
 1813. Pie did all which the existing re- 
 sources of science could enable genius and 
 judgment to accomplish. The mystery in 
 which the subject obviously and confes- 
 sedly remains, must be removed by fur- 
 ther investigations, and not by analogical 
 assumptions. These, indeed, by giving rest- 
 ing points to the imagination, of which it 
 becomes fond, powerfully tend to obstruct 
 the advancement of truth. 
 
 The principal reason for considering 
 fluoric acid as a compound of fluorine with 
 
 hydrogen, seems on the whole to be the 
 analogy of chlorine. Put the analogy is in- 
 complete. Certainly it is consonant to the 
 true logic of chemical science to regard 
 chlorine as a simple body, since every at- 
 tempt to resolve it into simpler forms of 
 matter has failed. But fluorine has not been 
 exhibited in an insulated state like chlorine ; 
 and here therefore the analogy does not hold. 
 
 With the view of separating its hydrogen, 
 Sir II. Davy applied the power of the great 
 voltaic batteries of the Royal Institution 
 to the liquid fluoric acid. “ In this case, 
 gas appeared to be produced from both 
 the negative and positive surfaces; but it 
 was probably only the undecompounded acid 
 rendered gaseous, which was evolved at the 
 positive surface ; for during the operation 
 the fluid became very hot, and speedily 
 diminished.” “ In the course of these in- 
 vestigations I made several attempts to de- 
 tach hydrogen from the liquid fluoric acid, 
 by the agency of oxygen and chlorine. It 
 was not decomposed when passed through 
 a platina tube heated red hot with chlorine, 
 nor by being distilled from salts containing 
 abundance of oxygen, or those containing 
 abundance of chlorine.” By the strict rules 
 of chemical logic, therefore, fluoric acid ought 
 to be regarded as a simple body, for we 
 have no evidence of its ever having been de- 
 compounded ; and nothing but analogy with 
 the other acid bodies has given rise to the 
 assumption of its being a compound. 
 
 There is no difficulty in imagining a radical 
 to exist, whose saturating powers are exactly 
 one-third of those of hydrogen ; for 0.515 is 
 precisely thrice 0.1 25, the weight of the 
 prime equivalent of hydrogen ; and one- half 
 of 0.750, the equivalent of carbon. Those 
 who are allured by the harmony of numbers, 
 might possibly consider these examples of 
 accordance, as of some value in the dis- 
 cussion. 
 
 The marvellous activity of fluoric acid may 
 be inferred from the following remarks of 
 Sir H. Davy, from which also may be esti- 
 mated in some measure the prodigious diffi- 
 culty attending refined investigations on this 
 extraordinary substance. 
 
 “ I undertook the experiment of electrizing 
 pure liquid fluoric acid with considerable in- 
 terest, as it seemed to offer the most probable 
 method of ascertaining its real nature ; but 
 considerable difficulties occurred in executing 
 the process. The liquid fluoric acid imme- 
 diately destroys glass, and all animal and 
 vegetable substances ; it acts on all bodies 
 containing metallic oxides ; and I know of 
 no substances which are not rapidly dissolved 
 or decomposed by it, except metals, charcoal, 
 phosphorus, sulphur, and certain combina- 
 tions of chlorine. I attempted to make tubes 
 of sulphur, of muriates of lead, and of cop- 
 per containing metallic wires, by which it 
 
A Cl 
 
 ACI 
 
 might be electrized, but without success. I 
 succeeded, however, in boring a piece of 
 horn silver in such a manner that I was able 
 to cement a platina wire into it by means of 
 a spirit lamp; and by inverting this in a tray 
 of platina, filled with liquid fluoric acid, I 
 contrived to submit the fluid to the agency 
 of electricity in such a manner, that, in suc- 
 cessive experiments, it was possible to collect 
 any elastic fluid that might be produced. 
 Operating in this way with a very weak vol- 
 taic power, and keeping the apparatus cool 
 by a freezing mixture# I ascertained that the 
 platina wire at the positive pole rapidly cor- 
 roded, and became covered with a chocolate 
 powder ; gaseous matter separated at the 
 negative pole, which I could never obtain in 
 sufficient quantities to analyze with accuracy, 
 but it inflamed like hydrogen. No other in- 
 flammable matter was produced when the 
 acid was pure.” We beg to refer the reader 
 to the Philosophical Transactions for 1813 
 and 1814; or the 42d and 43d vols. of Til- 
 loch’s Magazine, where he will see philoso- 
 phical sagacity and experimental skill in their 
 utmost variety and vigour, struggling with 
 the most mysterious and intractable powers 
 of matter. 
 
 If instead of being distilled in metallic 
 vessels, the mixture of fluor spar and oil of 
 vitriol be distilled in glass vessels, little of 
 the corrosive liquid will be obtained ; but 
 the glass will be acted upon, and a peculiar 
 gaseous substance will be produced, which 
 must be collected over mercury. The best 
 mode of procuring this gaseous body is to 
 mix the fluor spar with pounded glass or 
 quartz ; and in this case, the glass retort 
 may be preserved from corrosion, and the 
 gas obtained in greater quantities. This 
 gas, which is called silicated fluoric gas, is 
 possessed of very extraordinary properties. 
 
 It is very heavy; 100 cubic inches of it 
 weigh 110.77 gr. and hence its sp. gr. is to 
 that of air, as 3.632 is to 1.000. It is about 
 48 times denser than hydrogen. When 
 brought into contact with water, it instantly 
 deposits a white gelatinous substance, which 
 is hydrate of silica ; it produces white fumes 
 when suffered to pass into the atmosphere. 
 It is not affected by any of the common 
 combustible bodies ; but when potassium is 
 strongly heated in it, it takes fire and burns 
 with a deep red light ; the gas is absorbed, 
 and a fawn-coloured substance is formed, 
 which yields alkali to water with slight effer- 
 vescence, and contains a combustible body. 
 The washings afford potash and a salt, from 
 which the strong acid fluid previously de- 
 scribed, may be separated by sulphuric acid. 
 
 The gas formed by the action of liquid 
 sulphuric acid on a mixture containing silica 
 and fluor spar, the silicated fluoric gas or 
 fluo-silicic acid, may be regarded as a 
 
 compound of fluoric acid and silica. It 
 affords, when decomposed by solution of am- 
 monia, 6T.4 per cent of silica; and hence 
 was at first supposed by Sir H. Davy to con- 
 sist of two prime proportions of acid = 2.632 
 and one of silica = 4.066, the sum of which 
 numbers may represent its equivalent = 
 6.718. One volume of it condenses two 
 volumes of ammonia, and they form toge- 
 ther a peculiar saline substance which is de- 
 composed by water. The composition of 
 this salt is easily reconciled to the numbers 
 given as representing silica and fluoric 
 acid, on the supposition that it contains 1 
 prime of ammonia to 1 of the fluosilicic gas ; 
 for 200 cubic inches of ammonia weigh 
 36.2 gr. and 100 of the acid gas 110.77. 
 Now 36.2 : 2.13 : : 110.77 : 6.52. 
 
 Dr John Davy obtained, by exposing that 
 
 gas to the action of water, of its weight 
 
 of silica ; and from the action of water of 
 ammonia he separated of its weight. 
 
 Hence 100 cubic inches consist by weight of 
 68 silica and 42 of unknown fluoric matter, 
 the gas which holds the silica in solution. 
 Sir H. Davy, however, conceives that this 
 gas is a compound of the basis of silica, or 
 silicon, with fluorine, the supposed basis of 
 fluoric acid. 
 
 If, instead of glass or silica, the fluor spar 
 be mixed with dry vitreous boracic acid, and 
 distilled in a glass vessel with sulphuric 
 acid, the proportions being one part boracic 
 acid, two fluor spar, and twelve oil of vitriol, 
 the gaseous substance formed is of a different 
 kind, and is called the fluoboric gas. 100 
 cubic inches of it weigh 73.5 gr. according 
 to Sir II. Davy, which makes its density to 
 that of air as 2.41 is to 1.00 ; but M. The- 
 nard, from Dr John Davy, states its density 
 to that of air as 2.371 to 1 .000. It is colour- 
 less ; its smell is pungent, and resembles that 
 of muriatic acid ; it cannot be breathed with- 
 out suffocation ; it extinguishes combustion ; 
 and reddens strongly the tincture of turnsole. 
 It has no manner of action on glass ; but a 
 very powerful one on vegetable and animal 
 matter : It attacks them with as much force 
 as concentrated sulphuric acid, and appears 
 to operate on these bodies by the production 
 of water ; for while it carbonizes them, or 
 evolves carbon, they may be touched without 
 any risk of burning. Exposed to a high tem- 
 perature, it is not decomposed ; it is condensed 
 by cold without changing its form. When 
 it is put in contact with oxygen, or air, either 
 at a high or low temperature, it experiences 
 no change, except seizing, at ordinary tempe- 
 ratures, the moisture which these gases con- 
 tain. It becomes in consequence a liquid which 
 emits extremely dense vapours. It operates 
 in the same way with all the gases which 
 contain liygrometric water. However little 
 they may contain, it occasions in them very 
 
ACi 
 
 ACI 
 
 perceptible vapours. It may hence be em- 
 ployed with advantage to shew whether or 
 not a gas contains moisture. 
 
 No combustible body, simple or compound, 
 attacks iluoboric gas, if we except the alka- 
 line metals. Potassium and sodium with 
 the aid of heat, burn in this gas, almost as 
 brilliantly as in oxygen. Boron, and fluate 
 ot potash, are the products of this decomposi- 
 tion. It might hence be inferred that the 
 metal seizes the oxygen of the boracic acid, 
 sets the boron at liberty, and is itself oxidized 
 and combined with the fluoric acid. Ac- 
 cording to Sir II. Davy’s views, the fluoboric 
 gas being a compound of fluorine and boron, 
 the potassium unites to the former, giving 
 rise to the fluoride of potassium, while the 
 boron remains disengaged. 
 
 o o 
 
 Fluoboric gas is very soluble in water. Dr 
 John Davy says, water can combine with 
 700 times its own volume, or twice its 
 weight at the ordinary temperature and pres- 
 sure of the air. The liquid has a specific 
 gravity of 1.770. If a bottle containing this 
 gas be uncorked under water, the liquid will 
 rush in and fill it with explosive violence. 
 Water saturated with this gas is limpid, 
 fuming and very caustic. By heat, about 
 one- fifth of the absorbed gas may be expelled ; 
 but it is impossible to abstract more. It 
 then resembles concentrated sulphuric acid, 
 and boils at a temperature considerably above 
 212°. It afterwards condenses altogether, 
 in stride , although it contains still a very large 
 quantity of gas. It unites with the bases, 
 forming salts, called fluoborates, none of 
 which has been applied to any use. The most 
 important will be described under their respec- 
 tive bases. 
 
 The 2d part of the Phil. Transactions for 
 1812, contains an excellent paper by Dr 
 John Davy on fluosilicic and fluoboric gases, 
 and the combinations of the latter with am- 
 moniacal gas. When united in equal vo- 
 lumes, a pulverulent salt is formed ; a second 
 volume of ammonia, however, gives a liquid 
 compound ; and a third of ammonia, which 
 is the limit of combination, affords still a li- 
 quid ; both of them curious on many ac- 
 counts. “ They are,” says he, “ the first 
 salts that have been observed liquid at the 
 common temperature of the atmosphere. 
 And they are additional facts in support of 
 the doctrine of definite proportions, and of 
 the relation of volumes.” The fluosilicic 
 acid also unites to bases forming fluosilicates. 
 
 If we regard fluoric acid as capable of com- 
 bining, like the sulphuric, nitric, and carbonic 
 acids, with the oxidized bases, the weight of 
 its prime equivalent is 1.375 ; whence all its 
 neutral compounds may be inferred ; but if 
 we suppose that it is fluorine alone which 
 unites to the metallic bases, then the prime 
 of oxygen must be subtracted from them and 
 added to its w r eight, which will make it 
 
 2.375. This is exactly like a man taking a 
 piece of money out of the one pocket, and 
 putting it in the other. All the proportions 
 experimentally associated with the com- 
 pound, remain essentially the same.* 
 
 From the remarkable property fluoric acid 
 possesses of corroding glass, it has been 
 employed for etching on it, both in the 
 gaseous state and combined with w ater ; and 
 an ingenious apparatus for this purpose is 
 given by Mr Richard Knight, in the Philo- 
 sophical Magazine, vol. xvii. p. 357. 
 
 M. Kortum, of Warsaw, having found 
 that some pieces of glass were more easily 
 acted upon by it than others, tried its ef- 
 fect on various stones. Rock crystal, ruby, 
 sapphire, lux sapphire, emerald, oriental 
 garnet, amethyst, chrysolite, aventurine, gir- 
 asol, a Saxon topaz, a Brazilian topaz 
 burnt, and an opal, being exposed to the 
 fluoric gas at a temperature of 122° F. 
 were not acted upon. Diamond exposed 
 to the vapour on a common German stove 
 for four days, w 7 as unaffected. Of polished 
 granite, neither the quartz nor mica ap- 
 peared to be attacked, but the feldt-spar 
 w f as rendered opaque and muddy, and cover- 
 ed with a white powder. Chrysoprase, 
 an opal from Hungary, onyx, a carnelian 
 from Persia, agate, chalcedony, green Sibe- 
 rian jasper, and common flint, were etched 
 by it in twenty- four hours ; the chrysoprase 
 near half a line deep, the onyx pretty deep- 
 ly, the opal with the finest and most regu- 
 lar strokes, and all the rest more or less 
 irregularly. The uncovered part of the 
 brown flint had become white, but was still 
 compact : water, alcohol, and other liquids, 
 rendered the whiteness invisible, but as soon 
 as the flint became dry, it appeared again. 
 The same effect was produced on carnelian, 
 and on a dark brown jasper, if the operation 
 of the acid w^ere stopped, as soon as it had 
 whitened the part exposed, without destroy- 
 ing its texture. A piece of black flint, with 
 efflorescent white spots, and partly covered 
 wfith the common white crust, being exposed 
 five days to the gas at a heat of about 63° F. 
 was reduced from 105 grains to 91, and 
 rendered white throughout. Some parts of 
 it were rendered friable. White Carrara mar- 
 ble in twenty- four hours, at 77°, lost l-30th 
 of its weight, but the shining surface of its 
 crystallized texture w as distinguishable. Black 
 marble was not affected, either in weight or 
 colour, and agate w as not attacked. Trans- 
 parent foliated gypsum fell into white pow- 
 der on its surface, in a few' hours; hut this 
 powder was not soluble in dilute nitric acid, 
 
 — so that the fluoric acid had not destroyed 
 
 ¥ 
 
 the combination of its principles; but de- 
 prived it of its water of crystallization. A 
 striated zeolite, weighing 102 grains, was 
 rendered friable on its surface in forty-eight 
 hours, and weighed only 85-1 grains. On 
 
 ' C’ r ** 1- 
 
ACI 
 
 ACI 
 
 being immersed in water, and then dried, it 
 gained 2\ grains, but did not recover its lus- 
 tre. Barytes of a fibrous texture remained 
 unchanged. A thin plate of \ enetian talc, 
 weighing 124 grains, was reduced to 81 
 grains in forty-eight hours, and had fallen 
 into a soft powder, which floated on water. 
 
 M. Kortum poured water on the residuum 
 in the apparatus, and the next day the sides 
 were incrusted with small crystalline glitter- 
 ing flakes, adhering in detached masses, 
 which could not be washed off with dilute 
 nitrous acid. 
 
 Of the combinations of this acid with most 
 of the bases little is known. 
 
 The native fluate of lime, the fluor spar 
 already mentioned, is the most common. It 
 is rendered phosphorescent by heat, but this 
 property gradually goes off, and cannot be 
 produced a second time. With a strong 
 heat it decrepitates. At a heat of 130° of 
 Wedgwood, it enters into fusion in a clay 
 crucible. It is not acted upon by the air, 
 and is insoluble in water. Concentrated 
 sulphuric acid deprives it of the fluoric 
 acid with effervescence, at the common tem- 
 perature, but heat promotes its action. Be- 
 sides its use for obtaining this acid, it is 
 much employed in chimney ornaments, and 
 as a flux for some ores and stones. 
 
 The fluoric acid takes barytes from the 
 nitric and muriatic, and forms a salt very 
 little soluble, that effloresces in the air. 
 
 With magnesia, it precipitates, according 
 to Scheele, in a gelatinous mass. But Berg- 
 man says, that a part remains in solution, 
 and by spontaneous evaporation, shoots on 
 the sides of the vessel into crystalline 
 threads, resembling a transparent mass. 
 The bottom of the vessel affords also cry- 
 stals in hexagonal prisms, ending in a low 
 pyramid of three rhombs. He adds, that 
 no acid decomposes it in the moist way, 
 and that it is unalterable by the most vio- 
 lent fire. 
 
 The fluate of potash is not crystallizable ; 
 and if it be evaporated to dryness, it soon 
 deliquesces. Its taste is somewhat acrid and 
 saline. It melts with a strong heat, is after- 
 ward caustic, and attracts moisture. 
 
 This fluate, as well as those of soda and 
 ammonia, are commonly obtained, as Four- 
 croy conceives, in the state of triple salts, 
 being combined with siliceous earth. 
 
 The fluate of soda affords small crystals 
 in cubes and parallelograms, of a bitterish 
 and astringent taste, decrepitating on burn- 
 ing coals, and melting into semitransparent 
 globules with the blowpipe, without losing 
 their acid. It is not deliquescent, and diffi- 
 cultly soluble. The concentrated acids disen- 
 gage its acid with effervescence. 
 
 The fluate of ammonia may be prepared 
 by adding carbonate of ammonia to diluted 
 fluoric acid in a leaden vessel, observing, 
 
 7 O 7 
 
 that there is a small excess of acid, lhis 
 is a very delicate test of lime. 
 
 Fourcroy informs us, that ammonia and 
 magnesia form a triple salt with the fluoric 
 acid. 
 
 Scheele observed, that the fluor acid unit- 
 ed with alumina into a salt that could not 
 be crystallized, but assumed a gelatinous 
 form. Fourcroy adds, that the solution is 
 always acid, astringent, decomposable and 
 precipitable by all the earthy and alkaline 
 bases, but capable of uniting with silex 
 and the alkalis into various triple salts. A 
 native combination of alumina and soda 
 with fluoric acid, has been found lately in a 
 semitransparent stone from Greenland. See 
 Cryolite. 
 
 The affinity of the fluoric acid for silex, 
 has already appeared. If the acid solution 
 of fluate of silex, obtained by keeping the 
 solution of the acid in glass vessels, be eva- 
 porated to dryness, the fluoric acid may be 
 disengaged from the solid salt remaining, 
 as Fourcroy informs us, either by the pow- 
 erful acids, or by a strong heat; and if the 
 solution be kept in a vessel that admits of 
 a slow evaporation, small brilliant crystals, 
 transparent, hard, and apparently of a rhom- 
 boidal figure, will form on the bottom of the 
 vessel, as Bergman found in the course of 
 two years’ standing. 
 
 Beside the fluor spar and cryolite, in which 
 it is abundant, fluoric acid has been detect- 
 ed in the topaz ; in wavellite, in w hich, how- 
 ever, it is not rendered sensible by sulphu- 
 ric acid ; and in fossil teeth and fossil ivory, 
 though it is not found in either of these in 
 their natural state. 
 
 Acids (Ferrofrussic and Ferruretted 
 Chyazic). See Acid (Prussic). 
 
 Acid (Formic). It has long been known, 
 that ants contain a strong acid, which they 
 occasionally emit ; and which may be ob- 
 tained from the ants, either by simple distil- 
 lation, or by infusion of them in boiling w a- 
 ter, and subsequent distillation of as much 
 of the water as can be brought over with- 
 out burning the residue After this it may 
 be purified by repeated rectifications, or by 
 boiling to separate the impurities ; or after 
 rectification it may be concentrated by frost. 
 
 * This acid has a very sour taste, and conti- 
 nues liquid even at very iow temperatures. Its 
 specific gravity is 1.1168 at 68°, which is 
 much denser than acetic acid ever is. Ber- 
 zelius finds, that the formiate of lead consists 
 of 4.696 acid, and 14 oxide of lead; and 
 that the ultimate constituents of the dry acid 
 are hydrogen 2.84 -{- carbon 32.40 + ox- 
 ygen 64.76 = 100.* 
 
 We have been informed, that it has been 
 employed among quacks, as a wonderful re- 
 medy for the toothach, by applying it to 
 the tooth with the points of the forefinger 
 and thumb. 
 
ACI 
 
 ACI 
 
 * Acid ( Fungic). The expressed juice of 
 the boletus juglandis, boletus pseudo- ig uiarius, 
 the phallus irnpudicus , merulius cantharellus , 
 or the peziza nigra, being boiled to coagulate 
 the albumen, then filtered, evaporated to the 
 consistence of an extract, and acted on by 
 pure alcohol, leaves a substance which has 
 been called by Braconnot Fungic Acid. lie 
 dissolved that residue in water, added solu- 
 tion of acetate of lead, whence resultedyim- 
 gate of' lead, which he decomposed at a gen- 
 tle heat by dilute sulphuric acid. The evolv- 
 ed fungic acid being saturated with ammo- 
 nia, yielded a crystallized fungate of ammo- 
 nia, which he purified by repeated solution 
 and crystallization. From this salt by ace- 
 tate of lead, and thereafter sulphuric acid as 
 above detailed, he procured the pure fungic 
 acid. 
 
 It is a colourless, uncrystallizable, and 
 deliquescent mass, of a very sour taste. The 
 fungates of potash and soda, are uncrystalliz- 
 able ; that of ammonia forms regular six-sid- 
 ed prisms ; that of lime is moderately soluble, 
 and is not affected by the air ; that of barytes 
 is soluble in 15 times its weight of water, and 
 crystallizes with difficulty; that of magnesia 
 appears in soluble granular crystals. This 
 acid precipitates from the acetate of lead a 
 white flocculent fungate, which is soluble in 
 distilled vinegar. When insulated, it does 
 not affect solution of nitrate of silver; but 
 the fungates decompose this salt. * 
 
 Acid (Gallic). This acid is found in 
 different vegetable substances possessing as- 
 tringent properties, but most abundantly in 
 the excrescences termed galls, or nut-galls, 
 whence it derives its name. It may be ob- 
 tained by macerating galls in water, filter- 
 ing, and suffering the liquor to stand ex- 
 posed to the air. It will grow mouldy, be 
 covered with a thick glutinous pellicle, 
 abundance of glutinous flocks will fall down, 
 and, in the course of two or three months, 
 the sides of the vessel will appear covered 
 with small yellowish crystals, abundance of 
 which will likewise be found on the under 
 surface of the supernatant pellicle. These 
 crystals may be purified by solution in alco- 
 hol, and evaporation to dryness. 
 
 Or muriate of tin may be added to the 
 infusion of galls, till no more precipitate falls 
 down ; the excess of oxide of tin remaining 
 in the solution, may then be precipitated by 
 sulphuretted hydrogen gas, and the liquor will 
 yield crystals of gallic acid by evaporation. 
 
 A more simple process, however, is that 
 of M. Fiedler. Boil an ounce of powder- 
 ed galls in sixteen ounces of water to eight, 
 and strain. Dissolve two ounces of alum in 
 water, precipitate the alumina by carbonate 
 of potash ; and, after edulcorating it com- 
 pletely by repeated ablutions, add it to the 
 decoction, frequently stirring the mixture 
 with a glass rod. The next day filter the 
 
 mixture; wash the precipitate with warm 
 water, till this will no longer blacken sul- 
 phate of iron ; mix the washings w ith the 
 filtered liquor, evaporate, and the gallic acid 
 will be obtained in fine needled crystals. 
 
 These crystals obtained in any of these 
 w ays, how ever, according to Sir II. Davy, are 
 contaminated with a small portion of ex- 
 tractive matter; and to purify them they 
 may be placed in a glass capsule in a sand 
 heat, and sublimed into another capsule, 
 inverted over this and kept cool. I\I. De- 
 yeux indeed recommends to procure the acid 
 by sublimation in the first instance; putting 
 the powdered galls into a glass retort, and 
 applying heat slowly and cautiously ; when 
 the acid will rise, and be condensed in the 
 neck of the retort. This process requires 
 great care, as, if the heat be carried so far as 
 to disengage the oil, the crystals will be dis- 
 solved immediately. The crystals thus ob- 
 tained are pretty large, laminated, and brilliant. 
 
 The gallic acid, placed on a red-hot 
 iron, burns with flame, and emits an aro- 
 matic smell, not unlike that of benzoic acid. 
 It is soluble in 20 parts of cold water, and 
 in 5 parts at a boiling heat. It is more 
 soluble in alcohol, which takes up an equal 
 weight if heated, and one-fourth of its w r eight 
 cold. 
 
 * It has an aeido-astringent taste, and red- 
 dens tincture of litmus. It does not attract 
 humidity from the air. 
 
 From the gallate of lead, Berzelius infers 
 the equivalent of this acid to be 8.00. Its 
 ultimate constituents are, hydrogen 5.00 -f- 
 carbon 56.64 -j- oxygen 38.36= 100. 
 
 This acid, in its combinations with the sa- 
 lifiable bases, presents some remarkable phe- 
 nomena. If we pour its aqueous solution by 
 slow degrees into lime, barytes, or strontites 
 w r ater, there will first be formed a greenish 
 white precipitate. As the quantity of acid is 
 increased, the precipitate changes to a violet 
 hue, and eventually disappears. The liquid 
 has then acquired a reddish tint. Among 
 the salts those only of black oxide, and red 
 oxide of iron, are decomposed by the pure 
 gallic acid. It forms a blue precipitate with 
 the first, and a browm with the second. But 
 w hen this acid is united w ith tannin, it de- 
 composes almost all the salts of the permanent 
 metals. * 
 
 Concentrated sulphuric acid decomposes 
 and carbonizes it ; and the nitric acid con- 
 verts it into malic and oxalic acids. 
 
 United with barytes, strontian, lime, and 
 magnesia, it forms salts of a dull yellow' 
 colour, which are little soluble, but more 
 so if their base be in excess. With alkalis, 
 it forms salts that are not very soluble in ge- 
 neral. 
 
 Its most distinguishing characteristic is its 
 
 O O 
 
 great affinity for metallic oxides, so as, when 
 combined with tannin, to take them from 
 
ACI 
 
 ACI 
 
 powerful acids. The more readily the me- 
 tallic oxides part with their oxygen, the more 
 they are alterable by the gallic acid. l o a 
 solution of gold, it imparts a green hue; 
 and a brown precipitate is formed, which 
 readily passes to the metallic state, and co- 
 vers the solution with a shining golden pelli- 
 cle. With nitric solution of silver, it pro- 
 duces a similar effect. Mercury it precipi- 
 tates of an orange yellow ; copper, brown ; 
 bismuth, of a lemon colour ; lead, white ; 
 iron, black. Platina, zinc, tin, cobalt, and 
 manganese, are not precipitated by it. 
 
 The gallic acid is of extensive use in the 
 art of dyeing, as it constitutes one of the 
 principal ingredients in all the shades of black, 
 and is employed to fix or improve several 
 other colours. It is well known as an ingre- 
 dient in ink. See Galls, Dyeing and Ink. 
 
 * Acid (Hydrocyanic). See Acid (Prus- 
 sic). 
 
 * Acid (IIydriodic). This acid resembles 
 the muriatic in being gaseous in its insulat- 
 ed state. If four parts of iodine be mixed 
 with one of phosphorus, in a small glass re- 
 tort, applying a gentle heat, and adding a 
 few drops of water from time to time, a gas 
 comes over, which must be received in the 
 mercurial bath. Its specific gravity is 4.4; 
 100 cubic inches, therefore, weigh 134.2 
 grains. It is elastic and invisible, but has a 
 smell somewhat similar to that of muriatic 
 acid. Mercury after some time decomposes 
 it, seizing its iodine, and leaving its hydrogen 
 equal to one* half the original bulk, at liberty. 
 Chlorine, on the other hand, unites to its hy- 
 drogen, and precipitates the iodine. From 
 these experiments, it evidently consists of va- 
 pour of iodine and hydrogen, which combine 
 in equal volumes, without change of their 
 primitive bulk. Its composition by weight, 
 is therefore 8.61 of iodine + 0.0694 hydro- 
 gen, which is the relation of their gasiform 
 densities; and if 8.61 be divided by 0.0694, 
 it will give the prime of iodine 124 times 
 greater than hydrogen ; and a9 the prime of 
 oxygen is eight times more than that of hy- 
 drogen, on dividing 124 by 8, we have 15.5 
 for the prime equivalent of iodine ; to which, 
 if we add 0.125, the sum 15.625 represents 
 the equivalent of hydriodic acid. The num- 
 ber deduced for iodine, from the relation of 
 iodine to hydrogen in volume, approaches 
 very nearly to 15.621, which was obtained in 
 the other experiments of M. Gay Lussac. 
 Hydriodic acid is partly decomposed at a red 
 heat, and the decomposition is complete, if 
 it be mixed with oxygen. Water is formed 
 and iodine separated. 
 
 M. Gay Lussac, in his admirable memoir 
 on iodine and its combinations, published in 
 the Ann. de Chimie, vol. xci. says, that the 
 specific gravity he there gives for hydriodic 
 gas, viz. 4.443, must be a little too great, for 
 traces of moisture were seen in the inside of 
 
 the bottle. In fact, if we take 15. 621 as the 
 prime of iodine to oxygen, whose specific 
 gravity is 1. 1 1 1 1 ; and multiply one-half ot 
 this number by 15.621, as he does, we shall 
 have a product of 8.6696, to which adding 
 0.0694 for the density of hydrogen, we get 
 the sum 8.7390, one-half of which is ob- 
 viously the density of the hydriodic gas = 
 4.3695. When the prime of iodine is taken 
 at 15.5, then the density of the gas comes 
 out 4.3. 
 
 We can easily obtain an aqueous hy- 
 driodic acid very economically, by pass- 
 ing sulphuretted hydrogen gas through a 
 mixture of water and iodine in a Woolfe’s 
 bottle. On heating the liquid obtained, the 
 excess of sulphur flies off, and leaves liquid 
 hydriodic acid. At temperatures below 
 262°, it parts with its water ; and becomes of 
 a density = 1.7. At 262° the acid distils 
 over. When exposed to the air, it is speedi- 
 ly decomposed, and iodine is evolved. Con- 
 centrated sulphuric and nitric acids also de- 
 compose it. When poured into a saline so- 
 lution of lead, it throws down a fine orange 
 precipitate. With solution of peroxide of 
 mercury, it gives a red precipitate ; and 
 with that of silver, a white precipitate inso- 
 luble in ammonia. Hydriodic acid may 
 also be formed, by passing hydrogen over 
 iodine at an elevated temperature. 
 
 The compounds of hydriodic acid with 
 the salifiable bases may be easily formed, 
 either by direct combination, or by acting on 
 the basis in water, with iodine. The lat- 
 ter mode is most economical. Upon a deter- 
 minate quantity of iodine, pour solution of 
 potash or soda, till the liquid ceases to be 
 coloured. Evaporate to dryness, and digest 
 the dry salt in alcohol of the specific gravity 
 0.810, or 0.820. As the iodate is not solu- 
 ble in this liquid, while the hydriodate is 
 very soluble, the two salts easily separate 
 from each other. After having washed the 
 iodate two or three times with alcohol, dis- 
 solve it in water, and neutralize it with ace- 
 tic acid. Evaporate to dryness, and digest 
 the dry salt in alcohol, to remove the acetate. 
 After two or three washings, the iodaie is 
 pure. As for the alcohol containing the hy- 
 driodate, distil it oft’, and then complete the 
 neutralization of the potash, by means of 
 a little hydriodic acid separately obtained. 
 Sulphurous and muriatic acids, as well as 
 sulphuretted hydrogen, produce no change 
 on the hydriodates, at the usual temperature 
 of the air. 
 
 Chlorine, nitric acid, and concentrated sul- 
 phuric, instantly decompose them, and sepa- 
 rate the iodine. 
 
 With solution of silver, they give a white 
 precipitate insoluble in ammonia; with the 
 pernitrate of mercury, a greenish yellow pre- 
 cipitate ; with corrosive sublimate, a precipi- 
 tate of a fine orange red, very soluble in an 
 
ACI 
 
 AC1 
 
 excess of hydriodate ; and with nitrate of 
 lead, a precipitate of an orange yellow co- 
 lour. 1 hey dissolve iodine, and acquire a 
 deep reddish brown colour. 
 
 Hydriodate of potash , or in the dry state, 
 iodide of potassium, yields crystals like sea- 
 salt, which melt and sublime at a red heat. 
 This salt is not changed by being heated in 
 contact with air. 100 parts of water at 64°, 
 dissolve 145 of it. It consists of 15.5 io- 
 dine, and 4.95 potassium. 
 
 Hydriodate of soda , called in the dry state 
 iodide of sodium, may be obtained in pretty 
 large flat rhomboidal prisms. These prisms 
 unite together with larger ones, terminated 
 in echellon, and striated longways, like those 
 of sulphate of soda. This is a true hydrio- 
 date, for it contains much water of crvstalli- 
 zation. It consists, when dry, of 15.5 iodine 
 + 2.95 sodium. 
 
 Hydriodate of barytes crystallizes in fine 
 prisms, similar to muriate of strontites. In 
 its dry state, it consists of 15.5 iodine — }— 8. 7 
 or 8.75 barium. 
 
 The hydriodates of lime and strontites are 
 very soluble ; and the first exceedingly deli- 
 quescent. 
 
 Hydriodate of ammonia results from the 
 combination of equal volumes of ammonia- 
 cal and hydriodic gases; though it is usually 
 prepared by saturating the liquid acid with 
 ammonia. It is nearly as volatile as sal am- 
 moniac ; but it is more soluble and more de- 
 liquescent. It crystallizes in cubes. From 
 this compound, we may infer the prime of 
 hydriodic acid, from the specific gravity of the 
 hydriodic gas ; or having the prime, we may 
 determine/the sp. gr. If we call 15.625 its 
 equivalent, then we have this proportion : — 
 As a prime of ammonia, to a prime of hydri- 
 odic acid, so is the density of ammoniacal, to 
 that of hydriodic gas. 
 
 2.13 : 15.625 : : 0.59 : 4.328. 
 
 This would make 100 cubic inches weigh 
 exactly 132 grains. 
 
 Hydriodate of magnesia is formed by unit- 
 ing its constituents together; it is deliques- 
 cent, and crystallizes with difficulty. — It is 
 decomposed by a strong heat. 
 
 Hydriodate of zinc is easily obtained, by 
 putting iodine into water with an excess of zinc, 
 and favouring , their action by heat. When 
 dried it becomes an iodide. 
 
 All the hydriodates have the property of 
 dissolving abundance of iodine; and thence 
 they acquire a deep reddish brown colour. 
 They part with it on boiling, or when expos- 
 ed to the air after being dried.* 
 
 * Acid ( Iodic). When barytes water is made 
 to act on iodine, a soluble hydriodate, and an 
 insoluble iodate of barytes, are formed. On 
 the latter, well washed, pour sulphuric acid 
 equivalent to the barytes present, diluted with 
 twice its weight of water, and heat the mix- 
 ture. The iodic acid quickly abandons a por- 
 
 tion of its base, and combines with the water ; 
 but though even less than the equivalent pro- 
 portion of sulphuric acid has been used, a little 
 of it w ill be found mixed w ith the liquid acid. 
 If we endeavour to separate this portion, by 
 adding barytes water, the two acids precipi- 
 tate together. 
 
 The above economical process is that of 
 M. Gay Lussac ; but Sir H. Davy, who is 
 the first discoverer of this acid, invented one 
 more elegant, and which yields a purer 
 acid. Into a long glass tube, bent like the 
 letter L inverted ( r j), shut at one end, put 
 100 grains of chlorate of potash, and pour 
 over it 400 grains of muriatic acid, specific 
 gravity 1.105. Put 40 grains of iodine 
 into a thin long- necked receiver. Into the 
 open end of the bent tube put some muriate 
 of lime, and then connect it with the receiver. 
 Apply a gentle heat to the sealed end of the 
 former. Protoxide of chlorine is evolved, 
 which, as it comes in contact with the iodine, 
 produces combustion, and two new com- 
 pounds, a compound of iodine and oxygen, 
 and one of iodine and chlorine. The latter 
 is easily separable by heat, while the former 
 remains in a state of purity. 
 
 The iodic acid of Sir H. Davy is a white 
 semi-transparent solid. It has a strong acido- 
 astringent taste, but no smell. Its density is 
 considerably greater than that of sulphuric 
 acid, in which it rapidly sinks. It melts, and 
 is decomposed into iodine and oxygen, at a 
 temperature of about 620°. A grain of io- 
 dic acid gives out 176.1 grain measures of 
 oxygen gas. It w r ould appear from this, 
 that iodic acid consists of 15.5 iodine, to 5 
 oxygen. This agrees with the determination 
 of M. Gay Lussac, obtained from much great- 
 er quantities ; and must therefore excite ad- 
 miration at the precision of result derived by 
 Sir H. from the very minute proportions 
 which he used. 176.1 grain measures, are 
 equal to 0.7 of a cubic inch ; which, calling 
 100 cubic inches 33.88, will weigh 0.237 of 
 a grain, leaving 0.763 for iodine. And 
 0.763 : 0.237 : : 15.5 : 5.0. 
 
 Iodic acid deliquesces in the air, and is, 
 of course, very soluble in water. It first 
 reddens, and then destroys the blues of ve- 
 getable infusions. It blanches other vege- 
 table colours. By concentration of the li- 
 quid acid of Gay Lussac, it acquires the con- 
 sistence of syrup. Had not the happy ge- 
 nius of Sir II. Davy produced it in the so- 
 lid state, his celebrated French rival would 
 have persuaded us to suppose that state im- 
 possible. “ Hitherto,” says M. Gay Lussac, 
 
 “ iodic acid has only been obtained in com- 
 bination with water, and it is very probable 
 that this liquid is as necessary as a base, to 
 keep the elements of the acid united, as we 
 see is the case with sulphuric acid, nitric 
 acid,” Sec. M. Gay Lussac’s Memoir was 
 read to the Institute on the 1st August 
 
A Cl 
 
 1814; and, on the 10th February following, 
 Sir H. dates at Rome his communication to 
 the Royal Society, written before he had 
 seen the French paper. When the tempera- 
 ture of inspissated iodic acid is raised to 
 about 392°, it is resolved into iodine and 
 oxygen. Here we see the influence of wa- 
 ter is exactly the reverse of what M. Gay 
 Lussac assigns to it; for, instead of giving 
 fixity like a base to the acid, it favours its 
 decomposition. The dry acid may be raised 
 to upwards of 600° without being decom- 
 posed. Sulphurous acid, and sulphuretted 
 hydrogen immediately separate iodine from 
 it. Sulphuric and nitric acids have no ac- 
 tion on it. With solution of silver, it gives 
 a white precipitate, very soluble in ammonia. 
 It combines with all the bases, and produ- 
 ces all the iodates which we can obtain by 
 making the alkaline bases act upon iodine 
 in water. It likewise forms with ammonia 
 a salt, which fulminates when heated. Be- 
 tween the acid prepared by M. Gay Lussac, 
 and that of Sir H. Davy, there is one im- 
 portant difference. The latter being dis- 
 solved, may, by evaporation of the water, 
 pass not only to the inspissated syrupy state, 
 but can be made to assume a pasty consis- 
 tence ; and finally, by a stronger heat, yields 
 the solid substance unaltered. When a mix- 
 ture of it, with charcoal, sulphur, rosin, su- 
 gar, or the combustible metals, in a finely 
 divided state, is heated, detonations are pro- 
 duced ; and its solution rapidly corrodes all 
 the metals to which Sir FI. Davy exposed 
 it, both gold and platinum, but much more 
 intensely the first of these metals. 
 
 It appears to form combinations with all 
 the fluid or solid acids which it does not de- 
 compose. When sulphuric acid is dropped 
 into a concentrated solution of it in hot wa- 
 ter, a solid substance is precipitated, which 
 consists of the acid and the compound ; for, 
 on evaporating the solution by a gentle heat, 
 nothing rises but water. On increasing the 
 heat in an experiment of this kind, the solid 
 substance formed fused ; and on cooling the 
 mixture, rhomboidal crystals formed of a 
 pale yellow colour, which were very fusible, 
 and which did not change at the heat at 
 which the compound of oxygen and iodine 
 decomposes, but sublimed unaltered. When 
 urged by a much stronger heat, it partially 
 sublimed and partially decomposed, afford- 
 ing oxygen, iodine, and sulphuric acid. 
 
 ith hydro-phosphoric, the compound 
 presents phenomena precisely similar, and 
 they form together a solid, yellow, crystal- 
 line combination. 
 
 With hydro- nitric acid, it yields white 
 crystals in rhomboidal plates, which, at a 
 lower heat than the preceding acid com- 
 pounds, are resolved into hydro-nitric acid, 
 oxygen, and iodine. By liquid muriatic acid, 
 the substance is immediately decomposed, 
 
 A Cl 
 
 and the compound of chlorine and iodine is 
 formed. All these acid compounds redden 
 vegetable blues, taste sour, and dissolve 
 gold and platinum. F’rom these curious re- 
 searches, Sir H. Davy infers, that M. Gay 
 Lussac’s iodic acid, is a sulpho-iodic acid, 
 and probably a definite compound. How- 
 ever minute the quantity of sulphuric acid 
 made to act on the iodide of barium may be, 
 a part of it is always employed to form the 
 compound acid ; and the residual fluid con- 
 tains both the compound acid and a certain 
 quantity of the original salt. 
 
 In treating of hydriodic acid, we have al- 
 ready described the method of forming the 
 iodates, a class of salts distinguished chiefly 
 for their property of deflagrating when heat- 
 ed with combustibles.* 
 
 * Acid (Chloriodic). The discovery of 
 this interesting compound, constitutes ano- 
 ther of Sir H. Davy’s contributions to the 
 advancement of science. In a communica- 
 tion from Florence to the Royal Society, in 
 March 1814, he gives a curious detail of its 
 preparation and properties. Fie formed it, 
 by admitting chlorine in excess to known 
 quantities of iodine, in vessels exhausted of 
 air, and repeatedly heating the sublimate. 
 Operating in this way, he found that iodine 
 absorbs less than one-third of its weight of 
 chlorine. 
 
 Chloriodic acid is a very volatile sub- 
 stance, and in consequence of its action upon 
 mercury, he was not able to determine the 
 elastic force of its vapour. In the most con- 
 siderable experiment which he made to de- 
 termine proportions, 20 grains caused the 
 disappearance of 9.6 cubical inches of chlo- 
 rine. These weigh 7.296 grains. And 
 20 : 7.296 : ; 15.5 : 5.6, a number certainly 
 not far from 4.5, the prime equivalent of 
 chlorine ; and in the very delicate circum- 
 stances of the experiment, an approximation 
 not to be disparaged. Indeed, the first re- 
 sult in close vessels, giving less than one- 
 third of the weight of chlorine absorbed, 
 comes sufficiently near 4.5, which is just a 
 little less than one-third of 1 5.5, the prime 
 equivalent of iodine. 
 
 The chloriodic acid formed by the subli- 
 mation of iodine in a great excess of chlo- 
 rine, is of a bright yellow colour; when 
 fused it becomes of a deep orange, and when 
 rendered elastic, it forms a deep orange co- 
 loured gas. It is capable of combining with 
 much iodine when they are heated together, 
 its colour becomes, in consequence, deeper, 
 and the chloriodic acid and the iodine rise- 
 together in the elastic state. The solution 
 of the chloriodic acid in water, likewise dis- 
 solves large quantities of iodine, so that it is 
 possible to obtain a fluid containing very dif- 
 ferent proportions of iodine and chlorine. 
 
 When two bodies so similar in their cha- 
 racters, and in the compounds they form, as 
 
ACl 
 
 iodine and chlorine, act upon substances at 
 the same time, it is difficult, Sir H. observes, 
 to form a judgment of the different parts 
 that they play in the new chemical arrange- 
 ment produced. It appears most probable, 
 that the acid property of the chloriodic com- 
 pound depends upon the combination of 
 the two bodies; and its action upon solu- 
 tions of the alkalis and the earths may be 
 easily explained, when it is considered that 
 chlorine has a greater tendency than iodine 
 to form double compounds with the metals, 
 and that iodine has a greater tendency than 
 chlorine to form triple compounds with oxy- 
 gen and the metals. 
 
 A triple compound of this kind with so- 
 dium may exist in sea water, and would be 
 separated with the first crystals that are form- 
 ed by its evaporation. Hence, it may exist 
 in common salt. Sir H. Davy ascertained, 
 by feeding birds with bread soaked with wa- 
 ter, holding some of it in solution, that it is 
 not poisonous like iodine itself.* 
 
 Acid ( IIvdrothionic). Some of the Ger- 
 man chemists distinguish sulphuretted hy- 
 drogen by this name, on account of its pro- 
 perties resembling those of an acid. 
 
 * Acid (Kinic). A peculiar acid ex- 
 tracted by M. Vauquelin from cinchona. 
 Let a watery extract from hot infusions of 
 the bark in powder be made. Alcohol re- 
 moves the resinous part of this extract, and 
 leaves a viscid residue, of a brown colour, 
 which has hardly any bitter taste, and which 
 consists of kinate of lime and a mucilaginous 
 matter. This residue is dissolved in water, 
 the liquor is filtered and left to spontane- 
 ous evaporation, in a warm place. It be- 
 comes thick like syrup, and then deposits 
 by degrees crystalline plates, sometimes hex- 
 ahedral, sometimes rhomboidal, sometimes 
 square, and always coloured slightly of a 
 reddish brown. These plates of kinate of 
 lime must be purified by a second crystalli- 
 zation. They are then dissolved in 10 or 
 12 times their weight of water, and very 
 dilute aqueous oxalic acid is poured into the 
 solution, till no more precipitate is formed. 
 13y filtration, the oxalate of lime is separated, 
 and the kinic acid being concentrated by 
 spontaneous evaporation, yields regular crys- 
 tals. It is decomposed by heat. While it 
 forms a soluble salt with lime, it does not 
 precipitate lead or silver from their solutions. 
 These are characters sufficiently distinctive. 
 The kinates are scarcely known ; that of 
 lime constitutes 7 per cent of cinchona.* 
 
 Acid (Laccic) of Dr John. 
 
 * This chemist made a watery extract of 
 powdered stick lac, and evaporated it to dry- 
 ness. lie digested alcohol on this extract, 
 and evaporated the alcoholic extract to dry- 
 ness. lie then digested this mass in ether, 
 and evaporated the etherial solution ; when 
 lie obtained a syrupy mass of a light yel- 
 
 ACi 
 
 low colour, which was again dissolved in 
 alcohol. On adding water to this solution a 
 little resin fell. A peculiar acid united to 
 potash and lime remains in the solution, 
 which is obtained free, by forming with ace- 
 tate of lead an insoluble laccate, and decom- 
 posing this with the equivalent quantity of 
 sulphuric acid. Laccic acid crystallizes ; it 
 has a wine yellow colour, a sour taste, and is 
 soluble, as we have seen, in water, alcohol, 
 and ether. It precipitates lead and mercury 
 white ; but it does not affect lime, barytes, 
 or silver, in their solutions. It throws down 
 the salts of iron white. With lime, soda, and 
 potash, it forms deliquescent salts, soluble in 
 alcohol.* 
 
 Acid ( Lactic). By evaporating sour whey 
 to one-eighth, filtering, precipitating with 
 lime-water, and separating the lime by oxalic 
 acid, Scheele obtained an aqueous solution 
 of what he supposed to be a peculiar acid, 
 which has accordingly been termed the lactic. 
 To procure it separate, he evaporated the so- 
 lution to the consistence of honey, poured 
 on it alcohol, filtered this solution, and eva- 
 porated the alcohol. The residuum w r as an 
 acid of a yellow colour, incapable of being 
 crystallized, attracting the humidity of the 
 air, and forming deliquescent salts with the 
 earths and alkalis. 
 
 Bouillon Lagrange since examined it more 
 narrowly; and from a series of experiments 
 concluded, that it consists of acetic acid, mu- 
 riate of potash, a small portion of iron pro- 
 bably dissolved in the acetic acid, and an 
 animal matter. 
 
 * This judgment of M. Lagrange was after- 
 wards supported by the opinions of MM. 
 Fourcroy and Vauquelin. But since then 
 Berzelius has investigated its nature very 
 fully, and has obtained, by means of a long 
 and often repeated series of different expe- 
 riments, a complete conviction that Scheele 
 was in the right, and that the lactic acid is 
 a peculiar acid, very distinct from all others. 
 The extract which is obtained when dried 
 whey is digested with alcohol, contains un- 
 combined lactic acid, lactate of potash, mu- 
 riate of potash, and a proper animal matter. 
 As the elimination of the acid affords an in- 
 structive example of chemical research, we 
 shall present it at some detail, from the 2d 
 volume of Berzelius’s Animal Chemistry. 
 
 He mixed the above alcoholic solution with 
 another portion of alcohol, to which jj of 
 concentrated sulphuric acid had been added, 
 and continued to add fresh portions of this 
 mixture as long as any saline precipitate was 
 formed, and until the fluid had acquired a de- 
 cidedly acid taste. Some sulphate of potash 
 was precipitated, and there remained in the 
 alcohol, muriatic acid, lactic acid, sulphuric 
 acid, and a minute portion of phosphoric acid, 
 detached from some bone earth which had 
 been held in solution. The acid liquor was 
 
ACI 
 
 ACI 
 
 filtered, and afterwards digested with carbo- 
 nate of lead, which with the lactic acid af- 
 fords a salt soluble in alcohol. As soon as 
 the mixture had acquired a sweetish taste, 
 the three mineral acids had fallen down in 
 combination with the lead, and the lactic 
 acid remained behind, imperfectly saturated 
 by a portion of it, from which it was detach- 
 ed by means of sulphuretted hydrogen, and 
 then evaporated to the consistence of a thick 
 varnish, of a dark- brown colour, and sharp 
 acid taste, but altogether without smell. 
 
 In order to free it from the animal matter 
 which might remain combined with it, he 
 boiled it with a mixture of a large quantity 
 of fresh lime and water, so that the animal 
 substances were precipitated and destroyed 
 by the lime. The lime became yellow brown, 
 and the solution almost colourless, while the 
 mass emitted a smell of soap lees, which 
 disappeared as the boiling was continued. 
 The fluid thus obtained was filtered and 
 evaporated, until a great part of the super- 
 fluous lime held in solution was precipitated. 
 A small portion of it was then decomposed 
 by oxalic acid, and carbonate of silver was dis- 
 solved in the uncombined lactic acid, until 
 it was fully saturated. With the assistance 
 of the lactate of silver thus obtained, a fur- 
 ther quantity of muriatic acid was separated 
 from the lactate of lime, which was then de- 
 composed by pure oxalic acid, free from nitric 
 acid, taking care to leave it in such a state 
 that neither the oxalic acid nor lime water 
 afforded a precipitate. It was then evapo- 
 rated to dryness, and dissolved again in al- 
 cohol, a small portion of oxalate of lime, be- 
 fore retained in union with the acid, now 
 remaining undissolved. The alcohol was 
 evaporated until the mass was no longer fluid 
 while warm ; it became a brown clear trans- 
 parent acid, which was the lactic acid, free 
 from all substances that we have hitherto 
 had reason to think likely to contaminate it. 
 
 The lactic acid, thus purified, has a brown 
 yellow colour, and a sharp sour taste, which 
 is much weakened by diluting it with water. 
 It is without smell in the cold, but emits, 
 when heated, a sharp sour smell, not unlike 
 that of sublimed oxalic acid. It cannot be 
 made to crystallize, and does not exhibit the 
 slightest appearance of a saline substance, 
 but dries into a thick and smooth varnish, 
 which slowly attracts moisture from the air. 
 It is very easily soluble in alcohol. Heated in 
 a gold spoon over the flame of a candle, it first 
 boils, and then its pungent acid smell be- 
 comes very manifest, but extremely distinct 
 from that of the acetic acid ; afterwards it is 
 charred, and has an empyreumatic, but by 
 no means an animal smell. A porous char- 
 coal is left behind, which does not readily 
 burn to ashes. \\ hen distilled, it gives an em- 
 pyreumatic oil, water, empyreumatic vinegar, 
 carbonic acid, and inflammable gases. With 
 
 alkalis, earths, and metallic oxides, it affords 
 peculiar salts : and these are distinguished 
 by being soluble in alcohol, and in general 
 by not having the least disposition to crystal- 
 lize, but drying into a mass like gum, which 
 slowly becomes moist in the air. 
 
 Lactate of jiotash is obtained, when the 
 lactate of lime, purified as has been men- 
 tioned, is mixed warm with a warm solution 
 of carbonate of potash. It forms, in drying, 
 a gummy, light yellow brown, transparent 
 mass, which cannot easily be made hard. If 
 it is mixed with concentrated sulphuric acid, 
 no smell of acetic acid is perceived ; but if 
 the mixture is heated, it acquires a disagree- 
 able pungent smell, which is observable in 
 all animal substances mixed with the sul- 
 phuric acid. The extract which is obtained 
 directly from milk, contains this salt ; but 
 this affords, when mixed with sulphuric acid, 
 a sharp acid smell, not unlike that of the 
 acetic acid. This, however, depends not on 
 acetic but on muriatic acid, which in its 
 concentrated state introduces this modifica- 
 tion into the smell of almost all organic bo- 
 dies. The pure lactate of potash is easily 
 soluble in alcohol ; that which contains an 
 excess of potash, or is still contaminated with 
 the animal matter soluble in alcohol, which 
 is destroyed by the treatment with lime, is 
 slowly soluble, and requires about 14 parts 
 of warm alcohol for its solution. It is dis- 
 solved in boiling alcohol more abundantly 
 than in cold, and separates from it, while it 
 is cooling, in the form of hard drops. 
 
 The lactate of soda resembles that of pot- 
 ash, and can only be distinguished from it by 
 analysis. 
 
 Lactate of ammonia. If concentrated lac- 
 tic acid is saturated with caustic ammonia in 
 excess, the mixture acquires a strong volatile 
 smell, not unlike that of the acetate or for- 
 miate of ammonia, which, however, soon 
 ceases. The salt which is left has sometimes 
 a slight tendency to shoot into crystals. It 
 affords a gummy mass, which in the air ac- 
 quires an excess of acidity. When heated, a 
 great part of the alkali is expelled, and a 
 very acid salt remains, which deliquesces in 
 the air. 
 
 The lactate of barytes may be obtained in 
 the same way as that of lime ; but it then 
 contains an excess of the base. When eva- 
 porated, it affords a gummy mass, soluble in 
 alcohol. A portion remains undissolved, 
 which is a sub-salt, is doughy, and has a 
 browner colour. That which is dissolved in 
 the alcohol affords by evaporation an almost 
 colourless gummy mass, which hardens into 
 a stiff but not a brittle varnish. It does 
 not show the least tendency to crystallize. 
 
 1 he salt, which is less soluble in alcohol, may 
 be further purified from the animal matter 
 adhering to it, by adding to it more barytes, 
 and then becomes more soluble. 
 
 13 
 
ACI 
 
 ACI 
 
 riie lactate of lime is obtained in the man- 
 ner above described. It affords a gummy 
 mass, which is also divided by alcohol into 
 two portions. Ihe larger portion is soluble, 
 and gives a shining varnish inclining to a 
 light yellow colour, which, when slow ly dried, 
 cracks all over, and becomes opaque. This is 
 pure lactate of lime. That which is insolu- 
 ble in alcohol is a powder, with excess of‘ the 
 base ; received on a filter, it becomes smooth 
 m the air like gum, or like malate of lime. 
 By boiling with more lime, and by the pre- 
 cipitation of the superfluous base upon ex- 
 posure to the air, it becomes pure and solu- 
 ble in alcohol. 
 
 Lactate of * magnesia , evaporated to the 
 consistence of a thin syrup, and left in a 
 warm place, shoots into small granular cry- 
 stals. When hastily evaporated to dryness, 
 it affords a gummy mass. With regard to 
 alcohol, its properties resemble those of the 
 two preceding salts. 
 
 Am mo niaco- magnesian lactate is obtained 
 by mixing the preceding salt with caustic 
 ammonia, as long as any precipitation conti- 
 nues. By spontaneous evaporation this salt 
 shoots into needle-shaped prisms, which are 
 little coloured, and do not change in the 
 air. Berzelius has once seen these crystals 
 form in the alcoholic extract of milk boiled 
 to dryness ; but this is by no means a com- 
 mon occurrence. 
 
 The lactate of silver is procured by dissolv- 
 ing the carbonate in the lactic acid. The so- 
 lution is of a light yellow, somewhat inclin- 
 ing to green, and has an unpleasant taste of 
 verdigris. When evaporated in a flat vessel, 
 it dries into a very transparent greenish yel- 
 low varnish, which has externally an unusual 
 splendour like that of a looking-glass. If 
 the evaporation is conducted in a deeper ves- 
 sel, and with a stronger heat, a part of the 
 salt is decomposed, and remains brown from 
 the reduction of the silver. If this salt is 
 dissolved in water, no inconsiderable portion 
 of the silver is reduced and deposited, even 
 when the salt has been transparent ; and the 
 concentrated solution has a fine greenish yel- 
 low colour, which by dilution becomes yel- 
 low. If we dissolve the oxide of silver in an 
 impure acid, the salt becomes brown, and 
 more silver is revived during the evapora- 
 tion. 
 
 The lactate of the protoxide of mercury is 
 obtained when the lactic acid is saturated 
 with black oxidated mercury. It has alight 
 yellow colour, which disappears by means of 
 repeated solution and evaporation. The salt 
 exhibits acid properties, deliquesces in the air, 
 and is partially dissolved in alcohol, but is 
 at the same time decomposed, and depo- 
 sits carbonate of mercury, while the mixture 
 acquires a slight smell of ether. The lactic 
 acid dissolves also the red oxide of mercury, 
 and gives with it a red gummy deliquescent 
 
 salt. If it is left exposed to a warm and 
 moist atmosphere, it deposits, after the ex- 
 piration of some weeks, a light semi- crys- 
 talline powder, which he has not examined, 
 but which probably must be acetate of mer- 
 cury. 
 
 The lactate of lead may be obtained in 
 several different degrees of saturation. If 
 the lactic acid is digested with the carbonate 
 of lead, it becomes browner than before, but 
 cannot be fully saturated with the oxide ; 
 and we obtain an acid salt, which does not 
 crystallize, but dries into a syrup- like browm 
 mass, with a sweet austere taste. When a 
 solution of lactic acid in alcohol is digested 
 with finely powdered litharge, until the so- 
 lution becomes sweet, and is then slowly 
 evaporated to the consistence of honey, the 
 neutral lactate of lead crystallizes in small 
 grayish grains, which may be rinsed with al- 
 cohol, to wash off' the viscid mass that ad- 
 heres to them, and wall then appear as a gray 
 granular salt, which when dry is light and 
 silvery. 
 
 This silver grained salt is not changed 
 in the air ; treated w ith sulphuretted hydro- 
 gen it affords pure lactic acid. If the lac- 
 tic acid is digested with a greater portion 
 of levigated litharge than is required for its 
 saturation, the fluid acquires first a browner 
 colour, and as the digestion is continued the 
 colour becomes more and more pale, and the 
 oxide swells into a bulky powder, of a colour 
 somewhat lighter than before. If the fluid 
 is evaporated, and water is then poured on 
 the dry mass, a very small portion of it only 
 is dissolved ; the solution is not coloured, 
 and when it is exposed to the air, a pellicle 
 of carbonate of lead is separated from it. If 
 the dried salt of lead be boiled with water, 
 and the solution be filtered while hot, a great 
 part of that which had been dissolved wall be 
 precipitated while it cools, in the form of a 
 white, or light yellow powder, which is a 
 sublactate of lead. This salt is of a light 
 flame colour ; when dried, it remains mealy, 
 and soft to the touch, and it is decomposed 
 by the weakest acids, while the acid salt is 
 dissolved in water, exhibiting a sweet taste 
 and a brown colour. When moistened with 
 water, it undergoes this change from the 
 operation of the carbonic acid diff used in the 
 air. If this salt is warmed and then set on 
 fire at one point, it burns like tinder, and 
 leaves the lead in great measure reduced. A 
 hundred parts of this salt, dissolved in nitric 
 acid, and precipitated with carbonate of 
 potash, gave exactly 100 parts of carbonate 
 of lead ; consequently its component parts, de- 
 termined from those of the carbonate, must be 
 83 of the oxide of lead, and 1 7 of the lactic 
 acid. At the same time we cannot wholly 
 depend on this proportion, and it certainly 
 makes the quantity of lead somewhat too 
 great. The relation of the lactic acid to lead 
 
A Cl 
 
 ACI 
 
 affords one of the best methods of recognizing 
 it, and Berzelius always principally employ- 
 ed it in extracting this acid from animal 
 fluids ; it gives the clearest distinction be- 
 tween the lactic acid and the acetic. 
 
 The lactate of iron is of a red brown co- 
 lour, does not crystallize, and is not soluble 
 in alcohol. The lactate of zinc crystallizes. 
 Both these metals are dissolved by the lactic 
 acid, with an extrication of hydrogen gas. 
 The lactate of copper , according to its dif- 
 ferent degrees of saturation, varies from blue 
 to green and dark blue. It does not crys- 
 tallize. 
 
 It is only necessary to compare the de- 
 scriptions of these salts with what we know 
 of the salts which are formed with the same 
 bases by other acids, for example, the acetic, 
 the malic, and others, in order to be com- 
 pletely convinced that the lactic acid must be 
 a peculiar acid, perfectly distinct from all 
 others. Its prime equivalent may be called 
 5.8. 
 
 The nanceic acid of Braconnot resembles 
 the lactic in many respects. * 
 
 * Acid (Lampic). Sir H. Davy, during his 
 admirable researches on the nature and pro- 
 perties of flame, announced the singular fact, 
 that combustible bodies might be made to 
 combine rapidly with oxygen, at temperatures 
 below what were necessary to their visible 
 inflammation. Among the phenomena result- 
 ing from these new combinations, he remark- 
 ed the production of a peculiar acid and 
 pungent vapour from the slow combustion of 
 ether ; and from its obvious qualities he was 
 led to suspect, that it might be a product yet 
 new to the chemical catalogue. Mr Faraday, 
 in the 3d volume of the Journal of Science 
 and the Arts, has given some account of the 
 properties of this new acid ; but from the 
 very small quantities in which he was able to 
 collect it, was prevented from performing 
 any decisive experiments upon it. 
 
 In the 6th volume of the same Journal, 
 we have a pretty copious investigation of the 
 properties and compounds of this new acid, 
 by Mr Daniell. From the slow combustion 
 of ether during six weeks, by means of a coil 
 of platina wire sitting on the cotton wick of 
 the lamp, (See Flame), he condensed with 
 the head of an alembic, whose beak was in- 
 serted in a receiver, a pint and a half of the 
 lampic acid liquor. 
 
 When first collected it is a colourless fluid 
 of an intensely sour taste, and pungent 
 odour. Its vapour, when heated, is extremely 
 irritating and disagreeable, and when receiv- 
 ed into the lungs produces an oppression at 
 the chest very much resembling the effect of 
 chlorine. Its specific gravity varies accord- 
 ing to the care with which it has been pre- 
 pared, from less than 1.000 to 1.008. It 
 may be purified by careful evaporation ; and 
 it is worthy of remark, that the vapour which 
 
 rises from it is that of alcohol, with which 
 it is slightly contaminated, and not of ether. 
 Thus rectified, its specific gravity is 1.015. 
 It reddens vegetable blues, and decomposes 
 all the earthy and alkaline carbonates, form- 
 ing neutral salts with their bases, which are 
 more or less deliquescent. Lampate of soda 
 is a very deliquescent salt, of a not unpleasant 
 saline taste. It is decomposed by heat. It 
 consists of 62. 1 acid and 37.9 soda. Hence 
 its prime equivalent comes out 6.47. Lam- 
 pate of potash is not quite so deliquescent. 
 Lampate of ammonia evaporates at a temper- 
 ature below 212°. It is a brown salt. Lam- 
 pate of barytes crystallizes in colourless 
 transparent needles. Its composition is 39.5 
 acid and 60.5 base ; and hence the prime is 
 6.365, barytes being reckoned 9.75, with Dr 
 Wollaston. Lampate of lime is deliquescent, 
 and has a caustic bitter taste. Lampate of 
 magnesia has a sweet, astringent taste, like 
 sulphate of iron. All these salts burn with 
 flame. Lampic acid reduces gold from the 
 muriate instantly ; and the lampates of potash 
 and ammonia produce the same effect more 
 slowly. A mixture of these two lampates, 
 throws down metallic platinum from its so- 
 lution. Nitrate of silver also gives a metallic 
 precipitate ; but what is singular, the oxide 
 of silver is soluble in lampic acid, but at a 
 boiling heat falls down in the metallic state. 
 A hot solution of nitrated protoxide of mer- 
 cury exhibits a very beautiful phenomenon, 
 when mixed with the acid. A shower of 
 mercurial globules falls down through the 
 liquid. Red oxide forms with lampic acid 
 a bulky white salt, of sparing solubility, from 
 which, after a few days, metallic mercury 
 separates. Lampate of copper affords by 
 evaporation under an exhausted receiver, 
 blue rhomboidal crystals. When the solu- 
 tion is boiled, metallic copper falls. Lampate 
 of lead is a white, sweetish, and easily crys- 
 tallized salt. 
 
 By analysis of the lampate of barytes in 
 M M. Gay Lussac and Thenard’s apparatus, 
 (See Vegetable Analysis), Mr Daniell 
 infers the composition of the acid to be 40.7 -f- 
 carbon — j— 7. 7 — hydrogen 51.6 of oxy- 
 gen and hydrogen, in their aqueous ratio 
 = 100. These numbers correspond, he 
 says, with what we may suppose to result 
 from 1 atom of carbon, 1 of hydrogen, and 
 1 of water, or its elements. The excess of 
 hydrogen explains, he imagines, the property 
 which the acid possesses of reviving the 
 metals, whence it may be usefully applied in 
 the arts, to plate delicate works with gold and 
 platinum. 
 
 The weight of its equivalent, and some of 
 the properties of the salts, might lead to the 
 opinion of the lampic acid of Mr Daniell 
 being merely the acetic, combined with some 
 etherous matter. This conjecture must be 
 left for future verification.* 
 
ACI 
 
 ACI 
 
 Acid (Lithic). This was discovered about 
 the year 1776 by Scheele, in analyzing 
 human calculi, ot many ot* which it consti- 
 tutes the greater part, and of some, parti- 
 cularly that which resembles wood in ap- 
 pearance, it forms almost the whole. It is 
 likewise present in human urine, and in that 
 of the camel ; and Dr Pearson found it in 
 those arthritic concretions commonly called 
 chalkstones, which Mr Tennant has since 
 confirmed. It is often called uric acid. 
 
 The following are the results of Scheele’s 
 experiments on calculi, which were found to 
 consist almost wholly of this acid : 
 
 1. Dilute sulphuric acid produced no ef- 
 fect on the calculus, but the concentrated 
 dissolved it ; and the solution distilled to dry- 
 ness left a black coal, giving off sulphurous 
 acid fumes. 2. The muriatic acid, either di- 
 luted or concentrated, had no effect on it 
 even with ebullition. 5. Dilute nitric acid 
 attacked it cold ; and with the assistance of 
 heat produced an effervescence and red va- 
 pour, carbonic acid was evolved, and the 
 calculus was entirely dissolved. The solu- 
 tion was acid, even when saturated with the 
 calculus, and gave a beautiful red colour to 
 the skin in half an hour after it was applied ; 
 when evaporated, it became of a blood red, but 
 the colour was destroyed by adding a drop of 
 acid : it did not precipitate muriate of barytes, 
 or metallic solutions, even with the addition of 
 an alkali; alkalis rendered it more yellow, and, 
 if superabundant, changed it by a strong digest- 
 ing heat to a rose colour; and this mixture im- 
 parts a similar colour to the skin, and is capable 
 of precipitating sulphate of iron black, sulphate 
 of copper green, nitrate of silver gray, super- 
 oxygenated muriate of mercury, and solutions 
 of lead and zinc, white. Lime-water pro- 
 duced in the nitric solution a while preci- 
 pitate, which dissolved in the nitric and mu- 
 riatic acids without effervescence, and with- 
 out destroying their acidity. Oxalic acid 
 did not precipitate it. 4. Carbonate of pot- 
 ash did not dissolve it, either cold or hot, 
 but a solution of perfectly pure potash dis- 
 solved it even cold. The solution was yel- 
 low ; sweetish to the taste ; precipitated by 
 all the acids, even the carbonic ; did not 
 render lime-water turbid ; decomposed and 
 precipitated solution of iron brown, of copper 
 gray, of silver black, of zinc, mercury, and 
 lead, white ; and exhaled a smell of ammonia. 
 5. About 200 parts of lime-water dissolved 
 the calculus by digestion, and lost its acrid 
 taste. The solution was partly precipitated 
 by acids. 6. Pure water dissolved it entirely, 
 but it was necessary to boil for some time 
 360 parts with one of the calculus in powder. 
 This solution reddened tincture of litmus, 
 did not render lime-water turbid, and on 
 cooling deposited in small crystals almost the 
 whole of what it had taken up. 7. Seventy- 
 two grains distilled in a small glass retort 
 
 over an open fire, and gradually brought to 
 a red heat, produced water of ammonia mix- 
 ed with a little animal oil, and a brown sub- 
 limate weighing 28 grains, and 12 grains of 
 coal remained, which preserved its black 
 colour on red hot iron in the open air. The 
 brown sublimate was rendered white by a 
 second sublimation ; was destitute of smell, 
 even when moistened by an alkali ; was acid 
 to the taste ; dissolved in boiling water, and 
 also in alcohol, but in less quantity ; did 
 not precipitate lime-water; and appeared to 
 resemble succinic acid. 
 
 Fourcroy has found, that this acid is al- 
 most entirely soluble in 2000 times its 
 weight of cold water, when the powder is 
 repeatedly treated with it. From his experi- 
 ments he infers, that it contains azote, with a 
 considerable portion of carbon, and but little 
 hydrogen, and little oxygen. 
 
 Of its combinations with the bases we 
 know but little. The lithate of lime is more 
 soluble than the acid itself ; but on exposure 
 to the air it is soon decomposed, the carbonic 
 acid in the atmosphere combining wfith the 
 lime, and precipitating both the lithic acid 
 and new formed carbonate of lime separate 
 from each other. The lithate of soda appears 
 from the analysis of Mr Tennant to consti- 
 tute the chief part of the concretions formed 
 in the joints of gouty persons. The lithate 
 of potash is obtained by digesting calculi in 
 caustic lixivium ; and Fourcroy recommends 
 the precipitation of the lithic acid from this 
 solution by acetic acid, as a good process 
 for obtaining the acid pure in small, white, 
 shining, and almost pulverulent needles. 
 
 * Much additional information has been 
 obtained within these few years on the na- 
 ture and habitudes of the lithic acid. Dr 
 Henry wrote a medical thesis, and after- 
 wards published a paper, on the subject, in 
 the second volume of the new series of the 
 Manchester Memoirs, both of which con- 
 tain many important facts. He procured 
 the acid in the manner above prescribed by 
 Fourcroy. It has the form of white shining 
 plates, which are denser than water. Has 
 no taste nor smell. It dissolves in about 
 1400 parts of boiling water. It reddens the 
 infusion of litmus. When dissolved in ni- 
 tric acid, and evaporated to dryness, it leaves 
 a pink sediment. The dry acid is not acted 
 on nor dissolved by the alkaline carbonates, 
 or sub- carbonates. It decomposes soap w hen 
 assisted by heat ; as it does also the alkaline 
 sulphurets, and hydrosulphurets. No acid 
 acts on it, except those that occasion its de- 
 composition. It dissolves in hot solutions 
 of potash and soda, and likewise in ammo- 
 nia, but less readily. The lithates may be 
 formed, either by mutually saturating the 
 tw r o constituents, or we may dissolve the 
 acid in an excess of base, and we may then 
 precipitate by carbonate of ammonia. The 
 
ACI 
 
 ACI 
 
 lithates are all tasteless, and resemble in ap- 
 pearance lithic acid itself. They are not al- 
 tered by exposure to the atmosphere. They 
 are very sparingly soluble in water. r Ihey 
 are decomposed by a red heat, which de- 
 stroys the acid. The lithic acid is precipitat- 
 ed from these salts, by all the acids except 
 the prussic and carbonic. They are decom- 
 posed by the nitrates, muriates, and acetates 
 of barytes, strontites, lime, magnesia, and 
 alumina. They are precipitated by all the 
 metallic solutions except that of gold. W hen 
 lithic acid is exposed to heat, the products are 
 carburetted hydrogen, and carbonic acid, 
 prussic acid, carbonate of ammonia, a subli- 
 mate, consisting of ammonia combined with 
 a peculiar acid, which has the following pro- 
 perties : — 
 
 Its colour is yellow, and it has a cooling 
 bitter taste. It dissolves readily in water, 
 and in alkaline solutions, from which it is 
 not precipitated by acids. It dissolves also 
 sparingly in alcohol. It is volatile, and when 
 sublimed a second time, becomes much 
 whiter. The watery solution reddens vege- 
 table blues, but a very small quantity of am- 
 monia destroys this property. It does not 
 Cause effervescence with alkaline carbonates. 
 By evaporation it yields permanent crystals, 
 but ill defined, from adhering animal matter. 
 These redden vegetable blues. Potash when 
 added to these crystals, disengages ammonia. 
 When dissolved in nitric acid, they do not 
 leave a red stain, as happens with uric acid ; 
 nor does their solution in water decompose 
 the earthy salts, as happens with alkaline 
 lithates (or urates). Neither has it any ac- 
 tion on the salts of copper, iron, gold, plati- 
 num, tin, or mercury. With nitrates of sil- 
 ver, and mercury, and acetate of lead, it 
 forms a white precipitate, soluble in an ex- 
 cess of nitric acid. Muriatic acid occasions 
 no precipitate in the solution of these crystals 
 in water. These properties shew, that the 
 acid of the sublimate is different from the uric, 
 and from every other known acid. Dr Aus- 
 tin found, that by repeated distillations, lithic 
 acid was resolved into ammonia, nitrogen, 
 and prussic acid. See Acid (Pyrolithic. ) 
 When lithic acid is projected into a flask 
 with chlorine, there is formed, in a little 
 time, muriate of ammonia, oxalate of am- 
 monia, carbonic acid, muriatic acid, and 
 malic acid ; the same results are obtained 
 by passing chlorine through water, holding 
 this acid in suspension. 
 
 M. Gay Lussac mixed lithic acid with 20 
 times its weight of oxide of copper, put the 
 it mixture into a glass tube, and covered it with 
 a quantity of copper filings. The copper 
 filings being first heated to a dull red heat, 
 
 1 4 w'as applied to the mixture. The gas which 
 came over, was composed of 0.69 carbonic 
 m acid, and 0.91 nitrogen. lie conceives, that 
 the bulk of the carbonic acid would have 
 
 been exactly double that of the nitrogen, had 
 it not been for the formation of a little car- 
 bonate of ammonia. Hence, uric acid con- 
 tains two prime equivalents of carbon, and 
 one of nitrogen. This is the same propor- 
 tion as exists in cyanogen. Probably, a 
 prime equivalent of oxygen is present. Dr 
 Prout, in the eighth vol. of the Med. Chir. 
 Trans, describes the result of an analysis of 
 lithic acid, effected also by ignited oxide of 
 copper, but so conducted as to determine 
 the product of oxygen and hydrogen. Four 
 grains of lithic acid yielded, w'ater 1 .05, car- 
 bonic acid 11.0 c. inches, nitrogen 5.5 do. 
 Hence, it consisted of 
 Hydrogen 2.857 or 1 prime = 0.125 
 Carbon 34.286 2 = 1.500 
 
 Oxygen 22.857 1 = 1.000 
 
 Nitrogen 40.00 1 = 1.750 
 
 100.000 4.375 
 
 M. Berard has published an analysis of 
 lithic acid since Dr Prout, in which he also 
 employed oxide of copper. 
 
 The following are the results : — 
 
 Carbon 33.61 f 1 Carbon 
 
 Oxygen 1 8.89 wFich ap- J 1 Oxygen 
 
 Hydrogen 8. 34 proach to y 4 Hydrogen 
 
 Nitrogen 39.16 (. 1 Nitrogen 
 
 100.00 
 
 Here we find the nitrogen and carbon 
 nearly in the same quantity as by Dr Prout, 
 but there is much more hydrogen and less 
 oxygen. By urate of barytes, we have the 
 prime equivalent of uric acid equal to 15.67 ; 
 and by urate of potash it appears to be 
 14.0. It is needless to try to accommodate 
 an arrangement of prime equivalents to these 
 discrepancies. The lowest number would 
 require, on the Daltonian plan, an associa- 
 tion of more than twenty atoms, the group- 
 ing of which is rather a sport of fancy, than 
 an exercise of reason. For what benefit 
 could accrue to chemical science, by stating, 
 that if we consider the atom of lithic acid 
 to be 16.75, then it would probably consist 
 
 of 7 atoms Carbon = 
 
 5.25 
 
 31.4 
 
 3 
 
 Oxygen = 
 
 3.00 
 
 17.90 
 
 12 
 
 Hydrogen = 
 
 1.500 
 
 8.90 
 
 4 
 
 Nitrogen = 
 
 7.00 
 
 41.80 
 
 26 
 
 
 16.75 
 
 100.0* 
 
 * Acid (Malic). The acid of apples ; the 
 same with that which is extracted from the 
 fruit of the mountain ash. See Acid (Sor- 
 bic.)* 
 
 * Acid (Margaric). When w e immerse 
 soap made of pork-grease and potash, in a 
 large quantity of water, one part is dissolved, 
 while another part is precipitated, in the 
 form of several brilliant pellets. These are 
 separated, dried, washed in a large quantity 
 of water, and then dried on a filter. They 
 are now dissolved in boiling alcohol, sp. gr. 
 
ACI 
 
 ACI 
 
 0.820, from which, as it cools, the pearly sub- 
 stance lalls down pure. On acting on this 
 with dilute muriatic acid, a substance of a 
 peculiar kind, which M. Chevreul, the dis- 
 coverer, calls margarine, or margaric acid, 
 is separated. It must be well washed with 
 water dissolved in boiling alcohol, from 
 which it is recovered in the same crystalline 
 pearly form, when the solution cools. 
 
 Margaric acid is pearly white, and taste- 
 less. Its smell is feeble, and a little similar 
 to that of melted wax. Its specific gravity is 
 inferior to water. It melts at 134° F. into a 
 very limpid, colourless liquid, which crystal- 
 lizes on cooling, into brilliant needles of the 
 finest white. It is insoluble in w r ater, but 
 very soluble in alcohol, sp. gr. 0.800. Cold 
 margaric acid has no action on the colour of 
 litmus; but when heated so as to soften 
 without melting, the blue was reddened. 
 It combines with the salifiable bases, and 
 forms neutral compounds. 100 parts of it 
 unite to a quantity of base containing three 
 parts of oxygen, supposing that 100 of pot- 
 ash contain 17 of oxygen. Two orders of 
 margarates are formed, the margarates, and 
 the supermargarates, the former being con- 
 verted into the latter, by pouring a large 
 quantity of water on them. Other fats be- 
 sides that of the hog yield this substance. 
 
 
 Acid. 
 
 Base. 
 
 Margarate of potash consists of 
 
 100 
 
 17.77 
 
 Supermargarate 
 
 100 
 
 8.88 
 
 Margarate of soda 
 
 100 
 
 12.72 
 
 Barytes - 
 
 100 
 
 28.93 
 
 Strontites - 
 
 100 
 
 20 . 25 
 
 Lime - 
 
 100 
 
 1 1.06 
 Potash 
 
 Supermargarate of Human fat 
 
 100 
 
 8.85 
 
 Sheep fat 
 
 100 
 
 8.68 
 
 Ox fat 
 
 100 
 
 8.78 
 
 Jaguar fat 
 
 100 
 
 8.60 
 
 Goose fat 
 
 100 
 
 8.77 
 
 If we compare the above numbers, we 
 shall find 35 to be the prime equivalent of 
 margaric acid. 
 
 That of man is obtained under three dif- 
 ferent forms. 1 st, In very fine long needles, 
 disposed in flat stars. 2 cl, In very fine and 
 very short needles, forming waved figures, 
 like those of the margaric acid of carcasses. 
 3d, In very large brilliant crystals disposed 
 in stars, similar to the margaric acid of the 
 hog. The margaric acids of man and the 
 hog resemble each other ; as do those of the 
 ox and the sheep ; and of the goose and the 
 jaguar. The compounds with the bases, are 
 real soaps. The solution of alcohol affords 
 the transparent soap of this country. — An- 
 nalcs de Chimie , several volumes.* 
 
 * Acid (Meconic). This acid is a consti- 
 tuent of opium. It was discovered by M. 
 Sertuerner, who procured it in the following 
 way : After precipitating the morphia , from 
 a solution of opium, by ammonia, he added 
 
 to the residual fluid a solution of the muri- 
 ate of barytes. A precipitate is in this way 
 formed, which is supposed to be a quadruple 
 compound, of barytes, morphia, extract, and 
 the meconic acid. The extract is removed 
 by alcohol, and the barytes by sulphuric 
 acid ; when the meconic acid is left, merely 
 in combination with a portion of the mor- 
 phia ; and from this it is purified by succes- 
 sive solutions and evaporations. The acid, 
 w'hen sublimed, forms long colourless needles ; 
 it has a strong affinity for the oxide of iron, 
 so as to take it from the muriatic solution, 
 and form with it a cherry-red precipitate. 
 It forms a crystallizable salt with lime, 
 which is not decomposed by sulphuric acid ; 
 and what is curious, it seems to possess no 
 particular power over the human body, when 
 received into the stomach. The essential 
 salt of opium, obtained in M. Derosne’s 
 original experiments, was probably the me- 
 coniate of morphia. 
 
 Mr Hobiquet has made a useful modifica- 
 tion of the process for extracting meconic 
 acid. He treats the opium with magnesia, 
 to separate the morphia, while meconiate of 
 magnesia is also formed. The magnesia is 
 removed by adding muriate of barytes, and 
 the barytes is afterwards separated by dilute 
 sulphuric acid. A larger proportion of me- 
 conic acid is thus obtained. 
 
 Mr Robiquet denies that meconic acid 
 precipitates iron from the muriate; but, ac- 
 cording to M. Vogel, its pow r er of reddening 
 solutions of iron is so great, as to render it a 
 more delicate test of this metal, than even 
 the prussiate of potash. 
 
 To obtain pure meconic acid from the 
 meconiate of barytes, M. Choulant triturated 
 it in a mortar, with its own weight of glassy 
 boracic acid. This mixture being put into a 
 small glass flask, which was surrounded w ith 
 sand in a sand pot, in the usual manner, and 
 the red heat being gradually raised, the me- 
 conic acid sublimed, in the state of fine w hite 
 scales or plates. It has a strong sour taste, 
 which leaves behind it an impression of bit- 
 terness. It dissolves readily in water, alco- 
 hol, and ether. It reddens the greater num- 
 ber of vegetable blues, and changes the solu- 
 tions of iron to a cherry- red colour. When 
 these solutions are heated, the iron is preci- 
 pitated in the state of protoxide. 
 
 The meconiates examined by Choulant, 
 are the following : — 
 
 1st, Meconiate of potash. It crystallizes 
 in four sided tables, is soluble in twice its 
 weight of water, and is composed of 
 
 Meconic acid 2 7 2.7 
 
 Potash 60 6.0 
 
 Water 1 3 
 
 100 
 
 It is destroyed by heat. 
 
 ~ * f 
 2 d, Meconiate of soda. It crystallizes in 
 
AC1 
 
 ACI 
 
 soft prisms, is soluble in five times its weight 
 of water, and seems to effloresce. It is de- 
 stroyed by heat. It consists ot 
 
 Acid 32 3.2 
 
 Soda 40 4.0 
 
 Water 28 
 
 100 
 
 3d, Meconiate of ammonia. It crystal- 
 lizes in star-form needles, which, when su- 
 blimed, lose their water of crystallization, 
 and assume the shape of scales. The crys- 
 tals are soluble in l\ their weight of water, 
 
 and are composed of 
 
 Acid 40 2.03 
 
 Ammonia 42 2.13 
 
 Water 18 
 
 100 
 
 If two parts of sal ammoniac be triturated 
 with 3 parts of meconiate of barytes, and heat 
 be applied to the mixture, meconiate of am- 
 monia sublimes, and muriate of barytes re- 
 mains. 
 
 4 th, Meconiate of lime. It crystallizes in 
 prisms, and is soluble in eight times its 
 weight of water. It consists of 
 
 Acid 34 2.882 
 
 Lime 42 3.560 
 
 Water 24 
 
 100 
 
 As the potash and lime compounds give 
 nearly the same acid ratio, we may take 
 their mean of it, as the true prime ==2.8.* 
 
 * Acin (Melasic). The acid present in 
 melasses, which has been thought a peculiar 
 acid by some, by others, the acetic.* 
 
 Acid (Mellitic). M. Klaproth discovered 
 in the melilite, or honey-stone, what he con- 
 ceives to be a peculiar acid of the vegetable 
 kind, combined with alumina. This acid is 
 easily obtained by reducing the stone to pow- 
 der, and boiling it in about 70 times its 
 weight of water ; when the acid will dis- 
 solve, and may be separated from the alumi- 
 na by filtration. By evaporating the solu- 
 tion, it may be obtained in the form of 
 crystals. The following are its characters: — 
 
 It crystallizes in fine needles or globules 
 by the union of these, or small prisms. Its 
 taste is at first a sweetish sour, which leaves 
 a bitterness behind. On a plate of hot me- 
 tal it is -readily decomposed, and dissipated 
 in copious gray fumes, which affect not the 
 smell ; leaving behind a small quantity of 
 ashes, that do not change either red or blue 
 tincture of litmus. Neutralized by potash 
 it crystallizes in groups of long prisms: by 
 soda, in cubes, or triangular laminae, some- 
 times in groups, sometimes single ; and 
 by ammonia, in beautiful prisms with six 
 planes, which soon lose their transparency, 
 and acquire a silvery white hue. If the 
 mellitic acid be dissolved in lime-water, and 
 
 a solution of calcined strontian or bary- 
 tes be dropped into it, a white precipitate is 
 thrown down, which is redissolved on add- 
 ing muriatic acid. With a solution of ace- 
 tate of barytes, it produces likewise a white 
 precipitate, which nitric acid redissolves. 
 With solution of muriate of barytes, it pro- 
 duces no precipitate, or even cloud ; but af- 
 ter standing some time, fine transparent 
 needly crystals are deposited. The mellitic 
 acid produces no change in a solution of ni- 
 trate of silver. From a solution of nitrate of 
 mercury, either hot or cold, it throws down 
 a copious white precipitate, which an addi- 
 tion of nitric acid immediately redissolves. 
 With nitrate of iron it gives an abundant 
 precipitate of a dun yellow colour, which 
 may be redissolved by muriatic acid. With 
 a solution of acetate of lead, it produces an 
 abundant precipitate, immediately redissolv- 
 ed on adding nitric acid. With acetate of 
 copper, it gives a grayish-green precipitate; 
 but it does not affect a solution of muriate 
 of copper. Lime-water precipitated by it, 
 is immediately redissolved on adding nitric 
 acid. 
 
 M. Klaproth was never able to convert 
 this acid into the oxalic by means of nitric 
 acid, which only changed its brownish co- 
 lour to a pale yellow. 
 
 * The jnellite, or native mellate of alumina, 
 consists, according to Klaproth, of 46 acid + 
 
 1 6 alumina + 5 8 water = 1 00 ; from which, 
 calling the prime of alumina 3.2, that of mel- 
 litic acid appears to be 9.2.* 
 
 * Acid (Menispermic). The sedds of mc- 
 nispermum cocculus being macerated for 24 
 hours in 5 times their weight of water, first 
 cold, and then boiling hot, yield an infusion, 
 from which solution of subacetate of lead 
 throws down a menispermate of lead. This 
 is to be washed and drained, diffused through 
 water, and decomposed by a current of sul- 
 phuretted hydrogen gas. The liquid thus 
 freed from lead, is to be deprived of sul- 
 phuretted hydrogen by heat, and then forms 
 solution of menispermic acid. By repeated 
 evaporations and solutions in alcohol, it loses 
 its bitter taste, and becomes a purer acid. 
 It occasions no precipitate with lime-water; 
 with nitrate of barytes it yields a gray preci- 
 pitate ; with nitrate of silver, a deep yellow ; 
 and with sulphate of magnesia, a copious 
 precipitate.* 
 
 * Acid (Molyrdic). The native sulphuret 
 of molybdenum being roasted for some time, 
 and dissolved in water of ammonia, when 
 nitric acid is added to this solution, the mo- 
 lybdic acid precipitates in fine white scales, 
 which become yellow, on melting and sub- 
 liming them. It changes the vegetable blues 
 to red, but less readily and powerfully than 
 the following acid. 
 
 M. Bucholz found that H)0 parts of the 
 sulphuret gave 90 parts of molybdic acid. 
 
ACI 
 
 ACi 
 
 Iii other experiments in which he oxidized 
 molybdenum, he found that 100 of the metal 
 combined with from 49 to 50 of oxygen. 
 Berzelius, after some vain attempts to analyze 
 the molybdates of lead and barytes, found that 
 the only method of obtaining an exact result 
 was to form a molybdate of lead. He dis- 
 solved 10 parts of neutral nitrate of lead in 
 water, and poured an excess of solution of 
 crystallized molybdate of ammonia into the 
 liquid. The molybdate of lead, washed, 
 dried and heated to redness, weighed 1 1 .068. 
 No traces of lead were found in the liquid 
 by sulphate of ammonia; hence these 11.068 
 of lead, evince 67.3 per cent of oxide of lead. 
 This salt then is composed of 
 
 Molybdic acid 39.194 9.0 
 
 Oxide of lead 60.806 14.0 
 
 100.000 
 
 And from Bucholz we infer, that this prime 
 equivalent 9, consists of 3 of oxygen 6 
 metal; while molybdous acid will be 2 oxy- 
 gen 6 metal = 8.0. 
 
 Molybdic acid has a specific gravity of 
 3.460. In an open vessel it sublimes into 
 brilliant yellow scales ; 960 parts of boiling 
 water dissolve one of it, affording a pale yel- 
 low solution, which reddens litmus, but has 
 no taste. Sulphur, charcoal, and several 
 metals decompose the molybdic acid. Molyb- 
 date of potash is a colourless salt. Molyb- 
 dic acid gives, with nitrate of lead, a white 
 precipitate, soluble in nitric acid ; with the 
 nitrates of mercury and silver, a white flaky 
 precipitate ; with nitrate of copper, a green- 
 ish precipitate ; with solutions of the neutral 
 sulphate of zinc, muriate of bismuth, muriate 
 of antimony, nitrate of nickel, muriates of 
 gold and platinum, it produces white preci- 
 pitates. When melted with borax, it yields 
 a bluish colour ; and paper dipped in its so- 
 lution becomes, in the sun, of a beautiful 
 blue. * 
 
 The neutral alkaline molybdates precipi- 
 tate all metallic solutions. Gold, muriate of 
 mercury, zinc, and manganese, are precipi- 
 tated in the form of a white powder ; iron 
 and tin, from their solutions in muriatic 
 acid, of a brown colour ; cobalt, of a rose 
 colour ; copper, blue ; and the solutions of 
 alum and quick lime, white. If a dilute 
 solution of recent muriate of tin be precipi- 
 tated by a dilute solution of molybdate of 
 potash, a beautiful blue powder is obtained. 
 
 The concentrated sulphuric acid dissolves 
 a considerable quantity of the molybdic acid, 
 the solution becoming of a fine blue colour 
 as it cools, at the same time that it thickens ; 
 the colour disappears again on the applica- 
 tion of heat, but returns again by cooling. 
 A strong heat expels the sulphuric acid. 
 The nitric acid has no effect on it ; but the 
 muriatic dissolves it in considerable quantity, 
 and leaves a dark blue residuum when dis- 
 
 tilled. With a strong heat it expels a por- 
 tion of sulphuric acid from sulphate of potash. 
 It also disengages the acid from nitre and 
 common salt by distillation. It has some 
 action upon the filings of the metals in the 
 moist way. 
 
 The molybdic acid has not yet been em- 
 ployed in the arts. 
 
 * Acid (Molybdous). The deutoxide of 
 molybdenum is of a blue colour, and pos- 
 sesses acid properties. Triturate 2 parts of 
 molybdic acid, with 1 part of the metal, 
 along with a little hot water, in a porcelain 
 mortar, till the mixture assumes a blue co- 
 lour. Digest in 10 parts of boiling water, 
 filter, and evaporate the liquid in a heat of 
 about 120°. The blue oxide separates. It 
 reddens vegetable blues, and forms salts with 
 the bases. Air or w r ater, when left for some 
 time to act on molybdenum, convert it into 
 this acid. It consists of about 100 metal to 
 
 34 oxygen. * 
 
 Acid (Moroxylic). In the botanic gar- 
 den at Palermo, Mr Thompson found an 
 uncommon saline substance on the trunk 
 of a white mulberry tree. It appeared as a 
 coating on the surface of the bark in little 
 granulous drops of a yellowfish and blackish 
 brown colour, and had likewise penetrated 
 its substance. M. Klaproth, who analyzed 
 it, found that its taste was somewhat like 
 that of succinic acid ; on burning coals it 
 swelled up a little, emitted a pungent va- 
 pour scarcely visible to the eye, and left a 
 slight earthy residuum. Six hundred grains 
 of the bark loaded with it were lixiviated with 
 w r ater, and afforded 320 grains of alight salt, 
 resembling in colour a light wood, and com- 
 posed of short needles united in radii. It 
 w r as not deliquescent ; and though the crys- 
 tals did not form till the solution was greatly 
 condensed by evaporation, it is not very solu- 
 ble, since 1000 parts of water dissolve but 
 
 35 with heat, and 15 cold. 
 
 This salt was found to be a compound of 
 lime and a peculiar vegetable acid, with some 
 extractive matter. 
 
 To obtain the acid separate, M. Klap- 
 roth decomposed the calcareous salt by acetate 
 of lead, and separated the lead by sulphuric 
 acid. He likewise decomposed it directly 
 by sulphuric acid. The product was still 
 more like succinic acid in taste; was not deli- 
 quescent ; easily dissolved both in water and 
 alcohol ; and did not precipitate the metallic 
 solutions, as it did in combination w ith lime. 
 Twenty grains being slightly heated in a 
 small glass retort, a number of drops of an 
 acid liquor first came over ; next a concrete 
 salt arose, that adhered flat against the top 
 and part of the neck of the retort in the 
 form of prismatic crystals, colourless and 
 transparent ; and a coaly residuum remain- 
 ed. The acid was then washed out, and 
 crystallized by spontaneous evaporation. 
 
ACI 
 
 ACI 
 
 Thus sublimation appears to be the best 
 mode of purifying the salt, but it adhered 
 too strongly to the lime to be separated 
 from it directly by heat without being de- 
 composed. 
 
 Not having a sufficient quantity to deter- 
 mine its specific characters, though he con- 
 ceives it to be a peculiar acid, coming near- 
 est to the succinic both in taste and other 
 qualities, Mr Klaproth has provisionally 
 given it the name of moroxylic, and the cal- 
 careous salt containing it that of moroxylate 
 of lime. 
 
 Acid (Mucic). This acid has been gene- 
 rally known by the name of saccholactic, be- 
 cause it was first obtained from sugar of 
 milk ; but as all the gums appear to afford 
 it, and the principal acid in sugar of milk is 
 the oxalic, chemists in general now distin- 
 guish it by the name of mucic acid. 
 
 It was discovered by Scheele. Having 
 poured twelve ounces of diluted nitric acid 
 on four ounces of powdered sugar of milk in 
 a glass retort on a sand bath, the mixture 
 became gradually hot, and at length effer- 
 vesced violently, and continued to do so for a 
 considerable time after the retort was taken 
 from the fire. It is necessary therefore to 
 use a large retort, and not to lute the receiver 
 too tight. The effervescence having nearly 
 subsided, the retort was again placed on the 
 sand heat, and the nitric acid distilled off, 
 till the mass had acquired a yellowish colour. 
 This exhibiting no crystals, eight ounces 
 more of the same acid were added, and the 
 distillation repeated, till the yellow colour of 
 the fluid disappeared. As the fluid was in- 
 spissated by cooling, it was redissolved in 
 eight ounces of water, and filtered. The fil- 
 tered liquor held oxalic acid in solution, and 
 seven drams and a half of a white powder re- 
 mained on the filter. This powder was the 
 acid under consideration. 
 
 If one part of gum be heated gently with 
 two of nitric acid, till a small quantity of ni- 
 trous gas and of carbonic acid is disengaged, 
 the dissolved mass will deposit on cooling 
 the mucic acid. According to Fourcroy and 
 Vauquelin, different gums yield from 14 to 
 26 hundredths of this acid. 
 
 This pulverulent acid is soluble in about 
 60 parts of hot water, and by cooling, a 
 fourth part separates in small shining scales, 
 that grow white in the air. It decomposes 
 the muriate of barytes, and both the nitrate 
 and muriate of lime. It acts very little on 
 the metals, but forms with their oxides salts 
 scarcely soluble. It precipitates the nitrates 
 of silver, lead, and mercury. With potash it 
 forms a salt soluble in eight parts of boiling 
 water, and crystallizable by cooling. That 
 of soda requires but five parts of water, and 
 is equally crystallizable. Both these salts 
 are still more soluble when the acid is in ex- 
 cess. 'I'll at of ammonia is deprived of its 
 
 base by heat. The salts of barytes, lime, 
 and magnesia, are nearly insoluble. 
 
 * Mucic or saccholactic acid has been 
 analyzed recently with much care; 
 
 Hydrogen. Carbon. Oxygen. 
 ByLussac, 3.62 + 33.69 +62.69 =100 
 
 Berzelius, 5.105 + 33.430+61.465 = 100 
 
 From saclactate of lead, Berzelius has in- 
 ferred the prime equivalent of the acid to be 
 13.1.* 
 
 * Acid (Muriatic). Let 6 parts of pure 
 and well dried sea salt be put into a glass 
 retort, to the beak of which is luted, in a ho- 
 rizontal direction, a long glass tube artifici- 
 ally refrigerated, and containing a quantity 
 of ignited muriate of lime. Upon the salt 
 pour at intervals 5 parts of concentrated oil 
 of vitriol, through a syphon funnel, fixed, 
 air-tight, in the tubulure of the retort. The 
 free end of the long tube being recurved, so 
 as to dip into the mercury of a pneumatic 
 trough, a gas will issue, which on coming in 
 contact with the air, will form a visible 
 cloud, or haze, presenting, when view r ed in a 
 vivid light, prismatic colours. This gas is 
 muriatic acid. When received in glass jars 
 over dry mercury, it is invisible, and pos- 
 sesses all the mechanical properties of air. 
 Its odour is pungent and peculiar. Its taste 
 acid and corrosive. Its specific gravity, ac- 
 cording to Sir H. Davy, is such, that 100 
 cubic inches weigh 39 grains, while by esti- 
 mation, he says, they ought to be 38.4 gr. 
 By the latter number the specific gravity, 
 compared to air, becomes 1.2590. By the 
 former number the density comes out 1 . 2800. 
 M. Gay Lussac states the sp.gr. at 1.2780. 
 Sir H.’s second number makes the prime 
 equivalent of chlorine 4.43, which comes 
 near to Berzelius’s latest result ; w r hile his first 
 number makes it 4.48, (See Chlorine). As 
 the attraction of muriatic acid gas for hygro- 
 metric water is very strong, it is very proba- 
 ble that 38.4 grs. may be the more exact 
 weight of 100 cubic inches, regarding the 
 same bulk of air as = 30.5. If an inflamed 
 taper be immersed in it., it is instantly extin- 
 guished. It is destructive of animal life ; 
 but the irritation produced by it on the epi- 
 glottis scarcely permits its descent into the 
 lungs. It is merely changed in bulk by altera- 
 tions of temperature; it experiences no change 
 of state. When potassium, tin, or zinc, is 
 heated in contact with this gas over mercury, 
 one-half of the volume disappears, and the 
 remainder is pure hydrogen. On examining 
 the solid residue, it is found to be a me- 
 tallic chloride. Hence muriatic acid gas 
 consists of chlorine and hydrogen, united in 
 equal volumes. This view of its nature was 
 originally given by Scheele, though obscur- 
 ed by terms derived from the vague and 
 visionary hypothesis of phlogiston. The 
 French school afterwards introduced the be- 
 liel that muriatic acid gas was a compound 
 
ACI 
 
 ACI 
 
 of an unknown radical and water ; and that 
 chlorine consisted of this radical and oxygen. 
 Sir II. Davy has the distinguished glory of 
 refuting the French hypothesis, and of prov- 
 ing by decisive experiments, that in the pre- 
 sent state of our knowledge, chlorine must 
 be regarded as a simple substance; and mu- 
 riatic acid gas, as a compound of it with hy- 
 drogen. 
 
 This gaseous acid unites rapidly, and in 
 large quantity, with water. The following 
 table of its aqueous combinations, was con- 
 structed after experiments made by Mr E. 
 Davy, in the laboratory of the Royal Insti- 
 tution, under the inspection of Sir H. Davy. 
 
 At temperature 45°, barometer 30. 
 
 100 parts of solution 
 
 of muriatic gas, in 
 
 Of muriatic 
 
 water, of specific gra- 
 
 gas, parts. 
 
 vi ty 
 
 1.21 contain 42.43 
 
 1.20 
 
 40.80 
 
 1.19 
 
 38.38 
 
 1.17 
 
 34.34 
 
 1.16 
 
 32.32 
 
 1.15 
 
 30.30 
 
 1.14 
 
 28.28 
 
 1.15 
 
 26.26 
 
 1.12 
 
 24.24 
 
 1.11 
 
 22.50 
 
 1.10 
 
 20.20 
 
 1.09 
 
 18.18 
 
 1.08 
 
 16.16 
 
 1.07 
 
 14.14 
 
 1.06 
 
 12.12 
 
 1.05 
 
 10.10 
 
 1.04 
 
 8.08 
 
 1.03 
 
 6.06 
 
 1.02 
 
 4.04 
 
 1.01 
 
 2.02 
 
 At the temperature of 10° Fahrenheit, 
 water absorbs about 4 SO times its bulk of 
 gas, and forms solution of muriatic acid gas 
 in water, the specific gravity of which is 
 1.2109. — Sir H. Davy's Elements. 
 
 In the Annals of Philosophy for October 
 and November 1817, there are two papers 
 on the constitution of liquid muriatic acid, 
 
 with tables, by Dr Ure, which coincide near- 
 ly with the preceding results. They were 
 founded on a great number of experiments 
 carefully performed, which are detailed in 
 the October number. In mixing strong li- 
 quid acid with water, he found that some 
 heat is evolved, and a small condensation of 
 volume is experienced, contrary to the obser- 
 vation of Mr Kirwan. Hence this acid 
 forms no longer an exception, as that emi- 
 nent chemist taught, to the general law of 
 condensation of volume, which liquid acids 
 obey in their progressive dilutions. Hitherto 
 indeed many chemists have, without due con- 
 sideration, assumed the half-sum or arithme- 
 tical mean of two specific gravities, to be the 
 truly computed mean ; and on comparing the 
 number thus obtained with that derived from 
 experiment, they have inferred the change 
 of volume, occasioned by chemical combina- 
 tion. The errors into which this false mode 
 of computation leads are excessively great, 
 when the two bodies differ considerably in 
 their specific gravities. A view of these erro- 
 neous results was given in Dr Ure’s third 
 table of sulphuric acid, published in the 7th 
 number of the Journal of Sciences and the 
 Arts, and reprinted in this Dictionary, arti- 
 cle Specific Gravity. When, however, the 
 two specific gravities do not differ much, the 
 errors become less remarkable. It is a sin- 
 gular fact, that the arithmetical mean, which 
 is always greater than the rightly computed 
 mean specific gravity, gives in the case of li- 
 quid muriatic acid, an error in excess, very 
 nearly equal to the actual increase of density. 
 The curious coincidence thus accidentally 
 produced, between accurate experiments and 
 a false mode of calculation is very instructive, 
 and ought to lead chemists to verify every 
 anomalous phenomenon, by independent 
 modes of research. Had Mr Kinvan, for 
 example, put into a nicely graduated tube 
 50 measures of strong muriatic acid, and 
 poured gently over it 50 measures of water, 
 he would have found after agitation, and 
 cooling the mixture to its former tempera- 
 ture, that there w as a decided diminution of 
 volume, as Dr Ure experimentally ascer- 
 tained.* 
 
ACI 
 
 ACI 
 
 TABLE of real Muriatic Acid, <$c. in 100 of the L iquid Acid, by Dr Ure. 
 
 Sp. Gr. 1 
 
 Dry | 
 Acid. 1 
 
 Acid 
 
 Gas. 
 
 Chlo- 
 
 rine. 
 
 Sp. Gr. 
 
 Dry 
 
 Acid. 
 
 Acid 
 
 Gas. 
 
 Chlo- j 
 rine. ' 
 
 Sp. Gr. 
 
 Dry 
 
 Acid. 
 
 Acid 
 
 Gas. 
 
 Chlo^ 
 
 rine. 
 
 1.1920 
 
 28.3 
 
 37.60 
 
 36.50 
 
 1.1272 
 
 18.68 
 
 24.82 24.09 
 
 1.0610 
 
 9.05 
 
 12.03 
 
 11.68 
 
 1.1900 
 
 28.02 
 
 37.22 
 
 36.1 3 
 
 1.1253 
 
 1 8.39 
 
 24.44 25.72 
 
 1.0590 
 
 8.77 
 
 1 1.65 
 
 11.31 
 
 1.1881 
 
 27.73 
 
 36.85 
 
 35.77 
 
 1.1233 
 
 18.11 
 
 24.06 23.36 
 
 1.0571 
 
 8.49 
 
 1 1.28 
 
 10.95 
 
 1.1863 
 
 27.45 
 
 36.47 
 
 35.40 
 
 1.1214 
 
 17.85 
 
 23.69 22.99 
 
 1.0552 
 
 8.21 
 
 10.90 
 
 10.58 
 
 1.184.5 
 
 27.17 
 
 36.10 
 
 35.04 
 
 1.1194 
 
 17.55 
 
 23.3 1 
 
 2 2.6 3 j 
 
 1.0533 
 
 7.92 
 
 1 0.55 
 
 10.22 
 
 1.1827 
 
 26.88 
 
 35.72 
 
 34.67 
 
 1.1173 
 
 17.26 
 
 22.93 22.26 
 
 1.0514 
 
 7.64 
 
 10.15 
 
 9.85 
 
 1.1808 
 
 26.60 
 
 35.34 
 
 34.31 
 
 1.1 155 
 
 16.98 
 
 22.56 21.90 
 
 1.0495 
 
 7.36 
 
 9.77 
 
 9.49 
 
 1.1790 
 
 26.32 
 
 34.97 
 
 33.94 
 
 1.1134 
 
 16.70 
 
 22.1821.53 
 
 1.0477 
 
 7.07 
 
 9.40 
 
 9.12 
 
 1.1772 
 
 26.04 
 
 34.59 
 
 33.58 
 
 1.1 1 15 
 
 16.41 
 
 21.81 21.17 
 
 | 1 
 
 1.0457 
 
 6.79 
 
 9.02 
 
 8.76 
 
 1.1753 
 
 25.75 
 
 34.22 
 
 33.21 
 
 1.1097 
 
 16.13 
 
 21.43 20.80' 
 
 1.0438 
 
 6.51 
 
 8.65 
 
 8.59 
 
 1.1735 
 
 25.47 
 
 33.84 
 
 32.85 
 
 1.1077 
 
 15.85 
 
 21.05,20.44! 
 
 1.0418 
 
 6.23 
 
 8.27 
 
 8.03 
 
 1.1715 
 
 25.19 
 
 33.46 
 
 32.48 
 
 1.1058 
 
 15.56 
 
 20.684 9.07: 
 
 1.0399 
 
 5.94 
 
 7.89 
 
 7.66 
 
 1.1698 
 
 24.90 
 
 55.09 
 
 32.1 2 
 
 1.1057 
 
 15.28 
 
 20.30 19.71 
 
 1.0380 
 
 5.66 
 
 7.52 
 
 7.30 
 
 1.1679 
 
 24.62 
 
 32.71 
 
 31.75 
 
 1.1018 
 
 1 5.00 
 
 19.93 
 
 19.34 
 
 1.0361 
 
 5.38 
 
 7.14 
 
 6.93 
 
 1.1661 
 
 24.34 
 
 33.54 
 
 31.59 
 
 1.0999 
 
 14.72 
 
 19.55 
 
 18.98 
 
 1.0342 
 
 5.09 
 
 6.77 
 
 6.57 
 
 1.1642 
 
 24.05 
 
 31.96 
 
 31.02 
 
 1.0980 
 
 14.43 
 
 19.17 
 
 18.61 
 
 1.0324 
 
 4.81 
 
 6.39 
 
 6.20 
 
 1.1624 
 
 23.77 
 
 31.58 
 
 30.66 
 
 1.0960 
 
 14.15 
 
 18.80 
 
 18.25 1 
 
 1.0304 
 
 4.53 
 
 6.02 
 
 5.84 
 
 1.1605 
 
 23.49 
 
 31.21 
 
 50.29 
 
 1.0941 
 
 13.87 
 
 18.42 
 
 17.88 
 
 1.0285 
 
 4.24 
 
 5.64 
 
 5.47 
 
 1.1587 
 
 23.20 
 
 30.83 
 
 29.93 
 
 1.0922 
 
 13.58 
 
 18.04 
 
 17.52 
 
 1.0266 
 
 3.96 
 
 5.26 
 
 5.11 
 
 1.1568 
 
 22.92 
 
 30.46 
 
 29.56 
 
 1.0902 
 
 13.30 
 
 17.67 
 
 17.15, 
 
 1.0247 
 
 3.68 
 
 4.89 
 
 4.74 
 
 1.1550 
 
 22.64 
 
 30.08 
 
 29.20 
 
 1.0883 
 
 1 3.02 
 
 17.29 
 
 16.79 
 
 1.0228 
 
 3.39 
 
 4.51 
 
 4.38 
 
 1.1531 
 
 22.36 
 
 29.70 
 
 28.83 
 
 1.0863 
 
 12.73 
 
 16.92 
 
 16.42 ) 
 
 1.0209 
 
 3.11 
 
 4.14 
 
 4.01 
 
 1.1510 
 
 22.07 
 
 29.33 
 
 28.47 
 
 1.0844 
 
 12.45 
 
 16.54 
 
 16.06^ 
 
 1.0190 
 
 2.83 
 
 3.76 
 
 3.65 
 
 1.1491 
 
 21.79 
 
 29.95 
 
 28.10 
 
 1.0825 
 
 12.17 
 
 16.17 
 
 15.69 
 
 1.0171 
 
 2.55 
 
 3.38 
 
 5.28 
 
 1.1471 
 
 21.51 
 
 28.57 
 
 27.74 
 
 1.0805 
 
 11.88 
 
 15.79 
 
 15.33 
 
 1.0152 
 
 2.26 
 
 3.01 
 
 2.92 
 
 1.1452 
 
 21.22 
 
 28.20 
 
 27.37 
 
 1.0785 
 
 11.60 
 
 15.42 
 
 14.96 
 
 1.0133 
 
 1.98 
 
 2.6S 
 
 2.55 
 
 1.1431 
 
 20.94 
 
 27.82 
 
 27.01 
 
 1.0765 
 
 11.32 
 
 15.04 
 
 14.60 
 
 1.0114 
 
 1.70 
 
 2.26 
 
 2.19 
 
 1.1410 
 
 20.66 
 
 27.45 
 
 26.64 
 
 1.0746 
 
 11.04 
 
 14.66 
 
 14.23 
 
 1.0095 
 
 1.41 
 
 1.88 
 
 1.82 
 
 1.1391 
 
 20.37 
 
 27.07 
 
 26.28 
 
 1.0727 
 
 10.75 
 
 14.29 
 
 13.87 
 
 1.0076 
 
 1.13 
 
 1.50 
 
 1.46 
 
 1.1371 
 
 20.09 
 
 26.69 
 
 25.91 
 
 1.0707 
 
 10.47 
 
 13.91 
 
 13.50 
 
 1.0056 
 
 0.85 
 
 1.1 S 
 
 1.09 
 
 1.1351 
 
 19.81 
 
 26.32 
 
 25.55 
 
 1.0688 
 
 10.19 
 
 15.54 
 
 13.14 
 
 1 .0037 
 
 0.56 
 
 0.752 
 
 0.73 
 
 1.1332 
 
 19.53 
 
 29.94 
 
 25.18 
 
 1.0669 
 
 9.90 
 
 15.16 
 
 12.77 
 
 1.0019 
 
 0.28 
 
 0.376 
 
 0.365 
 
 1.1312 
 
 19.24 
 
 25.57 
 
 24.82 
 
 1.0649 
 
 9.62 
 
 12.78 
 
 12.41 
 
 1.000 
 
 0.00 
 
 0.000 
 
 0.000 
 
 1.1293 
 
 18.96 
 
 25.19 
 
 24.45 
 
 1.0629 
 
 9.34 
 
 12.41 
 
 12.04 
 
 
 
 
 
 The fundamental density of the acid of 
 the preceding table is 1.1920, which is as 
 strong as it is comfortable to make or to use 
 in chemical researches. To find the quantity of 
 real acid in that possessed of greater density, 
 we have only to dilute it with a known pro- 
 portion of water, till it come within the range 
 of the table. The short memoir in the An- 
 nals for November, contains the logarithmic 
 series corresponding to the range of densities 
 and acid strengths ; but for all ordinary pur- 
 poses the following simple rule will serve : 
 Multiply the decimal part of the number 
 denoting the specific gravity by 147, the 
 product will be very nearly the per-centage 
 of dry acid, or by 197 when we wish to 
 know the per-centage of the acid gas. 
 
 Examples. 1 . The specific gravity is 1.141 ; 
 required the proportion of dry acid in 100 
 parts. 
 
 0.141 X 147= 20.72. By the table it is 
 
 20 . 66 . 
 
 2. The specific gravity is 1.960; the quan- 
 tity of acid gas is sought. 
 
 0.960 X 107= 18.9. By the table it is 
 18.8. 
 
 According to the new doctrine of Sir H. 
 Davy there is no such substance as the dry 
 acid ; and therefore in a theoretical point of 
 view r , the column containing it might have 
 been expunged. But for practical purposes 
 it is very useful, for it shews directly the in- 
 crease of weight which any alkaline or earthy 
 base will acquire, by combining with the 
 liquid acid. Thus, if we unite 100 grs. of 
 liquid acid sp. gravity 1.134 with quicklime, 
 we see that the base will, on evaporation to 
 dryness, be heavier by 16.7 grains. We 
 would require a little calculation to deter- 
 mine this amount from the other columns. 
 We have seen it stated that water, in absorb- 
 ing 480 times its bulk of the acid gas, be- 
 comes of specific gravity 1.2109. If we com- 
 pute from these data the increase of its bulky 
 we shall find it equal to 1.42, or nearly one 
 and a half the volume of the water. 481 
 parts occupy only 1.42 in bulk, a condensa- 
 tion of about 340 into one. The consequence 
 of this approximation of the particles, is the 
 evolution of their latent heat ; and accord- 
 ingly the heat produced in the condensation 
 of the gas is so great that it melts ice almost 
 
ACI 
 
 ACi 
 
 as rapidly as the steam of boiling water does. 
 Hence also in passing the gas from the beak 
 of a retort into a Woolfe’s apparatus contain- 
 ing water to be impregnated, it is necessary 
 to surround the bottles with cold water or 
 ice, it we wish a considerable condensation. 
 
 Dr Thomson, in the second volume of his 
 System of Chemistry, 5th edition, has com- 
 mitted some curious mistakes in treating of 
 the aqueous combination of muriatic acid gas. 
 He says, “ A cubic inch of water at the tem- 
 perature of 60°, barometer 29.4, absorbs 5 1 5 
 cubic inches of muriatic acid gas, which is 
 equivalent to 308 grains nearly. Hence 
 water thus impregnated contains 0.548, or 
 more than half of its weight of muriatic acid, 
 in the same state of purity, as when gaseous. 
 I caused a current of gas to pass through 
 water, till it refused to absorb any more. 
 The specific gravity of the acid thus obtained 
 was 1.203. If we suppose that the water in 
 this experiment absorbed as much gas as in 
 the last, it will follow' from it that 6 parts of 
 water, by being saturated with this gas, ex- 
 panded so as to occupy very nearly the bulk 
 of 1 1 parts ; but in all my trials the expan- 
 sion was only to 9 parts. This would indi- 
 cate a specific gravity of 1.477 ; yet upon 
 actually trying water thus saturated, its spe- 
 cific gravity was only 1.203. Is this differ- 
 ence owing to the gas that escapes during 
 the taking of the specific gravity?” page 282. 
 
 We are here presented w ith a puzzle for 
 the chemical student ; and an instructive ex- 
 ample, when one takes the trouble of unra- 
 velling the hank, of a contest between ex- 
 perimental results and false computation. 
 Granting all the experimental statements to 
 be exact, none of the consequences follow'. 
 For, in the first place, 515 cubic inches of 
 muriatic acid gas do not w r eigh 308 grains 
 nearly, but only 201 grains ; and hence, 
 secondly, his liquid acid could contain at ut- 
 most only 0.443 of its weight of gas, instead 
 of 0.548 ; and, in the third place, the calcu- 
 lated enlargement of bulk is 1.5, or from 6 
 to 9, and not to 1 1 ; so that the quere w'ith 
 which he concludes is superseded. But ano- 
 ther querc may here be started, about the ex- 
 perimental results themselves. Dr Thom- 
 son says, that a cubic inch of water absorbs 
 515 cubic inches of gas, and acquires the 
 specific gravity by experiment of 1.203. Sir 
 II. Davy states, that a cubic inch of water 
 absorbs about 480 cubic inches of gas, and 
 forms a liquid of specific gravity 1.2109. 
 Now it is remarkable that Dr Thomson’s 
 additional condensation of 35 inches of gas 
 gives a less specific gravity than we have in 
 the stronger acid of Sir II. Davy. 
 
 But farther, the table constructed by Sir 
 II. and E. Davy presents for its fundamen- 
 tal density the number 1.20 of Dr Thom- 
 son. Now this particular acid of 1.20 was 
 
 carefully analyzed by nitrate of silver, and is 
 stated by Sir II. to contain in 100 grains 
 40.8 grains of condensed gas. Of course 
 we have a remainder of 59.2 grains of water. 
 40.8 gr. of gas have a volume at the ordinary 
 pressure and temperature of 104 cubic in- 
 ches, reckoning the weight of 100 cubic in- 
 ches to be 39.162 gr. with Dr Thomson. 
 And as 59.2 gr. of water have absorbed 104 
 cubic inches, we have the following pro- 
 portion, 59.2 : 104 : : 252.5 : 443. Thus a 
 cubic inch has condensed only 443 cubic in- 
 ches, instead of 515, as by Dr Thomson. 
 And whatever error may be supposed to be 
 in their table, it is but minute, and undoubt- 
 edly does not consist in underrating the 
 quantity of condensed gas. 
 
 By uniting the base of this gas with silver, 
 and also with potassium, Berzelius has lately 
 determined the prime equivalent of muriatic 
 acid to be 3.4261, whence chlorine comes 
 out 4.4261, and muriatic gas 4.4261 -{- 
 0.125 (the prime of hydrogen) = 4.551 1. 
 But if w r e take 1.278 as the specific gravity 
 of this acid gas, then the specific gravity of 
 chlorine will be tw ice that number, minus the 
 specific gravity of hydrogen, or (1.278 X 2) 
 — 0.0694 = 2.4866 ; and as chlorine and 
 hydrogen unite volume to volume, then the 
 relation of the prime of chlorine will be to that 
 
 of hydrogen = } = 35.83. If we di- 
 
 b 0.0 69 4 
 
 vide this by 8, w e shall have 4.48, to repre- 
 sent the prime equivalent of chlorine, and 
 4.48 -j- 0. 125 = 4.605 for that of muriatic 
 acid gas. 
 
 But if we call the specific gravity of dry 
 muriatic acid gas 1.2590, as Sir H. Davy 
 says it should be by calculation, then the sp. 
 gravity of chlorine becomes 2.4486, and its 
 prime 4.42, a number agreeing nearly with 
 the latest researches of Berzelius. 
 
 Muriatic acid, from its composition, has 
 been termed by M. Gay Lussac the hydro- 
 chloric acid ; a name objected to, on good 
 grounds, by Sir H. Davy. It was prepared 
 by the older chemists in a very rude manner, 
 and w'as called by them spirit of salt.* 
 
 In the ancient method, common salt was 
 previously decrepitated, then ground with 
 dried clay, and kneaded or wrought with 
 w ater to a moderately stiff consistence, after 
 which it was divided into balls of the size of 
 a pigeon’s egg : these balls, being previously 
 w T ell dried, were put into a retort, so as to 
 fill the vessel two-thirds full; distillation 
 being then proceeded upon, the muriatic 
 acid came over when the heat was raised to 
 ignition. In this process eight or ten parts 
 of clay to one of salt are to be used. The 
 retort must be of stone-ware well coated, 
 and the furnace must be of that kind called 
 reverberatory. 
 
 It was formerly thought, that the salt was 
 
AC1 
 
 AC1 
 
 merely divided in this operation by the clay, 
 and on this account more readily gave out 
 its acid: but there can be little doubt, that 
 the effect is produced by the siliceous earth, 
 which abounds in large proportions in all 
 natural clays, and detains the alkali of the 
 salt by combining with it 
 
 * Sir H. Davy first gave the just explana- 
 tion of this decomposition. Common salt is 
 a compound of sodium and chlorine. I he 
 sodium may be conceived to combine with 
 the oxygen of the water in the earth, and 
 with the earth itself, to form a vitreous com- 
 pound ; and the chlorine to unite with the 
 hydrogen of the water, forming muriatic acid 
 gas. “ It is also easy,” adds he, “ according 
 to these new ideas, to explain the decomposi- 
 tion of salt by moistened litharge, the theory 
 of which has so much perplexed the most 
 acute chemists. It may be conceived to be 
 an instance of compound affinity; the chlorine 
 is attracted by the lead, and the sodium com- 
 bines with the oxygen of the litharge, and 
 with water, to form hydrate of soda, which 
 gradually attracts carbonic acid from the air. 
 When common salt is decomposed by oil of vi- 
 triol, it was usual to explain the phenomenon 
 by saying, that the acid by its superior affini- 
 ty, aided by heat, expelled the gas, and united 
 to the soda. But as neither muriatic acid 
 nor soda exists in common salt, we must 
 now modify the explanation, by saying that 
 the water of the oil of vitriol is first decom- 
 posed, its oxygen unites to the sodium to 
 form soda, which is seized on by the sul- 
 phuric acid, while the chlorine combines with 
 the hydrogen of the water, and exhales in 
 the form of muriatic acid gas.” 
 
 As 100 parts of dry sea salt, are capable of 
 yielding 62 parts by weight of muriatic acid 
 gas, these ought to afford by economical 
 management nearly 22 1 parts of liquid acid, 
 specific gravity 1.142, as prescribed by the 
 London College, or 200 parts of acid sp. gr. 
 1.160, as directed by the Edinburgh and 
 Dublin Pharmacopeias. 
 
 The fluid ounce of the London College 
 being yL of a wine pint, is equal in weight 
 to 1.265817 lbs. Troy divided by 16, which 
 gives 453.7 grains Troy. This weight multi- 
 plied by 1.142 = the specific gravity of 
 their standard acid, gives the product 520.4 ; 
 which being multiplied by 0.2763, the muri- 
 atic gas in 1.00 by Dr Ure’s table, we have 
 143.8 or 144 for the acid gas in the liquid 
 ounce, of the above density. We find this 
 quantity equivalent to 200 gr. of carbonate 
 of lime. Had the fundamental number 28.3 
 of Dr Ure’s table been made 28.6, as one of 
 his experiments related in the Annals of 
 Philosophy indicates, then a liquid ounce of 
 the above acid would have dissolved upwards 
 of 202 grains of pure calcareous carbonate. 
 But when the results fluctuate between 28.3 
 
 and 28.6, they become exceedingly difficult 
 to decide upon. As the difference is alto- 
 gether unimportant in practice, he does not 
 feel himself justified in making any altera- 
 tion in his table. The limit of its error is 
 certainly a fraction of one per cent. Were 
 29.0 the leading number, then a liquid oz. 
 of acid of 1.142, would dissolve 205 grains 
 of calc spar. It is obvious that the series of 
 specific gravities given in the above table, is 
 altogether independent of this question. If 
 28.6 should be preferred by any person, let 
 him multiply this number by 0.9, 0.8, 0.7, 0.6, 
 &c. and he w ill have a series of numbers re- 
 presenting the quantities of dry acids corres- 
 ponding to the specific gravities 1,190, 
 1.1755, 1.1550, 1.1551, &c. for these den- 
 sities are opposite to 90, 80, 70, 60, &c. per 
 cent of the strong acid. When this acid is 
 contaminated with sulphuric acid, it affords 
 precipitates wfith muriates of barytes and 
 strontites.* 
 
 We have described the ancient method of 
 extracting the gas from salt, which is now laid 
 aside. 
 
 The English manufacturers use iron stills 
 for this distillation, with earthen heads : 
 the philosophical chemist, in making the 
 acid of commerce , will doubtless prefer glass. 
 Five parts, by weight, of strong sulphu- 
 ric acid are to be added to six of decrepi- 
 tated sea salt, in a retort, the upper part of 
 which is furnished with a tube or neck, 
 through which the acid is to be poured upon 
 the salt. The aperture of this tube must 
 be closed with a ground stopper immediately 
 after the pouring. The sulphuric acid im- 
 mediately combines with the alkali, and ex- 
 pels the muriatic acid in the form of a peculiar 
 air, which is rapidly absorbed by w ater. As 
 this combination and disengagement take 
 place without the application of heat, and the 
 aerial fluid escapes very rapidly, it is neces^ 
 sary to arrange and lute the vessels together 
 before the sulphuric acid is added, and not 
 to make any fire in the furnace until the dis- 
 engagement begins to slacken ; at which 
 time it must be very gradually raised. Before 
 the modern improvements in chemistry w ere 
 made, a great part of the acid escaped for want 
 of water to combine with; but by the use of 
 Woolfe’s apparatus, (See Laboratory), the 
 acid air is made to pass through water, in which 
 it is nearly condensed, and forms muriatic acid 
 of double the weight of the water, though the 
 bulk of this fluid is increased one-half only. 
 The acid condensed in the first receiver, which 
 contains no water, is of a yellow' colour, aris- 
 ing from the impurities of the salt. 
 
 The marine acid in commerce has a straw 
 colour : but this is owing to accidental im- 
 purity ; for it does not obtain in the acid 
 produced by the impregnation of water with 
 the aeriform acid. 
 
ACI 
 
 AC1 
 
 The muriatic acid is one of those longest 
 known, and 'some of its compounds are 
 among those salts with which we are most 
 familiar. 
 
 * The muriates, when in a state of dryness, 
 are actually chlorides, consisting of chlorine 
 and the metal ; but since moisture makes 
 them instantly pass to the state of muriates, 
 we shall describe them under this article. 
 The sulphates and nitrates, when destitute of 
 water, may in like manner be regarded as 
 containing neither acid nor alkali, and might 
 therefore be transported to some new depart- 
 ment of classification, to be styled sulphides 
 and nitrides, as we shall see in treating of 
 salts. * 
 
 The muriate of barytes crystallizes in ta- 
 bles bevelled at the edges, or in octa'e'dral 
 pyramids applied base to base. It is soluble 
 in five parts of water at 60°, in still less at a 
 boiling heat, and also in alcohol. It is not 
 altered in the air, and but partly decompos- 
 able by heat. The sulphuric acid separates 
 its base ; and the alkaline carbonates and 
 sulphates decompose it by double affinity. It 
 is best prepared by dissolving the carbonate 
 in dilute muriatic acid ; and if contaminated 
 with iron or lead, which occasionally happens, 
 these may be separated by the addition of a 
 small quantity of liquid ammonia, or by boil- 
 ing and stirring the solution with a little 
 barytes. Mr Goettling recommends to prepare 
 it from the sulphate of barytes : eight parts of 
 which in fine powder are to be mixed w ith 
 two of muriate of soda, and one of charcoal 
 powder. This is to be pressed hard into a 
 Hessian crucible, and exposed for an hour 
 and a half to a red heat in a wind furnace. 
 The cold mass, being powdered, is to be 
 boiled a minute or two in sixteen parts of 
 water, and then filtered. To this liquor mu- 
 riatic acid is to be added by little and little, 
 till sulphuretted hydrogen ceases to be evolv- 
 ed ; it is then to be filtered, a little hot water 
 to be poured on the residuum, the liquor 
 evaporated to a pellicle, filtered again, and 
 then set to crystallize. As the muriate of 
 soda is much more soluble than the muriate 
 of barytes, and does not separate by cooling, 
 the muriate of barytes will crystallize into a 
 perfectly white salt, and leave the muriate of 
 soda in the mother water, w hich may be eva- 
 porated repeatedly till no more muriate of 
 barytes is obtained. This salt w r as first em- 
 ployed in medicine by Dr Crawford, chiefly 
 in scrofulous complaints and cancer, begin- 
 ning with doses of a few drops of the saturat- 
 ed solution twice a-day, and increasing it 
 gradually, as far as forty or fifty drops in 
 some instances. In large doses it excites 
 nausea, and has deleterious effects. Fourcroy 
 says it has been found very successful in 
 scrofula in France. It has likewise been 
 recommended as a vermifuge ; and it has 
 been given with much apparent advantage, 
 
 even to very young children, where the usual 
 symptoms of worms occurred, though none 
 were ascertained to be present. As a test of 
 sulphuric acid it is of great use. 
 
 The muriate of potash, formerly known 
 by the names of febrifuge salt of ‘ Sylvius , di- 
 gestive salt , and regenerated sea salt , crystal- 
 lizes in regular cubes, or in rectangular pa- 
 rallelopipedons ; decrepitating on the fire, 
 without losing much of their acid, and ac- 
 quiring a little moisture from damp air, and 
 giving it out again in dry. Their taste is 
 saline and bitter. They are soluble in thrice 
 their weight of cold water, and in but little 
 less of boiling w ater, so as to require spon- 
 taneous evaporation for crystallizing. Four- 
 croy recommends, to cover the vessel with 
 gauze, and suspend hairs in it, for the pur- 
 pose of obtaining regular crystals. 
 
 It is sometimes prepared in decomposing 
 sea salt by common potash for the purpose of 
 obtaining soda ; and may be formed by the 
 direct combination of its constituent parts. 
 
 It is decomposable by the sulphuric and 
 nitric acids. Barytes decomposes it, though 
 not completely. And both silex and alumina 
 decomposed it partially in the dry way. It 
 decomposes the earthy nitrates, so that it 
 might be used in saltpetre manufactories to 
 decompose the nitrate of lime. 
 
 Muriate of soda, or common salt, is of con- 
 siderable use in the arts, as well as a neces- 
 sary ingredient in our food. It crystallizes 
 in cubes, which are sometimes grouped to- 
 gether in various ways, and not unfrequently 
 form hollow quadrangular pyramids. In 
 the fire it decrepitates, melts, and is at length 
 volatilized. When pure it is not deliquescent. 
 One part is soluble in of cold water, and 
 in little less of hot, so that it cannot be crys- 
 tallized but by evaporation. According to 
 M. Chenevix, it is soluble in alcohol also, 
 particularly when it is mixed with the chlorate. 
 
 Common salt is found in large masses, or 
 in rocks under the earth, in England and else- 
 w'here. In the solid form it is called sal 
 gem or rock salt. If it be pure and transpa- 
 rent, it may be immediately used in the state 
 in which it is found ; but if it contain any 
 impure earthy particles, it should be previ- 
 ously freed from them. In some countries it 
 is found in incredible quantities, and dug up 
 like metals from the bow'els of the earth. In 
 this manner has this salt been dug out of 
 the celebrated salt mines near Bochnia and 
 Wieliczka, in Poland, ever since the middle 
 of the 13th century, consequently above these 
 500 years, in such amazing quantities, that 
 sometimes there have been 20,000 tons ready 
 for sale. In these mines, which are said to 
 reach to the depth of several hundred fathoms, 
 500 men are constantly employed. The pure 
 and transparent salt needs no other prepara- 
 tion than to be beaten to small pieces or 
 ground in a mill. But that which is more 
 
ACI 
 
 ACI 
 
 impure must be elutriated, purified, and boil- 
 ed. That which is quite impure, and full of 
 small stones, is sold under the name of rock 
 salt, and is applied to ordinary uses ; it may 
 likewise be used for strengthening weak and 
 poor brine- springs. 
 
 Though the salt mines of Wieliczka, near 
 Cracow in Poland, have long astonished the 
 philosopher and traveller, yet it deserves to 
 be remarked, that the quantity of rock salt 
 obtained from the mines of Northwich is 
 greatly superior to that obtained at Cracow. 
 The bishop of LlandafF affirms, that a single 
 pit, into which he descended, yielded at a 
 medium 4000 tons of salt in a year, which 
 alone is about two-thirds of that raised in the 
 Polish mines. This rock salt is never used 
 on our tables in its crude state, as the Polish 
 rock salt is ; and though the pure transparent 
 salt might be used with our food, without 
 any danger, yet it is prohibited under a 
 penalty of 40s. for every pound of rock salt 
 so applied. It is partly purified in water, 
 and a great part of it is sent to Liverpool 
 and other places, where it is used either for 
 strengthening brine-springs or sea water. 
 
 Beside the salt mines 'here mentioned, 
 where the common salt is found in a concrete 
 6tate, under the name of rock salt, there is at 
 Cordova, in the province of Catalonia in 
 Spain, a remarkable solid mountain of rock 
 salt : this mountain is between four and five 
 hundred feet in height, and a league in 
 circuit ; its depth below the surface of the 
 earth is not known. This mountain contains 
 the rock salt without the least admixture of 
 any other matter. 
 
 The waters of the ocean every- where 
 abound with common salt, though in diffe- 
 rent proportions. The water of the Baltic 
 sea is said to contain one sixty-fourth of its 
 weight of salt ; that of the sea between Eng- 
 land and Flanders contains one thirty-second 
 part ; that on the coast of Spain, one six- 
 teenth part ; and between the tropics it is 
 said, erroneously, to contain from an eleventh 
 to an eighth part. 
 
 The water of the sea contains, besides the 
 common salt, a considerable proportion of 
 muriate of magnesia, and some sulphate of 
 lime, of soda, and potash. The former is 
 the chief ingredient of the remaining liquid 
 which is left after the extraction of the com- 
 mon salt, and is called the mother water. 
 Sea water, if taken up near the surface, con- 
 tains also the putrid remains of animal sub- 
 stances, which render it nauseous, and in a 
 long continued calm cause the sea to stink. 
 
 J he whole art of extracting salt from waters 
 which contain it, consists in evaporating the 
 water in the cheapest and most convenient 
 manner. In England, a brine composed of 
 sea water, with the addition of rock salt, is 
 evaporated in large shallow iron boilers ; and 
 the crystals of salt are taken out in baskets. 
 
 In Russia, and probably in other northern 
 countries, the sea water is exposed to freeze; 
 and the ice, which is almost entirely fresh, 
 being taken out, the remaining brine is much 
 stronger, and is evaporated by boiling. In 
 the southern parts of Europe the salt-makers 
 take advantage of spontaneous evaporation. 
 A flat piece of ground near the sea is chosen, 
 and banked round, to prevent its being over- 
 flowed at high water. The space within the 
 hanks is divided by low walls into several 
 compartments, which successively communi- 
 cate with each other. At flood tide, the first 
 of these is filled with sea w ater ; which, by 
 remaining a certain time, deposits its im- 
 purities, and loses part of its aqueous fluid. 
 The residue is then suffered to run into the 
 next compartment ; and the former is again 
 filled as before. From the second compart- 
 ment, after a due time, the water is trans- 
 ferred into a third, w hich is lined with clay 
 well rammed and levelled. At this period 
 the evaporation is usually brought to that de- 
 gree, that a crust of salt is formed on the 
 surface of the water, wdiich the workmen 
 break, and it immediately falls to the bottom. 
 They continue to do this, until the quantity 
 is sufficient to be raked out, and dried in 
 heaps. This is called bay salt. 
 
 In some parts of France, and also on the 
 coast of China, they w r ash the dried sands 
 of the sea with a small proportion of water, 
 and evaporate this brine in leaden boilers. 
 
 There is no difference between this salt 
 and the lake salt extracted from different 
 lakes, excepting such as may be occasioned 
 by the casual intervention of some substances. 
 In this respect the Jeltonic salt water lake, 
 in the Russian dominions, near Saratow and 
 Dmitrewsk, deserves our attention. In the 
 year 1748, when the Russians first fetched 
 salt thence, the lake was almost solid with 
 salt; and that to such a degree, that they 
 drove their heavy waggons over it, as over a 
 frozen river, and broke up the salt. But 
 since the year 1757 the water has increased 
 so much, that at this time it is nothing more 
 than a lake very strongly impregnated with 
 salt. The Jeltonic lake salt contains at the 
 same time alum and sulphate of magnesia. 
 
 At several places in Germany, and at 
 Montmarot in France, the waters of salt 
 springs are pumped up to a large reservoir 
 at the top of a building or shed ; from which 
 it drops or trickles through small apertures 
 upon boards covered with brush-wood. The 
 large surface of the water thus exposed to the 
 air causes a very considerable evaporation ; 
 and the brine is afterward conveyed to the 
 boilers for the perfect separation of the salt. 
 
 I o free common salt from those mixtures 
 that render it deliquescent, and less fit for the 
 purposes to which it is applied, it maybe put 
 into a conical vessel with a small aperture at 
 the point, and a saturated solution of the 
 
ACI 
 
 ACI 
 
 muriate of soda boiling hot be poured on it. 
 Ibis solution will dissolve and carry off any 
 other salts mixed with the soda, and leave it 
 quite pure, by repeating the process three or 
 four times. 
 
 hrom this salt, as already observed, the 
 muriatic acid is extracted ; and of late years 
 to obtain its base separate, in the most eco- 
 nomical mode, for the purposes of the arts, 
 has been an object of research. The process 
 ot Scheele, which consists in mixing the 
 muriate of soda with red oxide of lead, mak- 
 ing this into a soft paste with water, and al- 
 lowing it to stand thus for some time, moist- 
 ening it with water as it gets dry, and then 
 separating the soda from the muriate of lead 
 by lixiviation, has been resorted to in this 
 country. Mr Turner some years ago had 
 a patent for it ; converting the muriate of 
 lead into a pigment, which was termed mi- 
 neral or patent yellow , by heating it to fusion. 
 The oxide of lead should be at least twice the 
 weight of the salt. This would have answer- 
 ed extremely well, had there been an adequate 
 and regular demand for the pigment. At 
 present, we understand, the greater part of 
 the carbonate of soda in the market is fur- 
 nished by decomposing the sulphate of soda 
 left after the muriatic acid is expelled in the 
 usual way of manufacturing it from common 
 salt. Various processes for this purpose were 
 tried in France and made public by the 
 French government, all depending on the 
 principle of decomposing the acid of the sul- 
 phate, by charcoal, and at the same time add- 
 ing some other material to prevent the soda 
 from forming a sulphuret. What they con- 
 sider as the best, is to mix the sulphate of 
 soda with an equal weight of chalk and ra- 
 ther more than half its weight of charcoal 
 powder, and to expose the mixture in a re- 
 verberatory furnace to a heat sufficient to 
 bring them to a state of imperfect liquefaction. 
 Much of the sulphur formed will be expelled 
 in vapour and burned, the mixture being 
 frequently stirred to promote this ; and this 
 is continued till the mass on cooling assumes 
 a fine grain. It is then left exposed to a 
 humid atmosphere, and the carbonate of soda 
 may be extracted by lixiviation, the sulphur 
 not consumed having united with the lime. 
 Tinmen’s sheds, or old iron, may be employ- 
 ed instead of chalk, in the proportion of 65 
 parts to 200 of sulphate of soda, and 62 of 
 charcoal ; or chalk and iron may be used at 
 the same time in different proportions. The 
 muriate of soda might be decomposed in the 
 first instance by the sulphate of iron, instead 
 of the sulphuric acid. The carbonate of soda 
 thus prepared, however, is not free from sul- 
 phur, and Dize recommends the abstraction 
 of it by adding litharge to the lixivium in a 
 state of ebullition, which will render the 
 alkali pure. Oxide of manganese was sub- 
 stituted in the same way with equal success; 
 
 and this may be used repeatedly, merely by 
 calcining it after each time to expel the sul- 
 phur. 
 
 Mr Accum gives the following me- 
 thod, as having answered extremely well in 
 a soda manufactory in which he was em- 
 ployed : — Five hundred pounds of sulphate 
 of soda, procured from the bleachers, who 
 make a large quantity in preparing their 
 muriatic acid from common salt, were put 
 into an iron boiler with a sufficient quantity 
 of soft water. Into another boiler were put 
 560 lbs. of good American potash, or 570 if 
 the potash were indifferent, dissolved in about 
 30 pails of water, or as little as possible. 
 When both were brought to boil, the solu- 
 tion of potash was ladled into that of sul- 
 phate of soda, agitating the mixture, and 
 raising the fire as quickly as possible. When 
 the wdiole boiled, it was ladled into a wooden 
 gutter, that conveyed it to a wooden cistern 
 lined with lead near half an inch thick, in a 
 cool place. Sticks were placed across the 
 cistern, from which slips of sheet lead, two or 
 three inches wide, hung down into the fluid 
 about four inches distant from each other. 
 When the whole was cold, which in winter 
 W'as in about three days, the fluid was draw n 
 off, the crystalized salt was detached from 
 the slips of lead, and the rock of salt fixed to 
 the bottom was separated by a chisel and 
 mallet. The salt being washed in the same 
 cistern, to free it from impurities, was then 
 returned to the boiler, dissolved in clear 
 water, and evaporated till a strong pellicle 
 formed. Letting it cool till the hand could 
 be dipped into it, it was kept at this tem- 
 perature as long as pellicles would form over 
 the whole surface, and fall to the bottom. 
 When no more pellicles appeared without 
 blowing on the surface, the fire was put out, 
 and the solution returned into the cistern to 
 crystallize. If the solution be suffered to 
 cool pretty low, very little sulphate of pot- 
 ash will be found mixed with the soda ; but 
 the rocky masses met with in the market 
 generally contain a pretty large quantity. In 
 the process above described, the produce of 
 the mixed salt from 100 lbs. of sulphate of 
 soda was in general from 136 to 139 lbs. 
 
 lleside its use in seasoning our food, and 
 preserving meat both for domestic consump- 
 tion and during the longest voyages, and in 
 furnishing us with the muriatic acid and soda, 
 salt forms a glaze for coarse pottery, by be- 
 ing thrown into the oven where it is baked ; 
 it improves the whiteness and clearness of 
 glass ; it gives greater hardness to soap ; in 
 melting metals it preserves their surface from 
 calcination, by defending them from the air, 
 and is employed with advantage in some 
 assays ; it is used as a mordant, and for im- 
 proving certain colours, and enters more or 
 less into many other processes of the arts. 
 
 The muriate of strontian has not long 
 
ACI 
 
 ACI 
 
 been known. Dr Hope first distinguished 
 it from muriate of barytes. It crystallizes 
 in very slender hexagonal prisms, has a cool 
 pungent taste, without the austerity of the 
 muriate of barytes, or the bitterness of the 
 muriate of lime ; is soluble in 0.75 of water 
 at 60°, and to almost any amount in boiling 
 water ; is likewise soluble in alcohol, and 
 gives a blood red colour to its flame. 
 
 It has never been found in nature, but 
 may be prepared in the same way as the 
 muriate of barytes. 
 
 The muriate of lime has been known by 
 the names of marine selenite , calcareous ma- 
 rine salty muria , and fixed sal ammoniac . It 
 crystallizes in hexaedral prisms, terminated 
 by acute pyramids ; but if the solution be 
 greatly concentrated, and exposed to a low 
 temperature, it is condensed in confused 
 bundles of needly crystals. Its taste is acrid, 
 bitter, and very disagreeable. It is soluble 
 in half its weight of cold water, and by heat 
 in its own water of crystallization. It is one 
 of the most deliquescent salts known ; and 
 when deliquesced has been called oil of lime . 
 It exists in nature, but neither very abundant- 
 ly nor very pure. It is formed in chemical 
 laboratories, in the decomposition of muriate 
 of ammonia ; and Homberg found, that, if 
 it were urged by a violent heat till it con- 
 densed, on cooling, into a vitreous mass, it 
 emitted a phosphoric light upon being struck 
 by any hard body, in which state it was call- 
 ed Homberg s phosphorus. 
 
 Hitherto it has been little used except for 
 frigorific mixtures ; and with snow it pro- 
 duces a very great degree of cold. Four- 
 croy, indeed, says he has found it of great 
 utility in obstructions of the lymphatics, and 
 in scrofulous affections. 
 
 The muriate of ammonia has long been 
 known by the name of sal ammonia , or am- 
 moniac. It is found native in the neighbour- 
 hood of volcanoes, where it is sublimed some- 
 times nearly pure, and in different parts of 
 Asia and Africa. A great deal is carried 
 annually to Russia and Siberia from Bucha- 
 rian Tartary ; and we formerly imported 
 large quantities from Egypt, but now manu- 
 facture it at home. See Ammonia. 
 
 This salt is usually in the form of cakes, 
 with a convex surface on one side, and con- 
 cave on the other, from being sublimed into 
 large globular vessels ; but by solution it 
 may be obtained in regular quadrangular 
 crystals. It is remarkable for possessing a 
 certain degree of ductility, so that it is not 
 easily pulverable. It is soluble in 3^ parts 
 of water at 60°, and in little more than its 
 own weight of boiling water. Its taste is 
 cool, acrid, and bitterish. Its specific gra- 
 vity is 1.42. It attracts moisture from the 
 air but very slightly. 
 
 Muriate of ammonia has been more em- 
 ployed in medicine than it is at present. It 
 
 is sometimes useful as an auxiliary to the 
 bark in intermittents ; in gargles it is bene- 
 ficial, and externally it is a good discutient. 
 In dyeing it improves or heightens different 
 colours. In tinning and soldering it is em- 
 ployed to preserve the surface of the metals 
 from oxidation. In assaying it discovers 
 iron, and separates it from some of its com- 
 binations. 
 
 The muriate of magnesia is extremely de- 
 liquescent, soluble in an equal weight of wa- 
 ter, and difficultly crystallizable. It dissolves 
 also in five parts of alcohol. It is decom- 
 posable by heat, which expels its acid. Its 
 taste is intensely bitter. 
 
 With ammonia this muriate forms a triple 
 salt, crystallizable in little polyedrons, which 
 separate quickly from the water, but are not 
 very regularly formed. Its taste partakes 
 of that of both the preceding salts. The 
 best mode of preparing it is by mixing a so- 
 lution of 27 parts of muriate of ammonia 
 with a solution of 73 of muriate of magne- 
 sia ; but it may be formed by a semi-decom- 
 position of either of these muriates by the 
 base of the other. It is decomposable by 
 heat, and requires six or seven times its 
 weight of water to dissolve it. 
 
 Of the muriate of glucine we know but 
 little. It appears to crystallize in very small 
 crystals ; to be decomposable by heat ; and, 
 dissolved in alcohol and diluted with water, 
 to form a pleasant saccharine liquor. 
 
 Muriate of alumina is scarcely crystalliz- 
 able, as on evaporation it assumes the state 
 of a thick jelly. It has an acid, styptic, acrid, 
 taste. It is extremely soluble in w r ater, and 
 deliquescent. Fire decomposes it. It may 
 be prepared by directly combining the muri- 
 atic acid with alumina, but the acid always 
 remains in excess. 
 
 The muriate of zircon crystallizes in small 
 needles, which are very soluble, attract mois- 
 ture, and lose their transparency in the air. 
 It has an austere taste, with somewhat of 
 acrimony. It is decomposable by heat. The 
 gallic acid precipitates from its solution, if it 
 be free from iron, a white powder. Carbo- 
 nate of ammonia, if added in excess, redis- 
 solves the precipitate it had before thrown 
 down. 
 
 Muriate of yttria does not crystallize w hen 
 evaporated, but forms a jelly : it dries with 
 difficulty, and deliquesces. 
 
 Fourcroy observes, that when siliceous 
 stones, previously fused with potash, are 
 treated with muriatic acid, a limpid solution 
 is formed, which may be reduced to a trans- 
 parent jelly by slow evaporation. But a boil- 
 ing heat decomposes the siliceous muriate, 
 and the earth is deposited. The solution is 
 ahvays acid. 
 
 * Acid (Muriatic, Oxygenated). See 
 Chlorine.* 
 
 * Acid (Muriatic, Oxygenized). This 
 
A Cl 
 
 supposed acid was lately described by M. 
 Thenard. He saturated common muriatic 
 acid of moderate strength with deutoxide of 
 barium, reduced into a soft paste by tritura- 
 tion with water. He then precipitated the 
 barytes from the liquid, by adding the requi- 
 site quantity of sulphuric acid. He next 
 took this oxygenized muriatic acid, and treat- 
 ed it with deutoxide of barium and sulphuric 
 acid, to oxygenate it anew. In this way he 
 charged it with oxygen as often as 15 times. 
 He thus obtained a liquid acid which con- 
 tained 32 times its volume of oxygen at the 
 temperature of 68° Fahr. and at the ordi- 
 nary atmospherical pressure, and only 4\ 
 times its volume of muriatic acid, which 
 gives about 28 equivalent primes of oxygen 
 to one of muriatic acid. For the ratio of 
 oxygen to the acid, by weight, is 1. to 4.6 ; 
 but by measure the ratio will be as these two 
 numbers respectively divided by the specific 
 gravity of the gases, or as to 
 
 which by reduction makes nearly one volume 
 of oxygen, equivalent to four of muriatic 
 acid. Now, the oxygen in the above result, 
 instead of being l-4th of the volume of the 
 acid gas, was seven times greater, whence 
 we derive the number 28. Still more oxy- 
 gen may however be added. On putting the 
 above oxygenized acid in contact with sul- 
 phate of silver, an insoluble chloride of this 
 metal subsides, and the liquid is oxygenized 
 sulphuric acid. When this is passed through 
 the filter, muriatic acid is added to it, but in 
 smaller quantity than existed in the original 
 oxygenized acid. A quantity of barytes, just 
 sufficient to precipitate the sulphuric acid, is 
 then added. Instantly the oxygen, leaving 
 the sulphuric acid to unite with the muriatic 
 acid, brings that acid to the highest point of 
 oxygenation. Thus we see that we can 
 transfer the whole of the oxygen from one 
 of these acids to the other ; and on a little 
 reflection it will be evident, that to obtain 
 sulphuric acid in the highest degree of oxy- 
 genation, it will be merely necessary to pour 
 barytes water into oxygenated sulphuric acid, 
 so as to precipitate only a part of the acid. 
 
 All these operations, with a little practice, 
 may be performed without the least diffi- 
 culty. By combining the two methods just 
 described, M. Thenard found that he could 
 obtain oxygenized muriatic acid, containing 
 nearly 1 6 times as many volumes of oxygen 
 as of muriatic acid, which represents about 
 64 equivalent primes of the former to one of 
 the latter. This oxygenized acid leaves no 
 residuum when evaporated. It is a very 
 acid, colourless liquid, almost destitute of 
 smell, and powerfully reddens turnsole. 
 When boiled for some time, its oxygen is 
 expelled. It dissolves zinc without effer- 
 vescence. Its action on the oxide of silver 
 is curious. These two bodies occasion as 
 lively an effervescence as if an acid were 
 
 A Cl 
 
 poured upon a carbonate. Water and a 
 chloride are formed, while the oxygen is 
 evolved. This oxide enables us to deter- 
 mine the quantity of oxygen present in the 
 oxygenized acid. Pour mercury into a 
 graduated glass tube, leaving a small deter- 
 minate space, which must be filled with the 
 above acid, invert the tube in mercury, let 
 up oxide of silver diffused in water ; in- 
 stantly the oxygen is separated. 
 
 We ought, however, to regard this apparent 
 oxygenation of the acid, merely as the con- 
 version of a portion of its combined water 
 into deutoxide of hydrogen. The same ex- 
 planation may be extended to the other oxy- 
 genized acids of M. Thenard. See Water.* 
 
 * Acid (Chloric). We place this acid 
 after the muriatic acid, because it has chlo- 
 rine also for its base. It was first eliminat- 
 ed from the salts containing it by M. Gay 
 Lussac, and described by him in his admir- 
 able memoir on iodine, published in the 91st 
 volume of the Annales de Chimie. When a 
 current of chlorine is passed for some time 
 through a solution of barytic earth in warm 
 water, a substance called hyperoxymuriate of 
 barytes by its first discoverer, M. Chenevix, 
 is formed, as well as some common muriate. 
 The latter is separated, by boiling phosphate 
 of silver in the compound solution. The 
 former may then be obtained by evapora- 
 tion, in fine rhomboidal prisms. Into a di- 
 lute solution of this salt, M. Gay Lussac 
 poured weak sulphuric acid. Though he 
 added only a few drops of acid, not nearly 
 enough to saturate the barytes, the liquid be- 
 came sensibly acid, and not a bubble of oxy- 
 gen escaped. By continuing to add sulphu- 
 ric acid with caution, he succeeded in ob- 
 taining an acid liquid entirely free from sul- 
 phuric acid and barytes, and not precipitat- 
 ing nitrate of silver. It was chloric acid 
 dissolved in water. Its characters are the 
 following. 
 
 This acid has no sensible smell. Its solu- 
 tion in water is perfectly colourless. Its 
 taste is very acid, and it reddens litmus 
 without destroying the colour. It produces 
 no alteration on solution of indigo in sul- 
 phuric acid. Light does not decompose it. 
 It may be concentrated by a gentle heat, 
 without undergoing decomposition, or with- 
 out evaporating. It was kept a long time 
 exposed to the air without sensible diminu- 
 tion of its quantity. When concentrated, it 
 has something of an oily consistency. When 
 exposed to heat, it is partly decomposed into 
 oxygen and chlorine, and partly volatilized 
 without alteration. Muriatic acid decom- 
 poses it in the same way, at the common 
 temperature. Sulphurous acid, and sulphu- 
 retted hydrogen, have the same property ; 
 but nitric acid produces no change upon it. 
 Combined with ammonia, it forms a ful- 
 minating salt, formerly described by M. 
 
ACI 
 
 ACI 
 
 Chenevix. It does not precipitate any me- 
 tallic solution. It readily dissolves zinc, 
 disengaging hydrogen ; but it acts slowly 
 on mercury. It cannot be obtained in the 
 gaseous state. It is composed of 1 volume 
 chlorine 4" 2 *5 oxygen, or, by weight, of 
 100 chlorine -j- 1 1 1.70 oxygen, if we con- 
 sider the specific gravity of chlorine to be 
 2.4866. But if it be called 2.420, as M. 
 Gay Lussac does in his memoir, it will then 
 come out 100 chlorine 114.7 oxygen. 
 This last number is however too great, in 
 consequence of estimating the specific gra- 
 vity of oxygen 1.1111, while M. Gay Lus- 
 sac makes it 1.10359. Chloric acid is at 
 any rate a compound of 5 primes of oxy- 
 gen + 1 of chlorine = 5. + 4.43 by 
 Berzelius, or 5. -f- 4. 45 by Dr Ure’s esti- 
 mate of the atom of chlorine. 
 
 M. Vauquelin, in making phosphate of 
 silver act on the mixed saline solution above 
 described, tried to accelerate its action by 
 dissolving it previously in acetic acid. But on 
 evaporating the chlorate of barytes so obtain- 
 ed to dryness, and exposing about 30 grains 
 to a decomposing heat, a tremendous explo- 
 sion took place, which broke the furnace, 
 rent a thick platina crucible, and drove its 
 lid into the chimney, where it stuck. It was 
 the employment of acetic acid which occa- 
 sioned this accident, and therefore it ought 
 never to be used in this way. 
 
 To the preceding account of the properties 
 of chloric acid, M. Vauquelin has added the 
 following : Its taste is not only acid, but 
 astringent, and its odour, when concentrated, 
 is somewhat pungent. It differs from chlo- 
 rine, in not precipitating gelatine. When 
 paper stained with litmus is left for some 
 time in contact with it, the colour is destroy- 
 ed. Mixed with muriatic acid, water is 
 formed, and both acids are converted into 
 chlorine. Sulphurous acid is converted into 
 sulphuric, by taking oxygen from the chloric 
 acid, which is consequently converted into 
 chlorine. 
 
 Chloric acid combines with the bases, and 
 forms the chlorates, a set of salts formerly 
 known by the name of the hypcroxygenized 
 muriates. They may be formed either di- 
 rectly by saturating the alkali or earth with 
 the chloric acid, or by the old process of 
 transmitting chlorine through the solutions 
 of the bases, in Woolfe’s bottles. In this 
 case the water is decomposed. Its oxygen 
 unites to one portion of the chlorine, form- 
 ing chloric acid, while its hydrogen unites to 
 another portion of chlorine, forming muria- 
 tic acid ; and hence, chlorates and muriates 
 must be contemporaneously generated, and 
 must be afterwards separated by crystalliza- 
 tion, or peculiar methods. 
 
 I he chlorate of potash, or hyperoxymu- 
 riate, lias been long known. When exposed 
 to a red heat, 100 grains of this salt yield 
 
 38.8S of oxygen, and are converted into the 
 chloride of potassium, or the dry muriate. 
 This remainder of 61.12 grains consists of 
 32.19 potassium and 28.93 chlorine. But 
 32.19 potassium require 6.50 oxygen, to 
 form the potash which existed in the origi- 
 nal chlorate. Therefore, subtracting this 
 quantity from 38.88, we have 32.38 for the 
 oxygen combined with the chlorine, consti- 
 tuting 61.31 of chloric acid, to 38.69 of 
 potash. * 
 
 To its compounds we shall proceed, pre- 
 mising, that we are indebted to M. Chene- 
 vix for the first accurate description of the 
 chlorates, or hyperoxymuriates. 
 
 Chlorate, or hyperoxymuriate of potash, 
 may be procured by receiving chlorine, as it 
 is formed, into a solution of potash. When 
 the solution is saturated, it may be evapo- 
 rated gently, and the first crystals produced 
 will be the salt desired, this crystallizing be- 
 fore the simple muriate, which is produced 
 at the same time with it. Its crystals are in 
 shining hexa’edral laminae, or rhomboidal 
 plates. It is soluble in 17 parts of cold 
 water ; and, but very sparingly, in alcohol. 
 * Its taste is cooling, and rather unpleasant. 
 Its specific gravity is 2.0. 16 parts of water, 
 at 60°, dissolve one of it, and of boiling 
 water. The purest oxygen is extracted from 
 this salt, by exposing it to a gentle red heat. 
 One hundred grains yield about 115 cubic 
 inches of gas. It consists of 9.45 chloric 
 acid 5.95 potash = 15.4, which is the 
 prime equivalent of the salt. * It is not de- 
 composed by the direct rays of the sun. Sub- 
 jected to distillation in a coated retort, it first 
 fuses, and on increasing the heat, gives out 
 oxygen gas. It is incapable of discharging 
 vegetable colours ; but the addition of a lit- 
 tle sulphuric acid developes this property. So 
 likewise a few grains of it, added to an ounce 
 of muriatic acid, give it this property. It is 
 decomposed by the sulphuric and nitric acid. 
 If a few grains be dropped into strong sul- 
 phuric acid, an offensive smell is produced, 
 resembling that of a brick-kiln, mixed with 
 that of nitrous gas ; and if the quantity be 
 large enough, ail explosion will ensue. If 
 the vessel be deep, it will be filled with a 
 thick, heavy vapour, of a greenish yellow 
 colour, but not producing the symptoms of 
 catarrh, at least in so violent a degree as the 
 fumes of chlorine. Underneath this vapour 
 is a bright orange- coloured fluid. This va- 
 pour inllames alcohol, oil of turpentine, cam- 
 phor, resin, tallow, elastic gum, and some 
 other inflammable substances, if thrown into 
 it. If the sulphuric acid be poured upon the 
 salt, a violent decrepitation takes place, some- 
 times, though rarely, accompanied by a flash. 
 M. Chenevix attempted to disengage the 
 chloric acid from this salt, by adding sul- 
 phuric acid to it in a retort ; but almost as 
 soon as the fire was kindled ? an explosion 
 
ACI 
 
 AC1 
 
 took place, by which a French gentleman 
 present was severely wounded, and narrowly 
 escaped the loss of an eye. 
 
 1 he effects of this salt on inflammable 
 bodies are very powerful. Rub two grains 
 into powder in a mortar, add a grain of sul- 
 phur, mix them well by gentle trituration, 
 then collect the powder into a heap, and 
 press upon it suddenly and forcibly with the 
 pestle, aloud detonation will ensue. If the 
 mixture be wrapped in strong paper, and 
 struck with a hammer, the report will be 
 still louder. Five grains of the salt, mixed 
 in the same manner with two and a half of 
 charcoal, will be inflamed by strong tritura- 
 tion, especially if a grain or two of sulphur 
 be added, but without much noise. If a 
 little sugar be mixed with half its weight of 
 the chlorate, and a little strong sulphuric 
 acid poured on it, a sudden and vehement 
 inflammation will ensue ; but this experi- 
 ment requires caution, as well as the follow- 
 ing. To one grain of the powdered salt in 
 a mortar, add half a grain of phosphorus, it 
 will detonate, with a loud report, on the 
 gentlest trituration. In this experiment the 
 hand should be defended by a glove, and 
 great care should be taken that none of the 
 phosphorus get into the eyes. Phosphorus 
 may be inflamed by it under water, putting 
 into a wine glass one part of phosphorus and 
 two of the chlorate, nearly filling the glass 
 with water, and then pouring in through a 
 glass tube reaching to the bottom, three or 
 four parts of sulphuric acid. This experi- 
 ment, too, is very hazardous to the eyes. If 
 olive or linseed oil be taken instead of phos- 
 phorus, it may be inflamed by similar means 
 on the surface of the water. This salt should 
 not be kept mixed with sulphur, or perhaps 
 any inflammable substance, as in tins state 
 it has been known to detonate spontaneous- 
 ly. As it is the common effect of mixtures 
 of this salt with inflammable substances of 
 every kind, to take fire on being projected 
 into the stronger acids, M. Chenevix tried 
 the experiment with it mixed with diamond 
 powder in various proportions, but without 
 success. ' 
 
 Chlorate of soda may bo prepared in the 
 same manner as the preceding, by substitut- 
 ing soda for potash ; but it is not easy to ob- 
 tain it separate, as it is nearly as soluble as 
 the muriate of soda, requiring only 5 parts 
 of cold water. * Vauquelin formed it, by 
 saturating chloric acid with soda ; 500 parts 
 of the dry carbonate yielding 1100 parts of 
 crystallized chlorate. It consists of 3.95 
 soda 4- 9.45 acid = 15.4, which is its 
 prime equivalent.* It crystallizes in square 
 plates, produces a sensation of cold in the 
 mouth, and a saline taste ; is slightly deli- 
 quescent, and in its other properties resem- 
 bles the chlorate of potash. 
 
 Barytes appears to be the next base in 
 
 order of affinity for this acid. The best me- 
 thod of forming it is to pour hot water on a 
 large quantity of this earth, and to pass a 
 current of chlorine through the liquid kept 
 warm, so that a fresh portion of barytes 
 may be taken up as the former is saturated. 
 This salt is soluble in about four parts of 
 cold water, and less of warm, and crystallizes 
 like the simple muriate. It may be obtain- 
 ed, however, by the agency of double affi- 
 nity ; for phosphate of silver boiled in the 
 solution will decompose the simple muriate, 
 and the muriate of silver and phosphate of 
 barytes being insoluble, will both fall down 
 and leave the chlorate in solution alone. The 
 phosphate of silver employed in this process 
 must be perfectly pure, and not the least 
 contaminated with copper. 
 
 The chlorate of strontites may be obtained 
 in the same manner. It is deliquescent, 
 melts immediately in the mouth and produces 
 cold ; is more soluble in alcohol than the 
 simple muriate, and crystallizes in needles. 
 
 The chlorate of lime, obtained in a similar 
 way, is extremely deliquescent, liquefies at a 
 low heat, is very soluble in alcohol, produces 
 much cold in solution, and has a sharp bitter 
 taste. 
 
 Chlorate of ammonia is formed by double 
 affinity, the carbonate of ammonia decom- 
 posing the earthy salts of this genus, giving 
 up its carbonic acid to their base, and com- 
 bining with their acid into chlorate of am- 
 monia, which may be obtained by evapora- 
 tion. It is very soluble both in water and 
 alcohol, and decomposed by a moderate heat. 
 
 The chlorate of magnesia much resembles 
 that of lime. 
 
 To obtain chlorate of alumina, INI. Chene- 
 vix put some alumina, precipitated from the 
 muriate, and well washed, Tut still moist, 
 into a Woolfe’s apparatus, and treated it as 
 the other earths. The alumina shortly dis- 
 appeared ; and on pouring sulphuric acid 
 into the liquor, a strong smell of chloric acid 
 was perceivable ; but on attempting to ob- 
 tain the salt pure by means of phosphate of 
 silver, the whole was decomposed, and no- 
 thing but chlorate of silver was found in the 
 solution. M. Chenevix adds, however, that 
 the aluminous salt appears to be very deli- 
 quescent, and soluble in alcohol. 
 
 * Acid (Perchloric). If about 3 parts of 
 sulphuric acid be poured on one of chlorate 
 of potash in a retort, and after the lirst vio- 
 lent action is over, heat be gradually applied, 
 to separate the deutoxide of chlorine, a saline 
 mass will remain, consisting of bisulphate of 
 potash and perchlorate of potash. By one 
 or two crystallizations, the latter salt may be 
 separated from the former. It is a neutral 
 salt, with a taste somewhat similar to the 
 common muriate of potash. It is very spar- 
 ingly soluble in cold water, since at 60°, 
 only - i is dissolved ; but in boiling water it 
 
 u 0 
 
ACI 
 
 ACI 
 
 
 1 
 
 F 
 
 I' 
 
 more soluble. Its crystals are elongated 
 octahedrons. It detonates feebly when tri- 
 turated with sulphur in a mortar. At the 
 heat of 412°, it is resolved into oxygen and 
 muriate of potash, in the proportion of 46 of 
 the former to 54 of the latter. Sulphuric 
 acid, at 280°, disengages the perchloric acid. 
 For these facts science is indebted to Count 
 Von Stadion. It seems to consist of 7 
 primes of oxygen, combined with 1 of chlo- 
 rine, or 7.0 -f 4.45. These curious dis- 
 coveries have been lately verified by Sir H. 
 Davy. The other perchlorates are not 
 known. 
 
 Before leaving the acids of chlorine, we 
 shall describe the ingenious method employed 
 by Mr Wheeler to procure chloric acid from 
 the chlorate of potash. He mixed a warm 
 solution of this salt with one of fluosilicic 
 acid. He kept the mixture moderately hot 
 for a few minutes, and to ensure the perfect 
 decomposition of the salt, added a slight ex- 
 cess of the acid. Aqueous solution of am- 
 monia will shew, by the separation of silica, 
 whether any of the fluosilicic acid be left 
 after the decomposition of the chlorate. Thus 
 we can effect its complete decomposition. 
 The mixture becomes turbid, and fluosilicate 
 of potash is precipitated abundantly in the 
 form of a gelatinous mass. The supernatant 
 liquid will then contain nothing but chloric 
 acid, contaminated with a small quantity of 
 fluosilicic. This may be removed by the 
 cautious addition of a small quantity of solu- 
 tion of chlorate. Or after filtration, the 
 whole acid may be neutralized by carbonate 
 of barytes, and the chlorate of that earth 
 being obtained in crystals, is employed to 
 procure the acid, as directed by M. Gay 
 Lussac.* 
 
 Acid (Nitric). The two principal con- 
 stituent parts of our atmosphere, when in 
 certain proportions, are capable, under parti- 
 cular circumstances, of combining chemi- 
 cally into one of the most powerful acids, the 
 nitric. If these gases be mixed in a proper 
 proportion in a glass tube about a line in 
 diameter, over mercury, and a series of elec- 
 tric shocks be passed through them for some 
 hours, they will form nitric acid ; or, if a so- 
 lution of potash be present with them, ni- 
 trate of potash will be obtained. The con- 
 stitution of this acid may be further proved, 
 analytically, by driving it through a red hot 
 porcelain tube, as thus it will be decomposed 
 into oxygen and nitrogen gases. For all 
 practical purposes, however, the nitric acid 
 is obtained from nitrate of potash, from which 
 it is expelled by sulphuric acid. 
 
 Three parts of pure nitrate of potash, 
 Coarsely powdered, are to be put into a glass 
 retort, with two of strong sulphuric acid. 
 ’I his must be cautiously added, taking care 
 to avoid the fumes that arise. Join to the 
 retort a tubulated receiver of large capacity, 
 
 with an adopter interposed, and lute the 
 junctures with glazier’s putty. In the 
 tubulure fix a glass tube, terminating in 
 another large receiver, in which is a small 
 quantity of water ; and, if you wish to col- 
 lect the gaseous products, let a bent glass 
 tube from this receiver communicate with a 
 pneumatic trough. Apply heat to the re- 
 ceiver by means of a sand bath. The first 
 product that passes into the receiver is gene- 
 rally red and fuming ; but the appearances 
 gradually diminish, till the acid comes over 
 pale, and even colourless, if the materials 
 used were clean. After this it again be- 
 comes more and more red and fuming, till 
 the end of the operation ; and the whole 
 minded together will be of a yellow or 
 orange colour. 
 
 * Empty the receiver, and again replace it. 
 Then introduce by a small funnel, very cau- 
 tiously, one part of boiling water in a slender 
 stream, and continue the distillation. A 
 small quantity of a weaker acid will thus be 
 obtained, which can be kept apart. The first 
 will have a specific gravity of about 1.500, if 
 the heat have been properly regulated, and if 
 the receiver was refrigerated by cold water or 
 ice. Acid of that density, amounting to 
 two-thirds of the weight of the nitre, may 
 thus be procured. But commonly the heat 
 is pushed too high, whence more or less of 
 the acid is decomposed, and its proportion of 
 water uniting to the remainder, reduces its 
 strength. It is not profitable to use a smaller 
 proportion of sulphuric acid, when a concen- 
 trated nitric is required. But when only a 
 dilute acid, called in commerce aquafortis , is 
 required, then less sulphuric acid will suf- 
 fice, provided a portion of water be added. 
 One hundred parts of good nitre, sixty of 
 strong sulphuric acid, and twenty of water, 
 form economical proportions. * 
 
 In the large way, and for the purposes of 
 the arts, extremely thick cast iron or earthen 
 retorts are employed, to which an earthen 
 head is adapted, and connected with a range 
 of proper condensers. The strength of the 
 acid too is varied, by putting more or less 
 water in the receivers. The nitric acid thus 
 made generally contains sulphuric acid, and 
 also muriatic, from the impurity of the nitrate 
 employed. If the former, a solution of nitrate 
 of barytes will occasion a white precipitate ; if 
 the latter, nitrate of silver will render it milky. 
 The sulphuric acid may be separated by a 
 second distillation from very pure nitre, equal 
 in weight to an eighth of that originally em- 
 ployed ; or by precipitating with nitrate of 
 barytes, decanting the clear liquid, and dis- 
 tilling it. The muriatic acid may be sepa- 
 rated by proceeding in the same way with 
 nitrate of silver, or with litharge, decanting 
 the clear liquor, and re-distilling it, leaving 
 an eighth or tenth part in the retort The 
 acid for the last process should lie condensed 
 
ACi 
 
 ACI 
 
 ai much as possible, and the re- distillation 
 conducted very slowly ; and if it be stopped 
 when half is come over, beaittiful crystals of 
 muriate of lead will be obtained on cooling 
 the remainder, if litharge be used, as M. 
 Steinacher informs us ; who also adds, that 
 the vessels should be made to fit tight by 
 grinding, as any lute is liable to contaminate 
 the product. 
 
 As this acid still holds in solution more or 
 less nitrous gas, it is not in fact nitric acid, 
 but a kind of nitrous : it is therefore neces- 
 sary to put it into a retort, to which a re- 
 ceiver is added, the two vessels not being 
 luted, and to apply a very gentle heat for se- 
 veral hours, changing the receiver as soon as 
 it is filled with red vapours. The nitrous 
 gas will thus be expelled, and the nitric acid 
 will remain in the retort as limpid and co- 
 lourless as water. It should be kept in a 
 bottle secluded from the light, otherwise it 
 will lose part of its oxygen. 
 
 What remains in the retort is a bisulphate 
 of potash, from which the superfluous acid 
 may be expelled by a pretty strong heat, and 
 the residuum, being dissolved and crystallized, 
 will be sulphate of potash. 
 
 As nitric acid in a fluid state is always 
 mixed with water, different attempts have 
 been made to ascertain its strength, or the 
 quantity of real acid contained in it. Mr 
 Kirwan supposed, that the nitrate of soda 
 contained the pure acid undiluted with wa- 
 ter, and thus calculated its strength from the 
 quantity requisite to saturate a given portion 
 of soda. Sir H. Davy more recently took 
 the acid in the form of gas as the standard, 
 and found how much of this is contained in 
 an acid of a given specific gravity in the li- 
 quid state. 
 
 *Mr Kirwan gave 68 as the quantity of real 
 acid in 100 of the liquid acid of specific gra- 
 vity 1.500 ; Sir H. Davy’s determination was 
 91 ; Dr Wollaston’s, as inferred from the 
 experiments of Mr 11. Philips, 75 ; and Mr 
 Dalton’s corrected result from Kirwan’s 
 table, w r as 68. In this state of discordance 
 Dr Ure performed a series of experiments, 
 with the view of determining the constitution 
 of liquid nitric acid, and published an account 
 of them, with some new tables, in the fourth 
 and sixth volumes of the Journal of Science 
 and the Arts. 
 
 From regular prisms of nitre, he procured 
 by slow r distillation, with concentrated oil of 
 vitriol, nitric acid ; which by the tests of ni- 
 trates of silver and of barytes, was found to 
 be pure. Only the first portion that came 
 over w'as employed for the experiments. It 
 was nearly colourless, and had a specific gra- 
 vity of 1.500. A re-distilled and colourless 
 nitric acid, prepared in London, was also 
 used for experiments of verification, in esti- 
 mating the quantity of dry acid in liquid 
 add of » known density. 
 
 The above acid of 1.500 being mixed in 
 numbered phials, with pure water, in the dif- 
 ferent proportions of 95 5, 90-|-10, 80 
 
 + 20, &c. he obtained, after due agitation, 
 and an interval of 24 hours, liquids whose 
 specific gravities, at 60° Fahrenheit, were 
 determined by means of an accurate balance, 
 with a narrow -necked glass globe of known 
 capacity. By considering the series of numbers 
 thus obtained, he discovered the geometrical 
 law which regulates them. The specific gra- 
 vity of dilute add, containing 10 parts in 
 the 100 of that whose density is 1.500, is 
 1.054. Taking this number as the root, its 
 successive powers will give us the successive 
 densities, at the terms of 20, 30, 40, Sec. per 
 cent. Thus 1.054 2 = l.lll is the specific 
 gravity corresponding to 20 of the strong 
 liquid acid -|- 80 w-ater ; 1.054 3 = 1.171 is 
 that for 30 per cent of strong acid ; 1.054+ 
 = 1.234 is the specific gravity at 40 per 
 cent. The specific gravities arc therefore a 
 series of numbers in geometrical progression, 
 corresponding to the terms of dilution, ano- 
 ther series in arithmetical progression, exact- 
 ly as he had shewn in the 7th number of the 
 Journal of Science with regard to sulphuric 
 acid. Hence if one term be given, the whole 
 series may be found. On uniting the strong 
 acid with water, a considerable condensation 
 of volume takes place. The maximum con- 
 densation occurs, when 58 of acid are mixed 
 with 42 of water. Above this point, the 
 curve of condensation has a contrary flexure ; 
 and therefore a small modification must be 
 made on the root 1.054, in order to obtain 
 with final accuracy, in the higher part of the 
 range, the numerical powers which represent 
 the specific gravities. The modification is 
 however very simple. To obtain the num- 
 ber for 50 per cent, the root is 1.053 ; and 
 for each decade up to 70, the root must be 
 diminished by 0.002. Thus for 60, it will 
 become 1.051, and for 70, 1.049. Above 
 this w^e shall obtain a precise correspondence 
 with experiment, up to 1.500 sp. gravity, if 
 for each successive decade we subtract 
 0.0025 from the last diminished root, before 
 raising it to the desired power, which repre- 
 sents the per centage of liquid acid. 
 
 It is established by the concurring experi- 
 ments of Sir H. Davy andM. Gay Lussac, that 
 dry nitric acid is a compound of 2^ volumes 
 of oxygen combined with 1 of nitrogen ; of 
 which the weights are 2.5 X 1.111 = 2.777 
 for the proportion of oxygen, and 0.9722 for 
 that of nitrogen ; and in 100 parts, of 73 j 
 of the former 26^ of the latter. But 
 nitrogen combines with several inferior pro- 
 portions of oxygen, which are all multiples 
 of its prime equivalent 1 .0 ; and the present 
 compound is exactly represented by making 
 1 prime of nitrogen = 1.75, and 5 of oxy- 
 gen = 5.0; whence the acid prime is the sum 
 of these two numbers, or 6.75. Now this 
 
ACI 
 
 i 
 
 ]{ 
 
 ;i‘ 
 
 ’ 
 
 91 
 
 l 
 
 V. 
 
 V 
 
 E 
 
 ii 
 
 N 
 
 
 ACI 
 
 result deduced from its constituents, coincides 
 perfectly with that derived from the quantity 
 in which this acid saturates definite quantities 
 of the salifiable bases, potash, soda, lime, &c. 
 There can be no doubt, therefore, that the 
 prime equivalent of the acid is 6.75 ; and as 
 little that it consists of 5 parts of oxygen and 
 1.75 of nitrogen. Possessed of these data, 
 we may perhaps see some reason why the 
 greatest condensation of volume, in diluting 
 strong liquid acid, should take place with 58 
 of it, and 42 of water. Since 100 parts of 
 acid of 1 .500 contain, by Dr Ure’s experi- 
 ments, 79.7 of dry acid, therefore acid of the 
 above dilution will contain 46 dry acid, and 
 54 water ; or reducing the numbers to prime 
 proportions, we have the ratio of 6.75 to 
 7.875, being that of one prime of real acid 
 to 7 primes of water. But we have seen that 
 the real acid prime, is made up of 1 of nitro- 
 gen associated by chemical affinity with 5 of 
 oxygen. Now imagine a figure, in which 
 the central prime of nitrogen is surrounded 
 by 5 of oxygen. To the upper and under 
 surface of the nitrogen let a prime of water 
 be attached ; and one also to each of the 
 primes of oxygen. We have thus the 7 
 
 TABLE of Nitric 
 
 primes distributed in the most compact and 
 symmetrical manner. By this hypothesis , we 
 can understand how the elements of acid and 
 water may have such a collocation and pro- 
 portion, as to give the utmost efficacy to 
 their reciprocal attractions, whence the maxi- 
 mum condensation will result. A striking 
 analogy will be found in the dilution of sul- 
 phuric acid. 
 
 If on 58 parts by weight of acid of 1.500, 
 we pour cautiously 42 of water in a graduat- 
 ed measure, of which the whole occupies 100 
 divisions, and then mix them intimately, the 
 temperature will rise from 60° to 140°, and 
 after cooling to 60° again, the volume will 
 be found only 92.65. No other proportion 
 of water and acid causes the evolution of so 
 much heat. When 90 parts of the strong 
 acid are united with 10 of water, 100 in vo- 
 lume become 97 ; and when 10 parts of the 
 same acid are combined with 90 of water, 
 the resulting volume is 98. It deserves no- 
 tice, that 80 of acid 20 water, and 50 of 
 acid -j- 70 water, each gives a dilute acid, 
 whose degree of condensation is the same, 
 namely, 100 measures become 94.8. 
 
 Acid, hy Dr Ure. 
 
 Specific 
 
 gravity 
 
 Liq. 
 Acid 
 in 100 
 
 Dry acid 
 ! in 100. 
 
 Specific 
 
 gravity 
 
 Liq. 
 Acid 
 in 100 
 
 Dry acid 
 
 in 100. 
 
 , Specific 
 gravity. 
 
 Liq. 
 Acid 
 in 100 
 
 Dryacic 
 in 100. 
 
 Specific 
 
 gravity 
 
 | Liq. 
 Acid 
 ’in IOC 
 
 Dryacid 
 in 100. 
 
 1 .5006 
 
 100 
 
 79.700 
 
 1.4189 
 
 75 
 
 59.775 
 
 1.2947 
 
 50 
 
 39.85C 
 
 1.1403 
 
 1 25 
 
 19.925 
 
 1.4 98C 
 
 99 
 
 78.903 
 
 1.4147 
 
 74 
 
 58.978 
 
 1.2887 
 
 49 
 
 39.053 
 
 1.1345 
 
 > 24 
 
 19.128 
 
 1 .4966 
 
 98 
 
 78.106 
 
 1.4107 
 
 75 
 
 58.181 
 
 1.2826 
 
 48 
 
 38.256 
 
 ■ 1. 1286 
 
 23 
 
 18.331 
 
 1.494C 
 
 97 
 
 77.309 
 
 1.4065 
 
 72 
 
 57.384 
 
 1.2765 
 
 47 
 
 37.459 
 
 1.1227 
 
 22 
 
 17.534 
 
 1.49 1C 
 
 96 
 
 76.512 
 
 1.4023 
 
 71 
 
 56.587 
 
 1.2705 
 
 46 
 
 36.662 
 
 1.1168 
 
 21 
 
 16.737 
 
 1.488C 
 
 95 
 
 75.715 
 
 1.3978 
 
 70 
 
 55.790 
 
 1.2644 
 
 45 
 
 35.865 
 
 1.1109 
 
 20 
 
 15.940 
 
 1.4850 
 
 94 
 
 74.918 
 
 1.3945 
 
 69 
 
 54.993 
 
 1.2583 
 
 44 
 
 35.068 
 
 1.1051 
 
 19 
 
 15.143 
 
 1.4820 
 
 93 
 
 74.121 
 
 1.3882 
 
 68 
 
 54.196 
 
 1.2523 
 
 43 
 
 34.271 
 
 1.0993 
 
 18 
 
 14.346 
 
 1.4790 
 
 92 
 
 73.324 
 
 1.3833 
 
 67 
 
 55.399 
 
 1.2462 
 
 42 
 
 33.474 
 
 1.0935 
 
 17 
 
 ! 13.54 9 
 
 1.4760 
 
 91 
 
 72.527 
 
 1.3783 
 
 66 
 
 52.602 
 
 1.2402 
 
 41 
 
 32.677 
 
 1.0878 
 
 16 
 
 12.752 
 
 1.4730 
 
 90 
 
 71.730 
 
 1.3732 
 
 65 
 
 51.805 
 
 1.2341 
 
 40 
 
 31.880 
 
 1.0821 
 
 15 
 
 1 1.955 
 
 1.4700 
 
 89 
 
 70.933 
 
 1.3681 
 
 64 
 
 51.068 
 
 1.2277 
 
 39 
 
 31.083 
 
 1.0764 
 
 14 
 
 11.158 
 
 1.4670 
 
 88 
 
 70.136 
 
 1.3630 
 
 65 
 
 50.21 1 
 
 1.2212 
 
 38 
 
 30.286 
 
 1.0708 
 
 13 
 
 10.361 
 
 1.4640 
 
 87 
 
 69.339 
 
 1.3579 
 
 62 
 
 49.414 
 
 1.2148 
 
 57 
 
 29.489 
 
 1.0651 
 
 12 
 
 9.564 
 
 1.4600 
 
 86 
 
 68.542 
 
 1.3529 
 
 61 
 
 48.617 
 
 1.2084 
 
 56 
 
 28.692 
 
 1.0595 
 
 11 
 
 8.1 Cl 
 
 1.4570 
 
 85 
 
 67.745 
 
 1.3477 
 
 60 
 
 47.820 
 
 1.2019 
 
 55 
 
 27.895 
 
 1.0540 
 
 10 
 
 7.970 
 
 1.4530 
 
 84 
 
 66.948 
 
 1 .3427 
 
 59 
 
 47.023 
 
 1.1958 
 
 54 
 
 27.098 
 
 .0485 
 
 9 
 
 7.173 
 
 1.4500 
 
 83 
 
 66.1 55 
 
 1.5376 
 
 58 
 
 46.226 
 
 1.1895 
 
 35 
 
 26.301 
 
 .0430 
 
 8 
 
 6.376 
 
 1.4460 
 
 82 
 
 65.354 
 
 1.3323) 
 
 57 
 
 45.429 
 
 1.1833 
 
 52 
 
 25.504 
 
 1.0375 
 
 7 
 
 5.579 
 
 1.4424 
 
 81 
 
 64.557 
 
 1.3270 
 
 56 
 
 14.632 1 
 
 1.1770 
 
 51 
 
 24.707 
 
 1.0320 
 
 6 
 
 4.782 
 
 1.4385 
 
 80 
 
 60.760 
 
 1.3216 
 
 55 
 
 15.835 j 
 
 1.1709 
 
 30 
 
 23.900 
 
 1.0267 
 
 5 
 
 3.985 
 
 1.4.546 
 
 79 
 
 62.963 
 
 1.3163 
 
 54 
 
 13.038 
 
 1.1648 
 
 29 
 
 23.113 
 
 1.0212 
 
 4 I 
 
 3.188 
 
 1.4506 
 
 78 
 
 62.166) 
 
 1.311 Oj 
 
 53 
 
 12.241 
 
 1.1587 
 
 28 i 
 
 22.3 1 6 
 
 1.0159 
 
 3 
 
 2.391 
 
 1.4269 
 
 77 
 
 6 1.3C 9 
 
 1 .3056: 
 
 52 < 
 
 1.444 
 
 1.1526 
 
 27 i 
 
 21.519 
 
 1.0106 
 
 9 
 
 1.594 
 
 .4228 
 
 76 
 
 50.572) 
 
 1 .3001 f 
 
 51 < 
 
 10.6 4 7(1 1.1 4 65 
 
 26 $ 
 
 20.722 
 
 1 .0053 
 
 1 1 
 
 0,797 
 
 Fhe column of dry acid shews the weight 
 which any salifiable base would gain, by 
 uniting with 100 parts of the liquid acid of 
 the corresponding specific gravity. But it 
 may be proper here to observe, that Sir H. 
 
 Davy, in extending his views relative to the 
 constitution of the dry muriates, to the nitrates, 
 has suggested, that the latter when dry may 
 be considered as consisting, not of a dry ni- 
 tric acid combined with the salifiable oxide, 
 
ACI 
 
 ACI 
 
 but of the oxygen and nitrogen of the nitric 
 acid with the metal itself in triple union. A 
 view of his reasoning will be found under 
 the article Salt. He regards liquid nitric 
 acid at its utmost density as a compound of 
 1 prime of hydrogen, 1 of nitrogen, and 
 6 of oxygen. * 
 
 The strongest acid that Mr Kirwan could 
 procure at 60° was 1.5543 ; but liouclle 
 professes to have obtained it of 1.583. 
 
 Nitric acid should be of the specific gra- 
 vity of 1.5, or a little more, and colourless. 
 
 *That of Mr Kirwan seems to have con- 
 sisted of one prime of real acid and one of 
 water, when the suitable corrections are 
 made ; but no common chemical use re- 
 quires it of such a strength. The following 
 table of boiling points has been given by Mr 
 Dalton. 
 
 Acid of sp. gr. 1.50 boils at 
 
 210° 
 
 1.45 
 
 240 
 
 1.42 
 
 218 
 
 1.40 
 
 247 
 
 1.35 
 
 242 
 
 1.30 
 
 236 
 
 1.20 
 
 226 
 
 1.15 
 
 219 
 
 At 1.42 specific gravity it distils unalter- 
 ed. Stronger acid than that becomes weak- 
 er, and weaker acid stronger, by boiling. 
 When the strong acid is cooled down to — 
 60°, it concretes, by slight agitation, into a 
 mass of the consistence of butter. 
 
 This acid is eminently corrosive, and 
 hence its old name of aquafortis. Its taste 
 is sour and acrid. It is a deadly poison 
 when introduced into the stomach in a con- 
 centrated state ; but when greatly diluted, it 
 may be swallowed without inconvenience. 
 It is often contaminated, through negligence 
 or fraud in the manufacturer, with sulphuric 
 and muriatic acids. Nitrate of lead detects 
 both, or nitrate of barytes may be employed 
 to determine the quantity of sulphuric acid, 
 and nitrate of silver that of the muriatic. 
 The latter proceeds from the crude nitre usu- 
 ally containing a quantity of common salt.* 
 
 When it is passed through a red hot por- 
 celain tube, it is resolved into oxygen and 
 nitrogen, in the proportion above stated. It 
 retains its oxygen with little force, so that it 
 is decomposed by all combustible bodies. 
 Drought into contact w ith hydrogen gas at 
 a high temperature, a violent detonation 
 ensues, so that this must not be done with- 
 out great caution. It inflames essential oils, 
 as those of turpentine and cloves, when sud- 
 
 Colour. 
 
 Real Acid 
 
 Pale yellow 
 
 90.5 
 
 Bright yellow’ 
 
 88.94 
 
 Dark orange 
 
 86.84 
 
 Light olive 
 
 86.0 
 
 Dark olive 
 
 85.4 
 
 Bright green 
 
 84.8 
 
 Blue green 
 
 84. G 
 
 denly poured on them ; but, to perform this 
 experiment with safety, the acid must be 
 poured out of a bottle tied to the end of a 
 long stick, otherwise the operator’s face and 
 eyes w ill be greatly endangered. If it be 
 poured on perfectly dry charcoal pow’der, it 
 excites combustion, with the emission of co- 
 pious fumes. By boiling it with sulphur it 
 is decomposed, and its oxygen, uniting with 
 the sulphur, forms sulphuric acid. Che- 
 mists in general agree, that it acts very 
 powerfully on almost all the metals ; but 
 Baume has asserted, that it will not dissolve 
 tin, and Dr Woodhouse of Pennsylvania af- 
 firms, that in a highly concentrated and pure 
 state it acts not at all on silver, copper, or 
 tin, though, with the addition of a little wa- 
 ter, its action on them is very powerful. 
 
 * Proust has ascertained, that acid having 
 the specific gravity 1.48, has no more ac- 
 tion on tin than on sand, while acid some- 
 what stronger or weaker acts furiously on 
 the metal. Now r , acid of 1.485, by Dr Lire’s 
 table, consists of one prime of real acid united 
 with two of water, constituting, it w'ould thus 
 appear, a peculiarly powerful combination. 
 
 Acid which takes up yVoo^ ls of its 
 weight of marble, freezes, according to Mr 
 Cavendish, at — 2°. When it can dissolve 
 
 r c i 
 
 PhOTT’ it requires to be cooled to — 4 1 °. 6 
 before congelation; and when so much dilut- 
 ed as to take up only j it congeals at 
 
 — 40°. 3. The first has a specific gravity of 
 1.330 nearly, and consists of 1 prime of 
 dry acid -j- 7 of water ; the second has a 
 specific gravity of 1.420, and contains ex- 
 actly one prime of dry acid -f- four of water; 
 while the third has a specific gravity of 1.21 5, 
 consisting of one prime of acid -}- 14 of 
 water. We perceive, that the liquid acid of 
 1.420, composed of 4 primes of water 
 one of dry acid, possesses the greatest power 
 of resisting the influence of temperature to 
 change its state. It requires the maximum 
 heat to boil it, when it distils unchanged ; and 
 the maximum cold to effect its congelation.* 
 
 It has already been observed, that the 
 nitric acid, when first distilled over, holds in 
 solution a portion of nitric oxide, which is 
 greater in proportion as the heat has been 
 urged tow'ard the end, and much increased 
 by even a small portion of inflammable mat- 
 ter, should any have been present The 
 colour of the acid, too, is affected by the 
 quantity of nitric oxide it holds, and Sir II. 
 Davy has given us the following table of 
 proportions answering to its different hues. 
 
 itric Oxide. 
 
 Water. 
 
 1.2 
 
 6.5 
 
 2.96 
 
 8.10 
 
 5.56 
 
 7.6 
 
 6.45 
 
 7.55 
 
 7.1 
 
 7.5 
 
 7.76 
 
 7.44 
 
 8. 
 
 7.4 
 
ACI 
 
 ACI 
 
 But these colours are not exact indications 
 of the state of the acid, for an addition of 
 water will change the colour into one lower 
 in the scale, so that a considerable portion of 
 water will change the dark orange to a blue 
 green. 
 
 The nitric acid is of considerable use in 
 the arts. It is employed for etching on cop- 
 per ; as a solvent of tin to form with that 
 metal a mordant for some of the finest dyes; 
 in metallurgy and assaying ; in various che- 
 mical processes, on account of the facility 
 with which it parts with oxygen and dissolves 
 metals ; in medicine as a tonic, and as a 
 substitute for mercurial preparations in si- 
 phylis and affections of the liver; as also in 
 form of vapour to destroy contagion. For 
 the purposes of the arts it is commonly used 
 in a diluted state, and contaminated with the 
 sulphuric and muriatic acids, by the name of 
 aquafortis. This is generally prepared by 
 mixing common nitre with an equal weight 
 of sulphate of iron, and half its weight of the 
 same sulphate calcined, and distilling the 
 mixture ; or by mixing nitre with twice its 
 weight of dry powdered clay, and distilling 
 in a reverberatory furnace. Two kinds are 
 found in the shops, one called double aqua- 
 fort is f which is about half the strength of 
 nitric acid ; the other simply aquafortis , 
 which is half the strength of the double. 
 
 A compound made by mixing two parts 
 of the nitric acid with one of muriatic, known 
 formerly by the name of aqua regia , and now 
 by that of nitro- muriatic acid , has the pro- 
 perty of dissolving gold and platina. On 
 mixing the two acids heat is given out, an 
 effervescence takes place, and the mixture 
 acquires an orange colour. This is likewise 
 made by adding gradually to an ounce of 
 powdered muriate of ammonia, four ounces 
 of double aquafortis, and keeping the mix- 
 ture in a sand-heat till the salt is dissolved ; 
 taking care to avoid the fumes, as the vessel 
 must be left open ; or by distilling nitric 
 acid with an equal weight, or rather more, of 
 common salt. 
 
 * On this subject we are indebted to Sir IT. 
 Davy for some excellent observations, pub- 
 lished by him in the first volume of the Jour- 
 nal of Science. If strong nitrous acid, sa- 
 turated with nitrous gas, be mixed with a 
 saturated solution of muriatic acid gas, no 
 other effect is produced than might be ex- 
 pected from the action of nitrous acid of the 
 same strength on an equal quantity of water ; 
 and the mixed acid so formed has no power 
 of action on gold or platina. Again, if mu- 
 riatic acid gas, and nitrous gas in equal vo- 
 lumes, be mixed together over mercury, and 
 half a volume of oxygen be added, the im- 
 mediate condensation will be no more than 
 might be expected from the formation of ni- 
 trous acid gas. And when this is decompos- 
 ed, or absorbed by the mercury, the muriatic 
 
 acid gas is found unaltered, mixed with a 
 certain portion of nitrous gas. 
 
 It appears then that nitrous acid, and mu- 
 riatic acid gas, have no chemical action on 
 each other. If colourless nitric acid, and 
 muriatic acid of commerce, be mixed toge- 
 ther, the mixture immediately becomes yel- 
 low, and gains the pow r er of dissolving gold 
 and platinum. If it be gently heated, pure 
 chlorine arises from it, and the colour be- 
 comes deeper. If the heat be longer con- 
 tinued, chlorine still rises, but mixed with 
 nitrous acid gas. When the process has been 
 very long continued till the colour becomes 
 very deep, no more chlorine can be procured, 
 and it loses its power of acting upon plati- 
 num and gold. It is now nitrous and mu- 
 riatic acid. It appears then from these ob- 
 servations, which have been very often re- 
 peated, that nitro- muriatic acid owes its pe- 
 culiar properties to a mutual decomposition 
 of the nitric and muriatic acids ; and that 
 water, chlorine, and nitrous acid gas, are the 
 results. Though nitrous gas and chlorine 
 have no action on each other when perfectly 
 dry, yet if water be present there is an im- 
 mediate decomposition, and nitrous acid and 
 muriatic acid are formed. 118 parts of 
 strong liquid nitric acid being decomposed in 
 this case, yield 67 of chlorine. Aqua regia 
 does not oxidize gold and platina. It mere- 
 ly causes their combination with chlorine. 
 
 A bath made of nitro-muriatic acid, dilut- 
 ed so much as to taste no sourer than vine- 
 gar, or of such a strength as to prick the 
 skin a little, after being exposed to it for 
 twenty minutes or half an hour, has been 
 introduced by Dr Scott of Bombay as a re- 
 medy in chronic syphilis, a variety of ulcers, 
 and diseases of the skin, chronic hepatitis, 
 bilious dispositions, general debility, and 
 languor. He considers every trial as quite 
 inconclusive where a ptyalism, some affection 
 of the gums, or some very evident constitu- 
 tional effect, has not arisen from it. The 
 internal use of the same acid has been re- 
 commended to be conjoined with that of the 
 partial or general bath.* 
 
 With the different bases the nitric acid 
 forms nitrates. 
 
 The nitrate of barytes, when perfectly 
 pure, is in regular octaedral crystals, though 
 it is sometimes obtained in small shining 
 scales. It may be prepared by uniting bary- 
 tes directly with nitric acid, or by decompos- 
 ing the carbonate or sulphuret of barytes 
 with this acid. Exposed to heat it decrepi- 
 tates, and at length gives out its acid, which 
 is decomposed ; but if the beat be urged too 
 far, the barytes is apt to vitrify with the earth 
 of the crucible. It is soluble in 12 parts of 
 cold, and 3 or 4 of boiling water. It is said 
 to exist in some mineral w aters. *It consists 
 of 6.7.5 acid -|- 9.75, or 9.7 base.* 
 
 The nitrate of potash is the salt well 
 
ACI 
 
 ACI 
 
 known by the name of nitre or saltpetre. It 
 is found ready formed in the East Indies, in 
 Spain, in the kingdom of Naples, and else- 
 where, in considerable quantities ‘ but nitrate 
 of lime is still more abundant. Far the 
 greater part of the nitrate made use of is 
 produced by a combination of circumstances 
 which tend to compose and condense nitric 
 acid. I his acid appears to be produced in 
 all situations, where animal matters are com- 
 pletely decomposed with access of air, and of 
 proper substances with which it can readily 
 combine. Grounds frequently trodden by 
 cattle and impregnated with their excrements, 
 or the walls of inhabited places where putrid 
 animal vapours abound, such as slaughter- 
 houses, drains, or the like, afford nitre by 
 long exposure to the air. Artificial nitre 
 beds are made by an attention to the circum- 
 stances in which this salt is produced by na- 
 ture. Dry ditches are dug, and covered 
 with sheds, open at the sides, to keep off the 
 Tain : these are filled with animal substances 
 — such as dung, or other excrements, w'ith 
 the remains of vegetables, and old mortar, or 
 other loose calcareous earth ; this substance 
 being found to be the best and most conve- 
 nient receptacle for the acid to combine 
 with. Occasional w atering, and turning up 
 from time to time, are necessary, to accele- 
 rate the process, and increase the surfaces to 
 which the air may apply ; but too much 
 moisture is hurtful. When a certain por- 
 tion of nitrate is formed, the process appears 
 to go on more quickly ; but a certain quan- 
 tity stops it altogether, and after this cessa- 
 tion the materials W’ill go on to furnish more, 
 if what is formed be extracted by lixiviation. 
 After a succession of many months, more or 
 less, according to the management of the 
 operation, in which the action of a regular 
 current of fresh air is of the greatest im- 
 portance, nitre is found in the mass. If the 
 beds contained much vegetable matter, a 
 considerable portion of the nitrous salt will 
 be common saltpetre ; but, if otherw ise, the 
 acid will, for the most part, be combined 
 with the calcareous earth. * It consists of 
 6.7 5 acid + 5 .95 potash.* 
 
 To extract the saltpetre from the mass of 
 earthy matter, a number of large casks are 
 prepared, w ith a cock at the bottom of each, 
 and a quantity of straw within, to prevent its 
 being stopped up. Into these the matter is 
 put, together w ith w ood-ashes, either strewed 
 at top, or added during the filling. Boiling 
 water is then poured on, and suffered to 
 stand for some time ; after w hich it is drawn 
 off, and other water added in the same man- 
 ner, as long as any saline matter can be thus 
 extracted. The weak brine is heated, and 
 passed through other tubs, until it becomes 
 of considerable strength. It is then carried 
 to the boiler, and contains nitre and other 
 salts ; the chief of which is common culinary 
 
 salt, and sometimes muriate of magnesia. 
 It is the property of nitre to be much more 
 soluble in hot than cold water ; but common 
 salt is very nearly as soluble in cold as in hot 
 w r ater. Whenever, therefore, the evapora- 
 tion is carried by boiling to a certain point, 
 much of the common salt wall fall to the 
 bottom, for want of water to hold it in solu- 
 tion, though the nitre will remain suspended 
 by virtue of the heat. The common salt 
 thus separated is taken out with a perforated 
 ladle, and a small quantity of the fluid is 
 cooled, from time to time, that its concentra- 
 tion may be known by the nitre which crys- 
 tallizes in it. When the fluid is sufficiently 
 evaporated, it is taken out and cooled, and 
 great part of the nitre separates in crystals ; 
 while the remaining common salt continues 
 dissolved, because equally soluble in cold and 
 in hot water. Subsequent evaporation of the 
 residue will separate more nitre in the same 
 manner. * By the suggestion of Lavoisier, a 
 much simpler plan w r as adopted ; reducing 
 the crude nitre to pow’der, and washing it 
 twice with water.* 
 
 This nitre, which is called nitre of the 
 first boiling, contains some common salt ; 
 from which it may be purified by solution in 
 a small quantity of water, and subsequent 
 evaporation ; for the crystals thus obtained 
 are much less contaminated w'ith common 
 salt than before ; because the proportion of 
 water is so much larger, with respect to the 
 small quantity contained by the nitre, that 
 very little of it will crystallize. For nice 
 purposes, the solution and crystallization of 
 nitre are repeated four times. The crystals 
 of nitre are usually of the form of six-sided 
 flattened prisms, with diedral summits. Its 
 taste is penetrating ; but the cold produced 
 by placing the salt to dissolve in the mouth 
 is such as to predominate over the real taste 
 at first. Seven parts of water dissolve two of 
 nitre, at the temperature of sixty degrees ; 
 but boiling water dissolves its own weight. 
 100 parts of alcohol, at a heat of 1 76°, dis- 
 solve only 2.9. 
 
 On being exposed to a gentle heat, nitre 
 fuses ; and in this state being poured into 
 moulds, so as to form little round cakes, or 
 balls, it is called sal prunella , or crystal mi- 
 neral. This at least is tho w r ay in which this 
 salt is now' usually prepared, conformably to 
 the directions of Boerhaave ; though in most 
 dispensatories a twenty-fourth part of sul- 
 phur was directed to be deflagrated on the 
 nitre before it was poured out. This salt 
 should not be left on the fire after it has en- 
 tered into fusion, otherwise it will be con- 
 verted into a nitrite of potash. If the heat 
 be increased to redness, the acid itself is de- 
 composed, and a considerable quantity of 
 tolerably pure oxygen gas is evolved, suc- 
 ceeded by nitrogen. 
 
 This salt powerfully promotes the com- 
 
A Cl 
 
 ACI 
 
 bastion of inflammable substances. Two or 
 three parts mixed with one of charcoal, and 
 set on fire, burn rapidly ; azote and carbonic 
 acid gas are given out, and a small portion 
 of the latter is retained by the alkaline resi- 
 duum, which was formerly called clyssus of 
 nitre . Three parts of nitre, two of subcar- 
 bonate of potash, and one of sulphur, mixed 
 together in a warm mortar, form th e fulmi- 
 nating powder; a small quantity of which, 
 laid on a fire-shovel, and held over the fire 
 till it begins to melt, explodes with a loud 
 sharp noise. Mixed with sulphur and char- 
 coal it forms gunpowder. See Gunpowder. 
 
 Three parts of nitre, one of sulphur, and 
 one of fine saw-dust, well mixed, constitute 
 what is called the powder of fusion. If a 
 bit of base copper be folded up and covered 
 with this powder in a walnut-shell, and the 
 powder be set on fire with a lighted paper, 
 it will detonate rapidly, and fuse the metal 
 into a globule of sulphuret, without burning 
 the shell. 
 
 If nitrate of potash be heated in a retort 
 with half its "weight of solid phosphoric or 
 boracic acid, as soon as this acid begins to 
 enter into fusion it combines with the pot- 
 ash, and the nitric acid is expelled, accompa- 
 nied with a small portion of oxygen gas and 
 nitric oxide. 
 
 Silex, alumina, and barytes, decompose 
 this salt in a high temperature by uniting 
 with its base. The alumina will effect this 
 even after it has been made into pottery. 
 
 The uses of nitre are various. Beside 
 those already indicated, it enters into the 
 composition of fluxes, and is extensively em- 
 ployed in metallurgy ; it serves to promote 
 the combustion of sulphur in fabricating its 
 acid ; it is used in the art of dyeing ; it is 
 added to common salt for preserving meat, 
 to which it gives a red hue ; it is an ingre- 
 dient in some frigorific mixtures ; and it is 
 prescribed in medicine, as cooling, febrifuge, 
 and diuretic ; and some have recommended 
 it mixed with vinegar as a very powerful 
 remedy for the sea scurvy. 
 
 Nitrate of soda, formerly called cubic or 
 quadrangular nitre , approaches in its pro- 
 perties to the nitrate of potash ; but differs 
 from it in being somewhat more soluble in 
 cold water, though less in hot, which takes 
 up little more than its own weight ; in being 
 inclined to attract moisture from the atmos- 
 phere ; and in crystallizing in rhombs, or 
 rhomboidal prisms. It may be prepared by 
 saturating soda with the nitric acid ; by pre- 
 cipitating nitric solutions of the metals, or of 
 the earths, except barytes, by soda ; by lixi- 
 viating and crystallizing the residuum of 
 common salt distilled with three-fourths its 
 weight of nitric acid ; or by saturating the 
 mother waters of nitre with soda instead of 
 potash. 
 
 7 his salt has been considered as useless- 
 
 but professor Proust says, that five parts of 
 it, with one of charcoal and one of sulphur, 
 will burn three times as long as common 
 powder, so as to form an economical com- 
 position for fire- works. * It consists of 6.75 
 acid ~|- 3. 95 soda. * 
 
 Nitrate of strontian may be obtained in 
 the same manner as that of barytes, with 
 which it agrees in the shape of its crystals, 
 and most of its properties. It is much more 
 soluble, however, requiring but four or five 
 parts of water according to Vauquelin, and 
 only an equal weight according to Mr Hen- 
 ry. Boiling water dissolves nearly twice as 
 much as cold. Applied to the wick of a 
 candle, or added to burning alcohol, it gives 
 a deep red colour to the flame. On this ac- 
 count it may be useful, perhaps, in the art of 
 pyrotechny. *It consists of 6.75 acid -|- 6.5 
 strontites. * 
 
 Nitrate of lime, the calcareous nitre of 
 older writers, abounds in the mortar of old 
 buildings, particularly those that have been 
 much exposed to animal effluvia, or pro- 
 cesses in which azote is set free. Hence it 
 abounds in nitre beds, as w^as observed when 
 treating of the nitrate of potash. It may 
 also be prepared artificially, by pouring dilute 
 nitric acid on carbonate of lime. If the so- 
 lution be boiled down to a sirupy consist- 
 ence, and exposed in a cool place, it crystal- 
 lizes in long prisms, resembling bundles of 
 needles diverging from a centre. These are 
 soluble, according to Henry, in an equal 
 weight of boiling water, and tw'ice their 
 w r eight of cold ; soon deliquesce on exposure 
 to the air, and are decomposed at a red heat. 
 Fourcroy says, that cold water dissolves four 
 times its weight, and that its owm water of 
 crystallization is sufficient to dissolve it at a 
 boiling heat. It is likewise soluble in less 
 than its weight of alcohol. By evaporating 
 the aqueous solution to dryness, continuing 
 the heat till the nitrate fuses, keeping it in 
 this state five or ten minutes, and then pour- 
 ing it into an iron pot previously heated, we 
 obtain Baldwin s phosphorus. This, which 
 is perhaps more properly nitrite of lime , be- 
 ing broken to pieces, and kept in a phial 
 closely stopped, will emit a beautiful white 
 light in the dark, after having been exposed 
 some time to the rays of the sun. At pre- 
 sent no use is made of this salt, except for 
 drying some of the gases by attracting their 
 moisture ; but it might be employed instead 
 of the nitrate of potash for manufacturing 
 aquafortis. 
 
 The nitrate of ammonia possesses the pro- 
 perty of exploding, and being totally decom- 
 posed, at the temperature of 600° ; whence 
 it acquired the name of nitrum Jlammans. 
 The readiest mode of preparing it is by add- 
 ing carbonate of ammonia to dilute nitric 
 acid till saturation takes place. If this so- 
 lution be evaporated in a heat between 70° 
 
AC I 
 
 ACI 
 
 1 00 Oleic acid of human fat 
 Saturate Barytes Strontian Lead 
 
 26.00 19.41 82.48 
 
 100 Oleic acid of sheep fat 
 
 26.77 19.38 81.81 
 
 100 Oleic acid of ox fat 
 
 28.93 19.41 81.81 
 
 1 00 Oleic acid of goose fat 
 26.77 19.38 81.34 
 
 100 Oleic acid of hog fat 
 
 27.00 29.38 81.80 
 
 Oleic acid is an oily fluid without taste 
 and smell. Its specific gravity is 0.914. It 
 is generally soluble in its own weight of 
 boiling alcohol, of the specific gravity of 
 0.7952; but some of the varieties are still 
 more soluble. 100 of the oleic acid satu- 
 rate 16.58 of potash, 10.11 of soda, 7.52 of 
 magnesia, M.83 of zinc, and 15.93 peroxide 
 of copper. M. ChevreuPs experiments have 
 finally induced him to adopt the quantities 
 of 100 acid to 27 barytes, as the most cor- 
 rect ; whence calling barytes 9.75, we have 
 the equivalent prime of oleic acid = 56.0.* 
 Acid (Oxalic). This acid, which a- 
 bounds in wood sorrel, and which, combin- 
 ed with a small portion of potash, as it exists 
 in that plant, has been sold under the name 
 of salt of lemons, to be used as a substitute 
 for the juice of that fruit, particularly for 
 discharging ink spots and iron-moulds, was 
 long supposed to be analogous to that of tar- 
 tar. In the year 1776, however, Bergman 
 discovered, that a powerful acid might be ex- 
 tracted from sugar by means of the nitric ; 
 and a few years afterwards Scheele found 
 this to be identical with the acid existing na- 
 turally in sorrel. Hence the acid began to 
 be distinguished by the name of saccharine , 
 but has since been known in the new nomen- 
 clature by that of oxalic. 
 
 Scheele extracted this acid from the salt 
 of sorrel, or acidulous oxalate of potash, as it 
 exists in the juice of that plant, by saturating 
 it with ammonia, when it becomes a very 
 soluble triple salt, and adding to the solution 
 nitrate of barytes dissolved in water. Hav- 
 ing well washed the oxalate of barytes, which 
 is precipitated, he dissolved it in boiling 
 water, and precipitated its base by sulphuric 
 acid. To ascertain that no sulphuric acid 
 remained in the supernatant liquor, he added 
 a little of a boiling solution of oxalate of 
 barytes till no precipitate took place, and 
 then filtered the liquor, which contained no- 
 thing but pure oxalic acid, which lie crystal- 
 lized by evaporation and cooling. 
 
 It may be obtained, however, much more 
 readily and economically from sugar in the 
 following way : To six ounces of nitric acid 
 in a stoppered retort, to which a large receiver 
 is luted, add, by degrees, one ounce of lump 
 sugar coarsely powdered. A gentle heat 
 may be applied during the solution, and ni- 
 
 tric oxide will be evolved in abundance- 
 When the whole of the sugar is dissolved, 
 distil off a part of the acid, till what remains 
 in the retort has a syrupy consistence, and 
 this will form regular crystals, amounting to 
 58 parts from 100 of sugar. These crystals 
 must be dissolved in water, re- crystallized, and 
 dried on blotting paper. 
 
 A variety of other substances afford the 
 oxalic acid when treated by distillation with 
 the nitric. Bergman procured it from honey, 
 gum arabic, alcohol, and the calculous con- 
 cretions in the kidneys and bladders of ani- 
 mals. Scheele and Hermbstadt from sugar 
 of milk. Scheele from a sweet matter con- 
 tained in fat oils, and also from the uncrys- 
 tallizable part of the juice of lemons. Hermb- 
 stadt from the acid of cherries, and the acid 
 of tartar. Goetling from beech wood. Kohl 
 from the residuum in the distillation of ar- 
 dent spirits. Westrumb not only from the 
 crystallized acids of currants, cherries, citrons, 
 raspberries, but also from the saccharine mat- 
 ter of these fruits, and from the unerystal- 
 lizable parts of the acid juices. Hoffmann 
 from the juice of the barberry ; and Berthol- 
 let from silk, hair, tendons, wool ; also from 
 other animal substances, especially from the 
 coagulum of blood, whites of eggs, and like- 
 wise from the amylaceous and glutinous parts 
 of flour. M. Berthollet observes, that the 
 quantity of the oxalic acid obtained by treat- 
 ing wool with nitric acid was very consider- 
 able, being above half the weight of the wool 
 employed. He mentions a difference which 
 he observed between animal and vegetable 
 substances thus treated with nitric acid, 
 namely, that the former yielded, beside am- 
 monia, a large quantity of an oil which the 
 nitric acid could not decompose ; whereas 
 the oily parts of vegetables were totally de- 
 stroyed by the action of this acid : and he 
 remarks, that in this instance the glutinous 
 part of flour resembled animal substances, 
 whereas the amylaceous part of the flour re- 
 tained its vegetable properties. He further 
 remarks, that the quantity of oxalic acid 
 furnished by vegetable matters thus treated 
 is proportionable to their nutritive quality, 
 and particularly that, from cotton, he could 
 not obtain any sensible quantity. Deyeux, 
 having cut with scissars the hairs of the chick 
 pea, found they gave out an acid liquor, 
 which, on examination, proved to be an 
 aqueous solution of pure oxalic acid. Proust 
 and other chemists had before observed, that 
 the shoes of persons walking through a field 
 of chick pease were corroded. 
 
 Oxalic acid crystallizes in quadrilateral 
 prisms, the sides of which are alternately 
 broad and narrow, and summits diedral ; or, 
 if crystallized rapidly, in small irregular 
 needles. They are efflorescent in dry air, 
 but attract a little humidity if it be damp ; 
 are soluble in one part of hot and two of 
 
ACI 
 
 ACI 
 
 cold water ; and are decomposable by a red 
 heat, leaving a small quantity of coaly resi- 
 duum. — 100 parts of alcohol take up near 
 56 at a boiling heat, but not above 40 cold. 
 Their acidity is so great, that when dissolved 
 in 3600 times their weight of water, the so- 
 lution reddens litmus paper, and is percepti- 
 bly acid to the taste. 
 
 The oxalic acid is a good test for detecting 
 lime, which it separates from all the other 
 acids, unless they are present in excess. It 
 has likewise a greater affinity for lime than 
 for any other of the bases, and forms with it 
 a pulverulent insoluble salt, not decomposa- 
 ble except by fire, and turning syrup of vio- 
 lets green. 
 
 * From the oxalate of lead, Berzelius infers 
 its prime equivalent to be 4.552, and by 
 igneous decomposition he finds it resolved 
 into 66. 534 oxygen, 33.222 carbon, and 
 0.244 hydrogen. The quantity of the latter, 
 when reduced to primitive ratios, gives only, 
 as Dr Thomson admits, 1-1 2th of an atom 
 of hydrogen, which makes this analysis of 
 Berzelius and the Atomic theory incompati- 
 ble. Since Berzelius published his analysis, 
 oxalic acid has been made the subject of 
 some ingenious remarks by Dobereiner, in 
 the 16th vol. of Schweigger’s Journal. We 
 see that the carbon and oxygen are to each 
 other in the simple ratio of 1 to 2 ; or re- 
 ferred to their prime equivalent, as 2 of car- 
 bon = 1.5, to 3 of oxygen == 3.0. This 
 proportion is what would result from a prime 
 of carbonic acid = C + 2- O, combined with 
 one of carbonic oxide = C -j- O. C being 
 carbon, and O oxygen. The sum of the 
 above weights gives 4.5 for the prime equi- 
 valent of oxalic acid, disregarding hydrogen, 
 which constitutes but l-37th of the whole, 
 and may possibly be referred to the imper- 
 fect desiccation of the oxalate of lead sub- 
 jected to analysis. Oxalic acid acts as a 
 violent poison when swallowed in the quan- 
 tity of 2 or 3 drachms ; and several fatal ac- 
 cidents have lately occurred in London, in 
 consequence of its being improperly sold in- 
 stead of Epsom salts. Its vulgar name of 
 salts, under which the acid is bought for the 
 purpose of whitening boot-tops, occasions 
 these lamentable mistakes. But the power- 
 fully acid taste of the latter substance, joined 
 to its prismatic or needle- formed crystalliza- 
 tion, are sufficient to distinguish it from 
 every thing else. The immediate rejection 
 from the stomach of this acid, by an emetic, 
 aided by copious draughts of warm water 
 containing bicarbonate of potash, or soda, 
 chalk, or carbonate of magnesia, are the pro- 
 per remedies.* 
 
 With barytes it forms an insoluble salt ; 
 but this salt will dissolve in water acidu- 
 lated with oxalic acid, and afford angular 
 crystals. If, however, we attempt to dis- 
 solve these crystals in boiling water, the 
 
 excess of acid will unite with the water, and 
 leave the oxalate, which will be precipi- 
 tated. 
 
 The oxalate of strontian too is a nearly 
 insoluble compound. 
 
 Oxala(e of magnesia too is insoluble, un- 
 less the acid be in excess. 
 
 The oxalate of potash exists in two states, 
 that of a neutral salt, and that of an acidule. 
 The latter is generally obtained from the 
 juice of the leaves of the oxalis acetosella , 
 wood sorrel, or rumex acetosa, common sor- 
 rel. The expressed juice, being diluted with 
 water, should be set by for a few days, till 
 the feculent parts have subsided, and the su- 
 pernatant fluid is become clear ; or it may 
 be clarified, when expressed, with the whites 
 of eggs. It is then to be strained off 1 , eva- 
 porated to a pellicle, and set in a cool place 
 to crystallize. The first product of crystals 
 being taken out, the liquor may be further 
 evaporated, and crystallized ; and the same 
 process repeated till no more can be obtain* 
 ed. In this way Schlereth informs us about 
 nine drachms of crystals may be obtained 
 from two pounds of juice, which are gene- 
 rally afforded by ten pounds of wood sorrel. 
 Savary, however, says, that ten parts of wood 
 sorrel in full vegetation yield five parts of 
 juice, which give little more than a two-hun- 
 dredth of tolerably pure salt. He boiled 
 down the juice, however, in the first instance, 
 without clarifying it; and w^as obliged re- 
 peatedly to dissolve and re-crystallize the salt 
 to obtain it white. 
 
 This salt is in small, white, needly, or la- 
 mellar crystals, not alterable in the air. It 
 unites with barytes, magnesia, soda, ammo- 
 nia, and most of the metallic oxides, into 
 triple salts. Yet its solution precipitates the 
 nitric solutions of mercury and silver in the 
 state of insoluble oxalate of these metals, the 
 nitric acid in this case combining with the 
 potash. It attacks iron, lead, tin, zinc, and 
 antimony. 
 
 This salt, beside its use in taking out ink 
 spots, and as a test of lime, forms with sugar 
 and water a pleasant cooling beverage ; and 
 according to Berthollet, it possesses consi- 
 derable powers as an antiseptic. 
 
 The neutral oxalate of potash is very so- 
 luble, and assumes a gelatinous form, but 
 may be brought to crystallize in hexaedral 
 prisms with diedral summits, by adding more 
 potash to the liquor than is sufficient to satu- 
 rate the acid. 
 
 Oxalate of soda likewise exists in two dif- 
 ferent states, those of an acidulous and a neu- 
 tral salt, which in their properties are analo- 
 gous to those of potash. 
 
 The acidulous oxalate of ammonia is crys- 
 tallizable, not very soluble, and capable, like 
 the preceding acidules, of combining with 
 other bases, so as to form triple salts. But 
 il the acid be saturated with ampionia, we 
 
ACI 
 
 AC1 
 
 obtain a neutral oxalate, which on evapora- 
 tion yields very fine crystals in tetraedral 
 prisms with diedral summits, one of the 
 planes of which cuts oft* three sides of the 
 prism. Ihis salt is decomposable by fire, 
 which raises from it carbonate of ammonia, 
 and leaves only some slight traces of a coaly 
 residuum. Lime, barytes, and strontian unite 
 with its acid, and the ammonia flies off in the 
 form of gas. 
 
 The oxalic acid readily dissolves alumina, 
 and the solution gives on evaporation a yel- 
 lowish transparent mass, sweet and a little 
 astringent to the taste, deliquescent, and red- 
 dening tincture of litmus, but not syrup of 
 violets. This salt swells up in the fire, loses 
 its acid, and leaves the alumina a little co- 
 loured. 
 
 * The composition of the different oxalates 
 may be ascertained by considering the neu- 
 tral salts as consisting of one prime of acid 
 = 4.552 to 1 of base, and the binoxylate 
 of potash of 2 of acid to 1 of base, as w as 
 first proved by Dr Wollaston. But this emi- 
 nent philosopher has further shewn, that ox- 
 alic acid is capable of combining in four pro- 
 portions with the oxides, whence result neu- 
 tral oxalates, suboxalates, acidulous oxalates, 
 and acid oxalates. The neutral contain 
 twice as much acid as the suboxalates ; one- 
 half of the quantity of acid in the acidulous 
 oxalates ; and one-quarter of that in the acid 
 oxalates.* 
 
 Acid (Perlate). This name was given 
 by Bergman to the acidulous phosphate of 
 soda, flaupt having called the phosphate of 
 soda sal mirabile perlatum. 
 
 Acid (Phosphoric). The base of this 
 acid, or the acid itself, abounds in the mine- 
 ral, vegetable, and animal kingdoms. In 
 the mineral kingdom it is found in combina- 
 tion with lead, in the green lead ore ; w-ith 
 iron, in the bog ores which afford cold short 
 iron ; and more especially with calcareous 
 earth in several kinds of stone. Whole 
 mountains in the province of Estremadura 
 in Spain are composed of this combination 
 of phosphoric acid and lime. Mr Bowles 
 affirms, that the stone is whitish and taste- 
 less, and affords a blue flame without smell 
 when thrown upon burning coals. Mr Proust 
 describes it as a dense stone, not hard enough 
 to strike fire with steel ; and says that it is 
 found in strata, which always lie horizontally 
 upon quartz, and which are intersected with 
 veins of quartz. When this stone is scat- 
 tered upon burning coals, it does not de- 
 crepitate, but burns with a beautiful green 
 light, which lasts a considerable time. It 
 melts into a white enamel by the blow- 
 pipe ; is soluble with heat, and some effer- 
 vescence in the nitric acid, and forms sul- 
 phate of lime w ith the sulphuric acid, while 
 the phosphoric acid is set at liberty in the fluid. 
 
 The vegetable kingdom abounds with 
 
 phosphorus, or its acid. It is principally 
 found in plants that grow in marshy places, 
 in turf, and several species of the white 
 W’oods. Various seeds, potatoes, agaric, soot, 
 and charcoal afford phosphoric acid,f by ab- 
 stracting the nitric acid from them, and lixi- 
 viating the residue. The lixivium contains 
 the phosphoric acid, which may either be 
 saturated w'ith lime by the addition of lime 
 water, in which case it forms a solid com- 
 pound ; or it may be tried by examination of 
 its leading properties by other chemical me- 
 thods. 
 
 In the animal kingdom it is found in al- 
 most every part of the bodies of animals 
 which are not considerably volatile. There 
 is not, in all probability, any part of these 
 organized beings which is free from it. It 
 has been obtained from blood, flesh, both of 
 land and water animals; from cheese; and 
 it exists in large quantities in bones, com- 
 bined with calcareous earth. Urine contains 
 it, not only in a disengaged state, but also 
 combined with ammonia, soda, and lime. It 
 tv as by the evaporation and distillation of 
 this excrementitious fluid with charcoal that 
 phosphorus was first made ; the charcoal de- 
 composing the disengaged acid and the 
 ammoniacal salt. (See Phosfhorus). But 
 it is more cheaply obtained by the process 
 of Scheele, from bones, by the application of 
 nn acid to their earthy residue after calcination. 
 
 In this process the sulphuric acid appears 
 to be the most convenient, because it forms 
 a nearly insoluble compound with the lime 
 of the bones. Bones of beef, mutton, or 
 veal, being calcined to wffiiteness in an open 
 fire, lose almost half of their weight. This 
 must be pounded, and sifted, or the trouble 
 may be spared by buying the powder that is 
 sold to make cupels for the assayers, and is, 
 in fact, the powder of burned bones ready 
 sifted. To three pounds of the powder there 
 may be added about two pounds of concen- 
 trated sulphuric acid. Four or five pounds 
 of water must be aftemard added to assist 
 the action of the acid ; and during the whole 
 process the operator must remember to place 
 himself and his vessels so that the fumes 
 may be blown from him. The whole may 
 be then left on a gentle sand bath for twelve 
 hours or more, taking care to supply the loss 
 of water which happens by evaporation. 
 The next day a large quantity of water must 
 be added, the whole strained through a sieve, 
 and the residual matter, which is sulphate of 
 lime, must be edulcorated by repeated affu- 
 sions of hot water, till it passes tasteless. 
 
 + To thfs Prof. Bartholdi ascribes two accidents at 
 the powder-mills at Essone, where spontaneous com- 
 bustion appeared to have taken place in one instance 
 in the charcoal store-room, in the other in the box 
 into which the charcoal was sifted ; as well as three 
 successive explosions at the powder-mills ef Vosges. 
 This certainly merits the attention of gunpowder 
 manufacturers, 
 
AC1 
 
 A Cl 
 
 The waters contain phosphoric acid nearly 
 free from lime, and by evaporation, first in 
 glazed earthen, and then in glass vessels, or 
 rather in vessels of platina or .silver, for the 
 hot acid acts upon glass, afford the acid in a 
 concentrated state, which, by the force ot a 
 strong heat in a crucible, may be made to 
 acquire the form of a transparent consistent 
 glass, though indeed it is usually of a milky, 
 opaque appearance. 
 
 For making phosphorus, it is not neces- 
 sary to evaporate the water further than to 
 bring it to the consistence of syrup ; and the 
 small portion of lime it contains is not an 
 impediment worth the trouble of removing, 
 as it affects the produce very little. But 
 when the acid is required in a purer state, it 
 is proper to add a quantity of carbonate of 
 ammonia, which, by double elective attrac- 
 tion, precipitates the lime that was held in 
 solution by the phosphoric acid. The fluid 
 being then evaporated, affords a crystallized 
 aramoniacal salt, which may be melted in a 
 silver vessel, as the acid acts upon glass or 
 earthen vessels. The ammonia is driven off 
 by the heat, and the acid acquires the form 
 of a compact glass as transparent as rock 
 crystal, acid to the taste, soluble in water, 
 and deliquescent in the air. 
 
 This acid is commonly pure, but never- 
 theless may contain a small quantity of soda, 
 originally existing in the bones, and not ca- 
 pable of being taken away by this process, 
 ingenious as it is. The only unequivocal 
 method of obtaining a pure acid appears to 
 consist in first converting it into phosphorus 
 by distillation of the materials with charcoal, 
 and then converting it again into acid by ra- 
 pid combustion, at a high temperature, either 
 in oxygen or atmospheric air, or some other 
 equivalent process. 
 
 Phosphorus may also be converted into 
 the acid state by treating it with nitric acid. 
 In this operation, a tubulated retort with a 
 ground stopper, must be half filled with ni- 
 tric acid, and a gentle heat applied. A small 
 piece of phosphorus being then introduced 
 through the tube will be dissolved with effer- 
 vescence, produced by the escape of a large 
 quantity of nitric oxide. The addition of 
 phosphorus must be continued until the last 
 piece remains undissolved. The fire being 
 then raised to drive over the remainder of 
 the nitric acid, the phosphoric acid will be 
 found in the retort, partly in the concrete and 
 partly in the liquid form. 
 
 Sulphuric acid produces nearly the same 
 effect as the nitric ; a large quantity of sul- 
 phurous acid flying off. But as it requires 
 a stronger heat to drive oft' the last portions 
 of this acid, it is not so w'ell adapted to the 
 purpose. 'Ihe liquid chlorine likewise acidi- 
 fies it. 
 
 When phosphorus is burned by a strong 
 heat, sufficient to cause it to flame rapidly, 
 
 it is almost perfectly converted into dry acid, 
 some of w hich is thrown up by the force of 
 the combustion, and the rest remains upon 
 the supporter. 
 
 This substance has also been acidified by 
 the direct application of oxygen gas passed 
 through hot water, in which the phosphorus 
 was liquefied or fused. 
 
 The general characters of phosphoric acid 
 are: 1. It is soluble in water in all propor- 
 tions, producing a specific gravity, which in- 
 creases as the quantity of acid is greater, but 
 does not exceed 2.687, which is that of the 
 glacial acid. 2. It produces heat when 
 mixed with water, though not very consi- 
 derable. 3. It has no smell when pure, and 
 its taste is sour, but not corrosive. 4. When 
 perfectly dry, it sublimes in close vessels ; 
 but loses this property by the addition of 
 water; in which circumstance it greatly dif- 
 fers from the boracic acid, which is fixed 
 when dry, but rises by the help of w’ater. 
 5. When considerably diluted w’ith water, 
 and evaporated, the aqueous vapour carries 
 up a small portion of the acid. 6. With 
 charcoal or inflammable matter, in a strong 
 heat, it loses its oxygen, and becomes con- 
 verted into phosphorus. 
 
 Phosphoric acid is'difficult of crystallizing. 
 
 Though the phosphoric acid is scarcely 
 corrosive, yet, w'hen concentrated, it acts up- 
 on oils, wdiich it discolours, and at length 
 blackens, producing heat, and a strong smell 
 like that of ether and oil of turpentine ; hut 
 does not form a true acid soap. It has most 
 effect on essential oils, less on drying oils, 
 and least of all on fat oils. Spirit of wane 
 and phosphoric acid have a w'eak action on 
 each other. Some heat is excited by this 
 mixture, and the product which comes over 
 in distillation of the mixture is strongly acid, 
 of a pungent arsenical smell, inflammable 
 with smoke, miscible in all proportions with 
 w’ater, precipitating silver and mercury from 
 their solutions, but not gold ; and although 
 not an ether, yet it seems to be an approxi- 
 mation to that kind of combination. 
 
 * From the syntheses of the phosphates of 
 soda, barytes, and lead, Berzelius deduces 
 the prime equivalent of phosphoric acid to be 
 4.5. But the experiments of Berzelius on 
 the synthesis of the acid itself, shew' it to be 
 a compound of about 100 phosphorus -f- 133 
 oxygen ; or of 2 oxygen -i- 1.5 phosphorus 
 = 3.5 for the prime equivalent of the acid. 
 Lavoisier’s synthesis gave 2 oxygen-)- 1.33 
 phosphorus. So did that of Sir II. Davy by 
 rapid combustion in oxygen gas, as publish- 
 ed in the Phil. Trans, for 1812. Dr Thom- 
 son, in his account of the improvements in 
 Physical Science, published in his Annals 
 for January 1817, says, “ It is quite clear 
 from these analyses (of Berzelius) that the 
 equivalent number for phosphoric acid is 4.5.” 
 M. Didong, in an elaborate paper published 
 
AC1 
 
 AC 1 
 
 in the third volume of the Memoires d’Ar- 
 Ciieil, gives as the result of* diversified experi- 
 ments, the proportions of 100 phosphorus to 
 125 oxygen ; or of 2 oxygen -j- 1.627 phos- 
 phorus = 3.627 for the acid equivalent. 
 
 In the Annals of Philosophy for April 
 1816, page 305, Dr Thomson gives the fol- 
 lowing statement : “ Prom this result it fol- 
 lows that the acid is composed of 
 Phosphorus, 100 
 Oxygen, 123.46. 
 
 “ To verify this result, the author (Dr 
 Thomson) had recourse to the phosphate of 
 lead, which is a compound of 2 atoms phos- 
 phoric acid -j- 1 atom yellow oxide of lead.” 
 He gives three analyses of this salt ; one by 
 Dr Wollaston ; one by Professor Berzelius; 
 and one by himself. These analyses are as 
 follows : — 
 
 Acid. Base. 
 
 By Wollaston, 100 -f 570.72 
 
 Berzelius, 100 -j- 380.56 
 
 Thomson, 100 -j- 398.49 
 
 Mean, 100 -j- 383.26. 
 
 This mean, which corresponds nearly with 
 the analysis of Berzelius, is considered by 
 him as exhibiting the true composition of 
 phosphate of lead. From this the weight of 
 an atom of phosphoric acid is shewn to be 
 3.649. But after a comparison of results by 
 different methods, he says, “ This gives us 
 1.634 for the weight of an atom of phos- 
 phorus ; 2 634 for the weight of an atom of 
 phosphorous acid ; and 3. 634 for the weight 
 of an atom of phosphoric acid.” Page 506. 
 
 In the subsequent January, when he gives 
 an Account of Physical Science for the same 
 year 1816, however, he says, “ It is quite 
 clear from these analyses,” (of Berzelius, 
 whom he there properly styles one of the 
 most accurate chemists of the present day), 
 “ that the equivalent number for phosphoric 
 acid is 4.5.” And farther, in the fifth edi- 
 tion of his System of Chemistry, published 
 in 1817, from an extremely large collection 
 of experiments, he determines the equivalent 
 of phosphorus to be 1.5 ; and that of phos- 
 phoric acid to be 4.5. Finally, in March 
 1820, without hinting in the least at his 
 abandonment of the number 3.634, and adop- 
 tion of 4.5, he merely says, “ that a set of 
 experiments he published some years ago 
 seem to me to demonstrate the constitution 
 of these two acids in a satisfactory manner.” 
 And he immediately fixes on 3.5 for phos- 
 phoric acid. 
 
 Amid all these perplexities, it is comfort- 
 able to resort to Sir H. Davy’s clear and de- 
 cisive paper, read before the Iloyal Society 
 on the 9th April 1818. With his well 
 known sagacity, he invented a new method 
 of research, to elude the former sources of 
 error. He burned the vapour of phosphorus 
 as it issues from a small tube, contained in a 
 
 retort filled with oxygen gas. By adopting 
 this process, he determined the composition 
 of phosphoric acid to be 1 00 phosphorus -J- 
 134.5 oxygen ; whence its equivalent comes 
 out 3.500. Phosphorous acid he then shews 
 to consist of 1 oxygen -j- 1.500 phosphorus 
 = 2.500. We shall therefore fix on Sir H. 
 Davy’s number 3.500 for the prime equiva- 
 lent of phosphoric acid.' 
 
 We see, indeed, in the Annals of Philos, 
 for 1816, in a paper on phosphuretted hydro- 
 gen by Dr Thomson, that this chemist had 
 determined the atom of phosphorus to be 
 1.5, and that of phosphoric acid 3.5, but he 
 subsequently renounced them. It will be 
 instructive to place his fluctuations of opinion 
 in one view. 
 
 In the Annals for April 1816, the report 
 of Dr Thomson’s paper, read at the Iloyal 
 Society, on phosphoric acid and the phos- 
 phates, makes the acid equivalent 3.634 ; in 
 the Annals for August 1816, the phosphu- 
 retted hydrogen experiments make it 3.5 : 
 the history of 1816 improvements, inserted 
 in January 1817, gives us 4.5 as the equiva- 
 lent, and an explicit renunciation of 3.5 ; 
 the System of Chemistry in October 1817 
 confirms this number 4.5 by multiplied facts 
 and reasonings ; and, finally, after Sir H. 
 Davy’s experiments appeared in 181 8, which 
 demonstrated 3.500 to be the real number, 
 Dr Thomson resumes 3.5 ; and to shew his 
 claim to priority, refers simply to his former 
 paper on phosphuretted hydrogen. From 
 this example, beginners in the study of che- 
 mistry will learn the danger of dogmatizing 
 hastily on experimental subjects.* 
 
 * Acid (Phosfhorous) was discovered in 
 1 8 1 2 by Sir H. Davy. When phosphorus and 
 corrosive sublimate act on each other at an ele- 
 vated temperature, a liquid called protochlo- 
 ride of phosphorus is formed. Water added 
 to this, resolves it into muriatic and phospho- 
 rous acids. A moderate heat suffices to ex- 
 pel the former, and the latter remains, asso- 
 ciated with water. It has a very sour taste, 
 reddens vegetable blues, and neutralizes 
 bases. When heated strongly in open ves- 
 sels, it inflames. Phosphuretted hydrogen 
 flies off, and phosphoric acid remains. Ten 
 parts of it heated in close vessels give off 
 one-half of bihydroguret of phosphorus, and 
 leave 8^ of phosphoric acid. Hence the 
 liquid acid consists of 80.7 acid -j- 19.3 
 water. Its prime equivalent is 2.5.* 
 
 * Acid (Hypophosphorous), lately disco- 
 vered by M. Dulong. Pour water on the 
 phosphuret of barytes, and wait till alt the 
 phosphuretted hydrogen be disengaged. Add 
 cautiously to the filtered liquid dilute sul- 
 phuric acid, till the barytes be all precipitat- 
 ed in the state of sulphate. The supernatant 
 liquid is hypophosphorous acid, which should 
 be passed through a filter. This liquid may 
 be concentrated by evaporation, till it become 
 
ACI 
 
 ACI 
 
 viscid. It has a very sour taste, reddens 
 vegetable blues, and does not crystallize. It 
 is probably composed of 2 primes of phos- 
 phorus = 3. + 1 of oxygen. Dulong’s 
 analysis approaches to this proportion. He 
 assigns, but from rather precarious data, 100 
 phosphorus to 37.44 oxygen. The hypo- 
 phosphites have the remarkable property of 
 being all soluble in water ; while many ot 
 the phosphates and phosphites are insoluble. 
 
 M. Thenard succeeded in oxygenizing 
 phosphoric acid by the method described 
 under nitric and muriatic acids. 
 
 With regard to the phosphates and phos- 
 phites, we have so many discrepancies in our 
 latest publications, that we must suspend our 
 judgment as to their composition. Sir H. 
 Davy says most appropriately in his last me- 
 moir on some of the combinations of phos- 
 phorus, that “ new researches are required 
 to explain the anomalies presented by the 
 phosphates.” We may add, that after he 
 has so effectually cleared up the mysteries of 
 the acids themselves, the scientific world look 
 to him to throw the same light on their saline 
 combinations.* 
 
 Phosphoric acid, united with barytes, pro- 
 duces an insoluble salt, in the form of a 
 heavy white powder, fusible at a high tempe- 
 rature into a grey enamel. The best mode 
 of preparing it is by adding an alkaline 
 phosphate to the nitrate or muriate of ba- 
 rytes. 
 
 The phosphate of strontian differs from 
 the preceding in being soluble in an excess 
 of its acid. 
 
 Phosphate of lime is very abundant in the 
 native state. At Marmarosch in Hungary, 
 it is found in a pulverulent form, mixed with 
 fluate of lime : in the province of Estrema- 
 dura in' Spain, it is in such large masses, 
 that walls of enclosures, and even houses, are 
 built with it; and it is frequently crystalliz- 
 ed, as in the apatite of Werner, when it as- 
 sumes different tints of grey, brown, purple, 
 blue, olive, and green. In the latter state, 
 it has been confounded with the crysolite, 
 and sometimes with the beryl and aqua ma- 
 rine, as in the stone called the Saxon beryl. 
 It likewise constitutes the chief part of the 
 bones of all animals. 
 
 The phosphate of lime is very difficult to 
 fuse, but in a glasshouse furnace it softens, 
 and acquires the semitransparency and grain 
 of porcelain. It is insoluble in water, but 
 when well calcined, forms a kind of paste 
 with it, as in making cupels, Besides this 
 use of it, it is employed for polishing gems 
 and metals, for absorbing grease from cloth, 
 linen, or paper, and for preparing phospho- 
 rus. In medicine it has been strongly re- 
 commended against the rickets by Dr Bon- 
 homme of Avignon, either alone or combin- 
 ed with phosphate of soda. The burnt harts - 
 Kern of the shops is a phosphate of lime. 
 
 An acidulous phosphate of lime is found 
 in human urine, and may be crystallized in 
 small silky filaments, or shining scales, which 
 unite together into something like the con- 
 sistence of honey, and have a perceptibly 
 acid taste. It may be prepared by partially 
 decomposing the calcareous phosphate of 
 bones by the sulphuric, nitric, or muriatic 
 acid, or by dissolving that phosphate in phos- 
 phoric acid. It is soluble in water, and 
 crystallizable. Exposed to the action of 
 heat, it softens, liquefies, swells up, becomes 
 dry, and may be fused into a transparent 
 glass, which is insipid, insoluble, and un- 
 alterable in the air. In these characters it 
 differs from the glacial acid of phosphorus. 
 It is partly decomposable by charcoal, so as 
 to afford phosphorus. 
 
 The phosphate of potash is very deliques- 
 cent, and not crystallizable, but condensing 
 into a kind of jelly. Like the preceding 
 species, it first undergoes the aqueous fusion, 
 swells, dries, and may be fused into a glass ; 
 but this glass deliquesces. It has a sweetish 
 saline taste. 
 
 The phosphate of soda was first discovered 
 combined with ammonia in urine, by Schock- 
 vvitz, and was called fusible or microcosmic 
 salt. Margraff obtained it alone by lixiviat- 
 
 ing the residuum left after preparing phos- 
 phorus from this triple salt and charcoal. 
 Haupt, who first discriminated the two, gave 
 the phosphate of soda the name of sal mira- 
 bile perlatum. Rouelle very properly an- 
 nounced it to be a compound of soda and 
 phosphoric acid. Bergman considered it, or 
 rather the acidulous phosphate, as a peculiar 
 acid, and gave it the name of perlate acid . 
 Guyton- Morveau did the same, but distin- 
 guished it by the name of ouretic : at length 
 Klaproth ascertained its real nature to be as 
 Rouelle had affirmed. 
 
 This phosphate is now commonly prepar- 
 ed by adding to the acidulous phosphate of 
 lime as much carbonate of soda in solution 
 as will fully saturate the acid. The car- 
 bonate of lime, which precipitates, being 
 separated by filtration, the liquid is duly 
 evaporated so as to crystallize the phosphate 
 of soda; but if there be not a slight excess 
 of alkali, the crystals will not be large and 
 regular. M. Funcke, of Linz, recommends, 
 as a more economical and expeditious mode, 
 to saturate the excess of lime in calcined 
 bones by dilute sulphuric acid, and dissolve 
 the phosphate of lime that remains in nitric 
 acid. To this solution he adds au equal 
 quantity of sulphate of soda, and recovers 
 the nitric acid by distillation. He then se- 
 parates the phosphate of soda from the sul- 
 phate of lime by elutriation and crystalliza- 
 tion, as usual. The crystals are rhomboidal 
 prisms of different shapes ; efflorescent; so- 
 luble in 3 parts of cold and l-§ of hot water. 
 They are capable of being fused into an 
 
ACI 
 
 ACI 
 
 opaque white glass, which may he again dis- 
 solved and crystallized. It may be convert- 
 ed into an acidulous phosphate hy an addi- 
 tion of acid, or by either of the strong acids, 
 which partially, but not wholly, decompose 
 it. As its taste is simply saline, without 
 any thing disagreeable, it is much used as a 
 purgative, chiefly in broth, in which it is not 
 distinguishable from common salt. For this 
 elegant addition to our pharmaceutical pre- 
 parations, we are indebted to Dr Pearson. 
 In assays with the blowpipe it is of great 
 utility ; and it has been used instead of bo- 
 rax for soldering. 
 
 The phosphate of ammonia crystallizes in 
 prisms with four regular sides, terminating 
 in pyramids, and sometimes in bundles oi 
 small needles. Its taste is cool, saline, pun- 
 gent, and urinous. On the fire it comports 
 itself like the preceding species, except that 
 the whole of its base may be driven off by a 
 continuance of the heat, leaving only the 
 acid behind. It is but little more soluble in 
 hot water than in cold, which takes up a 
 fourth of its weight. It is pretty abundant 
 in human urine, particularly after it is be- 
 come putrid. It is an excellent flux both 
 for assays and the blowpipe, and in the fa- 
 brication of coloured glass and artificial 
 gems. 
 
 Phosphate of magnesia crystallizes in ir- 
 regular hexaedral prisms, obliquely truncat- 
 ed ; but is commonly pulverulent, as it 
 effloresces very quickly. It requires fifty 
 parts of water to dissolve it. Its taste is 
 cool and sweetish. This salt too is found 
 in urine. Foureroy and Vauquelin have 
 discovered it likewise in small quantity in 
 the bones of various animals, though not 
 in those of man. The best way of prepar- 
 ing it is by mixing equal parts of the solu- 
 tions of phosphate of soda and sulphate of 
 magnesia, and leaving them some time at 
 rest, when the phosphate of magnesia will 
 crystallize, and leave the sulphate of soda 
 dissolved. 
 
 An ammoniaco-magnesian phosphate has 
 been discovered in an intestinal calculus of 
 a horse by Fourcrov, and since by Bar- 
 tholdi, and likewise by the former in some 
 human urinary calculi. Notwithstanding 
 the solubility of the phosphate of ammonia, 
 this triple salt is far less soluble than the 
 phosphate of magnesia. It is partially de- 
 composable into phosphorus by charcoal, in 
 consequence of its ammonia. 
 
 The phosphate of glucine has been exa- 
 mined by Vauquelin, who informs us, that 
 it is a white powder, or mucilaginous mass, 
 without any perceptible taste ; fusible, but 
 not decomposable by heat ; unalterable in 
 the air ; and insoluble unless in an excess of 
 its acid. 
 
 It has been observed, that the phospho- 
 ric acid, aided by heat, acts upon silex ; and 
 
 we may add, that it enters into many arti- 
 ficial gems in the state of a siliceous phos- 
 phate. 
 
 Acid (Prussic). The combination of this 
 acid with iron was long known and used as 
 a pigment by the name of prussian blue, be- 
 fore its nature was understood. Macquer 
 first found, that alkalis would decompose 
 prussian blue, by separating the iron from 
 the principle, with which it was combined in 
 it, and which he supposed to be phlogiston. 
 In consequence, the prussiate of potash was 
 long called phlogisticnted allcali. Bergman, 
 however, from a more scientific considera- 
 tion of its properties, ranked it among the 
 acids ; and as early as 1772, Sage announc- 
 ed, that this animal acid, as he called it, 
 formed with the alkalis neutral salts, that 
 with potash forming octaedral crystals, anil 
 that with soda rhomboids or hexagonal la- 
 mina?. About the same time Seheele insti- 
 tuted a series of sagacious experiments, not 
 only to obtain the acid separate, which he 
 effected, but also to ascertain its constituent 
 principles. These, according to him, are 
 ammonia and carbon ; and Berthollet there- 
 after added, that its triple base consists of 
 hydrogen and azote, nearly, if not precisely, 
 in the proportions that form ammonia and 
 carbon. Berthollet could find no oxygen in 
 any of his experiments for decomposing this 
 acid. 
 
 Seheele’ s method is this : Mix four ounces 
 of prussian blue with two of red oxide of 
 mercury prepared by nitric acid, and boil 
 them in twelve ounces hy weight of water, 
 till the whole becomes colourless ; filter the 
 liquor, and add to it one ounce of clean iron 
 filings, and six or seven drams of sulphuric 
 acid. Draw off by distillation about a fourth 
 of the liquor, which will be prussic acid ; 
 though, as it is liable to be contaminated with 
 a portion of sulphuric, to render it pure, it 
 may be rectified by redistilling it from car- 
 bonate of lime. 
 
 This prussic acid has a strong smell of 
 peach blossoms, or bitter almonds ; its taste 
 is at first sweetish, then acrid, hot, and viru- 
 lent, and excites coughing ; it has a strong 
 tendency to assume the form of gas ; it has 
 been decomposed in a high temperature, 
 and by the contact of light, into carbonic 
 acid, ammonia, and carburetted hydrogen. 
 It does not completely neutralize alkalis, 
 and is displaced even by the carbonic 
 acid ; it has no action upon metals, but 
 unites with their oxides, and forms salts for 
 the most part insoluble ; it likewise unites 
 into triple salts with these oxides and alka- 
 lis ; the oxygenated muriatic acid decom- 
 poses it. 
 
 The peculiar smell of the prussic acid 
 could scarcely fail to suggest its affinity with 
 the deleterious principle that rises in the 
 distillation of the leaves of the lauro-cerasus, 
 
ACI 
 
 bitter kernels of fruits, and some ether ve- 
 getable productions ; and M. Schrader of 
 Berlin has ascertained the fact, that these 
 vegetable substances do contain a principle 
 capable of forming a blue precipitate with 
 iron ; and that with lime they afford a test 
 of the presence of iron, equal to the prussiate 
 of that earth. Dr Bucholz of Weimar, and 
 Mr Roloff of Magdeburg, confirm this fact. 
 The prussic acid appears to come over in the 
 distilled oil. 
 
 * Prussic acid and its combinations have 
 been lately investigated by M. Gay Lussac 
 and Vauquelin in France, and Mr Porrett 
 in England, who have happily succeeded in 
 removing in some measure the veil which con- 
 tinued to hang over this department of che- 
 mistry. 
 
 To a quantity of powdered prussian blue 
 diffused in boiling water, let red oxide of 
 mercury be added in successive portions till 
 the blue colour is destroyed. Filter the li- 
 quid, and concentrate by evaporation till a 
 pellicle appears. On cooling, crystals of 
 prussiate or cyanide of mercury will be 
 formed. Dry these, and put them into a 
 tubulated glass retort, to the beak of which 
 is adapted a horizontal tube about two feet 
 long, and fully half an inch wide at its mid- 
 dle part. The first third part of the tube 
 next tlie retort is filled with small pieces of 
 white marble, the two other thirds with fused 
 muriate of lime. To the end of this tube is 
 adapted a small receiver, which should be 
 artificially refrigerated. Pour on the crys- 
 tals, muriatic acid, in rather less quantity 
 than is sufficient to saturate the oxide of 
 mercury, which formed them. Apply a very 
 gentle heat to the retort. Prussic acid, 
 named hydrocyanic by M. Gay Lussac, will 
 be evolved in vapour, and will condense in 
 the tube. Whatever muriatic acid may pass 
 over with it, will be abstracted by the marble, 
 while the water will he absorbed by the mu- 
 riate of lime. By means of a moderate heat 
 applied to the tube, the prussic acid may be 
 made to pass successively along ; and after 
 being left some time in contact with the 
 muriate of lime, it may he finally driven 
 into the receiver. As the carbonic acid 
 evolved from marble by the muriatic is apt 
 to carry ofl some of the prussic acid, care 
 should be taken to conduct the heat so 
 as to prevent the distillation of this mineral 
 acid. 
 
 Prussic acid thus obtained has the follow- 
 ing properties. It is a colourless liquid, 
 possessing a strong odour ; and the exhala- 
 tion, if incautiously snuffed up the nostrils, 
 may produce sickness or fainting. Its taste is 
 cooling at first, then hot, asthenic in a high 
 degree, and a true poison. Its specific gra- 
 vity at 444°, is 0.7058; at 64° it is 0.6969. 
 It boils at 81 t°, and congeals at about 8°. 
 It then crystallizes regularly, and affects 
 
 ACI 
 
 sometimes the fiorous form of nitrate of am- 
 monia. The cold which it produces, when 
 reduced into vapour, even at the temperature 
 of 68°, is sufficient to conceal it. This 
 phenomenon is easily produced by putting a 
 small drop at the end of a slip of paper or a 
 glass tube. Though repeatedly rectified on 
 pounded marble, it retains the property of 
 feebly reddening paper tinged blue with lit- 
 mus. The red colour disappears as the acid 
 evaporates. 
 
 The specific gravity of its vapour, experi- 
 mentally compared to that of air, is 0.9476. 
 By calculation from its constituents, its true 
 specific gravity comes out 0.9560, which 
 differs from the preceding number by only 
 one-hundredth part. This small density of 
 prussic acid, compared with its great volati- 
 lity, furnishes a new proof that the density 
 of vapours does not depend upon the boiling 
 point of the liquids that furnish them, but 
 upon their peculiar constitution. 
 
 M. Gay Lussac analyzed this acid by in- 
 troducing its vapour at the temperature of 
 86° into ajar, two-thirds filled with oxygen, 
 over warm mercury. When the temperature 
 of the mercury was reduced to that of the am- 
 bient air, a determinate volume of the gase- 
 ous mixture was taken and washed in a so- 
 lution of potash, which abstracts the prussic 
 acid, and leaves the oxygen. This gaseous 
 mixture may after this inspection, be employ- 
 ed without any chance that the prussic acid 
 will condense, provided the temperature be 
 not too low ; but during M. Gay Lussac’s 
 experiments it was never under 7 1 -^°. A 
 known volume was introduced into a V olta’s 
 eudiometer, with platina wires, and an elec- 
 tric spark was passed across the gaseous mix- 
 ture. The combustion is lively, and of a 
 bluish white colour. A white prussic va- 
 pour is seen, and a diminution of volume 
 takes place, which is ascertained by measur- 
 ing the residue in a graduated tube. This 
 being washed with a solution of potash or 
 barytes, suffers a new diminution from the 
 absorption of the carbonic acid gas formed. 
 Lastly, the gas, which the alkali has left, is 
 analyzed over water by hydrogen, and it is 
 ascertained to be a mixture of nitrogen and 
 oxygen, because this last gas w r as employed 
 in excess. 
 
 The follow ing are the results, referred to 
 
 prussic acid vapour. 
 
 Vapour, - - - - ]00 
 
 Diminution after combustion, - 78.5 
 
 Carbonic acid gas produced, - 101.0 
 
 Nitrogen, - 46.0 
 
 Hydrogen, - 55. 0 
 
 During the combustion a quantity of 
 oxygen disappears, equal to about 1± of 
 the vapour employed. The carbonic acid 
 produced represents one volume ; and the 
 oilier fourth is supposed to be employed in 
 
ACI 
 
 ACI 
 
 forming water ; for it is impossible to doubt 
 that hydrogen enters into the composition of 
 prussic acid. From the laws of chemical pro- 
 portions, M. G. Lussac concludes that prus- 
 sic acid vapour contains just as much carbon 
 as will form its own bulk of carbonic acid, 
 hall a volume of nitrogen, and half a volume 
 of hydrogen. This result is evident for the 
 carbon ; and though, instead of 50 of nitrogen 
 and hydrogen, which ought to be the num- 
 bers according to the supposition, he obtain- 
 ed 46 for the first, and 55 for the second, he 
 ascribes the discrepancy to a portion of the 
 nitrogen having combined with the oxygen 
 to form nitric acid. 
 
 The density of carbonic acid gas being, 
 according to M. Gay Lussac, 1.5196, and 
 that of oxygen 1.1036, the density of the 
 vapour of carbon is 1.5196 — 1.10S6 = 
 0.4 1 60. Hence 1 volume carbon, = 0.4 1 60 
 
 Half a volume of hydrogen, = 0.0366 
 
 Half a volume of nitrogen, = 0.4845 
 
 Sum, = 0.9371 
 
 Thus, according to the analytical state- 
 ment, the density of prussic vapour is 0.9371, 
 and by direct experiment it was found to be 
 0.9476. It may therefore be inferred from 
 this near coincidence, that prussic acid vapour 
 contains one volume of the vapour of car- 
 bon, half a volume of nitrogen, and half a 
 volume of hydrogen, condensed into one vo- 
 lume, and that no other substance enters 
 into its composition. 
 
 M. Gay Lussac confirmed the above de- 
 termination, analyzing prussic acid, by pass- 
 ing its vapour through an ignited porcelain 
 tube containing a coil of fine iron wire, 
 which facilitates the decomposition of this va- 
 pour, as does it with ammonia. No trace of 
 oxygen could be found in prussic acid. And 
 again, by transmitting the acid in vapour 
 over ignited peroxide of copper in a porce- 
 lain tube, he came to the same conclusion 
 with regard to its constituents. They are, — 
 One volume of the vapour of carbon, 
 Half a volume of hydrogen, 
 
 Half a volume of nitrogen, 
 condensed into one volume ; or in w eight, — 
 
 Carbon, 
 
 - 
 
 44.39 
 
 Nitrogen, 
 
 - 
 
 51.71 
 
 Hydrogen, 
 
 m 
 
 3. 90 
 
 
 
 100.00 
 
 This acid, when compared with the other 
 animal products, is distinguished by the 
 great quantity of nitrogen it contains, by its 
 small quantity of hydrogen, and especially 
 by the absence of oxygen. 
 
 When this acid is kept in well-closed 
 vessels, even though no air be present, it is 
 sometimes decomposed in less than an hour. 
 
 It has been occasionally kept 15 days with- 
 out alteration ; but it is seldom that it can 
 be kept longer, without exhibiting signs of 
 decomposition. It begins by assuming a 
 reddish brown colour, which becomes deeper 
 and deeper, and it gradually deposits a con- 
 siderable carbonaceous matter, which gives a 
 deep colour to both water and acids, and 
 emits a strong smell of ammonia. If the 
 bottle containing the prussic acid be not 
 hermetically sealed, nothing remains but a 
 dry charry mass, which gives no colour to 
 water. Thus a prussiate of ammonia is 
 formed at the expense of a part of the acid, 
 and an azoturet of carbon. When potassium 
 is heated in prussic acid vapour mixed w r ith hy- 
 drogen or nitrogen, there is absorption with- 
 out inflammation, and the metal is converted 
 into a grey spongy substance, which melts, 
 and assumes a yellow colour. 
 
 Supposing the quantity of potassium em- 
 ployed capable of disengaging from water a 
 volume of hydrogen equal to 50 parts, we 
 find after the action of the potassium, — 
 
 1. That the gaseous mixture has experi- 
 enced a diminution of volume amounting to 
 50 parts : 2. On treating this mixture w ith 
 
 potash, and analyzing the residue by oxygen, 
 that 50 parts of hydrogen have been produc- 
 ed : S. And consequently that the potassium 
 has absorbed 100 parts of prussic vapour; 
 for there is a diminution of 50 parts, which 
 w’ould obviously have been twice as great 
 had not 50 parts of hydrogen been disengag- 
 ed. The yellow matter is prussiate of pot- 
 ash ; properly a prusside of potassium, ana- 
 logous in its formation to the chloride and 
 iodide, when muriatic and hydriodic gases 
 are made to act on potassium. 
 
 The base of prussic acid thus divested of 
 its acidifying hydrogen, should be called, 
 agreeably to the same chemical analogy, 
 prussine. M. Gay Lussac styles it cyanogen, 
 because it is the principle which generates 
 blue ; or literally, the blue-maker. 
 
 Like muriatic and hydriodic acids also, it 
 contains half its volume of hydrogen. The 
 only difference is, that the former have in the 
 present state of our knowledge simple radi- 
 cals, chlorine and iodine, while that of the 
 latter is a compound of one volume vapour 
 of carbon, and half a volume of nitrogen. 
 This radical forms true prussides with metals. 
 
 If the term cyanogen be objectionable as 
 allying it to oxygen, instead of chlorine and 
 iodine, the term hydrocyanic acid must be 
 equally so, as implying that it contains 
 water. Thus we say hydronitric, hvdromu- 
 riatic, and hydrophosphoric, to denote the 
 aqueous compounds of the nitric, muriatic, 
 and phosphoric acids. As the singular merit 
 of M. Gay Lussac, however, has command- 
 ed a very general compliance among chemists 
 with his nomenclature, we shall use the terms 
 
ACI 
 
 ACI 
 
 prussic acid and hydrocyanic indifferently, as 
 has long been done with the words nitrogen 
 and azote. 
 
 The prusside or cyanide of potassium gives 
 a very alkaline solution in water, even when 
 a great excess of hydrocyanic vapour has 
 been present at its formation. In this re- 
 spect it differs from the chlorides and iodides 
 of that metal, which are perfectly neutral. 
 Knowing the composition of prussic acid, 
 and that potassium separates from it as much 
 hydrogen as from water, it is easy to find its 
 proportional number or equivalent to oxy- 
 gen. We must take such a quantity of 
 prussic acid that its hydrogen may saturate 
 10 of oxygen. Thus we find the prime 
 equivalent of this acid to be 33.846; and 
 subtracting the weight of hydrogen, there 
 remains 32.52 for the equivalent of cyano- 
 gen or prussine. But if we reduce the 
 numbers representing the volumes to the 
 prime equivalents adopted in this Dictionary, 
 viz. 0.75 for carbon, 0.1 25 for hydrogen, and 
 1.75 for nitrogen, we shall have the relation 
 of volumes slightly modified. Since the 
 fundamental combining ratio of oxygen to 
 hydrogen in bulk is \ to 1 , we must multi- 
 ply the prime equivalent by half the speci- 
 fic gravity of oxygen, and we obtain the fol- 
 lowing numbers 
 
 1 volume car. = 0.75 X 0.5555 = 0.41663 
 
 i volume hyd. = gj£gX°-5555 ==003471 
 
 2 
 
 \ volume nitr. = J - 7 ^X 0 ; 5_555 __ 0 4861() 
 
 2 
 
 Sum = 0.93744 
 
 Or, as is obvious by the above calculation, 
 we may take 2 primes of carbon, 1 of hydro- 
 gen, and 1 of nitrogen, which directly added 
 together will give the same results, since by 
 so doing we merely take away the common 
 multiplier 0.5555. Thus we have 
 
 2 primes carbon, - 1.500 
 
 1 prime hydrogen, - 0. 1 25 
 
 1 prime nitrogen, - 1.750 
 
 3.375 
 
 W hich reduced to proportions per cent, give 
 of carbon, - _ _ 44.444 
 
 Hydrogen, - - . 3.737 
 
 Nitrogen, - . - 51.818 
 
 100.000 
 
 Barytes, potash, and soda, combine with 
 prussine, forming true prussides of these al- 
 kaline oxides ; analogous to what are vulgar- 
 ly called oxymuriates of lime, potash, and 
 soda. I he red oxide of mercury acts so 
 powerfully on prussic acid vapour, when as- 
 sisted by heat, that the compound which 
 
 ought to result is destroyed by the heat disen- 
 gaged. The same thing happens when a 
 little of the concentrated acid is poured upon 
 the oxide. A great elevation of temperature 
 takes place, which would occasion a danger- 
 ous explosion if the experiment were made 
 upon considerable quantities. When the 
 acid is diluted the oxide dissolves rapidly, 
 with a considerable heat, and without the 
 disengagement of any gas. The substance 
 formerly called prussiate of mercury is ge- 
 nerated, which when moist may, like the 
 muriates, still retain that name ; but w r hen 
 dry is a prusside of the metal. 
 
 When the cold oxide is placed in contact 
 with the acid, dilated into a gaseous form 
 bv hydrogen, its vapour is absorbed in a few 
 minutes. The hydrogen is unchanged. 
 When a considerable quantity of vapour has 
 thus been absorbed, the oxide adheres to the 
 side of the tube, and on applying heat, w'ater 
 is obtained. The hydrogen of the acid has 
 here united with the oxygen of the oxide to 
 form the water, w'hile their two radicals com- 
 bine. Red oxide of mercury becomes an 
 excellent reagent for detecting prussic acid. 
 
 By exposing the dry prusside of mercury 
 to heat in a retort, the radical cyanogen or 
 prussine is obtained. See Prussine. 
 
 On subjecting hydrocyanic, or prussic acid, 
 to the action of a battery of 20 pairs of 
 plates, much hydrogen is disengaged at the 
 negative pole ; and cyanogen or prussine at 
 the positive, which remains dissolved in the 
 acid. This compound should be regarded 
 as a hypoprussic or prussous acid. Since 
 potash by heat separates the hydrogen of the 
 prussic acid, we see that in exposing a mix- 
 ture of potash and animal matters to a high 
 temperature, a true prusside or cyanide of 
 potash is obtained, formerly called the Prus- 
 sian or phlogisticated alkali. When cyanide 
 of potassium is dissolved in water, hydro- 
 cyanate of potash is produced, which is de- 
 composed by the acids without generating 
 ammonia or carbonic acid ; but w hen cyanide 
 of potash dissolves in water no change takes 
 place ; and neither ammonia, carbonic acid, 
 nor hydrocyanic vapour, is given out, unless 
 an acid be added. These are the characters 
 which distinguish a metallic cyanide from the 
 cyanide of an oxide. 
 
 From the experiments of M. Magendie it 
 appears, that the pure hydrocyanic acid is 
 the most violent of all poisons. W r hen a rod 
 dipped into it is brought in contact with the 
 tongue of an animal, death ensues before 
 the rod can be withdrawn. If a bird be held 
 a moment over the mouth of a phial con- 
 taining this acid, it dies. In the Annales 
 de Chimie for 1814 we find this notice: 
 M. B. Professor of Chemistry, left by acci- 
 dent on a table a flask containing alcohol 
 impregnated with prussic acid ; the servant* 
 enticed by the agreeable flavour of the liquid 
 
ACI 
 
 ACI 
 
 swallowed a small glass of it. In two mi- 
 nutes she dropped down dead, as if struck 
 with apoplexy. The body was not examin- 
 ed. 
 
 “ Scharinger, a professor at Vienna,” says 
 Orfila, “ prepared six or seven months ago a 
 pure and concentrated prussic acid ; he 
 spread a certain quantity of it on his naked 
 arm, and died a little time thereafter.” 
 
 Dr Magendie has, however, ventured to 
 introduce its employment into medicine. He 
 found it beneficial against phthisis and chronic 
 catarrhs. His formula is the following : — 
 
 Mix one part of the pure prussic or hy- 
 drocyanic acid of M. Gay Lussac with 8^ 
 of water by weight. To this mixture he 
 gives the name of medicinal prussic acid. 
 
 Of this he takes 1 gros. or 59 gr. Troy. 
 
 Distilled water, 1 lb. or 7560 grs. 
 
 Pure sugar, 1^ oz. or 708f gr. 
 
 And mixing the ingredients well together, 
 he administers a table spoonful every morn- 
 ing and evening. A well written report of 
 the use of the prussic acid in certain diseases, 
 by Dr Magendie, was communicated by Dr 
 Granville to Mr Brande, and is inserted in 
 the fourth volume of the Journal of Science. 
 
 For the following ingenious and accurate 
 process for preparing prussic acid for medi- 
 cinal uses, I am indebted to Dr Nimmo of 
 Glasgow : 
 
 “ Take of the ferroprussiate of potash 100 
 grains, of the protosulphate of iron 84-| 
 grains, dissolve them separately in four 
 ounces of water, and mingle them. After 
 allowing the precipitate of the protoprussiate 
 of iron to settle, pour off the clear part, and 
 add water to wash the sulphate of potash 
 completely away. To the protoprussiate of 
 iron, mixed with four ounces of pure water, 
 add 1 35 grains of the peroxide of mercury, 
 and boil the whole till the oxide is dissolved. 
 With the above proportions of peroxide of mer- 
 cury, the protoprussiate of iron is completely 
 decomposed. The vessel being kept warm, 
 the oxide of iron will fall to the bottom, the 
 clear part may be poured off to be filtered 
 through paper, taking care to keep the fun- 
 nel covered, so that crystals may not form in 
 it by refrigeration. The residuum may be 
 treated with more water, and thrown upon 
 the filter, upon which warm water ought to 
 be poured, until all the soluble part is wash- 
 ed away. By evaporation, and subsequent 
 rest in a cool place, 145 grains of crystals 
 of the prusside or cyanide of mercury will 
 be procured in quadrangular prisms. 
 
 “ The following process for eliminating 
 the hydrocyanic acid I believe to be new. 
 Take of the cyanide of mercury in fine pow- 
 der one ounce, diffuse it in two ounces of 
 water, and to it, by slow degrees, add a solu- 
 tion of hydrosulphuret of barytes, made by 
 decomposing sulphate of barytes with char- 
 coal in the common way. Of the sulphured 
 
 of barytes take an ounce, boil it with six 
 ounces of water, and filter it as hot as possi- 
 ble. Add this in small portions to the cy- 
 anide of mercury, agitating the whole very 
 well, and allowing sufficient time for the 
 cyanide to dissolve, while the decomposition 
 is going on between it and the hydrosulphu- 
 ret as it is added. Continue the addition of 
 the hydrosulphuret so long as a dark preci- 
 pitate of sulphuret of mercury falls down, 
 and even allowing a small excess. Let the 
 whole be thrown upon a filter, and kept 
 warm till the fluid drops through ; add more 
 w ater to wash the sulphuret of mercury, un- 
 til eight ounces of fluid have passed through 
 the filter, and it has become tasteless. To 
 this fluid, which contains the prussiate of 
 barytes, with a small excess of hydrosulphu- 
 ret of barytes, add sulphuric acid, diluted 
 with an equal weight of water, and allowed 
 to become cold, so long as sulphate of bary- 
 tes falls down. The excess of sulphuretted 
 hydrogen will he removed by adding a suffi- 
 cient portion of carbonate of lead, and agi- 
 tating very well. The whole may now be 
 put upon a filter, which must be closely 
 covered ; the fluid which passes is the hydro- 
 cyanic acid, of what is called the medical 
 standard strength.” 
 
 Dr Nimmo finds, that cyanide of mercury 
 is capable of dissolving the mercurial per- 
 oxide. Hence, the above proportions must 
 be strictly observed, if we wish to obtain this 
 powerful medicine of uniform strength. He 
 conceives, therefore, that the ferroprussiate of 
 potash should be taken for the basis of the 
 calculation. 
 
 Scheele found that prussic acid occasioned 
 precipitates with only the following three 
 metallic solutions, nitrates of silver, and 
 mercury, and carbonate of silver. The first 
 is white, the second black, the third green 
 becoming blue. In the Annals of Phil, for 
 May 1820, Dr Thomson gives an account of 
 some metallic precipitates by a substance of 
 a crystalline nature, which he obtained in the 
 sublimation of prussian blue at a red heat, 
 and which he reckons hydrocyanate of ammo- 
 nia. But the nature of the substance is by 
 no means demonstrated ; and the precipitates 
 differ so much from those of Scheele as to 
 justify scepticism. Free prussic acid, for ex- 
 ample, gives with nitrate of mercury a black 
 precipitate ; while Dr Thomson’s crystals 
 give a white. Vauquelin found the crystals 
 that sublime from prussian blue to be am* 
 moniacal carbonate, and not hydrocyanate. 
 
 The h'ydrocyanates are all alkaline, even 
 when a great excess of acid is employed in 
 their formation ; and they are decomposed 
 by the weakest acids. 
 
 The hydrocyanate of ammonia crystallizes 
 in cubes, in small prisms crossing each oilier, 
 or in feathery crystals, like the leaves of a 
 fern. Its volatility is such, that at the tan- 
 
ACI 
 
 ACI 
 
 perature of 71 4° it is capable of bearing a 
 pressure of 17.72 inches of mercury ; and at 
 97° its elasticity is equal to that of the at- 
 mosphere. Unfortunately this salt is charred 
 and decomposed with extreme facility. Its 
 great volatility prevented M. Gay Lussac 
 from determining the proportion of its con- 
 stituents. What is known of the cyanides or 
 prussides will be found under prussine, or 
 their bases. M. Gay Lussac considers Prus- 
 sian blue as a hydrated cyanide of iron, or a 
 cyanide having water in combination ; and 
 M. Vauquelin, in a memoir lately read be- 
 fore the Academy of Sciences, regards Prus- 
 sian blue as a simple hydrocyanate of iron. 
 He finds that water impregnated with cyano- 
 gen can dissolve iron without changing it 
 into prussian blue, and without the disen- 
 gagement of any hydrogen gas, while prus- 
 sian blue was left in the undissolved portion. 
 But hydrocyanic acid converts iron or its 
 oxide into prussian blue without the help 
 either of alkalis or acids. He conceives that 
 cyanogen acts on iron and water as iodine 
 does on water and a base ; and that a cya- 
 nic acid is formed which dissolves a part of 
 the iron, but also and at the same time hy- 
 drocyanic acid, which changes another part 
 of the iron into prussian blue. He farther 
 lays it down as a general rule, that those 
 metals which, like iron, decompose water at 
 the ordinary temperature of the atmosphere, 
 form hydrocyanates ; and that those metals 
 which do not possess this power, as silver and 
 quicksilver, form only cyanides. Are we to 
 regard the cyanic acid of M. Vauquelin as a 
 compound of one prime of oxygen, and one 
 of cyanogen, or in other w'ords, one of oxy- 
 gen, two of carbon, and one of nitrogen ? 
 
 According to M. Vauquelin, very complex 
 changes take place when gaseous cyanogen 
 is combined with water, which leave the 
 nature of cyanic acid involved in great ob- 
 scurity. The water is decomposed ; part of 
 its hydrogen combines with one part of the 
 cyanogen, and forms hydrocyanic acid ; ano- 
 ther part unites with the nitrogen of the cya- 
 nogen, and forms ammonia ; and the oxygen 
 of the water forms carbonic acid, with one 
 part of the carbon of the cyanogen. Hydro- 
 cyanate, carbonate, and cyan ate of ammonia, 
 are also found in the liquid ; and there still 
 remain some carbon and nitrogen, which 
 produce a brown deposite. Four and a half 
 parts ot water absorb one of gaseous cyano- 
 gen, which communicate to it a sharp taste 
 and smell, but no colour. The solution in 
 the course of some days, however, becomes 
 yellow, and afterw ards brown, in consequence 
 of the intestine changes related above. 
 
 Hydrocyanic acid is separated from potash 
 by carbonic acid ; but when oxide of iron is 
 added to the potash, M. Gay Lussac con- 
 ceives that a triple compound, united by a 
 nhich more energetic affinity, results, consti- 
 
 tuting what is usually called prussiate of po- 
 tash, or prussiate of potash and iron. In 
 illustration of this view', he prepared a hy- 
 drocyanate of potash and silver, which was 
 quite neutral, and which crystallized in hex- 
 agonal plates. The solution of these crys- 
 tals precipitates salts of iron and copper, 
 white. Muriate of ammonia does not render 
 it turbid ; but muriatic acid, by disengaging 
 hydrocyanic acid, precipitates chloride of sil- 
 ver. Sulphuretted hydrogen produces in it 
 an analogous change. This compound, says 
 M. Gay Lussac, is evidently the triple hy- 
 drocyanate of potash and silver ; and its for- 
 mation ought to be analogous to that of the 
 other triple hydrocyanates. “ And as we 
 cannot doubt, 75 adds he, “ that hydrocyanate 
 of potash and silver is in reality, from the 
 mode of its formation, a compound of cya- 
 nide of silver and hydrocyanate of potash, I 
 conceive that the hydrocyanate of potash 
 and iron is likewise a compound of neu- 
 tral hydrocyanate of potash, and subcya- 
 nide of iron, which I believe to be combined 
 with hydrocyanic acid in the white preci- 
 pitate. We may obtain it perfectly neutral, 
 and then it does not decompose alum ; but 
 the hydrocyanate of potash, w'hich is always 
 alkaline, produces in it a light and ficcculent 
 precipitate of alumina. To the same excess 
 of alkali we must ascribe the ochry colour of 
 the precipitates which hydrocyanate of po- 
 tash forms with the persalts of iron. Thus 
 the remarkable fact, which ought to fix the 
 attention of chemists, and which appears to 
 me to overturn the theory of Mr Porrett, is, 
 that hydrocyanate of potash cannot become 
 neutral except when combined with the 
 cyanides.” * 
 
 * Acid (Chlorocyanic, or Chloroprus- 
 sic). M. Berthollet discovered, that when 
 hydrocyanic acid is mixed with chlorine, it 
 acquires new properties. Its odour is much 
 increased. It no longer forms Prussian blue 
 with solutions of iron, but a green precipi- 
 tate, w hich becomes blue by the addition of 
 sulphurous acid. Hydrocyanic acid thus al- 
 tered had acquired the name of oxyprussic , 
 because it was supposed to have acquired 
 oxygen. M. Gay Lussac subjected it to a 
 minute examination, and found that it w r as a 
 compound of equal volumes of chlorine and 
 cyanogen, whence he proposed to distinguish 
 it by the name of chlorocyanic acid. To 
 prepare this compound, he passed a current 
 of chlorine into solution of hydrocyanic acid, 
 till it destroyed the colour of sulphate of in- 
 digo ; and by agitating the liquid with mer- 
 cury, he deprived it of the excess of chlorine. 
 By distillation, afterwards* in a moderate 
 heat, an elastic fluid is disengaged, which 
 possesses the properties formerly assigned to 
 oxyprussic acid. This, however, is not pure 
 chlorocyanic acid, but a mixture of it with 
 carbonic acid, in proportions which vary so 
 
ACI 
 
 ACI 
 
 much, as to make it difficult to determine 
 them. 
 
 When hydrocyanic acid is supersaturated 
 with chlorine, and the excess of this last is 
 removed by mercury, the liquid contains 
 chlorocyanic and muriatic acids. Having 
 put mercury into a glass jar till it was 3-4ths 
 full, he filled it completely with that acid 
 liquid, and inverted the jar in a vessel of 
 mercury. On exhausting the receiver of an 
 air pump containing this vessel, the mercury 
 sunk in the jar, in consequence of the elastic 
 fluid disengaged. By degrees the liquid it- 
 self was entirely expelled, and swam on the 
 mercury on the outside. On admitting the 
 air the liquid could not enter the tube, but 
 only the mercury, and the whole elastic fluid 
 condensed, except a small bubble. Hence 
 it was concluded that chlorocyanic acid was 
 not a permanent gas, and that, in order to re- 
 main gaseous under the pressure of the air, it 
 must be mixed with another gaseous substance. 
 
 The aqueous mixture of chlorocyanic and 
 carbonic acids, has the following properties. 
 It is colourless. Its smell is very strong. A 
 very small quantity of it irritates the pituitory 
 membrane, and occasions tears. It reddens 
 litmus, is not inflammable, and does not de- 
 tonate when mixed with twice its bulk of 
 oxygen or hydrogen. Its density, determin- 
 ed by calculation, is 2.111. Its aqueous 
 solution does not precipitate nitrate of silver, 
 nor barytes water. The alkalis absorb it 
 rapidly, but an excess of them is necessary 
 to destroy its odour. If we then add an 
 acid, a strong effervescence of carbonic acid 
 is produced, and the odour of chlorocyanic 
 acid is no longer perceived. If we add an 
 excess of lime to the acid solution, ammonia 
 is disengaged in abundance. To obtain the 
 green precipitate from solution of iron, we 
 must begin by mixing chlorocyanic acid with 
 that solution. We then add a little potash, 
 and at last a little acid. If we add the 
 alkali before the iron, we obtain no green 
 precipitate. 
 
 M. Gay Lussac deduces for the composi- 
 tion of chlorocyanic acid 1 volume of car- 
 bon -f- i a volume of azote H- \ a volume 
 of chlorine ; and when decomposed by the 
 successive action of an alkali and an acid, 
 it produces 1 volume of muriatic acid gas 
 -h 1 volume of carbonic acid -f- 1 volume 
 of ammonia. The above three elements se- 
 parately constituting turn volumes, are con- 
 densed, by forming chlorocarbonic acid, into 
 one volume. And since one volume of 
 chlorine, and one volume of cyanogen, pro- 
 duce two volumes of chlorocyanic acid, the 
 density of this last ought to be the half of 
 the sum of the densities of its two constitu- 
 ents. Density of chlorine is 2.421, density 
 of cvanogen 1.801, half sum =2.111, as 
 stated above : Or the proportions by weight 
 will be 3.37 5 = a prime equivalent of cya- 
 
 nogen -|- 4.45 = a prime of chlorine, giv- 
 ing the equivalent of chlorocyanic acid = 
 7.825. 
 
 Chlorocyanic acid exhibits with potassium 
 almost the same phenomena as cyanogen. 
 The inflammation is equally slow, and the 
 gas diminishes as much in volume. 
 
 The directions given by Dr Thomson for 
 forming chlorocyanic acid in the second vo- 
 lume of his System, 5 th edition, p. 27 6, are ap- 
 parently erroneous. He seems to have mistaken 
 M. Gay Lussac’s ingenious plan for proving 
 that this new acid is not naturally gaseous, 
 for the process of obtaining the acid itself, as 
 prescribed both by him and M. Thenard. The 
 chlorocyanic and carbonic acids which come 
 over in distillation, are to be condensed in 
 water. But the requisite process of distilla- 
 tion is not even hinted at by Dr Thomson, 
 whose chlorocyanic acid must be a mixture 
 of chlorocyanic and muriatic acids.* 
 
 * Acid (Ferroprussic). Into a solution 
 of the amber-coloured crystals, usually called 
 prussiate of potash, pour hydrosulphuret of 
 barytes, as long as any precipitate falls. 
 Throw the whole on a filter, and wash the 
 precipitate with cold water. Dry it ; and 
 having dissolved 100 parts in cold water, 
 add gradually SO of concentrated sulphuric 
 acid ; agitate the mixture, and set it aside to 
 repose. The supernatant liquid is ferro- 
 prussic acid, called by Mr Porrett, w ho had 
 the merit of discovering it, ferruretted chyazic 
 acid. 
 
 It has a pale lemon yellow colour, but no 
 smell. Heat and light decompose it. Hy- 
 drocyanic acid is then formed, and white 
 ferroprussiate of iron, which soon becomes 
 blue. Its affinity for the bases enables it to 
 displace acetic acid, without heat, from the 
 acetates, and to form ferroprussiates. 
 
 When a saline solution contains a base 
 with which the ferroprussic acid forms an 
 insoluble compound, then, agreeably to Ber- 
 thollet’s principle, it is capable of supplant- 
 ing its acid. When ferroprussiate of soda is 
 exposed to voltaic electricity, the acid is 
 evolved at the positive pole, with its consti- 
 tuent iron. Mr Porrett considers this acid 
 “ as a compound of 
 
 4 atoms carbon = 30.00 
 1 atom azote = 17.50 
 1 atom iron = 1 7.50 
 1 atom hydrogen = 1.25 
 
 66.25” 
 
 This sum represents the weight of its prime 
 equivalent. Ferroprussiate of potash, and of 
 barytes, will each, therefore, according to 
 him, consist, of an atom of acid + an atom of 
 base + two atoms of water. 
 
 Dr Thomson says, in his System, “ From 
 the analysis of Mr Porrett it appears, that this 
 acid is composed of cyanogen, 8. 904 
 
 Iron, 3.500 
 
ACI 
 
 A Cl 
 
 « This approaches to three atoms of cya- 
 nogen and one atom of iron. If we suppose 
 this to be the real constitution of the acid, its 
 constituents will be 
 
 Cyanogen, 9.75 
 
 Iron, 3.50 
 
 “ But such a composition is quite irrecon- 
 cileable to the equivalent number for ferro- 
 cyanic acid, derived from the analysis of the 
 ferrocyanate of barytes. This salt, accord- 
 ing to the experiments of Mr Borrett, is com- 
 posed of ferrocyanic acid, 34.51 6.813 
 
 Barytes, 49.10 9.750 
 
 Water, 16.59 
 
 1 00.00 
 
 “ We see that by this analysis the equiva- 
 lent number for ferrocyanic acid is 6.815. 
 Now this agrees very nearly with the suppo- 
 sition that the acid is a compound of one 
 atom cyanogen ■+■ one atom iron, for the 
 weights of an atom of these bodies are as fol- 
 lows : Cyanogen, 3.25 
 
 Iron, 3.5 
 
 “ The difference between 6.75 and 6.813 
 does not exceed one per cent. I am dispos- 
 ed, therefore, to consider this as the true 
 constitution of ferrocyanic acid.” 
 
 It is a real misfortune to chemical stu- 
 dents, when so elaborate a systematist as Dr 
 Thomson so readily scatters around him pre- 
 cipitate and dogmatical judgments, on dis- 
 cussions of such importance and delicacy as 
 the present. There were no reasonable 
 grounds whatever for peremptorily deciding, 
 as he did, that the ferruretted chyazic acid 
 of Mr Porrett was a simple cyanide of iron, 
 or a compound of cyanogen and iron. The 
 mere similarity of two numbers, viz. the sum 
 of the atoms of cyanogen und iron, and the 
 equivalent of Mr Porrett’s acid, were appa- 
 rently the chief, and surely very frivolous 
 motives, for that erroneous determination. 
 
 Mr Porrett expresses himself thus, in the 
 Ann. of Phil, for September 1818. “It 
 is a great satisfaction to me to find that Dr 
 Thomson has abandoned the opinion which 
 he entertained, that the ferruretted chyazic 
 acid contained no hydrogen, and was a com- 
 pound of cyanogen and iron only ; an opi- 
 nion which induced him to name it, in his 
 System of Chemistry, the ferrocyanic acid, 
 and its salts ferrocyanates. I was perfectly 
 convinced, from many circumstances that 
 occurred during my first experiments, that 
 this opinion was erroneous, and should have 
 combated it when it appeared in his System, 
 had I been fond of controversy, or been able 
 to find time for carrying on such a course of 
 experiments, as would perhaps have been re- 
 quisite to produce conviction in others. As 
 it was, I contented myself with expressing, 
 to my chemical friends, my dissent from Dr 
 Thomson’s opinions on this subject ; and I 
 
 can venture to assure him, that whenever he 
 makes experiments with the sulphuretted 
 chyazic acid, he will be convinced that it 
 also contains hydrogen, and that the names 
 sulphocyanic, and sulphocyanates, are quite 
 inappropriate; equally so are the names pro- 
 posed by Dr Ilenry of ferroprussic, and 
 sulphuretted prussic acids, as these names 
 imply, that the prussic acid is contained in 
 these compounds, instead of being merely 
 the result of a new play of affinities when 
 they are decomposed.” 
 
 How little room there is for arbitrary de- 
 crees on every thing regarding the prussic 
 combinations, we may readily judge, when 
 we consider that M. Gay Lussac, and M. 
 Vauquelin, two of the first chemists of the 
 age, have been led, after a series of admira- 
 ble researches, to form views totally incon- 
 sistent with those resulting from Mr Borrett’s 
 very ingenious experiments. On the rela- 
 tions of prussic acid and iron, the following 
 observations by M. Vauquelin are important. 
 Hydrocyanic acid diluted with water, when 
 placed in contact with iron in a glass vessel 
 standing over mercury, quickly produces 
 prussian blue, while, at the same time, hy- 
 drogen gas is given out. The greatest 
 part of the prussian blue formed in that ope- 
 ration, remains in solution in the liquid. It 
 appears only when the liquid comes in con- 
 tact with the air. This shews us that prus- 
 sian blue, at a minimum of oxidizement, is 
 soluble in hydrocyanic acid. Dry hydro- 
 cyanic acid, placed in contact with iron 
 filings, undergoes no change in its colour 
 nor smell ; but the iron, which becomes ag- 
 glutinated together at the bottom of the ves- 
 sel, assumes a brown colour. After some 
 days, the hydrocyanic acid being separated 
 from the iron, and put in a small capsule 
 under a glass jar, evaporated without leaving 
 any residue. Therefore it had dissolved no 
 iron. Hydrocyanic acid dissolved in water, 
 placed in contact with hydrate of iron, ob- 
 tained by means of potash, and washed with 
 boiling water, furnished prussian blue imme- 
 diately without the addition of any acid. 
 Scheele has made mention of this fact. When 
 hydrocyanic acid is in excess on the oxide of 
 iron, the liquor which floats over the prus- 
 sian blue assumes, after some time, a beau- 
 tiful purple colour. The liquor, when eva- 
 porated, leaves upon the edge of the dish 
 circles of blue, and others of a purple colour, 
 and likewise crystals of this last colour. When 
 water is poured upon these substances, the 
 purple-coloured body alone dissolves, and 
 gives the liquid a fine purple colour. The 
 substance which remains undissolved is prus- 
 sian blue, which has been held in solution 
 in the hydrocyanic acid. Some drops of 
 chlorine let fall into this liquid change it to 
 blue, and a greater quantity destroys its c€- 
 
ACI 
 
 ACI 
 
 lour entirely. It is remarkable that potash 
 poured into the liquid thus deprived of its 
 colour, occasions no precipitate whatever. 
 
 Chemists will not fail to remark, from 
 these experiments, that hydrocyanic acid 
 does not torin prussian blue directly with 
 iron ; but that, on the addition of water, 
 (circumstances remaining the same) prus- 
 sian blue is produced. They will remark, 
 likewise, that cyanogen united to water dis- 
 solves iron. This is confirmed by the inky 
 taste which it acquires, by the disappearance 
 of its colour, and by the residue which it 
 leaves when evaporated ; yet prussian blue is 
 not formed. These first experiments seem 
 already to shew that prussian blue is a hy- 
 drocyanate, and not a cyanide. 
 
 The ammonia, and hydrocyanic acid, dis- 
 engaged during the whole duration of the 
 combustion of prussian blue, give a new sup- 
 port to the opinion, that this substance is a 
 hydrocyanate of iron ; and likewise the re- 
 sults which are furnished by the decomposi- 
 tion of prussian blue by heat in a retort, 
 shew clearly that it contains both oxygen 
 and hydrogen, which are most abundant to- 
 wards the end, long after any particles of 
 adhering water must have been dissipated. 
 
 We shall conclude this subject with a com- 
 parison of Dr Thomson’s and Mr Porrett’s 
 latest results. In the Annals of Phil, for 
 August 1818, we have a paper by Dr Thom- 
 son, detailing numerous experiments which 
 lie had performed to ascertain the constitu- 
 tion of prussiatc of potash and iron. “ From 
 this analysis,” says he, “ it follows that the 
 acid in the triple salt (not reckoning the 
 iron) is composed of 
 
 Carbon, 0.6579 42.51 
 
 Azote, 0.7175 46.37 
 
 Hydrogen, 0.1722 11.12 
 
 1.5476 100.00 
 
 u From the preceding analysis, we see, 
 that the triple prussiate of potash is compos- 
 ed as follows : 
 
 ... f Iron, - 15.} 
 
 tu ( Gaseous matter, 30.9 3 
 Potash, 
 
 Water, 
 
 45.90 
 
 41.64 
 1 3.00 
 
 100.54 
 
 “ We see, from the preceding analysis, 
 that one-third part of the acid consists of 
 iron, while two-thirds of its weight consists 
 of carbon, azote, and hydrogen. The small- 
 est number of atoms, which agrees nearly 
 with the preceding proportions of the ingre- 
 dients, is the following : 
 
 2 atoms carbon = 1.50 41.379 
 
 1 atom azote = 1.75 48.277 
 
 3 atoms hydrogen =: 0.375 10.344 
 
 y u 
 
 to the Royal Society in 1814 and 1815, 
 which Dr Thomson justly describes “ as very 
 ingenious and important experiments, and 
 conclusions respecting this acid,” published 
 two or three papers in the Annals of Philo- 
 sophy, one of them in September 1818, 
 already quoted, and another in October 1819. 
 The latter presents us with experiments of 
 the same nature as Dr Thomson’s, from 
 which the following inferences are drawn. 
 
 “ Collecting now from the preceding expe- 
 riments the proportions of all the constitu- 
 ents of 100 gr. of ferrochyazate of potash, 
 they appear as follows : 
 
 Potash, - - 41.68 grains. 
 
 Ferrochyazic acid 
 Water, 
 
 f Iron, 
 j Carbon, 
 j Azote, 
 
 (. Hydrogen, 
 
 12.60 
 
 22.64 
 
 13.32 
 
 0.80 
 
 13.00 
 
 104.04 
 
 Being a surplus of four grains, arising from, 
 the unavoidable inaccuracies in determining 
 experimentally, on small portions of the salt, 
 the proportions of so many constituents. 
 
 “ These inaccuracies are easily removed by 
 the application of the atomic theory ; for, by 
 taking as our guide the weights of the atoms 
 of each of the elements, we obtain the fol- 
 lowing numbers : 
 
 1 atom potash, 
 
 1 atom ferro- 
 chyazic acid 
 = 66.25 
 
 2 atoms water, 
 
 
 60. 
 
 40.34 
 
 \ atom iron, 
 
 17.5 
 
 11.76 
 
 4 do. carbon, 
 
 30.0 
 
 20.17 
 
 1 do. azote, 
 
 17.5 
 
 11.76 
 
 1 do. hydrogen, 
 
 1.250 
 
 0.84 
 
 
 22.50 
 
 15.13 
 
 1 atom ferrochyazate of potash, 148.75 100.00 
 Which doubtless gives the true proportions 
 of the several elements of this salt.” 
 
 We are now entitled to consider the atom 
 of ferrochyazic acid as composed of 
 
 4 atoms of carbon = 30.00 45.3 
 
 1 atom of azote = 17.5 26.4 
 
 1 atom of hydrogen = 1.25 1.89 
 
 1 atom of iron = 17.5 26.4 
 
 66.25 99.99” 
 
 The discordances of these two sets of re- 
 sults, are sucli as to destroy all confidence in 
 them. Thus, Dr Thomson finds 1 5 per 
 cent of iron ; and Mr Porrett’s corrected 
 quantity of that metal, per cent, is only ll|, 
 a difference quite absurd in the present state 
 of chemical analysis. Here follows a tabular 
 comparison of the acid constituents, exclusive 
 of the iron : 
 
 Dr Thomson. 
 Carbon, 42.51 
 
 Azote, 46.37 
 
 Hydrogen, 11.12 
 
 J O 7 
 
 Mr Porrett. 
 6 1 .54 
 35.90 
 2.56 
 
 3.625 100.000'-’ 
 
 Mr Porrett, besides bis communications 
 
 1 00.00 100.00 * 
 
 It lias been supposed that Mr Porrett s 
 
A Cl 
 
 ACI 
 
 new acid is nothing but a hydrocyanate or 
 prussiate of iron, which, from the mutability 
 of its constituents, is easily decomposed by 
 heat and light ; and that the only permanent 
 compound which that acid forms is in triple 
 salts. This is the old opinion, and also the 
 present opinion, of several eminent chemists. 
 These compounds we shall call ferroprus- 
 siates. M. Vauquelin and M. Thenard 
 style them ferruginous prussiates. 
 
 Ferroprussiate of ‘ potash. Into an egg- 
 shaped iron pot, brought to moderate igni- 
 tion, project a mixture of good pearl-ash and 
 dry animal matters, of which hoofs and horns 
 are best, in the proportion of two parts of 
 the former to live of the latter. Stir them 
 well with a flat iron paddle. The mixture, 
 as it calcines, wall gradually assume a pasty 
 form, during which transition it must be 
 tossed about with much manual labour and 
 dexterity. When the conversion into a che- 
 mical compound is seen to be completed by 
 the cessation of the fetid animal vapours, 
 remove the pasty mass with an iron ladle. 
 
 If this be thrown, while hot, into water, 
 some of the prussic acid will be converted 
 into ammonia, and of course the usual pro- 
 duct diminished. Allow it to cool, dissolve 
 it in water, clarify the solution by filtration 
 or subsidence, evaporate, and, on cooling, 
 yellow crystals of the ferroprussiate of pot- 
 ash will form. Separate these, redissolve 
 them in hot water, and by allowing the solu- 
 tion to cool very slowly, larger and very re- 
 gular crystals may be had. This salt is now 
 manufactured in several parts of Great Bri- 
 tain, on the large scale; and therefore the 
 experimental chemist need not incur the 
 trouble and nuisance of its preparation. No- 
 thing can exceed in beauty, purity, and per- 
 fection, the crystals of it prepared at Campsie, 
 by Messrs Mackintosh and Wilson. 
 
 An extemporaneous ferroprussiate of pot- 
 ash may at any time be made, by acting on 
 Prussian blue, with pure carbonate of pot- 
 ash, prepared from the ignited bicarbonate 
 or bitartrate. The blue should be previ- 
 ously digested, at a moderate heat, for an 
 hour or two in its own weight of sulphuric 
 acid diluted with five times its weight of 
 water ; then filtered, and thoroughly edul- 
 corated by hot water, from the sulphuric acid. 
 Of this purified prussian blue, add successive 
 portions to the alkaline solution, as long as 
 its colour is destroyed, or while it continues 
 to change from blue to brown. Filter the 
 liquid, saturate the slight alkaline excess 
 with acetic acid, concentrate by evaporation, 
 and allow it slowly to cool. Quadrangular 
 bevelled crystals of the ferroprussiate of pot- 
 ash will form. 
 
 This salt is transparent, and of a beautiful 
 I canon or topaz yellow. Its specific gravity 
 is 1.850. It has a saline, cooling, but not 
 unpleasant taste. In large crystals it pos- 
 
 sesses a certain kind of toughness, and, in 
 thin scales, of elasticity. The inclination of 
 the bevelled side to the plane of the crystal 
 is about 135°. It loses about 13 per cent 
 of water, when moderately heated ; and then 
 appears of a white colour, as happens to the 
 green copperas ; but it does not melt like 
 this salt. The crystals retain their figure 
 till the heat verges on ignition. At a red 
 heat it blackens, but, from the mode of its 
 formation, we see that even that temperature 
 is compatible with the existence of the acid, 
 provided it be not too long continued. Water 
 at 60° dissolves nearly one- third of its weight 
 of the crystals ; and at the boiling point, al- 
 most its own weight. It is not soluble in 
 alcohol ; and hence, chemical compilers, with 
 needless scrupulosity, have assigned to 
 that liquid the hereditary sinecure of screen- 
 ing the salt from the imaginary danger of 
 atmospherical action. It is not altered by 
 the air. Exposed in a retort to a strong red 
 heat, it yields prussic acid, ammonia, carbo- 
 nic acid, and a coally residue consisting of 
 charcoal, metallic iron, and potash. When 
 dilute sulphuric or muriatic acid is boiled on 
 it, prussic acid is evolved, and a very abun- 
 dant white precipitate of protoprussiate of 
 iron and potash falls, which afterwards, treat- 
 ed with liquid chlorine, yields a prussian 
 blue, equivalent to fully one-third of the salt 
 employed. Neither sulphuretted hydrogen, 
 the hydrosulphurets, nor infusion of galls, 
 produce any change on this salt. Red ox- 
 ide of mercury acts powerfully on its solution 
 at a moderate heat. Prussiate of mercury is 
 formed, which remains in solution ; while 
 peroxide of iron and metallic mercury pre- 
 cipitate. Thus we see that a portion of the 
 mercurial oxide is reduced, to carry the iron 
 to the maximum of oxidizement. 
 
 The solution of ferroprussiate of potash is 
 not affected by alkalis; but it is decomposed 
 by almost all the salts of the permanent 
 metals. The following table presents a view 
 of the colours of the metallic precipitates 
 
 thus obtained. 
 
 
 Solutions of 
 
 Give a 
 
 Manganese, 
 
 White precipitate. 
 
 Protoxide of iron, 
 
 Copious white. 
 
 Deutoxide of iron, 
 
 Copious clear blue. 
 
 Tritoxide of iron, 
 
 Copious dark blue. 
 
 Tin, 
 
 White. 
 
 Zinc, 
 
 White. 
 
 Antimony, 
 
 White. 
 
 Uranium, 
 
 Blood coloured. 
 
 Cerium, 
 
 White. 
 
 Cobalt, 
 
 Grass green. 
 
 Titanium, 
 
 Green. 
 
 Bismuth, 
 
 White. 
 
 Protoxide of copper, 
 
 White. 
 
 Deutoxide of copper, 
 
 Crimson brown. 
 
 Nickel, 
 
 Apple green. 
 
 Lead, 
 
 White. 
 
 Deutoxide of mercurv, 
 
 White. 
 
 { 
 
ACI 
 
 Solutions of Give a 
 
 Silver, White, passing to 
 
 blue, in the air. 
 Palladium, Olive. 
 
 Rhodium, Platinum, & 
 
 Gold, None. 
 
 If some of these precipitates, for example 
 those of manganese or copper, be digested 
 in a solution of potash, we obtain a ferro- 
 prussiate of potash and iron exactly similar 
 to what is formed by the action of the alka- 
 line solution on prussian blue. Those pre- 
 cipitates, therefore, contain a quantity of 
 iron. I think this fact is very favourable 
 to the theory of Mr Porrett; and scarcely 
 explicable on any other supposition. This 
 salt is composed of the following constituents, 
 by the latest analyses. 
 
 Mr Porrett. Dr Thomson. 
 
 Potash, 
 
 40.34 
 
 41.64 
 
 Ferrocyhazic acid, 
 
 44.53 
 
 45.90 
 
 Water, 
 
 15.13 
 
 13.00 
 
 
 100.00 
 
 100.54 
 
 The small excess in the latter sum, Dr 
 Thomson thinks, may be equally divided 
 among all the ingredients. We shall then 
 have for his analysis : 
 
 Potash, 41.41 
 
 Acid, 45.67 
 
 Water, 12.92 
 
 100.00 
 
 We have seen the enormous discrepancies 
 with regard to the estimates of the ultimate 
 acid constituents by these two experiment- 
 alists ; and if we consider the directness and 
 simplicity of the methods by which the pri- 
 mary constituents of the salt may be ascer- 
 tained, the above differences also seem too 
 great. By a well regulated desiccation, the 
 water of crystallization may be pretty nearly 
 determined ; and the concurring results of 
 experiment give for its quantity 1 3 per cent. 
 Now the action of nitric acid properly con- 
 joined with that of heat, should decompose 
 and dissipate the gaseous part of the acid, 
 and convert the iron into an insoluble per- 
 oxide; the weight of potash may then be 
 exactly determined, first by saturation with 
 acid, and secondly, by the weight of result- 
 ing salt. In fact had Mr Porrett adhered 
 to his experimental numbers, and not modi- 
 fied them by his atomical notions, we should 
 have had the following results, which are 
 probably correct. 
 
 Potash, 41.68 
 
 Water, 13.00 
 
 Ferrochyazic acid, 45.32 
 
 100.00 
 
 And from this real analysis, we deduce 
 directly from the proportion of potash = 
 41.68, the apparent prime equivalent of this 
 
 ACI 
 
 neutral salt to be = 14.29; or rather its 
 double, 28.58. 
 
 If we make it 28.275, then we would 
 have the following hypothetical arrangement 
 of proportions, 
 
 2 primes of potash, = 11.900 42.04 
 
 2 do. of ferrochyazic acid, = 13.000 45.96 
 
 3 do. of water, = 3.375 12.00 
 
 28.275 100.00 
 
 We have treated the subject of the ferro- 
 prussiate of potash at considerable detail, since 
 it is one of the most valuable reagents, which 
 the chemist possesses, in metallic analysis. 
 
 F err oprussiate oJ‘ soda may be prepared from 
 prussian blue, and pure soda, by a similar 
 process to that prescribed for the preceding 
 salt. It crystallizes in four-sided prisms, ter- 
 minated by dihedral summits. They are 
 yellow, transparent, have a bitter taste, and 
 effloresce, losing in a warm atmosphere 3l\ 
 per cent. At 55° they are soluble in 4^ 
 parts of water, and in a much less quantity 
 of boiling water. As the solution cools, crys- 
 tals separate. Their specific gravity is 1.458. 
 They are said by Dr John to be soluble in 
 alcohol. 
 
 Ferr oprussiate of lime may be easily form- 
 ed from prussian blue and lime-water. Its 
 solution yields crystalline grains by evapora- 
 tion. 
 
 Ferroprussiate of barytes may be formed 
 in the same way as the preceding species; 
 or much more elegantly by Mr Porrett’s 
 process, described already in treating of the 
 ferroprussic acid. Its crystals are rhom- 
 boidal prisms, of a yellow colour, and solu- 
 ble in 2000 parts of cold water, and 100 of 
 boiling water. By Mr Porrett’s second ac- 
 count of this salt, it is composed of 
 Expert. Theory. 
 
 Acid, 41.5 
 Barytes, 47.5 
 Water, 11.0 
 
 41.49 1 atom 84. 84 
 
 47.44 1 atom 97.00 
 
 10.07 2 atoms 22.64 
 
 100.0 100.00 204.48 
 
 These results were given in the Annals of 
 Philosophy for September 1818. In Dr 
 Thomson’s System, published in October 
 1817, we have the following statement: — 
 “ Mr Porrett has analyzed this salt with 
 much precision. According to his experi- 
 ments, it is composed of 
 
 Ferrocyanic acid, 34.31 
 
 Barytes, 49.10 
 
 Water, 16.59 
 
 100 . 00 ” 
 
 In the Annals for October 1819, Mr Por- 
 rett gives as its true proportions, 
 
 1 atom ferrochyazic acid, 
 
 66.25 
 
 35.66 
 
 1 atom barytes, 
 
 97. 
 
 52.22 
 
 2 atoms water, 
 
 22.5 
 
 12.12 
 
 
 185.75 
 
 100.00 
 
ACI 
 
 ACI 
 
 The discrepancies are singular, with a sub- 
 stance so unalterable and so easily ascertain- 
 ed as barytes ; for Dr Thomson’s quotation 
 gives of this substance 49. 1 per cent ; the 
 second account makes it 47.5 ; and the last 
 52.22. The quantity of barytes may be de- 
 termined absolutely, without being deduced 
 from, or entangled with, the estimate of wa- 
 ter or acid. 
 
 Ferroprussiate of strontian and magnesia 
 have also been made. 
 
 Ferroprussiate of iron . With the protox- 
 ide of iron and this acid we have a white 
 powder, which, on exposure to air, becomes 
 blue, passing into deuto ferroprussiate of iron, 
 or prussian blue. We have already described 
 the method of making the ferroprussiate of 
 potash, which is the first step in the manu- 
 facture of this beautiful pigment. This is 
 usually made by mixing together one part of 
 the ferroprussiate of potash, one part of cop- 
 peras, and four parts or more of alum, each 
 previously dissolved in w ater. Prussian blue, 
 consisting of the deutoferroprussiate of iron, 
 mixed with more or less alumina, precipitates. 
 It is afterwards dried on chalk stones, in a 
 stove. 
 
 Pure prussian blue is a mass of an ex- 
 tremely deep blue colour, insipid, inodorous, 
 and considerably denser than w'ater. Nei- 
 ther w^atCr nor alcohol has any action on it. 
 Boiling solutions of potash, soda, lime, ba- 
 rytes, and strontites decompose it; forming 
 on one hand soluble ferroprussiates with these 
 bases, and on the other a residue of brown 
 deutoxide of iron, and a yellowish brown sub- 
 ferroprussiate of iron. This last, by means of 
 sulphuric, nitric, or muriatic acids, is brought 
 back to the state of a ferroprussiate, by ab- 
 stracting the excess of iron oxide. Aqueous 
 chlorine changes the blue to a green in a few 
 minutes, if the blue be recently precipitated. 
 Aqueous sulphuretted hydrogen, reduces the 
 blue ferroprussiate to the white protoferro- 
 prussiate. 
 
 Its igneous decomposition in a retort has 
 lately been executed by M. Vauquelin with 
 minute attention. He regards it as a hy- 
 drocyanate or mere prussiate of iron; but 
 the changes he describes are very complex, 
 nor do they invalidate Mr Porrett’s opinion, 
 that it is a combination of red oxide of iron, 
 with a ferruretted acid. The general results 
 of M. Vauquelin’s analysis, were hydrocyanic 
 acid, hydrocyanate of ammonia, an oil soluble 
 in potash, crystalline needles, which contain- 
 ed no hydrocyanic acid, but were merely 
 carbonate of ammonia; and finally, a ferre- 
 ous residue slightly attracted by the magnet, 
 and containing a little undecomposed prus- 
 sian blue. If we are to regard prussian 
 blue as a deutoferroprussiate of iron, then by 
 Mr Porrett’s latest considerations, it would 
 be composed of 
 
 1 atom acid, = 
 
 r 6.625 
 
 35.1 
 
 1 atom red oxide, = 
 
 = 10.000 
 
 53.0 
 
 2 atoms water, = 
 
 : 2.250 
 
 11.9 
 
 
 18.875 
 
 100.0 
 
 Dr Thomson, after 
 Porrett to consist of 
 
 reporting i 
 
 t from Mr 
 
 Acid, 
 
 55.58 
 
 6.75 
 
 Peroxide of iron, 
 
 34.25 
 
 4.328 
 
 Water, 
 
 1 2.39 
 
 
 100.00 
 
 thinks it likely that the true composition is, 
 Ferrocyanic acid, 6.75 
 
 Peroxide of iron, 5.00 
 
 Proust, in the Annales de Chimie, vol. lx. 
 states, that 100 parts of prussian blue, with- 
 out alum, yield 0.55 of red oxide of iron by 
 combustion; and by nitric acid, 0.54. 100 
 
 of prussiate of potash and iron, he further 
 says, afford, after digestion with sulphuric 
 or nitric acid, 35 parts of prussian blue. If 
 we compare with this, Mr Porrett’s earliest 
 estimate of 34.23 per cent of ferreous per- 
 oxide, besides the third of the weight of the 
 acid, == 17.79, which being metallic iron, is 
 equivalent to 25.4 of peroxide, we shall have 
 the sum 59.65, as the quantity of peroxide 
 in 100 of Prussian blue, calling the atom of 
 iron 3.5, and of peroxyde 5.0. Or if we take 
 Dr Thomson’s correction, we have the fol- 
 lowing numbers, supposing it to consist of 
 
 1 
 
 atom acid, 
 
 6.75 
 
 48.2 
 
 1 
 
 peroxide, 5.00 
 
 35.7 
 
 2 
 
 water, 
 
 2.25 
 
 16.1 
 
 
 
 14.00 
 
 100.0 
 
 
 or perhaps 
 
 
 
 1 
 
 atom acid, 
 
 6.75 
 
 52.3 
 
 1 
 
 peroxide, 5.00 
 
 39.0 
 
 1 
 
 water, 
 
 1.125 
 
 8.7 
 
 
 
 12.875 
 
 100.0 
 
 To the 35.7 of peroxide base in the first, 
 if we add 23 for the equivalent of peroxide 
 in its acid, we have 58.7 for the whole per- 
 oxide in 100 gr. ; and to the 39 of peroxide 
 in the second, if we add 25 for the equiva- 
 lent peroxide in the acid, w'e have the sum 
 of 64 ; both, quantities considerably greater 
 than Mr Proust’s.* 
 
 * Sulphuroprussic Acin ; the sulphuretted 
 chyazic acid of Mr Porrett. 
 
 Dissolve in w ater one part of sulphuret of 
 potash, and boil it for a considerable time 
 with three or four parts of powdered prus- 
 sian blue added at intervals. Sulphuret of 
 iron is formed, and a colourless liquid con- 
 taining the new acid combined with potash, 
 mixed with hyposulphite and sulphate of 
 potash. Render this liquid sensibly sour, by 
 the addition of sulphuric acid. Continue 
 the boiling for a little, and when it cools, add 
 a little peroxide of manganese in fine pow- 
 
ACI 
 
 ACI 
 
 der, which will give the liquid a fine crim- 
 son colour. To the filtered liquid add a so- 
 lution containing persulphate of copper, and 
 protosulphate of iron, in the proportion of 
 two of the former salt to three of the latter, 
 until the crimson colour disappears. Sul- 
 phuroprussiate of copper falls. Boil this 
 with a solution of potash, which will separate 
 the copper. Distil the liquid mixed with 
 sulphuric acid in a glass retort, and the pe- 
 culiar acid will come over. By saturation 
 with carbonate of barytes, and then throwing 
 down this by the equivalent quantity of sul- 
 phuric acid, the sulphuroprussic acid is ob- 
 tained pure. 
 
 It is a transparent and colourless liquid, 
 possessing a strong odour, somewhat rcsem- 
 bliag acetic acid. Its specific gravity is only 
 1.022. It dissolves a little sulphur at a boil- 
 ing heat. It then blackens nitrate of silver; 
 but the pure acid throws down the silver 
 white. By repeated distillations sulphur is 
 separated and the acid is decomposed. Mr 
 Porrctt, in the Annals of Phil, for May 
 1819, states the composition of this acid, as 
 it exists in the sulphuretted chyazate of cop- 
 per, to be 
 
 2 atoms sulphur, = 4.000 
 
 2 carbon, = 1.508 
 
 1 azote, = 1.754 
 
 1 hydrogen, = 0. 132 
 
 7.394 
 
 This is evidently an atom of the hydrocy- 
 anic acid of M. Gay Lussac, combined with 
 2 of sulphur. If to the above we add 9. for 
 an atom of protoxide of copper, we have 
 16.594 for the prime equivalent of the met- 
 allic salt. When cyanogen and sulphuretted 
 hydrogen were mixed together by M. Gay 
 Lussac in his researches on the prussic prin- 
 ciple, he found them to condense into yel- 
 low acicular crystals. Mr Porrctt has since 
 remarked, that these crystals are not formed 
 when the two gases are quite dry, but that 
 they are quickly produced if a drop of water 
 is passed up into the mixture. He does not 
 think their solution in water corresponds 
 to liquid sulphuretted chyazic acid ; it does 
 not change the colour of litmus ; it has no 
 effect on solutions of iron ; it contains nei- 
 ther prussic nor sulphuretted chyazic acid, 
 yet this acid is formed in it when it is mixed 
 first with an alkali and then with an acid. 
 The same treatment does not form any prus- 
 sic acid. 
 
 The facility with which the atomic hy- 
 pothesis may be twisted to any theoretical 
 perversion, is well exemplified in the follow- 
 ing passage : — “ The weight of an atom ot 
 hydrocyanic acid is 3.375, and that of an 
 atom of sulphur 2. But 6.328 (“ Mr Por- 
 rett’s first proportion of sulphur”) not being 
 a multiple of two, this statement does not 
 accord well with the atomic theory. It agrees 
 
 much better with that theory, if we suppose 
 the acid to be a compound of sulphur and 
 cyanogen. Its constitution will then be, 
 Sulphur, 1.20 100 6.09 
 
 Cyanogen, 0.64 53.3 5.25 
 
 Thus we see that it is a compound of 1 
 atom of cyanogen and 5 atoms of sulphur.” 
 Thomson’s System, Vol. ii. p. 292. 
 
 This procedure looks more like legerde- 
 main than philosophical research. Had Dr 
 . Thomson contented himself with saying that 
 the statement of Mr Porrctt did not accord 
 with the atomic theory, he would have said 
 right; and there he should have left the 
 matter, or have instituted experiments to settle 
 the point. But to create a new genus of 
 compounds, sulphur and cyanogen, and erect 
 it into a new acid, on such a frivolous con- 
 ceit, throws an air of ridicule on the science. 
 Nay further, the Doctor describing M. Gay 
 Lussac’s crystalline compound of sulphuret- 
 ted hydrogen and cyanogen, says, that “ as 
 far as its description goes, this substance 
 agrees exactly with the sulphuretted chyazic 
 acid of Mr Porrctt. If we abstract the hy- 
 drogen of the sulphuretted hydrogen, which 
 probably did not enter into the composition 
 of the compound, it will he a compound of 
 1 atom cyanogen, and 1^ atom sulphur, or 
 in whole numbers of 2 atoms cyanogen and 
 3 atoms sulphur. So that it will contain 
 just half tiie quantity of sulphur which Mr 
 Porrctt found.” M. Gay Lussac expressly 
 states that the yellow needles obtained from 
 the joint action of cyanogen and sulphuretted 
 hydrogen, are “ composed of one volume of 
 cyanogen, and 1^ volume of sulphuretted 
 hydrogen*” So that instead of containing 
 no hydrogen, this substance contains half a 
 volume more than hydrocyanic acid. 
 
 The sulphuroprussiates have been examin- 
 ed only by Mr Porrett. That of the red ox- 
 ide of iron is a deliquescent salt, of a beauti- 
 ful crimson colour. It may be obtained in a 
 solid form by an atmosphere artificially dried. 
 A concise account of these salts is given in 
 the 5th Vol. of the Annals of Philos.* 
 
 * Acid (Purpuric). The excrements of 
 the serpent Boa Constrictor , consist of pure 
 lithic acid. Dr Prout found that on digest- 
 ing; this substance thus obtained, or from 
 urinary calculi, in dilute nitric acid, an effer- 
 vescence takes place, and the lithic acid is 
 dissolved, forming a beautiful purple liquid. 
 The excess of nitric acid being neutralized 
 with ammonia, and the whole concentrated 
 by sIoav evaporation, the colour of the solu- 
 tion becomes of a deeper purple, and dark 
 red granular crystals, sometimes of a green- 
 ish hue externally, soon begin to separate in 
 abundance. These crystals are a compound 
 of ammonia with the acid principle in ques- 
 tion. The ammonia was displaced by digest- 
 ing the salt in a solution of caustic potash, 
 till the red colour entirely disappeared. This 
 
ACI 
 
 ACI 
 
 alkaline solution was then gradually dropped 
 into dilute sulphuric acid, which, uniting 
 with the potash, left the acid principle in a 
 state of purity. 
 
 This acid principle is likewise produced 
 from lithic acid by chlorine, and also, but 
 with more difficulty, by iodine. Dr Trout, 
 the discoverer of this new acid has, at the 
 suggestion of Dr Wollaston, called it pur- 
 puric acid, because its saline compounds have 
 for the most part a red or purple colour. 
 
 This acid, as obtained by the preceding 
 process, usually exists in the form of a very 
 fine powder, of a slightly yellowish or cream 
 colour ; and when examined with a magni- 
 fier, especially under water, appears to pos- 
 sess a pearly lustre. It has no smell, nor 
 taste. Its spec. grav. is considerably above 
 water. It is scarcely soluble in water. One- 
 tenth of a grain, boiled for a consider- 
 able time in 1000 grains of water, was 
 not entirely dissolved. The water, however, 
 assumed a purple tint, probably, Dr Prout 
 thinks, from the formation of a little purpu- 
 rate of ammonia. Purpuric acid is insolu- 
 ble in alcohol and ether. The mineral acids 
 dissolve it only when they are concentrated. 
 It does not affect litmus paper. By ignit- 
 ing it in contact with oxide of copper, he de- 
 termined its composition to be, 
 
 2 atoms hydrogen, 
 
 0.250 
 
 4.54 
 
 3 carbon, 
 
 1 .500 
 
 27.27 
 
 2 oxygen, 
 
 2.000 
 
 36.36 
 
 1 azote, 
 
 1.750 
 
 SI. 81 
 
 
 5.50 
 
 99.98 
 
 Purpuric acid combines with the 
 
 alkalis, 
 
 alkaline earths, and metallic oxides. It is 
 capable of expelling carbonic acid from the 
 alkaline carbonates by the assistance of heat, 
 and does not combine with any other acid. 
 These are circumstances sufficient, as Dr 
 Wollaston observed, to distinguish it from an 
 oxide, and to establish its character as an acid. 
 
 Purpurate of ammonia crystallizes in qua- 
 drangular prisms, of a deep garnet red co- 
 lour. It is soluble in 1500 parts of water 
 at G0°, and in much less at the boiling tem- 
 perature. The solution is of a beautiful 
 deep carmine, or rose-red colour. It has a 
 slightly sweetish taste, but no smell. Pur- 
 purate of potash is much more soluble ; of 
 soda is less ; that of lime is nearly insoluble ; 
 those of strontian and lime are slightly solu- 
 ble. All the solutions have the characteristic 
 colour. Purpurate of magnesia is very so- 
 luble ; and in solution, of a very beautiful 
 colour. A solution of acetate of zinc pro- 
 duces with purpurate of ammonia a solution 
 and precipitate of a beautiful gold yellow 
 colour ; and a most brilliant iridescent pel- 
 licle, in which green and yellow predominate, 
 forms oji the surface of the solution. Dr 
 Prout conceives the salts to be anhydrous, or 
 
 void of water, and composed of two atoms 
 
 47 
 
 of acid and one of base. The purpuric acid 
 and its compounds probably constitute the 
 bases of many animal and vegetable colours. 
 The well known pink sediment which gene- 
 rally appears in the urine of those labouring 
 under febrile affections, appears to owe its 
 colour chiefly to the purpurate of ammonia, 
 and perhaps occasionally to the purpurate of 
 soda. 
 
 The solution of lithic acid in nitric acid 
 stains the skin of a permanent colour, which 
 becomes of a deep purple on exposure to the 
 sun. These apparently sound experimental 
 deductions of Dr Prout, have been called in 
 question by M. Vauquelin ; but Dr Prout 
 ascribes M. Vauquelin’s failure, in attempt- 
 ing to procure purpuric acid, to his having 
 operated on an impure lithic acid. We 
 think entire confidence may be put in Dr 
 Prout’s experiments. He says that it is dif- 
 ficult to obtain purpuric acid from the lithic 
 acid of urinary concretions. — Phil. Trans . 
 for 1818, and Annals of Phil. vol. 14.* 
 
 Acid (Pyrolignous). In the destruc- 
 tive distillation of any kind of w ood, an acid 
 is obtained, which was formerly called acid 
 spirit of wood, and since pyrolignous acid. 
 * Fourcroy and Vauquelin shewed that this 
 acid w'as merely the acetic, contaminated with 
 empyreumatic oil and bitumen. See Acetic 
 Acid. 
 
 Under acetic acid wall be found a full ac- 
 count of the production and purification of 
 pyrolignous acid. We shall add here, that 
 M. Monge discovered, about two years ago, 
 that this acid has the property of preventing 
 the decomposition of animal substances. It 
 is sufficient to plunge meat for a few mo- 
 ments into this acid, even slightly empyreu- 
 matic, to preserve it as long as you please. 
 “ Putrefaction,” it is said, “ not only stops, 
 but retrogrades.” To the empyreumatic oil 
 a part of this effect has been ascribed ; and 
 hence has been accounted for, the agency of 
 smoke in the preservation of tongues, hams, 
 herrings, &c. Dr Jorg of Leipsic has en- 
 tirely recovered several anatomical prepara- 
 tions from incipient corruption by pouring 
 this acid over them. With the empyreuma- 
 tic oil or tar he has smeared pieces of flesh 
 already advanced in decay, and notwithstand- 
 ing that the weather was hot, they soon be- 
 came drv and sound. To the above state- 
 ments Mr Ramsay of Glasgow, an eminent 
 manufacturer of pyrolignous acid, and well 
 known for the purity of his vinegar from 
 wood, lias recently added the following facts 
 in the 5th number of the Edinburgh Philo- 
 sophical Journal. If fish be simply dipped 
 in redistilled pyrolignous acid, of the spe- 
 cific gravity 1.012, and afterwards dried in 
 the shade, they preserve perfectly well. On 
 boiling herrings treated in this manner, they 
 were very agreeable to the taste, and bad 
 nothing of the disagreeable empyreuma 
 
ACI 
 
 A Cl 
 
 which those of his earlier experiments had, 
 which were steeped for three hours in the 
 acid. A number of very fine haddocks were 
 cleaned, split, and slightly sprinkled with salt 
 for six hours. After being drained, they 
 were dipped for about three seconds in py- 
 rolignous acid, then hung up in the shade 
 for six days. On being broiled, the fish were 
 of an uncommonly fine flavour, and deli- 
 cately white. Beef treated in the same way, 
 had the same flavour as Hamburgh beef, 
 and kept as well. Mr Ramsay has since 
 found, that his perfectly purified vinegar, 
 specific gravity 1.034, being applied by a 
 cloth or sponge to the surface of fresh meat, 
 makes it keep sweet and sound for several 
 days longer in summer than it otherwise 
 would. Immersion for a minute in his pu- 
 rified common vinegar, specific gravity 1 .009, 
 protects beef and fish from all taint in sum- 
 mer, provided they be hung up and dried in 
 the shade. When, by frequent use, the py- 
 rolignous acid has become impure, it may be 
 clarified by beating up twenty gallons of it 
 with a dozen of eggs in the usual manner, 
 and heating the mixture in an iron boiler. 
 Before boiling, the eggs coagulate, and bring 
 the impurities to the surface of the boiler, 
 which are of course to be caiefully skimmed 
 off. 4 he acid must immediately be with- 
 drawn from the boiler, as it acts on iron. * 
 
 * Acid (Pvrolithic). When uric acid 
 
 concretions are distilled in a retort, silvery 
 white plates sublime. These are pyrolithate 
 of ammonia. When their solution is poured 
 into that of subacetate of lead, a pyrolithate 
 of lead falls, which, after proper washing, is 
 to be shaken with water, and decomposed by 
 sulphuretted hydrogen gas. The superna- 
 tant liquid is now a solution of pyrolithic 
 acid, which yields small acicular crystals by 
 evaporation. By heat these melt and su- 
 blime in white needles. They are soluble in 
 four parts of cold water, and the solution 
 reddens vegetable blues. Boiling alcohol 
 dissolves the acid, but on cooling it deposits 
 it, in small white grains. Nitric acid dis- 
 solves without changing it. Hence, pyro- 
 lithic is a different acid from the lithic, which, 
 by nitric acid, is convertible into purpurate 
 of ammonia. 1 he pyrolithate of lime crys- 
 tallizes in stalactites, which have a bitter and 
 slightly acrid taste. It consists of 91.4 acid 
 + 8 ' 6 lime. Pyrolithate of barytes is a 
 nearly insoluble powder. The salts of pot- 
 ash, soda, and ammonia, are soluble, and the 
 former two crystal lizable. At a red heat, 
 
 and by passing it over ignited oxide of cop- 
 per, it is decomposed, into oxygen 44.32, 
 carbon 28.29, azote 16.84, hydrogen 10. * 
 
 * Acid (Pyromalic). When malic or 
 sorbic acid, for they are the same, is distilled 
 in a retort, an acid sublimate, in white 
 needles, appears in the neck of the retort, 
 and an acid liquid distils into the receiver. 
 
 This liquid, by evaporation affords crystals, 
 constituting a peculiar acid, to which the 
 above name has been given. 
 
 They are permanent in the air, melt at 
 118° Fahr., and on cooling, form a pearl 
 coloured mass of diverging needles. When 
 thrown on red hot coals, they completely 
 evaporate in an acrid, cough-exciting smoke. 
 Exposed to a strong heat in a retort, they 
 are partly sublimed in needles, and are partly 
 decomposed. '1 hey are very soluble in strong 
 alcohol, and in double their weight of water, 
 at the ordinary temperature. The solution 
 reddens vegetable blues, and yields white 
 flocculent precipitates with acetate of lead 
 and nitrate of mercury ; but produces no 
 precipitate with lime water. By mixing it 
 with barytes water, a white powder falls, 
 which is redissolved by dilution with wa- 
 ter, after which, by gentle evaporation, the 
 pvromalate of barytes may be obtained in 
 silvery plates. These consist of 100 acid, 
 and 183.142 barytes, or in prime equivalents 
 of 5.24 + 9.70. 
 
 Pyromalate of potash may be obtained in 
 feather formed crystals, which deliquesce. 
 Pyromalate of lead forms first a white floccu- 
 lent precipitate, soon passing into a semi- 
 transparent jelly, which by dilution and fil- 
 tration from the water, yields brilliant pearly 
 looking needles. The white crystals that 
 sublime in the original distillation, are con- 
 sidered by M. Lassaigne as a peculiar acid.* 
 
 * Acid (Pyrotartaric). Into a coated 
 glass retort introduce tartar, or rather tar- 
 taric acid, till it is half full, and fit to it a 
 tubulated receiver. Apply heat, which is to 
 be gradually raised to redness. Pyrotartaric 
 acid of a brown colour, from impurity, is 
 found in the liquid products. We must filter 
 these through paper previously wetted, to se- 
 parate the oily matter. Saturate the liquid 
 with carbonate of potash ; evaporate to dry- 
 ness ; redissolve, and filter through clean 
 moistened paper. By repeating this process 
 of evaporation, solution, and filtration, seve- 
 ral times, we succeed in separating all the 
 oil. The dry salt is then to be treated in a 
 glass retort, at a moderate heat, with dilute 
 sulphuric acid. There passes over into the 
 receiver, first of all a liquor containing evi- 
 dently acetic acid ; but towards the end of 
 the distillation, there is condensed in the 
 vault of the retort, a white and foliated sub- 
 limate, which is the pyrotartaric acid, per- 
 fectly pure. 
 
 It has a very sour taste, and reddens 
 powerfully the tincture of turnsole. Heated 
 in an open vessel, the acid rises in a white 
 smoke, without leaving the charcoaly resi- 
 duum, which is left in a retort. It is very 
 soluble in water, from which it is separated 
 in crystals by spontaneous evaporation. The 
 bases combine with it, forming pyrotartarates, 
 of which those of potash, soda, ammonia 
 
ACI 
 
 ACI 
 
 barytes, strontites, and lime, are very solu- 
 ble. That of potash is deliquescent, soluble 
 in alcohol, capable of crystallizing in plates, 
 like the acetate of potash. This pyrotar- 
 tarate precipitates both acetate of lead and 
 nitrate of mercury, whilst the acid itself pre- 
 cipitates only the latter. Rose is the disco- 
 verer of this acid, which was formerly con- 
 founded with the acetic.* 
 
 * Acid (Rosasic). There is deposited 
 from the urine of persons labouring under 
 intermittent and nervous fevers, a sediment 
 of a rose colour, occasionally in reddish crys- 
 tals. This was first discovered to be a pe- 
 culiar acid by M. Proust, and afterwards 
 examined by M. Vauquelin. This acid is 
 solid, of a lively cinnabar hue, without smell, 
 w T ith a faint taste, but reddening litmus very 
 sensibly. On burning coal it is decomposed 
 into a pungent vapour, which has not the 
 odour of burning animal matter. It is very 
 soluble in water, and it even softens in the 
 air. It is soluble in alcohol. It forms solu- 
 ble salts with potash, soda, ammonia, barytes, 
 strontites, and lime. It gives a slight rose- 
 coloured precipitate with acetate of lead. It 
 also combines with lithic acid, forming so 
 intimate a union, that the lithic acid in pre- 
 cipitating from urine carries the other, though 
 a deliquescent substance, down along with it. 
 It is obtained pure by acting on the sedi- 
 ment of urine with alcohol. See Acid 
 (Purpuric).* 
 
 * Acid (Saclactic). See Acid (Mucic).* 
 
 * Acid (Sebacic). Subject, to a consider- 
 able heat, 7 or 8 pounds of hog’s lard, in a 
 stoneware retort capable of holding double 
 the quantity, and connect its beak by an 
 adopter with a cooled receiver. The con- 
 densible products are chiefly fat, altered by 
 the fire, mixed with a little acetic and sebacic 
 acids. Treat this product with boiling wa- 
 ter several times, agitating the liquor, allow- 
 ing it to cool, and decanting each time. 
 Pour at last into the watery liquid, solution 
 of acetate of lead in excess. A white floc- 
 culent precipitate of sebate of lead will in- 
 stantly fall, which must be collected on a 
 filter, washed, and dried. Put the sebate of 
 lead into a phial, and pour upon it its own 
 weight of sulphuric acid, diluted with five or 
 six times its weight of water. Expose this 
 phial to a heat of about 212°. The sul- 
 phuric acid combines with the oxide of lead, 
 and sets the sebacic acid at liberty. Filter 
 the whole while hot. As the liquid cools, 
 the sebacic acid crystallizes, which must be 
 washed, to free it completely from the adher- 
 ing sulphuric acid. Let it be then dried at 
 a gentle heat. 
 
 The sebacic acid is inodorous ; its taste is 
 slight, but it perceptibly reddens litmus paper; 
 its specific gravity is above that of water, and 
 its crystals are small white needles of little 
 coherence. Exposed to heat, it melts like 
 
 fat, is decomposed, and partially evaporated. 
 The air has no effect upon it. It is much 
 more soluble in hot than in cold water ; 
 hence boiling water saturated with it, assumes 
 a nearly solid consistence on cooling. Al- 
 cohol dissolves it abundantly at ordinary tem- 
 perature. 
 
 With the alkalis it forms soluble neutral 
 salts ; but if we pour into their concentrated 
 solutions, sulphuric, nitric, ©r muriatic acids, 
 the sebacic is immediately deposited in large 
 quantity. It affords precipitates with the 
 acetates and nitrates of lead, mercury, and 
 silver. 
 
 Such is the account given by M. Thenard 
 of this acid, in the 3d volume of his Traite 
 de Chimie, published in 1815. Berzelius, 
 in 1806, published an elaborate dissertation, 
 to prove that M. Thenard’s new sebacic acid 
 was only the benzoic, contaminated by the 
 fat, from which, however, it may be freed, 
 and brought to the state of common benzoic 
 acid. M. Thenard takes no ntftice of M. 
 Berzelius whatever, but concludes his account 
 by stating, that it has been known only for 
 twelve or thirteen years, and that it must not 
 be confounded with the acid formerly call- 
 ed sebacic, which possesses a strong disgust- 
 ing odour, and was merely acetic or muriatic 
 acid ; or fat, which had been changed in some 
 way or other, according to the process used 
 in the preparation.* 
 
 * Acid (Sorbic). The acid of apples, 
 called malic, may be obtained most conve- 
 niently and in greatest purity from the ber- 
 ries of the mountain ash, called sorbus, or 
 pyrus aucupciria, and hence the present 
 name, sorbic acid. This was supposed to be 
 a new and peculiar acid by Mr Donovan and 
 M. Vauquelin, who wrote good dissertations 
 upon it. But it now appears that the sorbic 
 and pure malic acids are identical. 
 
 Bruise the ripe berries in a mortar, and 
 then squeeze them in a linen bag. They 
 yield nearly half their weight of juice, of the 
 specific gravity of 1.077. This viscid juice, 
 by remaining for about a fortnight in a warm 
 temperature, experiences the vinous ferment- 
 ation, and would yield a portion of alcohol. 
 By this change, it has become bright, clear, 
 and passes easily through the filter, while the 
 sorbic acid itself is not altered. Mix the 
 clear juice with filtered solution of acetate of 
 lead. Separate the precipitate on a filter, 
 and wash it with cold water. A large quan- 
 tity of boiling water is then to be poured 
 upon the filter, and allowed to drain into 
 glass jars. At the end of some hours, the 
 solution deposits crystals of great lustre and 
 beauty. Wash these with cold water, dis- 
 solve them in boiling water, filter, and crys- 
 tallize. Collect the new crystals, and boil 
 them for half an hour in 2.3 times their 
 weight of sulphuric acid, specific gravity 
 1 .090, supplying water as fast us it evapo- 
 
ACI 
 
 ACI 
 
 rates, and stirring the mixture diligently with 
 a glass rod. 1 he clear liquor is to be de- 
 canted into a tall narrow glass jar, and while 
 still hot, a stream of sulphuretted hydrogen is 
 to be passed through it. When the lead has 
 been all thrown down in a sulphuret, the 
 liquid is to be filtered, and then boiled in an 
 open vessel to dissipate the adhering sul- 
 phuretted hydrogen. It is now a solution of 
 sorbic acid. 
 
 When it is evaporated to the consistence 
 of a syrup, it forms mammelated masses of a 
 crystalline structure. It still contains a con- 
 siderable quantity of water, and deliquesces 
 when exposed to the air. Its solution is 
 transparent, colourless, void of smell, but 
 powerfully acid to the taste. Lime and 
 barytes waters are not precipitated by solution 
 of tire sorbic acid, although the sorbate of 
 lime is nearly insoluble. One of the most 
 characteristic properties of this acid, is the 
 precipitate which it gives with the acetate of 
 lead, which is at first white and flocculent, 
 but afterwards assumes a brilliant crystalline 
 appearance. With potash, soda, and ammo- 
 nia, it forms crystal lizable salts containing 
 an excess of acid. That of potash is deli- 
 quescent. Sorbate of barytes consists, accord- 
 ing to M. Vauquelin, of 47 sorbic acid, and 
 5-3 barytes in 100. Sorbate of lime well 
 dried, appeared to be composed of 67 acid 
 -f-33 lime = 100. Sorbate of lead, which 
 in solution, like most of the other sorbates, 
 retains an acidulous taste, consists in the 
 dried state of S3 acid 67 oxide of lead in 
 100. The ordinary sorbate contains 12.5 per 
 cent of water. M. Vauquelin says that Mr 
 Donovan was mistaken in supposing that he 
 had obtained super and subsorbates of lead. 
 There is only one salt with this base, accord- 
 ing to M. Vauquelin. It is nearly insoluble 
 in cold water ; but a little more so in boiling 
 water : as it cools it crystallizes in the beau- 
 tiful white, brilliant, and shining needles, of 
 which vve have already spoken. A remark- 
 able phenomenon occurs, when sorbate of 
 lead is boiled in water. Whilst one part of 
 the salt saturates the water, the other part, 
 for want of a sufficient quantity of fluid to 
 dissolve it, is partially melted, and is at first 
 kept on the surface by the force of ebullition, 
 but after some time fails to the bottom, and 
 as it cools becomes strongly fixed to the vessel. 
 
 To procure sorbic acid, M. Braconnot sa- 
 turates with chalk the juice of the scarcely 
 ripe berries, evaporates to the consistence of 
 a syrup, removing the froth ; and a granular 
 sorbate falls, which he decomposes by car- 
 bonate of soda. The sorbate of soda is freed 
 from colouring matter by a little lime, strain- 
 ed, freed from lime by carbonic acid gas, 
 and decomposed by subacetate of lead, and 
 treated as above. 
 
 M. Vauquelin analyzed the acid, in the dry 
 sorbates of copper and lead. 
 
 The following are its constituents : 
 Hydrogen, 16.8 
 Carbon, 28.3 
 Oxygen, 54.9 
 
 100.0 
 
 M. Vauquelin’s analysis of the sorbate of 
 lead gives 7.0 for the prime equivalent of 
 this acid ; the sorbate of lime gives 7.230 ; 
 and the sorbate of barytes 8.6. If we take 
 that of lime for the standard, as it was the 
 only one quite neutral, we shall have the 
 following relation of prime equivalents : 
 
 Theory. Experiment. 
 
 4 of oxygen 
 
 = 4.00 
 
 53.3 
 
 54.9 
 
 3 of carbon 
 
 = 2.25 
 
 30.0 
 
 28.3 
 
 10 of hydrogen 
 
 = 1.25 
 
 16.7 
 
 16.8 
 
 
 7.50 
 
 100.0 
 
 100.0 
 
 The approximation of these sets of propor- 
 tions, illustrates and confirms the accuracy of 
 M. Vauquelin’s researches. 
 
 The calcareous salt having been procured in 
 a neutral state, by the addition of carbonate of 
 potash to its acidulous solution, it might rea- 
 dily be mixed with as much carbonate of lime 
 as would diminish the apparent equivalent of 
 acid from 7.50 to 7.2.30; especially as the 
 barytic compound gives no less than 8.6. 
 Had the composition of the sorbate of lime 
 been 67.7 and 32.3, instead of 67 and 33, 
 the prime equivalent of the acid would come 
 out 7.5, as its ultimate analysis indicates. 
 
 As the pure sorbic acid appears to be with- 
 out odour, without colour, and of an agree- 
 able taste, it might be substituted for the tar- 
 taric and citric, in medicine and the arts. 
 
 The same acid may be got from apples, 
 in a similar way. * 
 
 Acid (Suberic). This acid was obtained 
 by Brugnatelli from cork, and afterwards 
 more fully examined by Bouillon la Grange. 
 To procure it, pour on cork, grated to pow- 
 der, six times its weight of nitric acid, of the 
 specific gravity of 1.26, in a tubulated retort, 
 and distil the mixture with a gentle heat, as 
 long as any red fumes arise. As the distilla- 
 tion advances, a yellow matter, like wax, ap- 
 pears on the surface of the liquid in the re- 
 tort. While its contents continue hot, pour 
 them into a glass vessel, placed on a sand- 
 heat, and keep them continually stirring with 
 a glass rod ; by which means the liquid will 
 gradually grow thicker. As soon as white 
 penetrating vapours appear, let it be remov- 
 ed from the sand-beat, and kept stirring till 
 cold. Thus an orange- coloured mass will 
 be obtained, of the consistence of honey, 
 of a strong sharp smell while hot, and a 
 peculiar aromatic smell when cold. On this, 
 pour twice its weight of boiling water, apply 
 heat till it liquefies, and filter. As the filter- 
 ed liquor cools, it deposits a powdery sedi- 
 ment, and acquires a thin pellicle. Separate 
 
ACI 
 
 ACI 
 
 the sediment by filtration, and evaporate the 
 fluid nearly to dryness. The mass thus ob- 
 tained is the suberic acid, which may be pu- 
 rified by saturating with an alkali, and pre- 
 cipitating by an acid, or by boiling it with 
 charcoal powder. 
 
 * M. Chevreul obtained the suberic acid 
 by mere digestion of the nitric acid on grat- 
 ed cork, without distillation, and purified it 
 by washing with cold water. 1 2 parts of 
 cork may be made to yield 1 of acid. When 
 pure, it is white and pulverulent, having a 
 feeble taste, and little action on litmus. It 
 is soluble in 80 parts of water at 55 \° F. 
 and in 38 parts at 140°. It is much more 
 soluble in alcohol, from which water throws 
 dowui a portion of the suberic acid. It oc- 
 casions a white precipitate when poured into 
 acetate of lead, nitrates of lead, mercury, and 
 silver, muriate of tin, and protosulphate of 
 iron. It affords no precipitate with solu- 
 tions of copper or zinc. The suberates of 
 potash, soda, and ammonia, are very soluble. 
 The two latter may be readily crystallized. 
 Those of barytes, lime, magnesia, and alu- 
 mina, are of sparing solubility. * 
 
 Acid (Succinic). It has long been known 
 that amber, when exposed to distillation, 
 affords a crystallized substance, which sub- 
 limes into the upper part of the vessel. 
 Before its nature was understood it w'as call- 
 ed salt oJ‘ amber ; but it is now known to be 
 a peculiar acid, as Boyle first discovered. 
 The crystals are at first contaminated w'ith a 
 little oil, which gives them a brownish co- 
 lour ; but they may be purified by solution 
 and crystallization, repeated as often as ne- 
 cessary, when they will become transparent 
 and shining. Pott recommends to put on 
 the filter, through w'hich the solution is pass- 
 ed, a little cotton previously wetted wn'th oil 
 of amber. Their figure is that of a triangu- 
 lar prism. Their taste is acid, and they 
 redden the blue colour of litmus, but not 
 that of violets. They are soluble in less 
 than two parts of boiling alcohol, in two 
 parts of boiling water, and in twenty-five of 
 cold water. 
 
 M. Planche of Paris observes, that a con- 
 siderable quantity might be collected in mak- 
 ing amber varnish, as it sublimes while the 
 amber is melting for this purpose, and is 
 wasted. 
 
 * Several processes have been proposed 
 for purifying this acid : that of Richter ap- 
 pears to be the best. The acid being dis- 
 solved in hot water, and filtered, is to be 
 saturated with potash or soda, and boiled 
 with charcoal, which absorbs the oily matter. 
 The solution being filtered, nitrate of lead is 
 added; whence results an insoluble succinate 
 of lead, from which, by digestion in the equi- 
 valent quantity of sulphuric acid, pure succi- 
 nic acid is separated. Nitrate or muriate of 
 
 barytes, will shew whether any sulphuric 
 acid remains mixed with the succinic solu- 
 tion ; and if so, it may be withdrawn by di- 
 gesting the liquid wdth a little more succinate 
 of lead. Pure succinic acid may be obtained 
 by evaporation, in white transparent prisma- 
 tic crystals. Their taste is somewhat sharp, 
 and they redden powerfully tincture of turn- 
 sole. Heat melts and partially decomposes 
 succinic acid. Air has no effect upon it. It 
 is soluble injboth water and alcohol, and much 
 more so when they are heated. Its prime 
 equivalent, by Berzelius, is 6.2G ; and it is 
 composed of 4.. 51 hydrogen, 47. G carbon, 
 47.888 oxygen in 100, or 2 + 4 -f 3 primes.* 
 
 With barytes and lime the succinic acid 
 forms salts but little soluble; and w r ith mag- 
 nesia it unites into a thick gummy substance* 
 The succinates of potash and ammonia are 
 crystallizable and deliquescent ; that of soda 
 does not attract moisture. The succinate of 
 ammonia is useful in analysis to separate 
 oxide of iron. 
 
 * Acid (Sulphovinic). The name given 
 by Vogel to an acid, or class of acids, which 
 may be obtained by digesting alcohol and 
 sulphuric acid together w r ith heat. It seems 
 probable, that this acid is merely the hypo- 
 sulphuric, combined with a peculiar oily 
 matter. * 
 
 Acid (Sulphuric). When sulphur is 
 heated to 1 80° or 1 90° in an open vessel, it 
 melts, and soon afterward emits a blueish 
 flame, visible in the dark, but which, in 
 open day light, has the appearance of a 
 white fume. This flame has a suffocating 
 smell, and has so little heat that it will not 
 set fire to flax, or even gunpowder, so that 
 in this way the sulphur may be entirely con- 
 sumed out of it. If the heat be still aug- 
 mented, the sulphur boils, and suddenly 
 bursts into a much more luminous flame, the 
 same suffocating vapour still continuing to 
 be emitted. 
 
 The suffocating vapour of sulphur is im- 
 bibed by water, with which it forms the 
 fluid formerly called volatile vitriolic, now 
 sulphurous acid. If this fluid be exposed 
 for a time to the air, it loses the sulphureous 
 smell it had at first, and the acid becomes 
 more fixed. It is then the fluid which was 
 formerly called the spirit of vitriol. Much 
 of the water may be driven off by heat, and 
 the dense acid which remains is the sulphu- 
 ric acid, commonly called oil of vitriol ; a 
 name which was probably given to it from 
 the little noise it makes when poured out, 
 and the unctuous feel it has when rubbed 
 between the fingers, produced by its corrod- 
 ing and destroying the skin, with which it 
 forms a soapy compound. 
 
 The stone or mineral called martial py- 
 rites, wdiich consists for the most part of 
 sulphur and iron, is found to be converted 
 
ACI 
 
 ACI 
 
 into the salt vulgarly called green vitriol , but 
 more pioperly sulphate ot iron, by exposure 
 to air and moisture. In this natural process 
 the pyrites breaks and falls in pieces ; and if 
 the change take place rapidly, a consider- 
 able increase of temperature follows, which 
 is sometimes sufficient to set the mass on 
 fire. By conducting this operation in an ac- 
 curate way, it is found that oxygen is absorb- 
 ed. The sulphate is obtained by solution in 
 water, and subsequent evaporation ; by which 
 the crystals of the salt are separated from the 
 earthy impurities, which were not suspended 
 in the water. 
 
 The sulphuric acid was formerly obtained 
 in this country by distillation from sulphate 
 of iron, as it still is in many parts abroad : the 
 common green vitriol is made use of for this 
 purpose, as it is to be met with at a low price, 
 and the acid is most easily to be extracted 
 from it. With respect to the operation itself, 
 the following particulars should be attended 
 to : First, the vitriol must be calcined in an 
 iron or earthen vessel, till it appears of a 
 yellowish red colour : by this operation it 
 will lose half its weight. This is done in 
 order to deprive it of the greater part of the 
 water which it has attracted into its crystals 
 during the crystallization, and which would 
 otherwise, in the ensuing distillation, greatly 
 weaken the acid. As soon as the calcina- 
 tion is finished, the vitriol is to be put im- 
 mediately, while it is warm, into a coated 
 earthen retort, which is to be filled two- 
 thirds with it, so that the ingredients may 
 have sufficient room upon being distended 
 by the heat, and thus the bursting of the 
 retort be prevented. It will be most advis- 
 able to have the retort immediately enclosed 
 in brick- work in a reverberatory furnace, and 
 to stop up the neck of it till the distillation 
 begins, in order to prevent the materials 
 from attracting fresh humidity from the air. 
 At the beginning of the distillation the re- 
 tort must be opened, and a moderate fire is 
 to be applied to it, in order to expel from 
 the vitriol all that part of the phlegm which 
 does not taste strongly of the acid, and which 
 may be received in an open vessel placed 
 under the retort. But as soon as there ap- 
 pear any acid drops, a receiver is to be add- 
 ed, into which has been previously poured a 
 quantity of the acidulous fluid which has 
 come over, in the proportion of half a pound 
 of it to twelve pounds of the calcined vitriol; 
 when the receiver is to be secured with a 
 proper luting. The fire is now to be raised 
 by little and little to the most intense degree 
 of heat, and the receiver carefully covered 
 with wet cloths, and, in winter time, with 
 snow r or ice, as the acid rises in the form of 
 a thick white vapour, which toward the end 
 of the operation becomes hot, and heats the 
 receiver to a great degree. The fire must 
 
 be continued at this high pitch for several 
 days, till no vapour issues from the retort, 
 nor any drops are seen trickling down its 
 sides. In the case of a great quantity of 
 vitriol being distilled, M. Bernhardt has ob- 
 served it to continue emitting vapours in this 
 manner for the space of ten days. When the 
 vessels are quite cold, the receiver must be 
 opened carefully, so that none of the luting may 
 fall into it ; after which the fluid contained in 
 it is to be poured into a bottle, and the air 
 carefully excluded. The fluid that is thus ob- 
 tained is the German sulphuric acid, of which 
 Bernhardt got sixty-four pounds from six 
 hundred weight of vitriol ; and on the other 
 hand, when no water had been previously 
 poured into the receiver, fifty-two pounds 
 only of a dry concrete acid. This acid w r as 
 formerly called glacial oil of vitriol, and its 
 consistence is owing to a mixture of sulphu- 
 rous acid, which occasions it to become solid 
 at a moderate temperature. 
 
 * It has been lately stated by Vogel, that 
 when this fuming acid is put into a glass re- 
 tort, and distilled by a moderate heat into a 
 receiver cooled wdth ice, the fuming portion 
 comes over first, and may be obtained in a 
 solid state by stopping the distillation in 
 time. This has been supposed to constitute 
 absolute sulphuric acid, or acid entirely void 
 of water. It is in silky filaments, tough, 
 difficult to cut, and somewhat like asbestos. 
 Exposed to the air, it fumes strongly, and 
 gradually evaporates. It does not act on the 
 skin so rapidly as concentrated oil of vitriol. 
 Up to 66° it continues solid, but at tem- 
 peratures above this it becomes a colourless 
 vapour, which whitens on contact with air. 
 Dropped into water in small quantities, it 
 excites a hissing noise, as if it were red hot 
 iron ; in larger quantities it produces a spe- 
 cies of explosion. It is said to be convert- 
 ible into ordinary sulphuric acid, by the 
 addition of a fifth of water. It dissolves sul- 
 phur, and assumes a blue, green, or brown 
 colour, according to the proportion of sul- 
 phur dissolved. The specific gravity of the 
 black fuming sulphuric acid, prepared in 
 large quantities from copperas, at Nord- 
 liausen, is 1.896. Its constitution is not 
 well ascertained.* 
 
 The sulphuric acid made in Great Bri- 
 tain is produced by the combustion of sul- 
 phur. There are three conditions requisite 
 in this operation. Oxygen must be present 
 to maintain the combustion ; the vessel must 
 be so close as to prevent the escape of the 
 volatile matter which rises, and w ater must be 
 present to imbibe it. For these purposes, a 
 mixture of eight parts of sulphur with one 
 of nitre is placed in a proper vessel, enclosed 
 within a chamber of considerable size, lined 
 on all sides with lead, and covered at bottom 
 with a shallow 7 stratum of water. The mix- 
 
ACI 
 
 ACI 
 
 ture being set on fire, will burn for a consi- 
 derable time by virtue of the supply of oxy- 
 gen which nitre gives out when heated, and 
 the water imbibing the sulphurous vapours, 
 becomes gradually more and more acid after 
 repeated combustions, and the acid is after- 
 ward concentrated by distillation. 
 
 * Such was the account usually given of 
 this operation, till MM. Clement and Des- 
 ormes shewed, in a very interesting me- 
 moir, its total inadequacy to account for the 
 result. 100 parts of nitre, judiciously man- 
 aged, will produce, with the requisite quan- 
 tity of sulphur, 2000 parts of concentrated 
 sulphuric acid. Now these contain 1200 
 parts of oxygen, while the hundred parts of 
 nitre contain only 39^ of oxygen ; being not 
 
 ^qyth part of what is afterwards found in the 
 resulting sulphuric acid. But after the 
 combustion of the sulphur, the nitre is con- 
 verted into sulphate and bisulphate of pot- 
 ash, which mingled residuary salts contain 
 nearly as much oxygen as the nitre originally 
 did. Hence, the origin of the 1200 parts of 
 the oxygen in the sulphuric acid is still to be 
 sought for. The following ingenious theory 
 was first given by MM. Clement and Des- 
 ormes. The burning sulphur, or sulphurous 
 acid, taking from the nitre a portion of its 
 oxygen, forms sulphuric acid, which unites 
 with the potash, and displaces a little nitrous 
 and nitric acids in vapour. These vapours 
 are decomposed, by the sulphurous acid, into 
 nitrous gas, or deutoxide of azote. This gas, 
 naturally little denser than air, and now 
 expanded by the heat, suddenly rises to the 
 roof ot the chamber ; and might be expected 
 to escape at the aperture there, which manu- 
 facturers were always obliged to leave open, 
 otherwise they found the acidification would 
 not proceed. But the instant that nitrous 
 gas comes in contact with atmospherical oxy- 
 gen, nitrous acid vapour is formed, which be- 
 ing a very heavy aeriform body, immediately 
 precipitates on the sulphurous flame, and 
 converts it into sulphuric acid ; while itself 
 resuming the state of nitrous gas, reascends 
 for a new charge of oxygen, again to rede- 
 scend, and transfer it, to the flaming sulphur. 
 Thus we see, that a small volume of nitrous 
 vapour, by its alternate metamorphoses into 
 the states of oxide and acid, and its conse- 
 quent interchanges, may be capable of acidi- 
 fying a great quantity of sulphur. 
 
 This beautiful theory received a modifica- 
 tion from Sir H. Davy. He found that nitrous 
 gas had no action on sulphurous gas, to convert 
 it into sulphuric acid, unless water be pre- 
 sent. With a small proportion of water, 4 
 volumes of sulphurous acid gas, and 3 of 
 nitrous gas, are condensed into a crystalline 
 solid, which is instantly decomposed by 
 abundance of water ; oil of vitriol is formed, 
 and nitrous acid given off, which with con- 
 tact of air becomes nitrous acid gas, as above 
 
 described. The process continues, according 
 to the same principle of combination and 
 decomposition, till the water at the bottom 
 of the chamber is become strongly acid. It 
 is first concentrated in large leaden pans, and 
 afterwards in glass retorts heated in a sand- 
 bath. Platinum alembics, placed within pots 
 of cast-iron of a corresponding shape and 
 capacity, have been lately substituted in 
 many manufactories for glass, and have been 
 found to save fuel, and quicken the process 
 of concentration. 
 
 The proper mode of burning the sulphur 
 with the nitre, so as to produce the greatest 
 quantity of oil of vitriol, is a problem, con- 
 cerning which chemists hold a variety of opi- 
 nions. M. Thenard describes the following 
 as the best. Near one of the sides of the 
 leaden chamber, and about a foot above its 
 bottom, an iron plate, furnished with an up- 
 right border, is placed horizontally over a 
 furnace, whose chimney passes across, under 
 the bottom of the chamber, without having 
 any connexion with it. On this plate, which 
 is enclosed in a little chamber, the mixture 
 of sulphur and nitre is laid. The whole 
 being shut up, and the bottom of the large 
 chamber covered wdth water, a gentle fire is 
 kindled in the furnace. The sulphur soon 
 takes fire, and gives birth to the products de- 
 scribed. When the combustion is finished, 
 which is seen through a little pane adapted 
 to the trap-door of the chamber, this is open- 
 ed, the sulphate of potash is withdrawn, and 
 is replaced by a mixture of sulphur and 
 nitre. The air in the great chamber is mean- 
 while renewed, by opening its lateral door, 
 and a valve in its opposite side. Then, after 
 closing these openings, the furnace is lighted 
 anew. Successive mixtures are thus burned 
 till the acid acquires a specific gravity of 
 about 1 .390, taking care never to put at once 
 on the plate more sulphur than the air of 
 the chamber can acidify. The acid is then 
 withdrawn by stopcocks, and concentrated. 
 
 The following details are extracted from 
 a paper on sulphuric acid by Dr Ure, which 
 was published in the 4th volume of the Jour- 
 nal of Science and the Arts. 
 
 The best commercial sulphuric acid that I 
 have been able to meet with, contains from 
 one- half to three quarters of a part in the 
 hundred, of solid saline matter, foreign to 
 its nature. These fractional parts consist of 
 sulphate of potash and lead, in the pro- 
 portion of four of the former to one of 
 the latter. It is, I believe, difficult to 
 manufacture it directly, by the usual me- 
 thods, of a purer quality. The ordinary acid 
 sold in the shops contains often 3 or 4 per 
 cent of saline matter. Even more is occa- 
 sionally introduced, by the employment of 
 nitre, to remove the brown colour given 
 to the acid by carbonaceous matter. 1 he 
 amount of these adulterations, whether acci- 
 
ACI 
 
 ACI 
 
 dental or fraudulent, may be readily deter- 
 mined by evaporating, in a small capsule of 
 poi celain, or 1 ather platinum, a definite weight 
 of the acid. 1 he platinum cup, placed on the 
 red cinders of a common fire, will give an 
 exact result in five minutes. If more than 
 five grains of matter remain from five hundred 
 of acid, we may pronounce it sophisticated. 
 
 Distillation is the mode by which pure 
 oil of vitriol is obtained. This process is 
 described in chemical treatises as both diffi- 
 cult and hazardous ; but since adopting the 
 following plan, I have found it perfectly 
 safe and convenient. I take a plain glass 
 retort, capable of holding from two to four 
 quarts of water, and put into it about a pint 
 measure of the sulphuric acid, (and a few 
 fragments of glass,) connecting the retort 
 with a large globular receiver, by means of a 
 glass tube four feet long, and from one to 
 two inches in diameter. The tube fits very 
 loosely at both ends. The retort is placed 
 over a charcoal fire, and the flame is made 
 to play gently on its bottom. When the 
 acid begins to boil smartly, sudden explo- 
 sions of dense vapour, rush forth from time 
 to time, which would infallibly break small 
 vessels. Here, however, these expansions 
 are safely permitted, by the large capacity of 
 the retort and receiver, as well as by the 
 easy communication with the air at both ends 
 of the adopter tube. Should the retort, in- 
 deed, be exposed to a great intensity of 
 flame, the vapour will no doubt be generated 
 with incoercible rapidity, and break the ap- 
 paratus. But this accident can proceed only 
 from gross imprudence. It resembles, in 
 suddenness, the explosion of gunpowder, 
 and illustrates admirably Dr Black’s obser- 
 vation, that, but for the great latent heat of 
 steam, a mass of water, powerfully heated, 
 would explode on reaching the boiling tem- 
 perature. I have ascertained, that the speci- 
 fic caloric of the vapour of sulphuric acid is 
 very small, and hence the danger to which 
 rash operators may be exposed during its 
 distillation. Hence, also, it is unnecessary 
 to surround the receiver with cold water, as 
 when alcohol and most other liquids are dis- 
 tilled. Indeed the application of cold to the 
 bottom of the receiver generally causes it, in 
 the present operation, to crack. By the 
 above method, I have made the concentrated 
 oil of vitriol flow over in a continuous slen- 
 der stream, without the globe becoming sen- 
 sibly hot. 
 
 I have frequently boiled the distilled acid 
 till only one-half remained in the retort ; 
 yet at the temperature of 60° Fahrenheit, I 
 have never found the specific gravity of acid 
 so concentrated, to exceed 1.8455. It is, I 
 believe, more exactly 1.8452. The number 
 1.850, which it has been the fashion to 
 assign for the density of pure oil of vitriol, 
 is undoubtedly very erroneous, and ought to 
 
 be corrected. Genuine commercial acid 
 should never surpass 1.8485; when it is 
 denser, we may infer sophistication, or negli- 
 gence, in the manufacture. 
 
 The progressive increase of its density, 
 with saline contamination, will be shewn by 
 the following experiments. To 4100 grains 
 of genuine commercial acid (but concen- 
 trated to only 1.8350) 40 grains of dry sul- 
 phate of potash were added. When the so- 
 lution was completed, the specific gravity at 
 60° had become 1.8417. We see that at 
 these densities the addition of 0.01 of salt 
 increases the specific gravity by about 0.0067. 
 To the above 4140 grains other 80 grains of 
 sulphate were added, and the specific gravity, 
 after solution, was found to be 1.8526. We 
 perceive that somewhat more salt is now' re- 
 quired to produce a proportional increase of 
 density; 0.01 of the former changing the 
 latter by only 0.0055. Five hundred grains 
 of this acid being evaporated in a platinum 
 capsule left 16^ grains, whence the composi- 
 tion was 
 
 Sulphate of potash, with a little sulphate 
 of lead, - 3. 30 
 
 Water of dilution, - 5.5 
 
 Oil of vitriol of 1.8485, - 91.4 
 
 100.0 
 
 Thus, acid of 1.8526, which in commerce 
 would have been accounted very strong, con- 
 tained little more than 91 per cent of ge- 
 nuine acid. 
 
 Into the last acid more sulphate of potash 
 w r as introduced, and solution being favoured 
 by digestion in a moderate heat, the specific 
 gravity became, at 60°, 1.9120. Of this 
 compound, 300 grains, evaporated in the 
 platinum capsule, left 41 grains of gently 
 ignited saline matter. We have, therefore, 
 nearly 14 per cent. On the specific gravity 
 in this interval, an increase of 0.0054 w r as 
 effected by 0.01 of sulphate. This liquid 
 was composed of saline matter, 14. 
 
 Water of dilution, - - 4.7 
 
 Oil of vitriol of 1.8485, - 81.3 
 
 100.0 
 
 The general proportion between the density 
 and impurity may be stated at 0.0055 of the 
 former, to 0.01 of the latter. 
 
 If from genuine oil of vitriol, containing 
 ^ of a per cent of saline matter, a consider- 
 able quantity of acid be distilled off’, what re- 
 mains in the retort will be found very dense. 
 At the specific gravity 1.865, such acid con- 
 tains 3i§ of solid salt in the 100 parts. The 
 rest is pure concentrated acid. From such 
 heavy acid, at the end of a few days, some 
 minute crystals wiil be deposited, after which 
 its specific gravity becomes 1.860, and its 
 transparency is perfect. It contains about 
 per cent of saline matter. Hence if the 
 chemist employ for his researches an acid. 
 
A Cl 
 
 ACI 
 
 which, though originally pretty genuine, has 
 been exposed to long ebullition, he will fall 
 into great errors. From the last experiments 
 it appears, that concentrated oil of vitriol can 
 take up only a little saline matter in compa- 
 rison with that which is somewhat dilute. 
 It is also evident, that those who trust to 
 specific gravity alone, for ascertaining the 
 value of oil of vitriol, are liable to great im- 
 positions. 
 
 The saline impregnation exercises an im- 
 portant influence, on all the densities at sub- 
 sequent degrees of dilution. Thus, the 
 heavy impure concentrated acid, specific 
 gravity 1.8650, being added to water in the 
 proportion of one part to ten, by weight, 
 gave, after twenty -four hours, a compound 
 whose specific gravity was 1.064. But the 
 most concentrated genuine acid, as well as 
 distilled acid, by the same degree of dilution, 
 namely 1 — j— 1 0, acquires the specific gravity 
 of only 1.0602, while that of 1.852, con- 
 taining, as stated above, o\ per cent of sul- 
 phate of potash combined with acid of 1.835, 
 gives, on a similar dilution, 1.058. This 
 difference, though very obvious to good in- 
 struments, is inappreciable by ordinary com- 
 mercial apparatus. Hence this mode of 
 ascertaining the value of an acid, recom- 
 mended by Mr Dalton, is inadequate to de- 
 tect a deterioration of even 8 or 9 per cent. 
 Had a little more salt been present in the 
 acid, the specific gravity of the dilute, in this 
 case, would have equalled that of the genuine. 
 On my acidimeter one per cent of deteriora- 
 tion could not fail to be detected, even by 
 those ignorant of science. 
 
 The quantity of oxide, or rather sulphate 
 of lead, which sulphuric acid can take up, is 
 much more limited than is commonly ima- 
 gined. To the concentrated oil of vitriol I 
 added much carbonate of lead, and after 
 digestion by a gentle heat, in a close vessel, 
 for twenty- four hours, with occasional agita- 
 tion, its specific gravity, when taken at 60°, 
 was scarcely greater than before the experi- 
 ment. It contained about 0.005 of sulphate 
 of lead. 
 
 'I he quantity of water present in 100 parts 
 of concentrated and pure oil of vitriol, seems 
 to be pretty exactly 1 8.46. 
 
 In the experiments executed, to determine 
 the relation between the density of diluted 
 oil of vitriol, and its acid strength,. I em- 
 ployed a series of phials, numbered with a 
 diamond. Into each phial, recently boiled 
 acid, and pure water, were mixed in the suc- 
 cessive proportions of 99 + 1 ; 98 + 2; 97 
 4- d ; Sec. through the whole range of digits 
 down to 1 acid -f- 99 water. The phials 
 svere occasionally agitated during 24 hours, 
 after which the specific gravity was taken. 
 
 The acid was genuine and well concentrated. 
 Its specific gravity was 1.8485. Some of 
 the phials were kept with their acid contents 
 for a week or two, but no further change in 
 the density took place. The strongest possi- 
 ble distilled acid was employed for a few 
 points, and gave the same results as the 
 other. 
 
 Of the three well known modes of ascer- 
 taining the specific gravity of a liquid, name- 
 ly, that, by Fahrenheit’s hydrometer ; by 
 weighing a vessel of known capacity filled 
 with it; and by poising a glass ball, sus- 
 pended by a fine platina wire from the arm 
 of a delicate balance; I decidedly prefer the 
 last. The corrosiveness, viscidity, and weight 
 of oil of vitriol, render the first two methods 
 ineligible ; whereas, by a ball floating in a 
 liquid, of which the specific gravity does not 
 ditfer much from its own, the balance, little 
 loaded, retains its whole sensibility, and will 
 give the most accurate consistency of re- 
 sults. 
 
 In taking the specific gravity of concen- 
 trated or slightly diluted acid, the tempera- 
 ture must be minutely regulated, because, 
 from the small specific heat of the acid, it is 
 easily affected, and because it greatly influ- 
 ences the density. On removing the ther- 
 mometer, it will speedily rise in the air to 
 75° or 80°, though the temperature of the 
 apartment be only 60°. Afterwards it will 
 slowly fall to perhaps 60° or 62°. If this 
 thermometer, having its bulb covered with a 
 film of dilute acid (from absorption of at- 
 mospheric moisture), be plunged into a strong 
 acid, it will instantly rise 10°, or more, above 
 the real temperature of the liquid. This 
 source of embarrassment and occasional error 
 is obviated by wiping the bulb after every 
 immersion. An elevation of temperature, 
 equal to 10° Fahr. diminishes the density of 
 oil of vitriol by 0.005 ; 1000 parts being heat- 
 ed from 60° to 212°, become 1.043 in vo- 
 lume, as I ascertained by very careful ex- 
 periments. The specific gravity, which was 
 1.848, becomes only 1.772, being the num- 
 ber corresponding to a dilution of 14 per 
 cent of water. The viscidity of oil of vitriol, 
 which below 50° is such as to render it diffi- 
 cult to determine the specific gravity by a 
 floating ball, diminishes very rapidly as the 
 temperature rises, evincing that it is a modi- 
 fication of cohesive attraction. 
 
 The following table of densities, corres- 
 ponding to degrees of dilution, was the re- 
 sult, in each point, of a particular experi- 
 ment, and was, moreover, verified in a num- 
 ber of its terms, by the further dilution of an 
 acid, having previously combined with it a 
 known proportion of water. The balance 
 was accurate and sensible. 
 
ACI 
 
 ACI 
 
 1 ABLE of the quantity of Oil of Vitriol and dry Sulphuric Acid in 100 
 parts of dilute, at different densities, by Dr Urk. 
 
 Liquid. 
 
 Sp. Gr. 
 
 Dry. 
 
 Liquid. 
 
 Sp. Gr. 
 
 Dry. 
 
 Liquid 
 
 Sp. Gr. 
 
 Dry. 
 
 100 
 
 1.8485 
 
 81.54 
 
 66 
 
 1.5503 
 
 53.82 
 
 32 
 
 1.2334 
 
 26.09 
 
 99 
 
 1.8475 
 
 80.72 
 
 65 
 
 1.5390 
 
 53.00 
 
 31 
 
 1.2260 
 
 25.28 
 
 98 
 
 1.8460 
 
 79.90 
 
 64 
 
 1.5280 
 
 52.18 
 
 30 
 
 1.2184 
 
 24.46 
 
 97 
 
 1.8439 
 
 79.09 
 
 63 
 
 1.5170 
 
 51.37 
 
 29 
 
 1.2108 
 
 25.65 
 
 96 
 
 1.8410 
 
 78.28 
 
 62 
 
 1.5066 
 
 50.55 
 
 28 
 
 1 .2052 
 
 22.85 
 
 95 
 
 1.8376 
 
 77.46 
 
 61 
 
 1.4960 
 
 49.74 
 
 27 
 
 1.1956 
 
 22.01 
 
 94 
 
 1.8336 
 
 76.65 
 
 60 
 
 1.4860 
 
 48.92 
 
 26 
 
 1.1876 
 
 21.20 
 
 93 
 
 1.8290 
 
 75.83 
 
 59 
 
 1.4760 
 
 48.11 
 
 25 
 
 1.1792 
 
 20.38 
 
 92 
 
 1.8233 
 
 75.02 
 
 58 
 
 1.4660 
 
 47.29 
 
 24 
 
 1.1706 
 
 19.57 
 
 91 
 
 1.8179 
 
 74.20 
 
 57 
 
 1.4560 
 
 46.48 
 
 23 
 
 1.1626 
 
 18.75 
 
 90 
 
 1.81 15 
 
 73.39 
 
 56 
 
 1.4460 
 
 45.66 
 
 22 
 
 1.1549 
 
 17.94 
 
 89 
 
 1.8045 
 
 72.57 
 
 55 
 
 1.4360 
 
 44.85 
 
 21 
 
 1.1480 
 
 17.12 
 
 88 
 
 1.7962 
 
 71.75 
 
 54 
 
 1.4265 
 
 44.03 
 
 20 
 
 1.1410 
 
 16.31 
 
 87 
 
 1.7870 
 
 70.94 
 
 53 
 
 1.4170 
 
 45.22 
 
 19 
 
 1.1330 
 
 15.49 
 
 86 
 
 1.7774 
 
 70.12 
 
 52 
 
 1.4073 
 
 4 2.40 
 
 18 
 
 1.1246 
 
 14.68 
 
 85 
 
 1.7673 
 
 69.31 
 
 51 
 
 1.3977 
 
 41.58 
 
 17 
 
 1.1 165 
 
 13.86 
 
 84 
 
 1.7570 
 
 68.49 
 
 50 
 
 1.3884 
 
 40.77 
 
 16 
 
 1.1090 
 
 13.05 
 
 83 
 
 1.7465 
 
 67.68 
 
 49 
 
 1.3788 
 
 39.95 
 
 15 
 
 1.1019 
 
 12.23 
 
 82 
 
 1.7360 
 
 66.86 
 
 48 
 
 1.3697 
 
 39.14 
 
 14 
 
 1.0953 
 
 11.41 
 
 81 
 
 1.7245 
 
 66.05 
 
 47 
 
 1 .56 1 2 
 
 38.52 
 
 13 
 
 1.0887 
 
 10.60 
 
 80 
 
 1.7120 
 
 65.23 
 
 46 
 
 1.3530 
 
 57.51 
 
 12 
 
 1.0809 
 
 9.78 
 
 79 
 
 1.6993 
 
 64.42 
 
 45 
 
 1.3440 
 
 36.69 
 
 1 1 
 
 1.0743 
 
 8.97 
 
 78 
 
 1.6870 
 
 63.60 
 
 44 
 
 1.3345 
 
 35.88 
 
 10 
 
 1.0682 
 
 8.15 
 
 77 
 
 1.6750 
 
 62.78 
 
 45 
 
 1.3255 
 
 35.06 
 
 9 
 
 1.0614 
 
 7.34 
 
 76 
 
 1.6630 
 
 61.97 
 
 42 
 
 1.3165 
 
 34.25 
 
 8 
 
 1.0544 
 
 6.52 
 
 75’ 
 
 1.6520 
 
 61.15 
 
 41 
 
 1.3080 
 
 33.43 
 
 7 
 
 1.0477 
 
 5.71 
 
 74 
 
 1.6415 
 
 60.54 
 
 40 
 
 1.2999 
 
 32.61 
 
 6 
 
 1.0405 
 
 4.89 
 
 73 
 
 1.6321 
 
 59.52 
 
 39 
 
 1.2913 
 
 31.80 
 
 5 
 
 .0336 
 
 4.08 
 
 72 
 
 1.6204 
 
 58.71 
 
 38 
 
 1.2826 
 
 30.98 
 
 4 
 
 1.0268 
 
 3.26 
 
 71 
 
 1.6090 
 
 57.89 
 
 37 
 
 1.2740 
 
 30.17 
 
 5 
 
 1.0206 
 
 2.446 
 
 70 
 
 1.5975 
 
 57.08 
 
 36 
 
 1.2654 
 
 29.35 
 
 2 
 
 1.0140 
 
 1.63 
 
 69 
 
 1.5868 
 
 56.26 
 
 35 
 
 1.2572 
 
 28.54 
 
 1 
 
 1.0074 
 
 0.8154 
 
 68 
 
 1.5760 
 
 55.45 
 
 34 
 
 1.2490 
 
 27.72 
 
 
 
 
 67 
 
 1.5648 
 
 54.63 
 
 33 
 
 1.2409 
 
 26.91 
 
 
 
 
 In order to compare the densities of the 
 preceding dilute acid, with those of distilled 
 and again concentrated acid, I mixed one 
 part of the latter with nine of pure water, 
 and after agitation, and a proper interval, to 
 ensure thorough combination, I found its 
 specific gravity as above, 1.0682 : greater 
 density indicates saline contamination. 
 
 Dilute acid having a specific gravity = 
 1.6521, has suffered the greatest condensa- 
 tion ; 100 parts in bulk have become 92.14. 
 If either more or less acid exist in the com- 
 pound, the volume will be increased. What 
 reason can be assigned for the maximum 
 condensation occurring at this particular 
 term of dilution ? The above dilute acid con- 
 sists of 73 per cent of oil of vitriol, and 27 
 of water, liut 7S of the former contains, by 
 this Table, 59.52 of dry acid, and 13.48 of 
 water. Hence 100 of the dilute acid con- 
 sist of 59.52 of dry acid, -j- 13.48 X 3 = 
 40.44 of water = 99.96; or it is a com- 
 pound of one atom of dry acid, with three 
 
 atoms of water. Dry sulphuric acid con- 
 sists of three atoms of oxygen, united to one 
 of sulphur. Here each atom of oxygen is 
 associated with one of water, forming a 
 symmetrical arrangement. We may there- 
 fore infer, that the least deviation from the 
 above definite proportions, must impair the 
 balance of the attractive forces, whence 
 they will act less efficaciously, and therefore 
 produce less condensation. 
 
 The very minute and patient examination 
 which I was induced to bestow on the table 
 of specific gravities, disclosed to me the ge- 
 neral law pervading the whole, and conse- 
 quently the means of inferring at once the 
 density from the degree of dilution, as also of 
 solving the inverse proposition. 
 
 If we take the specific gravity, correspond- 
 ing to ten per cent of oil of vitriol, or 1.0682 
 as the root; then the specific gravities at the 
 successive terms of 20, 30, 40, &c. will be 
 the successive powers of that root. The 
 terms of dilution are like logarithms, a series 
 
ACI 
 
 ACI 
 
 of numbers in arithmetical progression, cor- 
 responding to another series, namely, the 
 specific gravities in geometrical progression. 
 
 The simplest logarithmic formula which 
 I have been able to contrive is the follow- 
 ing. 
 
 Log. S = — , where S is the specific 
 ° 700 
 
 gravity, and a the per centage of acid. 
 
 And a = Log. S X 550. 
 
 In common language the tw r o rules may 
 be stated thus. 
 
 Problem 1st, To find the proportion of 
 oil of vitriol in dilute acid of a given specific 
 gravity. Multiply the logarithm of the spe- 
 cific gravity by 350, the product is directly 
 the per centage of acid. 
 
 If the dry acid be sought, we must multi- 
 ply the logarithm of the specific gravity by 
 285, and the product will be the answer. 
 
 Problem 2d, To find the specific gravity 
 corresponding to a given proportion of acid. 
 Multiply the quantity of acid by 2, and di- 
 vide by 700 ; the quotient is the logarithm 
 of the specific gravity. 
 
 Table of distilled sulphuric acid, for the 
 higher points, below which it agrees with the 
 former table. 
 
 Liquid Acid in 100. 
 
 Sp. Gr. 
 
 Dry Acid. 
 
 100 
 
 1.84 6 
 
 81.63 
 
 95 
 
 1.834 
 
 77.55 
 
 90 
 
 1.807 
 
 73.47 
 
 85 
 
 1.764 
 
 69.39 
 
 80 
 
 1.708 
 
 65.30 
 
 75 
 
 1.650 
 
 61.22* 
 
 The sulphuric acid strongly attracts water, 
 which it takes from the atmosphere very ra- 
 pidly, and in larger quantities, if suffered to 
 remain in an open vessel, imbibing one-third 
 of its weight in twenty-four hours, and more 
 than six times its weight in a twelvemonth. 
 If four parts by weight be mixed with one 
 of water at 50°, they produce an instanta- 
 neous heat of 500° F. ; and four parts raise 
 one of ice to 212°: on the contrary, four 
 parts of ice, mixed with one of acid, sink the 
 thermometer to 4° below 0. When pure it 
 is colourless, and emits no fumes. It re- 
 quires a great degree of cold to freeze it ; 
 and if diluted with half a part or more of 
 water, unless the dilution be carried very far, 
 it becomes more and more difficult to con- 
 geal ; yet at the specific gravity of 1.78, or 
 a few hundredths above or below this, it may 
 be frozen by surrounding it with melting 
 snow. Its congelation forms regular pris- 
 matic crystals with six sides. Its boiling 
 point, according to Bergman, is 540° ; ac- 
 cording to Dalton, 590°. 
 
 * Sulphuric acid consists of three prime 
 equivalents of oxygen, one of sulphur, and 
 one of water ; and by weight, therefore, of 
 3.0 oxygen + 2.0 sulphur + 1.125 water = 
 6.125, which represents the prime equivalent 
 
 of the concentrated liquid acid ; while 3 -{- 2 
 — 5, will be that of the dry acid. 
 
 Pure sulphuric acid is without smell and 
 colour, and of an oily consistence. Its ac- 
 tion on litmus is so strong, that a single 
 drop of acid will redden an immense quan- 
 tity. It is a most violent caustic ; and has 
 sometimes been administered with the most 
 criminal purposes. The person who unfor- 
 tunately swallows it, speedily dies in dread- 
 ful agonies and convulsions. Chalk, or com- 
 mon carbonate of magnesia, is the best anti- 
 dote for this, as well as for the strong nitric 
 and muriatic acids. 
 
 When transmitted through an ignited por- 
 celain tube of one-fifth of an inch diameter, 
 it is resolved into two parts of sulphurous 
 acid gas, and one of oxygen gas, with water. 
 Voltaic electricity causes an evolution of sul- 
 phur at the negative pole ; whilst a sulphate 
 of the metallic wire is formed at the positive. 
 Sulphuric acid has no action on oxygen gas 
 or air. It merely abstracts their aqueous 
 vapour. 
 
 If the oxygenized muriatic acid of M. 
 Thenard be put in contact with the sul- 
 phate of silver, there is immediately formed 
 insoluble chloride of silver, and oxygenized 
 sulphuric acid. To obtain sulphuric acid in 
 the highest degree of oxygenation, it is 
 merely necessary to pour barytes water into 
 the above oxygenized acid, so as to precipi- 
 tate only a part of it, leaving the rest in 
 union with the whole of the oxygen. Oxy- 
 genized sulphuric acid partially reduces the 
 oxide of silver, occasioning a strong effer- 
 vescence. 
 
 All the simple combustibles decompose sul- 
 phuric acid, with the assistance of heat. About 
 400° Fahr. sulphur, converts sulphuric into 
 sulphurous acid. Several metals at an elevat- 
 ed temperature decompose this acid, with evo- 
 lution of sulphurous acid gas, oxidizement of 
 the metal, and combination of the oxide, with 
 the undecomposed portion of the acid.* 
 
 The sulphuric acid is of very extensive 
 use in the art of chemistry, as well as in me- 
 tallurgy, bleaching, and some of the processes 
 for dyeing ; in medicine it is given as a tonic, 
 stimulant, and lithontriptic, and sometimes 
 used externally as a caustic. 
 
 The combinations of this acid with the 
 various bases are called sulphates, and most 
 of them have long been known by various 
 names. With barytes it is found native and 
 nearly pure in various forms, in coarse pow- 
 der, rounded masses, stalactites, and regular 
 crystallizations, which are in some lamellar, 
 in others needly, in others prismatic or pyra- 
 midal. The cawks of our country and 
 the Bolognian stone are merely native sul- 
 phates of barytes. Their colour varies con- 
 siderably as well as their figure, but their 
 specific gravity is great, that of a very im- 
 pure kind being 3.89, and the pure sorts 
 
ACI 
 
 ACI 
 
 varying from 4 to 4.8 G5 ; hence it has been 
 distinguished by the names of marmor metal- 
 licum and ponderous spar. 
 
 It consists, according to Dr Wollaston, of 
 5 parts of dry acid, and 9.7 5 of barytes; and 
 by Professor Berzelius’s last estimate, of 5 of 
 acid and 9. 573 barytes.* 
 
 I his salt, though deleterious, is less so 
 than the carbonate of barytes, and is more 
 economical for preparing the muriate for 
 medicinal purposes. It requires 43,000 
 parts of water to dissolve it at 60°. 
 
 Sulphate of strontian has a considerable 
 resemblance to that of barytes in its pro- 
 perties. It is found native in considerable 
 quantities at A ust Passage and other places 
 in the neighbourhood of Bristol. It re- 
 quires 3840 parts of boiling water to dis- 
 solve it. 
 
 * Its composition is 5 acid 4- 6.5 base.* 
 
 The sulphate of potash, vitriolated kali of 
 
 the London college, formerly vitriolated tar- 
 tar, sal de duobus , and arcanum duplicatum , 
 crystallizes in hexaedral prisms, terminated 
 by hexagonal pyramids, but susceptible of 
 variations. Its crystallization by quick 
 cooling is confused. Its taste is bitter, 
 acrid, and a little saline. It is soluble in 
 5 parts of boiling water, and 1 6 parts at 60°. 
 In the fire it decrepitates, and is fusible by a 
 strong heat. It is decomposable by char- 
 coal at a high temperature. It may be pre- 
 pared by direct mixture of its component 
 parts ; but the usual and cheapest mode is 
 to neutralize the acidulous sulphate left after 
 distilling nitric acid, the sal enixen of the 
 old chemists, by the addition of carbonate 
 of potash. The sal polychresl of old dis- 
 pensatories, made by deflagrating sulphur 
 and nitre in a crucible, was a compound of 
 the sulphate and sulphite of potash. The 
 acidulous sulphate is sometimes employed as 
 a flux, and likewise in the manufacture of 
 alum. In medicine the neutral salt is some- 
 times used as a deobstruent, and in large 
 doses as a mild cathartic ; dissolved in a 
 considerable portion of water, and taken 
 daily in such quantity as to be gently ape- 
 rient, it has been found serviceable in cuta- 
 neous affections, and is sold in London for 
 this purpose as a nostrum ; and certainly it 
 deserves to be distinguished from the gene- 
 rality of quack medicines, very few indeed 
 of which can be taken without imminent 
 hazard. 
 
 * It consists of 5 acid -f 5-95 base ; but 
 there is a compound of .e same constitu- 
 ents, in the proportion of 10 acid -f- 5.95 
 potash, called the bisulphate.* 
 
 The sulphate of soda is the vitriolated na- 
 tron of the college, the well known Glauber's 
 salt, or sal mirabile . It is commonly prepar- 
 ed from the residuum left after distilling 
 muriatic acid, the superfluous acid of which 
 may be saturated by the addition of soda, or 
 
 precipitated by lime ; and is likewise obtain- 
 ed in the manufacture of the muriate of am- 
 monia. (See Ammonia). Scherer mentions 
 another mode by Mr Funcke, which is, 
 making 8 parts of calcined sulphate of lime, 
 
 5 of clay, and 5 of common salt, into a paste 
 with water; burning this in a kiln; and 
 then powdering, lixiviating, and crystallizing. 
 It exists in large quantities under the surface 
 of the earth in some countries, as Persia, 
 Bohemia, and Switzerland ; is found mixed 
 with other substances in mineral springs and 
 sea water ; and sometimes effloresces on walls. 
 Sulphate of soda is bitter and saline to the 
 taste. It is soluble in 2.85 parts of cold water, 
 and 0.8 at a boiling heat; it crystallizes in 
 hexagonal prisms bevelled at the extremities, 
 sometimes grooved longitudinally, and of 
 very 1 rge size, when the quantity is great : 
 these effloresce completely into a white pow- 
 der if exposed to a dry air, or even if kept 
 wrapped up in paper in a dry place; yet 
 they retain sufficient water of crystallization 
 to undergo the aqueous fusion on exposure 
 to heat, but by urging the lire, melt. Bary- 
 tes and strontian take its acid from it entire- 
 ly, and potash partially : the nitric and mu- 
 riatic acids, though they have a weaker affi- 
 nity for its base, combine with a part of it 
 when digested on it. Heated with charcoal 
 its acid is decomposed. Asa purgative its 
 use is very general ; and it has been employ- 
 ed to furnish soda. Pajot des Charmes has 
 made some experiments on it in fabricating 
 glass : with sand alone it would not succeed, 
 but equal parts of carbonate of lime, sand, 
 and dried sulphate of soda, produced a clear, 
 solid, pale, yellow glass. 
 
 * It is composed of 5 acid -|-5. 95 base + 
 11.25 water in crystals; when dry, the for- 
 mer two primes are its constituents.* 
 
 Sulphate of soda and sulphate of ammonia 
 form together a triple salt. 
 
 Sulphate of lime, selenite, gypsum, plaster 
 of Paris, or sometimes alabaster, forms ex- 
 tensive strata in various mountains. The 
 specular gypsum, or glacies Maria?, is a spe- 
 cies of this salt, and affirmed by some 
 French travellers to be employed in Russia, 
 where it abounds, as a substitute for glass in 
 windows. Its specific gravity is from 1.872 
 to 2.31 1. It requires 500 parts of cold wa- 
 ter, and 450 of hot, to dissolve it. When 
 calcined it decrepitates, becomes very triable 
 and white, and heats a little with water, with 
 which it forms a solid mass. In this process 
 it loses its water of crystallization. In this 
 state it is found native in Tyrol, crystallized 
 in rectangular parallel opipeds, or octa'edral 
 or hexaedral prisms, and is called anhydrous 
 sulphate of lime. Both the natural and ar- 
 tificial anhydrous sulphate consists of 56.3 
 lime and 43.6 acid, according to Mr Chene- 
 vix. The calcined sulphate is much em- 
 ployed for making casts of anatomical and 
 
ACI 
 
 ACI 
 
 ornamental figures ; as one of the bases of 
 stucco ; as a fine cement for making close 
 and strong joints between stone, and joining 
 rims or tops of metal to glass ; for making 
 moulds for the Staffordshire potteries ; for 
 cornices, mouldings, and other ornaments in 
 building. For these purposes, and for being 
 wrought into columns, chimney-pieces, and 
 various ornaments, about eight hundred tons 
 are raised annually in Derbyshire, where it 
 is called alabaster. In America it is laid on 
 grass land as a manure. 
 
 * Ordinary crystallized gypsum consists 
 of 5 sulphuric acid -J- 3.6 lime + 2.25 wa- 
 ter ; the anhydrous variety wants of course 
 the last ingredient.* 
 
 Sulphate of magnesia, the vitriolated mag- 
 nesia of the late, and sal catharticus aina- 
 rus of former London Pharmacopoeias, is 
 commonly known by the name of Epsom salt f 
 as it was furnished in considerable quantity 
 by the mineral water at that place, mixed 
 however with a considerable portion of sul- 
 phate cf soda. It is afforded, however, in 
 greater abundance and more pure from the 
 bittern left after the extraction of salt from 
 sea w'ater. Jt has likewise been found efflo- 
 rescing on brick walls, both old and recently 
 erected, and in small quantity in the ashes 
 of coals. The capillary salt of Idria, found 
 in silvery crystals mixed with the aluminous 
 schist in the mines of that place, and hither- 
 to considered as a feathery alum, has been 
 ascertained by Klaproth to consist of sulphate 
 of magnesia, mixed with a small portion of 
 sulphate of iron. When pure it crystallizes 
 in small quadrangular prisms, terminated by 
 quadrangular pyramids or diedral summits. 
 Its taste is cool and bitter. It is very soluble, 
 requiring only an equal weight of cold w ater, 
 and three- fourths its weight of hot. It efflo- 
 resces in the air, though but slowly. If it 
 attract moisture, it contains muriate of ma<r- 
 nesia or of lime. Exposed to heat, it dis- 
 solves in its ow n w^ater of crystallization, and 
 dries, but is not decomposed, nor fused, but 
 with extreme difficulty. It consists, ac- 
 cording to Bergman, of 33 acid, 1 9 mag- 
 nesia, 48 water. A very pure sulphate 
 is said to be prepared in the neighbour- 
 hood of Genoa by roasting a pyrites found 
 there; exposing it to the air in a covered 
 place for six months, watering it occasional- 
 ly, and then lixiviating. 
 
 Sulphate of magnesia is one of our most 
 valuable purgatives; for which purpose only 
 it is used, and for furnishing the carbonate 
 of magnesia. 
 
 * It is composed of 5 acid -f- 2.5 magnesia 
 + 7.875 water, in the state of crystals.* 
 
 Sulphate of ammonia crystallizes in slen- 
 der, flattened, hexaedral prisms, terminated 
 by hexagonal pyramids ; it attracts a little 
 moisture from very damp air, particularly if 
 the acid be in excess; it dissolves in two 
 
 parts of cold and one of boiling water. It 
 is not used, though Glauber, who called it 
 his secret ammoniacal salt , vaunted its excel- 
 lence in assaying. 
 
 * It consists of 5 acid -j- 2.1 7 ammonia 
 -j- 1.125 water in its most desiccated state ; 
 and in its crystalline state of 5 acid -{- 2. 13 
 ammonia -|- 5.575 water.* 
 
 If sulphate of ammonia and sulphate of 
 magnesia be added together in solution, they 
 combine into a triple salt of an octaedrai 
 figure, but varying much ; less soluble than 
 either of its component parts; unalterable in 
 the air; undergoing on the fire the watery 
 fusion ; after which it is decomposed, part of 
 the ammonia flying off', and the remainder 
 subliming with an excess of acid. It con- 
 tains, according to Fourcroy, 68 sulphate of 
 magnesia, and 32 sulphate of ammonia. 
 
 Sulphate of glueina crystallizes with diffi- 
 culty, its solution readily acquiring and re- 
 taining a syrupy consistence; its taste is 
 sweet, and slightly astringent ; it is not al- 
 terable in the air ; a strong heat expels its 
 acid, and leaves the earth pure ; heated with 
 charcoal it forms a sulphuret; infusion of 
 galls forms a yellowish white precipitate with 
 its solution. 
 
 Yttria is readily dissolved by sulphuric 
 acid ; and as the solution goes on, the sul- 
 phate crystallizes in small brilliant grains, 
 which have a sweetish taste, but less so than 
 sulphate of glueina, and are of a light ame- 
 thyst red colour. They require 30 parts of 
 cold water to dissolve them, and give up 
 their acid when exposed to a high tempera- 
 ture. They are decomposed by oxalic acid, 
 prussiate of potash, infusion of galls, and 
 phosphate of soda. 
 
 Sulphate of alumina in its pure state is 
 but recently known, and it was first atten- 
 tively examined by Vauquelin. It may be 
 made by dissolving pure alumina in pure 
 sulphuric acid, heating them for some time, 
 evaporating the solution to dryness, drying 
 the residuum with a pretty strong heat, re- 
 dissolving it, and crystallizing. Its crystals 
 are soft, foliaceous, shining, and pearly ; but 
 these are not easily obtained without cau- 
 tious evaporation and refrigeration. They 
 have an astringent taste ; are little alterable 
 in the air ; are pretty soluble, particularly in 
 hot w ater ; give out their acid on exposure 
 to a high temperature ; are decomposable by 
 combustible substances, though not readily; 
 and do not form a pyrophorus like alum. 
 
 If the evaporation and desiccation directed 
 above be omitted, the alumina will remain 
 supersaturated with acid, as may be known 
 by its taste, and by its reddening vegetable 
 blue. This is still more difficult to crystal- 
 lize than the neutral salt, and frequently 
 thickens into a gelatinous mass. 
 
 A compound of acidulous sulphate of 
 alumina with potash or ammonia has long 
 
ACI 
 
 been known by the name of Alum. See 
 Alumina. 
 
 It this acidulous sulphate or alum be dis- 
 solved in water, and boiled with pure alu- 
 mina, the alumina will become saturated 
 with its base, and fall down an insipid white 
 powder. This salt is completely insoluble, 
 and is not deprived of its acid by heat but 
 at a very high temperature. It may be de- 
 composed by long boiling with the alkaline 
 or earth bases ; and several acids convert it 
 into common alum, but slowly. 
 
 Sulphate of zircon may be prepared by 
 adding sulphuric acid to the earth recently 
 precipitated, and not yet dry. It is some- 
 times in small needles, but commonly pul- 
 verulent ; very friable ; insipid ; insoluble 
 in water, unless it contain some acid ; and 
 easily decomposed by heat. 
 
 Acid (Sulphurous). It has already been 
 observed, that sulphur burned at a low tem- 
 perature absorbs less oxygen than it does 
 when exposed to greater heat, and is conse- 
 quently acidified in a slighter degree, so as 
 to form sulphurous acid. This in the ordi- 
 nary state of the atmosphere is a gas ; but 
 on reducing its temperature very low by ar- 
 tificial cold, and exposing it to strong com- 
 pression, it becomes a liquid. To obtain it 
 in the liquid state, however, for practical 
 purposes, it is received into water, by which 
 it is absorbed. 
 
 As the acid obtained by burning sulphur 
 in this way is commonly mixed with more 
 or less sulphuric acid, when sulphurous acid 
 is wanted it is commonly made by abstract- 
 ing part of the oxygen from sulphuric acid 
 by means of some combustible substance. 
 Mercury or tin is usually preferred. For 
 the purposes of manufactures, however, chop- 
 ped straw or saw-dust may be employed. 
 If one part of mercury and two of concen- 
 trated sulphuric acid be put into a glass 
 retort with a long neck, and heat applied till 
 an effervescence is produced, the sulphurous 
 acid will arise in the form of gas, and may 
 be collected over quicksilver, or received into 
 water, which at the temperature of 61° will 
 absorb 33 times its bulk, or nearly an 
 eleventh of its weight. 
 
 Water thus saturated is intensely acid to 
 the taste, and has the smell of sulphur burn- 
 ing slowly. It destroys most vegetable co- 
 lours, but the blues are reddened by it pre- 
 vious to their being discharged. A pleasing 
 instance of its effect on colours may be ex- 
 hibited by holding a red rose over the blue 
 flame of a common match, by which the 
 colour will be discharged wherever the sul- 
 phurous acid comes into contact with it, so 
 as to render it beautifully variegated, or 
 entirely white. If it be then dipped into 
 water, the redness after a time will be re- 
 stored. 
 
 * The specific gravity of sulphurous acid 
 
 ACI 
 
 gas, as given by MM. Thenard and Gay 
 Lussac, is 2. 2553, but by Sir II. Davy is 
 2.2295, and hence 100 cubic inches weigh 
 68 grains ; but its sp. gr. most probably 
 should be estimated at 2.222, and the weight 
 of 100 cubic inches will become 67.777. 
 Its constituents by volume are one of oxy- 
 gen, and one of vapour of sulphur ; each 
 having a sp. gr. of 1.1 1 1, condensed so that 
 both volumes occupy only one. Or in popu- 
 lar language, sulphurous acid may be said to 
 be a solution of sulphur in oxygen, which 
 doubles the weight of this gas, without aug- 
 menting its bulk. It obviously, therefore, 
 consists by weight of equal quantities of the 
 two constituents. Its equivalent will either 
 be 2 oxygen 2 sulphur == 40 ; or 1 oxy- 
 gen -{- 1 sulphur = 2. Now the analysis of 
 sulphite of barytes by Berzelius gives 209.22 
 base to 86.53 acid ; which being reduced, 
 presents for the prime equivalent of sulphu- 
 rous acid, the number 4. Hydrogen and 
 carbon readily decompose sulphurous acid at 
 a red heat, and even under it. Mr Higgins 
 discovered, that liquid sulphurous acid dis- 
 solves iron, without the evolution of any gas. 
 The peroxides of lead and manganese fur- 
 nish oxygen to convert it into sulphuric acid, 
 which forms a sulphate, with the resulting 
 metallic protoxide.* 
 
 Sulphurous acid is used in bleaching, par- 
 ticularly for silks. It likewise discharges 
 vegetable stains, and iron-moulds from linen. 
 
 In combination with the salifiable bases, it 
 forms sulphites, which differ from the sul- 
 phates in their properties. The alkaline 
 sulphites are more soluble than the sulphates, 
 the earthy less. They are converted into 
 sulphates by an addition of oxygen, which 
 they acquire even by exposure to the air. 
 The sulphite of lime is the slowest to under- 
 go this change. A strong heat either expels 
 their acid entirely, or converts them into sul- 
 phates. They have all a sharp, disagreeable, 
 sulphurous taste. The best mode of obtain- 
 ing them is by receiving the sulphurous acid 
 gas into water, holding the base, or its car- 
 bonate, in solution, or diffused in it in fine 
 powder. None of them has yet been applied 
 to any use. 
 
 * Acid (IIyposulphurous). In the 85th 
 volume of the Annales de Chimie, M. Gay 
 Lussac describes permanent crystallizable 
 salts having lime and strontites for their base, 
 combined with an acid of sulphur, in which 
 the proportion of oxygen is less than in sul- 
 phurous acid ; but this acid he does not seem 
 to have examined in a separate state. Those 
 salts were procured by exposing solutions of 
 the sulphurets of the earths to the air, when 
 sulphur and carbonate of lime precipitated. 
 When the filtered liquid is then evaporated, 
 and cooled, colourless crystals form. The 
 calcareous are prismatic needles, and those 
 with strontites are rhomboidal. He called 
 
 13 
 
ACI 
 
 ACI 
 
 these new compounds sulphuretted sulphites. 
 Those of potash and soda he also formed, by 
 heating their sulphites with sulphur ; when, 
 a quantity of sulphurous acid was disengag- 
 ed, and neutral salts were formed. M. Gay 
 Lussac farther informs us, that boiling a so- 
 lution of a sulphite with sulphur, determines 
 the formation of the sulphuretted sulphite, 
 or hyposulphite ; and that iron, zinc, and 
 manganese, treated with liquid sulphurous 
 acid, yield sulphuretted sulphites ; from 
 which it follows, that a portion of the sul- 
 phurous acid is decomposed by the metal, 
 and that the resulting oxide combines with 
 the other portion of the sulphurous acid and 
 the liberated sulphur. The hyposulphites 
 are more permanent than the sulphites ; they 
 do not readily pass by the action of the air 
 into the state of sulphate ; and though de- 
 composable at a high heat, they resist the 
 action of fire longer than the sulphites. 
 They are decomposed in solution by the sul- 
 phuric, muriatic, fluoric, phosphoric, and ar- 
 senic acids ; sulphurous acid is evolved, sul- 
 phur is precipitated, and a new salt is form- 
 ed. Such is the account given of these by 
 M. Gay Lussac, and copied into the second 
 volume of the Traite de Chimie of M. The- 
 nard, published in 1814. 
 
 No additional information was communi- 
 cated to the world on this subject till Janu- 
 ary 1819, when an ingenious paper on the 
 hyposulphites appeared in the Edinburgh 
 Philosophical Journal, followed soon by two 
 others in the same periodical work, by Mr 
 Herschel. 
 
 In order to obtain hyposulphurous acid, 
 Mr Herschel mixed a dilute solution of hy- 
 posulphite of strontites with a slight excess 
 of dilute sulphuric acid, and after agitation 
 poured the mixture on three filters. The first 
 was received into a solution of carbonate of 
 potash, from which it expelled carbonic acid 
 gas. The second portion being received succes- 
 sively into nitrates of silver and mercury, pre- 
 cipitated the metals copiously in the state of 
 sulphurets, but produced no effect on solutions 
 of copper, iron, or zinc. The third, being 
 tasted, was acid, astringent and bitter. When 
 fresh filtered it was clear, but it became 
 milky on standing, depositing sulphur, and 
 colouring sulphurous acid. A moderate ex- 
 posure to air, or a gentle heat, caused its 
 entire decomposition. 
 
 I he habitudes of oxide of silver in union 
 with this acid are very peculiar. Hyposul- 
 phite of soda being poured on newly preci- 
 pitated oxide of silver, hyposulphite of silver 
 was formed, and caustic soda eliminated ; 
 the only instance, says Mr Herschel, yet 
 known of the direct displacement of a fixed 
 alkali by a metallic oxide, via humida. On 
 the other hand, hyposulphurous acid newly 
 disengaged from the hyposulphite of barytes, 
 by dilute sulphuric acid, readily dissolved, 
 
 and decomposed muriate of silver, forming a 
 sweet solution, from which alcohol separated 
 the metal in the state of hyposulphite. “ Thus 
 the affinity between this acid and base, unas- 
 sisted by any double decomposition , is such as 
 to form an exception to all the ordinary rules 
 of chemical union.” This acid has a remark- 
 able tendency to form double salts with the 
 oxides of silver and alkaline bases. The 
 hyposulphite of silver and soda has an in- 
 tensely sweet taste. When hyposulphite of 
 ammonia is poured on muriate of silver, it 
 dissolves it ; and if into the saturated solu- 
 tion alcohol be poured, a white salt is preci- 
 pitated, which must be forcibly squeezed be- 
 tween blotting paper and dried in vacuo. It 
 is very soluble in water. Its sweetness is 
 unmixed with any other flavour, and so in- 
 tense as to cause pain in the throat. One 
 grain of the salt communicates a perceptible 
 sweetness to 32.000 grains of water. If the 
 alcoholic liquid be evaporated, thin lengthen- 
 ed hexangular plates are sometimes formed, 
 which are not altered by keeping, and consist 
 of the same principles. 
 
 The best way of obtaining the alkaline 
 hyposulphites is to pass a current of sulphu- 
 rous acid gas through a lixivium , formed by 
 boiling a watery solution of alkali, or alka- 
 line earth, along with sulphur. The whole of 
 the sulphurous acid is converted into the hy- 
 posulphite, and pure sulphur, unmixed with 
 any sulphite, is precipitated, while the hypo- 
 sulphite remains in solution. 
 
 Mr Herschel, from his experiments on the 
 hyposulphite of lime, has deduced the prime 
 equivalent of hyposulphurous acid, to be 
 59.25. He found that 100 parts crystallized 
 hyposulphite of lime, were equivalent to 
 121.77 hyposulphite of lead, and yielded of 
 carbonate of lime, by carbonate of ammonia, 
 a quantity equivalent to 21.75 gr. of lime. 
 Therefore the theory of equivalent ratios 
 gives us this rule : — 
 
 As 21.75 gr. lime are to its prime equi- 
 valent 3.56, so are 121.77 gr. of hyposulphite 
 of lead, to its prime equivalent. In numbers 
 21.75: 3.56: : 121.77: 19.93. From this 
 number, if we deduct the prime of the oxide 
 of lead = 14, the remainder 5.93 will be 
 the double prime of hyposulphurous acid. 
 Now this number does not materially differ 
 from 6. Hence we see that the hyposul- 
 phites, for their neutral condition, require of 
 this feeble acid 2 prime proportions. One 
 prime proportion of it is obviously made up 
 of 1 prime of sulphur =*= 2, -{- 1 oxygen = 1 ; 
 and the acid equivalent is == 3. The crys- 
 tallized hyposulphite of lime is composed of 
 6. acid -|- 5.56 lime -{- 6.75 water, being 6 
 primes of the last constituent. 
 
 It ought to be stated, that when a solution 
 of a hyposulphite is boiled down to a certain 
 degree of concentration, it begins to be ra- 
 pidly decomposed, with the deposition of 
 
act 
 
 ACI 
 
 sulphur and sulphite of lime. To obtain the 
 salt in crystals, the solution must be evapo- 
 rated at a tempciature not exceeding ] 40^ 
 bahr. It it be then filtered while hot, it 
 will yield on cooling, large and exceedingly 
 beautiful crystals, which assume a great va- 
 riety of complicated forms. They are solu- 
 ble in nearly their own weight of water at 
 3 7° Fahr. and the temperature of the solu- 
 tion falls to 31°. The specific gravity of 
 their saturated solution at 60° is 1.300 ; and 
 when it is 1.114, the liquid contains one-fifth 
 of its weight. The crystals are permanent 
 in the air. 
 
 Hyposulphites of potash and soda yield 
 deliquescent crystals of a bitter taste, and 
 both of them dissolve muriate of silver. 
 The ammoniacal salt is not easily procured 
 in regular crystals. Its taste is pungent and 
 disagreeable. The barytic hyposulphite is 
 insoluble ; the strontitic is soluble and crys- 
 tallizable. Like the other hyposulphites it 
 dissolves silver ; and while its own taste is 
 purely bitter, it produces a sweet compound 
 with muriate of silver, which alcohol throws 
 down in a syrupy form. Hyposulphite of 
 magnesia is a bitter tasted, soluble, crystalliz- 
 able, and non-deliquescent salt. All the hy- 
 posulphites burn with a sulphurous flame. 
 The sweetness of liquid hyposulphite of soda, 
 combined with muriate of silver, surpasses 
 honey in intensity, diffusing itself over the 
 whole mouth and fauces without any disa- 
 greeable or metallic flavour. A coil of zinc 
 wire speedily separates the silver in a metal- 
 lic state, thus affording a ready analysis of 
 muriate of silver. Muriate of lead is also 
 soluble in the hyposulphites, but less readily.* 
 
 * Acid (Hvposulfhuric). MM. Gay 
 Lussac and Welther have recently announc- 
 ed the discovery of a new acid combination 
 of sulphur and oxygen, intermediate be- 
 tween sulphurous and sulphuric acids, to 
 which they have given the name of hvpo- 
 sulphuric acid. It is obtained by passing a 
 current of sulphurous acid gas over the black 
 oxide of manganese. A combination takes 
 place ; the excess of the oxide of manganese 
 is separated by dissolving the hyposulphate 
 of manganese in water. Caustic barytes 
 precipitates the manganese, and forms with 
 the new acid a very soluble salt, which, freed 
 from excess of barytes by a current of car- 
 bonic acid, crystallizes regularly, like the ni- 
 trate or muriate of barytes. Hyposulphate 
 of barytes being thus obtained, sulphuric 
 acid is cautiously added to the solution, 
 which throws down the barytes, and leaves 
 the hyposulplmric acid in the water. This 
 acid bears considerable concentration under 
 the receiver of the air-pump. It consists of 
 five parts of oxygen to four of sulphur. 
 The greater number of the hyposulphates, 
 both earthy and metallic, are soluble and 
 crystallize : those of barvtcs and lime are 
 
 m * # 
 
 unalterable in the air. Suberic acid and 
 chlorine do not decompose the barytic salt. 
 The barytic salt in crystals, consists of bary- 
 tes 9. 7 + hyposulplmric acid 9.00 4 - water 
 2.25 = ‘20.9 5. 
 
 The following table exhibits the composi- 
 tion of the different acid compounds of sul- 
 phur and oxygen : — 
 
 Ilyposulphurous acid 20 sul. -j- 10 oxygen 
 
 Sulphurous acid 10 + 10 
 
 Hyposulplmric acid 8 4 - 10 
 
 Sulphuric acid 4-10 
 
 Or if we prefer to consider the quantity of 
 sulphur in each acid as = 2 , the oxygen 
 combines with it in the following propor- 
 tions: — 1 ; 2 ; 2 . 5 ; 3 . 
 
 Hyposulphuric acid is distinguished by the 
 following properties: — 
 
 1st, It is decomposed by heat into sulphu- 
 rous and sulphuric acids. 
 
 2d, It forms soluble salts with barytes, 
 strontites, lime, lead, and silver. 
 
 3d, The hyposulphates are all soluble. 
 
 4th, They yield sulphurous acid when 
 their solutions are mixed with acids, only if 
 the mixture becomes hot of itself, or be arti- 
 ficially heated. 
 
 5lh, They disengage a great deal of sul- 
 phurous acid at a high temperature, and are 
 converted into neutral sulphates. 
 
 Before quitting the acids of sulphur, it 
 deserves to be mentioned, that Dr Gules of 
 Paris, has, by means of a chest or case, call- 
 ed Boete Fumigatoire, applied the vapour of 
 burning sulphur, or sulphurous acid gas, 
 mixed with air, to the surface of the body, 
 as an air bath, with great advantage, in many 
 chronic diseases of the skin, the joints, the 
 glands, and the lymphatic system.* 
 
 Acid (Tartaric). The casks in which 
 some kinds of wine are kept become in- 
 crusted with a hard substance, tinged with 
 the colouring matter of the wine, and other- 
 wise impure, which has long been known 
 by the name of argal, or tartar, and distin- 
 guished into red and w'hite according to its 
 colour. This being purified by solution, 
 filtration, and crystallization, was termed 
 cream or crystals of tartar. It was after- 
 wards discovered, that it consisted of a pecu- 
 liar acid combined with potash ; and the 
 supposition that it was formed during the 
 fermentation of the wine, was disproved by 
 Boerhaave, Neumann, and others, who show- 
 ed that it existed ready formed in the juice 
 of the grape. It has likewise been found 
 in other fruits, particularly before they are 
 too ripe; and in the tamarind, sumac, balm, 
 carduus bened ictus, and the roots of rest- 
 harrow^ germander, and sage. The separa- 
 tion of tartaric .acid from this acidulous salt, 
 is the first discovery of Scheele that is 
 known. He saturated the superfluous acid 
 by adding chalk to a solution of the super- 
 tartrate in boiling water as long as any efler- 
 
ACI 
 
 ACI 
 
 i 
 
 vescence ensued, and expelled the acid from 
 the precipitated tartrate of lime by means of 
 the sulphuric. Or four parts of tartar may 
 be boiled in twenty or twenty-four of water, 
 and one part of sulphuric acid added gra- 
 dually. By continuing the boiling the sul- 
 phate of potash will fall down. When the 
 liquor is reduced to one- half, it is to be fil- 
 tered, and if any more sulphate be deposited 
 by continuing the boiling, the filtering must 
 be repeated. When no more is thrown 
 down, the liquor is to be evaporated to the 
 consistence of a syrup, and thus crystals of 
 tartaric acid, equal to half the weight ot the 
 tartar employed, will be obtained. 
 
 The tartaric acid may be procured in 
 needly or laminated crystals, by evaporating 
 a solution of it. Its taste is very acid and 
 agreeable, so that it may supply the place of 
 lemon-juice. It is very soluble in water. 
 Burnt in an open fire it leaves a coaly re- 
 siduum ; in close vessels it gives out carbo- 
 nic acid and carburetted hydrogen gas. By 
 distilling nitric acid off' the crystals they may 
 be converted into oxalic acid, and the nitric 
 acid passes to the state of nitrous. 
 
 * To extract the whole acid from tartar, 
 M. Thenard recommends, after saturating 
 the redundant acid with chalk, to add mu- 
 riate of lime to the supernatant neutral tar- 
 trate, by which means it is completely de- 
 composed. The insoluble tartrate of lime 
 being washed with abundance of water, is 
 then to be treated with three-fifths of its 
 weight of strong sulphuric acid, diluted pre- 
 viously with five parts of water. But Four- 
 croy’s process as improved by Vauquelin, 
 seems still better. Tartar is treated with 
 quicklime and boiling water in the propor- 
 tion, by the theory of equivalents, of 100 of 
 tartar to 50 of dry lime, or 40 of the slaked. 
 A caustic magma is obtained, w hich must be 
 evaporated to dryness, and gently heated. 
 On digesting this in water, a solution of 
 caustic potash is obtained, while tartrate of 
 lime remains ; from which the acid may be 
 separated by the equivalent quantity of oil 
 of vitriol. 
 
 According to Berzelius, tartaric acid is a 
 compound of 3.807 hydrogen -}- 35.980 car- 
 bon -f 60.213 oxygen = 100; to which re- 
 sult. he shows that of M. Gay Lussac and 
 Thenard to correspond, when allowance is 
 made for a certain portion of water, which 
 they had omitted to estimate. The analysis 
 of tartrate of lead, gives 8.384 for the acid 
 prime equivalent ; and it may be made up 
 of 3 hydrogen == 0.57 5 4.48 
 
 4 carbon = 3.000 35.82 
 
 5 oxygen = 5.000 59.70 
 
 8.375 100.00 
 
 The crystallized acid is a compound of 
 8.37 5 acid -J- 1.125 water = 9.5; or in 
 100 parts 88.15 acid -f 1 1,85 water. 
 
 The tartrates in their decomposition by fire, 
 comport themselves like all the other vege- 
 table salts, except that those with excess of 
 acid yield the smell of caramel when heated, 
 and afford a certain quantity of the pyrotar- 
 taric acid. All the soluble neutral tartrates 
 form w ith tartaric acid, bitartrates of sparing 
 solubility ; w hile all the insoluble tartrates 
 may be dissolved in an excess of their acid. 
 Hence, by pouring gradually an excess of 
 acid into barytes, strontites and lime waters, 
 the precipitates formed at first cannot fail to 
 disappear ; while those obtained by an ex- 
 cess of the same acid, added to concentrated 
 solutions of potash, soda, or ammonia, and 
 the neutral tartrates of these bases, as well as 
 of magnesia and copper, must be permanent. 
 The first are always ffocculent; the second 
 always crystalline ; that of copper alone, is 
 in a greenish white powder. It likewise 
 follows, that the greater number of acids 
 ought to disturb the solutions of the alkaline 
 neutral tartrates, because they transform 
 these salts into bitartrates ; and on the con- 
 trary, they ought to effect the solution of the 
 neutral insoluble tartrates, which indeed al- 
 ways happens, unless the acid cannot dis- 
 solve the base of the tartrate. The order of 
 apparent affinities of tartaric acid are. lime, 
 barytes, strontites, potash, soda, ammonia, 
 and magwesia. 
 
 The tartrates of potash, soda, and ammo- 
 nia, are not only susceptible of combining 
 together, but also with the other tartrates, so 
 as to form double or triple salts. We may 
 thus easily conceive why the tartrates of pot- 
 ash, soda, and ammonia, do not disturb the 
 solutions of iron and manganese; and on 
 the other hand disturb the solutions of the 
 salts of barytes, strontites, lime, and lead. 
 In the first case, double salts are formed, 
 however small a quantity of tartrate shall 
 have been employed ; in the second, no 
 double salt is formed unless the tartrate be 
 added in very great excess.* 
 
 The tartrates of lime and barytes are 
 white, pulverulent, and insoluble. 
 
 Tartrate of strontian, formed by the dou- 
 ble decomposition of muriate of strontian 
 and tartrate of potash, according to Vauque- 
 lin, is soluble, crystallizabie, and consists of 
 52.88 strontian and 47.1 2 acid. 
 
 That of magnesia forms a gelatinous or 
 gummy mass. 
 
 Tartrate of potash, the tartarized kali of 
 the London college, and vegetable salt of 
 some, formerly called soluble tartar , because 
 much more so than the supertartrate, crys- 
 tallizes in oblong squares, bevelled at the 
 extremities. It has a bitterish taste, and is 
 decomposed by heat, as its solution is even 
 by standing some time. It is used as a 
 mild purgative. 
 
 The supertartrate of potash, already men- 
 tioned at the beginning of this article, is 
 
ACI 
 
 A Cl 
 
 much used as a cooling and gently opening 
 medicine, as well as in several chemical and 
 pharmaceutical preparations. Dissolved in 
 water, with the addition of a little sugar, 
 and a slice or two of lemon- peel, it forms 
 an agieeable cooling drink by the name of 
 imperial; and if an infusion of green balm 
 be used instead of water, it makes one of 
 the pleasantest liquors of the kind with 
 which we are acquainted. Mixed with an 
 equal weight of nitre, and projected into a 
 red-hot crucible, it detonates, and forms the 
 white flux ; treated in the same way with 
 half its weight of nitre, it forms the black 
 flux ; and simply mixed with nitre in various 
 proportions, it is called raw Jiux. It is like- 
 wise used in dyeing, in hat-making, in gild- 
 ing, and in other aits. 
 
 The blanching of the crude tartar is aided 
 
 by boiling its solution with of pipe clay. 
 
 According to the analysis of Berzelius, it 
 consists of 70.45 acid + 24.8 potash + 
 4.75 water = 100; or 
 
 2 primes acid, = 16.75 70.30 
 
 1 potash, = 5.95 24.95 
 
 1 water, = 1.125 4.75 
 
 25.825 100.00 
 
 60 parts of water dissolve 4 of bitartrate at a 
 boiling heat ; and only 1 at 60° Fahr. It 
 is quite insoluble in alcohol. It becomes 
 very soluble in water, by adding to it one- 
 fifth of its weight of borax ; or even by the 
 addition of boracic acid. It appears by Ber- 
 zelius, that neutral tartrate of potash, dried 
 in the sun, differs from the bitartrate, in con- 
 taining no water of crystallization. He states 
 it to be a compound of 58.69 acid 41.31 
 potash =100; which afford 155.7 tartrate 
 of lead. Now, 8.375 : 5.95:: 58.5:41.5; 
 which are the equivalent proportions. 
 
 On considering the great solvent property 
 of cream of tartar, and that it is even capable 
 of dissolving various oxides, which are inso- 
 luble in tartaric acid, as the protoxide of an- 
 timony, M. Gay Lussac has recommended it 
 as a useful agent in chemical analysis. He 
 thinks that in many cases it acts the part of a 
 single acid. According to this view, tartar eme- 
 tic would be a compound of the cream-tartar 
 acid, and protoxide of antimony. Cream of 
 tartar generally contains from 5 to 5 per 
 cent of tartrate of lime, which are in a great 
 measure separated when 3 parts of tartar are 
 boiled with l of borax for a few minutes in 
 a sufficient quantity of water. The soluble 
 cream of tartar which is obtained by this 
 process is deliquescent; it dissolves in its 
 own weight of boiling water, at 54.5°, and 
 in half its weight of boiling water. Its solu- 
 tion is very imperfectly decomposed by the 
 sulphuric, nitric, and muriatic acids. 4 parts 
 of tartar and 1 of boracic acid form a perma- 
 nent saline compound, very soluble in water. 
 Alum also increases the solubility of tartar.* 
 
 By saturating the superfluous acid in this 
 supertartrate with soda, a triple salt is form- 
 ed, which crystallizes in larger regular prisms 
 of eight nearly equal sides, of a bitter taste, 
 efflorescent, and soluble in about live parts 
 of water. It consists, according to Vauque- 
 lin, of 54 parts tartrate of potash and 46 tar- 
 trate of soda ; and was once in much repute 
 as a purgative, by the name of Rochelle salt, 
 or sel de Seignette . 
 
 The tartrate of soda is much less soluble 
 than this triple salt, and crystallizes in slen- 
 der needles or thin plates. 
 
 The tartrate of ammonia is a very soluble, 
 bitter salt, and crystallizes easily. Its solu- 
 tion is spontaneously decomposable. 
 
 This too forms with tartrate of potash a 
 triple salt, the solution of which yields, by 
 cooling, fine pyramidal or prismatic efflores- 
 cent crystals. Though both the neutral salts 
 that compose it are bitter, this is not, but has 
 a cooling taste. 
 
 Acid (Tungstous). What has been thus 
 called appears to be an oxide of Tungsten. 
 
 * Acid (Tungstic) has been found only 
 in two minerals; one of which formerly call- 
 ed tungsten, is a tungstate of lime, and is 
 very rare ; the other more common, is com- 
 posed of tungstic acid, oxide of iron, and a 
 little oxide of manganese. The acid is se- 
 parated from the latter in the following way. 
 The wolfram cleared from its siliceous gan- 
 gue, and pulverized, is heated in a matrass 
 with five or six times its weight of muriatic 
 acid, for half an hour. The oxides of iron 
 and manganese being thus dissolved, we ob- 
 tain the tungstic acid under the form of a 
 yellow powder. After washing it repeated- 
 ly with w'ater, it is then digested in an excess 
 of liquid ammonia, heated, which dissolves 
 it completely. The liquor is filtered and 
 evaporated to dryness in a capsule. The dry 
 residue being ignited, the ammonia flies off, 
 and pure tungstic acid remains. If the wffiole 
 of the wmlfram has not been decomposed in 
 this operation, it must be subjected to the 
 muriatic acid again. 
 
 It is tasteless, and does not affect vegetable 
 colours. The tungstates of the alkalis and 
 magnesia are soluble and crystallizable, the 
 other earthy ones are insoluble, as well as 
 those of the metallic oxides. The acid is 
 composed of 100 parts metallic tungsten, 
 and 25 or 26.4 oxygen.* 
 
 Acid (Uric). The same with Lithic 
 Acid; which see. 
 
 Acid (Zoonic). In the liquid procured 
 by distillation from animal substances, which 
 had been supposed to contain only carbonate 
 of ammonia and an oil, Berthollet imagin- 
 ed he had discovered a peculiar acid, to 
 which he gave the name of zoonic. The- 
 nard, however, has demonstrated that it is 
 merely acetic acid combined with an animal 
 matter. 
 
ACT 
 
 ADA 
 
 * Acid (Zumic). An acid called by M. 
 Braconnot, Nanceic, in honour of the town 
 of Nancy, where he lives. He discovered it 
 in many acescent vegetable substances ; in 
 sour rice ; in putrefied juice of beet-root ; in 
 sour decoction of carrots, peas, &c. He 
 imagines that this acid is generated at the 
 same time as vinegar in organic substances, 
 when they become sour. It is without colour, 
 does not crystallize, and has a very acid taste. 
 
 He concentrates the soured juice of the 
 beet-root till it become almost solid, digests 
 it with alcohol, and evaporates the alcoholic 
 solution to the consistence of syrup. He 
 dilutes this with w'ater, and throws into it car- 
 bonate of zinc till it be saturated. He passes 
 the liquid through a filter, and evaporates till 
 a pellicle appear. The combination of the 
 new acid with oxide of zinc crystallizes. After 
 a second crystallization, he redissolves it in 
 water, pours in an excess of water of barytes, 
 decomposes by sulphuric acid the barytic salt 
 formed, separates the deposit by a filter, and 
 obtains, by evaporation, the new acid, pure. 
 
 It forms with alumina a salt resembling 
 gum, and with magnesia one unalterable in 
 the air, in little granular crystals, soluble in 
 25 parts of water at 66° Fahr; with potash 
 and soda it forms uncrystallizable salts, deli- 
 quescent and solublein alcohol ; with lime and 
 strontites, soluble granular salts ; with barytes, 
 an uncrystallizable nondeliquescent salt hav- 
 ing the aspect of gum ; with white oxide of 
 manganese, a salt which crystallizes in tetrahe- 
 dral prisms, soluble in 12 parts of water at 
 60° ; with oxide of zinc, a salt crystallizing 
 in square prisms, terminated by summits 
 obliquely truncated, soluble in 50 parts of 
 w’ater at 66° ; with iron, a salt crystallizing 
 in slender four-sided needles, of sparing so- 
 lubility, and not changing in the air ; with 
 red oxide of iron, a white noncrystallizing 
 salt; with oxide of tin, a salt crystallizing in 
 wedge-form octahedrons; with oxide of lead, 
 an uncrystallizable salt, not deliquescent, and 
 resembling a gum ; with black oxide of mer- 
 cury, a very soluble salt, which crystallizes 
 in needles.* 
 
 Acimfiagle. Capable of being con- 
 verted into an acid by an acidifying prin- 
 ciple. (See Acid). Substances possessing 
 this property are called radicals , or acidijiable 
 bases. 
 
 AcinuLjr. A term applied by the French 
 chemists to those salts, in which the base is 
 combined with such an excess of acid, that 
 they manifestly exhibit acid properties; such 
 as the supertartrate of potash. 
 
 * Aconita. A poisonous vegetable princi- 
 ple, probably alkaline, recently extracted from 
 the Slconilvm napellus, or Wolfsbane, by M. 
 Braudes. The details of the analysis have 
 not reached this country.* 
 
 * Actinolite. Strahlstcin of Werner. 
 | Amphibole J dirt ate hexaedre of Many. ’There 
 
 are three varieties of this mineral : the crys- 
 tallized , the asbestous , and the glassy. 
 
 1st , Crystallized actinolite. Colour leek 
 green, and green of darker shades. It crystal- 
 lizes in long oblique hexahedral prisms with 
 irregular terminations. Crystals frequently 
 striated lengthwise, sometimes acicular. Its 
 lustre is shining. It is translucent. Occa- 
 sionally it is found in silky fibres. Its sp. 
 gr. varies from 3.0 to 3.3. Fracture usually 
 radiated; sometimes it is foliated with an in- 
 distinct twofold cleavage. It scratches glass. 
 
 2d, Asbestous actinolite. Colours green, 
 verging on grey and brown, and smalt-blue. 
 Massive and in elastic capillary crystals, 
 which are grouped in wedge-shaped, radi- 
 ated or promiscuous masses. Internal lustre 
 pearly. Melts before the blowpipe into a 
 dark glass. Fracture intermediate between 
 fibrous and narrow radiated. Fragments 
 wedge-shaped. Opaque. Soft. Tough but 
 sectile. Sp. gr. 2.7 to 2.9. 
 
 3d, Glassy actinolite. Colours, mountain 
 green, and emerald green. In thin six sided 
 needle-form crystals. Has cross rents. Sp. 
 gr. from 3.0 to 3.2. The composition of 
 actinolite is very differently stated by differ- 
 ent analysts. Laugier’s results with glassy 
 actinolite are the following, and they ap- 
 proximate to those of Vauquelin on asbestous 
 actinolite; silica 50, lime 9.75, magnesia 
 19.25, oxide of iron 11, alumina 0.75, oxide 
 of manganese 0.5, oxide of chromium 3 f 
 potash 0.5, moisture 5, loss 0.25. 28.2 
 
 of alumina and 3.84 of tungstic acid w r ere 
 found in 100 parts of asbestous actinolite 
 from Cornwall, analyzed by Dr Thomson. 
 Actinolite is found chiefly in primitive dis- 
 tricts, with a magnesian basis. It accom- 
 panies talc, and some micaceous rocks. Its 
 principal localities are Zillcrthal, in the 
 Tyrol, Mont St Gothard, near Saltzburg, 
 in Saxony ; in Norway and in Piedmont. 
 In Great Britain, it is found in Cornwall 
 and Wales ; and in Glen Elg, the isles of 
 Lewis and Sky. It is never found in se- 
 condary mountains.* 
 
 Adamant. See Diamond. 
 
 Adamantine Spar. This stone, which 
 comes to us from the peninsula of Hither 
 India, and also from China, has not en- 
 gaged the attention of the chemical world 
 till within a few years past. It is remarkable 
 for its extreme hardness, which approaches 
 to that of the diamond, and by virtue of 
 which property it is used for polishing gems. 
 
 Two varieties of this stone are known in 
 Europe. The first comes from China. It 
 is crystallized, in six-sided prisms, without 
 pyramids, the length of which varies from 
 half an inch to an inch, and their thickness 
 is about three quarters of an inch. Its co- 
 lour is gray of different shades. The larger 
 pieces are opaque ; but thin pieces and the 
 edges of the prisms are transparent. Its 
 II 
 
ADH 
 
 ADI 
 
 fracture is brilliant, and its texture spathose ; 
 which causes its surface to appear lightly 
 striated. Its crystals are covered with a very 
 fine and strongly adherent crust of plates of 
 silvery mica, mixed with particles of red fel- 
 spar. A yellow superficial covering of sul- 
 phate of iron was observed upon one specimen. 
 
 This stone is so hard that it not only cuts 
 glass as easily as a diamond, but likewise 
 marks rock crystal and several other hard 
 stones. Its specific gravity is 3.710. 
 
 Small crystalline grains of magnetical fer- 
 ruginous calx are occasionally found in the 
 adamantine spar of China, which may be se- 
 parated by the magnet when the stone is pul* 
 verized. 
 
 The second variety, which comes from 
 India, is called Corundum by the inhabitants 
 of Bombay. It differs from the former by a 
 white colour, a texture more evidently spa- 
 those, and lastly, because the grains of mag- 
 netical iron are smaller than in the former 
 specimens, and are not interspersed through 
 its substance, but only at its surface. 
 
 From its hardness it is extremely difficult 
 to analyze. M. Chenevix, by repeatedly 
 heating it red hot, and then plunging it into 
 cold water, caused it to appear fissured in 
 every direction. He then put it into a steel 
 mortar, about three quarters of an inch in 
 diameter, and three inches deep, to which a 
 steel pestle was closely fitted. A few blows 
 on the pestle caused it to crumble, and the 
 fragments were then easily reduced to an 
 impalpable powder by an agate pestle and 
 mortar. This powder was fused in a cru- 
 cible of platinum with twice its weight of cal- 
 cined borax, and the glass was dissolved by 
 boiling in muriatic acid about twelve hours. 
 The precipitates from this solution being ex- 
 amined, a specimen from China w f as found 
 to give from 100 parts, 86.50 of alumina, 
 5.25 of silex, 6.50 of iron : one from Ava, 
 alumina 87, silex 6.5, iron 4.5 : one from Ma- 
 labar, alumina 86.5, silex 7, iron 4 : one from 
 the Carnatic, alumina 91, silex 5, iron 1.5. 
 
 The Rev. Mr W. Gregor analyzed a spe- 
 cimen from Thibet, in the collection of Mr 
 Rashleigh, which gave him alumina 81.75, 
 silex 1 2. 1 25, oxide of titanium 4, water 0.937, 
 but no iron. 
 
 This stone has been said to have been 
 found in different parts of Europe, and near 
 Philadelphia in America; but most, if not 
 all of the specimens have proved not to be 
 the adamantine spar. Lately, however, Prof. 
 Pini has discovered a stone in Italy, the cha- 
 racters of which, as given by him, agree with 
 those of the adamantine spar. See Corundum. 
 
 Adhesion. See Cohesion. 
 
 * Adhesive Slate. See Slate.* 
 
 Adipocere. The attention of chemists has 
 been much excited by the spontaneous con- 
 version of animal matter into a substance 
 considerably resembling spermaceti. file 
 
 fact has long been well known, and is said 
 to have been mentioned in the works of 
 Lord Bacon, though I have not seen the 
 passage. On the occasion of the removal 
 of a very great number of human bodies 
 from the ancient burying-place des Innocens 
 at Paris, facts of this nature w r ere observed 
 in the most striking manner. Fourcroy 
 may be called the scientific discoverer of this 
 peculiar matter, as w r ell as the saponaceous 
 ammoniacal substance contained in bodies 
 abandoned to spontaneous destruction in 
 large masses. This chemist read a memoir 
 on the subject in the year 1789 to the Royal 
 Academy of Sciences, from which I shall 
 abstract the general contents. 
 
 At the time of clearing the before men- 
 tioned burying-place, certain philosophers 
 were specially charged to direct the precau- 
 tions requisite for securing the health of the 
 workmen. A new and singular object of' 
 research presented itself, which had been ne- 
 cessarily unknown to preceding chemists. It 
 was impossible to foretell w hat might be the 
 contents of a soil overloaded for successive 
 ages with bodies resigned to the putrefactive 
 process. This spot differed from common 
 burying-grounds, where each individual ob- 
 ject is surrounded by a portion of the soil. 
 It w r as the burying-ground of a large district, 
 wherein successive generations of the inhabi- 
 tants had been deposited for upwards of three 
 centuries. It could not he foreseen that the 
 entire decomposition might be retarded for 
 more than forty years ; neither w f as there 
 any reason to suspect that any remarkable 
 difference would arise from the singularity 
 of situation. 
 
 The remains of the human bodies im- 
 mersed in this mass of putrescence were 
 found in three different states, according to 
 the time they had been buried, the place 
 they occupied, and their relative situations 
 w ith regard to each other. The most ancient 
 w r ere simply portions of bones, irregularly 
 dispersed in the soil, which had been fre- 
 quently disturbed. A second state, in cer- 
 tain bodies which had always been insulated, 
 exhibited the skin, the muscles, tendons, 
 and aponeuroses, dry, brittle, hard, more or 
 less gray, and similar to what are called 
 mummies in certain caverns where this change 
 has been observed, as in the catacombs at 
 Rome, and the vault of the Cordeliers at 
 Toulouse. 
 
 The third and most singular state of these 
 soft parts was observed in the bodies which 
 filled the common graves or repositories. By 
 this appellation are understood cavities of 
 thirty feet in depth and twenty on each side,, 
 which were dug in the burying-ground ot 
 the Innocents, and were appropriated to con- 
 tain the bodies of the poor ; which were 
 placed in very close rows, each in its proper 
 wooden bier. The necessity for disposing * 
 
ADI 
 
 ADI 
 
 great number obliged the men charged with 
 this employment to arrange them so near 
 each other, that these cavities might be con- 
 sidered when filled as an entire mass of hu- 
 man bodies, separated only by two planks of 
 about half an inch thick. Each cavity con- 
 tained between one thousand and fifteen hun- 
 dred. When one common grave of this mag- 
 nitude was filled, a covering of about one 
 foot deep of earth was laid upon it, and ano- 
 ther excavation of the same sort was made 
 at some distance. Each grave remained 
 open about three years, which was the time 
 required to fill it. According to the ur- 
 gency of circumstances, the graves were again 
 made on the same spot after an interval of 
 time not less than fifteen years, nor more 
 than thirty. Experience had taught the 
 workmen, that this time was not sufficient 
 for the entire destruction of the bodies, and 
 had shown them the progressive changes 
 which form the object of Mr Fourcroy’s me- 
 moir. 
 
 The first of these large graves opened in 
 the presence of this chemist, had been closed 
 for fifteen years. The coffins w r ere in good 
 preservation, but a little settled, and the 
 w'ood (I suppose deal) had a yellow tinge. 
 When the covers of several w^ere taken off, 
 the bodies were observed at the bottom, 
 leaving a considerable distance between 
 their surface and the cover, and flattened 
 as if they had suffered a strong compression. 
 The linen which had covered them was 
 slightly adherent to the bodies ; and, with 
 the form of the different regions, exhibited, 
 on removing the linen, nothing but irregular 
 masses of a soft ductile matter of a gray 
 white colour. These masses environed the 
 bones on all sides, which had no solidity, 
 but broke by any sudden pressure. The 
 appearance of this matter, its obvious com- 
 position and its softness, resembled common 
 white cheese ; and the resemblance w r as 
 more striking from the print which the 
 threads of the linen had made upon its sur- 
 face. This white substance yielded to the 
 touch, and became soft when rubbed for a 
 time between the fingers. 
 
 No very offensive smell was emitted from 
 these bodies. The novelty and singularity 
 of the spectacle, and the example of the 
 grave-diggers, dispelled every idea either of 
 disgust or apprehension. These men as- 
 serted that they never found this matter, by 
 them called gras (fat), in bodies interred 
 alone ; but that the accumulated bodies of 
 the common graves only were subject to 
 this change. On a very attentive examina- 
 tion of a number of bodies passed to this 
 state, M. Fourcroy remarked, that the con- 
 version appeared in different stages of ad- 
 vancement, so that, in various bodies, the 
 fibrous texture and colour, more or less red, 
 were discernible within the fatty matter ; 
 
 that the masses covering the bones were en- 
 tirely of the same nature, offering indistinct- 
 ly in all the regions a gray substance, for the 
 most part soft and ductile, sometimes dry, 
 always easy to be separated in porous frag- 
 ments , penetrated with cavities, and no 
 longer exhibiting any traces of membranes, 
 muscles, tendons, vessels, or nerves. On 
 the first inspection of these white masses, ife 
 might have been concluded that they were 
 simply the cellular tissue, the compartments 
 and vesicles of which they very w r ell repre- 
 sented. 
 
 By examining this substance in the dif- 
 ferent regions of the body, it w r as found that 
 the skin is particularly disposed to this re- 
 markable alteration. It was afterwards per- 
 ceived that the ligaments and tendons no 
 longer existed, or at least had lost their te- 
 nacity : so that the bones w ere entirely un- 
 supported, and left to the action of their 
 own weight. Whence their relative places 
 W'ere preserved in a certain degree by mere 
 juxtaposition; the least effort being suffi- 
 cient to separate them. The grave-diggers 
 availed themselves of this circumstance in 
 the removal of the bodies. For they rolled 
 them up from head to feet, and by that 
 means separated from each other the ex- 
 tremities of the bones, which had formerly 
 been articulated. In all these bodies which 
 w-ere changed into the fatty matter, the ab- 
 dominal cavity had disappeared. The tegu- 
 ments and muscles of this region being con- 
 verted into the white matter, like the other 
 soft parts, had subsided upon the vertebral 
 column, and were so flattened as to leave no 
 place for the viscera, and accordingly there 
 was scarcely ever any trace observed in the 
 almost obliterated cavity. This observation 
 was for a long time matter of astonishment 
 to the investigators. In vain did they seek 
 in the greater number of bodies the place 
 and substance of the stomach, the intestines, 
 the bladder, and even the liver, the spleen, 
 the kidneys, and the matrix in females. All 
 these viscera were confounded together, and 
 for the most part no traces of them were 
 left. Sometimes only certain irregular masses 
 were found, of the same nature as the white 
 matter, of different bulks, from that of a nut 
 to tw r o or three inches in diameter, in the 
 regions of the liver or of the spleen. 
 
 The thorax likewise offered an assemblage 
 of facts no less singular and interesting. 
 The external part of this cavity was flatten- 
 ed and compressed like the rest of the or- 
 gans ; the ribs, spontaneously luxated in 
 their articulations with the vertebrae, were 
 settled upon the dorsal column ; their arch- 
 ed part left only a small space on each side 
 between them and the vertebrae. The pleura, 
 the mediastines, the large vessels, the aspera 
 arteria, and even the lungs and the heart, 
 w ere no longer distinguishable ; but for the 
 
ADI 
 
 ADI 
 
 most part had entirely disappeared, and in 
 their place nothing was seen but some par- 
 cels of the fatty substance. In this case, 
 the matter which was the product of decom- 
 position of the viscera, charged with blood 
 and various humours, differs from that of the 
 surface of the body, and the long bones, in 
 the red or brown colour possessed by the 
 former. Sometimes the observers found in 
 the thorax a mass irregularly rounded, of 
 the same nature as the latter, which appear- 
 ed to them to have arisen from the fat and 
 fibrous substance of the heart. They sup- 
 posed that this mass, not constantly found in 
 all the subjects, owed its existence to a super- 
 abundance of fat in this viscus, where it was 
 found. For the general observation present- 
 ed itself, that in similar circumstances, the 
 fat parts undergo this conversion more evi- 
 dently than the others, and afford a larger 
 quantity of the white matter. 
 
 The external region in females exhibited 
 the glandular and adipose mass of the 
 breasts converted into the fatty matter very 
 white and very homogeneous. 
 
 The head was, as has already been re- 
 marked, environed with the fatty matter ; 
 the face was no longer distinguishable in the 
 greatest number of subjects ; the mouth dis- 
 organized exhibited neither tongue nor pa- 
 late ; and the jaws, luxated and more or less 
 displaced, were environed with irregular 
 layers of the white matter. Some pieces of 
 the same matter usually occupied the place 
 of the parts situated in the mouth ; the car- 
 tilages of the nose participated in the general 
 alteration of the skin ; the orbits instead of 
 eyes contained white masses ; the ears were 
 equally disorganized ; and the hairy scalp, 
 having undergone a similar alteration to that 
 of the other organs, still retained the hair. 
 M. Fourcroy remarks incidentally, that the 
 hair appears to resist every alteration much 
 longer than any other part of the body. The 
 cranium constantly contained the brain con- 
 tracted in bulk ; blackish at the surface, and 
 absolutely changed like the other organs. In 
 a great number of subjects which were exa- 
 mined, this viscus was never found wanting, 
 and it was always in the above-mentioned 
 state ; which proves that the substance of the 
 brain is greatly disposed to be converted into 
 the fat matter. 
 
 Such was the state of the bodies found in 
 the burial-ground des Innocens. Its modi- 
 fications were also various. Its consistence 
 in bodies lately changed, that is to say, from 
 three to five years, was soft and very ductile ; 
 containing a great quantity of water. In 
 other subjects converted into this matter for 
 a long time, such as those which occupied 
 the cavities which had been closed thirty or 
 forty years, this matter is drier, more brittle, 
 and in denser flakes. In several which were 
 deposited iu dry earth, variou# portions of the 
 
 fatty matter had become semi-transparent. 
 The aspect, the granulated texture, and 
 brittleness of this dried matter, bore a consi- 
 derable resemblance to wax. 
 
 The period of the formation of this sub- 
 stance had likewise an influence on its pro- 
 perties. In general, all that which had been 
 formed for a long time was white, uniform, 
 and contained no foreign substance, or fibrous 
 remains; such, in particular, was that afford- 
 ed by the skin of the extremities. On the 
 contrary, in bodies recently changed, the 
 fatty matter was neither so uniform nor so 
 pure as in the former ; but it was still found 
 to contain portions of muscles, tendons, and 
 ligaments, the texture of which, though al- 
 ready altered and changed in its colour, was 
 still distinguishable. Accordingly, as the 
 conversion was more or less advanced, these 
 fibrous remains were more or less penetrat- 
 ed with the fatty matter, interposed as it 
 were between the interstices of the fibres. 
 This observation shews, that it is not merely 
 the fat which is thus changed, as w as natu- 
 ral enough to think at first sight. Other 
 facts confirm this assertion. The skin, as 
 has been remarked, becomes easily converted 
 into very pure white matter, as does likewise 
 the brain, neither of which has been consi- 
 dered by anatomists to be fat. It is true, 
 nevertheless, that the unctuous parts, and 
 bodies charged with fat, appear more easily 
 and speedily to pass to the state under consi- 
 deration. This was seen in the marrow, 
 wfliich occupied the cavities of the longer 
 bones. And again, it is not to be supposed, 
 but that the greater part of these bodies had 
 been emaciated by the illness which termi- 
 nated their lives ; notwithstanding which, 
 they w'ere all absolutely turned into this fatty 
 substance. 
 
 An experiment made by M. Poulletier de 
 la Salle, and Fourcroy likewise, evinced that 
 a conversion docs not take place in the fat 
 alone. M. Poulletier had suspended in his 
 laboratory a small piece of the human liver, 
 to observe wfliat would arise to it bv the con- 
 tact of the air. It partly putrefied, without, 
 however, emitting any very noisome smell. 
 Larvae of the dennestes and bruchus attack- 
 ed and penetrated it in various directions ; at 
 last it became dry, and after more than ten 
 years’ suspension, it was converted into a 
 white friable substance resembling dried 
 agaric, which might have been taken for an 
 earthy substance. In this state it had no 
 perceptible smell. M. Poulletier was de- 
 sirous of knowing the state of this animal 
 matter, and experiment soon convinced him 
 and M. F. that it was very far from being 
 in the state of an earth. It melted by heat, 
 and exhaled in the form of vapour, which 
 had the smell of a very fetid fat; spirit of 
 wine separated a conereseible oil, which 
 appeared to possess all the properties oi 
 
ADI 
 
 ADI 
 
 spermaceti. Each of the three alkalis con- 
 verted it into soap, and in a word it exhibit- 
 ed all the properties of the fatty matter of 
 the burial-ground of the Innocents exposed 
 for several months to the air. Here then 
 was a glandular organ, which in the midst 
 of the atmosphere had undergone a change 
 similar to that of the bodies in the burying- 
 place ; and this fact sufficiently shews, that 
 an animal substance which is very far from 
 being of the nature of grease, may be totally 
 converted into this fatty substance. 
 
 Among the modifications of this remark- 
 able substance in the burying-ground before 
 mentioned, it w r as observed that the dry, 
 friable, and brittle matter, was most com- 
 monly found near the surface of the earth, 
 and the soft ductile matter at a greater depth. 
 M. Fourcroy remarks, that this dry matter 
 did not differ from the other merely in con- 
 taining less water, but likewise by the vola- 
 tilization of one of its principles. 
 
 The grave-diggers assert, that near three 
 years are required to convert a body into 
 this fatty substance. But Dr Gibbes of 
 Oxford found, that lean beef secured in a 
 running stream was converted into this fatty 
 matter at the end of a month. He judges 
 from facts, that running water is most fa- 
 vourable to this process. He took three 
 lean pieces of mutton, and poured on each 
 a quantity of the three common mineral 
 acids. At the end of three days, each w r as 
 much changed : that in the nitric acid w r as 
 very soft, and converted into the fatty mat- 
 ter ; that in the muriatic acid was not in 
 that time so much altered ; the sulphuric 
 acid had turned the other black. M. La- 
 voisier thinks that this process may hereafter 
 prove of great use in society. It is not 
 easy to point out what animal substance, or 
 what situation, might be the best adapted for 
 an undertaking of this kind. M. L. points 
 out fecal matters ; but I have not heard of 
 any conversion having taken place in these 
 animal remains, similar to that of the fore- 
 going. 
 
 The result of M. Fourcroy’s inquiries into 
 the ordinary changes of bodies recently de- 
 posited in the earth, w as not very extensive. 
 The grave-diggers informed him, that these 
 bodies interred do not perceptibly change 
 colour for the first seven or eight days ; that 
 the putrid process disengages elastic fluid, 
 which inflates the abdomen, and at length 
 bursts it ; that this event instantly causes 
 vertigo, faintness, and nausea in such per- 
 sons as unfortunately are within a certain 
 distance of the scene where it takes place ; 
 but that when the object of its action is 
 nearer, a sudden privation of sense, and fre- 
 quently death, is the consequence. These 
 men are taught by experience, that no im- 
 mediate danger is to he feared from the dis- 
 gusting business they arc engaged in, ex- 
 
 cepting at this period, which they regard 
 with the utmost terror. They resisted 
 every inducement and persuasion which 
 these philosophers made use of, to prevail on 
 them to assist their researches into the na- 
 ture of this active and pernicious vapour. 
 M. Fourcroy takes occasion from these facts, 
 as w r ell as from the pallid and unwholesome 
 appearance of the grave-diggers, to reprobate 
 burials in great towns or their vicinity. 
 
 Such bodies as are interred alone, in the 
 midst of a great quantity of humid earth, 
 are totally destroyed by passing through 
 the successive degrees of the ordinary putre- 
 faction ; and this destruction is more speedy, 
 the warmer the temperature. But if these 
 insulated bodies he dry and emaciated ; if 
 the place of deposition be likew ise dry, and 
 the locality and other circumstances such, 
 that the earth, so far from receiving mois- 
 ture from the atmosphere, becomes still more 
 effectually parched by the solar rays ; — the 
 animal juices are volatilized and absorbed, 
 the solids contract and harden, and a pecu- 
 liar species of mummy is produced. But 
 every circumstance is very different in the 
 common burying- grounds. Heaped toge- 
 
 ther almost in contact, the influence of ex- 
 ternal bodies affects them scarcely at all, and 
 they become abandoned to a peculiar disor- 
 ganization, which destroys their texture, and 
 produces the new r and most permanent state 
 of combination here described. From va- 
 rious observations which I do not here 
 extract, it was found, that this fatty matter 
 w r as capable of enduring in these burying- 
 places for thirty or forty years, and is at 
 length corroded and carried offiby the aqueous 
 putrid humidity which there abounds. 
 
 Among other interesting facts afforded by 
 the chemical examination of this substance, 
 are the following from experiments by M*. 
 Fourcroy. 
 
 1 . This substance is fused at a less de- 
 gree of heat than that of boiling water, and 
 may be purified by pressure through a cloth, 
 which disengages a portion of fibrous and 
 bony matter. 2 . The process of destructive 
 distillation by a very graduated heat w r as be** 
 gun, hut not completed on account of its te- 
 diousness, and the little promise of advan- 
 tage it afforded. The products which came- 
 over were water charged with volatile alkali, 
 a fat oil, concrete volatile alkali, and no 
 elastic fluid during the time the operation 
 was continued. 3. Fragments of the fatty 
 matter exposed to the air during the hot and 
 dry summer of 1 78G became dry, brittle, and 
 almost pulverulent at the surface. On a 
 careful examination, certain portions were 
 observed to be semi-transparent, and more 
 brittle than the rest. These possessed all 
 the apparent properties of wax, and did not 
 a fiord volatile alkali by distillation. 4. With 
 water this fatty matter exhibited all the ap* 
 
ADI 
 
 ADI 
 
 pearances of soap, and afforded a strong 
 lather. I he dried substance did not form 
 the saponaceous combination with the same 
 facility or perfection as that which was re- 
 cent. About two-thirds of this dried matter 
 separated from the water by cooling, and 
 proved to be the semi-transparent substance 
 resembling wax. This was taken from the 
 surface of the soapy liquor, which being 
 then passed through the filter, left a white 
 soft shining matter, which w\as fusible and 
 combustible. 5. Attempts were made to 
 ascertain the quantity of volatile alkali in 
 this substance by the application of lime, 
 and of the fixed alkalis, but without success : 
 for it was difficult to collect and appreciate 
 the first portions which escaped, and like- 
 wise to disengage the last portions. The 
 caustic volatile alkali, with the assistance of 
 a gentle heat, dissolved the fatty matter, 
 and the solution became perfectly clear and 
 transparent at the boiling temperature of the 
 mixture, which was at 185° F. 6. Sulphuric 
 acid, of the specific gravity of 2.0, was pour- 
 ed upon six times its weight of the fatty 
 matter, and mixed by agitation. Heat was 
 produced, and a gas or effluvium of the most 
 insupportable putrescence was emitted, which 
 infected the air of an extensive laboratory for 
 several days. M. Fourcroy says, that the 
 smell cannot be described, but that it is one 
 of the most horrid and repulsive that can be 
 imagined. It did not, however, produce 
 any indisposition either in himself or his 
 assistants. By dilution with water, and the 
 ordinary processes of evaporation and cool- 
 ing, properly repeated, the sulphates of am- 
 monia and of lime were obtained. A sub- 
 stance was separated from the liquor, which 
 appeared to be the waxy matter, somewhat 
 altered by the action of the acid. 7. The 
 nitrous and muriatic acids were also applied, 
 and afforded phenomena worthy of remark, 
 but which for the sake of conciseness are 
 here omitted. 8. Alcohol does not act on 
 this matter at the ordinary temperature of 
 the air. But by boiling it dissolves one- 
 third of its own weight, which is almost to- 
 tally separable by cooling as low r as 55°. 
 The alcohol, after this process, affords by 
 evaporation a portion of that waxy matter 
 which is separable by acids, and is therefore 
 the only portion soluble in cold alcohol. 
 The quantity of fatty matter operated on, 
 was 4 ounces, or 2304 grains, of which the 
 boiling spirit took up the whole except 26 
 grains, which proved to be a mixture of 20 
 grains of ammoniacal soap, and 6 or 8 grains 
 of the phosphates of soda and of lime. From 
 this experiment, which was three times re- 
 peated w r ith similar results, it appears that 
 alcohol is well suited to afford an analysis of 
 the fatty matter. It does not dissolve the 
 neutral salts ; when cold it dissolves that 
 pprtion of concrete animal oil from which 
 
 the volatile alkali had flown off, and when 
 heated it dissolves the whole of the truly 
 saponaceous matter, w hich is afterwards com- 
 pletely separated by cooling. And accord- 
 ingly it w as found, that a thin plate of the 
 fatty matter, which had lost nearly the whole 
 of its volatile alkali, by exposure to the air 
 for three years, was almost totally dissolved 
 by the cold alcohol. 
 
 The concrete oily or waxy substance ob- 
 tained in these experiments constitutes the 
 leading object of research, as being the pe- 
 culiar substance with which the other well 
 know n matters are combined. It separates 
 spontaneously by the action of the air, as 
 well as by that of acids. These last separate 
 it in a state of greater purity, the less dis- 
 posed the acid may be to operate in the way 
 of combustion. It is requisite, therefore, for 
 this purpose, that the fatty matter should be 
 previously diffused in 12 times its weight of 
 hot water ; and the muriatic or acetous acid 
 is preferable to the sulphuric or the nitrous. 
 The colour of the waxy matter is grayish ; 
 and though exposure to the air, and also the 
 action of the oxygenated muriatic acid did 
 produce an apparent whiteness, it neverthe- 
 less disappeared by subsequent fusion. No 
 method was discovered by which it could be 
 permanently bleached. 
 
 The nature of this wax or fat is different 
 from that of any other known substance of 
 the like kind. When slowly cooled after 
 fusion, its texture appears crystalline or 
 shivery, like spermaceti ; but a speedy cool- 
 ing gives it a semi-transparency resembling 
 wax. Upon the w hole, nevertheless, it seems 
 to approach more nearly to the former than 
 to the latter of these bodies. It has less 
 smell than spermaceti, and melts at 127° F.j 
 Dr Bostock says 92°. Spermaceti requires 
 6° more of heat to fuse it, (according to Dr 
 Bostock 20°). The spermaceti did not so 
 speedily become brittle by cooling as the 
 adipocere. One ounce of alcohol of the 
 strength between 39 and 40 degrees of 
 Baume’s areometer, dissolved when boiling 
 hot 12 gros of this substance, but the same 
 quantity in like circumstances dissolved only 
 30 or 36 grains of spermaceti. The separa- 
 tion of these matters was also remarkably 
 different, the spermaceti being more speedily 
 deposited, and in a much more regular and 
 crystalline form. Ammonia dissolves with 
 singular facility, and even in the cold, this 
 concrete oil separated from the fatty matter ; 
 and by heat it forms a transparent solution, 
 which is a true soap. But no excess of 
 ammonia can produce such an effect with 
 spermaceti. 
 
 M. Fourcroy concludes his memoir with 
 some speculations on the change to which 
 animal substances in peculiar circumstances 
 are subject. In the modern chemistry, soft 
 animal matters arc considered as a compost. 
 
ADI 
 
 ADI 
 
 tion of the oxides of hydrogen and carbonat- 
 ed azote, more complicated than those of ve- 
 getable matters, and therefore more inces- 
 santly tending to alteration. If then the 
 carbon be conceived to unite with the oxy- 
 gen, either of the water which is present, or 
 of the other animal matters, and thus escape 
 in large quantities in the form of carbonic 
 acid gas, we shall perceive the reason why 
 this conversion is attended with so great a 
 loss of weight, namely, about nine-tenths of 
 the whole. The azote, a principle so abun- 
 dant in animal matters, will form ammonia 
 by combining with the hydrogen ; part of 
 this will escape in the vaporous form, and 
 the rest will remain fixed in the fatty matter. 
 The residue of the animal matters deprived 
 of a great part of their carbon, of their oxy- 
 gen, and the whole of their azote, will consist 
 of a much greater proportion of hydrogen, 
 together with carbon and a minute quantity 
 of oxygen. This, according to the theory of 
 M. Fourcroy, constitutes the waxy matter, 
 or adipocere, which in combination with am- 
 monia forms the animal soap, into which the 
 dead bodies are thus converted. 
 
 Muscular fibre, macerated in dilute nitric 
 acid, and afterwards well washed in warm 
 water, affords pure adipocere, of a light 
 yellow colour, nearly of the consistence of 
 tallow', of a homogeneous texture, and of 
 course free from ammonia. This is the 
 mode in wdiich it is now' commonly procured 
 for chemical experiment. 
 
 Ambergris appears to contain adipocere 
 in large quantity, rather more than half of it 
 being of this substance. 
 
 * This curious substance has been more 
 recently examined by Chevreul. He found 
 it composed of a small quantity of ammonia, 
 potash, and lime, united to much margarine, 
 and to a very little of another fatty matter 
 different from that. Weak muriatic acid 
 seizes the three alkaline bases. On treatinsr 
 the residue with a solution of potash, the 
 margarine is precipitated in the form of a 
 pearly substance, while the other fat remains 
 dissolved. Fourcroy being of opinion that 
 the fatty matter of animal carcases, the sub- 
 stance of biliary calculi, and spermaceti, were 
 nearly identical, gave them the same name of 
 adipocere ; but it appears from the researches 
 of M. Chevreul that these substances are 
 very different from each other. 
 
 In the Philosophical Transactions for 
 18 13 there is a very interesting paper on the 
 above subject by Sir E. Home and Mr 
 Brande. He adduces many curious facts to 
 prove that adipocere is formed by an inci- 
 pient and incomplete putrefaction. Mary 
 Howard, aged 44, died on the 1 2th May 
 1790, and was buried in a grave ten feet 
 deep at the cast end of Shoreditch church- 
 yard, ten feet to the east of the great com- 
 mon sewer, which runs from north to south, 
 
 and has always a current of water in it, the 
 usual level of which is eight feet below the 
 level of the ground, and two feet above the 
 level of the coffins in the graves. In August 
 1811 the body was taken up, with some 
 others buried near it, for the purpose of 
 building a vault, and the flesh in all of them 
 was converted into adipocere or spermaceti. 
 At the full and new' moon the tide raises 
 water into the graves, which at other times 
 are dry. To explain the extraordinary quan- 
 tities of fat or adipocere formed by animals 
 of a certain intestinal construction, Sir E. 
 observes, that the current of water which 
 passes through their colon, wdiile the locu- 
 lated lateral parts are full of solid matter, 
 places the solid contents in somew hat similar 
 circumstances to dead bodies in the banks of 
 a common sewer. 
 
 The circumstance of ambergris, w'bich 
 contains 60 per cent of fat, being found in 
 immense quantities in the lower intestines of 
 the spermaceti whales, and never higher up 
 than seven feet from the anus, is an unde- 
 niable proof of fat being formed in the intes- 
 tines ; and as ambergris is only met with in 
 whales out of health, it is most probably col- 
 lected there from the absorbents, under the 
 influence of disease, not acting so as to take 
 it into the constitution. In the human 
 colon, solid masses of fat are sometimes met 
 with in a diseased state of that canal, and 
 are called scybcila. A description and ana- 
 lysis by Dr Ure of a mass of ambergris, ex- 
 tracted in Perthshire from the rectum of a 
 living woman, were published in a London 
 Medical Journal in September 1817. There 
 is a case communicated by Dr Babington, of 
 fat formed in the intestines of a girl four and 
 a half years old, and passing off by stool,. 
 Mr Brande found, on the suggestion of Sir 
 E. Home, that muscle digested in bile, is 
 convertible into fat, at the temperature of 
 about 100°. If the substance, however, pass 
 rapidly into putrefaction, no fat is formed. 
 Fasces voided by a gouty gentleman after six 
 days constipation, yielded, on infusion in 
 water, a fatty film. This process of forming 
 fat in the low r er intestines by means of bile 
 throws considerable light upon the nourish- 
 ment derived from clysters, a fact well ascer- 
 tained, but which could not be explained. 
 It also accounts for the wasting of the body 
 which so invariably attends all complaints of 
 the low'er bowels. It accounts too for all 
 the varieties in the turns of the colon, which 
 w r e meet with in so great a degree in diffe- 
 rent animals. This property of the bile ex- 
 plains likewise the formation of fatty concre- 
 tions in the gall bladder so commonly met 
 with, and which, from these experiments* 
 appear to be produced by the action of the 
 bile on the mucus secreted in the gall blad- 
 der ; and it enables us to understand how 
 want of the gall bladder in children, from 
 
A Ell 
 
 AET 
 
 mal- formation, is attended with excessive 
 leanness, notwithstanding a great appetite, 
 and leads to an early death. Fat thus ap- 
 pears to be formed in the intestines, and 
 from thence received into the circulation, 
 and deposited in almost every part of the 
 body. And as there appears to be no direct 
 channels by which any superabundance of it 
 can be thrown out of the body, whenever its 
 supply exceeds the consumption, its accumu- 
 lation becomes a disease, and often a very 
 distressing one. See Biliary concretions 
 and Margarine.* 
 
 * Adit, in mining, is a subterraneous pas- 
 sage slightly inclined, about six feet high 
 and two or three feet wide, begun at the 
 bottom of a neighbouring valley, and conti- 
 nued up to the vein, for the purpose of car- 
 rying out the minerals and drawing off the 
 water. If the mine require draining by a 
 steam-engine from a greater depth, the water 
 need be raised only to the level of the adit 
 There is a good account of the Cornish adits 
 by Mr W. Phillips, Trans. Geol. Soc. vol. 
 ii. ; and of adits in general article Galcrie , 
 Brogniart’s Mineralogy, vol. ii.* 
 
 Adopter. A vessel with two necks placed 
 between a retort and a receiver, and serving 
 to increase the length of the neck of the for- 
 mer. See Laroratory. 
 
 * Adularia. See Felspar.* 
 
 Aerated Alkaline Water. See Acid 
 
 (Carbonic). 
 
 Aerial Acin. See Acid (Carbonic). 
 
 * Aerolite or Meteoric Stone. See Me- 
 tro iiolite.* 
 
 * Aerometer. The name given by Dr 
 M. Flail to ah ingenious instrument of his 
 invention for making the necessary correc- 
 tions in pneumatic experiments, to ascertain 
 the mean bulk of the gases. It consists of 
 a bulb of glass cubic inches capacity, 
 blown at the end of a long tube whose capa- 
 city is one cubic inch. This tube is inserted 
 into another tube of nearly equal length, 
 supported on a sole. The first tube is sus- 
 tained at any height within the second by 
 means of a spring. Five cubic inches of at- 
 mospheric air, at a medium pressure and 
 temperature, are to be introduced into the 
 bulb and tube, of the latter of which it will 
 occupy one-half; the other half of this tube, 
 and part of the tube into which it is inserted, 
 are to be occupied by the fluid of the pneu- 
 matic trough, whether water or mercury. The 
 point of the tube at which the air and fluid 
 meet, is to be marked by the figure 5, denot- 
 ing 5 cubic inches. The upper and lower 
 halves of the tube are each divided into 5 
 parts, representing tenths of a cubic inch. 
 The external tube has a scale of inches at- 
 tached. Journal of Science , vol. v. See Gas. * 
 
 * Aerostation. A name commonly, but 
 not very correctly, given to the art of raising 
 heavy bodies into the atmosphere, by the 
 
 buoyancy of heated air, or gases of small 
 specific gravity, enclosed in a bag, which, from 
 being usually of a spheroidal form, is called 
 a balloon. Of all the possible shapes, the 
 globular admits the greatest capacity under 
 the least surface. Hence, of two bags of 
 the same capacity, if one be spherical, and the 
 other of any other shape, the former will 
 contain the least quantity of cloth, or the 
 least surface. The spheroidal form is there- 
 fore best fitted for aerostation. Varnished 
 
 lutestring or 
 
 muslin are employed for the 
 
 envelopes. The following 
 
 table shews the 
 
 relation betwixt the diameters, surfaces, and 
 
 capacities of spheres : 
 
 
 Diameters. Surfaces. 
 
 Capacities, 
 
 1 
 
 3.141 
 
 0.523 
 
 2 
 
 12.567 
 
 4.188 
 
 5 
 
 28.274 
 
 14.137 
 
 4 
 
 50.265 
 
 33.51 
 
 5 
 
 78.54 
 
 65.45 
 
 10 
 
 514.159 
 
 523.6 
 
 15 
 
 706.9 
 
 1767.1 
 
 20 
 
 1256.6 
 
 4189. 
 
 25 
 
 1963.5 
 
 8181. 
 
 30 
 
 2827. 
 
 14157. 
 
 40 
 
 5026. 
 
 33510. 
 
 Having ascertained by 
 
 experiment the 
 
 weight of a 
 
 square foot 
 
 of the varnished 
 
 cloth, we find, by inspection in the above 
 table, a multiplier whence we readily com- 
 pute the total weight of the balloon. A 
 cubic foot of atmospheric air weighs 527 gr. 
 and a cubic foot of hydrogen about 40. But 
 as the gas employed to fill balloons is never 
 pure, we must estimate its weight at some- 
 thing more. And perhaps, taking every 
 thing into account, we shall find it a conve- 
 nient and sufficiently precise rule for aeros- 
 tation, to consider every cubic foot of includ- 
 ed gas, to have by itself a buoyancy of fully 
 one ounce avoirdupois. Hence a balloon of 
 10 feet diameter will have an ascensional force 
 of fully 524 oz. or 33 lbs. minus the weight 
 of the 314 superficial feet of cloth ; and one 
 of 30 feet diameter, a buoyancy of fully 
 14137 oz., or nearly 890 libs, minus the 
 weight of the 2827 feet of cloth. On this 
 calculation no allowance need be made for 
 the seams of the balloon. See the article 
 Varnish.* 
 
 tEtites, or Eagle Stone, is a name that 
 has been given to a kind of hollow geodes of 
 oxide of iron, often mixed with a larger or 
 smaller quantity of silex and alumina, con- 
 taining in their cavity some concretions, 
 which rattle on shaking the stone. It is of 
 a dull pale colour, composed of concentric 
 layers of various magnitudes, of an oval or 
 polygonal form, anti often polished. Eagles 
 were said to carry them to their nests, whence 
 their name ; and superstition formerly as- 
 cribed wonderful virtues to them. 
 
AG A 
 
 Affinity (Chemical), See Attraction 
 (Chemical). 
 
 A GALMATOL1TE. See BlLDSTEIN. 
 
 Agaricus. The mushroom, a genus of 
 the order Fungi. Mushrooms appear to ap- 
 proach nearer to the nature of animal matter, 
 than any other productions of the vegetable 
 kingdom, as, beside hydrogen, oxygen, and 
 carbon, they contain a considerable portion of 
 nitrogen, and yield ammonia by distillation. 
 Prof. Proust has likewise discovered in them 
 the benzoic acid, and phosphate of lime. 
 
 A few of the species are eaten in this 
 country, but many are recorded to have pro- 
 duced poisonous effects ; though in some 
 foreign countries, particularly in Russia, very 
 few are rejected. Perhaps it is of import- 
 ance, that they should be fresh, thoroughly 
 dressed, and not of a coriaceous texture. 
 The Russians, however, are very fond of the 
 A. piperatus , which we deem poisonous, pre- 
 served with salt throughout the winter : and 
 our ketchup is made by sprinkling mush- 
 rooms with salt, and letting them stand till 
 great part is resolved into a brown liquor, 
 which is then boiled up with spices. The 
 A. piperatus has been recommended in France 
 to consumptive people. The A. muscarius 
 has been prescribed in doses of a few grains 
 in cases of epilepsy and palsy, subsequent to 
 the drying up of eruptions. 
 
 In pharmacy two species of boletus have 
 formerly been used under the name of aga- 
 ric. The B. pini laricis , or male agaric of 
 the shops, was given as a purgative, either 
 in substance, or in an extract made with 
 vinegar, wine, or an alkaline solution : and 
 the B. igniarius , spunk, or touchwood, call- 
 ed female agaric, was applied externally as a 
 styptic, even after amputations. For this 
 purpose the soft inner substance was taken, 
 and beaten w ith a hammer to render it still 
 softer. That of the oak was preferred. 
 
 * The mushrooms, remarkable for the 
 quickness of their growth, and decay, as well 
 as for the feetor attending their spontaneous 
 decomposition, were unaccountably neglected 
 by analytical chemists, though capable of 
 rewarding their trouble, as is evinced by the 
 recent investigations and discoveries of MM. 
 Vauquelin and Braconnot. The insoluble 
 fungous portion of the mushroom, though it 
 resembles woody fibre in some respects, yet 
 being less soluble than it in alkalis, and 
 yielding a nutritive food, is evidently a 
 peculiar product, to which accordingly the 
 name of f ungin has been given. Two new 
 vegetable acids, the boletic and fungic, were 
 also fruits of these researches. 
 
 1. Agaricus campestris, an ordinary article 
 of food, analyzed by Vauquelin, gave the 
 following constituents: 1. Adipocere. On 
 expressing the juice ol the agaric, and sub- 
 jecting the remainder to the action of boiling 
 alcohol, a fatty matter is extracted, which 
 
 AGA 
 
 falls down in white flakes as the alcohol 
 cools. It has a dirty wdiite colour, a fatty 
 feel like spermaceti, and, exposed to heat, 
 soon melts, and then exhales the odour of 
 grease ; 2. An oily matter ; 3. Vegetable 
 albumen ; 4. The sugar of mushrooms ; 5. 
 An animal matter soluble in w'ater and al- 
 cohol : On being heated it evolves the odour 
 of roasting meat, like osmazome ; 6. An 
 animal matter not soluble in alcohol ; 7. 
 Fungin ; 8. Acetate of potash. 
 
 2. Agaricus volvaccus afforded Braconnot 
 fungin, gelatin, vegetable albumen, much 
 phosphate of potash, some acetate of potash, 
 sugar of mushrooms, a brown oil, adipocere, 
 wax, a very fugaceous deleterious matter, 
 uncombined acid, supposed to be the acetic, 
 benzoic acid, muriate of potash, and a deal 
 of water ; in all 1 4 ingredients. 
 
 3. Agaricus acris or piperatus , was found 
 by Braconnot, after a minute analysis, to 
 contain nearly the same ingredients as the 
 preceding, w ithout the w ax and benzoic acid, 
 but with more adipocere. 
 
 4. Agaricus stypticus. From twenty parts 
 of this Braconnot obtained of resin and adi- 
 pocere 1.8, fungin 16.7, of an unknown 
 gelatinous substance, a potash salt, and a 
 fugaceous acrid principle 1.5. 
 
 5. Agaricus bulbosus , was examined by 
 Vauquelin, who found the following consti- 
 tuents ; an animal matter insoluble in alco- 
 hol, osmazome, a soft fatty matter of a yellow 
 colour and acrid taste, an acid salt, (not a 
 phosphate). The insoluble substance of the 
 agaric yielded an acid by distillation. In 
 Orfila’s Toxicology several instances are de- 
 tailed of the fatal effects of this species of 
 mushroom on the human body. Dogs were 
 killed within 24 hours by small quantities of 
 it in substance, and also by its w atery and 
 alcoholic infusions, but water distilled from 
 it was not injurious. It is curious that the 
 animals experienced little inconvenience after 
 swallowing it, during the first ten hours-; 
 stupor, cholera, convulsions, and painful 
 cramps are the usual symptoms of the poison 
 in men. The best remedy is an emetic. 
 
 6. Agaricus theogolus . In this Vauquelin 
 found sugar of mushrooms, osmazome, a 
 bitter acrid fatty matter, an animal matter 
 not soluble in alcohol, a salt containing a 
 vegetable acid. 
 
 7. Agaricus muscarius. Vauquelin’s ana- 
 lysis of this species is as follows : The two 
 animal matters of the last agaric, a fatty 
 matter, sulphate, phosphate, and muriate of 
 potash, a volatile acid from the insoluble 
 matter. The following account from Orfila 
 of the effects of this species in the animal 
 economy is interesting. Several French 
 soldiers ate, at two leagues from Polosck in 
 Russia, mushrooms of the above kind. Four 
 ol iliein, of a robust constitution, who con- 
 ceived themselves proof against the conse- 
 
AGA 
 
 AGA 
 
 quences under which their feebler com- 
 panions were beginning to suffer, refused ob- 
 stinately to take an emetic. In the evening 
 the following symptoms appeared : Anxiety, 
 sense of suffocation, ardent thirst, intense 
 griping pains, a small and irregular pulse, 
 universal cold sweats, changed expression of 
 countenance, violet tint of the nose and 
 lips, general trembling, fetid stools. These 
 symptoms becoming worse, they were car- 
 ried to the hospital. Coldness and livid 
 colour of the limbs, a dreadful delirium, and 
 acute pains, accompanied them to the last 
 moment. One of them sunk a few hours 
 after his admission into the hospital; the 
 three others had the same fate in the course 
 of the night. On opening their dead bodies, 
 the stomach and intestines displayed large 
 spots of inflammation and gangrene ; and 
 putrefaction seemed advancing very rapidly.* 
 
 Agaricus mineralis, the mountain milk , 
 or mountain meal , of the Germans, is one of 
 the purest of the native carbonates of lime, 
 found chiefly in the clefts of rocks, and at 
 the bottom of some lakes, in a loose or 
 semi-indurated form. It has been used in- 
 ternally in haemorrhages, strangury, gravel, 
 and dysenteries ; and externally as an ap- 
 plication to old ulcers, and weak and watery 
 eyes. 
 
 M. Fabroni calls by the name of mineral 
 agaric , or fossil meal, a stone of a loose con- 
 sistence found in Tuscany in considerable 
 abundance, of which bricks may be made, 
 either with or without the addition of a 
 twentieth part of argil, so light as to float 
 in water ; and which he supposes the an- 
 cients used for making their floating bricks. 
 This, however, is very different from the 
 preceding, not being even of the calcareous 
 genus, since it appears, on analysis, to con- 
 sist of silex 55 parts, magnesia 15, water 14, 
 argil 12, lime 3, iron 1. Kirwan calls it 
 argillo-murite. 
 
 * Agate. A mineral, whose basis is cal- 
 cedony, blended with variable proportions of 
 jasper, amethyst, quartz, opal, heliotrope, and 
 carnelian. Ribbon agate consists of alternate 
 and parallel layers of calcedony with jasper, 
 or quartz, or amethyst. The most beautiful 
 comes from Siberia and Saxony. It occurs 
 in porphyry and gneiss . — Brecciated agate; 
 a base of amethyst, containing fragments of 
 ribbon agate, constitute this beautiful variety. 
 It is of Saxon origin . — Fortification agate, 
 is found in nodules of various imitative 
 shapes, imbedded in amygdaloid. This hap- 
 pens at Oberstein on the Rhine, and in 
 Scotland. On cutting it across and polish- 
 ing it, the interior zig-zag parallel lines bear 
 a considerable resemblance to the plan of a 
 modern fortification. In the very centre, 
 quartz and amethyst are seen in a splintery 
 mass, surrounded by the jasper and cal- 
 cedony . — Mocha stone . Translucent calce- 
 
 dony, containing dark outlines of arbor- 
 ization, like vegetable filaments, is called 
 Mocha stone, from the place in Arabia where 
 it is chiefly found. These curious appear- 
 ances were ascribed to deposites of iron or 
 manganese, but more lately they have been 
 thought to arise from mineralized plants of 
 the cryptogamous class . — Moss agate, is a 
 calcedony with variously coloured ramifica- 
 tions of a vegetable form, occasionally tra- 
 versed with irregular veins of red jasper. 
 Dr M‘Culloch has recently detected, what 
 Daubenton merely conjectured, in mocha 
 and moss agates, aquatic confervas, unaltered 
 both in colour and form, and also coated 
 with iron oxide. Mosses and lichens have 
 also been observed, along with chlorite, in 
 vegetations. An onyx agate set in a ring, 
 belonging to the Earl of Powis, contains 
 the chrysalis of a moth. Agate is found in 
 most countries, chiefly in trap rocks, and 
 serpentine. Hollow nodules of agate called 
 geodes, present interiorly crystals of quartz, 
 colourless or amethystine, having occasional- 
 ly scattered crystals of stilbite, chabasie, and 
 capillary mesotype. These geodes are very 
 common. Bitumen has been found by M. 
 Patrin in the inside of some of them, among 
 the hills of Dauria, on the right bank of the 
 Chilca. The small geodes of volcanic dis- 
 tricts contain water occasionally in their ca- 
 vities. These are chiefly found in insulated 
 blocks of a lava having an earthy fracture. 
 When they are cracked, the liquid escapes 
 by evaporation ; it is easily restored by plung- 
 ing them for a little in hot water. Agates 
 are artificially coloured by immersion in me- 
 tallic solutions. Agates were more in de- 
 mand formerly than at present. They were 
 cut into cups and plates for boxes ; and also 
 into cutlass and sabre handles. They are 
 still cut and polished on a considerable scale 
 and at a moderate price, at Oberstein. The 
 surface to be polished is first coarsety ground 
 by large millstones of a hard reddish sand- 
 stone, moved by water. The polish is after- 
 wards given on a wheel of soft wood, mois- 
 tened and imbued with a fine powder of a 
 hard red tripoli found in the neighbourhood. 
 M. Faujas thinks that this tripoli is produced 
 by the decomposition of the porphyrated rock 
 that serves as a gangue to the agates. The 
 ancients employed agates for making cameos. 
 (See Calcedony). Agate mortars are valu- 
 ed by analytical chemists, for reducing hard 
 minerals to an impalpable powder. For 
 some interesting optical properties of agates, 
 see Light.* 
 
 The oriental agate is almost transparent, 
 and of a vitreous appearance. The occiden- 
 tal is of various colours, and often veined 
 with quartz or jasper. It is mostly found in 
 small pieces covered with a crust, and often 
 running in veins through rocks like flint and 
 petrosilex, from which it docs not seem to 
 
AGR 
 
 AIR 
 
 differ greatly. Agates are most prized, 
 when the internal figure nearly resembles 
 some animal or plant. 
 
 Aggregate. When bodies of the same 
 kind are united, the only consequence is, 
 that one larger body is produced. In this 
 case, the united mass is called an aggregate, 
 and does not differ in its chemical proper- 
 ties from the bodies from which it was ori- 
 ginally made. Elementary writers call the 
 smallest parts into which an aggregate can 
 be divided without destroying its chemical 
 properties, integrant parts. Thus the inte- 
 grant parts of common salt are the smallest 
 parts which can be conceived to remain 
 without change; and beyond these, any fur- 
 ther subdivision cannot be made without de- 
 veloping the component parts, namely, the 
 alkali and the acid ; which are still further 
 resolvable into their constituent principles. 
 
 * Agriculture, considered as a department 
 of chemistry, is a subject of vast importance, 
 but hitherto much neglected. When we 
 consider that every change in the arrange- 
 ments of matter connected with the growth 
 and nourishment of plants; the comparative 
 values of their produce as food ; the compo- 
 sition and constitution of soils ; and the 
 manner in which lands are enriched by ma- 
 nure, or rendered fertile by the different 
 processes of cultivation, we shall not hesitate 
 to assign to chemical agriculture, a high 
 place among the studies of man. If land be 
 unproductive, and a system of ameliorating 
 it is to be attempted, the sure method of at- 
 taining this object is by determining the 
 causes of its sterility, which must necessarily 
 depend upon some defect in the constitution 
 of the soil, which may easily be discovered 
 by chemical analysis. Some lands of good 
 apparent texture are yet eminently barren ; 
 and common observation and common prac- 
 tice afford no means of ascertaining the cause, 
 or of removing the effect. The application 
 of chemical tests in such cases is obvious; 
 for the soil must contain some noxious prin- 
 ciple which may be easily discovered, and 
 probably easily destroyed. Are any of the 
 salts of iron present? They may be decom- 
 posed by lime. Is there an excess of sili- 
 ceous sand ? The system of improvement 
 must depend on the application of clay and 
 calcareous matter. Is there a defect of cal- 
 careous matter? The remedy is obvious. 
 Is an excess of vegetable matter indicated? 
 It may be removed by liming, paring, and 
 burning. Is there a deficiency of vegetable 
 matter? It is to be supplied by manure. 
 Peat earth is a manure; but there are some 
 varieties of peats which contain so large a 
 quantity of ferruginous matter as to be abso- 
 lutely poisonous to plants. There has been 
 no question on which more difference of 
 opinion has existed, than that of the state in 
 which manure ought to he ploughed into 
 
 land ; whether recent, or when it has gone 
 through the process of fermentation. But 
 whoever will refer to the simplest principles 
 of chemistry, cannot entertain a doubt on 
 the subject. As soon as dung begins to de- 
 compose, it throws off its volatile parts, 
 which are the most valuable and most effi- 
 cient. Dung which has fermented so as to 
 become a mere soft cohesive mass, has gene- 
 rally lost from one- third to one-half of its 
 most useful constituent elements. See the 
 articles, Analysis, Manure, Soils, Vegeta- 
 tion, and Sir II. Davy’s Agricult. Chem.* 
 
 Air w r as, till lately, used as the generic 
 name for such invisible and exceedingly rare 
 fluids as possess a very high degree of elas- 
 ticity, and are not condensable into the li- 
 quid state by any degree of cold hitherto 
 produced ; but as this term is commonly 
 employed to signify that compound of aeri- 
 form fluids which constitutes our atmos- 
 phere, it has been deemed advisable to re- 
 strict it to this signification, and to employ 
 as the generic term the word Gas, (which 
 see), for the different kinds of air, except 
 what relates to our atmospheric compound. 
 
 Air (Atmospherical or Common). The 
 immense mass of permanently elastic fluid 
 which surrounds the globe we inhabit, must 
 consist of a general assemblage of every 
 kind of air which can be formed by the 
 various bodies that compose its surface. Most 
 of these, however, are absorbed by w r ater; 
 a number of them are decomposed by com- 
 bination with each other; and some of them 
 are seldom disengaged in considerable quan- 
 tities by the processes of nature. Hence it 
 is that the lower atmosphere consists chiefly 
 of oxygen and nitrogen, together with mois- 
 ture and the occasional vapours or exhala- 
 tions of bodies. The upper atmosphere 
 seems to be composed of a large proportion 
 of hydrogen, a fluid of so much less specific 
 gravity than any other, that it must natural- 
 ly ascend to the highest place, where, being 
 occasionally set on fire by electricity, it ap- 
 pears to be the cause of the aurora borealis 
 and fire-balls. It may easily be understood, 
 that this will only happen on the confines 
 of the respective masses of common atmos- 
 pherical air, and of the inflammable air; 
 that the combustion will extend progressive- 
 ly, though rapidly, in flashings from the 
 place w'here it commences; and that when 
 by any means a stream of inflammable air, 
 in its progress toward the upper atmos- 
 phere, is set on fire at one end, its ignition 
 may be much more rapid than what happens 
 higher up, where oxygen is wanting, and at 
 the same time more definite in its figure 
 and progression, so as to form the appear- 
 ance of a fire-ball. 
 
 * To the above speculations, it may proba- 
 bly be objected, that the air on the summit 
 of Mont Blanc, and that brought dowa 
 
AIR 
 
 AIR 
 
 from still greater heights by M. Gay Lus- 
 sac, in an aerostatic machine, gave, on ana- 
 lysis, no product of hydrogen. But the 
 lowest estimate of the height of luminous 
 meteors, is prodigiously greater than the 
 highest elevations to which man has reach- 
 ed.* See Combustion, 
 
 lhat the air of the atmosphere is so 
 transparent as to lie invisible, except by the 
 blue colour it reflects when in very large 
 masses, as is seen in the sky or region above 
 us, or in viewing extensive landscapes ; that 
 it is without smell, except that of electri- 
 city, which it sometimes very manifestly 
 exhibits; altogether without taste, and im- 
 palpable ; not condensable by any degree 
 of cold into the dense fluid state, though 
 easily changing its dimensions with its tem- 
 perature; that it gravitates and is highly 
 elastic, are among the numerous observa- 
 tions and discoveries, which do honour to 
 the sagacity of the philosophers of the se- 
 venteenth century. They likewise knew 
 that this fluid is indispensably necessary to 
 combustion ; but no one, except the great, 
 though neglected, John Mayow, appears to 
 have formed any proper notion of its manner 
 of acting in that process. 
 
 The air of the atmosphere, like other 
 fluids, appears to be capable of holding bo- 
 dies in solution. It takes up water in con- 
 siderable quantities, with a diminution of 
 its own specific gravity; from which cir- 
 cumstance, as well as from the considera- 
 tion that water rises very plentifully in the 
 vaporous state in vacuo , it seems probable, 
 that the air suspends vapour, not so much 
 by a real solution, as by keeping its parti- 
 cles asunder, and preventing their conden- 
 sation. Water likewise dissolves or absorbs 
 air. 
 
 Mere heating or cooling does not affect 
 the chemical properties of atmospherical 
 air; but actual combustion, or any process 
 of the same nature, combines its oxygen, 
 and leaves its nitrogen separate. Whenever 
 a process of this kind is carried on in a ves- 
 sel containing atmospherical air, which is en- 
 closed either by inverting the vessel over 
 mercury, or by stopping its aperture in a 
 proper manner, it is found that the process 
 ceases after a certain time ; and that the re- 
 maining air, *(if a combustible body capable 
 of solidifying the oxygen, such as phospho- 
 rus, have been employed)/ has lost about a 
 fifth part of its volume, and is of such a na- 
 ture as to be incapable of maintaining any 
 combustion for a second time, or of support- 
 ing the life of animals. From these experi- 
 ments it is clear, that one of the following 
 deductions must be true: — 1. The combus- 
 tible body has emitted some principle, which, 
 bv combining with the air, has rendered it 
 unfit, for the purpose of further combustion ; 
 or, 2. It has absorbed part of the air which 
 
 was fit for that purpose, and has left a resi- 
 due of a different nature ; or, 5. Both 
 events have happened ; namely, that the 
 pure part of the air has been absorbed, and 
 a principle has been emitted, which has 
 changed the original properties of the re- 
 mainder. 
 
 The facts must clear up these theories. 
 The first induction cannot be true, because 
 the residual air is not only of less bulk, but 
 of less specific gravity, than before. The 
 air cannot therefore have received so much 
 as it has lost. The second is the doctrine of 
 the philosophers who deny the existence of 
 phlogiston, or a principle of inflammability; 
 and the third must be adopted by those who 
 maintain that such a principle escapes from 
 bodies during combustion. This residue 
 was called phlogisticated air, in consequence 
 of such an opinion. 
 
 In the opinion that inflammable air is the 
 phlogiston, it is not necessary to reject the 
 second inference, that the air has been no 
 otherwise changed than by the mere sub- 
 traction of one of its principles: for the 
 pure or vital part of the air may unite with 
 inflammable air supposed to exist in a fixed 
 state in the combustible body ; and if the 
 product of this union still continues fixed, it 
 is evident, that the residue of the air after 
 combustion will be the same as it would 
 have been, if the vital part had been absorb- 
 ed by any other fixed body. Or, if the vital 
 air be absorbed, while inflammable air or 
 phlogiston is disengaged, and unites with 
 the aeriform residue, this residue will not be 
 heavier than before, unless the inflammable 
 air it has gained exceeds in weight the vital 
 air it has lost; and if the inflammable air 
 falls short of that weight, the residue will be 
 lighter. 
 
 These theories it was necessary to men- 
 tion ; but it has been sufficiently proved by 
 various experiments, that combustible bo- 
 dies take oxygen from the atmosphere, and 
 leave nitrogen; and that when these two 
 fluids are again mixed, in due proportions, 
 they compose a mixture not differing from 
 atmospherical air. 
 
 The respiration of animals produces the 
 same effect on atmospherical air as com- 
 bustion does, and their constant heat ap- 
 pears to be an effect of the same nature. 
 When an animal is included in a limited 
 quantity of atmospherical air, it dies as soon 
 as the oxygen is consumed ; and no other 
 air will maintain animal life but oxygen, or 
 a mixture which contains it. Bure oxygen 
 maintains the life of animals much longer 
 than atmospherical air, bulk for bulk. 
 
 * It is to be particularly observed, how- 
 ever, that, in many cases of combustion, the 
 oxygen of the air, in combining with the 
 combustible body, produces a compound, not 
 solid or liquid, but aeriform. The residual 
 
AIR 
 
 AIR 
 
 air will therefore be a mixture of the nitro- 
 gen of the atmosphere with the consumed 
 oxygen, converted into another gas. Thus, 
 in burning charcoal, the carbonic acid gas 
 generated, mixes with the residual nitrogen, 
 and makes up exactly, when the effect of 
 heat ceases, the bulk of the original air. The 
 breathing of animals, in like manner, changes 
 the oxygen into carbonic acid gas, without 
 altering the atmospherical volume.* 
 
 There are many provisions in nature by 
 which the proportion of oxygen in the at- 
 mosphere, which is continually consumed in 
 respiration and combustion, is again restored 
 to that fluid. In fact there appears, as far 
 as an estimate can be formed of the great 
 and general operations of nature, to be at 
 least as great an emission of oxygen, as is 
 sufficient to keep the general mass of the 
 atmosphere at the same degree of purity. 
 Thus, in volcanic eruptions there seems to 
 be at least as much oxygen emitted or extri- 
 cated by fire from various minerals, as is 
 sufficient to maintain the combustion, and 
 perhaps even to meliorate the atmosphere. 
 And in the bodies of plants and animals, 
 which appear in a great measure to derive 
 their sustenance and augmentation from the 
 atmosphere and its contents, it is found that 
 a large proportion of nitrogen exists. Most 
 plants emit oxygen in the sunshine, from 
 which it is highly probable that they im- 
 bibe and decompose the air of the atmo- 
 sphere, retaining carbon, and emitting the 
 vital part. Lastly, if to this we add the de- 
 composition of water, there will be nume- 
 rous occasions in which this fluid will supply 
 us with disengaged oxygen ; while, by a very 
 rational supposition, its hydrogen may be 
 considered as having entered into the bodies 
 of plants for the formation of oils, sugars, 
 mucilages, Sec. from which it may be again 
 extricated. 
 
 To determine the respirability or purity 
 of air, it is evident that recourse must be 
 had to its comparative efficacy in maintain- 
 ing combustion, or some other equivalent 
 process. This subject will be considered 
 under the article Eudiometer. 
 
 From the latest and most accurate expe- 
 riments, the proportion of oxygen in atmo- 
 spheric air is by measure about 21 per cent; 
 and it appears to be very nearly the same, 
 whether it be in this country or on the coast 
 of Guinea, on low plains or lofty mountains, 
 or even at the height of 7250 yards above 
 the level of the sea, as ascertained by Gay 
 Lussac in his aerial voyage in September 
 1805. The remainder of the air is nitro- 
 gen, with a small portion of aqueous vapour, 
 amounting to about 1 per cent in the driest 
 weather, and a still less portion of carbonic 
 acid, not exceeding a thousandth part of the 
 whole. 
 
 As oxygen and nitrogen differ in specific 
 
 gravity in the proportion of 135 to 121, ac- 
 cording to Kirwan, and of 139 to 120 ac- 
 cording to Davy, it has been presumed, that 
 the oxygen would be more abundant in the 
 lower regions, and the nitrogen in the high- 
 er, if they constituted a mere mechanical 
 mixture, which appears contrary to the fact. 
 On the other hand it has been urged, that 
 they cannot be in the state of chemical 
 combination, because they both retain their 
 distinct properties unaltered, and no change 
 of temperature or density takes place on their 
 union. But perhaps it may be said, that, as 
 they have no repugnance to mix with each 
 other, as oil and water have, the continual 
 agitation to which the atmosphere is exposed, 
 may be sufficient to prevent two fluids, dif- 
 fering not more than oxygen and nitrogen 
 in gravity, from separating by subsidence, 
 though simply mixed. On the contrary, it 
 may be argued, that to say chemical com- 
 bination cannot take place without producing 
 new properties, which did not exist before 
 in the component parts, is merely begging 
 the question ; for though this generally ap- 
 pears to be the case, and often in a very 
 striking manner, yet combination does not 
 always produce a change of properties, as 
 appears in M. Biot’s experiments with vari- 
 ous substances, of which we may instance- 
 water, the refraction of which is precisely the 
 mean of that of the oxygen and hydrogen, 
 which are indisputably combined in it. 
 
 To get rid of the difficulty, Mr Dalton of 
 Manchester framed an ingenious hypothesis, 
 that the particles of different gases neither 
 attract nor repel each other ; so that one gas 
 expands by the repulsion of its own parti- 
 cles, without any more interruption from the 
 presence of another gas, than if it were in a 
 vacuum. This would account for the state 
 of atmospheric air, it is true ; but it does not 
 agree with certain facts. In the case of the 
 carbonic acid gas in the Grotto del Cano, 
 and over the surface of brewers’ vats, why 
 does not this gas expand itself freely upward, 
 if the superincumbent gases do not press up- 
 on it ? Mr Dalton himself too instances as 
 an argument for his hypothesis, that oxygen 
 and hydrogen gases, when mixed by agita- 
 tion, do not separate on standing. But why 
 should either oxygen or hydrogen require 
 agitation, to diffuse it through a vacuum, in 
 which, according to Mr Dalton, it is placed ? 
 — C. 
 
 The theory of Berthollet appears consis- 
 tent with all the facts, and sufficient to ac- 
 count for the phenomenon. If two bodies 
 be capable of chemical combination, their 
 particles must have a mutual attraction for 
 each other. 'Ibis attraction, however, may 
 be so opposed by concomitant circumstances, 
 that it may be diminished in any degree. 
 Thus we know, that the affinity of aggrega- 
 tion may occasion a body to combine slowly 
 
Allt 
 
 ALB 
 
 with a substance for which it has a powerful 
 affinity, or even entirely prevent its combin- 
 ing with it; the presence of a third sub- 
 stance may equally prevent the combination ; 
 and so may the absence of a certain quan- 
 tity of caloric. But in all these cases the 
 attraction of the particles must subsist, 
 though diminished or counteracted by op- 
 posing circumstances. Now we know that 
 oxygen and nitrogen are capable of com- 
 bination ; their particles, therefore, must at- 
 tract each other ; but in the circumstances in 
 which they are placed in our atmosphere, 
 that attraction is prevented from exerting it- 
 self to such a degree as to form them into a 
 chemical compound, though it operates with 
 sufficient force to prevent their separating 
 by their difference of specific gravity. Thus 
 the state of the atmosphere is accounted for, 
 and every difficulty obviated, without any 
 new hypothesis. 
 
 * The exact specific gravity of atmospherical 
 air, compared to that of water, is a very nice 
 and important problem. By reducing to 
 60° Fahr. and to 30 inches of’ the barome- 
 ter, the results obtained with great care bv 
 MM. Biot and Arago, the specific gravity of 
 atmospherical air appears to be 0.001220, 
 water being represented by 1.000000. This 
 
 relation expressed fractionally is or wa- 
 ter is 820 times denser than atmospherical 
 air. Mr Rice, in the 77th and 78th num- 
 bers of the Annals of Philosophy, deduces 
 from Sir George Shuckburgh’s experiments 
 0.00120 855 for the specific gravity of air. 
 This number gives water to air as 827.437 
 to 1. If with Mr Rice we take the cubic 
 inch of water = 2.72.525 gr. then 100 cubic 
 inches of air by Biot’s experiments will weigh 
 30.808 gr. and by Mr Rice’s estimate 
 30.519. He considers with Dr Prout the 
 atmosphere to be a compound of 4 volumes 
 of nitrogen, and 1 of oxygen ; the specific 
 gravity of the first being to that of the second 
 as 1.1*111 to 0.9722. 
 
 Hence 
 
 0.8 vol. nitr. sp. gr. 0.00 1 1 66 = 0.000940 
 0.2 oxy. 0.001340= 0.000268 
 
 0.001208 
 
 The numbers are transposed in the An- 
 nals of Philosophy by some mistake. 
 
 MM. Biot and Arago found the specific 
 gravity of oxygen to be - 1.10359 
 
 and that of nitrogen, - 0.96913 
 
 air being reckoned, - 1.00000 
 
 Or compared to water as unity, — 
 
 Nitrogen is 0.001182338 
 Oxygen, 0.001346579 
 
 And 0.8 nitrogen = 0.00094587 
 
 0.2 oxygen *= 0.00026927 
 
 And 0.79 nitrogen *=^ 0.000934 
 
 0.21 oxygen = 0.000283 
 
 0.001217 
 
 A number which approaches very nearly to 
 the result of experiment. Many analogies, 
 it must be confessed, favour Dr Pr out’s pro- 
 portions ; but the greater number of experi- 
 ments on the composition and density of the 
 atmosphere agree with Biot’s results. No- 
 thing can decide these fundamental chemical 
 proportions except a new, elaborate, and most 
 minutely accurate series of experiments. We 
 shall then know whether the atmosphere con- 
 tains in volume 20 or 21 per cent of oxygen. 
 See Meteorology.* 
 
 Alabaster. Among the stones which 
 are known by the name of marble, and 
 have been distinguished by a considerable 
 variety of denominations by statuaries, and 
 others whose attention is more directed to 
 their external character and appearance than 
 their component parts, alabasters are those 
 which have a greater or less degree of imper- 
 fect transparency, a granular texture, are 
 softer, take a duller polish than marble, and 
 are usually of a wdiiter colour. Some stones, 
 however, of a veined and coloured appear- 
 ance, have been considered as alabasters, 
 from their possessing the first mentioned cri- 
 terion ; and some transparent and yellow 
 sparry stones have also received this appella- 
 tion. 
 
 Chemists are at present agreed in applying 
 this name only to such opaque, consistent, 
 and semi-transparent stones, as are composed 
 of lime united with the sulphuric acid. But 
 the term is much more frequent among ma- 
 sons and statuaries than chemists. Chemists 
 in general confound the alabasters among 
 the selenites, gypsums, or plaster of Paris, 
 more especially when they allude only to 
 the component parts, without having occa- 
 sion to consider the external appearance, in 
 which only these several compounds differ 
 from each other. 
 
 As the semi-opaque appearance and gra- 
 nular texture arise merely from a disturbed 
 or successive crystallization, which would 
 else have formed transparent spars, it is ac- 
 cordingly found, that the calcareous stalac- 
 tites, or drop-stones, formed by the transi- 
 tion of water through the roots of cavenis 
 in a calcareous soil, do not differ in appear- 
 ance from the alabaster, most of which is 
 also formed in this manner. But the calca- 
 reous stalactites here spoken of consist of 
 calcareous earth and carbonic acid ; while 
 the alabaster of the chemists is formed of the 
 same earth and sulphuric acid, as has already 
 been remarked. 
 
 * Albin. A mineral discovered at Mo- 
 naberg, near Aussig, in Bohemia ; and be- 
 ing of an opaque white colour, has been 
 called, by Werner, albin. Aggregated crys- 
 
 0.00121514 
 
ALB 
 
 ALB 
 
 talline laminae constitute massive albin. Small 
 crystals of it in right prisms, whose summits 
 consist of four quadrangular planes, are found 
 sprinkled over mammelated masses in cavi- 
 ties.* See Zeolite. 
 
 Album Gr^ecum. Innumerable are the 
 instances of fanciful speculation and absurd 
 credulity in the invention and application of 
 subjects in the more ancient materia medica. 
 The white and solid excrement of dogs, 
 which subsist chiefly on bones, has been re- 
 ceived as a remedy in the medical art, under 
 the name of Album Graecum. It consists, 
 for the most part, of the earth of bones or 
 lime, in combination with phosphoric acid. 
 
 Albumen. This substance, which derives 
 its name from the Latin for the white of an 
 egg, in which it exists abundantly, and in its 
 purest natural state, is one of the chief con- 
 stituent principles of all the animal solids. 
 Beside the white of egg, it abounds in the 
 serum of blood, the vitreous and crystalline 
 humours of the eye, and the fluid of dropsy. 
 Fourcroy claims to himself the honour of 
 having discovered it in the green feculae of 
 plants in general, particularly in those of the 
 cruciform order, in very young ones, and in 
 the fresh shoots of trees, though Rouelle ap- 
 pears to have detected it there long before. 
 Vauquelin says it exists also in the mineral 
 water of Plombieres. 
 
 Mr Seguin has found it in remarkable 
 quantity in such vegetables as ferment with- 
 out yeast, and afford a vinous liquor ; and 
 from a series of experiments he infers, that 
 albumen is the true principle of fermenta- 
 tion, and that its action is more powerful 
 in proportion to its solubility, three different 
 degrees of which he found it to possess. 
 
 The chief characteristic of albumen is its 
 coagulability by the action of heat. If the 
 white of an egg be exposed to a heat of 
 about 184° F. white fibres begin to appear 
 in it, and at 1 60° it coagulates into a solid 
 mass. In a heat not exceeding 212° it dries, 
 shrinks, and assumes the appearance of horn. 
 It is soluble in cold water before it has been 
 coagulated, but not after ; and when diluted 
 with a very large portion it does not coagu- 
 late easily. Pure alkalis dissolve it, even 
 after coagulation. It is precipitated by mu- 
 riate of mercury, nitro-muriate of tin, ace- 
 tate of lead, nitrate of silver, muriate of 
 gold, infusion of galls, and tannin. The 
 acids and metallic oxides coagulate albumen. 
 On the addition of concentrated sulphuric 
 acid, it becomes black, aud exhales a nause- 
 ous smell. Strong muriatic acid gives a 
 violet tinge to the coagulum, and at length 
 becomes saturated with ammonia. Nitric 
 acid, at 70° F. disengages from it abundance 
 of azotic gas ; and if the heat be increased 
 prussic acid is formed, after which carbonic 
 acid and carburetted hydrogen are evolved, 
 aud the residue consists of water containing 
 
 a little oxalic acid, and covered with a lemon 
 coloured fat oil. If dry potash or soda be 
 triturated with albumen, either liquid or so- 
 lid, ammoniacal gas is evolved, and tlie cal- 
 cination of the residuum yields an alkaline 
 prussiate. 
 
 On exposure to the atmosphere in a moist 
 state, albumen passes at once to the state of 
 putrefaction. 
 
 * Solid albumen may be obtained by agitat- 
 ing white of egg with ten or twelve times its 
 weight of alcohol. This seizes the water 
 which held the albumen in solution ; and 
 this substance is precipitated under the form 
 of white flocks or filaments, which cohesive 
 attraction renders insoluble, and which con- 
 sequently may be freely washed with water. 
 Albumen thus obtained is like fibrine, solid, 
 white, insipid, inodorous, denser than w r ater, 
 and without action on vegetable colours. It 
 dissolves in potash and soda more easily than 
 fibrine ; but in acetic acid and ammonia 
 with more difficulty. When these two ani- 
 mal principles are separately dissolved in 
 potash, muriatic acid added to the albumin- 
 ous does not disturb the solution, but it pro- 
 duces a cloud in the other. 
 
 Fourcroy and several other chemists have 
 ascribed the characteristic coagulation of al- 
 bumen bv heat to its oxygenation. But co- 
 hesive attraction is the real cause of the phe- 
 nomenon. In proportion as the tempera- 
 ture rises, the particles of w'ater and albu- 
 men recede from each other, their affinity 
 diminishes, and then the albumen precipi- 
 tates. However, by uniting albumen with a 
 large quantity of water, we diminish its co- 
 agulating property to such a degree, that 
 heat renders the solution merely opalescent. 
 A new'-laid egg yields a soft coagulum by 
 boiling ; but when, by keeping, a portion of 
 the water has transuded so as to leave a void 
 space within the shell, the concentrated al- 
 bumen affords a firm coagulum. An analo- 
 gous phenomenon is exhibited by acetate of 
 alumina, a solution of which, being heated, 
 gives a precipitate in flakes, which redissolve 
 as the caloric which separated the particles of 
 acid and base escapes, or as the temperature 
 
 falls. A solution containing tV of dry al- 
 bumen forms by heat a solid coagulum ; but 
 when it contains only yy, it gives a glairy 
 liquid. One thousandth part, however, on 
 applying heat, occasions opalescence. Putrid 
 white of egg, and the pus of ulcers, have a 
 similar smell. According to Dr Bostock, 
 a drop of a saturated solution of corrosive 
 
 sublimate let fall into w r ater containing ^ IhTo 
 of albumen, occasions a milkiness and curdy 
 precipitate. On adding a slight excess of 
 the mercurial solution to the albuminous 
 liquid, and applying heat, the precipitate 
 which falls, being dried, contains in every 7 
 parts 5 of albumen. Ilence that salt is the 
 most delicate test of this animal product. 
 
ALC 
 
 ALC 
 
 The yellow pitchy precipitate occasioned by 
 tannin, is brittle when dried, and not liable 
 to putrefaction. But tannin, or infusion of 
 galls, is a much nicer test of gelatin than of 
 albumen. 
 
 The cohesive attraction of coagulated 
 albumen makes it resist putrefaction. In 
 this state it may be kept for weeks under 
 water without suffering change. By long 
 digestion in weak nitric acid, albumen seems 
 convertible into gelatine. By the analysis 
 of Gay Lussac and Thenard, 100 parts of 
 albumen are formed of 52.883 carbon, 
 23.872 oxygen, 7.540 hydrogen, 15.705 
 nitrogen, or, in other terms, of 52.883 cai- 
 bon, 27.127 oxygen and hydrogen, in the 
 proportions for constituting water, 15.705 
 nitrogen, and 4.285 hydrogen in excess. 
 The negative pole of a voltaic pile in high 
 activity coagulates albumen ; but if the pile 
 be feeble, coagulation goes on only at the 
 positive surface. Albumen, in such a state 
 of concentration as it exists in serum of 
 blood, can dissolve some metallic oxides, 
 particularly the protoxide of iron. Orfila 
 has found white of egg to be the best anti- 
 dote to the poisoning effects of corrosive sub- 
 limate on the human stomach. As albumen 
 occasions precipitates with the solutions of 
 almost every metallic salt, probably it may 
 act beneficially against other species of mi- 
 neral poison.* 
 
 From its coagulability albumen is of great 
 use in clarifying liquids. See Clarification. 
 
 It is likewise remarkable for the property 
 of rendering leather supple, for which pur- 
 pose a solution of whites of eggs in water 
 is used by leather-dressers ; and hence Dr 
 Lobb of Yeovil in Somersetshire was induc- 
 ed to employ this solution in cases of con- 
 traction and rigidity of the tendons, and de- 
 rived from it apparent success. 
 
 Whites of eggs beaten in a basin with a 
 lump of alum, till they coagulate, form the 
 alum curd of Riverius, or alum cataplasm 
 of the London Pharmacopoeia, used to re- 
 move inflammations of the eyes. 
 
 * Alburnum. The interior white bark 
 of trees.* 
 
 * Alcarrazas. A species of porous pot- 
 tery made in Spain, for the purpose of cool- 
 ing water by its transudation and copious 
 evaporation from the sides of the vessel. M. 
 Darcet gives the following as the analysis of 
 the clay which is employed for the purpose : 
 GO calcareous earth, mixed with alumina 
 and a little peroxide of iron, and 56 of sili- 
 ceous earth, mixed with a little alumina. In 
 working up the earths with water, a quantity 
 of salt is added, and dried in it. The pieces 
 are only half baked.* 
 
 * Alchemy. A title of dignity, given in 
 the dark ages, by the adepts, to the mystical 
 art by which they professed to find the phi- 
 losopher’s stone, that was to transmute base 
 
 metals into gold, and prepare the elixir of 
 life. Though avarice, fraud, and folly were 
 their motives, yet their experimental re- 
 searches were instrumental in promoting the 
 progress of chemical discovery. Hence, in 
 particular, metallic pharmacy derived its 
 origin.* 
 
 Alcohol. This term is applied in strict- 
 ness only to the pure spirit obtainable by 
 distillation and subsequent rectification from 
 all liquids that have undergone vinous fer- 
 mentation, and from none but such as are 
 susceptible of it. But it is commonly used 
 to signify this spirit more or less imperfectly 
 freed from water, in the state in which it is 
 usually met with in the shops, and in which, 
 as it was first obtained from the juice of the 
 grape, it was long distinguished by the name 
 of spirit of wine. At present it is extracted 
 chiefly from grain or melasses in Europe, 
 and from the juice of the sugar-cane in the 
 West Indies ; and in the diluted state in 
 which it commonly occurs in trade, consti- 
 tutes the basis of the several spirituous liquors 
 called brandy, rum, gin, whisky, and cordials, 
 however variously denominated or disguised. 
 
 As we are not able to compound alcohol 
 immediately from its ultimate constituents, 
 w T e have recourse to the process of fermenta- 
 tion, by which its principles are first extri- 
 cated from the substances in which they were 
 combined, and then united into a new com- 
 pound ; to distillation, by which this new 
 compound, the alcohol, is separated in a state 
 of dilution with water, and contaminated with 
 essential oil ; and to rectification, by which 
 it is ultimately freed from these. 
 
 It appears to be essential to the fermenta- 
 tion of alcohol, that the fermenting fluid 
 should contain saccharine matter, which is 
 indispensable to that species of fermentation 
 called vinous. In France, where a great 
 deal of wine is made, particularly at the 
 commencement of the vintage, that is too 
 weak to be a saleable commodity, it is a 
 common practice to subject this wine to dis- 
 tillation, in order to draw off the spirit ; and 
 as the essential oil that rises in this process 
 is of a more pleasant flavour than that of 
 malt or melasses, the French brandies are 
 preferred to any other ; though even in the 
 flavour of these there is a difference, accord- 
 ing to the wine from which they arc produc- 
 ed. Tn the West Indies a spirit is obtained 
 from the juice of the sugar-cane, which is 
 highly impregnated with its essential oil, 
 and well known by the name of rum. The 
 distillers in this country use grain, or melas- 
 ses, whence they distinguish the products by 
 the name of malt spirits, and melasses spirits . 
 It is said that a very good spirit may be ex- 
 tracted from the husks of gooseberries or 
 currants, after wine has been made from 
 them. 
 
 As the process of malting developes tb« 
 
ALC 
 
 ALC 
 
 saccharine principle of grain, it would ap- 
 pear to render it fitter for the purpose; 
 though it is the common practice to use 
 about three parts of raw grain with one of 
 malt. For this two reasons may be assign- 
 ed : by using raw grain the expense of malt- 
 ing is saved, as well as the duty on malt; 
 and the process of malting requires some 
 nicety of attention, since, if it be carried too 
 far, part of the saccharine matter is lost, and 
 if it be stopped too soon, this matter will not 
 be wholly developed. Besides, if the malt 
 be dried too quickly, or by an unequal heat, 
 the spirit it yields will be less in quantity, 
 and more unpleasant in flavour. Another 
 object of economical consideration is, what 
 grain will afford the most spirit in propor- 
 tion to its price, as well as the best in quali- 
 ty. Barley appears to produce less spirit 
 than wheat ; and if three parts of raw wheat 
 be mixed with one of malted barley, the pro- 
 duce is said to be particularly fine. This is the 
 practice of the distillers in Holland for pro- 
 ducing a spirit of the finest quality ; but in 
 England they are expressly prohibited from 
 using more than one part of wheat to two of 
 other grain. Rye, however, affords still 
 more spirit than wheat. 
 
 * The practice with the distillers in Scot- 
 land is to use one part of malted with from 
 four to nine parts of unmalted grain. This 
 mixture yields an equal quantity of spirit, 
 and at a much cheaper rate than when the 
 former proportions are taken.* 
 
 Whatever be the grain employed, it may 
 be coarsely ground, and then mixed care- 
 fully with a little cold water, to prevent its 
 running into lumps ; water about 90° F. 
 may then be added, till it is sufficiently di- 
 luted ; and, lastly, a sufficient quantity of 
 yeast. The whole is then to be allowed to 
 ferment in a covered vessel, to which, how- 
 ever, the air can have access. Attention 
 must be paid to the temperature; for if it 
 exceed 77° F. the fermentation will be too 
 rapid ; if it be below GO 5 , the fermentation 
 will cease. The mean between these will 
 generally be found most favourable. In this 
 country it is the more common practice to 
 mash the grain as for brewing malt liquors, 
 and boil the wort. But in whichever way 
 it be prepared, or if the wash, so the liquor 
 intended for distillation is called, be made 
 from melasses and water, due attention must 
 be paid to the fermentation, that it be con- 
 tinued till the liquor grows fine, and pungent 
 to the taste, which will generally be about 
 the third day, but, not so long as to permit 
 the acetous fermentation to commence. 
 
 In this state the wash is to be committed 
 to the still, of which, including the head, 
 it should occupy at least three-fourths ; and 
 distilled with a gentle heat, as long as any 
 spirit comes over, which will be till about 
 half the wash is consumed. The more 
 
 slowly the distillation is conducted, the les» 
 will the product be contaminated with essen- 
 tial oil, and the less danger will there be of 
 empyreuma. A great saving of time and 
 fuel, however, may be obtained by making 
 the still very broad and shallow, and con- 
 triving a free exit for the steam.- This has 
 been carried to such a pitch in Scotland, that 
 a still measuring 43 gallons, and containing 
 1G gallons of wash, has been charged and 
 worked no less than four hundred and eighty 
 times in the space of twenty-four hours. 
 This would be incredible, were it not esta- 
 blished by unquestionable evidence. See 
 Laboratory, article Still. 
 
 * The above wonderful rapidity of distil- 
 lation has now ceased, since the excise duties- 
 have been levied on the quantity of spirit 
 produced, and not, as formerly, by the size 
 of the still. Hence, too, the spirit is pro- 
 bably improved in flavour.* 
 
 The first product, technically termed low 
 wine , is again to be subjected to distillation, 
 the latter portions of what comes over, called 
 Joints, being set apart to put into the wash 
 still at some future operation. Thus a large 
 portion of the watery part is left behind. 
 This second product, termed raw spirit, be- 
 ing distilled again, is called rectified spirit* 
 It is calculated, that a hundred gallons of 
 malt or corn wash will not produce above 
 twenty of spirit, containing 60 parts of alco- 
 hol to 50 of water ; the same of cyder wash, 
 15 gallons; and of melasses wash, 22 gal- 
 lons. The most spirituous wines of France, 
 those of Languedoc, Guienne, and Rousil- 
 lon, yield, according to Chaptal, from 20 to 
 25 gallons of excellent brandy from 100; 
 but those of Burgundy and Champagne 
 much less. Brisk wines, containing much 
 carbonic acid, from the fermentation having 
 been stopped at an early period, yield the 
 least spirit. 
 
 The spirit thus obtained ought to be co- 
 lourless, and free from any disagreeable 
 flavour ; and in this state it is fittest for 
 pharmaceutical purposes, or the extraction of 
 tinctures. But for ordinary sale something 
 more is required. The brandy of France, 
 which is most in esteem here, though per- 
 fectly colourless when first made, and often 
 preserved so for use in that country, by be- 
 ing kept in glass or stone bottles, is put into 
 new or*, casks for exportation, whence it 
 soon acquires an amber colour, a peculiar 
 flavour, and something like an unctuosity of 
 consistence. As it is not only prized for 
 these qualities, but they are commonly deem- 
 ed essential to it, the English distiller imi- 
 tates by design these accidental qualities. 
 The most obvious and natural method of 
 doing this would be by impregnating a pure 
 spirit with the extractive, resinous, and co- 
 louring matter of oak shavings; but other 
 modes have been contrived. The dulcified 
 I 
 
ALC 
 
 ALC 
 
 spirit of nitre, as it is called, is commonly 
 used to give the flavour ; and catechu, or 
 burnt sugar, to impart the desired colour. 
 A French writer has recommended three 
 ounces and a half of finely powdered char- 
 coal, and four ounces and a half of ground 
 rice, to be digested for a fortnight in a quart 
 of malt spirit. 
 
 The finest gin is said to be made in Hol- 
 land, from a spirit drawn from wheat mixed 
 with a third or fourth part of malted barley, 
 and twice rectified over juniper berries ; but 
 in general, rye meal is used instead of wheat. 
 They pay so much regard to the water em- 
 ployed, that many send vessels to fetch it on 
 purpose from the Meuse ; but all use the 
 softest and clearest river water they can get. 
 In England it is the common practice to add 
 oil of turpentine, in the proportion of two 
 ounces to ten gallons of raw spirit, with 
 three handfuls of bay salt, and draw off till 
 the faints begin to rise. 
 
 But corn or melasses spirit is flavoured 
 likewise by a variety of aromatics, with or 
 without sugar, to please different palates ; 
 all of which are included under the general 
 technical term of compounds or cordials . 
 
 Other articles have been employed, though 
 rot generally, for the fabrication of spirit, as 
 carrots and potatoes ; and we are lately in- 
 formed by Professor Proust, that from the 
 fruit of the carob tree he has obtained good 
 brandy in the proportion of a pint from five 
 pounds of the dried fruit. 
 
 To obtain pure alcohol, different processes 
 have been recommended ; but the purest rec- 
 tified spirit obtained as above described, being 
 that which is least contaminated with foreign 
 matter, should be employed. Bouelle re- 
 commends to draw off half the spirit in a 
 water bath ; to rectify this twice more, draw- 
 ing off' two-thirds each time ; to add water 
 to this alcohol, which will turn it milky by 
 separating the essential oil remaining in it ; 
 to distil the spirit from this water ; and fin- 
 ally rectify it by one more distillation. 
 
 Baume sets apart the first running, when 
 about a fourth is come over, and continues 
 the distillation till he has drawn off' about 
 as much more, or till the liquor runs oft' 
 milky. The last running he puts into the 
 still again, and mixes the first half of what 
 comes over with the preceding first product. 
 This process is again repeated, and nil the 
 first products being mixed together, are dis- 
 tilled afresh. When about half the liquor is 
 come over, this is to be set apart as pure al- 
 cohol. 
 
 Alcohol in this state, however, is not so 
 pure as when, to use the language of the old 
 chemists, it has been dephlegmated , or still 
 further freed from water, by means of some 
 alkaline salt. Boerhaave recommended, for 
 this purpose, the muriate of soda, deprived 
 of its water of crystallization by heat, and 
 
 added hot to the spirit. But the subcar- 
 bonate of potash is preferable. About a 
 third of the weight of the alcohol should be 
 added to it in a glass vessel, well shaken, 
 and then suffered to subside. The salt will 
 be moistened by the water absorbed from 
 the alcohol ; which being decanted, more of 
 the salt is to be added, and this is to be con- 
 tinued till the salt falls dry to the bottom of 
 the vessel. The alcohol in this state will be 
 reddened by a portion of the pure potash, 
 which it will hold in solution, from which it 
 must be freed by distillation in a w r ater bath. 
 Dry muriate of lime may be substituted ad- 
 vantageously for the alkali. 
 
 As alcohol is much lighter than u'ater, its 
 specific gravity is adopted as the test of its 
 purity. Fourcroy considers it as rectified 
 to the highest point w r hen its specific gravity 
 is 829, that of water being 1000 ; and per- 
 haps this is nearly as far as it can be carried 
 by the process of Rouelle or Baume simply. 
 Mr Bories found the first measure that came 
 over from twenty of spirit at 856 to be 820, 
 at the temperature of 71° F. Sir Charles 
 Blagden, by the addition of alkali, brought 
 it to SI 3, at 60° F. Chaussier professes to 
 have reduced it to 798 ; but he gives 998.35 
 as the specific gravity of water. Lowitz as- 
 serts, that he has obtained it at 79 J, by add- 
 ing as much alkali as nearly to absorb the 
 spirit ; but the temperature is not indicated. 
 In the shops it is about 855 or 840 ; accord- 
 ing to the London College it should be 815. 
 
 It is by no means an easy undertaking to 
 determine the strength or relative value of 
 spirits, even w r ith sufficient accuracy for 
 commercial purposes. The following re- 
 quisites must be obtained before this can be 
 well done : the specific gravity of a certain 
 number of mixtures of alcohol and water 
 must be taken so near each other, as that 
 the intermediate specific gravities may not 
 perceptibly differ from those deduced from 
 the supposition of a mere mixture of the 
 fluids ; the expansions or variations of spe- 
 cific gravity in these mixtures must be de- 
 termined at different temperatures ; some 
 easy method must be contrived of deter- 
 mining the presence and quantity of sac- 
 charine or oleaginous matter which the spi- 
 rit may hold in solution, and the effect of 
 such solution on the specific gravity ; and 
 lastly, the specific gravity of the fluid must 
 be ascertained by a proper floating instru- 
 ment with a graduated stem, or set of 
 weights ; or, which may be more conveni- 
 ent, with both. 
 
 The strength of brandies in commerce is 
 judged by the phial, or by burning. The 
 phial proof consists in agitating the spirit in 
 a bottle, and observing the form and mag- 
 nitude of the bubbles that collect round the 
 edge of the liquor, technically termed the 
 bead, which are larger the stronger the spi- 
 
A IX 
 
 ALC 
 
 rit. These probably depend on the solution 
 of resinous matter from the cask, which is 
 taken up in greater quantities, the stronger 
 the spirit. It is not difficult, however, to 
 produce this appearance by various simple 
 additions to weak spirit. The proof by burn- 
 ing is also fallacious ; because the magnitude 
 of the flame, and quantity of residue, in the 
 same spirit, vary greatly with the form of 
 the vessel it is burned in. If the vessel be 
 kept cool, or suffered to become hot, if it be 
 deeper or shallower, the results will not be 
 the same in each case. It does not follow, 
 however, but that manufacturers and others 
 may in many instances receive considerable 
 information from these signs, in circumstan- 
 ces exactly alike, and in the course of opera- 
 tions wherein it would be inconvenient to 
 recur continually to experiments of specific- 
 gravity. 
 
 The importance of this object, as well for 
 the purposes of revenue as of commerce, in- 
 duced the British government to employ Dr 
 Blagden, now Sir Charles, to institute a very 
 minute and accurate series of experiments. 
 These may be considered as fundamental re- 
 sults ; for which reason, I shall give a sum- 
 mary of them in this place, from the Philo- 
 sophical Transactions for 1790. 
 
 The first object to which the experiments 
 were directed was to ascertain the quantity 
 and law resulting from the mutual penetra- 
 tion of water and spirit. 
 
 All bodies in general expand by heat ; but 
 the quantity of this expansion, as well as the 
 law of its progression, is probably not the 
 same in any two substances. In water and 
 spirit they are remarkably different. The 
 whole expansion of pure spirit from 30° to 
 300° of Fahrenheit’s thermometer is not less 
 than 1 -2.5th of its whole bulk at 30° ; where- 
 as that of water, in the same interval, is only 
 1-1 45th of its bulk. The laws of their ex- 
 pansion are still more different than the quan- 
 tities. If the expansion of quicksilver be, as 
 usual, taken for the standard, (our thermo- 
 meters being constructed with that fluid), 
 the expansion of spirit is, indeed, progres- 
 sively increasing with respect to that standard, 
 but not much so within the above-mention- 
 ed interval ; while water kept from freezing 
 to 30°, which may easily be done, will abso- 
 lutely contract as it is heated for ten or more 
 degrees, that is, to 40° or 42° of the ther- 
 mometer, and will then begin to expand as 
 its heat is augmented, at first slowly, and 
 afterward gradually more rapidly, so as to 
 observe upon the whole a very increasing 
 progression. Now, mixtures of these two 
 substances will, as may be supposed, approach 
 to the less or the greater of these progres- 
 sions, according as they are compounded of 
 more spirit or more water, while their total 
 expansion will be greater, according as more 
 spirit enters into their composition ; but the 
 
 exact quantity of the expansion, as well as 
 law of the progression, in all of them, can 
 be determined only by trials. These w ere, 
 therefore, the tw o other principal objects to 
 be ascertained by experiment. 
 
 The person engaged to make these expe- 
 riments was Dr Dollfuss, an ingenious Swiss 
 gentleman then in London, who had distin- 
 guished himself by several publications on 
 chemical subjects. As he could not conve- 
 niently get the quantity of spirit he wanted 
 lighter than 825, at 60° F., he fixed upon 
 this strength as the standard for alcohol. 
 
 These experiments of Dr Dollfuss w^ere 
 repeated by Mr Gilpin, clerk of the Royal 
 Society ; and as the deductions in this ac- 
 count will be taken chiefly from that last set 
 of experiments, it is proper here to describe 
 minutely the method observed by Mr Gilpin 
 in his operation. This naturally resolves it- 
 self into two parts : the way of making the 
 mixtures, and the way of ascertaining their 
 specific gravity. 
 
 1. The mixtures were made by weight, as 
 the only accurate method of fixing the pro- 
 portions. In fluids of such very unequal ex- 
 pansions by beat as water and alcohol, if 
 measures had been employed, increasing or 
 decreasing in regular proportions to each 
 other, the proportions of the masses w r ould 
 have been sensibly irregular : now the latter 
 was the object in view, namely, to deter- 
 mine the real quantity of spirit in any given 
 mixture, abstracting the consideration of its 
 temperature. Besides, if the proportions had 
 been taken by measure, a different mixture 
 should have been made at every different degree 
 of heat. But the principal consideration was, 
 that with a very nice balance, such as was 
 employed on this occasion, quantities can be 
 determined to much greater exactness by 
 weight than by any practicable way of mea- 
 surement. The proportions were therefore 
 always taken by weight. A phial being pro- 
 vided of such a size as that it should he 
 nearly full with the mixture, was made per- 
 fectly clean and dry, and being counterpois- 
 ed, as much of the pure spirit as appeared 
 necessary was poured into it. The w r eight 
 of this spirit was then ascertained, and the 
 weight of distilled water required to make a 
 mixture of the intended proportions was cal- 
 culated. This quantity of water was then 
 added, with all the necessary care, the last 
 portions being put in by means of a w r ell- 
 known instrument, which is composed of a 
 small dish terminating in a tube drawn to a 
 fine point: the top of the dish being covered 
 with the thumb, the liquor in it is prevented 
 from running out through the tube by the 
 pressure of the atmosphere, but instantly 
 begins to issue by drops, or a very small 
 stream, upon raising the thumb. Water be- 
 ing thus introduced into the phial, till it ex- 
 actly counterpoised the weight, which having 
 
ALC 
 
 ALC 
 
 been previously computed, was put into the 
 opposite scale, the phial was shaken, and 
 then well stopped with its glass stopple, 
 over which leather was tied very tight, to pre- 
 vent evaporation. No mixture was used till 
 it had remained in the phial at least a month, 
 for the full penetration to have taken place ; 
 and it was always well shaken before it 
 was poured out to have its specific gravity 
 tried. 
 
 2. There are two common methods of 
 taking the specific gravity of fluids; one, by 
 finding the weight which a solid body loses 
 by being immersed in them ; the other, by 
 filling a convenient vessel with them, and as- 
 certaining the increase of weight it acquires. 
 In both cases a standard must have been 
 previously taken, which is usually distilled 
 water ; namely, in the first method, by find- 
 ing the weight lost by the solid body in the 
 water; and in the second method, the weight 
 of the vessel filled with water. The latter 
 was preferred, for the following reasons: — 
 
 When a ball of glass, which is the proper- 
 cst kind of solid body, is weighed in any 
 spirituous or watery fluid, the adhesion of 
 the fluid occasions some inaccuracy, and 
 renders the balance comparatively sluggish. 
 To what degree this effect proceeds is un- 
 certain ; but from some experiments made 
 by Mr Gilpin with that view, it appears to 
 be very sensible. Moreover, in this method 
 a large surface must be exposed to the air 
 during the operation of weighing, which, 
 especially in the higher temperatures, would 
 give occasion to such an evaporation as to 
 alter essentially the strength of the mixture. 
 It seemed also as if the temperature of the 
 fluid under trial could be determined more 
 exactly in the method of filling a vessel, than 
 in the other : for the fluid cannot well be 
 stirred while the ball to be weighed remains 
 immersed in it; and as some time must ne- 
 cessarily be spent in the weighing, the change 
 of heat which takes place during that period 
 will be unequal through the mass, and may 
 occasion a sensible error. It is true, on the 
 other hand, that in the method of filling a 
 vessel, the temperature could not be ascer- 
 tained with the utmost precision, because 
 the neck of the vessel employed, containing 
 about ten grains, was filled up to the mark 
 with spirit not exactly of the same tempe- 
 rature, as will be explained presently : but 
 this error, it is supposed, would by no means 
 equal the other, and the utmost quantity of 
 it may be estimated very nearly. Finally, 
 it was much easier to bring the fluid to any 
 given temperature when it was in a vessel to 
 be weighed, than when it was to have a solid 
 body weighed in it ; because in the former 
 case the quantity was smaller, and the vessel 
 containing it more manageable, being readily 
 heated with the hand or warm water, and 
 cooled with cold water : and the very circum- 
 
 stance, that so much of the fluid was not 
 required, proved a material convenience. 
 The particular disadvantage in the method 
 of weighing in a vessel, is the difficulty of 
 filling it with extreme accuracy ; but when 
 the vessel is judiciously and neatly marked, 
 the error of filling will, with due care, be 
 exceedingly minute, By several repetitions 
 of the same experiments, Mr Gilpin seemed 
 to bring it within the 1- ,15000th part of the 
 whole weight. 
 
 The above-mentioned considerations in- 
 duced Dr Blagden, as well as the gentlemen 
 employed in the experiments, to give the 
 preference to weighing the fluid itself ; and 
 that was accordingly the method practised 
 both by Dr Dollfuss and Mr Gilpin in their 
 operations. 
 
 The vessel chosen as most convenient for 
 the purpose was a hollow glass ball, termi- 
 nating in a neck of small bore. That which 
 Dr Dollfuss used held 5800 grains of distill- 
 ed water ; but as the balance was so extreme- 
 ly accurate, it was thought expedient, upon 
 Mr Gilpin’s repetition of the experiments, to 
 use one of only 2965 grains capacity, as ad- 
 mitting the heat of any fluid contained in it 
 to be more nicely determined. The ball of 
 this vessel, which may be called the weigh- 
 ing bottle, measured about 2.8 inches in 
 diameter, and was spherical, except a slight 
 flattening on the part opposite to the neck, 
 which served as a bottom for it to stand up- 
 on. Its neck was formed of a portion of a 
 barometer tube, .25 of an inch in bore, and 
 about 1^ inch long; it was perfectly cylin- 
 drical, and, on its outside, very near the 
 middle of its length, a fine circle or ring 
 was cut round it with a diamond, as the 
 mark to which it was to be filled with the 
 liquor. This mark was made by fixing the 
 bottle in a lathe, and turning it round with 
 great care, in contact with the diamond. 
 The glass of this bottle was not very thick j 
 it weighed 916 grains, and with its silver 
 cap 936. 
 
 When the specific gravity of any liquor 
 was to be taken by means of this bottle, the 
 liquor w r as first brought nearly to the re- 
 quired temperature, and the bottle was filled 
 with it up to the beginning of the neck only, 
 that there might he room for shaking it. A 
 very fine and sensible thermometer was then 
 passed through the neck of the bottle into 
 the contained liquor, which showed whether 
 it was above or below the intended tempera- 
 ture. In the former case the bottle was 
 brought into colder air, or even plunged for 
 a moment into cold water ; the thermometer 
 in the mean time being frequently put into 
 the contained liquor, till it was found to sink 
 to the right point. In like manner, when 
 the liquor was too cold, the bottle was 
 brought into warmer air, immersed in warm 
 water, or more commonly held between the 
 
ALC 
 
 ALC 
 
 hands, till upon repeated trials with the ther- 
 mometer the just temperature was found. It 
 will be understood, that during the course 
 of this heating or cooling, the bottle was 
 very frequently shaken between each immer- 
 sion of the thermometer ; and the top of the 
 neck was kept covered, either with the fin- 
 ger, or a silver cap made on purpose, as con- 
 stantly as possible. Hot water was used to 
 raise the temperature only in heats of 80° 
 and upwards, inferior heats being obtained 
 by applying the hands to the bottle : when 
 the hot water was employed, the ball of the 
 bottle was plunged into it, and again quickly 
 lifted out, with the necessary shaking inter- 
 posed, as often as was necessary for commu- 
 nicating the required heat to the liquor ; but 
 care was taken to wipe the bottle dry after 
 each immersion, before it was shaken, lest 
 any adhering moisture might by accident get 
 into it. The liquor having by these means 
 been brought to the desired temperature ; 
 the next operation was to fill up the bottle 
 exactly to the mark upon the neck, which 
 was done with some of the same liquor, by 
 means of a glass funnel with a very small 
 bore. Mr Gilpin endeavoured to get that 
 portion of the liquor which was employed 
 for this purpose, pretty nearly to the tempe- 
 rature of the liquor contained in the bottle ; 
 but as the whole quantity to be added never 
 exceeded ten grains, a difference of ten de- 
 grees in the heat of that small quantity, which 
 is more than it ever amounted to, would 
 have occasioned an error of only 1 -50th of a 
 degree in the temperature of the mass. 
 Enough of the liquor was put in to fill the 
 neck rather above the mark, and the super- 
 fluous quantity was then absorbed to great 
 nicety, by bringing into contact with it the 
 fine point of a small roll of blotting paper. 
 A6 the surface of the liquor in the neck 
 would be always concave, the bottom or 
 centre of this concavity was the part made to 
 coincide with the mark round the glass ; and 
 in viewing it care was taken, that the near 
 and opposite sides of the mark should appear 
 exactly in the same line, by which means nil 
 parallax was avoided. A silver cap, which 
 fitted tight, was then put upon the neck, to 
 prevent evaporation ; and the whole appara- 
 tus was in that state laid in the scale of the 
 balance, to be weighed with all the exactness 
 possible. 
 
 The spirit employed by Mr Gilpin was 
 furnished tohim by Dr Dollfuss, under whose 
 inspection it had been rectified from ruin 
 
 supplied by government. Its specific gra- 
 vity, at CO degrees of heat, was .82514. It 
 was first weighed pure, in the above-men- 
 tioned bottle, at every five degrees of heat, 
 from 30 to 100 inclusively. Then mixtures 
 were formed of it, and distilled water, in 
 every proportion, from l-20th of the water 
 to equal parts of water and spirit ; the quan- 
 tity of water added being successively aug- 
 mented, in the proportion of five grains to 
 one hundred of the spirit; and these mix- 
 tures were also weighed in the bottle, like 
 the pure spirit, at every five degrees of heat. 
 The numbers hence resulting are delivered 
 in the following table ; where the first co- 
 lumn shows the degrees of heat ; the second 
 gives the weight of the pure spirit contained 
 in the bottle at those different degrees ; the 
 third gives the weight of a mixture in the 
 proportions of 100 parts by weight of that 
 spirit to 5 of water, and so on successively 
 till the water is to the spirit as 100 to 5. 
 They are the mean of three several experi- 
 ments at least, as Mr Gilpin always filled 
 and weighed the bottle over again that num- 
 ber of times, if not oftencr. The heat was 
 taken at the even degree, as shown by the 
 thermometer, without any allowance in the 
 first instance, because the coincidence of the 
 mercury with a division can be perceived 
 more accurately than any fraction can be es- 
 timated ; and the errors of the thermometers, 
 if any, it was supposed would be less upon 
 the grand divisions of 5 degrees than in any 
 others. It must be observed, that Mr Gil- 
 pin used the same mixture throughout all 
 the different temperatures, heating it up 
 from 50° to 100°; hence some small error 
 in its strength may have been occasioned in 
 the higher degrees, by more spirit evaporat- 
 ing than water : but this, it is believed, must 
 have been trifling, and greater inconvenience 
 would probably have resulted from interpos- 
 ing a fresh mixture. 
 
 The precise specific gravity of the pure 
 spirit employed was .82514 ; but to avoid 
 an inconvenient fraction, it is taken, in con- 
 structing the table of specific gravities, as 
 .825 only, a proportional deduction being 
 made from all the other numbers. Thus the 
 follow ing table gives the true specific gra- 
 vity, at the different degrees of heat, of a 
 pure rectified spirit, the specific gravity of 
 which at 60 ° is .825, together with the spe- 
 cific gravities of different mixtures of it with 
 water, at those different temperatures. 
 
Real Specific Gravities at the different Temperatures. 
 
 Heat. 
 
 The 
 
 pure 
 
 spirit. 
 
 100 
 
 grains of | 
 spirit to i 
 .0 gr. of 
 water . 
 
 100 1 
 grains of! 
 spirit to 
 10 gr. of 
 water. 
 
 100 
 
 grains of 
 spirit to 
 15 gr. of 
 water. 
 
 100 l 
 grains of 
 spirit to 
 ‘iO gr. of 
 water. 
 
 100 
 
 grains of 
 spirit to 
 25 gr. of 
 water. 
 
 100 
 
 grains of 
 spirit to 
 30 gr. of 
 water. 
 
 100 
 
 grainsof 
 spirit to 1 
 35 gr. of j 
 water. 
 
 100 
 
 grains of 
 spirit to 
 4-0 gr. of 
 water. 
 
 100 | 
 grains of 
 spirit to 
 15 gr. of 
 water. 
 
 100 ' 
 grainsof 
 spirit to 
 50 gr. of 
 water. 
 
 SO 0 
 
 *83896 
 
 •84995 
 
 *85957 
 
 *86825 
 
 *87585 
 
 *88282 
 
 •88921 
 
 *89511 
 
 *90054 
 
 •90558 
 
 *91023 
 
 35 
 
 83672 
 
 84769 
 
 85729 
 
 86587 
 
 87357 
 
 88059 
 
 88701 
 
 89294 
 
 89839 
 
 90345 
 
 90811 
 
 40 
 
 83445 
 
 84539 
 
 85507 
 
 86361 
 
 87134 
 
 87838 
 
 88481 
 
 89073 
 
 89617 
 
 90127 
 
 90596 
 
 45 
 
 83214 
 
 84310 
 
 85277 
 
 86131 
 
 86905 
 
 87613 
 
 88255 
 
 88849 
 
 89396 
 
 89909 
 
 90380 
 
 50 
 
 82977 
 
 84076 
 
 85042 
 
 85902 
 
 86676 
 
 87384 
 
 88030 
 
 88626 
 
 89174 
 
 89684 
 
 90160 
 
 55 
 
 82736 
 
 83834 
 
 S4802 
 
 85664 
 
 86441 
 
 87150 
 
 87796 
 
 88393 
 
 88945 
 
 89458 
 
 89933 
 
 60 
 
 82500 
 
 83599 
 
 84568 
 
 85430 
 
 86208 
 
 86918 
 
 87569 
 
 88169 
 
 88720 
 
 89232 
 
 89707 
 
 65 
 
 82262 
 
 83362 
 
 84334 
 
 85193 
 
 85976 
 
 86686 
 
 87337 
 
 87938 
 
 88490 
 
 89006 
 
 89479 
 
 70 
 
 82023 
 
 83124 
 
 84092 
 
 84951 
 
 85736 
 
 86451 
 
 87105 
 
 87705 
 
 88254 
 
 88773 
 
 89252 
 
 75 
 
 81780 
 
 82878 
 
 83851 
 
 84710 
 
 85496 
 
 86212 
 
 86864 
 
 87466 
 
 88018 
 
 88538 
 
 89018 
 
 80 
 
 81530 
 
 82631 
 
 83603 
 
 84467 
 
 85248 
 
 85966 
 
 86622 
 
 8722? 
 
 87776 
 
 88301 
 
 88781 
 
 85 
 
 81291 
 
 82396 
 
 83371 
 
 84243 
 
 85036 
 
 85757 
 
 86411 
 
 87021 
 
 87590 
 
 88120 
 
 88609 
 
 90 
 
 81044 
 
 82150 
 
 83126 
 
 84001 
 
 84797 
 
 85518 
 
 86172 
 
 86787 
 
 87360 
 
 87889 
 
 88376 
 
 95 
 
 80794 
 
 81900 
 
 82877 
 
 83753 
 
 84550 
 
 85272 
 
 85928 
 
 86542 
 
 87114 
 
 87654 
 
 88146 
 
 100 
 
 80548 
 
 81657 
 
 82639 
 
 83513 
 
 84038 
 
 85031 
 
 85688 
 
 86302 
 
 86879 
 
 87421 
 
 87915 
 
 Heat. 
 
 100 
 
 grains of 
 spirit to 
 55 gr. of 
 water. 
 
 100 
 
 grains of 
 spirit to 
 60 gr. of 
 water. 
 
 100 
 
 grainsof 
 spirit to 
 65 gr. of 
 water. 
 
 100 
 
 grainsof 
 spirit to 
 70 gr. of 
 water. 
 
 100 
 
 grainsof 
 spirit to 
 75 gr. of 
 water. 
 
 100 
 
 grainsof 
 spirit to 
 80 gr. of 
 water. 
 
 100 
 
 grainsof 
 spirit to 
 85 gr. of 
 water. 
 
 100 
 
 grainsof 
 spirit to 
 90 gr. of 
 water. 
 
 lOu 
 
 grainsof 
 spirit to 
 95 gr. of 
 water. 
 
 100 
 
 grains of 
 spirit to 
 100 gr. 
 of water. 
 
 30° 
 
 •91449 
 
 •91847 
 
 •92217 
 
 *92563 
 
 •92889 
 
 •93191 
 
 •93474 
 
 •93741 
 
 •93991 
 
 •94222 
 
 35 
 
 91241 
 
 91640 
 
 92009 
 
 92355 
 
 92680 
 
 92986 
 
 93274 
 
 93541 
 
 93790 
 
 94025 
 
 40 
 
 91026 
 
 91428 
 
 91799 
 
 92151 
 
 92476 
 
 92783 
 
 93072 
 
 93341 
 
 93592 
 
 93827 
 
 45 
 
 90812 
 
 9121 1 
 
 91584 
 
 91937 
 
 92264 
 
 92570 
 
 92859 
 
 95131 
 
 93382 
 
 93621 
 
 50 
 
 90596 
 
 90997 
 
 91370 
 
 91723 
 
 92051 
 
 92358 
 
 92647 
 
 92919 
 
 93177 
 
 93419 
 
 55 
 
 90367 
 
 90768 
 
 91144 
 
 91502 
 
 91837 
 
 92145 
 
 92436 
 
 92707 
 
 92965 
 
 93208 
 
 60 
 
 90144 
 
 90549 
 
 90927 
 
 93 287 
 
 91622 
 
 91933 
 
 92225 
 
 92499 
 
 92758 
 
 93002 
 
 65 
 
 89920 
 
 90328 
 
 90707 
 
 91066 
 
 91400 
 
 91715 
 
 92010 
 
 92283 
 
 92546 
 
 92794 
 
 70 
 
 89695 
 
 90104 
 
 90484 
 
 90847 
 
 91181 
 
 91493 
 
 91793 
 
 92069 
 
 92333 
 
 92580 
 
 75 
 
 89464 
 
 89872 
 
 90252 
 
 90617 
 
 90952 
 
 91270 
 
 91569 
 
 91849 
 
 92111 
 
 92564 
 
 80 
 
 89225 
 
 89639 
 
 90021 
 
 90385 
 
 90723 
 
 91046 
 
 91340 
 
 91622 
 
 91891 
 
 92142 
 
 85 
 
 89043 
 
 89460 
 
 89843 
 
 90209 
 
 90558 
 
 90882 
 
 91186 
 
 91465 
 
 91729 
 
 91969 
 
 90 
 
 88817 
 
 89230 
 
 89617 
 
 89988 
 
 90342 
 
 90668 
 
 90967 
 
 91248 
 
 91511 
 
 91751 
 
 95 
 
 88588 
 
 89003 
 
 89390 
 
 89763 
 
 90119 
 
 90443 
 
 90747 
 
 91029 
 
 91290 
 
 91531 
 
 100 
 
 88357 
 
 88769 
 
 89158 
 
 89536 
 
 89889 
 
 90215 
 
 90522 
 
 90805 
 
 91066 
 
 91S10 
 
 Heat. 
 
 95 
 
 grains of 
 spirit to 
 100 gr.of 
 water. 
 
 90 
 
 grains of 
 spirit to 
 100 gr. of 
 water. 
 
 85 
 
 grains of 
 spirit to 
 lOOgr. of 
 water. 
 
 fcO 
 
 grains of 
 spirit to 
 100 gr.of 
 water. 
 
 15 
 
 grains of 
 spirit to 
 lOOgr. of 
 water. 
 
 7° J 
 
 grains of 
 spirit to 
 100 gr.of 
 water. 
 
 65 
 
 grains of 
 spirit to 
 lOOgr. of 
 water. 
 
 60 
 
 grains of 
 spirit to 
 100 gr.of 
 water. 
 
 55 
 
 grains of 
 spirit to 
 lOOgr. of 
 water. 
 
 60 
 
 grains of 
 spirit to 
 100 gr.of 
 water. 
 
 30° 
 
 •94447 
 
 •94675 
 
 •94920 
 
 •95173 
 
 •95429 
 
 *95681 
 
 *95944 
 
 •96209 
 
 *96470 
 
 •967J9 
 
 35 
 
 94249 
 
 94484 
 
 94734 
 
 94988 
 
 95246 
 
 95502 
 
 95772 
 
 96048 
 
 96315 
 
 965 79 
 
 40 
 
 94058 
 
 94295 
 
 94547 
 
 94802 
 
 95060 
 
 95328 
 
 95602 
 
 95879 
 
 96159 
 
 96434 
 
 45 
 
 93860 
 
 94096 
 
 94348 
 
 94605 
 
 94871 
 
 95143 
 
 95423 
 
 95705 
 
 95993 
 
 96280 
 
 50 
 
 93658 
 
 93897 
 
 94149 
 
 94414 
 
 94683 
 
 94958 
 
 95243 
 
 95534 
 
 95831 
 
 96126 
 
 55 
 
 93452 
 
 93696 
 
 93948 
 
 94213 
 
 94486 
 
 94767 
 
 95057 
 
 95357 
 
 95662 
 
 9 5966 
 
 60 
 
 93247 
 
 934 93 
 
 93749 
 
 94018 
 
 94296 
 
 94579 
 
 94876 
 
 95181 
 
 95493 
 
 95804 
 
 65 
 
 93040 
 
 93285 
 
 93546 
 
 93822 
 
 94099 
 
 94388 
 
 94689 
 
 95000 
 
 95318 
 
 95635 
 
 70 
 
 92828 
 
 93076 
 
 93337 
 
 93616 
 
 93898 
 
 94 1 93 
 
 94500 
 
 94813 
 
 95139 
 
 95469 
 
 75 
 
 92613 
 
 92865 
 
 95132 
 
 93413 
 
 93695 
 
 93989 
 
 94301 
 
 94623 
 
 94 957 
 
 95292 
 
 80 
 
 92395 
 
 92646 
 
 92917 
 
 93201 
 
 93488 
 
 937S5 
 
 94102 
 
 94431 
 
 94768 
 
 95111 
 
ALC 
 
 ALC 
 
 Heat. 
 
 45 
 
 grains of 
 spirit to 
 100 gr. 
 of water. 
 
 40 
 
 grains of 
 spirit to 
 100 gr. 
 of water. 
 
 35 
 
 grains of 
 spirit to 
 100 gr. 
 of water. 
 
 30 
 
 grains of 
 spirit to 
 100 gr. 
 of water. 
 
 25 
 
 grains of 
 spirit to 
 100 gr. 
 of water. 
 
 20 
 
 grains of 
 spirit to 
 100 gr. 
 of water. 
 
 15 
 
 grains of 
 spirit to 
 100 gr. 
 of water. 
 
 10 
 
 grains of 
 spirit to 
 100 gr. 
 ofwater. 
 
 5 
 
 grains of 
 spirit to 
 100 gr. 
 ofwater. 
 
 30° 
 
 •96967 
 
 •97200 
 
 •97418 
 
 *97635 
 
 •97860 
 
 *98108 
 
 *98412 
 
 •98804 
 
 *99334 
 
 35 
 
 96840 
 
 97086 
 
 97319 
 
 97556 
 
 97801 
 
 98076 
 
 98397 
 
 98804 
 
 99344 
 
 40 
 
 96706 
 
 96967 
 
 97220 
 
 97472 
 
 97737 
 
 98033 
 
 98373 
 
 98795 
 
 99345 
 
 45 
 
 96563 
 
 96840 
 
 97110 
 
 97384 
 
 97666 
 
 97980 
 
 98338 
 
 98774 
 
 99338 
 
 50 
 
 96420 
 
 96708 
 
 96995 
 
 97284 
 
 97589 
 
 97920 
 
 98293 
 
 98745 
 
 99316 
 
 55 
 
 96272 
 
 96575 
 
 96877 
 
 97181 
 
 97500 
 
 97847 
 
 98239 
 
 98702 
 
 99284 
 
 60 
 
 96122 
 
 96437 
 
 96752 
 
 97074 
 
 97410 
 
 97771 
 
 98176 
 
 98654 
 
 99244 
 
 65 
 
 95962 
 
 96288 
 
 96620 
 
 96959 
 
 97309 
 
 97688 
 
 98106 
 
 98594 
 
 99194 
 
 70 
 
 95802 
 
 96143 
 
 96484 
 
 96836 
 
 97203 
 
 97596 
 
 98028 
 
 98527 
 
 99134 
 
 75 
 
 95638 
 
 95987 
 
 96344 
 
 96708 
 
 97086 
 
 97495 
 
 97943 
 
 98454 
 
 99066 
 
 80 
 
 95467 
 
 95826 
 
 96192 
 
 96568 
 
 96963 
 
 97385 
 
 97845 
 
 98367 
 
 98991 
 
 From this table, when the specific gravity 
 of any spirituous liquor is ascertained, it will 
 be easy to find the quantity of rectified spirit 
 of the above-mentioned standard, contained 
 in any given quantity of it, either by weight 
 or measure. 
 
 Dr Elagden concludes this part of the re- 
 port with observing, that as the experiments 
 were made with pure spirit and water, if any 
 extraneous substances are contained in the 
 liquor to be tried, the specific gravity in the 
 tables will not give exactly the proportions 
 of water and spirit in it. The substances 
 likely to be found in spirituous liquors, 
 where no fraud is suspected, are essential 
 oils, sometimes empyreumatic, mucilaginous 
 or extractive matter, and perhaps some sac- 
 charine matter. The effect of these, in the 
 course of trade, seems to be hardly such as 
 would be worth the cognizance of the excise, 
 nor could it easily be reduced to certain 
 rules. Essential and empyreumatic oils are 
 nearly of the same specific gravity as spirit, 
 in general rather lighter, and therefore, not- 
 withstanding the mutual penetration, will 
 probably make little change in the specific 
 gravity of any spirituous liquor in which 
 they are dissolved. The other substances 
 are all heavier than spirit ; the specific gra- 
 vity of common gum being 1.482, and of 
 sugar 1.606, according to the tables of M. 
 lirisson. The effect of them therefore will 
 be to make spirituous liquors appear less 
 strong than they really are. An idea was 
 once entertained of endeavouring to deter- 
 mine this matter with some precision ; and 
 accordingly Dr Dollfuss evaporated 1000 
 giains of brandy, and the same quantity of 
 rum, to dryness ; the former left a residuum 
 of 40 grains, the latter only of 8| grains. 
 
 I he 40 grains of residuum from the brandy, 
 dissolved again in a mixture of 100 of spirit, 
 with 50 of water, increased its specific gra- 
 vity .00041 ; hence the effect of this extra- 
 neous matter upon the specific gravity of the 
 brandy containing it, would be to increase 
 the fifth decimal by six nearly, equal to what 
 would indicate in the above-mentioned mix- 
 
 ture, about one-seventh of a grain of water 
 more than the truth, to 100 of spirit ; a quan- 
 tity much too minute for the consideration of 
 government. 
 
 * The strength of spirits is determined, ac- 
 cording to the existing laws, by Sikes’ hydro- 
 meter ; but as many dealers use Dicas’s, I 
 shall describe it here, and the former under 
 Distillation. 
 
 It consists of a light copperball, terminating 
 
 below with a ballast bottom, and above with 
 
 a thin stem, divided into ten parts. The 
 
 upper extremity of the stem is pointed, to 
 
 receive the little brass poises, or discs, having 
 
 each a hole in its centre. These poises are 
 
 numbered 0, 10, 20, 50, &c. up to 350, 
 
 which is the lightest of the series. The in- 
 © 
 
 termediate units are given bv the subdivi- 
 sions on the stem. A graduated ivory 
 scale, with a sliding rule and thermometer, 
 accompanies the hydrometer, to make the cor- 
 rection for temperature. The first thing in 
 using this instrument is to plunge the ther- 
 mometer into a glass cylinder containing the 
 spirits to be tried. The sliding rule has then 
 the degree of temperature indicated, moved 
 opposite to zero. The hydrometer is now 
 placed in the liquid, and such a poise is put 
 on as to submerge a portion of the stem. 
 The weight, added to the number on the 
 stem, gives a sum, opposite to which on the 
 scale we find a quantity, by which the parti- 
 cular spirit may exceed or fall short of proof. 
 Thus, if it mark 20 under proof, it signifies 
 that every J00 gallons of that spirit would 
 require to have 20 gallons of water abstract- 
 ed from it to bring it up to proof. If it 
 mark 10 over proof, we learn that every 
 100 gallons contain too little. water, by 10 
 gallons. When the thermometric degree of 
 60° is put opposite to zero, then the weights 
 and value of the spirits have the following 
 relations on the scale. 
 
 102.5 denotes 20 under proof 
 
 1 22.0 1 0 
 
 143.5 Proof 
 
 167. 10 over proof 
 
 1 95 . 20 
 
ALC 
 
 ALC 
 
 221. denotes 30 over proof 
 
 251. 40 
 
 284.5 50 
 
 322.5 GO 
 
 350.5 Alcohol. 
 
 There is, besides, an upper line on the 
 scale, which exhibits the relation of spirit to 
 water reckoned unity. Thus, above 10 per 
 cent over proof in the second line, we find 
 in the upper line 8. From which we learn, 
 that 8 of that spirit by bulk, will take 1 of 
 water to bring it down to proof. At 60° 
 Fahr. I find that 10 over proof on Dicas 
 corresponds to specific gravity 0.9085 
 over proof to 0.91 6 9 
 
 Proof, - 0.9218 
 
 Now, by Gilpin’s tables this indicates a 
 compound of 100 grains of alcohol 0.825, 
 and 85 grains of water. But by Lowitz’s 
 table in Crell’s Annals, the above specific 
 gravity corresponds to 48 alcohol of 0.791 
 at the temperature of 68°, united to 52 of 
 water, and cooled down to 60. Equal 
 weights of that strong alcohol and water, 
 give, at 60°, a specific gravity of 0.9175. 
 By the Act of Parliament of 1762, the spe- 
 cific gravity of proof was fixed at 0.916, It 
 is at present to water as 12 to 13, or = 
 0.925. See Distillation.* 
 
 The most remarkable characteristic pro- 
 perty of alcohol, is its solubility or combina- 
 tion in all proportions with water ; a pro- 
 perty possessed by no other combustible sub- 
 stance, * except the acetic spirit obtained by 
 distilling the dry acetates,* When it is burn- 
 ed in a chimney which communicates with 
 the worm-pipe of a distilling apparatus, the 
 product, which is condensed, is found to 
 consist of water, which exceeds the spirit in 
 weight about one-eighth part ; * or more ac- 
 curately, 100 parts of alcohol, by combus- 
 tion, yield 136 of water.* If alcohol be 
 burned in closed vessels with vital air, the 
 product is found to be water and carbonic 
 acid. Whence it is inferred that alcohol 
 consists of hydrogen, united either to carbo- 
 nic acid or its acidifiable base ; and that the 
 oxygen uniting on the one part with the hy- 
 drogen, forms water ; and on the other with 
 the base of the carbonic acid, forms that 
 acid. 
 
 * The most exact experiments on this 
 subject are those recently made by M. de 
 Saussure. The alcohol he used had, at 
 62°. 8, a specific gravity of 0.8302; and by 
 Richter’s proportions, it consists of 13.8 
 water, and 86.2 of absolute alcohol. The 
 vapour of alcohol was made to traverse a 
 narrow porcelain tube ignited, from which 
 the products passed along a glass tube about 
 six feet in length, refrigerated by ice. A 
 little charcoal was deposited in the porcelain, 
 and a trace of oil in the glass tube. The 
 resulting gas being analyzed in an exploding 
 eudiometer, with oxygen, was found to re- 
 
 solve itself into carbonic acid and water. 
 Three volumes of oxygen disappeared for 
 every two volumes of carbonic acid produc- 
 ed ; a proportion which obtains, in the ana- 
 lysis by oxygenation of olefiant gas. Now, 
 as nothing resulted but a combustible gas of 
 this peculiar constitution, and condensed 
 
 water equal to ifhT original weight 
 
 of the alcohol, we may conclude, that vapour 
 of water and olefiant gas are the sole consti- 
 tuents of alcohol. Subtracting the 13.8 per 
 cent of water in the alcohol at the beginning 
 of the experiment, the absolute alcohol of 
 Richter will consist of 13.7 hydrogen, 51.98 
 carbon, and 54.32 oxygen. Hence M. Gay 
 Lussac infers, that alcohol, in vapour, is 
 composed of one volume olefiant gas, and 
 one volume of the vapour of water, con- 
 densed by chemical affinity into one volume. 
 
 The sp. gr. of olefiant gas is 0.97804 
 
 Of aqueous vapour is 0.62500 
 
 Sum = 1.60304 
 
 And alcoholic vapour is = 1.6133 
 
 These numbers approach nearly to those 
 which would result from two prime equiva- 
 lents of olefiant gas, combined with one of 
 water; or ultimately, three of hydrogen, two 
 of carbon, and one of oxygen.* 
 
 A considerable number of the uses of this 
 fluid as a menstruum, will pass under our 
 observation in the various articles of this 
 work. The mutual action between alcohol 
 and acids produces a light, volatile, and in- 
 flammable oil, called ether. See Ether. 
 Pure alkalis unite with spirit of wine, and 
 form alkaline tinctures. Few of the neutral 
 salts unite with this fluid, except such as 
 contain ammonia. The carbonated fixed al- 
 kalis are not soluble in it. From the strong 
 attraction which exists between alcohol and 
 water, it unites 'with this last in saline solu- 
 tions, and in most cases precipitates the salt. 
 This is a pleasing experiment, which never 
 fails to surprise those who are unacquainted 
 with chemical effects. If, for example, a 
 saturated solution of nitre in water be taken, 
 and an equal quantity of strong spirit of 
 wine be poured upon it, the mixture will 
 constitute a weaker spirit, which is incapable 
 of holding the nitre in solution ; it therefore 
 falls to the bottom instantly, in the form of 
 minute crystals. 
 
 The degrees of solubility of many neutral 
 salts in alcohol have been ascertained bv ex- 
 periments made by Macqucr, of which an 
 account is published in the Memoirs of the 
 Turin Academy. The alcohol he employed 
 w as carefully freed from superabundant w ater 
 by repeated rectifications, without addition 
 of any intermediate substance. The salts 
 employed in his experiments were previously 
 deprived of their water of crystallization by a 
 careful drying, lie poured into a matrass, 
 
ALC 
 
 Ai.C 
 
 upon each of the salts thus prepared, half an 
 ounce of his alcohol, and set the matrass in 
 a sand-bath. When the spirit began to boil, 
 he filtrated it while it was hot, and left it to 
 cool, that he might observe the crystalliza- 
 tions which took place. He then evaporated 
 the spirit, and weighed the saline residuums. 
 
 He repeated these experiments a second 
 time, with this difference, that instead of 
 evaporating the spirit in which the salt had 
 been digested, he set fire to it in order to 
 examine the phenomena which its flame 
 might exhibit. The principal results of his 
 experiments are subjoined. 
 
 Quantity 
 of' grains. 
 
 Salts soluble in 
 200 grains of spirit. 
 
 4 
 
 Nitrate of potash 
 
 5 
 
 Muriate of potash 
 
 0 
 
 Sulphate of soda 
 
 15 
 
 Nitrate of soda 
 
 0 
 
 Muriate of soda 
 
 0 
 
 Sulphate of ammonia 
 
 108 
 
 Nitrate of ammonia 
 
 24 
 
 Muriate of ammonia 
 
 238 
 
 Nitrate of lime 
 
 288 
 
 Muriate of lime 
 
 84 
 
 Nitrate of silver 
 
 204 
 
 Muriate of mercury 
 
 4 
 
 Nitrate of iron 
 
 36 
 
 Muriate of iron 
 
 48 
 
 Nitrate of copper 
 
 48 
 
 Muriate of copper 
 
 Peculiar phenomena of the fame. 
 
 ( Flame larger, higher, more ardent, yellow, 
 I and luminous. 
 
 Large, ardent, yellow, and luminous. 
 Considerably red. 
 
 Yellow, luminous, detonating. 
 
 Larger, more ardent, and reddish. 
 
 None. 
 
 Whiter, more luminous. 
 
 None. 
 
 C Larger, more luminous, red and dccrepi- 
 | tating. 
 
 Like that of the calcareous nitre. 
 
 None. 
 
 Large, yellow, luminous and decrepitating, 
 lied and decrepitating. 
 
 More white, luminous and sparkling. 
 TMore white, luminous and green, much 
 < smoke. The saline residuum became 
 C black and burnt. 
 
 Fine green, white, and red figurations. 
 
 Macquer accompanies the relation of his 
 experiments with many judicious reflections, 
 not easily capable of abridgment. 
 
 * The alcohol he employed in the above 
 experiments had a specific gravity of 0.840. 
 In analytical researches, alcohol affords fre- 
 quently a valuable agent for separating salts 
 from each other. We shall therefore intro- 
 duce the following additional table, derived 
 chiefly from the experiments of Wenzel : — 
 
 1 00 parts of alcohol dissolve of 
 
 
 Temp . 
 
 
 Nitrate of Cobalt at 
 
 54°.5 
 
 1 00 parts 
 
 Copper 
 
 54°.5 
 
 100 
 
 Alumina 
 
 54°. 5 
 
 100 
 
 Lime 
 
 
 125 
 
 Magnesia 
 
 1 80.5 
 
 290 
 
 Muriate of Zinc 
 
 54°.5 
 
 100 
 
 Alumina 
 
 54.5 
 
 100 
 
 Magnesia 
 
 1 80.5 
 
 547 
 
 Iron 
 
 180.5 
 
 100 
 
 Copper 
 
 1 80.5 
 
 100 
 
 Acetate of Lead 
 
 154°.5 
 
 100 
 
 At the boiling point, 
 
 100 parts of alcohol 
 
 dissolve of muriate of lime 
 
 100 parts 
 
 Nitrate of ammonia, 
 
 89 
 
 Corrosive sublimate, 
 
 88.8 
 
 Succinic acid, 
 
 • 
 
 74.0 
 
 A cetate of soda, 
 
 • 
 
 46.5 
 
 Nitrate of silver, 
 
 ■» 
 
 41.7 
 
 Kefincd sugar, 
 
 ~ 
 
 24.6 
 
 Boracic acid, 
 
 • 
 
 20.0 
 
 Nitrate of soda, 
 
 
 9.6 
 
 Acetate of copper, 
 
 7.5 
 
 Muriate of ammonia, 
 
 7.1 
 
 Superarseniate of potash, 
 
 5.75 
 
 Oxalate of potash, 
 
 2.92 
 
 Nitrate of potash, 
 
 2.08 
 
 Muriate of potash, 
 
 2.08 
 
 Arseniate of soda, 
 
 1.58 
 
 Arsenious acid, 
 
 1.25 
 
 Tartrate of potash, 
 
 0.42 
 
 It appears from the experiments of Kir- 
 wan, that dried muriate of magnesia dis- 
 solves more abundantly in strong than in 
 weak alcohol. 100 parts of specific gravity 
 0.900, dissolve 21.25 ; of 0.848, 23.7 5 ; of 
 0.834, 36.25 ; and of 0.817, 50 parts. The 
 same holds to a more limited extent with 
 acetate of lime, 2.4 grains being soluble in 
 100 of the first alcohol, and 4.88 in 100 of 
 the hast. The other salts which he tried dis- 
 solved more sparingly in the stronger than 
 in the weaker alcohol. The temperature of 
 the spirit was generally 60°. 
 
 All deliquescent salts are soluble in alco- 
 hol. Alcohol holding the strontitic salts in 
 solution, gives a flame of a rich purple. 
 The cupreous salts and boracic acid give a 
 green ; the soluble calcareous, a reddish ; 
 the barytie, a yellowish. For the effect of 
 other salts on the colour of the flame, see a 
 preceding table. 
 
 The alcohol of 0.825 has been subjected 
 to a cold of — 91° without congealing, 
 lint Mr Hutton has given, in the Edinburgh 
 Encyclopedia, article Cold, an account of his 
 
ALC 
 
 ALC 
 
 having succeeded in solidifying it by a cold 
 of — 110°. The alcohol he employed had 
 a density of 0.798 at 60°. His process has 
 been kept secret. The boiling point of al- 
 cohol of 0.825 is 176°. Alcohol of 0.810 
 boils at 173°.5. For the force of its vapour 
 at different temperatures, and its specific 
 heat, see Vapour. 
 
 V hen potassium and sodium are putin 
 contact with the strongest alcohol, hydrogen 
 is evolved. From this experiment we may in- 
 fer, that the term absolute alcohol should 
 not be applied to the liquid of Richter. 
 Probably by distilling alcohol off potassium, 
 it would be obtained free from water. When 
 chlorine is made to pass through alcohol in 
 a Woolfe’s apparatus, there is a mutual ac- 
 tion. Water, an oily looking substance, mu- 
 riatic acid, a little carbonic acid, and car- 
 bonaceous matter, are the products. This 
 oily substance dees not redden turnsole, 
 though its analysis by heat shews it to con- 
 tain muriatic acid. It is white, denser than 
 water, has a cooling taste analogous to mint, 
 and a peculiar, but not ethereous odour. It 
 is very soluble in alcohol, but scarcely in 
 water. The strongest alkalis hardly operate 
 on it. 
 
 It was at one time maintained, that al- 
 cohol did not exist in wines, but was gene- 
 rated and evolved by the heat of distillation. 
 On this subject M. Gay Lussac made some 
 decisive experiments. He agitated wine with 
 litharge in fine powder, till the liquid became 
 as limpid as water, and then saturated it with 
 subcarbonate of potash. The alcohol im- 
 mediately separated and floated on the top. 
 He distilled another portion of wine in vacuo , 
 at 59° Fahr. a temperature considerably be- 
 low that of fermentation. Alcohol came over. 
 Mr Braude proved the same position by sa- 
 turating wine with subacetate of lead, and 
 adding potash. 
 
 MM. Adam and Duportal have substitut- 
 ed for the redistillations used in converting 
 wine or beer into alcohol, a single process of 
 great elegance. From the capital of the still a 
 tube is led into a large copper recipient. 
 This is joined by a second tube, to a second 
 recipient, and so on through a series of four 
 vessels, arranged like a Woolfe’s apparatus. 
 The last vessel communicates with the worm 
 of the first refrigeratory. This, the body of the 
 still, and the two recipients nearest it, are 
 charged with the wine or fermented liquor. 
 When ebullition takes place in the still, the 
 vapour issuing from it communicates soon 
 the boiling temperature to the liquor in the 
 two recipients. From these the volatilized 
 alcohol will rise and pass into the third vessel, 
 which is empty. After communicating a 
 certain heat to it, a portion of the finer or 
 less condensable spirit will pass into the 
 fourth, and thence, in a little, into the worm 
 of the first refrigeratory. The wine round 
 
 the worm will likewise acquire heat, but 
 more slowly. The vapour that in that event 
 may pass uncondensed through the first worm, 
 is conducted into a second, surrounded with 
 cold water. Whenever the still is work- 
 ed off, it is replenished by a stop-cock from 
 the nearest recipient, which, in its turn, 
 is filled from the second, and the second 
 from the first worm tub. It is evident, from 
 this arrangement, that by keeping the 3d and 
 4th recipients at a certain temperature, wo 
 may cause alcohol, of any degree of lightness, 
 to form directly at the remote extremity 
 of the apparatus. The utmost economy of 
 fuel and time is also secured, and a better 
 flavoured spirit is obtained. The arricre 
 gout of bad spirit can scarcely be destroyed 
 by infusion with charcoal and redistillation. 
 In this mode of operating, the taste and 
 smell are excellent, from the first. Several 
 stills on the above principle have been con. 
 structed at Glasgow for the West India dis- 
 tillers, and have been found extremely ad- 
 vantageous. The excise laws do not per- 
 mit their employment in the home trade.* 
 
 If sulphur in sublimation meet with the 
 vapour of alcohol, a very small portion com- 
 bines with it, which communicates a hvdro- 
 sulphurous smell to the fluid. The increased 
 surface of the two substances appears to fa- 
 vour the combination. It had been suppos- 
 ed, that this was the only way in which they 
 could be united ; but M. Favre has lately 
 asserted, that, having digested two drams of 
 flowers of sulphur in an ounce of alcohol, 
 over a gentle fire not sufficient to make it 
 boil, for twelve hours, he obtained a solution 
 that gave twenty-three grains of precipitate. 
 A similar mixture left to stand for a month 
 in a place exposed to the solar rays, afforded 
 sixteen grains of precipitate ; and another, 
 from which the light was excluded, gave 
 thirteen grains. If alcohol be boiled with 
 one-fourth of its weight of sulphur for an 
 hour, and filtered hot, a small quantity of 
 minute crystals will be deposited on cooling; 
 and the clear fluid will assume an opaline 
 hue on being diluted with an equal quantity 
 of water, in which state it will pass the filter, 
 nor will any sediment be deposited for seve- 
 ral hours. The alcohol used in the last- 
 mentioned experiment did not exceed .840. 
 
 Phosphorus is sparingly soluble in alcohol, 
 but in greater quantity by heat than in cold. 
 The addition of water to this solution affords 
 an opaque milky fluid, which gradually be- 
 comes clear by the subsidence of the phos- 
 phorus. 
 
 Earths seem to have scarcely any action 
 upon alcohol. Quick-lime, however, pro- 
 duces some alteration in this fluid, by chang- 
 ing its flavour and rendering it of a yellow 
 colour. A small portion is probably taken 
 up. 
 
 Soaps are dissolved with great facility 
 
ALC 
 
 ALK 
 
 alcohol, with which they combine more 
 readily than with water. None of the me- 
 tals, or their oxides, are acted upon by this 
 fluid. Resins, essential oils, camphor, bitu- 
 men, and various other substances, are dis- 
 solved with great facility in alcohol, from 
 which they may be precipitated by the addi- 
 tion of water. From its property of dissolv- 
 ing resins, it becomes the menstruum ol one 
 class of varnishes. See Varnish. 
 
 Camphor is not only extremely soluble in 
 alcohol, but assists the solution of resins in 
 it. Fixed oils, when rendered drying by 
 metallic oxides, are soluble in it, as well as 
 when combined with alkalis. 
 
 Wax, spermaceti, biliary calculi, urea, and 
 all the animal substances of a resinous na- 
 ture, are soluble in alcohol ; but it curdles 
 milk, coagulates albumen, and hardens the 
 muscular fibre and coagulum of the blood. 
 
 The uses of alcohol are various. As a 
 solvent of resinous substances and essential 
 oils, it is employed both in pharmacy and by 
 the perfumer. When diluted with an equal 
 quantity of water, constituting what is called 
 proof spirit, it is used for extracting tinc- 
 tures from vegetable and other substances, 
 the alcohol dissolving the resinous parts, and 
 the %vater the gummy. From giving a steady 
 heat without smoke when burnt in a lamp, 
 it was formerly much employed to keep 
 water boiling on the tea-table. In thermo- 
 meters for measuring great degrees of cold, 
 it is preferable to mercury, as we cannot 
 bring it to freeze. It is in common use for 
 preserving many anatomical preparations, 
 and certain subjects of natural history ; but 
 to some it is injurious, the molluscae for in- 
 stance, the calcareous covering of which it 
 in time corrodes. It is of considerable use 
 too in chemical analysis, as appears under 
 the different articles to which it is applica- 
 ble. 
 
 From the great expansive power of alco- 
 hol, it has been made a question, whether it 
 might not be applied with advantage in the 
 working of steam engines. From a series 
 of experiments made by Betancourt, it ap- 
 pears, that the steam of alcohol has, in all 
 cases of equal temperature, more than dou- 
 ble the force of that of water ; and that the 
 steam of alcohol at 1 74° F. is equal to that 
 of water at 21 2° : thus there is a considerable 
 diminution of the consumption of fuel, and 
 where this is so expensive as to be an object 
 of great importance, by contriving the ma- 
 chinery so as to prevent the alcohol from 
 being lost, it may possibly at some future 
 time be used with advantage, if some other 
 fluid of great expansive power, and inferior 
 price, be not found more economical. 
 
 It was observed at the beginning of this 
 article, that alcohol might be decomposed by 
 transmission through a red-hot tube : it is 
 
 also decomposable by the strong acids, and 
 thus affords that remarkable product, Ether, 
 and Oleum Vini. 
 
 Ale. See Beer. 
 
 Alembic, or Still. This part of chemi- 
 cal apparatus, used for distilling or separat- 
 ing volatile products, by first raising them 
 by heat, and then condensing them into the 
 liquid state by cold, is of extensive use in a 
 variety of operations. It is described under 
 the article Laboratory. 
 
 Alembroth Salt. Corrosive muriate of 
 mercury is rendered much more soluble in 
 water, by the addition of muriate of ammo- 
 nia. From this solution crystals are sepa- 
 rated by cooling, which were called sal- 
 alembroth by the earlier chemists, and ap- 
 pear to consist of ammonia, muriatic acid, 
 and mercury. 
 
 Algarotii (PowrER of). Among the 
 numerous preparations which the alchemi- 
 cal researches into the nature of antimony 
 have afforded, the powder of algaroth is one. 
 When butter of antimony is thrown into wa- 
 ter, it is not totally dissolved ; but part of 
 the metallic oxide falls down in the form of 
 a white powder, which is the powder of al- 
 garoth. It is violently purgative and emetic 
 in small doses of three or four grains. See 
 Antimony. 
 
 Alkahest. The pretended universal sol- 
 vent, or menstruum, of the ancient chemists. 
 Kunckel has very well shown the absurdity 
 of searching for a universal solvent, by ask- 
 ing, “ If it dissolve all substances, in what 
 vessels can it be contained?” 
 
 Alkalescent. Any substance in which 
 alkaline properties are beginning to be de- 
 veloped, or to predominate, is termed alka- 
 lescent. The only alkali usually observed 
 to be produced by spontaneous decompo- 
 sition is the volatile ; and from their ten- 
 dency to produce this, some species of vege- 
 tables, particularly the cruciform, are styled 
 alkalescent, as are some animal substances. 
 See Fermentation (Putrid). 
 
 * Alkali. A term derived from kali the 
 Arabic name of a plant, from the ashes of 
 which one species of alkaline substance can 
 be extracted. Alkalis may be defined, those 
 bodies which combine with acids, so as to 
 neutralize or impair their activity, and pro- 
 duce salts. Acidity and alkalinity are there- 
 fore two correlative terms of one species of 
 combination. When Lavoisier introduced 
 oxygen as the acidifying principle, Morveau 
 proposed hydrogen as the alkalifying princi- 
 ple, from its being a constituent of volatile 
 alkali or ammonia. But the splendid dis- 
 covery bv Sir II. Davy, of the metallic bases 
 of potash and soda, and of their conversion 
 into alkalis, by combination with oxygen, 
 has banished lor ever that hypothetical con- 
 ceit. it is the mode in which the consti- 
 
ALK 
 
 ALK 
 
 tuents are combined, rather than the nature 
 of the constituents themselves, which gives 
 rise to the acid or alkaline condition. Some 
 metals combined with oxygen in one pro- 
 portion, produce a body possessed of alkaline 
 properties, in another proportion of acid pro- 
 perties. And on the other hand, ammonia 
 and prussic acid prove that both the alkaline 
 and acid conditions can exist independent of 
 oxygen. These observations by generalizing 
 our notions of acids and alkalis, have rendered 
 the definitions of them very imperfect. The 
 difficulty of tracing a limit between the acids 
 and alkalis is still increased, when we find a 
 body sometimes performing the functions of 
 an acid, sometimes of an alkali. Nor can 
 we diminish this difficulty by having recourse 
 to the beautiful law discovered by Sir II. Davy, 
 that oxygen and acids go to the positive pole, 
 and hydrogen, alkalis, and inflammable bases 
 to the negative pole. We cannot in fact 
 give the name of acid to all the bodies which 
 go to the first of these poles, and that of al- 
 kali to those that go to the second ; and if we 
 wished to define the alkalis by bringing into 
 view their electric energy, it would be neces- 
 sary to compare them with the electric ener- 
 gy which is opposite to them. Thus we 
 are always reduced to define alkalinity by 
 the property which it has of saturating 
 acidity, because alkalinity and acidity are 
 two correlative and inseparable terms. M. 
 Gay Lussac conceives the alkalinity which 
 the metallic oxides enjoy to be the result of 
 two opposite properties, the alkalifying pro- 
 perty of the metal, and the acidifying of 
 oxygen, modified both by the combination 
 and by the proportions. 
 
 The alkalis may be arranged into three 
 classes: 1$£, Those which consist of a me- 
 
 tallic basis combined with oxygen. These 
 are three in number, potash, soda and 
 lithia. 2 d, That which contains no oxygen, 
 viz. ammonia. 3d, Those containing oxy- 
 gen, hydrogen, and carbon. In this class we 
 have aconita, atropia, brucia, cicuta, datura, 
 delphia, hyosciama, morphia, strychnia, and 
 perhaps some other truly vegetable alkalis. 
 The order of vegetable alkalis may be 
 as numerous as that of vegetable acids. 
 The earths, lime, barytes, and strontites were 
 enrolled among the alkalis by Fourcroy, but 
 they have been kept apart by other systematic 
 writers, and are called alkaline earths. 
 
 Besides neutralizing acidity, and thereby 
 giving birth to salts, the first four alkalis 
 have the following properties : 
 
 1st, They change the purple colour of 
 many vegetables to a green, the reds to a pur- 
 ple, and the yellows to a brown. If the pur- 
 ple have been reddened by acid, alkalis restore 
 the purple. 
 
 2d, They possess this power on vegetable 
 colours after being saturated with carbonic 
 
 acid, by which criterion they are distinguish- 
 able from the alkaline earths. 
 
 3d, They have an acrid and urinous taste. 
 
 4th, They are powerful solvents or cor- 
 rosives of animal matter; with which, as 
 well as with oils in general, they combine, 
 so as to produce neutrality. 
 
 5th, They are decomposed, or volatilized, 
 at a strong red heat. 
 
 6lh, They combine with water in every 
 proportion, and also largely with alcohol. 
 
 1th, They continue to be soluble in water 
 when neutralized with carbonic acid; while 
 the alkaline earths thus become insoluble. 
 
 It is needless to detail at length Dr 
 Murray’s speculations on alkalinity. They 
 seem to flow from a partial view of che- 
 mical phenomena. According to him, 
 either oxygen or hydrogen may generate 
 alkalinity, but the combination of both 
 principles is necessary to give this con- 
 dition its utmost energy. “ Thus the class 
 of alkalis will exhibit the same relations 
 as the class of acids. Some are com- 
 pounds of a base with oxygen ; such are the 
 greater number of the metallic oxides, and 
 probably of the earths. Ammonia is a com- 
 pound of a base with hydrogen. Potash, soda, 
 barytes, strontites, and probably lime, are 
 compounds of bases with oxygen and hydro- 
 gen ; and these last, like the analogous order 
 among the acids, possess the highest power.” 
 Now, surely, perfectly dry and caustic 
 barytes, lime, and strontites, as well as the 
 dry potash and soda obtained by Gay Lussac 
 and Thenard, are not inferior in alkaline 
 power to the same bodies after they are 
 slacked or combined with w r ater. 100 parts 
 of lime destitute of hydrogen, that is, pure 
 oxide of calcium, neutralize 78 parts of car- 
 bonic acid. But 132 parts of Dr Murray’s 
 strongest lime, that is the hydrate, are re- 
 quired to produce the same alkaline effect. 
 If w r e ignite nitrate of barytes, we obtain, as 
 is well known, a perfectly dry barytes, or 
 protoxide of barium ; but if w r e ignite crys- 
 tallized barytes, we obtain the same alkaline 
 earth combined with a prime equivalent of 
 water. These two different states of barytes 
 were demonstrated by M. Berthollet in an 
 excellent paper published in the 2d volume 
 of the Memoires D’Arcueil, so far back as 
 1809. “ The first barytes,” (that from 
 
 crystallized barytes), says he, “ presents all 
 the characters of a combination ; it is engag- 
 ed with a substance which diminishes its ac- 
 tion on other bodies, which renders it more 
 fusible, and which gives it by fusion the ap- 
 pearance of glass. This substance is nothing 
 else but water ; but in fact, by adding a 
 little w r ater to the second barytes (that from 
 ignited nitrate), and by urging it at the fire, 
 we give it the properties of the first.” Page 
 47. 100 parts of barytes void of hydrogen, 
 
ALK 
 
 ALL 
 
 or dry barytes, neutralize 28^§ of dry carbonic 
 acid. Whereas 1 11 j parts of the hydrate, 
 or vvhat Dr Murray has styled the most 
 energetic, are required to produce the same 
 effect. In fact, it is not hydrogen which 
 combines with the pure barytic earth, but 
 hydrogen and oxygen in the state of water. 
 The proof of this is, that when carbonic acid 
 and that hydrate unite, the exact quantity of 
 water is disengaged. The protoxide ot 
 barium, or pure barytes, has never been com- 
 bined with hydrogen by any chemist.* 
 
 Alkali (Phlogisticated, or Prussian). 
 When a fixed alkali is ignited with bullock’s 
 blood, or other animal substances, and lixi- 
 viated, it is found to be in a great measure 
 saturated with the prussic acid : from the 
 theories formerly adopted respecting this 
 combination, it was distinguished by the 
 name of phlogisticated alkali. See Acid 
 (Prussic). 
 
 Alkali (Volatile). See Ammonia. 
 
 * Alkalimeter. The name first given by 
 M. Descroizilles to an instrument or measure 
 of his graduation, for determining the quantity 
 of alkali in commercial potash and soda, by 
 the quantity of dilute sulphuric acid of a 
 known strength which a certain weight of 
 them could neutralize. Plis method Mas 
 unnecessarily operose. A much simpler, 
 and very accurate mode, was exhibited by 
 Dr Ure before the Linen Board of Dublin 
 in June 1816, and soon afterwards submitted 
 in manuscript to Dr Henry, who has since 
 then expunged the description of M. Des- 
 croizilles’ alkalimeter from his valuable ele- 
 ments, and substituted one on Dr Ure’s prin- 
 ciple. More recently Dr Ure has been oc- 
 cupied in completing the arrangement of an 
 instrument for giving increased facility and 
 dispatch to chemical analysis in general. 
 It will apply to alkalis, acids, earths, metals, 
 Sec. He hopes to be able, very soon, to sub- 
 mit its construction and performance to the 
 tribunal of the public. Meanwhile direc- 
 tions will be given in this w r ork under the 
 individual alkalis, for ascertaining the quali- 
 ty of commercial specimens. * 
 
 Alkanet. The alkanet plant is a kind 
 of bugloss, which is a native of the wnrmer 
 parts of Europe, and cultivated in some of 
 our gardens. The greatest quantities are 
 raised in Germany and France, particularly 
 about Montpelier, whence we are chiefly 
 supplied with the roots. These are of a su- 
 perior quality to such as are raised in Eng- 
 land. This root imparts an elegant deep 
 red colour to pure alcohol, to oils, to wax, 
 md to all unctuous substances. The aque- 
 ous tincture is of a duli brownish colour ; 
 is is likewise the spirituous tincture when 
 nspissated to the consistence of an extract. 
 Hie principal use of alkanet root is, that of 
 colouring oils, unguents, and lip-salves. 
 Wax tinged with it, and applied on warm 
 
 marble, stains it of a flesh colour, which 
 sinks deep into the stone ; as the spirituous 
 tincture gives it a deep red stain. 
 
 As the colour of this root is confined to 
 the bark, and the small roots have more 
 bark in proportion to their bulk than the 
 great ones, these also afford most colour. 
 
 * Allanite. A mineral first recognized as 
 a distinct species by Mr Allan, of Edin- 
 burgh, to whose accurate knowledge, and 
 splendid collection, the science of mineralogy 
 has been so much indebted in Scotland. Its 
 analysis and description, by Dr Thomson, 
 were published in the 6th volume of the 
 Edinburgh Ph. Trans. M. Giesecke found 
 it in a granite rock in West Greenland. It 
 is massive and of a brownish black colour. 
 External lustre, dull ; internal, shining and 
 resinous — fracture small conchoidal — opaque 
 — greenish gray streak — scratches glass and 
 hornblende — brittle — spec. grav. 3.5 to 4.0. 
 Froths and melts imperfectly before the blow- 
 pipe, into a black scoria. It consists in 100 
 parts, of silica 35.4, oxide of cerium 33.9, 
 oxide of iron 25.4, lime 9.2, alumina 4.1, and 
 moisture 4.0. It has been also found crys- 
 tallized in four, six, or eight-sided prisms. It 
 closely resembles gadolinite, but may be dis- 
 tinguished from the thin fragments of the lat- 
 ter being translucent on the edges, and of a fine 
 green colour, w r hereas those of the former are 
 commonly opaque and of a yellowish brown. 
 The ores of cerium analyzed by Berzelius, un- 
 der the name of cerin, approach very closely 
 in their composition to allanite.* 
 
 * Allochroite. A massive opaque mineral 
 
 of a greyish, yellowish, or reddish colour. 
 Quartz scratches it, but it strikes fire with 
 steel. It has externally, a glistening, and 
 internally, a glimmering lustre. Its frac- 
 ture is uneven, and its fragments are trans- 
 lucent on the edges : sp. gr. 3.5 to 3.6. It 
 melts before the blow- pipe into a black opaque 
 enamel. Vauquelin’s analysis is the follow- 
 ing : Silica 35, lime 30.5, oxide of iron 
 
 17, alumina 8, carbonate of lime 6, oxide of 
 manganese 3.5. M. Brogniart says it is abso- 
 lutely infusible without addition, and that it 
 requires a flux as phosphate of soda or am- 
 monia. With these it passes through a beau- 
 tiful gradation of colours. It is covered at 
 first with a species of enamel, which becomes 
 on cooling reddish yellow, then greenish, 
 and lastly of a dirty yellowish white. He 
 represents it as pretty difficult to break. It 
 was found by M. Dandrada in the iron mine 
 of Virums, near Drammen in Norw ay. It 
 is accompanied by carbonate of lime, protoxide 
 of iron, and sometimes brown garnets.* 
 
 * Alloehane. A mineral of a blue, and 
 sometimes a green or brown colour, which 
 occurs massive, or in imitative shapes. Lustre 
 vitreous ; fracture imperfectly conchoidal ; 
 transparent or translucent on the edges. 
 Moderately hard, but very brittle. Sp. gr. 
 
ALL 
 
 ALL 
 
 1 . 89. Composition, silica 21 .92, alumina 92.2, 
 lime 0.73, sulphate of lime 0.32, carbonate 
 of copper 3.06, hydrate of iron 0.27, water 
 41.3. Stromei/er . It gelatinizes in acids : It 
 is found in a bed of ironshot limestone in 
 greywacke slate, in the forest of Thuringia. 
 It was called Riemannite.* 
 
 Allay, or Alloy. Where any precious 
 metal is mixed with another of less value, the 
 assayers call the latter the alloy, and do not 
 in general consider it in any other point of 
 view than as debasing or diminishing the 
 value of the precious metal. Philosophical 
 chemists have availed themselves of this term 
 to distinguish all metallic compounds in ge- 
 neral. Thus brass is called an alloy of cop- 
 per and zinc ; bell metal an alloy of copper 
 and tin. 
 
 * Every alloy is distinguished by the me- 
 tal which predominates in its composition, 
 or which gives it its value. Thus English 
 jewellery trinkets are ranked under alloys 
 of gold, though most of them deserve to be 
 placed under the head of copper. When 
 mercury is one of the component metals, the 
 alloy is called amalgam. Thus we have an 
 amalgam of gold, silver, tin, &c. Since there 
 are about 30 different permanent metals, in- 
 dependent of those evanescent ones that con- 
 stitute the bases of the alkalis and earths, 
 there ought to be about 870 different species 
 of binary alloy. But only 152 species have 
 been hitherto made and examined. Some 
 metals have so little affinity for others, that 
 as yet no compound of them has been effect- 
 ed, w hatever pains have been taken. Most of 
 these obstacles to alloying, arise from the 
 difference in fusibility and volatility. Yet a 
 few metals wffiose melting point is nearly the 
 same, refuse to unite. It is obvious that two 
 bodies will not combine, unless their affinity 
 or reciprocal attraction, be stronger than the 
 cohesive attraction of their individual par- 
 ticles. To overcome this cohesion of the 
 solid bodies, and render affinity predominant, 
 they must be penetrated by caloric. If one 
 be very difficult of fusion, and the other very 
 volatile, they will not unite unless the reci- 
 procal attraction be exceedingly strong. But 
 if their degree of fusibility be almost the same, 
 they are easily placed in the circumstances 
 most favourable for making an alloy. If we 
 are therefore far from knowing all the bi- 
 nary alloys which are possible, w r e are still 
 further removed from knowing all the triple, 
 quadruple, &c. which may exist. It must be 
 confessed, moreover, that this department ot 
 chemistry has been imperfectly cultivated. 
 
 Besides, alloys are not, as far as we know, 
 definitely regulated like oxides in the pro- 
 portions of their component parts. 100 
 parts of mercury will combine w ith 4, or 8, 
 parts of oxygen, to form two distinct oxides, 
 the black and the red ; but with no greater, 
 less, or intermediate proportions, But 100 
 
 parts of mercury will unite with 1, 2, 3, or 
 with any quantity up to a 100 or 1000, of 
 tin or lead. The alloys have the closest re- 
 lations in their physical properties with the 
 metals. They are all solid at the temperature 
 of the atmosphere, except some amalgams; 
 they possess metallic lustre, even w-hen re- 
 duced to a coarse pow der ; are completely 
 opaque, aud more or less dense, according 
 to the metals which compose them ; are ex- 
 cellent conductors of electricity; crystallize 
 more or less perfectly ; some are brittle, 
 others ductile and malleable; some have a 
 peculiar odour ; several are very sonorous 
 and elastic. When an alloy consists of 
 metals differently fusible, it is usually mal- 
 leable while cold, but brittle while hot; us is 
 exemplified in brass. 
 
 The density of an alloy is sometimes 
 greater, sometimes less than the mean density 
 of its components, shewing that, at the in- 
 stant of their union, a diminution, or aug- 
 mentation of volume takes place. The re- 
 lation between the expansion of the separate 
 metals, and that of their alloys, has been in- 
 vestigated only in a very few cases. Alloys 
 containing a volatile metal are decomposed, 
 in whole or in part, at a strong heat. This 
 happens with those of arsenic, mercury, tel- 
 turium and zinc. Those that consist of two 
 differently fusible metals, may often be de- 
 composed, by exposing them to a tempera- 
 ture capable of melting only one of them. 
 This operation is called eliquation. It is 
 practised on the great scale to extract silver 
 from copper. The argentiferous copper is 
 melted with 3^ times its weight of lead ; 
 and the triple alloy is exposed to a sufficient 
 heat. The lead carries off the silver in its 
 fusion, and leaves the copper under the form 
 of a spongy lump. The silver is afterwards 
 recovered from the lead by another operation. 
 
 Some alloys oxidize more readily by heat 
 and air, than when the metals are separately 
 treated. Thus 3 of lead, and 1 of tin, at 
 a dull red, burn visibly, and are almost in- 
 stantly oxidized. Each by itself in the same 
 circumstances, would oxidize slowly, and 
 without the disengagement of light. 
 
 The formation of an alloy must be regu- 
 lated by the nature of the particular metals ; 
 to which therefore we refer. 
 
 The degree of affinitv between metals may 
 be in some measure estimated by the greater 
 or less facility with which, when of different 
 degrees of fusibility or volatility, they unite, 
 or with which they can after union he se- 
 parated by heat. The greater or less ten- 
 dency to separate into different proportional 
 alloys, by long continued fusion, may also 
 give some information on this subject. Mr 
 Hatchett remarked, in his admirable re- 
 searches on metallic alloys, that gold made 
 standard with the usual precautions by sil- 
 ver. copper, lead, antimony, Ac. and then 
 
ALL 
 
 ALM 
 
 cast into vertical bars, was by no means a 
 uniform compound ; but that the top of the 
 bar, corresponding to the metal at the hot* 
 tom of the crucible, contained the larger 
 proportion of gold. Hence, for thorough 
 combination, two red-hot crucibles should be 
 employed ; and the liquefied metals should 
 be alternately poured from the one into the 
 other. And to prevent unnecessary oxidize- 
 ment by exposure to air, the crucibles should 
 contain, besides the metal, a mixture of com- 
 mon salt and pounded charcoal. The melt- 
 ed alloy should also be occasionally stirred 
 up with a rod of pottery. 
 
 The most direct evidence of a chemical 
 change having taken place in the two metals 
 by combination, is when the alloy melts at a 
 much lower temperature than the fusing 
 points of its components. Iron which is 
 nearly infusible, when alloyed with gold, ac- 
 quires almost the fusibility of this metal. 
 Tin and lead form solder, an alloy more fusi- 
 ble than either of its components ; but the 
 triple compound of tin, lead, and bismuth, is 
 most remarkable on this account. The ana- 
 logy is here strong, with the increase of 
 solubility, which salts acquire by mixture, as is 
 exemplified in the uncrystallizable residue of 
 saline solutions, or mother waters, as they are 
 called. Sometimes two metals will not di- 
 rectly unite, which yet, by the intervention 
 of a third, are made to combine. This hap- 
 pens with mercury and iron, as has been 
 shewn by Messrs Aikin, who effected this 
 difficult amalgamation by previously uniting 
 the iron to tin or zinc. 
 
 The tenacity of alloys is generally, though 
 not always, inferior to the mean of the se- 
 parate metals. One part of lead will de- 
 stroy the compactness and tenacity of a 
 thousand of gold. Brass, made with a small 
 proportion of zinc, is more ductile than cop- 
 per itself ; but when one-third of zinc enters 
 into its composition, it becomes brittle. 
 
 In common cases, the specific gravity af- 
 fords a good criterion whereby to judge of 
 the proportion in an alloy, consisting of two 
 metals of different densities. But a very 
 fallacious rule has been given in some re- 
 spectable works, for comparing the specific 
 gravity that should result from given quan- 
 tities of two metals of known densities al- 
 loyed together, supposing no chemical pene- 
 tration or expansion of volume to take 
 place. Thus it has been taught, that if 
 gold and copper be united in equal weights, 
 the computed or mathematical specific gra- 
 vity of the alloy is the arithmetical mean of 
 the two specific gravities. This error was 
 pointed out by me in a paper published 
 in the 7 th number of the Journal of Science 
 and the Arts; and the correct rule was at 
 the same time given. The details belong to 
 the article Specific Gravity ; but the rule 
 merits a place here. The specific gravity of 
 
 the alloy is found by dividing the sum of the 
 weights by the sum of the volumes, compar- 
 ed to water, reckoned unity. Or in another 
 form, the rule may be stated thus : Multiply 
 the sum of the weights into the product of 
 the two specific gravities for a numerator, 
 and multiply each specific gravity into the 
 weight cf the other body, and add the two 
 products together for a denominator. The 
 quotient obtained by dividing the numerator 
 by the denominator, is the true computed 
 mean specific gravity ; and that found by 
 experiment, being compared with it, will shew 
 whether expansion or condensation of volume 
 has attended the chemical combination. Gold 
 having a specific gravity of 1 9.36', and cop- 
 per of 8.87, being alloyed in equal weights, 
 give on the fallacious rule of the arithmeti- 
 
 i a 19.36 4- 8.87 
 
 cal mean of the densities, ! =r 
 
 2 
 
 14.11 ; whereas the rightly calculated mean 
 specific gravity is only 12.16. It is evident, 
 that by comparing the former number with 
 chemical experiment, we should be led to in- 
 fer a prodigious condensation of volume be- 
 yond what really occurs. 
 
 A circumstance was observed by Mr 
 Hatchett to influence the density of metals, 
 which a priori might be thought unimport- 
 ant. When a bar of gold was cast in a ver- 
 tical position, the density of the metal at the 
 lower end of the bar was greater than that 
 of the top, in the proportion of 1 7.364 to 
 17.035. Are we to infer that melted metal 
 is a compressible fluid, or rather, that parti- 
 cles passing into the solid state under pres- 
 sure, exert their cohesive attraction with ad- 
 ventitious strength? Under the title metal , a 
 tabular view of metallic combinations will be 
 found, and under that of the particular 
 metal, the requisite information about its alloys. 
 
 Alluvial Formations, in geology, are re- 
 cent deposites in valleys or in plains, of the 
 detritus of the neighbouring mountains. 
 Gravel, loam, clay, sand, brown coal, wood 
 coal, bog iron ore, and calc tuff, compose 
 the alluvial deposites. The gravel and sand 
 sometimes contain gold and tin, if the ores 
 exist in the adjoining mountains. Petrified 
 wood and animal skeletons are found in the 
 alluvial clavs and sand.* 
 
 V 
 
 Almonds. Almonds consist chiefly of 
 an oil of the nature of fat oils, together 
 with farinaceous matter. The oil is so plen- 
 tiful, and so loosely combined or mixed 
 with the other principles, that it is obtained 
 by simple pressure, and part of it may be 
 squeezed out with the fingers. Five pounds 
 and a half have yielded one pound six ounces 
 of oil by cold expression, and three quarters 
 of a pound more on heating them. There 
 are two kinds of almonds, the sweet and 
 bitter. The bitter almonds yield an oil as 
 tasteless as that of the other, all the bitter 
 matter remaining in the cuke after the ex- 
 
ALO 
 
 ALU 
 
 pression. Great part of the bitter matter 
 dissolves by digestion, both in watery and 
 spirituous liquors ; and part arises with both 
 in distillation. Rember obtained from them 
 l-3d of watery extract, and 3-32ds of spiri- 
 tuous. Bitter almonds are poisonous to 
 birds, and to some animals. A water dis- 
 tilled from them, when made of a certain 
 degree of strength, has been found from ex- 
 periment to be poisonous to brutes ; and 
 there are instances of cordial spirits impreg- 
 nated with them being poisonous to men. 
 It seems, indeed, that the vegetable principle 
 of bitterness in almonds and the kernels of 
 other fruits, is destructive to animal life, 
 when separated by distillation from the oil 
 and farinaceous matter. The distilled wa- 
 ter from laurel leaves appears to be of this 
 nature, and its poisonous effects are well 
 known. 
 
 Sweet almonds arc made into an emulsion 
 by trituration with water, which on standing 
 separates a thick cream floating on the top. 
 The emulsion may be curdled by heat, or 
 the addition of alcohol or acids. The whey 
 contains gum, extractive matter, and sugar, 
 according to Professor Proust ; and the 
 curd, when washed and dried, yields oil by 
 expression, and afterward by distillation the 
 same products as cheese. The whey is a 
 good diluent. 
 
 * Prussic or hydrocyanic acid is the dele- 
 terious ingredient in bitter almonds. The 
 best remedy after emetics is a combination 
 of sulphate of iron with bicarbonate of po- 
 tash. * 
 
 Aloes. This is a bitter juice, extracted 
 from the leaves of a plant of the same name. 
 Three sorts of aloes are distinguished in the 
 shops by the names of aloe soccotrina, aloe 
 hepatica, and aloe caballina. The first de- 
 nomination, which is applied to the purest 
 kind, is taken from the island of Zocotora ; 
 the second, or next in quality, is called hepa- 
 tica, from its liver colour ; and the third, 
 caballina, from the use of this species being 
 confined to horses. These kinds of aloes 
 are said to differ only in purity, though, from 
 the difference of their flavours, it is probable 
 that they may be obtained in some instances 
 from different species of the same plant. It 
 is certain, however, that the different kinds 
 are all prepared at Morviedro in Spain, from 
 the same leaves of the common aloe. Deep 
 incisions are made in the leaves, from which 
 the juice is suffered to flow ; and this, after 
 decantation from its sediment, and inspissa- 
 tion in the sun, is exposed to sale in leathern 
 bags by the name of soccotrine aloes. An 
 additional quantity of juice is obtained by 
 pressure from the leaves ; and this, when 
 decanted from its sediment and dried, is the 
 hepatic aloes. And lastly, a portion of juice 
 is obtained by strong pressure of the leaves, 
 and is mixed with the dregs of the two pre- 
 
 ceding kinds to form the caballine aloes. 
 The first kind is said to contain much less 
 resin. The principal characters of good aloes 
 are these : it must be glossy, not very black, 
 but brown ; when rubbed or cut, of a yellow 
 colour ; compact, but easy to break ; easily 
 soluble ; of an unpleasant peculiar smell, 
 which cannot be described, and an extremely 
 bitter taste. 
 
 Aloes appears to be an intimate combina- 
 tion of gummy resinous matter, so well 
 blended together, that watery or spirituous 
 solvents, separately applied, dissolve the 
 greater part of both. It is not determined 
 whether there be any difference in the medi- 
 cal properties of these solutions. Both are 
 purgative, as is likewise the aloes in sub- 
 stance ; and, if used too freely, are apt to 
 prove heating, and produce hemorrhoidal 
 complaints. 
 
 * Braconnot imagines he has detected in 
 aloes a peculiar principle, similar to the bit- 
 ter resinous which Vauquelin has found in 
 many febrifuge barks. The recent juice of 
 the leaves absorbs oxygen, and becomes a 
 fine reddish purple pigment.* 
 
 Aludel. The process of sublimation 
 differs from distillation in the nature of its 
 product, which, instead of becoming con- 
 densed in a fluid, assumes the solid state, 
 and the form of the receivers may of course 
 be very different. The receivers for subli- 
 mates are of the nature of chimneys, in 
 which the elastic products are condensed, 
 and adhere to their internal surface. It is 
 evident that the head of an alembic will 
 serve very well to receive and condense such 
 sublimates as are not veiy volatile. The 
 earlier chemists, whose notions of simplicity 
 were not always the most perfect, thought 
 proper to use a number of similar heads, 
 one above the other, communicating in suc- 
 cession by means of a perforation in the 
 superior part of each, which received the 
 neck of the capital immediately above it. 
 These heads differing in no respect from the 
 usual heads of alembics, excepting in their 
 having no nose or beak, and in the other 
 circumstances here mentioned, were called 
 aludels. They are seldom now to be seen 
 in chemical laboratories, because the opera- 
 tions of this art may be performed with 
 greater simplicity of instruments, provided 
 attention be paid to the heat and other cir- 
 cumstances. 
 
 * Alum. See Alumina, Sulphate of.* 
 
 * Alum- Earth. A massive mineral, of a 
 blackish brown colour, a dull lustre, an 
 earthy and somewhat slaty fracture, sectile, 
 and rather soft. By Klaproth’s analysis it 
 contains, charcoal 19.65, silica 40, alumina 
 16, oxide of iron 6.4, sulphur 2.84, sulphates 
 of lime and potash each 1.5, sulphate ot iron 
 1 . 8, magnesia and muriate of potash 0.5, ami 
 water 10.75. 
 
 o 
 
ALU 
 
 ALU 
 
 • Alum-slate. 1 . Common. This mine- 
 ral occurs both massive and in insulated 
 .balls, of a greyish black colour, dull lustre, 
 straight slaty fracture, tabular fragments, 
 streak coloured like itself ; though soft, it is 
 not very brittle. Effloresces, acquiring the 
 taste of alum. 
 
 2. Glossy Alum-slate. A massive mine- 
 ral of a bluish black colour. The rents dis- 
 play a variety of lively purple tints. It has 
 a semi-metallic lustre in the fracture, which 
 is straight, slaty, or undulating. There is a 
 soft variety of it approaching in appearance 
 to slate clay. By exposure to air its thick- 
 ness is prodigiously augmented by the for- 
 mation of a saline efflorescence, which sepa- 
 rates its thinnest plates. These afterwards 
 exfoliate in brittle sections, causing entire 
 disintegration.* 
 
 * Alumina. One of the primitive earths, 
 which, as constituting the plastic principle of 
 all clays, loams and boles, was called argil 
 or the argillaceous earth, but now, as being 
 obtained in greatest purity from alum, is 
 styled alumina. It was deemed elementary 
 matter till Sir H. Davy’s celebrated electro- 
 chemical researches led to the belief of its 
 being, like barytes and lime, a metallic 
 oxide. 
 
 The purest native alumina is found in the 
 oriental gems, the sapphire and ruby. They 
 consist of nothing but this earth, and a small 
 portion of colouring matter. The native 
 porcelain clays or kaolins, however white 
 and soft, can never be regarded as pure alu- 
 mina. They usually contain fully half their 
 weight of silica, and frequently other earths. 
 To obtain pure alumina we dissolve alum in 
 20 times its weight of water, and add to it a 
 little of the solution of carbonate of soda, to 
 throw down any iron which may be present. 
 AVe then drop the supernatant liquid into a 
 quantity of the water of ammonia, taking 
 care not to add so much of the aluminous 
 solution as will saturate the ammonia. The 
 volatile alkali unites with the sulphuric acid 
 of the alum, and the earthy basis of the lat- 
 ter is separated in a white spongy precipi- 
 tate. This must be thrown on a filter, 
 washed, or edulcorated as the old chemists 
 expressed it, by repeated affusions of water, 
 and then dried. Or if an alum, made with 
 ammonia instead of potash, as is the case 
 with some French alums, can be got, simple 
 ignition dissipates its acid and alkaline 
 constituents, leaving pure alumina. 
 
 Alumina prepared by the first process is 
 white, pulverulent, soft to the touch, adheres 
 to the tongue, forms a smooth paste without 
 grittiness in the mouth, insipid, inodorous, 
 produces no change in vegetable colours, in- 
 soluble in water, but mixes with it readily in 
 every proportion, and retains a small quan- 
 tity with considerable force j is infusible in 
 the strongest heat ol a furnace, experiencing 
 
 merely a condensation of volume and conse- 
 quent hardness, but is in small quantities 
 melted by the oxy-hydrogen blow-pipe. Its 
 specific gravity is 2.000, in the state of pow- 
 der, hut by ignition it is augmented. 
 
 Every analogy leads to the belief that 
 alumina contains a peculiar metal, which 
 may be called aluminum. The first evi- 
 dences obtained of this position are present- 
 ed in Sir II. Davy’s researches. Iron ne- 
 gatively electrified by a very high power be- 
 ing fused in contact with pure alumina, 
 formed a globule whiter than pure iron, 
 which effervesced slowly in water, becoming 
 covered with a white powder. The solution 
 of this in muriatic acid, decomposed by an 
 alkali, afforded alumina and oxide of iron. 
 By passing potassium in vapour through alu- 
 mina heated to whiteness, the greatest part 
 of the potassium became converted into pot- 
 ash, which formed a coherent mass with that 
 part of the alumina not decompounded ; and 
 in this mass there were numerous grey par- 
 ticles, having the metallic lustre, and which 
 became white when heated in theair, and which 
 slowly effervesced in water. In a similar ex- 
 periment made by the same illustrious che- 
 mist, a strong red heat only being applied to 
 the alumina, a mass was obtained, which 
 took fire spontaneously by exposure to air, 
 and which effervesced violently in water. 
 This mass was probably an alloy of aluminum 
 and potassium. The conversion of potassium 
 into its deutoxide, dry potash, by alumina, 
 proves the presence of oxygen in the latter. 
 AVhen regarded as an oxide, Sir II. Davy 
 estimates its oxvgen and basis to be to one 
 another as 15 to 33 ; or as 10 to 22. The 
 prime equivalent of alumina would thus ap- 
 pear to be 1.0 — J— 2.2 = 3.2. 
 
 But Berzelius’s analysis of sulphate of alu- 
 mina seems to indicate 2.136 as the quantity 
 of the earth which combines with 5. of the 
 acid. Hence aluminum will come to be re- 
 presented by 2.1 36 — 1 . = ] . 1 36. But we 
 shall presently shew that his analysis, both 
 of alum and sulphate of alumina, may be 
 reconciled to Sir H. Davy’s equivalent 
 prime = 3.2. That of aluminum will be- 
 come of course 2.2. 
 
 Alumina which has lost its plasticity by 
 ignition, recovers it by being dissolved in an 
 acid or alkaline menstruum, and then preci- 
 pitated. In this state it is called a hydrate, 
 for when dried in a steam-heat it retains 
 much water ; and therefore resembles in 
 composition wavellite, a beautiful mineral, 
 consisting almost entirely of alumina, with 
 about 28 per cent of water. Alumina is 
 widely diffused in nature. It is a constitu- 
 ent of every soil, and of almost every rock. 
 It is the basis of porcelain, pottery, bricks, 
 and crucibles. Its affinity for vegetable co- 
 louring matter, is made use of in the prepa- 
 ration of lakes, and in the arts of dveing and 
 
ALU 
 
 ALU 
 
 calico printing. Native combinations of alu- 
 mina, constitute the fuller’s earth, ochres, 
 boles, pipe-clays, &c. * 
 
 * Alumina, (Salts of). 
 
 These salts have the following general 
 characters : 
 
 1. Most of them are very soluble in 
 water, and their solutions have a sweetish 
 acerb taste. 
 
 2. Ammonia throws down their earthy 
 base, even though they have been previously 
 acidulated with muriatic acid. 
 
 3. At a strong red heat they give out a 
 portion of their acid. 
 
 4. Phosphate of ammonia gives a white 
 precipitate. 
 
 5. Hydriodate of potash produces a floc- 
 culent precipitate of a white colour, passing 
 into a permanent yellow. 
 
 6. They are not affected by oxalate of 
 ammonia, tartaric acid, ferroprussiate of pot- 
 ash, or tincture of galls ; by the first two 
 tests they are distinguishable from yttria, 
 and by the last two from that earth and glu- 
 cina. 
 
 7. If bisulphate of potash be added to a 
 solution of an aluminous salt, moderately 
 concentrated, octahedral crystals of alum will 
 form. 
 
 Acetate of Alumina. By digesting strong 
 acetic acid on newly precipitated alumi- 
 na, this saline combination can be direct- 
 ly formed. Vinegar of ordinary strength 
 scarcely acts on the earth. But the salt is 
 seldom made in this way. It is prepared in 
 large quantities for the calico printers, by 
 decomposing alum with acetate of lead ; or 
 more economically with aqueous acetate 
 of lime, having a specific gravity of about 
 1.050; a gallon of which, equivalent to 
 nearly half a pound avoirdupois of dry acetic 
 acid, is employed for every 2j lb. of alum. 
 A sulphate of lime is formed by complex 
 affinity, which precipitates, and an acetate of 
 alumina floats above. The above proportion 
 of alum is much beyond the equivalent 
 quantity ; and the specific gravity of the 
 liquid is consequently raised by the excess of 
 salt. It is usually 1 . 080. By careful evapora- 
 tion capillary crystals are formed, which readily 
 deliquesce. M. Gay Lussae made some curi- 
 ous observations on the solutions of this salt. 
 15 ven when made with cold saturated solu- 
 tions of alum and acetate of lead, and conse- 
 quently but little concentrated, it becomes 
 turbid when heated to 1 22° Fahr. ; and at 
 a boiling heat a precipitate falls of about 
 one-half of the whole salt. On cooling, it is 
 redissolved, This decomposition by heat, 
 which would be prejudicial to the calico 
 printer, is prevented by the excess of alum, 
 which is properly used in actual practice. 
 M. Gay Lussae thinks this phenomenon has 
 considerable analogy with the coagulation of 
 
 albumen by heat ; the particles of the water, 
 and of the solid matter, being carried by the 
 heat out of their sphere of activity, separate. 
 It is probably a subacetate which falls down, 
 as well as that which is obtained by drying 
 the crystals. Wenzel’s analysis of acetate of 
 alumina gives 73.81 acid to 26.19 base in 
 100 parts. If we suppose it to consist, like 
 the sulphate, of three primes of acid to two 
 of alumina, we shall have for its equivalent 
 proportions, 20 of dry acid -[-6.4 earth, or 
 
 75.8 -J- 24.2 = 100, As alum contains, in 
 round numbers, about l-9th of earthy base, 
 8 oz. of real acetic acid present in the gallon 
 of the redistilled pyrolignous, would require 
 about 2 jibs, of alum, for exact decomposition. 
 The excess employed is found to be useful. 
 
 The affinity between the constituents 
 of this salt is very feeble. Hence the at- 
 traction of cotton fibre for alumina, aided 
 by a moderate heat, is sufficient to decom- 
 pose it. 
 
 The following salts of alumina are in- 
 soluble in water: — -Arseniate, borate, phos- 
 phate, tungstate, mellate, saclactate, lithate, 
 malate, camphorate. Tho oxalate is uncrys- 
 tallizable. It consists of 56 acid and water, 
 and 44 alumina. The tartrate does not 
 crystallize. But the tartrate of potash and 
 alumina is remarkable, according to The- 
 nard, for yielding no precipitate, either by 
 alkalis or alkaline carbonates. The super- 
 gallate crystallizes. There seems to be no 
 dry carbonate. A supernitrate exists very 
 difficult to crystallize. Its specific gravity is 
 1.645. A moderate heat drives off the acid. 
 The muriate is easily made by digesting mu- 
 riatic acid on gelatinous alumina. It is 
 colourless, astringent, deliquescent, uncrystal- 
 lizable, reddens turnsole, and forms a gelatin- 
 ous mass by evaporation. Alcohol dissolves 
 at 60° half its weight of this salt. A dull 
 red heat separates the acid from the alumi- 
 na. Its composition is, according to Bucholz, 
 
 29.8 acid, 30.0 base, 40,2 water, in 10O 
 parts. 
 
 Sulphate of alumina exists under several 
 modifications. The simple sulphate is easily 
 made, by digesting sulphuric acid on pure 
 clay. The salt thus formed crystallizes in 
 thin soft plates, having a pearly lustre. It 
 has an astringent taste, and is so soluble in 
 waiter as to crystallize with difficulty. When 
 moderately heated the water escapes, and, 
 at a higher temperature, the acid. Berzelius 
 has chosen this salt for the purpose of de- 
 termining the equivalent of alumina. He 
 considers the dry sulphate as a compound ot 
 100 parts of sulphuric acid with 42.722 
 earth. This makes the equi valent 21.861, 
 oxygen being reckoned 10, if wc consider it 
 a compound of a prime proportion of each. 
 But if we regard it as consisting of 3 of 
 acid and 2 of base, we shall have 3*.Q for 
 
£ 
 
 ALU 
 
 ALU 
 
 li 
 
 the prime equivalent of alumina. The rea- 
 son for preferring this number will appear 
 in treating of the next salt.* 
 
 * Alum, This important salt has been 
 the object of innumerable researches, both 
 with regard to its fabrication and composi- 
 tion.* It is produced, but in a very small quan- 
 tity, in the native state ; and this is mixed 
 with heterogeneous matters. It effloresces 
 in various forms upon ores during calcina- 
 tion, but it seldom occurs crystallized. The 
 greater part of this salt is factitious, being 
 extracted from various minerals called alum 
 ores, such as, 1. Sulphurated clay. This 
 constitutes the purest of all aluminous ores, 
 namely, that of la Tolfa, near Civita Veechia, 
 in Italy. It is white, compact, and as hard 
 as indurated clay, whence it is called petra 
 nluminaris » It is tasteless and mealy ; one 
 
 hundred parts of this ore contain above forty 
 of sulphur and fifty of clay, a small quantity 
 of potash, and a little iron. Bergman says 
 it contains forty-three of sulphur in one hun- 
 dred, thirty-five of clay, and twenty-two of 
 siliceous earth. This ore is first torrefied to 
 acidify the sulphur, which then acts on the 
 clay, and forms the alum. 
 
 2. The pyritaceous clay, which is found 
 at Schwemsal, in Saxony, at the depth of 
 ten or twelve feet. It is a black and hard, 
 but brittle substance, consisting of clay, py- 
 rites, and bitumen. It is exposed to the air 
 for two years ; by which means the pyrites 
 are decomposed, and the alum is formed. 
 The alum ores of Hesse and Liege are of 
 this kind ; but they are first torrefied, which 
 is said to be a disadvantageous method. 
 
 3. The schistus aluminaris contains a vari- 
 able proportion of petroleum and pyrites in- 
 timately mixed with it. When the last are 
 in a very large quantity, this ore is rejected 
 as containing too much iron. Professor 
 Bergman very properly suggested, that by 
 adding a proportion of clay, this ore may 
 turn out advantageously for producing alum. 
 But if the petrol be considerable, it must be 
 torrefied. The mines of Becket in Nor- 
 mandy, and those of Whitby in Yorkshire, 
 are of this species. 
 
 4. Volcanic aluminous ore. Such is that 
 of Solfaterra near Naples. It is in the form 
 of a white saline earth, after it has efflo- 
 resced in the air ; or else it is in a stony form, 
 
 5. Bituminous alum ore is called shale, 
 and is in the form of a shistus, impregnated 
 with so much oily matter, or bitumen, as to 
 be inflammable. It is found in Sweden, and 
 also in the coal mines at Whitehaven, and 
 elsewhere. 
 
 Chaptal has fabricated alum on a large 
 scale from its component parts. For this 
 purpose he constructed a chamber 91 feet 
 long, 48 wide, and 31 high in the middle. 
 The walls are of common masonry, lined 
 
 with a pretty thick coating of plaster. The 
 floor is paved with bricks, bedded in a mix- 
 ture of raw and burnt clay ; and this pave- 
 ment is covered with another, the joints of 
 which overlap those of the first, and instead 
 of mortar the bricks are joined with a ce- 
 ment of equal parts of pitch, turpentine, and 
 wax, which, after having been boiled till it 
 ceases to swell, is used hot. The roof is of 
 wood, but the beams are very close together, 
 and grooved lengthwise, the intermediate 
 space being filled up by planks fitted into 
 the grooves, so that the whole is put toge- 
 ther without a nail. Lastly, the whole of the 
 inside is covered with three or four succes- 
 sive coatings of the cement above mention- 
 ed, the first being laid on as hot as possible ; 
 and the outside of the wooden roof was var- 
 nished in the same manner. The purest and 
 whitest clay being made into a paste with 
 w'ater, and formed into balls half a foot in 
 diameter, these are calcined in a furnace, 
 broken to pieces, and a stratum of the frag- 
 ments laid on the floor. A due proportion 
 of sulphur is then ignited in the chamber, in 
 the same manner as for the fabrication of sul- 
 phuric acid ; and the fragments of burnt clay, 
 imbibing this as it forms, begin after a few 
 days to crack and open, and exhibit an efllo- 
 rescence of sulphate of alumina. When the 
 earth has completely effloresced, it is taken 
 out of the chamber, exposed for some time 
 in an open shed, that it may be the more in- 
 timately penetrated by the acid, and is then 
 lixiviated and crystallized in the usual man- 
 ner. The cement answers the purpose of 
 lead on this occasion very effectually, and 
 according to M. Chaptal, costs no more than 
 lead would at three farthings a-pound. 
 
 Curaudau has lately recommended a pro- 
 cess for making alum without evaporation. 
 One hundred parts of clay and five of mu- 
 riate of soda are kneaded into a paste with 
 water, and formed into loaves. With these 
 a reverberatory furnace is filled, and a brisk 
 fire is kept up for two hours. Being pow- 
 dered, and put into a sound cask, one-fourth 
 of their weight of sulphuric acid is poured 
 over them by degrees, stirring the mixture 
 well at each addition. As soon as the mu- 
 riatic gas is dissipated, a quantity of water 
 equal to the acid is added, and the mixture 
 stirred as before. When the heat is abated, 
 a little more water is poured in, and this is 
 repeated till eight or ten times as much wa- 
 ter as there w^as acid is added. When the 
 whole has settled, the clear liquor is drawn 
 off into leaden vessels, and a quantity of wa- 
 ter equal to this liquor is poured on the sedi- 
 ment. The tw'o liquors being mixed, a so- 
 lution of potash is added to them, the alkali 
 in which is equal to one-fourth of the weight 
 of the sulphuric acid. Sulphate of potash 
 may be used, but twice as much of this as of 
 
ALU 
 
 ALU 
 
 the alkali is necessary. After a certain 
 time the liquor by cooling affords crystals of 
 alum equal to three times the weight of the 
 acid used. It is refined by dissolving it in 
 the smallest possible quantity of boiling wa- 
 ter. T he residue may be washed with more 
 water, to be employed in lixiviating a fresh 
 portion of the ingredients. 
 
 As the mother water still contains alum, 
 with sulphate of iron very much oxided, it 
 is well adapted to the fabrication of prussian 
 blue. This mode of making alum is parti- 
 cularly advantageous to the manufacturers 
 of prussian blue, as they may calcine their 
 clay at the same time with their animal 
 matters, without additional expense ; they 
 will have no need in this case to add potash ; 
 and the presence of iron, instead of being 
 injurious, will be very useful. If they wish- 
 ed to make alum for sale, they might use the 
 solution of sulphate of potash arising from 
 the washing of their prussian blue, instead of 
 water, to dissolve the combination of alumina 
 and sulphuric acid. 
 
 The residuums of distillers of aquafortis 
 are applicable to the same purposes, as they 
 contain the alumina and potash requisite, 
 and only require to be reduced to powder, 
 sprinkled with sulphuric acid, and lixiviated 
 with water, in the manner directed above. The 
 mother waters of these alums are also useful 
 in the fabrication of prussian blue. As the 
 residuum of aquafortis contains an over-pro- 
 portion of potash, it will be found of advan- 
 tage to add an eighth of its weight of clay 
 calcined as above. 
 
 * The most extensive alum manufactory in 
 Great Britain is at Hurlett, near Paisley, on 
 the estate of the Earl of Glasgow. The 
 next in magnitude is at Whitby ; of whose 
 state and processes an instructive account was 
 published by Mr Winter, in the 25th vo- 
 lume of Nicholson’s Journal. The stratum 
 of aluminous schistus is about 29 miles in 
 width, and it is covered by strata of alluvial 
 soil, sandstone, ironstone, shell, and clay. 
 The alum schist is generally found disposed 
 in horizontal laminae. The upper part of 
 the rock is the most abundant in sulphur; so 
 that a cubic yard taken from the top of the 
 stratum, is 5 times more valuable than the 
 same bulk, 100 feet below. 
 
 If a quantity of the schistus be laid in a heap, 
 and moistened with sea water, it will take 
 fire spontaneously, and will continue to burn 
 till the whole inflammable matter be con- 
 sumed. Its colour is bluish gray. Its sp. 
 gravity is 2,48. It imparts a bituminous 
 principle to alcohol. Fused with an alkali, 
 muriatic acid precipitates a large proportion 
 of silex. 
 
 The expense of digging and removing to 
 a distance of 200 yards one cubic yard of the 
 schistose rock, is about sixpence-halfpenny. 
 A man can cam from 2s. u'd. to 8s. a-day. 
 
 The rock, broken into small pieces, is laid 
 on a horizontal bed of fuel, composed of 
 brushwood, &c. When about 4 feet in 
 height of the rock is piled on, fire is set to 
 the bottom, and fresh rock continually pour- 
 ed upon the pile. This is continued until 
 the calcined heap be raised to the height of 
 90 or 100 feet. Its horizontal area has also 
 been progressively extended at the same 
 time, till it forms a great bed nearly 200 
 feet square, having about 100,000 yards of 
 solid measurement. The rapidity of the 
 combustion is allayed by plastering lip the 
 crevices with small schist moistened. Not- 
 withstanding of tins precaution, a great deal 
 of sulphuric or sulphurous acid is dissipat- 
 ed. 150 tons of calcined schist produce on 
 an average 1 ton of alum. This result has 
 been deduced from an average of 1 50,000 tons. 
 
 'Fhe calcined mineral is digested in water 
 contained in pits that usually contain about 
 GO cubic yards. The liquid is drawn off 
 into cisterns, and afterwards pumped up 
 again upon fresh calcined mine. This is re- 
 peated until the specific gravity becomes 
 1.15. The half exhausted schist is then co- 
 vered with water, to take up the whole solu- 
 ble matter. The strong liquor is drawn off 
 into settling cisterns, where the sulphate of 
 lime, iron, and earth, are deposited. At 
 some works the liquid is boiled, which aids 
 its purification. It is then run into leaden 
 pans 10 feet long, 4 feet 9 inches wide, 2 
 feet 2 inches deep at the one end, and 2 feet 
 8 inches at the other. This slope makes 
 them be easily emptied. Here the liquor 
 is concentrated at a boiling heat. Every 
 morning the pans are emptied into a settling 
 cistern, and a solution of muriate of potash, 
 either pretty pure from the manufacturer, or 
 crude and compound from the soap-boiler, is 
 added. The quantity of muriate necessary 
 is determined by a previous experiment in a 
 basin, and is regulated for the workmen by 
 the hydrometer. By this addition the pan 
 liquor, which had acquired a specific gra- 
 vity of 1.4 or 1.5, is reduced to 1.55. After 
 beine: allowed to settle for two hours, it is 
 run off into the coolers to be crystallized. 
 At a greater sp. gravity than 1.35, the li- 
 quor, instead of crystallizing, would, when it 
 cools, present us with a solid magma, resem- 
 bling grease. Urine is occasionally added, 
 to bring it down to the proper density. 
 
 After standing 4 days, the mother waters 
 are drained off, to be pumped into the pans 
 on the succeeding day. The crystals of 
 alum arc washed in a tub, and drained. 
 They are then put into a lead pan, with as 
 much water as will make a saturated solu- 
 tion at the boiling point. Whenever this is 
 effected, the solution is run off into casks. 
 At the end of JO or 16 days, the casks arc 
 unhooped and taken asunder. I he alutn » 
 found exteriorly in a solid cake, but in th«J 
 
ALU 
 
 ALU 
 
 interior cavity, in large pyramidal crystals, 
 consisting of octahedrons, inserted succes- 
 sively into one another. This last pro- 
 cess is called roching. Mr Winter says, 
 that 22 tons of muriate of potash will pro- 
 duce 100 tons of alum, to which 31 tons of 
 the black ashes of the soap-boiler, or 73 ot 
 kelp, are equivalent. Where much iron 
 exists in the alum ore, the alkaline muriate, 
 by its decomposition, gives birth to an un- 
 crystallizable muriate of iron. The alum ma- 
 nufactured in the preceding mode is a super- 
 sulphate of alumina and potash. There is 
 another alum which exactly resembles it. 
 This is a supersulphate of alumina and am- 
 monia. Both crystallize in regular octahe- 
 drons, formed by two four-sided pyramids 
 joined base to base. Alum has an astringent - 
 sweetish taste. Its sp. gravity is about 1.71. 
 
 It reddens the vegetable blues. It is solu- 
 ble in 16 parts of water at 60°, and in ^ths 
 of its weight at 212°. It effloresces superfi- 
 cially on exposure to air, but the interior re- 
 mains long unchanged. Its water of crys- 
 tallization is sufficient at a gentle heat to fuse 
 it. If the heat be increased it froths up, 
 and loses fully 45 per cent of its weight in 
 water. The spongy residue is called burnt 
 or calcined alum, and is used by surgeons as 
 a mild escharotic. A violent heat separates 
 a great portion of its acid. 
 
 Alum thus was analyzed by Berzelius : 
 ls£, 20 parts (grammes) of pure alum lost by 
 the heat of a spirit lamp 9 parts, which 
 gives 45 per cent of water. The dry salt 
 was dissolved in water, and its acid precipi- 
 tated by muriate of barytes ; the sulphate of 
 which, obtained after ignition, weighed 20 
 parts; indicating in 100 parts 34.5 of dry 
 sulphuric acid. 2 d, Ten parts of alum were 
 dissolved in water, and digested with an ex- 
 cess of ammonia. Alumina, well washed 
 and burnt, equivalent to 10.67 per cent, was 
 obtained. In another experiment, 10. SC 
 per cent resulted. 3d, Ten parts of alum dis- 
 solved in water, were digested with carbo- 
 nate of strontites, till the earth was com- 
 pletely separated. The sulphate of potash, 
 alter ignition, weighed 1.815, corresponding 
 to 0.981 potash, or in 100 parts to 9.81. 
 
 Alum, therefore, consists of 
 
 Sulphuric acid, 54.53 
 Alumina, 10.86 
 
 Potash, 9.81 
 
 Water, 45.00 
 
 1 00.00 
 
 or, Sulphate of alumina, 36.85 
 Sulphate of potash, 18.15 
 
 Water, - 45.00 
 
 100.00 
 
 Thenard’s analysis, Ann. de Chimie, vol. 
 59. or Nicholson’s Journal, vol. 18. coincides 
 
 perfectly with that of Berzelius in the pro- 
 duct of sulphate of barytes. From 490 parts 
 of alum, he obtained 490 of the ignited ba- 
 rytic salt; but the alumina was in greater 
 proportion, equal to 1 2.54 per cent, and the 
 sulphate of potash less, or 15.7 in 100 parts. 
 
 l)r Thomson considers it as a compound 
 of 5 atoms sulphate of alumina, 1 atom sul- 
 phate of potash, and 25 atoms water, as fol- 
 lows : Sulphate of alumina, 36.70 
 Sulphate of potash, 18.88 
 Water, - 44.42 
 
 100.00 
 
 But Vauquelin, in his last analysis, found 
 48.58 water ; and by Thenard’s state- 
 ment there are indicated 54.23 dry acid, 
 
 7.14 potash, 
 
 12.54 alumina, 
 46.09 water, 
 
 100.C0 
 
 It deserves to be remarked, that the ana- 
 lysis of Professor Berzelius agrees with the 
 supposition that alum contains, 
 
 4 sulphuric acid, = 20.0 
 
 34.36 
 
 2 alumina, = 6.4 
 
 1 1.00 
 
 1 potash, *= 6.0 
 
 10.30 
 
 23 water, — 25.8 
 
 44.34 
 
 58.2 
 
 100.00 
 
 If we rectify Vauquelin’s erroneous esti- 
 mate of the sulphate of barytes, his analysis 
 will also coincide with the above. Alum, 
 therefore, differs from the simple sulphate of 
 alumina previously described, which consist- 
 ed of 3 prime equivalents of acid, and 2 of 
 earth, merely by its assumption of a prime of 
 sulphate of potash. It is probable that all 
 the aluminous salts have a similar constitu- 
 tion. It is to be observed, moreover, that 
 the number 34.36 resulting from the theo- 
 retic proportions, is, according to Gilbert’s 
 remarks on the essay of Berzelius, the just 
 representation of the dry acid in 100 of sul- 
 phate of barytes, by a corrected analysis, 
 which makes the prime of barytes 9.57. 
 
 Should ammonia be suspected in alum, 
 it may be detected, and its quantity estimat- 
 ed, by mixing quicklime with the saline so- 
 lution, and exposing the mixture to heat in 
 a retort, connected with a Woolfe’s appara- 
 tus. The water of ammonia being after- 
 wards saturated with an acid, and evaporat- 
 ed to a dry salt, will indicate the quantity of 
 pure ammonia in the alum. A variety of 
 alum, containing both potash and ammonia, 
 may also be found. This will occur where 
 urine has been used, as well as muriate of 
 potash, in its fabrication. If any of these 
 bisulphates of alumina and potash be acted 
 on in a watery solution, by gelatinous alu- 
 mina, a neutral triple salt is formed, which 
 precipitates in a nearly insoluble state. 
 
ALU 
 
 AMB 
 
 When alum in powder is mixed with 
 flour or sugar, and calcined, it forms the 
 pyrophorus of Homberg. 
 
 i\ir W inter first mentioned, that another 
 variety ot alum call be made with soda, in- 
 stead of potash. This salt, which crystal- 
 lizes in octahedrons, has been also made 
 with pure muriate of soda, and bisulphate of 
 alumina, at the laboratory of Hurlett, by Mr 
 W. \V ilson. It is extremely difficult to form, 
 and effloresces like the sulphate of soda. 
 
 The only injurious contamination of alum 
 is sulphate of iron. It is detected by fer- 
 roprussiate of potash. To get rid of it 
 cheaply, M. Thenard recommended dis- 
 solving the alum in boiling water, and 
 agitating the solution with rods as it cools. 
 The salt is thus reduced to a fine granular 
 powder, which being washed two or three 
 times with cold water, and drained, yields a 
 perfectly pure alum. For a very advanta- 
 geous mode of concentrating alum liquors, as 
 well as those of other salts, on the great 
 scale, see Eva po ratio x. 
 
 Oxyinuriate of alumina, or the chloride, 
 lias been proposed by Mr Wilson of Dublin 
 as preferable to solution of chlorine, for dis- 
 charging the turkey-red dye. He prepares 
 it by adding to a solution of oxy muriate of 
 lime, at a sp. gravity of 1.060, a solution of 
 alum of the sp. grav. 1. 100, as long as any 
 precipitate falls. The clear liquid is to be 
 drawn off from the precipitate, and kept in 
 close vessels. He says that it does not in- 
 jure the cloth, nor annoy the workmen, like 
 the liquor of uncombined chlorine. — Ann . 
 of' Phil. vol. viii. 4 
 
 Alum is used in large quantities in many 
 manufactories. W T hen added to tallow, it 
 renders it harder. Printers’ cushions, and 
 the blocks used in the calico manufactory, 
 are rubbed with burnt alum to remove any 
 greasiness, which might prevent the ink or 
 colour from sticking. Wood sufficiently 
 soaked in a solution of alum does not easily 
 take fire ; and the same is true of paper 
 impregnated with it, which is fitter to keep 
 gunpowder, as it also excludes moisture. 
 Paper impregnated with alum is useful in 
 whitening silver, and silvering brass without 
 heat. Alum mixed in milk helps the separa- 
 tion of its butter. If added in a very small 
 quantity to turbid water, in a few minutes 
 it renders it perfectly limpid, without any 
 bad taste or quality ; while the sulphuric 
 acid imparts to it a very sensible acidity, 
 and does not precipitate so soon, or so well, 
 the opaque earthy mixtures that render it 
 turbid, as I have often tried. It is used in 
 making pyrophorus, in tanning, and many 
 other manufactories, particularly in the art 
 of dyeing, in which it is of the greatest and 
 most important use, by cleansing and open- 
 ing the pores on the surface of the substance 
 
 to be dyed, rendering it fit for receiving the 
 colouring particles, (by which the alum is 
 generally decomposed), and at the same time 
 making the colour fixed. Crayons gene- 
 rally consist of the earth of alum, finely pow- 
 dered, and tinged for the purpose. In me- 
 dicine it is employed as an astringent. 
 
 * Aluminite. A mineral of a snow-white 
 colour, dull, opaque, and having a fine earthy 
 fracture. It has a glistening streak. It is 
 found in kidney-shaped pieces, which are 
 soft to the touch, and adhere slightly to the 
 tongue. Sp. gravity, 1.67. 
 
 It consists of sulphuric acid, 19.25 
 
 Alumina, 52.50 
 
 Water, 47.00 
 
 Silica, lime, and oxide of iron, 1.25 
 
 100.00 
 
 It may be represented very exactly by 
 2 primes of acid, 10 =20 
 
 5 alumina, 16 =32 
 
 21 water, 23.6 = 47.2 
 
 Foreign matter, 0.4 = O.S 
 
 50.0 100.0 
 
 The conversion of the above into alum is 
 easily explained. When the three primes 
 composing bisulphate of potash come into 
 play, they displace precisely three primes 
 (or atoms) of alumina. Two additional 
 primes of water are also introduced at the 
 same time, by the strong affinity of the bi- 
 sulphate for the particles of that liquid. 
 
 The above alum ore is found chiefly irt 
 the alluvial strata round Halle in Saxony. * 
 
 * Amadou. It is a variety of the boletus 
 igniarius , found on old ash and other trees. 
 It is boiled in water to extract its soluble 
 parts, then dried, and beat with a mallet to 
 loosen its texture. It has now the appear- 
 ance of very spongy doe- skin leather. It is 
 lastly impregnated with a solution of nitre, 
 and dried, when it is called spunk, or Ger- 
 man tinder ; a substance much used on the 
 continent for lighting fire, either from the 
 collision of flint and steel, or from the sud- 
 den condensation of air in the atmospheric 
 pyrophorus.* 
 
 Amalgam. This name is applied to the 
 combinations of mercury with other metallic 
 substances. See Mercury. 
 
 Amber is a hard, brittle, tasteless sub- 
 stance, sometimes perfectly transparent, but 
 mostly semi-transparent or opaque, and of a 
 glossy surface : it is found of all colours, 
 but chiefly yellow or orange, and often con- 
 tains leaves or insects ; its specific gravity is 
 from 1.065 to 1.100; its fracture is even, 
 smooth, and glossy ; it is capable of a fine 
 polish, and becomes electric by friction ; 
 when rubbed or heated, it gives a peculiar 
 agreeable smell, particularly when it melts, 
 that is at 550° of Fahrenheit, but it then 
 
AMB 
 
 AMB 
 
 Joses its transparency ; projected on burning 
 coals, it burns with a whitish flame, and a 
 whitish yellow smoke, but gives very little 
 soot, and leaves brownish ashes ; it is insolu- 
 ble in water and alcohol, though the latter, 
 when highly rectified, extracts a reddish co- 
 lour from it ; but it is soluble in the sulphu- 
 ric acid, which then acquires a reddish pur- 
 ple colour, and is precipitable from it by 
 water ; no other acid dissolves it, nor is it 
 soluble in essential or expressed oils, without 
 some decomposition and long digestion ; but 
 pure alkali dissolves it. By distillation it 
 affords a small quantity of water, with a lit- 
 tle acetous acid, an oil, and a peculiar acid. 
 See Acid (Succinic). The oil rises at first 
 colourless ; but, as the heat increases, be- 
 comes brown, thick, and empyreumatic. 
 The oil may be rectified by successive distil- 
 lations, or it may be obtained very light 
 and limpid at once, if it be put into a glass 
 alembic with water, as the elder Rouelle di- 
 rects, and distilled at a heat not greater than 
 212° Fahr. It requires to be kept in stone 
 bottles, however, to retain this state ; for in 
 glass vessels it becomes brown by the action 
 of light. 
 
 Amber is met with plentifully in regular 
 mines in some parts of Prussia. The upper 
 surface is composed of sand, under which is 
 a stratum of loam, and under this a bed of 
 wood, partly entire, but chiefly mouldered or 
 changed into a bituminous substance. Under 
 the wood is a stratum of sulphuric or rather 
 aluminous mineral, in which the amber is 
 found. Strong sulphureous exhalations are 
 often perceived in the pits. 
 
 * Detached pieces are also found occa- 
 sionally on the sea-coast in various countries. 
 It has been found in gravel beds near Lon- 
 don. In the Royal Cabinet at Berlin there 
 is a mass of 18 lbs. weight, supposed to be 
 the largest ever found. Jussieu asserts, that 
 the delicate insects in amber, which prove 
 the tranquillity of its formation, are not Eu- 
 ropean. M. Ilauy has pointed out the fol- 
 lowing distinctions between mellite and 
 copal, the bodies which most closely resem- 
 ble amber. IViellite is infusible by heat. A 
 bit of copal heated at the end of a knife takes 
 lire, melting into drops, which flatten as they 
 fall ; whereas amber burns with spitting and 
 frothing ; and when its liquefied particles 
 drop, they rebound from the plane which 
 receives them. The origin of amber is at 
 present involved in perfect obscurity, though 
 the rapid progress of vegetable chemistry 
 promises soon to throw light on it. Various 
 frauds are practised with this substance. 
 Neumann states as the common practices of 
 workmen the two following *. * The one 
 consists in surrounding the amber with sand 
 in an iron pot, and cementing it with a gra- 
 dual fire for forty hours, some small pieces 
 placed near the sides of the vessel being oc- 
 
 casionally taken out for judging of the effect 
 of the operation : the second method, which 
 lie says is that most generally practised, is 
 by digesting and boiling the amber about 
 twenty hours with rapeseed oil, by which 
 it is rendered both clear and hard. 
 
 * Werner has divided it into two sub- 
 species, the white and the yellow ; but there 
 is little advantage in the distinction. Its 
 ultimate constituents are the same with those 
 of vegetable bodies in general ; viz. earbon, 
 hydrogen, and oxygen ; but the proportions 
 have not been ascertained. 
 
 In the second volume of the Edinburgh 
 Philosophical Journal, Dr Brewster has 
 given an account of some optical proper- 
 ties of amber, from which he considers it 
 established beyond a doubt that amber is an 
 indurated vegetable juice ; and that the traces 
 Of a regular structure, indicated by its action 
 upon polarized light, are not the effect of the 
 ordinary laws of crystallization by which 
 mellite has been formed, but are produced by 
 the same causes which influence the mecha- 
 nical condition of gum arabic, and other 
 gums, which are known to be formed by the 
 successive deposition and induration of vege- 
 table fluids.* 
 
 Amber is also used in Varnishes. See 
 Varnish, and Oil of Amber. 
 
 Ambergris is found in the sea, near the 
 coasts of various tropical countries ; and 
 has also been taken out of the intestines of 
 the physeter macrocephalus, the spermaceti 
 whale. As it has not been found in any 
 whales but such as are dead or sick, its pro- 
 duction is generally supposed to be owflng to 
 disease, though some have a little too pe- 
 remptorily affirmed it to be the cause of the 
 morbid affection* As no large piece has 
 ever been found without a greater or less 
 quantity of the beaks of the sepia octopodia, 
 the common food of the spermaceti wdiale, 
 interspersed throughout its substance, there 
 can be little doubt of its originating in the 
 intestines of the whale ; for if it w r ere occa- 
 sionally swallowed by it only, and then 
 caused disease, it must much more frequent- 
 ly be found without these, when it is met 
 with floating in the sea, or thrown upon the 
 shore. 
 
 Ambergris is found of various sizes, ge- 
 nerally in small fragments, but sometimes so 
 large as to weigh near two hundred pounds. 
 When taken from the whale it is not so hard 
 as it becomes afterward on exposure to the 
 air* Its specific gravity ranges from 780 to 
 926. If good, it adheres like wax to the 
 edge of a knife with which it is scraped, re- 
 tains the impression of the teeth or nails, and 
 emits a fat odoriferous liquid on being pene- 
 trated with a hot needle. It is generally 
 brittle ; but, on rubbing it witli the nail, it 
 becomes smooth like hard soap. Its colour 
 is either white, black, ash coloured, yellow, 
 
AME 
 
 A MM 
 
 or blackish ; or it is variegated, namely, 
 grey with black specks, or grey with yellow 
 specks. Its smell is peculiar, and not easy 
 to be counterfeited. At 144° it melts, and 
 at 212° is volatilized in the form of a white 
 vapour. But, on a red-hot coal, it burns, 
 ami is entirely dissipated. Water has no 
 action on it ; acids, except nitric, act feebly 
 on it ; alkalis combine with it, and form a 
 soap ; ether and the volatile oils dissolve it ; 
 so do the fixed oils, and also ammonia, when 
 assisted by heat ; alcohol dissolves a portion 
 ot it, and is of great use in analyzing it, by 
 separating its constituent parts. According 
 to Bouillon la Grange, who has given the 
 latest analysis of it, 3820 parts of ambergris 
 consist of adipocere 2016 parts, a resinous 
 substance 1167, benzoic acid 425, and coal 
 212. * But Bucholz could find no benzoic 
 
 acid in it. Dr Ure examined two different 
 specimens with considerable attention. The 
 one yielded benzoic acid, the other, equally 
 genuine to all appearance, afforded none. 
 See Adipogere and Intestinal Concretion. 
 
 An alcoholic solution of ambergris, added 
 in minute quantity to lavender water, tooth 
 powder, hair powder, wash balls, &c. com- 
 municates its peculiar fragrance. Its retail 
 price being in London so high as a guinea 
 per oz. leads to many adulterations. These 
 consist of various mixtures of benzoin, labda- 
 num, meal, &c. scented with musk. The 
 greasy appearance and smell which heated 
 ambergris exhibits, afford good criteria, join- 
 ed to its solubility in hot ether and alcohol.* 
 
 It has occasionally been employed' in me- 
 dicine, but its use is now confined to the 
 perfumer. Dr Sw r ediaur took thirty grains 
 of it without perceiving any sensible effect. 
 A sailor, w r ho took half an ounce of it, found 
 it a good purgative. 
 
 * Amblvgonite. A greenish coloured 
 mineral of different pale shades, marked on 
 the surface with reddish and yellowish brown 
 spots. It occurs massive and crystallized in 
 oblique four-sided prisms. Lustre vitreous ; 
 cleavage parallel with the sides of an oblique 
 four-sided prism of 106° 10' and 77° 50' ; 
 fracture uneven ; fragments rhomboidal ; 
 translucent ; hardness, as felspar ; brittle ; 
 sp. gr. 3.0. Intumesces with the blow-pipe, 
 and fuses with a reddish-yellow phospho- 
 rescence into a white enamel. It qccurs in 
 granite, along w r ith green topaz and tourma- 
 line, near Pinig in Saxony. It seems to be 
 a species of spodumene. * 
 
 Amethyst. The amethyst is a gem of a 
 .violet colour, and great brilliancy, said to 
 be as bard as the ruby or sapphire, from 
 which it only differs in colour. This is call- 
 ed the oriental amethyst, and is very rare. 
 When it inclines to the purple or rosy co- 
 lour, it is more esteemed than when it is 
 nearer to the blue. These amethysts have 
 the same figure, hardness, specific gravity, 
 
 and other qualities, as the best sapphires or 
 rubies, and come from the same places, par- 
 ticularly from Persia, Arabia, Armenia, and 
 the West Indies. The occidental amethysts 
 are merely coloured crystals or quartz. See 
 Quartz and Sapphire. 
 
 Amianthus, Mountain Flax. See Asbes- 
 tus. 
 
 * Ammonia, called also Volatile Alkali, 
 We shall first consider this substance in its 
 purely scientific relations, and then detail its 
 manufacture on the great scale, and its uses 
 in die arts. There is a saline body, former- 
 ly brought from Egypt, where it was sepa- 
 rated from soot by sublimation, but which is 
 now made abundantly in Europe, called sal 
 ammoniac. From this salt, pure ammonia 
 can be readily obtained by the following pro- 
 cess : Mix unslaked quicklime with its owti 
 weight of sal ammoniac, each in fine powder, 
 and introduce them into a glass retort. Join 
 to the beak of the retort, by a collar of 
 caoutchouc, (a neck of an India rubber bottle 
 answers well), a glass tube about 18 inches 
 long, containing pieces of ignited muriate of 
 lime. This tube should lie in a horizontal 
 position, and its free end, previously bent 
 obliquely by the blow'-pipe, should dip into 
 dry mercury in a pneumatic trough. A slip 
 of porous paper, as an additional precaution, 
 may be tied round the tube, and kept moist 
 with ether. If a gentle heat from a char- 
 coal chauffer or lamp be now applied to the 
 bottom of the retort, a gaseous body will 
 bubble up through the mercury. Fill a little 
 glass tube, sealed at one end, with the gas, 
 and transfer it, closely stopped at the other 
 end, into a basin containing water. If the 
 water rise instantly and fill the whole tube, 
 the gas is pure, and may be received for ex- 
 amination. 
 
 Ammonia is a transparent, colourless, and 
 consequently invisible gas, possessed of elas- 
 ticity, and the other mechanical properties of 
 the atmospherical air. Its specific gravity is 
 an important datum in chemical researches* 
 and has been rather differently stated. Now* 
 as no aeriform body is more easily obtained 
 in a pure state than ammonia, this diversity 
 among accurate experimentalists, shews the 
 nicety of this statical operation. MM. Biot 
 and Arago make it = 0.59669 by experi- 
 ment, and by calculation from its elementary 
 gases, they make it = 0.59438, Kirwan 
 says, that 100 cubic inches weigh 18.16 gr. 
 at 30 inches of bar. and 61° F., which com- 
 pared to air reckoned 30.519, gives 0.59540* 
 Sir H. Davy determines its density to he = 
 0.590, with which estimate the theoretic cal- 
 culations of Dr Prout, in the 6th volume of 
 the Annals of Philosophy, agree. 
 
 This gas has an exceedingly pungent 
 smell, well known by the old name of spirits 
 of hartshorn. An animal plunged into it 
 speedily dies. It extinguishes combustion, 
 
A MM 
 
 A MM 
 
 I 
 
 I 
 
 
 
 
 but being itself to a certain degree combus- 
 tible, the flame of a taper immersed in it, is 
 enlarged before going out. It has a very 
 acrid taste. Water condenses it very rapidly. 
 The following valuable table of its aqueous 
 combinations has been given 
 
 Davy. 
 
 Sp. Gr . 
 0.8750 
 0.8875 
 0.9000 
 0.9054 
 0.9166 
 0.9255 
 0.9326 
 0.9385 
 0.9435 
 0.9476 
 0.9513 
 0.9545 
 0.9573 
 0.9597 
 0.9619 
 0.9692 
 
 Ammonia . 
 32.50 
 29.25 
 26.00 
 25.37 
 22.07 
 19.54 
 17-52 
 15.88 
 14.53 
 1 3.46 
 1 2.40 
 11.56 
 10.82 
 10.17 
 9.60 
 9.50 
 
 by Sir H. 
 
 Water. 
 
 67.50 
 70.75 
 74.00 
 74.63 
 77.93 
 
 80.46 
 82.48 
 84.12 
 
 85.47 
 86.54 
 87.60 
 88.44 
 89.18 
 89.83 
 90.40 
 
 90.50 
 
 Water is capable of dissolving easily 
 about one-third of its weight of ainmoniacal 
 gas, or 460 times its bulk. Hence, when 
 placed in contact with a tube filled with this 
 gas, water rushes into it with explosive velo- 
 city. Probably the quantity of ammonia 
 stated in the above table is too high by about 
 one per cent. 
 
 Dr Thomson states, in his System, vol. 2d. 
 page 29. “ Water, by my trials, is capable of 
 absorbing 780 times its bulk of this gas ; 
 while, in the mean time, the bulk of the li- 
 quid increases from 6 to 10. The specific 
 gravity of this solution is 0.900, which just 
 accords with the increase of bulk.” Correct- 
 ing the first error where 6 is substituted for 9, 
 a less excusable error comes to be examined. 
 Taking the Doctor’s own number for the 
 specific gravity of the gas, it is evident that 
 780 times the volume, combined with water, 
 would give nearly 36 by weight of gas in 
 100 of the liquid. But in the very same 
 page he says, “ It follows, from the experi- 
 ments of Davy, that a saturated solution of 
 ammonia is composed of 74.63 water and 
 25.37 ammonia.” Hence, if that be correct, 
 a liquid containing 36 per cent of ammonia 
 is a manifest impossibility. In the very 
 same page he gives Mr Dalton’s table, 
 “ which exhibits the quantity of ammonia 
 contained in ammoniacal solutions of differ- 
 ent specific gravities.” In this table, oppo- 
 site to the specific gravity 0.90 of the liquid 
 ammonia, such as he made in his own trials, 
 we have 22.2, a far different quantity from 
 the number 36 equivalent to his 780 vo- 
 lumes. Sir H. Davy’s table differs very little 
 from that of Mr Dalton, the truth probably 
 lying between them. It is certain, indeed, 
 
 that 100 parts of ammoniacal w r ater, sp. gr. 
 0.900, instead of containing 36 parts, or 780 
 volumes, do not contain above 24 parts, or 
 520 volumes. Had Dr Thomson consulted 
 Sir H. Davy’s Elements of Chemical Philo* 
 sophy, he would have found the following 
 statement, p. 268. “ At the temperature of 
 
 50°, under a pressure equal to 29.8 inches, 
 water, I find, absorbs about 670 times its 
 volume of gas, and becomes of specific gra- 
 vity 0.875.” In the table of Sir H. Davy, 
 opposite 0.875, w r e have 32.5 per cent of 
 ammonia. If any person will take the 
 trouble of calculating, he w ill find that 670 
 inches of a gas, of which 100 cubic inches 
 weigh 18 grs, in combining with one cubic 
 inch of water weighing 252.5 grains, form a 
 solution that must contain just 32.3 per cent 
 of the condensed gas. 
 
 We thus perceive, that liquid ammonia, as 
 the aqueous compound is termed, may like 
 spirits be very accurately valued by its speci- 
 fic gravity. But it differs remarkably from 
 alcoholic mixtures in this respect, that the 
 strongest ammoniacal liquor, w'hen it is di- 
 luted with water, suffers no condensation of 
 volume. The specific gravity of the dilute, 
 is the mean of that of its components. 
 Hence, having one point accurately, we can 
 compute all below it, by paying attention to 
 the rule given under Specific Gravity. To 
 procure aqueous ammonia, we may use either 
 a common still and refrigeratory or a Woolfe’s 
 apparatus. The latter should be preferred. 
 Into a retort we put a mixture of two part* 
 of slaked lime, and one part of pulverized 
 sal ammoniac, and having connected the beak 
 of the retort with the Woolfe’s apparatus, 
 containing pure water, we then disengage 
 the ammonia, by the application of heat. 
 When gas ceases to be evolved, the addition 
 of a little hot water will renew its disengage- 
 ment, and ensure complete decomposition of 
 the salt. Since sal ammoniac contains nearly 
 j its weight of ammonia, ten pounds of it 
 should yield by economical treatment, 30 
 pounds of liquid, whose specific gravity is 
 0.950, which is as strong as the ordinary 
 purposes of chemistry and medicine require ; 
 and it will form twice that quantity, or 60 
 pounds of the common water of ammonia, 
 sold by apothecaries, which has rarely a smal- 
 ler density than 0.978 or 0.980. There is 
 no temptation to make it with the ammoni- 
 acal carbonate ; but if this salt be accident- 
 ally present, it is instantly detected by its 
 causing a milkiness in lime water. 
 
 Ammoniacal gas, perfectly dry, when 
 mixed w ith oxygen, explodes with the elec- 
 tric spark, and is converted into w^ater and 
 nitrogen, as has been shewn in an ingenious 
 paper by Dr Henry. But the simplest, and 
 perhaps most accurate mode of resolving 
 ammonia into its elementary constituents, is 
 that first practised by M, Berthollet, the 
 
AMM 
 
 AMM 
 
 celebrated discoverer of its composition. 
 1 his consists in making the pure gas tra- 
 verse very slowly an ignited porcelain tube 
 ol a small diameter, ihe process, as lately 
 repeated by M. Gay Lussac, yielded from 
 100 cubic inches of ammonia, 200 cubic 
 inches of constituent gases ; of which by 
 subsequent analysis, .50 were found to be 
 nitrogen, and 1.50 hydrogen. Hence we 
 see, that the reciprocal affinity of the am- 
 moniacal elements had effected a condensa- 
 tion equal to one-half of the volume of the 
 free gases. It appears, by the most recent 
 determinations, that the specific gravity of 
 hydrogen is 0.0694, compared to air as 
 unity, and that of nitrogen, 0.9722. Three 
 volumes of the former will therefore weigh 
 0.2082, and one of the latter, 0.9722; the 
 sum of which numbers, 1.1804, divided by 2, 
 ought to coincide with the experimental den- 
 sity of ammonia. Now, it is 0.5902, being 
 an exact correspondence. And the ratio of 
 the two weights, reduced to 100 parts, will 
 be 82. S 6 nitrogen to 17.64 hydrogen. To 
 reduce ammonia to the system of equiva- 
 lents, or to find its saturating ratio on that 
 scale where oxygen represents unity, we have 
 this proportion 0: 9722: 1.75: : 1.1S04 : 
 2. 1 225, so that 2. 1 25 may be called its prime 
 equivalent. We shall find this number de- 
 duced from analysis, confirmed by the syn- 
 thesis of all the ammoniacal salts. 
 
 Dr Prout, in an able memoir on the rela- 
 tion between the specific gravities of gaseous 
 bodies, and the weights of their atoms, pub- 
 lished in the 6th vol. of the Annals of Phi- 
 losophy, makes the theoretical weight of the 
 atom of ammonia to be only 1.9375, con- 
 sidering it as a compound of 1 atom of 
 azote, and 1 % atoms of hydrogen. This 
 statement appears to be a logical inference 
 from Mr Dalton’s hypothesis of atomical 
 combination. For water, the great ground- 
 work of his atomic structure, is represented 
 as a compound of one atom oxygen with 
 one atom of hydrogen ; and this atomi- 
 cal unit of hydrogen consists of two volumes 
 of the gas. Hence three volumes of the gas 
 must represent an atom and an half. But 
 an atom is, by its very definition, indivisible. 
 Dr Prout in- the 38th number of the Annals, 
 restores the true proportions of 3 atoms 
 hydrogen, + 1 azote. Our doctrine of equi- 
 valent primes, resting on the basis of ex- 
 perimental induction, claims no knowledge 
 of the atomical constitution of bodies. 
 
 The alkaline nature of ammonia is de- 
 monstrated, not only by its neutralizing 
 acidity, and changing the vegetable reds to 
 purple or green, but also by its being at- 
 tracted to the negative pole of a voltaic 
 arrangement. When a pretty strong elec- 
 tric power is applied to ammonia in its liquid 
 or solid combinations, simple decomposition 
 is effected ; but in contact with mercury, 
 
 very mysterious phenomena occur. If a 
 globule of mercury be surrounded with a 
 little water of ammonia, or placed in a little 
 cavity in a piece of sal ammoniac, and then 
 subjected to the voltaic power by two wires, 
 the negative touching the mercury, and the 
 positive the ammoniacal compound, the glo- 
 bule is instantly covered with a circulating 
 film, a white smoke rises from it, and its 
 volume enlarges, whilst it shoots out ramifi- 
 cations of a semi-solid consistence over the 
 salt. The amalgam has the consistence of 
 soft butter, and may he cut with a knife. 
 Whenever the electrization is suspended, the 
 Crab- like fibres retract towards the central 
 mass, which soon, by the constant formation 
 of white saline films, resumes its pristine 
 globular shape and size. The enlargement 
 of volume seems to amount occasionally to 
 ten times that of the mercury, when a small 
 globule is employed. Sir II. Davy, Ber- 
 zelius, and MM. Gay Lussac and Thenard, 
 have studied this singular phenomenon with 
 great care. They produced the very same 
 substance by putting an amalgam of mer- 
 cury and potassium into the moistened cupel 
 of sal ammoniac. It becomes five or six 
 times larger, assumes the consistence of but- 
 ter, whilst it retains its metallic lustre. 
 
 What takes place in these experiments ? In 
 the second case, the substance of metallic aspect 
 ‘■which w r e obtain is an ammoniacal hydruret 
 of mercury and potassium. There is form- 
 ed, besides, muriate of potash* Consequent- 
 ly a portion of the potassium of the amal- 
 gam, decomposes the water, becomes pot- 
 ash, which itself decomposes the muriate of 
 ammonia. Thence result hydrogen and am- 
 monia, which, in the nascent state, unite to 
 the undecomposed amalgam. In the first 
 experiment, the substance, which, as in the 
 second, presents the metallic aspect, is only 
 an ammoniacal hydruret of mercury ; its 
 formation is accompanied by the perceptible 
 evolution of a certain quantity of chlorine at 
 the positive pole. It is obvious, therefore, 
 that the salt is decomposed by the electricity* 
 The hydrogen of the muriatic acid, and the 
 ammonia, both combine with the mercury. 
 These hydrurets possess the following pro- 
 perties. 
 
 Their sp. gravity is in general below 3.0; 
 exposed for some time to the temperature of 
 .32° F. they assume considerable hardness, 
 and crystallize in cubes, which are often as 
 beautiful and large as those of bismuth. 
 Ether and alcohol instantly destroy these 
 amalgams, exciting a brisk effervescence with 
 them, and reproducing the pure mercurial 
 globule. These amalgams are slightly per- 
 manent in the air, if undisturbed ; hut the 
 least agitation is fatal to their existence. 
 MM. Gay Lussac and Thenard found, by 
 immersion in water, that mercury, in passing 
 to the state of a hydruret, absorbed time* 
 
AMM 
 
 AMM 
 
 its volume of hydrogen. The ammoniacal 
 hydruret of mercury and potassium may ex- 
 ist by itself; but as soon as we attempt to 
 separate or oxidize the potassium, its other 
 constituent principles also separate. Hence 
 this hydruret is speedily decomposed by the 
 air, by oxygen gas, and in general by all 
 bodies that act upon potassium. It is even 
 affected by mercury, so that in treating it 
 with this metal, we may easily determine the 
 relative quantity of ammonia and hydrogen 
 which it contains. We need only tor this 
 purpose take up the interior parts of the hy- 
 druret with a little iron spoon, fill up with 
 it a little glass tube, already nearly full of 
 mercury ; and closing this with a very dry 
 stopper, invert it in mercury equally dry. 
 The hydruret will rise to the upper part of 
 the tube, will be decomposed, especially by a 
 slight agitation, and will give out hydrogen 
 and ammonia in the ratio of 1 to 2.5. 
 
 The mere ammoniacal hydrurets contain 
 but a very small quantity of hydrogen and 
 ammonia. By supposing that in the ammo- 
 niacal hydruret of mercury, the hydrogen is to 
 the ammonia in the same proportion as in the 
 ammoniacal hydruret of mercury and potas- 
 sium, it will appear that the first is formed 
 in volume of 1 of mercury, 3.47 hydrogen, 
 and 8. 67 ammoniacal gas, at the mean pres- 
 sure and temperature of 30. and 60° ; or in 
 weight, of about 1800 parts of mercury, witli 
 1 part of hydrogen, and 1 of ammonia. 
 
 Ammonia is not affected by a cherry red 
 heat. According to Guyton de IVIorveau, it 
 becomes a liquid at about 40° — 0°, or at 0°, 
 the freezing point of mercury; but it is un- 
 certain whether the appearances he observed 
 may not have been owing to hygrometrie 
 water, as happens with chlorine gas. The 
 ammoniacal liquid loses its pungent smell as 
 its temperature sinks, till at — 50°, it gelati- 
 nizes, if suddenly cooled ; but if slowly cool- 
 ed, it crystallizes. 
 
 Oxygen, by means of electricity, or a mere 
 red heat, resolves ammonia into water and ni- 
 trogen. When there is a considerable excess 
 of oxygen, it acidifies a portion of the nitro- 
 gen into nitrous acid, whence many fallacies 
 in analysis have arisen. Chlorine and ammo- 
 nia exercise so powerful an action on each 
 other, that when mixed suddenly, a sheet of 
 white flame pervades them. The simplest 
 way of making this fine experiment, is to in- 
 vert a mattrass, with a wide mouth and co- 
 nical neck, over another with a taper neck, 
 containing a mixture of sal ammoniac and 
 lime, heated by a lamp. As soon as the 
 upper vessel seems to be full of ammonia, by 
 the overflow of the pungent gas, it is to be 
 cautiously lifted up, and inserted, in a per- 
 pendicular direction, into a wide-mouthed 
 glass decanter or flask, filled with chlorine. 
 On seizing the two vessels thus joined, with 
 the two hands covered with glovcs ; and sud- 
 
 denly inverting them, like a sandglass, the 
 heavy chlorine and light ammonia, rushing 
 in opposite directions, unite, with the evolu- 
 tion of flame. As one volume of ammonia 
 contains, in a condensed state, one and a half 
 of hydrogen, which requires for its saturation 
 just one and a half of chlorine, this quantity 
 should resolve the mixture into muriatic 
 acid and nitrogen, and thereby give a ready 
 analysis of the alkaline gas. If the propor- 
 tion of chlorine be less, sal ammoniac and 
 nitrogen are the results. The same thing 
 happens on mixing the aqueous solutions of 
 ammonia and chlorine. But if large bubbles 
 of chlorine be let up into ammoniacal water 
 of moderate strength, luminous streaks are 
 seen in the dark to pervade the liquid, and 
 the same reciprocal change of the ingredients 
 is effected. 
 
 MM. Gay Lussac and Thenard state that 
 when 3 parts of ammoniacal gas, and 1 
 of chlorine, are mixed together, they con- 
 dense into sal ammoniac, and azote, equal 
 to 1-lOtli the whole volume, is given out. 
 This result is at variance with their own 
 theory of volumes. 
 
 Three of ammoniacal gas consist of 4^ hy- 
 drogen, and 1 nitrogen in a condensed state]; 
 
 1 of chlorine seizes 1 of hydrogen, to form 
 
 2 of muriatic acid gas, which precipitate 
 with 2 of ammonia, in a pulverulent mu- 
 riate. But the third volume of ammonia 
 had parted with 1 volume of its hydrogen to 
 the chlorine, and another half- volume of hy- 
 drogen, will unite with 0. 166 of a volume of 
 
 nitrogen, to form _li_ = 0.35 of redundant 
 
 2 
 
 ammonia, while 0.35 of a volume of nitrogen 
 is left unemployed. Hence of a volume, 
 or of the original bulk of the mixed gases, 
 ought to remain ; consisting of equal parts 
 of ammonia and nitrogen, instead of 1-lOtli 
 of azote, as the French chemists state. 
 
 Iodine has an analogous action on ammo- 
 nia ; seizing a portion of its hydrogen to 
 form hydriodic acid, w'hence hydriodate of 
 ammonia results ; while another portion of 
 iodine unites with the liberated nitrogen, to 
 form the explosive pulverulent iodide. 
 
 Cyanogen and ammoniacal gas begin to 
 act upon each other whenever they come in- 
 to contact, but some hours are requisite to 
 render the effect complete. They unite in 
 the proportion nearly of 1 to 1 forming a 
 compound which gives a dark orange brown 
 colour to water, but dissolves in only a very 
 small quantity in water. The solution does 
 not produce prussian blue with the salts of 
 iron. 
 
 By transmitting ammoniacal gas through 
 charcoal ignited in a tube, prussic or hydro- 
 cyanic acid is formed. 
 
 The action of the alkaline metals on gase- 
 ous ammonia is very curious. When potas- 
 
AMM 
 
 A MM 
 
 slum is fused in that gas, a very fusible olive 
 green substance, consisting of potassium, ni- 
 trogen, and ammonia, is formed ; and a vo- 
 lume of hydrogen remains, exactly equal to 
 what would result from the action on water, 
 of the quantity of potassium employed. 
 Hence, according to M. Thenard, the am- 
 monia is divided into two portions. One is 
 decomposed, so that its nitrogen combines 
 with the potassium, and its hydrogen remains 
 free, whilst the other is absorbed in whole or 
 in part by the nitroguret of potassium. Sodium 
 acts in the same manner. The olive sub- 
 stance is opaque, and it is only when in plates 
 of extreme thinness that it appears semi- 
 transparent ; it has nothing of the metallic 
 appearance ; it is heavier than water ; and 
 on minute inspection seems imperfectly crys- 
 tallized. When it is exposed to a heat pro- 
 gressively increased, it melts, disengages am- 
 monia, and hydrogen, and nitrogen, in the 
 proportions constituting ammonia ; then it 
 becomes solid, still preserving its green 
 colour, and is converted into a nitroguret of 
 potassium or sodium. Exposed to the air 
 at the ordinary temperature, it attracts only 
 its humidity, but not its oxygen, and is 
 slowly transformed into ammoniacal gas, and 
 potash or soda. It burns vividly when pro- 
 jected into a hot crucible, or when heated in 
 a vessel containing oxygen. Water and acids 
 produce also sudden decomposition, with the 
 extrication of heat. Alkalis or alkaline salts 
 are produced. Alcohol likewise decomposes 
 it with similar results. The preceding des- 
 cription of the compound of ammonia with 
 potassium, as prepared by MM. Gay Lussac 
 and Thenard, was controverted by Sir H. 
 Davy. 
 
 The experiments of this accurate che- 
 mist led to the conclusion, that the presence 
 of moisture had modified their results. In 
 proportion as more precautions are taken 
 to keep every thing absolutely dry, so in pro- 
 portion, is less ammonia regenerated. He 
 seldom obtained as much as -j-q of the quan- 
 tity absorbed ; and he never could procure 
 hydrogen and nitrogen in the proportions 
 constituting ammonia ; there was always an 
 excess of nitrogen. The following experi- 
 ment was conducted with the utmost nicety. 
 5\ gr. of potassium were heated in 12 cubic 
 inches of ammoniacal gas ; 7.5 were absorbed, 
 and 5 . 2 of hydrogen evolved. On distilling 
 the olive- coloured solid in a tube of platina, 
 9 cubical inches of gas were given off, and 
 half a cubical inch remained in the tube and 
 adapters. Of the 9 cubical inches, one-fifth 
 of a cubical inch only was ammonia; 10 
 measures of the permanent gas mixed with 
 7.5 of oxygen, and acted upon by the electri- 
 cal spark, left a residuum of 7.5. He infers 
 that the results of the analysis of ammonia, 
 by electricity and potassium, are the same. 
 
 On the whole, we may legitimately in- 
 
 fer that there is something yet unexplained 
 in these phenomena. The potassium sepa- 
 rates from ammonia, as much hydrogen, as 
 an equal weight of it would from water. If 
 two volumes of hydrogen be thus detached 
 from the alkaline gas, the remaining volume, 
 with the volume of nitrogen, will be left to 
 combine with the potassium, forming a triple 
 compound, somewhat analogous to the cyan- 
 ides, a compound capable of condensing am- 
 monia. For an account of a singular com- 
 bination of ammonia, by which its volatility 
 seems destroyed, see Chlorine. 
 
 When ammoniacal gas is transmitted over 
 ignited wires of iron, copper, platina, &c. it 
 is decomposed completely, and though the’ 
 metals are not increased in weight, they 
 have become extremely brittle. Iron, at the 
 same temperature, decomposes the ammonia, 
 with double the rapidity that platinum does. 
 At a high temperature, the protoxide of ni- 
 trogen decomposes ammonia. 
 
 Of the ordinary metals, zinc is the only 
 one which liquid ammonia oxidizes and then 
 dissolves. But it acts on many of the me- 
 tallic oxides. At a high temperature the- 
 gas deoxidizes all those which are reducible 
 by hydrogen. The oxides soluble in liquid 
 ammonia, are the oxide of zinc, the protoxide 
 and peroxide of copper, the oxide of silver, 
 the third and fourth oxides of antimony, the 
 oxide of tellurium, the protoxides of nickel, 
 cobalt, and iron, the peroxide of tin, mer- 
 cury, gold, and platinum. The first five are 
 very soluble, the rest less so. These com- 
 binations can be obtained by evaporation, in 
 the dry state, only with copper, antimony, 
 mercury, gold, platinum, and silver; the four 
 last of which, are very remarkable for their 
 detonating property. See the particular 
 metals. 
 
 All the acids are susceptible of combining 
 with ammonia, and they almost all form with 
 it neutral compounds. M. Gay Lussac 
 made the important discovery, that when- 
 ever the acid is gaseous, its combination 
 with ammoniacal gas, takes place in a simple 
 ratio of determinate volumes, whether a neu- 
 tral or a subsalt be formed. 
 
 Ammoniacal Salts have the following 
 general characters. — 
 
 1 st, When treated with a caustic fixed al- 
 kali or earth, they exhale the peculiar smell 
 of ammonia. 
 
 2d, They are generally soluble in water, 
 and crystallizable. 
 
 3d, They are all decomposed at a moderate 
 red heat; and if the acid be fixed, as the 
 phosphoric or boracic, the ammonia comes 
 aw r ay pure. 
 
 4 til, When they are dropped into a solu- 
 tion of muriate of platina, a yellow- precipi- 
 tate falls. 
 
 1. Acetate. This saline compound was 
 formerly called the spirit of Miiulererus, who 
 
AMM 
 
 AMM 
 
 introduced it into medicine as a febrifuge 
 sudorific. By saturating a pretty strong 
 acetic acid with subcarbonate of ammonia, 
 enclosing the liquid under the receiver of 
 an air-pump, along with a saucerful of 
 sulphuric acid, and exhausting the air, the 
 salt will concrete in acicular crystals, which 
 are nearly neutral. It may also be made 
 very conveniently, by mixing hot saturated 
 solutions of acetate of lead, and sulphate of 
 ammonia, taking 100 of the first salt in its 
 ordinary state, to 34.4 of the second, well 
 dried at a heat of 212°. Or even muriate of 
 ammonia will answer in the proportion of 
 27. 9 to 100 of the acetate. Acetate of ammo- 
 nia has a cooling sweetish taste. It is deli- 
 quescent, and volatile at all temperatures ; but 
 it sublimes in the solid state at 250°. It con- 
 sists of 7 5-|- of dry acetic acid, and 24j am- 
 monia. When intended for medicine, it 
 should always be prepared from pure acetic 
 acid, and subcarbonate of ammonia. 
 
 Ar&eniate of ammonia may be formed by 
 saturating the arsenic acid with ammonia, and 
 evaporating the liquid. Crystals of a rliom- 
 boidal prismatic form are obtained. A bin- 
 arseniate may also be made by using an ex- 
 cess of acid. At a red heat, the ammonia 
 of both salts is decomposed, and the acid is 
 reduced to the metallic state. Under the 
 respective acids, an account of several am- 
 moniacal salts will be found. As the mu- 
 riate, however, constitutes an extensive ma- 
 nufacture, we shall enter here into some ad- 
 ditional details concerning its production. 
 
 Sal ammoniac was originally fabricated in 
 Egypt. The dung of camels and other ani- 
 mals constitutes the chief fuel used in that 
 country. The soot is carefully collected. 
 Globular glass vessels, about a foot in dia- 
 meter, are filled within a few inches of their 
 mouth with it, and are then arranged in an 
 oblong furnace, where they are exposed to a 
 heat gradually increased. The upper part 
 of the glass balloon stands out of the fur- 
 nace, and is kept relatively cool by the air. 
 On the 3d day the operation is completed, 
 at which time they plunge an iron rod occa- 
 sionally into the mouths of the globes, to 
 prevent them from closing up, and thus en- 
 danger the bursting of the glass. 
 
 '1 he fire is allowed to go out ; and on break- 
 ing the cooled globes, their upper part is 
 found to be lined with sal ammonia in hem- 
 ispherical lumps, about l 2\ inches thick, of a 
 greyish white colour, semi-transparent, and 
 possessed of a degree of elasticity. 26 pounds 
 ol soot yield 6 of sal ammoniac. The ordi- 
 nary mode of manufacturing sal ammoniac 
 in Europe, is by combining with muriatic 
 acid fhe ammonia resulting from the igneous 
 decomposition of animal matters in close 
 vessels. Cylinders of cast iron, fitted up as 
 v.e have described under Acetic Ann, are 
 charged with bones, horns, parings of hides, 
 
 and oilier animal matters; and being ex- 
 posed to a full red heat, an immense quan- 
 tity of an impure liquid carbonate of ammonia 
 distils over. Mr Minish contrived a cheap 
 method of converting this liquid into sal am- 
 moniac. He digested it with pulverized 
 gypsum, or simply made it percolate through 
 a stratum of bruised gypsum ; whence re- 
 sulted a liquid sulphate of ammonia, and an 
 insoluble carbonate of lime. The liquid, 
 evaporated to dryness, was mixed with mu- 
 riate of soda, put into large glass balloons, 
 and decomposed by a subliming heat. Sal 
 ammoniac was found above in its characteristic 
 cake, while sulphate of soda remained below. 
 
 M. Leblanc of St Denis, near Paris, in- 
 vented another method of much ingenuity, 
 which is described by a commission of emi- 
 nent French chemists in the 19th volume of 
 the Annales de Chimie, and in the Journal 
 de Physique for the year 1794. He used 
 tight brick kilns, instead of iron cylinders, for 
 holding the materials to be decomposed. 
 Into one he put a mixture of common salt 
 and oil of vitriol ; into another, animal mat- 
 ters. Heat extricated from the first, muria- 
 tic acid gas, and from the second, ammonia ; 
 which bodies being conducted by their re- 
 spective flues into a third chamber lined 
 with lead, and containing a stratum of water 
 on its bottom, entered into combination, and 
 precipitated in solid sal ammoniac on the 
 roof and sides, or liquid at the bottom. 
 
 In the 20th volume of the Annales, a plan 
 for employing bittern or muriate of magnesia 
 to furnish the acid ingredient is described. 
 An ingenious process on the same principles, 
 was some time ago commenced at Borrows- 
 tounness in Scotland, by Mr Astley. He im- 
 bued in a stove- room, heated by brick flues, 
 parings of skins, horns, and other animal 
 matters, with the muriate of magnesia, or 
 mother water of the sea-salt works. The 
 matters thus impregnated and dried, were 
 subjected in a close kiln to a red heat, when 
 the sal ammoniac vapour sublimed, and was 
 condensed either in a solid form, into an 
 adjoining chamber or chimney, or else into 
 a stratum of water on its bottom. Muriate 
 of magnesia at a red heat, evolves muriatic 
 acid gas; an evolution probably aided in the 
 present case, by the affinity of ammonia. 
 
 From coal soot likewise a considerable 
 quantity of ammonia, in the state of carbo- 
 nate and sulphate, may be obtained, either by 
 sublimation or lixiviation with water. These 
 ammoniacal products can afterwards be 
 readily converted into the muriate, as above 
 described. M. Leblanc used a kettle or 
 eolipile for projecting steam into the leaden 
 chamber, to promote the combination. It 
 is evident, that the exact neutralization essen- 
 tial to sal ammoniac, might not he hit at 
 first in these operations; but it could be af- 
 terwards effected by the separate addition of 
 
ANA 
 
 ANA 
 
 a portion of alkaline or acid gas. As the 
 mother waters of the Cheshire salt-works 
 contain only per cent of muriate of mag- 
 nesia, they are not suitable, like those of sea- 
 salt works, for the above manufacture.* 
 
 * Ammoniac (Gum), This is a gum resin, 
 which consists, according to Braconnot, of 
 70 resin, 18.4 gum, 4.4 glutinous matter, 6 
 water, and 1.2 loss in 100 parts. It forms 
 a milky solution with water ; is partially 
 soluble in alcohol ; entirely in ether, nitric 
 acid, and alkalis. Sp. gr. 1.200. It has 
 a rather heavy smell, and a bitter sweet taste. 
 It is in small agglutinated pieces of a yel- 
 lowish white colour. It is used in medicine 
 as an expectorant and antispasmodic.* 
 
 Ammonites. These petrifactions, which 
 have likewise been distinguished by the name 
 of cornua ammonis , and are called snake-stones 
 by the vulgar, consist chiefly of lime-stone. 
 They are found of all sizes, from the breadth 
 of half an inch to more than two feet in dia- 
 meter; some of them rounded, others greatly 
 compressed, and lodged in different strata of 
 stones and clays. They appear to owe their 
 origin to shells of the nautilus kind. 
 
 Amomum. See Pimento. 
 
 * Amphibole. See Hornblende and Ac- 
 
 TYNOLITE.* 
 
 * Amfhigene. See Vesuvjan.* 
 
 * Amygdaloid. A compound mineral, 
 consisting of spheroidal particles or vesicles 
 of litliomarge, green earth, calc spar, steatite, 
 imbedded in a basis of fine grained green- 
 stone, or wacke, containing sometimes also 
 crystals of hornblende.* 
 
 Anacardium, Cashew Nut, or Marking 
 Nut. At one extremity of the fruit of the 
 cashew tree is a flattisli kidney-shaped nut, 
 between the rind of which and the thin outer 
 shell is a small quantity of a red, thickish, 
 inflammable, and very caustic liquor. This 
 liquor forms a useful marking ink, as any 
 thing written on linen or cotton with it is of 
 a brown colour, which gradually grows 
 blacker, and is very durable. 
 
 * Analcime. Cubic Zeolite. This mine- 
 ral is generally found in aggregated or cubic 
 crystals, whose solid angles are replaced by 
 three planes. External lustre between vi- 
 treous and pearly ; fracture, fiat conchoidal ; 
 colours, white, grey, or reddish ; translucent. 
 From its becomingjfecWy electrical by heat it 
 has got the name analcime. Its sp. gr. is 
 less than 2.6. It consists of 58 silica, 18 
 alumina, 2 lime, 10 soda, water, and 5-£ 
 loss in 100 parts. It is found in granite, 
 gneiss, trap rocks and lavas, at Calton Hill 
 Edinburgh, at Talisker in Skye, in Dum- 
 bartonshire, in the Ilartz, Bohemia, and at 
 the Ferroe Islands. The variety found at 
 Soinma has been called snreolite, from its 
 flesh colour.* 
 
 Analysis. Chemical analysis consists of 
 a great variety of operations, performed lor 
 
 the purpose of separating the component 
 parts of bodies. In these operations the 
 most extensive knowledge of such properties 
 of bodies as are already discovered must be 
 applied, in order to produce simplicity of 
 ellect, and certainty in the results. Che- 
 mical analysis can hardly be executed with 
 success by one who is not in possession of 
 a considerable number of simple substances 
 in a state of great purity, many of which, 
 from their effects, are called reagents. The 
 word analysis is applied by chemists to de- 
 note that series of operations, by which the 
 component parts of bodies are determined, 
 whether they be merely separated, or ex- 
 hibited apart from each other ; or whether 
 these distinctive properties he exhibited by 
 causing them to enter into new combina- 
 tions, without the perceptible intervention 
 of a separate state. The forming of new 
 combinations is called synthesis ; and, in 
 the chemical examination of bodies, analysis 
 or separation can scarcely ever he effected, 
 without synthesis taking place at the same 
 time. 
 
 As most of the improvements in the 
 science of chemistry consist in bringing the 
 art of analysis nearer to perfection, it is not 
 easy to give any other rule to the learner 
 than the general one of consulting and re- 
 marking the processes of the best chemists, 
 such as Scheele, Bergman, Berthollet, Kir- 
 wan, Vauquelin, and Berzelius. The bodies 
 which present themselves more frequently for 
 examination than others, are minerals and 
 mineral waters. In the examination of the 
 former, it was the habit of the earlier che- 
 mists to avail themselves of the action of 
 fire, with very few humid processes, which 
 are such as might be performed in the usual 
 temperature of the atmosphere. Modem 
 chemists have improved the process by fire, 
 by a very extensive use of the blow- pipe 
 (see Blow-pipe); and have succeeded in de- 
 termining the component parts of minerals 
 to great accuracy in the humid way. For 
 the method of analyzing mineral waters, see 
 Waters (Mineral); and for the analysis of 
 metallic ores, see Ores. 
 
 Several authors have written on the exa- 
 mination of earths and stones. 
 
 The first step in the examination of con- 
 sistent earths or stones is somewhat different 
 from that of such as are pulverulent. Their 
 specific gravity should first he examined ; 
 also their hardness, whether they will strike 
 fire with steel, or can be scratched by the 
 nail, or only by crystal, or stones of still 
 greater hardness; also their texture, pervi- 
 ousness to light, and whether they be mani- 
 festly homogeneous or compound species, <vc. 
 
 2d, In some eases, we should try whether 
 they imbibe water, or whether w ater can ex- 
 tract any thing from them by ebullition or 
 digestion. 
 
ANA 
 
 f 
 
 I 
 
 il 
 
 3d, Whether they be soluble in, or effer- 
 vesce with, acids, before or after pulveriza- 
 tion ; or whether decomposable by boiling in 
 a strong solution of potash, &c. as gypsums 
 and ponderous spars are. 
 
 4th, Whether they detonate with nitre. 
 
 5th, Whether they yield the fluor acid by 
 distillation with sulphuric acid, or ammonia 
 by distilling them with potash. 
 
 6th, Whether they be fusible per se with 
 a blow-pipe, and how they are alfected by 
 soda, borax, and microcosmic salt; and 
 whether they decrepitate when gradually 
 heated. 
 
 7th, Stones that melt per se with the 
 blow-pipe are certainly compound, and con. 
 tain at least three species of earth, of which 
 the calcareous is probably one ; and il they 
 give fire with steel, the siliceous is probably 
 another. 
 
 The general process prescribed by the 
 celebrated Vauquelin, in the 30th volume of 
 the Annales de Chimie, is the clearest which 
 has yet been offered to the chemical stu- 
 dent. 
 
 If the mineral be very hard, it is to be 
 ignited in a covered crucible of platinum, 
 and then plunged into cold water, to ren- 
 der it brittle and easily pulverizable. The 
 weight should be noted before and after this 
 operation, in order to see if any volatile mat- 
 ter has been emitted. For the purpose of 
 reducing stones to an impalpable powder, lit- 
 tle mortars of highly hardened steel arc now 
 made, consisting of a cylindrical case and 
 pestle. A mortar of agate is also used for 
 subsequent levigation. About ten grains of 
 the mineral should be treated at once ; and 
 after the whole 100 grains have been re- 
 duced in succession to an impalpable pow- 
 der, they should be weighed, to find what 
 increase may have been derived from the 
 substance of the agate. This addition may 
 be regarded as silica. 
 
 Of the ten primary earths, only four are 
 usually met with in minerals, viz. silica, alu- 
 mina, magnesia, and lime, associated with 
 some metallic oxides, which are commonly 
 iron, manganese, nickel, copper and chro- 
 mium. 
 
 If neither acid nor alkali be expected to 
 be present, the mineral is mixed in a silver 
 crucible, with thrice its weight of pure pot- 
 ash and a little water. Heat is gradually 
 applied to the covered crucible, and is finally 
 raised to redness; at which temperature it 
 ought to be maintained for an hour. If the 
 ma&s, on inspection, be a perfect glass, silica 
 may be regarded as the chief constituent of 
 the stone; but if the vitrification be very 
 imperfect and the bulk much increased, alu- 
 mina may be supposed to predominate. A 
 brownish or dull green colour indicates the 
 presence of iron ; a bright grass-green, 
 which is imparted to water, that of manga- 
 
 ANA 
 
 nese ; and from a greenish-yellow, chromium 
 may bo expected. The crucible, still a lit- 
 tle hot, being first wiped, is put into a cap- 
 side of porcelain or platinum ; w hen, warm 
 distilled water is poured upon the alkaline 
 earthy mass, to detach it from the crucible. 
 Having transferred the whole of it into the 
 capsule, muriatic acid is poured on, and a 
 gentle heat applied, if necessary, to accom- 
 plish its solution. If the liquid be of an 
 orange-red colour, w r e infer the presence of 
 iron; if of a golden-yellow, that of chro- 
 mium ; and if of a purplish-red, that of 
 manganese. The solution is next to be 
 evaporated to dryness, on a sand-bath, or 
 over a lamp, taking care so to regulate the 
 heat, that no particles lie thrown out. To- 
 wards the end of the evaporation, it assumes 
 a gelatinous consistence. At this period it 
 must be stirred frequently with a platinum 
 spatula or glass rod, to promote the disen- 
 gagement of the muriatic acid gas. After 
 this, the heat may be raised to fully 212° F. 
 for a few minutes. Ilot water is to be now 
 poured on in considerable abundance, w’bich 
 dissolves every thing except the silica. ISy 
 filtration, this earth is separated from the li- 
 quid ; and being edulcorated w ith hot water, 
 it is then dried, ignited, and weighed. It 
 constitutes a fine wdiite powder, insoluble in 
 acids, and feeling gritty between the teeth. 
 If it be coloured, a little dilute muriatic acid 
 must be digested on it, to remove the adher- 
 ing metallic particles, which must be added 
 to the first solution. This must now be re- 
 duced by evaporation to the bulk of half a 
 pint. Carbonate of potash being then add- 
 ed, till it indicates alkaline excess, the li- 
 quid must be made to boil for a little. A 
 copious precipitation of the earth and oxides 
 is thus produced. The whole is thrown on 
 a filter, and after it is so drained as to as- 
 sume a semi-solid consistence, it is removed 
 by a platinum blade, and boiled in a cap- 
 sule for some time, with solution of pure 
 potash. Alumina and glucina are thus dis- 
 solved, while the other earths and the me- 
 tallic oxides remain. 
 
 This alkalino-earthy solution, separated 
 from the rest by filtration, is to be treated 
 w ith an excess of muriatic acid ; after which 
 carbonate of ammonia being added also in 
 excess, the alumina is thrown down while 
 the glucina continues dissolved. The first 
 earth separated by filtration, washed, dried, 
 and ignited, gives the quantity of alumina., 
 The nature of this may he further demon- 
 strated, by treating it with dilute sulphuric 
 acid, and sulphate of potash, both in equiva- 
 lent quantities, when the w hole will be con- 
 verted into alum. (See Alum). The fil- 
 tered liquid will deposit its glucina, on dis- 
 sipating the ammonia, by ebullition. It is 
 to be separated by filtration, to be washed, 
 ignited, and weighed. 
 
ANA 
 
 ANA 
 
 1 he matter mulissolved by the digestion 
 of the liquid potash, may consist of lime, 
 magnesia, and metallic oxides. Dilute sul- 
 phuric acid must be digested on it for some 
 time. -The solution is to be evaporated to 
 dryness, and heated to expel the excess of 
 acid. 1 he saline solid matter being now 
 diffused in a moderate quantity of water, the 
 sulphate of magnesia will be dissolved, and 
 along with the metallic sulphates, may be 
 separated from the sulphate of lime by the 
 filter. The latter being washed with a little 
 water, dried, ignited, and weighed, gives, by 
 the scale of equivalents, the quantity of lime 
 in the mineral. The magnesian and metal- 
 lic solution being diluted with a large quan- 
 tity of water, is to be treated with bicarbo- 
 nate of potash, which will precipitate the 
 nickel, iron, and chromium, but retain the 
 magnesia and manganese, by the excess of 
 carbonic acid. Hydrosulphuret of potash 
 will throw down the manganese, from the 
 magnesian solution. The addition of pure 
 potash, aided by gentle ebullition, will then 
 precipitate the magnesia. The oxide of 
 manganese may be freed from the sulphu- 
 retted hydrogen, by ustulation. 
 
 The mingled metallic oxides must he di- 
 gested with abundance of nitric acid, to aci- 
 dify the chromium. The liquid is next 
 treated with potash, which forms a soluble 
 chromate, while it throws down the iron and 
 nickel. The chromic acid may be separated 
 from the potash by muriatic acid, and diges- 
 tion with heat, washed, dried till it becomes 
 a green oxide, and weighed. The nickel is 
 separated from the iron, by treating their 
 solution in muriatic acid, with water of am- 
 monia. The latter oxide which falls, may 
 be separated by the filter, dried and weighed. 
 By evaporating the liquid, and exposing the 
 dry residue to a moderate heat, the amraoni- 
 acal salt will sublime and leave the oxide of 
 nickel behind. The whole separate weights 
 must now be collected in one amount, and 
 if they constitute a sum within two per cent 
 of the primitive weight, the analysis may he 
 regarded as giving a satisfactory account of 
 the composition of the mineral. But if the 
 deficiency be considerable, then some vola- 
 tile ingredient, or some alkali or alkaline 
 salt, may be suspected. 
 
 A portion of the mineral broken into 
 small fragments, is to be ignited in a porce- 
 lain retort, to which a refrigerated receiver 
 is fitted. The water or other volatile and 
 condensable matter, if any be present, will 
 thus he obtained. But if no loss of weight 
 be sustained by ignition, alkali, or a volatile 
 acid, may be looked for. The latter is usual- 
 ly the fluoric. It may be expelled by 
 digestion with sulphuric acid. it is ex- 
 actly characterized by its property of corrod- 
 ing glass.* 
 
 Beside this general method, some others 
 may be used in particular cases. 
 
 lbus, to discover a small proportion of 
 alumina or magnesia in a solution of a large 
 quantity of lime, pure ammonia may be ap- 
 plied, which will precipitate the alumina or 
 magnesia (if any he), but not the lime. 
 Distilled vinegar applied to the precipitate 
 will discover whether it be alumina or mag- 
 nesia. 
 
 2dly , A minute portion of lime or bary- 
 tes, in a solution of alumina or magnesia, 
 may be discovered by the sulphuric acid, 
 which precipitates the lime and barytes : the 
 solution should be dilute, else the alumina 
 also would be precipitated. Jf there be not 
 an excess of acid, the oxalic acid is still a nicer 
 test of lime: 100 grains of gypsum contain 
 about 33 of lime; 100 grains of sulphate of 
 barytes contain 66 of barytes; 100 grains of 
 oxalate of lime contain 43.8 of lime. The 
 insolubility of sulphate of barytes in 500 
 times its weight of boiling water, sufficiently 
 distinguishes it. From these data the quan- 
 tities are easily investigated. 
 
 3 dly, A minute proportion of alumina in 
 a large quantity of magnesia may be disco- 
 vered, either by precipitating the whole, 
 and treating it with distilled vinegar; or by 
 heating the solution nearly to ebullition, 
 and adding more carbonate of magnesia, un- 
 til the solution is perfectly neutral, which it 
 never is when alumina is contained in it, as 
 this requires an excess of acid to keep it in 
 solution. By these means the alumina is 
 precipitated in the state of embryon alum, 
 which contains about half its weight of alu- 
 mina (or, for greater exactness, it may be 
 decomposed by boiling it in volatile alkali). 
 After the precipitation the solution should 
 be largely diluted, as the sulphate of mag- 
 nesia, which remained in solution while hot, 
 would precipitate when cold, and mix with 
 the embryon alum. 
 
 4 Ikly, A minute portion of magnesia in 
 a large quantity of alumina is best separated 
 by precipitating the whole, and treating the 
 precipitate with distilled vinegar. 
 
 Lastly, Lime and barytes are separated 
 by precipitating both with the sulphuric 
 acid, and evaporating the solution to a small 
 compass, pouring off the liquor, and treating 
 the dried precipitate with 500 times its 
 weight of boiling water ; what remains un- 
 
 O O 7 
 
 dissolved is sulphate of barytes. 
 
 The inconveniences of employing much 
 heat, are obvious, and Mr Lowitz informs 
 us, that they may be avoided without the 
 least disadvantage. Over the dame of a 
 spirit lamp, that will hold an ounce and 
 half, and is placed in a cylindrical tin fur- 
 nace four inches high and three in diameter, 
 with air-holes, and a cover perforated to 
 hold the crucible, he boils the stone prepar- 
 
 6 
 
ANA 
 
 ANA 
 
 
 
 
 . I 
 
 
 eel as directed above, stirring it frequently. 
 His crucible, which, as well as the spatula, 
 is of very fine silver, holds two ounces and 
 a half, or three ounces. As soon as the mat- 
 ter is boiled dry, he pours in as much hot 
 water as he used at first ; and this he re- 
 peats two or three times more, if the refrac- 
 toriness of the fossil require it. Large tough 
 bubbles arising during the boiling, are in ge- 
 neral a sign that the process will be attend- 
 ed with success. Even the sapphire, though 
 the most refractory of all Mr Lowitz tried, 
 was not more so in this than in the dry way. 
 
 SirH. Davy observes, that the boracic acid 
 is very useful in analyzing stones that con- 
 tain a fixed alkali ; as its attraction for the 
 different earths at the heat of ignition is 
 considerable, and the compounds it forms 
 with them are easily decomposed by the 
 mineral acids dissolved In w r ater. His pro- 
 cess is as follows: Let 100 grains of the 
 stone to be examined be reduced to a fine 
 powder, mixed with 200 grains of boracic 
 acid, and fused for about half an hour at a 
 strong red heat in a crucible of platina or 
 silver. Digest the fused mass in an ounce 
 and half of nitric acid diluted with seven or 
 eight times the quantity of water, till the 
 whole is decomposed ; and then evaporate 
 the solution till it is reduced to an ounce and 
 half, or tw r o ounces. If the stone contained 
 silcx, it will separate in this process, and 
 must be collected on a filter, and edulco- 
 rated with distilled water, to separate the 
 saline matter. The fluid, mixed with all 
 the water that has been passed through the 
 filter, being evaporated till reduced to about 
 half a pint, is to be saturated with carbonate 
 of ammonia, and boiled with an excess of 
 this salt, till all that will precipitate has 
 fallen down. The earths and metallic 
 oxides being separated by filtration, mix 
 nitric acid with the clear fluid till it has a 
 strongly sour taste, and then evaporate till 
 the boracic acid remains free. Filter the 
 fluid, evaporate it to dryness, and expose it 
 to a heat of 450° F* when the nitrate of am- 
 monia will be decomposed, and the nitrate 
 of potash or soda will remain in the vessel. 
 The earths and metallic oxides, that re- 
 mained on the filter, may be distinguished 
 by the common processes. The alumina 
 may be separated by solution of potash, the 
 lime by sulphuric acid, the oxide of iron by 
 succinate of ammonia, the manganese by 
 hydrosulphuret of potash, and the magnesia 
 by pure soda. 
 
 * Lately carbonate or nitrate of barytes 
 has been introduced into mineral analysis 
 with great advantage, for the fluxing of 
 stones, that may contain alkaline matter. 
 See the English Translation of M. The- 
 nard’s volume on analysis.* 
 
 Under the head of mineral analysis no- 
 thing is of so much general importance as 
 
 the examination of soils, with a view to the 
 improvement of such as are less productive, 
 by supplying the ingredients they want in 
 due proportions to increase their fertility. 
 To Lord Dundonald and Mr Kirvvan we are 
 much indebted for their labours in this field 
 of inquiry ; but Sir H. Davy, assisted by the 
 labours of these gentlemen, the facts and ob- 
 servations of Mr Young, and his own skill 
 in chemistry, having given at large, in a 
 manner best adapted for the use of the prac- 
 tical farmer, an account of the methods to 
 be pursued for this purpose, we shall here 
 copy them. 
 
 The substances found in soils are certain 
 mixtures or combinations of some of the 
 primitive earths, animal and vegetable mat- 
 ter in a decomposing state, certain saline 
 compounds, and the oxide of iron. These 
 bodies always retain water, and exist in very 
 different proportions in different lands, and 
 the end of analytical experiments is the de- 
 tection of their quantities and mode of union. 
 
 The earths commonly found in soils are 
 principally silex, or the earth of flints ; alu- 
 mina, or the pure matter of clay ; lime, or 
 calcareous earth ; and magnesia : for the 
 characters of which see the articles. Silex 
 composes a considerable part of hard gra- 
 velly soils, hard sandy soils, and hard stony 
 lands. Alumina abounds most in clayey 
 soils, and clayey loams ; but even in the 
 smallest particles of these soils it is generally 
 united with silex find oxide of iron. Lime 
 always exists in soils in a state of combina- 
 tion, and chiefly with carbonic acid, when it 
 is called carbonate of lime. This carbonate 
 in its hardest state is marble ; in its softest, 
 chalk. Lime united with sulphuric acid is 
 sulphate of lime, or gypsum ; with phospho- 
 ric acid, phosphate of lime, or the earth of 
 bones. Carbonate of lime, mixed with 
 other substances, composes chalky soils and 
 marles, and is found in soft sandy soils. 
 Magnesia is rarely found in soils : when it 
 is, it is combined with carbonic acid, or with 
 silex and alumina. Animal decomposing 
 matter exists in different states, contains 
 much carbonaceous substance, volatile alkali, 
 inflammable aeriform pfoducts, and carbonic 
 acid. It is found chiefly in lands* lately 
 manured. Vegetable decomposing matter 
 usually contains still more carbonaceous sub- 
 stance, and differs from the preceding princi- 
 pally in not producing volatile alkali. It 
 forms a great proportion of all peats, abounds 
 in rich mould, and is found in larger or 
 smaller quantities in all lands. The saline 
 compounds are few, and in small quantity : 
 they are chiefly muriate of soda, or common 
 salt, sulphate of magnesia, muriate and sul- 
 phate of potash, nitrate of lime, and the 
 mild alkalis. Oxide of iron, which is the 
 same with the rust produced by exposing 
 iron to air and water, is found in all soils, 
 L 
 
ANA 
 
 ANA 
 
 but most abundantly in red and yellow clays, 
 and red and yellow siliceous sands. 
 
 The instruments requisite for the analysis 
 ot soils are few. A pair of scales capable of 
 holding a quarter of a pound of common 
 soil, and turning with a single grain when 
 loaded : a set of weights, from a quarter of 
 a pound troy to a grain : a wire sieve, coarse 
 enough to let a peppercorn passthrough : an 
 Argand lamp and stand : a few glass bottles, 
 Hessian crucibles, and china or queen’s ware 
 evaporating basins : a Wedgwood pestle and 
 mortar : some filters made of half a sheet 
 of blotting paper, folded so as to contain a 
 pint of liquid, and greased at the edges : a 
 bone knife : and an apparatus for collecting 
 and measuring aeriform fluids. 
 
 The reagents necessary are muriatic acid, 
 sulphuric acid, pure volatile alkali dissolved 
 in water, solution of prussiate of potash, 
 soap lye, and solutions of carbonate of am- 
 monia, muriate of ammonia, neutral carbo- 
 nate of potash, and nitrate of ammonia. 
 
 1. When the general nature of the soil of 
 a field is to be ascertained, specimens ot it 
 should be taken from different places, two 
 or three inches below the surface, and exa- 
 mined as to the similarity of their proper- 
 ties. It sometimes happens, that on plains 
 the whole of the upper stratum of the land 
 is of the same kind, and in this case one 
 analysis will be sufficient. Hut in valleys, 
 and near the beds of rivers, there are very 
 great differences, and it now and then oc- 
 
 O ' t 
 
 curs, that one part of a field is calcareous, 
 and another part siliceous ; and in this and 
 analogous cases, the portion different from 
 each other should be analyzed separately. 
 Soils when collected, if they cannot be ex- 
 amined immediately, should be preserved in 
 phials quite filled with them, and closed with 
 ground glass stopples. The most convenient 
 quantity for a perfect analysis is from two 
 hundred grains to four hundred. It should 
 he collected in dry weather, and exposed to 
 the air till it feels dry. Its specific gravity 
 may be ascertained, by introducing into a 
 phial, which will contain a known quantity 
 of water, equal bulks of water and of the 
 soil ; which may easily he done, by pouring 
 in water till the phial is halt full, and then 
 adding the soil till the fluid rises to the 
 mouth. The difference between the weight 
 of the water, and that of the soil, will give 
 the result. Then if the bottle will contain 
 four hundred grains of water, and gains two 
 hundred grains when half filled with water 
 and half with soil, the specific gravity of the 
 soil will be 2 ; that is, it will he twice as 
 heavy as water : and if it gained one hun- 
 dred and sixty-five grains, its specific gravity 
 would be 1825, water being 1000. It is of 
 importance that the specific gravity of a soil 
 should be known, as it affords an indication 
 of the quantity of animal and vegetable mat- 
 ter it contains, these substances being always 
 
 most abundant in the lighter soils. The 
 other physical properties of soils should like- 
 wise be examined before the analysis is made, 
 as they denote, to a certain extent, their 
 composition, and serve as guides in directing 
 the experiments. Thus siliceous soils are 
 generally rough to the touch, and scratch 
 glass when rubbed upon it : aluminous soils 
 adhere strongly to the tongue, and emit a 
 strong earthy smell when breathed upon : 
 and calcareous soils are soft, and much less 
 adhesive than aluminous soils. 
 
 2. Soils, when as dry as they can be made 
 by exposure to the air, still retain a consi- 
 derable quantity of water, which adheres 
 ■with great obstinacy to them, and cannot be 
 driven off' without considerable heat : ami 
 the first process of analysis is to free them 
 from as much of this water as possible, with- 
 out affecting their composition in other re- 
 spects. This may be done by heating the 
 soil for ten or twelve minutes in a china 
 basin over an Argand lamp, at a tempera- 
 ture equal to 300° F. ; and if a thermometer 
 be not used, the proper degree of heat may 
 easily be ascertained by keeping a piece of 
 wood in the basin in contact with its bot- 
 tom ; for as long as the colour of the wood 
 remains unaltered, the heat is not too high ; 
 but as soon as it begins to be charred, the 
 process must be stopped. In several expe- 
 riments, in which Sir H. Davy collected the 
 water that came over at this degree of heat, 
 he found it pure, without any sensible quan- 
 tity of other volatile matter being produced. 
 The loss of w-eight in this process must be 
 carefully noted ; and if it amount to 50 
 grains in 400 of the soil, this may be con- 
 sidered as in the greatest degree absorbent 
 and retentive of water, and will generally be 
 found to contain a large proportion of alu- 
 minous earth : if the loss be not more than 
 1 0 or 20 grains, the land may be considered 
 as slightly absorbent and retentive, and the 
 siliceous earth as most abundant. 
 
 3 . None of the loose stones, gravel, or 
 large vegetable fibres, should be separated 
 from the soil, till the water is thus expelled ; 
 for these bodies are often highly absorbent 
 and retentive, and consequently influence the 
 fertility of the land. But after the soil has 
 been heated as above, these should be sepa- 
 rated by the sieve, after the soil has been 
 gently bruised in a mortar. The weights of 
 the vegetable fibres or wood, and of the 
 gravel and stones, should be separately noted 
 down, and the nature of the latter ascertain- 
 ed : if they be calcareous, they will effervesce 
 with acids ; if siliceous, they will scratch 
 glass ; if aluminous, they will be soft, easily 
 scratched with a knife, and incapable of ef- 
 fervescing with acids. 
 
 4. Most soils, beside stones and gravely 
 contain larger or smaller proportions of 
 sand of different degrees of fineness ; and 
 the next operation necessary is to separate 
 
ANA 
 
 ANA 
 
 this sand from the parts more minutely di- 
 vided, such as clay, loam, marl, and vege- 
 table and animal matter. This may be done 
 sufficiently by mixing the soil well with 
 water ; as the coarse sand will generally fall 
 to the bottom in the space of a minute, and 
 the liner in two or three ; so that by pouring 
 the water off after one, two, or three minutes, 
 the sand will be for the most part separated 
 from the other substances ; which, with the 
 water containing them, must be poured into 
 a filter. After the water has passed through, 
 what remains on the filter must be dried and 
 weighed ; as must also the sand ; and their 
 respective quantities must be noted down. 
 The water must be preserved, as it will con- 
 tain the saline matter, and the soluble animal 
 or vegetable matter, if any existed in the soil. 
 
 5. A minute analysis of the sand thus se- 
 parated is seldom or never necessary, and 
 its nature may be detected in the same way 
 as that of the stones and gravel. It is al- 
 ways siliceous sand, or calcareous sand, or 
 both together. If it consist wholly of car- 
 bonate of lime, it will dissolve rapidly in 
 muriatic acid with effervescence ; but if it 
 consists partly of this and partly of siliceous 
 matter, a residuum will be left after the 
 acid has ceased to act on it, the acid being 
 added till the mixture has a sour taste, and 
 has ceased to effervesce. This residuum is 
 the siliceous part ; which being washed, 
 dried, and heated strongly in a crucible, the 
 difference of its weight from that of the 
 whole, will indicate the quantity of the cal- 
 careous sand. 
 
 6. The finely divided matter of the soil is 
 usually very compound in its nature ; it 
 sometimes contains all the four primitive 
 earths of soils, as well as animal and vege- 
 table matter ; and to ascertain the propor- 
 tions of these with tolerable accuracy, is the 
 most difficult part of the subject. The first 
 process to be performed in this part of the 
 analysis is the exposure of the fine matter of 
 the soil to the action of muriatic acid. This 
 acid, diluted with double its bulk of water, 
 should be poured upon the earthy matter in 
 an evaporating basin, in a quantity equal to 
 twice the weight of the earthy matter. The 
 mixture should be often stirred, and suffered 
 to remain for an hour, or an hour and half, 
 before it is examined. If any carbonate of 
 lime, or of magnesia, exist in the soil, they 
 will have been dissolved in this time by the 
 acid, which sometimes takes up likewise a 
 little oxide of iron, but very seldom any 
 alumina. The fluid should be passed through 
 a filter; the solid matter collected, washed 
 with distilled or rain water, dried at a mo- 
 derate heat, and weighed. Its loss will de- 
 note the quantity of solid matter taken up. 
 The washings must be added to the solution ; 
 which, if not sour to the taste, must be 
 made so by the addition of fresh acid ; and 
 
 a little solution of prussiate of potash must 
 be mixed with the liquor. If a blue preci- 
 pitate occur, it denotes the presence of oxide 
 of iron, and the solution of the prussiate 
 must be dropped in, till no further effect is 
 produced. To ascertain its quantity, it must 
 be collected on a filter in the same manner 
 as the other solid precipitates, and heated 
 red : the result will be oxide of iron. Into 
 the fluid freed from oxide of iron a solution 
 of carbonate of potash must be poured till 
 all effervescence ceases in it, and till its taste 
 and smell indicate a considerable excess of 
 alkaline salt. The precipitate that falls 
 down is carbonate of lime ; which must be 
 collected on a filter, dried at a heat below 
 that of redness, and afterward weighed. 
 The remaining fluid must be boiled for a 
 quarter of an hour, when the magnesia, if 
 there be any, will be precipitated combined 
 with carbonic acid, and its quantity must be 
 ascertained in the same manner as that of 
 the carbonate of lime. If any minute pro- 
 portion of alumina should, from peculiar 
 circumstances, be dissolved by the acid, it 
 will be found in the precipitate with the 
 carbonate of lime, and it may be separated 
 from it by boiling for a few minutes with 
 soap lye sufficient to cover the solid matter : 
 for this lye dissolves alumina, without acting 
 upon carbonate of lime. Should the finely 
 divided soil be sufficiently calcareous to 
 effervesce very strongly with acids, a simple 
 method of ascertaining the quantity of car- 
 bonate of lime, sufficiently accurate in all 
 common cases, may be adopted. As car- 
 bonate of lime in all its states contains a de- 
 terminate quantity of acid, which is about 
 4 5 parts in a hundred by w r eight, the quan- 
 tity of this acid given out during the effer- 
 vescence occasioned by its solution in a 
 stronger acid, will indicate the quantity of 
 carbonate of lime present. Thus, if you 
 weigh separately one part of the matter of 
 the soil, and tw o parts of the acid diluted 
 with an equal quantity of w r ater, and mix 
 the acid slowly in small portions with the 
 soil, till it ceases to occasion any effeives- 
 cence, by weighing the mixture, and the 
 acid that remains, you will find the quan- 
 tity of carbonic acid lost ; and for every four 
 grains and half so lost you will estimate tea 
 grains of carbonate of lime. You may also 
 collect the carbonic acid in the pneumatic 
 apparatus for the analysis of soils, described 
 in the article Laboratory ; and allow for 
 every ounce measure of the carbonic acid, tw r o 
 grains of carbonate of lime. 
 
 7. The quantity of insoluble animal and 
 vegetable matter may next be ascertained 
 with sufficient precision, by heating it to a 
 strong red heat in a crucible over a common 
 fire, till no blackness remains in the mass, 
 stirring it frequently meanwhile with a me- 
 tallic wire. The loss of weight will ascer- 
 
ANA 
 
 ANA 
 
 tain the quantity of animal and vegetable 
 matter there was, but not the proportions of 
 each. It the smell emitted, during this pro- 
 cess, resemble that of burnt feathers, it is a 
 certain indication of the presence of some 
 animal matter ; and a copious blue flame 
 almost always denotes a considerable propor- 
 tion ot vegetable matter. Nitrate of ammo- 
 tiia, in the proportion of twenty grains to a 
 hundred of the residuum of the soil, will 
 greatly accelerate this process, if the operator 
 be in haste; and not affect the result, as it 
 will be decomposed and evaporate. 
 
 8. What remains after this decomposition 
 or* the vegetable and animal matter, consists 
 generally of minute particles of earthy mat- 
 ter, which are usually a mixture of alumina 
 and silex with oxide of iron. To separate 
 these, boil them two or three hours in sul- 
 phuric acid diluted with four times its 
 weight of water, allowing a hundred and 
 twenty grains of acid for every hundred 
 grains of the residuum. If any thing remain 
 undissolved by this acid, it may be consi- 
 dered as silex, and be separated, washed, 
 dried, and weighed, in the usual manner. 
 Carbonate of ammonia being added to the 
 solution in quantity more than sufficient to 
 saturate the acid, the alumina will be pre- 
 cipitated ; and the oxide of iron, if any, 
 may be separated from the remaining liquid 
 by boiling it. It scarcely ever happens, 
 that any magnesia or lime escapes solution 
 in the muriatic acid ; but if it should, it 
 will be found in the sulphuric acid ; from 
 which it may be separated as directed above 
 for the muriatic. This method of analysis 
 is sufficiently precise for all common pur- 
 poses : but if very great accuracy be an ob- 
 ject, the residuum after the incineration 
 must be treated with potash, and in the 
 manner in which stones are analyzed, as 
 given in the first part of this article. 
 
 9. If the soil contained any salts, or solu- 
 ble vegetable or animal matter, they will be 
 found in the water used for separating the 
 sand. This water must be evaporated to 
 dryness at a heat below boiling. If the solid 
 matter left be of a brown colour, and in- 
 flammable, it may be considered as partly 
 vegetable extract. If its smell, when ex- 
 posed to heat, be strong and fetid, it con- 
 tains animal mucilaginous, or gelatinous 
 matter. If it be white and transparent, it 
 may be considered as principally saline. 
 Nitrate of potash or of lime is indicated in 
 this saline matter by its sparkling when 
 thrown on burning coals ; sulphate of mag- 
 nesia may be detected by its bitter taste : 
 and sulphate of potash produces no alteration 
 in a solution of carbonate of ammonia, but 
 precipitates a solution of muriate of barytes. 
 
 10. If sulphate or phosphate of lime be 
 suspected in the soil, a particular process is 
 requisite to detect it, A given weight of 
 
 the entire soil, as four hundred grains for 
 instance, must be mixed with One-third as 
 much powdered charcoal, and kept at a red 
 heat in a crucible for half an hour. The 
 mixture must then be boiled a quarter of an 
 hour in half a pint of water, and the solu- 
 tion, being filtered, exposed some days to 
 the open air. If any soluble quantity of 
 sulphate of lime, or gypsum, existed in the 
 soil, a white precipitate will gradually form 
 in the fluid, and the weight of it will indicate 
 the proportion. 
 
 Phosphate of lime, if any be present, may 
 be separated from the soil after the process 
 for gypsum. Muriatic acid must be di- 
 gested upon the soil in quantity more than 
 sufficient to saturate the soluble earths. 
 The solution must be evaporated, and water 
 poured upon the solid matter. This fluid 
 will dissolve the compounds of earths with 
 the muriatic acid, and leave the phosphate 
 of lime untouched. 
 
 11. When the examination of a soil is 
 completed, the products should be classed, 
 and their quantities added together ; and if 
 they nearly equal the original quantity of 
 soil, the analysis may he considered as ac- 
 curate. It must however be observed, that 
 when phosphate or sulphate of lime is disco- 
 vered by the independent process, No. 10. 
 just mentioned, a correction must be made 
 for the general process, by subtracting a 
 sum equal to their weight from the quan- 
 tity of carbonate of lime obtained by preci- 
 pitation from the muriatic acid. In arrang- 
 ing the products, the form should be in the 
 order of the experiments by which they are 
 obtained. Thus 400 grains of a good sili- 
 ceous sandy soil may be supposed to con- 
 tain grains. 
 
 Of water of absorption, - - 18 
 
 Of loose stones and gravel, principally 
 
 siliceous, - - - - 42 
 
 Of undecompounded vegetable fibres, 10 
 Of fine siliceous sand, - - 200 
 
 Of minutely divided matter, separated 
 by filtration, and consisting of, 
 Carbonate of lime, - - 2.5 
 
 Carbonate of magnesia, - 4 
 
 Matter destructible by beat, prin- 
 cipally vegetable, - - 10 
 
 Silex, - - 40 
 
 Alumina, - - - 52 
 
 Oxide of iron, 4 
 
 Soluble matter, principally sul- 
 phate of potash and vegetable 
 extract, 5 
 
 Gypsum, 3 
 
 Phosphate of lime, 2 
 
 — 125 
 
 Amount of all the products, 395 
 Loss, _ - - 5 
 
 400 
 
ANA 
 
 ANA 
 
 In this instance the loss is supposed small ; 
 but in general, in actual experiments, it will 
 be found much greater, in consequence of 
 the difficulty of collecting the whole quan- 
 tities of the different precipitates ; and when 
 it is within thirty for four hundred grains, 
 there is no reason to suspect any want of due 
 precision in the processes. 
 
 12. When the experimenter is become 
 acquainted with the use of the different in- 
 struments, the properties of the reagents, 
 and the relations between the external and 
 chemical qualities of soils, he will seldom 
 find it necessary to perform, in any one case, 
 all the processes that have been described. 
 When his soil, for instance, contains no not- 
 able proportion of calcareous matter, the ac- 
 tion of the muriatic acid, No. 6. may be 
 omitted : in examining peat soils, he will 
 principally have to attend to the operation 
 by fire and air, No. 7. : and in the analysis 
 of chalks and loams, he will often be able 
 to omit the experiment with sulphuric acid, 
 No. 8. 
 
 In the first trials that are made by persons 
 unacquainted with chemistry, they must not 
 expect much precision of result. Many dif- 
 ficulties will be met with ; but in overcom- 
 ing them the most useful kind of practical 
 knowledge will be obtained ; and nothing is 
 so instructive in experimental science as the 
 detection of mistakes. The correct analyst 
 ought to be well grounded in general che- 
 mical information ; but perhaps there is no 
 better mode of gaining it than that of at- 
 tempting original investigations. In pursu- 
 ing his experiments, he will be continually 
 obliged to learn from books the history of 
 the substances he is employing or acting 
 upon ; and his theoretical ideas will be more 
 valuable in being connected with practical 
 operation, and acquired for the purpose of 
 discovery. 
 
 The analysis of vegetables requires various 
 manipulations, and peculiar attention, as 
 their principles are extremely liable to be 
 altered by the processes to which they are 
 subjected. It was long before this analysis 
 was brought to any degree of perfection. 
 
 Some of the immediate materials of vege- 
 tables are separated to our hands by Nature 
 in a state of greater or less purity, as the 
 gums, resins, and balsams, that exude from 
 plants. I he expressed juices contain vari- 
 ous matters, that may be separated by the ap- 
 propriate reagents. Maceration, infusion, 
 and decoction in water, take up certain parts 
 soluble in this menstruum ; and alcohol will 
 extract others that water will not dissolve. 
 The mode of separating and distinguishing 
 these materials will easily be collected from 
 their characters, as given under the head 
 Vegetable Kingdom, and under the differ- 
 ent articles themselves. 
 
 * As the ultimate constituents of all ve- 
 
 getable substances are carbon, hydrogen, 
 and oxygen, with occasionally azote, the 
 problem of their final analysis resolves into a 
 method of ascertaining the proportion of these 
 elementary bodies. MM. Gay Lussac and 
 Thenard contrived a very elegant apparatus 
 for vegetable and animal analysis, in w'hich 
 the matter in a dried state was mixed with 
 chlorate of potash, and formed into minute 
 pellets. These pellets being projected through 
 the intervention of a stop- cock of peculiar 
 structure into an ignited glass tube, were in- 
 stantly resolved into carbonic acid and water. 
 The former product was received over mer- 
 cury, and estimated by its condensation wuth 
 potash ; the latter was intercepted by ignited 
 muriate of lime, and w r as measured by the 
 increase of w'eight which it communicates to 
 this substance. By previous trials, the 
 quantity of oxygen which a given weight of 
 the chlorate of potash yielded by ignition 
 was known ; and hence the carbon, hydro- 
 gen, and oxygen, derived from the organic 
 substance, as w r ell as the residual azote, of 
 the gaseous products. 
 
 M. Berzelius modified the above appara- 
 tus, and employed the organic product in 
 combination with a base, generally oxide of 
 lead. He mixed a certain w r eight of this 
 neutral compound with a known quantity of 
 pure chlorate of potash, and triturated the 
 whole with a large quantity of muriate of 
 soda, for the purpose of moderating the sub- 
 sequent combustion. This mingled dry pow r - 
 der is put into a glass tube about half an inch 
 diameter, and eight or ten inches long, which 
 is partially enclosed in a fold of tin-plate, 
 hooped with iron w r ire. One end of the tube 
 is hermetically sealed beforehand, the other 
 is now’ drawn to a pretty fine point by the 
 blow-pipe. This termination is inserted into 
 a glass globe about an inch diameter, which 
 joins it to a long tube containing dry mu- 
 riate of lime in its middle, and dipping at 
 its other extremity into the mercury of a 
 pneumatic trough. The first tube, with its 
 protecting tin case, being exposed gradually 
 to ignition, the enclosed materials are re- 
 solved into carbonic acid, w r ater, and azote, 
 which come over, and are estimated as above 
 described. M. Gay Lussac has more re- 
 cently employed peroxide of copper to mix 
 with the organic substance to be analyzed ; 
 because while it yields its oxygen to hydro- 
 gen and carbon, it is not acted on by azote ; 
 and thus the errors resulting from the for- 
 mation of nitric acid with the chlorate of 
 potash are avoided. Berzelius has afforded 
 satisfactory evidence by his analyses, that the 
 simple apparatus which he employed is ade- 
 quate to every purpose of chemical research. 
 Dr 1 rout has described, in the Annals of 
 Philosophy for March 1820, a very neat 
 form of apparatus for completing analyses of 
 organic substances with the heat of a lamp . 
 
ANH 
 
 ANI 
 
 Hydrogen having the power in minute quan- 
 tities of modifying the constitution of the 
 organic bodies, requires to be estimated with 
 corresponding minuteness. Mr Porrett has 
 very ingeniously suggested, that its quantity 
 may be more accurately determined by the 
 proportion of oxide of copper that is revived, 
 than by the product of water. Dilute sul- 
 phuric acid being digested on the residual 
 cupreous powder, will instantly dissolve the 
 oxide, and leave the reduced metal ; whose 
 weight will indicate, by the scale of equiva- 
 lents, the hydrogen expended in its reduc- 
 tion. One of hydrogen corresponds to 9 of 
 water, and to 32 of copper. 
 
 Under the different vegetable and animal 
 products, we shall take care to state their 
 ultimate constituents by the most correct 
 and recent analyses. The peculiar substan- 
 ces which water, alcohol, ether, and other 
 solvents, can separate from an organic body, 
 may be called the immediate products of the 
 vegetable or animal kingdom ; while the 
 carbon, hydrogen, oxygen, and azote, dis- 
 coverable by igneous analysis, are the ulti- 
 mate constituent elements. To the former 
 class belong sugar, gum, starch, oils, resins, 
 gelatin, urea, organic acids, and alkalis, &c. 
 which see.* 
 
 '* Anatase. Octohedritc, oxide of tita- 
 nium, rutile, and titane rutile. This mine- 
 ral shews a variety of colours by reflected 
 light, from indigo blue to reddish brown. 
 I3y transmitted light, it appears greenish- 
 yellow. It is found usually in small crys- 
 tals, octohedrons, with isosceles triangular 
 faces. Structure lamellar ; it is semi-trans- 
 parent, or opaque, fragments splendent, ada- 
 mantine, scratches glass, brittle, sp. gr. 3.85. 
 It is a pure oxide of titanium. It has 
 been found only in Dauphiny and Norway ; 
 and is a very rare mineral. It occurs in 
 granite, gneis, mica slate, and transition lime- 
 stone. * 
 
 * Andalusite. A massive mineral, of a 
 flesh and sometimes rose-red colour. It is, 
 however, occasionally crystallized in rectan- 
 gular four-sided prisms, verging on rhom- 
 boids. The structure of the prisms is lamel- 
 lar, with joints parallel to their sides. Trans- 
 lucent, scratches quartz ; is easily broken ; 
 sp. gr. 3.16'5, Infusible by the blow-pipe; 
 in which respect it differs from felspar, 
 though called felspath apyre by Haiiy. It 
 is composed of 52 alumina, 32 silica, 8 pot- 
 ash, 2 oxide of iron, and 6 loss. Vauq, It 
 belongs to primitive countries, and was first 
 found in Andalusia in Spain. It is found 
 in mica slate in Aberdeenshire, and in the 
 Isle of Unst ; Dartmoor in Devonshire ; 
 in mica slate at Killiney, near Dublin, and 
 at Douce Mountain, county Wicklow.* 
 
 * Andreolite. See IIarmotome.* 
 
 * Anhydrite. Anhydrous gypsum. There 
 are six varieties of it.— 
 
 1 . Compact, has various shades, of white, 
 blue, and red; massive and kidney-shaped ; 
 dull aspect ; splintery or conchoidal fracture ; 
 translucent on the edges ; is scratched by 
 fluor, but scratches calc spar ; somewhat 
 tough ; specific gravity 2.850. It is dry 
 sulphate of lime, with a trace of sea salt. 
 It is found in the salt mines of Austria and 
 Salzburg, and at the foot of the Harz moun- 
 tains. 2. Granular, the scaly of Jameson. 
 Is found in massive concretions, of which 
 the structure is confusedly foliated. White 
 or bluish colour, of a pearly lustre ; compo- 
 sition as above, with one per cent of sea salt. 
 It occurs in the salt mines of Halle ; sp. gr. 
 2.957. 3. Fibrous. Massive; glimmering, 
 
 pearly lustre ; fracture in delicate parallel 
 fibres ; scarcely translucent ; easily broken. 
 Found at Halle, Ischel, and near Bruns- 
 wick. 4. Radiated. Blue, sometimes spotted 
 with red ; radiated, splendent fracture ; partly 
 splintery ; translucent ; not hard ; sp. gr. 
 2.940. 5. Spany, or cube spar. Milk- 
 
 white colour, passing sometimes into greyish 
 and reddish white ; short four-sided prisms, 
 having two of the opposite sides much broader 
 than the other two ; and occasionally the 
 lateral edges are truncated, whence results 
 an eight-sided prism ; lustre, splendent, pear- 
 ly. Foliated fracture. Threefold rectangu- 
 lar cleavage. Cubical fragments. Trans- 
 lucent. Scratches calc spar. Brittle. Sp. 
 gr. 2.9. This is the muriacite of some 
 writers. It is doubly refracting. It is said 
 to contain one per cent of sea salt. It is 
 found at Bex in Switzerland, and Halle in 
 the Tyrol. 6. Siliciferous, or vulpinite. 
 Massive concretions of a laminated structure, 
 translucent on the edges, splendent, and brit- 
 tle. Greyish white, veined with bluish grey. 
 Sp. gr. 2.88, It contains eight per cent 
 silex. The rest is sulphate of lime. It is 
 called by statuaries, Marmo bardiglio di Ber- 
 gamo, and takes a fine polish. It derives its 
 name from Vulpino in Italy, where it accom- 
 panies lime.* 
 
 Anil, or Nil. This plant, from the 
 leaves of which indigo is prepared, grows in 
 America. 
 
 Animal Kingdom. Hie various bodies 
 around us, which form the objects of che- 
 mical research, have all undergone a num- 
 ber of combinations and decompositions be- 
 fore we take them in hand for examination. 
 These are all consequences of the same at- 
 tractions or specific properties that we avail 
 ourselves of, and are modified likewise by 
 virtue of the situations and temperatures of 
 the bodies presented to each other. In the 
 great mass of unorganized matter, the com- 
 binations appear to be much more simple 
 than such as take place in the vessels of or- 
 ganized beings, namely, plants and animals : 
 in the former of which there is not any pe- 
 culiar structure of tubes conveying various 
 
ANI 
 
 ANI 
 
 fluids ; and in the latter there is not only an 
 elaborate system of vessels, but likewise, for 
 the most part, an augmentation of tempera- 
 ture, From such causes as these it is, that 
 some of the substances afforded by animal 
 bodies are never found either in vegetables 
 or minerals j and so likewise in vegetables 
 are found certain products never unequivo- 
 cally met with among minerals. Hence, 
 among the systematical arrangements used 
 by chemists, the most general is that which 
 divides bodies into three kingdoms, the ani- 
 mal, the vegetable, and the mineral. 
 
 Animal, as well as vegetable bodies, may 
 be considered as peculiar apparatus for car- 
 rying on a determinate series of chemical 
 operations. Vegetables seem capable of 
 operating with fluids only, and at the tem- 
 perature of the atmosphere, as we have just 
 noticed. But most animals have a provision 
 for mechanically dividing solids by mastica- 
 tion, which answers the same purpose as 
 grinding, pounding, or levigation, does in 
 our experiments ; that is to say, it enlarges 
 the quantity of surface to be acted upon by 
 solvents. The process carried on in the 
 stomach appears to be of. the same kind as 
 that which we distinguish by the name of 
 digestion ; and the bowels, whatever other 
 uses they may serve, evidently form an ap- 
 paratus for filtering or conveying off' the fluids ; 
 while the more solid parts of the aliments, 
 which are probably of such a nature as not 
 to be rendered fluid, but by an alteration 
 which would perhaps destroy the texture of 
 the machine itself, are rejected as useless. 
 When this filtered fluid passes into the cir- 
 culatory vessels, through which it is driven 
 with considerable velocity by the mechanical 
 action of the heart, it is subjected, not only 
 to all those changes which the chemical ac- 
 tion of its parts is capable of producing, but 
 is likewise exposed to the air of the atmos- 
 phere in the lungs, into which that elastic 
 fluid is admitted by the act of respiration. 
 Here it undergoes a change of the same na- 
 ture as happens to other combustible bodies 
 when they combine with its vital part, or 
 oxygen. This vital part becomes condensed, 
 and combines with the blood, at the same 
 time that it gives out a large quantity of 
 heat, in consequence of its own capacity for 
 heat being diminished. A small portion of 
 azote likewise is absorbed, and carbonic acid 
 is given out. Some curious experiments of 
 Spallanzani show that the lungs are not the 
 sole organs by which these changes are ef- 
 fected. Worms, insects, shells of land and 
 sea animals, egg shells, fishes, dead animals, 
 and parts of animals, even after they have 
 become putrid, are capable of absorbing oxy- 
 gen from the air, and giving out carbonic 
 acid. They deprive atmospheric air of its 
 oxygen as completely as phosphorus. Shells, 
 however, lose this property when their or- 
 
 ganization is destroyed by age. Amphibia, 
 deprived of their lungs, lived much longer 
 in the open air, than others in air destitute of 
 oxygen. It is remarkable, that a larva, 
 weighing a few grains, would consume al- 
 most as much oxygen in a given time as one 
 of the amphibia a thousand times its bulk. 
 Fishes, alive and dead, animals, and parts of 
 animals, confined under water in jars, ab- 
 sorbed the oxygen of the atmospheric air 
 over the water. Muscles, tendons, bones, 
 brain, fat, and blood, all absorbed oxygen in 
 different proportions, but the blood did not 
 absorb most ; and bile appeared not to ab- 
 sorb any. 
 
 It would lead us too far from our purpose 
 if we were to attempt an explanation of the 
 little we know respecting the manner in 
 which the secretions or combinations that 
 produce the various animal and vegetable 
 substances are effected, or the uses of those 
 substances in the economy of plants and ani- 
 mals. Most of them are very different from 
 any of the products of the mineral kingdom. 
 We shall therefore only add, that these or- 
 ganized beings are so contrived, that their 
 existence continues, and all their functions 
 are performed, as long as the vessels are 
 supplied with food or materials to occupy 
 the place of such as are carried off by evapo- 
 ration from the surface, or otherwise, and as 
 long as no great change is made, either by 
 violence or disease, in those vessels, or the 
 fluids they contain. But as soon as the en- 
 tire process is interrupted in any very consi- 
 derable degree, the chemical arrangements 
 become altered, the temperature in land ani- 
 mals is changed, the minute vessels are acted 
 upon and destroyed, life ceases, and the ad- 
 mirable structure, being no longer sufficient- 
 ly perfect, loses its figure, and returns, by 
 new combinations and decompositions, to the 
 general mass of unorganized matter, with a 
 rapidity which is usually greater the more 
 elaborate its construction. 
 
 The parts of vegetable or animal substan- 
 ces may be obtained, for chemical examina- 
 tion, either by simple pressure, which empties 
 the vessels of their contents ; by digestion in 
 water, or in other fluids, which dissolve cer- 
 tain parts, and often change their nature ; by 
 destructive distillation, in which the applica- 
 tion of a strong heat alters the combination 
 of the parts, and causes the new products to 
 pass over into the receiver in the order of 
 their volatility ; by spontaneous decompo- 
 sition or fermentation, wherein the compo- 
 nent parts take a new arrangement, and form 
 compounds which did not for the most part 
 exist in the organized substance ; or, lastly, 
 the judicious chemist will avail himself of all 
 these several methods singly, or in combina- 
 tion, lie will, according to circumstances, 
 separate the parts of an animal or vegetable 
 substance by pressure, assisted by beat ; or 
 
ANI 
 
 ANN 
 
 by digestion or boiling in various fluids add- 
 ed in the retort which contains the substance 
 under examination. lie will attend particu- 
 larly to the products which pass over, whe- 
 ther they be permanently elastic, or subject 
 to condensation in the temperatures we are 
 able to produce. In some cases, he will suf- 
 fer the spontaneous decomposition to precede 
 the application of chemical methods ; and in 
 others he will attentively mark the changes 
 which the products of his operations undergo 
 in the course of time, whether in closed ves- 
 sels, or exposed to the open air. Thus it is 
 that, in surveying the ample field of nature, 
 the philosophical chemist possesses numerous 
 means of making discoveries, if applied with 
 judgment and sagacity ; though the progress 
 of discovery, so far from bringing us nearer 
 the end of our pursuit, appears continually 
 to open new scenes, and, by enlarging our 
 powers of investigation, never fails to point 
 out additional objects of inquiry. 
 
 Animal and vegetable substances approach 
 each other by insensible gradations ; so that 
 there is no simple product of the one 
 which may not be found in greater or less 
 quantity in the other. The most general 
 distinctive character of animal substances is 
 that of affording volatile alkali by destructive 
 distillation. Some plants, however, afford it 
 likewise. Neither contain it ready formed ; 
 but it appears to be produced by the combi- 
 nation of hydrogen and azote, during the 
 changes produced either by fire, or by the 
 putrefactive process. See Ammonia. 
 
 Our knowledge of the products of the ani- 
 mal kingdom, by the help of chemical ana- 
 lysis, is not yet sufficiently matured to ena- 
 ble us to arrange them according to the na- 
 ture of their component parts, which appear 
 to consist chiefly of hydrogen, oxygen, car- 
 bon, and azote ; and with these sulphur, 
 phosphorus, lime, magnesia, and soda, are 
 frequently combined in variable proportions. 
 
 * The following are the peculiar chemical 
 products of animal organization. Gelatin, 
 albumen, fibrin, caseous matter, colouring 
 matter of blood, mucus, urea, picromel, os- 
 mazome, sugar of milk, and sugar of diabetes. 
 The compound animal products are the va- 
 rious solids and fluids, whether healthy or 
 morbid, that are found in the animal body ; 
 such as muscle, skin, bone, blood, urine, 
 bile, morbid concretions, brain, Sec.* 
 
 When animal substances are left exposed 
 to the air, or immersed in water or other 
 fluids, they suffer a spontaneous change, 
 which is more or less rapid according to cir- 
 cumstances. The spontaneous change of 
 organized bodies is distinguished by the name 
 of fermentation. In vegetable bodies there 
 are distinct stages or periods of this process, 
 which have been divided into the vinous, 
 acetous, and putrefactive fermentations. Ani- 
 mal substances are susceptible only of the 
 
 two latter, during which, as in all other spon- 
 taneous changes, the combinations of chemi- 
 cal principles become in general more and 
 more simple. There is no doubt but much 
 instruction might be obtained from accurate 
 observations of the putrefactive processes in 
 all their several varieties and situations ; but 
 the loathsomeness and danger attending on 
 such inquiries has hitherto greatly retarded 
 our progress in this department of chemical 
 science. See Fermentation (Putrefac- 
 tive). 
 
 Anime, improperly called gum anime, is a 
 resinous substance imported from New Spain 
 and the Brazils. There are two kinds, dis- 
 tinguished by the names of oriental and oc- 
 cidental. The former is dry, and of an un- 
 certain colour, some specimens being green- 
 ish, some reddish, and some of the brown 
 colour of myrrh. The latter is in yellowish, 
 white, transparent, somewhat unctuous tears, 
 and partly in larger masses, brittle, of a light 
 pleasant taste, easily melting in the fire, and 
 burning with an agreeable smell. Like re- 
 sins, it is totally soluble in alcohol, and also 
 in oil. Water takes up about 1-lo'th of the 
 weight of this resin by decoction. The 
 spirit, drawn off by distillation, has a con- 
 siderable degree of the taste and flavour 
 of the anime ; the distilled water discovers on 
 its surface some small portion of essential oil. 
 
 This resin is used by perfumers, and also 
 in certain plasters, wherein it has been sup- 
 posed to be of service in nervous affections 
 of the head and other parts ; but there are 
 no reasons to think that, for medical pur- 
 poses, it differs from common resins. 
 
 Anneal. We know too little of the ar- 
 rangement of particles to determine, what it 
 is that constitutes or produces brittleness in 
 any substance. In a considerable number 
 of instances of bodies which are capable of 
 undergoing ignition, it is found that sud- 
 den cooling renders them hard and brittle. 
 This is a real inconvenience in glass, and 
 also in steel, when this metallic substance is 
 required to be soft and flexible. The incon- 
 veniences are avoided by cooling them very 
 gradually, and this process is called anneal- 
 ing. Glass vessels, or other articles, are 
 carried into an oven or apartment near the 
 great furnace, called the leer, where they are 
 permitted to cool, in a greater or less time, 
 according to their thickness and bulk. The 
 annealing of steel, or other metallic bodies, 
 consists simply in heating them, and suffer- 
 ing them to cool again either upon the hearth 
 of the furnace, or in any other situation 
 where the heat is moderate, or at least the 
 temperature is not very cold. 
 
 Annotto. The pellicles of the seeds of 
 the bixa orcllnna , a liliaceous shrub, from 15 
 to 20 feet high in good ground, afford the 
 red masses brought into Europe under the 
 name of Annotto, Orlean, and Houcou. 
 
ANT 
 
 ANT 
 
 The annotto commonly met with among 
 us is moderately hard, of a brown colour on 
 the outside, and a dull red within. It is 
 difficultly acted upon by water, and tinges 
 the liquor only of a pale brownish yellow 
 colour. In rectified spirit of wine it very 
 readily dissolves, and communicates a high 
 orange or yellowish red. Hence it is used 
 as an ingredient in varnishes, for giving 
 more or less of an orange cast to the simple 
 yellows. Alkaline salt renders it perfectly 
 soluble in boiling water, without altering its 
 colour. 
 
 Beside its use in dyeing, it is employed for 
 colouring cheese. 
 
 * Anthophyllite. A massive mineral 
 of a brownish colour ; sometimes also crys- 
 tallized, in thin flat six-sided prisms, streaked 
 lengthwise. It has a false metallic lustre, 
 glistening and pearly. In crystals, trans- 
 parent. Massive, only translucent on the 
 edges. It does not scratch glass, but fluate 
 of lime. Specific gravity 3.2. Somewhat 
 hard, but exceedingly brittle. Infusible alone 
 before the blow-pipe, but with borax it gives 
 a grass-green transparent bead. It consists 
 of 56 silica, 1S.3 alumina, 14 magnesia, 
 3.33 lime, 6 oxide of iron, 3 oxide of man- 
 ganese, l A3 water, and 2.94 loss in 100. 
 It is found at Konigsberg in Norway.* 
 
 * Anthracite. Blind coal, Kilkenny coal, 
 or glance-coal. There are three varieties. 
 1. Massive, the conchoidal of Jameson. Its 
 colour is iron black, sometimes tarnished on 
 the surface, with a splendent metallic lustre. 
 Fracture conchoidal, with a pseudo- metallic 
 lustre. It is brittle and light. It yields no 
 flame, and leaves whitish ashes. It is found 
 in the new r est floetz formations, at Meissner 
 in Ilcsse, and Walsall in Staffordshire. 2. 
 Slaty anthracite. Colour black, or brownish 
 black. Imperfect slaty in one direction, 
 with a slight metallic lustre. Brittle. Spe- 
 cific gravity 1.4 to 1.8. Consumes without 
 flame. It is composed of 72 carbon, 15 
 silica, 3.3 alumina, and 3.5 oxide of iron. 
 It is found in both primitive and secondary 
 rocks; at Calton Hill, Edinburgh; near 
 Walsall, Staffordshire ; in the southern parts 
 of Brecknockshire, Carmarthenshire, and 
 Pembrokeshire, whence it is called Welsh 
 culm ; near Cumnock and Kilmarnock, 
 Ayrshire; and most abundantly at Kilkenny, 
 Ireland. 3. Columnar anthracite. In small 
 short prismatic concretions, of an iron black 
 colour, with a tarnished metallic lustre. It 
 is brittle, soft, and light. It yields no flame 
 or smoke. It forms a thick bed near San- 
 quhar, in Dumfries-shire; at Saltcoats and 
 New Cumnock, in Ayrshire. It occurs also 
 at Meissner in I lesse. * 
 
 Antimony. The word antimony is al- 
 ways used in commerce to denote a metallic 
 ore, consisting of sulphur combined with the 
 metal which is properly called antimony. 
 
 Sometimes this sulphuret is termed crude 
 antimony, to distinguish it from the pure 
 metal, or regulus, as it was formerly called. 
 According to Prof. Proust, the sulphuret 
 contains 26 per cent of sulphur. He heated 
 ] 00 parts of antimony with an equal weight 
 of sulphur in a glass retort, till the whole 
 was well fused and the excess of sulphur 
 expelled, and the sulphuret remaining was 
 135. The result was the same after repeat- 
 ed trials: 1 00 parts of antimony, with 300 
 of red sulphuret of mercury, afforded 135 to 
 136 of sulphur. These artificial sulphurets 
 lost nothing by being kept in fusion an hour ; 
 and heated with an equal weight of sulphur, 
 they could not be made to take up more. 
 Some of the native sulphurets of the shops, 
 however, appear to have a small portion 
 more of sulphur united with them, as they 
 will take up an addition of 7 or 8 per cent 
 of antimony. 
 
 Antimony is of a dusky white colour, 
 very brittle, and of a plated or scaly texture. 
 Its specific gravity, according to Brisson, is 
 6.7021, but Bergman makes it 6.86. Soon 
 after ignition it melts, and by a continuance 
 of the heat it becomes oxidized, and rises in 
 white fumes, which may afterward be vola- 
 tilized a second time, or fused into a hya- 
 cinthine glass, according to the management 
 of the heat: the first were formerly called 
 argentine flow ers of regulus of antimony. In 
 closed vessels the antimony rises totally without 
 decomposition. This metallic substance is not 
 subject to rust by exposure to air, though its 
 surface becomes tarnished by that means. 
 Its oxides are a little soluble in water ; and 
 in this respect they resemble the oxide of 
 arsenic, by an approach toward the acid 
 state. 
 
 * There are certainly three, probably four, 
 distinct combinations of antimony and oxy- 
 gen : 1. The protoxide of Berzelius is a 
 blackish grey powder, obtained from a mix- 
 ture of powder of antimony and water, at the 
 positive pole of a voltaic circuit. Heat ena- 
 bles this oxide to absorb oxygen rapidly, 
 converting it into the tritoxide. According 
 to Berzelius, it consists of 100 of metal, and 
 4.65 oxygen. It must he confessed, how- 
 ever, that the data for fixing these propor- 
 tions are very doubtful. 2. The deutoxide 
 may be obtained by digesting the metal in 
 pow der in muriatic acid, and pouring the so- 
 lution into water of potash. Wash and dry 
 the precipitate. It is a powder of a dirty 
 white colour, which melts at a moderate red 
 heat, and crystallizes as it cools. According 
 to Berzelius, it consists of 84.3 metal + 15.7 
 oxygen. 3. fhe tritoxide, or antiinonious acid, 
 is the immediate product of the combustion of 
 the metal, called of old from its fine white 
 colour, the argentine flow ers of antimony. 1 1 
 
 v also lie formed by digesting hot nitric 
 acid on antimony. When fused with one- 
 
ANT 
 
 ANT 
 
 fourth of antimony, the whole becomes deu- 
 toxide. It forms the salts called antimonites 
 with the different bases. According to Ber- 
 zelius, the tritoxide consists of about 80 
 metal 20 oxygen. 4. The peroxide, or 
 antimonic acid, is formed when the metal in 
 powder is ignited along with six times its 
 weight of nitre in a silver crucible. The 
 excess of potash and nitre being afterwards 
 separated by hot water, the antimoniate of 
 potash is then to be decomposed by muriatic 
 acid, when the insoluble antimonic acid of a 
 straw colour will be obtained. Nitro-muria- 
 tic acid likewise converts the metal into the 
 peroxide. Though insoluble in water, it 
 reddens the vegetable blues. It does not 
 combine with acids. At a red heat oxygen 
 is disengaged, and antimonious acid results. 
 Berzelius infers its composition to be 73.5 
 metal 26.5 oxygen. It is difficult to re- 
 concile the above three portions of oxygen to 
 one prime equivalent for antimony. The 
 number 11. gives the best approximation to 
 Berzelius’s analyses. We shall then have the 
 
 In 100 parts. 
 
 Protoxide 1 1 metal -j- 1 oxy. or 91.j -J- 8.j 
 
 Deutoxide 1 1 + 2 84.6 -f 15.4 
 
 Tritoxide 11 -}- 3 78.6 -{- 21.4 
 
 Peroxide 1 1 + 4 73.4 + 26.6 
 
 The second and fourth numbers agree 
 perfectly with experiment ; the first oxide is 
 too imperfectly known to enter into the ar- 
 gument ; and the third number, though it 
 indicates a little more oxygen than Berzelius 
 assigns, gives less than Proust. 
 
 Chlorine gas and antimony combine with 
 combustion, and a bichloride results. This 
 was formerly prepared by distilling a mixture 
 of two parts of corrosive sublimate with one 
 of antimony. The substance which came 
 over having a fatty consistence, was called 
 butter of antimony. It is frequently crys- 
 tallized in four-sided prisms. It is fusible 
 and volatile at a moderate heat ; and is re- 
 solved by water alone into the white oxide 
 and muriatic acid. Being a bichloride, it is 
 eminently corrosive, like the bichloride of 
 mercury, from which it is formed. It con- 
 sists of 45.7 chlorine -j- 54.5 antimony, ac- 
 cording to Dr John Davy’s analysis, when 
 the composition of the sulphuret is corrected 
 by its recent exact analysis by Berzelius. 
 But 1 1 . antimony -}- 2 primes chlorine = 
 9.0, give the proportion per cent of 44.1 -{- 
 55.5 ; a good coincidence, if we consider the 
 circuitous process by which Dr Davy’s ana- 
 lysis was performed. Three parts of corro- 
 sive sublimate, and one of metallic antimony, 
 are the equivalent proportions for making 
 butter of antimony. Iodine and antimony 
 combine by the aid of heat into a solid iodide, 
 of a dark red colour. The phosphuret ol 
 this metal is obtained by fusing it with solid 
 
 phosphoric acid. It is a white semicrystal- 
 line substance. The sulphuret of antimony 
 exists abundantly in nature. See Ores of 
 Antimony. It consists, according to Ber- 
 zelius, of 100 antimony 57.25 sulphur. 
 The proportion given by the equivalent ratio 
 is 100 -j- 36.5. Other analysts have found 
 30, 33, and 35 to 100 of metal. Berzelius 
 admits that there may be a slight error in his 
 numbers. The only important alloys of an- 
 timony are those of lead and tin ; the former 
 constitutes type metal, and contains about 
 one-sixteenth of antimony ; the latter alloy 
 is employed for making the plates on which 
 music is engraved. 
 
 The salts of antimony are of two different 
 orders ; in the first, the deutoxide acts the part 
 of a salifiable base ; in the second, the trit- 
 oxide and peroxide, act the part of acids, 
 neutralizing the alkaline and other bases, to 
 constitute the antimonites and antimoniates. 
 
 The only distinct combination of the first 
 order entitled to our attention, is the triple 
 salt called tartrate of potash and antimony, 
 or tartar emetic, and which, by M. Gay 
 Lussac’s new views, would be styled cream- 
 tartrate of antimony. This constitutes a 
 valuable and powerful medicine, and there- 
 fore the mode of preparing it should be 
 correctly and clearly defined. As the dull 
 white deutoxide of antimony is the true 
 basis of this compound salt, and as that 
 oxide readily passes by mismanagement into 
 the tritoxide or antimonious acid, which is 
 altogether unfit for the purpose, adequate 
 pains should be taken to guard against so 
 capital an error. In former editions of the 
 British Pharmacopoeias, the glass of anti- 
 mony was prescribed as the basis of tartar 
 emetic. More complex and precarious for- 
 mulae have been since introduced. The new 
 edition of the Pharmacopee Fran 9 aise has 
 given a recipe, which appears, with a slight 
 change of proportions, to be unexceptionable. 
 Take of the sulphuretted vitreous oxide of 
 antimony levigated and acidulous tartrate of 
 potash, equal parts. Form a powder, which 
 is to be put into an earthen or silver vessel, 
 with a sufficient quantity of pure water. 
 Boil the mixture for half an hour, adding 
 boiling ■water from time to time ; filter the 
 hot liquor, and evaporate to dryness in a 
 porcelain capsule ; dissolve in boiling water 
 the result of the evaporation, evaporate till 
 the solution acquires the spec. grav. 1.161, 
 and then let it repose, that crystals be ob- 
 tained, which, by this process, will be pure. 
 Bv another recipe, copied, with some alter- 
 ation from Mr Phillips’s prescription, into 
 the appendix of the French Pharmacopoeia, 
 a subsulphate of antimony is formed first of 
 all, by digesting two parts of sulphuret of 
 antimony in a moderate heat, with three 
 parts of oil of vitriol. This insoluble sub- 
 sulphate being well washed, is then digested 
 
ANT 
 
 ANT 
 
 in a quantity of boiling water, with its own 
 weight of cream of tartar, and evaporated at 
 the density 1.161, after which it is filtered 
 hot. On cooling, crystals of the triple tar- 
 trate are obtained. One might imagine, that 
 there is a chance of obtaining by this pro- 
 cess, a mixture of sulphate of potash, and 
 perhaps of a triple sulphate of antimony, 
 along with the tartar emetic. Probably this 
 does not happen, for it is said to yield crys- 
 tals, very pure, very white, and without any 
 mixture whatever. 
 
 Pure tartar emetic is in colourless and 
 transparent tetrahedrons or octohedrons. It 
 reddens litmus. Its taste is nauseous and 
 caustic. Exposed to the air, it effloresces 
 slowly. Boiling water dissolves half its 
 weight, and cold water a fifteenth part. Sul- 
 phuric, nitric, and muriatic acids, when pour- 
 ed into a solution of this salt, precipitate 
 its cream of tartar ; and soda, potash, am- 
 monia, or their carbonates, throw down its 
 oxide of antimony. Barytes, strontites, and 
 lime waters, occasion not only a precipitate 
 of oxide of antimony, like the alkalis, but 
 also insoluble tartrates of these earths. That 
 produced by the alkaline hydrosulphurets, is 
 wholly formed of kermes ; while that caused 
 by sulphuretted hydrogen, contains both 
 kermes and cream of tartar. The decoc- 
 tions of several varieties of cinchona, and of 
 several bitter and astringent plants, equally 
 decompose tartar emetic ; and the precipi- 
 tate then always consists of the oxide of an- 
 timony, combined with the vegetable matter 
 and cream of tartar. Physicians ought 
 therefore to beware of such incompatible 
 mixtures. When tartar emetic is exposed 
 to a red heat, it first blackens, like all organic 
 compounds, and afterwards leaves a resi- 
 duum of metallic antimony and subcarbonate 
 of potash. From this phenomenon, and the 
 deep brownish red precipitate, by hydrosul- 
 phurets, this antimonial combination may 
 readily be recognized. The”precipitate may 
 further be dried on a filter, and ignited with 
 black flux, when a globule of metallic anti- 
 mony will be obtained. Infusion of galls is 
 an active precipitant of tartar emetic. 
 
 I his salt, in an undue dose, is capable of 
 acting as a poison. The best antidotes are de- 
 mulcent drinks, infusions ol bark, tea, and 
 sulphuretted hydrogen water, which instantly 
 converts the energetic salt into a relatively 
 mild sulphuret : anodynes are useful after- 
 wards. The powder of tartar emetic, mixed 
 with hog’s-lard, and applied to the skin of 
 the human body, raises small vesications. 
 
 The composition of this salt, according to 
 M. Thenard, is 35.4 acid, 39.6 oxide, 16.7 
 potash, and 8.2 water. The presence of the 
 latter ingredient is obvious, from the undis- 
 puted phenomenon of efflorescence. If we 
 adopt the new views of M. Gay Lussac, this 
 *alt may be a compound of a prime equiva- 
 
 lent of tartar = 23.825, witn a prime equi- 
 valent of deutoxide of antimony =13. On 
 this hypothesis we would have the following 
 proportions : 
 
 2 primes acid = 16.75 45.4 
 
 1 prime potash = 5.95 16.2 
 
 1 prime water = 1.125 3.1 
 
 1 oxide of antimony = 1 3.00 35.3 
 
 36.825 100.0 
 
 But very little confidence can be reposed in 
 such atomical representations. 
 
 The deutoxide seems to have the property 
 of combining with sulphur in various pro- 
 portions. To this species of compound must 
 be referred the liver of antimony, glass of 
 antimony, and crocus metallorum of the an- 
 cient apothecaries. Sulphuretted hydrogen 
 forms, with the deutoxide of antimony, a 
 compound which possessed at one time great 
 celebrity in medicine, and of which a modi- 
 fication has lately been introduced into the 
 art of calico printing. By dropping hydro- 
 sulphuret of potash, or of ammonia, into the 
 cream tartrate, or into mild muriate of anti- 
 mony, the hydrosulphuret of the metallic 
 oxide precipitates of a beautiful deep orange 
 colour. This is kermes mineral. Cluzel’s 
 process for obtaining a fine kermes , light, 
 velvety, and of a deep purple brown, is the 
 following : one part of pulverized sulphuret 
 of antimony, 22^ parts of crystallized sub- 
 carbonate of soda, and 200 parts of water, 
 are to be boiled together in an iron pot. Fil- 
 ter the hot liquor into w r arm earthen pans, 
 and allow them to cool very slowly. At the 
 end of 24 hours the kermes is deposited. 
 Throw it on a filter, wash it with water 
 which had been boiled and then cooled out 
 of contact with^air. Dry the kermes at a 
 temperature of 85°, and preserve in corked 
 phials. Whatever may be the process em- 
 ployed, by boiling the liquor after cooling 
 and filtration, on new sulphuret of antimony, 
 or upon that which was left in the former 
 operation, this new liquid will deposit, on 
 cooling, a new quantity of kermes. Besides 
 the hydrosulphuretted oxide of antimony, 
 there is formed a sulphuretted hydrosulphu- 
 ret of potash or soda. Consequently, the al- 
 kali seizes a portion of the sulphur from the 
 antimonial sulphuret, water is decomposed, 
 and whilst a portion of its hydrogen unites 
 to the alkaline sulphuret, its oxygen, and the 
 other portion of its hydrogen, combine with 
 the sulphuretted antimony. It seems, that 
 the resulting kermes remains dissolved in 
 the sulphuretted hydrosulphuret of potash or 
 soda ; but as it is less soluble in the cold 
 than the hot, it is partially precipitated by 
 refrigeration. If we pour into the superna- 
 tant liquid, after the kermes is deposited and 
 removed, any acid, as the dilute nitric, sul- 
 phuric, or muriatic, we decompose the sul- 
 phuretted hydrosulphuret of potash or soda. 
 
A PL 
 
 ANT 
 
 The alkaline base being laid hold of, the sul- 
 phuretted hydrogen and sulphur to which 
 they were united are set at liberty ; the sul- 
 phur and kermes fall together, combine with 
 it, and form an orange-coloured compound, 
 called the golden sulphuret of antimony. It 
 is a hydrogureted sulphuret of antimony. 
 Hence, when it is digested with warm muri- 
 atic acid, a large residuum of sulphur is ob- 
 tained, amounting sometimes to 1 2 per cent. 
 Kermes is composed by Thenard, of 20.3 
 sulphuretted hydrogen, 4.15 sulphur, 72.76 
 oxide of antimony, 2.79 water and loss; and 
 the golden sulphuret consists of 17.87 sul- 
 phuretted hydrogen, 68.3 oxide of antimony, 
 and 12 sulphur. 
 
 By evaporating the supernatant kermes 
 liquid, and cooling, crystals form, which 
 have been lately employed by the calico 
 printer, to give a topical orange. These 
 crystals are dissolved in water, and the solu- 
 tion being thickened with paste or gum, is 
 applied to cloth in the usual way. When 
 the cloth is dried, it is passed through a di- 
 lute acid, when the orange precipitate is 
 deposited and fixed on the vegetable fibres. 
 
 An empirical anlimonial medicine, called 
 James’s powder, has been much used in this 
 country. The inventor called it his fever 
 powder , and was so successful in his practice 
 with it, that it obtained very great reputa- 
 tion, which it still in some measure retains. 
 Probably, the success of Dr James was in 
 great measure owing to his free use of the 
 bark, which he always gave as largely as the 
 stomach would bear, as soon as he had com- 
 pletely evacuated the prima? via? by the use 
 of his antimonial preparation, with which at 
 first he used to combine some mercurial. 
 His specification, lodged in chancery, is as 
 follows : “ Take antimony, calcine it with a 
 continued protracted heat, in a flat, unglazed, 
 earthen vessel, adding to it from time to time 
 a sufficient quantity of any animal oil and salt, 
 well dephlegmated ; then boil it in melted ni- 
 tre for a considerable time, and separate the 
 powder from the nitre by dissolving it in wa- 
 ter.” The real recipe has been studiously con- 
 cealed, and a false one published in its stead. 
 Different formulas have been offered for imi- 
 tating it That of Dr Pearson furnishes a 
 mere mixture of an oxide of antimony, with 
 phosphate of lime. The real powder of 
 James, according to this chemist, consists of 
 57 oxide of antimony, with 43 phosphate of 
 lime. It seems highly probable that super- 
 phosphate of lime would act on oxide of an- 
 timony, in a way somewhat similar to cream 
 of tartar, and produce a more chemical com- 
 bination, than what can be derived from a 
 precarious ustulation and calcination, of 
 hartshorn shavings and sulphuret of anti- 
 mony, in ordinary hands. The antimonial 
 medicines arc powerful deobstruents, pro- 
 moting particularly the cuticular discharge. 
 
 The union of this metallic oxide with sul- 
 phuretted hydrogen, ought undoubtedly to 
 favour its medicinal agency in chronic dis- 
 eases of the skin. The kermes deserves 
 more credit than it has hitherto received from 
 British physicians. 
 
 The compounds formed by the antimo- 
 nious and antimonic acids, with the bases, 
 have not been applied to any use. Muriate 
 of barytes may be employed as a test for 
 tartar emetic. It will shew, hy a precipitate 
 insoluble in nitric acid, if sulphate of potash 
 be present. If the crystals be regularly 
 formed, mere tartar need not be suspected. * 
 
 For its ores, and the reduction of the me- 
 tals, see Ores. 
 
 Ants. See Acin (Formic). 
 
 * Apatite. Phosphate of lime. This mi- 
 neral occurs both massive and crystallized. 
 The crystals are six-sided prisms, low, and 
 sometimes passing into the six-sided table. 
 Lateral edges, frequently truncated, and the 
 faces smooth. Lustre splendent. Translu- 
 cent, rarely transparent. Scratched by fluor 
 spar. Brittle. Colours, white, wine-yellow, 
 green, and red. Sp. grav. 3.1. Phospho- 
 resces on coals. Electric by heat and fric- 
 tion. Consists of 55.75 lime + 46. 25 phos- 
 phoric acid, by Klaproth’s analysis of the va- 
 riety called asparagus stone. It occurs in 
 primitive rocks ; in the tin veins of the gra- 
 nite of St Michael's Mount, Cornwall ; near 
 Chudleigh in Devonshire ; at Nantes in 
 France ; in St Gothard, and in Spain ; and 
 with molybdena in granite, near Colbeck, 
 Cumberland. Phosphorite is massive, form- 
 ing great beds in the province of Estrema- 
 dura. Yellowish white colour. Dull or 
 glimmering lustre. Semi-hard. Fracture, 
 imperfect curved foliated. Brittle. Sp. grav. 
 2.8. Phosphorescent with heat. Its com- 
 position by Pelletier is 59 lime, 34 phos- 
 phoric acid, 1 carbonic acid, 2.5 fluoric 
 acid, 2 silica, 1 oxide of iron, and 0.5 mu- 
 riatic acid.* 
 
 * Am rite. Earth foam ; Schaumerde. 
 This carbonate of lime occurs usually in a 
 friable state ; but sometimes solid. Colour, 
 almost silver white. Massive, or in fine par- 
 ticles. Shining lustre, between semi-metal- 
 lic and pearly. Fracture, curve foliated. 
 Opaque; soils a little. Very soft, and easily 
 cut. Feels fine and light. It is usually 
 found in calcareous veins, at Gera in Misnia, 
 and Eisleben in Thuringia. It consists, by 
 Bucholz, of 51.5 lime, 89 acid, 1 water, 5.7 
 silica, 3.3 oxide of iron.* 
 
 * Aplome. This is commonly consider- 
 ed to be a variety of the garnet ; but the 
 difference between these minerals is this : 
 the planes of the aplome dodecahedrons are 
 striated parallel with their smaller diagonal, 
 which, according to Iiaiiy, indicates the pri- 
 mitive form to be a cube, and not a dodeca- 
 hedron. Its colour is deep orange brown. 
 
ARA 
 
 ARC 
 
 It is opaque, and harder than quartz. Sp. 
 grav. is much less than garnet, viz. 3.44. It 
 consists, by Laugier’s analysis, of 40 silica, 
 
 20 alumina, 14.5 lime, 14 oxide of iron, 2 
 oxide of manganese, 2 silica and iron. It is 
 fusible into a black glass, while garnet fuses 
 into a black enamel. It is found on the 
 river Lena in Siberia, and also in New 
 Holland.* 
 
 * AropuYLLiTE. Ichthyophthalmite. Fish- 
 eyestoue. It is found both massive and 
 crystallized. It occurs in square prisms, 
 whose solid angles are sometimes replaced 
 by triangular planes, or the prisms are ter- 
 minated by pyramids consisting of 4 rhom- 
 boidal planes. Structure lamellar; cross 
 fracture, fine grained, uneven. External 
 lustre, splendent, and peculiar; internal, 
 glistening and pearly. Semi-transparent, or 
 translucent. Moderately hard, and easily 
 broken. Sp. gr. 2.49. It exfoliates, then 
 froths, and melts into an opaque bead before 
 the blow-pipe. It consists of 51 silica, 28 
 lime, 4 potash, 17 water. Vauquelin. It is 
 found in the iron mine of Utoe in Sweden, 
 at the copper mine of Fahlun, at Arendahl, 
 Faroe, the Tyrol; and Dr MacCulloch met 
 with a solitary crystal in Dunvegan, in the 
 Isle of Sky. * 
 
 Apparatus. See Laboratory. 
 
 Apples. See Acid (Malic). 
 
 Apyrous. Bodies which sustain the ac- 
 tion of a strong heat for a considerable time, 
 without change of figure or other properties, 
 have been called apyrous ; but the word is 
 seldom used in the art of chemistry. It is 
 synonymous with refractory. 
 
 Aquafortis. This name is given to a 
 weak and impure nitric acid, commonly used 
 in the arts. It is distinguished by the terms 
 double and single , the single being only half 
 the strength of the other. The artists who 
 use these acids call the more concentrated 
 acid, which is much stronger even than the 
 double aquafortis, spirit of nitre. This dis- 
 tinction appears to be of some utility, and is 
 therefore not improperly retained by chemi- 
 cal writers. See Acid (Nitric). 
 
 * Aqua Marine. See Beryl.* 
 
 Aqua Regia, or Regis. This acid, being 
 compounded of a mixture of the nitric and 
 muriatic acids, is now termed by chemists 
 nitro-muriatic acid. 
 
 Aqua V it.®. Ardent spirit of the first 
 distillation has been distinguished in com- 
 merce by this name. The distillers of malt 
 and melasses spirits call it low wines. 
 
 Aquila Alba. One of the names given 
 to the combination of muriatic acid and 
 mercury in that state, which is more com- 
 monly known by the denomination of mcr- 
 curius dulcis , calomel , or mild muriate of 
 mercury. 
 
 ■ Arabic (Gum). This is reckoned the 
 purest of gums, and docs not greatly differ 
 
 from gum Senegal, vulgarly called gum se~ 
 neca, which is supposed to be the strongest, 
 and is on this account, as well as its greater 
 plenty and cheapness, mostly used by calico 
 printers and other manufacturers. The gums 
 of the plum and the cherry-tree have nearly 
 the same qualities as gum arabic. All these 
 substances facilitate the mixture of oils with 
 water. 
 
 Arable Lands. It is a problem in che- 
 mistry, and by no means one of the least 
 importance to society, to determine what 
 are the requisites which distinguish fruitful 
 lands from such as are less productive. See 
 Soils, and Analysis of Soils. 
 
 Arbor Dianne. See Silver. 
 
 Archil, Archilla, Rocella, Orseille. 
 
 A whitish lichen, growing upon rocks in the 
 Canary and Cape Yerd Islands, which yields 
 a rich purple tincture, fugitive indeed, but 
 extremely beautiful. This weed is imported 
 to us as it is gathered : those who prepare it 
 for the use of the dyer, grind it betwixt 
 stones, so as thoroughly to bruise, but not 
 to reduce it into powder, and then moisten 
 it occasionally with a strong spirit of urine, 
 or urine itself mixed with quicklime : in a 
 few days it acquires a purplish red, and at 
 length a blue colour ; in the first state it is 
 called archil, in the latter laemus or litmus. 
 
 The dyers rarely employ this drug by it- 
 self, on account of its dearness, and the 
 perishableness of its beauty. The chief use 
 they make of it is for giving a bloom to 
 other colours, as pinks, See. This is effected 
 by passing the dyed cloth or silk through 
 hot water slightly impregnated with the ar- 
 chil. The bloom thus communicated soon 
 decays upon exposure to the air. Mr Hellofc 
 informs us, that by the addition of a little 
 solution of tin, this drug gives a durable dye ; 
 that its colour is at the same time changed 
 toward a scarlet ; and that it is the more 
 permanent, in proportion as it recedes the 
 more from its natural colour. 
 
 Prepared archil very readily gives out its 
 colour to water, to volatile spirits, and to al- 
 cohol ; it is the substance principally made 
 use of for colouring the spirits of thermome- 
 ters. As exposure to the air destroys its 
 colour upon cloth, the exclusion of the air 
 produces a like effect in those hermetically 
 sealed tubes, the spirits of large thermome- 
 ters becoming in a few years colourless. The 
 Abbe Nollet observes, (in the French 
 Memoirs for the year 1742), that the colour- 
 less spirit, upon breaking the tube, soon re- 
 sumes its colour, and this for a number of 
 times successively ; that a watery tincture of 
 archil, included in the tubes of thermome- 
 ters, lost its colour in three days ; and that 
 in an open deep vessel, it became colourless 
 at the bottom, while the upper part retained 
 its colour. 
 
 A solution of archil in water, applied on 
 
ARIl 
 
 ARS 
 
 cold marble, stains it of a beautiful violet or 
 purplish blue colour, far more durable than 
 the colour which it communicates to other 
 bodies. M. du Fay says, he has seen pieces 
 ot marble stained with it, which in two years 
 had suffered no sensible change. It sinks 
 deep into the marble, sometimes above an 
 inch, and at the same time spreads upon the 
 surface, unless the edges be bounded by wax 
 or some similar substance. It seems to make 
 the marble somewhat more brittle. 
 
 There is a considerable consumption of 
 an article of this kind manufactured in Glas- 
 gow by Mr Mackintosh. It is much es- 
 teemed, and sold by the name of cudbear. 
 We have seen beautiful specimens of silk 
 thus dyed, the colours of which were said to 
 be very permanent, of various shades, from 
 pink and crimson to a bright mazarine blue. 
 
 Litmus is likewise used in chemistry as a 
 test, either staining paper with it, or by in- 
 fusingitin water, when it is very commonly, 
 but with great impropriety, called tincture of 
 turnsole. The persons by whom this article 
 was prepared, formerly gave it the name of 
 turnsole, pretending that it was extracted 
 from the turnsole, heliotropium tricoccum, 
 in order to keep its true source a secret. 
 The tincture should not be too strong, other- 
 wise it will have a violet tinge, which, how- 
 ever, may be removed by dilution. The 
 light of the sun turns it red even in close 
 vessels. It may be made with spirit instead 
 of water. This tincture, or paper stained 
 with it, is presently turned red by acids : 
 and if it be first reddened by a small quan- 
 tity of vinegar, or some weak acid, its blue 
 colour will be restored by an alkali. 
 
 * Arctizite. See Wernerite.* 
 
 Ardent Spirit. See Alcohol. 
 
 * A REND ATE. See PisTACITE.* 
 
 Areometer. See Hydrometer. 
 
 Argal. Crude tartar, in the state in 
 
 which it is taken from the inside of wine 
 vessels, is known in the shops by this name. 
 
 Argentate of Ammonia, fulminating 
 silver. 
 
 Argillaceous Earth, or Alumina. 
 
 * Argillite. See Clay- slate.* 
 
 Aromatics. Plants which possess a fra- 
 grant smell united with pungency, and at 
 the same time are warm to the taste, are 
 called aromatics. Their peculiar flavour 
 appears to reside in their essential oil, and 
 rises in distillation either with water or spi- 
 rit. 
 
 Arrack. A spirituous liquor imported 
 from the East Indies. It is chiefly manu- 
 factured at Batavia, and at Goa upon the 
 Malabar coast. 
 
 * Aiiragonite. This mineral occurs 
 massive, in fibres of a silky lustre ; and in 
 the form of fibrous branches, diverging from 
 a centre Flos-Jerri. It is frequently crys- 
 tallized in what appear at first sight to be 
 
 regular six-sided prisms. On close inspec- 
 tion a longitudinal crack will be observed 
 down each lateral face. It occurs also in 
 elongated octohedrons. Lustre glassy, frac- 
 ture foliated and fibrous. Colours greenish 
 and pearl grey ; often violet and green in 
 the middle; and arranged in the direction 
 of the fibres, so that the longitudinal fibres 
 are green, the transverse violet blue. Double 
 
 cleavage translucent refracts doubly 
 
 scratches calcareous spar, and sometimes 
 even glass — brittle — sp. grav. 2.90. It con- 
 sists of carbonate of lime, with occasionally a 
 little carbonate of strontites. It is found in 
 Arragon in Spain, at Leogany in Salzburg, 
 at Marienberg in Saxony, and Sterzing in 
 the Tyrol. In the cavities of Basalt near 
 Glasgow. The finest specimens of the Flos- 
 ferri ramifications, come from the mines of 
 Eisenerz in Stiria ; beautiful specimens 
 have been also found in the Dufton lead 
 mines in England, in the workings of an old 
 coal mine, called Lufton-hill pit near Dur- 
 ham. It also occurs in the trap rocks of 
 Scotland.* 
 
 Arsenic, in the metallic state, is of a 
 blueish white colour, subject to tarnish, and 
 grow first yellowish, then black, by exposure 
 to air. It is brittle, and when broken exhi- 
 bits a laminated texture. Its specific gravity 
 is 5.765. In close vessels it sublimes entire 
 at 356° F. but burns with a small flame if 
 respirable air be present. 
 
 The arsenic met with in commerce has 
 the form of a white oxide. It is brought 
 chiefly from the cobalt works in Saxony, 
 where zaffre is made. Cobalt ores contain 
 much arsenic, which is driven off by long 
 torrefaction. The ore is thrown into a fur- 
 nace resembling a baker’s oven, with a flue, 
 or horizontal chimney, nearly two hundred 
 yards long, into which the fumes pass, and 
 are condensed into a greyish or blackish 
 powder. This is refined by a second subli- 
 mation in close vessels, with a little potash, 
 to detain the impurities. As the heat is 
 considerable, it melts the sublimed flowers 
 into those crystalline masses which are met 
 with in commerce. See Acid (Arsenious). 
 
 The metal may be obtained from this, 
 either by quickly fusing it together with 
 twice its weight of soft soap and an equal 
 quantity of alkali, and pouring it out, when 
 fused, into a hot iron cone ; or by mixing 
 it in powder with oil, and exposing it in a 
 matrass to a sand heat. This process is too 
 offensive to be performed, except in the open 
 air, or where a current of air carries off the 
 fumes. The decomposed oil first rises; and 
 the arsenic is afterwards sublimed, in the 
 form of a flaky metallic substance. It may 
 likewise be obtained by mixing two parts ot 
 the arsenious acid with one of black flux ; 
 putting the mixture into a crucible, with 
 another inverted over it ; and luted to it with 
 
ARS 
 
 ARS 
 
 clay and sand ; and applying a red heat to 
 the lower crucible. The metal will be re- 
 duced, and line the inside of the upper cru- 
 cible. 
 
 It is among the most combustible of the 
 metals, burns with a blue flame, and garlic 
 smell, and sublimes in the state of arsenious 
 acid. 
 
 Concentrated sulphuric acid does not at- 
 tack arsenic when cold ; but if it be boiled 
 upon this metal, sulphurous acid gas is 
 emitted, a small quantity of sulphur sub- 
 limes, and the arsenic is reduced to an oxide. 
 
 Nitrous acid readily attacks arsenic, and 
 converts it into arsenious acid, or, if much 
 be employed, into arsenic acid. 
 
 Boiling muriatic acid dissolves arsenic, 
 but affects it very little when cold. This 
 solution affords precipitates upon the addi- 
 tion of alkalis. The addition of a little ni- 
 tric acid expedites the solution ; and this 
 solution, first heated and condensed in a 
 close vessel, is wholly sublimed into a thick 
 liquid, formerly termed butter of arsenic. 
 Thrown in powder into chlorine gas, it burns 
 with a bright white flame, and is converted 
 into a chloride. 
 
 None of the earths or alkalis act upon it, 
 unless it be boiled a long while in fine 
 powder, in a large proportion of alkaline 
 solution. 
 
 Nitrates detonate with arsenic, convert it 
 into arsenic acid, and this, combining with 
 the base of the nitrate, forms an arseniate, 
 that remains at the bottom of the vessel. 
 
 Muriates have no action upon it ; but if 
 three parts of chlorate of potash be mixed 
 with one part of arsenic in fine powder, 
 which must be done with great precaution, 
 and a very light hand, a very small quantity 
 of this mixture, placed on an anvil, and 
 struck with a hammer, will explode with 
 flame and a considerable report ; if touched 
 with fire, it will burn with considerable rapi- 
 dity ; and if thrown into concentrated sul- 
 phuric acid, at the instant of contact a flame 
 rises into the air like a flash of lightning, 
 which is so bright as to dazzle the eye. 
 
 Arsenic readily combines with sulphur by 
 fusion and sublimation, and forms a yellow 
 compound called orpiment , or a red called 
 realgar. The nature of these, and their dif- 
 ference, are not accurately known ; but Four- 
 croy considers the first as a combination of 
 sulphur with the oxide, and the second as a 
 combination of sulphur with the metal itself 
 as he found the red sulphuret converted into 
 the yellow by the action of acids. 
 
 Arsenic is soluble in fat oils in a boiling 
 heat ; the solution is black, and has the cont 
 sistence of an ointment when cold. Most 
 metals unite with arsenic; which exists in 
 the metallic state in such alloys as possess 
 the metallic brilliancy. 
 
 * Iodine and arsenic unite, forming an 
 
 iodide, of a dark purple red colour, possess- 
 ing the properties of an acid. It is soluble 
 in water, and its solution forms a soluble 
 compound with potash. Arsenic combines 
 with hydrogen into a very noxious com- 
 pound, called arsenuretted hydrogen gas. 
 To prepare it, fuse in a covered crucible 3 
 parts of granulated tin, and 1 of metallic ar- 
 senic in powder; and submit this alloy, 
 broken in pieces, to the action of muriatic 
 acid in a glass retort. On applying a mo- 
 derate heat, the arsenuretted hydrogen comes 
 over, and may be received in a mercurial or 
 water pneumatic trough. Protomuriate of 
 tin remains in the retort. When 1 of arse- 
 nic is used for 15 of tin, the former metal is 
 entirely carried off in the evolved hydrogen. 
 100 parts of this gas contain 140 of hydro- 
 gen, as is proved by heating it with tin. Its 
 specific gravity, according to Sir H. Davy, 
 is 0.5552 ; according to Trommsdorff 
 0.5293. Stromeyer states, that by a cold 
 of — 22° it condenses into a liquid. Ex- 
 ploded with twice its bulk of oxygen, water 
 and oxide of arsenic are formed. When ar- 
 senuretted hydrogen issuing from a tube is 
 set on fire, it deposits a hydruret of arsenic. 
 Sulphur, potassium, sodium, and tin, decom- 
 pose this gas, combine with its metal ; and 
 in the case of sulphur, sulphuretted hydro- 
 gen results. By subtracting from the spe- 
 cific gravity of the arsenuretted gas that of 
 
 hydrogen gas we have the proportion 
 
 of arsenic present; 0.55520 — 0.09716 = 
 0.45804 = the arsenic in 100 measures of ar- 
 senuretted hydrogen; which gives the pro- 
 portion by weight of about 6 arsenic to I 
 hydrogen ; but Stromeyer’s analysis by nitric 
 acid gives about 50 arsenic to 1 hydrogen, 
 which is probably much nearer the true com- 
 position. A prime equivalent of hydro- 
 gen is to one of arsenic as 1 to 76 ; and 2 
 consequently as 1 to 38. Gehlen fell a vic- 
 tim to his researches on this gas ; and there- 
 fore the new experiments requisite to eluci- 
 date its constitution must be conducted with 
 circumspection. If chlorine be added to a 
 mixture of arsenuretted and sulphuretted 
 hydrogen, the bulk diminishes, and yellow 
 coloured flakes are deposited. Concentrat- 
 ed nitric acid occasions an explosion in this 
 gas, preceded by nitrous fumes ; but if the 
 acid be diluted, a silent decomposition of 
 the gas is effected. The density of the hy- 
 drogen in this compound gas is 0.09716. 
 
 I herefore, by fstromeyer s analysis, we have 
 this proportion to calculate the specific gra- 
 vity of the gas, 2.19:0.09716: : (2.19+106) 
 
 : 4.82/ ; a quantity nearly 9 times greater 
 than what experiment has given. 
 
 I his gas extinguishes flame, and instantly 
 destroys animal life. Water has no effect 
 upon it. From the experiments of Sir H. 
 Davy and MM. Gay Lussac and Thenard, 
 there appears to be a solid compound of liy- 
 
AIIS 
 
 ASB 
 
 drogen and arsenic*, or a Iiydruret. It is 
 formed by acting with the negative pole of a 
 voltaic battery on arsenic plunged in water. 
 It is reddish brown, without lustre, taste, and 
 smell. It is not decomposed at a heat, ap- 
 proaching to cherry red ; but at this tempera- 
 ture it absorbs oxygen ; while water and ar- 
 senious acid are formed, with the evolution 
 of heat and light. The proportion of the 
 two constituents is not known.* 
 
 Arsenic h used in a variety of arts. It 
 enters into metallic combinations, wherein a 
 white colour is required. Glass manufac- 
 turers use it ; but its effect in the composi- 
 tion of glass does not seem to be clearly ex- 
 plained. Orpiment and realgar are used as 
 pigments. See Acids (Arsenic, and Arse- 
 njous). 
 
 Asafcetida is obtained from a lar<re um- 
 belliferous plant growing in Persia. The 
 root resembles a large parsnep externally, of 
 a black colour: on cutting it transversely, 
 the asafoetida exudes in form of a white 
 thick juice, like cream ; which, from expo- 
 sure to the air, becomes yellower and yel- 
 lower, and at last of a dark brown colour. 
 It is very apt to run into putrefaction ; and 
 hence those who collect it carefully defend 
 it from the sun. The fresh juice has an ex- 
 cessively strong smell, which grows weaker 
 and weaker upon keeping : a single dram of 
 the fresh fluid juice .smells more than a hun- 
 dred pounds of the dry asafoetida brought to 
 us. The Persians are commonly obliged to 
 hire ships on purpose for its carriage, as 
 scarcely any one will receive it along with 
 other commodities, its stench infecting every 
 thing that comes near it. 
 
 The common asafoetida of the shops is of 
 a vellowish or brownish colour, unctuous 
 and tough, of an acrid or biting taste, and a 
 strong disagreeable smell, resembling that of 
 garlic. From four ounces Neumann obtain- 
 ed, by rectified spirit, two ounces six drams 
 and a half of resinous extract ; and after- 
 ward, by water, three drams and half a scru- 
 ple of gummy extract, about six drams and a 
 scruple of earthy matter remaining undis- 
 solved. On applying water at first, he gain- 
 ed, from four ounces, one ounce three scru- 
 ples and a half of gummy extract. 
 
 Asafcetida is administered in nervous and 
 hysteric affections, as a deobstruent, and 
 sometimes as an anthelmintic. A tincture 
 of it is kept in the shops, and' it enters into 
 the composition of the compound galbanum 
 pill of the London college, the gum pill of 
 former dispensatories. 
 
 * Asbestos or Asbestos. A mineral of 
 which there arc five varieties, all more or 
 less flexible and fibrous. 
 
 1. Amianthus occurs in very long, fine, 
 flexible, elastic fibres, of a white, greenish, 
 or reddish colour. It is somewhat unctuous 
 to the touch, has a silky or pearly lustre, and 
 
 is slightly translucent. Sectile ; tough ; sp. 
 grav. from 1 to 2.3. Melts with difficulty 
 before the blow- pipe, into a white enamel. 
 It is usually found in serpentine; in the 
 Tarentaise in Savoy; in long and beautiful 
 fibres, iu Corsica; near Bareges, in the 
 Pyrenees; in Dauphiny and St Gothard ; 
 at St Keverne, Cornwall; at Portsoy, Scot- 
 land ; in mica slate at Glenclg, Inverness- 
 shire, and near Durham. It consists of 59 
 silex, 25 magnesia, 9.5 lime, 5 alumina, 
 and 2.25 oxide of iron.* 
 
 The ancients manufactured cloth out of 
 the fibres of asbestos, for the purpose, it is 
 said, of wrapping up the bodies of the dead, 
 when exposed on the funeral pile. Several 
 moderns have likewise succeeded in making 
 this cloth ; the chief artifice of which seems 
 to consist in the admixture of flax and a li- 
 beral use of oil; both which substances are 
 afterwards consumed by exposing the cloth 
 for a certain time to a red heat. Although 
 the cloth of asbestos, when soiled, is restored 
 to its primitive whiteness by heating in the 
 fire ; it is found, nevertheless, by several au- 
 thentic experiments, that its weight dimi- 
 nishes by such treatment. The fibres of as- 
 bestos, exposed to the violent heat of the 
 blow-pipe, exhibit slight indications of fu- 
 sion ; though the parts, instead of running 
 together, moulder away, and part fall down, 
 while the rest seem to disappear before the 
 current of air. Ignition impairs the flexi- 
 bility of asbestos in a slight degree. 
 
 * 2. Common Asbestus occurs in masses 
 of fibres of a dull greenish colour, and of a 
 somewhat pearly lustre. Fragments splin- 
 tery. It is scarcely flexible, and greatly den- 
 ser than amianthus. It is slightly unctuous 
 to the touch. Sp. grav. 2.7. Fuses with 
 difficulty into a greyish-black scoria. It is 
 composed of 65.9 silica, 16 magnesia, 12.8 
 lime, 6 oxide of iron, and 1.1 alumina. It 
 is more abundant than amianthus, and is 
 found usually in serpentine, as at Portsoy, 
 the Isle of Anglesea, and the Lizard in 
 Cornwall. It was found in the limestone of 
 Glentilt, by Dr M‘Culloch, in a pasty state, 
 but it soon hardened by exposure to air. 
 
 3. Mountain Leather consists not of 
 parallel fibres like the preceding, but inter- 
 woven and interlaced so as to become tough. 
 When in very thin pieces it is called moun- 
 tain paper. Its colour is yellowish-wliite, 
 and its touch meagre. It is found at \\ an- 
 lockhead, in Lanarkshire. Its specific gravity 
 is uncertain. 
 
 4. Mountain Cork, or Elastic Asbestus , 
 is, like the preceding, of an interlaced 
 fibrous texture ; is opaque, has a meagre 
 fool and appearance, not unlike common 
 cork, and like it too, is somewhat clastic. 
 It swims on water. Its colours are, white, 
 grey, and yellowish-brown. Receives an 
 impression from the nail ; very tough ; 
 
ASP 
 
 ASS 
 
 cracks when handled, and melts with diffi- 
 culty before the blow- pipe. Sp. grav. from 
 0.68 to 0.99. It is composed of silica 62, 
 carbonate of lime 1 2, carbonate of magnesia 
 23, alumina 2.8, oxide of iron 5. 
 
 5. Mountain Wood, Ligniform asbes- 
 tus. Is usually massive, of a brown colour, 
 and having the aspect of wood. Internal 
 lustre glimmering. Soft, sectile and tough ; 
 opaque ; feels meagre ; fusible into a black 
 slag. Sp. grav. 2.0. It is found in the 
 Tyrol ; Dauphiny ; and in Scotland, at Glen- 
 tilt, Portsoy, and Kildrumie.* 
 
 Ashes. The fixed residue of combustible 
 substances, which remains after they have 
 been burned, is called ashes. In chemistry 
 it is most commonly used to denote the re- 
 sidue of vegetable combustion. 
 
 * Asparagin. White transparent crystals, 
 of a peculiar vegetable principle, which spon- 
 taneously form in asparagus juice which has 
 been evaporated to the consistence of syrup. 
 They are in the form of rhomboidal prisms, 
 hard and brittle, having a cool and slightly 
 nauseous taste. They dissolve in hot water, 
 but sparingly in cold water, and not at all 
 in alcohol. On being heated they swell, and 
 emit penetrating vapours, which affect the 
 eyes and nose like wood-smoke. Their solu- 
 tion does not change vegetable blues ; nor is 
 it affected by hydrosulphuret of potash, oxa- 
 late of ammonia, acetate of lead, or infusion 
 of galls. Lime disengages ammonia from 
 it; though none is evolved by triturating it 
 with potash. The asparagus juice should be 
 first heated to coagulate the albumen, then 
 filtered and left to spontaneous evaporation 
 for 1 5 or 20 days. Along with the aspara- 
 gin crystals, others in needles of little con- 
 sistency appear, analogous to mannite , from 
 which the first can be easily picked out. — 
 Vauquelin and Robiquet. Annales de Chi- 
 mie, vol. 55. and Nicholson’s Journal, 13.* 
 Asphaltum. This substance, likewise 
 called Bitumen Judaicum, or Jews’ Pitch, is 
 a smooth, hard, brittle, black or brown sub- 
 stance, which breaks with a polish, melts 
 easily when heated, and when pure burns 
 without leaving any ashes. It is found in a 
 soft or liquid state on the surface of the 
 Dead Sca,j- but by age grows dry and hard. 
 The same kind of bitumen is likewise found 
 in the earth in other parts of the world ; in 
 China ; America, particularly in the island 
 of Trinidad ; and some parts of Europe, as 
 the Carpathian hills, France, Neufchattel, 
 Ac. Its specific gravity, according to Boyle, 
 is 1.400, to Kirwan, from 1.07 to 1.63. A 
 specimen from Albania, of the specific gra- 
 
 f In the Mem. of the Academy of Sciences of 
 Pans for 1778, there is an analysis of the water of this 
 sea by Messrs Macquer, Lavoisier, and Sage; by 
 which it appears to contain 22 per cent of miniate of 
 magnesia, 16$ of muriate of lime, and 6$ of muriate of 
 soda. Its specific gravity is 1.25, It is limpid, and 
 without smell. 
 
 vity of 1.203, examined by Mr Klaproth, 
 was found to be soluble only in oils and in 
 ether. Five parts of rectified oil of petro- 
 leum dissolved one of the asphaltum, without 
 heat, in 24 hours. Analyzed in the dry- 
 way, 100 grains afforded 52 of bituminous 
 oil, 6 of water faintly ammoniacal, 30 of 
 charcoal, of silex, of alumina, ^ of 
 lime, 1^ oxide of iron, \ oxide of manga- 
 nese, and 36 cubic inches of hydrogen gas. 
 
 According to Neumann, the asphaltum of 
 the shops is a very different compound from 
 the native bitumen ; and varies, of course, 
 in its properties, according to the nature of 
 the ingredients made use of in forming it. 
 On this account, and probably from other 
 reasons, the use of asphaltum, as an article 
 of the materia medica, is almost totally laid 
 aside. 
 
 * The Egj T ptians used asphaltum in em- 
 balming, under the name of mumia mine- 
 ralis, for which it is well adapted. It was 
 used for mortar at Babylon.* 
 
 Assay, or Essay. This operation con- 
 sists in determining the quantity of valuable 
 or precious metal contained in any mineral 
 or metallic mixture, by analyzing a small 
 part thereof. The practical difference be- 
 tween the analysis and the assay of an ore, 
 consists in this : The analysis, if properly 
 made, determines the nature and quantities 
 of all the parts of the compound; whereas, 
 the object of the assay consists in ascertain- 
 ing how much of the particular metal in 
 question may be contained in a certain de- 
 terminate quantity of the material under 
 examination. Thus, in the assay of gold or 
 silver, the baser metals are considered as of 
 no Value or consequence ; and the problem 
 to be resolved is simply, how much of each 
 is contained in the ingot or piece of metal 
 intended to be assayed. The examination 
 of metallic ores may be seen under their re- 
 spective titles ; the present article will there- 
 fore consist of an account of the assaying of 
 gold and silver. 
 
 To obtain gold or silver in a state of pu- 
 rity, or to ascertain the quantity of alloy it 
 may contain, it is exposed to a strong heat, 
 together with lead, in a porous crucible. 
 This operation is called cupellation, and is 
 performed as follows ; The precious metal 
 is put, together with a due proportion of lead, 
 into a shallow crucible, made of burned 
 bones, called a cupel ; and the fusion of the 
 metals is effected by exposing them to a 
 considerable heat in a muffle, or small 
 earthen oven, fixed in the midst of a furnace. 
 The lead continually vitrifies, or becomes 
 converted into a glassy calx, which dissolves 
 all the imperfect metals. This fluid glass, 
 with its contents, soaks into the cupel, and 
 leaves the precious metals in a state of pu- 
 rity. During the cupellation, the scoria; 
 running down on all sides of the metallic 
 
ASS 
 
 ASS 
 
 mass, produce an appearance called circula- 
 tion ; by which the operator judges whether 
 the process be going on well. When the 
 metal is nearly pure, certain prismatic co- 
 lours flash suddenly across the surface of 
 the globule, which soon afterward appears 
 very brilliant and clean : this is called the 
 brightening, and show's that the separation is 
 ended. 
 
 After gold has passed the cupel, it may 
 still contain either of the other perfect metals, 
 platina, or silver. The former is seldom 
 suspected; the latter is separated by the 
 operations called quartation and parting. 
 Quartation consists in adding three parts of 
 silver to the supposed gold, and fusing them 
 together ; by which means the gold becomes 
 at most one-fourth of the mass only. The 
 intention of this is to separate the particles 
 of gold from each other, so that they may 
 not cover and defend the silver from the ac- 
 tion of the nitric acid, which is to be used 
 in the process of parting. Parting consists 
 in exposing the mass, previously hammered 
 or rolled out thin, to the action of seven or 
 eight times its weight of boiling nitric acid of 
 a due strength. The ‘first portion of nitric 
 acid being poured off, about half the quan- 
 tity, of a somewhat greater strength, is to be 
 poured on the remaining gold ; and if it be 
 supposed that this has not dissolved all the 
 silver, it may even be repeated a second time. 
 For the first operation an acid of the specific 
 gravity of 1.280 may be used, diluted with 
 an equal quantity of w r ater ; for the second, 
 an acid about 1.26 may be taken undiluted. 
 If the acid be not too concentrated, it dis- 
 solves the silver, and leaves the gold in a po- 
 rous mass, of the original form ; but, if too 
 strong, the gold is in a powdery form, which 
 may be washed and dried. The weight of 
 the original metal before cupellation, and in 
 all the subsequent stages, serves to ascertain 
 the degree of fineness of the ingot, or ore, of 
 which it is a part. 
 
 In estimating or expressing the fineness 
 of gold, the whole mass spoken of is sup- 
 posed to weigh twenty-four carats of twelve 
 grains each, either real, or merely propor- 
 tional, like the assayer’s weights; and the 
 pure gold is called fine. Thus, if gold be 
 said to be 23 carats fine, it is to be under- 
 stood that, in a mass weighing 24 carats, 
 the quantity of pure gold amounts to c 2o 
 carats. 
 
 In such small works as cannot be assayed 
 by scraping off a part, and cupelling it, the 
 assayers endeavour to ascertain its quality or 
 fineness by the touch. This is a method of 
 comparing the colour, and other properties, 
 of a minute portion of the metal, with those 
 of small bars, the composition of which is 
 known. These bars are called touch-nee- 
 dles ; and they are rubbed upon the black 
 basal tes, which, for this reason, is called the 
 
 touchstone. Black flint or pottery will serve 
 the same purpose. Sets of gold needles may 
 consist of — pure gold ; pure gold 23^ carats, 
 with half a carat of silver ; 23 carats of gold, 
 with one carat of silver ; 22^ carats of gold, 
 with ]-t carats of silver; and so on, till the 
 silver amounts to four carats ; after which 
 the additions may proceed by whole carats. 
 Other needles may be made in the same 
 manner, with copper instead of silver ; and 
 other sets may have the addition consisting 
 either of equal parts silver and copper, or 
 such proportions as the occasions of business 
 require. The examination by the touch 
 may be advantageously employed previous to 
 quartation, to indicate the quantity of silver 
 necessary to be added. 
 
 In foreign countries, where trinkets and 
 small work are required to be submitted to 
 the assay of the touch, a variety of needles, 
 are necessary ; but they are not much used 
 in England. They afford, however, a de- 
 gree of information which is more conside- 
 rable than might at first be expected. The 
 attentive assayer not only compares the co- 
 lour of the stroke made upon the touchstone 
 by the metal under examination, with that 
 produced by his needle; but will likewise 
 attend to the sensation of roughness, dryness, 
 smoothness, or greasiness, which the texture 
 of the rubbed metal excites, when abraded 
 by the stone. When two strokes, perfectly 
 alike in colour, are made upon the stone, he 
 may then wet them with aquafortis, which 
 will affect them very differently, if they he 
 not similar compositions; or the stone itself 
 may be made red-hot by the fire, or by the 
 blow-pipe, if thin black pottery be used ; in 
 which case the phenomena of oxidation will 
 differ, according to the nature and quantity 
 of the alloy. 
 
 The French government lias from time to 
 time caused various experimental inquiries to 
 he made respecting the art of assaying gold, 
 which have thrown much light on this sub- 
 ject, and greatly tend to produce uniformity 
 in the results of the operation. The latest 
 report on this subject may be seen in the 
 Annales de Chimie, vol. vi. p. 6'4. ; which 
 may be consulted for a full account of the 
 experiments and history of former proceed- 
 ings. The general result is as follows, near- 
 ly in the words of the authors: 
 
 Six principal circumstances appear to af- 
 fect the operation of parting : namely, the 
 quantity of acid used in parting, or in the 
 first boiling; the concentration of this acid; 
 the time employed in its application ; the 
 quantity of acid made use of in the reprise, 
 or second operation ; its concentration ; 
 and the time during which it is applied. 
 From the experiments it has been shown, 
 that each of these unfavourable circum- 
 stances might easily occasion a loss of bom 
 the half of a thirty- second part of a carat, of 
 
ASS 
 
 AST 
 
 two thirty- second parts* 'Hie writers explain 
 their technical language by observing, that, 
 the whole mass consisting of twenty-four 
 carats, this thirty-second part denotes 1 -768th 
 part of the mass. It may easily be conceiv- 
 ed, therefore, that if the whole six circum- 
 stances were to exist, and be productive of 
 errors falling the same way, the loss would 
 be very considerable. 
 
 It is therefore indispensably necessary, 
 that one uniform process should be followed 
 in the assays of gold ; and it is a matter of 
 astonishment, that such an accurate process 
 should not have been prescribed by Govern- 
 ment for assayers in an operation of such 
 great commercial importance, instead of every 
 one being left to follow his own judgment. 
 The process recommended in the report be- 
 fore us is as follows : — 
 
 Twelve grains of the gold intended to 
 be assayed must be mixed with thirty grains 
 of fine silver, and cupelled with 108 grains f 
 of lead. The cupellation must be carefully 
 attended to, and all the imperfect buttons 
 rejected. When the cupellation is ended, 
 the button must be reduced by lamination 
 into a plate of \\ inch, or rather more, in 
 length, and four or five lines in breadth* 
 This must be rolled up upon a quill, and 
 placed in a matrass capable of holding 
 about three ounces of liquid, when filled up 
 to its narrow part. Two ounces and a half 
 of very pure aquafortis, of the strength of 
 20 degrees of iiaume’s areometer, must then 
 be poured upon it ; and the matrass being 
 placed upon hot ashes, or sand, the acid 
 must be kept gently boiling for a quarter of 
 an hour ; the acid must then be cautiously 
 decanted, and an additional quantity of 1^ 
 ounce must be poured on the metal, and 
 slightly boiled for twelve minutes. This 
 
 being likewise carefully decanted, the small 
 spiral piece of metal must be washed with 
 filtered river water, or distilled water, by 
 filling the matrass with this fluid. The 
 
 vessel is then to be reversed, by applying 
 the extremity of its neck against the bottom 
 of a crucible of fine earth, the internal sur- 
 face of which is very smooth. The anneal- 
 ing must then be made, after having sepa- 
 rated the portion of water which had fallen 
 into the crucible ; and, lastly, the annealed 
 gold must be weighed. For the certainty 
 of this operation, two assays must be made 
 in the same manner, together with a third 
 assay upon gold of twenty-four carats, or 
 upon gold the fineness of which is perfectly 
 and generally known. 
 
 f U gross. 'Though these doses of silver and lead 
 appeared to he proper for all operations of assaying 
 gold, the commissaries observe, nevertheless, that 
 gold of a lower title than eighteen carats may be al- 
 loyed with two parts, and even less, of silver ; in order 
 t hat the small mass of metal, when it comes to he la- 
 minated, may not be too thin, so as to break in pieces 
 during the parting. 
 
 No conclusion must be drawn from this 
 assay, unless the latter gold should prove to 
 be of tlie fineness of twenty-four carats 
 exactly, or of its known degree of fineness ; 
 for, if there be either loss or surplus, it may 
 be inferred, that the other two assays, hav- 
 ing undergone the same operation, must be 
 subject to the same error. The operation 
 being made according to this process, by se- 
 veral assayers, in circumstances of import- 
 ance, such as those which relate to large 
 fabrications, the fineness of the gold must 
 not be depended on, nor considered as ac- 
 curately known, unless all the assayers have 
 obtained a uniform result, without commu- 
 nication with each other. The authors ob- 
 serve, however, that this identity must be 
 considered as existing to (he accuracy of 
 half of the thirty -second part of a carat. 
 For, notwithstanding every possible precau- 
 tion or uniformity, it very seldom happens 
 that an absolute agreement is obtained be- 
 tween the different assays of one and tlie 
 same ingot, because the ingot itself may dif- 
 fer in its fineness in different parts of its mass* 
 
 The assaying of silver does not differ from 
 that of gold, excepting that the parting ope- 
 ration is not necessary. A certain small 
 portion of the silver is absorbed by the cu- 
 pel, and the more when a larger quantity of 
 lead is used, unless the quantity of lead be 
 excessive ; in which case most of it will be 
 scorified before it begins to act upon the 
 silver. Messrs Hellot, Fillet, and Macquer, 
 from their experiments made by order of 
 the French Government, have ascertained, 
 that four parts of lead are requisite for sil- 
 ver of eleven pennyweights twelve grains 
 fine, or containing this weight of pure silver, 
 and twelve grains of alloy, in twelve penny- 
 weights ; six parts of lead for silver of eleven, 
 pennyweights ; eight parts lead for silver of 
 ten pennyweights ; ten parts lead for silver 
 of nine pennyweights ; and so on in the same 
 progression. 
 
 Astringent Principle. The effect call- 
 ed astringency, considered as distinguish- 
 able by the taste, is incapable of being de- 
 fined. It is perceived in the husks of nuts, 
 of walnuts, in green tea, and eminently in 
 the nut gall. This is probably owing to 
 the circumstance, that acids have likewise 
 the property of corrugating the fibres of 
 the mouth and tongue, which is considered 
 as characteristic of astringency as it relates 
 to taste ; and hence the gallic acid, which 
 is commonly found united with the true as- 
 tringent principle, was long mistaken for it. 
 Seguin first distinguished them, and, from 
 the use of this principle in tanning skins, has 
 given it the name of tannin. Their charac- 
 teristic differences are, the gallic acid forms 
 a black precipitate with iron ; the astringent 
 principle forms an insoluble compound with 
 albumen. See Tannin. 
 
ATM 
 
 Atiianor. A kind of furnace, which has 
 long since fallen into disuse. The very long 
 ami durable operations of the ancient che- 
 mists rendered it a desirable requisite, that 
 their fires should be constantly supplied 
 with fuel in proportion to the consumption. 
 The athancr furnace was peculiarly adapt- 
 ed to inis purpose. Beside the usual parts, 
 it was provided with a hollow tower, into 
 which charcoal was put. The upper part 
 of the tower, when fdled, was closely shut 
 by a well-fitted cover; and the lower part 
 communicated with the fire-place of the 
 furn ace. In consequence of this disposition, 
 the charcoal subsided into the fire-place 
 gradually as the consumption made room 
 for it ; but that which was contained in 
 the tower was defended from combustion 
 by the exclusion of a proper supply of air. 
 
 * Atmometer. The name of an instru- 
 ment contrived by Professor Leslie, to mea- 
 sure the quantity of exhalation from a humid 
 surface in a coven time. It consists of a thin 
 
 O 
 
 ball of porousearthen-ware,twoor three inches 
 in diameter, with a small neck, to which is 
 firmly cemented a long and rather wide tube 
 of glass, bearing divisions, each of them cor- 
 responding to an internal annular section, 
 equal to a film of liquid that w’ould cover the 
 outer surface of the ball to the thickness of 
 the thousandth part of an inch. These divi- 
 sions are ascertained by a simple calculation, 
 and numbered downwards to the extent of 
 1 00 or 200. To the top of the tube is fitted 
 a brass cap, having a collar of leather, and 
 which, after the cavitv has been filled with 
 distilled or boiled water, is screwed tight. 
 The outside of the ball being now wiped dry, 
 the instrument is suspended out of doors, 
 and exposed to the free action of the air. 
 The quantity of evaporation from a wet ball 
 is the same as from a circle having twice the 
 diameter of the sphere. In the atmometcr, 
 the humidity transudes through the porous 
 substance, just as fast as it evaporates from 
 the external surface ; and this waste is mea- 
 sured by the corresponding descent ot water 
 in the stem. At the same time, the tightness 
 of the collar taking offthe pressure of the co- 
 lumn of liquid, prevents it from oozing so pro- 
 fusely as to drop from the ball; an incon- 
 venience which, in the case of very feeble 
 evaporation, might otherwise take place. As 
 the process goes on, a corresponding portion 
 of air is likewise imbibed by the moisture on 
 the outside, and being introduced into the 
 ball, rises in a small stream to replace the 
 water. The rate of evaporation is nowise 
 affected by the quality of the porous ball. It 
 continues exactly the same when the exhal- 
 ing surface appears almost dry, as when it 
 glistens with superfluous moisture. When 
 the consumption of water is excessive, it may 
 be allowed to percolate by unscrewing the 
 
 ATT 
 
 cap, taking care, however, to let no drops 
 fall. 1 Leslie on Heat and Moisture. 
 
 Atmosphere. kee Air ( Atmospheri- 
 cal). 
 
 * Atomic Theory. See Equivalents 
 (Chemical).* 
 
 * Atropa. A poisonous vegetable princi- 
 ple, probably alkaline, recently extracted from 
 the Atropa belladonna, or deadly nightshade, 
 by M. Brandes ; the details have not reached 
 us.* 
 
 Attraction. The instances of attraction 
 which are exhibited by the phenomena 
 around us, are exceedingly numerous, and 
 continually present themselves to our obser- 
 vation. The effect of gravity, which causes 
 the weight of bodies, is so universal, that we 
 can scarcely form an idea how the universe 
 could subsist without it. Other attractions, 
 such as those of magnetism and electricity, 
 are likewise observable ; and every experi- 
 ment in chemistry tends to show, that bodies 
 are composed of various principles or sub- 
 stances, which adhere to each other with va- 
 rious degrees of force, and may be separated 
 by known methods. It is a question among 
 philosophers, whether all the attractions 
 which obtain between bodies be referable to 
 one general cause modified by circumstan- 
 ces, or whether various original and distinct 
 causes act upon the particles of bodies atone 
 and the same time. The philosophers at 
 the beginning of the present century were 
 disposed to consider the several attractions 
 as essentially different, because the laws of 
 their action differ from each other ; hut the 
 moderns appear disposed to generalize this 
 subject, and to consider all the attractions 
 which exist between bodies, or at least those 
 which arc permanent, as depending upon 
 one and the same cause, whatever it may be, 
 which regulates at once the motions of the 
 immense bodies that circulate through the 
 celestial spaces, and those minute particles 
 that are transferred from one combination to 
 another in the operations of chemistry. The 
 earlier philosophers observed, for example, 
 that the attraction of gravitation acts upon 
 bodies with a force which is inversely as the 
 squares of the distances ; and from mathe- 
 matical deduction they have inferred, that 
 the law of attraction between the particles 
 themselves follows the same ratio; but when 
 their observations were applied to bodies 
 very near each other, or in contact, an ad- 
 hesion took place, which is found to be much 
 greater than could be deduced from that 
 law applied to the centres of gravity. Hence 
 they concluded, that the cohesive attraction 
 is governed by a much higher ratio, and pro- 
 bably the cubes of the distances. The mo- 
 dems, on the contrary, among whom are 13erg- 
 mann, Guyton- Morveau, and others, have 
 remarked, that these deduction* are too ge- 
 
ATT 
 
 ATT 
 
 neral, because, for the most part, drawn 
 from the consideration of spherical bodies, 
 which admit of no contact but such as is in- 
 definitely small, and exert the same powers 
 on each other, whichever side may be ob- 
 verted. They remark, likewise, that the 
 consequence depending on the sum of the 
 attractions in bodies not spherical, and at 
 minute distances from each other, will not 
 follow the inverted ratio of the square of the 
 distance taken from any point assumed as 
 the centre of gravity, admitting the particles 
 to be governed by that law ; but that it will 
 greatly differ, according to the sides of the 
 solid which are presented to each other, and 
 their respective distances ; insomuch that the 
 attractions of certain particles indefinitely 
 near each other will be indefinitely increased, 
 though the ratio of the powers acting upon 
 the remoter particles may continue nearly 
 the same. 
 
 This doctrine, which however requires to 
 be much more strictly' examined by the ap- 
 plication of mathematical principles, obvi- 
 ously points to a variety of interesting con- 
 sequences. The polarity of particles, or 
 their disposition to present themselves in 
 their approach to each other in certain as- 
 pects, though it has been treated as a chime- 
 rical notion by a few writers, is one of the 
 first of these results. 
 
 These are speculations, which, with re- 
 gard to the present state of chemistry, stand 
 in much the same situation as the theory of 
 gravity, which is minutely described in Plu- 
 tarch, did with regard to astronomy before 
 the time of Newton. As the celestial phe- 
 nomena were formerly arranged from ob- 
 servation merely, but are now computed 
 from the physical cause, gravitation ; so, at 
 present, chemistry is the science of matter of 
 fact duly arranged, without the assistance of 
 any extensive theory immediately deduced 
 from the figures, volumes, densities, or mu- 
 tual actions of the particles of bodies. What 
 it may hereafter be, must depend on the 
 ability and research of future chemists; but 
 at present we must dismiss this remoter part 
 of theory, to attend more immediately to the 
 facts. 
 
 I hat the parts oi bodies do attract each 
 other, is evident from that adhesion which 
 produces solidity, and requires a certain 
 force to overcome it. For the sake of per- 
 spicuity, the various effects of attraction have 
 beeu considered as different kinds of affinity 
 or powers. That power which physical 
 writers call the attraction of cohesion, is ge- 
 nerally called tlie attraction of aggregation 
 by chemists. Aggregation is considered as 
 the adhesion of parts of the same kind. 
 Thus a number of pieces of brimstone united 
 by fusion, form an aggregate, the parts of 
 which may be separated again by mechanical 
 means. These parts have been called inte- 
 
 grant parts ; that is to say, the minutest 
 parts into which a body can be divided, 
 either really or by the imagination, so as not 
 to change its nature, are called integrant 
 parts. Thus, if sulphur and an alkali be 
 combined together, and form liver of sul- 
 phur, we may conceive the mass to be divid- 
 ed and subdivided to an extreme degree, 
 until at length the mass consists of merely 
 a particle of brimstone and a particle of al- 
 kali. This then is an integrant part; and if 
 it be divided further, the effect which che- 
 mists call decomposition will take place ; 
 and the particles, consisting no longer of 
 liver of sulphur* but of sulphur alone, and 
 alkali alone, will be what chemists call com- 
 ponent parts or principles. 
 
 The union of bodies in a gross way is 
 called mixture. Thus sand and an alkali 
 may be mixed together. But when the 
 very minute parts of a body unite with 
 those of another so intimately as to form a 
 body which has properties different from 
 those of cither of them, the union is called 
 combination, or composition. Thus, if sand 
 and an alkali he exposed to a strong heat, 
 the minute parts of the mixture combine, 
 and form glass. 
 
 The earlier chemists were verv desirous of 
 
 * 
 
 ascertaining the first principles, or elements 
 of bodies ; and they distinguished by this 
 name such substances as their art was inca- 
 pable of rendering more simple. They seem 
 however to have overlooked the obvious cir- 
 cumstance, that the limits of art are not the 
 limits of nature. At present we hear little 
 concerning elements. Those substances 
 which we have not hitherto been able to 
 analyze, or which, if decomposed, have 
 hitherto eluded the observation of' chemists, 
 are indeed considered as simple substances 
 relative to the present state of our know- 
 ledge, but in no other respect; for a variety 
 of experiments give us reason to hope, that 
 future inquiries may elucidate their nature 
 and composition. Some writers, calling these 
 simple substances by the name of Primary 
 Principles, have distinguished compounds of 
 these by the name of Secondary Principles, 
 which they suppose to enter again into com- 
 binations without decomposition or change. 
 It must be confessed, nevertheless, that no 
 means have yet been devised to show whe- 
 ther any such subordination of principles ex- 
 ists. Wc may indeed discover, that a com- 
 pound body consists of three or more prin- 
 ciples ; but whether two of these be previ- 
 ously united, so as to form a simple sub- 
 stance with relation to the third, or what in 
 other respects mnv be their arrangement, we 
 do not know. That it does exist, however, 
 seems clear by making combinations in va- 
 ried orders. Thus a weak solution of alkali 
 will not dissolve oil ; but n combination of 
 oil and alkali will noi; separate by the addu 
 
ATT 
 
 ATT 
 
 tion of water. The alkali therefore adheres 
 to that with which it was first combined. 
 See also the article Vegetables. 
 
 It two solid bodies, disposed to combine 
 together, be brought into contact with each 
 other, the particles which touch will com- 
 bine, and form a compound ; and if the 
 temperature at which this new compound 
 assumes the fluid form be higher than the 
 temperature of the experiment, the process 
 will go no further, because this new com- 
 pound being interposed between the two 
 bodies, will prevent their further access to 
 each other; but if, on the contrary, the 
 freezing point of the compound be lower 
 than this temperature, liquefaction w ill en- 
 sue ; and the fluid particles being at liberty 
 to arrange themselves according to the law 
 of their attractions, the process will go on, 
 and the whole mass will gradually be con- 
 verted into a new compound in the fluid 
 state. An instance of this may be exhibited 
 by mixing common salt and perfectly dry 
 pounded ice together. The crystals of the 
 salt alone will not liquefy unless very much 
 heated ; the crystals of the water, that is to 
 say, the ice, will not liquefy unless heated 
 as high as thirty-two degrees of Fahrenheit ; 
 and we have of course supposed the tempe- 
 rature of the experiment to be low r er than 
 this, because our water is in the solid state. 
 Now it is a well known fact, that brine, or 
 the saturated solution of sea salt in water, 
 cannot be frozen unless it he cooled thirty- 
 eight degrees lower than the freezing point 
 of pure water. It follows then, that, if the 
 temperature of the experiment be higher 
 than this, the first combinations of salt and 
 ice will produce a fluid brine, and the com- 
 bination will proceed until the temperature 
 of the mass has gradually sunk as low as 
 the freezing point of brine ; after which it 
 would cease, if it were not that surround- 
 ing bodies continually tend to raise the 
 temperature. And accordingly it is found 
 by experiment, that, if the ice and the salt 
 be previously cooled below the tempera- 
 ture of freezing brine, the combination and 
 liquefaction will not take place. See Ca- 
 loric. 
 
 The instances in which solid bodies thus 
 combine together not being very numerous, 
 and the fluidity which ensues immediately 
 after the commencement of this kind of ex- 
 periment, have induced several chemists to 
 consider fluidity in one or both of the bo- 
 dies applied to each other, to be a necessary 
 circumstance, in order that they may pro- 
 duce chemical action upon each other. Cor- 
 pora non a x unt nisi sint Jlnida. 
 
 If one of two bodies applied to each other 
 be fluid at the temperature of the experi- 
 ment, its parts will successively unite with 
 the parts of the solid, which will by that 
 
 means be suspended in the fluid, and disap- 
 pear. Such a fluid is called a solvent or 
 menstruum ; and the solid body is said to be 
 dissolved. 
 
 Some substances unite together in all pro- 
 portions. In this way the acids unite with 
 water. But there are likewise many sub- 
 stances which cannot be dissolved in a fluid, 
 at a settled temperature, in any quantity 
 beyond a certain proportion. Thus, water 
 w'ill dissolve only about one-third of its 
 weight of common salt ; and if more salt bo 
 added, it will remain solid. A fluid which 
 holds in solution as much of any substance 
 as it can dissolve, is said to be saturated with 
 it. But saturation with one substance is so 
 far from preventing a fluid from dissolving 
 another body, that it very frequently hap- 
 pens, that the solvent power of the com- 
 pound exceeds that of the original fluid it- 
 self. Chemists likewise use the word satu- 
 ration in another sense ; in which it denotes, 
 such a union of two bodies as produces a 
 compound the most remote in its properties 
 from the properties of the component parts 
 themselves. In combinations where one of 
 the principles predominates, the one is said 
 to be supersaturated, and the other principle 
 is said to be subsaturated. 
 
 Heat in general increases the solvent power 
 of fluids, probably by pieventing part of the 
 dissolved substance from congealing, or as- 
 suming the solid form. 
 
 It often happens, that bodies which have 
 no tendency to unite are made to combine 
 together by means of a third, which is then 
 called the medium. Thus, water and fat 
 oils are made to unite by the medium of an 
 alkali, in the combination called soap. Some 
 writers, who seem desirous of multiplying 
 terms, call this tendency to unite the affinity 
 of' intermedium. This case has likewise 
 been called disposing affinity ; but Berthollet 
 more properly styles it reciprocal affinity. 
 lie likewise distinguishes affinity into ele - 
 mentary , when it is betw een the elementary 
 parts of bodies ; and resulting, when it is to 
 a compound only, and w-ould not take place 
 with the elements of that compound. 
 
 It very frequently happens, on the con- 
 trary, that the tendency of two bodies to 
 unite, or remain in combination together, 
 is weakened or destroyed by the addition of 
 a third. Thus, alcohol unites with water in 
 such a manner as to separate most salts from 
 it. A striking instance of this is seen in a 
 saturated or strong solution of nitre in water. 
 If to this there be added an equal measure 
 of alcohol, the greater part of the nitre in- 
 stantly falls down. Thus magnesia is sepa- 
 rated from a solution of Epsom salt, by the 
 addition of an alkali, which combines with 
 the sulphuric acid, and separates the earth. 
 The principle which falls down is said to l ® 
 
ATT 
 
 ATT 
 
 precipitated, and in many instances is called 
 a precipitate. Some modern chemists use 
 the term precipitation in a more extended, 
 and rather forced sense ; for they apply it 
 to all substances thus separated. In this 
 enunciation, therefore, they would say, that 
 potash precipitates soda from a solution of 
 common salt, though no visible separation or 
 precipitation takes place ; for the soda, when 
 disengaged from its acid, is still suspended 
 in the water by reason of its solubility. 
 
 From a great number of facts of this na- 
 ture it is clearly ascertained, not as a pro- 
 bable hypothesis, but as simple matter of 
 fact, that some bodies have a stronger ten- 
 dency to unite than others ; and that the 
 union of any substance with another will 
 exclude, or separate, a third substance, which 
 might have been previously united with one 
 of them ; excepting only in those cases 
 wherein the new compound has a tendency 
 to unite with that third substance, and form 
 a triple compound. This preference of unit-, 
 ing, which a given substance is found to ex- 
 hibit with regard to other bodies, is by an 
 easy metaphor called elective attraction, and 
 is subject to a variety of cases, according to 
 the number and the powers of the principles 
 which are respectively presented to each 
 other. The cases which have been most 
 frequently observed by chemists, are those 
 called simple elective attractions, and double 
 elective attractions. 
 
 When a simple substance is presented or 
 applied to another substance compounded of 
 two principles, and unites with one of these 
 two principles so as to separate or exclude 
 the other, this effect is said to be produced 
 by simple elective attraction. 
 
 It may be doubted whether any of our 
 operations have been carried to this degree 
 of simplicity. All the chemical principles 
 we are acquainted with are simple only 
 with respect to our power of decomposing 
 them ; and the daily discoveries of our con- 
 temporaries tend to decompose those sub- 
 stances, which chemists a few years ago 
 considered as simple. Without insisting, 
 however, upon this difficulty, we may ob- 
 serve, that water is concerned in all the ope- 
 rations which arc called humid, and beyond 
 a doubt modifies all the effects of such bodies 
 as are suspended in it; and the variations of 
 temperature, whether arising from an actual 
 igneous fluid, or from a mere modification 
 of the parts of bodies, also tend greatly to 
 disturb the effects of elective attraction. 
 These causes render it difficult to point out 
 an example of simple elective attraction, 
 which may in strictness be reckoned as 
 such. 
 
 Double elective attraction takes place 
 when two bodies, each consisting of two 
 principles, are presented to each other, and 
 mutually exchange a principle of each ; by 
 
 which means two new bodies, or compounds, 
 are produced, of a different nature from the 
 original compounds. 
 
 Under the same limitations as were point- 
 ed out in speaking of simple elective attrac- 
 tion, we may offer instances of double elec- 
 tive attraction. Let oxide of mercury be 
 dissolved to saturation in the nitric acid, the 
 water will then contain nitrate of mercury. 
 Again, let potash be dissolved to saturation 
 in the sulphuric acid, and the result will be 
 a solution of sulphate of potash. If mercury 
 were added to the latter solution, it would 
 indeed tend to unite with the acid, but 
 would produce no decomposition ; because 
 the elective attraction of the acid to the al- 
 kali is the strongest. So likew ise, if the ni- 
 tric acid alone be added to it, its tendency 
 to unite with the alkali, strong as it is, will 
 not effect any change, because the alkali is 
 already in combination w’ith a stronger acid. 
 But if the nitrate of mercury be added to 
 the solution of sulphate of potash, a change 
 of principles will take place, the sulphuric 
 acid will quit the alkali, and unite with the 
 mercury, while the nitric acid combines 
 with the alkali; and these two new salts, 
 namely, nitrate of potash, and sulphate of 
 mercury, may be obtained separately by crys- 
 tallization. 
 
 The most remarkable circumstance in this 
 process is, that the joint effects of the attrac- 
 tions of the sulphuric acid to mercury, and 
 the nitric acid to alkali, prove to be stronger 
 than the sum of the attractions between the 
 sulphuric acid and the alkali, and between 
 the nitrous acid and the mercury ; for, if 
 the sum of these two last had not been 
 w eaker, the original combinations would not 
 have been broken. 
 
 Mr Kirwan, w ho first, in the year 1 78?, 
 considered this subject with that attention it 
 deserves, called the affinities which tend to 
 preserve the original combinations, the qui- 
 escent affinities. He distinguished the affi- 
 nities or attractions which tend to produce a 
 change of principles, by the name of the di- 
 vellent affinities. 
 
 Some eminent chemists are disposed to 
 consider as effects of double affinities, those 
 changes of principles only which would not 
 have taken place without the assistance of a 
 fourth principle. Thus, the mutual decom- 
 position of sulphate of soda and nitrate of 
 potash, in which the alkalis are changed, and 
 sulphate of potash and nitrate of soda are 
 produced, is not considered by them as an 
 instance of double decomposition ; because 
 the nitre would have been decomposed by 
 simple elective attraction, upon the addition 
 of the acid only. 
 
 There are various circumstances which 
 modify the effects of elective attraction, and 
 have from time to time misled chemists in 
 their deductions. The chief of these is the 
 
ATT 
 
 ATT 
 
 temperature, which, acting differently upon 
 the several parts of compounded bodies, sel- 
 dom fails to alter, and frequently reverses 
 the effects of the affinities. Thus, if alcohol 
 be added to a solution of nitrate of potash, 
 it unites with the water, and precipitates the 
 salt at a common temperature. But if the 
 temperature be raised, the alcohol rises on 
 account of its volatility, and the salt is again 
 dissolved. Thus again, if sulphuric acid be 
 added, in a common temperature, to a com- 
 bination of phosphoric acid and lime, it will 
 decompose the salt, and disengage the phos- 
 phoric acid ; but if this same mixture of 
 these principles be exposed to a considerable 
 heat, the sulphuric acid will have its attrac- 
 tion to the lime so much diminished, that it 
 will rise, and give place again to the phos- 
 phoric, which will combine with the lime. 
 Again, mercury kept in a degree of heat 
 very nearly equal to volatilizing it will ab- 
 sorb oxygen, and become converted into the 
 red oxide formerly called precipitate per sc ; 
 but if the heat be augmented still more, the 
 oxygen will assume the elastic state, and fly 
 off, leaving the mercury in its original state. 
 Numberless instances of the like nature con- 
 tinually present themselves to the observa- 
 tion of chemists, which are sufficient to esta- 
 blish the conclusion, that the elective attrac- 
 tions are not constant but at one and the 
 same temperature. 
 
 Many philosophers are of opinion, that 
 the variations produced by change of tempe- 
 rature arise from the elective attraction of 
 the matter of heat itself. But there arc no 
 decisive experiments either in confirmation 
 or refutation of this hypothesis. 
 
 If we except the operation of heat, which 
 really produces a change in the elective at- 
 tractions, we shall find, that most of the 
 other difficulties attending this subject arise 
 from the imperfect state of chemical science. 
 If to a compound of two principles a third 
 be added, the effect of this must necessarily 
 be different according to its quantity, and 
 likewise according to the state of saturation 
 of the two principles of the compounded 
 body. If the third principle which is added 
 be iii excess, it may dissolve and suspend the 
 compound which may be newly formed, and 
 likewise that which might have been preci- 
 pitated. The metallic solutions, decom- 
 posed by the addition of an alkali, afford no 
 precipitate in various cases when the alkali 
 is in excess ; because this excess dissolves 
 the precipitate, which would else have fallen 
 down. If, on the other hand, one of the 
 two principles of the compound body be in 
 excess, the addition of a third substance may 
 combine with that excess, and leave a neu- 
 tral substance, exhibiting very different 
 properties from the former. Thus, it cream 
 of tartar, which is a salt of difficult solubi- 
 lity, consisting of potash united to an excess 
 
 of the acid of tartar, be dissolved in water, 
 and chalk be added, the excess unites with 
 part of the lime of the chalk, and forms a 
 scarcely soluble salt; and the neutral com- 
 pound, which remains after the privation 
 of this excess of acid, is a very soluble salt, 
 greatly differing in taste and properties from 
 the cream of tartar. The metals and the 
 acids likewise afford various phenomena, 
 according to their degree of oxidation. A 
 determinate oxidation is in general necessary 
 for the solution of metals in acids; and the 
 acids themselves act very differently, ac- 
 cordingly as they are more or less acidified. 
 Thus, the nitrous acid gives place to acids 
 which are weaker than the nitric acid : the 
 sulphurous acid gives place to acids greatly 
 inferior in attractive power or affinity to the 
 sulphuric acid. The deception arising from 
 effects of this nature is in a great measure 
 produced by the want of discrimination on 
 the part of chemical philosophers ; it being- 
 evident, that the properties of any com- 
 pound substance depend as much upon the 
 proportion of its ingredients, as upon their 
 respective nature. 
 
 The presence and quantity of water is 
 probably of more consequence than is yet 
 supposed. Thus, bismuth is dissolved in 
 nitrous acid, but falls when the water is 
 much in quantity. The same is true of anti- 
 mony. Hibaucout has shown the last( Annak*3 
 de Chimie, xv. 122.) in alum, and it is like- 
 ly that the fact is more common than is sus- 
 pected. Whether the attraction and strength, 
 as to quantity in saturation, he not variable 
 by the presence or absence of water, must 
 be referred to experiment 
 
 The power of double elective attractions 
 too, is disturbed by this circumstance. If 
 muriate of lime be added to a solution of 
 carbonate of soda, they are both decompos- 
 ed, and the results are muriate of soda and 
 carbonate of lime. But if lime and muriate 
 of soda be mixed with just water sufficient 
 to make them into a paste, and this be ex- 
 posed to the action of carbonic acid gas, a 
 saline efflorescence consisting of carbonate 
 cf soda will be formed on the surface, and 
 the bottom of the vessel will be occupied 
 by muriate of lime in a state of deliques- 
 cence. 
 
 M. Berth ollct made a great number of 
 experiments, from which he deduced the fol- 
 lowing law : — that in elective attractions the 
 power exerted is not in the ratio of the affi- 
 nity simply, but in a ratio compounded of 
 the force of affinity and the quantity of the 
 agent ; so that quantity may compensate for 
 weaker affinity. Thus an acid which has a 
 weaker affinity than another lor a given 
 base, if it be employed in a certain quanti- 
 ty, is capable of taking part of that base 
 from the acid which has a stronger affinity 
 for it ; so that the base will be divided be- 
 
ATT 
 
 ATT 
 
 tween them in the compound ratio of their 
 affinity and quantity. This division of one 
 substance between two others, for which it 
 has different affinities, always takes place, 
 according to him, when three such are pre- 
 sent under circumstances in which they can 
 mutually act on each other. And hence it 
 is, that the force of affinity acts most power- 
 fully when two substances first come into 
 contact, and continues to decrease in power 
 as either approaches the point of saturation. 
 For the same reason it is so difficult to sepa- 
 rate the last portions of any substance ad- 
 hering to another. Hence, if the doctrine 
 laid down by M. Berthollet be true, to its 
 utmost extent, it must be impossible ever to 
 free a compound completely from any one 
 of its constituent parts by the agency of 
 elective attraction ; so that all our best esta- 
 blished analyses are more or less inaccu- 
 rate. 
 
 The solubility or insolubility of princi- 
 ples, at the temperature of any experiment, 
 has likewise tended to mislead chemists, 
 who have deduced consequences from the 
 first effects of their experiments. It is evi- 
 dent, that many separations may ensue with- 
 out precipitation; because this circumstance 
 does not take place unless the separated 
 principle be insoluble, or nearly so. The 
 soda cannot be precipitated from a solution 
 of sulphate of soda, by the addition of pot- 
 ash, because of its great solubility ; but, on 
 the contrary, the new compound itself, or 
 sulphate of potash, which is much less solu- 
 ble, may fall down, if there be not enough 
 water present to suspend it. No certain 
 knowledge can therefore be derived from 
 the appearance or the want of precipitation, 
 unless the products be carefully examined. 
 In some instances all the products remain 
 suspended, and in others they all fall down, 
 as may be instanced in the decomposition of 
 sulphate of iron by lime. Here the acid 
 unites with the lime, and forms sulphate of 
 lime, which is scarcely at all soluble ; and 
 the still less soluble oxide of iron, w hich w r as 
 disengaged, falls down along with it. 
 
 Many instances present themselves, in 
 which decomposition does not take place, 
 but a sort of equilibrium of affinity is per- 
 ceived. I bus, soda, added to the supertar- 
 tiate of potash, forms a triple salt by com- 
 bining with its excess of acid. So likewise 
 ammonia combines with a portion of the 
 acid of muriate of mercury, and forms the 
 triple compound formerly distinguished by 
 the barbarous name of sal alembroth. 
 
 When we reflect maturely upon all the 
 circumstances enumerated, or slightly touch- 
 ed upon, in the foregoing pages, we may 
 form some idea of the extensive field of re- 
 search, w hich yet remains to be explored by 
 chemists. If it. were possible to procure 
 simple substances, and combine two together, 
 
 and to this combination of two to add one 
 more of the other simple substances, the re- 
 sult of the experiment would in many cases 
 determine, by the exclusion of one of the 
 three, that its affinity to either of the remain- 
 ing two w'as less than that between those two 
 
 o 
 
 respectively. In this way it would be as- 
 certained, in the progress of experimental 
 inquiry, that the simple attractions of a 
 series of substances were gradually increas- 
 ing or diminishing in strength. Thus, am- 
 monia separates alumina from the sulphuric 
 acid ; magnesia, in like manner, separates 
 the ammonia ; lime predominates, in the 
 strength of affinity, over magnesia, as ap- 
 pears by its separating this last earth ; the 
 soda separates the lime, and itself gives place 
 to the potash ; and, lastly, potash yields its 
 acid to barytes. The simple elective attrac- 
 tions of these several substances to sulphuric 
 acid, are therefore in the inverted order of 
 their effects : barytes is the strongest ; and 
 this is succeeded regularly by potash, soda, 
 lime, magnesia, ammonia, and alumina. It 
 is evident, that results of this nature, being 
 tabulated, as was first done bv the celebrated 
 Geoffroy, and afterward by Bergmann, must 
 afford a valuable mass of chemical know- 
 ledge. It must be remarked, however, that 
 these results merely indicate, that the powers 
 are greater or less than each other ; but how' 
 much greater or less is not determined, either 
 absolutely or relatively. Tables of this na- 
 ture cannot therefore inform us of the effects 
 which may take place in the way of double 
 affinity, for want of the numerical relations 
 between the attracting powers. Thus, when 
 we are in possession of the order of the sim- 
 ple elective attractions between the sulphuric 
 acid and a series of substances, and also be- 
 tween the nitrous acid and the same sub- 
 stances; and when, in addition to this, the 
 respective powers of each of the acids upon 
 every one of the substances singly taken, are 
 known, so far as to determine which will 
 displace the other ; yet we cannot thence 
 foretell the result of applying two combina- 
 tions to each other, each containing an acid 
 united with one of the number of simple 
 substances. Or, more concisely, a table of 
 simple elective attractions can be of no use 
 to determine the effects of double elective 
 attraction, unless the absolute power of the 
 attractions be expressed by number instead 
 of their order merely. 
 
 * It has been often remarked, that the 
 action of a substance is diminished in pro- 
 portion as it approaches to a state of satura- 
 tion ; and this diminution of power lias been 
 employed to explain several chemical pheno- 
 mena. Itis likewise known, that the resistance 
 found in expelling a substance from the last 
 portions of a combination, either by affinity 
 or heat, is much greater than at the com- 
 mencement ot die decomposition, and sonic- 
 
ATT 
 
 ATT 
 
 times such, that its entire decomposition can- 
 not be effected. Thus the black oxide of 
 manganese exposed to heat will part with 
 only a certain definite quantity of its oxygen. 
 No degree of heat can expel the whole. 
 
 According to Berthollet, when two sub- 
 stances are in competition to combine with a 
 third, each of them obtains a degree of satura- 
 tion proportionate to its affinity multiplied by 
 its quantity, a product, which he denominates 
 mass. The subject of the combination di- 
 vides its action in proportion to the masses, 
 and by varying the latter, this illustrious 
 chemist thinks, that the results also will be 
 varied. The following are the forces which 
 he regards as exercising a great influence 
 upon chemical combinations and phenomena, 
 by concurring with or opposing the mutual 
 affinity of the substances brought into action. 
 1. The action of solvents, or the affinity 
 which they exert according to their propor- 
 tion. Thus, if into a very dilute solution of 
 muriate of lime, a solution of sulphate of 
 soda be poured, no precipitate of sulphate of 
 lime will happen, though the quantity of the 
 solvent water be less than is necessary to 
 dissolve the calcareous sulphate. If the 
 same two saline solutions be mixed with less 
 water, the sulphate of lime will fall in a few 
 seconds, or a few minutes, according to the 
 strength of the mingled solutions. 2. The 
 force of cohesion, which is the effect of the 
 mutual affinity of the particles of a substance 
 or combination. Hence we can easily see 
 why a solution of pure potash, which so 
 readily dissolves pulverulent alumina, has no 
 effect on alumina concreted and condensed 
 in the oriental gems. The lowest red heat 
 kindles charcoal, or determines its combina- 
 tion with atmospherical oxygen ; but a much 
 higher temperature is requisite to burn the 
 same carbonaceous matter, more densely 
 aggregated in the diamond. 3. Elasticity, 
 whether natural or produced by heat ; which 
 has, by some, been considered as the affinity 
 of caloric. Of Che influence of this power 
 a fine illustration is afforded by muriate of 
 lime and carbonate of ammonia. \\ hen a 
 solution of the latter salt is poured into one 
 of the former, a double decomposition in- 
 stantly takes place : carbonate of lime falls 
 to the bottom in powder, and muriate ol am- 
 monia floats above. Let this liquid mixture 
 he boiled for some time ; exhalation of ara- 
 moniacal gas will be perceived by the nostrils, 
 and the carbonate of lime will be redissolv- 
 ed ; as may be proved by the further addi- 
 tion of carbonate of ammonia. This will 
 cause an earthy precipitate from the liquid, 
 which prior to ebullition was merely rmuiate 
 of ammonia. 4. Efflorescence, a power which 
 acts only under very rare circumstances. It 
 is exemplified in the natron lakes of Egypt ; 
 on the margin of which, according to Ber- 
 thollet, carbonate oflime decomposes muriate 
 
 of soda, in consequence of the efflorescing 
 property of the resulting carbonate. 5. 
 Gravity likewise exerts its influence, parti- 
 cularly when it produces the compression of 
 clastic fluids ; but it may always without in- 
 convenience be confounded with the force of 
 cohesion. 
 
 M. Berthollet thinks, that as the tables of 
 affinity have all been constructed upon the 
 supposition that substances possess different 
 degrees of affinity, which produce the decom- 
 positions and combinations that are formed, 
 independently of the proportions and other 
 conditions which contribute to the results, 
 these tables are calculated only to give a 
 false idea of the degrees of chemical action 
 of the substances arranged in them. “ The 
 denomination of elective affinity,” says he, 
 “ is in itself erroneous, since it supposes the 
 union of one entire substance with another, 
 in preference to a third, while there is only 
 a division of action, subjected to other che- 
 mical conditions.” The force of cohesion, 
 which was formerly considered merely as an 
 obstacle to solution, limits not only the 
 quantities of substances which maybe brought 
 into action in a liquid, and consequently 
 modifies the conditions of the saturation 
 which follows ; hut it is the power which 
 causes the precipitations and crystallizations 
 that take place, and determines the propor- 
 tions of such combinations as are made by 
 quitting the liquid ; it is this force which 
 sometimes even produces the separation of a 
 substance, without its forming any combina- 
 tion witli another substance, as has been re- 
 marked in metallic precipitations. Elasticity 
 acts by producing effects opposite to those of 
 cohesion, and which consists either in with- 
 drawing some substances from the action of 
 others in a liquid, or in diminishing the pro- 
 portion which exists within the sphere of ac- 
 tivity ; but when all the substances are in 
 the elastic state, their action is subjected 
 to the same conditions. If tables were 
 formed which would represent the dispo- 
 sition to insolubility or volatility, in the 
 different combinations, they would serve to 
 explain a great number of combinations 
 which take their origin from the mixture of 
 different substances, and from the influence 
 of heat. These considerations need not 
 prevent us, says Berthollet, from using the 
 term affinity to denote the whole chemical 
 power of a body exerted in a given situation, 
 even by its present constitution, its propor- 
 tion, or even by the concurrence of other 
 affinities ; but we must avoid considering 
 this power as a constant force, which pro- 
 duces compositions and decompositions. All 
 substances, according to him, exert a mutual 
 action during the time they are in the liquid 
 state; so that in a solution, for example, of 
 sulphate of potash and muriate of soda, these 
 
 two salts arc not distinct, while there is no 
 
ATT 
 
 ATT 
 
 cause to determine the separation from their 
 combination ; but there exists in this li- 
 quid, sulphuric acid, muriatic acid, soda, 
 and potash. In like manner, when the pro- 
 per quantity of carbonate of potash is added 
 to muriate of soda, the mingled solution does 
 not consist of carbonate of soda and muriate 
 of potash, resulting from complex affinity, 
 but contains simply muriatic and carbonic 
 acids with potash and soda, in quadruple 
 union and saturation. It is the crystallizing 
 property of the soda carbonate which, after 
 due evaporation, determines the definite de- 
 composition, and not any power of elective 
 Attraction. Or generally, when one substance 
 separates from a combination by the intro- 
 duction of another, it is not merely from 
 being supplanted by the superior affinity of 
 an antagonist, but because its intrinsic ten- 
 dency to the solid or gaseous form educes it 
 from its former associate. There is certainly 
 much truth in this proposition of Berthollet. 
 
 But. with regard to the indefinite parti- 
 tion of a base between two rival acids, and 
 of an acid between two rival bases, a doc- 
 trine which that profound philosopher la- 
 boured to establish by a wide experimental 
 induction, many facts of an irreconcileable 
 nature occur. Sir H. Davy has remarked 
 with his usual good judgment, that were this 
 proposition correct, it is evident that there 
 could be scarcely any definite proportions; 
 a salt crystallizing in a strong alkaline solu- 
 tion would be strongly alkaline ; in a weak 
 one, less alkaline ; while in an acid solution 
 it would be acid. But this does not seem 
 to be the case. In combinations of gaseous 
 bodies, whose constitution gives their par- 
 ticles perfect freedom of motion, the propor- 
 tions are definite and unchangeable, how- 
 ever we may change the proportions of the 
 aeriform mixture. And in all solid com- 
 pounds that have been accurately examined, 
 in which there is no chance of mechanical 
 mixture, the same law seems to prevail. 
 Different bodies may indeed be dissolved in 
 different menstrua in very various propor- 
 tions, but the result may be regarded as a 
 mixture of different solutions, rather than a 
 combination. With regard to glasses and 
 metallic alloys, adduced by Berthollet, it is 
 sufficient to know that the points of fusion 
 of alkali, glass, and oxides of lead and tin, 
 are so near each other, that transparent mix- 
 tures of them may be formed. The attrac- 
 tive power of matter is undoubtedly general, 
 hut in the formation of aggregates, certain 
 definite arrangements take place. Bergmann 
 observed long ago, that when nitric acid was 
 digested on sulphate of potash, a portion of 
 nitre was formed, in apparent contradiction 
 to the superior affinity which lie had assign- 
 ed to sulphuric acid for the potash. But 
 he also gave what appears to lie a satisfac- 
 tory explanation of this seeming anomaly, 
 
 which Berthollet has adduced in support of his 
 views of indefinite and universal partition. 
 
 Sulphuric acid tends to combine in two 
 distinct but definite proportions with potash, 
 forming the neutral sulphate and the bisul- 
 phate. Nitric acid may therefore abstract from 
 the neutral salt, that portion of potash which 
 it should lose to pass into the acidulous 
 salt ; but it will not deprive it of any more. 
 Hence this very example is decidedly ad- 
 verse to the indefinite combinations and suc- 
 cessive partitions taught by Berthollet. The 
 above decomposition resolves itself evident- 
 ly, therefore, into a case of double affinity. 
 That a large quantity of pure potash can 
 separate a little sulphuric acid from the sul- 
 phate of barytes, has been stated by Berthol- 
 let; but it is a circumstance difficult to de- 
 monstrate. If the operation be conducted 
 with access of air, then carbonate of potash 
 is readily formed, and a well known double 
 affinity comes into play, viz. that of barytes 
 for carbonic acid on one hand, and of sul- 
 phuric acid for potash on the other. Sup- 
 posing the agency of carbonic acid to be ex- 
 cluded, then are we to believe that the pot- 
 ash having become a soluble sulphate, exists 
 in liquid union with pure barytes ? See M. 
 Dulong’s experiments, further on. 
 
 When M. Berthollet separated a little 
 potash from sulphuric acid by soda, he 
 merely formed a little bisulphate of potash, 
 while the free potash united to the Mater 
 and alcohol, for which it has a strong affi- 
 nity, and sulphate of soda was also formed. 
 This, therefore, is a very intelligible case of 
 compound attraction. According to 3V1. 
 Berthollet, Mhenever an earth is precipitated 
 from a saline combination, by an alkali, it 
 should carry down with it a portion of its 
 acid associate. But sulphate of magnesia 
 acted on by potash, yields an earthy precipi- 
 tate, which, after proper washing, betrays 
 the presence of no retained sulphuric acid, 
 'i he neutral salts of soda and potash part 
 with none of their acid to magnesia, by the 
 longest digestion in their solutions. If on 
 the tartrate of lime, or oxalate of lead, the 
 portion of sulphuric acid adequate to saturate 
 these respective bases be poured, entire de- 
 composition Mill be effected without any 
 partition whatever. Now, sulphate of lime, 
 M’hich is the result in the first case, being 
 actually a much more soluble salt than the 
 tartrate, we should expect a portion of the 
 latter to resist decomposition by the aid of 
 its cohesive force. A plate of iron plunged 
 into a solution of sulphate of copper, sepa- 
 rates the whole of the latter metal. An 
 equally absolute decomposition is effected 
 by zinc on the saline solutions of lead and 
 tin. I lie sum (otal ol oxygen and acid is 
 here transferred to the decomposing body, 
 without any partition whatever. 
 
 We have already observed, that sulphate 
 
ATT 
 
 ATT 
 
 of barytes digested in a hot solution of car- 
 bonate of potash, gives birth to a portion of 
 carbonate of barytes and sulphate of potash. 
 But by M. Dulong’s experiment, the reverse 
 decomposition is possible, viz. carbonate of 
 barytes being digested in solution of sul- 
 phate ol potash, we obtain sulphate of barytes 
 and carbonate of potash. Are we lienee to 
 infer, that sulphate of barytes and carbonate 
 of potash having for some time amused the 
 operator by the production of an alkaline 
 sulphate and earthy carbonate, will change 
 their mood, and, retracing their steps, restore 
 things to their pristine condition ; and thus 
 in alternate oscillation for ever? 
 
 If chlorine gas be made to act on the ox- 
 ides of mercury, tin, or antimony, it will 
 unite to the metallic base, and displace every 
 particle cf the oxygen. Now, the resulting 
 chlorides cannot owe their purity to any su- 
 periority of cohesive force which they possess 
 over the oxides, which, on the contrary, are 
 both denser and more fixed than the new 
 compounds. Finally, if 25 parts of pure 
 magnesia mixed with 35.6 of dry lime, be 
 digested in 85 parts of nitric acid, sp. gr. 
 1.500, diluted with water, we shall find that 
 the whole lime will be dissolved, but not a 
 particle of the magnesia. On decanting the 
 neutral calcareous nitrate, washing and dry- 
 ing the earthy residuum, we shall procure 
 the 25 parts of magnesia unchanged. 
 
 We are, therefore, entitled to affirm, that 
 affinity is elective, acting in the different 
 chemical bodies with gradations of attrac- 
 tive force, liable however to be modified, as 
 we have shewn in the case of muriate of lime 
 and carbonate of ammonia, by temperature, 
 and other adventitious powers. 
 
 Decompositions which cannot be produc- 
 ed by single attractions, may be effected by 
 double affinity ; and that, we may expect 
 with the greater certainty, a priori, if one 
 of the two resulting compounds of the double 
 interchange, naturally exists in the solid or 
 aeriform state. And if the one resulting 
 compound be solid and the other gaseous, 
 then decomposition will be certain and com- 
 plete. This applies with equal force to 
 single affinities, or decompositions. 'I bus 
 when sulphuric acid and muriate ol lime in 
 due proportions are exposed to heat, a per- 
 fect decomposition is accomplished, and pure 
 sulphate of lime and muriatic acid gas are 
 produced. But when the various mixed in- 
 gredients remain in solution , it is then rea- 
 sonable to think with Berthollet, that a reci- 
 procal attraction pervades the whole, modi- 
 fying its nature and properties. Thus solu- 
 tion of sulphate of copper is blue, that of 
 muriate of copper is green. Now, if into 
 a solution of the former salt, we pour muri- 
 atic acid, we shall observe this robbing the 
 sulphuric acid of a quantity of the cupreous 
 oxide, proportional to its mass ; for the more 
 
 muriatic acid we add, the greener will the 
 liquid become. But if, by concentration, the 
 sulphate of copper be suffered to crystallize, 
 the phenomena change; a new force, that 
 of crystallization, is superadded, which aids 
 the affinity of the sulphuric acid, and decides 
 the decomposition. The surplus of each of 
 these acids is employed in counterbalancing 
 the surplus of its antagonist, and need not 
 be considered as combined with the copper. 
 Here, however, we verge on the obscure and 
 unproductive domain of chemical metaphy- 
 sics, a region in which a late respectable sys- 
 tematist delighted to expatiate. 
 
 M. Berthollet estimates the attractive 
 forces or affinities of bodies of the same 
 class, to be inversely as their saturating 
 quantities. Thus, among acids, 50 parts of 
 real sulphuric, will saturate as much pot- 
 ash or soda as Ql\ of real nitric, and as 21\ 
 of carbonic. Thus too, 21^ of ammonia 
 will saturate as much acid as 25 of magne- 
 sia, 35^ of lime, and 5 9| of potash. Hence 
 he infers that the carbonic acid is endowed 
 with a higher affinity than the sulphuric ; 
 and this, than the nitric. The same propo- 
 sition applies to ammonia, magnesia, lime, 
 and potash. But in direct hostility to this 
 doctrine, we have seen lime exercise a greater 
 affinity for the acids than magnesia. And 
 though M. Berthollet has ingeniously 
 sought to explain away the difficulty about 
 potash, ammonia, and carbonic acid, by re- 
 ferring to the solid or gaseous results of 
 their action ; yet it is hard to conceive of so- 
 lidity operating in producing an effect, be- 
 fore solidity exists, and of elasticity operat- 
 ing while the substance is solid or liquid. 
 On this point a good syllogism has been 
 offered by Sir H. Davv. “ 'ihe action,” 
 says this profound chemist, “ between the 
 constituents of a compound, must be mutual. 
 Sulphuric acid, there is every reason to be- 
 lieve, has as much attraction for barytes, as 
 barytes has for sulphuric acid, and barytes is 
 the alkaline substance of which the largest 
 quantity is required to saturate sulphuric 
 acid; therefore, on M. Berthollet’s view, it 
 has the weakest affinity for that acid ; hut 
 less sulphuric acid saturates this substance 
 than any other earthy or alkaline body. 
 Therefore, according to M. Berthollet, sul- 
 phuric acid has a stronger affinity for barytes 
 than for any other substance ; which is con- 
 tradictory.” 
 
 In the table of chemical equivalents at 
 the. end of the Dictionary, will be found a 
 view of the definite proportions in which the 
 various chemical bodies combine, referred to 
 their primary or lowest numerical terms, vul- 
 garly called the weights ol the atoms. 
 
 * Mr Higgins, the real author ot the 
 Atomic Theory, in first promulgating its 
 principles in his Comparative Mew of the 
 Phlogistic and Antiphlogistic Hypothecs 
 
ATT 
 
 ATT 
 
 connected their exposition with general 
 views of the relative forces of affinity among 
 the combining particles. These forces he 
 illustrates by diagrams, to which I have ad- 
 verted, in the article Equivalents (Chemi- 
 cal). This joint consideration of combining 
 force , and combining ratio , has been neglect- 
 ed by subsequent writers; whence, Mr Hig- 
 gins says, “ The atomic doctrine has been 
 applied by me in abstruse and difficult re- 
 searches. Its application by Mr Dalton, 
 has been in a general and popular way ; and 
 it is from these circumstances alone, that it 
 gained the name of Dalton’s Theory. * 
 
 * Since the chemical statics appeared, perhaps 
 no chemist has contributed so many impor- 
 tant facts to the doctrines of affinity as M. 
 Dulong. His admirable inquiries concern- 
 ing the mutual decomposition of soluble and 
 insoluble salts, were presented to the Na- 
 tional Institute, and afterwards published in 
 the Annales de Chimie, tom. 82 ; from which 
 they were translated into the 35th and 36th 
 volumes of Nicholson’s Journal, and an ab- 
 stract of them was given in the 41st vol. of 
 the Phil. Mag. Notwithstanding such means 
 of notoriety, it is amusing to observe so un- 
 wearied a compiler as Dr Thomson, recently 
 appropriating to his friend Mr Phillips, the 
 discovery of a fact observed and recorded 
 years before by M. Dulong ; and treating as 
 an anomaly, what the French philosopher had 
 shewn to be none, but had referred with 
 equal sagacity and industry to general prin- 
 ciples. 
 
 After the labours of Bergmann and Ber- 
 thollet, chemistry seemed to leave little fur- 
 ther to be desired, relative to the mutual de- 
 composition of soluble salts. But the inso- 
 luble salts are likewise susceptible of ex- 
 changing their principles with a great num- 
 ber of the soluble salts. “ This class of 
 phenomena,” says M. Dulong, “ though 
 almost as numerous as that which embraces 
 the soluble salts, and capable of affording 
 new resources to analysis, has not yet been 
 examined in a general manner/’ 
 
 The action of the soluble carbonates on 
 the insoluble salts, is the only one which 
 had been at all studied. Thus carbonates of 
 potash and soda in solution, had been em- 
 ployed conveniently to decompose sulphate 
 of barytes. M. Dulong had an opportunity 
 in some particular researches, to observe a 
 considerably extensive number of facts relat- 
 ing to the mutual decomposition of the solu- 
 ble and insoluble salts, and endeavoured, he 
 says, to determine the general cause of these 
 phenomena, and the method of foreseeing 
 their results, without being obliged to retain 
 by an effort of memory, of which few per- 
 sons would be capable, all the direct obser- 
 vations which would be requisite to ascertain 
 them. 
 
 M. Dulong found by experiment, that all 
 the insoluble salts are decomposable by the 
 carbonate of potash or the carbonate of soda, 
 and in some instances with curious pheno- 
 mena. When sulphate of barytes, phosphate 
 of barvtes, or oxalate of lime, is boiled with 
 solution of bicarbonate, or carbonate of pot- 
 ash, a considerable part of the insoluble sul- 
 phate is constantly transformed into a car- 
 bonate of the same base ; but on reaching a 
 certain limit, the decomposition stopped, al- 
 though there remained sometimes a very 
 considerable quantity of the soluble carbo- 
 nate not decomposed. M. Dulong con- 
 vinced himself, that the different degrees of 
 concentration of the alkaline solution, pro- 
 duced but very slight variations in the results 
 of this decomposition. Fie took 10 grammes 
 of dry subcarbonate of potash, and 7.66, 
 being their equivalent proportion, of dry 
 subcarbonate of soda ; quantities containing 
 each 3.07 grammes of carbonic acid. They 
 were separately dissolved in 250 grammes of 
 water, and each solution was kept in ebulli- 
 tion for two hours, on 8 grammes of the 
 sulphate of barytes. On analyzing the two 
 residues, it was found that the potash experi- 
 ment yielded 2. 1 85 grammes, and the soda 
 only 1.833 ; or in the proportion of 6 to 5. 
 Is this difference to be ascribed to the diffe- 
 rence in the attractive forces of the two 
 alkalis ; to the more sparing solubility, or 
 greater attractive force of the sulphate of 
 potash ; or to both causes conjointly ? 
 
 Since the alkaline carbonates lose their de- 
 composing agency when a certain proportion 
 of the alkaline sulphate is formed, M. Du- 
 long tried to ascertain the limits by the fol- 
 lowing experiment: 7 grammes of sulphate of 
 potash, with 6 of subcarbonate, dissolved in 
 250 of water, were boiled with the sulphate 
 of barvtes for several hours, without the least 
 trace of decomposition being evinced. Tho 
 supernatant liquid, filtered, and boiled on 
 carbonate of barytes, produced a considerable 
 quantity of sulphate ; but ceased acting be- 
 fore this sulphate of potash was exhausted. 
 The same phenomena were obtained with 
 carbonate and sulphate of soda. “ Lastly, 
 the sulphate of potash and the sulphate of 
 soda alone, and perfectly neutral, re-actcd 
 likewise upon the carbonate of barytes, and 
 produced on one part sulphate of barytes, but 
 on the other the subcarbonate of potash or 
 soda which remained in solution, together 
 with the portion of the sulphate which resist- 
 ' ed the decomposition. 20 grammes of crys- 
 tallized sulphate of soda, and 10 grammes 
 of sulphate of potash, were separately dis- 
 solved in 260 of water. Each solution was 
 boiled for 2 hours on 20 grains of carbonate 
 of barytes. The sulphate of soda produced 
 10.17 gr. of sulphate of barytes, and the sul- 
 phate of potash 9.87.” Had 108 of sulphate 
 o 
 
ATT 
 
 ATT 
 
 of potash been employed, which is the true 
 equivalent of 200 sulphate of soda in crystals, 
 a somewhat larger product would have been 
 obtained than 9.87. This experiment, how- 
 ever, is most satisfactory with regard to the 
 amount ot decomposition. The mutual ac- 
 tion ot the insoluble carbonates, with the so- 
 luble salts, whose acids form, with the bases 
 ot these carbonates, insoluble salts, is equally 
 general with that of the soluble carbonates 
 °n the insoluble salts. The following is M. 
 Dulong’s table of results: 
 
 Carbonate of Barytes. 
 
 Carbo- 
 nate of 
 Stron- 
 tian. 
 
 .'Carbo- 
 nate of 
 Lime. 
 
 I Carbo- 
 nate of 
 Lead. 
 
 Sulphate of Potash 
 
 Id. 
 
 0 
 
 Id. 
 
 Soda 
 
 Id. 
 
 0 
 
 Id. 
 
 Lime 
 
 Id. 
 
 0 
 
 Id. 
 
 • Ammonia 
 
 Id. 
 
 Id. 
 
 Id. 
 
 • Magnesia 
 
 Id. 
 
 • • • 
 
 Id. 
 
 Phosphate of Soda 
 
 Id. 
 
 Id. 
 
 Id. 
 
 Ammonia 
 
 Id. 
 
 Id. 
 
 Id. 
 
 Sulphite of Potash 
 
 Id. 
 
 Id. 
 
 Id. 
 
 Phosphite of Potash 
 
 Id. 
 
 Id. 
 
 Id. 
 
 — Soda 
 
 Id. 
 
 Id. 
 
 Id. 
 
 Ammonia 
 
 Id. 
 
 Id. 
 
 Id. 
 
 Borate of Soda 
 
 Id. 
 
 • • • 
 
 Id. 
 
 Arseniate of Potash 
 
 Id. 
 
 Id. 
 
 Id. 
 
 Soda 
 
 Id. 
 
 Id. 
 
 Id. 
 
 Oxalate of Potash 
 
 Id. 
 
 Id. 
 
 Id. 
 
 Ammonia 
 
 Id. 
 
 Id. 
 
 Id. 
 
 Fluate of Soda 
 
 Id. 
 
 Id. 
 
 Id. 
 
 Chromate of Potash 
 
 Id. 
 
 Id. 
 
 Id. 
 
 All those salts which have ammonia for 
 their base, are completely decomposed by the 
 insoluble carbonates found in the same co- 
 lumn. The new insoluble salt replaces the 
 carbonate which is decomposed, and the car- 
 bonate of ammonia flies off. Hence, if a 
 sufficient quantity of insoluble carbonate be 
 present, the liquid will become pure water. 
 
 When the soluble salt has an insoluble 
 base, the decomposition does not meet with 
 any obstacle, but continues until the liquid 
 becomes mere water. Thus, solution of sul- 
 phate of magnesia, boiled with carbonate of 
 barytes, will be resolved into an insoluble 
 carbonate and sulphate, provided enough of 
 carbonate of barytes be present. Otherwise 
 a portion of the magnesian carbonate being 
 dissolved in its own sulphate, gives alkaline 
 properties to the solution. 
 
 If the base be metallic, it almost always 
 forms a salt witli excess of oxide, which being 
 insoluble, precipitates. 
 
 The general inferences of M. Dulong's 
 inquiries are the following : 1. That all the 
 insoluble salts are decomposed by the subcar- 
 bonates of potash or soda, but that a mutual 
 exchange of the principles of these salts can- 
 not in any case be completely made ; or in 
 
 other words, that the decomposition of the 
 subcarbonates is only partial. 2. That all 
 the soluble salts, of which the acid forms, 
 with the base of the insoluble carbonates, an 
 insoluble salt, are decomposed by these car- 
 bonates, until the decomposition has reached 
 a certain limit which it cannot pass. 
 
 W hen a soluble subcarbonate acts on an 
 insoluble salt, in proportion as the carbonic 
 acid is precipitated on the base of the inso- 
 luble salts, it is replaced in the solution by a 
 quantity of another acid, capable of complete- 
 ly neutralizing the alkali. Thus, during the 
 whole course of the decomposition, fresh quan- 
 tities of neutral salt replace the correspond- 
 ing quantities of an imperfectly saturated al- 
 kaline compound ; and if we view the excess 
 of alkal ine power in the undecomposed sub- 
 carbonate, or its unbalanced capacity of sa- 
 turation, as acting upon both acids, it is evi- 
 dent that in proportion as the decomposition 
 advances, the liquid approaches more anil 
 more to the neutral state. In the inverse 
 experiment, a contrary change supervenes. 
 Each portion of the acid of the soluble salt, 
 (sulphate of soda for example), which is pre- 
 cipitated on the base of the insoluble carbo- 
 nate, is replaced by a quantity of carbonic 
 acid, which forms with the corresponding 
 base, an alkaline subcarbonate ; and the more 
 of the first acid is precipitated upon the earthy 
 base, the more subcarbonate the liquid con- 
 tains, and the further does its state recede 
 from neutralization. This consideration 
 seems to lead directly to the following theory 
 of these decompositions. 
 
 It is known, says M. Dulong, that all the 
 salts, even those which possess the greatest 
 cohesion, yield to caustic potash or soda, a 
 more or less considerable portion of their 
 acid, according to circumstances. Now the 
 alkaline subcarbonates may be considered as 
 weak alkalis, which may take from all the 
 insoluble salts a small quantity of their 
 acids. This effect would soon be limited if 
 the alkali were pure, in consequence of the 
 resistance offered by the pure and soluble 
 base. Ilut the latter meeting in the liquid, 
 an acid with which it can form an insoluble 
 salt, unites with it, and thus re-establishes 
 the primitive conditions of the experiment. 
 The same effects are produced successively 
 on new portions of the bodies, till the degree 
 of saturation of the liquid is in equilibrium 
 with the cohesive force of the insoluble salt, 
 so that the feebler this resistance may be, 
 the more progress the decomposition will 
 make. And again, when an insoluble car- 
 bonate is in contact with a neutral soluble 
 salt, the base of the carbonate will tend to 
 take part of the acid of the neutral salts; and 
 if, from this union, an insoluble salt can re- 
 sult, the force of cohesion peculiar to tins 
 compound, will determine the formation. 
 The carbonic acid, released from the attrac- 
 
ATT 
 
 ATT 
 
 tion of the earthy base by the fixed acid, in- 
 stantly attaches itself to the surrounding 
 alkali, forming a subcarbonate which replaces 
 the decomposed neutral salt. The precipita- 
 tion of the fixed acid on the insoluble car- 
 bonate, and the absorption of carbonic acid 
 by the liquid, continues until the alkalinity 
 thereby developed, becomes so strong as to 
 resist the precipitation of the acid; thus 
 forming a counterpoise to the force by which 
 that precipitation was accomplished. All 
 action then ceases, so that the more cohesion 
 the insoluble salt possesses, the greater will 
 be the proportion of acid taken from the 
 soluble salt. 
 
 When the carbonate of potash can no 
 longer decompose the sulphate of barytes, 
 the carbonic acid which remains in the so- 
 lution, is to the sulphuric acid nearly in the 
 ratio of 3 to 1 ; and when the sulphate of 
 potash can no longer act upon the carbonate 
 of barytes, these two acids are nearly in the 
 ratio of 3 to 2 ; whence it follows, that the 
 first liquor is much more alkaline than the 
 second. 
 
 It is easy to account for this difference by 
 examining the conditions of the equilibrium 
 established in the two cases. When the 
 sulphate of potash no longer decomposes the 
 .carbonate of barytes, it is because the excess 
 of alkali, developed in the liquid, forms a 
 counterpoise to the power with which sul- 
 phate of barytes tends to be produced in 
 these circumstances. And when the sub- 
 carbonate of potash can no longer decompose 
 the sulphate of barytes, it is because there is 
 not such an excess of alkali in the liquid, as 
 is capable of overcoming the cohesion and 
 attraction between the elements of that salt. 
 Now' we know, that it requires a greater 
 force to overcome an existing attractive 
 pow'er, than to maintain the quiescent con- 
 dition. Therefore the subcarbonate of pot- 
 ash ought to cease to decompose the sulphate 
 of barytes, before the sulphuric and carbonic 
 acids are in the same relation in which they 
 are found, when the equilibrium is establish- 
 ed by the inverse experiment. Hence we 
 see, that a mixture of sulphate and subcar- 
 bonate of potash, in which the proportions 
 of their two acids shall be within the limits 
 pointed out, will have no action either on 
 the sulphate or carbonate of barytes. For 
 the other insoluble salts, there will be other 
 relations of quantity; but there is always a 
 certain interval, more or less considerable, 
 between their limits. The mutual action of 
 sulphate of soda and carbonate of barytes is 
 almost instantaneous. It is sufficient to pour 
 a boiling hot solution of the sulphate, on the 
 carbonate placed on a filter, in order that 
 more than three-fourths of the sulphuric 
 acid be precipitated, and replaced by a cor- 
 responding quantity of carbonic acid. 
 
 In the first part of the Philosophical Trans- 
 
 actions for 1 P'09, w r e have tables of elective 
 attractions by l)r Thomas Young, a philo- 
 sopher of the very first rank, wffiom the late 
 ingenious Dr Wells pronounced the most 
 learned man in England. These have been 
 unaccountably overlooked by our different 
 systematic writers, though they are, both in 
 accuracy and ingenuity, far superior to the 
 tables which, with unvarying routine of 
 typography, are copied into their compila- 
 tions. I conceive it will be doing an essential 
 service to chemical students, to lay before 
 them the tables of Dr Young, accompanied 
 with his admirable remarks on the sequences 
 of double decompositions. 
 
 Attempts have been made, by several che- 
 mists, to obtain a series of numbers, capable 
 of representing the mutual attractive forcos 
 of the component parts of different salts ; but 
 these attempts have hitherto been confined 
 within narrow limits, and have indeed been 
 so hastily abandoned, that some very impor- 
 tant consequences, which necessarily follow 
 from the general principle of a numerical 
 representation, seem to have been entire- 
 ly overlooked. • It appears that nearly all 
 the phenomena of the mutual actions of a 
 hundred different salts may be correctly re- 
 presented by a hundred numbers, while, in 
 the usual manner of relating every case as a 
 different experiment, above two thousand 
 separate articles w r ould be required. 
 
 Having been engaged in the collection of 
 a few of the principal facts relating to che- 
 mistry and pharmacy, Dr Young was in- 
 duced to attempt the investigation of a scries 
 of these numbers ; and he has succeeded in 
 obtaining such as appear to agree sufficient- 
 ly well with all the cases of double decom- 
 positions which are fully established, the ex- 
 ceptions not exceeding twenty, out of about 
 twelve hundred cases enumerated by Four- 
 eroy. The same numbers agree in general 
 with the order of simple elective attractions, 
 as usually laid down by chemical authors ; 
 but it was of so much less importance to ac- 
 commodate them to these, that he has not 
 been very solicitous to avoid a few' inconsis- 
 tencies in this respect, especially as many of 
 the bases of the calculation remain uncertain, 
 and as the common tables of simple elective 
 attractions are certainly imperfect, if they are 
 considered as indicating the order of the in- 
 dependent attractive forces of the substances 
 concerned. Although it cannot be expected 
 that these numbers should be accurate mea- 
 sures of the forces which they represent, yet 
 they may be supposed to be tolerable approxi- 
 mations to such measures; at least, if any 
 two of them are nearly in the true propor- 
 tion, it is probable that the rest cannot de- 
 viate very far from it : thus, if the attractive 
 force of the phosphoric acid for potash is 
 about eight-tenths of that of the sulphuric 
 
 acid for barytes, that of the phosphoric acid 
 47 
 
ATT 
 
 ATT 
 
 for barytes must be about nine-tenths as 
 great ; but they are calculated only to agree 
 with a certain number of phenomena, & and 
 will probably require many alterations, as 
 well as additions, when all other similar 
 phenomena shall have been accurately in- 
 vestigated. 
 
 Ihere must be a sequence,” says Dr 
 Young, “ in the simple elective attractions. 
 I 1 or example, there must be an error in the 
 common tables of elective attractions, in which 
 magnesia stands above ammonia under the 
 sulphuric acid, and below it under the phos- 
 phoric ; and the phosphoric acid stands above 
 the sulphuric under magnesia, and below it 
 under ammonia; since such an arrangement 
 implies that the order of the attractive forces is 
 this: phosphate of magnesia, sulphate of mag- 
 nesia, sulphate of ammonia, phosphate of am- 
 monia, and again phosphate of magnesia ; 
 which forms a circle, and not a sequence. 
 We must therefore either place magnesia 
 above ammonia under the phosphoric acid, 
 or the phosphoric acid below the sulphuric 
 under magnesia ; or we must abandon the 
 principle of a numerical representation in 
 this particular case. 
 
 “In the second place, there must be an 
 agreement between the simple and double 
 elective attractions. Thus, if the fluoric 
 acid stands above the nitric under barita, and 
 below it under lime, the fluate of barita can- 
 not decompose the nitrate of lime, since the 
 previous attractions of these two salts are 
 respectively greater than the divellent attrac- 
 tions of the nitrate of barita and the fluate 
 of lime. Probably, therefore, we ought to 
 place the fluoric acid below the nitric under 
 barita ; and we may suppose, that when 
 the fluoric acid has appeared to form a 
 precipitate with the nitrate of barita, there 
 has been some fallacy in the experiment. 
 
 “ The third proposition is somewhat less 
 obvious, but perhaps of greater utility : there 
 must be a continued sequence in the order 
 of double elective attractions ; that is, be- 
 tween any two acids we may place the dif- 
 ferent bases in such an order, that any two 
 salts, resulting from their union, shall al- 
 ways decompose each other, unless each acid 
 be united to the base nearest to it ; for ex- 
 ample, sulphuric acid, barita, potash, soda, 
 ammonia, strontia, magnesia, glycina, alu- 
 mina, zirconia, lime, phosphoric acid. The 
 sulphate of potash decomposes the phosphate 
 of barita, because the difference of the attrac- 
 tions of barita for the sulphuric and phos- 
 phoric acids is greater than the difference of 
 the similar attractions of potash ; and in the 
 
 same manner, the difference of the attractions 
 of potash is greater than that of the attrac- 
 tions of soda ; consequently the difference 
 of the attractions of barita must be much 
 greater than that of the attractions of soda, 
 and the sulphate of soda must decompose 
 the phosphate of barita ; and in the same 
 manner it may be shewn, that each base 
 must preserve its relations of priority or pos- 
 teriority to every other in the series. It is 
 also obvious, that, for similar reasons, the 
 acids may he arranged in a continued se- 
 quence between the different bases ; and 
 when all the decompositions of a certain 
 number of salts have been investigated, we 
 may form two corresponding tables, one of 
 the sequences of the bases with the acids, 
 and another of those of the acids with the 
 different bases ; and if either or both of the 
 tables are imperfect, their deficiencies may 
 often be supplied, and their errors corrected, 
 by a repeated comparison with each other.” 
 In the table of simple elective attractions, 
 he has retained the usual order of the dif- 
 ferent substances ; inserting again in paren- 
 theses such of them as require to be transpos- 
 ed, in order to avoid inconsequences in the 
 simple attractions : He has attached to each 
 combination marked with an asterisk the 
 number deduced from the double decompo- 
 sitions, as expressive of its attractive force ; 
 and where the number is inconsistent with 
 the corrected order of the simple elective at- 
 tractions, he has enclosed it in a parenthesis. 
 Such an apparent inconsistency may perhaps 
 in some cases be unavoidable, as it is possible 
 that the different proportions of the masses 
 concerned in the operations of simple and 
 compound decomposition, may sometimes 
 cause a real difference in the comparative 
 magnitude of the attractive forces. Thosenum- 
 bers to which no asterisk is affixed, are merely 
 inserted by interpolation, and they can only be 
 so far employed for determining the mutual 
 actions of the salts to which they belong, as 
 the results which they indicate would follow 
 from the comparison of any other numbers, 
 intermediate to the nearest of those which 
 are more correctly determined. lie was not 
 able to obtain a sufficient number of facts 
 relating to the metallic salts, to enable him 
 to comprehend many of them in the tables. 
 
 He thought it necessary to make some 
 alterations in the orthography generally adopt- 
 ed by chemists, not from a want of defer- 
 ence to their individual authority, but be- 
 cause it appeared to him that there are certain 
 rules of etymology, which no modern author 
 has a right to set aside.* 
 
ATT 
 
 ATT 
 
 Sj © 
 
 g 3 
 3 
 
 B g 
 
 o 
 
 3 
 
 3 
 
 CL 
 
 v> 
 
 P 
 
 3 
 
 o 
 
 3 
 
 P* 
 
 7> 
 
 OJ t> 
 
 o* 
 
 ^3 I 
 
 3* 2 cl 
 
 cr p- w 
 
 P rr 
 S 3 o 
 
 P Z* = 
 
 3 3 3 
 
 ffi 5 
 3 » ctq 
 
 3 
 CD 
 
 7* 
 
 S' 
 
 o 
 
 B* j 
 
 S. 3 
 
 p p 
 3 OQ 
 CL 3 
 w> a 
 
 71 
 
 cr 
 
 2 . 
 
 o 
 
 3 
 
 p 
 
 S 
 
 3* 
 
 CD 
 
 3 
 
 n 
 
 o 
 
 p 
 
 1 73 CL 
 <-► • 
 
 P 
 
 3 
 
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 TABLES OF ELECTIVE ATTRACTIONS, bv Db Young. 
 
TABLE II. by Dr Young. 
 
 NITRIC 
 
 ACID. 
 
 
 NITRIC 
 
 AND MURIATIC ACIDS* 
 
 Barita 
 
 Potash 
 
 Barita 
 
 Potash 
 
 Barita (10) 
 
 Potash 
 
 Potash 
 
 Soda 
 
 Potash 
 
 Soda 
 
 Potash 
 
 Soda 
 
 Soda 
 
 Ammonia 
 
 Soda 
 
 Ammonia 
 
 Soda 
 
 Barita ( 10) 
 
 Strontia 
 
 Magnesia 
 
 Ammonia 
 
 Magnesia 
 
 Ammonia 
 
 Ammonia (7,1 1 ) 
 
 Lime 
 
 Glycina 
 
 Magnesia 
 
 Glycina 
 
 Magnesia 
 
 Magnesia (7) 
 
 Magnesia 
 
 (7) Alumina 
 
 Glycina 
 
 Alumina 
 
 Glycina 
 
 Strontia 
 
 Ammonia 
 
 (7)Zirconia (8) Alumina 
 
 Zirconia 
 
 Alumina 
 
 Lime 
 
 Glycina 
 
 Barita 
 
 Zirconia 
 
 Barita 
 
 Zirconia 
 
 Glycina 
 
 Alumina 
 
 Strontia 
 
 Strontia (9) 
 
 Strontia 
 
 Strontia 
 
 Alumina 
 
 Zirconia 
 
 Lime 
 
 Lime 
 
 Lime 
 
 Lime 
 
 Zirconia 
 
 Muriatic 
 
 Phosphoric 
 
 Fluoric 
 
 Sulphurous 
 
 Boracic 
 
 Carbonic. 
 
 (7.) A triple salt is formed. (8.) Fourcroy says, that the muriate of zirconia decom- 
 poses the phosphates of barita and strontia. (9.) According to Fourcroy’s account, the flu- 
 ate of strontia decomposes the muriates of ammonia, and of all the bases below it; but he 
 says in another part of the same volume, that the fluate of strontia is an unknown salt. 
 (10.) According to Fourcroy’s account of these combinations, barita should stand immedi- 
 ately below ammonia in both of these columns. (11.) With heat, the carbonate of lime 
 decomposes the muriate of ammonia. 
 
 PHOSPHORIC ACID. 
 
 Barita 
 
 Lime 
 
 Barita 
 
 Potash 
 
 Barita 
 
 Lime 
 
 Barita 
 
 Lime 
 
 Soda 
 
 Lime 
 
 Potash 
 
 Potash 
 
 Potash 
 
 Barita 
 
 Potash 
 
 Soda 
 
 Soda 
 
 Soda 
 
 Lime (13) 
 
 Soda 
 
 Strontia 
 
 Strontia 
 
 Strontia 
 
 Strontia 
 
 Strontia 
 
 Magnesia 
 
 Magnesia 
 
 Ammonia (12) Ammonia 
 
 Magnesia 
 
 Ammonia 
 
 Ammonia 
 
 Magnesia 
 
 Magnesia 
 
 Glycina? 
 
 Glycina 
 
 Glycina 
 
 Glycina 
 
 Glycina 
 
 Alumina 
 
 Alumina 
 
 Alumina 
 
 Alumina 
 
 Alumina 
 
 Zirconia 
 
 Zirconia 
 
 Zirconia 
 
 Zirconia 
 
 Zirconia 
 
 
 Fluoric 
 
 Sulphurous 
 
 Boracic 
 
 Carbonic 
 
 ( Phosphorous) 
 
 ( 1 2.) According to Fourcroy, the phosphate 
 
 of ammonia decomposes the borate < 
 
 pesia. (13.) Fourcroy 
 
 ' says, that the carbonate of lime decomposes the phosphates 
 
 ash and of soda. 
 
 
 
 
 
 
 FLUORIC 
 
 ACID. 
 
 
 
 Lime 
 
 Lime 
 
 Potash 
 
 
 
 Potash 
 
 Barita 
 
 Soda 
 
 
 
 Soda 
 
 Strontia 
 
 Lime 
 
 
 
 Magnesia 
 
 Potash 
 
 Barita 
 
 • 
 
 
 Ammonia 
 
 Soda 
 
 Strontia 
 
 
 
 Glycina 
 
 Ammonia 
 
 Ammonia 
 
 (14) 
 
 
 Alumina 
 
 Magnesia 
 
 Magnesia 
 
 
 
 Zirconia 
 
 Glycina 
 
 Glycina 
 
 
 
 Strontia 
 
 A lumina 
 
 Alumina 
 
 
 
 Barita 
 
 Zirconia 
 
 Zirconia 
 
 
 
 Sulphurous 
 
 Boracic 
 
 Carbonic 
 
 
 (14.) According to Fourcroy, the carbonate of ammonia decomposes the fluate* of btriU 
 and strontia. 
 
ATT 
 
 ATT 
 
 Dr Young’s SECOND TABLE— (concluded). 
 
 SULPHUROUS ACID. BORACIC ACID. 
 
 Barita 
 
 Potash 
 
 Lime 
 
 Zirconia 
 
 Potash 
 
 Strontia 
 
 Soda 
 
 Strontia 
 
 Alumina 
 
 Soda 
 
 Potash 
 
 Barita (15.) 
 
 Barita 
 
 Glycina 
 
 Lime 
 
 Soda 
 
 Strontia 
 
 Zirconia 
 
 Ammonia 
 
 Barita 
 
 Ammonia 
 
 Ammonia 
 
 Alumina 
 
 Magnesia 
 
 Strontia 
 
 Magnesia 
 
 Lime 
 
 Glycina 
 
 Strontia 
 
 Magnesia 
 
 Lime 
 
 Magnesia 
 
 Magnesia 
 
 Soda 
 
 Ammonia 
 
 Glycina 
 
 Glycina 
 
 Ammonia 
 
 Potash 
 
 Glycina 
 
 Alumina 
 
 Alumina 
 
 Soda 
 
 Barita 
 
 Alumina 
 
 Zircon ia 
 
 Zirconia 
 
 Potash 
 
 Lime 
 
 Zirconia 
 
 Boracic 
 
 Carbonic 
 
 (Nitrous) 
 
 (Phosphorus ?) 
 
 Carbonic 
 
 f\ 5 .) pourcroy says, that the sulfite of barita decomposes the carbonate of ammonia. 
 
 III. A Table of the Sequences qf the Acids with different Bases, by Dr Young. 
 
 BARITA. 
 
 
 STRONTIA. 
 
 
 LIME. 
 
 
 Potash 
 
 MAG- 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 Soda 
 
 NESIA 
 
 Sulphuric 
 
 S 
 
 c 
 
 s | 
 
 S 
 
 C 
 
 s 
 
 P 
 
 s 
 
 C 
 
 P 
 
 P 
 
 P 
 
 Magn. = Amm. 
 
 "S 
 
 B 
 
 Nitric 
 
 N 
 
 S 
 
 P N 
 
 SS 
 
 p 
 
 s 
 
 p 
 
 P 
 
 F 
 
 F 
 
 F 
 
 Glycina 
 
 N 
 
 c 
 
 Muriatic 
 
 M 
 
 P SS M 
 
 F 
 
 SS 
 
 SS 
 
 SS 
 
 F 
 
 B 
 
 B 
 
 SS 
 
 Alumina 
 
 
 Phosphoric SS 
 
 SS N 
 
 SS 
 
 P 
 
 F 
 
 F 
 
 F 
 
 B 
 
 SS 
 
 C 
 
 S 
 
 Zirconia 
 
 M 
 
 P 
 
 Sulphurous P 
 
 N 
 
 M 
 
 c 
 
 B 
 
 B 
 
 B 
 
 B 
 
 SS 
 
 S 
 
 SS 
 
 B 
 
 Each with every 
 
 p 
 
 F 
 
 Fluoric 
 
 C 
 
 M 
 
 F 
 
 B 
 
 S 
 
 C 
 
 C 
 
 N 
 
 s 
 
 c 
 
 S 
 
 N 
 
 subsequent base 
 
 
 
 Boracic 
 
 B 
 
 F 
 
 B 1 
 
 F 
 
 M 
 
 N 
 
 N 
 
 M 
 
 M 
 
 N 
 
 N 
 
 M 
 
 in this order, < 
 
 F 
 
 SS 
 
 Carbonic 
 
 F 
 
 B 
 
 C 
 
 P 
 
 N 
 
 M 
 
 M 
 
 C 
 
 N 
 
 M 
 
 M 
 
 C 
 
 * 
 
 SS 
 
 s 
 
 Strontia 
 
 I, AT 
 
 PT 
 
 MG LM 
 
 PT 
 
 MG 
 
 AM 
 
 CI. 
 
 PT 
 
 MG 
 
 AM 
 
 GL 
 
 
 
 
 
 
 sn 
 
 AM 
 
 
 SD 
 
 
 
 A I 
 
 3I> 
 
 
 
 A L 
 
 
 B 
 
 N 
 
 
 
 
 CL 
 
 
 
 
 
 ZV 
 
 
 
 
 ZR 
 
 
 C 
 
 M 
 
 
 
 
 A.L 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 ZH 
 
 
 
 
 
 
 
 
 
 
 
 
 AM 
 
 The comparative use of this Table may be understood from an example: If we suppose 
 that the nitrate of barita decomposes the borate of ammonia, we must place the boracic acid 
 above the nitric, between barita and ammonia in this Table, and consequently barita below 
 ammonia, between the fluoric and boracic in the former : hence the boracic and fluoric acids 
 must also be transposed between barita and strontia, arid between barita and potash ; or if 
 we place the fluoric still higher than the boracic. in the first instance, we must place barita 
 below ammonia between the nitric and fluoric acids, where indeed it is not impossible that it 
 ought to stand. 
 
ATT 
 
 ATT 
 
 W. A Numerical Table of Electice Attractions , by Dr Young. 
 
 B A RITA. 
 
 Strontia, 
 
 » 
 
 Fotash. 
 
 Soda. Lime. 
 
 Sulphuric acid 
 
 1000* Sulphuric acid 
 
 903* 
 
 Sulphuric acid 894* 885* Oxalic acid 960 
 
 Oxalic 
 
 950 Phosphoric 
 
 827* 
 
 Nitric 
 
 812* 804* Sulphuric 
 
 868* 
 
 Succinic 
 
 930 Oxalic 
 
 825 
 
 Muriatic 
 
 804* 797* Tartaric 
 
 867 
 
 Fluoric 
 
 Tartaric 
 
 757 
 
 Phosphoric 
 
 801* 795* Succinic 
 
 866 
 
 Phosphoric 
 
 906* Fluoric 
 
 
 Suberic ? 
 
 745 740 Phosphoric 865* 
 
 Mucic 
 
 900 Nitric 
 
 754* 
 
 Fluoric 
 
 671* 666* Mucic 
 
 860 
 
 Nitric 
 
 849* Muriatic 
 
 748* 
 
 Oxalic 
 
 650 645 Nitric 
 
 741* 
 
 Muriatic 
 
 840* (Succinic) 
 
 740 
 
 Tartaric 
 
 616 611 Muriatic 
 
 736* 
 
 Suberic 
 
 800 (Fluoric) 
 
 703 
 
 Arsenic 
 
 614 609 Suberic 
 
 735 
 
 Citric 
 
 Succinic 
 
 
 Succinic 
 
 612 607 Fluoric 
 
 754* 
 
 Tartaric 
 
 760 Citric? 
 
 618 
 
 Citric 
 
 610 605 Arsenic 
 
 7S3J 
 
 Arsenic 
 
 733^ Lactic 
 
 603 
 
 Lactic 
 
 609 604 Lactic 
 
 732 
 
 (Citric) 
 
 730 Sulphurous 
 
 527* 
 
 Benzoic 
 
 608 603 Citric 
 
 751 
 
 Lactic 
 
 729 Acetic 
 
 
 Sulphurous 
 
 488* 484* Malic 
 
 700 
 
 ( Fluoric) 
 
 706* Arsenic (733^) 
 
 Acetic 
 
 486 482 Benzoic 
 
 590 
 
 Benzoic 
 
 5 97 Boracic 
 
 513* 
 
 Mucic 
 
 484 480 Acetic 
 
 
 Acetic 
 
 594 (Acetic) 
 
 480 
 
 Boracic 
 
 482* 479* Boracic 
 
 537* 
 
 Boracic 
 
 (515)* Nitrous? 
 
 430 
 
 Nitrous 
 
 440 437 Sulphurous 51 6* 
 
 Sulphurous 
 
 592* Carbonic 
 
 419* 
 
 Carbonic 
 
 306* 304* (Acetic) 
 
 470 
 
 Nitrous 
 
 450 
 
 
 Prussic 
 
 300 298 Nitrous 
 
 425 
 
 Carbonic 
 
 420* 
 
 
 
 Carbonic 
 
 423* 
 
 Prussic 
 
 400 
 
 
 
 Prussic 
 
 290 
 
 Magnesia. Ammonia. Glycina ? Alumina. Zirconia? 
 
 Oxalic acid 
 
 820 Sulphuric acid 
 
 808* 
 
 Sulphuric acid 
 
 718* 
 
 709* 
 
 700* 
 
 Phosphoric 
 
 Nitric 
 
 751* 
 
 Nitric 
 
 642* 
 
 634* 
 
 626* 
 
 Sulphuric 
 
 810* Muriatic 
 
 729* 
 
 Muriatic 
 
 639* 
 
 652* 
 
 625* 
 
 ( Phosphoric) 
 
 736* Phosphoric 
 
 728* 
 
 Oxalic 
 
 600 
 
 594 
 
 588 
 
 Fluoric 
 
 Suberic ? 
 
 720 
 
 Arsenic 
 
 580 
 
 575 
 
 570 
 
 Arsenic 
 
 733 Fluoric 
 
 613* 
 
 Suberic ? 
 
 535 
 
 530 
 
 525 
 
 Mucic 
 
 732^ Oxalic 
 
 611 
 
 Fluoric 
 
 554* 
 
 529* 
 
 524* 
 
 Succinic 
 
 75 Tartaric 
 
 609 
 
 Tartaric 
 
 520 
 
 515 
 
 510 
 
 Nitric 
 
 732* Arsenic 
 
 607 
 
 Succinic 
 
 510 
 
 505 
 
 500 
 
 Muriatic 
 
 728* Succinic 
 
 605 
 
 Mucic 
 
 425 
 
 420 
 
 415 
 
 Suberic? 
 
 700 Citric 
 
 603 
 
 Citric 
 
 415 
 
 410 
 
 405 
 
 ( Fluoric) 
 
 620* Lactic 
 
 601 
 
 Phosphoric 
 
 (648)* 
 
 (642)* 
 
 (636)* 
 
 Tartaric 
 
 618 Benzoic 
 
 599 
 
 Lactic 
 
 410 
 
 405 
 
 400 
 
 Citric 
 
 615 Sulphurous 
 
 433* 
 
 Benzoic 
 
 400 
 
 395 
 
 390 
 
 Malic? 
 
 600 ? Acetic 
 
 432 
 
 Acetic 
 
 395 
 
 391 
 
 387 
 
 Lactic 
 
 575 Mucic 
 
 431 
 
 Boracic 
 
 388* 
 
 385* 
 
 382* 
 
 Benzoic 
 
 560 Boracic 
 
 430* 
 
 Sulphurous 
 
 355* 
 
 351* 
 
 347* 
 
 Acetic 
 
 Nitrous 
 
 400 
 
 Nitrous 
 
 340 
 
 338 
 
 332 
 
 Boracic 
 
 459* Carbonic 
 
 339* 
 
 Carbonic 
 
 325* 
 
 323* 
 
 321* 
 
 Sulphurous 
 
 (Acetic) 
 
 Nitrous 
 
 Carbonic 
 
 Prussic 
 
 439* Prussic 
 
 430 
 
 410 
 
 366* 
 
 280 
 
 270 
 
 Prussic 
 
 260 
 
 258 
 
 256 
 
 Acids . 
 
 Sulphuric. Nitric. Muriatic. Phosphoric. 
 
 Barita 
 
 1000* 
 
 Barita 
 
 849* 
 
 Barita 
 
 840* 
 
 Barita 
 
 906* 
 
 Strontia 
 
 905* 
 
 Potash 
 
 8 1 2* 
 
 Potash 
 
 804* 
 
 Strontia 
 
 827* 
 
 Potash 
 
 894* 
 
 Soda 
 
 804* 
 
 Soda 
 
 797* 
 
 Lime 
 
 (865)* 
 
 Soda 
 
 885* 
 
 Strontia 
 
 754* 
 
 Strontia 
 
 748* 
 
 Potash 
 
 801* 
 
 Lime 
 
 868* 
 
 Lime 
 
 741* 
 
 Lime 
 
 756* 
 
 Soda 
 
 795* 
 
 Magnesia 
 
 810* 
 
 Magnesia 
 
 732* 
 
 Ammonia 
 
 729* 
 
 Ammonia (728)* 
 
 Ammonia 
 
 808* 
 
 Ammonia 
 
 751* 
 
 Magnesia 
 
 728* 
 
 Magnesia 
 
 736* 
 
 Glycina 
 
 718* 
 
 Glycina 
 
 642* 
 
 Glycina 
 
 639* 
 
 Glycina 
 
 648* 
 
 Itria 
 
 712 
 
 Alumina 
 
 634* 
 
 Alumina 
 
 632* 
 
 Alumina 
 
 642* 
 
 Alumina 
 
 Zirconia 
 
 709* 
 
 700* 
 
 Zirconia 
 
 626* 
 
 Zirconia 
 
 625 * 
 
 Zirconia 
 
 63 6* 
 
 4-M 
 
ATT 
 
 ATT 
 
 Fluoric. 
 
 Oxalic. Tartaric. 
 
 Arsenic. 
 
 TUNC6TIC. 
 
 Lime 
 
 734* 
 
 Lime 960 
 
 867 
 
 Lime 
 
 733f 
 
 Lime 
 
 Darita 
 
 706* 
 
 Barita 930 
 
 760 
 
 Barita 
 
 733£ 
 
 Barita 
 
 Strontia 
 
 703* 
 
 Strontia 825 
 
 757 
 
 Strontia 
 
 733i 
 
 Strontia 
 
 Magnesia (620)* 
 
 Magnesia 820 
 
 618 
 
 Magnesia 
 
 733 
 
 Magnesia 
 
 Potash 
 
 671* 
 
 Potash 650 
 
 616 
 
 Potash 
 
 614 
 
 Potash 
 
 Soda 
 
 666* 
 
 Soda 645 
 
 61.1 
 
 Soda 
 
 609 
 
 Soda 
 
 Ammonia 
 
 613* 
 
 Ammonia 611 
 
 609 
 
 Ammonia 
 
 607 
 
 Ammonia 
 
 Glycina 
 
 534* 
 
 Glycina ? 600 
 
 520 
 
 Glycina 
 
 580 
 
 Glycina 
 
 Alumina 
 
 5 29* 
 
 Alumina 594 
 
 515 
 
 Alumina 
 
 575 
 
 Alumina 
 
 Zirconia 
 
 524* 
 
 Zirconia ? 588 
 
 510 
 
 Zirconia 
 
 570 
 
 Zirconia 
 
 Succinic. 
 
 Suberic. 
 
 
 Camphoric. 
 
 Citric. 
 
 Barita 
 
 93 0 
 
 Barita 800 
 
 
 Lime 
 
 
 Lime 731 
 
 Lime 
 
 866 
 
 Potash 745 
 
 
 Potash 
 
 
 Barita 750 
 
 Strontia ? 
 
 740 
 
 Soda 740 
 
 
 Soda 
 
 
 Strontia 618 
 
 (Magnesia) 75 2£ 
 
 Lime 735 
 
 
 Barita 
 
 
 Magnesia 6 1 5 
 
 Potash 
 
 612 
 
 Ammonia 720 
 
 
 Ammonia 
 
 
 Potash 6 1 0 
 
 Soda 
 
 607 
 
 Magnesia 700 
 
 
 Glycina ? 
 
 
 Soda 605 
 
 Ammonia 
 
 605 
 
 Glycina? 535? 
 
 
 Alumina 
 
 
 Ammonia 603 
 
 Magnesia 
 
 
 Alumina 530 
 
 
 Zirconia ? 
 
 
 Glycina? 415? 
 
 Glycina ? 
 
 510 
 
 Zirconia? 525? 
 
 
 Magnesia 
 
 
 Alumina 410 
 
 Alumina 
 
 505 
 
 
 
 
 
 Zirconia 405 
 
 Zirconia ? 
 
 500 
 
 
 
 
 
 
 Lactic. 
 
 Benzoic. 
 
 
 Sulphurous. 
 
 Acetic. 
 
 Barita 
 
 729 
 
 White oxide of 
 
 
 Barita 
 
 592* 
 
 Barita 594 
 
 Potash 
 
 609 
 
 arsenic 
 
 
 Lime 
 
 516* 
 
 Potash 486 
 
 Soda 
 
 604 
 
 Potash 608 
 
 
 Potash 
 
 488* 
 
 Soda 482 
 
 Strontia 
 
 603 
 
 Soda 603 
 
 
 Soda 
 
 484* 
 
 Strontia 480 
 
 Lime 
 
 (732) 
 
 Ammonia 699 
 
 
 Strontia (527)* 
 
 Lime 470 
 
 Ammonia 
 
 601 
 
 Barita 597 
 
 
 Magnesia 
 
 439* 
 
 Ammonia 432 
 
 Magnesia 
 
 575 
 
 Lime 590 
 
 
 Ammonia 
 
 433* 
 
 Magnesia 430 
 
 Metallic oxides 
 
 Magnesia 560 
 
 
 Glycina 
 
 355* 
 
 Metallic oxides 
 
 Glycina 
 
 410 
 
 Glycina ? 400 ? 
 
 
 Alumina 
 
 351* 
 
 Glycina 395 
 
 Alumina 
 
 405 
 
 Alumina 395 
 
 
 Zirconia 
 
 547* 
 
 Alumina 591 
 
 Zirconia 
 
 400 
 
 Zirconia? 390? 
 
 
 
 
 Zirconia 587 
 
 Mucic ? 
 
 Boracic. 
 
 
 Nitrous ? 
 
 Phosphorous 
 
 Barita 
 
 900 
 
 Lime 537* 
 
 
 Barita 
 
 450 
 
 Lime 
 
 Lime 
 
 860 
 
 Barita 515* 
 
 
 Potash 
 
 440 
 
 Barita 
 
 Potash 
 
 484 
 
 Strontia 513* 
 
 
 Soda 
 
 437 
 
 Strontia 
 
 Soda 
 
 480 
 
 Magnesia (459)* 
 
 
 Strontia 
 
 430 
 
 Potash 
 
 Ammonia 
 
 431 
 
 Potash 482* 
 
 
 Lime 
 
 425 
 
 Soda 
 
 Glycina 
 
 425 
 
 Soda 479* 
 
 
 Magnesia 
 
 410 
 
 Magnesia ? 
 
 Alumina 
 
 420 
 
 Ammonia 430* 
 
 
 Ammonia 
 
 400 
 
 Ammonia 
 
 Zirconia 
 
 415 
 
 Glycina 388* 
 
 
 Glycina 
 
 340 
 
 Glycina 
 
 
 
 Alumina 385* 
 
 
 Alumina 
 
 336 
 
 Alumina 
 
 
 
 Zirconia 382* 
 
 
 Zirconia 
 
 332 
 
 Zirconia 
 
 
 * 
 
 Carbonic. 
 
 Prussic. 
 
 
 
 
 Barita 
 
 420* 
 
 Barita 
 
 400 
 
 
 
 
 Strontia 
 
 419* 
 
 Strontia 
 
 
 
 
 
 Lime 
 
 (423)* 
 
 Potash 
 
 300 
 
 
 
 
 Potash ? 
 
 506* 
 
 Soda 
 
 298 
 
 
 
 
 Soda 
 
 304* 
 
 Lime 
 
 290 
 
 
 
 
 Magnesia 
 
 (366)* 
 
 Magnesia 
 
 280 
 
 
 
 
 Ammonia 
 
 , 839* 
 
 Ammonia 
 
 270 
 
 
 
 
 Glycina 
 
 325* 
 
 Glycina ? 
 
 260 
 
 
 
 
 Alumina 
 
 323* 
 
 Alumina ? 
 
 258 
 
 
 
 
 Zirconia 
 
 321* 
 
 Zirconia ? 
 
 256 
 
 
ATI' 
 
 ATT 
 
 TABLES 
 
 or 
 
 SIMPLE ELECTIVE ATTRACTIONS, 
 
 FROM BERGMANN. 
 
 I — WATER AND COMBUSTIBLE SUBSTANCES. 
 
 IN THE HUMID WAY. 
 
 Water. 
 
 Sulphur. 
 
 Saline 
 
 SlILPHURETS. 
 
 Alcohol. 
 
 Ether. 
 
 Potash 
 
 Oxygen 
 
 Oxygen 
 
 Water 
 
 Alcohol 
 
 Soda 
 
 Molybdic oxide 
 
 Oxide of gold 
 
 Ether 
 
 Volatile oils 
 
 Ammonia 
 
 and acid 
 
 silver 
 
 Volatile oils 
 
 Water 
 
 Deliquescent salts 
 
 Oxide of lead 
 
 mercury 
 
 Ammonia 
 
 Sulphur 
 
 Alcohol 
 
 tin 
 
 arsenic 
 
 Fixed alkali 
 
 
 Carbonate of am- 
 
 silver 
 
 antimony 
 
 Alkaline sulphu- 
 
 
 monia 
 
 mercury 
 
 bismuth 
 
 rets 
 
 
 Ether 
 
 arsenic 
 
 copper 
 
 Sulphur 
 
 
 Sulphuric acid 
 
 antimony 
 
 tin 
 
 Muriates. 
 
 
 Non- deliquescent 
 
 iron 
 
 lead 
 
 Phosphoric acid 
 
 
 .salts 
 
 Potash 
 
 Soda 
 
 nickel 
 
 cobalt 
 
 
 
 
 
 
 
 Barytes 
 
 Strontian 
 
 Lime 
 
 manganese 
 
 iron 
 
 Other metallic 
 
 Fat Oils. 
 
 Volatile Oils. 
 
 
 Barytes ? 
 
 Ether 
 
 
 Magnesia 
 
 oxides 
 
 Strontian ? 
 
 A lcohol 
 
 
 Phosphorus 
 
 Carbon 
 
 Lime 
 
 Fat oils 
 
 
 Fat oils 
 
 Water 
 
 Metallic oxides 
 
 Fixed alkalis 
 
 
 Ammonia 
 
 Alcohol 
 
 Ether 
 
 Sulphur 
 
 
 Ether 
 
 Ether 
 
 Volatile oils 
 
 Phosphorus 
 
 
 Hydrogen? 
 
 
 Fixed alkalis 
 
 
 t 
 
 
 
 Ammonia 
 
 Sulphur 
 
 
 
 IN THE 1 
 
 
 Phosphorus 
 
 
 
 DRY WAY. 
 
 Sulphuretted 
 
 Hydrogen. 
 
 
 
 
 
 
 Oxygen 
 
 Potash 
 
 Manganese 
 
 
 
 
 Iron 1 
 
 
 Barvtes 
 
 
 Soda 
 
 Copper 
 
 
 Potash 
 
 
 Iron 
 
 Im 
 
 
 Soda 
 
 
 Copper 
 
 Lead 
 
 
 Lime 
 
 
 Tin 
 
 Silver 
 
 
 Ammonia 
 
 
 Lead 
 
 Gold 
 
 
 Magnesia 
 
 
 Silver 
 
 Antimony 
 
 
 Zircon 
 
 
 Cobalt 
 
 Cobal t 
 
 
 
 Nickel 
 
 Nickel 
 
 
 
 
 Bismuth 
 
 Bismuth 
 
 
 
 
 Antimony 
 
 Mercury 
 
 
 
 
 Mercury 
 
 Arsenic 
 
 
 
 
 Arsenic 
 Uranium ? 
 
 Carbon ? 
 
 
 
 ♦ 
 
 Molybdena 
 
 Tillurium 
 
 
 
 I 
 
ATT 
 
 ATT 
 
 TABLE of Simple Elective Attractions. 
 
 II.— OXYGEN AND METALS. 
 
 IN THE IIUMID WAY. 
 
 Carbon 
 Boron 
 Phosphorus 
 Sulphur 
 Azote 
 Chlorine 
 
 Oxygen. 
 
 Oxide of 
 Gold. 
 
 Oxide of 
 Silver. 
 
 Oxide of 
 Platina. 
 
 Oxide of 
 Mercury. 
 
 Oxide of 
 Lead. 
 
 Zinc 
 
 Acids, gallic 
 
 Acids, gallic 
 
 Acids, gallic 
 
 Acids, gallic 
 
 Acids, gallic 
 
 Iron 
 
 muriatic 
 
 muriatic 
 
 muriatic 
 
 muriatic 
 
 sulphuric 
 
 Tin 
 
 nitric 
 
 oxalic 
 
 nitric 
 
 oxalic 
 
 mucic 
 
 Antimony 
 
 sulphuric 
 
 sulphuric 
 
 sulphuric 
 
 succinic 
 
 oxalic 
 
 Arsenic 
 
 arsenic 
 
 mucic 
 
 arsenic 
 
 phospho- 
 
 arsenic 
 
 Lead 
 
 fluoric 
 
 phospho- 
 
 fluoric 
 
 ric 
 
 tartaric 
 
 Bismuth 
 
 tartaric 
 
 ric 
 
 tartaric 
 
 sulphuric 
 
 phospho- 
 
 Copper 
 
 phospho- 
 
 sulphur- 
 
 phospho- 
 
 mucic 
 
 ric 
 
 Platinum 
 
 ric 
 
 ous 
 
 ric 
 
 tartaric 
 
 muriatic 
 
 Mercury 
 
 acetic 
 
 nitric 
 
 oxalic 
 
 citric 
 
 sulphur- 
 
 f Palladium 
 
 sebacic 
 
 arsenic 
 
 citric 
 
 malic 
 
 OllS 
 
 J Rhodium 
 
 prussic 
 
 fluoric 
 
 acetic 
 
 sulphur- 
 
 suberic 
 
 j Iridium 
 
 Fixed alkalis 
 
 tartaric 
 
 succinic 
 
 ous 
 
 nitric 
 
 (. Osmium 
 
 Ammonia 
 
 citric 
 
 prussic 
 
 nitric 
 
 fluoric 
 
 Silver 
 
 Sulphuretted 
 
 succinic 
 
 carbonic 
 
 fluoric 
 
 citric 
 
 Gold 
 
 hydrogen 
 
 acetic 
 
 Ammonia 
 
 acetic 
 
 malic 
 
 
 
 prussic 
 
 
 benzoic 
 
 succinic 
 
 
 
 carbonic 
 
 
 boracic 
 
 acetic 
 
 
 
 Ammonia 
 
 
 prussic 
 
 benzoic 
 
 
 
 
 
 carbonic 
 
 boracic 
 
 
 
 
 
 Ammonia 
 
 prussic 
 
 
 
 
 
 
 carbonic 
 
 
 
 
 
 
 hixed alkalis 
 
 
 
 IN THE DRY WAY. 
 
 
 Fat oils 
 
 
 
 
 
 
 Ammonia 
 
 
 Gold. 
 
 Silver. 
 
 Platina. 
 
 Mercury. 
 
 Lead. 
 
 Titanium 
 
 Mercury 
 
 Lead 
 
 Arsenic 
 
 Gold 
 
 Gold 
 
 Manganese 
 
 Copper 
 
 Copper 
 
 Gold 
 
 Silver 
 
 Silver 
 
 Zinc 
 
 Silver 
 
 Mercury 
 
 Copper 
 
 Platina 
 
 Copper 
 
 Iron 
 
 Lead 
 
 Bismuth 
 
 Tin 
 
 Lead 
 
 Mercurv 
 
 Tin 
 
 Bismuth 
 
 Tin 
 
 Bismuth 
 
 Tin 
 
 Bismuth 
 
 Uranium 
 
 Tin 
 
 Gold 
 
 Zinc 
 
 Zinc 
 
 Tin 
 
 Molybdena 
 
 Antimony 
 
 Antimony 
 
 Antimony 
 
 Bismuth 
 
 Antimony 
 
 Tungsten 
 
 Iron 
 
 Iron 
 
 Nickel 
 
 Copper 
 
 Platina 
 
 Cobalt 
 
 Platina 
 
 Manganese 
 
 Cobaft 
 
 Antimony 
 
 Arsenic 
 
 Antimony 
 
 Zinc 
 
 Zinc 
 
 Manganese 
 
 Arsenic 
 
 Zinc 
 
 Nickel 
 
 Nickel 
 
 Arsenic 
 
 Iron 
 
 Iron 
 
 Nickel 
 
 Arsenic 
 
 Arsenic 
 
 Nickel 
 
 Lead 
 
 Alkaline sul- 
 
 Iron 
 
 Chromium 
 
 Cobalt 
 
 Platina 
 
 Silver 
 
 phurets 
 
 Alkaline sul- 
 
 Bismuth 
 
 Manganese 
 
 Alkaline sul- 
 
 Mercury 
 
 Sulphur 
 
 phurets 
 
 l^cad 
 
 Alkaline sul- 
 
 phurets 
 
 Alkaline sul- 
 
 
 Sulphur 
 
 Copper 
 
 Tellurium 
 
 phurets 
 
 
 phurets. 
 
 
 
 Platinum 
 
 
 
 
 
 
 Mercury 
 
 
 
 
 
 
 Silver 
 
 
 
 
 
 
 Gold 
 
 
 
 
 
 
 Hydrogen 
 
 
 
 
 
 
 1 he column under oxygen is divided into two parts. The first exhibits the 
 order in which the metals precipitate one another from acid solutions ; the 
 f^" d ’ toVauqmdin, shews the affinities of the metals for oxygen, 
 
 n i i ll 1 ' W ;y the difficulty with which their qxides are decomposed by heat. 
 It is different from Bergmann’s column. 
 
ATT 
 
 ATT 
 
 TABLE of Simple Elective Attractions. 
 
 MET ALS — (continued). 
 
 IN THE HUMID WAT. 
 
 Oxide of 
 
 Oxide of 
 
 Oxide of 
 
 Oxide of 
 
 Oxide of 
 
 Oxide of 
 
 Copper. 
 
 Iron. 
 
 Tin. 
 
 Bismuth. 
 
 Nickel. 
 
 Arsenic. 
 
 Acids, gallic 
 
 Acids, gallic 
 
 Acids, gallic 
 
 Acids, oxalic 
 
 Acids, oxalic 
 
 Acids, gallic 
 
 oxalic 
 
 oxalic 
 
 tartaric 
 
 arsenic 
 
 muriatic 
 
 muriatic 
 
 tartaric 
 
 tartaric 
 
 muriatic 
 
 tartaric 
 
 sulphuric 
 
 oxalic 
 
 muriatic 
 
 campho- 
 
 sulphuric 
 
 phospho- 
 
 tartaric 
 
 sulphuric 
 
 sulphuric 
 
 ric 
 
 oxalic 
 
 ric 
 
 nitric 
 
 nitric 
 
 mucic 
 
 sulphuric 
 
 arsenic 
 
 sulphuric 
 
 sebacic 
 
 sebacic 
 
 nitric 
 
 mucic 
 
 phospho- 
 
 muriatic 
 
 phospho- 
 
 tartaric 
 
 arsenic 
 
 muriatic 
 
 ric 
 
 nitric 
 
 ric 
 
 phospho- 
 
 phospho- 
 
 nitric 
 
 nitric 
 
 fluoric 
 
 fluoric 
 
 ric 
 
 ric 
 
 phospho- 
 
 succinic 
 
 mucic 
 
 mucic 
 
 fluoric 
 
 succinic 
 
 ric 
 
 fluoric 
 
 succinic 
 
 succinic 
 
 mucic 
 
 fluoric 
 
 arsenic 
 
 mucic 
 
 citric 
 
 citric 
 
 succinic 
 
 citric 
 
 fluoric 
 
 citric 
 
 acetic 
 
 acetic 
 
 citric 
 
 acetic 
 
 succinic 
 
 acetic 
 
 prussic 
 
 arsenic 
 
 arsenic 
 
 boracic 
 
 citric 
 
 boracic 
 
 carbonic 
 
 boracic 
 
 acetic 
 
 prussic 
 
 acetic 
 
 prussic 
 
 Ammonia 
 
 prussic 
 
 prussic 
 
 carbonic 
 
 boracic 
 
 Potash 
 
 
 carbonic 
 
 Fixed alkalis 
 
 Potash 
 
 prussic 
 
 Soda 
 
 
 Ammonia 
 
 Ammonia 
 
 Soda 
 
 carbonic 
 
 Ammonia 
 
 
 
 Fat oils 
 
 Ammonia 
 
 
 
 
 
 Water 
 
 Compound 
 
 
 
 
 
 
 salts 
 
 
 
 
 
 
 bat oils 
 
 
 
 
 
 
 
 
 IN THE DRY WAY. 
 
 
 
 Copper. 
 
 Iron. 
 
 Tin. 
 
 Bismuth. 
 
 Nickel. 
 
 Arsenic. 
 
 Gold 
 
 Nickel 
 
 Zinc 
 
 Lead 
 
 Iron 
 
 Nickel 
 
 Silver 
 
 Cobalt 
 
 Mercury 
 
 Silver 
 
 Cobalt 
 
 Cobalt 
 
 Iron 
 
 Manganese 
 
 Copper 
 
 Gold 
 
 Arsenic 
 
 Copper 
 
 Arsenic 
 
 Arsenic 
 
 Antimony 
 
 Mercury 
 
 Copper 
 
 Iron 
 
 Manganese 
 
 Copper 
 
 Gold 
 
 Antimony 
 
 Gold 
 
 Silver 
 
 Zinc 
 
 Gold 
 
 Silver 
 
 Tin 
 
 Tin 
 
 Tin 
 
 Antimony 
 
 Silver 
 
 Lead 
 
 Copper 
 
 Antimony 
 
 Lead 
 
 Platina 
 
 Tin 
 
 Iron 
 
 Platina 
 
 Platina 
 
 Gold 
 
 Tin 
 
 Antimony 
 
 Manganese 
 
 Nickel 
 
 Bismuth 
 
 Platina 
 
 Lead 
 
 Platina 
 
 Nickel 
 
 Iron 
 
 Lead 
 
 Zinc 
 
 Nickel 
 
 Bismuth 
 
 Arsenic 
 
 Zinc 
 
 Silver 
 
 Antimony 
 
 Bismuth 
 
 Lead 
 
 Platina 
 
 Alkaline sul- 
 
 Zinc 
 
 Alkaline sul- 
 
 Cobalt 
 
 Alkaline sul- 
 
 Bismuth 
 
 phurets 
 
 Alkaline sul- 
 
 phurets 
 
 Mercury 
 
 phurets 
 
 Cobalt 
 
 Sulphur 
 
 phurets 
 
 Sulphur 
 
 Alkaline sul- 
 
 Sulphur 
 
 Alkaline sill- 
 
 
 Sulphur 
 
 
 phurets 
 
 
 phurets 
 
 
 
 
 Sulphur 
 
 
 Sulphur 
 
 
 
 
ATT 
 
 ATT 
 
 TABLE of Simple Elective Attractions. 
 METALS — (concluded.) 
 
 IN THE HUMID WAY. 
 
 / 
 
 Oxide of 
 Cobalt. 
 
 Oxide of 
 Zinc. 
 
 Oxide of „ 
 Antimony*. 
 
 Oxide of 
 Manganese. 
 
 Oxide of 
 Tellurium. 
 
 Oxide of 
 Titanium. 
 
 Acids, oxalic 
 muriatic 
 sulphuric 
 tartaric 
 nitric 
 phospho- 
 ric 
 
 fluoric 
 
 mucic 
 
 succinic 
 
 citric 
 
 acetic 
 
 arsenic 
 
 boracic 
 
 prussic 
 
 carbonic 
 
 Ammonia 
 
 Acids, gallic 
 oxalic 
 sulphuric 
 muriatic 
 mucic 
 nitric 
 tartaric 
 phospho- 
 ric 
 citric 
 succinic 
 fluoric 
 arsenic 
 acetic 
 boracic 
 prussic 
 carbonic 
 Fixed alkalis 
 Ammonia 
 
 Acids, gallic 
 muriatic 
 benzoic 
 oxalic 
 sulphuric 
 nitric 
 tartaric 
 mucic 
 phospho- 
 ric 
 citric 
 succinic 
 fluoric 
 arsenic 
 acetic 
 boracic 
 prussic 
 carbonic 
 Sulphur 
 Fixed alkalis 
 Ammonia 
 
 Acids, oxalic 
 tartaric 
 citric 
 fluoric 
 phospho- 
 ric 
 nitric 
 sulphuric 
 muriatic 
 arsenic 
 acetic 
 prussic 
 carbonic 
 
 9 
 
 Acids, nitric 
 nitro-mu- 
 riatic 
 sulphuric 
 Sulphur 
 Alkalis 
 Mercury 
 
 Acids, sulphu- 
 ric 
 nitric 
 muriatic 
 prussic 
 
 Oxide of 
 Uranium. 
 
 Acids, sulphu- 
 ric 
 
 nitro- mu- 
 riatic 
 muriatic 
 nitric 
 phospho- 
 ric 
 acetic 
 gallic 
 prussic 
 carbonic 
 Sulphur 
 
 IN THE DRY WAY. 
 
 Cobalt. 
 
 Zinc. 
 
 Antimony. 
 
 Manganese. 
 
 Tellurium. 
 
 Iron 
 
 Nickel 
 
 Arsenic 
 
 Copper 
 
 Gold 
 
 Platina 
 
 Tin 
 
 Antimony 
 
 Zinc 
 
 Alkaline sul- 
 phurets 
 Sulphur 
 
 Copper 
 
 Antimony 
 
 Tin 
 
 Mercury 
 
 Silver 
 
 Gold 
 
 Cobalt 
 
 Arsenic 
 
 Platina 
 
 Bismuth 
 
 Lead 
 
 Nickel 
 
 Iron 
 
 Iron 
 
 Copper 
 
 Tin 
 
 Lead 
 
 Nickel 
 
 Silver 
 
 Bismuth 
 
 Zinc 
 
 Gold 
 
 Platina 
 
 Mercury 
 
 Arsenic 
 
 Cobalt 
 
 Alkaline sul- 
 phurets 
 Sulphur 
 
 Copper 
 
 Iron 
 
 Gold 
 
 Silver 
 
 Tin 
 
 Alkaline sul- 
 phurets 
 
 Mercury 
 
 Sulphur 
 
ATT 
 
 ATT 
 
 Schemes of Double Affinities in the Humid Way . 
 
 Sulphate 
 
 of 
 
 Magnesia 
 
 r 
 
 r Sulphuric 
 
 acid 
 50 
 
 Magnesia 
 
 \ 
 
 Fluoric 
 
 acid 
 
 Nitrate of 
 lime 
 
 r Nitric 
 
 acid 
 
 44 
 
 Lime 54 
 
 “V" 
 
 Sulphuric 
 
 acid 
 
 ) 
 
 Sulphate of lime 
 
 Arseni- 
 
 ous 
 
 acid 
 
 Muriatic' 
 
 acid 
 
 Oxygen 
 
 Arsenic 
 
 Oxygen 
 
 Oxy- 
 genated 
 muria- 
 tic acid 
 
 v 
 
 Arsenic acid 
 
 Acetate of potash 
 
 a 
 
 r 
 
 r Potash 26 Acetic 
 
 acid 
 
 Sulphuret 
 of potash 
 
 .Sulphur 
 
 Sulphuret 
 of lime ^ 
 
 Sulphate of lime 
 
 c > 
 
 ‘Lime 54 Sulphuric 
 acid 
 
 Sulphur 
 
 
 
 Muriate of potash 
 
 < A > 
 
 Potash S2 Muriatic 
 acid 
 
 Sulphate 
 of pot- < 
 ash 
 
 l 
 
 62 
 
 + 23 = 85 l M " iate 
 
 ot lime 
 
 Sulphu- ^ 
 lie acid 86 
 
 ~V"~ 
 
 Lime 
 
 /' 
 
 Sulphate of lime 
 
 Nitre 
 
 Sulphate 
 of pot- 
 ash 
 
 ( ; i 
 
 '‘Potash 58 Nitric 
 
 
 
 '‘Potash 62 
 
 Sulphu- “ 
 
 acid 
 
 Nitrate 
 
 Muriate 
 
 
 ric acid 
 
 62 
 
 > of lead 
 
 of pot- < 
 ash 
 
 32 4- 
 
 54 = 86 
 
 Sulphuric Oxide of 
 
 
 
 Muriatic 
 
 
 acid lead 
 
 
 
 acid .85 
 
 Lime^ 
 
 v 
 
 Sulphate of lead 
 
 Sul- 
 
 >phat< 
 
 lime 
 
 Nitrate of ammonia 
 
 a 
 
 Nitrate of soda 
 
 a 
 
 Sulphate 
 of am- < 
 
 "Ammo- 
 
 nia 
 
 46 
 
 38 Nitric " 
 acid 
 
 Nitrate 
 >of mer- 
 
 Com- < 
 
 "Soda 
 
 i 
 
 Nitric * 
 acid 
 
 > 
 
 monia 
 
 Sulphuric 
 
 acid 
 
 Oxide of 
 mercury J 
 
 cury 
 
 moil salt 
 
 Muriatic 
 - acid 
 
 Silver ^ 
 
 of silver 
 
 Sulphate of mercury 
 
 V 
 
 Muriate of silver 
 
A UR 
 
 AXI 
 
 * Augite. Pyroxene of Ilaiiy. This 
 mineral is for the most part crystallized in 
 small six or eight sided prisms, with dihe- 
 dral summits. It is found also in grains. 
 Its colours are green, brown, and black. In- 
 ternal lustre shining. Uneven fracture. 
 Translucent. Easily broken. It scratches 
 glass. Sp. gr. 3.3. Melts into a black 
 enamel. Its composition, according to Klap- 
 roth, is 48 silica, 24 lime, 12 oxide of iron, 
 8.75 magnesia, 5 alumina, 1 manganese. It 
 is met with among volcanic rocks, but is 
 supposed to have existed prior to the ei op- 
 tion, and ejection of the lava. Large crys- 
 tals of it are also found in basalt, of a finer 
 green and more brilliant than those found 
 in lavas. It occurs with olivin in the basalt 
 of Teesdale; in the trap rocks round Edin- 
 burgh ; and in several of the Hebrides. 
 
 Sahlite and coccolite are considered to be 
 varieties of augite.* 
 
 Aurum Fulminans. See Fulminating. 
 
 * Aurum Graphicum. See Ores of Gold.* 
 
 Aurum Musivum, or Mosaicum. A com- 
 bination of tin and sulphur, which is thus 
 made : Melt twelve ounces of tin, and add 
 to it three ounces of mercury ; triturate this 
 amalgam with seven ounces of sulphur, and 
 three of muriate of ammonia. Put the pow- 
 der into a matrass, bedded rather deep in 
 sand, and keep it for several hours in a gen- 
 tle heat ; which is afterward to be raised, 
 and continued for several hours longer. If 
 the heat have been moderate, and not conti- 
 nued too long, the golden-coloured scaly 
 porous mass, called aurum musivum, will 
 be found at the bottom of the vessel; but if 
 it have been too strong, the aurum musivum 
 fuses to a black mass of a striated texture. 
 This process is thus explained : As the heat 
 increases, the tin, by stronger affinity, seizes 
 and combines with the muriatic acid of the 
 muriate of ammonia ; while the alkali of 
 that salt, combining with a portion of the 
 sulphur, flies off in the form of a sulphuret. 
 The combination of tin and muriatic acid 
 sublimes ; and is found adhering to the sides 
 of the matrass. The mercury, which served 
 to divide the tin, combines with part of the 
 sulphur, and forms cinnabar, which also 
 sublimes ; and the remaining sulphur, with 
 the remaining tin, forms the aurum musivum 
 which occupies the lower part of the vessel. 
 It must be admitted, however, that this ex- 
 planation does not indicate the reasons why 
 such an indirect and complicated process 
 should be required to form a simple combi- 
 nation of tin and sulphur. 
 
 It does not appear that the proportions of 
 the materials require to be strictly attended 
 to. The process of the Marquis de Bullion, 
 as described by Chaptal in his Elements of 
 Chemistry, consists in amalgamating eight 
 ounces of tin with eight ounces of mercury, 
 and mixing this with sux ouncesof sulphur, and 
 
 four of muriate of ammonia. This mixture 
 is to be exposed for three hours on a sand 
 heat sufficient to render the bottom of the 
 matrass obscurely red-hot. But Chaptal 
 himself found, that if the matrass containing 
 the mixture were exposed to a naked fire, 
 and violently heated, the mixture took fire, 
 and a sublimate was formed in the neck of 
 the matrass, consisting of the most beautiful 
 aurum musivum in large hexagonal plates. 
 
 Aurum musivum has no taste, though 
 some specimens exhibit a sulphureous smell. 
 It is not soluble in water, acids, or alkaline 
 solutions. But in the dry way it forms a 
 yellow sulphuret, soluble in water. It de- 
 flagrates with nitre. Bergmann mentions a 
 native aurum musivum from Siberia, con- 
 taining tin, sulphur, and a small proportion 
 of copper. 
 
 Aurum musivum is used as a pigment for 
 giving a golden colour to small statue or 
 plaster figures. It is likewise said to be 
 mixed with melted glass to imitate lapis 
 lazuli. 
 
 * Mosaic gold is composed of 100 tin 
 56.25 sulphur, by Dr John Davy; and of 
 100 tin -J- 52.5 sulphur, by Professor Ber- 
 zelius ; the mean of which, or 1 00 — j— 54.2 
 is probably correct. It will then consist of 
 1 prime of tin = 7.375 -J- 2 sulphur = 4.0. * 
 
 * Avanturine. A variety of quartz rock 
 containing mica spangles. The most beautiful 
 comes from Spain, but Dr M‘Culloch found 
 specimens at Glen Fernat in Scotland, 
 which, when polished, were equal in beauty 
 to any of the foreign. The most usual co- 
 lour of the base of avanturine is brown, or 
 reddish brown, enclosing golden coloured 
 spangles. * 
 
 * Axe-stone. A subspecies of jade, from 
 w’hich it differs in not being of so light a 
 green, and in having a somewhat slaty texture. 
 The natives of New Zealand work it into 
 hatchets. It is found in Corsica, Switzer- 
 land, Saxony, and on the banks of the river 
 Amazons, whence it has been called Ama- 
 zonian stone. Its constituents are silica 50.5, 
 magnesia 31, alumina 10, oxide of iron 5.5, 
 water 2.75, oxide of chromium 0.05.* 
 
 * Axinite, or Thumerstone. This mine- 
 ral is sometimes massive, but most usually 
 crystallized. The crystals resemble an axe in 
 the form and sharpness of their edges ; being 
 flat rhomboidal parallelopipeds, with two of 
 the opposite edges wanting, and a small face 
 instead of each. They are translucent, and of 
 a violet colour, whence called violet schorl. 
 They become electric by heat. The usual 
 colour is clove brown. Lustre splendent. 
 Hard, but yields to the file, and easily 
 broken. Sp. gr. 3.25. It froths like zeo- 
 lite before the blow-pipe, melting into a 
 black enamel, or a dark green glass. Ac- 
 cording to Vauquelin’s analysis, it contains 
 41 silica, 18 alumina, 19 lime, 14 oxide of 
 
AZU 
 
 AZU 
 
 ft • A 
 
 iron, and 4 oxide of manganese. It is 
 found in beds at Thum in Saxony ; in Kilias 
 at Botallack near the Land’s-end, Cornwall ; 
 and at Trewellard in that neighbourhood.* 
 
 Azote. See Gas (Nitrogen). 
 
 * Azure-stone, or Lapis Lazuli. This 
 massive mineral is of a fine azure blue co- 
 lour. Lustre glistening. Fine grained un- 
 even fracture. Scratches glass, but scarcely 
 strikes fire with steel. Opaque, or translu- 
 cent on the very edges. Easily broken. Sp. 
 grav. 2.85. In a very strong heat it intu- 
 mesces, and melts into a yellowish black 
 mass. After calcination it forms a jelly 
 with acids. It consists of 46 silica, 28 
 lime, 14.5 alumina, 3 oxide of iron, 6.5 sul- 
 phate of lime, and 2. water, according to 
 Klaproth. But by a later and most inte- 
 resting research of MM. Clement and De- 
 sormes, lapis lazuli appears to be composed 
 of 34 silica, 33 alumina, 3 sulphur, and 22 
 soda. (Ann. de Chimie, tom. 57.) In this 
 analysis, however, a loss of eight per cent 
 was experienced. These distinguished che- 
 mists consider the above ingredients essential, 
 and the 2.4 of lime and 1.5 of iron, which 
 they have occasionally met with, as accidental. 
 It is from azure-stone that the beautiful and 
 unchangeable blue colour ultramarine is pre- 
 pared. The finest specimens are brought 
 from China, Persia, and Great Bucharia. 
 
 They are made red-hot in the fire, and 
 thrown into water to render them easily pul- 
 verizable. They are then reduced to a fine 
 powder, and intimately combined with a var- 
 nish, formed of rosin, wax, and boiled lin- 
 seed oil. This pasty mixture is put into a 
 linen cloth, and repeatedly kneaded with 
 hot water : the first water, which is usually 
 dirty, is thrown away ; the second gives a 
 blue of the first quality ; and the third yields 
 one of less value. The process is founded 
 on the property which the colouring matter 
 of azure- stone has of adhering less firmly to 
 the resinous cement, than the foreign matter 
 with which it is associated. When azure- 
 stone has its colour altered bv a moderate 
 heat, it is reckoned bad. Messrs Clement 
 and Desormes consider the extraction of 
 ultramarine as a species of saponification. * 
 
 * Azurite, the Lazulite of Werner and 
 Ilaiiy. This mineral is often found in ob- 
 lique quadrangular crystals of a fine blue co- 
 lour. It is translucent only on the edges, 
 brittle, and nearly as hard as quartz. When 
 massive, it is either in grains, or bits like a 
 hazel nut. It occurs imbedded in mica 
 slate. Its lustre is vitreous. Its constituents 
 are 66 alumina, 18 magnesia, 10 silica, 2.5 
 oxide of iron, 2 lime. It occurs in Vorau in 
 Stiria in a gangue of quartz ; but the finest spe- 
 cimens come from the bishopric of Salzburg. * 
 
 B 
 
 B ALANCE. The beginning and end of 
 every exact chemical process consists 
 in weighing. With imperfect instruments 
 this operation will be tedious and inaccurate ; 
 but with a good balance, the result will be 
 satisfactory ; and much time, which is so 
 precious in experimental researches, will be 
 saved. 
 
 The balance is a lever, the axis of motion 
 of which is formed with an edge like that 
 of a knife ; and the two dishes at its extre- 
 mities are hung upon edges of the same 
 kind. These edges are first made sharp, 
 and then rounded with a fine hone, or a 
 piece of buff* leather. The excellence of 
 the instrument depends, in a great mea- 
 sure, on the regular form of this rounded 
 part. When the lever is considered as a mere 
 line, the two outer edges are called points 
 of suspension, and the inner the fulcrum. 
 The points of suspension are supposed to be 
 at equal distances from the fulcrum, and 
 to be pressed with equal weights when 
 loaded. 
 
 1. If the fulcrum be placed in the centre 
 of gravity of the beam, and the three edges 
 lie all in the same right line, the balance 
 rvill have no tendency to one position more 
 than another, but will rest in any position it 
 
 may be placed in, w hether the scales be on 
 or oft', empty or loaded. 
 
 2. If the centre of gravity of the beam, 
 when level, be immediately above the ful- 
 crum, it will overset by the smallest action ; 
 that is, the end which is lowest will descend: 
 and it wdll do this with more swiftness, the 
 higher the centre of gravity, and the less the 
 points of suspension are loaded. 
 
 3. But if the centre of gravity of the 
 beam be immediately below the fulcrum, the 
 beam w r ill not rest in any position but when 
 level : and, if disturbed from this position, 
 and then left at liberty, it w ill vibrate, and 
 at last come to rest on the level. Its vibra- 
 tions will be quicker, and its horizontal ten- 
 dency stronger, the lower the centre of gra- 
 vity, and the less the w eights upon the points 
 of suspension. 
 
 4. If the fulcrum be below the line join- 
 ing the points of suspension, and these be 
 loaded, the beam will overset, unless pre- 
 vented by the weight of the beam tending to 
 produce a horizontal position, as in § 3. In 
 this last case, small weights will equilibrate, 
 as in § 3. ; a certain exact weight will rest 
 in any position of the beam, as in § L; and 
 all greater weights will cause the beam to 
 overset, as in § 2. Many scales arc often 
 
BAL 
 
 BAL 
 
 made this way, and will overset with any 
 considerable load. 
 
 5. If the fulcrum be above the line join- 
 ing the points of suspension, the beam will 
 come to the horizontal position, unless pre- 
 vented by its own weight, as in § 2. If 
 the centre of gravity of the beam be 
 nearly in the fulcrum, all the vibrations of 
 the loaded beam will be made in times 
 nearly equal, unless the weights be very 
 small, when they will be slower. The vibra- 
 tions of balances are quicker, and the horizon- 
 tal tendency stronger, the higher the fulcrum. 
 
 6. If the arms of a balance be unequal, 
 the weights in equipoise will be unequal in 
 the same proportion. It is a severe check 
 upon a workman to keep the arms equal, 
 while he is making the other adjustments in 
 a strong and inflexible beam. 
 
 7. The equality of the arms of a balance 
 is of use, in scientific pursuits, chiefly in 
 making weights by bisection. A balance 
 with unequal arms will weigh as accurately 
 as another of the same workmanship with 
 equal arms, provided the standard weight 
 itself be first counterpoised, then taken out 
 of the scale, and the thing to be weighed be 
 put into the scale, and adjusted against the 
 counterpoise ; or when proportional quanti- 
 ties only are considered, as in chemical and 
 in other philosophical experiments, the bo- 
 dies and products under examination may 
 be weighed against the weights, taking care 
 always to put the weights into the same 
 scale. For then, though the bodies may 
 not be really equal to the weights, yet their 
 proportions among each other may be the 
 same as if they had been accurately so. 
 
 8. But though the equality of the arms 
 may be well dispensed with, yet it is indis- 
 pensably necessary, that their relative lengths, 
 whatever they may be, should continue inva- 
 riable. For this purpose, it is necessary, 
 either that the three edges be all truly paral- 
 lel, or that the points of suspension and sup- 
 port should be always in the same part of 
 the edge. This last requisite is the most 
 easily obtained. 
 
 The balances made in London are usually 
 constructed in such a manner, that the 
 bearing parts form notches in the other 
 parts of the edges ; so that the scales being 
 set to vibrate, all the parts naturally fall 
 into the same bearing. The balances made 
 in the country have the fulcrum edge straight, 
 and confined to one constant bearing by two 
 side plates. But the points of suspension 
 are referred to notches in the edges, like the 
 London balances. Ihe balances here men- 
 tioned, which come from the country, are 
 enclosed in a small iron japanned box ; and 
 are to be met with at the Birmingham and 
 Sheffield warehouses, though less frequently 
 than some years ago; because a pocket con- 
 trivance for weighing guineas and half-gui- 
 
 neas has got possession of the market. They 
 are, in general, well made and adjusted, turn 
 with the twentieth of a grain when empty, 
 and will sensibly show the tenth of a grain, 
 with an ounce in each scale. Their price is 
 from five shillings to half a guinea; but 
 those which are under seven shillings have 
 not their edges hardened, and consequently 
 are not durable. This may be ascertained 
 by the purchaser, by passing the point of a 
 penknife across the small piece which goes 
 through one of the end boxes ; if it makes 
 any mark or impression, the part is soft. 
 
 9. If a beam be adjusted so as to have no 
 tendency to any one position, as in § 1. and 
 the scales be equally loaded ; then, if a small 
 weight be added in one of the scales, that 
 balance will turn, and the points of suspen- 
 sion will move with an accelerated motion, 
 similar to that of falling bodies, but as much 
 slower, in proportion, very nearly, as the 
 added weight is less than the whole weight 
 borne by the fulcrum. 
 
 10. The stronger the tendency to a hori- 
 zontal position in any balance, or the quicker 
 its vibrations, §§ 3. 5. the greater additional 
 weight will be required to cause it to turn, 
 or incline to any given angle. No balance, 
 therefore, can turn so quick as the motion 
 deduced in § 9. Such a balance as is there 
 described, if it were to turn with the ten- 
 thousandth part of the weight, would move 
 at quickest ten thousand times slower than 
 falling bodies ; that is, the dish containing 
 the weight, instead of falling through sixteen 
 feet in a second of time, would fall through 
 only two hundred parts of an inch, and it 
 would require four seconds to move through 
 one-third part of an inch ; consequently all 
 accurate weighing must be slow. If the in- 
 dexes of two balances be of equal lengths, 
 that index which is connected with the 
 shorter balance wil 1 move proportionally 
 quicker than the other. Long beams are 
 the most in request, because they are thought 
 to have less friction ; this is doubtful ; but 
 the quicker angular motion, greater strength, 
 and less weight of a short balance, are cer- 
 tainly advantages. 
 
 11. Very delicate balances are not only 
 useful in nice experiments, but are likewise 
 much more expeditious than others in com- 
 mon weighing. If a pair of scales with a 
 certain load be barely sensible to one-tenth 
 of a grain, it will require a considerable time 
 to ascertain the weight to that degree of ac- 
 curacy, because the turn must be observed 
 several times over, and is very small. But 
 if no greater accuracy were required, and 
 scales were used which would turn with the 
 hundredth of a grain, a tenth of a grain, 
 more or less, would make so great a differ- 
 ence in the turn, that it would be seen im- 
 mediately. 
 
 12. If a balance be found to turn with a 
 13 
 
BAL 
 
 BAL 
 
 certain addition, and is not moved bv anv 
 smaller weight, a greater sensibility may be 
 given to that balance, by producing a tre- 
 mulous motion in its parts. Thus, if the 
 edge of a blunt saw, a file, or other similar 
 instrument, be drawn along any part of the 
 case or support of a balance, it will produce 
 a jarring, which will diminish the friction 
 on the moving parts so much, that the turn 
 will be evident with one-third or one-fourth 
 of the addition that would else have been 
 required. In this way, a beam which would 
 barely turn by the addition of one-tenth of 
 a grain, will turn with one-thirtieth or forti- 
 eth of a grain. 
 
 IS. A balance, the horizontal tendency of 
 which depends only on its own weight, as in 
 § 3. will turn with the same addition, what- 
 ever may be the load ; except so far as a 
 greater load will produce a greater fric- 
 tion. 
 
 14. But a balance, the horizontal tendency 
 of which depends only on the elevation of 
 the fulcrum, as in § 5. will be less sensible 
 the greater the load ; and the addition re- 
 quisite to produce an equal turn will be in 
 proportion to the load itself. 
 
 15. In order to regulate the horizontal 
 tendency in some beams, the fulcrum is 
 placed below the points of suspension, as in 
 § 4. and a sliding weight is put upon the 
 cock or index, by means of which the centre 
 of gravity may be raised or depressed. This 
 is a useful contrivance. 
 
 16. Weights are made bv a subdivision 
 of a standard weight. If the weight be con- 
 tinually halved, it will produce the common 
 pile, which is the smallest number for weigh- 
 ing between its extremes, without placing 
 any weight in the scale with the body under 
 examination. Granulated lead is a very 
 convenient substance to be used in this ope- 
 ration of halving, which, however, is very 
 tedious. The readiest way to subdivide small 
 weights, consists in weighing a certain quan- 
 tity of small wire, and afterward cutting it 
 into such parts, by measure, as are desired ; 
 or the wire may be wrapped close round two 
 pins, and then cut asunder with a knife. By 
 this means it will be divided into a great 
 number of equal lengths, or small rings. 
 The wire ought to be so thin, as that one ot 
 these rings may barely produce a sensible 
 elfect on the beam. If any quantity (as, for 
 example, a grain) of these rings be weighed, 
 and the number then reckoned, the gr*in 
 may be subdivided in any proportion, by di- 
 viding that number, and making the weights 
 equal to as many of the rings as the quotient 
 of the division denotes. Then, if 750 of the 
 rings amounted to a grain, and it were re- 
 quired to divide the grain decimally, down- 
 wards, 9-10ths would be equal to 675 rings, 
 8-lOths would bo equal to 600 rings, 7-10tlis 
 to 525 rings, & c. Small weights may be 
 
 made of thin leaf brass. Jewellers’ foil is a 
 good material for weights below 1-1 Oth of a 
 grain, as low as to l-100th of a grain ; and 
 all lower quantities may be either estimated 
 by the position of the index, or shown by 
 actually counting the rings of wire, the value 
 of which has been determined. 
 
 17. In philosophical experiments, it will 
 be found very convenient to admit no more 
 than one dimension of weight. The grain 
 is of that magnitude as to deserve the pre- 
 ference. With regard to the number of 
 weights the chemists ought to be provided 
 with, writers have differed according to their 
 habits and views. Mathematicians have 
 computed the least possible number, with 
 which all weights within certain limits might 
 he ascertained ; but their determination is of 
 little use. Because, with so small a num- 
 ber, it must often happen, that the scales 
 will be heavily loaded with weights on each 
 side, put in with a view only to determine 
 the difference between them. It is not the 
 least possible number of weights which it is 
 necessary an operator should buy to effect 
 his purpose, that we ought to inquire after, 
 but the most convenient number for ascer- 
 taining his inquiries with accuracy and ex- 
 pedition. The error of adjustment is the 
 least possible, when only one weight is in 
 the scale ; that is, a single weight of live 
 grains is twice as likely to be true, as two 
 weights, one of three, and the other of two 
 grains, put into the dish to supply the place 
 of the single five ; because each of these last 
 has its own probability of error in adjust- 
 ment. But since it is as inconsistent with 
 convenience to provide a single weight, as it 
 would be to have a single character for every 
 number ; and as we have nine characters, 
 which we use in rotation, to express higher 
 values according to their position, it will be 
 found very serviceable to make the set of 
 weights correspond with our numerical sys- 
 tem. This directs us to the set of weights as 
 follows : 1000 grains, 900 g. 800 g. 700 g. 
 600 g. 500 g. 400 g. 500 g. 200 g. ICOg. 
 90 g. 80 g. 70 g. 60 g. 50 g. 40 g. SO g. 
 20 g. 10 g. 9 g. 8. g. 7 g. 6 g. 5. g. 4 g. 
 
 3 g- 2 g. 1 g. 
 
 _5_ cr cr. 
 
 1 0 to * 1 0 to * 
 __H_ or _7 , r 
 10 0 to* 107) to* 
 _H_ or _jri_ fr . 
 
 1 0 0 to* 100 
 
 0 nr 6 or 7 cj 6 _ cr 
 \ 0 &* 1 0 to* _l o to* 1 0 to 
 
 ."> Q* _j2 _ Q* 
 
 10 to* id to* 1 0 to _ 
 
 cr 5. or _it-_ IT 
 
 ldd to 
 
 too £>* 
 
 i 
 
 100 
 
 g* 
 
 _l_ cr, _H_ cr, 
 ' ^ *“ * 100 C' 
 
 cr, 
 
 100 to* 
 
 With these the 
 
 philosopher will always have the same num- 
 ber of weights in his scales as there are 
 figures in the number expressing the weights 
 
 in grains. 
 
 Thus 742.5 grains will be weighed by the 
 weights 700, 40, 2, and 5-10ths. 
 
 I shall conclude this chapter with an ac- 
 count of some balances I have seen or heard 
 of, and annex a table of the correspondence 
 of weights of different countries. 
 
 Muschenbroek, in his Cours de Physique, 
 (French translation, Paris, 1769), tom. h- 
 
BAL 
 
 BAL 
 
 p. 247 . says, he used an ocular balance of 
 great accuracy, which turned (trebuchoit) 
 with 77 of a grain. The substances he 
 weighed were between 200 and 300 grains. 
 His balance therefore weighed to the 73777 
 part of the whole ; and would ascertain such 
 weights truly to four places of figures. 
 
 In the Philosophical Transactions, vol. 
 lxvi. p. 509 . mention is made of two accu- 
 rate balances of Mr Bolton ; and it is said 
 that one would weigh a pound, and turn 
 
 with 77 of a grain. This, if the pound be 
 
 avoirdupois, is 7-7777 °f the weight; and 
 shews that the balance could be well depend- 
 ed on to four places of figures, and probably 
 to five. The other weighed half an ounce, 
 
 and turned with 777 of a grain. This is 
 
 £7 0 77 of the weight. 
 
 In the same volume, p. 51 1 . a balance of 
 Mr Read’s is mentioned, which readily 
 turned with less than one pennyweight, 
 when loaded with 55 pounds, before the 
 Royal Society ; but very distinctly turned 
 with four grains, when tried more patiently. 
 
 This is about 777777 part of the weight; 
 and therefore this balance may be depended 
 on to five places of figures. 
 
 Also, page 576 . a balance of Mr White- 
 hurst’s weighs one pennyweight, and is sen- 
 sibly affected with 27W °** a g ra i n * This 
 
 lS TS'oTTo P art the weight. 
 
 I have a pair of scales of the common 
 construction, § 8. made expressly for me by 
 a skilful workman in London. With 1200 
 grains in each scale, it turns with 77 of a 
 
 grain. This is 77777 of the whole ; and 
 therefore about this weight may be known 
 to five places of figures. The proportional 
 delicacy is less in greater weights. The 
 beam will weigh near a pound troy ; and 
 when the scales are empty, it is affected by 
 
 TThTo °1* a grain. On the whole, it may be 
 usefully applied to determine all weights be- 
 tween 100 grains and 4000 grains to four 
 places of figures. 
 
 A balance belonging to Mr Alchorne of 
 the Mint in London, is mentioned, vol. 
 Ixxvii. p. 205 . of the Philosophical Transac- 
 tions. It is true to 5 grains with 15 lb. an 
 end. It these were avoirdupois pounds, the 
 
 weight is known to 77777 part, or to four 
 places of figures, or barely five. 
 
 A balance, (made by llamsden, and turn- 
 ing on points instead of edges) in the pos- 
 session of* Dr George Fordyce, is mentioned 
 in the seventy-fifth volume of the Philoso- 
 phical Transactions. With a load of four 
 or five ounces, a difference of one division in 
 the index was made by 7777 of a grain. 
 
 This is 5 7 47 7 7 part of the weight, and 
 < onsequently this beam will ascertain such 
 weights to five places of figures, beside an 
 •vtiinate figure. 
 
 I have seen a strong balance in the pos- 
 session of my friend Mr Magellan, of the 
 kind mentioned in § 15 . which would bear 
 
 several pounds, and showed 77 of a grain, 
 
 with one pound an end. This is 77777 of 
 the weight, and answers to five figures. But 
 I think it would have done more by a more 
 patient trial than I had time to make. 
 
 The Royal Society’s balance, which was 
 lately made by Ramsden, turns on steel 
 edges, upon planes of polished crystal. I 
 was assured, that it ascertained a weight to 
 the seven-millionth part. I was not present 
 at this trial, which must have required great 
 care and patience, as the point of suspension 
 could not have moved over much more than 
 
 the 777 of an inch in the first half minute ; 
 but, from some trials which I saw, I think it 
 probable that it may be used in general prac- 
 tice to determine weights to five places and 
 better. 
 
 From this account of balances, the stu- 
 dent may form a proper estimate of the 
 value of those tables of specific gravities, 
 which are carried to five, six, and even 
 seven places of figures, and likewise of the 
 theoretical deductions in chemistry, that 
 depend on a supposed accuracy in weighing, 
 which practice does not authorize. In gene- 
 ral, where weights are given to five places of 
 figures, the last figure is an estimate, or 
 guess figure ; and where they are carried 
 farther, it may be taken for granted, that 
 the author deceives either intentionally, or 
 from vrant of skill in reducing his weights to 
 fractional expressions, or otherw ise. 
 
 The most exact standard weights were 
 procured, by means of the ambassadors of 
 France, resident in various places; and these 
 were compared by Mons. Tillet with the 
 standard mark in the pile preserved in the 
 Cour de Monnoies de Baris. His experiments 
 were made with an exact balance made to 
 weigh one marc, and sensible to one quarter 
 of a grain. Now, as the marc contains 
 18432 quarter grains, it follows that this 
 balance was a good one, and would exhibit 
 proportions to four places, and a guess figure. 
 The results are contained in the following 
 table, extracted from Mons. Tillet’s excel- 
 lent paper in the Memoirs of the Royal 
 Academy of Sciences for the year 1767 . I 
 have added the two last columns, which 
 show' the number of French and English 
 grains contained in the compound quantities 
 against which they stand. The English 
 grains are computed to one-tenth of a grain, 
 although the accuracy of weighing came no 
 nearer than about two-tenths. 
 
 The weights of the kilogramme, gramme, 
 decigramme, and centigramme, which arc now 
 frequently occurring in the French chemical 
 writers, are added at the bottom of this ta- 
 ble, according to their respective values. 
 
15AL 
 
 UAL 
 
 Table of the Weights of different Countries. 
 
 Marc. oz. groe. grains F. grains. 
 
 
 Place and Denomination of Weights. 
 
 Berlin. The marc of 16 loths, 
 
 Berne. Goldsmiths’ weight of 8 ounces, - 
 Berne. Bound of 16 ounces, for merchan- 
 dise, - 
 
 1 he common pound varies very consider- 
 ably in other towns of the canton. 
 Berne. Apothecaries weight of 8 ounces, - 
 Bonn, - 
 
 Brussels. The marc, or original troyes 
 weight, - 
 
 Cologn. The marc of 16 loths, 
 Constantinople. The cheki, or 100 drachms, 
 Copenhagen. Goldsmiths’ weight com 
 monly supposed equal to the marc of 
 Cologn, 
 
 Copenhagen. Merchants’ weight of 1 6 loths, 
 Dantzic weight ; commonly supposed equal ) 
 to the marc of Cologn, \ 
 
 Florence. The pound (anciently used by ) 
 the Romans), £ 
 
 Genoa. The peso sottile, - 
 Genoa. The peso grosso, 
 
 Hamburgh weight ; commonly supposed 7 
 equal to the Cologn marc, ) 
 
 Hamburgh. Another weight, 
 
 The Brussels marc used ; but the } 
 weight proved, } 
 
 Lisbon. The marc, or half pound, 
 
 London. The pound troy, 
 
 London. The pound avoirdupois, 
 
 Lucca. The pound, 
 
 Madrid. The marc royal of Castile, 
 
 Malta. The pound, - 
 
 Manheim. (The Cologn marc), 
 
 Milan. The marc, - 
 Milan. The libra grossa, 
 
 Munich. (The Cologn marc), 
 
 The pound of 12 ounces, 
 
 The weight for gold of 1 28 crowns, 
 The weight for ducats : of 64 
 
 Liege. 
 
 Naples. 
 
 Ratisbon. 
 
 Ratisbon. 
 
 ducats, 
 
 Ratisbon. 
 
 Ratisbon. 
 
 i 
 
 The marc of 8 ounces, 
 
 The pound of 1 6 ounces, 
 
 Rome. The pound of 12 ounces, 
 Stockholm. The pound of 2 marcs, 
 Stuttgard. (The Cologn marc), 
 
 Turin. The marc of 8 ounces, 
 
 At Turin they have also a pound of 1 1 
 of the above ounces. But, in tliei 
 apothecaries pound of 12 ounces, th 
 ounce is one-sixth lighter. 
 
 Warsaw. The pound, 
 
 Venice. The libra grossa of 12 ounces, 
 Venice. The peso sottile of 12 ounces, 
 
 In the pounds dependent on Venice 
 
 Vienna. The marc of commerce, 
 
 Vienna. The marc of money, 
 
 England. The grain, 
 
 France. The grain, 
 
 The kilogramme, 
 
 The gramme, 
 
 The decigramme, 
 
 The centigramme, 
 
 See Tables of Weights and Measures in the Appendix. 
 
 E. grains. 
 
 — 
 
 7 
 
 5 
 
 16 
 
 4408 
 
 3616.3 
 
 1 
 
 — 
 
 i 
 
 4 
 
 4648 
 
 3815.2 
 
 2 
 
 1 
 
 A 
 
 a 
 
 6 
 
 9834 
 
 8067.7 
 
 _ 
 
 7 
 
 H 
 
 26 
 
 4454 
 
 3654. 
 
 — 
 
 7 
 
 5 
 
 
 4398* 
 
 3608.6 
 
 1 
 
 — 
 
 — 
 
 21 
 
 4629 
 
 3797.6 
 
 — 
 
 7 
 
 5 
 
 11 
 
 4403 
 
 3612.2 
 
 1 
 
 2 
 
 3 
 
 28 
 
 6004 
 
 4925.6 
 
 — 
 
 7 
 
 <A 
 
 
 443 8 j 
 
 3641.2 
 
 1 
 
 — 
 
 1 
 
 22* 
 
 4702* 
 
 3857.9 
 
 — 
 
 7 
 
 5 
 
 3* 
 
 4395^ 
 
 3606. 
 
 1 
 
 3 
 
 X 
 
 a 
 
 20 
 
 6392 
 
 5 44. 
 
 1 
 
 2 
 
 OJL 
 
 30 
 
 5970 
 
 4897.7 
 
 1 
 
 2 
 
 3 
 
 5 
 
 5981 
 
 4906.7 
 
 — 
 
 7 
 
 5 
 
 n 
 
 4399* 
 
 3609.4 
 
 — 
 
 7 
 
 7 
 
 23 
 
 4559 
 
 3740.2 
 
 1 
 
 — 
 
 — 
 
 24 
 
 4632 
 
 3800.1 
 
 — - 
 
 7 
 
 
 34 
 
 4318 
 
 3542.4 
 
 1 
 
 4 
 
 
 1 
 
 7021 . 
 
 5760. 
 
 1 
 
 6 
 
 Ǥ 
 
 6 
 
 8538 
 
 7004.5 
 
 1 
 
 3 
 
 
 23 
 
 6359* 
 
 5217. 
 
 — 
 
 7 
 
 4 
 
 H 
 
 4328 
 
 3550.7 
 
 1 
 
 2 
 
 H 
 
 21 
 
 5961 
 
 4890.4 
 
 — — 
 
 7 
 
 5 
 
 10 
 
 4402 
 
 3611.5 
 
 — 
 
 7 
 
 . 5 
 
 33* 
 
 4425 
 
 3660.2 
 
 3 
 
 — 
 
 7 X 
 • a 
 
 — 
 
 14364* 
 
 1 1 784. 
 
 — 
 
 7 
 
 5 
 
 11 
 
 4403* 
 
 3612.9 
 
 1 
 
 2 
 
 H 
 
 27* 
 
 6039 
 
 4954. S 
 
 1 
 
 6 
 
 
 24 
 
 8088 
 
 6635.3 
 
 — 
 
 7 
 
 2 
 
 32 
 
 4208 
 
 3452.3 
 
 1 
 
 ... 
 
 _ 
 
 24 
 
 4632 
 
 3800.1 
 
 2 
 
 2 
 
 
 6 
 
 10698 
 
 8776.5 
 
 1 
 
 3 
 
 h 
 
 14 
 
 6386 
 
 5239. 
 
 1 
 
 5 
 
 7 
 
 8 
 
 8000 
 
 6563.1 
 
 — 
 
 7 
 
 5 
 
 11| 
 
 4403* 
 
 3612.6 
 
 | 
 
 
 
 22* 
 
 1 
 
 4630* 
 
 3799. 
 
 1 
 
 5 
 
 2 
 
 12 
 
 7644 
 
 6271. 
 
 1 
 
 7 
 
 4 h 
 
 2 5* 
 
 8989* 
 
 7374.5 
 
 1 
 
 1 
 
 6 h 
 
 24 
 
 5676 
 
 4656.5 
 
 1 
 
 1 
 
 1 
 
 16 
 
 5272 
 
 4325. 
 
 1 
 
 1 
 
 1 
 
 26 
 
 5282 
 
 4333.3 
 
 ■ ■ — 
 
 — — 
 
 — 
 
 
 0.82039 
 
 1. 
 
 
 — 
 
 
 
 _ 
 
 1. 
 
 1.21895 
 
 4 
 
 — 
 
 5 
 
 35 
 
 18827.15 
 
 15445.5 
 
 _ 
 
 — 
 
 — 
 
 — 
 
 18.827 
 
 15.445 
 
 - 
 
 - 
 
 
 _ 
 
 1.8827 
 
 1.5445 
 
 — 
 
 — 
 
 — 
 
 — 
 
 .18827 
 
 .15445 
 
BAL 
 
 BAL 
 
 * The commissioners appointed by the Bri- 
 tish government for considering the subject 
 of weights and measures, gave in their first 
 report on the 24th June 1819. The follow- 
 ing is the substance of it : 
 
 “ 1. With respect to the actual magnitude 
 of the standards of length, the commissioners 
 ure of opinion, that there is no sufficient rea- 
 son for altering those generally employed, 
 as there is no practical advantage in having 
 a quantity commensurable to any original 
 quantity existing, or which may be imagined 
 to exist, in nature, except as affording some 
 little encouragement to its common adoption 
 by neighbouring nations. 
 
 “ 2. The subdivisions of weights and 
 measures at present employed in this coun- 
 try, appear to be far more convenient for 
 practical purposes than the decimal scale. 
 The power of expressing a third, a fourth, 
 and a sixth of a foot in inches, without a 
 fraction, is a peculiar advantage in the duo- 
 decimal scale ; and for the operation of 
 weighing and of measuring capacities, the 
 continual division by two, renders it practi- 
 cable to make up any given quantity with 
 the smallest possible number of weights and 
 measures, and is far preferable in this respect 
 to any decimal scale. The commissioners 
 therefore recommend, that all the multiples 
 and subdivisions of the standard to be adopt- 
 ed, should retain the same relative propor- 
 tion:, to each other as are at present in gene- 
 ral use. 
 
 “ 3. That the standard yard should be 
 that employed by General Roy in the mea- 
 surement of a base on Hounslow Heath, as 
 a foundation of the great trigonometrical 
 survey. 
 
 “ 4. That in case this standard should be 
 lost or impaired, it shall be declared, that the 
 length of a pendulum, vibrating seconds of 
 mean solar time in London, on the level of 
 
 the sea, and in a vacuum, is 59.1572 inches 
 of the standard scale, and that the length ct 
 the French metre, as the 10 millionth part of 
 the quadrantal are of the meridian, has been 
 found equal to 39.3694 inches. 
 
 “ 5. That 10 ounces troy, or 4800 grains, 
 should be declared equal to the weight of 1 9 
 cubic inches of distilled water, at the tem- 
 perature of 50°, and that one pound avoir- 
 dupois must contain 7000 of these grains. 
 
 “ 6. That the standard ale and corn gal- 
 lon should contain exactly ten pounds avoir- 
 dupois of distilled water at 62° Fahr. being 
 nearly equal to 277.2 cubic inches, and 
 agreeing with the standard pint in the Ex- 
 chequer, which is found to contain exactly 
 20 ounces of water. The customary ale gal- 
 lon contains 282 cubic inches, and the Win- 
 chester corn gallon 269, or according to 
 other statutes 272y cubic inches; so that no 
 inconvenience can possibly be felt from the 
 introduction of a new gallon of 277.2 inches. 
 The commissioners have not decided upon 
 the propriety of abolishing entirely the use 
 of the wine gallon.” 
 
 The following elegantly simple relations 
 of weight and measure were suggested by 
 Dr Wollaston, in his examination before the 
 committee ; and it is to be hoped they will 
 be adopted in the national system : 
 
 “ There is one standard of capacity that 
 would be particularly advantageous, because 
 it would bear simple proportions to the mea- 
 sures now in use, so that one of the great 
 inconveniences arising from change of the 
 standard would be obviated, by the facility 
 of making many necessary computations 
 without reference to tables. 
 
 “ If the gallon measure be defined to be 
 that which contains 10 lbs of water at 56^° 
 F. ; then, since the cubic foot of water 
 weighs 1000 oz. at 56\°, 
 
 i pint = 18 oz. = cubic foot = 17.28 inches. 
 
 Pint = 20 oz. = 34.56 inches. 
 
 Bushel = 80 lb. = 2211.84. 
 
 “ And the simple proportions above alluded to will be found as follows : 
 
 The gallon of 10 lb. 
 
 Also, 
 
 The pint of 1-J lb. 
 
 Bushel of 80 lb. 
 
 A cylinder of 18f in. diam. 
 Ditto 18f 
 
 Cubic Inches. 
 
 276.48 xi= 282.01 
 
 276.48 X T2 = 230.40 
 34.56 X ^ = 103.68 
 
 2211.84 X |4 = 2150.40 
 X 8 = 2208.93 
 
 X 8.010.5 
 
 282 beer gallon. 
 
 231 wine gallon. 
 103.4 Stirlg. jug. 
 
 2150.42 Winch, bush. 
 Approximate bush. 
 221.184 new bush. 
 
 “ The following mode of defining the standards of length, weight, and capacity, 
 
 is submitted to the committee on weights and measures, as the most distinct answer to 
 their inquiries : 
 
 One yard, of 36 inches, X 15 suc ^’ that a pendulum of 39.13 inches, vibrates seconds in 
 
 ) London. 
 
 a „«* $ one pound, of ) . 
 
 AVOir * i 16 oz. J ts suc ffi ^ iat one cu t> ic foot of water at 56|°, weighs 1000 oz. 
 
 O 
 
13 A R 
 
 13AR 
 
 Troy. 
 
 \ one pound, of 
 t 5760 grains, 
 
 One gallon, of 8 pints, 
 
 « such, that 7000 grains = 1 pound (avoirdupois). 
 
 may be such as to contain 10 pounds of distilled water at the 
 temperature of 56\° Fahr. with great convenience.” 
 
 Captain Kater has lately made a small 
 correction on his first determination of the 
 length of the pendulum vibrating seconds 
 in the latitude of London. Instead of 
 39.13860 inches, as given in the Ph, Trans, 
 for 1818, he has made it 39.13929 inchas 
 of Sir Geo. Slmckburgh’s standard scale. 
 
 n 
 
 Mr Watts, in the 5th number of the Edin- 
 burgh Philosophical Journal, makes it = 
 39. 1.58666 of the above scale, or = 
 39.1372405 of General Roy’s scale, at Cap- 
 tain Rater’s temperature of 62° Fahr. and 
 0.9941 of a metre.* 
 
 * Baikalite. See Tremolite Asbesti- 
 form.* 
 
 Balas, or Balais Ruby. See Spinelle. 
 
 Balloon. Receivers of a spherical form 
 are called balloons. 
 
 Balloon. See Aerostatics. 
 
 * Balsams, are vegetable juices, either li- 
 quid, or which spontaneously become doncrete, 
 consisting of a substance of a resinous nature, 
 combined with benzoic acid, or which are cap- 
 able of affording benzoic acid, by being heated 
 alone, or with water. They are insoluble in 
 water, but readily dissolve in alcohol and 
 ether. The liquid balsams are copaiva, opo- 
 balsam, Peru, styrax, tolu ; the concrete are 
 benzoin, dragon’s blood, and storax ; wdiich 
 see.* 
 
 Balsam of Sulphur. A solution of sul- 
 phur in oil. 
 
 * Baldwin’s Phosphorus. Ignited ni- 
 trate of lime.* 
 
 * Barium. The metallic basis of the 
 earth barytes has been called barium by its 
 discoverer, Sir H. Davy. Take pure barytes, 
 make it into a paste with water, and put this 
 on a plate of platinum. Make a cavity in 
 the middle of the barytes, into which a glob- 
 ule of mercury is to be placed. Touch the 
 globule with the negative wire and the pla- 
 tinum with the positive wire, of a voltaic 
 battery of about 100 pairs of plates in good 
 action. In a short time an amalgam will be. 
 formed, consisting of mercury and barium. 
 This amalgam must be introduced into a lit- 
 tle bent tube, made of glass free from lead, 
 sealed at one end, which being tilled with 
 the vapour of naphtha, is then to be hermeti- 
 cally sealed at the other end. Ileat must be 
 applied to the recurved end of the tube, 
 where the amalgam lies. The mercury will 
 distil over, while the barium will remain. 
 
 This metal is of a dark grey colour, with a 
 lustre inferior to that of cast-iron. It is fu- 
 sible at a red heat. Its density is superior 
 to that of sulphuric acid; for though sur- 
 rounded with globules of gas, it sinks imme- 
 diately in that liquid. When exposed to air, 
 
 it instantly becomes covered with a crust of 
 barytes ; and when gently heated in air, 
 burns with a deep red light. It effervesces 
 violently in water, converting this liquid in- 
 to a solution of barytes. Sir II. Davy 
 thinks it probable that barium may be pro- 
 cured by chemical as well as electrical de- 
 composition. When chloride of barium, or 
 even the dry earth, ignited to whiteness,, is 
 exposed to the vapour of potassium, a dark 
 grey substance is found diffused through the 
 barytes or the chloride, not volatile, which 
 effervesces copiously in water, and possesses a 
 metallic appearance, which disappears in the 
 air. The potassium, by being thus trans- 
 mitted, is converted into potash. From in- 
 direct experiments Sir FI. Davy was inclined 
 to consider barytes as composed of 89.7 ba- 
 rium -|~ 10.3 oxygen = 100. This would 
 make the prime equivalent of barium 8.7, 
 and that of barytes 9.7, compared to that of 
 oxygen 1.0; a determination probably very 
 exact. Dr Clarke of Cambridge, by ex- 
 posing dry nitrate of barytes on charcoal, to 
 the intense heat of the condensed hydroxy- 
 gen flame, observed metallic globules in the 
 midst of the boiling fluid, and the charcoal 
 was found to be studded over with innumer- 
 able globules of a pure metal of the most 
 brilliant lustre and whiteness. On letting 
 these globules fall from the charcoal into 
 w ater, hydrogen w r as evolved in a continued 
 stream. When the globules are plunged in 
 naphtha, they retain their brilliancy but for 
 a few days. 
 
 Barium combines with oxygen in two 
 proportions, forming, 1st, barytes, and 2d, 
 the deutoxide of barium. 
 
 Pure barytes is best obtained by igniting 
 in a covered crucible, the pure crystallized ni- 
 trate of barytes. It is procured in the state 
 of hydrate, by adding caustic potash or soda 
 to a solution of the muriate or nitrate. And 
 barytes, slightly coloured with charcoal, may 
 be obtained by strongly igniting the carbo*. 
 nate and charcoal mixed together in line 
 pow der. Barytes obtained from the ignited 
 nitrate is of a whitish grey colour ; more 
 caustic than strontites, or perhaps even lime. 
 It renders the syrup of violets green, and the 
 infusion of turmeric red. Its specific gravity 
 by Fourcroy is 4. When water in small 
 quantity is poured on the dry earth, it slakes 
 like quicklime, but perhaps with evolution 
 of more heat. When swallowed it acts as a 
 violent poison. It is destitute of smell. 
 
 When pure barytes is exposed, in a porce- 
 lain tube, at a heat verging on ignition, to a 
 stream of dry oxygen gas, it absorbs the gas 
 rapidly, and passes to the state of deutoxide 
 
BAR 
 
 BAR 
 
 of barium. But when it is calcined in con- 
 tact with atmospheric air, we obtain at first 
 this deutoxide and carbonate of barytes ; the 
 former of which passes very slowly into the 
 latter, by absorption of carbonic acid from 
 the atmosphere. 
 
 The deutoxide of barium is of a greenish 
 grey colour, it is caustic, renders the syrup 
 of violets green, and is not decomposable by 
 heat or light. The voltaic pile reduces it. 
 Exposed at a moderate heat to carbonic 
 acid, it absorbs it, emitting oxygen, and be- 
 coming carbonate of barytes, llie deutoxide 
 is probably decomposed by sulphuretted hy- 
 drogen at ordinary temperatures. Aided by 
 heat, almost all combustible bodies, as well 
 as many metals, decompose it. The action of 
 hydrogen is accompanied with remarkable phe- 
 nomena. At about 592° F. the absorption of 
 this gas commences ; but at a heat approach- 
 ing to redness it is exceedingly rapid, attend- 
 ed with luminous jets proceeding from the 
 surface of the deutoxide. Although much 
 water be formed, none of it appears on the 
 sides of the vessel. It is all retained in 
 combination with the protoxide, which in 
 consequence becomes a hydrate, and thus 
 acquires the property of fusing easily. By 
 heating a certain quantity of barytes with an 
 excess of oxygen in a small curved tube 
 standing over mercury, M. Thenard ascer- 
 tained, that in the deutoxide the quantity of 
 the oxygen is the double of that in the pro- 
 toxide. Hence the former will consist of 
 8.7 barium 2 oxygen = 10.7 for its 
 prime equivalent. From the facility with 
 which the protoxide passes into the deutoxide, 
 we may conceive that the former may fre- 
 quently contain a proportion of the latter, to 
 which cause may be ascribed in some degree 
 the discrepancies among chemists, in esti- 
 mating the equivalent of barytes. 
 
 Water at 50° F. dissolves one- twentieth 
 of its weight of barytes, and at 212° about 
 one-half of its weight ; though M. Thenard 
 in a table, has stated it at only one-tenth. As 
 the solution cools, hexagonal prisms, termi- 
 nated at each extremity with a four-sided 
 pyramid, form. These crystals are often 
 attached to one another, so as to imitate the 
 leaves of fern. Sometimes they are deposit- 
 ed in cubes. They contain about 55 per cent 
 of water, or 20 prime proportions. The super- 
 natant liquid is barytes water. It is colour- 
 less, acrid, and caustic. It acts powerfully 
 on the vegetable purples and yellows. Ex- 
 posed to the air, it attracts carbonic acid, and 
 the dissolved barytes is converted into carbo- 
 nate, which falls down in insoluble crusts. 
 It appears from the experiments of M. Ber- 
 thollet, that heat alone cannot deprive the 
 crystallized hydrate of its water. After 
 exposure to a red heat, when it fuses like 
 potash, a proportion of water remains in 
 combination. This quantity is a prime equi- 
 
 valent = 1.12.5, to 9.7 of barytes. The 
 
 ignited hydrate is a solid of a whitish-grey 
 colour, caustic, and very dense. It fuses at 
 a heat a little under a cherry red ; is fix- 
 ed in the fire ; attracts, but slowly, carbonic 
 acid from the atmosphere. It yields carbu- 
 retted hydrogen and carbonate of barytes 
 when heated along with charcoal, provided 
 this be not in excess. 
 
 Sulphur combines with barytes, when they 
 are mixed together, and heated in a crucible. 
 The same compound is more economically 
 obtained by igniting a mixture of sulphate 
 of barytes and charcoal in line powder. This 
 sulphuret is of a reddish-yellow colour, and 
 when dry without smell. When this sub- 
 stance is put into hot water, a powerful ac- 
 tion is manifested. The water is decompos- 
 ed, and two new products are formed, name- 
 ly, hydrosulphuret, and hydroguretted sul- 
 phuret of barytes. The first crystallizes as 
 the liquid cools, the second remains dissolved. 
 The hydrosulphuret is a compound of 9.7 of 
 barytes with 2.125 sulphuretted hydrogen. 
 Its crystals should be quickly separated by 
 filtration, and dried by pressure between the 
 folds of porous paper. They are white 
 scales, have a silky lustre, are soluble 
 in water, and yield a solution having a 
 greenish tinge. Its taste is acrid, sulphu- 
 reous, and when mixed with the hydroguret- 
 ted sulphuret, eminently corrosive. It rapid- 
 ly attracts oxygen from the atmosphere, and 
 is converted into the sulphate of barytes. 
 The hydroguretted sulphuret is a compound 
 of 9.70 barytes with 4.125 bisulphuretted 
 hydrogen ; but contaminated with sulphite 
 and hyposulphite in unknown proportions. 
 The dry sulphuret consists probably of 2 
 sulphur -|- 9.7 barytes. The readiest way 
 of obtaining barytes water is to boil the so- 
 lution of the sulphuret with deutoxide of 
 copper, which seizes the sulphur, while the 
 hydrogen Hies off, and the barytes remains 
 dissolved. 
 
 Phosphuret of barytes may be easily form- 
 ed by exposing the constituents together to 
 heat in a glass tube. Their reciprocal action 
 is so intense as to cause ignition. Like 
 phosphuret of lime, it decomposes water, and 
 causes the disengagement of phosphuretted 
 hydrogen gas, which spontaneously inflames 
 with contact of air. When sulphur is made 
 to act on the deutoxide of barytes, sulphuric 
 acid is formed, which unites to a portion of 
 the earth into a sulphate. 
 
 The salts of barytes are white, and more 
 or less transparent. All the soluble sulphates 
 cause in the soluble salts of barytes, a preci- 
 pitate insoluble in nitric acid. They are all 
 poisonous except the sulphate; and hence 
 the proper counter-poison is dilute sulphuric 
 acid for the carbonate, and sulphate of soda 
 for the soluble salts of barytes. An account 
 has been given of the most useful of these 
 
BAS 
 
 BAS 
 
 salts under the respective acids. What re- 
 mains of any consequence will be found in 
 the table of Sa LTS. For some interesting 
 facts on the decomposition of the sulphate 
 and carbonate, see Attraction. When the 
 object is merely to procure barytes or the 
 sulphuret, form the powdered carbonate or 
 sulphate into a paste with lamp black and 
 coal tar, and subject to strong ignition in a 
 covered crucible.* 
 
 Barradoes Tar. See Petroleum. 
 
 Barilla, or Barillor. The term given 
 in commerce to the impure soda imported 
 from Spain and the Levant. It is made by 
 burning to ashes different plants that grow 
 on the sea-shore, chiefly of the genus sal- 
 sola, and is brought to us in hard porous 
 masses, of a speckled brown colour. 
 
 Kelp, a still more impure alkali made in 
 this country by burning various seaweeds, is 
 sometimes called British barilla. See Soda. 
 
 Barolite. Carbonate of barytes. 
 
 * Barras. The resinous incrustation on 
 the wounds made in fir trees. It is nlso 
 called galipot.* 
 
 Barytes. See Barium. 
 
 * Basalt. Occurs in amorphous mas- 
 
 ses, columnar, amygdaloidal, and vesicular. 
 Its colours are greyish-black, ash-grey, and 
 raven-black. Massive. Dull lustre. Gra- 
 nular structure. Fracture uneven or con- 
 choidal. Concretions; columnar, globular, 
 or tabular. It is opaque, yields to the knife, 
 but not easily frangible. Streak light ash- 
 grey. Sp. grav. 3. Melts into a black 
 
 glass. It is found in beds and veins in 
 
 granite and mica slate, the old red sandstone, 
 limestone, and coal formations. It is distri- 
 buted over the whole world ; but nowhere is 
 met with in greater variety than in Scotland. 
 The German basalt is supposed to be a wa- 
 tery deposit ; and that of France to be of 
 volcanic origin.* 
 
 The most remarkable is the columnar ba- 
 saltes, which forms immense masses, com- 
 posed of columns thirty, forty, or more feet 
 in height, and of enormous thickness. Nay, 
 those at Fairhead are two hundred and fifty 
 feet high. These constitute some of the 
 most astonishing scenes in nature, for the 
 immensity and regularity of their parts. The 
 coast of Antrim in Ireland, for the space of 
 three miles in length, exhibits a very magni- 
 ficent variety of columnar cliffs ; and the 
 Giant’s Causeway consists of a point of that 
 coast formed of similar columns, and pro- 
 jecting into the sea upon a descent for seve- 
 ral hundred feet. These columns are, for 
 the most part, hexagonal, and fit very accu- 
 rately together ; but most frequently not ad- 
 herent to each other, though water cannot 
 penetrate between them. And the basaltic 
 appearances on the Hebrides Islands on the 
 coast of Scotland, as described by Sir Joseph 
 
 Banks, who visited them in 17 72, are upon 
 a scale very striking for their vastness and 
 variety. 
 
 An extensive field of inquiry is here offer- 
 ed to the geological philosopher, in his at- 
 tempts to ascertain the alterations to which 
 the globe has been subjected. The inquiries 
 of the chemist equally co-operate in these 
 researches, and tend likewise to show to 
 what useful purposes this and other substan- 
 ces may be applied. Bergraann found that 
 the component parts of various specimens of 
 basaltes were, at a medium, 52 parts silex, 
 15 alumina, 8 carbonate of lime, and 25 
 iron. The differences seem, however, to be 
 considerable ; for Faujas de St Fond gives 
 these proportions: 46 silex, 50 alumina, 10 
 lime, 6 magnesia, and 8 iron. The amor- 
 phous basaltes, known by the name of row- 
 ley rag, the ferrilite of Kirwan, of the speci- 
 fic gravity of 2.748, afforded Dr Withering 
 47.5 of silex, 32.5 of alumina, and 20 of iron, 
 at a very low degree of oxidation probably. 
 Dr Kennedy, in his analysis of the basaltes 
 of Staffa, gives the following as its compo- 
 nent parts : silex 48, alumina 16, oxide of 
 iron 1 6, lime 9, soda 4, muriatic acid 1 , wa- 
 ter and volatile parts 5. Klaproth gives for 
 the analysis of the prismatic basaltes of Ila- 
 senberg : silex 44.5, alumina 16-75, oxide 
 of iron 20, lime 9.5, magnesia 2.25, oxide of 
 manganese 0.12, soda 2.60, water 2. On a 
 subsequent analysis, with a view to detect 
 the existence of muriatic acid, he found 
 slight indications of it, but it was in an ex- 
 tremely minute proportion. 
 
 * Sir James Hall and Mr Gregory Watt 
 have both proved, by admirably conducted 
 experiments, that basalt when fused into a 
 perfect glass will resume the stony structure 
 by slow r cooling; and hence have endeavour, 
 ed to shew, that the earthy structure affords 
 no argument against the igneous formation 
 of basalt in the terrestrial globe.* 
 
 Basaltes, when calcined and pulverized, is 
 said to be a good substitute for puzzolana 
 in the composition of mortar, giving it the 
 property of hardening under water. Wine 
 bottles have likewise been manufactured 
 with it, but there appears to be some nicety 
 requisite in the management to ensure suc- 
 cess. Mr Castelveil, who heated his furnace 
 with w r ood, added soda to the basaltes to 
 render it more fusible ; while Mr Giral, who 
 used pit coal, found it necessary to mix with 
 his basaltes a very refractory sand. The best 
 mode probably would be to choose basaltes 
 of a close fine grain and uniform texture, 
 and to employ it alone, taking care to regu- 
 late the heat properly ; for if this be carried 
 too high, it will drop from the iron almost 
 like water. 
 
 * Basaltic Hornblende. It usually 
 occurs in opaque six-sided single crystals, 
 
 47 
 
BDE 
 
 BEE 
 
 which sometimes act on the magnetic needle. 
 It is imbedded in basalt or wacke. Colour 
 velvet black. Lustre vitreous. Scratches 
 glass. Sp. gr. 3 .‘25. Fuses with difficulty 
 into a black glass. It consists of 47 silica, 
 526 alumina, 8 lime, 2 magnesia, 15 iron, 
 and 0.5 water. It is found in the basalt of 
 Arthur’s Seat, in that of Fifeshirc, and in 
 the Isles of Mull, Canna, Eigg, and Sky. 
 It is found also in the basaltic and floetz 
 trap rocks of England, Ireland, Saxony, 
 Bohemia, Silesia, Bavaria, Hungary, Spain, 
 Italy, and Prance.* 
 
 * Basanite. See Flinty Slate.* 
 
 * Base or Basis. A chemical term usu- 
 ally applied to alkalis, earths, and metallic 
 oxides, in their relations to the acids and 
 salts. It is sometimes also applied to the 
 particular constituents of an acid or oxide, 
 on the supposition that the substance com- 
 bined with the oxygen, &c. is the basis of 
 the compound to which it owes its particular 
 qualities. This notion seems unphilosophi- 
 cal, as these qualities depend as much on 
 the state of combination as on the nature of 
 the constituent.* 
 
 Bath. The heat communicated from 
 bodies in combustion must necessarily vary 
 according to circumstances ; and this varia- 
 tion not only influences the results of opera- 
 tions, but in many instances endangers the 
 vessels, especially if they be made of glass. 
 Among the several methods of obviating this 
 inconvenience, one of the most usual consists 
 in interposing a quantity of sand, or other 
 matter, between the fire and the vessel in- 
 tended to be heated. The sand bath and 
 the water bath are most commonly used ; 
 the latter of which was called Balneum Ma- 
 rias by the elder chemists. A bath of steam 
 may, in some instances, be found preferable 
 to the water bath. Some chemists have pro- 
 posed baths of melted lead, of tin, and of 
 other fusible substances. These may per- 
 haps be found advantageous in a few peculiar 
 operations, in which the intelligent operator 
 must indeed be left to his own sagacity. 
 
 * A considerably greater heat may be 
 given to the water bath by dissolving various 
 salts in it. Thus a saturated solution of 
 common salt boils at 22 5°.3, or 13°.3 Fahr. 
 above the boiling point of water. By using 
 solution of muriate of lime, a bath of any 
 temperature from 212 to 252° may be con- 
 veniently obtained.* 
 
 Bdellium. A gum resin, supposed to 
 be of African origin. The best bdellium is 
 of a yellowish brown, or dark brown colour, 
 according to its age ; unctuous to the touch, 
 brittle, but soon softening, and growing 
 tough betwixt the fingers; in some degree 
 transparent, not unlike myrrh ; of a bitterish 
 taste, and a moderately strong smell. It 
 does not easily take flame, and, when set on 
 fire, soon goes out. In burning it sputters a 
 
 little, owing to its aqueous humidity. * Its 
 sp. grav. is 1.371. Alcohol dissolves about 
 three-fifths of bdellium, leaving a mixture of 
 gum and ccrasin. Its constituents, according 
 to Pelletier, are 59 resin, 9.2 gum, 30.6 
 cerasin, 1.2 volatile oil and loss.* 
 
 * Beak. The seed of the vicia faba, a 
 small esculent bean, which becomes black as 
 it ripens, has been analyzed by Einholf. He 
 found 3840 parts to consist of 600 volatile 
 matter, 386 skins, 610 fibrous starchy mat- 
 ter, 1312 starch, 417 vegeto-animal matter, 
 31 albumen, 156 extractive, soluble in alco- 
 hol, 177 gummy matter, 37£ earthy phos- 
 phate, 133£ loss. Fourcroy and Vauquelin 
 found its incinerated ashes to contain the 
 phosphates of lime, magnesia, potash, and 
 iron, with uncombined potash. They found 
 no sugar in this bean. Kidney beans, the 
 seeds of the phaseolus vulgaris , yielded to 
 Einholf 288 skins, 425 fibrous starchy mat- 
 ter, 1380 starch, 799 vegeto-animal matter, 
 not quite free from starch, 131 extractive, 
 52 albumen, with some vegeto-animal mat- 
 ter, 744 mucilage, and 21 loss in 3840.* 
 
 * Bee. The venom of the bee according to 
 Fontana, bears a close resemblance to that 
 of the viper. It is contained in a small 
 vesicle, and has a hot and acrid taste, like 
 that of the scorpion.* 
 
 Beer is the w r ine of grain. Malt is usu- 
 ally made of barley. The grain is steeped 
 for two or three days in w 7 ater until it swells, 
 becomes somewhat tender, and tinges the 
 water of a bright reddish brown colour. The 
 water being then drained away, the barley is 
 spread about two feet thick upon a floor, 
 where it heats spontaneously, and begins to 
 grow, by first shooting out the radicle. In 
 this state the germination is stopped by 
 spreading it thinner, and turning it over for 
 two days ; after which it is again made into 
 a heap, and suffered to become sensibly hot, 
 which usually happens in little more than 
 a day. Lastly, it is conveyed to the kiln, 
 where, by a gradual and low heat, it is ren- 
 dered dry and crisp. This is malt ; and its 
 qualities differ according as it is more or less 
 soaked, drained, germinated, dried, and bak- 
 ed. In this, as in other manufactories, the 
 intelligent operators often make a mystery 
 of their processes from views of profit; and 
 others pretend to peculiar secrets who really 
 possess none. 
 
 Indian corn, and probably all large grain, 
 requires to be suffered to grow into the 
 blade, as well as root, before it is fit to be 
 made into malt. For this purpose it is 
 buried about two or three inches deep in 
 the ground, and covered with loose earth ; 
 and in ten or twelve days it springs up. In 
 this state it is taken up and washed, or 
 fanned, to clear it from its dirt ; and then 
 dried in the kiln for use. ^ 
 
 * Barley, by being converted into malt, be- 
 
ATT 
 
 ATT 
 
 comes one- fifth lighter, or 20 per cent; 12 
 of which are owing to kiln drying, 1.5 are 
 carried off by the steep- water, 3 dissipated on 
 the floor, 5 lost in cleaning the roots, and 
 0.5 waste or loss. * 
 
 1 he degree of heat to which the malt is 
 exposed in this process, gradually changes 
 its colour from very pale to actual blackness, 
 as it simply dries it, or converts it to char- 
 coal. 
 
 Tile colour of the malt not only affects 
 the colour of the liquor brewed from it ; 
 but, in consequence of the chemical opera- 
 tion, of the heat applied, on the principles 
 that are developed in the grain during the 
 process of malting, materially alters the qua- 
 lity of the beer, especially with regard to the 
 properties of becoming fit for drinking and 
 growing fine. 
 
 Beer is made from malt previously ground, 
 or cut to pieces by a mill. This is placed 
 in a tun, or tub with a false bottom; hot 
 water is poured upon it, and the whole 
 stirred about with a proper instrument. The 
 temperature of the water in this operation, 
 . called Mashing, must not be equal to boil- 
 ing; for, in that case, the malt would be 
 converted into a paste, from which the im- 
 pregnated water could not be separated. 
 This is called Setting. After the infusion 
 has remained for some time upon the malt, 
 it is drawn off, and is then distinguished by 
 the name of Sweet Wort. By one or more 
 subsequent infusions of water, a quantity of 
 weaker w^ort is made, which is either added 
 to the foregoing, or kept apart, according 
 to the intention of the operator. The wort 
 is then boiled with hops, which gives it an 
 aromatic bitter taste, and is supposed to 
 render it less liable to be spoiled in keeping ; 
 after which it is cooled in shallow vessels, 
 and suffered to ferment, with the addition 
 of a proper quantity of yeast. The ferment- 
 ed liquor is beer; and differs greatly in its 
 quality, according to the nature of the grain, 
 the malting, the mashing, the quantity and 
 kind of the hops and the yeast, the purity 
 or admixtures of the w r ater made use of, 
 the temperature and vicissitudes of the wea- 
 ther, &c. 
 
 Beside the various qualities of malt liquors 
 of a similar kind, there are certain leading 
 features by which they are distinguished, and 
 classed under different names, and to pro- 
 duce which, different modes of management 
 must be pursued.. T he principal distinctions 
 are into beer, properly so called ; ale ; table 
 or small beer; and porter, which is com- 
 monly termed beer in London. Beer is a 
 strong, fine, and thin liquor; the greater 
 part of the mucilage having been separated 
 by boiling the wort longer than for ale, and 
 carrying the fermentation farther, so as to 
 convert the saccharine matter into alcohol. 
 Ale is of a more sirupy consistence, and 
 
 sw’ceter taste ; more of the mucilage being 
 retained in it, and the fermentation not hav- 
 ing been carried so far as to decompose all 
 the sugar. Small beer, as its name implies, 
 is a w'eakcr liquor ; and is made, either by 
 adding a large portion of water to the malt, 
 or by mashing with a fresli quantity of water 
 what is left after the beer or ale wort is 
 drawn off. Porter was probably made ori- 
 ginally from very high dried malt ; but it is 
 said, that its peculiar flavour cannot be im- 
 parted by malt and hops alone. 
 
 * Mr Brande obtained the following quan- 
 tities of alcohol from 100 parts of different 
 species of beers. Burton ale, 8.88, Edin- 
 burgh ale, 6. 2, Dorchester ale, 5.56; the 
 average being = 6.8 7. Brown stout, 6.8, 
 London porter (average) 4.2, London small 
 beer, (average) 1.28.* 
 
 As long ago as the reign of Queen Anne, 
 brewers were forbid to mix sugar, honey, Gui- 
 nea pepper, essentia bina, cocculus indicus, or 
 any other unwholesome ingredient, in beer, 
 under a certain penalty; from which we 
 may infer, that such at least w as the practice 
 of some ; and writers, w ho profess to discuss 
 the secrets of the trade, mention most of 
 these and some other articles as essentially 
 necessary. The essentia bina is sugar boiled 
 down to a dark colour, and empyreumatio 
 flavour. Broom tops, wormwood, and other 
 bitter plants, were formerly used to render 
 beer fit for keeping, before hops w ere intro- 
 duced into this country ; but are now prohi- 
 bited to be used in beer made for sale. 
 
 * By the present law of this country, nothing 
 is allowed to enter into the composition of 
 beer, except malt and hops. Quassia and 
 wormwood are often fraudulently introduced ; 
 both of which are easily discoverable by their 
 nauseous bitter taste. They form a beer 
 which does not preserve so well as hop beer. 
 Sulphate of iron, alum, and salt, are often 
 added by the publicans, under the name of 
 beer-heacling , to impart a frothing property 
 to beer, when it is poured out of one vessel 
 into another. Molasses and extract of gentian 
 root are added with the same view. Capsi- 
 cum, grains of paradise, ginger root, corian- 
 der seed, and orange peel, are also employed 
 to give pungency and flavour to w eak or had 
 beer. The following is a list of some of the 
 unlawful substances seized at different brew- 
 eries, and brewers’ druggists’ laboratories, in 
 London, as copied from the minutes of the 
 committee of the House of Commons. Coc- 
 culus indicus, multum, (an extract of the 
 cocculus), colouring, honey, hartshorn shav- 
 ings, Spanish juice, orange powder, ginger, 
 grains of paradise, quassia, liquorice, cara- 
 way seeds, copperas, capsicum, mixed drugs. 
 Sulphuric acid is very frequently added to 
 bring beer forward, or make it hard, giving 
 new beer instantly the taste of what is 18 
 months old. According to Mr Accuua, the 
 
DEN 
 
 BEIt 
 
 present entire beer of the London brewer is 
 composed of all the waste and spoiled beer 
 of the publicans, the bottoms of butts, the 
 leavings of the pots, the drippings of the 
 machines for drawing the beer, the remnants 
 of beer that lay in the leaden pipes of the 
 brewery, with a portion of brown stout, bot- 
 tling beer, and mild beer. He says that 
 opium, tobacco, nux vomica, and extract of 
 poppies, have likewise been used to adulter- 
 ate beer. For an account of the poisonous 
 qualities of the coccvlus indicus, see Picro- 
 toxia; and for those of nux vomica, see 
 Strychnia. By evaporating a portion of 
 beer to dryness, and igniting the residuum 
 with chlorate of potash, the iron of the cop- 
 peras will be procured in an insoluble oxide. 
 Muriate of barytes will throw down an abun- 
 dant precipitate from beer contaminated with 
 sulphuric acid or copperas, which precipitate 
 may be collected, dried, and ignited. It will 
 be insoluble in nitric acid.* 
 
 Beer appears to have been of ancient use, 
 as Tacitus mentions it among the Germans, 
 and has been usually supposed to have been 
 peculiar to the northern nations', but the 
 ancient Egyptians, whose country was not 
 adapted to the culture of the grape, had also 
 contrived this substitute for wine ; and Mr 
 Park has found the art of making malt, and 
 brewing from it very good beer, among the 
 negroes in the interior parts of Africa. 
 
 Beet. The root of the beet affords a con- 
 siderable quantity of sugar, and has lately 
 been cultivated for the purpose of extracting 
 it to some extent in Germany. See Sugar. 
 It is likewise said, that if beet roots be dried 
 in the same manner as malt, after the great- 
 er part of their juice is pressed out, very good 
 beer may be made from them. 
 
 * Bellmetal. Sec Copper.* 
 
 * Bellmetal Ore. See Ores of Tin.* 
 
 Ben (Oil of). This is obtained from the 
 
 ben nut, by simple pressure. It is remark- 
 able for its not growing rancid in keeping, 
 or at least not until it has stood for a num- 
 ber of years ; and on this account it is used 
 in extracting the aromatic principle of such 
 odoriferous flowers as yield little or no essen- 
 tial oil in distillation. 
 
 * Benzoic Acid. See Acid (Benzoic).* 
 
 Benzoin or Benjamin. The tree which 
 
 produces Benzoin is a native of the East In- 
 rlies, particularly of the island Siam and 
 Sumatra. j- The juice exudes from incisions, 
 in the form of a thick white balsam. If col- 
 lected as soon as it has grown somewhat 
 solid, it proves internally white like almond, 
 and hence it is called Benzoe Amygdaloides : 
 if suffered to lie long exposed to the sun 
 and air, it changes more and more to a 
 brownish, and at last to a quite reddish 
 brown colour. 
 
 •f Consult the Philosophical Transactions, vol. 
 ixxvn. page 307. for a botanical description and draw- 
 ing of tfie tree, by Dryander, 
 
 This resin is moderately hard and brittle, 
 and yields an agreeable smell when rubbed 
 or warmed. When chewed, it impresses a 
 slight sweetness on the palate. It is totally 
 soluble in alcohol ; from which, like other 
 resins, it may be precipitated by the addition 
 of water. Its specific gravity is 1.092. 
 
 The white opaque fluid thus obtained has 
 been called Lac Virginale ; and is still sold, 
 with other fragrant additions, by perfumers, 
 as a cosmetic. Boiling water separates the 
 peculiar acid of benzoin. 
 
 The products Mr Brande obtained by 
 distillation were, from a hundred grains, 
 benzoic acid 9 grains, acidulated water 5.5, 
 butyraceous and empyreumatic oil 60, brittle 
 coal 22, and a mixture of carburetted hydro- 
 gen and carbonic acid gas, computed at 3.5. 
 On treating the empyreumatic oil with water, 
 however, 5 grains more of acid were extract- 
 ed, making 14 in the whole. 
 
 * From 1 500 grains of benzoin, Bucholz 
 obtained 1250 of resin, 187 benzoic acid, 25 
 of a substance similar to balsam of Peru, 8 
 of an aromatic substance soluble in water 
 and alcohol, and 30 of woody fibres and im- 
 purities. 
 
 Ether, sulphuric, and acetic acids, dissolve 
 benzoin ; so do solutions of potash and soda. 
 Nitric acid acts violently on it, and a portion 
 of artificial tannin is formed. Ammonia 
 dissolves it sparingly.* 
 
 * Bergmannite. A massive mineral of a 
 greenish, greyish-white, or reddish colour. 
 Lustre intermediate between pearly and re- 
 sinous. Fracture fibrous, passing into fine 
 grained, uneven. Slightly translucent on 
 the edges. Scratches felspar. Fuses into a 
 transparent glass, or a semi-transparent ena- 
 mel. It is found at FVederickswarn in Nor- 
 way, in quartz and in felspar.* 
 
 * Beryl. This precious mineral is most 
 commonly green, of various shades, passing 
 into honey-yellow, and sky-blue. It is crys- 
 tallized in hexahedral prisms deeply striated 
 longitudinally, or in 6 or 12 sided prisms, 
 terminated by a 6 sided pyramid, whose 
 summit is replaced. It is harder than the 
 emerald, hut more readily yields to cleavage. 
 Its sp. grav. is 2.7. Its lustre is vitreous. 
 It is transparent, and sometimes only trans- 
 lucent. It consists by Vauquelin of 68 sili- 
 ca, 15 alumina, 14 glucina, 1 oxide of iron, 
 2 lime. Berzelius found in it a trace of 
 oxide of tantalum. It occurs in veins tra- 
 versing granite in Daouria ; in the Altaic 
 chain in Siberia; near Limoges in France; 
 in Saxony; Brazil; at Kinloch Raimoch, 
 and Cairngorm, Aberdeenshire, Scotland ; 
 above Dundrum, in the county of Dublin, 
 and near Cronehane, county of Wicklow, in 
 Ireland. It differs from emerald in hard- 
 ness and colour. It lias been called aqua 
 marine, and greenish-yellow emerald. It is 
 electric by friction and not by heat.* 
 
BIL 
 
 BIL 
 
 * Bezoaiu This name, which is derived 
 irom a Persian word implying an antidote 
 to poison, was given to a concretion found 
 in the stomach of an animal of the goat kind, 
 which was once very highly valued for this 
 imaginary quality, and has thence been ex- 
 tended to all concretions found in animals. 
 
 These are of eight kinds, according to 
 bourcroy, Vauquelin, and Berthollet. 1. 
 Superphosphate of lime, which forms con- 
 cretions in the intestines of many mammalia. 
 2. Phosphate of magnesia, semi-transparent 
 and yellowish, and of sp. grav. 2.160. 3. 
 
 Phosphate of ammonia and magnesia. A 
 concretion of a grey or brown colour, com- 
 posed of radiations from a centre. It is 
 found in the intestines of herbiverous ani- 
 mals, the elephant, horse, &c. 4. Biliary, 
 
 colour reddish-brown, found frequently in 
 the intestines and gall bladder of oxen, and 
 used by painters for an orange-yellow pig- 
 ment. It is inspissated bile. 5. Resinous. 
 The oriental bezoars, procured from unknown 
 animals, belong to this class of concretions. 
 They consist of concentric layers, are fusi- 
 ble, combustible, smooth, soft, and finely 
 polished. They are composed of bile and 
 resin. 6. Fungous, consisting of pieces of 
 the boletus igniarius, swallowed by the 
 animal. 7. Hairy. 8. Ligniform. Three 
 bezoars sent to Bonaparte by the king of 
 Persia, were found by Berthollet to be no- 
 thing but woody fibre agglomerated.* 
 
 BrHYDROGURET of Carbon. See Carbu- 
 retted Hydrogen. 
 
 Bihydroguret of Phosphorus. See 
 Phosphu retted Hydrogen. 
 
 * Bildstein, Agalmatolite, or Figure- 
 stone. A massive mineral, with sometimes 
 an imperfectly slaty structure. Colour 
 gray, brown, flesh red, and sometimes spot- 
 ted, or with blue veins. It is translucent on 
 the edges, unctuous to the touch, and yields 
 to the nail. Sp. grav. 2.8. It is composed 
 of 56 silica, 29 alumina, 7 potash, 2 lime, 1 
 oxide of iron, and 5 water, by Vauquelin. 
 Klaproth found in a specimen from China, 
 54.5 silica, 34 alumina, 6.25 potash, 0.75 
 oxide of iron, and 4 water. It fuses into a 
 transparent glass. M. Brogniart calls it 
 steatite pagodite , from its coming from China 
 cut into grotesque figures. It wants the 
 magnesia, which is a constant ingredient of 
 steatites. It is found at Nay gag in Transyl- 
 vania, and Glyder-bach in Wales. 
 
 * Bile. A bitter liquid, of a yellowish or 
 greenish yellow colour, more or less viscid, 
 of a sp. gravity greater than that of water, 
 common to a great number of animals, the 
 peculiar secretion of their liver. It is the 
 prevailing opinion of physiologists, that the 
 bile is separated from the venous, and not 
 like the other secretions, from the arterial 
 blood. The veins which receive the blood 
 distributed to the abdominal viscera, unite 
 
 into a large trunk called the vena porta, 
 which divides into two branches, that pene- 
 trate into the liver, and divide into innumer- 
 able ramifications. The last of these termi- 
 nate partly in the biliary ducts, and partly in 
 the hepatic veins, -which restore to the cir- 
 culation the blood not needed for the form- 
 ation of bile. This liquid passes directly 
 into the duodenum by the ductus choledocus , 
 when the animal has no gall bladder ; but 
 when it has one, as more frequently happens, 
 the bile flows back into it by the cystic duct, 
 and remaining there for a longer or shorter 
 time, experiences remarkable alterations. Its 
 principal use seems to be, to promote the 
 duodenal digestion, in concert with the pan- 
 creatic juice. 
 
 Boerhaave, by an extravagant error, re- 
 garded the bile as one of the most putresci- 
 ble fluids ; and hence originated many hypo- 
 thetical and absurd theories on diseases and 
 their treatment. We shall follow the ar- 
 rangement of M. Thenard, in a subject 
 which owes to him its chief illustration. 
 
 1. Ox bile is usually of a greenish-yellow 
 colour, rarely a deep green. By its colour 
 it changes the blue of turnsole and violet to 
 a reddish-yellow. At once very bitter, and 
 slightly sweet, its taste is scarcely support- 
 able. Its smell, though feeble, is easy to 
 recognize, and approaches somewhat to the 
 nauseous odour of certain fatty matters when 
 they are heated. Its specific gravity varies 
 very little. It is about 1.026 at 43° F. 
 It is sometimes limpid, and at others dis- 
 turbed with a yellow matter, from which it 
 may be easily separated by water : its con- 
 sistence varies from that of a thin mucilage, 
 to viscidity. Cadet regarded it as a kind of 
 soap. This opinion was first refuted by M. 
 Thenard. According to this able chemist, 
 100 parts of ox bile, are composed of 700 
 water, 15 resinous matter, 69 picromel, about 
 4 of a yellow matter, 4 of soda, 2 phosphate 
 of soda, 5.5 muriates of soda and potash, 0.8 
 sulphate of soda, 1.2 phosphate of lime, and 
 a trace of oxide of iron. When distilled to 
 dryness, it leaves from 1 - 8 tli to l-9th of 
 solid matter, which, urged with a higher 
 heat, is resolved into the usual igneous pro- 
 ducts of animal analysis ; only with moie 
 oil and less carbonate of ammonia. 
 
 Exposed for some time in an open vessel, 
 the bile gradually corrupts, and lets fall a 
 small quantity of a yellowish matter ; then 
 its mucilage decomposes. Thus the putre- 
 factive process is very inactive, and the odour 
 it exhales is not insupportable, but in some 
 cases has been thought to resemble that of 
 musk. Water and alcohol combine in all 
 proportions with bile. AY hen a very little 
 acid is poured into bile, it becomes slightly 
 turbid, and reddens litmus ; when more is 
 added, the precipitate augments, particularly 
 if sulphuric acid be employed. It is formed 
 
BIR 
 
 BIS 
 
 of a yellow animal matter, with very little 
 resin. Potash and soda increase the thin- 
 ness and transparency of bile. Acetate of 
 lead precipitates the yellow matter, and the 
 sulphuric and phosphoric acids of the bile. 
 The solution of the subacetate precipitates 
 not only these bodies, but also the picromel 
 and the muriatic acid, all combined with the 
 oxide of lead. The acetic acid remains in 
 the liquid united to the soda. The greater 
 number of fatty substances are capable of 
 being dissolved by bile. This property, 
 which made it be considered a soap, is ow- 
 ing to the soda, and to the triple compound 
 of soda, resin, and picromel. Scourers 
 sometimes prefer it to soap, for cleansing 
 woollen. The bile of the calf, the dog, and 
 the sheep, are similar to that of the ox. 
 The bile of the sow contains no picromel. 
 It is merely a soda- resinous soap. Hu- 
 man bile is peculiar. It varies in colour, 
 sometimes being green, generally yellowish- 
 brown, occasionally almost colourless. Its 
 taste is not very bitter. In the gall bladder 
 it is seldom limpid, containing often, like 
 that of the ox, a certain quantity of yellow r 
 matter in suspension. At times this is in 
 such quantity, as to render the bile somewhat 
 grumous. Filtered and boiled, it becomes 
 very turbid, and diffuses the odour of white 
 of egg. When evaporated to dryness, there 
 results a brown extract, equal in weight to 
 1-1 1th of the bile. I3v calcination we obtain 
 the same salts as from ox bile. 
 
 All the acids decompose human bile, and 
 occasion an abundant precipitate of albumen 
 and resin, which are easily separable by alco- 
 hol. One part of nitric acid, sp. grav. 1.210, 
 saturates 100 of bile. On pouring into it a 
 solution of sugar of lead, it is changed into 
 a liquid of a light yellow colour, in which 
 no picromel can be found, and which con- 
 tains only acetate of soda and some traces of 
 animal matter. Human bile appears hence 
 to be formed, by Thenard, in 1100 parts; of 
 1000 water; from 2 to 10 yellow insoluble 
 matter; 42 albumen; 41 resin; 5.6 soda; 
 and 45 phosphates of soda and lime, sul- 
 phate of soda, muriate of soda and oxide of 
 iron. But by Berzelius, its constituents are 
 in 1000 parts: 908.4 water; 80 picromel; 
 3 albumen; 4.1 soda; 0.1 phosphate of 
 lime; 3.4 common salt, and 1. phosphate of 
 soda, with some phosphate of lime.* 
 
 Birdlime. The best birdlime is made of 
 the middle bark of the holly, boiled seven or 
 eight hours in water, till it is soft and ten- 
 der; then laid in heaps in pits in the ground 
 and covered with stones, the water being 
 previously drained from it ; and in this state 
 left for two or three weeks to ferment till it 
 is reduced to a kind of mucilage. This be- 
 ing taken from the pit is pounded in a mor- 
 tar to a paste, washed in river water, and 
 >. Beaded, till it h freed from extraneous mat- 
 
 ters. In this state it is left four or five days 
 in earthen vessels, to ferment and purify it- 
 self, when it is fit for use. 
 
 It may likewise be obtained from the 
 mistleto, the viburnum lantana, young shoots 
 of elder, and other vegetable substances. 
 
 It is sometimes adulterated with turpen- 
 tine, oil, vinegar, and other matters. 
 
 Good birdlime is of a greenish colour, 
 and sour flavour ; gluey, stringy, and tena- 
 cious; and in smell resembling linseed oil. 
 By exposure to the air it becomes dry and 
 brittle, so that it may be powdered ; but its 
 viscidity is restored by wetting it. It red- 
 dens tincture of litmus. Exposed to a gen- 
 tle heat it liquefies slightly, swells in 
 bubbles, becomes grumous, emits a smell 
 resembling that of animal oils, grows brown, 
 but recovers its properties on cooling, if not 
 heated too much. With a greater heat it 
 burns, giving out a brisk flame and much 
 smoke. The residuum contains sulphate 
 and muriate of potash, carbonate of lime 
 and alumina, with a small portion of iron. 
 
 Bismuth is a metal of a yellowish or 
 reddish- white colour, little subject to change 
 in the air. It is somewhat harder than lead, 
 and is scarcely, if at all, malleable ; being 
 easily broken, and even reduced to powder, 
 by the hammer. The internal face, or place 
 of fracture, exhibits large shining plates, 
 disposed in a variety of positions ; thin 
 pieces are considerably sonorous. At a tem- 
 perature of 480° Fahrenheit, it melts; and 
 its surface becomes covered with a greenish- 
 gray, or brown oxide. A stronger heat ig- 
 nites it, and causes it to burn with a small 
 blue flame ; at the same time that a yellow- 
 ish oxide, known by the name of flowers of 
 bismuth, is driven up. This oxide appears 
 to rise in consequence of the combustion ; 
 for it is very fixed, and runs into a greenish 
 glass when exposed to heat alone. 
 
 * This oxide consists of 100 metal + 
 
 1 1.275 oxygen, whence its prime equivalent 
 will be 9.87, and that of the metal itself 
 8.87. The specific gravity of the metal is 
 9.85.* 
 
 Bismuth urged by a strong heat in a 
 closed vessel, sublimes entire, and crystal- 
 lizes very distinctly when gradually cool- 
 ed. 
 
 The sulphuric acid has a slight action up- 
 on bismuth, when it is concentrated and 
 boiling. Sulphurous acid gas is exhaled, 
 and part of the bismuth is converted into a 
 white oxide. A small portion combines 
 with the sulphuric acid, and affords a deli- 
 quescent salt in the form of small needles. 
 
 The nitric acid dissolves bismuth with 
 the greatest rapidity and violence; at the 
 same time that much heat is extricated, and 
 a large quantity of nitric oxide escapes. The 
 solution, when saturated, affords crystals as 
 it cools; the salt detonates weakly, and 
 
 w • 
 
 
BIS 
 
 leaves a yellow oxide behind, which ef- 
 floresces in the air. Upon dissolving this 
 salt in water, it renders that fluid of a milky 
 white, and lets fall an oxide of the same 
 colour. 
 
 l’he nitric solution of bismuth exhibits 
 the same property when diluted with wa- 
 ter, most of the metal falling down in the 
 form of a white oxide, called magistery of 
 bismuth. This precipitation of the nitric 
 solution, by the addition of water, is the cri- 
 terion by which bismuth is distinguished 
 from most other metals. The magistery or 
 oxide is a very white and subtile powder : 
 when prepared by the addition of a large 
 quantity of water, it is used as a paint for 
 the complexion, and is thought gradually to 
 impair the skin. The liberal use of any 
 paint for the skin seems indeed likely to do 
 this ; but there is reason to suspect, from the 
 resemblance between the general properties 
 of lead and bismuth, that the oxide of this 
 metal may be attended with effects similar to 
 those which the oxides of lead are known to 
 produce. If a small portion of muriatic acid 
 be mixed with the nitric, and the precipitat- 
 ed oxide be washed with but a small quanti- 
 ty of cold water, it will appear in minute 
 scales of a pearly lustre, constituting the 
 pearl powder of perfumers. These paints are 
 liable to be turned black by sulphuretted hy- 
 drogen gas. 
 
 The muriatic acid does not readily act 
 upon bismuth. 
 
 * When bismuth is exposed to chlorine 
 <ras it takes fire, and is converted into a chlo>- 
 ride, which, formerly prepared by heating the 
 metal with corrosive sublimate, was called 
 butter of bismuth. The chloride is of a grey- 
 ish-white colour, a granular texture, and is 
 opaque. It is fixed at a red heat. Accord- 
 ing to Dr John Davy, it is composed of 33.6 
 chlorine, + 66.4 bismuth, = 100; or in 
 equivalent numbers, of 4.45 chlorine, 
 8.87 bismuth, = 15.52. When iodine and 
 bismuth are heated together, they readily 
 form an iodide of an orange yellow colour, 
 insoluble in water, but easily dissolved in 
 potash ley.* 
 
 Alkalis likewise precipitate its oxide; hut 
 not of so beautiful a white colour as that 
 afforded by the affusion of pure water. 
 
 The gallic acid precipitates bismuth of a 
 greenish yellow, as ferroprussiate of potash 
 does of a yellowish colour. 
 
 * There appears (o be two sulphurets, the 
 first a compound of 100 bismuth to 22.34 
 sulphur; the second of 100 to 46.5; the 
 second is a bisulphuret.* 
 
 This metal unites with most metallic sub- 
 stances, and renders them in general more 
 fusible. When calcined with the imperfect 
 metals, its glass dissolves them, and produces 
 the same effect as lead in cupellation; in 
 
 BIT 
 
 which process it is even said to be preferable 
 to lead. 
 
 Bismuth is used in the composition of 
 pewter, in the fabrication of printers’ types, 
 and in various other metallic mixtures. With 
 an equal weight of lead, it forms a brilliant 
 white alloy, much harder than lead, and 
 more malleable than bismuth, though not 
 ductile ; and if the proportion of lead be in- 
 creased, it is rendered still more malleable. 
 Eight parts of bismuth, five of lead, and 
 three of tin, constitute the fusible metal, 
 sometimes called Newton’s, from its disco- 
 verer, which melts at the heat of boiling 
 
 water, and may be fused over a candle in 
 ¥ 
 
 a piece of stiff paper without burning the 
 paper. One part of bismuth, with five of 
 lead, and three of tin, forms plumbers’ sol- 
 der. It forms the basis of a sympathetic ink. 
 The oxide of bismuth precipitated by potash 
 from nitric acid, has been recommended in 
 spasmodic disorders of the stomach, and 
 given in doses of four grains four times a- 
 day. A writer in the Jena Journal says he 
 has known the dose carried gradually to 
 one scruple without injury. 
 
 Bismuth is easily separable, in the dry 
 way, from its ores, on account of its great 
 fusibility. It is usual, in the processes at 
 large, to throw the bismuth ore into a fire 
 of wood ; beneath which a hole is made in 
 the ground to receive the metal, and de- 
 fend it from oxidation. The same process 
 may be imitated in the small way, in the 
 examination of the ores of this metal ; no- 
 thing more being necessary, than to expose 
 it to a moderate heat in a crucible, with a 
 quantity of reducing flux ; taking care, at 
 the same time, to perform the operation as 
 speedily as possible, that the bismuth may 
 be neither oxidized nor volatilized. 
 
 Bi stiie. A brown pigment, consisting 
 of the finer parts of w'ood soot, separated 
 from the grosser by washing. The soot of 
 the beech is said to make the best. 
 
 * Bitter Principle, of which there are 
 several varieties. 
 
 When nitric acid is digested on silk, indi- 
 go, or white w illow, a substance of a deep 
 yellow colour, and an intensely bitter taste, is 
 formed. It dyes a permanent ycllow r . It 
 crystallizes, in oblong plates, and saturates al- 
 kalis, like an acid, producing crystallizable 
 salts. That with potash, is in yellow prisms. 
 They are bitter, permanent in the air, and 
 less soluble than the insulated bitter princi- 
 ple. On hot charcoal they deflagrate. When 
 struck smartly on an anvil, they detonate 
 with much violence, and with emission of a 
 purple light. Ammonia deepens the colour 
 of the bitter principle solution, and forms a 
 salt in yellow spicula;. It unites also with 
 the alkaline earths and metallic oxides. 31. 
 Chevreul considers it a compound of nitric 
 
BIT 
 
 BLE 
 
 acid, with a peculiar substance of an oily na- 
 ture. Quassia, cocculus Indicus, daphne, Al- 
 pina, coffee, squills, colocynth, and bryony, 
 ,as well as many other medicinal })lants, 
 yield bitter principles, peculiarly modified.* 
 
 Bittern. The mother water which re- 
 mains after the crystallization of common 
 salt in sea water, or the water of salt springs. 
 It abounds with sulphate and muriate of 
 magnesia, to which its bitterness is owing. 
 See Water (Sea). 
 
 * Bitterspar, or Rhombspar. This mi- 
 neral crystallizes in rhomboids, which were 
 confounded with those of calcareous spar, 
 till Dr Wollaston applied his admirable re- 
 flecting goniometer, and proved the peculia- 
 rity of the angles in bitterspar, which are 
 106° 15', and 73° 45'. Its colour is greyish 
 -or yellow, with a somewhat pearly lustre. It 
 is brittle, semi-transparent, splendent, and 
 .harder than calcareous spar. Fracture straight 
 foliated with a threefold cleavage. Its sp. gr. 
 is 2.88. It consists of from 68 to 73 car- 
 bonate of lime, 25 carbonate of magnesia, 
 jmd 2 oxide of manganese. It is usually 
 imbedded in serpentine, chlorite or steatite; 
 and is found in the Tyrol, Salzburg, and 
 Dauphiny. In Scotland, on the borders of 
 Loch Lomond in chlorite slate, and near 
 Newton- Stewart in Galloway; as also in the 
 Isle of Mann. It bears the same relation to 
 dolomite and magnesian limestone, that cal- 
 careous spar does to common limestone.* 
 
 Bitumen. This term includes a consider- 
 able range of inflammable mineral sub- 
 stances, burning with flame in the open air. 
 I hey are of different consistency, from a 
 thin fluid to a solid ; but the solids are for 
 the most part liquefiable at a moderate heat. 
 The fluid arc, 1. Naphtha; a fine, white, 
 thin, fragrant, colourless oil, which issues 
 out of white, yellow, or black clays in Per- 
 sia and Media, 'i bis is highly inflammable, 
 and is decomposed by distillation. It dis- 
 solves resins, and the essential oils of thyme 
 and lavender ; but is not itself soluble either 
 in alcohol or ether. It is the lightest of all 
 the dense fluids, its specific gravity being 
 0.708. 2. Petroleum, which is a yellow, 
 
 reddish, brown, greenish, or blackish oil, 
 found dropping from rocks, or issuing from 
 the earth, in the duchy of Modena, and in 
 yaiious other parts of Furope and Asia. 
 1 his likewise is insoluble in alcohol, and 
 seems to consist of naphtha, thickened by 
 •cxposuie to the atmosphere. It contains a 
 portion of the succinic acid. 5. Barbadoes 
 tar, which is a viscid, brown, or black in- 
 flammable substance, insoluble in alcohol, 
 and containing the succinic acid. This ap- 
 pears to be the mineral oil in its third state 
 of alteration. The solid are, I. Asphaltum, 
 mineral pitch, of which there are three va- 
 rieties: the cohesive; the semi-compact, 
 maltha; the compact, or asphaltum. These 
 
 are smooth, more or less hard or brittle, 
 inflammable substances, which melt easily, 
 and burn without leaving any or but little 
 ashes, if they be pure. They are slightly 
 and partially acted on by alcohol and ether. 
 2. Mineral tallow, which is a white sub- 
 stance of the consistence of tallow, and as 
 greasy, although more brittle. It was found 
 in the sea on the coasts of Finland, in the 
 year 1736; and is also met with in some 
 rocky parts of Persia. It is near one-fifth 
 lighter than tallow ; burns with a blue flame, 
 and a smell of grease, leaving a black viscid 
 matter behind, which is more difficultly con- 
 sumed. 5 . Elastic bitumen, or mineral 
 caoutchouc, of which there are two varieties. 
 Beside these, there are other bituminous 
 substances, as jet and amber, which ap- 
 proach the harder bitumens in their nature ; 
 and all the varieties of pit-coal, and the bitu- 
 minous schistus, or shale, which contain 
 more or less of bitumen in their composition. 
 See the different kinds of bitumen and bitu- 
 minous substances, in their respective places 
 in the order of the alphabet. 
 
 * Bituminous Limestone is of a lamel- 
 lar structure ; susceptible of polishing ; 
 emits an unpleasant smell when rubbed, and 
 has a brown or black colour. Heat con- 
 verts it into quicklime. It contains 8.8 alu- 
 mina; 0.6 silica; 0.6 bitumen; and 89-75 
 carbonate of lime. It is found near Bristol, 
 and in Galway in Ireland. The Dalmatian 
 is so charged with bitumen that it may be 
 cut like soap, and is used for building 
 houses. When the w'alls are reared, fire is 
 applied to them and they burn white.* 
 
 * Black Chalk. This mineral has a blu- 
 ish-black colour; a slaty texture; soils the 
 fingers, and is meagre to the touch. It con- 
 tains about 64 silica, 1 1 alumina, 1 1 car- 
 bon, with a little iron and water. It is 
 found in primitive mountains, and also 
 sometimes near coal formations. It occurs 
 in Caernarvonshire, and in the Island of 
 Isla.* 
 
 Black Jack. The miners distinguish 
 blende, or mock lead, by this name. It is 
 an ore of zinc. 
 
 Black Lead. See Plumbago. 
 
 Black Wald. One of the ores of man- 
 ganese. 
 
 * Bleaching. The chemical art by which 
 the various articles used for clothing are de- 
 prived of their natural dark colour and ren- 
 dered white. 
 
 The colouring principle of silk is un- 
 doubtedly resinous. Lienee, M. Baume 
 proposed the following process, as the best 
 mode of bleaching it. On six pounds of 
 yellow raw silk, disposed in an earthen pot, 
 pounds of alcohol, sp. gr. 0.867, mixed 
 with 12 oz. muriatic acid, sp. gr. 1.100, are 
 to be poured. After a day’s digestion, the 
 liquid passes from a fine green colour to a 
 
BLE 
 
 BLE 
 
 dusky brown. The silk is then to be drain- 
 ed, and washed with alcohol. A second in- 
 fusion with the above acidulated alcohol is 
 then made, for four or six days, after 
 which the silk is drained and washed with 
 alcohol. 1 he spirit may be recovered by 
 saturating the mingled acid with alkali or 
 lime, and distilling. M. Baume says, that 
 silk may thus be made to rival or surpass in 
 whiteness and lustre, the finest specimens 
 from Nankin. But the ordinary method of 
 bleaching silk is the following:* — The silk, 
 being still raw, is put into a bag of thin 
 linen, and thrown into a vessel of boiling 
 river water, in which has been dissolved 
 good Genoa or Toulon soap. 
 
 After the silk has boiled two or three 
 hours in that water, the bag being frequent- 
 ly turned, it is taken out to be beaten, and 
 is then washed in cold water. When it has 
 been thus thoroughly washed and beaten, 
 they wring it slightly, and put it for the 
 second time into the boiling vessel, filled 
 with cold water, mixed with soap and a 
 little indigo; which gives it that bluish cast 
 commonly observed in white silk. 
 
 When the silk is taken out of this second 
 water, they wring it hard with a wooden 
 peg, to press out all the water and soap ; 
 after which they shake it to untwist it, and 
 separate the threads. Then they suspend 
 it in a kind of stove constructed for that 
 purpose, where they burn sulphur ; the va- 
 pour of which gives the last degree of white- 
 ness to the silk. 
 
 The method of bleaching woollen stuffs . — 
 There are three ways of doing this. The 
 first is with water and soap ; the second 
 with the vapour of sulphur ; and the third 
 with chalk, indigo, and the vapour of sul- 
 phur. 
 
 Bleaching with soap and water . — After the 
 stuffs are taken out of the fuller’s mill, they 
 are put into soap and water, a little warm, 
 in which they are again worked by the 
 strength of the arms over a wooden bench : 
 this finishes giving them the whitening 
 which the fuller’s mill had only begun. 
 When they have been sufficiently worked 
 with the hands, they are washed in clear 
 water and put to dry. 
 
 This method of bleaching woollen stuffs is 
 called the Natural Method. 
 
 Bleaching with sulphur . — They begin with 
 washing and cleansing the stuffs thoroughly 
 in river water ; then they put them to dry 
 upon poles or perches. When they are half 
 dry, they stretch them out in a very close 
 stove, in which they burn sulphur ; the va- 
 pour of which diffusing itself, adheres by de- 
 grees to the whole stuff, and gives it a fine 
 whitening; this is commonly called Bleach- 
 ing by the Flower, or Bleaching of Paris, 
 because they use this method in that city 
 •more than anv where else. 
 
 * The colouring matter of linen and cotton 
 is also probably resinous ; at least the ex- 
 periments of Mr Kirwan on alkaline lixivia 
 saturated with the dark colouring matter, 
 lead to that conclusion. By neutralizing the 
 alkali with dilute muriatic acid, a precipitate 
 resembling lac was obtained, soluble in alco- 
 hol, in solutions of alkalis, and alkaline sul- 
 phurets. 
 
 The first step towards freeing vegetable 
 yarn or cloth from their native colour, is fer- 
 mentation. The raw goods are put into a 
 large wooden tub, with a quantity of used 
 alkaline lixivium, in an acescent state, heat- 
 ed to about the hundredth degree of Fahr. 
 It would be better to use some uncoloured 
 fermentable matter, such as soured bran or 
 potato paste, along with clean warm water. 
 In a short time, an intestine motion arises, 
 air bubbles escape, and the goods swell, rais- 
 ing up the loaded board which is used to 
 press them into the liquor. At the end 
 of from 18 to 48 hours, according to the 
 quality of the stuffs, the fermentation ceases, 
 when the goods are to be immediately with- 
 drawn and washed. Much advantage may 
 be derived by the skilful bleacher, from con- 
 ducting the acetous fermentation completely 
 to a close, without incurring the risk of in- 
 juring the fibre, by the putrefactive fermen- 
 tation. 
 
 The goods are next exposed to the action 
 of hot alkaline lixivia, by bucking or boil- 
 ing, or both. The former operation con- 
 sists in pouring boiling hot ley on the cloth 
 placed in a tub ; after a short time drawing 
 off the cooled liquid belovr, and replacing it 
 above, by hot lixivium. The most conve- 
 nient arrangement of apparatus is the follow- 
 ing: — Into the mouth of an egg-shaped iron 
 boiler, the bottom of a large tub is fixed air 
 tight. The tub is furnished with a false 
 bottom pierced with holes, a few inches 
 above the real bottom. In the latter, a 
 valve is placed, opening downwards, but 
 which may be readily closed, by the upwards 
 pressure of steam. From the side of the iron 
 boiler, a little above its bottom, a pipe issues, 
 which, turning at right angles upwards, rises 
 parallel to the outside of the bucking tub, to 
 a foot or two above its summit. The verti- 
 cal part of this pipe forms the cylinder of a 
 sucking pump, and has a piston and rod 
 adapted to it. At a few inches above the 
 level of the mouth of the tub, the vertical 
 pipe sends off a lateral branch, which termi- 
 nates in a bent-down nozzle, over a hole in 
 the centre of the lid of the tub. Under the 
 nozzle, and immediately within the lid, is a 
 metallic circular disc. The boiler being 
 charged with lixivium, and the tub with 
 the washed goods, a moderate fire is kindled. 
 At the same time, the pump is set a-going, 
 either by the hand of a workman or by ma- 
 chinery. Thus, the lixivium in its progres- 
 
BLE 
 
 sively heating state, is made to circulate 
 continually down through the stuffs. But 
 when it finally attains the boiling tempera- 
 ture, the piston rod and piston are removed, 
 and the pressure of the included steam 
 alone, forces the liquid up the vertical pipe, 
 and along the horizontal one in an uninter- 
 rupted stream. The valve at the bottom of 
 the tub, yielding to the accumulated weight 
 of the liquid, opens from time to time, and 
 replaces the lixivium in the boiler. 
 
 This most ingenious self-acting apparatus, 
 was invented by Mr John Laurie of G lasgow ; 
 and a representation of it accompanies Mr 
 Ramsay’s excellent article, Bleaching, in the 
 Edinburgh Encyclopaedia. By its means, 
 labour is spared, the negligence of servants 
 is guarded against, and fully one-fourth of 
 alkali saved. 
 
 It is of great consequence to heat the 
 liquid very slowly at first. Hasty boiling 
 is incompatible with good bleaching. When 
 the ley seems to be impregnated with co- 
 louring matter, the fire is lowered, and 
 the liquid drawn off by a stop-cock ; at the 
 same time that water, at first hot and then 
 cold, is run in at top, to separate all the 
 dark coloured lixivium. The goods are 
 then taken out and well washed, either by 
 the hand with the wash stocks, or by the ro- 
 tatory wooden wheel with hollow compart- 
 ments, called the dash wheel. The strength 
 of the alkaline lixivium is varied by diffe- 
 rent bleachers. A solution of potash, ren- 
 dered caustic by lime, of the specific gravity 
 1.014, or containing a little more than 1 per 
 cent of pure potash, is used by many 
 bleachers. The Irish bleachers use barilla- 
 lixivium chiefly, and of inferior alkaline 
 power. The routine of operations may be 
 conveniently presented in a tabular form. 
 
 A parcel of goods consists of 360 pieces 
 of those linens which are called Britannias. 
 Each piece is 35 yards long, weighing on 
 an average, 10 pounds. Hence, the weight 
 of the whole is 5600 pounds avoirdupois. 
 These linens are first washed, and then sub- 
 jected to the acetous fermentation, as above 
 described. They then undergo the follow - 
 ing operations: — 
 
 1. Bucked with 60 lbs. pearl ashes, wash- 
 ed and exposed on the field. 
 
 2. 
 
 do. with 
 
 80 lbs. do. 
 
 do. 
 
 do. 
 
 3. 
 
 do. 
 
 90 
 
 potashes 
 
 do. 
 
 do. 
 
 4. 
 
 do. 
 
 80 
 
 do. 
 
 do. 
 
 do. 
 
 5. 
 
 do. 
 
 80 
 
 do. 
 
 do. 
 
 do. 
 
 6. 
 
 do. 
 
 50 
 
 do. 
 
 do. 
 
 do. 
 
 7. 
 
 do. 
 
 70 
 
 do. 
 
 do. 
 
 do. 
 
 8. 
 
 do. 
 
 70 
 
 do. 
 
 do. 
 
 do. 
 
 9. Soured one night in dilute sulphuric 
 acid. 
 
 10. Bucked with 50 lbs. pearl ashes, wash- 
 ed and exposed. 
 
 1 1. Immersed in the oxymuriato of potash 
 for 12 hours. 
 
 BLE 
 
 ] 2. Boiled with SO lbs. pearl ashes, wash- 
 ed and exposed. 
 
 15. do. 30 do. do. do. 
 
 14. Soured and washed. 
 
 The linens are then taken to the rubbing 
 board, and well rubbed with a strong lather 
 of black soap, after which they are well 
 washed in pure spring w-ater. At this pe- 
 riod they are carefully examined, and those 
 which are fully bleached are laid aside to be 
 blued and made up for the market. Those 
 which are not fully white, are returned to bo 
 boiled and steeped in the oxymuriate of pot- 
 ash, and soured until they are fully white. 
 By the above process, 690 lbs. of commer- 
 cial alkali are used in bleaching 360 pieces 
 of linen, each measuring 35 yards. Hence, 
 the expenditure of alkali would be a little 
 under 2 lbs. a- piece, were it not that some 
 part of the above linens may not be 
 thoroughly w'hitened. It will, therefore, be 
 a fair average, to allow 2 lbs. for each piece 
 of such goods. 
 
 On the above process we may remark, 
 that many enlightened bleachers have found 
 it advantageous to apply the souring at a 
 more early period, as well as the oxymuriatic 
 solution. According to Dr Stephenson, in 
 his elaborate paper on the linen and hempen 
 manufactures, published by the Belfast Lite- 
 rary Society, 10 naggins, or quarter pints of 
 oil of vitriol, are sufficient to make 200 gal- 
 lons of souring. This gives the proportion, 
 by measure, of 640 water to 1 of acid. Mr 
 Parkes, in describing the bleaching of cali- 
 coes in his Chemical Essays, says, that, 
 throughout Lancashire, one measure of sul- 
 phuric acid is used with 46 of water, or one 
 pound of the acid to 25 pounds of water ; 
 and he states, that a scientific calico printer 
 in Scotland makes his sours to have the spe- 
 cific gravity 1.0254 at 110° of Fahrenheit; 
 which dilute acid contains at least l-25th of 
 oil of vitriol. Five or six hours’ immersion 
 is employed. 
 
 In a note Mr Parkes adds, that in bleach- 
 ing common goods, and such as are not de- 
 signed for the best printing, the specific 
 gravity of the sours is varied from 1.0146 to 
 1.0238, if taken at the atmospheric tempe- 
 rature. Most bleachers use the strongest 
 alkaline lixiviums at first, and the weaker 
 afterwards. As to the strength of the oxy- 
 muriatic steeps, as the bleacher terms them, 
 it is difficult to give certain data, from the 
 variableness of the chlorides of potash and 
 lime. 
 
 Mr Parkes, in giving the process of the 
 Scotch bleacher, says, that after the cali- 
 coes have been singed, steeped, and squeezed, 
 they are boiled four successive times, for 1 0 
 or 12 hours each, in a solution of caustic 
 potash of a specific gravity from 1.0127 to 
 1.0156, and washed thoroughly between 
 each boiling, “ They are then immersed in 
 
BLE 
 
 BLE 
 
 a solution of the oxymuriate of potash, ori- 
 ginally of the strength of 1.0625, and after- 
 wards reduced with 24 times its measure of 
 water. In this preparation they are suffered 
 to remain 12 hours.” Dr Stephenson says, 
 that, for coarse linens, the steep is made by 
 dissolving 1 lb. of oxymuriate of lime in 3 
 gallons ot water, and afterwards diluting 
 with 25 additional gallons. The ordinary 
 specific gravity of the oxymuriate of lime 
 steeps, by Mr Ramsay, is 1.005. Rut from 
 these data, little can be learned ; because 
 oxymuriate of lime is always more or less 
 mixed with common muriate of lime, or 
 chloride of calcium, a little of which has a 
 great effect on the hydrometric indications. 
 The period of immersion is 10 or 12 hours. 
 Many bleachers employ gentle and long 
 continued boiling without bucking. The 
 operation of souring was long ago effected 
 by butter milk, but it is more safely and ad- 
 vantageously performed by the dilute sul- 
 phuric acid uniformly combined with the 
 water by much agitation. 
 
 Mr Tennent’s ingenious mode of uniting 
 chlorine with pulverulent lime, was one of 
 the greatest improvements in practical bleach- 
 ing. When this chloride is well prepared 
 and properly applied, it will not injure the 
 most delicate muslin. Magnesia has been 
 suggested as a substitute for lime, but the 
 high price of this alkaline earth, must be a 
 bar to its general employment. The mu- 
 riate of lime solution resulting from the ac- 
 tion of unbleached cloth on that of the oxy- 
 muriate, if too strong, or too long applied, 
 would weaken the texture of cloth, as Sir H. 
 Davy has shewn. But the bleacher is on 
 his guard against this accident ; and the 
 process of souring, which follows most com- 
 monly the oxymuriatic steep, thoroughly re- 
 moves the adhering particles of lime. 
 
 Blr Parkes informs us, that calicoes for 
 madder work, or resist work, or for the fine 
 pale blue dipping, cannot without injury be 
 bleached with oxymuriate of lime. They 
 require, he says, oxymuriate of potash. I 
 believe this to be a mistake. Test liquors 
 made by dissolving indigo in sulphuric acid, 
 and then diluting the sulphate with water, 
 or with infusion of cochineal, are employed 
 to measure the blanching power of the oxy- 
 muriatic or chloridic solutions. But they 
 are all more or less uncertain, from the 
 changeableness of these colouring matters. 
 I have met with indigo of apparently excel- 
 lent quality, of which four parts were re- 
 quired to saturate the same weight of oxy- 
 muriate of lime, as was saturated by three 
 parts of another indigo. Such coloured 
 liquors, however, though they give no abso- 
 lute measure of chlorine, afford useful means 
 of comparison to the bleacher. 
 
 Some writers have recommended lime and 
 
 sulphuret of lime as detergent substances in- 
 
 stead of alkali ; but I believe no practical 
 bleacher of respectability would trust to them. 
 Lime should always be employed, however, 
 to make the alkalis caustic ; in which state 
 their detergent powers are greatly increased. 
 
 The coarser kinds of muslin are bleached 
 by steeping, washing, and then boiling them 
 in a weak solution of pot and pearl ashes. 
 They are next washed, and afterwards boiled 
 in soap alone, and then soured in very dilute 
 sulphuric acid. After being washed from 
 the sour, they are boiled with soap, washed, 
 and immersed in the solution of chloride of 
 lime or potash. The boiling in soap, and 
 immersion in the oxymuriate, is repeated, 
 until the muslin is of a pure white colour. 
 It is finally soured and washed in pure 
 spring water. The same scries of operations 
 is used in bleaching fine muslins, only soap' 
 is used in the boilings commonly to the ex- 
 elusion of pearl ash. Fast coloured cottons 
 are bleached in the following way: — After 
 the starch or dressing is well removed by 
 cold water, they are gently boiled with soap, 
 washed, and immersed in a moderately strong 
 solution of oxymuriate of potash. This pro- 
 cess is repeated till the white parts of the 
 cloth are sufficiently pure. They are them 
 soured in dilute sulphuric acid. If these - 
 operations be well conducted, the colours, 
 instead of being impaired, will be greatly 
 improved, having acquired a delicacy of tint 
 which no other process can impart. 
 
 After immersing cloth or yarn in alkaline- 
 ley, if it be exposed to the action of steam 
 heated to WWW y in a strong vessel, it will be 
 in a great measure bleached. 
 
 This operation is admirably adapted to the 
 cleansing of hospital linen. 
 
 The following is the practice followed by 
 a very skilful bleacher of muslins near Glas- 
 gow. 
 
 “ In fermenting inusTin goods, we surround 
 them with our spent leys from the tempe- 
 rature of 100° to 150° F. according to the 
 weather, and allow them to ferment for 36 
 hours. In boiling 112 lbs. = 112 pieces of 
 yard-wide muslin, we use 6 or 7 lbs. of 
 ashes, and 2 lbs. of soft soap, and allow 
 them to boil for 6 hours ; then wash them, 
 and boil them again, with 5 lbs. of ashes, 
 and 2 lbs of soft soap, and allow them to 
 boil 3 hours ; then wash them with water, 
 and immerse them into the solution of oxy- 
 muriate of lime, at 5 on the test tube, and 
 allow them to remain from 6 to 12 hours; 
 next wash them, and immerse them into 
 diluted sulphuric acid at the specific gravity 
 of on Twaddle’s hydrometer = 1.0175, 
 and allow them to remain an hour. They 
 are now well washed, and boiled with 2^ lbs. 
 of ashes, and 2 lbs. of soap, for half an hour ; 
 afterwards washed and immersed into the 
 oxymuriate of lime as before, at the strength 
 of 3 on the test tube, which is stronger than 
 
BLE 
 
 BLO 
 
 the former, and allowed to remain for 6 
 hours. They are again washed and immersed 
 into diluted sulphuric acid at the specific 
 gravity of 3 on Twaddle’s hydrometer = 
 1.015* If the goods be strong, they will 
 require another boil, steep, and sour. At 
 any rate, the sulphuric acid is well washed 
 out before they receive the finishing opera- 
 tion with starch. 
 
 “ With regard to the lime, which some use 
 instead of alkali, immediately after ferment- 
 ing, the same weight of it is employed as of 
 ashes, along with the former weight of soap. 
 The goods are allowed to boil in it for 15 
 minutes, but not longer, otherwise the lime 
 will injure the fabric.” 
 
 The alkali may be recovered from the 
 brown lixivia, by evaporating them to dry- 
 ness and gentle ignition of the residuum. 
 But, in most situations, the expense of fuel 
 would exceed the value of the recovered 
 alkali. A simpler mode is to boil the foul 
 lixivium with quicklime, and a little pipe- 
 clay and bullock’s blood. After skimming, 
 and subsidence, a tolerably pure ley is ob- 
 tained.* 
 
 Under the head of chlorine, we have de- 
 scribed the preparation of this article ; and 
 the chief circumstance respecting it to be no- 
 ticed here is the apparatus, which must be 
 on an extensive scale, and adapted to the 
 purpose of immersing and agitating the goods 
 to be bleached. The process of distillation 
 may be performed in a large leaden alembic, 
 g g, Plate I. fig. 1. supported by an iron 
 trevet J] in an iron boiler e. This is heated 
 by a furnace b, of which a is the ashhole, c 
 the place for introducing the fuel ; d is the 
 handle of a stopper of burnt clay, for regu- 
 lating the draught. To the top of the alem- 
 bic is fitted a leaden cover {, which is luted 
 on, and has three perforations ; one for the 
 i curved glass or leaden funnel h, through 
 which the sulphuric acid is to be poured in ; 
 one in the centre for the agitator k, made of 
 iron coated with lead ; and the third for the 
 ‘ leaden tube l, three inches in diameter inter- 
 nally, through which the gas is conveyed in- 
 to the tubulated leaden receiver m. To 
 prevent the agitator from reaching to the 
 bottom ot the alembic, it is furnished with a 
 conical leaden collar, adapted to a conical 
 projection round the hole in the centre of 
 the cover, to which it becomes so closely 
 fitted by means of its rotatory motion, as to 
 prevent the escape of the gas. The tube /, 
 i passing through the aperture m, to the bot- 
 tom of the intermediate receiver nearly, 
 which is two- thirds full of water, deposits 
 there the little sulphuric acid that may arise ; 
 while the chlorine gas passes through the 
 tube n into the wooden condenser oo. The 
 agitator p, turned by its handle t, serves to 
 ( > accelerate the combination of the gas with 
 the alkali, to which the horizontal pieces 
 
 q q , projecting from the inside, likewise con- 
 tribute. The cover of this receiver has a 
 sloping groove r, to fit close on its edge; 
 which is bevilled on each side ; and a cock s 
 serves to draw off the liquor. Mr Ten- 
 nent’s chloride of lime has nearly superseded 
 that plan. 
 
 The rags or other materials for making 
 paper may be bleached in a similar manner : 
 but it is best to reduce them first to the 
 state of pulp, as then the acid acts more' 
 uniformly upon the whole substance. 
 
 For bleaching old paper : Boil your print- 
 ed paper for an instant in a solution of caustic 
 soda. That from kelp may be used. Steep 
 it in soap-suds, and then wash it ; after 
 which it may be reduced to pulp. The soap 
 may be omitted without much inconvenience.- 
 For old written paper to be worked up 
 again : Steep it in water acidulated with 
 sulphuric acid, and then wash it well before 
 it is taken to the mill. If the w ater be heat- 
 ed it wall be more effectual. To bleach 
 printed paper, without destroying its texture r 
 Steep the leaves in a caustic solution of soda, 
 either hot or cold, and then in a solution of 
 soap. Arrange them alternately between 
 cloths, as paper-makers do thin sheets of 
 paper when delivered from the form, and 
 subject them to the press. If one operation 
 do not render them sufficiently white, it may 
 be repeated as often as necessary. To bleach 
 old written paper, without destroying its tex- 
 ture : Steep the paper in water acidulated 
 w r ith sulphuric acid, either hot or cold, and 
 then in a solution of oxygenated muriatic 
 acid ; after w hich immerse it in water, that 
 none of the acid may remain behind. Thi^ 
 paper, when pressed and dried, will be fit 
 for use as before. 
 
 Blende. An ore of zinc. 
 
 Blood. The fluid which first presents it- 
 self to observation, when the parts of living 
 animals are divided or destroyed, is the blood, 
 which circulates with considerable velocity 
 through vessels, called veins and arteries, 
 distributed into every part of the system. 
 
 Recent blood is uniformly fluid, and of a 
 saline taste. Under the microscope, it ap- 
 pears to be composed of a prodigious num- 
 ber of red globules, swimming in a transpa- 
 rent fluid. After standing for a short time, 
 its parts separate into a thick red matter, or 
 crassamentum, and a fluid called serum. If 
 it be agitated till cold, it continues fluid ; 
 but a consistent polypous matter adheres to 
 the stirrer, which by repeated ablutions with 
 water becomes white, and has a fibrous ap- 
 pearance ; the crassamentum becomes white 
 and fibrous by the same treatment. If blood 
 be received from the vein into warm water, 
 a similar filamentous matter subsides, while 
 the other parts are dissolved. Alkalis pre- 
 vent the blood from coagulating ; acids, on 
 the contrary, accelerate that effect. In the 
 
 
BLO 
 
 BLO 
 
 latter case, the fluid is found to contain neu- 
 tral salts, consisting of the acid itself, united 
 with soda, which consequently must exist in 
 the blood, probably in a disengaged state. 
 Alcohol coagulates blood. On the water 
 bath, blood affords an aqueous fluid, neither 
 acid nor alkaline, but of a faint smell, and 
 easily becoming putrid. A stronger heat 
 gradually dries it, and at the same time re- 
 duces it to a mass of about one- eighth of its 
 original weight. 
 
 * Blood usually consists of about 3 parts 
 serum to 1 of cruor. The serum is of a pale 
 greenish-yellow colour. Its specific gravity 
 is about 1.029, while that of blood itself is 
 1.053. It changes syrup of violets to a 
 green, from its containing free soda. At 
 156° serum coagulates, and resembles boiled 
 white of egg. When this coagulated albu- 
 men is squeezed, a muddy fluid exudes, 
 which has been called the serosity. Accord- 
 ing to Berzelius, 1000 parts of the serum of 
 bullock’s blood consist of 905. water, 79.99 
 albumen, 6.175 lactate of soda and extrac- 
 tive matter, 2.565 muriates of soda and pot- 
 ash, 1.52 soda and animal matter, and 4.75 
 loss. 1000 parts of serum of human blood 
 consist, by the same chemist, of 905 water, 
 80 albumen, 6 muriates of potash and soda, 
 4 lactate of soda with animal matter, and 
 4.1 of soda, and phosphate of soda with ani- 
 mal matter. There is no gelatin in serum. 
 
 The cruor has a specific gravity of about 
 1 .245. By making a stream of water flow up- 
 on it till the water runs off' colourless, it is se- 
 parated into insoluble fibrin, and the soluble 
 colouring matter. A little albumen has also 
 been found in cruor. The proportions of 
 the former two, are 64 colouring matter, and 
 56 fibrin in 100. To obtain the colouring 
 matter pure, we mix the cruor with 4 parts 
 of oil of vitriol previously diluted with 8 
 parts of water, and expose the mixture to a 
 heat of about 160° for 5 or 6 hours. Filter 
 the liquid while hot, and wash the residue 
 with a few ounces of hot water. Evaporate the 
 liquid to one-half, and add ammonia, till the 
 acid be almost, but not entirely saturated. 
 The colouring matter falls. Decant the 
 supernatant liquid, filter and wash the resi- 
 duum, from the whole of the sulphate of am- 
 monia. When it is well drained, remove it 
 with a platina blade, and dry it in a capsule. 
 
 When solid, it appears of a black colour, but 
 becomes wine- red by diffusion through water, 
 in which, how r ever, it is not soluble. It has 
 neither taste nor smell. Alcohol and ether 
 convert it into an unpleasant smelling kind 
 of adipocere. It is soluble both in alkalis 
 and acids. It approaches to fibrin in its 
 constitution, and contains iron in a peculiar 
 state, } of a per cent of the oxide of which 
 may be extracted from it by calcination. 
 The incinerated colouring matter weighs 
 l-80th of the whole; and these ashes con- 
 
 sist of 50 oxide of iron, 7.5 subphosphate of 
 iron, 6 phosphate of lime, with traces of 
 magnesia, 20 pure lime, 16.5 carbonic acid 
 and loss ; or the two latter ingredients may 
 be reckoned .32 carbonate of lime. Berzelius 
 imagines that none of these bodies existed in 
 the colouring matter, but only their bases, 
 iron, phosphorus, calcium, carbon, &c. and 
 that they were formed during the incinera- 
 tion. From the albumen of blood, the same 
 proportion of ashes may be obtained, but no 
 iron. 
 
 No good explanation has yet been given 
 of the change of colour which blood under- 
 goes from exposure to oxygen, and other 
 gases. Under the exhausted receiver, car- 
 bonic acid gas is disengaged from it. The 
 blood of the foetus is darker coloured than 
 that of the adult; it has no fibrin, and no 
 phosphoric acid. The huffy coat of inflam- 
 ed blood is fibrin ; from which the colouring 
 matter has precipitated by the greater li- 
 quidity or slowmess of coagulation produced 
 by the disease. The serum of such blood 
 does not yield consistent albumen by heat. 
 In diabetes mellitus, when the urine of the 
 patient is loaded wdth sugar, the serum of 
 the blood assumes the appearance of whey, 
 according to Dr Rollo and Dobson ; but 
 Dr Wollaston has proved that it contains no 
 sugar. * 
 
 Dr Carbonel of Barcelona has employed 
 serum of blood on an extensive scale in 
 painting. Mixed with powdered quicklime 
 or slaked lime, to a proper consistence, it 
 is easily applied on wood, to which it thus 
 gives a coating of a stone colour, that dries 
 quickly, without any bad smell, and resists 
 the action of sun and rain. The wood 
 should be first covered with a coating of 
 plaster, the composition must be mixed as it 
 is used, and the serum must not be stale. It 
 maybe used too as a cement for water-pipes, 
 and for stones in building under water. 
 
 * Bloodstone. See Calcedony.* 
 
 Blow-pipe. This simple instrument will 
 
 be described under the article Laboratory. 
 
 * We shall here present our readers first 
 with an abstract of Assessor Gahn’s late valu- 
 able treatise on the comvion blow r -pipe, and 
 shall aftenvards give an account of Dr 
 Clarke’s very interesting experiments with 
 the oxyhydrogen blow-pipe.* 
 
 The substance to be submitted to the 
 action of the blow-pipe must be placed on a 
 piece of charcoal, or in a small spoon of plat- 
 ina, gold, or silver; or, according to Saus- 
 sure, a plate of cyanite may sometimes be 
 used. Charcoal from the pine is to be pre- 
 ferred, which should be well ignited and 
 dried, that it may not crack. The sides, not 
 the ends, of the fibres must be used ; otherwise 
 the substance to be fused spreads about, and 
 a round bead will not be formed. A small 
 hole is to be made in the charcoal, which is 
 
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 best done by a slip of plate iron bent longi- 
 tudinally. Into this hole the substance to be 
 examined must be put in very small quantity ; 
 if a very intense heat is to be used, it should 
 not exceed the size of half a peppercorn. 
 
 The metallic spoons are used when the 
 substance to be examined is intended to be 
 -exposed to the action of heat only, and might 
 undergo some change by immediate contact 
 with the charcoal. When the spoon is used, 
 the flame of the blow-pipe should be directed 
 to that part of it which contains the sub- 
 stance under examination, and not be imme- 
 diately applied to the substance itself. The 
 handle of the spoon may be inserted into a 
 piece of charcoal : and if a very intense heat 
 is required, the bowl of the spoon may be 
 adapted to a hole in the charcoal. Small 
 portions may be taken up by platina forceps. 
 Salts and volatile substances are to be heated 
 in a glass tube closed at one end, and en- 
 larged according to circumstances, so as to 
 form a small matrass. 
 
 When the alteration which the substanco 
 undergoes by the mere action of heat has 
 ■been observed, it will be necessary to exa- 
 mine what further change takes place when it 
 is melted with various fluxes, and how far it 
 is capable of reduction to the metallic state. 
 
 These fluxes are, 
 
 1. Microcosmic salt; a compound of 
 phosphoric acid, soda, and ammonia. 
 
 2. Subcarbonate of soda, which must be 
 free from all impurity, and especially from 
 sulphuric acid, as this will be decomposed, 
 and sidphuret of soda will be formed, which 
 will dissolve the metals we wish to reduce, 
 and produce a bead of coloured glass with 
 substances that would otherwise give a co- 
 lourless one. 
 
 3. Borax, which should be first freed 
 from its water of crystallization. 
 
 These are kept powdered in small phials; 
 and when used a sufficient quantity may be 
 taken up by the moistened point of a knife : 
 the moisture causes the particles to cohere, 
 and prevents their being blown away when 
 placed on the charcoal. The flux must then 
 be melted to a dear bead, and the substance 
 to be examined placed upon it. It is then 
 to he submitted to the action, first of the ex- 
 terior, and afterwards of the interior flame, 
 and the following circumstances to be care- 
 fully observed: — 
 
 1 . W h ether the substance is dissolved ; 
 and, if so, 
 
 2. W h ether with or without effervescence, 
 which would be occasioned by the liberation 
 of carbonic acid, sulphurous acid, oxvgcn, 
 gaseous oxide of carbon, &c. 
 
 3. 'I'he transparency and colour of the 
 glass while cooling. 
 
 4. The same circumstances after cooling. 
 
 5 1 he nature of the glass formed by the 
 
 exterior flame, and 
 
 6. By the interior flame. 
 
 7. The various relations to each of the 
 fluxes. 
 
 It must be observed that soda will not 
 form a bead on charcoal, but with a certain 
 degree of heat will be absorbed. When, 
 therefore, a substance is to ‘be fused -with 
 soda, this flux must be added in very small 
 quantities, and a very moderate beat used at 
 first, by which means a combination will-take 
 place, and the soda will not be absorbed. It 
 too large a quantity of soda has been added 
 at first, and it has consequently been absorbed, 
 a more intense heat will cause it to return to 
 the surface of the charcoal, and it w ill then 
 enter into combination. 
 
 Some minerals combine readily with 
 only very small portions of soda, but melt 
 with difficulty if more be added, and are -ab- 
 solutely infusible with a larger quantity : 
 and when the substance has no affinity for 
 this flux, it is absorbed by the charcoal, and 
 no combination ensues. 
 
 When the mineral or the soda contains 
 sulphur or sulphuric acid, the glass acquires 
 a deep yellow^ colour, w'hich by the light of a 
 lamp appears red, and as if produced by 
 copper. 
 
 If the glass bead becomes opaque as it 
 cools, so as to render the colour indistinct, it 
 should be broken, and a part of it mixed w ith 
 more of the flux, until the colour becomes 
 more pure and distinct. To render the co- 
 lour more perceptible, the bead may be either 
 compressed before it cools, or drawn out to a 
 thread. 
 
 When it is intended to oxidate more 
 highly a metallic oxide contained in a vitrifi- 
 ed compound with any of the fluxes, the glass 
 is first heated by a strong flame, and -when 
 melted is to be gradually withdrawn from 
 the point of the blue flame. This operation 
 may be repeated several times, permitting the 
 glass sometimes to cool, and using a jet of 
 large aperture with the blow-pipe. 
 
 The reduction of metals is effected in the 
 following manner : The glass bead, formed 
 after the manner already pointed out, is to be 
 kept in a state of fusion on the charcoal as 
 long as it remains on the surface, and is not 
 absorbed, that the metallic particles may col- 
 lect themselves into a globule. It is then to 
 be fused with an additional quantity of soda, 
 which will he absorbed by the charcoal, and 
 the spot w here the absorption has taken place 
 is to be strongly ignited by a tube with a 
 small aperture. By continuing this ignition, 
 the portion of metal which was not previ- 
 ously reduced will now be brought to a me- 
 tallic state ; and the process may be assisted 
 by placing the head in a smoky flame, so as to 
 cover it with soot that is not easily blown off’. 
 
 The greatest part of the beads which 
 contain metals are frequently covered with a 
 metallic splendour, which is most easily pro, 
 P ' V 
 
BLO 
 
 BLO 
 
 cluce'l by a gentle, fluttering, smoky flame, 
 when the more intense heat has ceased. 
 "With a moderate heat the metallic surface 
 remains ; and by a little practice it may ge- 
 nerally be known whether the substance un- 
 der examination contains a metal or not. 
 But it must be observed, that the glass of 
 borax sometimes assumes externally a metal- 
 lic splendour. 
 
 When the charcoal is cold, that part 
 impregnated with the fused mass should be 
 taken out with a knife, and ground with dis- 
 tilled water in a crystal, or, what is much 
 better, an agate mortar. The soda will be 
 dissolved ; the charcoal will float, and may 
 be poured off'; and the metallic particles will 
 remain in the water, and may be examined. 
 In this manner most of the metals may be 
 reduced. 
 
 j Relations of' the Earths and Metallic Oxides 
 before the Blow-pipe. 
 
 I. THE EARTHS. 
 
 Barytes , when containing water, melts and 
 spreads on the charcoal. Combined with 
 sulphuric acid, it is converted, in the interior 
 flame, into a sulphuret, and is absorbed by 
 the charcoal, with effervescence, which con- 
 tinues as long as it is exposed to the action 
 of the instrument. 
 
 Strontites. If combined with carbonic 
 acid, and held in small thin plates with pla- 
 tina forceps in the interior flame, the car- 
 bonic acid is driven off'; and on the side of 
 the plate farthest from the lamp, a red flame 
 is seen sometimes edged with green, and 
 scarcely perceptible but by the flame of a 
 lamp. Sulphate of strontites is reduced in 
 the interior flame to a sulphuret. Dissolve 
 this in a drop of muriatic acid, add a drop ot 
 alcohol, and dip a small bit of stick in the 
 solution; it will burn with a fine red flame. 
 
 Lime . The carbonate is easily rendered 
 caustic by heat ; it evolves heat on being 
 moistened, and is afterwards infusible before 
 the blow-pipe. The sulphate is easily re- 
 duced to sulphuret, and possesses, besides, 
 the property of combining with flu or at a 
 moderate heat, forming a clear glass. The 
 fluor should be rather in excess. 
 
 Magnesia produces, like the strontites, an 
 intense brightness in the flame of the blow r - 
 pipe. A drop of solution of cobalt being 
 added to it, and it being then dried and 
 strongly ignited, a faint reddish colour like 
 flesh is produced, which, however, is scarce- 
 ly visible by the light of a lamp. And mag- 
 nesia may by this process be detected in 
 compound bodies, if they do not contain 
 much metallic matter, or a proportion of 
 alumina exceeding the magnesia. Some in- 
 ference as to the quantity of* the magnesia 
 may be drawn from the intensity of the co- 
 lour produced. 
 
 All these alkaline earths, when pure, are 
 readily fusible in combination with the fluxes 
 into a clear, colourless glass, without effer- 
 vescence ; but on adding a further quantity 
 of the earth, the glass becomes opaque. 
 
 Alumina combines more slowly with the 
 fluxes than the preceding earths do, and 
 forms a clear glass, which does not become 
 opaque. But the most striking character of 
 alumina is the bright blue colour it acquires 
 from the addition of a drop of nitrate of 
 cobalt, after having been dried and ignited 
 for some time. And its presence may be 
 detected in this manner in compound mine- 
 rals, where the metallic substances are not in 
 great proportion, or the quantity of magnesia 
 large. Alumina may be thus detected in 
 the agalmatolite. 
 
 II. THE METALLIC OXIDES. 
 
 Arsenic flies off' accompanied by its cha- 
 racteristic smell, resembling garlic. When 
 larger pieces of white arsenic are heated on 
 a piece of ignited charcoal, no smell is per- 
 ceived. To produce this effect the white 
 oxide must be reduced, by being mixed with 
 powdered charcoal. If arsenic is held in 
 solution, it may be discovered by dipping 
 into the solution a piece of pure and well 
 burned charcoal, which is afterwards to be 
 dried and ignited. 
 
 Chrome . Its green oxide, the form in 
 
 which it most commonly occurs, and to 
 which it is reduced by heating in the com- 
 mon air, exhibits the following properties : 
 it is fusible with microcosmic salt , in the in- 
 terior flame, into a glass which, at the in- 
 stant of its removal from the flame, is of a 
 violet hue, approaching more to the dark 
 blue or red, according to the proportion of 
 chrome. After cooling, the glass is bluish- 
 green, but less blue than the copper glass. 
 In the exterior flame the colour becomes 
 brighter, and less blue, than the former. 
 With borax it forms a bright yellow ish, or 
 yellow’-red glass, in the exterior flame; and 
 in the interior flame, this becomes darker 
 and greener, or bluish-green. I he reduc- 
 tion w ith soda has not been examined. 
 
 Molybdic acid melts bv itself upon the 
 charcoal with ebullition, and is absorbed. In 
 a platina spoon it emits white fumes, and is 
 reduced in the interior flame to molybdous 
 acid, which is blue ; but in the exterior 
 flame it is again oxidated, and becomes w hite. 
 With microcosmic salt , in the exterior flame, 
 a small proportion of the acid gives a green 
 glass, which, by gradual additions ot the 
 acid, passes through yellow-green to reddish, 
 brownish, and hyacinth-brown, with a slight 
 tinge of green. In the interior flame the 
 colour passes from yellow-green, through 
 yellow-brown and brown-red, to black ; and 
 if the proportion of acid be large, it acquires 
 
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 BLO 
 
 a metallic lustre, like the sulphuret, which 
 sometimes remains after the glass has cool- 
 ed. Molybdic acid is but little dissolved by 
 borax. In the exterior flame the glass ac- 
 quires a grey-yellow colour. In the interior 
 flame, a quantity of black particles is precipi- 
 tated from the clear glass, and leaves it al- 
 most colourless when the quantity of molyb- 
 denum is small, and blackish when the pro- 
 portion is larger. If to a glass formed of 
 this acid and microcosmic salt a little borax 
 be added, and the mixture fused in the ex- 
 terior flame, the colour becomes instantly 
 reddish-brown ; in the interior flame the 
 black particles are also separated, but in 
 smaller quantity. By long continued heat 
 the colour of the glass is diminished, and it 
 appears yellower by the light of a lamp than 
 by day-light. This acid is not reduced by 
 soda in the interior flame. 
 
 Tungstic acid becomes upon the charcoal 
 at first brownish- yellow, is then reduced to a 
 brown oxide, and lastly becomes black with- 
 out melting or smoking. With microcosmic 
 salt it forms in the interior flame a pure blue 
 glass, without any violet tinge ; in the ex - 
 • terior flame this colour disappears, and re- 
 appears again in the interior. With borax , 
 in the internal flame, and in small propor- 
 tions it forms a colourless glass, which, by 
 increasing the proportion of the acid, be- 
 comes dirty grey, and then reddish. By 
 long exposure to the external flame it be- 
 comes transparent, but as it cools it becomes 
 irtuddy, jvhitish, and changeable into red 
 when seen by day-light. It is not reduced. 
 
 Oxide of Tantalum undergoes no change 
 by itself, but is readily fused with microcos- 
 mic salt and with borax , into a clear colour- 
 less glass, from which the oxide may be pre- 
 cipitated by heating and cooling it alternate- 
 ly. The glass then becomes opaque, and 
 the oxide is not reduced. 
 
 Oxide of Titanium becomes yellowish 
 when ignited in a spoon, and upon charcoal 
 dark brown. With microcosmic salt it gives 
 in the interior flame a fine violet-coloured 
 glass, with more of blue than that from man- 
 ganese. In the exterior flame this colour 
 disappears. With borax it gives a dirty 
 hyacinth colour. Its combinations with soda 
 have not been examined. 
 
 Oxide of Cerium becomes red-brown when 
 ignited. When the proportion is small it 
 forms with the fluxes a clear colourless glass, 
 
 ' which by increasing the proportion of oxide 
 becomes yellowish-green while hot. With 
 microcosmic salt , if heated a long time in the 
 i internal flame, it gives a clear colourless 
 glass. With borax , under similar circumstan- 
 |i ces, it gives a faint yellow-green glass while 
 if warm, but colourless when cold. Exposed 
 i again for some time to the external flame, it 
 I becomes reddish-yellow, which colour it partly 
 retains when cold. If two transparent beads 
 
 of the compound with microcosmic salt- and 
 with borax be fused together, the triple com- 
 pound becomes opaque and white. Flies off 
 by reduction. 
 
 Oxide of Uranium . The yellow oxide 
 
 by ignition becomes green or greenish-brown. 
 With microcosmic salt in the interior flamo 
 it forms a clear yellow glass, the colour of 
 which becomes more intense when cold. If 
 long exposed to the exterior flame, and fre- 
 quently cooled, it gives a pale yellowish red- 
 brown glass, which becomes greenish as it 
 cools. With borax in the interior flame a 
 clear, colourless, or faintly green glass, is 
 formed, containing black particles, which 
 appear to be the metal in its lowest state of 
 oxidation. In the exterior flame this black 
 matter is dissolved if the quantity be not too 
 great, and the glass becomes bright yellowish- 
 green, and after further oxidation yellowish- 
 brown. If brought again into the interior 
 flame, the colour gradually changes to green, 
 and the black matter is again precipitated, 
 but no further reduction takes place. 
 
 Oxide of Manganese gives with microcos- 
 mic salt in the exterior flame a fine amethyst 
 colour, which disappears in the interior flame. 
 With borax it gives a yellowish hyacinth red 
 glass. 
 
 When the manganese, from its combina- 
 tion with iron, or any other cause, does not 
 produce a sufficiently intense colour in the 
 glass, a little nitre may be added to it while 
 in a state of fusion, and the glass then be- 
 comes dark violet while hot, and reddish 
 violet when cool : is not reduced. 
 
 Oxide of Tellurium , when gently heated, 
 becomes first yellow, then light red, and af- 
 terwards black. It melts and is absorbed by 
 the charcoal, and is reduced with a slight 
 detonation, a greenish flame, and a smell of 
 horse- raddish. Microcosmic salt dissolves it 
 without being coloured. 
 
 Oxide of Antimony is partly reduced in 
 the exterior flame, and spreads a white smoke 
 on the charcoal. In the interior flame it is 
 readily reduced by itself, and with soda. 
 With microcosmic salt and with borax it 
 forms a hyacinth-coloured glass. Metallic 
 antimony, when ignited on charcoal, and re- 
 maining untouched, becomes covered with 
 radiating acicular crystals of white oxide. 
 Sulphuret of antimony melts on charcoal, 
 and is absorbed. 
 
 Oxide of Bismuth melts readily in a 
 spoon to a brown glass, which becomes 
 brighter as it cools. With microcosmic salt 
 it forms a grey-yellow glass, which loses its 
 transparency, and becomes pale, when cool. 
 Add a further proportion of oxide, and it 
 becomes opaque. With borax it forms a 
 grey glass, which decrepitates in the interior 
 flame, and the metal is reduced and volatil- 
 ized. It is most readily reduced by itself on 
 charcoal. 
 
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 Oxide of Zinc becomes yellow when heat- 
 ed, but whitens as It cools. A small pro- 
 portion forms with microcosmic sedt and with 
 borax a clear glass, which becomes opaque 
 on increasing the quantity of oxide. A drop 
 of nitrate of cobalt being added to the oxide, 
 and dried and ignited, it becomes green. 
 "With soda in the interior flame it is reduced, 
 and burns with its characteristic flame, de- 
 positing its oxide upon the charcoal. By 
 this process zinc may be easily detected even 
 in the automolite. Mixed with oxide of 
 copper, and reduced, the zinc will be fixed, 
 and brass be obtained. But one of the most 
 unequivocal characters of the oxide of zinc 
 is to dissolve it in vinegar, evaporate the so- 
 lution to dryness, and expose it to the flame 
 of a lamp, when it will burn with its pecu- 
 liar flame. 
 
 Oxide of Iron produces with microcosmic 
 salt or borax in the exterior flame, when cold, 
 a yellowish glass, which is blood-red while 
 hot. The protoxide forms with these fluxes 
 a green glass, which, by increasing the pro- 
 portion of the metal, passes through bottle- 
 green to black and opaque. The glass from 
 the oxide becomes green in the interior flame, 
 and is reduced to protoxide, and becomes 
 attractible by the magnet. When placed on 
 the wick of a candle, it burns with the crack- 
 ling noise peculiar to iron. 
 
 Oxide of Cobalt becomes black in the 
 exterior , and grey in the interior flame. A 
 small proportion forms with microcosmic salt 
 and with borax a blue glass, that with borax 
 being the deepest. By transmitted light the 
 glass is reddish. By farther additions of the 
 oxide it passes through dark blue to black. 
 The metal may be precipitated from the 
 dark blue glass by inserting a steel wire into 
 the mass while in fusion. It is malleable if 
 the oxide has been free from arsenic, and 
 may be collected by the magnet; and is dis- 
 tinguished from iron by the absence of any 
 crackling sound when placed on the wick of 
 a candle. 
 
 Oxide of Nickel becomes black at the 
 extremity of the exterior flame, and in the 
 interior greenish-grey. It is dissolved rea- 
 dily, and in large quantity, by microcosmic 
 salt. The glass, while hot, is a dirty dark 
 red, which becomes paler and yellowish as it 
 cools. After the glass has cooled, it requires 
 a large addition of the oxide to produce a 
 distinct change of colour. It is nearly the 
 same in the exterior and interior flame, being 
 slightly reddish in the latter. Nitre added 
 to the bead makes it froth, and it becomes 
 red-brown at first, and afterwards paler. It 
 is easily fusible with borax , and the colour 
 resembles the preceding. When this glass 
 is long exposed to a high degree of heat in 
 the interior flame, it passes from reddish to 
 blackish and opaque ; then blackish-grey, 
 ^nd translucent ; then paler reddish-grey, 
 
 and clearer; and, lastly, transparent; and 
 the metal is precipitated in small white me- 
 tallic globules. 'I he red colour seems here 
 to be produced by the entire fusion or solu- 
 tion of the oxide, the black by incipient re- 
 duction, and the grey by the minute metallic 
 particles before they combine and form small 
 globules, W hen a little soda is added to the 
 glass formed with borax, the reduction is 
 more easily effected, and the metal collects 
 itself into one single globule. When this 
 oxide contains iron, the glass retains its own 
 colour while hot, but assumes that of the 
 iron as it cools. 
 
 Oxide of Tin in form of hydrate, and in 
 its highest degree of purity, becomes yellow 
 when heated, then red, and when approach- 
 ing to ignition, black. If iron or lead be 
 mixed w ith it, the colour is dark brown when 
 heated. These colours become yellowish as 
 the substance cools. Upon charcoal in the 
 interior flame it becomes and continues white ; 
 and, if originally white and free from water, 
 it undergoes no change of colour by heating. 
 It is very easily reduced without addition, 
 but the reduction is promoted by adding a 
 drop of solution of soda or potash. 
 
 Oxide of Lead melts, and is very quick- 
 ly reduced, either without any addition, or 
 when fused with microcosmic salt or borax. 
 The glass not reduced is black. 
 
 Oxide of Copper is not altered by the 
 exterior flame, but becomes protoxide in the 
 interior. With both microcosmic salt and 
 borax it forms a yellow-green glass while 
 hot, but which becomes blue-green as it 
 cools. When strongly heated in the interior 
 flame, it loses its colour, and the metal is re- 
 duced. If the quantity of oxide is so small 
 that the green colour is not perceptible, its 
 presence may be detected by the addition of 
 a little tin, which occasions a reduction of 
 the oxide to protoxide, and produces an 
 opaque, red glass. If the oxide has been 
 fused with borax, this colour is longer pre- 
 served ; but if with microcosmic salt, it soon 
 disappears by a continuance of heat. 
 
 The copper may also be precipitated 
 upon iron, but the glass must he first satu- 
 rated with iron. Alkalis or lime promote 
 this precipitation. If the glass containing 
 copper he exposed to a smoky flame, the 
 copper is superficially reduced, and the glass 
 covered while hot with an iridescent pellicle, 
 which is not always permanent after cooling. 
 It is very easily reduced bv soda. Salts of 
 copper, when heated before the blow-pipe, 
 give a fine green flame. 
 
 Oxide of Mercury before the blow’-pipa 
 becomes black, and is entirely volatilized. In 
 this manner its adulteration may be disco- 
 vered. 
 
 The other metals may be reduced by 
 themselves, and mav be known by their ow# 
 peculiar characters. 
 
BLO 
 
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 * Under the particular mineral species their 
 habitudes with the blow* pipe are given. 
 
 Dr Robert Hare, Professor of Natural 
 Philosophy in the University of Philadel- 
 phia, published, in the first volume of 
 Bruce’s Mineralogical Journal, an account 
 of very intense degrees of heat, which he 
 had produced and directed on different bo- 
 dies, by a jet of flame, consisting of hydro- 
 gen and oxygen gases, in the proportion re- 
 quisite for forming water. The gases were 
 discharged from separate gasometers, and 
 were brought in contact only at a common 
 orifice or nozzle of small diameter, in which 
 their two tubes terminated. 
 
 In the first number of the Journal of Science 
 and Arts, is a description of a blow-pipe con- 
 trived by Mr Brooke, and executed by Mr 
 Newman, consisting of a strong iron box, with 
 a blow-pipe nozzle and stop-cock, for regulat- 
 ing the emission of air, which had been previ- 
 ously condensed into the box, by means of a 
 syringe screwed into its top. For this fine 
 invention we are ultimately indebted to Sir 
 II. Davy. John George Children, Esq. 
 first proposed to him this application of 
 Newman’s apparatus for condensed air or 
 oxygen, immediately after Sir II. had dis- 
 covered that the explosion from oxygen and 
 hydrogen would not communicate through 
 very small apertures ; and he first tried the 
 experiment himself with a fine glass capil- 
 lary tube.. The flame was not visible at the 
 end of this tube, being overpowered by the 
 brilliant star of the glass ignited at the aperture. 
 
 Dr Clarke, after being informed by Sir 
 FI. Davy that there would be no danger 
 of explosion in burning the compressed 
 gases, by suffering them to pass through a 
 fine thermometer tube, of an inch "dia- 
 meter, and three inches in length com- 
 menced a series of experiments, which were 
 attended with most important and striking 
 results.. By the suggestion of Professor 
 Cumimng, there has been enclosed in the 
 
 a smal1 cylinder of safety, about 
 half filled with oil, and stuffed at top with 
 fine wire gauze. The condensed gases must 
 pass from the large chamber into this small 
 one, up through the oil, and then across the 
 gauze, before they can reach the stop-cock 
 and blow-pipe nozzle. By this means, the 
 dangerous explosions which had occurred so 
 frequently, as would have deterred a less 
 intrepid experimenter than Dr Clarke are 
 now obviated. It is still, however, a ’pm- 
 dent precaution, to place a wooden screen 
 between the box and the operator. The 
 box is about five inches long, four broad, 
 and three deep The syringe is joined to 
 C top of the box by a stop-cock. Near 
 
 . h V ,p £ e : e " d of syringe, a screw nozzle 
 rs ixed in it at right angles, to which the 
 stop-cock of a bladder containing the mixed 
 gases may be attached. When we wish to 
 
 inject the gases, it is proper to draw the pis- 
 ton to the top, before opening the lower 
 stop-cock, lest the flame of the jet should 1 
 be sucked backward, and cause explosions 
 It is likewise necessary to see that no little 
 explosion has dislodged the oil from the 
 safety cylinder. A bubbling noise is heard 
 when the oil is present. A slight excess of 
 hydrogen is found to he advantageous. 
 
 Platinum is not only fused the instant it 
 is brought in contact with the flame of the 
 ignited gases, but the melted metal runs 
 down in drops. Dr Clarke has finally fused 
 the astonishing quantity of half an ounce at 
 once, by this jet of flame. In small quanti- 
 ties, it burns like iron wire. Palladium 
 melted like lead. Pure lime becomes a wax- 
 yellow vitrification. A lambent purple flame 
 always accompanies its fusion. The fusion 
 of magnesia is also attended with combus- 
 tion. Strontites fused with a flame, of an 
 intense amethystine colour, and after some 
 minutes there appeared a small oblong mass 
 of shining metal in its centre. Silex instant- 
 ly melted into a deep orange-coloured glass, 
 which was partly volatilized. Alumina 
 melted with great rapidity into globules of 
 a yellowish transparent glass. In these ex- 
 periments, supports of charcoal, platinum 
 or plumbago, were used with the same ef- 
 fect. The alkalis were fused and volatilized 
 the instant they came in contact with the flame, 
 v ith an e\ ident appearance of combustion. 
 
 The following refractory native com- 
 pounds were fused. Rock crystal, white 
 quartz, noble opal, flint, calcedony, Egyptian 
 jasper, ziicon, spinelle, sapphire, topaz, cy- 
 mophane, pycnite, andalusite, wavellite, ru- 
 bellite, hyperstene, cyanite, talc, serpentine, 
 hyalite, lazulite, gadolinite, leucite, apatite, 
 Peruvian emerald, Siberian beryl, potstone] 
 hydrate of magnesia, subsulphate of alu- 
 mina, pagodite of China, Iceland spar, com- 
 mon chalk, Arragonite, diamond. 
 
 Gold exposed on pipe-clay to the flame, was 
 surrounded with a halo of a lively rose colour, 
 and soon volatilized. Stout iron wire was 
 rapidly burned. Plumbago Was fused into 
 a magnetic bead. Red oxide of titanium 
 fused, with partial combustion. Red ferri- 
 ferous copper, blende, oxides of platinum, 
 grey oxide of manganese, crystallized oxide 
 ot manganese, wolfram, sulphuret of molyb- 
 denum, siliceo- calcareous titanium, black 
 oxide of cobalt, pechblende, siliciferous 
 oxule of cerium, chromate of iron, and ore 
 of iridium, were all, except the second last, 
 reduced to the metallic state, with peculiar, 
 and for the most part, splendid phenomena. 
 Jade, mica, amianthus, asbestus, melt like 
 wax before this potent flame. 
 
 But the two most surprising of Dr Clarke’s 
 experiments were, the fusion of the meteoric 
 stone from 1 Aigle, and its conversion into 
 it on anc the reduction of barium, from the 
 eartli barytes and its salts. Some nitrate of 
 
BLO 
 
 BOL 
 
 barytes, put into a cavity, at the end of a 
 stick ot charcoal, was exposed to the ignited 
 gas. It fused with vehement ebullition, and 
 metallic globules were clearly discernible in 
 the midst of the boiling fluid, suddenly 
 forming, and as suddenly disappearing. On 
 checking the flame, the cavity of the char- 
 coal was studded over with innumerable 
 globules of a metal of the most brilliant 
 lustre and whiteness, resembling the purest 
 platinum after fusion. Some globules were 
 detached and dropped into naphtha, where 
 they retained for some time their metallic 
 aspect. Their specific gravity was 4.00. 
 
 Or Clarke fused together a bead of barium 
 and one of platinum, each weighing one 
 grain. The bronze coloured alloy weighed 
 two grains, proving a real combination. The 
 alloy of barium and iron is black and brittle. 
 Barium is infusible before the blow-pipe, 
 per se; but with borax it dissolves like bary- 
 tes, with a chrysolite green colour, and dis- 
 closing metallic lustre to the file. The al- 
 loy of barium and copper is of a Vermillion 
 colour. When silex is mixed into a paste 
 with lamp-oil, and exposed on a cavity of 
 charcoal to the flame, it runs readily into 
 beads of various colours. If these be heat- 
 ed in contact with iron, an alloy of silicium 
 and iron is obtained, which discloses a me- 
 tallic surface to the file. Magnesium and 
 iron may be alloyed in the same way. 
 
 By using from two to three volumes of 
 hydrogen to one of oxygen, and directing 
 the flame on pure barytes, supported on 
 pincers of slate, Dr Clarke has more lately 
 revived barium in larger quantities, so as to 
 exhibit its qualities for some time. It gra- 
 dually, however, passes again into pure 
 barytes. Muriate of rhodium, placed in a 
 charcoal crucible, yielded the metal rho* 
 diurn, brilliant like platinum. It is mal- 
 leable on the anvil. Oxide of uranium, 
 from Cornwall, w r as also reduced to the me- 
 tallic state. 
 
 We shall conclude this article by the 
 following experiment of Dr Clarke’s: If 
 you take two pieces 'of lead foil and pla- 
 tinum foil of equal dimensions, and roll 
 them together, and place the roll upon char- 
 coal, and direct the flame of a candle cau- 
 tiously towards the edges of the roll, at 
 about a red heat, the two metals will com- 
 bine with a sort of explosive force, scattering 
 their melted particles off the charcoal, and 
 emitting light and heat in a very surprising 
 manner. Then there will remain upon the 
 charcoal a film of glass ; which by further 
 urging the flame towards it, will melt into 
 a highly transparent globule of a sapphire 
 blue colour. Also, if the platinum and lead 
 be placed beside each other, as soon as the 
 platinum becomes heated, you will observe 
 a beautiful play of blue light upon the sur- 
 face of the lead, becoming highly iridescent 
 before it melts, * 
 
 * Blue (Prussian). A combination of 
 oxide ot iron with an acid distinguished by 
 the name ot the Jerro-prussic* See Acid 
 (Prussic), and Iron.* 
 
 Blue (Saxon). The best Saxon blue co- 
 lour may be given by the following composi- 
 tion : 
 
 Mix one ounce of the best powdered in- 
 digo with four ounces of sulphuric acid, in 
 a glass bottle or matrass, and digest it for 
 one hour with the heat of boiling water, 
 shaking the mixture at different times : then 
 add twelve ounces of water to it, and stir 
 the whole well, and w-hen grown cold, filter 
 it. 
 
 Mr Poerner adds one ounce of good dry 
 potash at the end of twenty-four hours, and 
 lets this stand as much longer, before he di- 
 lutes it with water. The cloth should be 
 prepared with alum and tartar. 
 
 Bog Ores. See Ores of Iron. 
 
 * Bole. A massive mineral, having a per- 
 fectly conchoidal fracture, a glimmering in- 
 ternal lustre, and a shining streak. Its co- 
 lours are yellow-red, and brownish-black, 
 when it is called mountain soap. It is trans- 
 lucent, or opaque. Soft, so as to be easily cut, 
 and to yield to the nail. It adheres to the 
 tongue, has a greasy feel, and falls to pieces 
 in water. Sp. grav. 1.4 to 2. It may be 
 polished. If it be immersed in water after 
 it is dried, it falls asunder with a crackling 
 noise. It occurs in wacke and basalt, in 
 Silesia, Ilessia, and Sienna in Italy, and also 
 in the cliffs of the Giant’s Causeway, Ire- 
 land. The black variety is found in the 
 trap rocks of the Isle of Sky.* 
 
 Bolognian Stone. Lemery reports, that 
 an Italian shoemaker, named Vincenzo Cas- 
 ciarolo, first discovered the phosphoric pro- 
 perty of the Bolognian stone. It is the 
 ponderous spar, or native sulphate of ba- 
 rytes. 
 
 If it be first heated to ignition, then finely 
 powdered, and made into a paste with mu- 
 cilage ; and this paste, divided into pieces a 
 quarter of an inch thick, and dried in a mo- 
 derate heat, be exposed to the heat of a w ind 
 furnace, by placing them loose in the midst 
 of the charcoal ; a pyrophorus will be ob- 
 tained, which, after a few minutes’ exposure 
 to the sun’s rays, will give light enough in 
 the dark to render the figures on the dial- 
 plate of a watch visible. 
 
 * Boletic Acid. See Acid (Boletic).* 
 
 * Boletus. A genus of mushroom, of 
 which several species have been subjected to 
 chemical examination by MM. Braconnot and 
 Bouillon La Grange. 
 
 1. Boletus juglandis, in 1260 parts, yield- 
 ed, 1118.3 water, 95.68 fungin, 18 animal 
 matter insoluble in alcohol, 12 osmazome, 
 
 7.2 vegetable albumen, 6 fungate of potash* 
 
 1.2 adipoccre, 1.12 oily matter, 0.5 sugar of 
 mushrooms, and a trace of phosphate of pot- 
 ash. 
 
BON 
 
 BON 
 
 2. Boletus laricis , used on the continent in 
 medicine, under the name of agaric . It is 
 in white, light friable pieces, of which the 
 outside is like dark- coloured leather. Its 
 taste at first sweetish, soon passes into bitter- 
 ness and acrimony. Its infusion in water is 
 yellowish, sweet tasted, and reddens veget- 
 able blues. It contains muriate of potash, 
 sulphate of lime, and sulphate of potash. 
 Water boiled on agaric, becomes gelatinous 
 on cooling ; and if the water be dissipated 
 by evaporation, ammonia is exhaled by the 
 addition of lime. Resin of a yellow colour, 
 with a bitter sour taste, may be extracted 
 from it by alcohol. It yields benzoic acid, 
 by Scheele’s process. The strong acids act 
 with energy on agaric, and the nitric evolves 
 oxalic acid. Fixed alkalis convert it into a 
 red jelly, which emits an ammoniacal 
 smell. 
 
 5. Boletus igniarius is found in most 
 countries, and particularly in the Highlands 
 of Scotland, on the trunks of old ash and 
 other trees. The French and Germans pre- 
 pare it abundantly for making tinder , by 
 boiling in water, drying, beating it, and 
 steeping it in a solution of nitre, and again 
 drying it. In France it is called amadou, in 
 this country German tinder. It has been 
 recommended in surgery, for stopping hae- 
 morrhage from wounds. It imparts to wa- 
 ter a deep brown colour, and an astringent 
 taste. The liquid consists of sulphate of 
 lime, muriate of potash, and a brown extrac- 
 tive matter. When the latter is evaporated 
 to dryness, and burned, it leaves a good deal 
 of potash. Phosphates of lime and mag- 
 nesia, with some iron, are found in the inso- 
 luble matter. Alkalis convert it with some 
 difficulty into a soapy liquid, exhaling am- 
 monia. No benzoic acid, and little animal 
 matter, are found in this boletus. 
 
 4. Boletus pseudo- igniarius, yielded to 
 Braconnot, water, fungin, a sweetish mucil- 
 age, boletate of potash, a yellow fatly mat- 
 ter, vegetable albumen, a little phosphate of 
 potash, acetate of potash, and fungic acid 
 combined with a base. 
 
 5. Boletus viscidus was found by Bracon- 
 not to be composed, in a great measure, of 
 an animal mucus, which becomes cohesive 
 by heat. * 
 
 Bone. The bones of men and quadru- 
 peds owe their great firmness and solidity 
 to a considerable portion of the phosphate 
 of lime which they contain. When these 
 are rasped small, and boiled in water, they 
 afford gelatinous matter, and a portion of fat 
 or oil, which occupied their interstices. 
 
 * Calcined human bones, according to 
 Berzelius, are composed, in 100 parts, of 
 81.9 phosphate of lime, 5 fluate of lime, 10 
 lime, 1.1 phosphate of magnesia, 2 soda, and 
 2 carbonic acid. 100 parts of bones by cal- 
 cination are reduced to 63. Fourcroy and 
 
 Vauquelin found the following to be tho 
 composition of 100 parts of ox bones : 51 
 solid gelatin, 37.7 phosphate of lime, 10 car- 
 bonate of lime, and 1.5 phosphate of magne- 
 sia ; but Berzelius gives the following as 
 their constituents : 33.3 cartilage, 55.35 
 
 phosphate of lime, 5 fluate of lime, 5.85 
 carbonate of lime, 2.05 phosphate of magne- 
 sia, and 2.45 soda, with a little common 
 salt. 
 
 About l-30th of phosphate of magnesia 
 was obtained from the calcined bones of 
 fowls, by Fourcroy and Vauquelin. When 
 the enamel of teeth, rasped down, is dissolved 
 in muriatic acid, it leaves no albumen, like 
 the other bones. Fourcroy and Vauquelin 
 state its components to be, 27. 1 gelatin and 
 water, 72.9 phosphate of lime. Messrs 
 Hatchett and Pepys rate its composition at 
 78 phosphate of lime, 6 carbonate of lime, 
 and 16 water and loss. Berzelius, on the 
 other hand, found only 2 per cent of com- 
 bustible matter in teeth. The teeth of adults, 
 by Mr Pepys, consist of 64 phosphate of 
 lime, 6 carbonate of lime, 20 cartilage, and 
 10 water or loss. The fossil bones from 
 Gibraltar, are composed of phosphate of 
 lime and carbonate, like burnt bones. Much 
 difference of opinion exists with regard to 
 the existence of fluoric acid in the teeth of 
 animals, some of the most eminent chemists 
 taking opposite sides of the question. It ap- 
 pears that bones buried for many centuries, 
 still retain their albumen, with very little 
 diminution of its quantity.* 
 
 Fourcroy and Vauquelin discovered phos- 
 phate of magnesia in all the bones they exa- 
 mined, except human bones. The bones of 
 the horse and sheep afford about l-36th of 
 phosphate of magnesia ; those of fish nearly 
 the same quantity as those of the ox. They 
 account for this by observing, that phosphate 
 of magnesia is found in the urine of man, 
 but not in that of animals, though both 
 equally take in a portion of magnesia with 
 their food. 
 
 The experiments of Mr Hatchett show, 
 that the membranous or cartilaginous sub- 
 stance, which retains the earthy salts within 
 its interstices, and appears to determine the 
 shape of the bone, is albumen. Mr Hat- 
 chett observes, that the enamel of tooth is 
 analogous to the porcellanous shells, while 
 mother of pearl approaches in its nature to 
 tt*ue bone. 
 
 A curious phenomenon with respect to 
 bones is the circumstance of their acquiring 
 a red tinge, when madder is given to ani- 
 mals with their food. The bones of young 
 pigeons will thus be tinged of a rose colour 
 in twenty-four hours, and of a deep scarlet 
 in three days ; but the bones of adult ani- 
 mals will be a fortnight in acquiring a rose 
 colour. The bones most remote from tho 
 heart are the longest in acquiring this tinge. 
 
 
BON 
 
 BOR 
 
 Mr Gibson informs us, that extract of log- 
 wood too, in considerable quantity, will tinge 
 the bones of young pigeons purple. On de- 
 sisting from the use of this food, however, 
 the colouring matter is again taken up into 
 the circulation, and carried off, the bones re- 
 gaining their natural hue in a short time. 
 It was said by Du Hamel, that the bones 
 would become coloured and colourless in 
 concentric layers, if an animal were fed al- 
 ternately one week with madder, and one 
 week without ; and hence he inferred, that 
 the bones were formed in the same manner 
 as the woody parts of trees. But he was 
 mistaken in the fact ; and indeed had it been 
 true, witli the inference he naturally draws 
 from it, the bones of animals must have been 
 out of all proportion larger than they are at 
 present. 
 
 Bones are of extensive use in the arts. In 
 their natural state, or dyed of various co- 
 lours, they are made into handles of knives 
 and forks, and numerous articles of turnery. 
 We have already noticed the manufacture of 
 volatile alkali from bones, the coal of which 
 forms bone black ; or, if they be afterwards 
 calcined to whiteness in the open air, they 
 constitute the bone ashes, of which cupels 
 are made, and which, finely levigated, are 
 used for cleaning articles of paste, and some 
 other trinkets, by the name of burnt harts- 
 horn. The shavings of hartshorn, which is 
 a species of bone, afford an elegant jelly ; 
 and the shavings of other bones, of which 
 those of the calf are the best, are often em- 
 ployed in their stead. 
 
 On this principle, Mr Proust has recom- 
 mended an economical use of bones, parti- 
 cularly with a view to improve the sub- 
 sistence of the soldier. lie first chops them 
 into small pieces, throws them into a kettle 
 of boiling water, and lets them boil about a 
 quarter of an honr. When this has stood 
 till it is cold, a quantity of fat, excellent for 
 culinary purposes when fresh, and at any 
 time fit for making candles, may be taken 
 off the liquor. This in some instances 
 amounted to an eighth, and in others even 
 to a fourth, of the weight of the bones. 
 After this the bones may be ground, and 
 boiled in eight or ten times their weight of 
 water* of which that already used may form 
 a part, till about half is wasted, when a very 
 nutritious jelly will be obtained. The boiler 
 should not be of copper, as this metal is 
 easily dissolved by the jelly ; and the cover 
 should fit very tight, so that the heat may be 
 greater than that of boiling water, but not 
 equal to that of Papin’s digester, which 
 would give it an empyreuma. The bones 
 of meat that have been boiled, are nearly as 
 productive as fresh bones; but Dr Young 
 found those of meat that had been roasted 
 afforded no jelly, at least by simmering, or 
 gentle boiling. 
 
 * Boracic Acid. See Acid (Boracic). 
 This acid has been found native on the 
 edges of hot springs, near Sapo in the terri- 
 tory of Florence ; also attached to specimens 
 from the Lipari Islands, and from Monte 
 ltotondo, to the west of Sienna. It is in 
 small pearly scales, and also massive, fusing 
 at the flame of a candle into a glassy glo- 
 bule. It consists, by Klaproth’s analysis, of 
 86 boracic acid, 1 1 ferruginous sulphate of 
 manganese, and 5 sulphate of lime. * 
 
 *■ Boracitk. Borate of magnesia. It is 
 found in cubic crystals, whose fracture is 
 uneven, or imperfectly conchoidal. Shining 
 greasy lustre ; translucent ; so hard as t& 
 strike lire with steel ; of a yellowish, grey- 
 ish, or greenish- white. Sp. grav. 2.56. It 
 becomes electric by heat; and the diagonally 
 opposite solid angles, are in opposite electri- 
 cal states. It fuses into a yellow enamel, 
 after emitting a greenish light. 
 
 Vauquelin’s analysis gives, 85.4 boracic 
 acid, and 16.6 magnesia. It occurs in gypsum 
 in the Ivalkberg in the duchy of Brunswick, 
 and at Segeberg, near Kiel in Holstein.* 
 
 Borax. The origin of borax was for a 
 long time unknown in Europe. Mr Grill 
 Abrahamson, however, sent some to Sweden 
 in the year 1772, in a crystalline form, as 
 dug out of the earth in Thibet, where it is 
 called Pounnxa, Mypoun, and Iiouipoun : 
 it is said to have been also found in Saxony, 
 in some coal pits. 
 
 It does not appear that borax was known 
 to the ancients, their chrysocolla being a very 
 different substance, composed of the rust of 
 copper, triturated with urine. The word 
 borax is found for the first time in the works 
 of Geber. 
 
 Borax is not only found in the East, hut 
 likewise in South America. Mr Anthony 
 Carera, a physician established at Potosi, in- 
 forms us, that this salt is abundantly obtain- 
 ed at the mines of Riquintipa, and those in 
 the neighbourhood of Escapa, where it is 
 used by the natives- in the fusion of copper 
 ores. 
 
 The purification of borax by the Vene- 
 tians and the Hollanders, was for a long 
 time kept secret. Chaptal finds, after try- 
 ing all the processes in the large wav, that 
 the simplest method consists in boiling the 
 borax strongly, and for a long time, with 
 water. This solution being filtered, affords 
 by evaporation crystals, which are somewhat 
 foul, but may be purified by repeating the 
 operation. 
 
 Purified borax is white, transparent, ra- 
 ther greasy in its fracture, affecting the form 
 of six-sided prisms, terminating in three- 
 sided or six-sided pyramids. Its taste is 
 styptic ; it converts syrup of violets to a 
 green ; and when exposed to heat, it sw ells 
 up, boils, loses its water of crystallization, 
 and becomes converted into a porous, white, 
 
BOT 
 
 BRA 
 
 opaque mass, commonly called Calcined 
 Borax. A stronger heat brings it into a 
 state of quiet fusion ; but the glassy sub- 
 stance thus afforded, which is transparent, 
 and of a greenish-yellow colour, is soluble in 
 water, and effloresces in the air. It requires 
 about eighteen times its weight of water to 
 dissolve it at the temperature of sixty de- 
 grees of Fahrenheit ; but water at the boil- 
 ing heat dissolves three times this quantity. 
 Its component parts, according to Kirwan, 
 are, boracic acid 34, soda 17, water 47. 
 For an account of the neutral borate of soda, 
 and other compounds of this acid, see Acid 
 (Boracic). 
 
 Borax is used as an excellent flux in do- 
 cimastic operations. It enters into the 
 composition of reducing fluxes, and is of the 
 greatest use in analysis by the blow-pipe. It 
 may be applied with advantage in glass ma- 
 nufactories ; for when the fusion turns out 
 bad, a small quantity of borax re-establishes 
 it. It is more especially used in soldering ; 
 it assists the fusion of the solder, causes it to 
 flow, and keeps the surface of the metals in 
 a soft or clean state, which facilitates the 
 operation. It is scarcely of any use in me- 
 dicine. Its acid, called Sedative Salt, is 
 used by some physicians ; and its name 
 sufficiently indicates its supposed effects. 
 Mixed with shell lac, in the proportion of 
 one part to five, it renders the lac soluble by 
 digestion in water heated near boiling. 
 
 * Boron. The combustible basis of 
 boracic acid, which see.* 
 
 * Botany Bay Resin exudes spontaneous- 
 ly from the trunk of the acarois resinifera of 
 New Holland, and also from the wounded 
 bark. It soon solidifies by the sun, into 
 pieces of a yellow colour of various sizes. 
 It pulverizes easily w ithout caking ; nor 
 does it adhere to the teeth when chewed. It 
 has a slightly sweet astringent taste. It 
 melts at a moderate heat. When kindled, 
 it emits a wdiite fragrant smoke. It is in- 
 soluble in water, but imparts to it the flavour 
 of storax. Out of nine parts, six are soluble 
 in w’ater, and astringent to the taste ; and 
 two parts are woody fibre.* 
 
 * Botryolite is a mineral wdiich occurs 
 in mamillary concretions, formed of concen- 
 tric layers ; and also in botroidal masses, 
 white and earthy. Its colour is pearl and 
 yellowish-grey, with sometimes reddish-white 
 concentric stripes. It has a rough and dull 
 surface, and a pearly lustre internally. Frac- 
 ture delicate stellular fibrous. Translucent 
 on the edges. Brittle, but moderately hard. 
 Sp. gr. 2.85. It is composed of 36 silica, 
 
 39.5 boracic acid, 1 ,3.5 lime, 1 oxide of iron, 
 
 6.5 w r ater. It froths and fuses before the 
 blow-pipe into a white glass. It is found 
 in a bed of gneiss, near Arendahl in Nor- 
 way. It is regarded by some as a variety of 
 Datholite. * 
 
 * Bournonite. An antimonial sulphuret 
 of lead.* 
 
 Bovey Coal. This is of a brown or 
 brownish- black colour, and lamellar texture ; 
 the laminae are frequently flexible when first 
 dug, though generally they harden wdien ex- 
 posed to the air. It consists of wood pene- 
 trated with petroleum or bitumen, and fre- 
 quently contains pyrites, alum, and vitriol ; 
 its ashes afford a small quantity of fixed al- 
 kali, according to the German chemists ; but 
 according to Mr Mills, they contain none. 
 By distillation it yields an ill-smelling liquor, 
 mixed with volatile alkali and oil, part ol 
 which is soluble in alcohol, and part insolu- 
 ble, being of a mineral nature. 
 
 It is found in England, France, Italy, 
 Switzerland, Germany, Iceland, &c. 
 
 * Boyle’s Fuming Liquor. Hydroguret- 
 ted sulphuret of ammonia.* 
 
 Brain of Animals. The brain has long 
 been known to anatomists ; but it is only of 
 late years that chemists have paid it any at- 
 tention. It is a soft white substance, of a 
 pulpy saponaceous feel, and little or no 
 smell. Exposed to a gentle heat, it loses 
 moisture, shrinks to about a fourth of its 
 original bulk, and becomes a tenacious mass 
 of a greenish-brown colour. When com- 
 pletely dried, it becomes solid, and friable 
 like old cheese. Exposed to a strong heat, 
 it gives out ammonia, sw ells up, melts into 
 a black pitchy mass, takes fire, burns with 
 much flame and a thick pungent smoke, and 
 leaves a coal difficult of incineration. 
 
 In its natural state, or moderately dried, 
 it readily forms an emulsion by trituration 
 with water, and is not separated by filtra- 
 tion. This solution lathers like soap-suds, 
 but does not turn vegetable blue colours 
 green. Ileat throws down the dissolved 
 brain in a flocculent form, and leaves an al- 
 kaline phosphate in solution. Acids separate 
 a white coagulum from it ; and form salts 
 with bases of lime, soda, and ammonia. Al- 
 cohol too coagulates it. 
 
 Caustic fixed alkalis act very powerfully 
 on brain even cold, evolving much ammonia 
 and caloric. With heat they unite wfith it 
 into a saponaceous substance. 
 
 The action of alcohol on brain is most 
 remarkable. When Fourcroy treated it 
 four times in succession with twice its 
 weight of well rectified alcohol, boiling it 
 a quarter of an hour each time, in a long- 
 necked matrass with a grooved stopple, the 
 three first portions of alcohol, decanted 
 boiling, deposited by cooling brilliant la- 
 mina? of a yellowish-white colour, diminish- 
 ing in quantity each time. The fourth de- 
 posited very little. The cerebral matter had 
 lost 5-8ths of its weight ; and by the spon- 
 taneous deposition, and the subsequent eva- 
 poration oi the alcohol, half of this was re- 
 
BRA 
 
 BRA 
 
 covered in needly crystals, large scales, or 
 granulated matter. The other half was lost 
 by volatilization. This crystallized sub- 
 stance, ot a fatty appearance, was aggluti- 
 nated into a paste under the linger ; but did 
 not melt at the heat of boiling water, being 
 merely softened. At a higher temperature 
 it suddenly acquired a blackish- yellow co- 
 lour, and exhaled during fusion an empyreu- 
 matic and ammoniacal smell. This shews 
 that it is not analogous to spermaceti, or to 
 adipocere ; but it seems more to resemble 
 the fat lamellated crystals contained in some 
 biliary calculi, which, however, do not soften 
 at a heat of 23*1° F. or become ammoniacal 
 and empyreumatic at this temperature, as the 
 crystalline cerebral oil does. 
 
 A portion of this concrete oil, separated 
 from the alcohol by evaporation in the sun, 
 formed a granulated pellicle on its surface, 
 of a consistence resembling that of soft soap. 
 It was of a yellower colour than the former, 
 and had a marked smell of animal extract, 
 and a perceptible saline taste. It was diffu- 
 sible in water, gave it a milky appearance, 
 reddened litmus paper, and did not become 
 really oilv, or fusible after the manner of an 
 oil, till it had given out ammonia, and depo- 
 sited carbon, by the action of fire or caustic 
 alkalis. 
 
 A similar action of alcohol on the brain, 
 nerves, and spinal marrow, is observed after 
 long maceration in it cold, when they are 
 kept as anatomical preparations. 
 
 * Vauquelin analyzed the brain and found 
 the following constituents in 100 parts: 80 
 water, 4.55 white fatty matter, 0.7 reddish 
 fatty matter, 7. albumen, i.12 osmazome, 
 1.5 phosphorus, 5.15 acids, salts, and sul- 
 phur. The medulla oblongata and nerves 
 have the same chemical composition.* 
 
 The spontaneous change that brain under- 
 goes in certain situations, has already been 
 noticed under the article Adipocere. 
 
 Brandy. This well known fluid is the 
 spirit distilled from wine. The greatest 
 quantities are made in Languedoc, where 
 this manufacture, upon the whole so perni- 
 cious to society, first commenced. It is ob- 
 tained by distillation in the usual method, 
 by a still, which contains five or six quintals 
 of wine, and has a capital and worm tube 
 applied. Its peculiar flavour depends, no 
 doubt, on the nature of the volatile princi- 
 ples, or essential oil, which come over along 
 with it, and likewise, in some measure, upon 
 the management of the fire, the wood of the 
 cask in which it is kept, &c. It is said, that 
 our rectifiers imitate the flavour of brandy, 
 by adding a small proportion of nitrous ether 
 to the spirit of malt or molasses. See Al- 
 cohol. 
 
 Brass. An elegant yellow-coloured com- 
 pound metal, consisting of copper combined 
 with about one-third of its weight of zint;. 
 
 The best brass is made by cementation of 
 calamine, or the ore of zinc, with granulated 
 copper. See Copper. 
 
 Brassica Rubra. The red cabbage af- 
 fords a very excellent test both for acids and 
 aikalis; in which it is superior to litmus, be- 
 ing naturally blue, turning green with alka- 
 lis, and red w'ith acids. * The minced leaves 
 may be dried before the fire till they become 
 quite crisp, when they ought to be put into 
 a bottle, and corked up. Hot water pour- 
 ed on a little of the dried leaves, affords an 
 extemporaneous test liquor for acids and al- 
 kalis. The purple petals of violets may be 
 preserved in the same way ; as well as those 
 of the pink coloured lychnis , and scarlet 
 rose. * 
 
 Brazil Wood. The tree that affords 
 this wood, the caesalpina crista, is of the 
 growth of the Brazils in South America, 
 and also of the Isle of France, Japan, and 
 elsewhere. It is chiefly used in the process 
 of dyeing. The wood is considerably hard, 
 is capable of a good polish, and is so heavy 
 that it sinks in water. Its colour is pale 
 when newly cut, but it becomes deeper by 
 exposure to the air. The various specimens 
 differ in the intensity of their colour ; but 
 the heaviest is reckoned the most valuable. 
 It has a sweetish taste when chewed, and is 
 distinguished from red sanders, or sandal, 
 by its property of giving out its colour with 
 water, which this last does not. 
 
 If the brazil wood be boiled in water for 
 a sufficient time, it communicates a tine red 
 colour to that fluid. The residue is very 
 dark coloured, and gives out a considerable 
 portion of colouring matter to a solution of 
 alkali. Alcohol extracts the colour from 
 brazil wood, as does likewise the volatile al- 
 kali ; and both these are deeper than the 
 aqueous solution. The spirituous tincture, 
 according to Dufay, stains warm marble of a 
 purplish red, which on increasing the heat 
 becomes violet; and if the stained marble 
 be covered with wax, and considerably heat- 
 ed, it changes through all the shades of 
 brown, and at last becomes fixed of a choco- 
 late colour. 
 
 * The colours imparted to cloth by brazil 
 wood are of little permanence. A very mi- 
 nute portion of alkali, or even soap, darkens 
 it into purple. Hence paper stained with it 
 may be used as a test of saturation with the 
 salts. Alum added to the decoction of this 
 wood, occasions a fine crimson-red precipi- 
 tate, or lake, which is increased in quantity 
 by the addition of alkali to the liquor. The 
 crimson-red colour is also precipitated by 
 muriate of tin ; but it is darkened by the 
 salts of iron. Acids change it to yellow, 
 from which, however, solution of tin restores 
 it to its natural hue. The extract of brazil 
 wood reddens litmus paper, by depriving it 
 of the alkali wdiich darkens it. * 
 
BRE 
 
 BRE 
 
 Bread. I am net acquainted with any 
 set of experiments regularly instituted and 
 carried into effect, for ascertaining what 
 happens in the preparation of bread. Fari- 
 naceous vegetables are converted into meal 
 by trituration, or grinding in a mill ; and 
 when the husk or bran has been separated 
 by sifting or bolting, the powder is called 
 flour. This is composed of a small quantity 
 of mucilaginous saccharine matter, soluble 
 in cold w ater, much starch, which is scarcely 
 soluble in cold water, but combines with that 
 fluid by heat, and an adhesive gray substance 
 insoluble in water, alcohol, oil, or ether, and 
 resembling an animal substance in many of 
 its properties. See Wheat, Starch, Glu- 
 ten (Vegetable), Mucilage. 
 
 When flour is kneaded together with 
 water, it forms a tough paste, containing 
 these principles very little altered, and not 
 easily digested by the stomach. The action 
 of heat produces a considerable change in 
 the gluten, and probably in the starch, ren- 
 dering the compound more easy to masti- 
 cate, as well as to digest. Hence the first 
 approaches towards the making of bread 
 consisted in parching the corn, either for 
 immediate use as food, or previous to its tri- 
 turation into meal; or else in baking the 
 flour into unleavened bread, or boiling it 
 into masses more or less consistent ; of all 
 which we have sufficient indications in the 
 histories of the earlier nations, as w^ell as in 
 the various practices of the moderns. It 
 appears likewise from the Scriptures, that 
 the practice of making leavened bread is of 
 very considerable antiquity ; but the addi- 
 tion of yeast, or the vinous ferment, now 
 so generally used, seems to be of modern 
 date. 
 
 Unleavened bread in the form of small 
 cakes, or biscuit, is made for the use of ship- 
 ping in large quantities ; but most of the 
 bread used on shore is made to undergo, 
 previous to baking, a kind of fermentation, 
 which appears to be of the same nature as 
 the fermentation of saccharine substances; 
 but is checked and modified by so many 
 circumstances, as to render it not a little 
 difficult to speak with certainty and preci- 
 sion respecting it. See Fermentation. 
 
 When dough or paste is left to undergo a 
 spontaneous decomposition in an open ves- 
 sel, the various parts of the mass are diffe- 
 rently affected, according to the humidity, 
 the thickness or thinness of the part, the 
 vicinity or remoteness of fire, and other 
 circumstances less easily investigated. The 
 saccharine part is disposed to become con- 
 verted into alcohol, the mucilage has a ten- 
 dency to become sour and mouldy, while 
 the gluten in all probability verges toward 
 the putrid state. An entire change in the 
 chemical attractions of the several compo- 
 
 gressive manner, not altogether the same in 
 the internal and more humid parts as in the 
 external parts, which not only become dry 
 by simple evaporation, but are acted upon 
 by the surrounding air. The outside may 
 therefore become mouldy or putrid, while 
 the inner part may be only advanced to an 
 acid state. Occasional admixture of the 
 mass w r ould of course not only produce some 
 change in the rapidity of this alteration, but 
 likewise render it more uniform throughout 
 the whole. The effect of this commencing 
 fermentation is found to be, that the mass 
 is rendered more digestible and light ; by 
 which last expression it is understood, that 
 it is rendered much more porous by the 
 disengagement of elastic fluid, that sepa- 
 rates its parts from each other, and greatly 
 increases its bulk. The operation of baking 
 puts a stop to this process, by evaporating 
 great part of the moisture which is requi- 
 site to favour the chemical attraction, and 
 probably also by still farther changing the 
 nature of the component parts. It is then 
 bread. 
 
 Bread made according to the preceding 
 method will not possess the uniformity 
 which is requisite, because some parts may 
 be mouldy, while others are not yet suffi- 
 ciently changed from the state of dough. 
 The same means are used in this case as 
 have been found effectual in promoting the 
 uniform fermentation of large masses. This 
 consists in the use of a leaven or ferment, 
 which is a small portion of some matter of 
 the same kind, but in a more advanced stage 
 of the fermentation. After the leaven has 
 been well incorporated by kneading into 
 fresh dough, it not only brings on the fer- 
 mentation with greater speed, but. causes it 
 to take place in the whole of the mass at the 
 same time ; and as soon as the dough has by 
 this means acquired a due increase of bulk 
 from the carbonic acid, which endeavours to 
 escape, it is judged to be sufficiently fer- 
 mented, and ready for the oven. 
 
 The fermentation by means of leaven or 
 sour dough is thought to be of the acetous 
 kind, because it is generally so managed that 
 the bread has a sour flavour and taste. But 
 it has not been ascertained that this acidity 
 proceeds from true vinegar. Bread raised 
 by leaven is usually made of a mixture of 
 wheat and rye, not very accurately cleared 
 of the bran. It is distinguished by the name 
 of rye bread ; and the mixture of these tw'O 
 kinds of grain is called bread-corn, or mes- 
 lin, in many parts of the kingdom, where it 
 is raised on one and the same piece of 
 ground, and passes through all the processes 
 of reaping, threshing, grinding. &c. in this 
 mixed state. 
 
 Yeast or barm is used as the ferment for 
 the finer kinds of bread. This is the muci- 
 laginous froth which rises to the surface of 
 
BRE 
 
 BRE 
 
 beer in its first stage of fermentation.- When 
 it is mixed with dough, it produces a much 
 more speedy and effectual fermentation than 
 that obtained by leaven, and the bread is accor- 
 dingly much lighter, and scarcely ever sour. 
 
 I he fermentation by yeast seems to be almost 
 certainly of the vinous or spirituous kind. 
 
 Bread is much more uniformly miscible 
 with water than dough ; and on this cir- 
 cumstance its good qualities most probably 
 do in a great measure depend. 
 
 A very great number of processes are 
 used by cooks, confectioners, and others, to 
 make cakes, puddings, and other kinds of 
 bread, in which different qualities are re- 
 quired. Some cakes are rendered brittle, or 
 as it is called short, by an admixture of sugar 
 or of starch. Another kind of brittleness is 
 given by the addition of butter or hit. White 
 of egg, gum- water, isinglass, and other ad- 
 hesive substances, are used, when it is in- 
 tended that the effect of fermentation shall 
 expand the dough into an exceedingly porous 
 mass. Dr Percival has recommended the 
 addition of salep, or the nutritious powder of 
 the orchis root. He says, that an ounce of 
 salep, dissolved in a quart of water, and 
 mixed with two pounds of flour, two ounces 
 of yeast, and eighty grains of salt, produced a 
 remarkably good loaf, weighing three pounds 
 two ounces ; while a loaf made of an equal 
 quantity of the other ingredients, without 
 the salep, weighed but two pounds twelve 
 ounces. If the salep be in too large quan- 
 tity, however, its peculiar taste will be dis- 
 tinguishable in the bread. The farina of 
 potatoes likewise, mixed with wheaten flour, 
 makes very good bread. The reflecting che- 
 mist will receive considerable information on 
 this subject from an attentive inspection of 
 the receipts to be met with in treatises of 
 cooking and confectionary. 
 
 * Mr Accurn, in his late Treatise on Cu- 
 linary Poisons, states, that the inferior kind 
 of flour which the London bakers generally 
 use for making loaves, requires 1 - the addition 
 of alum to give them the white appearance of 
 bread made from fine flour. “ The baker’s 
 flour is very often made of the worst kinds 
 of damaged foreign wheat, and other cereal 
 grains mixed with them in grinding the 
 wheat into flour. In this capital, no fewer 
 than six distinct kinds of wheaten flour are 
 brought into the market. Thev are called 
 fine flour, seconds, middlings, fine middlings, 
 coarse middlings, and twenty -penny flour. 
 Common garden beans and pease are also 
 frequently ground up among the London 
 bread flour. 
 
 “ The smallest quantity of alum that can 
 be employed with effect to produce a white, 
 light, and porous bread from an inferior 
 kind of flour, I have my own baker’s autho- 
 rity to state, is from three to four ounces to 
 a sack of flour weighing 240 pounds.” 
 
 u The following account of making a sack 
 or five bushels of flour into bread, is taken 
 from Dr P. Markham’s considerations on the 
 ingredients used in the adulteration of flour 
 and bread, p. 21. 
 
 Five bushels flour, 
 
 Eight ounces of alum, 
 
 Four lbs. salt, 
 
 Half a gallon of yeast mixed w ith aboilt 
 Three gallons of water. 
 
 “ Another substance employed by fraudu- 
 lent bakers is subcarbonate of ammonia.- 
 With this salt they realize the important 
 consideration of producing light and porous- 
 bread from spoiled, or what is technically 
 called sour flour. This salt, which becomes 
 wholly converter! into a gaseous substance 
 during the operation of baking, causes the 
 dough to sw r ell up into air bubbles, which 
 carry before them the stiff dough, and thus 
 it renders the dough porous ; the salt itself 
 is at the same time totally volatilized during 
 the operation of baking.” — “ Potatoes are like- 
 wise largely, and perhaps constantly used by 
 fraudulent bakers, as a cheap ingredient to 
 enhance their’ profit.” — “ There arc instances 
 of convictions on record, of bakers having 
 used gypsum, chalk, and pipe-clay, in the 
 manufacture of bread. ” 
 
 Mr E. Davy, Prof, of Chemistry at the 
 Cork Institution, has made experiments, shew- 
 ing that from twenty to forty grains of com- 
 mon carbonate of magnesia, well mixed with a 
 pound of the w^orst neio seconds flour, materi- 
 ally improved the quality of the bread baked 
 with it. 
 
 The habitual and daily introduction of 
 a portion of alum into the human sto- 
 mach, however small, must be -prejudicial 
 to the exercise of its functions, and particu- 
 larly in persons of a bilious and costive 
 habit. And besides, as the best sweet flour 
 never stands in need of alum, the presence 
 of this salt indicates an inferior and highly 
 acescent food ; which cannot fail to aggra- 
 vate dyspepsia, and which may generate a 
 calculous diathesis in the urinary organs. 
 Every precaution of science and law ought 
 therefore to be employed to detect and stop 
 such deleterious adulterations. Bread may 
 be analyzed for alum by crumbling it down 
 when somewhat stale in distilled water, 
 squeezing the pasty mass through a piece of 
 cloth, and then passing the liquid through a 
 paper filter. A limpid infusion w ill thus be 
 obtained. It is difficult to procure it clear 
 if we use new bread or hot water. A dilute 
 solution of muriate of barytes dropped into 
 the filtered infusion, will indicate by a white 
 cloud, more or less heavy, the presence and 
 quantity of alum. I find that genuine bread 
 gives no precipitate by this treatment. I he 
 earthy adulterations are easily discovered, by 
 
BRE 
 
 BRE 
 
 incinerating the bread at a red heat In a 
 shallow earth vessel, and heating the residu- 
 ary ashes with a little nitrate of ammonia. 
 The earths themselves will then remain, cha- 
 racterized by their whiteness and insolubility. 
 
 The latest chemical treatise on the art ot 
 making bread, except the account given by 
 Mr Accum in his work on the adulterations 
 of food, is the article Baking in the Supple- 
 ment to the Encyclopaedia Britannica, — a 
 work adorned by the dissertations of Biot, 
 
 13 rande, Jeffrey, Lesley, Playfair, and Stewart. 
 
 Under Process of Baking we have the fol- 
 lowing statement : (i An ounce of alum is 
 then dissolved over the fire in a tin pot, and 
 the solution poured into a large tub, called 
 by the bakers the seasoning-tub. Four 
 pounds and a half of salt are likewise put 
 into the tub, and a pailful of hot water.” 
 Note on this passage. — “ In London, where 
 the goodness of bread is estimated entirely 
 by its whiteness, it is usual with those bakers 
 who employ flour of an inferior quality to 
 add as much alum as common salt to the 
 dough. Or in other words, the quantity of 
 salt added is diminished one-lialf, and the de- 
 ficiency supplied by an equal weight of alum. 
 This improves the look of the bread very 
 much, rendering it much whiter and firmer.” 
 In a passage which we shall presently 
 quote, our author represents the bakers of 
 London joined in a conspiracy to supply the 
 citizens with bad bread. We may hence 
 infer, that the full allowance he assigns of 
 2\ pounds of alum for every pounds of 
 salt, will be adopted in converting a sack of 
 flour into loaves. But as a sack of flour 
 weighs 280 pounds, and furnishes on an 
 average 80 quartern loaves, we have 2— 
 
 pounds divided by 80, or _ d — 
 
 80 
 
 197 grains, for the quantity present by this 
 writer in a London quartern loaf. Yet in 
 the very same page (39th of volume 2d) we 
 have the following passage : “ Alum is not 
 added by all bakers. The writer of this ar- 
 ticle has been assured by several bakers of 
 respectability, both in Edinburgh and Glas- 
 gow, on whose testimony he relies, and 
 who made excellent bread, that they never 
 employed any alum. The reason for add- 
 ing it given by the London bakers is, 
 that it renders the bread whiter, and enables 
 them to separate readily the loaves from each 
 other. This addition has been alleged by 
 medical men, and is considered by the com- 
 munity at large as injurious to the health, 
 by occasioning constipation. But if we con- 
 sider the small quantity of this salt added by 
 the baker, not quite 5h grains to a quartern 
 loaf, we will not readily admit these allega- 
 tions. Suppose an individual to eat the 
 seventh part of a quartern loaf a-day, he 
 would only swallow eight-tenths of a grain 
 alum, or in reality not quite so much as 
 
 half a grain, for one-half of this salt consists 
 of water. It seems absurd to suppose that 
 half a grain of alum, swallowed at different 
 times during the course of a day, should oc- 
 casion constipation.” Is it not more absurd 
 to state pounds, or 36 ounces, as the alum 
 adulteration of a sack of flour by the Lon- 
 don bakers, and within a few periods to re- 
 duce the adulteration to one ounce ? 
 
 That this voluntary abstraction of of 
 the alum, and substitution of superior and 
 more expensive flour, (is not expected by him 
 from the London bakers, is sufficiently evi- 
 dent from the following story : It would ap- 
 pear that some of his friends had invented a 
 new yeast for fermenting dough by mixing a 
 quart of beer barm with a paste made of ten 
 pounds of flour and two gallons of boiling 
 water, and keeping this mixture warm for 
 six or eight hours. 
 
 “ Yeast made in this way,” says he, “ an- 
 swers the purposes of the baker much better 
 than brewer’s yeast, because it is clearer, and 
 free from the hop mixture, which sometimes 
 injures the yeast of the brewer. Some years 
 ago the bakers of London, sensible of the 
 superiority of this artificial yeast, invited a 
 company of manufacturers from Glasgow to 
 establish a manufactory of it in London, and 
 promised to use no other. About L. 5000 
 accordingly were laid out on buildings and 
 materials, and the manufactory was begun 
 on a considerable scale. The ale brewers, 
 finding their yeast, for which they had drawn 
 a good price, lie heavy on their hands, in- 
 vited all the journeymen bakers to their cel- 
 lars, gave them their full of ale, and pro- 
 mised to regale them in that manner every 
 day, provided they would force their masters 
 to take all their yeast from the ale brewers. 
 The journeymen accordingly declared in a 
 body, that they would work no more for their 
 masters unless they gave up taking any more 
 yeast from the new manufactory. The mas- 
 ters were obliged to comply ; the new manu- 
 factory was stopped ; and the inhabitants of 
 London were obliged to continue to eat U'orse 
 bread, because it icas the interest of the ale 
 brewers to sell the yeast. Such is the influ- 
 ence of journeymen bakers in the metropolis 
 of England ! ” 
 
 This doleful diatribe seems rather extra- 
 vagant ; for surely beer-yeast can derive no- 
 thing noxious to a porter-drinking people, 
 from a slight impregnation of hops ; while 
 it must form probably a more energetic fer- 
 ment than the fermented paste of the new 
 company, which at any rate could be pre- 
 pared in six or eight hours by any baker 
 who found it to answer his purpose of mak- 
 ing a pleasant eating bread. But it is a very 
 serious thing for a lady or gentleman of se- 
 dentary habits, or infirm constitution, to have 
 their digestive process daily vitiated by da- 
 maged flour, whitened with 197 grains of 
 
BRI 
 
 BRO 
 
 alum per quartern loaf. Acidity of stomach, 
 indigestion, flatulence, headaches, palpita. 
 tion, costiveness, and urinary calculus, may 
 be the probable consequences of the habitual 
 introduction of so much acidulous and aces- 
 cent matter. 
 
 1 have made many experiments on bread, 
 and have found the proportion of alum very 
 variable. Its quantity seems to be propor- 
 tional to the badness of the flour ; and hence 
 when the best flour is used, no alum need be 
 introduced. That alum is not necessary for 
 giving bread its utmost beauty, sponginess, 
 and agreeableness of taste, is undoubted, 
 since the bread baked at the establishment of 
 Mr Harley of Willowbank, Glasgow, in 
 which about 20 tons of flour are converted 
 into loaves in the course of a week, unites 
 every quality of appearance, with an absolute 
 freedom from that acido-astringent drug. 
 
 o n 
 
 He uses six pounds of salt for every sack of 
 flour ; which from its good quality generally 
 affords 83 or 84 quartern loaves of the legal 
 weight, of four pounds five ounces and a 
 half each. The loaves lose nine ounces in 
 the oven. For an account of the constitu- 
 ents of wheat flour, see Wheat.* 
 
 Breccia. An Italian term, frequently 
 used by our mineralogical writers to denote 
 such compound stones as are composed of 
 agglutinated fragments of considerable size. 
 When the agglutinated parts are rounded, 
 the stone is called pudding-stone. Breccias 
 are denominated according to the nature of 
 their component parts. Thus we have cal- 
 careous breccias, or marbles ; and siliceous 
 breccias, which are still more minutely class- 
 ed. according to their varieties. 
 
 Brewing. See Beer, Alcohol, and Fer- 
 mentation. 
 
 Brick. Among the numerous branches 
 of the general art of fashioning argillaceous 
 earths into useful forms, and afterward har- 
 dening them by fire, the art of making bricks 
 and tiles is by no means one of the least useful. 
 
 Common clay is scarcely ever found in a 
 state approaching to purity on the surface of 
 the earth. It usually contains a large pro- 
 portion of siliceous earth. Bergmann exa- 
 mined several clays in the neighbourhood of 
 Upsal, and made bricks, which he baked 
 with various degrees of heat, suffered them 
 to cool, immersed them in water for a con- 
 siderable time, and then exposed them to the 
 open air for three years. They were formed 
 of clay and sand. The hardest were those 
 into the composition of which a fourth part 
 of sand had entered. Those which had been 
 exposed for the shortest time to the fire were 
 almost totally destroyed, and crumbled down 
 by the action of the air ; such as had been 
 more thoroughly burned suffered less da- 
 mage ; and in those which had been fprmed 
 of clay alone, and were half vitrified by the 
 heat, no change whatever was produced. 
 
 On the whole he observes, that the prow 
 portion of sand to be used to any clay, in 
 making bricks, must be greater the more 
 such clay is found to contract in burning ; 
 but that the best clays are those which need 
 no sand. Bricks should be well burned ; 
 but no vitrification is necessary, when they 
 can be rendered hard enough by the mere 
 action of the heat. Where a vitreous crust 
 might be deemed necessary, he recommends 
 the projection of a due quantity of salt into 
 the furnace, which would produce the effect 
 in the same manner as is seen in the fabri- 
 cation of the English pottery called stone- 
 ware. 
 
 A kind of bricks called fire-bricks are 
 made from slate-clay, which are very hard, 
 heavy, and contain a large proportion of 
 sand. These are chiefly used in the con- 
 struction of furnaces for steam-engines, or 
 other large works, and in lining the ovens 
 of glass-houses, as they will stand any de- 
 gree of heat. Indeed they should always be 
 employed where fires of any intensity are 
 required. 
 
 * Bricks ( Floating). Bricks, that swim 
 on water, were manufactured by the an- 
 cients ; and Fabbroni discovered some years 
 since a substance, at Castel del Piano, near 
 Santa Fiora, between Tuscany and the States 
 of the Church, from which similar bricks 
 might be made. It constitutes a brown earthy 
 bed, mixed with the remains of plants. Haiiy 
 calls it talc pulverulent silicifere , and Bro- 
 chaut considers it as a variety of meerschaum . 
 The Germans name it bergmehl , (mountain 
 meal), and the Italians latte di luna , (moon 
 milk). By Klaproth’s analysis, it consists of 
 79 silica, 5 alumina, 3 oxide of iron, 12 
 water, and 1 loss, in 100 parts. It agrees 
 nearly in composition with Kieselguhr* 
 
 Brimstone. See Sulphur. 
 
 * Brionia Alba. A root used in medi- 
 cine. By the analysis of Vauquelin, it is 
 found to consist in a great measure of starch, 
 with a bitter principle, soluble in water and 
 alcohol, some gum, a vegeto-animal matter, 
 preeipitable by infusion of galls, some woody 
 fibre, a little sugar, and supermalate and 
 phosphate of lime. It has cathartic powers; 
 but is now seldom prescribed by physicians.* 
 
 Brocatello. A calcareous stone or mar- 
 ble, composed of fragments of four colours, 
 white, grey, yellow, and red. 
 
 Bronze. A mixed metal, consisting 
 chiefly of copper, with a small proportion of 
 tin, and sometimes other metals. It is used 
 for casting statues, cannon, bells, and other 
 articles, in all which the proportions of the 
 ingredients vary. 
 
 * Bronzite. This massive mineral has a 
 pseudo-metallic lustre, frequently resembling 
 bronze. Its colour is intermediate between 
 yellowish-brown and pinchbeck-brow n. Lus- 
 tre shining; structure lamellar with joints. 
 
BRU 
 
 BUT 
 
 parallel to the lateral planes of a rhomboidal 
 prism ; the fragments are streaked on the 
 surface. It is opaque in mass, but transpar- 
 ent in thin plates. White streak ; somewhat 
 hard, but easily broken. Sp. gr. 3.2. It 
 is composed of 60 silica, 27.5 magnesia, 
 10.5 oxide of iron, and 0.5 water. It is 
 found in large masses in beds of serpentine, 
 near Kranbat, in Upper Stiria ; and in a sy- 
 enitic rock in Glen Tilt, in Perthshire.* 
 
 * Brown Spar. Pearl spar, or Sidero- 
 calcite. It occurs massive, and in obtuse 
 rhomboids with curvilinear faces. Its co- 
 lours are white, red, and brown, or even 
 pearl-grey and black. It is found crystalliz- 
 ed in Hat and acute double three-sided pyra- 
 mids, in oblique six-sided pyramids, in lenses 
 and rhombs. It is harder than calcareous 
 spar, but yields to the knife. Its external 
 lustre Is shining, and internal pearly. Sp. 
 gr. 2.88. Translucent, crystals semi-transpa- 
 rent ; it is easily broken into rhomboidal 
 fragments. It effervesces slowly with acids. 
 It is composed of 49.19 carbonate of lime, 
 44.39 carbonate of magnesia, 3.4 oxide of 
 iron, and 1.5 manganese, by Hisinger’s ana- 
 lysis. Klaproth found 32 carbonate of mag- 
 nesia, 7.5 carbonate of iron, 2 carbonate 
 of manganese, and 51.5 carbonate of lime. 
 
 There is a variety of this mineral of a 
 fibrous texture, flesh-red colour, and mas- 
 sive.* 
 
 * Brucia, or Brucine. A new vegetable 
 alkali, lately extracted from the bark of the 
 false angustura, or Brucea antidysenterica , 
 by MM. Pelletier and Caventou. After be- 
 ing treated with sulphuric ether, to get rid 
 of a fatty matter, it was subjected to the ac- 
 tion of alcohol. The dry residuum from the 
 evaporated alcoholic solution, was treated 
 with Goulard’s extract, or solution of sub- 
 acetate of lead, to throw down the colouring 
 matter, and the excess of lead was separated 
 by a current of sulphuretted hydrogen. The 
 nearly colourless alkaline liquid was saturat- 
 ed with oxalic acid, and evaporated to dryness. 
 The saline mass being freed from its remain- 
 ing colouring particles, by absolute alcohol, 
 was then decomposed by lime or magnesia, 
 when the brucia was disengaged. It was 
 dissolved in boiling alcohol, and obtained in 
 crystals, by the slow evaporation of the liquid. 
 I hese crystals, when obtained by very slow 
 evaporation, are oblique prisms, the bases of 
 which are parallelograms. When deposited 
 from a saturated solution in boiling water, 
 by cooling, it is in bulky plates, somewhat 
 similar to boracic acid in appearance. It is 
 soluble in 500 times its weight of boiling 
 water, and in 850 of cold. Its solubility is 
 much increased by the colouring matter of 
 the bark. 
 
 Its taste is exceedingly bitter, acrid, and 
 dm able in the mouth. When administered 
 in doses of a few grains, it is poisonous, act- 
 
 ing on animals like strychnia, but much 
 less violently. It is not affected by the air. 
 The dry crystals fuse at a temperature a little 
 above that of boiling water, and assume the 
 appearance of wax. At a strong heat, it is 
 resolved into carbon, hydrogen, and oxygen ; 
 without any trace of azote. It combines 
 with the acids, and forms both neutral and 
 super- salts. Sulphate of brucia crystalliz- 
 es in long slender needles, which appear to 
 be four- sided prisms, terminated by pyramids 
 of extreme fineness. It is very soluble in 
 water, and moderately in alcohol. Its taste 
 is very bitter. It is decomposed by potash, 
 soda, ammonia, barytes, strontites, lime, mag- 
 nesia, morphia, and strychnia. The bisul- 
 phate crystallizes more readily than the neu- 
 tral sulphate. The latter is said to be com- 
 posed of 
 
 Sulphuric acid, 8.84 5 
 
 Brucia, 91.1 6 51.582 
 
 Muriate of brucia forms in four-sided 
 prisms, terminated at each end by an oblique 
 face. It is permanent in the air, and very 
 soluble in water. It is decomposed by sul- 
 phuric acid. Concentrated nitric acid des- 
 troys the alkaline basis of both these salts. 
 The muriate consists of 
 
 Acid, 5.953 4.575 
 
 Brucia, 94.046 72.5 
 
 Phosphate of brucia, is a crystal li zable, 
 soluble, and slightly efflorescent salt. The 
 nitrate forms a gummy looking mass; the 
 binitrate crystallizes in acicular four-sided 
 prisms. An excess of nitric acid decom- 
 poses the brucia, into a matter of a fine red 
 colour. Acetate and oxalate of brucia both 
 crystallize. Brucia is insoluble in sulphuric 
 ether, the fixed oils, and very slightly in the 
 volatile oils. W hen administered internally, 
 it produces tetanus, and acts upon the nerves 
 without affecting the brain, or the intellec- 
 tual faculties. Its intensity is to that of 
 strychnia, as 1 to 12. From the discre- 
 pancies in the prime number for brucia, de- 
 duced from the above analysis, we see that 
 its true equivalent remains to he determined. 
 See Journal de Pharmacies Dec. 1819.* 
 Brunswick Green. This is an ammo- 
 niaco-muriate of copper, much used for 
 paper-hangings, and on the continent in oil 
 painting. See Coffer. 
 
 * Buntkupferz. Purple copper ore.* 
 Butter. The oily inflammable part of 
 milk, which is prepared in many countries 
 as an article of food. The common mode 
 of preserving it is by the addition of salt, 
 which will keep it good a considerable time, 
 if in sufficient quantity. Mr Eaton informs 
 us, in his Survey of the Turkish Empire, 
 that most of the butter used at Constantino- 
 ple is brought from the Crimea and Kirban, 
 and that it is kept sweet, by melting it while 
 fresh over a very slow fire, and removing 
 the scum as it rises. He adds, that by 
 
CAC 
 
 CAD 
 
 melting butter in the Tartarian manner, and 
 then salting it in ours, he kept it good and 
 fine-tasted tor two years; and that this 
 melting, it carefully done, injures neither 
 the taste nor colour. Thenard, too, recom- 
 mends the Tartarian method. lie directs 
 the melting to be done on a water-bath, or 
 at a heat not exceeding 1 80° F. ; and to be 
 continued till all the caseous matter has 
 subsided to the bottom, and the butter is 
 transparent. It is then to be decanted, or 
 strained through a cloth, and cooled in a 
 mixture of pounded ice and salt, or at least 
 in cold spring water, otherwise it will be- 
 come lumpy by crystallizing, and likewise 
 not resist the action of the air so well. Kept 
 in a close vessel, and in a cool place, it will 
 thus remain six months or more, nearly as 
 good as at first, particularly after the top is 
 taken oil. If beaten up with one-sixth of 
 its weight of the cheesy matter when used, 
 it will in some degree resemble fresh butter 
 in appearance. The taste of rancid butter, 
 he adds, may be much corrected by melting 
 and cooling in this manner. 
 
 Dr Anderson has recommended another 
 mode of curing butter, which is as follows : 
 Take one part of sugar, one of nitre, and 
 two of the best Spanish great salt, and rub 
 them together into a fine powder. This 
 composition is to be mixed thoroughly with 
 the butter, as soon as it is completely freed 
 from the milk, in the proportion of one 
 ounce to sixteen ; and the butter thus pre- 
 pared is to be pressed tight into the vessel 
 prepared for it, so as to leave no vacuities. 
 This butter does not taste well, till it has 
 stood at least a fortnight ; it then lias a rich 
 marrowy flavour, that no other butter ever 
 acquires ; and with proper care may be 
 .kept for years in this climate, or carried 
 to the East Indies, if packed so as not to 
 melt. 
 
 In the interior parts of Africa, Mr Park 
 informs us, there is a tree much resembling 
 the American oak, producing a nut in ap- 
 pearance somewhat like an olive. The 
 kernel of this nut, by boiling in water, 
 affords a kind of butter, which is whiter, 
 firmer, and of a richer flavour, than any he 
 ever tasted made from cows’ milk, and will 
 keep without salt the whole year. The na- 
 tives call it shea toulou , or tree butter. 
 Large quantities of it are made every sea- 
 son. 
 
 Butter of Antimony. See Antimony. 
 
 Butter of Cacao. An oily concrete 
 white matter, of a firmer consistence than 
 suet, obtained from the cacao nut, of which 
 chocolate is made. The method of sepa- 
 rating it consists in bruising the cacao and 
 boiling it in water. The greater part of the 
 superabundant and uncombined- oil contain- 
 ed in the nut is by this means liquefied, and 
 rises to the surface, where it swims, and is 
 left to congeal, that it may be the more easi- 
 ly taken off. It is generally mixed with 
 small pieces of the nut, from which it may 
 be purified, by keeping it in fusion without 
 water in a pretty deep vessel, until the seve- 
 ral matters have arranged themselves accord- 
 ing to their specific gravities. By this treat- 
 ment it becomes very pure and white. 
 
 Butter of cacao is w ithout smell, and has 
 a very mild taste, when fresh; and in all its 
 general properties and habitudes, it resembles 
 fat oils;; among which it must therefore be 
 classed. It is used as an ingredient in po- 
 matums. 
 
 Butter of Tin. See Tin. 
 
 * Byssolite. A massive mineral, in 
 short and somewhat stiff filaments, of an 
 olive-green colour, implanted perpendicular- 
 ly like moss, on the surface of certain stones. 
 It has been found at the foot of Mount 
 Blanc, and also near Oisaus-on- gneiss.* 
 
 
 C 'tABBAGE (Red). See Brassica Ru- 
 
 A BRA. 
 
 Cacao (Butter of). Sec Butter. 
 
 * Cacholong. A variety of quartz. It is 
 opaque, dull on the surface, internally of a 
 pearly lustre, brittle, with a flat conchoidal 
 fracture, and harder than opal. Its colour 
 is milk-w'hite, yellowish, or greyish- white. 
 It is not fusible before the blow-pipe. Its 
 sp. grav. is about 2.2. It is found in de- 
 tached masses on the river Cach in Bucharia, 
 in the trap rocks of Iceland, in Greenland, 
 and the Ferroe Islands. According to 
 Brogniart, cacholongs are found also at 
 Champigny near Baris, in the cavities ol a 
 calcareous breccia, some of which are hard 
 and have a shining fracture, while others are 
 
 tender, light, adhere to the tongue, and re- 
 semble chalk.* 
 
 * Cadmium. A new metal, first discover- 
 ed by M. Stromeyer, in the autumn of 1817, 
 in some carbonate of zinc which he was ex- 
 amining in Ilanover. It has been since 
 found in the Derbyshire silicates of zinc. 
 
 The following is Dr Wollaston’s process 
 for procuring cadmium. It is distinguished 
 by the usual elegance and precision of the 
 analytical methods of this philosopher. Ironi 
 the solution of the salt of zinc supposed to 
 contain cadmium, precipitate all the other 
 metallic impurities by iron ; filter and im- 
 merse a cylinder of zinc into the clear solu- 
 tion. If cadmium he present, it will be 
 thrown down in the metallic state, and whe» 
 
CAD 
 
 CAD 
 
 redissolved in muriatic acid, will exhibit its 
 peculiar character on the application of the 
 proper tests. 
 
 M. Stromeyer’s process consists in dissolv- 
 ing the substance which contains cadmium 
 in sulphuric acid, and passing through the 
 acidulous solution a current of sulphuretted 
 hydrogen gas. He washes this precipitate, dis- 
 solves it in concentrated muriatic acid, and ex- 
 pels the excess of acid by evaporation. The 
 residue is then dissolved in water, and precipi- 
 tated by carbonate of ammonia, of which an 
 excess is added, to redissolve the zinc and the 
 copper that may have been precipitated by 
 the sulphuretted hydrogen gas. The car- 
 bonate of cadmium being well washed, is 
 heated, to drive oft' the carbonic acid, and 
 the remaining oxide is reduced by mixing it 
 with lampblack, and exposing it to a mode- 
 rate red heat in a glass or earthen retort. 
 
 The colour of cadmium is a tine wfflite, 
 with a slight shade of bluish grey, approach- 
 ing much to that of tin, which metal it re- 
 sembles in lustre and susceptibility of po*- 
 lish. Its texture is compact, and its fracture 
 hackly. It crystallizes easily in octohe- 
 drons, and presents on its surface, when 
 cooling, the appearance of leaves of fern. It 
 is flexible, and yields readily to the knife. It 
 is harder and more tenacious than tin ; and, 
 like it, stains paper, or the fingers. It is 
 ductile and malleable, but w r hen long ham- 
 mered, it scales off in different places. Its 
 sp. grav. before hammering, is 8.6040; and 
 when hammered, it is 8.6944. It melts, 
 and is volatilized under a red heat. Its 
 vapour, which has no smell, may be con- 
 densed in drops like mercury, which, on con- 
 gealing, present distinct traces of crystalliza- 
 tion. 
 
 Cadmium is as little altered by exposure 
 to the air as tin. When heated in the open 
 air, it burns like that metal, passing into a 
 smoke, which falls and forms a very fixed 
 Oxide, of a brownish-yellow colour* Nitric 
 acid readily dissolves it cold ; dilute sulphu- 
 ric, muriatic, and even acetic acids, act fee- 
 bly on it with the disengagement of hydro- 
 gen. The solutions are colourless, and are 
 not precipitated by water. 
 
 Cadmium forms a single oxide, in which 
 100 parts of the metal are combined with 
 14.852 of oxygen. The prime equivalent 
 of cadmium deduced from this compound 
 seems to be very nearly 7, and that of the 
 oxide 8. This oxide varies in its appear- 
 ance according to circumstances, from a 
 brownish- yellow to a dark brown, and even 
 a blackish colour. With charcoal it is re- 
 duced with rapidity below a red heat. It 
 gives a transparent colourless glass bead 
 with borax. It is insoluble in water, but in 
 some circumstances forms a white hydrate, 
 which speedily attracts carbonic acid from 
 
 the air, and gives out its water when expos- 
 ed to heat. 
 
 The fixed alkalis do not dissolve the oxide 
 of cadmium in a sensible degree ; but liquid 
 ammonia readily dissolves it. On evaporat- 
 ing the solution, the oxide falls in a dense 
 gelatinous hydrate. With the acids it forms 
 salts, which are almost all colourless, have a 
 sharp metallic taste, are generally soluble in 
 water, and possess the following characters : 
 
 1. The fixed alkalis precipitate the oxide 
 in the state of a white hydrate. When add- 
 ed in excess, they do not redissolve the pre- 
 cipitate, as is the case with the oxide of zinc, 
 
 2. Ammonia likewise precipitates the oxide 
 white, and doubtless in the state of hydrate ; 
 but an excess of the alkali immediately re- 
 dissolves the precipitate. 
 
 3. The alkaline carbonates produce a 
 white precipitate, which is an anhydrous car- 
 bonate. Zinc in the same circumstances 
 gives a hydrous carbonate. The precipitate 
 formed bv the carbonate of ammonia is not 
 
 y 
 
 soluble in an excess of this solution. Zinc 
 exhibits quite different properties. 
 
 4. Phosphate of soda exhibits a white 
 pulverulent precipitate. The precipitate 
 formed by the same salt in solutions of zinc, 
 is in fine crystalline plates. 
 
 5. Sulphuretted hydrogen gas, and the 
 hydrosulphurets, precipitate cadmium yel- 
 low or orange. This precipitate resembles 
 orpiment a little in colour, with which it 
 might be confounded without sufficient at- 
 tention. But it may be distinguished by be- 
 ing more pulverulent, and precipitating more 
 rapidly. It differs particularly in its easy so- 
 lubility in muriatic acid, and in its fixity. 
 
 6. Ferroprussiate of potash precipitates 
 solutions of cadmium white. 
 
 7. Nutgalls do not occasion any change. 
 
 8. Zinc precipitates cadmium in the me- 
 tallic state in the form of dendritical leaves, 
 which attach themselves to the zinc. 
 
 The carbonate consists, by Strom eyer, of 
 Acid, 100.00 25.4 2.750 
 
 Oxide, 292.88 74.6 8.054 
 
 The sulphate crystallizes in large rectaru 
 giilar transparent prisms, similar to sulphate 
 of zinc, and very soluble in water. It efflo- 
 resces in the air. At a strong red heat it 
 gives out a portion of its acid, and becomes 
 a subsulphate, which crystallizes in plates 
 that dissolve with difficulty in water. The 
 neutral sulphate consists of, 
 
 Acid, 100.00 38.3 5*000 
 
 Oxide, 161.12 61.7 8.056 
 
 100 parts of the salt take 34.26 of water of 
 crystallization. Nitrate of cadmium crys- 
 tallizes in prisms or needles, usually group- 
 ed in rays. It is deliquescent. Its consti- 
 tuents are, 
 
 Acid, 100.00 46. 6.75000 
 
 Oxide, 117.58 54. 7.93665 
 
 O 
 
CAD 
 
 CAL 
 
 100 parts of the dry salt take 28.31 water 
 ox crystallization. The muriate of cadmium 
 crystallizes in small rectangular prisms, per- 
 fectly transparent, which effloresce easily 
 when heated, and which are very soluble. 
 It melts under a red heat, loses its water of 
 crystallization, and on cooling assumes the 
 form of a foliated mass, which is transparent, 
 and has a lustre slightly metallic and pearly. 
 In the air, it speedily loses its transparency, 
 and falls down in a white powder. 100 
 parts of fused chloride are composed of, 
 Cadmium, 61.59 7.076 
 
 Chlorine, 58.61 4.450 
 
 Phosphate of cadmium is pulverulent, in- 
 soluble in water, and melts, when heated to 
 redness, into a transparent vitreous body. It 
 is composed of, 
 
 Acid, 100 5.54 
 
 Oxide, 225.49 8.00 
 
 Borate of cadmium is scarcely soluble in 
 w ater. It consists of, 
 
 Acid, 27.88 3.079 
 
 Oxide, 72.12 8.000 
 
 Acetate of cadmium crystallizes in small 
 prisms, usually disposed in stars, which are 
 not altered by exposure to air, and are very 
 soluble in water. The tartrate crystallizes 
 in small scarcely soluble needles. The oxa- 
 late is insoluble. The citrate forms a crys- 
 talline powder, very little soluble. 
 
 100 parts of cadmium unite with 28.172 
 of sulphur, to form a sulphuret of a yellow 
 colour, with a shade of orange. It is very 
 fixed in the fire. It melts at a white-red 
 heat, and on cooling, crystallizes in micace- 
 ous plates of the finest lemon-yellow colour. 
 The sulphuret dissolves even cold in con- 
 centrated muriatic acid, with the disengage- 
 ment of sulphuretted hydrogen gas ; but the 
 dilute acid has little effect on it, even with 
 the assistance of heat. It is best formed by 
 heating together a mixture of sulphur with 
 the oxide, or by precipitating a salt of cad- 
 mium with sulphuretted hydrogen. It pro- 
 mises to be useful in painting. 
 
 Phosphuret of cadmium, made by fusing 
 the ingredients together, has a grey colour, 
 and a lustre feebly metallic. Muriatic acid 
 decomposes it, evolving phosphuretted hydro- 
 gen gas. Iodine unitqs with cadmium, both 
 in the moist and dry way. We obtain an 
 iodide in large and beautiful hexahedral 
 tables. These crystals are colourless, trans- 
 parent, and not altered by exposure to air. 
 Their lustre is pearly, approaching to metal- 
 lic. It melts with extreme facility, and as- 
 sumes, on cooling, the original form. At a 
 high temperature, it is resolved into cad- 
 mium and iodine. Water and alcohol dis- 
 solve it with facility. It is composed of, 
 Cadmium, 100.00 8.000 
 
 Iodine, 227.43 18.1984? 
 
 Cadmium unites easily with most ol the 
 metals, when heated along with them out of 
 
 contact of air. Most of its alloys are brittle 
 and colourless. r l hat of copper and cad- 
 mium is white, with a slight tinge of yellow’. 
 Its texture is composed of very fine plates. 
 
 of cadmium communicates a good deal 
 of brittleness to copper. At a strong heat 
 the cadmium flies off. Tutty usually con- 
 tains oxide of cadmium. The alloy con- 
 sists of, 
 
 Copper, 1 00. 
 
 Cadmium, 84.2 
 
 The alloy of cobalt and cadmium has a 
 good deal of resemblance to arsenical cobalt. 
 Its colour is almost silver white. 100 parts 
 of platinum combine with 1 17.5 of cadmium. 
 Cadmium and mercury readily unite cold, 
 into a fine silver wdiite amalgam, of a granu- 
 lar texture, which may be crystallized in oc- 
 tahedrons. Its specific gravity is greater 
 than that of mercury ! It fuses at 167° F. 
 It consists of, 
 
 Mercury, 100. 
 
 Cadmium, 27.78 
 
 Dr Clarke found in 100 gr. of the fibrous 
 silicate of zinc, of Derbyshire, about of a 
 grain of sulphuret of cadmium, a result 
 which agrees with the experiments of Dr 
 Wollaston and Mr Children.* 
 
 •* Caffein. By adding muriate of tin to 
 an infusion of unroasted coffee, M. Chenevix 
 obtained a precipitate, which he w r ashed and 
 decomposed by sulphuretted hydrogen. The 
 supernatant liquid contained a peculiar bitter 
 principle, which occasioned a green precipi- 
 tate in concentrated solutions of iron. When 
 the liquid was evaporated to dryness, it was 
 yellow and transparent, like horn. It did 
 not attract moisture from the air, but w as 
 soluble in water and alcohol. The solution 
 had a pleasant bitter taste, and assumed with 
 alkalis a garnet-red colour. It is almost as 
 delicate a test of iron as infusion of galls is ; 
 yet gelatine occasions no precipitate with it.* 
 
 Cajeput Oil. The volatile oil obtained 
 from the leaves of the cajeput tree. Caje- 
 puta officinarum, the Melaleuca Leucaden- 
 dron of Linnaeus. The tree which furnishes 
 the cajeput oil is frequent on the mountains 
 of Amboyna, and other Molucca islands. It 
 is obtained by distillation from the dried 
 leaves of the smaller of two varieties. It is 
 prepared in great quantities, especially in the 
 island of Banda, and sent to Holland in cop- 
 per flasks. As it comes to us, it is of a green 
 colour, very limpid, lighter than water, of a 
 strong smell, resembling camphor, and a 
 strong pungent taste, like that of cardamons. 
 It burns entirely away, w ithout leaving any 
 residuum. It is often adulterated with other 
 essential oils, coloured with the resin of mil- 
 foil. In the genuine oil, the green colour 
 depends on the presence of copper ; for when 
 rectified it is colourless. 
 
 Calamine. A native carbonate of zinc. 
 
CAL 
 
 CAL 
 
 Calcareous Earth. See Lime. 
 
 * Calcareous Spar. Crystallized carbo- 
 nate of lime. It occurs crystallized in more 
 than 600 different forms, all having for their 
 primitive form an obtuse rhomboid, with 
 angles of 74° 55' and 105° 5\ It occurs also 
 massive, and in imitative shapes. Werner 
 has given a comprehensive idea of the va* 
 rieties of the crystals, by referring all the 
 forms to the six-sided pyramid, the six-sided 
 prism, and the three-sided prism, with their 
 truncations. The colours of calc- spar are 
 grey, yellow, red, green, and rarely blue. 
 Vitreous lustre. Foliated fracture, with a 
 threefold cleavage. Fragments rhomboidal. 
 Transparent, or translucent, riie transpa- 
 rent crvstals refract double. It is less hard 
 
 it 
 
 than fluor spar, and is easily broken. Sp. gr. 
 2.7. It consists of 43.6 carbonic acid, and 
 56.4 lime. It effervesces powerfully with 
 acids. Some varieties are phosphorescent on 
 hot coals. It is found in veins in all rocks, 
 from granite to alluvial strata, and some- 
 times in strata between the beds of calcareous 
 mountains. The rarest and most beautiful 
 crystals are found in Derbyshire ; but it 
 exists in every part of the world.* 
 
 * Calcedony. A mineral so called from 
 Calcedon in Asia Minor, where it was found 
 in ancient times. There are several sub- 
 species : common calcedony, heliotrope, chry- 
 soprase, plasma, onyx, sard, and sardonyx. 
 
 Common calcedony occurs in various 
 shades of white, grey, yellow, brown, green, 
 and blue. The blackish- brown appears, on 
 looking through the mineral, to become a 
 blood-red. It is found in nodules ; botroidal, 
 stalactitical, bearing organic impressions, in 
 veins, and also massive. Its fracture is even, 
 sometimes flat conchoidal, or fine splintery. 
 Semi-transparent, harder and tougher than 
 flint. Sp. grav. 2.6. It is not fusible. It 
 may be regarded as pure silica, with a mi- 
 nute portion of water. Very fine stalactiti- 
 cal specimens have been found in Trevascus 
 mine in Cornwall. It occurs in the toad- 
 stone of Derbyshire, in the trap rocks of 
 Fifeshire, of the Pentland-hills, Mull, Rum, 
 Sky, and others of the Scotish Hebrides ; 
 likewise in Iceland, and the Ferro Islands, 
 See the sub-species, under their respective 
 titles.* 
 
 I 
 
 * Calc Sinter. Stalactitical carbonate of 
 lime. It is found in pendulous conical rods 
 I or tubes, mamellated, massive, and in many 
 I imitative shapes. Fracture lamellar, or di- 
 | vergent fibrous. Lustre silky or pearly. 
 Colours white, of various shades, yellow, 
 brown, rarely green, passing into blue or 
 red. Translucent — semihard — very brittle. 
 
 Large stalactites are found in the grotto of 
 | Anti paros, the woodman’s cave in the Hartz, 
 
 I the cave of Auxelle in France, in the cave of 
 I Castleton in Derbyshire, and Macalister cave 
 
 I I in Sky. , They are continually forming by 
 
 the infiltration of carbonated lime-water, 
 through the crevices of the roofs of caverns. 
 Solid masses of stalactite have been called 
 oriental alabaster. The irregular masses on 
 the bottoms of caves have been called stal- 
 agmites.* 
 
 * Calchantum. Fliny’s term for copper- 
 as.* 
 
 Calcination. The fixed residues of such 
 matters as have undergone combustion are 
 called cinders in common language, and 
 calces, or now more commonly oxides, by 
 chemists ; and the operation, when consider- 
 ed with regard to these residues, is termed 
 calcination. In this general way it has like- 
 wise been applied to bodies not really com- 
 bustible, but only deprived of some of their 
 principles by heat. Thus we hear of the 
 calcination of chalk, to convert it into lime, 
 by driving off its carbonic acid and water ; 
 of gypsum or plaster stone, of alum, of bo- 
 rax, and other saline bodies, by which they 
 are deprived of their water of crystallization ; 
 of bones, which lose their volatile parts by 
 this treatment ; and of various other bodies. 
 See Combustion and Oxidation. 
 
 * Calcium. The metallic basis of lime. 
 Sir II. Davy, the discoverer of this metal, 
 procured it by the process which he used for 
 obtaining barium which see. It was in 
 such small quantities, that little could be 
 said concerning its nature. It appeared 
 brighter and whiter than either barium or 
 strontium ; and burned when gently heated, 
 producing dry lime. 
 
 There is only one known combination of 
 calcium and oxygen, which is the important 
 substance called lime. The nature of this 
 substance is proved by the phenomena of 
 the combustion of calcium ; the metal chang- 
 ing into the earth with the absorption of 
 oxygen gas. When the amalgam of cal- 
 cium is thrown into water, hydrogen gas is 
 disengaged, and the water becomes a solu- 
 tion of lime. From the quantity of hydro- 
 gen evolved, compared with the quantity of 
 lime formed in experiments of this kind, 
 M. Berzelius endeavoured to ascertain the 
 proportion of oxygen in lime. The nature 
 of lime may also be proved by analysis. 
 When potassium in vapour is sent through 
 the earth ignited to whiteness, the potassium 
 was found by Sir II. Davy to become pot- 
 ash, while a dark grey substance of metallic 
 splendour, which is calcium, either wholly 
 or partially deprived of oxygen, is found im- 
 bedded in the potash, for it effervesces vio- 
 lently, and forms a solution of lime by the 
 action of water. 
 
 Lime is usually obtained for chemical 
 purposes, from marble of the whitest kind, 
 or from calcareous spar, by long exposure to 
 a strong red heat. It is a soft white sub- 
 stance, of specific gravity 2.3. It requires 
 an intense degreo of heat for its fusion : and 
 
CAL 
 
 CAL 
 
 lias not hitherto been volatilized. Its taste 
 is caustic, astringent and alkaline. It is so- 
 luble in 450 parts of water, according to Sir 
 II. Davy; and in 760 parts, according to 
 other chemists. The solubility is not in- 
 creased by heat. If a little water only be 
 sprinkled on new burnt lime, it is rapidly 
 absorbed, with the evolution of much heat 
 and vapour. This constitutes the phenome- 
 non called slaking. The heat proceeds, ac- 
 cording to Dr Black’s explanation, from the 
 consolidation of the liquid water into the 
 lime, forming a hydrate , as slaked lime is 
 now called. It is a compound of 3.56 parts 
 of lime, with 1.125 of water; or very nearly 
 3 to 1. This water may be expelled by a 
 red heat, and therefore does not adhere to 
 lime with the same energy as it does to ba- 
 rytes and strontites. Lime water is astrin- 
 gent and somewhat acrid to the taste. It 
 renders vegetable blues green ; the yellows 
 brown ; and restores to reddened litmus 
 its usual purple. When lime water stands 
 exposed to the air, it gradually attracts car- 
 bonic acid, and becomes an insoluble carbo- 
 nate, while the water remains pure. If 
 lime water be placed in a capsule under an 
 exhausted receiver, which also encloses a 
 saucer filled with concentrated sulphuric 
 acid, the water will be gradually withdrawn 
 from the lime, which will concrete into 
 small six-sided prismatic crystals. 
 
 Berzelius attempted to determine the 
 prime equivalent of calcium, from the pro- 
 portion in which it combines with oxygen, 
 to form lime; but his results can be regard- 
 ed only as approximations, in consequence 
 of the difficulties of the experiment. The 
 prime equivalent of lime, or oxide of cal- 
 cium, can be determined to rigid precision, 
 by my instrument for analyzing the carbo- 
 nates. By this means, I find, that 100 
 parts of carbonate of lime, consist of 43.60 
 carbonic acid -j~ 56.4 lime ; whence the 
 prime equivalent proportions are, 2.75 acid 
 + 3.562 base. 
 
 If a piece of phosphorus be put into the 
 sealed end of a glass tube, the middle part 
 of which is filled with bits of lime about the 
 size of peas ; and after the latter is ignited, 
 if the former be driven through it in vapour, 
 heating the end of the tube, a compound of 
 a dark brown colour, called phosphuret of 
 lime, will be formed. This probably consists 
 of 1.5 phosphorus -{» 5.56 lime; but it has 
 not been exactly analyzed. When thrown 
 into water, phosphuretted hydrogen gas is 
 disengaged in small bubbles, which explode 
 in succession as they burst. 
 
 Sulphuret of lime is formed by fusing the 
 constituents rffixed together in a covered cruci- 
 ble. The mass is reddish coloured and very 
 acrid. It deliquesces on exposure to air, and 
 becomes of a greenish-yellow hue. When it 
 is put into water, a hydroguretted sulphuret 
 
 of lime is immediately formed. The same 
 liquid compound may be directly made, by 
 boiling a mixture of sulphur in lime and 
 water. It acts corrosively on animal bodies, 
 and is a powerful reagent in precipitating 
 metals from their solutions. Solid sulphu- 
 ret of lime probably consists of 2. sulphur 
 
 3.56 lime. 
 
 When lime is heated strongly in contact 
 wutli chlorine, oxygen is expelled, and the 
 chlorine is absorbed. For every tw r o parts 
 in volume of chlorine that disappear, one 
 of oxygen is obtained. When liquid muriate 
 of lime is evaporated to dryness, and ignit- 
 ed, it forms the same substance, or chloride 
 of lime. It is a semitransparent crystalline 
 substance; fusible at a strong red heat ; anon- 
 conductor of electricity; has a very bitter taste ; 
 rapidly absorbs w r ater from the atmosphere ; 
 and is extremely soluble in water. (See Mu- 
 riatic Acid). It consists of 2.56 calcium -J- 
 4.45 chlorine = 7.01. Chlorine combines also 
 with oxide of calcium or lime, forming tire 
 very important substance used in bleaching, 
 under the name of oxvmuriate of lime ; but 
 which is more correctly called chloride of 
 lime. 
 
 Several years ago I performed a series of 
 laborious, and rather insalubrious experi- 
 ments, synthetical and analytical, on chlo- 
 ride of lime ; the results of some of which 
 w'ere detailed in a manuscript essay on alka- 
 limetry, and other subjects connected with 
 bleaching, submitted to Dr Henry in 1816. 
 Having since then been occupied in extend- 
 ing my new methods of chemical research, 
 I have delayed publishing till my plans 
 shall be completed. Meanwhile I shall ob- 
 serve, that slaked lime absorbs chlorine very 
 greedily, though unslaked lime, at ordinary 
 temperatures, condenses scarcely an appre- 
 ciable quantity of the dry gas. Under a 
 very trilling pressure, hydrate of lime is ca- 
 pable of condensing almost its own weight 
 of chlorine; or 3.56 lime -f- 1.125 water 
 = 4.685, combine with 4.45 chlorine. 
 Hence, it is really a chloride of lime, and 
 not a sub-bichloride, as Dr Thomson and 
 Mr Dalton have hastily inferred from com- 
 mercial samples, altered by carriage and 
 keeping. And indeed, as it is not the in- 
 terest of the manufacturer to make so rich 
 and pure a compound, when he can get the 
 market price for what contains only one- 
 third or one-fourth the quantity of chlorine, 
 it is absurd to assume a commercial article 
 as the just chemical standard, or equivalent 
 combination. In mv first set of experi- 
 
 r 
 
 ments, I took a certain weight of pure lune, 
 slaked it, and saturated it with pure chlorine. 
 I next ascertained, by analysis, the propor- 
 tion of lime, water, and chlorine, that exist- 
 ed in the compound. The synthesis and 
 analysis agreed very well. But the chloride 
 slowly changes its nature from the disen- 
 
CAL 
 
 gagement of oxygen, by the superior affinity 
 of the chlorine for the calcium. Hence, as 
 well as from negligence or fraud in the ma- 
 nufacture, the chloride of lime is always 
 mixed with more or less of the common 
 muriate. For this reason, as well as for 
 that assigned by M. Gay Lussac, in his ju- 
 dicious critique on Dr Thomson’s paper on 
 oxymuriate of lime, it is impossible to infer 
 the bleaching powder, or to analyze it, by 
 using nitrate of silver. This test shews 
 strongest in fact, when the power is weakest , 
 or when the oxymuriate haS passed into 
 common muriate, to use the manufacturer’s 
 language. Nor is it possible to analyze the 
 chloride with any precision, by exposing it 
 to heat and measuring the oxygen expelled ; 
 because variable portions of chlorine are se- 
 parated at the same time, in very uncertain 
 states of combination. It is difficult to con- 
 ceive how a chemist of Dr Thomson’s high 
 reputation, should ever have pitched upon 
 nitrate of silver to analyze the mingled 
 chlorides of lime and calcium. 
 
 In performing the synthetic experiment, 
 the hydrate of lime must be kept cool, 
 otherwise the heat produced by the chemical 
 union, is very apt to expel oxygen from the 
 lime, and generate some chloride of calcium. 
 Mr Dalton advises the use of solution of 
 copperas, to analyze the bleaching powder. 
 He desires us to add it, till all the chlorine 
 smell disappears, and to measure the quanti- 
 ty of copperas employed. I tried this me- 
 thod, and was nearly killed by it. The re- 
 peated and careful application of the nostrils 
 to the mixture, and the inevitable inhalation 
 of chlorine, evolved by the sulphate of iron, 
 brought on a very painful and dangerous 
 affection of the lungs. 
 
 Tnere is usually a considerable quantity 
 of unsaturated lime in the above powder • 
 the amount of which is readily ascertained 
 by digesting it in water, and filtering. It 
 may be expected, that I should now give my 
 own method of analysis; but the desire of 
 verifying it by some further experiments of a 
 new kind, for which I have hitherto wanted 
 leisure, induces me to suppress it for the 
 present. Under Lime, some observations 
 will be found on the uses of this substance. 
 
 If the liquid hydriodate of lime be eva- 
 porated to dryness, and gently heated, an 
 iodide of calcium remains. It has not been 
 applied to any use.* 
 
 * Calctuff. An alluvial formation of 
 carbonate of lime, probably deposited from 
 calcareous springs. It has a yellowish -grey 
 
 I colour; a dull lustre internally; a fine 
 grained earthy fracture ; is opaque, and 
 usually marked with impressions of vege- 
 table matter. Its specific gravity is nearly 
 
 | the same with that of water. It is soft, and 
 
 I I easily cut or broken.* 
 
 * Calculus, or Stone. This name is ge- 
 
 CAL 
 
 nerally given to all hard concretions, rmt 
 bony, formed in the bodies of animals. Of 
 these the most important, as giving rise to 
 one of the most painful diseases incident to 
 human nature, is the urinary calculus , or 
 stone in the bladder. Different substances 
 occasionally enter into the composition ot 
 this calculus, but the most usual is the litliic 
 acid. 
 
 If we except Scheele’s original observa- 
 tion concerning the uric or litliic acid, all 
 the discoveries relating to urinary concre- 
 tions are due to Dr Wollaston; discoveries 
 so curious and important, as alone are sufficient 
 to entitle him to the admiration and gratitude 
 of mankind. They have been fully verified 
 by the subsequent researches of MM. Four- 
 croy, Vauquelin, and Brande, Drs Henry, 
 Marcet, and Prout. Dr Marcet, in his late 
 valuable essay on the chemical history and 
 medical treatment of calculous disorders, 
 arranges the concretions into nine species. 
 
 1. The litliic acid calculus. 
 
 2. The ammonia-magnesian phosphate cal- 
 culus. 
 
 3. The bone earth calculus, or phosphate 
 of lime. 
 
 4. The fusible calculus, a mixture of the 
 2d and 3d species. 
 
 5. The mulberry calculus, or oxalate of 
 lime. 
 
 6. The cystic calculus ; cystic oxide of 
 Dr Wollaston. 
 
 7. The alternating calculus, composed of 
 alternate layers of different species. 
 
 8. The compound calculus, whose ingre- 
 dients are so intimately mixed, as to be se- 
 parable only by chemical analysis. 
 
 9. Calculus from the prostate gland, which, 
 by Dr Wollaston’s researches, is proved to 
 be phosphate of lime, not distinctly strati- 
 fied, and tinged by the secretion of the pros- 
 tate gland. 
 
 To the above Dr Marcet has added two 
 new sub-species. The first seems to have 
 some resemblance to the cystic oxide, but it 
 possesses also some marks of distinction. It 
 forms a bright lemon-yellow residuum on 
 evaporating its nitric acid solution, and is 
 composed of lamina?. But the cystic oxide 
 is not laminated, and it leaves a white resi- 
 duum from the nitric acid solution. Though 
 they are both soluble in acids as well as al- 
 kalis, yet the oxide is more so in acids than 
 the new calculus, which has been called by 
 Dr Marcet, from its yellow residuum, xanthic 
 oxide. Dr Marcet’s other new calculus, was 
 found to possess the properties of the fibrine 
 of the blood, of which it seems to be a depo- 
 site. lie terms it fibrinous calculus. 
 
 Species 1. Uric acid calculi. Dr Henry 
 says, in bis instructive paper on urinary and 
 other morbid concretions, read before the 
 Medical Society of London, March 2. 1819, 
 that it has never yet occurred to him to exu- 
 
 
CAL 
 
 CAL 
 
 mine a calculi composed of this acid in a 
 state of absolute purity. They contain about 
 9-10ths of the pure acid, along with urea, 
 and an animal matter which is not gelatine, 
 but of an albuminous nature. This must 
 not, however, be regarded as a cement. The 
 calculus is aggregated by the cohesive attrac- 
 tion of the lithic acid itself. The colour of 
 lithic acid calculi is yellowish, or reddish- 
 brown, resembling the appearance of wood. 
 They have commonly a smooth polished sur- 
 face, a lamellar or radiated structure, and 
 consist of line particles well compacted. 
 Their sp. gravity varies from 1.3 to 1.8. 
 They dissolve in alkaline lixivia, without 
 evolving an ammoniacal odour, and exhale 
 the smell of horn before the blow-pipe. The 
 relative frequency of lithic acid calculi will 
 be seen from the following statement. Of 
 150 examined by Mr Brande, 16 were com- 
 posed wholly of this acid, and almost all con- 
 tained more or less of it. Fourcroy and 
 Vauquelin found it in the greater number of 
 500 which they analyzed. All those exa- 
 mined by Scheele consisted of it alone ; and 
 300 analyzed by Dr Pearson, contained it in 
 greater or smaller proportion. According 
 to Dr Henry’s experience, it constitutes JO 
 urinary concretions out of 26, exclusive of 
 the alternating calculi. And Mr Brande 
 lately states, that out of 58 cases of kidney 
 calculi, 51 were lithic acid, 6 oxalic, and 1 
 cystic. 
 
 Species 2. Ammonia-magnesian phos- 
 phate. This calculus is white like chalk, is 
 friable between the fingers, is often covered 
 with dog-tooth crystals, and contains semi- 
 crystalline layers. It is insoluble in alkalis, 
 but soluble in nitric, muriatic, and acetic 
 acids. According to Dr Henry, the earthy 
 phosphates, comprehending the 2d and 3d 
 species, were to the whole number of con- 
 cretions, in the ratio of 10 to 85. Mr 
 Brande justly observes, in the 16th number 
 of his Journal, that the urine has at all times 
 a tendency to deposit the triple phosphate, 
 upon any body over which it passes. Hence 
 drains by which urine is carried off, are often 
 incrusted with its regular crystals ; and in 
 cases where extraneous bodies have got into 
 the bladder, they have often in a very short 
 time become considerably enlarged by depo- 
 sition of the same substance. When this 
 calculus, or those incrusted with its semi- 
 crystalline particles are strongly heated be- 
 fore the blow- pipe, ammonia is evolved, and 
 an imperfect fusion takes place. W lien a 
 little of the calcareous phosphate is present, 
 however, the concretion readily fuses. Cal- 
 culi composed entirely of the ammonia-mag- 
 nesian phosphate are very rare. Mr Brande 
 has seen only two. They were crystallized 
 upon the surface, and their fracture was 
 somewhat foliated. In its pure state, it is 
 
 even rare as an incrustation. The powder 
 of the ammonia-phosphate calculus lias a 
 brilliant white colour, a faint sweetish taste, 
 and is somewhat soluble in water. Four- 
 croy and Vauquelin suppose the above depo- 
 sites to result from incipient putrefaction of 
 urine in the bladder. It is certain that the 
 triple phosphate is copiously precipitated from 
 urine in such circumstances out of the body. 
 
 Species 3. The bone earth calculus. Its 
 surface, according to Dr Wollaston, is ge- 
 nerally pale brown, smooth, and when sawed 
 through, it appears of a laminated texture, 
 easily separable into concentric crusts. Some- 
 times, also, each lamina is striated in a di- 
 rection perpendicular to the surface, as from 
 an assemblage of crystalline needles. It is 
 difficult to fuse this calculus by the blow- 
 pipe, but it dissolves readily in dilute mu- 
 riatic acid, from which it is precipitable by 
 ammonia. This species, as described by 
 Fourcroy and Vauquelin, was white, without 
 lustre, friable, staining the hands, paper, and 
 cloth. It had much of a chalky appearance, 
 and broke under the forceps, and was inti- 
 mately mixed with a gelatinous matter, which 
 is left in a membranous form, when the 
 earthy salt is withdrawn by dilute muriatic 
 acid. Dr Henry says that he has never been 
 able to recognize a calculus of pure phos- 
 phate of lime, in any of the collections which 
 he has examined ; nor did he ever find the 
 preceding species in a pure state, though a 
 calculus in Mr White’s collection contained 
 more than 90 per cent of ammonia-magne- 
 sian phosphate. 
 
 Species 4. The fusible calculus. This is 
 a very friable concretion, of a white colour, 
 resembling chalk in appearance and texture ; 
 it often breaks into lavers, and exhibits a 
 glittering appearance internally, from inter- 
 mixture of the crystals of triple phosphate. 
 Sp. grav. from 1.14 to 1.47. Soluble in 
 dilute muriatic and nitric acids, but not in 
 alkaline lixivia. The nucleus is generally 
 lithic acid. In 4 instances only out of 187, 
 did Dr Henry find the calculus composed 
 throughout of the earthy phosphates. The 
 analysis of fusible calculus is easily perform- 
 ed by distilled vinegar, which at a gentle 
 heat dissolves the ammonia- magnesian phos- 
 phate, but not the phosphate of lime ; the 
 latter may be taken up by dilute muriatic 
 acid. The lithic acid present will remain, 
 and may be recognized by its solubility in 
 the water of pure potash or soda. Or the 
 lithic acid may, in the first instance, be re- 
 moved by the alkali, which expels the am- 
 monia, and leaves the phosphate of magne- 
 sia and lime. 
 
 Species 5. The mulberry calculus. Its 
 surface is rough and tuberculatcd ; colour 
 deep reddish-brown. Sometimes it is pale 
 brown, of a crystalline texture, and co'vercd 
 
CAL 
 
 CAL 
 
 with flat octahedral crystals. This calculus 
 has commonly the density and hardness of 
 ivory, a sp. grav. from 1.4 to 1.98, and ex- 
 hales the odour of semen when sawed. A 
 moderate red heat converts it into carbonate 
 of lime. It does not dissolve in alkaline 
 lixivia, but slowly and with difficulty in 
 acids. When the oxalate of lime is voided 
 directly after leaving the kidney, it is of a 
 greyish-brown colour, composed of small co- 
 hering spherules, sometimes with a polished 
 surface resembling hempseed. They are 
 easily recognized by their insolubility in 
 muriatic acid, and their swelling up and 
 passing into pure lime before the blow- pipe. 
 Mulberry calculi contain always an admix- 
 ture of other substances besides oxalate of 
 lime. These are, uric acid, phosphate of 
 lime, and animal matter in dark flocculi. 
 The colouring matter of these calculi is pro- 
 bably effused blood. Dr Henry rates the 
 frequency of this species at l in 1 7 of the 
 whole which he has compared ; and out of 
 187 calculi, he found that 17 were formed 
 round nuclei of oxalate of lime. 
 
 Species 6. The cystic-oxide calculus. It 
 resembles a little the triple phosphate, or 
 more exactly magnesian limestone. It is 
 somewhat tough when cut, and has a pecu- 
 liar greasy lustre. Its usual colour is pale 
 brown, bordering on straw- yellow ; and its 
 texture is irregularly crystalline. It unites 
 in solution with acids and alkalis, crystal- 
 lizing with both. Alcohol precipitates it 
 from nitric acid. It does not become red 
 with nitric acid, and it has no effect upon 
 vegetable blues. Neither water, alcohol, nor 
 ether dissolves it. It is decomposed by heat 
 into carbonate of ammonia and oil, leaving a 
 minute residuum of phosphate of lime. This 
 concretion is of very rare occurrence. Dr 
 Henry states its frequency to the whole, as 
 10 to 985. In two which he examined, the 
 nucleus was the same substance with the 
 rest of the concretion ; and in a third, the 
 nucleus of an uric acid calculus was a small 
 spherule of cystic oxide. Hence, as Dr 
 Marcet has remarked, this oxide appears to 
 be in reality the production of the kidneys, 
 and not, as its name would import, to be ge- 
 nerated in the bladder. It might be called 
 with propriety renal oxide, if its eminent 
 discoverer should think fit. 
 
 Species 7. The alternating calculus. The 
 surface of this calculus is usually white like 
 chalk, and friable or semi-crystalline, accord- 
 ing as the exterior coat is the calcareous or 
 ammonia-magnesian phosphate. They are 
 frequently of a large size, and contain a 
 nucleus of lithic acid. Sometimes the two 
 phosphates form alternate layers round the 
 nucleus. The above are the most common 
 alternating calculi ; next are those of oxa- 
 late of lime with phosphates; then oxalate 
 
 of lime with lithic acid ; and lastly, those in 
 which the three substances alternate. Ihe 
 alternating, taken all together, occur in 10 
 out of 25, in Dr Henry’s list ; the lithic 
 acid with phosphates as 10 to 48 ; the oxa- 
 late of lime with phosphates, as 10 to 1 16 ; 
 the oxalate of lime with lithic acid, as 10 to 
 1 70 ; the oxalate of lime, with lithic acid 
 and phosphates, as 10 to 265. 
 
 Species 8. The compound calculus. This 
 consists of a mixture of lithic acid with the 
 phosphates in variable proportions, and is 
 consequently variable in its appearance. 
 Sometimes the alternating layers are so thin 
 as to be undistinguishable by the eye, when 
 their nature can be determined only by che- 
 mical analysis. This species, in Dr Henry’s 
 list, forms 10 in 235. About l-40th of the 
 calculi examined by Tourcroy and Vauque- 
 lin were compound. 
 
 Species 9. has been already described. 
 
 In almost all calculi, a central nucleus 
 may be discovered, sufficiently small to 
 have descended through the ureters into 
 the bladder. The disease of stone is to be 
 considered, therefore, essentially and origin- 
 ally as belonging to the kidneys. Its in- 
 crease in the bladder may be occasioned, 
 either by exposure to urine that contains an 
 excess of the same ingredient as that com- 
 posing the nucleus, in which case it will be 
 uniformly constituted throughout ; or if the 
 morbid nucleus deposite should cease, the 
 concretion will then acquire a coating of the 
 earthy phosphates. It becomes, therefore, 
 highly important to ascertain the nature of 
 the most predominant nucleus. Out of 187 
 calculi examined by Dr Henry, 17 were 
 formed round nuclei of oxalate of lime ; 3 
 round nuclei of cystic oxide; 4 round nuclei 
 of the earthy phosphates; 2 round extra- 
 neous substances ; and in 3 the nucleus was 
 replaced by a small cavity, occasioned pro- 
 bably by the shrinking of some animal mat- 
 ter, round which the ingredients of the cal- 
 culi (fusible) had been deposited. Rau has 
 shewn by experiment, that pus may form the 
 nucleus of an urinary concretion. The re- 
 maining 158 calculi of Dr Henry's list, had 
 central nuclei composed chiefly of lithic acid. 
 It appears also, that in a very great majority 
 of the cases referred to by him, the disposi- 
 tion to secrete an excess of lithic acid has 
 been the essential cause of the origin of 
 stone. Hence it becomes a matter of great 
 importance to inquire, what are the circum- 
 stances which contribute to its excessive pro- 
 duction, and to ascertain bv what plan of 
 diet and medicine this morbid action of the 
 kidneys may best be obviated or removed. 
 A calculus in Mr White’s collection had for 
 its nucleus a fragment of a bougie, that had 
 slipped into the bladder. It belonged to the 
 fusible species, consisting of, 
 
CAL 
 
 CAL 
 
 20 phosphate of lime 
 60 ammonia-magnesian phosphate 
 10 lithic acid 
 10 animal matter 
 
 100 
 
 In some instances, though these are com- 
 paratively very few, a morbid secretion of 
 the earthy phosphates in excess, is the cause 
 of the formation of stone. Dr Henry re- 
 lates the case of a gentleman, who, during 
 paroxysms of gravel, preceded by severe 
 sickness and vomiting, voided urine as 
 opaque as milk,, which deposited a great 
 quantity of an impalpable powder, consist- 
 ing of the calcareous and triple phosphate 
 in nearly equal proportions. The weight 
 of the body was rapidly reduced from 188 
 to 100 pounds, apparently by the abstrac- 
 tion of the earth of his bones ; for there 
 was no emaciation of the muscles cor- 
 responding to the above diminution. 
 
 The first rational views on the treatment 
 of calculous disorders, were given by Dr 
 Wollaston. These have been followed up 
 lately by some very judicious observations of 
 Mr Braude, in the 12th, 15th, and 16th 
 numbers of his Journal ; and also by Dr 
 Marcet, in his excellent treatise already re- 
 ferred to. Of the many substances con- 
 tained in human urine, there are rarely 
 more than three which constitute gravel ; 
 viz. calcareous phosphate, ammonia-magne- 
 sian phosphate, and lithic acid. The for- 
 mer two form a white sediment; the latter 
 a red or brown. The urine is always an 
 acidulous secretion. Since by this excess of 
 acid, the earthy salts, or white matter, are 
 held in solution, whatever disorder of the 
 system, or impropriety of food and medicine, 
 diminishes that acid excess, favours the for- 
 mation of white deposit. The internal use 
 of acids was shewn by Dr Wollaston, to be 
 the appropriate remedy in this case. 
 
 White gravel is frequently symptomatic 
 of disordered digestion, arising from excess 
 in eating or drinking ; and it is often pro- 
 duced by too farinaceous a diet. It is also 
 occasioned by the indiscreet use of magnesia, 
 soda water, or alkaline medicines in general. 
 Medical practitioners, as well as their pa- 
 tients, ignorant of chemistry, have often 
 committed fatal mistakes, by considering 
 the white gravel, passed on the administra- 
 tion of alkaline medicines, as the dissolution 
 of the calculus itself ; and have hence push- 
 ed a practice, which has rapidly increased 
 the size of the stone. Magnesia, in many 
 cases, acts more injuriously than alkali, in 
 precipitating insoluble phosphate from the 
 urine. The acids of urine, which, by their 
 excess, hold the earths in solution, are the 
 phosphoric, lithic, and carbonic. Mr Brande 
 lias uniformly obtained the latter acid, by 
 
 placing urine under an exhausted receiver ; 
 and he has formed carbonate of barytes, 
 by dropping barytes water into urine recent- 
 ly voided. 
 
 The appearance of white sand does not 
 seem deserving of much attention, where it 
 is merely occasional, following indigestiou 
 brought on by an accidental excess. But if 
 it invariably follows meals, and if it be ol>- 
 served in the urine, not as a mere deposite, 
 but at the time the last drops are voided, it 
 becomes a matter of importance, as the fore- 
 runner of other and serious forms of the dis- 
 order. It has been sometimes, viewed as the 
 effect of irritable bladder, where it was in 
 reality the cause. Acids are the proper 
 remedy, and unless some peculiar tonic effect 
 be sougiit for in sulphuric acid, the vegeta- 
 ble acids ought to be preferred. Tartar, or 
 its acid, may bo prescribed with advantage, 
 but the best medicine is citric acid, in daily 
 doses of from 5 to 30 grains. Persons re- 
 turning from warm climates, with dyspeptic 
 and hepatic disorders, often void this white 
 gravel, for which they have recourse to em- 
 pyrical solvents, for the most part alkaline, and 
 are deeply injured. They ought to adopt an 
 acidulous diet, abstaining from soda water, 
 alkalis, malt liquor, madeira and port ; to eat 
 salads with acid fruits ; and if habit requires 
 it, a glass of cyder, champagne or claret, but 
 the less of these fermented liquors the better. 
 An effervescing draught is often very bene- 
 ficial, made by dissolving 30 grains of bi- 
 carbonate of potash, and 20 of citric acid, in 
 separate tea cups of water, mixing the solu- 
 tion in a large tumbler, and drinking the whole 
 daring the effervescence. This dose may be 
 repeated 3 or 4 times a-day. The carbonic 
 acid of the above medicine enters the circu- 
 lation, and passing off by the bladder, is use- 
 ful in retaining, particularly, the triple phos- 
 phate in solution, as was first pointed out by 
 Dr Wollaston. The bowels should be kept 
 regular by medicine and moderate exercise. 
 The febrile affections of children are fre- 
 quently attended by an apparently formida- 
 ble deposite of white sand in the urine. A 
 dose of calomel will generally carry off both 
 the fever and the sand. Air, exercise, bark, 
 bitters, mineral tonics, are in like manner 
 often successful in removing the urinary 
 complaints of grown up persons. 
 
 In considering the red gravel, it is neces- 
 sary to distinguish between those cases in 
 which the sand is actually voided, and those 
 in which it is deposited, after some hours, 
 from originally limpid urine. In the first, 
 the sabulous appearance is an alarming in- 
 dication of a tendency to form calculi ; in 
 the second, it is often merely a fleeting symp- 
 tom of indigestion. Should it frequently 
 recur, however, it is not to be disregarded. 
 
 Bicarbonate of potash or soda is the pro- 
 
CAL 
 
 CAL 
 
 per remedy for the red sand, or lithic acid 
 deposite. The alkali may often be benefi- 
 cially combined with opium. Ammonia, or 
 its crystallized carbonate, may be resorted to 
 with advantage, where symptoms of indiges- 
 tion are brought on by the other alkalis ; 
 and particularly in red gravel connected 
 with gout, in which the joints and kidneys 
 are affected by turns. Where potash and 
 soda have been so long employed as to dis- 
 agree with the stomach, to create nausea, 
 flatulency, a sense of weight, pain, and othei 
 symptoms of indigestion, magnesia may be 
 prescribed with the best effects, i he ten- 
 dency which it has to accumulate in danger- 
 ous quantities in the intestines, and to foim 
 a white sediment in urine, calls on the prac- 
 titioner to look minutely after its adminis- 
 tration. It should be occasionally alternated 
 with other laxative medicines. Magnesia 
 dissolved in carbonic acid, as Mr Scheweppe 
 used to prepare it many years ago, by the 
 direction of Mr Brande, is an elegant form 
 of exhibiting this remedy. 
 
 Care must be had not to push the alkaline 
 medicines too far, lest they give rise to the 
 deposition of earthy phosphates in the urine. 
 
 Cases occur in which the sabulous depo- 
 site consists of a mixture of lithic acid with 
 the phosphates. The sediment of urine in 
 inflammatory disorders is sometimes of this 
 nature ; and of those persons who habitually 
 indulge in excess of wine ; as also of those 
 who, labouring under hepatic affections, se- 
 crete much albumen in their urine. Purges, 
 tonics, and nitric acid, which is the solvent 
 of both the above sabulous matters, are the 
 appropriate remedies. The best diet for pa- 
 tients labouring under the lithic deposite, is 
 a vegetable. Dr Wollaston’s fine observa- 
 tion, that the excrement of birds fed solely 
 upon animal matter, is in a great measure 
 lithic acid, and the curious fact since ascer- 
 tained, that the excrement of the boa con- 
 strictor, fed also entirely on animals, is pure 
 lithic acid, concur in giving force to the 
 above dietetic prescription. A week’s ab- 
 stinence from animal food has been known 
 to relieve a fit of lithic acid gravel, where 
 the alkalis were of little avail. But we 
 must not carry the vegetable system so far 
 as to produce flatulency and indigestion. 
 
 Such are the principal circumstances con- 
 nected with the disease of gravel in its inci- 
 pient or sabulous state. The calculi form- 
 ed in the kidneys are, as we have said above, 
 either lithic, oxalic, or cystic ; and very rare- 
 ly indeed of the phosphate species. An 
 aqueous regimen, moderate exercise on 
 horseback when not accompanied with much 
 irritation, cold bathing, and mild aperients, 
 along with the appropriate chemical medi- 
 cines, must he prescribed in kidney eases. 
 These are particularly requisite immediately 
 after acute pain in the region of the ureter, 
 
 and inflammatory symptoms have led to the 
 belief that a nucleus has descended into the 
 bladder. Purges, diuretics, and diluents, 
 ought to be liberally enjoined. A large 
 quantity of mucus streaked witli blood, or of 
 a purulent aspect, and haemorrliagy, are fre- 
 quent symptoms of the passage of the stone 
 into the bladder. 
 
 When a stone has once lodged in the 
 bladder, and increased there to such a size 
 as no longer to be capable of passing through 
 the urethra, it is generally allowed, by all 
 who have candidly considered the subject, 
 and who are qualified by experience to be 
 judges, that the stone can never again be 
 dissolved; and although it is possible that it 
 may become so loosened in its texture, as to 
 be voided piecemeal, or gradually to crumble 
 away, the event is so rare as to be barely pro- 
 bable. 
 
 By examining collections of calculi we 
 learn, that in by far the greater number of 
 cases, a nucleus of lithic acid is enveloped 
 in a crust of the phosphates. Our endea- 
 vours must therefore be directed towards re- 
 ducing the excess of lithic acid in the urine 
 to its natural standard ; or, on the other 
 hand, to lessen the tendency to the deposition 
 of the phosphates. The urine must be sub- 
 mitted to chemical examination, and a suit- 
 able course of diet and medicines prescribed. 
 But the chemical remedies must be regu- 
 lated nicely, so as to hit the happy equili- 
 brium, in which no deposite will be formed. 
 Here is a powerful call on the physicians 
 and surgeons to make themselves thoroughly 
 versant in chemical science ; for they will 
 otherwise commit the most dangerous blun- 
 ders in calculous complaints. 
 
 “ The idea of dissolving a calculus of 
 uric acid in the bladder by the internal use 
 of the caustic alkalis,” says Mr Brande, 
 
 “ appears too absurd to merit serious refuta- 
 tion.” In respect to the phosphates, it seems 
 possible, by keeping up an unusual acidity 
 in the urine, so far to soften a crust of the 
 calculus, as to make it crumble down, or ad- 
 mit of being abraded by the sound ; but this 
 is the utmost that can be looked for ; and 
 the lithic nucleus will still remain. “ These 
 considerations,” adds Mr Brande, “ inde- 
 pendent of more urgent reasons, shew the 
 futility of attempting the solution of a stone 
 of the bladder by the injection of acid and 
 alkaline solutions. In respect to the alkalis, 
 if sufficiently strong to act upon the uric 
 crust of the calculus, they would certainly 
 injure the coats of the bladder ; they would 
 otherwise become inactive by combination 
 with the acids of the urine, and they would 
 form a dangerous precipitate from the same 
 cause.” — It therefore appears to me, that 
 Fourcroy, and others who have advised the 
 plan of injection, have thought little of all 
 these obstacles to success, and have regarded 
 
CAL 
 
 CAT 
 
 the bladder as a lifeless receptacle into which, 
 as into an India rubber bottle, almost any 
 solvent might be injected with impunity.” — 
 Journal of Science, vol. viii. p. 216. 
 
 I have judged it an imperative duty to in- 
 sert the above cautions, from an eminent 
 chemist who has studied this subject in its 
 medical relations, lest the medical student, 
 misled by l)r Thomson’s favourable tran- 
 script of the injection scheme, might be hur- 
 ried into very dangerous practice. 
 
 It does not appear that the peculiarities of 
 water in different districts, have any influence 
 upon the production of calculous disorders. 
 Dr Wollaston’s discovery of the analogy be- 
 tween urinary and gouty concretions, has 
 led to the trial in gravel of the vinum colchi - 
 ci, the specific for gout. By a note to Mr 
 Braude’s dissertation we learn, that benefit 
 has been derived from it in a case of red 
 gravel. 
 
 Dr Henry confirms the above precepts in 
 the following decided language. “ These 
 cases, and others of the same kind, which I 
 think it unnecessary to mention, tend to dis- 
 courage all attempts to dissolve a stone sup- 
 posed to consist of uric acid, after it has at- 
 tained considerable size in the bladder ; all 
 that can be effected under such circum- 
 stances by alkaline medicines appears, as Mr 
 Braude has remarked, to be the precipitating 
 upon it a coating of the earthy phosphates 
 from the urine, a sort of concretion which, 
 as has been observed by various practical 
 writers, increases much more rapidly than 
 that consisting of uric acid only. The same 
 unfavourable inference may be drawn also 
 from the dissections of those persons in whom 
 a stone was supposed to be dissolved by alka- 
 line medicines ; for in these instances it has 
 been found either encysted, or placed out of 
 the reach of the sound by an enlargement of 
 the prostate gland.* 
 
 The urinary calculus of a dog, examined 
 by Dr Pearson, w r as found to consist princi- 
 pally of the phosphates of lime and ammo- 
 nia, with animal matter. Several taken 
 from horses, were of a similar composition. 
 One of a rabbit consisted chiefly of carbo- 
 nate of lime and animal matter, with perhaps 
 a little phosphoric acid. A quantity of sabu- 
 lous matter, neither crystallized nor con- 
 crete, is sometimes found in the bladder of 
 the horse : in one instance there were nearly 
 45 pounds. These appear to consist of car- 
 bonate of lime and animal matter. A cal- 
 culus of a cat gave Fourcroy three parts of 
 carbonate, and one of phosphate of lime. 
 That of a pig, according to Bcrtholdi, was 
 phosphate of lime. 
 
 The renal calculus in man appears to be 
 of the same nature as the urinary. In that 
 of the horse, Fourcroy found S parts of car- 
 bonate, and one of phosphate of lime. Dr 
 Pearson, in one instance, carbonate of lime, 
 
 and animal matter ; in two others, phos- 
 phates of lime and ammonia, with animal 
 matter. 
 
 Arthritic calculi, or those formed in the 
 joints of gouty persons, were once supposed 
 to be carbonate of lime, whence they were 
 called chalkstones ; afterward it was suppos- 
 ed that they were phosphate of lime ; but 
 Dr Wollaston has shewn, that they are 
 lithate of soda. The calculi found some- 
 times in the pineal, prostate, salivary, and 
 bronchial glands, in the pancreas, in the 
 corpora cavernosa penis, and between the 
 muscles, as well as the tartar, as it is called, 
 that encrusts the teeth, appear to be phos- 
 phate of lime. Dr Crompton, however, ex- 
 amined a calculus taken from the lungs of a 
 deceased soldier, which consisted of lime 45, 
 carbonic acid 37, albumen and water 18. 
 It was very hard, irregularly spheroidal, and 
 measured about inches in circumference. 
 
 For the biliary calculi, see Gall. Those 
 called bezoars have been already noticed un- 
 der that article. 
 
 It has been observed, that the lithic acid, 
 which constitutes the chief part of most 
 human urinary calculi, and abounds in the 
 arthritic, has been found in no phytivorous 
 animal ; and hence has been deduced a prac- 
 tical inference, that abstinence from animal 
 food would prevent their formation. But 
 we are inclined to think this conclusion too 
 hasty. The cat is carnivorous ; but it ap- 
 peared above, that the calculus of that ani- 
 mal is equally destitute of lithic acid. If, 
 therefore, w^e would form any deduction 
 with respect to regimen, we must look for 
 something used by man, exclusively of all 
 other animals ; and this is obviously found 
 in fermented liquors, but apparently in no- 
 thing else : and this practical inference is 
 sanctioned by the most respectable medical 
 authorities. 
 
 On Caloric. By Dr TJrc . 
 
 * Caloric. The Agent to which the 
 phenomena of heat and combustion are 
 ascribed. This is hypothetically regarded as 
 a fluid, of inappreciable tenuity, whose par- 
 ticles are endowed with indefinite idio-repul- 
 sive powers, and which by their distribution 
 in various proportions among the particles of 
 ponderable matter, modifies cohesive attrac- 
 tion, giving birth to the three general forms 
 of gaseous, liquid, and solid. 
 
 Many eminent philosophers, however, have 
 doubted the separate entity of a calorific 
 matter, and have adduced evidence to shew r 
 that the phenomena might be rather referred 
 to a vibratory or intestinal motion of the par- 
 ticles of common matter. The most distin- 
 guished advocate of this opinion in modern 
 times is Sir II. Davy, the usual justness and 
 nrofunditv of whose view r s entitle them to dc- 
 
 1 V 
 
CAL 
 
 CAL 
 
 ference. The following sketch of his ideas 
 on this intricate subject, though it graduates 
 perhaps into the poetry of science, cannot 
 fail to increase our admiration of his genius, 
 and to inculcate moderation on the partisans 
 of the opposite doctrine. 
 
 “ Calorific repulsion has been accounted 
 for by supposing a subtile fluid capable of 
 combining with bodies, and of separating 
 their parts from each other, which has been 
 named the matter of heat or caloric. 
 
 “ Many of the phenomena admit of a happy 
 explanation on this idea, such as the cold 
 produced during the conversion of solids 
 into fluids or gases, and the increase of tem- 
 perature connected with the condensation of 
 gases and fluids.” In the former case we 
 say the matter of heat is absorbed or com- 
 bined ; in the latter it is extended or disen- 
 gaged from combination. “ But there are 
 other facts which are not so easily reconciled 
 to the opinion. Such are the production of 
 heat by friction and percussion ; and some 
 of the chemical changes which have been 
 just referred to.” These are the violent 
 heat produced in the explosion of gunpow- 
 der, where a large quantity of aeriform mat- 
 ter is disengaged ; and the fire which ap- 
 pears in the decomposition of the euchlorine 
 gas, or protoxide of chlorine, though the 
 resulting gases occupy a greater volume. 
 
 “ When the temperature of bodies is raised 
 by friction, there seems to be no diminution 
 of their capacities, using the w ord in its com- 
 mon sense ; and in many chemical changes, 
 connected with an increase of temperature, 
 there appears to be likewise an increase of 
 capacity. A piece of iron made red-hot by 
 hammering, cannot be strongly heated a se- 
 cond time by the same means, unless it 
 has been previously introduced into a fire. 
 This fact has been explained by supposing 
 that the fluid of heat has been pressed 
 out of it, by the percussion, which is reco- 
 vered in the fire ; but this is a very rude 
 mechanical idea : the arrangements of its 
 parts are altered by hammering in this w'ay, 
 and it is rendered brittle. By a moderate 
 degree of friction, as would appear from 
 liumford’s experiments, the same piece of 
 metal may be kept hot for any length of 
 time ; so that if heat be pressed out, the 
 quantity must be inexhaustible. When any 
 body is cooled, it occupies a smaller volume 
 than before ; it is evident therefore that its 
 parts must have approached to each other ; 
 when the body is expanded by heat, it is 
 equally evident that its parts must have se- 
 parated from each other. The immediate 
 cause of the phenomena of heat, then, is mo- 
 tion, and the laws of its communication are 
 precisely the same as the law's of the com- 
 munication of motion.” “ Since all matter 
 may be made to fill a smaller volume by 
 cooling, it is evident that the particles of 
 
 matter must have space between them ; and 
 since every body can communicate the power 
 of expansion to a body of a lower tempera- 
 ture, that is, can give an expansive motion 
 to its particles, it is a probable inference that 
 its own particles are possessed of motion ; 
 but as there is no change in the position of 
 its parts as long as its temperature is uni- 
 form, the motion, if it exist, must be a vibra- 
 tory or undulatory motion, or a motion of 
 the particles round their axes, or a motion of 
 particles round each other. 
 
 “ It seems possible to account for all 
 the phenomena of heat, if it be supposed 
 that in solids the particles are in a constant 
 state of vibratory motion, the particles of the 
 hottest bodies moving with the greatest velo- 
 city, and through the greatest space ; that in 
 liquids and elastic fluids, besides the vibra- 
 tory motion, which must be conceived great- 
 est in the last, the particles have a motion 
 round their (jwn axes, with different veloci- 
 ties, the particles of elastic fluids moving 
 w ith the greatest quickness ; and that in 
 ethereal substances ;” the particles move 
 round their own axes, and separate from 
 each other, penetrating in right lines through 
 space. Temperature may be conceived to 
 depend upon the velocities of the vibrations ; 
 increase of capacity on the motion being 
 performed in greater space ; and the diminu- 
 tion of temperature, during the conversion of 
 solids into fluids or gases, may be explained 
 on the idea of the loss of vibratory motion, 
 in consequence of the revolution of particles 
 round their axes, at the moment when the 
 body becomes liquid or aeriform ; or from the 
 loss of rapidity of vibration, in consequence 
 of the motion of the particles through greater 
 space. 
 
 “ If a specific fluid of heat be admitted, 
 it must be supposed liable to most of the af- 
 fections which the particles of common mat- 
 ter are assumed to possess, to account for the 
 phenomena ; such as losing its motion when 
 combining with bodies, producing motion 
 w hen transmitted from one body to another, 
 and gaining projectile motion when passing 
 into free space ; so that many hypotheses 
 must be adopted to account for its agency, 
 which renders this view of the subject less 
 simple than the other. Very delicate expe- 
 riments have been made, which shew' that 
 bodies, when heated, do not increase in 
 weight. This, as far as it goes, is an evi- 
 dence against a subtile elastic fluid, produc- 
 ing the calorific expansion ; but it cannot be 
 considered as decisive, on account of the im- 
 perfection of our instruments. A cubical 
 inch of inflammable air requires a good ba- 
 lance to ascertain that it has any sensible 
 weight, and a substance bearing the same re- 
 lation to this, that this bears to platinum, 
 could not perhaps be weighed by any method 
 in our possession.” 
 
CAL 
 
 CAL 
 
 It has been supposed, on the other hand, 
 that the observations of Sir Wm. Herschel 
 on the calorific rays which accompany those 
 ot light in the solar beam, afford decisive 
 evidence of the materiality of caloric, or at 
 least place the proof of its existence and that 
 of light, on the same foundation. That cele- 
 brated astronomer discovered that when simi- 
 lar thermometers were placed in the diffe- 
 rent parts of the solar beam, decomposed by 
 the prism into the primitive colours, they in- 
 dicated different temperatures. He esti- 
 mates the power of heating in the red rays, 
 to be to that of the green rays, as 55 to 26, 
 and to that of the violet rays as 55 to 16, 
 And in a space beyond the red rays, where 
 there is no visible light, the increase of tem- 
 perature is greatest of all. Thus, a thermo- 
 meter in the full red ray rose 7° Fahr. in ten 
 minutes ; beyond the confines of the coloured 
 beam entirely, it rose in an equal time 9°. 
 
 These experiments were repeated by Sir 
 H. Englefield with similar results. Mr 
 Berard, however, came to a somewhat diffe- 
 rent conclusion. To render his experiments 
 more certain, and their effects more sensible, 
 this ingenious philosopher availed himself of 
 the heliostat , an instrument by which the 
 sunbeam can be steadily directed to one 
 spot during the whole of its diurnal period. 
 He decomposed by a prism the sunbeam, 
 reflected from the mirror of the heliostat, 
 and placed a sensible thermometer in each 
 of the seven coloured rays. The calorific 
 faculty was found to increase progressively 
 from the violet to the red portion of the 
 spectrum, in which the maximum heat exist- 
 ed, and not beyond it, in the unilluminated 
 space. The greatest rise in the thermometer 
 took place, while its bulb was still entirely 
 covered by the last red rays ; and it w r as ob- 
 served progressively to sink as the bulb en- 
 tered into the dark. Finally, on placing the 
 bulb quite out of the visible spectrum, where 
 Herschel fixed the maximum of heat, the ele- 
 vation of its temperature above the ambient 
 air was found, by M. Berard, to be only 
 one-fifth of what it was in the extreme red 
 ray. He afterwards made similar experi- 
 ments on the double spectrum produced by 
 Island crystal, and also on polarized light, 
 and he found in both cases that the calorific 
 principle accompanied the luminous mole- 
 cules; and that in the positions where light 
 ceased to be reflected, heat also disappeared. 
 
 Newton has shewn that the different refran- 
 gibility of the rays of light may be explained 
 by supposing them composed of particles 
 differing in size, the largest being at the red, 
 and the smallest at the violet extremity of 
 the spectrum. 'Hie same great man has put 
 the query, Whether light and common mat- 
 ter are not convertible into each other ? and 
 adopting the idea that the phenomena of 
 sensible heat depend upon vibrations of the 
 
 particles of bodies, supposes that a certain 
 intensity of vibrations may send off' particles 
 into free space ; and that particles in rapid 
 motion in right lines, in losing their own mo- 
 tion, may communicate a vibratory motion to 
 the particles of terrestrial bodies, "in this way 
 we can readily conceive how the red rays, 
 should impinge most forcibly, and therefore 
 excite the greatest degree of heat. 
 
 Enough has now been said to shew how 
 little room there is to pronounce dogmatic 
 decisions on the abstract nature of heat. If 
 the essence of the cause be still involved in 
 mystery, many of its properties and effects 
 have been ascertained, and skilfully applied to 
 the cultivation of science and the uses of life. 
 
 We shall consider them in the following 
 order : 
 
 1. Of the measure of temperature. 
 
 2. Of the distribution of heat. 
 
 5. Of the general habitudes of heat with 
 the different forms of matter. 
 
 It will be convenient to make use of the 
 popular language, and to speak of heat as 
 existing in bodies in greater or smaller quan- 
 tities, without meaning thereby to decide on 
 the question of its nature. 
 
 1. Of the measure of temperature. 
 
 If a rod or ring of metal of considerable 
 size, which is fitted to an oblong or circular 
 gauge in its ordinary state, be moderately 
 heated, it will be found, on applying it to 
 the cool gauge, to have enlarged its dimen- 
 sions. It is thus that coachmakers enlarge 
 their strong iron rims, so as to make them 
 embrace and firmly bind, by their retraction 
 when cooled, the wooden frame-work of their 
 wheels. 
 
 Ample experience has proved, that bodies, 
 by being progressively heated, progressively 
 increase in bulk. On this principle are 
 constructed the various instruments for mea- 
 suring temperature. If the body selected for 
 indicating, by its increase of bulk, the in- 
 crease of heat, suffered equal expansions by 
 equal increments of the calorific power, then 
 the instrument w r ould be perfect, and we 
 should have a just thermometer, or pyrome- 
 ter. But it is very doubtful whether any 
 substance, solid, liquid, or aeriform, preserves 
 this equable relation, between its increase of 
 volume and increase of heat. The following 
 quotation from a paper which the Royal So- 
 ciety did me the honour to publish in their 
 Transactions for 1818, conveys my notions 
 on this subject : 
 
 “ I think it indeed highly probable, that 
 every species of matter, both solid and liquid, 
 follows an increasing rate in its enlargement 
 by caloric. Each portion that enters into a 
 body must weaken the antagonist force, co- 
 hesion, and must therefore render more effi- 
 cacious the operation of the next portion that 
 is introduced. Let 1000 represent the co- 
 hesive attraction at the commencement, then, 
 
CAL 
 
 CAL 
 
 after receiving one increment of caloric, it 
 will become 1000 — 1 = 999. Since the 
 next unit of that divellent agent will have to 
 combat only this diminished cohesive force, 
 it will produce an effect greater than the 
 first, in the proportion of 1000 to 999, and 
 so on in continued progression. That the 
 increasing ratio is, however, greatly less than 
 Mr Dalton maintains, may, I think, be 
 clearly demonstrated.” P. 34. 
 
 The chief object of the second chapter of 
 that memoir, is the measure of temperature. 
 The experiments on which the reasoning ot 
 that part is founded, were made in the years 
 1812 and 1813, in the presence of many 
 philosophical friends and pupils. By means 
 of two admirable micrometer microscopes of 
 Mr Troughton’s construction, attached to a 
 peculiar pyrometer, I found, that between 
 the temperatures of melting ice, and the 540th 
 degree Fahr., the apparent elongations of 
 rods of pure copper and iron corresponded 
 pari passu with the indications of two mercu- 
 rial thermometers of singular nicety, made by 
 Mr Crighton of Glasgow, one of which cost 
 three guineas, and the other two, and they 
 were compared with a very fine one of Mr 
 Troughton’s. I consider the above results, 
 and others contained in that same paper, as 
 decisive against Mr Dalton’s hypothetical 
 graduation of thermometers. They were 
 obtained and detailed in public lectures 
 many years before the elaborate researches of 
 Messrs Petit and Dulong on the same sub- 
 ject appeared ; and indeed the paper itself pass- 
 
 ed through Dr Thomson’s hands, to Dondon, 
 many months before the excellent disserta- 
 tion of the French philosophers was publish- 
 ed. Their memoir gained a well-merited 
 prize, voted by the Academy of Sciences, on 
 the 16th March 1818. My paper was sub- 
 mitted the preceding summer, in its fin- 
 ished state, to three professors of the Uni- 
 versity of Glasgow, as well as to Dr Brewster 
 and Dr Murray. 
 
 The researches of MM. Dulong and Petit 
 are contained in the 7th volume of the 
 Annales de Chimie et Physique. They 
 commence with some historical details, in 
 which they observe, “ that Mr Dalton, con- 
 sidering this question from a point of view 
 much more elevated, has endeavoured to 
 establish general Jaws applicable to the mea- 
 surement of all temperatures. These laws, 
 it must be acknowledged, form an imposing 
 whole by their regularity and simplicity. 
 Unfortunately, this skilful philosopher pro- 
 ceeded with too much rapidity to generalize 
 his very ingenious notions, but which de- 
 pended on uncertain data. The consequence 
 is, that there is scarcely one of his assertions 
 but what is contradicted by the result of the 
 researches, w hich we are now going to make 
 known.’* M. Gay Lussac had previously 
 shewn, that between the limits cf freezing 
 and boiling water, a mercurial air thermome- 
 ter did not present any sensible discordance. 
 The following table of MM. Dulong and 
 Petit gives the results from nearly the freez- 
 ing to the boiling point of mercury. 
 
 TABLE of Comparison of the Mercurial and Air Thermometer. 
 
 Temperature indicated by the 
 mercurial. 
 
 Corresponding 
 vols. of the same 
 mass of air. 
 
 Temperature indicated by an air ther. 
 corrected for the dilatation of glass. 
 
 Centigr. 
 
 Fahr. 
 
 Centigr. 
 
 Fahr. 
 
 —36° 
 
 —32.8 3 
 
 0.8650 
 
 —36.00° 
 
 — 32.8° 
 
 0 
 
 +32. 
 
 1 .0000 
 
 0.00 
 
 +52.0 
 
 100 
 
 212 
 
 1.3750 
 
 100.00 
 
 212.0 
 
 150 
 
 302 
 
 1.5576 
 
 148.70 
 
 299.66 
 
 200 
 
 392 
 
 1.7389 
 
 1 97.05 
 
 586.69 
 
 250 
 
 482 
 
 1.9189 
 
 245.05 
 
 475.09 
 
 soo 
 
 572 
 
 2.0976 
 
 292.70 
 
 558.86 
 
 Boiling, 860 
 
 680 
 
 2.3125 
 
 550.00 
 
 662.00 
 
 The well known uniformity in the princi- 
 pal physical properties of all the gases, and 
 particularly the perfect identity in the laws 
 of their dilatation, render it very probable, 
 that in this class of bodies the disturbing: 
 causes, to which I have adverted in my pa- 
 per, have not the same influence as in solids 
 and liquids* and that consequently the 
 changes in volume produced by the action of 
 heat upon air and gases, are more immedi- 
 ately dependent upon the force which pro- 
 duces them. It is therefore very probable, 
 
 that the greatest number of the phenomena 
 relating to heat will present themselves under 
 a more simple form, if we measure the tem- 
 peratures by an air thermometer. 
 
 I coincide with these remarks of the French 
 chemists, and think they were justified by 
 such considerations to employ the scale of an 
 air thermometer in their subsequent re- 
 searches, which form the second part of their 
 memoir on the laws of the communication 
 of heat. 
 
 The boiling point of mercury, according 
 
CM 
 
 CAL 
 
 to MM. Dulong and Petit, measured by a 
 true thermometer, is 662° of Fahr. degrees. 
 Now by Mr Crighton’s thermometer the 
 boiling point is 656°, a difference of only 
 6° in that prodigious range. Hence we see, 
 as I pointed out in my paper, that there is a 
 compensation produced between the une- 
 quable expansions of mercury and glass, and 
 the lessening mass of mercury remaining in 
 the bulb as the temperatures rise, whereby 
 his thermometer becomes a true measurer of 
 the increments of sensible caloric. From 
 all the experiments which have been made 
 with care, we are safe in assuming the appa- 
 rent expansion of mercury in glass to be 
 l-63d part of its volume on an average for 
 every 180° Fahr. between 32° and 662°, or 
 through an interval of 7 times 90 degrees. 
 Hence the apparent expansion in glass for 
 the whole is, = -J,,- = ^ = 350 
 
 Fahr. 
 
 Were the whole body of the thermometer, 
 stem, and bulb, immersed in boiling mercu- 
 ry, it would therefore indicate 35° more than 
 it does when the bulb alone is immersed, or 
 it would mark nearly 691° by Crighton. 
 But the abstraction made of these 35°, in 
 consequence of the bulb alone being im- 
 mersed in the heated liquids, brings back 
 the common mercurial scale, when well exe- 
 cuted, near to the absolute and just scale of 
 an air thermometer, corrected for the expan- 
 sions of the containing glass. 
 
 Dr Thomson, in his Annals for March 
 1819, has, in his account of my paper, hazard- 
 ed some remarks on this subject, which it 
 will be necessary merely to quote in order to 
 see their futility : “ From Mr Crighton’s 
 mode of graduating thermometers,” says he, 
 “ it is obvious that in the higher parts of the 
 scale the degrees are below the truth. Thus 
 mercury boils, as determined by his thermo- 
 meters, at 556 0 ; the real boiling point, as 
 determined by Dulong and Petit, is 580°. 
 It is probable that Dr Ure also employed a 
 thermometer made by Crighton. But it is 
 unlikely that it should be better than mine, 
 as Mr Crighton was at great pains to make 
 mine as correct as possible, and I paid him a 
 high price for it.” Making due allowance 
 for the oblique censure of this insinua- 
 tion, as well as for the typographical er- 
 ror of 580° instead of 680°, it is obvious 
 that Dr Thomson has misunderstood the 
 merits of the discussion. The real tempera- 
 ture of boiling mercury by Dulong and Pe- 
 tit is 662 0 F. ; the apparent temperature, 
 measured by mercury in glass, both heated 
 to the boiling point of the former, is 680°. 
 But the latter is a false indication, and Mr 
 Crighton’s compensated number 656° is very 
 near the truth. We may therefore consider 
 a well made mercurial thermometer as a 
 sufficiently just measurer of temperature. 
 
 Lor its construction and graduation, see 
 Th e r mom f.ter. 
 
 2. Of the distribution of heat. 
 
 1 his head naturally divides into two parts, 
 first, the modes of distribution, or the laws of 
 cooling, and the communication of heat among 
 aeriform, liquid, and solid substances; and, 
 secondly, the specific heats of different bodies 
 at the same and at different temperatures. 
 
 The first views relative to the laws of the 
 communication of heat are to be found in 
 the opuscula of Newton. This great philo- 
 sopher assumes a priori , that a heated body 
 exposed to a constant cooling cause, such as 
 the uniform action of a current of air, ought 
 to lose at each instant a quantity of heat 
 proportional to the excess of its temperature 
 above that of the ambient air ; and that con- 
 sequently its losses of heat in equal and suc- 
 cessive portions of time ought to form a de- 
 creasing geometrical progression. Though 
 Martin, in his Essays on Heat, pointed out 
 long ago the inaccuracy of the preceding 
 law, which indeed could not fail to strike 
 any person, as it struck me forcibly the mo- 
 ment that I watched the progressive cooling 
 of a sphere of oil which had been heated 
 to the 500th degree, yet the proposition 
 has been passed from one systematist to 
 another without contradiction. 
 
 Erxleben proved, by very accurate obser- 
 vations, that the deviation of the supposed 
 law increases more and more as we consider 
 greater differences of temperatures; and con- 
 cludes that we should fall into very great 
 errors if we extended the law much beyond 
 the temperature at which it has been verifi- 
 ed. Yet Mr Leslie since, in his ingenious 
 researches on heat, has made this law the 
 basis of several determinations, which from 
 that very cause are inaccurate, as has been 
 proved by Dulong and Petit. At length 
 these gentlemen have investigated the true 
 law r in a masterly manner. 
 
 When a body cools in vacuo, its heat is 
 entirely dissipated by radiation. When it is 
 placed in air, or in any other fluid, its cool- 
 ing becomes more rapid, the heat carried oft' 
 by the fluid being in that case added to that 
 which is dissipated by radiation. It is natu- 
 ral therefore to distinguish these two effects ; 
 and as they are subject in all probability to 
 different laws, they ought to be separately 
 studied. 
 
 MM. Dulong and Petit employed in this 
 research mercurial thermometers, whose bulbs 
 were from 0.8 of an inch to 2.6 ; the latter 
 containing about three lbs. of mercury. 
 
 o r 
 
 They found by preliminary trials, that the 
 ratio of cooling was not affected by the size 
 of the bulb, and that it held also in compari- 
 sons of mercury, with water, with absolute 
 alcohol, and with sulphuric acid, through a 
 range of temperature, from 60 to 30 of the 
 
CAL 
 
 CAL 
 
 centigrade scale ; so that the ratio of the 
 velocity of cooling between 60 and 50, and 
 40 and 30, was sensibly the same. On 
 cooling water in a tin plate, and in a glass 
 sphere, they found the law of cooling to be 
 more rapid in the former, at temperatures 
 under the boiling point ; but by a very re- 
 markable casualty, the contrary effect takes 
 place in bodies heated to high temperatures, 
 when the law of cooling in tin plate becomes 
 least rapid. Hence, generally, that which 
 cools by a most rapid law at the lower part 
 of the scale, becomes the least rapid at high 
 temperatures. 
 
 “ Mr Leslie obtained such inaccurate re- 
 sults respecting this question, because he did 
 not make experiments on the cooling of bo- 
 dies raised to high temperatures,” say MM. 
 Dulong and Petit, who terminate their preli- 
 minary researches by experiments on the cool- 
 ing of water in three tin-plate vessels of the 
 same capacity, the first of which was a sphere, 
 the second and third cylinders ; from which 
 we learn that the law of cooling is not affect- 
 i ed by the difference of shape. 
 
 The researches on cooling in a vacuum 
 were made with an exhausted balloon ; and 
 a compensation was calculated for the minute 
 quantity of residuary gas. The following 
 series was obtained when the balloon was 
 surrounded with ice. The degrees are cen- 
 tigrade. 
 
 Excess of the therm, 
 above the balloon. 
 
 240° 
 
 220 
 
 200 
 
 180 
 
 160 
 
 140 
 
 120 
 
 100 
 
 80 
 
 Corresponding velocities 
 of cooling. 
 
 10.69 
 
 8.81 
 
 7.40 
 
 6.10 
 
 4.89 
 
 3.88 
 
 3.02 
 
 2.30 
 
 1.74 
 
 
 
 
 The first column contains the excesses of 
 temperature above the walls of the balloon ; 
 that is to say, the temperatures themselves, 
 since the balloon was at 0°. The second co- 
 lumn contains the corresponding velocities of 
 cooling, calculated and corrected. These ve- 
 locities are the numbers of degrees that the 
 thermometer would sink in a minute. The 
 first series shews clearly the inaccuracy of the 
 geometrical law of llichmann; for according 
 to that law, the velocity of cooling at 200° 
 should be double of that at 100°; whereas 
 we find it as 7.4 to 2.3, or more than triple ; 
 and in like manner, when we compare the 
 loss of heat at 240° and at 80°, we find the 
 first about 6 times greater than the last ; 
 while, according to the law of llichmann, it 
 ought to be merely triple. From the above 
 
 and some analogous experiments, the follow- 
 ing law has been deduced : When a body 
 cpols in vacuo, surrounded by a medium whose 
 
 13 
 
 temperature is constant , the velocity of cooling 
 for excess oj temperature in arithmetical pro- 
 gression, increases as the terms of a geometri- 
 cal progression, diminished by a certain quan- 
 tity. Or, expressed in algebraic language, 
 the following equation contains the law of 
 
 cooling in vacuo : V = m.a ( a — 1 ). 
 
 6 is the temperature of the substance sur- 
 rounding the vacuum ; and t that of the heated 
 body above the former. The ratio a of this 
 progression is easily found for the thermome- 
 ter, whose cooling is recorded above; for when 
 6 augments by 20°, t remaining the same, the 
 velocity of cooling is then multiplied by 1.1 65, 
 which number is the mean of all the ratios 
 experimentally determined. We have then 
 2 0 
 
 a — \/ 1.165 = 1.0077. 
 
 It only remains, in order to verify the ac- 
 curacy of this law, to compare it with the 
 different series contained in the table insert- 
 ed above. In that case, in which the sur- 
 rounding medium was 0°, it is necessary to 
 
 make m = 2.037, for m = , and n is 
 
 log. a 
 
 an intermediate 
 
 number ; we 
 
 have then V 
 
 = 2.037 {a — - 
 
 1). 
 
 
 Excesses of temp. 
 
 Values of 
 
 Values of V 
 
 or values of t. 
 
 V observed. 
 
 calculated. 
 
 240° 
 
 10.69 
 
 10.68 
 
 220 
 
 8.81 
 
 8.89 
 
 200 
 
 7.40 
 
 7. 34 
 
 180 
 
 6.10 
 
 6.03 
 
 160 
 
 4.89 
 
 4.87 
 
 140 
 
 3.88 
 
 3.89 
 
 120 
 
 .3.02 
 
 3.05 
 
 100 
 
 2.30 
 
 2.33 
 
 80 
 
 1.74 
 
 1.72 
 
 The laws of cooling in vacuo being known, 
 nothing is more simple than to separate from 
 the total cooling of a body surrounded with 
 air, or with any other gas, the portion of the 
 effect due to the contact of the fluid. For 
 this, it is obviously sufficient to subtract from 
 the real velocities of cooling, those velocities 
 which would take place if the body cecteris 
 jmribus were placed in vacuo. This subtrac- 
 tion may be easily accomplished now that 
 we have a formula, which represents this 
 velocity with great precision, and for all pos- 
 sible cases. 
 
 From numerous experimental compari- 
 sons the following law was deduced : The 
 
 velocity of cooling if a body, owing to the sole 
 contact of a gas, depends for the same excess 
 of temperature, on the density and tempera- 
 ture of the fluid ; but this dependence is such, 
 that the velocity of cooling remains the same , 
 if the density and the temperature of the gas 
 change in, such a way that the elasticity re- 
 mains constant. 
 
 It we call P the cooling power of air 
 under the pressure p, this power will become 
 
CAL 
 
 CAL 
 
 P (1.366) under a pressure 2p ; P (1.36G) 2 
 under a pressure 4 p • and under a pressure 
 
 p 2 , it will be P (1.366)”. Hence J- = 
 
 We shall find in the same 
 
 way for hydrogen 
 
 0.38 
 
 For carbonic acid, the exponent will be 
 0.5 1 7, and for olefiant gas 0.501, while for 
 air as we see it is 0.45. These last three 
 numbers differing little from 0.5 or i, we 
 may say that in the aeriform bodies to which 
 they belong, the cooling power is nearly 
 as the square root of the elasticity. “ If 
 we compare the law which we have thus 
 announced,” say MM. Dulong and Petit, 
 “ with the approximations of Leslie and Dal- 
 ton, we shall be able to judge of the errors 
 into which they have been led by the inaccu- 
 rate suppositions which serve as the basis of 
 all their calculations, and by the little pre- 
 cision attainable by the methods which they 
 have followed.” But for these discussions, 
 w r e must refer to the memoir itself. 
 
 The influence of the nature of the surface 
 of bodies in the distribution of heat, was first 
 accurately examined by Mr Leslie. This 
 branch of the subject is usually called the 
 radiation of caloric. To measure the amount 
 of this influence with precision, he contrived 
 a peculiar instrument, called a differential 
 thermometer. It consists of a glass tube, 
 bent into the form of the letter U, terminated 
 at each end with a bulb. The bore is about 
 the size of that of large thermometers, and 
 the bulbs have a diameter of 3 - of an inch 
 and upwards. Before hermetically closing 
 the instrument, a small portion of sulphuric 
 acid, tinged with carmine is introduced. The 
 adjustment of this liquid so as to make it 
 stand at the top of one of the stems, imme- 
 diately below the bulb, requires dexterity in 
 the operator. To this stem a scale divided in- 
 to 100 parts is attached, and the instrument 
 is then fixed upright by a little cement on a 
 wooden sole. If the finger, or any body 
 warmer than the ambient air, be applied to 
 one of these bulbs, the air within will be 
 heated, and will of course expand, and issu- 
 ing in part from the bulb, depress before it 
 the tinged liquor. The amount of this de- 
 pression observed upon the scale, will denote 
 the difference of temperature of the two balls. 
 But if the instrument be merely carried 
 without touching either ball, from a warmer 
 to a cooler, or from a cooler to a warmer 
 air, or medium of any kind, it will not be 
 affected ; because the equality of contraction or 
 expansion in the enclosed air of both bulbs, 
 will maintain the equilibrium of the liquid in 
 the stem. Being thus independent of the 
 fluctuations of the surrounding medium, it 
 Is well adapted to measure the calorific 
 
 47 
 
 emanations of different surfaces, successively 
 converged by a concave reflector, upon one 
 of its bulbs. Dr Howard has described, in 
 the 16th number of the Journal of Science, 
 a differential thermometer of his contrivance, 
 which he conceives to possess some advan- 
 tages. Its form is an imitation of Mr Les- 
 lie’s ; but it contains merely tinged alcohol, 
 or ether, the air being expelled by ebullition 
 previous to the hermetical closure of the 
 instrument. The vapour of ether, or of spirit 
 in vacuo , affords, he finds, a test of superior 
 delicacy to air. He makes the two legs of 
 different lengths ; since it is in some cases 
 very convenient to have the one bulb stand- 
 ing quite aloof from the other. In Mr Les- 
 lie’s, when they are on the same level, their 
 distance asunder varies from -- of an inch to 
 1 or upwards, according to the size of the in- 
 strument. The general length of the legs of 
 the syphon is about 3 or 6 inches. 
 
 His reflecting mirrors, of about 14 inches 
 diameter, consisted of planished tin- plate, 
 hammered into a parabolical form by the 
 guidance of a curvilinear gauge. A hollowtin 
 vessel, 6 inches cube, was the usual source of 
 calorific emanation in his experiments. lie 
 coated one of its sides with lampblack, another 
 with paper, a third with glass, and a fourth 
 was left bare. Having then filled it with hot 
 water, and set it in the line of the axis, and 4 
 or 6 feet in front of one of the mirrors, in 
 whose focus the bulb of a differential ther- 
 mometer stood, he noted the depression of 
 the coloured liquid produced on presenting 
 the different sides of the cube towards the 
 mirror in succession. The following table 
 gives a general view r of the results, with these, 
 and other coatings ; — 
 
 Lampblack, 
 
 - 
 
 100 
 
 Water by estimate, 
 
 - 
 
 100 4- 
 
 Writing paper, 
 
 - 
 
 00 
 
 Rosin, 
 
 - 
 
 96 
 
 Sealing w r ax, 
 
 - 
 
 95 
 
 Crown glass, 
 
 - 
 
 90 
 
 China ink, 
 
 - 
 
 88 
 
 Ice, - 
 
 - 
 
 85 
 
 Red lead, 
 
 - 
 
 80 
 
 Plumbago, - 
 
 - 
 
 Pm «■ 
 
 to 
 
 Isinglass, 
 
 - 
 
 75 
 
 Tarnished lead, 
 
 - 
 
 45 
 
 Mercury, 
 
 - 
 
 20 -f 
 
 Clean lead, - 
 
 - 
 
 19 
 
 Iron polished, 
 
 - 
 
 15 
 
 Tin plate, 
 
 - 
 
 12 
 
 Gold, Silver, Copper, 
 
 - 
 
 12 
 
 Similar results w’ere obtained by Leslie 
 and Rumford in a simpler form. Vessels 
 of similar shapes and capacities, but of dif- 
 ferent materials, were filled with hot liquids, 
 and their rates of refrigeration noted. A 
 blackened tin globe cooled a certain number 
 of degrees in 81 minutes; while a bright 
 one took nearly double the time, or 156 
 minutes; a naked brass cylinder in 55 mi- 
 
CAL 
 
 CAL 
 
 nutes cooled ten degrees, while its fellow 
 cased in linen, was 36^ minutes in cooling 
 the same quantity. If rapid motions be ex- 
 cited in the air, the difference of cooling 
 between bright and dark metallic surfaces 
 becomes less manifest. Mr Leslie estimates 
 the diminution of effect from a radiating 
 surface to be directly as its distance, so that 
 double the distance gives one-half, and treble 
 one- third of the primitive heating impression 
 on thermometers and other bodies. Some of 
 his experiments do not seem in accordance 
 with this simple law. One would have ex- 
 pected certainly, that, like light, electricity, 
 and other qualities emanating from a centre, 
 its diminution of intensity would have been 
 as the square of the distance ; and particu- 
 larly as Mr Leslie found the usual analogy 
 of the sine of inclination to hold, in pre- 
 senting the faces of the cube to the plane of 
 the mirror under different angles of obli- 
 quity. 
 
 Some practical lessons flow from the pre- 
 ceding results. Since bright metals project 
 heat most feebly, vessels which are intended 
 to retain their heat, as tea and coffee-pots, 
 should be made of bright and polished me- 
 tals, Steam-pipes intended to convey heat 
 to a distant apartment, should be likewise 
 bright in their course, but darkened when 
 they reach their destination. 
 
 By coating the bulb of his thermometer 
 with different substances, Mr Leslie ingeni- 
 ously discovered the power of different sur- 
 faces to absorb heat ; and he found this to fol- 
 low the same order as the radiating or project- 
 ing quality. The same film of silver leaf which 
 obstructs the egress of heat from a body to 
 those suiTounding it, prevents it from re- 
 ceiving their calorific emanations in return. 
 On this principle we can understand how a 
 metallic mirror, placed before a fire, should 
 scorch substances in its focus, while itself re- 
 mains cold ; and, on the other hand, how a 
 mirror of darkened or even of silvered glass, 
 should become intolerably hot to the touch, 
 while it throws little heat before it. From 
 this absorbent faculty it comes, that a thin 
 pane of glass intercepts almost the whole 
 heat of a blazing fire, while the light is 
 scarcely diminished across it. By degrees 
 indeed, itself becoming heated, constitutes a 
 new focus of emanation, but still the energy 
 of the fire is greatly interrupted. Hence 
 also we see why the thinnest sheet of bright 
 tin foil is a perfect fire-screen ; so impervious 
 indeed to heat, that with a masque coated 
 with it, our face may encounter without in- 
 convenience, the blaze of a glass-house fur- 
 nace. 
 
 Since absorption of heat goes hand in 
 hand with radiation in the above table, we 
 perceive that the inverse of absorption, that 
 is reflection, must be possessed in inverse 
 powers by the different substances coinpos- 
 
 II 
 
 in g the list. Thus bright metals reflect 
 most heat, and so on upwards in succession. 
 
 Mr Leslie is anxious to prove that elastic 
 fluids, by their pulsatory undulations, are the 
 media of the projection or radiation of heat; 
 and that therefore liquids, as well as a per- 
 fect vacuum, should obstruct the operation 
 of this faculty. The laws of the cooling of 
 bodies in vacuo, experimentally established by 
 MM. Dulong and Petit, are fatal to Mr 
 Leslie’s hypothesis, which indeed was not 
 tenable against the numerous objections which 
 had previously assailed it. The following 
 beautiful experiment of Sir IT. Davy seems 
 alone to settle the question. He bad an 
 apparatus made, by which platina wire could 
 be heated in any elastic medium or in vacuo ; 
 and by which the effects of radiation could 
 be distinctly exhibited by two mirrors, the 
 heat being excited by a voltaic battery. In 
 several experiments in which the same 
 powers were employed to produce the ignition* 
 it was found that the temperature of a ther- 
 mometer rose nearly three times as much in 
 the focus of radiation, when the air in the 
 receiver was exhausted to yA jj, as when it 
 was in its natural state of condensation. 
 The cooling pow r er, by contact of the rare- 
 fied air, was much less than that of the air 
 in its common state, for the glow of the pla- 
 tina w r as more intense in the first case than 
 in the last ; and this circumstance perhaps 
 renders the experiment not altogether deci- 
 sive, but the results seem favourable to the 
 idea, that the terrestrial radiation of heat is 
 not dependent upon any motions or affections 
 of the atmosphere. The plane of the two 
 mirrors was placed parallel to the horizon, 
 the ignited body being in the focus of the 
 upper, and the thermometer in that of the 
 under mirror. It is evident that a diminish- 
 ed density of the clastic medium, amounting 
 to should, on Mr Leslie’s views, have 
 occasioned a greatly diminished temperature 
 in the inferior focus, and not a threefold in- 
 crease, as happened ; making every allow r - 
 ance for the diminished intensity of glow 
 resulting from the cooling power of atmos- 
 pheric air. The experiments with screens 
 of glass, paper, &c. which Mr Leslie addu- 
 ced in support of his; undulatory hypothesis, 
 have been since confronted with the experi- 
 ments on screens of Dr Delaroehe, who, by 
 varying them, obtained results incompatible 
 with Mr Leslie’s view's, and favourable to 
 those on the intimate connexion between 
 light and heat, with which our account of 
 heat was prefaced. He shews that invisible 
 radiant heat, in some circumstances, passes 
 directly through glass, in a quantity so much 
 greater relative to the whole radiation, as the 
 temperature of the source of heat is more 
 elevated. The following table shews the 
 ratio between the rays passing through clear 
 
CAL 
 
 CAL 
 
 glass, and the rays acting on the thermometer, 
 vshen no screen was interposed, at successive 
 temperatures. 
 
 Temperature ltays transmit- ^ . , 
 
 ot the hot body ted through the lotal 
 
 in the focus. glass screen, Rays ‘ 
 
 357° 10° 263° 
 
 655 10 139 
 
 800 10 75 
 
 1760 10 34 
 
 Argand’s lamp with- 
 out its chimney, 10 29 
 
 Do. with glass 
 
 chimney, 10 18 
 
 He next shews that the calorific rays which 
 have already passed through a screen of glass, 
 experience, in passing through a second 
 glass screen of a similar nature, a much 
 smaller diminution of their intensity than 
 they did in passing through the first screen ; 
 and that the rays emitted by a hot body dif- 
 fer from each other in their faculty to pass 
 through glass ; that a thick glass, though as 
 much as, or more permeable to light than, a 
 thin glass of worse quality, allows a much 
 smaller quantity of radiant heat to pass, the 
 difference being so much the less, the higher 
 the temperature of the radiating source. This 
 curious fact, that radiating heat becomes 
 more and more capable of penetrating glass, 
 as the temperature increases, till at a certain 
 temperature the rays become luminous, leads 
 to the notion that heat is nothing else than a 
 modification of light, or that the two sub- 
 stances are capable of passing into each other. 
 Dr Delaroche’s last proposition is, that the 
 quantity of heat which a hot body yields in 
 a given time by radiation to a cold body si- 
 tuated at a distance, increases cceteris paribus, 
 in a greater ratio than the excess of tempe- 
 rature of the first body above the second. 
 This proposition, which Dr Thomson de- 
 clared in his Annals, vol. ii. p. 102. to be 
 “ somewhat puzzling,” is in philosophical 
 accordance with the laws of Dulong and 
 Petit. 
 
 For some additional facts on radiation, 
 see Light, to which subject indeed, the whole 
 discussion probably belongs. 
 
 Even ice, which appears so cold to the 
 organs of touch, would become a focus of 
 heat if transported into a chamber w here the 
 temperature of the air was at 0° F. ; and a 
 mass of melting ice placed before the mir- 
 ror, would affect the bulb of the thermome- 
 ter, just as the cube of heated water did, A 
 mixture of snow and salt at 0°, would in 
 like manner become a w r arm body when car- 
 ried into an atmosphere at — 40°. In all this, 
 as well as in our sensations, we see nothing 
 absolute, nothing but mere differences. We 
 are thus led to consider all bodies as project- 
 ing heat at every temperature, but with un- 
 equal intensities, according to their nature, 
 their surfaces, and their temperature. The 
 
 constancy or steadiness of the temperature 
 of a body, wdll consist in the equality of the 
 quantities of radiating caloric which it emits 
 and receives in an equal time, and the equa- 
 lity of temperature between several bodies 
 which influence one another by their mutual 
 radiation, will consist in the perfect compen- 
 sation of the momentary interchanges effect- 
 ed among one and all. Such is the ingenious 
 principle of a moveable equilibrium, pro- 
 posed by Professor Prevost, a principle whose 
 application, directed with discretion, and com- 
 bined with the properties peculiar to diffe- 
 rent surfaces, explains all the phenomena 
 w'hich w r e observe in the distribution of ra- 
 diating caloric. Thus, when we put a ball 
 of snow in the focus of one concave mirror, 
 and a thermometer in that of an opposite 
 mirror placed at some distance, we perceive 
 the temperature instantly to fall, as if there 
 w r ere a real radiation of frigorific particles, 
 according to the ancient notion. The true 
 explanation is derived from the abstraction 
 of that return of heat which the thermoscope 
 mirror had previously derived from the one 
 now influenced by the snow, and now par- 
 ticipating in its inferior radiating tension. 
 Thus, also a black body placed in the foens 
 of one mirror, would diminish the light in 
 the focus of the other; and, as Sir II. Davy 
 happily remarks, the eye is, to the rays pro- 
 ducing light, « measure, similar to that which 
 the thermometer is to rays producing heat. 
 
 This interchange of heat is finely exem- 
 plified in the relation which subsists betw’een 
 any portion of the sky and the temperature 
 of the subjacent surface of the earth. In 
 the year 1788 Mr Six of Canterbury men- 
 tioned, in a paper transmitted to the Royal 
 Society, that on clear and dewy nights he 
 always found the mercury lower in a ther- 
 mometer laid upon the ground, in a meadow 
 in his neighbourhood, than it was in a simi- 
 lar thermometer suspended in the air 6 feet 
 above the former; and that upon one night 
 the difference amounted to 5 C of Fahrenheit’s 
 scale. And Dr Wells, in autumn 1811, on 
 laying a thermometer upon grass wet with 
 dew, and suspending a second in the air 2 
 feet above the surface, found in an hour af- 
 terwards, that the former stood 8° lower 
 than the latter. He at first regarded this 
 coldness of the surface to be the effect of the 
 evaporation of the moisture, but subsequent 
 observations and experiments convinced him, 
 that the cold was not the effect, but the cause 
 of deposition of dew\ Under a cloudless 
 sky, the earth projects its heat without re- 
 turn, into empty space ; but a canopy of 
 cloud is a concave mirror, which restores the 
 equilibrium by counter- radiation. See Dew. 
 
 On this principle Professor Leslie has 
 constructed a pretty instrument, which he 
 calls .Ethrioscope, whose function it is to de- 
 note the clearness and coolness of the sky. 
 
CAL 
 
 CAL 
 
 It consists of a polished metallic cup, of an 
 oblong spheroidal shape, very like a silver 
 porter-cup, standing upright, with the bulb 
 of a differential thermometer placed in its 
 axis, and the stem lying parallel to the stalk 
 of the cup. The other ball is gilt, and tinn- 
 ed outwards and upwards, so as to rest 
 against the side of the vessel. I he best 
 form of the cup is an ellipsoid, whose eccen- 
 tricity is equal to half the transverse axis, 
 and the focus consequently placed at the 
 third part of the whole height of the cavity ; 
 while the diameter of the thermoscope ball 
 should be nearly the third part of the orifice 
 of the cup. A lid of the same thin metal 
 unpolished, is titted to the mouth of the cup, 
 and removed only when an observation is to 
 be made. The scale attached to the stem of 
 the thermoscope, may extend to 60 or 70 
 millesimal degrees above the zero, and about 
 15 degrees below it. 
 
 This instrument exposed to the open air 
 in clear weather, will at all times, both dur- 
 ing the day and the night, “ indicate an im- 
 pression of cold shot downward from the 
 higher regions,” in the figurative language 
 of the inventor. Yet the effect varies ex- 
 ceedingly. It is greatest while the sky has 
 the pure azure hue; it diminishes fast as the 
 atmosphere becomes loaded with spreading 
 clouds; and it is almost extinguished when 
 low fogs settle on the surface. The liquid 
 in the stem falls and rises with every passing 
 cloud. Dr Howard’s modification of the 
 thermoscope would answer well here. 
 
 The diffusion of heat among the particles 
 of fluids themselves , depends upon their spe- 
 cific gravity and specific heat conjunctly, 
 and therefore must vary for each particular 
 substance. The mobility of the particles in 
 a fluid, and their reciprocal independence on 
 one another, permit them to change their 
 places whenever they are expanded or con- 
 tracted by alternations of temperature ; and 
 hence the immediate and inevitable effect of 
 communicating heat to the under stratum of 
 a fluid mass, or of abstracting it from the 
 upper stratum, is to determine a series of in- 
 testine movements. The colder particles, by 
 their superior density, descend in a perpetual 
 current, and force upwards those rarefied by 
 the heat. When however the upper stratum 
 primarily acquires an elevated temperature, 
 it seems to have little power of imparting 
 heat to the subjacent strata of fluid particles. 
 Water may be kept long in ebullition at 
 the surface of a vessel, while the bottom re- 
 mains ice cold, provided wc take measures 
 to prevent the heat passing downwards 
 through the sides of the vessel itself. Count 
 Rumford became so strongly persuaded of 
 the impossibility of communicating heat 
 downwards through fluid particles, that he 
 r regarded them as utterly destitute of the 
 faculty of transmitting that power from one 
 to another, and capable of acquiring heat, 
 
 only in individual rotation and directly, from 
 a foreign source. The proposition thus ab- 
 solutely announced is absurd, for we know 
 that by intermixture and many other modes, 
 fluid particles impart heat to each other ; 
 and experiments have been instituted, which 
 prove the actual descent of heat through 
 fluids by communication from one stratum 
 to another. But unquestionably this com- 
 munication is amazingly difficult and slow. 
 We are hence led to conceive, that it is an 
 actual contact of particles, which in the solid 
 condition facilitates the transmission of heat 
 
 so speedily from point to point through their 
 mass. This contact of certain poles in the 
 molecules, is perfectly consistent with void 
 spaces, in which these molecules may slide 
 over each other in every direction ; by which 
 movements or condensations, heat may be 
 excited. The fluid condition reverts or 
 averts the touching and cohering poles, 
 whence mobility results. This statement 
 may be viewed either as a representation of 
 facts, or an hypothesis to aid conception. 
 
 Since the diffusion of heat through a fluid 
 mass is accomplished almost solely by the 
 intestine currents, whatever obstructs these 
 must obstruct the change of temperature. 
 Hence fluids intermingled with porous mat- 
 ter, such as silk, wool, cotton, downs, fur, 
 hair, starch, mucilage, &c. are more slowly 
 cooled than in their pure and limpid state. 
 Hence apple-tarts and pottages retain their 
 heat very long, in comparison of the same 
 bulk of water heated to the same degree, 
 and exposed in similar covered vessels to the 
 cool air. Of the conducting power of gase- 
 ous bodies, w*e have alreadv taken a view. 
 I know of no experiments which have satis- 
 factorily determined in numbers, the relative 
 conducting power of liquids. Mercury for 
 a liquid, possesses a high conducting faculty, 
 due to its density and metallic nature, and 
 small specific heat. 
 
 The transmission of heat through solids 
 
 was made the subject of some pleasing po- 
 pular experiments by Dr Ingenhausz. He 
 took a number of metallic rods of the same 
 length and thickness, and having coated one 
 of the ends of them for a few inches with 
 bees wax, he plunged their other ends into a 
 heated liquid. The heat travelled onwards 
 among the matter of each rod, and soon be- 
 came manifest by the softening of the wax. 
 The following is the order in which the w r ax 
 melted ; and according to that experiment, 
 therefore, the order of conducting power re- 
 lative to heat. 
 
 1. Silver. 
 
 2. Gold. 
 
 3 . 
 
 4 . 
 
 Copper, near jy e q Ua j # 
 
 "" l 
 
 Platinum 
 
 Iron, 
 
 Steel, 
 
 Lead, 
 
 $ 
 
 much inferior to 
 the others. 
 
CAL 
 
 CAL 
 
 In my repetition of the experiment, I found 
 silver by much the best conductor, next cop- 
 per, then brass, iron, tin, much the same, 
 then cast iron, next zinc, and last of all, lead. 
 Dense stones follow metals in conducting 
 power, then bricks, pottery, and at a long 
 interval, glass. A rod of this singular body 
 may be held in the fingers for a long time, 
 at a distance of an inch from where it is 
 ignited and fused by the blow-pipe. It is 
 owing to the inferior conducting power of 
 stone, pottery, glass, and cast iron, that 
 the sudden application of heat so readily 
 cracks them. The part acted on by the ca- 
 loric expands, while the adjacent parts re- 
 taining their pristine form and volume, do 
 not accommodate themselves to the change : 
 whence a fissure must necessarily ensue. 
 Woods and bones are better conductors than 
 glass ; but the progress of heat in them at 
 elevated temperatures, may be aided by the 
 vaporization of their juices. Charcoal and 
 saw-dust rank very low in conducting power. 
 Hence the former is admirably fitted for ar- 
 resting the dispersion of heat in metal fur- 
 naces. If the sides of these be formed of 
 double plates, with an interval between them 
 of an inch filled with pounded charcoal, an 
 intense heat may exist within, while the out- 
 side is scarcely affected. Morveau has rated 
 the conducting power of charcoal to that of 
 fine sand, as 2 to 3, a difference much too 
 small. Spongy organic substances, silk, 
 wool, cotton, Sec. are still worse conductors 
 than any of the above substances ; and the 
 finer the fibres, the less conducting power 
 they possess. The theory of clothing de- 
 pends on this principle. The heat generated 
 by the animal powers, is accumulated round 
 the body by the imperfect conductors of 
 which clothing is composed. 
 
 To discover the exact law of the distribu- 
 tion of heat in solids, let us take a prismatic 
 bar of iron, three feet long, and w ith a drill 
 form three cavities in one of its sides, at 10, 
 20, and SO inches from its end, each cavity 
 capable of receiving a little mercury, and the 
 small bulb of a delicate thermometer. Cut 
 a hole fitting exactly the prismatic bar, in the 
 middle of a sheet of tin-plate, which is then 
 to be fixed to the bar, to screen it and the 
 thermometer, from the focus of heat. Im- 
 merse the extremity of the bar obliquely into 
 oil or mercury heated to any known degree, 
 and place the thermometers in their cavities 
 surrounded with a little mercury. Or the 
 bar may be kept horizontal, if an inch or two 
 at its end be ineurvated, at right angles to its 
 length. Call the thermometers A, B, C. 
 Were there no dissipation of the heat, each 
 thermometer would continue to mount till it 
 attained the temperature of the source of heat. 
 But in actual experiments, projection and 
 aerial currents modify that result, making the 
 thermometers rise more slowly, and prevent- 
 
 ing them from ever reaching the temperature 
 of the end of the bar. I heir state becomes 
 indeed stationary whenever the excess of tem- 
 perature, each instant communicated by the 
 preceding section of the bar, merely compen- 
 sates what they lose by the contact of the 
 succeeding section of the bar, and the other 
 outlets of heat. The three thermometers 
 now indicate three steady temperatures, but 
 in diminishing progression. In forming an 
 equation from the experimental results, M. 
 Laplace has shewn, that the difficulties of the 
 calculation can be removed only by admitt- 
 ing, that a determinate point is influenced not 
 only by those points which touch it, but by 
 others at a small distance before and be- 
 hind it. Then the laws of homogeneity, to 
 which differentials are subject, are re-esta- 
 blished, and all the rules of the differential 
 calculus are observed. Now, in order that 
 the calorific influence may thus extend to a 
 distance in the interior of the bar, there must 
 operate through the very substance of the 
 solid elements a true radiation, analogous to 
 that observed in air, but whose sensible in- 
 fluence is bounded to distances incomparably 
 smaller. This result is in no respect impro- 
 bable. In fact, Newton has taught us, that 
 all bodies, even the most opaque, become 
 transparent when rendered sufficiently thin ; 
 and the most exact researches on radiating 
 caloric, prove that it does not emanate solely 
 from the external surface of bodies, but also 
 from material particles situated within this 
 surface, becoming no doubt insensible at a 
 very slight depth, which probably varies in 
 the same body, with its temperature. 
 
 M. Biot, M. Fourier, and M. Poisson, threo 
 of the most eminent mathematicians and phi- 
 losophers of the age, have distinguished them- 
 selves in this abstruse investigation. The 
 following is the formula of INI. Biot, when 
 one end of the bar is maintained at a con- 
 stant temperature, and the other is so remote 
 as to make the influence of the source insen- 
 sible. Let y represent, in degrees of the 
 thermometer, the temperature of the air by 
 which the bar is surrounded ; let the tempe- 
 rature of the focus be y -}- Y ; then the inte- 
 
 gral becomes, log. y = log. Y — — V — . 
 
 INI a* 
 
 x is the distance from the hot end of the bar; 
 a and b are two coefficients, supposed con- 
 stant for the whole length of the bar, which 
 serve to accommodate the formula to every 
 possible case, and which must be assigned in 
 each case, agreeably to two observations. AI 
 is the modulus of the ordinary logarithmic 
 tables, or the number 2.302585. M. Biot 
 presents several tables of observations, in 
 which sometimes 8, and sometimes 14 ther- 
 mometers w r ere applied all at once to suc- 
 cessive points of the bar ; and then he com- 
 putes by the above formula, what ought to he 
 the temperature of these successive points, 
 
CAL 
 
 CAI 
 
 liaving given the temperature of the source ; 
 and vice versa , what should be the tempera- 
 ture of the source, from the indications of the 
 thermometers. A perfect accordance is shewn 
 to exist between fact and theory. W hence 
 we may regard the view opened up by the 
 latter, as a true representation of the condi- 
 tion of the bar. With regard to the applica- 
 tion of this theorem, to discover for example, 
 the temperature of a furnace, by thrusting 
 the end of a thermoscopic iron bar into it, 
 we must regret its insufficiency. M. Biot 
 himself, after shewing its exact coincidence at 
 all temperatures, up to that of melting lead, 
 declares that it ought not to apply at high 
 heats. But I see no difficulty in making a 
 very useful instrument of this kind, by eiperi- 
 meiit, to give very valuable pyrometrical in- 
 dications. The end of the bar which is to bo 
 exposed to the heat, being coated with fire- 
 clay, or sheathed with platinum, should be 
 inserted a few inches into the flame, and 
 drops of oil being put into three successive 
 cavities of the bar, we should measure the 
 temperatures of the oil, when they have be- 
 come stationary, and note the time elapsed, 
 to produce this effect. A pyroscope of this 
 kind could not fail to give useful infor- 
 mation to the practical chemist, as well as 
 to the manufacturers of glass, pottery, steel, 
 Sec. 
 
 
 2. Of specific heat . — If we take equal weights, 
 or equal bulks, of a series of substances ; for 
 example, a pound or a pint of water, oil, 
 alcohol, mercury, and having heated each 
 separately, in a thin vessel, to the same tem- 
 perature, say to 80° or 100° Fahr. from an 
 atmospherical temperature of 60°, then in 
 the subsequent cooling of these four bodies to 
 their former state, they will communicate to 
 surrounding media very different quantities 
 of heat. And conversely, the quantity of 
 heat requisite to raise the temperature of 
 equal masses of different bodies, an equal 
 number of thermometric degrees, is different, 
 but specific for each body. There is another 
 point of view in which specific heats of bodies 
 may be considered relative to their change of 
 form, from gaseous to liquid, and from liquid 
 to solid. Thus the steam of water, at 212°, 
 in becoming a liquid, does not change its 
 thermometric temperature 212°, yet it com- 
 
 
 municates, by this change, a vast quantity of 
 heat to surrounding bodies ; and, in like 
 manner, liquid water at 32°, in becoming 
 the solid called ice, does not change its tem- 
 perature as measured by a thermometer, yet 
 it imparts much heat to surrounding matter. 
 We therefore divide the study of specific 
 heats into two branches: 1. The specific 
 
 heats of bodies while they retain the same 
 state ; and 2. The specific heats, connected 
 with, or developed by, change of state. The 
 first has been commonly called the capacities 
 
 of bodies for caloric ; the second, the latent 
 heat of bodies. The latter we shall consider 
 after change of state. 
 
 1. Of the specific heats of bodies, while 
 they experience no change of state. 
 
 Three distinct experimental modes have 
 been employed to determine the specific 
 heats of bodies ; in the whole of which 
 modes, that of water has been adopted for 
 the standard of comparison or unity. 1. In 
 the fr st mode, a given weight or bulk ot the 
 body to be examined, being heated to a cer- 
 tain point, is suddenly mixed with a given 
 weight or bulk of another body, at a diffe- 
 rent temperature ; and the resulting tempe- 
 rature of the mixture shews the relation be- 
 tween their specific heats. Hence, if the 
 second body be water, or any other substance 
 whose relation to water is ascertained, the re- 
 lative heat of the first to that of water will be 
 known. It is an essential precaution in using 
 this mode, to avoid all such chemical action 
 as happens in mixing water with alcohol or 
 acids. Let us take oil for an example. If 
 a pound of it, at 90° Fahr. be mixed with a 
 pound of water at 60°, the resulting tempe- 
 rature will not be the mean 75°, but only 
 70°. And conversely, if we mix a pound ot 
 water heated to 90°, with a pound of oil at 
 60°, the temperature of the mixture will be 
 80°. We see here, that the water in the 
 first case acquired 10°, while the oil lost 20° ; 
 and in the second case, that the water lost 
 10° while the oil gained 20°. Hence w'e 
 say, that the specific heat of water is double 
 to that of oil, or that the same quantity or 
 intensity of heat which will change the tem- 
 perature of oil 20°, will change that of water 
 only 10° ; and therefore, if the specific heat, 
 or capacity for heat, of water be called 1.000, 
 that of oil will be 0.500. When the expe- 
 riment has been, from particular circum- 
 stances, made with unequal weights, the ob- 
 vious arithmetical reduction, for the diffe- 
 rence, must be made. This is the original 
 method of Black, Irvine, and Crawford. 
 
 The second mode is in some respects a mo- 
 dification of the first. The heated mass of 
 the matter to be investigated, is so surround- 
 ed by a large quantity of the standard sub- 
 stance at an inferior temperature, that the 
 whole heat evolved by the first, in cooling, is 
 received by the second. We may refer to 
 this mode, Is/, Wilcke’s practice of suspend- 
 ing a lump of heated metal in the centre of 
 a mass of cold water contained in a tin ves- 
 sel : 2d, The plan of Lavoisier and Laplace, 
 in w hich a heated mass of matter was placed 
 by means of their elegant Calorimeter, in 
 the centre of a shell of ice ; and the specific 
 heat was inferred from the quantity of ice 
 that was liquefied : And 3d, The method of 
 Berard and Helarochc, in which gaseous 
 matter, heated to a knowrn temperature, was 
 
CAL 
 
 CAL 
 
 mado to traverse, slowly and uniformly, the 
 convolutions of a spiral pipe, fixed in a 
 cylinder ol cool water, till this water rose to 
 a stationary temperature ; when, “reckoning 
 from tliis point, the excess of the tempera- 
 ture of the cylinder, above that of the ambi- 
 ent air, becomes proportional to the quan- 
 tity ot heat given out by the current of gas 
 that passed through the cylinder.” Each gas 
 was definitely heated, by being passed through 
 a straight narrow tube, placed in the axis of 
 a large tube, filled with the steam of boiling 
 water. The specific heats were then com- 
 pared to water by two methods. The first 
 consists in subjecting the cylinder, which 
 they call the calorimeter , to the action of a 
 current of water perfectly regular, and so 
 slow, that it will hardly produce a greater 
 effect than the current of the different gases. 
 The second method consists in determining, 
 by calculation, the real quantity of heat which 
 the calorimeter, come to its stationary tem- 
 perature, can lose in a given time ; for since, 
 after it reaches this point, it does not become 
 hotter, though the source of heat continues 
 to be applied to it, it is evident that it loses 
 as much heat as it receives. MM. Berard 
 and Delaroche employed these two methods 
 in succession. From the singular ingenuity 
 of their apparatus, and precision of their ob- 
 servations, we may regard their determina- 
 tions as deserving a degree of confidence to 
 which the previous results, on the specific 
 heat of the gases, are not at all entitled. 
 They have completely overturned the hypo- 
 thetical structures of Black, Lavoisier, and 
 Crawford, on the heat developed in combus- 
 tion and respiration, while they give great 
 countenance to the profound views of Sir H. 
 Davy. See Combustion. 
 
 The third method of determining the spe- 
 cific heats of bodies, is by raising a given 
 mass to a certain temperature, suspending it 
 in a uniform cool medium, till it descends 
 through a certain number of thermometric 
 degrees, and carefully noting by a watch the 
 time elapsed. It is evident, that il the 
 bodies be invested with the same coating, 
 for instance, glass or burnished metals; if 
 they be suspended in the same medium, with 
 the same excess of temperature, and if their 
 interior constitution relative to the conduc- 
 tion of heat be also the same, then tneir spe- 
 cific heats will be directly as the times of 
 cooling. I have tried this method, and find 
 that it readily gives, in common cases, good 
 approximations. Some of my results were 
 published in the Annals of Phil, lor October 
 1817, on water, sulphuric acid, spermaceti 
 oil, and oil of turpentine. “ A thin glass 
 globe, capable of holding 1800 grains ol 
 water, was successively filled with this liquid, 
 and with the others ; and being in each case 
 heated to the same degree, w'as suspended, 
 with a delicate thermometer immersed in 
 
 it, in a large room of uniform temperature. 
 The comparative times of cooling, through 
 an equal range of the thermometric scale, 
 were carefully noted by a watch in each case.” 
 The difference of mobility in the liquid par- 
 ticles may be regarded as very trilling, at 
 temperatures from 100° to 200°. At infe- 
 rior temperatures, under 80° for example, oil 
 of vitriol, as well as spermaceti oil, becoming 
 viscid, would introduce erroneous results. 
 
 This mode has been lately practised with 
 the utmost scientific refinement by MM. 
 Dulong and Petit. Their experiments were 
 made on metals reduced to fine filings, 
 strongly pressed into a cylindrical vessel 
 of silver, very thin, very small, and the 
 axis of which was occupied by the reser- 
 voir of the thermometer. This cylinder, 
 containing about 460 grains of the substance, 
 heated about 12° F. above the ambient me- 
 dium, was suspended in the centre of a ves- 
 sel blackened interiorly, surrounded with 
 melting ice, and exhausted of air, to prolong 
 the period of refrigeration, which lasted ge- 
 nerally 15 minutes. Their results have dis- 
 closed a beautiful and unforeseen relation, 
 between the specific heats and primitive 
 combining ratios or atoms of the metals ; 
 namely, that the atoms of all simple bodies 
 have exactly the same capacity for heat . 
 Hence the specific heat of a simple sub- 
 stance, multiplied into the weight of its atom 
 or prime equivalent, ought to give always 
 the same product. 
 
 The law of specific heats being thus esta- 
 blished for elementary bodies, it became very 
 important to examine, under the same point 
 of view, the specific heats of compound bodies. 
 Their process applying indifferently to all 
 substances, whatever be their conductibility 
 or state of aggregation, they had it in their 
 pow er to subject to experiment, a great many 
 bodies whose proportions may be considered 
 as fixed ; but when they endeavoured to 
 mount from these determinations to that of 
 the specific heat of each compound atom, bv 
 a method analogous to that employed for the 
 simple bodies, they found themselves stopped 
 by the number of equally probable supposi- 
 tions among which they had to choose. “II 
 the method,” say they, “of fixing the weights 
 of the atoms of simple bodies lias not yet 
 been subjected to any certain rule, that of 
 the atoms of compound bodies has been, a 
 fortiori , deduced from suppositions purely 
 arbitrary.” They satisfy themselves by say- 
 ing, in the mean time, that, abstracting every 
 particular supposition, the observations which 
 they have hitherto made tend to establish 
 this remarkable law', that there always exists 
 a very simple ratio, between the capacity lor 
 beat of the compound atoms, and that ol the 
 elementary atoms. 
 
 We shall insert here tabular views of the 
 specific heats determined by the recent re- 
 
CAL 
 
 CAL 
 
 searches of these French chemists, reserving, 
 for the end of the volume, the usual more 
 extended, but less accurate tables of specific 
 beat. MM. Petit and Dulong justly re- 
 mark, that “ the attempts hitherto made to 
 discover some laws in the specific heats of 
 bodies have been entirely unsuccessful. We 
 shall not be surprised at this, if we attend to 
 the great inaccuracy of some of the mea- 
 surements ; for if we except those of La- 
 voisier and Laplace (unfortunately very few), 
 and those by Laroche and Berard for elastic 
 fluids, we are forced to admit, that the great- 
 est part of the others are extremely inaccu- 
 rate, as our own experiments have informed 
 us, and as might indeed be concluded from 
 the meat discordance in the results obtained 
 
 O m 
 
 for the same bodies by different experimen- 
 ters.” From this censure, we must except 
 the recent results of MM. Clement and De- 
 sormes on gases, which I believe may be 
 regarded as entitled to equal confidence with 
 those of Berard and Delaroche. 
 
 TABLE I . — Of the Specific Heats of Gases, 
 by MM. Berard and Delaroche. 
 
 
 Equal 
 | volumes. 
 
 Equal 
 
 weights. 
 
 Sp. 
 
 gravity. 
 
 Air, 
 
 1 .0000 
 
 1.0000 
 
 1 *0000 
 
 Hydrogen, 
 
 0.9033 
 
 12.3401 
 
 0.0732 
 
 Carbonic acid, 
 
 1.2583 
 
 0.8280 
 
 1.5196 
 
 Oxygen, 
 
 0*9765 
 
 0.8848 
 
 1.1036 
 
 Azote, 
 
 1.0000 
 
 1.0318 
 
 0.9691 
 
 Oxide of azote, 
 
 1.3503 
 
 0.8878 
 
 1.5209 
 
 Olefiant gas, 
 
 1.5530 
 
 1.5763 
 
 0.9885 
 
 Carbonic oxide, 
 
 1.0340 
 
 1.0805 
 
 0.9569 
 
 To reduce the above numbers to the stan- 
 dard of water, three different methods were 
 employed ; from which the three numbers, 
 0.2498, 0.2697, and 0.2813 were obtained 
 for atmospheric air. The experimenters 
 have taken 0.2669 as the mean, to which all 
 the above results are referred, as follows : 
 
 TABLE II. 
 
 Water 1.0000 
 
 Air 0.2669 
 
 Hydrogen gas 3.2936 
 Carbonic acid 0. 22 1 0 
 Oxygen 0.2361 
 
 Azote 0.2754 
 
 Oxide of azote 0.2369 
 Olefiant gas 0.4207 
 Carbonic oxide 0.2884 
 
 Aqueous vapour 0.8470 
 
 The following are the results given by 
 MM. Clement and Desormes, for equal vo- 
 lumes at temperatures from 0° to 60° cen- 
 tigrade, or 52° to 140° Fahr. 
 
 TABLE III. 
 
 Tnehes Clement & Delaroche 
 Barom. Desormes. & Berard. 
 
 Atmospheric air at 59.6 
 
 1.215 
 
 1.2396 
 
 Ditto 
 
 29.84 
 
 1.000 
 
 1.0000 
 
 Ditto 
 
 14.92 
 
 0.693 
 
 
 Ditto 
 
 7.44 
 
 0*540 
 
 
 Ditto 
 
 5.74 
 
 0.368 
 
 
 Do. charged with \ 
 ether, j 
 
 ^ 29.84 
 
 1.000 
 
 
 Azote, 
 
 29.84 
 
 1.000 
 
 1.0000 
 
 Oxygen, 
 
 29.84 
 
 1.000 
 
 0.974 
 
 Hydrogen, 
 
 29.84 
 
 0.664 
 
 0.9033 
 
 Carbonic acid, 
 
 29.84 
 
 1.500 
 
 1.2583 
 
 The relative specific heat of air 
 
 to water, 
 
 is by MM. Clement and Desormes 0.250 to 
 1.000, or exactly one-fourth. The last table, 
 which is extracted from the Journal de Phy- 
 sique, gives the specific heat of oxygen by 
 Delaroche and Berard, a little different from 
 their own number, Table I. from the An - 
 nales de Chimie , vol. 85. The most remark- 
 able result given by MM. Clement and De- 
 sormes regards carbonic acid, which being 
 reduced to the standard of weights, gives a 
 specific heat compared to air of about 0. 987 
 to 1.000, while oxygen is only 0.9000. The 
 former tables of Crawford and Dalton give 
 the sp. heat of oxygen 2.65, and of carbonic 
 acid 0.586, compared to air 1.000. And 
 upon these very erroneous numbers, they 
 reared their hypothetical fabric of latent 
 heat, combustion, and animal temperature. 
 
 We shall refer to the above table in treat- 
 ing of combustion. 
 
 We see from the experiments on air, at 
 different densities, that its specific heat dimi- 
 nishes in a much slower rate than its specific 
 gravity. When air is expanded to a quadru- 
 ple volume, its specific heat becomes 0.540, 
 and when expanded to eight times the vo- 
 lume, its specific heat is 0.368. The densi- 
 ties in the geometrical progression 1 . 
 correspond nearly to the specific heats in the 
 arithmetical series 5, 4, 3, 2. Hence also 
 the specific heat of atmospherical air, and of 
 probably all gases, considered in the ratio of 
 its weight or mass, diminishes as the den- 
 sity increases. On the principle of the in- 
 crease of specific heat, relative to its mass, 
 has been explained the long observed pheno- 
 menon of the intense cold which prevails on 
 the tops of mountains, and generally in the 
 upper regions of the atmosphere ; and also 
 that of the prodigious evolution of heat, 
 when air is forcibly condensed. According 
 to M. Gay Lussac, a condensation of volume 
 amounting to four-fifths, is sufficient to ig- 
 nite tinder. If a syringe of glass be used, 
 a vivid flash of light is seen to accompany 
 the condensation. 
 
CAL 
 
 CAL 
 
 TABLE IV . — Of Specific Heats of some 
 Solids determined by Du long and Petit. 
 
 
 Specific 
 heats, that 
 of water 
 being 100. 
 
 Weight of 
 the atoms, 
 oxygen be- 
 ing 1. 
 
 Product 
 of these 
 two num- 
 bers. 
 
 Bismuth, 
 
 0.0288 
 
 13.300 
 
 0. 3830 
 
 Lead, 
 
 0.0293 
 
 12.950 
 
 0.3794 
 
 Gold, 
 
 0.0298 
 
 12.430 
 
 0.3704 
 
 Platinum, 
 
 0.0314 
 
 1 1.160 
 
 0.3740 
 
 Tin, 
 
 0.0514 
 
 7.550 
 
 0.3779 
 
 Silver, 
 
 0.0557 
 
 6.750 
 
 0.3759 
 
 Zinc, 
 
 0.0927 
 
 4.030 
 
 0.3736 
 
 Tellurium, 
 
 0.0912 
 
 4.030 
 
 0.3675 
 
 Copper, 
 
 0.0949 
 
 3.957 
 
 0.3755 
 
 Nickel, 
 
 0.1035 
 
 3.690 
 
 0.3819 
 
 Iron, 
 
 0.1100 
 
 3.392 
 
 0.3731 
 
 Cobalt, 
 
 0.1498 
 
 2.460 
 
 0.3685 
 
 Sulphur, 
 
 0.1 8S0 
 
 2.011 
 
 0.3780 
 
 The above products, which express the capa- 
 cities of the different atoms, approach so 
 near equality, that the slight differences must 
 be owing to slight errors, either in the mea- 
 surement of the capacities, or in the chemi- 
 cal analyses, especially if we consider, that in 
 certain cases, these errors derived from these 
 two sources, may be on the same side, and 
 consequently be found multiplied in the re- 
 sult. Each atom of these simple bodies 
 seems, therefore, as was formerly stated, to 
 have the same capacity for heat. 
 
 An important question now occurs, whe- 
 ther the relative capacities for heat of diffe- 
 rent solid and liquid bodies be uniform at 
 different temperatures, or whether it vary 
 with the temperature ? This question may 
 be perhaps more clearly expressed thus : 
 Whether a body, in cooling a certain thermo- 
 metric range at a high temperature, gives out 
 the same quantity of heat that it does in 
 cooling through the same range at a lower 
 temperature ? No means seem better adapt- 
 ed for solving this problem, than to measure 
 the refrigeration produced, by the same 
 weights of ice, on uniform weights of wa- 
 ter, at different temperatures. Mr Dalton 
 found in this way, that “ 176.5° expresses 
 the number of degrees of temperature, such 
 as are found between 200° and 212° of the 
 old or common scale, entering into ice of 
 .72° to convert it into water of 32°; 150° 
 of the same scale, between 122° and 130°, 
 suffice for the same effect ; and between 45° 
 and 50°, 1 28° are adequate to the conversion 
 of the same ice into water. These three 
 resulting numbers, (128, 150, 176.5), are 
 nearly as 5, 6, 7. Hence it follows, that as 
 much heat is necessary to raise water 5° in 
 the lower part of the old scale, as is required 
 to raise it 7° in the higher, and 6° in the 
 middle .” — Sec bis A r ew System of Chemical 
 Philos, vol. i. p. 53. 
 
 Mr Dalton, instead of adopting the ob- 
 
 vious conclusion, that the capacity of water 
 for heat is greater at lower than it is at high- 
 er temperatures, and that therefore a smaller 
 number of degrees at the former, should melt 
 as much ice as a greater number at the lat- 
 ter, ascribes the deviation denoted by these 
 numbers, 5, 6, and 7, to the gross errors of 
 the ordinary thermometric graduation, which 
 he considers so excessive, as not only to 
 equal, but greatly to overbalance the really 
 increased specific heat or capacity of water; 
 which, viewed in itself, he conceives would 
 have exhibited opposite experimental results. 
 That our old , and, according to his notions, 
 obsolete thermometric scale, has no such pro- 
 digious deviation from truth, is, I believe, 
 now fully admitted by chemical philoso- 
 phers; and therefore the only legitimate in- 
 ference from these very experiments of Mr 
 Dalton, is the decreasing capacity of water, 
 with the increase of its temperature. It de- 
 serves to be remarked, that my experiments 
 on the relative times of cooling a globe of 
 glass, successively filled with water, oil of 
 vitriol, common oil, and oil of turpentine, 
 give exactly the same results as Mr Dalton 
 had derived from mixtures of two ounces of 
 ice with 60 of w r ater, at different tempera- 
 tures. This concurrence is the more satis- 
 factory, since when my paper on the specific 
 heats of the above bodies, published in the 
 Annals of Philosophy for October 1817, 
 was written, I had no recollection of Mr 
 Dalton’s experiments. 
 
 In the Annals of Philosophy for March 
 1819, Dr Thomson has made the following 
 remarks in reviewing my paper on heat : 
 “ The second topic which Dr Ure discusses 
 in this paper, is Mr Dalton’s opinion that 
 the common thermometer is an inaccurate 
 measurer of heat, and that mercury and all 
 liquids expand as the square of the tempera- 
 ture, reckoning from the freezing point. It 
 is not necessary to give a particular detail of 
 the facts contained in this part, as Mr Dal- 
 ton’s opinions on this subject had been al- 
 ready overturned by the experiments of Du- 
 long and Petit. Dr Ure’s notion, that the 
 capacity of bodies for heat diminishes as the 
 temperature increases, is directly contrary to 
 the results of the experiments of Dulong 
 and Petit on the subject. It seems also con- 
 trary to analogy in other cases. e know 
 that the capacity of elastic fluids increases as 
 they become rarer, and that the rarest of all 
 the elastic fluids has the greatest capacity. 
 It is reasonable, I think, that this should be 
 the case ; for the further the particles of a 
 body are removed from each other, the 
 greater must the quantity of heat be, which 
 shall be capable of producing a given effect 
 on it.” From the early part of this passage, 
 readers of the Annals would naturally inter, 
 that I had undertaken a refutation which 
 had been already accomplished. Tut it is 
 
CAI 
 
 CAL 
 
 consistent with Dr Thomson’s personal know- 
 ledge, that my paper on heat was finished 
 and sent off to London many months before 
 the paper of MM. Dulong and Petit was 
 published. Besides, in a question of such 
 vital importance to the whole of physical 
 science, as whether the thermometer be a 
 crude or correct indicator of the increments 
 of temperature, it is surely desirable to have 
 the investigation conducted in two original 
 and independent methods. Dr Thomson 
 has misconceived my views with regard to 
 capacity. T adduce some experimental evi- 
 dence to shew that the capacity of water for 
 heat diminishes as we raise it from the freez- 
 ing to the boiling point; but I did not so 
 far violate the rules of philosophy, as to 
 make a general inference from a particular 
 case, a practice, it must be confessed, too 
 common with some chemical writers. So 
 far from asserting the proposition for all 
 bodies, the idea is thrown out, of its being 
 perhaps a property peculiar to water, like 
 that of its expanding by diminution of its 
 heat, after being cooled down to 39°. 
 
 The total absence in the gases of cohesive 
 attraction, that power which governs the phe- 
 nomena of solids as to heat, and modifies those 
 of liquids, renders the analogy of elastic 
 fluids adduced by Dr Thomson quite irre- 
 levant. “ The above circumstance in water, 
 renders it peculiarly qualified for serving as 
 the magazine and equalizer of the tempera- 
 ture of the globe. Since at our ordinary 
 atmospherical heats, it possesses the greatest 
 capacity for caloric, small variations in its 
 temperature gave it a great modifying power 
 over the circumambient air.” See New Ex- 
 perimental Researches on some of the lead- 
 ing doctrines of Caloric, in the Philosophi- 
 cal Transactions for 1818, or in Tilloch’s 
 Magazine, vol. 53. I have looked with at- 
 tention over MM. Dulong and Petit’s paper, 
 for the results of their experiments on the 
 subject, which Dr Thomson pronounces to 
 be directly contrary to mine, but I could 
 find nothing which affects my proposition 
 with regard to water. Their experiments 
 lead them to conclude, that the capacities of 
 the following metallic bodies increase with 
 the elevation of their temperature, in the 
 following proportions. 
 
 TABLE V . — Of Capacities for Ileat. 
 
 Mean capacity between 
 0° & 100°. 
 
 Mean capacity 
 between 0° & 
 300°. 
 
 Mercury, 
 
 0.0330 
 
 0.0350 
 
 Zinc, 
 
 0.0927 
 
 0.1015 
 
 Antimony, 
 
 0.0507 
 
 0.0549 
 
 Silver, 
 
 0.0557 
 
 0.061 1 
 
 Copper, 
 
 0.0919 
 
 0.1013 
 
 F'latinum, 
 
 0.0355 
 
 0.0355 
 
 Glass, 
 
 0.1770 
 
 0.1900 
 
 The capacity of iron was determined at 
 the four following intervals : 
 
 From 0° to 100°, the capacity is 0.1098 
 
 0° to 200 0.1150 
 
 0° to 300 0.1218 
 
 0° to 350 0.1255 
 
 If we estimate the temperatures, as some 
 philosophers have proposed, by the ratios of 
 the quantities of heat which the same body 
 gives out in cooling to a determinate tem- 
 perature, in order that this calculation be 
 exact, it would be necessary that the body 
 in cooling, for example, from 500° to 0°, 
 should give out three times as much heat as 
 in cooling from 100 to 0°. But it will give 
 out more than three times as much, because 
 the capacities are increasing. We should 
 therefore find too high a temperature. We 
 exhibit in the following table the tempera- 
 tures that would be deduced by employing 
 the different metals contained in the preced- 
 ing table. We must suppose that they have 
 been all placed in the same liquid bath at 
 300°, measured by an air thermometer. 
 
 Iron, 
 
 Mercury, 
 
 Zinc, 
 
 Antimony, 
 
 Silver, 
 
 Copper, 
 
 Platinum, 
 
 Glass, 
 
 332.2° 
 - 318.2 
 
 328.5 
 
 324.8 
 329. 3 
 
 320.0 
 
 317.9 
 
 322.1 
 
 Experiments have been instituted, and 
 theorems constructed, for determining the 
 absolute quantity of heat in bodies, and the 
 point of the total privation of that power, 
 or of absolute cold, on the thermometric 
 scale. The general principle on which most 
 of the inquirers have proceeded is due to the 
 ingenuity of Dr Irvine. Supposing, for 
 example, the capacity of ice to be to that of 
 water as 8 to 10, at the temperature of 32°, 
 we know that in order to liquefy a certain 
 weight of ice, as much heat is required as 
 would heat the same weight of water to 140° 
 f ahr. Hence 140° represent two-tenths or 
 one-fifth of the whole heat of fluid water; 
 and therefore the whole heat will be 5 X 
 140° = 700° below 32°. It is needless to 
 present any algebraic equations on a princi- 
 ple which is probably erroneous, and which 
 has certainly produced in experiment most 
 discor dant results. Mr Dalton has given a 
 general view of them in his section on the 
 zero of temperature. 
 
 44 V- voit liiiHC lllC 
 
 of water as 9 to 1 0, then the zero will come 
 
 out ’ " 1400° 
 
 Gadolin, from the heat evolved! 2956° 
 in mixing sulphuric acid and water 1710 
 in different proportions, and com- ! 1510 
 
 “■ * / — — — 
 
 paring the capacity of the compound 
 with those of its components, deduc 
 ed the opposite numbers, 
 
 2637 
 
 3230 
 
 1710 
 
CAL 
 
 CAL 
 
 Mr Dalton, from sulphuric acid and 
 water, - 6400° 
 
 Do. do. do. 4150 
 
 Do. do. do. 6000 
 
 He thinks these to be no nearer approxi- 
 mations to the truth than Gadolin’s. 
 
 From the heat evolved in slaking' 
 lime, compared to the specific heats 
 of the compound, and its constitu- >4260 
 eats, lime and water, Mr Dalton j 
 gives as the zero, 
 
 From nitric acid and lime, Mr Dalton 
 finds - 11000 
 
 From the combustion of hydrogen, 5400 
 From Lavoisier and Laplace’s experiments 
 on slaked lime, - - - 3428 
 
 From their experiments on sulphuric acid 
 and water, - - - - 7262 
 
 Do. do. do. 2598 
 
 Do. from nitric acid and lime, -|- 23837 
 Dr Irvine placed it below 30°, = 900 
 
 Dr Crawford do. do. = 1500 
 
 The above result of Lavoisier and La- 
 place, on nitric acid and lime, shews the 
 theorem in a very absurd point of view, for 
 it places the zero of cold, above melting 
 platina. MM. Clement and Desormes have 
 been lately searching after the absolute zero, 
 and are convinced that it is at 266.66° be- 
 low the zero of the centigrade scale, or — 
 448° F. This is a more conceivable result. 
 But MM. Dulong and Petit have been led 
 by their investigation to fix the absolute zero 
 at infinity. “ This opinion,” say they, 
 “ rejected by a great many philosophers 
 because it leads to the notion, that the quan- 
 tity of heat in bodies is infinite, supposing 
 their capacity constant, becomes probable, 
 now that we know that the specific heats di- 
 minish as the temperatures sink. In fact the 
 law of this diminution may be such, that the 
 integral of heat, taken to a temperature in- 
 finitely low, may notwithstanding have a 
 finite value.” They farther infer, that the 
 quantity of heat developed at the instant of 
 the combination of bodies has no relation to 
 the capacity of the elements ; and that in the 
 greatest number of cases this loss of heat is 
 not followed by any diminution in the capa- 
 city of the compounds formed. This conse- 
 quence of their researches, if correct, is fatal 
 to the theorem of Irvine, and to all the 
 inferences that have been drawn from it. 
 
 3. Of the general habitudes of heat , with 
 the different forms of matter. 
 
 The effects of heat are either transient and 
 physical; or permanent and chemical, induc- 
 ing a durable change in the constitution of 
 bodies. The second mode of operation we 
 shall treat of under Combustion. The first 
 falls to be discussed here ; and divides itself 
 naturally into the two heads, of changes in 
 the volume of bodies while they retain their 
 form, and changes in the state of bodies. 
 
 lsf, The successive increments of volume, 
 which bodies receive with successive incre- 
 
 ments of temperature, have been the subjects 
 of innumerable researches. The expansion 
 of fluids is so much greater than that of so- 
 lids by the same elevation of their tempera- 
 ture, that it becomes an easy task to ascer- 
 tain within certain limits the augmentation 
 of volume which liquids and gases suffer 
 through a moderate thermometric range. 
 \Y r e have only to enclose them in a glass 
 vessel of a proper form, and expose it to 
 heat. But to determine their expansions 
 with final accuracy, and free the results 
 from the errors arising from the unequable 
 expansion of the recipient, is a problem of 
 no small difficulty. It seems, however, after 
 many vain attempts by preceding experi- 
 menters, to have been finally solved by MM. 
 Dulong and Petit. The expansion of solids 
 had been previously measured with consi- 
 derable accuracy by several philosophers, 
 particularly by Smeaton, Roy, liamsden, 
 and Trough ton, in this country, and Lavoi- 
 sier and Laplace in France. The method 
 devised by Genl. Roy, and executed by him 
 in conjunction with Ramsden, deserves the 
 preference. The metallic or other rod, the 
 subject of experiment, was placed horizon- 
 tally in a rectangular trough of water, which 
 could be conveniently heated. At any ali- 
 quot distance on the rod, two micrometer 
 miscroscopes were attached at right angles, 
 so that each being adjusted at first to two 
 immoveable points, exterior to the heating- 
 apparatus, when the rod was elongated by- 
 heat, the displacement of the microscopes 
 could be determined to a very minute quan- 
 tity, to the twenty or thirty thousandth of an 
 inch, by the micrometrical mechanism. 
 
 The apparatus of Lavoisier and Laplace 
 was on Smeaton’s plan, a series of levers ; 
 but differed in this respect, that the last lever 
 gave a vertical motion to a telescope of six 
 feet focal length, whose quantity of displace- 
 ment was determined by a scale in its field 
 of view from 100 to 200 yards distant. 
 This addition of a micrometrical telescope 
 was ingenious ; but the whole mechanism is 
 liable to many objections, from which that 
 of Ramsden was free. Still, when manag- 
 ed by such hands and heads as those of La- 
 voisier and Laplace, we must regard its re- 
 sults with veneration. MM. Dulong and 
 Petit have measured the dilatations of some 
 solids, as well as mercury, on plans which me- 
 rit equal praise for their originality and phi- 
 losophical precision. They commenced with 
 mercury. Their method with it is founded 
 on this incontestable law of hydrostatics, that 
 when two columns of a liquid communicate 
 by means of a lateral tube, the vertical 
 heights of these two columns are precisely 
 the inverse of their densities. In the axis 
 of two upright copper cylinders, vertical 
 tubes of glass w ere fixed, joined together at 
 bottom by a horizontal glass tube resting on 
 a levelled iron bar. One of the cylinders 
 
CAL 
 
 CAL 
 
 was charged with ice, the other with oil to 
 be warmed at pleasure by a subjacent stove. 
 The rectangular inverted glass syphon was 
 filled nearly to the top with mercury, and 
 the height at which the liquid stood in each 
 leg was determined with nicety by a teles- 
 copic micrometer, revolving in a horizontal 
 plane on a vertical rod. The telescope had 
 a spirit level attached to it, and could be 
 moved up or down a very minute quantity 
 by a fine screw. The temperature of the 
 oil, the medium of heat, was measured by - 
 both an air and a mercurial thermometer, 
 whose bulbs occupied nearly the whole ver- 
 tical extent of the cylinder. The elongation 
 of the heated column of mercury could be 
 rigorously known by directing the eye 
 through the micrometer, first to its surface, 
 and next to that in the ice-cold leg. Hav- 
 ing by a series of careful trials ascertained 
 the expansions of mercury through different 
 thermometric ranges, they then determined 
 the expansion of glass from the apparent 
 expansions of mercury within it. They 
 filled a thermometer with well boiled mer- 
 cury, and plunging it into ice, waited till the 
 liquid became stationary, and then cut across 
 the stem at the point where the mercury 
 stood. After weighing it exactly, they im- 
 mersed it for some time in boiling water. 
 On withdrawing, wiping, and weighing it, 
 they learned the quantity of mercury ex- 
 pelled, which being compared with the whole 
 w'eight of the mercury in it at the tempera- 
 ture of melting ice, gave the dilatation of 
 volume. This is precisely the plan employed 
 long ago by Mr Crighton, as well as myself, 
 and which gave the quantity l-63d, employed 
 in my paper for the apparent dilatation of 
 mercury in glass. 
 
 Their next project was to measure the dila- 
 tation of other solids ; and this they accom- 
 plished with much ingenuity by enclosing a 
 yl de o the solid, iron for example, in a 
 
 glass tube, which was filled up wdth mercu- 
 ry, after its point had been drawn out to a 
 capillary point. The mercury having been 
 previously boiled in it, to expel all air and 
 moisture, the tube was exposed to different 
 temperatures. By determining the weight 
 of the mercury which was driven out, it was 
 easy to deduce the dilatation of the iron ; for 
 the volume driven out obviously represents 
 the sum of the dilatations of the mercury 
 and the metal, diminished by the dilatation 
 of the glass. To make the calculation, it is 
 necessary to know the volumes of these three 
 bodies at. the temperature of freezing water ; 
 but that of the iron is obtained by dividing its 
 weight by its density at 32°. We deduce 
 in the same manner the volume of the glass 
 from the quantity of mercury which fills it 
 at that temperature. That of the mercury 
 is obviously the difference of the first two. 
 The process just pointed out may be applied 
 likewise to other metals, taking the precau- 
 tion merely to oxidize their surface to hinder 
 amalgamation. 
 
 In the years 1812 and 1813 1 made many 
 experiments with a micrometrical apparatus 
 of a peculiar construction, for measuring 
 the dilatation of solids. I was particularly 
 perplexed with the rods of zinc, which after 
 innumerable trials I finally found to elongate 
 permanently by being alternately heated and 
 cooled. It would seem that the plates com- 
 posing this metal, in sliding over each other 
 by the expansive force of heat, present such an 
 adhesive friction as to prevent their entire re- 
 traction. It "would be desirable to know the 
 limit of this effect, and to see what other 
 metals are subject to the same change. I 
 hope to be able ere long to finish these 
 pyrometrical researches. 
 
 I shall now present a copious table of 
 dilatations, newly compiled from the best 
 experiments. 
 
 TABLE I . — Linear Dilatation of Solids by Heat. 
 
 Dimensions which a bar takes at 212°, whose length at 52° is 1.000C00. 
 
 Glass tube, 
 do. 
 do. 
 do. 
 do. 
 
 Plate glass, 
 do. crown glass, 
 do. do. 
 
 do. do. 
 
 do. rod, 
 
 Deal, 
 
 Platina, 
 
 do. 
 
 do. 
 
 do. and glass, 
 
 Smeaton, 
 
 Roy, 
 
 Deluc’s mean, 
 Dulong and Petit, 
 
 Lavoisier and Laplace, 
 
 do. 
 
 do. 
 
 do. 
 
 do. 
 
 do. 
 
 do. 
 
 uo. 
 
 do. 
 
 Roy, 
 
 . 
 
 Roy, as glass, 
 
 
 Bor da, 
 
 ♦ 
 
 Dulong and Petit, 
 
 Troughton, 
 
 Berthoud, 
 
 1.00083333 
 
 1.00077615 
 
 1.00082800 
 
 1.00086130 
 
 1.00081166 
 
 1.000890890 
 
 1.00087572 
 
 1.00089760 
 
 1.00091751 
 
 1.00080787 
 
 1.00085655 
 1.00088420 
 1.00099180 
 1.001 10000 
 
 Dilatation 
 in Vulgar 
 Fractions. 
 
 TTTfJ 
 
 ttVst 
 
 i 
 
 TIsq 
 
 TT4? 
 
 TTT4 
 
 i 
 
 i o IT o' 
 
 r 
 
 tijt 
 
CAL 
 
 CAL 
 
 Palladium, 
 
 Wollaston, 
 
 1.00100000 
 
 Antimony, 
 
 Smeaton, 
 
 1.00108300 
 
 Cast iron prism, 
 
 Roy, 
 
 1.001 10940 
 
 Cast iron, 
 
 Lavoisier, by Dr Young, 
 
 1.00111111 
 
 Steel, 
 
 Troug'nton, 
 
 1.001 18990 
 
 Steel rod, 
 
 Roy, 
 
 1.00114470 
 
 Blistered steel, 
 
 Phil. Trans. 1795. 428, 
 
 1. 001 12500 
 
 do. 
 
 Smeaton, 
 
 1.001 15000 
 
 Steel not tempered, 
 
 Lavoisier and Laplace, 
 
 1.00107875 
 
 do. do. do. 
 
 do. do. 
 
 1.00107956 
 
 do. tempered yellow, 
 
 do. do. 
 
 1.00156900 
 
 do. do. do. 
 
 do. do. 
 
 1.00138600 
 
 do. do. do. at a higher heat, 
 
 do. do. 
 
 1.00123956 
 
 Steel, 
 
 Troughton, 
 
 1.001 18980 
 
 Hard steel, 
 
 Smeaton, 
 
 1.00122500 
 
 Annealed steel, 
 
 Muschenbroek, 
 
 1.00122000 
 
 Tempered steel, 
 
 do. 
 
 1.00137000 
 
 Iron, 
 
 Borda, 
 
 1.001 15600 
 
 do. 
 
 Smeaton, 
 
 1.00125800 
 
 Soft iron forged, 
 
 Lavoisier and Laplace, 
 
 1.00122045 
 
 Round iron, wire- drawn, 
 
 do. do. 
 
 1.90123504 
 
 Iron wire, 
 
 Troughton, 
 
 1.00144010 
 
 Iron, 
 
 Dulong and Petit, 
 
 1.00118203 
 
 Bismuth, 
 
 Smeaton, 
 
 1.00139200 
 
 Annealed gold, 
 
 Muschenbroek, 
 
 1.00146000 
 
 Gold, 
 
 Ellicot, by comparison, 
 
 1.00150000 
 
 do. procured by parting, 
 
 Lavoisier and Laplace, 
 
 1.00146606 
 
 do. Paris standard, unannealed. 
 
 do. do. 
 
 1.00155155 
 
 do. do. annealed, 
 
 do. do. 
 
 1.00151361 
 
 Copper, 
 
 Muschenbroek, 
 
 1.0019100 
 
 do. 
 
 Lavoisier and Laplace, 
 
 1.00172244 
 
 do. 
 
 do. do. 
 
 1.00171222 
 
 do. 
 
 Troughton, 
 
 1.00191880 
 
 do. 
 
 Dulong and Petit, 
 
 1.00171821 
 
 Brass, 
 
 Borda, 
 
 1.00178300 
 
 do. 
 
 Lavoisier and Laplace, 
 
 1.00186671 
 
 do. 
 
 do. do. 
 
 1.00188971 
 
 Brass scale, supposed from Hamburg, 
 
 Roy, 
 
 1.00185540 
 
 Cast brass, 
 
 Smeaton, 
 
 1.00187500 
 
 English plate-brass, in rod, 
 
 Roy, 
 
 1.00189280 
 
 do. do. in a trough form, 
 
 do. 
 
 1.00189490 
 
 Brass, 
 
 Troughton, 
 
 1.00191880 
 
 Brass wire, 
 
 Smeaton, 
 
 1.00193000 
 
 Brass, 
 
 Muschenbroek, 
 
 1.00216000 
 
 Copper 8, tin 1, 
 
 Smeaton, 
 
 1.00181700 
 
 Silver, 
 
 Herbert, 
 
 1.00189000 
 
 do. 
 
 Ellicot, by comparison, 
 
 1.0021000 
 
 do. 
 
 Muschenbroek, 
 
 1.00212000 
 
 do. of cupel, 
 
 Lavoisier and Laplace, 
 
 1.00190974 
 
 do. Paris standard, 
 
 do. do. 
 
 1 .00190868 
 
 Silver, 
 
 Troughton, 
 
 1.0020826 
 
 Brass 16, tin 1, 
 
 Smeaton, 
 
 1.00190800 
 
 Speculum metal, 
 
 do. 
 
 1.00193300 
 
 Spelter solder ; brass 2, zinc 1 , 
 
 do. 
 
 1.00205800 
 
 Malacca tin, 
 
 Lavoisier and Laplace, 
 
 1.00193765 
 
 Tin from Falmouth, 
 
 do. do. 
 
 1.00217298 
 
 Fine pewter, 
 
 Smeaton, 
 
 1.00228300 
 
 Grain tin, 
 
 do. 
 
 1.00248300 
 
 Tin, 
 
 Muschenbroek, 
 
 1.00284000 
 
 Soft solder; lead 2, tin 1, 
 
 Smeaton, 
 
 1.00250800 
 
 Zinc 8, tin 1, a little hammered, 
 
 do. 
 
 1.00269200 
 
 Lead, 
 
 Lavoisier and Laplace, 
 
 1.00284836 
 
 do. 
 
 Smeaton, 
 
 1.00286700 
 
 Zinc, 
 
 do. - 
 
 1.00294200 
 
 TTTT 
 
 ■g-hr 
 
 "S^T 
 
 tI'g 
 
 7>Xcr 
 
 ?T43* 
 
 <T6~r 
 
 T¥T 
 
 T1T4 
 
 rhr 
 
 TSX 
 
 T"l X 
 
 ti 1 ? 
 
 TXT 
 
CAL 
 
 CAL 
 
 do. 
 do. 
 
 an air thermometer. 
 
 Smeaton, 
 
 Dulong and Petit, 
 do. 
 
 do. 
 
 1.00301100 
 
 1.00086130 
 
 1.00091827 
 
 1.000101114 
 
 r 
 
 TY'C'T 
 
 To-g-ir 
 
 TSTT 
 
 Zinc, hammered out £ inch per foot. 
 
 Glass, from 32°, to 212°, 
 
 do. from 212°, to 392°, 
 
 do. from 392°, to 5 72°, 
 
 The last two measurements by 
 
 To obtain the expansion in volume, mul- 
 tiply the above decimal quantities by three, 
 or divide the denominators of tire vulgar 
 fractions by three ; the quotient in either 
 case is the dilatation sought. 
 
 We see that a condensed metal, one whose 
 particles have been forcibly approximated by 
 the wire-drawing process, expands more, as 
 might be expected, than metals in a looser 
 state of aggregation. The result for pewter, 
 I conceive, must be inaccurate. Lead ought 
 to communicate to tin, surely, a greater ex- 
 pansive property. Borda’s measure of pla- 
 tina is important. It was observed with the 
 rules which served for measuring the base of 
 the trigonometrical survey in France. The 
 observations in the table on tempered steel, 
 are, I believe, by that eminent artist, For- 
 tin, though they are included in the table 
 which M. Biot published, under the title of 
 Lavoisier and Laplace. 
 
 The amount of the dilatation of metals 
 becomes very useful to determine, in certain 
 cases, the change of dimension to which 
 astronomical instruments are liable. Thus 
 in measuring a base for the grand operation 
 of the meridian of France, Borda sought to 
 elude the uncertainties arising from expan- 
 sion of the measuring rods, by combining me- 
 tallic bars, so that they indicated, of them- 
 selves, their variations of temperature, and of 
 length. A rule of platina, twelve feet long, 
 was attached by one of its extremities to a 
 rule of copper somewhat shorter, which 
 rested freely on its surface, when placed in 
 a horizontal position. Towards the loose 
 end of the copper rule, there was traced on 
 the platina rule very exact linear divisions, 
 the parts of which were millionths of the 
 total length of this rule. The end of the 
 copper rule carried a vernier, whose coin- 
 cidences with the platina graduations were 
 observed with a microscope. Now, the dila- 
 tations of the platina and copper being un- 
 equal for equal changes of temperature, we 
 may conceive that the vernier of the copper 
 rule would incessantly correspond to va- 
 riable divisions, according as the tempera- 
 tures varied. Borda made use of these 
 changes, to know at every instant the com- 
 mon temperature of these two bars, and the 
 ratio of the absolute dilatations of their two 
 metals. The value of the vernier divisions 
 had been previously ascertained, by plung- 
 ing the compound bar into water of different 
 temperatures, contained in an oblong wooden 
 trough. It was therefore sufficient to read 
 the indications of this metallic thermometer, 
 
 in order to learn the true temperature of the 
 bars in the atmosphere ; and of course, the 
 compensation to be made on the meter rods 
 or chains, to bring them to the true length 
 at the standard temperature. 
 
 An exact acquaintance with the dilata- 
 tion of metals, is also necessary for regulat- 
 ing the length of the pendulum in astrono- 
 mical clocks. When the ball or bob of a 
 seconds pendulum is let down y^qy of an 
 inch, the clock will go ten seconds slower in 
 
 24 hours; and therefore jj)0~6 0 f an inch, 
 will make it lose one second per day. Now, 
 as the effective length of the seconds pendu- 
 lum is 39.13929 inches, we know from the 
 previous table of expansion, that a change of 
 30 degrees of temperature by Fahrenheit’s 
 
 scale, will alter its length about 
 part, which Is equivalent to nearly 0.0078, 
 or y|~g of an inch, corresponding to about 
 eight seconds of error in the day. The 
 first, the most simple, and most perfect in- 
 vention for obviating these variations, is due 
 to Graham. The bob of his compensation 
 pendulum consisted of a glass cylinder, 
 about six inches long, holding ten or twelve 
 pounds of mercury. In proportion as the 
 iron or steel rod to which this was suspend- 
 ed, dilated by heat, the mercury also ex- 
 panded, and raised thereby the centre of 
 oscillation, just as much as the lengthening 
 of the rod had depressed it. M. Biot, with 
 his usual accuracy, has shewn, that if the 
 suspending rod were of glass, the length of 
 the cylinder of mercury would require to be 
 yy the total length of the pendulum, name- 
 ly, about four inches; but the expansion of 
 iron being greater in the ratio, pretty nearly 
 of three to two, we have hence the length of 
 the cylinder in the latter case, equal to about 
 six inches. The late very ingenious Mr 
 Gavin Lowe, prescribed, along with a steel 
 rod, a glass cylinder two inches diameter 
 inside, containing 6yy vertical inches of 
 mercury, weighing ten pounds. From ac- 
 curate calculation he found, that if such a 
 pendulum should go perfectly true, when 
 the thermometer is at 30°, but that at 90° 
 it should go one second slower in 24 hours, 
 it would be remedied by pouring in ten 
 ounces more quicksilver; or, by taking out 
 that quantity, if it went one second faster in 
 24 hours, when at 90° than at 30° Fahr. ; and 
 
 for yy of a second of deviation in 24 hours, 
 the compensation is the addition or abstrac- 
 tion of one ounce of mercury. Sec a useful 
 paper on this subject, by Mr Firminger, in 
 
CAL 
 
 CAL 
 
 the Philosophical Magazine for August 
 1819. 
 
 1 he balance wheel of a watch, varies in 
 the time of its oscillations, by its expansions 
 and contractions with variations of tem- 
 perature. The invention of Arnold fur- 
 nished a wheel or interrupted ring, compos- 
 ed of concentric laminae of two metals, 
 
 which, obviating the above defect by theii 
 difference of dilatation, has, under the name 
 of compensation balance, incalculably im- 
 proved the accuracy of marine chronometers. 
 We shall describe under Thermometer, an 
 elegant instrument constructed on similar] 
 principles, by the celebrated M.. Breguet.l 
 See other applications, infra . 
 
 TABLE II . — Dilatation of the volume of Liquids by being heated 
 
 from 32° to 2 1 2°. 
 
 Mercury, Dalton, - ► 
 
 0.020000 
 
 do. 
 
 Lord Charles Cavendisli, 
 
 0.018870 
 
 do. 
 
 Deluc, - * 
 
 0.018000 
 
 do. 
 
 General Roy, 
 
 0.017000 
 
 do.. 
 
 Shuckburgh, 
 
 0.01851 
 
 do. 
 
 Lavoisier and Laplace, 
 
 0.01810 
 
 do. 
 
 Haellstroem, 
 
 0.0181800 
 
 do. 
 
 Dulong and Petit, 
 
 0.0180180 
 
 do. 
 
 do. from 212°, to 392°, 
 
 0.0184331 
 
 do. 
 
 do. from 392°, to 572°, 
 
 0.0188700 
 
 do. 
 
 do. in glass, from 32°, to 21 2°, 
 
 0.015432 
 
 do. 
 
 do. do. from 212°, to 392°, 
 
 0.015680 
 
 do. 
 
 do. do. from 392°, to 572°, 
 
 0.0158280 
 
 Water, 
 
 Kirwan, from 39°, its maximum density, 
 
 0.04332 
 
 Muriatic acid, (sp. gr. 1.137), 
 
 Dalton, 
 
 0.0600 
 
 Nitric acid, (sp. gr. 1.40), 
 
 do. 
 
 0.1 ICO 
 
 Sulphuric acid, (sp. gr. 1.85), 
 
 do. 
 
 0.0600 
 
 Alcohol, 
 
 do. 
 
 0.1100 
 
 Water, 
 
 do. 
 
 0.0460 
 
 Water saturated with common salt, 
 
 do. 
 
 0.0500 
 
 Sulphuric ether, 
 
 do. 
 
 0.0700 
 
 Fixed oils, 
 
 do. 
 
 0.0800 
 
 Oil of turpentine, 
 
 do. 
 
 0.0700 
 
 The quantities given by Mr Dalton, are probably 
 too great, as is certainly the case w ith mercury ; 
 his experiments being perhaps modified by his 
 hypothetical notions. 
 
 Water saturated with common salt, Robison, 
 
 0.05198 
 
 I 
 
 JT) 
 
 l 
 
 JJ 
 
 l 
 
 JK 
 
 l 
 
 Tff 
 
 l 
 
 JT 
 
 l 
 
 65.22 
 
 1 
 
 IL 
 
 55.50 
 
 1__ 
 
 54.25 
 
 1 
 
 JJ 
 
 1 
 
 64.8 
 1 
 
 63.78 
 
 1 
 
 63.18 
 
 1 
 
 23.08 
 
 1 
 
 T7 
 
 1 
 
 g 
 
 i 
 
 T7 
 
 l 
 
 gg 
 
 i 
 
 HJS 
 
 i 
 
 ii 
 
 i 
 
 12.5 
 
 1 
 
 TT 
 
 i 
 
 Tg 
 
 Dr Young, in his invaluable Catalogue 
 raisonnec , Natural Philosophy, vol. ii. p. 391. 
 gives the following table of the expansions 
 of water, constructed from a collation of ex- 
 periments by Gilpin, Kirwan, and Achard. 
 He says, that the degrees of Fahrenheit’s 
 thermometer, reckoning either way from 39° 
 being called f the expansion of water is 
 nearly expressed by 22/' 2 (l — .002 f) in 10 
 millionths ; and the diminution of the speci- 
 fic gravity by .0000022/' 2 — .000000004 7 2 f 3 . 
 This equation, as well as the table, are very 
 important for the reduction of specific gra- 
 vities of bodies, taken by weighing them in 
 water. 
 
 Sp. grav. 
 50° 0.99980 
 
 32 0.99988 
 
 34 0.99994 
 
 Dimin. of sp. gr. Expansion. 
 0.00020 
 0.00012 
 0.00006 
 
 
 Sp. grav. 
 
 Dimin.ofsp.gr. I 
 
 Cxpansiom 
 
 39° 
 
 1.00000 
 
 
 0.00000 
 
 
 44 
 
 0.99994 
 
 
 0.00006 
 
 
 48 
 
 0.99982 
 
 
 0.00018 
 
 
 49 
 
 0.99978 
 
 
 0.00022 
 
 
 54 
 
 0.99951 
 
 
 0.00049 
 
 
 59 
 
 0.99914 
 
 
 0.00086 
 
 
 60 
 
 0.99906 
 
 
 0.00094 
 
 
 64 
 
 0.99867 
 
 
 0.00133 
 
 
 69 
 
 0.99812 
 
 
 0.00188 
 
 
 74 
 
 0.99749 
 
 
 0.00251 
 
 
 (77°) 
 
 0.99701 
 
 Achard 
 
 
 0.00299 
 
 79 
 
 0.99680 
 
 Gilpin 
 
 0.00320 
 
 0.00521 
 
 (82) 
 
 0.99612 
 
 Kirwan 
 
 0.00388 
 
 0.00389 
 
 90 
 
 0.9951 1 
 
 Gilpin 
 
 0.00489 
 
 0.00491 
 
 100 
 
 0.99313 
 
 
 0.00687 
 
 0.00692 
 
 1 02 
 
 0.99246 
 
 Kirwan 
 
 0.00754 
 
 0.00760 
 
 122 
 
 0.98757 
 
 
 0.01243 
 
 0.01258 
 
 
 0.98872 
 
 Deluc 
 
 0.01 128 
 
 
CAL 
 
 CAL 
 
 
 Sp. grav. 
 
 Dimin.of sp.gr. Expansion, 
 
 142° 
 
 0.98199 
 
 K. 
 
 0.01801 0.01855 
 
 162 
 
 0.9758.5 
 
 
 0.02417 0.02481 
 
 167 
 
 0.97480 
 
 Deluc 
 
 0.02520 
 
 182 
 
 0.96900 
 
 K. 
 
 0.03100 0.03198 
 
 202 
 
 0.96145 
 
 
 0.03855 0.04005 
 
 212 
 
 0.95848 
 
 
 0,04152 0.04533 
 
 Deluc introduced into a series of thermo- 
 meter glasses, the following liquids, and 
 noted their comparative indications by ex- 
 pansion at different degrees of heat, measur- 
 ed on Reaumur’s thermometer, of which 80° 
 is the boiling point of water, and 0° the melt- 
 ing point of ice. 
 
 TABLE of Thermometric Indications by Deluc. 
 
 Mercury. 
 
 Olive 
 
 Oil. 
 
 Es . Oil of 
 Chamomile. 
 
 Oil of 
 Thyme. 
 
 Alcohol. 
 
 Brine. 
 
 Water. 
 
 R. 
 
 Cent. 
 
 Fahr. 
 
 80 ° 
 
 100° 
 
 212° 
 
 80° 
 
 80° 
 
 80° 
 
 80° 
 
 80° 
 
 80° 
 
 75 
 
 93* 
 
 200| 
 
 74.6 
 
 74.7 
 
 74.3 
 
 75.8 
 
 74.1 
 
 71 
 
 70 
 
 87.5 
 
 189* 
 
 69.4 
 
 69.5 
 
 68.8 
 
 67.8 
 
 68.4 
 
 62 
 
 65 
 
 81. 
 
 178* 
 
 64.4 
 
 64.3 
 
 65.5 
 
 61.9 
 
 62.6 
 
 53.5 
 
 60 
 
 75. 
 
 167 
 
 59.3 
 
 59.1 
 
 58.3 
 
 56.2 
 
 57.1 
 
 45.8 
 
 55 
 
 68 f 
 
 155* 
 
 54.2 
 
 53.9 
 
 53.3 
 
 50.7 
 
 51.7 
 
 38.5 
 
 50 
 
 62 i 
 
 144* 
 
 49.2 
 
 48.8 
 
 48.3 
 
 45.3 
 
 46.6 
 
 32. 
 
 45 
 
 56 \ 
 
 1 33* 
 
 44.0 
 
 43.6 
 
 43.4 
 
 40.2 
 
 41.2 
 
 26.1 
 
 40 
 
 50 
 
 122 
 
 39.2 
 
 58.6 
 
 38.4 
 
 35.1 
 
 36.3 
 
 20.5 
 
 35 
 
 43* 
 
 no* 
 
 34.2 
 
 33.6 
 
 33.5 
 
 30.3 
 
 31.3 
 
 15.9 
 
 30 
 
 37* 
 
 99* 
 
 29.3 
 
 28.7 
 
 28.6 
 
 25.6 
 
 26.5 
 
 1 1.2 
 
 25 
 
 31 4 
 
 88| 
 
 24.3 
 
 23.8 
 
 25.8 
 
 21.0 
 
 21.9 
 
 7.3 
 
 20 
 
 25 
 
 77 
 
 19.3 
 
 18.9 
 
 19.0 
 
 16.5 
 
 17.3 
 
 4.1 
 
 15 
 
 i si 
 
 65 j 
 
 14.4 
 
 14.1 
 
 14.2 
 
 12.2 
 
 12.8 
 
 1.6 
 
 10 
 
 12* 
 
 54* 
 
 9.5 
 
 9.3 
 
 9.4 
 
 7.9 
 
 8.4 
 
 0.2 
 
 5 
 
 6 i 
 
 43* 
 
 4.7 
 
 4.6 
 
 4.7 
 
 3.9 
 
 4.2 
 
 0.4 
 
 0 
 
 0 
 
 32 
 
 0.0 
 
 0.0 
 
 0.0 
 
 0.0 
 
 0.0 
 
 0.0 
 
 — 5 
 
 H 
 
 20* 
 
 
 
 
 —3.9 
 
 —4.1 
 
 
 —10 
 
 12* 
 
 9* 
 
 
 
 
 —7.7 ! 
 
 —8.1 
 
 
 As I consider these results of Deluc va- 
 luable, in so far as they enable us to com- 
 pare directly the expansions in glass of these 
 different thermometric liquids, I have added 
 the two columns marked Cent, and Fahr. 
 to give at once the reductions to the centi- 
 grade and Fahrenheit graduation. The al- 
 cohol was of such strength that its flame 
 kindled gunpowder, and it was found that the 
 results were not much changed by a small 
 difference in the strength of the spirit. The 
 brine was water saturated with common salt. 
 
 M. Biot, in the first volume of his ela- 
 borate Traite dc Physique , has investigated 
 seveial ernpyrical formula;, to represent the 
 laws of dilatation of the different fluids. 
 They are too complex for a work of this na- 
 ture. lie shews that for all liquids whose 
 dilatations have been hitherto observed, the 
 general march of this dilatation may be re- 
 presented at every temperature by* an ex- 
 
 pression of this form, t — at -J- bt 2 -f ct\ 
 
 in which t denotes the temperature in de- 
 grees of the mercurial thermometer ; a b c 
 •constant coefficients, which depend on the 
 
 nature of the liquid ; and d f the true dilata- 
 tion for the volume 1.0 from the tempera- 
 ture of melting ice. We shall content our- 
 selves with giving one example, from which 
 we may judge of the great geometrical 
 resources of this philosopher. For olive oil 
 
 the formula becomes ^T = 0.95067 T -f 
 
 0.00075 T 3 — 0.000001667 T 3 . 
 
 The following table gives its results com- 
 pared with experiment. 
 
 Of the mercurial. 
 
 Calculated. 
 
 Observ 
 
 80° 
 
 80° 
 
 80° 
 
 70 
 
 69.64 
 
 69.41 
 
 60 
 
 59.37 
 
 59.3 
 
 50 
 
 49.2 
 
 49.2 
 
 40 
 
 39.12 
 
 39.2 
 
 30 
 
 29.15 
 
 29.3 
 
 20 
 
 19.30 
 
 19.3 
 
 10 
 
 9.58 
 
 9.5 
 
 
 0.0 
 
 0 . 
 
 M. Gay Lussac has lately endeavoured to 
 discover some law which should correspond 
 "ith the rate of dilatation of different liquids 
 
 I 
 
CAL 
 
 CAL 
 
 by heat, lor this purpose, instead of com- 
 paring the dilatations of different liquids, 
 above or below a temperature uniform for 
 all, he set out from a point variable with re- 
 gard to temperature, but uniform as to the 
 cohesion of the particles of the bodies ; 
 namely, from the point at which each liquid 
 boils under a given pressure. Among those 
 which he examined, he found two which di- 
 late equally from that point, viz. alcohol and 
 sulphuret of carbon, of which the former 
 boils at 173.14°, the latter at 1 1 5. 9° Falir. 
 
 I he other liquids did not present, in this 
 respect, the same resemblance. Another 
 analogy of the above two liquids is, that the 
 same volume of each gives, at its boiling 
 point, under the same atmospheric pressure, 
 the same volume of vapour, or in other 
 words, that the densities of their vapours are 
 to each other as those of the liquids at their 
 respective boiling temperatures. The fol- 
 lowing table shews the results of this distin- 
 guished chemist. 
 
 TABLE of the Contractions of 1000 parts in volume , by cooling. 
 
 
 Water. 
 
 Alcohol. 
 
 Sulphuret of Carb. 
 
 Ether. 
 
 Contract 
 by expt. 
 
 Ditto 
 
 calculated 
 
 Contract 
 by expt. 
 
 Ditto 
 
 calculated 
 
 Contract 
 by expt. 
 
 Ditto 
 
 calculated 
 
 Contract 
 by expt. 
 
 Ditto 
 
 calculated 
 
 Boiling, 
 
 0.00 
 
 0.00 
 
 0.00 
 
 0.00 
 
 0.00 
 
 0.00 
 
 0.00 
 
 0.00 
 
 — 5° 
 
 3.34 
 
 3.35 
 
 5.55 
 
 5.56 
 
 6.14 
 
 6.07 
 
 8.15 
 
 8.16 
 
 —10 
 
 6.61 
 
 6.65 
 
 11.43 
 
 11.24 
 
 12.01 
 
 12.08 
 
 16.17 
 
 16.01 
 
 — 15 
 
 10.50 
 
 9.89 
 
 17.51 
 
 17.00 
 
 17.98 
 
 17.99 
 
 24.16 
 
 23.60 
 
 —20 
 
 13.15 
 
 13.03 
 
 24.34 
 
 23.41 
 
 23.80 
 
 23.80 
 
 31.83 
 
 50.92 
 
 — 25 
 
 16.06 
 
 1 6.06 
 
 29.15 
 
 28.60 
 
 29.65 
 
 29.50 
 
 39.14 
 
 38.08 
 
 —30 
 
 18.85 
 
 18.95 
 
 34.74 
 
 34.37 
 
 55.06 
 
 35.05 
 
 46.42 
 
 45.04 
 
 —35 
 
 21.52 
 
 21.67 
 
 40.28 
 
 40.05 
 
 40.48 
 
 40.43 
 
 52.06 
 
 51.86 
 
 — 40 
 
 24.10 
 
 24.20 
 
 45.68 
 
 45.66 
 
 45.77 
 
 45.67 
 
 58.77 
 
 58.77 
 
 —45 
 
 26.50 
 
 26.52 
 
 50.85 
 
 51.11 
 
 51.08 
 
 50.70 
 
 65.48 
 
 65.20 
 
 —50 
 
 28.56 
 
 28.61 
 
 56.02 
 
 56.37 
 
 56.28 
 
 55.52 
 
 72.01 
 
 71.79 
 
 —55 
 
 30.60 
 
 30.45 
 
 61.01 
 
 61.43 
 
 61.14 
 
 60.12 
 
 78.38 
 
 78.36 
 
 — 60 
 
 32.4 2 
 
 31.96 
 
 65.96 
 
 66.23 
 
 66.21 
 
 64.48 
 
 
 
 —65 
 
 34.02 
 
 53.19 
 
 10.74 
 
 70.75 
 
 
 
 
 
 —70 
 
 35.47 
 
 34.09 
 
 75.48 
 
 74.93 
 
 
 
 
 
 —75 
 
 36.70 
 
 54.63 
 
 80.11 
 
 78.75 
 
 
 
 
 
 Their respective boiling points are : 
 
 Water, 
 
 100° Cent. 
 
 = 212° F. 
 
 Alcohol, 
 
 78.41 
 
 173 
 
 Sulphuret of carb. 
 
 46.60 
 
 126 
 
 Sulphuric ether, 
 
 35.66 
 
 96 
 
 The experiments were made in thermo- 
 meter vessels, hermetically sealed. 
 
 Alcohol, at 78.41° cent, produces 488.3 
 its vol. of vapour. 
 
 Sulphuret of carbon, at 46.60° cent, pro- 
 duces 491.1 its vol. of vapour. 
 
 Ether, at 35.66° cent, produces 285.9 its 
 vol. of vapour. 
 
 Water, at 100.00° cent, produces 1633.1 
 its vol. of vapour. 
 
 l)r Thomson, treating of expansion, states, 
 that “ different kinds of glass differ so much 
 from each other, that no general rule can 
 be laid down.” — System, vol. i. page 73. 
 This statement is at variance with the results 
 of MM. Dulong and Petit, as well as of my 
 own pyrometrical measurements. “ Nor have 
 we found,” say these accurate observers, 
 any appreciable difference between the ef- 
 
 fects observed in tubes of ordinary glass ob- 
 tained from different manufactories, what- 
 ever was their calibre or their thickness.” 
 T believe the differences to have arisen from 
 the errors of the previous pyrometrical mea- 
 surements, applied to a body whose dilata- 
 tion is so small. Thus General Roy, per- 
 haps the most accurate of all experimenters, 
 found at one time, that a glass tube expand- 
 ed four times as much as a rod ; and he af- 
 terwards found, on the contrary, that the rod 
 expanded more than the tube by about rry> 
 the glass being from the same pot. I found, 
 that a rod and tube made out of the same 
 glass pot expanded the same quantity, through 
 a range of 400° Falir. ; and believe, that 
 such crystal or (lint-glass as is used in Great 
 Britain for chemical purposes, is w onderfully 
 uniform in its rate of dilatation by heat, 
 through the same portions of the thermome- 
 tric scale. Nor are the differences consider- 
 able between the expansions of crown and 
 plate glass. 
 
 The different rate of expansion which li- 
 
CAL 
 
 CAL 
 
 quids undergo, by the same degree of tem- 
 perature, has been theorized upon by Dr 
 Thomson ; and as this is the only example in 
 his writings in which he has ventured to 
 propound an original philosophical law, it is 
 entitled to examination. 
 
 “ The expansion of liquid bodies differs 
 from that of the elastic fluids, not only in quan- 
 tity, but in the want of uniformity with which 
 they expand, when equal additions are made 
 to the temperature of each. This difference 
 seems to depend upon the fixity or volatility 
 of the component parts of the liquid bodies ; 
 for, in general, those liquids expand most by 
 a given addition of heat whose boiling tem- 
 peratures are lowest, or which contain in 
 them an ingredient which readily assumes 
 the gaseous form. Thus mercury expands 
 much less when heated to a given tempera- 
 ture than water, which boils at a heat much 
 inferior to mercury ; and alcohol is much 
 more expanded than water, because its boil- 
 ing temperature is lower. In like manner, 
 nitric acid is much more expanded than sul- 
 phuric acid, not only because its boiling 
 
 point is lower, but because a portion of it 
 has a tendency to assume the form of an 
 elastic fluid. This rule holds at least in all 
 the liquids whose expansions I have hitherto 
 tried. We may consider it therefore as a 
 pretty general fact, that the higher the tem- 
 perature necessary to cause a liquid to boil, 
 the smaller the expansion is which is pro- 
 duced by the addition of a degree of heat ; 
 or, in other words, the expansibility of li- 
 quids is nearly inversely as their boiling 
 temperatures.” — Thomson s Chemistry , 5th 
 edition , vol. i. pp. 66 and 67. 
 
 After enforcing, in such varied expres- 
 sions, his new law, that the lower the boil- 
 ing point of a liquid is, the greater is its ex- 
 pansibility by heat, one would not expect to 
 find it completely abrogated and set at 
 nought, by a table of experimental results 
 in the very same page. Yet sucli is the 
 fact, as its quotation will prove. 
 
 “ The following table exhibits the dilata- 
 tion of various liquids, from the temperature 
 of 32° to that of 212°, supposing their bulk 
 at 32° to be 1. 
 
 “ Alcohol, 
 
 Nitric acid, (sp. gr. 1.40) 
 
 Fixed oils, 
 
 Sulphuric ether, - - 
 
 Oil of turpentine, 
 
 Muriatic acid, (sp. gr. 1.137) 
 Sulphuric acid, (sp. gr. 1.85) 
 Water saturated with common salt, 
 Water, 
 
 Mercury, 
 
 0.1100 
 
 — 
 
 a 
 
 “ boiling 
 
 point, 174° 
 
 0.1 100 
 
 = 
 
 i - 
 
 V 
 
 ditto 
 
 247 
 
 0.080 
 
 = 
 
 i 
 
 ] 2 
 
 ditto 
 
 600 
 
 0.070 
 
 — 
 
 1 
 
 1 4 
 
 ditto 
 
 98 
 
 0.070 
 
 — ■ 
 
 ] 
 
 ditto 
 
 314 
 
 0.060 
 
 = 
 
 _L 
 
 IT 
 
 ditto 
 
 217 
 
 0.060 
 
 = 
 
 l 
 
 7T 
 
 ditto 
 
 620 
 
 0.05 
 
 = 
 
 l 
 
 £T<T 
 
 - ditto 
 
 225 
 
 0.0466 
 
 = 
 
 l 
 
 2 ‘2 
 
 ditto 
 
 212 
 
 0.02 
 
 = 
 
 1 >> 
 JO 
 
 ditto 
 
 656” 
 
 I have added the boiling points as set 
 down in his System. We here remark that 
 alcohol and nitric acid have the same rate of 
 expansion affixed, though the distances of 
 their respective boiling points from 32°, are 
 as 2 to 3. But the most amusing illustra- 
 tion of the converse of Dr Thomson’s law, is 
 presented by himself with regard to fixed 
 oil and ether, the former having the greater 
 expansion, though its boiling point is about 
 ten tunes more distant in thermometric de- 
 grees, than that of ether, from 32°. Ether 
 and oil of turpentine expand the same pro- 
 portion, and yet their boiling points differ 
 by 216°. But muriatic acid and sulphu- 
 ric acid also expand the same quantity, 
 though their boiling points, and “ their ten- 
 ancies to assume the form of an elastic 
 luid” are exceedingly different. Finally, 
 vater expands less than sulphuric acid, while 
 ts boiling temperature is greatly lower. 
 Had Dr Thomson propounded the very re- 
 r erse proposition, viz. that the rate of ex- 
 pansion in liquids is higher the higher their 
 •oiling temperatures, he would have en- 
 countered fewer contradictory facts, though 
 
 S 
 
 still enow to explode the generality of the 
 principle. In a philosophical system of che- 
 mistry, examples of such false reasoning are 
 injurious to the student, and lower the rank 
 of the science. 
 
 Mercury in its expansions, follows the rate 
 of fluid metals, and therefore is not properly 
 comparable to oily, watery, or spirituous 
 liquids. It is curious that one of the examples 
 which Dr Thomson adduces to illustrate his 
 pretended rule, which “holds, he says, at least 
 in all the liquids whose expansion I have 
 hitherto tried,” actually breaks it ; for alcohol 
 expands fully a half more than ether ; and 
 yet, the interval from its boiling point to 2 , 
 is more than double that interval in ether, in- 
 stead of being greatly less as his law requires. 
 Since his table obviously disqualifies water, 
 alcohol, ether, oils, and acids, from consti- 
 tuting such a series in expansion, as his rule 
 requires, one may naturally ask this celebrat- 
 ed chemist, what are “ the liquids whose ex- 
 pansion he has hitherto tried?” 
 
 In solid metals, the expansion seems to be 
 greater, the less their tenacity and density, 
 though to this general position, we have 
 
CAL 
 
 CAL 
 
 striking exceptions in antimony and bismuth, 
 provided they were accurately measured by 
 Smeaton s apparatus, of which, however, I 
 have reason to doubt. The least flexure in 
 the expanding rods, will evidently make the 
 expansions come out too small. If metallic 
 dilatability vary with some unknown function 
 of density and tenacity, as is probable a priori , 
 we would expect their rate of expansion to 
 increase with the temperature. This view 
 coincides with the following results of MM. 
 Dulong and Petit. 
 
 Temperatures by 
 dilatation of air. 
 
 0° to 100° cent, give 
 0° to 300°, mean quantity, 
 
 Expansions in 
 bulk of 
 
 Iron. Cop. Plat. 
 
 1 1 
 
 2b 2 l OT 377 
 1 l 1 
 227 T77 3773 
 
 Tripling these denominators, we have the 
 linear expansions, fractionally expressed, thus: 
 
 0° to 100° cent. 
 0 to 300°, mean, 
 
 Iron. Cop. Plat. 
 77437 7TT2 TT3T 
 
 l _ l _ l 
 
 775T 33T 107H) 
 
 To multiply inductive generalizations, that 
 is, to groupe togetherness which have some 
 important qualities common to them all, is the 
 main scope and business of philosophy. But 
 to imagine phenomena, or to twist real pheno- 
 mena into the shape suited to a preconceived 
 constitution of things, was the vice of the Pe- 
 ripatetic schools, which Bacon so admirably 
 exposed ; of which in our times and studies, 
 according to MM. Dulong and Petit, Mr 
 Dalton’s speculations on the laws of heat, 
 afford a striking example. 
 
 Mr Dalton has the merit of having first 
 proved that the expansions of all aeriform 
 bodies, when insulated from liquids, are uni- 
 form by the same increase of temperature ; a 
 fact of great importance to practical chemistry, 
 which was fully verified by the independent 
 and equally original researches of M. Gay 
 Lussac on the subject, with a more refined 
 and exact apparatus. The latter philosopher 
 demonstrated, that 100 in volume at .32° 
 Fahr. or 0° cent, become 1.375 at 212° Fahr. 
 or 100° cent. Hence the increment of bulk 
 
 for each degree F. is = 0.002083 =J 
 
 LIT 0 ; for the centigrade scale it is °— 
 
 1 100 
 — 0.00375 = '5 '7777-77* f ° reduce any vo- 
 
 lume of gas, therefore, to the bulk it would 
 occupy at any standard temperature, we 
 must multiply the thermometric difference 
 in degrees of Fahr. by 0.002083, or 
 subtracting the product from the given vo- 
 lume, if the gas be heated above, but adding 
 it, if the gas be cooled below, the standard 
 temperature. Thus 25 cubic inches at 120 w 
 Fahrenheit will at 60° occupy a volume of 
 
 21 vt : for fh X 60 = 4 <$>=£ ; and */ 
 
 which, taken from 25, leaves 21 7. \ 
 table of reduction will be found under Gas. 
 W hen the table is expressed decimally, in- 
 deed, to 6 or 7 figures, it becomes more 
 troublesome to apply than the above rule. 
 Vapours, when heated out of contact of their 
 respective liquids, obey the same law as 
 gases, a discovery due to M. Gay Lussac. 
 
 V T e shall now treat of the anomaly present- 
 ed by water in its dilatations by change of 
 temperature, and then conclude this part of 
 the subject with some practical applications 
 of the preceding facts. 
 
 The Florentine academicians, and after 
 them Dr Croune, observed, that on cooling 
 in ice and salt, the bulb of a thermometric glass, 
 vessel filled with water, the liquid progres- 
 sively sunk in the stem, till a certain point, 
 after which the further progress of refrigera- 
 tion was accompanied by an ascent of the 
 liquid, indicating expansion of the water. 
 This curious phenomenon was first accurate- 
 ly studied by M. De Luc, who placed the 
 apparent term of greatest density at 40° 
 Fahr., and considered the expansion of wa- 
 ter from that point, to vary with equal 
 amount, by an equal change of temperature, 
 whether of increase or decrease. Having 
 omitted to make the requisite correction for 
 the effect of the expansion of the glass in 
 which the water was contained, it was 
 found afterwards by Sir Charles Blagden 
 and Mr Gilpin, who introduced this correc- 
 tion, that the real term of greatest density was 
 39° F. 
 
 The following Table gives their Experimental results. 
 
 / 
 
 Sp. gravity. 
 
 Bulk of water. 
 
 ^Temperature. 
 
 Rulk of water. 
 
 Sp. gravity. 
 
 
 1.00000 
 
 39° 
 
 1.00000 
 
 
 1 .00000 
 
 J .00000 
 
 38 
 
 40 
 
 1.00000 
 
 1.00000 
 
 0.99999 
 
 1.00001 
 
 37 
 
 41 
 
 1.00001 
 
 0.99999 
 
 0.99998 
 
 1.00002 
 
 36 
 
 42 
 
 1.00002 
 
 0.99998 
 
 0.99996 
 
 1 .00004 
 
 35 
 
 43 
 
 1 .00004 
 
 0.99996 
 
 0.99994 
 
 1 .00006 
 
 34 
 
 44 
 
 1.00006 
 
 0.99994 
 
 0.99991 
 
 1.00008 
 
 S3 
 
 45 
 
 1 .00009 
 
 0.99991 
 
 0.99988 
 
 1.00012 
 
 32 
 
 46 
 
 1.00012 
 
 0.99988 
 
CAL 
 
 CAL 
 
 By weighing a cylinder of copper and of 
 glass in water at different temperatures, the 
 maximum density comes out 40° F. Final- 
 ly Dr Hope, in 1804, published a set of 
 experiments in the Edin. Phil. Trans, in 
 which the complication introduced into the 
 question by the expansion of solids, is very 
 philosophically removed. He shews that 
 xvater exposed in tall cylindrical vessels, to 
 a freezing atmosphere, precipitates to the bot- 
 tom its colder particles, till the temperature 
 of the mass sinks to 39.5° F* after which 
 the colder particles are found at the surface. 
 He varied the form of the experiment by ap- 
 plying a zone of ice, round the top, middle, 
 and bottom of the cylinders ; and in each 
 case, delicate thermometers placed at the 
 surface and bottom of the water, indicated 
 that the temperature 39.5°, coincided with 
 the maximum density. We may therefore 
 regard the point of 40°, adopted by the 
 French, in settling their standard of weights 
 and measures, as sufficiently exact. 
 
 The force with which solids and liquids 
 expand or contract by heat and cold, is so 
 prodigiously great as to overcome the strong- 
 est obstacles. Some years ago it was ob- 
 served at the Conservatoire des arts et metiers 
 at Paris, that the two side walls of a gallery 
 were receding from each other, being pressed 
 outwards by the weight of the roof and floors. 
 Several holes w ere made in each of the walls, 
 opposite to one another, and at equal dis- 
 tances, through which strong Iron bars w ere 
 introduced so as to traverse the chamber. 
 Their ends outside of the wall w ere furnish- 
 ed with thick iron discs, firmlv screwed on. 
 Those were sufficient to retain the walls in 
 their actual position. But to bring them 
 nearer together w ould have surpassed every 
 effort of human strength. All the alternate 
 
 bars of the series were now heated at once bv 
 
 • 
 
 lamps, in consequence of which they were 
 elongated. The exterior discs being thus 
 freed from contact of the walls, permitted 
 them to be advanced farther, on the screwed 
 ends of the bars. On removing the lamps, 
 the bars cooled, contracted, and drew in the 
 opposite w^alls. The other bars became in 
 consequence loose at their extremities, and 
 permitted their end plates to be further 
 screwed on. The first series of bars being 
 again heated, the above process was repeated 
 in each of its steps. By a succession of 
 these experiments they restored the walls to 
 ■ the perpendicular position ; and could easily 
 have reversed their curvature inwards, if 
 they had chosen. The gallery still exists 
 with its bars, to attest the ingenuity of its 
 preserver M. Molard. 
 
 2d, Of the change of state produced in 
 i bodies by caloric, independent of change of 
 composition. The three forms of matter, the 
 solid, liquid, and gaseous, seem immediately 
 referable to the power of heat, modifying, 
 
 balancing, or subduing cohesive attraction. 
 In the article bloiv-pipe , we have shewn that 
 every solid may be liquefied, and many of 
 them, as well as all liquids, may be vaporiz- 
 ed at a certain elevation of temperature. 
 And conversely almost every known liquid 
 may be solidified by the reduction of its tem- 
 perature. If we have not hitherto been able 
 to convert the air and other elastic fluids 
 into liquids or solids, it is probably owing to 
 the limited power we possess over thermo- 
 metric depression. But we know, that by 
 mechanical approximation of their elastic 
 particles, an immense evolution of heat is 
 occasioned, which must convince us that 
 their gaseity is intimately dependent on the 
 operation of that repulsive powder. 
 
 Sulphuric ether, always a liquid in cur 
 climate, if exposed to the rigours of a Siberian 
 winter, w'ould become a solid, and, trans- 
 ported to the torrid zone, would form a per- 
 manent gas. The same transitions are fami- 
 liar to us with regard to water, only its va- 
 porizing point, being much higher, leads us 
 at first to suppose steam an unnatural condi- 
 tion. But by generalizing our ideas, wc 
 learn that there is really no state of bodies 
 which can be called more natural than ano- 
 ther. Solidity, liquidity, the state of va- 
 pours and gases, are only accidents connect- 
 ed with a particular level of temperature. 
 If we pass the easily condensed vapour of 
 nitric acid through a red-hot glass tube, w r e 
 shall convert it into gases which are incon- 
 densable by any degree of cold which we can 
 command. The particles which formed the 
 liquid can no longer join together to repro- 
 duce it, because their distances are changed, 
 and with these have also changed the recipro- 
 cal attractions which united them. 
 
 Were our planet removed much further 
 from the sun, liquids and gases would soli- 
 dify ; were it brought nearer that luminary, 
 the bodies which appear to us the most solid, 
 would be reduced into thin invisible air. We 
 see, then, that the principle of heat, whatever 
 it may be, whether matter or quality, separates 
 the particles of bodies when its energy aug- 
 ments, and suffers them to approach when 
 its power is enfeebled. By extending this 
 view, it has been drawn into a general con- 
 clusion, that this principle was itself the 
 force which maintains the particles of bodies 
 in equilibria against the effort of their reci- 
 procal attraction, which tends continually to 
 bring them together. But although this 
 conclusion be extremely probable, we must 
 remember that it is hypothetical, and goes 
 further than the facts. We see that the force 
 which balances attraction in bodies may be 
 favoured or opposed by the principle of heat, 
 but this does not necessarily prove that these 
 forces are of the same nature. 
 
 1 lie instant ol equilibrium which sepa- 
 rates the solid from the liquid state, deserves 
 
CAL 
 
 CAL 
 
 consideration. Whatever may be the cause 
 and law of the attractions which the particles 
 exercise on one another, the effect which re- 
 sults ought to be modified by their forms. 
 AV hen all the other qualities are equal, a 
 particle which may be cylindrical, for exam- 
 ple, will not exercise the same attraction as a 
 sphere, on a point placed at an equal distance 
 troin its centre of gravity. Thus, in the law 
 of celestial gravitation, the attraction of an 
 ellipsoid on an exterior point, will be stronger 
 in the direction of its smaller than in that of 
 its larger axis, at the same distance from its 
 surface. Now whatever be the law of attrac- 
 tions which holds together the particles of 
 bodies, similar differences must exist. These 
 particles must be attracted more strongly by 
 certain sides than by others. Thence must 
 result differences in the manner of their ar- 
 rangement, when they are sufficiently ap- 
 proximated for their attractions to overcome 
 the repulsive power. This explains to us in 
 a very probable manner, the regular crystal- 
 lization which most solid bodies assume, 
 when they concrete undisturbed. We may 
 easily conceive how the different substance 
 of the particles, as well as their different forms, 
 may produce in crystals all the varieties 
 which we observe. 
 
 The System of the world presents magni- 
 ficent e fleets of this attraction dependent on 
 figure. Such are the phenomena of nuta- 
 tion and the precession of the equinoxes, pro- 
 duced by the attractions of the sun and 
 moon on the flattened spheroid of the earth. 
 These sublime phenomena would not have 
 existed, had the earth been a sphere ; they 
 are connected with its oblateness and rota- 
 tion, in a manner which may be mathemati- 
 cally deduced, and subjected to calculation. 
 
 But the investigation shews, that this part 
 of the attraction dependent on figure, de- 
 creases more rapidly than the principal force. 
 The latter diminishes as the square of the 
 distance ; the part dependent on figure di- 
 minishes as the cube of the distance. Thus 
 also, in the attractions which hold the parts 
 of bodies united, we ought to expect an ana- 
 logous difference to occur. Hence the force 
 of crystallization may be subdued, before the 
 principal attractive force is overcome. When 
 the particles are brought to this distance, 
 they will be indifferent to all the positions 
 which they can assume round their centre 
 of gravity ; this will constitute the liquid 
 condition. Suppose now that the tempera- 
 ture falling, the particles approach slowly to 
 each other, and tend to solidify anew ; then 
 the forces dependent on their figure will 
 come again into play, and in proportion as 
 they increase, the particles solicited by these 
 forces will take movements rouml their 
 centres of gravity. They will turn towards 
 each other their faces of greatest attraction, 
 to arrive finally at the positions which their 
 
 1 3 
 
 crystallization demands. Now according to 
 the figure ol the particles, we may conceive 
 that these movements may react on their 
 centre of gravity, and cause them to approach 
 or recede gradually from each other, till they 
 finally give to their assemblage the volume 
 due to the solid state ; a volume which in 
 certain cases may be greater, and in others 
 smaller, than that which they occupied as 
 liquids. These mechanical considerations 
 thus explain, in the most probable and satis- 
 factory manner, the dilatations and contrac- 
 tions of an irregular kind, which certain li- 
 quids, such as water and mercury, expe- 
 rience, on approaching the term of their 
 congelation. Having given these general 
 views, we may now content ourselves with 
 stating the facts as much as possible in a 
 tabular form. 
 
 TABLE of the Concreting or Congealing 
 Temperatures of various Liquids , by Fah- 
 renheit’s Scale. 
 
 Sulphuric ether, - — 46° 
 
 Liquid ammonia, - — 4G 
 
 Nitric acid, sp. gr. 1.424 — 45.5 
 Sulphuric acid, sp. gr. 1.6415 ■ — 45 
 Mercury, - - — 39 
 
 Nitric acid, sp. gr. 
 
 1.407 
 
 — 30.1 
 
 Sulphuric acid, 
 
 1.8064 ■ 
 
 — 26 
 
 Nitric acid, 
 
 1.3880 ■ 
 
 — 18.1 
 
 Do. Do. 
 
 1.2583 ■ 
 
 — 17.7 
 
 Do. Do. 
 
 1.3290 ■ 
 
 — 2.4 
 
 Brandy, 
 
 - 
 
 — 7.0 
 
 Sulphuric acid, 
 
 1.8376 -f 1. 
 
 Pure prussic acid, 
 
 - 
 
 4 to 5 
 
 Common salt, 25 -|- 
 
 water 75 
 
 4 
 
 Do. 22.2-1- 
 
 do. 77.8 
 
 7.2 
 
 Sal ammoniac, 20 -j- 
 
 do. 80 
 
 8. 
 
 C. salt, 20 -f 
 
 do. 80 
 
 9.5 
 
 Do. 16.1 + 
 
 do. 83.9 
 
 13.5 
 
 Oil of turpentine. 
 
 - 
 
 14. 
 
 Strong wanes, 
 
 
 20 
 
 Rochelle salt, 50 4 - water 50 
 
 21. 
 
 C. salt, 10 4- 
 
 do. 90 
 
 21.5 
 
 Oil of bergamot, 
 
 - 
 
 23 
 
 Blood, 
 
 - 
 
 25 
 
 C. salt, 6.25 
 
 water 93.75 
 
 25.5 
 
 Eps. salts, 41.6 -f- 
 
 do. 58.4 
 
 25.5 
 
 Nitre, 12.5 -f“ 
 
 do. 87.5 
 
 26. 
 
 C. salt, 4.16 4~ 
 
 do. 95.84 
 
 27.5 
 
 Copperas, 4 1 .6 -j- 
 
 do. 58.4 -f 28 
 
 Vinegar, 
 
 - 
 
 28 
 
 Sul. of zinc, 53.3 -4- "'ater 46.7 
 
 28.6 
 
 Milk, 
 
 mm m 
 
 SO 
 
 Water, 
 
 - - 
 
 32 
 
 Olive oil, 
 
 - 
 
 36 
 
 Sulphur and phosphorus, equal parts, 40 
 
 Sulphuric acid, sp. gr 
 
 . 1.741 
 
 42 
 
 Do. Do. 
 
 1.780 
 
 46 
 
 Oil of anise, 
 
 - 
 
 50 
 
 Concentrated acetic acid, 
 
 50 
 
 Tallow, Dr Thomson, 
 
 t 
 
 92 
 
 Phosphorus, 
 
 - 
 
 108 
 
 
CAL 
 
 CAL 
 
 Stearin from hog’s lard, 
 
 109 
 
 Spermaceti, 
 
 112 
 
 Tallow, Nicholson, 
 
 127 
 
 Margaric acid, 
 
 154 
 
 Potassium, - 
 
 156.4 
 
 Yellow wax, 
 
 142 
 
 l)o. Do. 
 
 149 
 
 White wax, 
 
 155 
 
 Sodium, 
 
 194 
 
 Sulphur, Dr Thomson, 
 
 218 
 
 Do. Dr Hope, 
 
 234 
 
 Tin, 
 
 442 
 
 Bismuth, 
 
 47 6 
 
 Lead, - 
 
 612 
 
 Zinc, by Sir H. Davy, 
 
 680 
 
 Do. Brogniart, 
 
 6 98 
 
 Antimony, 
 
 809? 
 
 See Pyrometer for higher heats. 
 
 The solidifying temperature of the bodies 
 above tallow, in the table, is usually called 
 their freezing or congealing point ; and of 
 tallow and the bodies below it, the fusing or 
 melting point. Now, though these tempe- 
 ratures be stated, opposite to some of the 
 articles, to fractions of a thermometric de- 
 gree, it must be observed, that various cir- 
 cumstances modify the concreting point of 
 the liquids, through several degrees ; but the 
 liquefying points of the same bodies, when 
 once solidified, are uniform and fixed, to the 
 preceding temperatures. 
 
 The preliminary remarks which we offer- 
 ed on the forces concerned in the transition 
 from liquidity to solidity, will in some mea- 
 sure explain these variations ; and we shall 
 now illustrate them by some instructive ex- 
 amples. 
 
 If we fill a narrow-mouthed matrass with 
 newly distilled water, and expose it very 
 gradually to a temperature considerably be- 
 low 52°, the liquid water will be observed, 
 by the thermometer left in it, to have sunk 
 10 or 11 degrees below its usual point of 
 congelation. M. Gay Lussac, by covering 
 the surface of the water with oil, has caused 
 it to cool 21^ degrees Fahr. below the ordi- 
 nary freezing temperature. Its volume at 
 the same time expanded as much as if it 
 had been heated 21^ degrees above 32°. 
 According to Sir Charles Blagden, to whom 
 the first of these two observations belongs, 
 its dilatation may amount to 1 - 7th of the 
 total enlargement, which it receives by soli- 
 difying. Absolute repose of the liquid par- 
 ticles is not necessary to ensure the above 
 phenomenon, for Sir Charles stirred water 
 at 21° without causing it to freeze, but the 
 least vibration of their mass, or the applica- 
 tion of icy spicuhe, by the atmosphere, or 
 the hand, determines an instantaneous con- 
 gelation. 
 
 We may remark here, that the dilatation 
 of’ the water increasing as it cools, but to a less 
 extent than when it concretes, is a proof that 
 its constituent particles, in obedience to the 
 
 cooling process, turn their poles more and 
 more towards the position of the maximum 
 attraction, which constitutes their solid state. 
 But this position may be determined instan- 
 taneously by the ready formed aqueous solid, 
 the particles of which presenting themselves 
 to those of the liquid, by their sides of greatest 
 attraction, will compel them to turn into simi- 
 lar positions. Then the particles of the liquid 
 first reverted will act on their neighbours 
 like the exterior crystal, and thus from point 
 to point the movement will be propagated 
 through the whole mass, till all be congeal- 
 ed. The vibratory movements act by throw- 
 ing the particles, into positions favourable 
 for their mutual attraction. 
 
 The very same phenomena occur with sa- 
 line solutions. If a hot saturated solution 
 of Glauber’s salt be cooled to 50° under a 
 film of oil, it will remain liquid, and will 
 bear to be moved about in the hand without 
 any change ; but if the phial containing it 
 be placed on a vibrating table, crystalliza- 
 tion will instantly take place. In a paper 
 on saline crystallization which I published 
 in the 9th number of the Journal of Science, 
 
 I gave the following illustration of the above 
 phenomena. “ The effect of mechanical 
 disturbance in determining crystallization, is 
 illustrated by the symmetrical disposition of 
 particles of dust and iron, by electricity and 
 magnetism. Strew these upon a plane, and 
 present magnetic and electric forces at a 
 certain distance from it, no effect will be 
 produced. Communicate to the plane a vi- 
 brating movement ; the particles, at the in- 
 stant of being liberated from the friction of 
 the surface, will arrange themselves accord- 
 ing to the laws of their respective magnetic 
 or electric attractions. The water of solu- 
 tion in counteracting solidity, not only re- 
 moves the particles to distances beyond the 
 sphere of mutual attraction, but probably 
 also inverts their attracting poles.” Per- 
 haps the term avert would be more appro- 
 priate to liquidity, to denote an obliquity of 
 direction in the attracting poles ; and revert 
 might be applied to gaseity, when a repul- 
 sive state succeeds to the feebly attractive 
 powers of liquid particles. 
 
 The above table presents some interesting 
 particulars relative to the acids. I have ex- 
 pressed their strengths, by specific gravity, 
 from my tables of the acids, instead of by 
 the quantity of marble which 1000 grains of 
 them could dissolve, in the original statement 
 of Mr Cavendish. Under the heads of ni- 
 tric acid and equivalent, some observations 
 will be found on these peculiarities with re- 
 gard to congelation. We see that common 
 salt possesses the greatest efficacy in coun- 
 teracting the congelation of water; and next 
 to it, sal ammoniac. Mr Crighton of Glas- 
 gow, whose accuracy of observation is well 
 known, has remarked, that when a mass of 
 
CAL 
 
 melted bismuth cools in the air, its tempera- 
 ture falls regularly to 468°, from which 
 term it however instantly springs up to 476°, 
 at which point it remains till the whole he 
 consolidated. Tin in like manner sinks and 
 then rises 4 degrees ; while melted lead, in 
 cooling, becomes stationary whenever it des- 
 cends to 6 1 2°. We shall presently find the 
 probable cause of these curious phenomena. 
 
 Water, all crystallizable solutions, and the 
 three metals, cast-iron, bismuth, and anti- 
 mony, expand considerably in volume, at 
 the instant of solidification. The greatest 
 obstacles cannot resist the exertion of this 
 expansive force. Thus glass bottles, trunks 
 of trees, iron and lead pipes, even mountain 
 rocks, are burst by the dilatation of the wa- 
 ter in their cavities, when it is converted 
 into ice. In the same way our pavements 
 are raised in winter. The beneficial opera- 
 tion of this cause is exemplified in the com- 
 minution or loosening the texture of dense 
 clay soils, by the winter’s frost, whereby the 
 delicate fibres of plants can easily penetrate 
 them. Major Williams of Quebec, burst 
 bombs, which were filled with water and plug- 
 ged up, by exposing them to a freezing cold. 
 
 There is an important circumstance occurs 
 in the preceding experiments on the sudden 
 congelation of a body kept liquid below its 
 usual congealing temperature, to which we 
 must now advert. The mass, at the mo- 
 ment its crystallization commences, rises in 
 temperature to the term marked in the pre- 
 ceding table, whatever number of degrees it 
 may have previously sunk below' it. Sup- 
 pose a globe of water suspended in an at- 
 mosphere at 21° F. ; the liquid will cool 
 and remain stationary at this temperature, 
 till vibration of the vessel, or contact of a 
 spiculaof ice, determines its concretion, w hen 
 it instantly becomes 1 1 degrees hotter than 
 the surrounding medium. We owe the ex- 
 planation of this fact, and its extension to 
 many analogous chemical phenomena, to the 
 sagacity of Dr Black. His truly philoso- 
 phical mind w'as particularly struck by the 
 slowness with which a mass of ice liquefies 
 when placed in a genial atmosphere. A 
 lump of ice at 22° freely suspended in a 
 room heated to 50°, which will rise to 32° 
 in 5 minutes, will take 14 times 5, or 70 mi- 
 nutes, to melt into water, whose temperature 
 will be only 32°. Dr Black suspended in 
 an apartment two glass globes of the same 
 size alongside of each other, one of which 
 w'as filled wfitli ice at 32°, the other with 
 water at .3.5°. In half an hour the water 
 had risen to 40°; but it took 10^ hours to 
 liquefy the ice and heat the resulting water 
 to 40°. Both these experiments concur 
 therefore in shewing that the fusion of ice is 
 accompanied with the expenditure of 140 
 degrees of calorific energy, which have no 
 • effect on the thermometer. For the first ex- 
 
 CAL 
 
 periraent tells us that 10 degrees of heat en- 
 tered the ice in the space of 5 minutes, and 
 yet 1 4 times that period passed in its lique- 
 faction. The second experiment shews that 
 7 degrees of heat entered the globes in half 
 an hour ; but 21 half hours w r ere required 
 for the fusion of the ice, and for heating of 
 its water to 40°. If from the product of 7 
 into 21 = 147, we subtract the 7 degrees 
 w hich the water was above 33, we have 1 40 as 
 before. But the most simple and decisive ex- 
 periment is to mingle a pound of ice in small 
 fragments with a pound of water at 1 72 u . 
 Its liquefaction is instantly accomplished, 
 but the temperature of the mixture is only 
 32°. Therefore 140° of heat seem to have 
 disappeared. Had we mixed a pound of 
 ice-cold water w'ith a pound of water at 
 172°, the resulting temperature would have 
 been 102°, proving that the 70° which had 
 left the hotter portion, were manifestly 
 transferred to that which w'as cooler. The 
 converse of the preceding experiments may 
 also be demonstrated ; for in suspending a 
 flask of water, at 55° for example, in an at- 
 mosphere at 20°, if it cool to 32° in 3 mi- 
 nutes, it will take 1 40 minutes to be con- 
 verted into ice of 32° ; because the heat 
 emanating at the rate of 1° per minute, it 
 will require that time for 140° to escape. 
 The latter experiment, however, from the 
 inferior conducting power of ice, and the 
 uncertainty when all is frozen, is not suscep- 
 tible of the precision which the one imme- 
 diately preceding admits. The tenth of 140 
 is obviously 14 ; and hence we may infer 
 that when a certain quantity of water, cooled 
 to 22°, or 10° below' 32°, is suddenly caused 
 to congeal, 1-1 4th of the weight will become 
 solid. 
 
 We can now' understand how the thaw’ 
 which supervenes after an intense frost, 
 should so slowly melt the wreaths of snow, 
 and beds of ice, a phenomenon observable in 
 these latitudes from the origin of time, but 
 whose explanation was reserved for Dr 
 Black. Indeed, had the transition of water 
 from its solid into its liquid state not been 
 accompanied by this great change in its re- 
 lation to heat, every thaw would have occa- 
 sioned a frightful inundation, and a single 
 night’s frost w'ould have solidified our rivers 
 and lakes. Neither animal nor vegetable 
 life could have subsisted under such sudden 
 and violent transitions. Mr Cavendish, who 
 had discovered the above fact, before lie 
 knew of its being inculcated by Dr Black 
 in his lectures, states the quantity ot heat 
 which ice seems to absorb in its fusion to be 
 1 50 ° ; Lavoisier and Laplace make it 1 .35° ; 
 a number probably correct, from the pains 
 they took in constructing, on this basis, t licit* 
 calorimeter. The fixity of the melting 
 points of bodies exposed to a strong heat 
 need no longer surprise us; because till the 
 
CAL 
 
 CAL 
 
 ivhole mass be melted, the heat incessantly 
 introduced, is wholly expended in constitut- 
 ing liquidity, without increasing the tempe- 
 rature. We can also comprehend how a li- 
 quid metal, a saline solution, or water, should 
 in the career of refrigeration, sink below the 
 term of its congelation, and suddenly re- 
 mount to it. Those substances, in which 
 the attractive force that reverts the poles into 
 the solid arrangement acts most slowly or 
 feebly, will most readily permit this depres- 
 sion of temperature, before liquidity begins 
 to cease. Thus bismuth, a brittle metal, 
 takes 8° of cooling below its melting point, 
 to determine its solidification ; tin takes 4°, 
 but lead passes so readily into the solid ar- 
 rangement that its cooling is at once arrested 
 at its fusing temperature. In illustration of 
 this statement, we may remark, that the par- 
 ticles of bismuth and tin lose their cohesive 
 attraction in a great measure long before 
 they are heated to the melting point ; though 
 lead continues relatively cohesive till it be- 
 gins to melt. Tin may be easily pulveriz- 
 ed at a moderate elevation of temperature, 
 and bismuth in its cold state. The in- 
 stant, however, that these two metals, when 
 melted, begin to congeal, they rise to the 
 proper fusing temperature, because the calo- 
 ric of liquidity is then disengaged. 
 
 Drs Irvine, father and son, to both of 
 whom the science of heat is deeply indebted, 
 investigated the proportion of caloric disen- 
 gaged by several other bodies in their pas- 
 sage from the liquid to the solid state, and 
 obtained the following results : 
 
 
 Caloric of 
 
 Do. referred to the 
 
 
 liquidity. 
 
 sp. heat of water. 
 
 Sulphur, 
 
 148.68 
 
 27.14 
 
 Spermaceti, 
 
 145. 
 
 
 Lead, 
 
 162. 
 
 5.6 
 
 Bees w r ax, 
 
 175. 
 
 
 Zinc, 
 
 493. 
 
 48.3 
 
 Tin, 
 
 500. 
 
 33. 
 
 Bismuth, 
 
 550. 
 
 23.25 
 
 The quantities in the second column are 
 the degrees by which the temperatures of 
 each of the bodies in its solid state, would 
 have been raised by the heat disengaged dur- 
 ing its concretion. An exception must be 
 made for wax and spermaceti ; which are 
 supposed to be in the finid state, when indi- 
 cating the above elevation. Dr Black ima- 
 gined that the new relation to heat which 
 solids acquire by liquefaction, was derived 
 Irom the absorption, and intimate combina- 
 tion of a portion of that fluid, which thus 
 employing all its repulsive energies in sub- 
 duing the stubborn force of cohesion, ceased 
 to have any thermometric tension, or to be 
 perceptible to our senses, lie termed this 
 supposed quantity. of caloric, their latent 
 heat ; a term very convenient and proper, 
 while we regard it simply as expressing the 
 
 relation which the calorific agent bears to 
 the same body in its fluid and solid states. 
 To the presence of a certain portion of la- 
 tent or combined heat in solids, Dr Black 
 ascribed their peculiar degrees of softness, 
 toughness, malleability. Thus we know 
 that the condensation of a metal by t lie 
 hammer, or under the die, never fails to ren- 
 der it brittle, while, at the same time, heat 
 is disengaged. Berthollet subjected equal 
 pieces of copper and silver to repeated 
 strokes of a fly press. The elevation of their 
 temperature, which was considerable by tho 
 first blow, diminished greatly at each suc- 
 ceeding one, and became insensible when- 
 ever the condensation of volume ceased. 
 The copper suffered greatest condensation, 
 and evolved most heat. Here the analogy 
 of a sponge, yielding its water to pressure, 
 has been employed to illustrate the mate- 
 riality of heat supposed deducible from these 
 experimehts. But the phenomenon may be 
 referred to the intestine actions between the 
 ultimate particles which must accompany 
 the violent dislocation of their attracting 
 poles. The cohesiveness of the metal is 
 greatly impaired. 
 
 The enlarged capacity for heat, to use 
 the popular expression, which solids acquire 
 in liquefying, enables us to understand 
 and apply the process of artificial cooling, 
 by what are called freezing mixtures. When 
 two solids, such as ice and salt, by their 
 reciprocal affinity, give birth to a solid, 
 then a very great demand for heat is 
 made on the surrounding bodies, or they are 
 powerfully stripped of their heat, and their 
 temperature sinks of course. Pulverulent 
 snow and salt mixed at 52°, will produce a 
 depression of the thermometer plunged into 
 them of about 38°. The more rapid the 
 liquefaction, the greater the cold. Hence 
 the paradoxical experiment of setting a pan 
 on the fire containing the above freez- 
 ing mixture with a small vessel of water 
 plunged into it. In a few seconds the wa- 
 ter will be found to be frozen. The solu- 
 tion of all crystallized salts is attended with 
 a depression of temperature, which increases 
 generally with the solubility of the salt. 
 
 The Table of Freezing Mixtures in the 
 Appendix, presents a copious choice of such 
 means of refrigeration. Equal parts of sal 
 ammoniac and nitre, in powder, form the 
 most convenient mixture for procuring mo- 
 derate refrigeration; because the water of so- 
 lution being afterwards removed by evapora- 
 tion, the pulverized salts are equally effica- 
 cious as at first. Under the articles Cli- 
 mate, Congelation, Temperature, Ther- 
 mometer, and Water, some additional facts 
 will be found on the present subject. 
 
 But the diminution of temperature by 
 liquefaction is not confined to saline bodies. 
 When a solid amalgam of bismuth, and a 
 
CAL 
 
 CAL 
 
 solid amalgam of lead, are mixed together, 
 they become fluid, and the thermometer sinks 
 during the time of their action. 
 
 The equilibrium between the attractive 
 and repulsive forces which constitutes the 
 liquid condition ot bodies, is totally subverted 
 by a definite elevation of temperature, when 
 the external compressing forces do not vary. 
 The transition from the liquid state into 
 that of elastic fluidity is usually accompa- 
 nied with certain explosive movements, term- 
 ed ebullition. The peculiar temperatures at 
 which different liquids undergo this change 
 is therefore called their boiling point; and 
 the resulting elastic fluid is termed a va- 
 pour, to distinguish it from a gas, a sub- 
 stance permanently elastic, and not con- 
 densable as vapours are, by moderate de- 
 grees of refrigeration. It is evident that 
 when the attractive forces, however fee- 
 ble in a liquid, are supplanted by strong 
 repulsive powers, the distances between the 
 particles must be greatly enlarged. Thus a 
 cubic inch of water at 40° becomes a cubic 
 inch and l-25th on the verge of 212°, and 
 at 212° it is converted into 1600 cubic 
 inches of steam. The existence of this steam 
 indicates a balance between its elastic force 
 and the pressure of the atmosphere. If the 
 latter be increased beyond its average quan- 
 tity by natural or artificial means, then the 
 elasticity of the steam will be partially over- 
 come, and a portion of it will return to 
 the liquid condition. And conversely, if the 
 pressure of the air be less than its mean 
 quantity, liquids will assume elastic fluidity 
 by a less intensity of calorific repulsion, or 
 at a lower thermometric tension. Professor 
 Robison performed a set of ingenious ex- 
 periments, which appear to prove, that when 
 the atmospheric pressure is wholly with- 
 drawn, that is, in vacuo, liquids become elas- 
 tic fluids 124° below their usual boiling 
 points. Hence water in vacuo will boil and 
 distil over at 212° — 124 = 88° Fahr. 
 This principle was long ago employed by 
 the celebrated Watt in his researches on the 
 steam engine, and has been recently applied 
 in a very ingenious way by Mr Tritton in 
 his patent still, (Phil. Mag. vol. 51.), and 
 Mr Barry, in his evaporator for vegetable 
 extracts, (Med. Chir. Trans, vol. 10). See 
 Alcohol, Distillation, Extract. 
 
 On the same principle of the boiling, vary- 
 ing with the atmospheric pressure, the Rev. 
 Mr Wollaston has constructed his beauti- 
 ful thermometric barometer for measuring 
 heights. He finds that a difference of 1° 
 in the boiling point of water is occasioned 
 by a difference of 0.589 of an inch on the 
 barometer. This corresponds to nearly 520 
 feet of difference of elevation. By using 
 the judicious directions which he has given, 
 
 the elevation of a place may thus be rigor- 
 ously determined, and with great conveni- 
 ence. The whole apparatus, weighing 20 
 ounces, packs in a cylindrical tin case, 2 
 inches dinmeter, and 10 inches long. 
 
 When a vessel containing water is placed 
 over a flame, a hissing sound or simmering 
 is soon perceived. This is ascribed to 
 the vibrations occasioned by the successive 
 vaporization and condensation of the parti- 
 cles in immediate contact with the bottom of 
 the vessel. The sound becomes louder as 
 the liquid is heated, and terminates in ebul- 
 lition. The temperature becomes now of a 
 sudden stationary when the vessel is open, 
 however rapidly it rose before, and whatever 
 force of fire be applied. Dr Black set a tin 
 cup full of water at 50°, on a red-hot iron 
 plate. In four minutes it reached the boil- 
 ing point, and in twenty minutes it was all 
 boiled off*. From 50° to 212°, the eleva- 
 tion is 162°; which interval, divided by 4, 
 gives 40^° of heat, which entered the tin cup 
 per minute. Hence 20 minutes, or 5 times 
 4 multiplied into 40^ =810, will represent 
 the quantity of heat that passed into the 
 boiling water to convert it into a vapour. 
 But the temperature of this is still only 212°. 
 Hence, according to Black, these 810° have 
 been expended solely in giving elastic ten- 
 sion, or, according to Irvine, in supplying 
 the vastly increased capacity of the aeriform 
 state ; and therefore they may be denomi- 
 nated latent heat, being insensible to the 
 thermometer. The more exact experiments of 
 Mr Watt have shewn, that whatever period be 
 assigned for the heating of a mass of water 
 from 50° to 212°, 6 times this period is re- 
 quisite with a uniform heat for its total va- 
 porization. But 6 X 162° = 972 = the 
 latent heat of steam ; a result which accords 
 with my experiments made in a different 
 way, as will be presently shewn. Every 
 attentive operator must have observed the 
 greater explosive violence and apparent diffi- 
 culty of the ebullition of water exposed to a 
 similar heat in glass, than in metallic ves- 
 sels. M. Gay Lussac has studied this sub- 
 ject with his characteristic sagacity. He 
 discovered that water boiling in a glass ves- 
 sel has a temperature of 214.2°, and in a tin 
 vessel contiguous to it, of only 212°. A few 
 particles of pounded glass thrown into the for- 
 mer vessel, reduces the thermometer plung- 
 ed in it to 212.6, and iron filings to 212°. 
 When the flame is withdrawn for a few se- 
 conds from under a glass vessel of boiling 
 water, the ebullition will recommence on 
 throwing in a pinch of iron filings. 
 
 Professors Munche and Gmelin of Heidel- 
 berg have extended these researches, and 
 given the curious results as to the boiling 
 points, expressed in the. following table : — 
 
CAL 
 
 CAL 
 
 Substance of the vessels. 
 
 Ther. 
 
 touching 
 
 bottom. 
 
 Do. \ inch 
 below sur- 
 face of the 
 water. 
 
 Silver, 
 
 211.775° 
 
 211. 55° 
 
 Platina, 
 
 211.775 
 
 210.875 
 
 Copper, 
 
 212.900 
 
 212.225 
 
 Tinned iron, 
 
 213. 
 
 24 
 
 211. 66 
 
 Marble, 
 
 212. 
 
 10 
 
 21 1. 66 
 
 Lead, 
 
 212. 
 
 45 
 
 211.775 
 
 Tin, 
 
 212. 
 
 7 
 
 211.775 
 
 Porcelain, 
 
 212. 
 
 1 
 
 211.900 
 
 White glass, 
 
 212. 
 
 7 
 
 212. 00 
 
 Green glass, 
 
 213. 
 
 8 
 
 213. 35 
 
 Ditto, 
 
 212. 
 
 7 
 
 212. 00 
 
 Delft ware, 
 
 213. 
 
 8 
 
 212. 7 
 
 Common earthen ware, 
 
 213. 
 
 8 
 
 212. 45 
 
 It is difficult to reconcile these variations 
 to the results of M. Gay Lussac. “ The 
 vapour formed at the surface of a liquid,” 
 lie remarks, “ may be in equilibria with the 
 atmospheric pressure ; while the interior por- 
 tion may acquire a greater degree of heat 
 than that of the real boiling point, provided 
 the fluid be enclosed in a vessel, and heated 
 at the bottom. In this case, the adhesion of 
 the fluid to the vessel may be considered as 
 analogous in its action to viscidity, in raising 
 the temperature of ebullition. On this 
 principle we explain the sudden starts which 
 sometimes take place in the boiling of fluids. 
 This frequently occurs to a great degree in 
 distilling sulphuric acid, by which the ves- 
 sels are not unfrequcntly broken when they 
 are of glass. This evil may be effectually 
 obviated by putting into the retort some 
 small pieces of platina wire, when the sud- 
 den disengagement of gas will be prevented, 
 and consequently the vessels not be liable to 
 be broken .” — Annales de C/iimie , March 
 1818. See my remarks on this subject 
 under the Distillation of Sulphuric Acid, 
 extracted from the Journal of Science, Oc- 
 tober 1817. If we throw a piece of paper, 
 a crust of bread, or a powder, into a liquid 
 slightly impregnated with cafbonic acid, its 
 evolution will be determined. See some 
 curious observations by M. Thenard under 
 our articles Oxygenized Nitric Acid, or 
 Oxygenized Water. In a similar manner, 
 the asperities of the surface of a glass or 
 other vessel, act like points in electricity, in 
 throwing off gas or vapour present in the 
 liquid which it contains. 
 
 In all the examples of the preceding ta- 
 ble, the temperature is greater at the bottom 
 than near the surface of the liquid ; and the 
 specific differences must be ascribed to the 
 attractive force of the vessel to water, and its 
 conduction of heat. We must thus try to 
 explain why tinned iron gives a temperature 
 to boiling water in contact with it, 1.67 de- 
 
 grees higher than silver and platina. Be- 
 tween water, and iron tin or lead, there are 
 reciprocal relations at elevated temperatures, 
 which do not apparently exist with regard 
 to silver and platina. 
 
 The following is a tabular view of the 
 boiling points by Fahrenheit’s scale of the 
 most important liquids, under a mean baro- 
 metrical pressure of thirty inches : — 
 
 Foiling points. 
 
 Ether, sp. gr. 
 
 0.7 565 at 4 8°. G. 
 
 Lussac, 100° 
 
 Carburet of sulphur, 
 
 do. 
 
 1 15 
 
 Alcohol, sp. 
 
 gr. 0. 8 1 5 Ure, 1 75.5 
 
 Nitric acid, 
 
 1.500 Dalton, 
 
 210 
 
 Water, 
 
 - - - 
 
 - 
 
 212 
 
 Saturated sol. of Glaub. salt, 
 
 Biot, 
 
 2 1 5s~ 
 
 Do. do. 
 
 sugar of lead, 
 
 do. 
 
 215| 
 
 Do. 
 
 sea salt, 
 
 do. 
 
 224£- 
 
 Muriate of lime 2 -4- water 1 
 
 Ure, 
 
 250 
 
 Do. 
 
 55.5 -j- do. 64.5 
 
 do. 
 
 255 
 
 Do. 
 
 40.5 -4- do. 59.5 
 
 do. 
 
 240 
 
 Muriatic acid, 1.094 
 
 Dalton, 
 
 232 
 
 Do. 
 
 1.127 
 
 do. 
 
 222 
 
 Do. 
 
 1.047 
 
 do. 
 
 222 
 
 Nitric acid, 
 
 1.45 
 
 do. 
 
 240 
 
 Do. 
 
 1.42 
 
 do. 
 
 248 
 
 Do. 
 
 1.40 
 
 do. 
 
 247 
 
 Do. 
 
 1.85 
 
 do. 
 
 242 
 
 Do. 
 
 1.50 
 
 do. 
 
 256 
 
 Do. 
 
 1.16 
 
 do. 
 
 220 
 
 Rectified petroleum, 
 
 Ure, 
 
 506 
 
 Oil of turpentine, 
 
 do. 
 
 516 
 
 Sulph. acid, 
 
 sp. gr. 1 .50 -j- 
 
 Dalton, 
 
 240 
 
 Do. 
 
 1.408 
 
 do. 
 
 260 
 
 Do. 
 
 1 .520 
 
 do. 
 
 290 
 
 Do. 
 
 1.650 
 
 do. 
 
 550 
 
 Do. 
 
 1.670 
 
 do. 
 
 560 
 
 Do. 
 
 1.699 
 
 do. 
 
 574 
 
 Do. 
 
 1.750 
 
 do. 
 
 591 
 
 Do. 
 
 1.780 
 
 do. 
 
 455 
 
 Do. 
 
 1.810 
 
 do. 
 
 475 
 
 Do. 
 
 1.819 
 
 do. 
 
 487 
 
 Do. 
 
 1.827 
 
 do. 
 
 501 
 
 Do. 
 
 1 .855 
 
 do. 
 
 515 
 
 Do. 
 
 1.842 
 
 do. 
 
 545 
 
 Do. 
 
 1.847 
 
 do. 
 
 575 
 
 Do. 
 
 1.848 
 
 do. 
 
 590 
 
 Do. 
 
 1.849 
 
 do. 
 
 605 
 
 Do. 
 
 1.850 
 
 do. 
 
 620 
 
 Do. 
 
 1.848 
 
 Ure, 
 
 600 
 
 Phosphorus, 
 
 - 
 
 554 
 
 Sulphur, 
 
 - 
 
 - 
 
 570 
 
 Linseed oil. 
 
 > 
 
 - 
 
 640 ? 
 
 Mercury, (Dulong, 662°), 
 
 - 
 
 656 
 
 These liquids emit vapours, which, at their 
 respective boiling points, balance a pressure 
 of the atmosphere, equivalent to thirty verti- 
 cal inches of mercury. I5ut at inferior tem- 
 peratures they yield vapours of inferior elas- 
 tic power. It is thus that the vapour of 
 quicksilver rises into the vacuum of the ba- 
 rometer tube ; as is seen particularly in warm 
 climates, by the mercurial dew on the glass 
 
CAL 
 
 CAL 
 
 at its summit. Hence aqueous moisture ad- 
 hering to the mercury, causes it to fall below 
 the true barometer level, by a quantity pro- 
 portional to the temperature. The determi- 
 nation of the elastic force of vapours, in con- 
 tact with their respective liquids, at different 
 temperatures, has been the subject of many ex- 
 periments. The method of measuring their 
 elasticities, described in my paper on Heat, 
 seems convenient, and susceptibleof precision. 
 
 A glass tube about j of an inch internal 
 diameter, and 6 feet long, is sealed at one 
 end, and bent with a round curvature in the 
 middle, into the form of a syphon, with its 
 two legs parallel, and about c 2\ inches asun- 
 der. A rectangular piece of cork is adapted 
 to the interval between the legs, and fixed 
 firmly by twine, about 6 inches from the 
 ends of the syphon. Dry mercury is now 
 introduced, so as to fill the sealed leg, and 
 the bottom of the curvature. On suspend- 
 ing this syphon barometer in a vertical di- 
 rection, by the cork, the level of the mercury 
 will take a position in each of the legs, cor- 
 responding to the pressure of the atmos- 
 phere. The difference is of course the true 
 height of the barometer at the time, which 
 may be measured by the application of a se- 
 parate scale of inches and tenths. Fix 
 rings of fine platinum wire round the tube at 
 the two levels of the mercury. Introduce 
 now into the tube a few drops of distilled 
 water, recently boiled, and pass them up 
 through the mercury. The vapour rising 
 from the water will depress the level of the 
 mercury in the sealed leg, and raise it in the 
 open leg, by a quantity equal in each to one- 
 half of the real depression. To measure 
 distinctly this difference of level with minute 
 accuracy, would be difficult ; but the total 
 depression, which is the quantity sought, 
 may be readily found, by pouring mercury 
 in a slender stream into the open leg, till the 
 surface of the mercury in the sealed leg be- 
 comes once more a tangent to the platina 
 ring, which is shewn by a delicate film of 
 light, as in the mountain barometer. The 
 vertical column of mercurv above the lower 
 initial level being measured, it represents 
 precisely the clastic force of the vapour, 
 since that altitude of mercury was required 
 to overcome the elasticity of the vapour. The 
 whole object now is to apply a regulated heat 
 to the upper portion of the sealed leg, from 
 an inch below the mercurial level, to its 
 summit. This is easily accomplished, by 
 passing it through a perforated cork into an 
 inverted phial, 5 inches diameter and 7 
 long, whose bottom has been previously 
 cracked off by a hot iron. Or a phial may 
 be made on purpose. V hen the tapering 
 elastic cork is now strongly pressed into the 
 mouth of the bottle, it renders it perfectly 
 water-tight-. By inclining the syphon, we 
 remove a little of the mercury, so that when 
 
 reverted, the level in the lower leg may 
 nearly coincide with the ring. Having then 
 suspended it in the vertical position from a 
 high frame, or the roof of an apartment, we 
 introduce water at 32° into the cylindrical 
 glass vessel. When its central tube, against 
 the side of which the bulb of a delicate ther- 
 mometer rests, acquires the temperature of 
 the surrounding medium, mercury is slowlv 
 added to the open leg, till the primitive level 
 is restored at the upper platina ring. The 
 column of mercury above the ring in the open 
 leg, is equivalent to the force of aqueous 
 vapour at 32°. The effect of lower tem- 
 peratures may be examined, by putting saline 
 freezing mixtures in the cylinder. To pro- 
 cure measures of elastic force at higher tem- 
 peratures, two feeble Argand flames are made 
 to send up heated air, on the opposite shoul- 
 ders of the cylinder. By adjusting the 
 flames, and agitating the liquid, very uniform 
 temperatures may be given to the tube in 
 the axis. At every 5° or 10° of elevation, 
 we make a measurement, by pouring mer- 
 cury into the open leg, till the primitive 
 level is restored in the other. 
 
 For temperatures above 212°, I employ the 
 same plan of apparatus, slightly modified. The 
 sealed leg of the syphon has a length of 6 or 
 7 inches, while the open leg is 10 or 12 feet 
 long, secured in the groove of a graduated 
 wooden prism. The initial level becomes 
 212° when the mercury in each leg is in a 
 horizontal plane, and the heat is now com- 
 municated through the medium of oil. If the 
 bending of the tube, he made to an angle of 
 about 35° from parallelism of the legs, a tu- 
 bulated globular receiver becomes a conveni- 
 ent vessel for holding the oil. The tapering 
 cork through which the sealed end of the 
 syphon is passed, being thrust into the taper- 
 ing mouth of the receiver, remains perfectly 
 tight at all higher temperatures, being pro- 
 gressively swelled with the heat. One who 
 has not made such trials, may be disposed to 
 cavil at the probable tightness of such a con- 
 trivance, but I who have used it in experi- 
 ments for many months together, know that 
 only extreme awkwardness in the operator, 
 can occasion the dropping out of oil heated 
 up to even 320° of Fahrenheit. The tubu- 
 lure of the receiver admits the thermometer. 
 The Tables of Vapour, in the Appendix, ex- 
 hibit the results of some carefully conducted 
 
 experiments. 
 
 In my attempts to find some ratio which 
 would connect the above elasticitiesof aqueous 
 vapour with the temperatures, the following 
 rule occurred to me : 
 
 “The elastic force at 212° = 50 being 
 divided by 1.23, will give the force for 10° 
 below; this quotient divided by 1.24, will 
 give that 10° lower, and so on progressively. 
 To obtain the forces above 212°, we have 
 :rely to multiply 30 by the ratio 1.23 for 
 
 me 
 
CAL 
 
 CAL 
 
 the force at 222° ; this product by 1.22 for 
 that at 232°, this last product by 1.21 for 
 the force at 242°, aud thus for each succes- 
 sive interval of 10° above the boiling point.” 
 The following modification ot the same rule 
 gives more accurate results. “ Let r = the 
 mean ratio between that of 210° and the 
 given temperature ; n = the number of 
 terms (each of 10°) distant from 210° ; F = 
 the elastic force of steam in inches of mer- 
 cury. Then Log. of F = Log. 28.9 n 
 Log. r ; the positive sign being used above, 
 the negative below 210°.” I have investi- 
 gated also simple ratios, which express the 
 connexion between the temperature and elas- 
 ticity of the vapours of alcohol, ether, petro- 
 leum, and oil of turpentine, for which I 
 must refer to the paper itself. 
 
 Mr W. Creighton of Soho communicated 
 in March 1819 to the Philosophical Ma- 
 gazine, the following ingenious formula 
 for aqueous vapour. “ Let the degrees of 
 Fahrenheit 85 = D, and the correspond- 
 ing force of steam in inches of mercury — 
 0. 09 = I. Then Log. D — 2.226 79X6 = 
 Log. I. 
 
 Example. 
 
 212°+85=297Log.=2.47276 
 
 2.22679 constant 
 
 number. 
 
 0.24579 
 X 6 
 
 Log. 1.47582=29.91=1 
 -J-0.09 
 
 Inches 30.00 D 
 
 Tlve above specific gravities are esti- 
 mated under a barometric pressure of 29.92 
 inches. 
 
 M. Gay Lussac has remarked, that when 
 ■a liquid combination of alcohol and water, 
 or alcohol and ether, is converted into va- 
 pour at 212° Fahr. or 100 cent., the volume 
 is exactly the sum of what their separate 
 volumes would have produced ; so that the 
 condensation by chemical action in the liquid 
 state, ceases to operate in the gaseous. An 
 equal volume of carburet of sulphur and ab- 
 solute alcohol, at their respective boiling 
 points of 173° and 126°, is said to yield 
 each an equal quantity of vapour of the 
 same density,. A more explicit statement 
 
 He then gives a satisfactory tabular view of 
 the near correspondences between the results 
 of his formula, and my experiments. 
 
 By determining experimentally the volume 
 of vapour which a given volume of liquid 
 can produce at 212°, M. Gay Lussac has 
 happily solved the very difficult problem of 
 the specific gravity of vapours. He took a 
 spherule of thin glass, with a short capillary 
 stem, and of a known weight. He filled it 
 with the peculiar liquid, hermetically sealed 
 the orifice, and weighed it. Deducting from 
 its whole weight the known weight of the 
 spherule, he knew the weight, and from its 
 sp. gravity the bulk of the liquid. He filled 
 a tall graduated glass receiver, capable of 
 holding about three pints, with mercury, in- 
 verted it in a basin, and let up the spherule. 
 The receiver was now surrounded by a bot- 
 tomless cylinder, which rested at its lower 
 edge in the mercury of the basin. The in- 
 terval between the two cylinders was filled 
 with water. Heat was applied by means of 
 a convenient bath, till the water and the in- 
 cluded mercury assumed the temperature of 
 212°. The expansible liquid had ere this 
 burst the spherule, expanded into vapour, 
 and depressed the mercury. The height of 
 the quicksilver column in the graduated cy- 
 linder above the level of the basin, being ob- 
 served, it was easy to calculate the volume of 
 the incumbent vapour. The quantity of 
 liquid used was always so small, that the 
 whole of it was converted into vapour. 
 
 The following exhibits the specific gravi- 
 ties as determined by the above method : 
 
 1. Boiling point, Fahr. 
 
 212 ° 
 
 79.7 
 173 
 96 
 148 
 316 
 116 
 
 Thenard, 52 
 
 has been promised, and is perhaps required 
 on this curious subject. 
 
 It appears, that a volume of water at 40° 
 forms 1694 volumes of steam at 2 1 The 
 subsequent increase of the volume of steam, 
 and of other vapours, out of the contact of 
 their respective liquids, we formerly stated 
 to he in the ratio of the expansion of gases, 
 forming an addition to their volume of 
 5-8ths for every 180° Fahrenheit. We can 
 now infer, both from this expansion of 
 one measure into 1694, and from the table 
 of the elastic forces of steam, the explosive 
 violence of this agent at still higher tem- 
 pcratui es, and the danger to be apprehended 
 from the introduction of water into the close 
 
 Spec. Grav. Air, — 
 
 Vapour of water, - 0.62349 
 
 Hydroprussic acid, 0.94760 
 
 Absolute alcohol, L6050 
 
 Sulphuric ether, 2.5860 
 
 Ilydriodic ether, 5.4749 
 
 Oil of turpentine, 5.0130 
 
 Carburet of sulphur, 2.6447 
 
 Muriatic ether, 2.2190 
 
CAL 
 
 CAL 
 
 moulds, in which melted metal is to be poured. 
 Hence, also, the formidable accidents which 
 have happened, from a little water falling 
 into heated oils. The little glass spherules, 
 called candle bombs, exhibit the force of 
 steam in a very striking manner ; but the 
 risk of particles of glass being driven into 
 the eye, should cause their employment to 
 be confined to prudent experimenters. Mr 
 Watt estimated the volumes of steam result- 
 ing from a volume of water at 1800; and 
 in round numbers at 1728 ; a number differ- 
 ing little from the above determination of 
 M. Gay Lussac. Desagulier’s estimate of 
 14000 was therefore extravagant. 
 
 It has been already mentioned, that the 
 caloric of fluidity in steam surpasses that of 
 an equal weight of boiling water by about 
 972°. This quantity, or the latent heat of 
 steam, as it is called, is most conveniently 
 determined, by transmitting a certain weight 
 of it into a given weight of water, at a known 
 temperature, and from the observed eleva- 
 tion of temperature in the liquid, deducing 
 the heat evolved during condensation. Dr 
 331ack, Mr Watt, Lavoisier, Count Rum- 
 ford, Clement, and Desormes, as well as my- 
 self, have published observations on the sub- 
 ject. “ In this research I employed a very 
 simple apparatus ; and with proper manage- 
 ment, I believe, it is capable of giving the 
 absolute quantities of latent heat in different 
 vapours, as exactly as more refined and com- 
 plicated mechanisms. At any rate, it will 
 afford comparative results with great preci- 
 sion. It consisted of a glass retort of very 
 small dimensions, with a short neck, inserted 
 into a globular receiver of very thin glass, 
 and about three inches in diameter. The 
 globe was surrounded with a certain quan- 
 tity of water at a known temperature, con- 
 tained in a glass basin. 200 grains of the 
 liquid, whose vapour was to be examined, 
 were introduced into the retort, and rapidly 
 distilled into the globe by the heat of an 
 Argand lamp. The temperature of the air 
 was 45°, that of the water in the basin from 
 42° to 43°, and the rise of temperature, oc- 
 casioned by the condensation of the vapour, 
 never exceeded that of the atmosphere by 
 four degrees. By tnese means, as the com- 
 munication of heat is very slow between 
 bodies which differ little in temperature, I 
 found that the air could exercise no percep- 
 tible influence on the water in the basin dur- 
 ing the experiment, which was always com- 
 pleted in five or six minutes. A thermome- 
 ter of great delicacy was continually moved 
 through the water ; and its indications were 
 read off, by the aid of a lens, to small frac- 
 tions of a degree. 
 
 “ In all the early experiments of Dr 
 Black on the latent heat of common steam, 
 the neglect of the above precautions intro- 
 duced material errors into the estimate. 
 Hence, that distinguished philosopher found 
 the latent heat of steam to be no more than 
 800° or 810°. Mr Watt afterwards deter- 
 mined it more nearly from 900 to 970°, 
 Lavoisier and Laplace have made it 1000°, 
 and Count liumford 1040°. 
 
 “ From the smallness of the retort in my 
 mode of proceeding, the shortness of the 
 neck, and its thorough insertion into the 
 globe, we prevent condensation by the air 
 in transitu ; while the surface of the globe, 
 and the mass of water being great, relative 
 to the quantity of vapour employed, the heat 
 is entirely transferred to the refrigeratory, 
 where it is allowed to remain without appa- 
 rent diminution for a few minutes. 
 
 “ In numerous repetitions of the same 
 experiment the accordances were excellent. 
 The following table contains the mean re- 
 sults. The water in the basin weighed in 
 each case 32340 grs., and 200 grs. of each 
 liquid was distilled over. The globe was 
 held steadily in the centre of the globe by a 
 slender ring fixed round the neck.” For 
 the arithmetical reductions I must refer to 
 the paper itself. Dr Thomson, in his com- 
 ments on this part of my researches, ob- 
 serves, “ It is obvious, that the latent heats 
 determined in this way must be considerably 
 below the truth. The method contrived by 
 Count liumford seems to me a good deal 
 better. He cooled the water surrounding the 
 globe 4° below the temperature of the room, 
 and continued the distillation till the tem- 
 perature of the water was exactly 4° above 
 that of the room.” Surely Dr Thomson 
 cannot have read the paper with attention, or 
 he would have perceived the following sen- 
 tence : “ I found that the air could exercise 
 no perceptible influence on the water in the 
 basin during the experiment, which was al- 
 ways completed in five or six minutes.” In 
 fact, I left the glass basin of water repeat- 
 edly at a temperature of 4° above that of the 
 room for double the duration of the experi- 
 ment, and found scarcely a perceptible change 
 in the thermometer immersed in it. This 
 source of fallacy was sufficiently guarded 
 against. But I have found since, that a com- 
 pensation was due for the glass basin itself, 
 which I omitted by accident to introduce 
 into the arithmetical reductions. This would 
 have raised the latent heat of water to very 
 nearly 1000, and that of the other vapours 
 in a proportional degree. I now give the 
 original table, along with a corrected co- 
 lumn : 
 
CAL 
 
 CAL 
 
 Table of Latent Heat of Vapours 
 
 Vapour of water, at its boiling point, 
 Alcohol, sp. gr. 825, 
 
 Ether, boiling point 112°, 
 Petroleum, 
 
 Oil of turpentine, 
 
 Nitric acid, sp. gr. 1.494, boilin 
 Liquid ammonia, sp. gr. 0.978, 
 Vinegar, sp. gr. 1.007, 
 
 
 967° 
 
 Corrected column. 
 1000° 
 
 mm 
 
 442 
 
 457 
 
 - 
 
 302.4 
 
 312.9 
 
 
 177.8 
 
 1 83.8 
 
 - 
 
 177.8 
 
 183.8 
 
 point 165°, 
 
 532. 
 
 550. 
 
 
 837.3 
 
 865.9 
 
 mm 
 
 875.0 
 
 905 
 
 “ Aqueous vapour of an elastic force ba- 
 lancing the atmospheric pressure, has a spe- 
 cific gravity compared to air, by the accurate 
 experiments of M. Gay Lussac, of 10 to 16. 
 For facility of comparison, let us call the 
 steam of water unity, or 1.00 ; then the spe- 
 cific gravity of the vapour of pure ether is 
 4.00, while the specific gravity of the vapour 
 of absolute alcohol is 2.60. Cut the vapour 
 of ether, whose boiling point is not 100°, but 
 112°, like the above ether, contains some 
 alcohol ; hence, we must accordingly di- 
 minish a little the specific gravity number of 
 its vapour. It will then become, instead of 
 4.00, 3.55. Alcohol of 0.825 sp. gr. con- 
 tains much water ; sp. gr. of its vapour 2.30. 
 That of water, as before unity, 1.00. The 
 interstitial spaces in these vapours will there- 
 fore be inversely as these numbers, or % jj 
 for ether, -gjjj for alcohol, for water. 
 
 Hence, yjj of latent heat, existing in ethe- 
 real vapour, will occupy a proportional space, 
 be equally condensed, or possess the same 
 tension with ^ jn in alcoholic, and in 
 
 aqueous vapour. A small modification will 
 no doubt be introduced by the difference of 
 the thermometric tensions, or sensible heats, 
 under the same elastic force. Common 
 steam, for example, may be considered as 
 deriving its total elastic energy from the 
 latent heat multiplied into the specific gra- 
 vity -j- the thermometric tension. 
 
 “ Hence, the elastic force of water, ether, 
 and alcohol, are as follows: — 
 
 E w = 970 X LOO + 212° = 1182 
 
 E e = 302 X 3.55 + 112°= 1184 
 
 E al = 440 X 23.0 + 175° = 1 185 
 
 ' Three equations, which yield, according to 
 my general proposition, equal quantities. 
 When the elastic forces of vapours are 
 | doubled, or when they sustain a double 
 pressure, their interstices are proportionably 
 diminished. We may consider them now, 
 as in the condition of vapours possessed of 
 greater specific gravities. Hence, the se- 
 1 cond portion of heat introduced to give 
 double the elastic force need not be equal to 
 the first, in order to produce the double tension. 
 
 “ This view accords with the experi- 
 ments of Mr Watt, alluded to in the begin- 
 ning of the memoir, lie found, that the 
 
 latent heat of steam is less when it is pro- 
 duced under a greater pressure, or in a more 
 dense state ; and greater when it is produced 
 under a less pressure, or in a less dense state. 
 Bcrthollet thinks this fact so unaccountable, 
 that he has been willing to discard it alto- 
 gether. Whether the view I have just 
 opened, of the relation subsisting between 
 the elastic force, density, and latent heat of 
 different vapours, harmonize with chemical 
 phenomena in general, I leave others to 
 determine. It certainly agrees with that 
 unaccountable fact. Wliatever be the fate 
 of the general law, now respectfully offered, 
 the statement of Mr W r att may be implicitly 
 received, under the sanction of his acknow- 
 ledged sagacity and candour.” Ure's 
 searches on heat , pp. 54 and 55. 
 
 As it is the vastly greater relation to heat, 
 which steam possesses above water, that 
 makes the boiling point of that liquid so 
 perfectly stationary in open vessels, over the 
 strongest fires, we may imagine that other 
 vapours which have a smaller latent heat, 
 may not be capable, by their formation, of 
 keeping the ebullition of their respective li- 
 quids at a uniform temperature. I observed 
 this variation of the boiling point actually to 
 happen with oil of turpentine, petroleum, 
 and sulphuric acid. W r hen these liquids are 
 heated briskly in apothecaries’ phials, they 
 rise 20 or 30 degrees above the ordinary 
 point, at which they boil in hemispherical 
 capsules. Hence, also, their vapours being 
 generated with little heat, are apt to rise 
 with explosive violence. Oil of turpentine 
 varies moreover, in its boiling point, accord- 
 ing to its freshness and limpidity. It is 
 needless therefore, to raise an argument on 
 a couple of degrees of difference. But, in 
 Dr Murray’s, and all our other chemical 
 systems, published prior to 1817, 560° 
 was assigned as the boiling point of this 
 volatile oil. Mr Dalton’s must be except- 
 ed, for he says, “ several authors have it, 
 that oil of turpentine boils at 560°. I do 
 not know how the mistake originated, but 
 it boils below 212°, like the rest of the es- 
 sential oils.” Dr Thomson makes it 314°; 
 a number which, from the great price he 
 paid for his thermometer, he insinuates to be 
 more exact than mine of 316° ; and a for- 
 tiori than 320°, as found by the manufac- 
 turer of the oil, to whom I had referred. 
 
CAL 
 
 CAL 
 
 l3ut the difference of our two numbers is 
 in reality frivolous, ancl to be ascribed to 
 the state of the oil and of the heat, as much 
 as to errors of the instruments or of observa- 
 tion. It is probable that our thermometers 
 were equally correct, and used with equal 
 care. But what will l)r Thomson say of 
 Mr Dalton’s emendation? 
 
 from the above quotation it may be in- 
 ferred, that the conversion at all tempera- 
 tures, however low, of any liquid or solid 
 whatever, into a vapour, is uniformly accom- 
 panied with the abstraction of heat from 
 surrounding bodies, or in popular language, 
 the production of cold ; and that the degree 
 of refrigeration will be proportional to the 
 capacity of the vapour for heat, and the ra- 
 pidity of its formation. The application of 
 this principle to the uses of life, first sug- 
 gested by Drs Cullen and Black, has been 
 improved and extended by Mr Leslie. We 
 shall describe his methods under Congelation. 
 
 It appears, moreover, probable, that the 
 permanent gases have the same superior re- 
 lation to heat with the vapours. Hence, 
 their transition to the liquid or solid states 
 ought to be attended with the evolution of 
 heat. Accordingly, in the combustion of 
 hydrogen, phosphorus, and metals, gaseous 
 matter is copiously fixed ; to which cause 
 Black and Lavoisier ascribed the whole of 
 the heat and light evolved. We shall see, 
 however, in the article Combustion, many 
 difficulties to the adoption of this plausible 
 hypothesis. The best illustration of the com- 
 mon notion as to the latent heat of gases, is 
 afforded by the condensed air tinder-tube ; 
 in which mechanical compression appears to 
 extrude from cold air its latent stores of 
 both heat and light. A glass tube, eight 
 inches long, and half inch wide, of uniform 
 calibre, shut at one end, and fitted with a 
 short piston, is best adapted for the exhibi- 
 tion of this pleasing experiment. When the 
 object, however, is merely to kindle agaric- 
 tinder, a brass tube 3-8ths wide and 4 \ inches 
 long will suffice. A dexterous condensation 
 of air into l-5th of the volume, produces the 
 heat of ignition. 
 
 Under the head of specific heat, it has 
 been shewn to dimirtish in a gas, more ra- 
 pidly than the diminution of its volume ; 
 and therefore, heat will be disengaged by its 
 condensation, whether we regard the pheno- 
 menon as the expulsion of a fluid, or in- 
 tense actions excited among the particles, by 
 their violent approximation. The converse 
 of the above phenomenon is exhibited on a 
 great scale, in the Schemnitz mines of 
 Hungary. The hydraulic machine for drain- 
 ing them, consists essentially of two strong 
 air-tight copper cylinders, 96 feet vertically 
 distant from each other, and connected by a 
 pipe. The uppermost, which is at the mouth 
 of the pit, can be charged with water by the 
 
 pressure of a reservoir, elevated 136 feet 
 above it. The air suddenly dislodged by 
 this vast hydrostatic pressure, is condensed 
 through the pipe, on the surface of the w ater 
 standing in the lower cylinder, which it 
 forces up a rising water-pipe to the surface, 
 and then takes its place. When the stop- 
 cocks are turned to recharge the lower cylin- 
 der w r ith water, the imprisoned air expanding 
 to its natural volume, absorbs the heat so 
 powerfully, as to convert the drops of w'ater 
 that issue with it, into hail and snow. M. 
 Gay Lussac has lately proposed a miniature 
 imitation of this machine for artificial refri- 
 geration. He exposes the small body to be 
 cooled, to a stream of air escaping by a small 
 orifice, from a box in which it had been 
 strongly condensed. In the autumn of 
 1816, I performed an analogous experi- 
 ment in the house of M. Breguet, in Baris. 
 This celebrated artist having presented me 
 with one of his elegant metallic thermome- 
 ters, I immediately proposed to determine 
 by means of it, the heat first abstracted, and 
 subsequently disengaged, in .the exhaustion 
 of air, and its readmission into the receiver 
 of an air-pump. MM. Breguet polite- 
 ly favoured me with their assistance, and 
 the use of their excellent air-pump. Hav- 
 ing enclosed in the receiver their thermome- 
 ter, and a delicate one by Crighton, which 
 I happened to have wdth me, we found, on 
 rapidly exhausting the receiver, that M. 
 Breguet’s thermometer indicated a refrige- 
 ration of 50° F. while Crighton’s sunk 
 only 7°. After the tw r o had arrived at the. 
 same temperature, the air was rapidly ad- 
 mitted into the receiver. INI. Breguets 
 thermometer now rase 50°, while Crighton’s 
 mounted 7° as before. See Thermome- 
 ter. 
 
 Dr Darwin has ingeniously explained the 
 production of snow on the tops of the 
 highest mountains, by the precipitation of 
 vapour from the rarefied air which ascends 
 from plains and valleys. “ The Andes,” 
 says Sir II. Davy, “ placed almost under 
 the line, rise in the midst of burning sands ; 
 about the middle height is a pleasant and 
 mild climate ; the summits are covered with 
 unchanging snows ; and these ranges of 
 temperature are always distinct; the hot 
 winds from below', if they ascend, become 
 cooled in consequence of expansion and the 
 cold air ; if by any force of the blast it is 
 driven downwards, it is condensed, and ren- 
 dered warmer as it descends.” 
 
 Evaporation and rarefaction, the grand 
 means employed by nature to temper the 
 excessive heats of the torrid zone, operate 
 very powerfully among mountains and seas. 
 But the level sands are devoured by unmitN 
 gated heat. In milder climates, the fer- 
 vours of the solstitial sun are assuaged by 
 the vapours copiously raised from cvciy 
 
CAL 
 
 CAL 
 
 river attd field, while the Wintry cold is 
 moderated by the condensation of atmos- 
 pherio vapours in the form of snow. 
 
 The equilibrium of animal temperature is 
 maintained, by the copious discharge of va- 
 pour from the lungs and the skin. The sup- 
 pression of this exhalation is a common cause 
 of many formidable diseases. Among these, 
 fever takes the lead. The ardour of the 
 body in this case of suppressed perspiration, 
 sometimes exceeds the standard of health 
 by six or seven degrees. The direct and 
 natural means of allaying this morbid tem- 
 perature, were first systematically enjoined by 
 Dr Currie of Liverpool. He shewed, that 
 the dashing or affusion of cold water on the 
 skin of a fever patient, has most sanatory 
 effects, when the heat is steadily above 98°, 
 and when there is no sensation of chilliness, 
 and no moisture on the surface. Topical re- 
 frigeration is elegantly procured, by apply- 
 ing a piece of muslin or tissue paper to any 
 part of the skin, and moistening it with 
 ether, carburet of sulphur, or alcohol. By 
 pouring a succession of drops of ether, on 
 the surface of a thin glass tube containing 
 water, a cylinder of ice may be formed at 
 midsummer. The most convenient plan 
 
 which the chemist can employ, to free a gas 
 from vapour, is to pass it slowly through a 
 long tortuous tube Wrapt in porous paper 
 wetted with ether. 
 
 On the other hand, when he wishes to 
 expose his vessels to a regulated heat, he 
 makes hot vapour be condensed on their 
 cold surface. The heat thus disengaged 
 
 from the vapour, passes into the vessel, and 
 speedily raises it to a temperature which he 
 can adjust with the nicest precision. A 
 vapour bath ought therefore to be provided 
 for every laboratory. That which I got 
 constructed a few years ago for the Institu- 
 tion, is so simple and efficacious as to merit 
 a description. — A square tin box, about 18 
 inches long, 12 broad, and 6 deep, has its 
 bottom hollowed a little by the hammer to- 
 wards its centre, in which a round hole is 
 cut of five or six inches diameter. Into this, 
 a tin tube three or four inches long is sol- 
 dered. This tube is made to fit tightly into 
 the mouth of a common tea-kettle, which 
 has a folding handle. The top of the box 
 has a number of circular holes cut into it, of 
 different diameters, into which evaporating 
 capsules of platina, glass, or porcelain, are 
 placed. When the kettle, filled with water, 
 and with its nozzle corked, is set on a stove, 
 the vapour, playing on the bottoms of the 
 capsules, heats them to any required tem- 
 perature ; and being itself continually con- 
 densed, it runs back into the kettle, to be 
 raised again, in ceaseless cohobation. With 
 a shade above, to screen the vapour chest 
 from soot, the kettle may be placed over a 
 common lire. The orifices not in use, arc 
 
 closed with tin lids. In drying precipitates* 
 
 I cork up the tube of the glass funnel, and 
 place it, w ith its filter, directly into the pro- 
 per sized opening. For drying red cabbage, 
 violet petals, &c. a tin tray is provided, 
 Which fits close on the top of the box, with- 
 in the rim which goes about it. The round 
 orifices are left open when this tray is ap- 
 plied. Such a form of apparatus is well 
 adapted to inspissate the pasty mass, from 
 which lozenges and troches are to be made. 
 
 But the most splendid trophy erected to 
 the science of caloric, is the steam-engine of 
 Watt. This illustrious philosopher, from a 
 mistake of his friend Dr llobison, has been 
 hitherto defrauded of a part of his claims to 
 the admiration and gratitude of mankind. 
 The fundamental researches on the constitu- 
 tion of steam, which formed the solid basis 
 of his gigantic superstructure, though they 
 coincided perfectly with Dr Black’s results, 
 w ere not drawn from them. In some con- 
 versations with which this great ornament 
 and benefactor of his country honoured me 
 a short period before his death, he describ- 
 ed, with delightful naivete the simple, 
 but decisive experiments, by which he dis- 
 covered the latent heat of steam. His 
 
 means and his leisure not then permitting 
 an expensive and complex apparatus, he 
 used apothecaries’ phials. With these, he 
 ascertained the two main facts, first, that a 
 cubic inch of water would form about a 
 cubic foot of ordinary steam, or 1728 inches; 
 and that the condensation of that quantity of 
 steam w r ould heat six cubic inches of water 
 from the atmospheric temperature to the 
 boiling point. Hence he saw that six times 
 the difference of temperature, or fully 900° 
 of heat had been employed in giving elas- 
 ticity to steam ; which must be all abstract- 
 ed before a complete vacuum could be pro- 
 cured under the piston of the steam-engine. 
 These practical determinations he afterwards 
 found to agree pretty nearly with the obser- 
 vations of Dr Black. Though Mr Watt 
 was then known to the Doctor, he w r as not 
 on those terms of intimacy with him, which 
 he afterwards came to be, nor was he a mem- 
 ber of his class. 
 
 Mr Watt’s three capital improvements, 
 which seem to have nearly exhausted the re- 
 sources of science and art, were the following 
 1. The separate condensing chest, immersed 
 in a body of cold w ater, and connected merelv 
 by a slender pipe with the great cylinder, in 
 which the impelling piston moved. On open- 
 ing a valve or stop -cock of communication, 
 the elastic steam which had floated the pon- 
 derous piston, rushed into the distant chest 
 with magical velocity, leaving an almost per- 
 fect vacuum in the cylinder, into which the 
 piston w r as forced by atmospheric pressure. 
 What had appeared impossible to all previous 
 engineers was thus accomplished. A vacuum 
 
 47 
 
CAL 
 
 CAL 
 
 was formed without cooling the cylinder it- 
 self. Thus it remained boiling hot, ready the 
 next instant to receive and maintain the elastic 
 steam. 2. His second grand improvement 
 consisted in closing the cylinder at top, mak- 
 ing the piston rod slide through a stuffing 
 box in the lid, and causing the steam to give 
 the impulsive pressure instead of the atmos- 
 phere. Henceforth the waste of heat was 
 greatly diminished. 3. The final improve- 
 ment was the double impulse, whereby the 
 power of his engines, which was before so 
 great, was in a moment more than doubled. 
 The counter- weight required in the single 
 stroke engine, to depress the pump-end of 
 the working beam, was now laid aside. lie 
 thus freed the machine from a dead weight 
 or drag of many hundred pounds, which had 
 hung upon it from its birth, about seventy 
 years before. 
 
 The application of steam to heat apart- 
 ments, is another valuable fruit of these 
 studies. Safety, cleanliness, and comfort, 
 thus combine in giving a genial warmth for 
 every purpose of private accommodation, or 
 public manufacture. It has been ascertain- 
 ed, that one cubic foot of boiler will heat 
 about two thousand feet of space, in a cotton 
 mill, whose average heat is from 70° to 80° 
 Fahr. And if we allow 25 cubic feet of a 
 boiler for a horse’s power in a steam-engine 
 supplied by it, such a boiler would be ade- 
 quate to the w r arming of fifty thousand cubic 
 feet of space. It has been also ascertained, 
 that one square foot of surface of steam pipe, 
 is adequate to the warming of two hundred 
 cubic feet of space. This quantity is adapt- 
 ed to a w^ell finished ordinary brick or stone 
 building. The safety valve on the boiler 
 should be loaded with pounds for an area 
 of a square inch, as is the rule for Mr Watt’s 
 engines. Cast iron pipes are preferable to 
 all others, for the diffusion of heat. Free- 
 dom of expansion must be allowed, w hich in 
 cast iron may be taken at about a tenth of 
 an inch for every ten feet in length. The pipes 
 should be distributed within a few inches of 
 the fioor. 
 
 Steam is now used extensively for drying 
 muslin and calicoes. Large cylinders are 
 filled with it, which, diffusing in the apart- 
 ment a temperature of 100° or 150°, ra- 
 pidly dry the suspended cloth. Occasionally 
 the cloth is made to glide in a serpentine 
 manner closely round a series of steam cy- 
 linders, arranged in parallel rows. It is 
 thus safely and thoroughly dried in the 
 course of a minute. Experience has shewn, 
 that bright dyed yarns like scarlet, dried in 
 a common stove heat of 128°, have their 
 colour darkened, and acquire a harsh feel ; 
 while similar hanks, laid on a steam pipe 
 heated up to 165°, retain the shade and 
 lustre they possessed in the wetted state. 
 The people who w ork in steam drying- rooms 
 
 are healthy ; those who were formerly em- 
 ployed in the stove-heated apartments, be- 
 came soon sickly and emaciated. These in- 
 jurious effects must be ascribed to the action 
 of cast iron at a high temperature on the 
 atmosphere. 
 
 The heating by steam of large quantities 
 of water or other liquids, either for baths or 
 manufactures, may be effected in two ways ; 
 that is, the steam pipe may be plunged with 
 an open end into the water cistern ; or the 
 steam may be diffused around the liquid in 
 the interval between the wooden vessel and 
 an interior metallic case. The second mode 
 is of universal applicability. Since a gallon 
 of water in the form of steam will heat G 
 gallons at 50°, up to the boiling point, or 
 162°; 1 gallon of the former w ill be ade- 
 quate to heat 18 gallons of the latter up to 
 100°, making a liberal allowance for waste 
 in the conducting pipe. 
 
 Cooking of food for man and cattle is 
 likewise another useful application of steam ; 
 “ for,” says Dr Black, “ it is the most effec- 
 tual carrier of heat that can be conceived, 
 and will deposit it only on such bodies as are 
 colder than boiling water.” Hence in a 
 range of pots, wdienever the first has reached 
 the boiling point, but no sooner, the steam 
 will go onwards to the second, then to the 
 third, and thus in succession. Inspection of 
 the last will therefore satisfy us of the con- 
 dition of the preceding vessels. Distillation 
 has been lately practised, by surrounding the 
 still with a strong metallic case, and filling 
 the interstice with steam heated up to 260° 
 or 280°. But notwithstanding of safety 
 valves, and every ordinary attention, dan- 
 gerous explosions have happened. Distilla- 
 tion in vacuo , by the heat of external steam 
 of ordinary strength, would be a safe and 
 elegant process. The old, and probably 
 very exact experiments of Mr Watt on this 
 subject, do not lead us, however, to expect 
 any saving of fuel, merely by the vacuum 
 distillation. “ The unexpected result of 
 these experiments is, that there is no advan- 
 tage to be expected in the manufacture of 
 ardent spirits by distillation in vacuo. For 
 we find, that the latent heat of the steam is 
 at least a9 much increased as the sensible 
 heat is diminished .” — Dr Mack's Lectures , 
 vol. i. p. 1 90. 
 
 By advantage is evidently meant saving of 
 fuel. But in preparing spirits, ethers, vine- 
 gars, and essential oils, there would undoubt- 
 edly be a great advantage relative to flavour. 
 Every risk of empyreuma is removed. 
 
 Chambers filled with steam heated to 
 about 125° Fahr. have been introduced with 
 advantage into medicine, under the name of 
 vapour baths. Dry air has also been used. 
 
 It can be tolerated at a much greater heat 
 than moist air ; see Temperature. A large 
 cradle, containing saw-dust heated with steam, 
 
CAM 
 
 CAM 
 
 should be kept in readiness at the houses 
 erected by the Humane Society, for the re- 
 covery of drowned persons ; or a steam cham- * 
 ber might be attached to them for this pur- 
 pose, as well as general medicinal uses. 
 
 I have thus completed what I conceive to 
 belong directly to caloric in a chemical dic- 
 tionary. Under alcohol , attraction , blow- 
 pipe, climate, combustion , congelation, digester, 
 distillation, electricity, gas, light, pyrometer, 
 thermometer, water, some interesting corre- 
 lative facts will be found. 
 
 * Calorimeter. An instrument contrived 
 by Lavoisier and Laplace, to measure the 
 beat given out by a body in cooling, from the 
 quantity of ice it melts. It consists of 3 
 vessels, one placed within the other, so as to 
 leave 2 cavities between them ; and a frame 
 of iron network, to be suspended in the 
 middle of the inner vessel. This network is 
 to hold the heated body. The two exterior 
 concentric interstices are tilled with bruised 
 ice. The outermost serves to screen, from 
 the atmosphere, the ice in the middle space, 
 by the fusion of which the heat given out by 
 the central hot body is measured. The 
 water runs off through the bottom, and ter- 
 minates in the shape of a funnel, with a 
 stop-cock. * 
 
 * Calf. An argillo-ferruginous lime- 
 stone.* 
 
 * Cameleon Mineral. When pure potash 
 and black oxide of manganese are fused to- 
 gether in a crucible, a compound is formed 
 whose solution in water, at first green, passes 
 spontaneously through the whole series of 
 coloured rays to the red. From this latter 
 tint, the solution may be made to retrograde 
 in colour to the original green, by the addi- 
 tion of potash ; or it may be rendered alto- 
 gether colourless, by adding either sulphur- 
 ous acid or chlorine to the solution, in which 
 case there may or may not be a precipitate, 
 according to circumstances. MM. Chevillot 
 and Edouard have lately read some interest- 
 ing memoirs on this substance, before the 
 Academy of Sciences. They found, that 
 when potash and the green oxide of man- 
 ganese were heated in close vessels, contain- 
 ing azote, no cameleon is formed. The 
 same result followed with the brown oxide, 
 and ultimately with the black. They there- 
 fore ascribe the phenomena to the absorp- 
 tion ol oxygen, which is greatest when the 
 oxide of manganese equals the potash in 
 weight. They regard it as a manganesiate 
 of potash, though they have hitherto failed 
 in their attempts to separate this supposed 
 tetroxide, or manganesic acid. When acids 
 are poured upon the green cameleon, or an 
 alkali upon t lie red, they arc equally changed 
 from one colour to the other ; even boiling 
 and agitation are sufficient to disengage the 
 
 ! €*xcess of potash in the green cameleon, and 
 to change it into red," Many acids also, 
 
 when used in excess, decompose the cavnp- 
 leon entirely, by taking the potash from it, 
 disengaging the oxygen, and precipitating 
 the manganese in the state of black oxide. 
 Sugar, gums, and several other substances, 
 capable of taking away the oxygen, also de- 
 compose the cameleon, and an exposure to 
 the air likewise produces the same effect. 
 Soda, barytes, and strontites, also afford pe- 
 culiar cameleons. The red potash cameleon 
 is perfectly neutral. Phosphorus brought 
 in contact with it, produces a detonation ; 
 and it sets some other combustibles on fire. 
 Exposed alone to heat, it is resolved into oxy- 
 gen, black oxide of manganese, and green 
 cameleon, or submanganesiate of potash.* 
 
 Campeachy Wood. See Logwood. 
 
 Camphor. There are two kinds grow in 
 the East, the one produced in the islands of 
 Sumatra and Borneo, and the other produc- 
 ed in Japan and China. 
 
 Camphor is extracted from the roots, wood, 
 and leaves of two species of laurus, the roots 
 affording by far the greatest abundance. The 
 method consists in distilling with water in 
 large iron pots, serving as the body of a still, 
 with earthen heads adapted, stuffed with 
 straw, and provided with receivers. Most of 
 the camphor becomes condensed in the solid 
 form among the straw, and part comes over 
 with the water. 
 
 The sublimation of camphor is performed 
 in low flat-bottomed glass vessels placed in 
 sand ; and the camphor becomes concrete in 
 a pure state against the upper part, whence 
 it is afterwards separated with a knife, after 
 breaking the glass. Lewis asserts, that no 
 addition is requisite in the purification of 
 camphor ; but that the chief point consists in 
 managing the fire so that the upper part of 
 the vessel may be hot enough to bake the 
 sublimate together into a kind of cake. 
 Chaptal says, the Hollanders mix an ounce 
 of quicklime with every pound of camphor 
 previous to the distillation. 
 
 Purified .camphor is a white concrete crys- 
 talline substance, not brittle, but easily crum- 
 bled, having a peculiar consistence resem- 
 bling that of spermaceti, but harder. It has 
 a strong lively smell, and an acrid taste ; is 
 so volatile as totally to exhale when left ex- 
 posed in a warm air ; is light enough to 
 swim on water ; and is very inflammable, 
 burning with a very white flame and smoke, 
 without any residue. 
 
 The roots of zedoary, thyme, rosemary, 
 sage, the inula hellenium, the anemony, the 
 pasque flower or pulsatilla, and other vege- 
 tables, afford camphor by distillation. It is 
 observable, that all these plants afford a 
 much larger quantity of camphor, when the 
 sap has been suffered to pass to the concrete 
 state by several months’ drying. Thyme 
 and peppermint, slowly dried, afford much 
 camphor j and Mr Acliard has observed, 
 
CAM 
 
 CAN 
 
 that a smell of camphor is disengaged when 
 volatile oil of fennel is treated with acids. 
 
 Mr Kind, a German chemist, endeavour- 
 ing to incorporate muriatic acid gas with oil 
 of turpentine, by putting this oil into the 
 vessels in which the gas was received when 
 extricated, found the oil change first yellow, 
 then brown, and lastly, to be almost wholly 
 coagulated into a crystalline mass, which 
 comported itself in every respect like cam- 
 phor. TromsdorfF and Boullay confirm this. 
 A small quantity of camphor may be ob- 
 tained from oil of turpentine by simple dis- 
 tillation at a very gentle heat. Other essen- 
 tial oils, however, afford more. By evapo- 
 ration in shallow vessels, at a heat not ex- 
 ceeding 57° F. Mr Proust obtained from oil 
 of lavender .25, of sage .21, of marjoram 
 .1014, of rosemary .0025. He conducted 
 the operation on a pretty large scale. 
 
 Camphor is not soluble in water in any 
 jierceptible degree, though it communicates 
 its smell to that fluid, and may be burned 
 as it floats on its surface. It is said, how- 
 ever, that a surgeon at Madrid has effected 
 its solution in water by means of the car- 
 bonic acid. 
 
 Camphor may be powdered by moisten- 
 ing it with alcohol, and triturating it till 
 dry. It may be formed into an emulsion by 
 previous grinding with near three times its 
 weight of almonds, and afterwards gradually 
 adding the water. Yolk of egg and muci- 
 lages are also effectual for this purpose ; but 
 sugar does not answer well. 
 
 It has been observed by Romieu, that 
 small pieces of camphor floating on water 
 have a rotatory motion. 
 
 Alcohol, ethers, and oils, dissolve cam- 
 phor. 
 
 The addition of water to the spirituous or 
 acid solutions of camphor, instantly separates 
 
 it. 
 
 Mr Hatchett has particularly examined 
 the action of sulphuric acid on camphor. A 
 hundred grains of camphor were digested in 
 an ounce of concentrated sulphuric acid for 
 two days. A gentle heat was then applied, 
 and the digestion continued for two days 
 longer. Six ounces of water were then 
 added, and the whole distilled to dryness. 
 Three grains of an essential oil, having a 
 mixed odour of lavender and peppermint, 
 came over with the water. The residuum 
 being treated twice with two ounces of alco- 
 hoi each time, fifty-three grains of a com- 
 pact coal in small fragments remained un- 
 dissolved. The alcohol, being evaporated in 
 a water bath, yielded forty-nine grains of a 
 blackish-brown substance, which was bitter, 
 astringent, had the smell of caromel, and 
 formed a dark brown solution with water. 
 
 This solution threw down very dark brown 
 precipitates, with sulphate of iron, acetate of 
 lead, muriate of tin, and nitrate of lime. It 
 precipitated gold in the metallic state. Isin- 
 glass threw down the whole of what was dis- 
 solved in a nearly black precipitate. 
 
 When nitric acid is distilled repeatedly in 
 large quantities from camphor, it converts it 
 into a peculiar acid. See Acid (Cam- 
 phoric). 
 
 * Camphor melts at 288°, and boils at the 
 temperature of 400°. By passing it in va- 
 pour through peroxide of copper, Dr Thom- 
 son converted it into carbonic acid and wa- 
 ter. He operated upon a single grain. He 
 infers its composition to be 
 Carbon, 0.738 8J atms. = 6.375 73.91 
 Hydrogen, 0.144 10 =1.250 14.49 
 
 Oxygen, 0.118 1 = 1.000 11.60 
 
 1.000 8.625 100.00 
 
 As an internal medicine, camphor has been 
 frequently employed in doses of from 5 to 
 20 grains, with much advantage, to procure 
 sleep in mania, and to counteract gangrene. 
 Though a manifest stimulant, when exter- 
 nally applied, it appears from the reports of 
 Cullen and others, rather to diminish the 
 animal temperature and the frequency of the 
 pulse. In large doses it acts as a poison, an 
 effect best counteracted by opium. It is ad- 
 ministered to alleviate the irritating effects 
 of cantharides, mezereon, the saline prepara- 
 tions of mercury and drastic purgatives. It 
 lessens the nauseating tendency of squill, and 
 prevents it from irritating the bladder. It is 
 employed externally as a discutient.* Dis- 
 solved in acetic acid, with some essential 
 oils, it forms the aromatic vinegar, for which 
 we arc indebted to the elder Mr Henry. It 
 remarkably promotes the solution of copal. 
 Its effluvia are very noxious to insects, on 
 which account it is much used to defend sub- 
 jects of natural history from their ravages. 
 
 * Cancer, matter of. This morbid se- 
 cretion was found by Dr Crawford to give a 
 green colour to syrup of violets, and treated 
 with sulphuric acid, to emit a gas resembling 
 sulphuretted hydrogen, which he supposes 
 to have existed in combination with ammo- 
 nia in the ulcer. Hence the action of viru- 
 lent pus on metallic salts. He likewise ob- 
 served, that its odour was destroyed by aque- 
 ous chlorine, which lie therefore recommends 
 for washing cancerous sores.* 
 
 * Candles. Cylinders of tallow or wax, 
 containing in their axis a spongy cord of 
 cotton or hemp. A few years ago I made 
 a set of experiments on the relative intensi- 
 ties of light, and duration of different candles, 
 the result of which is contained in the fol- 
 lowing table : — 
 
CAN 
 
 CAO 
 
 Number in a 
 Pound. 
 
 Duration of a 
 Candle. 
 
 Weight in 
 grains. 
 
 Consumption 
 per hour, 
 grains. 
 
 Proportion 
 
 of 
 
 Light. 
 
 Economy 
 
 of 
 
 Light. 
 
 Candles 
 
 equal 
 
 one argand. 
 
 10 mould. 
 
 5 h. 9 m. 
 
 682 
 
 132 
 
 12* 
 
 68 
 
 5.7 
 
 10 dipped. 
 
 4 36 
 
 672 
 
 150 
 
 13 
 
 65{ 
 
 5.25 
 
 8 mould. 
 
 6 31 
 
 856 
 
 132 
 
 10i 
 
 59^§ 
 
 6.6 
 
 6 do 
 
 h oJL 
 
 • -a 
 
 1160 
 
 3 63 
 
 
 66 
 
 5.0 
 
 4 do 
 
 Argand oil 
 
 9 36 
 
 1787 
 
 186 
 
 20^ 
 
 80 
 
 3.5 
 
 flame, 
 
 
 
 512 
 
 69*4 
 
 TOO 
 
 
 A Scotch mutehkin, or 1 - Sth of a gallon of 
 good seal oil, weighs 6010 gr.or 13 and l -10th 
 oz. avoirdupois, and lasts in a bright argand 
 lamp, 1 1 hours 44 minutes. The weight 
 of oil it consumes per hour, is equal to four 
 times the weight of tallow in candles, 8 to 
 the pound, and 5y times the weight of 
 tallow in candles, 6’ to the pound. But its 
 light, being equal to that of 5 of the latter 
 candles, it appears from the above table, that 
 2 pounds weight of oil, value Is. in an ar- 
 gand, are equivalent in illuminating power 
 to o pounds of tallow candles, which cost 
 about three shillings. The larger the flame 
 in the above candles, the greater the econo- 
 my of light.* 
 
 * Cannel Coal. Sec Coal.* 
 
 * Cannon Metal. See Copper. * 
 
 * Canthaiiides. Insects vulgarly called 
 Spanish flies : lytta vessicatoria is the name 
 adopted from Gmelin, by the London col- 
 lege. This insect is two-thirds of an inch 
 in length, one- fourth in breadth, oblong, and 
 of a gold shining colour, with soft elytera or 
 wing sheathes, marked with three longitudi- 
 nal raised stripes, and covering brown mem- 
 branous wings. An insect of a square form, 
 with black feet, but possessed of no vesicat- 
 ing property, is sometimes mixed with the 
 can thar ides. They have a heavy disagree- 
 able odour, and acrid taste. 
 
 li the inspissated watery decoction of these 
 insects be treated with pure alcohol, a solu- 
 tion of a resinous matter is obtained, which 
 being separated by gentle evaporation to dry- 
 ness, and submitted for some time to the 
 action ot sulphuric ether, forms a yellow so- 
 lution. By spontaneous evaporation crystal- 
 line plates are deposited, which may be freed 
 from some adhering colouring matter by al- 
 cohol. Their appearance is like spermaceti. 
 They are soluble in boiling alcohol, but pre- 
 cipitate as it cools. They do not dissolve in 
 water. According to M. Robiquet, who 
 lirst discovered them, these plates form the 
 true blistering principle. They might be 
 called Vesicatorin. Besides the above pe- 
 culiai body, cantharides contain, according 
 to M. Robiquet, a green bland oil, insoluble 
 in water, soluble in alcohol ; a black matter, 
 soluble in water, insoluble in alcohol, with- 
 out blistering properties ; a yellow viscid mat- 
 
 ter, mild, soluble ill water and alcohol ; the 
 crystalline plates ; a fatty bland matter ; 
 phosphates of lime and magnesia; a little 
 acetic acid, and much litliic or uric acid. 
 The blistering fly taken into the stomach in 
 doses of a few grains, acts as a poison, occa- 
 sioning horrible satyriasis, delirium, convul- 
 sions, and death. Some frightful cases are 
 related by Orfila, vol. i. part 2d. Oils, 
 milk, syrups, frictions on the spine, with vo- 
 latile liniment and laudanum, and draughts 
 containing musk, opium, and camphorated 
 emulsion, are the best antidotes.* 
 
 Caoutchouc. This substance, which has 
 been improperly termed elastic gum, and 
 vulgarly, from its common application to rub 
 out pencil marks on paper, Lidia rubber , is 
 obtained from the milky juice of different 
 plants in hot countries. The chief of these 
 are the Jatropha elastica, and Urceola elas • 
 tica. 
 
 The juice is applied in successive coat- 
 ings on a mould of clay, and dried by the 
 fire or in the sun ; and when of a sufficient 
 thickness, the mould is crushed, and the 
 pieces shaken out. Acids separate the ca- 
 outchouc from the thinner part of the juice 
 at once by coagulating it* The juice of old 
 plants yields nearly two-thirds of its weight; 
 that of younger plants less. Its colour, when 
 fresh, is yellowish white, but it grows darker 
 by exposure to the air. 
 
 The elasticity of this substance is its most 
 remarkable property: when warmed, ashy 
 immersion in hot water, slips of it may be 
 drawn out to seven or eight times their origi- 
 nal length, and M ill return to their former 
 dimensions nearly. Cold renders it stiff’ and 
 rigid, but warmth restores its original elasti- 
 city. Exposed to the fire it softens, swells 
 up, and burns with a bright flame. In 
 Cayenne it is used to give light as a candle. 
 Its solvents are ether, volatile oils, and pe- 
 troleum. The ether, however, requires to be 
 washed with water repeatedly, and in this 
 state it dissolves it completely. Pelletier 
 recommends to boil the caoutchouc in water 
 for an hour; then to cut it into slender 
 threads; to boil it again about an hour; and 
 then to put it into rectified sulphuric ether 
 in a vessel close stopped. In this May he 
 says it will be totally dissolved in a few days, 
 
CAO 
 
 CAR 
 
 without heat, except the impurities, which 
 ■will fall to the bottom, if ether enough be 
 employed. Berniard says, the nitrous ether 
 dissolves it better than the sulphuric. If 
 this solution be spread on any substance, the 
 ether evaporates very quickly, and leaves a 
 coating of caoutchouc unaltered in its pro- 
 perties. Naphtha, or petroleum, rectified 
 into a colourless liquid, dissolves it, and like- 
 wise leaves it unchanged by evaporation. 
 Oil of turpentine softens it, and forms a pasty 
 mass, that may be spread as a varnish, but 
 is very long in drying. A solution of caout- 
 chouc in five times its weight of oil of tur- 
 pentine, and this solution dissolved in eight 
 times its weight of drying linseed oil by boil- 
 ing, is said to form the varnish of air-balloons. 
 Alkalis act upon it so as in time to destroy 
 its elasticity. Sulphuric acid is decomposed 
 by it ; sulphurous acid being evolved, and 
 the caoutchouc converted into charcoal. 
 Nitric acid acts upon it with heat ; nitrous 
 gas being given out, and oxalic acid crys- 
 tallizing from the residuum. On distillation 
 it gives out ammonia, and carburetted hydro- 
 gen. 
 
 Caoutchouc may be formed into various 
 articles without undergoing the process of 
 solution. If it be cut into a uniform slip of 
 a proper thickness, and wound spirally round 
 a glass or metal rod, so that the edges shall 
 be in close contact, and in this state be boiled 
 for some time, the edges will adhere so as to 
 form a tube. Pieces of it may be readily 
 joined by touching the edges with the solu- 
 tion in ether : but this is not absolutely ne- 
 cessary, for, if they be merely softened by 
 heat, and then pressed together, they will 
 unite very firmly. 
 
 If linseed oil be rendered very drying by 
 digesting it upon an oxide of lead, and after- 
 ward applied with a small brush on any sur- 
 face, and dried by the sun or in the smoke, 
 it will afford a pellicle of considerable firm- 
 ness, transparent, burning like caoutchouc, 
 and wonderfully elastic. A pound of this 
 oil, spread upon a stone, and exposed to the 
 air for six or seven months, acquired almost 
 all the properties of caoutchouc : it was used 
 to make catheters and bougies, to varnish 
 balloons, and for other purposes. 
 
 Of the mineral caoutchouc there are seve- 
 ral varieties: 1. Of a blackish-brown inclin- 
 ing to olive, soft, exceedingly compressible, 
 unctuous, with a slightly aromatic smell. 
 It burns with a bright flame, leaving a black 
 oily residuum, which does not become dry. 
 2. Black, dry, and cracked on the surface, 
 but, when cut into, of a yellowish- white. A 
 fluid resembling pyrolignic acid exudes from 
 it when recently cut. It is pellucid on the 
 edges, and nearly of a hyacinthine red co- 
 lour. 3. Similar to the preceding, but of a 
 somewhat firmer texture, and ligneous ap- 
 pearance, from having acquired consistency 
 
 in repeated layers. 4. Resembling the first 
 variety, but of a darker colour, and adhering 
 to gray calcareous spar with some grains of 
 galaena. 5. Of a liver-brown colour, having 
 the aspect of the vegetable caoutchouc, but 
 passing by gradual transition into a brittle 
 bitumen, of vitreous lustre, and a yellowish 
 colour. 6. Dull reddish-brown, of a spongy 
 or cork -like texture, containing blackish-grey 
 nuclei of impure caoutchouc. Many more 
 varieties are enumerated. 
 
 One specimen of this caoutchouc has been 
 found in a petrified marine shell enclosed in 
 a rock, and another enclosed in crystallized 
 flu or spar. 
 
 The mineral caoutchouc resists the action 
 of solvents still more than the vegetable. The 
 rectified oil of petroleum affects it most, par- 
 ticularly when by partial burning it is resolv- 
 ed into a pitchy viscous substance. A hun- 
 dred grains of a specimen analyzed in the 
 dry way by Klaproth, afforded carburetted 
 hydrogen gas 38 cubic inches, carbonic acid 
 gas 4, bituminous oil 73 grains, acidulous 
 phlegm 1.5, charcoal 6.25, lime 2, silex 1.5, 
 oxide of iron .75, sulphate of lime .5, alumina 
 .25. 
 
 Carat. See Assay. 
 
 Carbon. When vegetable matter, parti- 
 cularly the more solid, as wood, is exposed 
 to heat in close vessels, the volatile parts fly 
 off, and leave behind a black porous sub- 
 stance, which is charcoal. If this be suffered 
 to undergo combustion in contact with oxygen, 
 or with atmospheric air, much the greater 
 part of it will combine with the oxygen, and 
 escape in the form of gas; leaving about a 
 two- hundredth part, which consists chiefly 
 of different saline and metallic substances. 
 This pure inflammable part of the charcoal 
 is what is commonly called carbon ; and if 
 the gas be received into proper vessels, the 
 carbon will be found to have been converted 
 by the oxygen into an acid, called the car- 
 bonic. See Acid (Carbonic). 
 
 From the circumstance, that inflammable 
 substances refract light, in a ratio greater 
 than that of their densities, Newton inferred, 
 that the diamond was inflammable. The 
 quantity of the inflammable part of charcoal 
 requisite to form a hundred parts of carbo- 
 nic acid, was calculated by Lavoisier to he 
 twenty-eight parts. From a careful experi- 
 ment of Mr Tennant, 27.6 parts of diamond, 
 and 72.4 of oxygen, formed 100 of carbonic 
 acid ; and hence lie inferred the identity of 
 diamond, and the inflammable part of char- 
 coal. 
 
 * Diamonds had been frequently consumed 
 in the open air with burning glasses; hut 
 Lavoisier first consumed them in oxygen gas, 
 and discovered carbonic acid to be the only 
 result. Sir George Mackenzie shewed, that 
 a red heat, inferior to what melts silver, i'* 
 sufficient to burn diamonds. They first cn- 
 
 u 
 
CAR 
 
 CAR 
 
 large somewhat in volume, and then waste 
 with a feeble flame. M. Guyton Morveau 
 was the first who dropped diamonds into 
 melted nitre, and observed the formation of 
 carbonic acid. 
 
 From a number of experiments M. Biot 
 lias made on the refraction of different sub- 
 stances, he has been led to form a different 
 opinion. According to him, if the elements 
 of which a substance is composed be known, 
 their proportions may be calculated with the 
 greatest accuracy from their refractive powers. 
 Thus he finds, that the diamond cannot be 
 pure carbon, but requires at least one-fourth 
 of hydrogen, which has the greatest refractive 
 power of any substance, to make its refrac- 
 tion commensurate to its density. 
 
 In 1809, Messrs Allen and Pepys made 
 some accurate researches on the combustion 
 of various species of carbon in oxygen, by 
 means of an elegant apparatus of their own 
 contrivance. A platina tube traversing a fur- 
 nace, and containing a given weight of the 
 carbonaceous substance, was connected at the 
 ends with two mercurial gasometers, one of 
 which was filled with oxygen gas, and the 
 other was empty. The same weight of dia- 
 mond, carbon, and plumbago, yielded very 
 nearly the same volume of carbonic acid. 
 Sir H. Davy was the first to shew' that the 
 diamond was capable of supporting its own 
 combustion in oxygen, without the continued 
 application of extraneous heat, and he thus 
 obviated one of the apparent anomalies of 
 this body, compared with charcoal. This 
 phenomenon, by his method, can now be 
 easily exhibited. If the diamond, supported 
 in a perforated cup, be fixed at the end of a 
 jet, so that a stream of hydrogen can be 
 thrown on it, it is easy, by inflaming the jet, 
 to ignite the gem, and whilst in that state to 
 introduce it into a globe or flask containing 
 oxygen. On turning off the hydrogen, the 
 diamond enters into combustion, and will go 
 on burning till nearly consumed. The loss 
 of weight, and corresponding production of 
 carbonic acid, were thus beautifully shewn. 
 
 A neat form of apparatus for this purpose is 
 delineated by Mr Faraday, in the 9th volume 
 of the Journal of Science. Sir H. Davy 
 found, that diamonds gave a volume of pure 
 carbonic acid, equal to the oxygen consumed • 
 charcoal and plumbago afforded a minute por- 
 tion of hydrogen.* See Diamond. 
 
 Well -burned charcoal is a conductor of 
 electricity, though wood simply deprived of 
 its moisture by baking is a nonconductor • but 
 it is a very bad conductor of caloric, a pro- 
 perty of considerable use on many occasions, 
 as m lining crucibles. 
 
 It is insoluble in water, and hence the uti- 
 Illy of charring the surfaqp of wood exposed 
 to that liquid, in order to preserve it, a cir- 
 cumstanee not unknown to the ancients. This 
 preparation of timber has been proposed as 
 
 an effectual preventive of what 16 commonly 
 called the dry rot. It has an attraction, 
 however, for a certain portion of water, which 
 it retains very forcibly. Heated red-hot, or 
 nearly so, it decomposes water; forming with 
 its oxygen carbonic acid, or carbonic oxide, 
 according to the quantity present ; and with 
 the hydrogen a gaseous carburet, called car- 
 buretted hydrogen, or heavy inflammable 
 air. 
 
 Charcoal is infusible by any heat. If ex- 
 posed to a very high temperature in close ves- 
 sels it loses little or nothing of its weight, but 
 shrinks, becomes more compact, and acquires 
 a deeper black colour. 
 
 Recently prepared charcoal has a remark- 
 able property of absorbing different gases, 
 and condensing them in its pores, without 
 any alteration of their properties or its own. 
 
 * The following are the latest results of M. 
 Theodore de Saussure, with boxwood char- 
 coal, the most powerful species : 
 
 Gaseous ammonia, 
 
 Ditto muriatic acid, 
 
 Ditto sulphurous acid, 
 
 Sulphuretted hydrogen, 
 
 Nitrous oxide, 
 
 90 vols. 
 85 
 65 
 55 
 40 
 35 
 35 
 9.42 
 9.25 
 
 7.5 
 
 5.0 
 
 1.75 
 
 Carbonic oxide, 
 
 Olefiant gas, 
 
 Carbonic oxide, 
 
 Oxygen, 
 
 Azote, 
 
 Light gas from moist charcoal, 
 
 Hydrogen, 
 
 Very light charcoal, such as that of cork, 
 absorbs scarcely any air ; while the pit-coal 
 of Rastiberg, sp. gr. 1.526, absorbs 10| times 
 its volume. The absorption was always com- 
 pleted in 24 hours. This curious faculty, 
 which is common to all porous bodies, resem- 
 bles the action of capillary tubes on liquids. 
 When a piece of charcoal, charged with one 
 gas, is transferred into another, it absorbs 
 some of it, and parts with a portion of that 
 first condensed. In the experiments of 
 Messrs Allen and Pepys, charcoal was found 
 to imbibe from the atmosphere in a day about 
 l -8th of its weight of water. For a general 
 view of absorption, see Gas. 
 
 When oxygen is condensed by charcoal, 
 carbonic acid is observed to form at the end 
 of several months. But the most remarkable 
 property displayed by charcoals impregnated 
 with gas, is that with sulphuretted hydrogen, 
 when exposed to the air or oxygen gas. Xhe 
 sulphuretted hydrogen is speedily destroyed 
 and water and sulphur result, with the disen- 
 gagement of considerable heat. Hydrogen 
 alone has no such effects. When charcoal 
 was exposed by Sir II. Davy to intense i<mi- 
 11011 m vacuo ’ a,ld in condensed azotef bv 
 means of Mr Children’s magnificent voltaic 
 .attcry, it slowly volatilized, and gave out a 
 little hydrogen. The remaining part was 
 always much harder than before ; and in one 
 
CAR 
 
 CAR 
 
 case so hard a3 to scratch glass, while its lus- 
 tre was increased. This line experiment may 
 he regarded as a near approach to the pro- 
 duction of diamond.* 
 
 Charcoal has a powerful affinity for oxy- 
 gen, whence its use in disoxygenating metallic 
 oxides, and restoring their base to its origi- 
 nal metallic state, or reviving the metal. 
 1 hus too it decomposes several of the acids, 
 as the phosphoric and sulphuric, from which 
 it abstracts their oxygen, and leaves the phos- 
 phorus and sulphur free. 
 
 Carbon is capable of combining with sul- 
 phur, and with hydrogen. With iron it forms 
 steel ; and it unites with copper into a car- 
 buret, as observed by Dr Priestley. 
 
 A singular and important property of char- 
 coal is that of destroying the smell, colour, 
 and taste of various substances : for the first 
 accurate experiments on which we are chiefiy 
 indebted to Mr Lowitz of Petersburgh, 
 though it had been long before recommend- 
 ed to correct the foetor of foul ulcers, and as 
 an antiseptic. On this account it is certainly 
 the best dentifrice. Water that has become 
 putrid by long keeping in wooden casks, is 
 rendered sweet by filtering through charcoal 
 powder, or by agitation with it ; particularly 
 if a few drops of sulphuric acid be added. 
 Common vinegar boiled with charcoal pow- 
 der becomes perfectly limpid. Saline solu- 
 tions, that are tinged yellow or brown, are 
 rendered colourless in the same way, so as to 
 afford perfectly white crystals. The impure 
 carbonate of ammonia obtained from bones, 
 is deprived both of its colour and fetid smell 
 by sublimation with an equal weight of char- 
 coal powder. Malt spirit is freed from its 
 disagreeable flavour by distillation from char- 
 coal ; but if too much be used, part of the 
 spirit is decomposed. Simple maceration, for 
 eight or ten days, in the proportion of about 
 1-1 50th of the weight of the spirit, improves 
 the flavour much. It is necessary, that the 
 charcoal be well burned, brought to a red 
 heat before it is used, and used as soon as 
 may be, or at least be carefully excluded from 
 the air. The proper proportion too should 
 be ascertained by experiment on a small scale. 
 The charcoal may be used repeatedly, by ex- 
 posing it for some time to a red heat before 
 it is again employed. 
 
 Charcoal is used on particular occasions 
 as fuel, on account of its giving a strong and 
 steady heat without smoke. It is employed 
 to convert iron into steel by cementation. 
 It enters into the composition of gunpowder. 
 In its finer states, as in ivory black, lamp- 
 black, &c. it forms the basis of black paints, 
 Indian ink, and printers’ ink. 
 
 * The purest carbon for chemical pur- 
 poses is obtained by strongly igniting lamp- 
 black in a covered crucible. This yields, 
 like the diamond, unmixed carbonic acid by 
 combustion in oxygen. 
 
 Carbon unites with all the common sim- 
 ple combustibles, and with azote, forming 
 a series of most important compounds. With 
 sulphur it forms a curious limpid liquid call- 
 ed carburet of sulphur, or sulphuret of car- 
 bon. With phosphorus it forms a species 
 of compound, whose properties are imper- 
 fectly ascertained. It unites with hydrogen 
 in two definite proportions, constituting sub- 
 carburetted and carburetted hydrogen gases. 
 With azote it forms prussic gas, the cyano- 
 gen of M. Gay Lussac. Steel and plum- 
 bago are two different compounds of carbon 
 with iron. In black chalk we find this 
 combustible intimately associated with silica 
 and alumina. The primitive combining pro- 
 portion, or prime equivalent of carbon, is 0.75 
 on the oxygen scale.* 
 
 * Carbon (Mineral), is of a greyish- 
 black colour. It is charcoal, with various 
 proportions of earth and iron, without bitu- 
 men. It has a silky lustre, and the fibrous 
 texture of wood. It is found in small quan- 
 tities, stratified with brown coal, slate coal, 
 and pitch coal.* 
 
 * Carbonates. Compounds of carbonic 
 acid with the salifiable bases. They are 
 composed either of one prime of the acid 
 and one of the base, or of two of the acid 
 and one of the base. The former set of 
 compounds is called carbonates, the latter 
 bicarbonates. See Carbonic Acid. 
 
 As the system of chemical equivalents, or 
 atomic theory of chemical combination, de- 
 rives some of its fundamental or prime pro- 
 portions from the constitution of the carbo- 
 nates, their analysis requires peculiar precau- 
 tions. In the Annals of Philosophy for 
 October 1817, I gave a description of a new 
 instrument for accomplishing this purpose 
 with the minutest precision. 
 
 The usual mode of analysis is to put a 
 giv^n weight of the carbonate in a phial, 
 and add to it a certain quantity of a liquid 
 acid which will dissolve the base, and dis- 
 engage the carbonic acid. I found, with 
 every care I could take in this method, 
 that variable and uncertain quantities of tlio 
 liquid acid were apt to be carried off in va- 
 pour with the carbonic gas, w hile a portion of 
 this gaseous acid was generally retained in 
 the saline liquid. Hence, in the analysis of 
 crystallized carbonate of lime, the most uni- 
 form of all compounds, we have the follow- 
 ing discordant results, which are of import* 
 cnee in the doctrine of equivalents : — 
 
 Mr Kirvvan makes it consist of 
 
 
 45 acid 
 
 -j- 55 lime, 
 
 MM. Aiken, 
 
 44 
 
 -f- 56 
 
 Dr Marcct, 
 
 45.9 
 
 4- 56.1 
 
 Dr Wollaston, 
 
 45.7 
 
 -f 56.3 
 
 M. Vauquelin, 
 
 45.5 
 
 4- 56.5 
 
 M. Thenard, 
 
 45/28 
 
 -f 56.72 
 
 Dr Thomson, 
 
 45.157 
 
 4- 56.865 
 
 If wc deduce the 
 
 equivalent of hme lrom 
 
CAR 
 
 CAR 
 
 the analysis of Dr Marcet, so well known 
 for his philosophical accuracy, we shall have 
 Lime = 55.1 to carb. acid 27.5 
 Dr Thomson’s is 36.25 to do. 27.5 
 I adduced the following experiment, se- 
 lected from among many others, as capable 
 of throwing light on the cause of these varia- 
 tions : “ Into a small pear-shaped vessel of 
 glass, with a long neck, and furnished with 
 a hollow spherical stopper, drawn out, above 
 and below, into a tube almost capillary, some 
 dilute muriatic acid was put. The whole 
 being poised in a delicate balance, 100 grains 
 of calc spar in rhomboidal fragments were 
 introduced, and the stopper was quickly in- 
 serted. A little while after the solution was 
 completed, the diminution of weight, indicat- 
 ing the loss of carbonic acid, was found to 
 be 42.2 grains. Withdrawing the stopper, 
 inclining the vessel to one side for a few 
 minutes, to allow the dense gas to flow out, 
 the diminution became 43.3, Finally, on 
 heating the body of the vessel to about 70°, 
 while the hollow stopper was kept cool, 
 small bubbles of gas escaped from the liquid, 
 and the loss of weight was found to be 43,65, 
 at which point it was stationary. This is a 
 tedious process.” The instrument which I 
 subsequently employed is quick in its opera- 
 tion, and still more accurate in its results. 
 It consists of a glass tube of the same 
 strength and diameter with that usually em- 
 ployed for barometers, having a strong egg- 
 j shaped bulb, about 2 inches long, and 
 1 wide, blown at one of its ends, while the 
 1 other is open and recurved like a syphon. 
 
 | The straight part of the tube, between the 
 ball and bend, is about 7 inches long. The 
 capacity, exclusive of the curved part, is a 
 ! little more than 5 cubic inches. It is accu- 
 fi rately graduated into cubic inches and hun- 
 | dredth parts, by the successive additions of 
 j equal weights of quicksilver, from a meastire 
 ‘I thermometric tube. Seven troy ounces and 
 66 grains of quicksilver occupy the bulk of 
 | one cubic inch. Four and a half such por- 
 tions being introduced, will fill the ball, and 
 the beginning of the stem. The point in 
 the tube, which is a tangent to the surface of 
 the mercury, is marked with a file or a dia- 
 mond. Then 34-^ grains, equal in volume to 
 ] -100th of a cubic inch, being drawn up 
 into the thermometric tube, rest at a certain 
 : height, which is also marked. The samo 
 i measure of mercury is successively introduc- 
 ed and marked off, till the tube is filled. 
 
 1 “ In the instrument thus finished, 1 -200th 
 
 of a cubic inch occupies on the stem about 
 1- 14th of an inch, a space very distinguisha- 
 ble. The weight of carbonic acid, equivalent 
 to that number, is less than l-400t!i of a 
 grain, 'file mode of using it is perfectly 
 simple and commodious, and the analytical 
 result is commonly obtained in a few mi- 
 nutes.” 
 
 For example, five grains of calcareous spar 
 in three or four rhomboids were weighed 
 with great care in a balance by Crighton, 
 
 which turns with ^oo\)(jlT °* ^ ie w f 1 3h t in 
 the scales. These are introduced into the 
 empty tube, and made to slide gently along 
 into the spheroid. The instrument is then 
 held in nearly a horizontal position with the 
 left hand, the top of the spheroid resting 
 against the breast, with a small funnel bent 
 at its point, inserted into the orifice of the 
 tube. Quicksilver is now poured in till it 
 be filled, which in this position is accom- 
 plished in a few seconds. Should any par- 
 ticles of air be entangled among the mercu- 
 ry, they are discharged by inverting the in- 
 strument, having closed the orifice with the 
 finger. On reverting it, and tapping the 
 ball with the finger, the fragments of spar 
 rise to the top. Three or four hundredth 
 parts of a cubic inch of mercury being dis- 
 placed from the mouth of the tube, that 
 bulk of dilute muriatic acid is poured :n ; 
 then pressing the forefinger on the orifice, 
 and inclining the instrument forwards, the 
 acid is made to rise through the quicksilver. 
 This, as it is displaced by the cooled carbo- 
 nic acid, falls into a stone-ware or glass 
 basin, within which the instrument stands in 
 a wooden frame. When the solution is 
 completed, the apparent volume of gas is 
 noted, the mercury in the two legs of the 
 syphon is brought to a level, or the differ- 
 ence of height above the mercury in the basin 
 is observed, as also the temperature of the 
 apartment, and the height of the barometer. 
 Then the ordinary corrections being made, 
 we have the exact volume of carbonic acid 
 contained in five grains of calc spar. In 
 very numerous experiments, which I have 
 made in very different circumstances of at- 
 mospherical pressure and temperature, the 
 results have not varied one-hundredth of a 
 cubic inch, on five grains, care being had to 
 screen the instrument from the radiation of 
 the sun or a fire. 
 
 As there is absolutely no action exercised 
 on mercury by dilute muriatic acid at ordi- 
 nary temperatures ; as no perceptible differ- 
 ence is made in the bulk of air, by introduc- 
 ing to it over the mercury a little of the acid 
 by itself; and as we can expel every atom of 
 carbonic acid from the muriate of lime, or 
 other saline solution, by gently heating that 
 point of the tube which contains it, it is evi- 
 dent that the total volume of gaseous pro- 
 duct must be accurately determined. When 
 a series of experiments is to be performed in 
 a short space of time, I wash the quicksilver 
 with w:ater, dry it with a sponge first, and 
 then with warm muslin. The tube is also 
 washed out and drained. According to my 
 experiments with the above instrument, 5 
 grains of calcareous spar yield 4.7 cubic 
 inches of carbonic acid, equivalent to 43.6 1 6 
 
 
CAR 
 
 CAR 
 
 per cent. The difference between this num- 
 ber and l)r Wollaston’s is inconsiderable. 
 
 Among other results which I obtained from 
 the use ot the above instrument, it enabled 
 me to ascertain the true composition of the 
 sublimed carbonate of ammonia, which che- 
 mists had previously mistaken. 1 shewed in 
 the Annals of Philosophy for September 
 
 1817, that this salt contained 54.5 of carbo- 
 nic acid, 50.5 ammonia, and 15 water, in 
 100 parts; numbers which, being translated 
 into the language of equivalents, approach 
 to the following proportions: — 
 
 Carbonic acid, 3 primes, 8.25 55. 89 
 
 Ammonia, 2 4.26 28.86 
 
 Water, 2 2.25 15.25 
 
 14.76 100.00 
 
 As this volatile salt possesses the curious 
 property of passing readily from one system 
 of definite proportions to another, absolute 
 accordance between experiment and theory 
 cannot be expected. The other salt gave 
 for its constituents, 54.5 carbonic acid 22.8 
 ammonia -f- 22.75 water = 100. Now, if 
 these numbers be referred to Dr Wollaston’s 
 oxygen scale, we shall have,— - 
 
 Theory. Expt. 
 
 2 primes carbonic acid, 5.50 55,66 54.50 
 
 1 ammonia, 2.13 21.56 22.80 
 
 2 water, 2.25 22.78 22.75 
 
 These near approximations to the equiva- 
 
 lent ratios in compounds of a variable na- 
 ture, do not seem to have attracted notice 
 at the time. Dr Thomson describes in his 
 System the solid subcarbonate found in the 
 shops as indefinite in the proportion of its 
 constituents. In the 14th Number of the 
 Journal of Science, his friend, Mr Phillips, 
 whose attention to minute accuracy is well 
 known, has published an ingenious paper on 
 the, subject, which begins with the following 
 handsome acknowledgment of my labours : 
 “ During some late researches, my attention 
 being directed to the composition of the car- 
 bonates of ammonia, I began, and had nearly 
 completed an examination of them, before I 
 observed that they had been recently analyz- 
 ed by Dr Ure ; and I consider his results 
 to be so nearly accurate, that I should have 
 suppressed mine, if I had not noticed some 
 circumstances respecting the compounds in 
 question, which have, I believe, hitherto 
 escaped observation.” 
 
 Mr Phillips’s communication is valuable. 
 It presents a luminous systematic view of 
 the carbonates of ammonia and soda. Dr 
 Thomson, in his Annals for July 1820, 
 enumerates that account of the carbonates of 
 ammonia among the improvements made in 
 1819, without any allusion to my experi- 
 ments on the ammoniacal salts, published in 
 
 his own Magazine, nearly three years before 
 he printed his retrospect. 
 
 The indications of the above analytical 
 instrument are so minute, as to enable us, by 
 the help of tire old and well known theorem 
 for computing the proportions of two metals 
 from the specific gravity of an alloy, to de- 
 duce the proportions of the bases from the 
 volume of gas disengaged by a given weight 
 of a mixed carbonate. A chemical problem 
 of this nature was practically solved by me, 
 in presence of two distinguished Professors 
 of the University of Dublin, in May 1816. 
 But such an application is more curious than 
 useful, since a slight variation in the quantity 
 of gas, as well as accidental admixtures of 
 other substances, are apt to occasion consi- 
 derable errors. It determines, however, the 
 nature and value of a limestone with suffi- 
 cient practical precision. As 100 grains of 
 magnesian limestone yield 99 cubic inches 
 of gas, a convenient rule for it is formed 
 when we say, that 10 grains will yield 10 
 cubic inches. In the same way marles and 
 common limestones may be examined, by 
 subjecting a certain number of grains, in a 
 graduated syphon tube, to the action of a 
 little muriatic acid over mercury. From, the 
 bulk of evolved gas , expressed in cubic inches 
 and tenths , deduct l- c 20th y the remainder will 
 express the proportion of' real limestone pre- 
 sent in the grains employed.* 
 
 * Carbonate of Barytes. See Withe- 
 rite.* 
 
 * Carbonate of Lime. See Calcareous 
 Spar.* 
 
 * Carbonate of Strontian. See Strox- 
 tian and Heavy Spar.* 
 
 * Carbonic Acid. See Acid Carbo- 
 
 nic. * 
 
 * Carbonic Oxide. A gaseous com- 
 pound of one prime equivalent of carbon, 
 and one of oxygen, consisting by weight of 
 0.75 of the former, and 1.00 of the latter. 
 Hence the prime of the compound is 1.75, 
 the same as that of azote. This gas cannot 
 be formed by the chemist by the direct com- 
 bination of its constituents ; for at the tem- 
 perature requisite for effecting a union, the 
 carbon attracts its full dose of oxygen, and 
 thus generates carbonic acid. It may be 
 procured by exposing charcoal to a long con- 
 tinued heat. The last products consist chiefly 
 of carbonic oxide. 
 
 To obtain it pure, however, our only plan 
 is to abstract one proportion of oxygen from 
 carbonic acid, either in its gaseous state, or 
 as condensed in the carbonates. Thus by 
 introducing well calcined charcoal into a 
 tube traversing a furnace, as is represented 
 plate I. fig. 2. ; and, when it is heated to 
 redness, passing over it backwards and tor- 
 wards, by means of two attached mercurial 
 gasometers or bladders, a slow current ot 
 carbonic acid, we convert the acid into an 
 
CAR 
 
 CAR 
 
 oxide more bulky than itself. Each prime 
 of the carbon becomes now associated with 
 only one of oxygen, instead of two, as 
 before. The carbon acting here, by its su- 
 perior mass, is enabled to effect the thorough 
 saturation of the oxygen. 
 
 If we subject to a strong heat, in a gun 
 barrel or retort, a mixture of any dry earthy 
 carbonate, such as chalk, or carbonate of 
 strontites, with metallic filings or charcoal, 
 the combined acid is resolved as before into 
 the gaseous oxide of carbon. The most 
 convenient mixture is equal parts of diied 
 chalk and iron, or zinc filings. By passing 
 a numerous succession of electric explosions 
 through one volume of carbonic acid, con- 
 fined over mercury, two volumes of carbonic 
 oxide, and one of oxygen, are formed, ac- 
 cording to Sir H. Davy. 
 
 The specific gravity of this gas is stated 
 by Gay Lussac and Thenard, from theoreti- 
 cal considerations, to be 0.96782, though 
 Mr Cruickshank’s experimental estimate 
 was 0.9569. As the gas is formed by with- 
 drawing from a volume of carbonic acid half 
 a volume of oxygen, while the bulk of the 
 gas remains unchanged, we obtain its specific 
 gravity by subtracting from that of carbonic 
 acid half the specific gravity of oxygen. 
 Hence 1.5277 — 0.5555 = 0.9722, differ- 
 ing slightly from the above, in consequence 
 of the French chemists rating the specific 
 gravity of the two original gases at 1.51961 
 and 1.10359. Hence 100 cubic inches 
 weigh 29|- grains at mean pressure and 
 temperature. 
 
 This gas burns with a dark-blue flame. 
 Sir H. I)avy has shewn, that though carbo- 
 nic oxide in its combustion produces less 
 heat than other inflammable gases, it may be 
 kindled at a much lower temperature. It 
 inflames in the atmosphere, when brought 
 into contact with an iron wire heated to dull 
 redness, whereas carburetted hydrogen is not 
 inflammable by a similar wire, unless it is 
 heated to whiteness, so as to burn with 
 sparks. It requires, for its combustion, half 
 its volume of oxygen gas, producing one 
 volume of carbonic acid. It is not decom- 
 posable by any of the simple combustibles, 
 except potassium and sodium. When pot- 
 assium is heated in a portion of the gas, pot- 
 ash is formed with the precipitation of char- 
 coal, and the disengagement of heat and light. 
 Perhaps iron, at a high temperature, would 
 condense the oxygen and carbon by its strong 
 affinity for these substances. Water con- 
 denses jjj of its bulk of the gas. The above 
 processes are those usually prescribed in our 
 systematic works, for procuring the oxide of 
 carbon. In some of them, a portion of car- 
 bonic acid is evolved, which may be with- 
 drawn by washing the gaseous product with 
 weak solution of potash, or milk of lime. 
 We avoid the chance of this impurity by ex- 
 
 tricating the gas from a mixture of dry car- 
 bonate of barytes and iron filings, or of oxide 
 of zinc, and previously calcined charcoal. 
 The gaseous product, from the first mixture, 
 is pure oxide of carbon. Oxide of iron, and 
 pure barytes, remain in the retort. Carbonic 
 oxide, when respired, is fatal to animal life. 
 Sir H. Davy took three inspirations of it, 
 mixed with about one-fourth of common air; 
 the effect was a temporary loss of sensation, 
 which was succeeded by giddiness, sickness, 
 acute pains in different parts of the body, 
 and extreme debility. Some days elapsed 
 before he entirely recovered. Since then, 
 Mr Witter of Dublin was struck down in 
 an apoplectic condition, by breathing this 
 gas ; but he was speedily restored, by the 
 inhalation of oxygen. See an interesting 
 account of this experiment, by Mr Witter, 
 in the Phil. Mag. vol. 43. 
 
 When a mixture of it and chlorine is ex- 
 posed to sunshine, a curious compound, dis- 
 covered by Dr John Davy, is formed, to 
 which he gave the name of phosgene gas. I 
 shall describe its properties in treating of 
 chlorine. It has been called chlorocarbonic 
 acid, though chlorocarbonous acid seems a 
 more appropriate name.* 
 
 * Carbuncle, a gem highly prized by the 
 ancients, probably the alamandine , a variety 
 of noble Garnet.* 
 
 * Carburet of Sulphur. Called also sul- 
 phuret of carbon, and alcohol of sulphur. 
 
 This interesting liquid was originally ob- 
 tained by Lampadius in distilling a mixture 
 of pulverized pyrites and charcoal in an 
 earthen retort, and w r as considered by him as 
 a peculiar compound of sulphur and hydro- 
 gen. But MM. Clement and Desormes, 
 with the precision and ingenuity which dis- 
 tinguish all their researches, first ascertained 
 its true constitution to be carburetted sul- 
 phur ; and they invented a process of great 
 simplicity, for at once preparing it, and prov- 
 ing its nature. Thoroughly calcined char- 
 coal is to be put into a porcelain tube, that 
 traverses a furnace, at a slight angle of in- 
 clination. To the higher end of the tube, a 
 retort of glass, containing sulphur, is luted ; 
 and to the low r er end is attached an adopter 
 tube, which enters into a bottle with tw T o 
 tubulures, half full of w r atcr, and surrounded 
 with very cold water or ice. From the 
 other aperture of the bottle, a bent tube pro- 
 ceeds into the pneumatic trough. When 
 the porcelain tube is brought into a state of 
 ignition, heat is applied to the sulphur, 
 which subliming into the tube, combines 
 with the charcoal, forming the liquid car- 
 buret. The conclusive demonstration of 
 such an experiment was however questioned 
 by M. Berthollet, jun. and Ouzel. But 
 MM. Berthollet, Thenard and Vauquelin, 
 the reporters on M. ( luzcl’s memoir, having 
 made some experiments of their own upon 
 
CAR 
 
 CAR 
 
 the subject, concluded that the liquid in 
 question was a compound of sulphur and 
 carbon only, 
 
 linally, an excellent paper was written on 
 the carburet by M. Berzelius and Dr Marcet, 
 who confirmed the results of MM. Clement 
 and Desormes, and added likewise several 
 important facts. 
 
 If about ten parts of well calcined char- 
 coal in powder, mixed with fifty parts of 
 pulverized native pyrites (bisulphuret of 
 iron J, be distilled from an earthen retort, 
 into a tubulated receiver surrounded with 
 ice, more than one part of sulphuret of car- 
 bon may be obtained. If we employ the 
 elegant process of M. Clement, we must 
 take care that the charcoal be perfectly cal- 
 cined, otherwise no carburet will be obtained. 
 In their early experiments, they attached to 
 the higher end of the porcelain tube a glass 
 one, containing the sulphur in small pieces, 
 and pushed these successively forwards by a 
 wire passing air-tight through a cork, at the 
 upper end of the tube. 
 
 Besides the liquid carburet, there is form- 
 ed some carburetted and sulphuretted hy, 
 drogen, and a reddish-brown solid and very 
 combustible matter, which seems to be sul- 
 phur slightly carburetted. This substance 
 remains almost entirely in the adopter tube. 
 The liquid carburet occupies the bottom of 
 the receiver bottle, and may be separated 
 from the supernatant water, by putting the 
 whole into a funnel, whose tube is closed 
 with the finger, and letting the denser brown 
 carburet flow out below, whenever the dis- 
 tinction of the liquid into two strata is com- 
 plete. Thus obtained, the carburet is always 
 yellowish, containing a small excess of sul- 
 phur, which may be removed by distillation 
 from a glass retort, plunged in water, at a tem- 
 perature of 1 1 5°. It is now transparent 
 and colourless, of a penetrating, fetid smell, 
 and an acrid burning taste. Its specific 
 gravity varies from 1.263 to 1.272. Ac- 
 cording to Dr Marcet, it boils below 110°; 
 according to M. Thenard at 115° F. ; and 
 the tension of its vapour at 72.5° is equiva- 
 lent to a column of 12.53 inches of mer- 
 cury. At 53.5°, according to Marcet and 
 Berzelius, the tension is equivalent to a co- 
 lumn of 7.4 inches, or one-fourth of the 
 mean atmospheric pressure ; hence one- 
 third is added to the bulk of any portion 
 of air, with which the liquid may be mixed. 
 A spirit of wine thermometer, having its 
 bulb surrounded with cotton cloth or lint, if 
 dipped in sulplmret of carbon, and suspend- 
 ed in the air, sinks from 60° to 0°. If it 
 be put into the receiver of an air pump, and 
 a moderate exhaustion be made, it sinks 
 rapidly from 60° to — 81°. If a tube con- 
 taining mercury be treated in the same way, 
 the mercury may be readily frozen even in 
 summer. The drier the air in the receiver, 
 
 the more easily is the cold produced. Hence 
 the presence of sulphuric acid may be of 
 some service in removing the vapour from 
 the air in the receiver. 
 
 This carburet may be cooled to — 80° 
 without congealing ; a conclusive proof that 
 combination changes completely the consti- 
 tution of bodies, since two substances usually 
 solid, form a fluid which we cannot solidify. 
 When a lighted body approaches the sur- 
 face of the carburet, it immediately catches 
 fire, and burns with a blue sulphurous 
 flame. Carbonic and sulphurous acids are 
 exhaled, and a little sulphur is deposited. 
 A heat of about 700° inflames the vapour of 
 the carburet. Oxygen dilated by it over 
 mercury explodes by the electric spark, with 
 a violent detonation. My eudiometer is pe- 
 culiarly adapted to the exhibition of this ex- 
 periment. A portion of oxygen being in- 
 troduced into the sealed leg, we pour a few 
 drops of the carburet on the surface of the 
 mercury in the open leg, and closing this 
 with the finger, transfer the liquid to the 
 other by a momentary inclination of the 
 syphon. The expansion of volume can be 
 now most accurately measured by bringing 
 the merenrv to a level in each lesr. 
 
 » o 
 
 The subsequent explosion occasions no dan- 
 ger, and a scarcely audible report. The result 
 is a true analysis, if we have mixed oxygen 
 saturated with the vapour at ordinary pres- 
 sure and temperature, with about its volume 
 of pure oxygen. Otherwise, all the sulphur 
 would not be oxygenated. We obtain, then, 
 sulphurous and carbonic acids, with the ex- 
 cess of oxygen. 
 
 The carburet of sulphur dissolves camphor. 
 It does not unite with water ; but very readily 
 with alcohol and ether. With chloride of azote 
 it forms a non-detonating compound. The 
 waters of potash, barytes, and lime, slowly de- 
 compose it, with the evolution of carbonic acid 
 gas. It combines with ammonia and lime, 
 forming carbo-sulphurets. The carburet, sa- 
 turated with ammoniacal gas, forms a yellow 
 pulverulent substance, which sublimes unal- 
 tered in close vessels, but is so deliquescent 
 that it cannot be passed from one vessel to 
 another without absorbing moisture. When 
 heated in that state, crystals of hydrosulphu- 
 ret of ammonia form. The compound with 
 lime is made bv beating some quicklime in 
 a tube, and causing the vapour of carburet to 
 pass through it. The lime becomes incan- 
 descent at the instant of combination. 
 
 When the carburet is left for some weeks 
 in contact with nitro-muriatic acid, it is con- 
 verted into a substance having very much 
 the appearance and physical properties of 
 camphor ; being soluble in alcohol and oils 
 and insoluble in water. This substance is, 
 according to Berzelius, a triple acid, com- 
 posed of two atoms of muriatic acid, one 
 atom of sulphurous acid, and one atom of 
 
CAR 
 
 CAR 
 
 carbonic acid. He calls it, muriatico-sul- 
 phurous-carbonic acid. 
 
 When potassium is heated in the vapour 
 of the carburet, it burns with a reddish flame, 
 and a black film appears on the surface. On 
 admitting water, a greenish solution of sul- 
 phuret of potash is obtained, containing a 
 mixture of charcoal. From its vapour pass- 
 ing through ignited muriate of silver, with- 
 out occasioning any reduction of the metal, 
 it is demonstrated that this carburet is desti- 
 tute of hydrogen. 
 
 When the compound of potash, water, and 
 carburet of sulphur, is added to metallic so- 
 lutions, precipitates of a peculiar kind, call- 
 ed carbo-sulphurets, are obtained. The fol- 
 lowing is a table of the colours of the preci- 
 pitates : 
 
 Muriate of Cerium, White or yellowish- 
 
 white. 
 
 Sulphate of Manga- 
 nese, 
 
 Sulphate of Zinc, 
 I’ermuriate of iron, 
 Submuriate of anti- 
 mony, 
 
 Muriate of tin, 
 
 Nitrate of cobalt, 
 
 Nitrate of lead, 
 Nitrate of copper, 
 Protomuriate of mer- 
 cury, 
 
 X’ermuriate of mer- 
 cury, 
 
 Muriate of silver, 
 
 Greenish-grey. 
 
 White. 
 l)ark red. 
 
 Orange. 
 
 Pale orange, then 
 brown. 
 
 Dark olive-green, at 
 last black. 
 
 A fine scarlet. 
 
 Dark brown. 
 
 Black, 
 
 Orange. 
 
 Reddish-brown. 
 
 Carburet of sulphur was found by Dr 
 Brewster to exceed all fluid bodies in refrac- 
 tive power, and even the solids, flint-glass, 
 topaz, and tourmaline. In dispersive power 
 it exceeds every fluid substance except oil of 
 cassia, holding an intermediate place between 
 phosphorus and balsam of tolu. 
 
 The best method of analyzing the carburet 
 of sulphur, is to pass its vapour over ignited 
 peroxide of iron ; though the analysis was 
 skilfully effected by MM. Berthollet, Vau- 
 quelin, and Thenard, by transmitting the 
 vapour through a red-hot copper tube, or a 
 porcelain one containing copper turnings. 
 Both the first method, as employed by Ber- 
 zelius, and the second, concur in shewing the 
 carburet to consist of 
 
 1 prime of carbon, 0.75 15.79 
 
 2 primes of sulphur, 4.00 84.21 
 
 4.75 100.00 
 
 Vauquelin’s experimental numbers are, 
 from 15 to 16 carbon, and from 86 to 85 
 sulphur ; and those of Berzelius and Marcct 
 are 15.17 carbon, and 84.85 sulphur, in 100 
 parts. 
 
 Of the cold produced by the evaporation 
 of the carburet of sulphur, the following ac- 
 
 count is given by Dr Thomson in the third 
 volume of bis Annals, being the extract of a 
 letter which he received from Mr J. Murray, 
 philosophical lecturer: — “ A glass of water 
 has remained on the table since the preced- 
 ing evening, and though it might be some 
 decrees below 32° Fahr. it indicated no dis- 
 position for congelation. A few drops of 
 sulphuret of carbon were applied to the sur- 
 face, instantly the globules became cased 
 with a shell of icy spicuke of retiform tex- 
 ture. Where they w ere in contact w'ith the 
 water, plumose branches darted from the 
 sulphuret as from a centre to the bottom of 
 the vessel, and the wdiole became solidified. 
 The sulphuret of carbon in the interim vola- 
 tilized, and during this period the spicules 
 exhibited the colours of the solar spectrum 
 in beautiful array.”* 
 
 * Carburetted Hydrogen Gas. Of this 
 compound gas, formerly called heavy inflam- 
 mable air, w'e have tw o species, differing in 
 the proportions of the constituents. The 
 first, consisting of 1 prime equivalent of 
 each, is carburetted hydrogen ; the second, of 
 1 prime of carbon, and 2 of hydrogen, is 
 subcarburetted hydrogen. 1. Carburetted 
 hydrogen, the percarburetted hydrogen of 
 the French chemists, is, according to Mr 
 Brande, the only definite compound of these 
 two elements. To prepare it, we mix in a 
 glass retort, 1 part of alcohol, and 4 of sul- 
 phuric acid, and expose the retort to a mo- 
 derate heat. The gas is usually received 
 over w ater : though De Saussure states that 
 this liquid absorbs more than l-7th of its 
 volume of the gas. It is destructive of ani- 
 mal life. Its specific gravity is 0.978, ac- 
 cording to Saussure. 100 cubic inches weigh 
 28.80 gr. It possesses all the mechanical 
 properties of air. It is invisible, and void of 
 taste and smell, when it has been washed 
 from a little ethereous vapour. The effect 
 of heat on this gas is curious. When passed 
 through a porcelain tube, heated to a cherry 
 red, it lets fall a portion of charcoal, and 
 nearly doubles its volume. At a higher tem- 
 perature it deposits more charcoal, and aug- 
 ments in bulk; till finally, at the greatest 
 heat to which we can expose it, it lets fall 
 almost the whole of its carbon, and assumes 
 a volume 3^ times greater than it had at 
 first. These remarkable results, observed 
 W'ith great care, have induced the illustrious 
 Berthollet to conclude, with much plausibi- 
 lity, that hydrogen and carbon combine in 
 many successive proportions. The trans- 
 mission of a scries of electric sparks through 
 this gas, produces a similar effect with that 
 of simple heat. 
 
 Carburetted hydrogen burns with a splen- 
 did white flame. When mixed with three times 
 its bulk of oxygen, and kindled by a taper 
 or the electric spark, it explodes with great 
 violence, and the four volumes are converted 
 
CAR 
 
 CAR 
 
 into two volumes of carbonic acid. But 
 two volumes ot carbonic acid contain two 
 volumes of oxygen. Ihe remaining volume 
 of oxygen therefore has been expended in 
 forming water with two volumes of hydro- 
 gen. Hence the original volume of carbu- 
 retted hydrogen was made up of these two 
 volumes of hydrogen = 0. 1398 (0.0694 X 2) 
 -f- 2 volumes of gaseous carbon = 0 . 8 . 553 , 
 constituting 1 condensed volume = 0.9731. 
 By gaseous carbon is meant the vapour of 
 this solid, as it exists in carbonic acid ; the 
 density of which vapour is found by sub- 
 tracting the specific gravity of oxygen, from 
 that of carbonic acid. Hence 1.5277 — 
 1.1111 = 0.4 1 66, represents the density of 
 gaseous carbon. M. Thenard says, that if 
 we mix the percarburetted hydrogen at once 
 with three times its volume of oxygen, the 
 eudiometer would be broken ; so sudden 
 and powerful is the expansion. The eudio- 
 meter referred to is that of Volta, which 
 costs three guineas in Paris. My eu- 
 diometer, which does not cost three shil- 
 lings, bears the explosive violence of the 
 above mixture, without any danger. (See 
 Eudiometer). When it is detonated with 
 only an equal volume of oxygen, it expands 
 greatly, and the two volumes become more 
 than three and a half. In this case only 
 1 -Sth or 1-1 Oth of a volume of carbonic acid 
 is formed ; but more than a volume and a half 
 of carbonic oxide ; a little hydrogen is con- 
 sumed, but the greatest part remains untouch- 
 ed and mixed with the carbonic oxide. It may 
 be separated by combustion with chlorine. 
 
 If we refer the weights above found, from 
 the combining volumes, to the equivalent 
 oxygen scale, we shall have the gas consist- 
 ing of 1 prime of each constituent. 
 
 For 0. 1 398 : 0 . 1 25 : : 8333 : 0. 752 ; now 
 0.125 and 0.750 represent the prime equi- 
 valents of hydrogen and carbon. 
 
 When this gas is mixed with its own bulk 
 of chlorine, the gaseous mixture is condensed 
 over water into a peculiar oily-looking com- 
 pound. Hence this carburetted hydrogen 
 was called by its discoverers, the associated 
 Dutch chemists, olefiant gas. MM. Robi- 
 quet and Colin formed this liquid in consi- 
 derable quantities, by making two currents 
 of its constituent gases meet in a glass globe. 
 The olefiant gas should be in rather larger 
 quantity than the chlorine, otherwise the li- 
 quid becomes of a green colour, and acquires 
 acid properties. When it is washed with 
 water, and distilled off dry muriate of lime, 
 it may be regarded as pure. It is then a 
 limpid colourless essence of a pleasant fla- 
 vour, and a sharp, sweet, and not disagree- 
 able taste. At 45° its specific gravity is 
 
 2 . 2201 . Its boiling point is 152°. At 49 ° 
 its vapour is said to be capable of sustaining 
 a column of 24^ inches of mercury. The 
 specific gravity of the vapour is 3 . 4434 , 
 compared to atmospheric air. But that 
 quantity is the sum of the densities of chlo- 
 rine and olefiant gas. It will consist there- 
 fore by weight of 
 
 Olefiant gas, 0.9731 (2 X 0.875) 1.75 
 
 Chlorine, 2.4733 4.45 
 
 3.4464 6.20 
 
 or two primes of the first and one of the se- 
 cond. Its ultimate constituents are there- 
 fore 1 chlorine, 2 carbon, and 2 hydrogen. 
 This essence burns with a green flame, from 
 which charcoal is deposited, and muriatic 
 acid gas flies off. Decomposition, with simi- 
 lar results, is effected by passing the liquid 
 through a red-hot porcelain tube. Its con- 
 stitution probably resembles that of muriatic 
 ether. 
 
 Olefiant gas is elegantly analyzed by heat- 
 ing sulphur in it over mercury. One cubic 
 inch of it, with 2 grains of sulphur, yields 2 
 cubic inches of sulphuretted hydrogen, and 
 charcoal is deposited. Now we know that 
 the latter gas contains just its own volume of 
 hydrogen. 
 
 2. Subcarburetted hydrogen. This gas 
 is supposed to be procured in a state of defi- 
 nite composition, from the mud of stagnant 
 pools or ditches. We have only to fill a 
 wide mouthed goblet with water, and in- 
 verting it in the ditch-water, stir the bottom 
 with a stick. Gas rises into the goblet. 
 
 The fire-damp of mines is a similar gas to 
 that of ditches. There is in both cases an 
 admixture of carbonic acid, which lime or 
 potash-water will remove. A proportion of 
 air is also present, the quantity of which can 
 be ascertained by analysis. By igniting 
 acetate of potash in a gun-barrel, an analo- 
 gous species of gas is obtained. According 
 to M. Berthollet, the sp. gr. of the carburet- 
 ted hydrogen from ditch mud, exclusive of 
 the azote, is 0.5582. 
 
 Subcarburetted hydrogen is destitute of 
 colour, taste, and smell. It burns with a 
 yellow' flame, like that of a candle. When 
 mixed w ith twice its volume of oxygen and 
 exploded, we obtain exactly its own bulk of 
 carbonic acid, while water is precipitated. 
 We can hence infer the composition of sub- 
 carburetted hydrogen. For of the two vo- 
 lumes of oxygen, one remains gaseous in the 
 carbonic acid, and another is condensed with 
 tw o volumes of hydrogen into water. 1 vo- 
 lume of vapour of carbon + 2 volumes of hydro- 
 gen, condensed into 1 volume, compose sub- 
 carburetted hydrogen gas. Thus in numbers, 
 
 1 volume of gaseous carbon =0.4166 0./5 — 1 piime 
 
 2 do. ° hydrogen =0.1398 (0.125 X 2) = 0.25 = 2 primes 
 
 0.556 4 
 
 1.00 
 
CAR 
 
 CAR 
 
 Here we see the specific gravity 0.5564, 
 is very near the determination of Berthollet. 
 We also perceive the compound prime to be 
 1.000, the same as oxygen. Berthollet says 
 that the carburetted hydrogen obtained by 
 exposing olefiant gas to an intense heat, con- 
 tains 2 of hydrogen to 1 of carbon by weight. 
 This proportion corresponds to 
 
 12 primes of hydrogen =1.5 
 
 And 1 do. of carbon = 0.75 
 
 As the gas of ditches and the choke-damp 
 of mines is evidently derived from the ac- 
 tion of water on decaying vegetable or car- 
 bonaceous matter, we can understand that 
 a similar product will be obtained by pass- 
 ing water over ignited charcoal, or by heat- 
 ing moistened charcoal or vegetable matter 
 in retorts. The gases are here, however, a 
 somewhat complex mixture, as w r ell as what 
 we obtain by igniting pit-coal and vrood in 
 iron retorts. (See Coal Gas). The com- 
 bustion of subcarburetted hydrogen with 
 common air takes place only when they are 
 mixed in certain proportions. If from 6 to 
 1 2 parts of air be mixed with 1 of carburetted 
 hydrogen, we have explosive mixtures. Pro- 
 portions beyond these limits will not ex- 
 plode. In like manner, from 1 to 2^ of 
 oxygen, must be mixed with 1 of the com- 
 bustible gas, otherwise vre have no explo- 
 sion. Sir H. Davy says that this gas has a dis- 
 agreeable empyreumatic smell, and that wa- 
 ter absorbs 1-S0th of its volume of it.* 
 
 Carica Papaya. Papaw tree. Every 
 part of the papaw tree, except the ripe fruit, 
 affords a milky juice, which is used in the 
 Isle of France as an effectual remedy for the 
 tape- worm. In Europe, however, whither 
 it has been sent in the concrete state, it has 
 not answered. 
 
 The most remarkable circumstance re- 
 garding the papaw tree, is the extraction 
 from its juice of a matter exactly resembling 
 the flesh or fibre of animals, and hence call- 
 ed vegetable fibrin; which see. 
 
 Carmine. A red pigment prepared from 
 cochineal. See Lake. 
 
 * Carnelian is a sub-species of calce- 
 dony. Its colours are white, yellow, brown, 
 and red. It has a conchoidal fracture and a 
 specific gravity of 2.6. It is semi-transparent, 
 and has a glistening lustre. It consists of 
 04 silica, 5.5 alumina, and 0.75 oxide of 
 iron. The finest specimens come from Cam- 
 bay and Surat in India. It is found in the 
 channels of torrents in Hindostan, in nodules 
 of a blackish olive, passing into grey. After 
 exposure for some weeks to the sun, these 
 are subjected to heat in earthen pots, whence 
 proceed the lively colours for which they are 
 valued in jewellery. It is softer than com- 
 mon calcedony.* 
 
 * Caromel. 1 he smell exhaled by sugar, 
 at a calcining heat. * 
 
 Carthamus, Safflower, or Bastard 
 
 Saffron. In some of the deep reddish, 
 yellow, or orange- coloured flowers, the yel- 
 low matter seems to be of the same kind w ith 
 that of the pure yellow flow'ers ; but the red 
 to be of a different kind from the pure red 
 ones. Watery menstrua take up only the 
 yellow, and leave the red, which may after- 
 ward be extracted by alcohol, or by a w r eak 
 solution of alkali. Such particularly are the 
 saffron-coloured flowers of carthamus. These, 
 after the yellow matter has been extracted 
 by water, are said to give a tincture to ley ; 
 from w'hich, on standing at rest for some 
 time, a deep red fecula subsides, called saf- 
 flower, and from the countries whence it is 
 commonly brought to us, Spanish red and 
 China lake. This pigment impregnates al- 
 cohol with a beautiful red tincture ; but com- 
 municates no colour to w;ater. 
 
 Rouge is prepared from carthamus. For 
 this purpose the red colour is extracted by 
 a solution of the subcarbonate of soda, and 
 precipitated by lemon juice, previously de- 
 purated by standing. This precipitate is 
 dried on earthen plates, mixed with talc, or 
 French chalk, reduced to a powaler by means 
 of the leaves of shave-grass, triturated with 
 it till they are both very fine, and then sifted. 
 The fineness of the pow der and proportion 
 of the precipitate constitute the difference be- 
 tween the finer and cheaper rouge. It is 
 likewise spread very thin on saucers, and sold 
 in this state for dyeing. 
 
 Carthamus is used for dyeing silk of a 
 poppy, cherry, rose, or bright orange red. 
 After the vellovv matter is extracted as above, 
 and the cakes opened, it is put into a deal 
 trough, and sprinkled at different times with 
 pearl ashes, or rather soda well powdered 
 and sifted, in the proportion of six pounds 
 to a hundred, mixing the alkali well as it is 
 put in. The alkali should be saturated with 
 carbonic acid. The carthamus is then put 
 on a cloth in a trough with a grated bottom, 
 placed on a larger trough, and cold water 
 poured on, till the large trough is filled. 
 And this is repeated, with the addition of a 
 little more alkali toward the end, till the car- 
 thamus is exhausted and become yellow. 
 Lemon juice is then poured into the bath, 
 till it is turned of a fine cherry colour, and 
 after it is w r ell stirred the silk is immersed in 
 it. The silk is wrung, drained, and passed 
 through fresh baths, washing and drying 
 after every operation, till it is of a proper 
 colour; when it is brightened in hot water 
 and lemon juice. For a poppy or fire colour 
 a slight annotta ground is first given; but 
 the silk should not be alumed. For a pale 
 carnation a little soap should be put into the 
 bath. All these baths must be used as soon 
 as they are made; and cold, because beat 
 destroys the colour of the red fecula?. 
 
 * Cartilage. An elastic, semi-transpa- 
 rent, animal solid, which remains of the 
 
CAS 
 
 CAT 
 
 shape, and one-third the weight of the bones, 
 when the calcareous salts are removed by 
 digestion in dilute muriatic acid. It resem- 
 bles coagulated albumen. Nitric acid con- 
 verts it into gelatin. With alkalis it forms 
 an animal soap. Cartilage is the primitive 
 paste, into which the calcareous salts are de- 
 posited in the young animal. In the disease 
 rickets, the earthy matter is withdrawn by 
 morbid absorption, and the bones return into 
 the state nearly of flexible cartilage. Hence 
 arise the distortions characteristic of this 
 disease.* 
 
 Case-IIaiideking. Steel when hardened 
 is brittle, and iron alone is not capable of 
 receiving the hardness steel may be brought 
 to possess. There is nevertheless a variety 
 of articles in which it is desirable to possess 
 all the hardness of steel, together with the 
 toughness of iron. These requisites are 
 united in the art of case-hardening, which 
 does not differ from the making of steel, 
 except in the shorter duration of the process. 
 Tools, utensils, or ornaments intended to be 
 polished, are first manufactured in iron and 
 nearly finished, after which they are put into 
 an iron box, together with vegetable or ani- 
 mal coals in powder, and cemented for a 
 certain time. This treatment converts the 
 external part into a coating of steel, which is 
 usually very thin, because the time allowed 
 for the cementation is much shorter than 
 when the whole is intended to be made into 
 steel. Immersion of the heated pieces into 
 water hardens the surface, which is afterward 
 polished by the usual methods. Moron’s 
 Mechanic Exercises, p. 56. gives the follovv- 
 ingreceipt: — Cow’s horn or hoof is to lie 
 baked or thoroughly dried, and pulverized. 
 To this add an equal quantity of bay salt : 
 mix them with stale chamber-ley, or white 
 wine vinegar: cover the iron with this mix- 
 ture, and bed it in the same in loam, or en- 
 close it in an iron box : lay it then on the 
 hearth of the forge to dry and harden : then 
 put it into the fire, and blow till the lump 
 have a blood-red heat, and no higher, lest 
 the mixture be burned too much. Take 
 the iron out, and immerse it in water to 
 harden. 
 
 * Caseic Acid. The name which Proust 
 gave to a substance of an acid nature, which 
 he extracted from cheese ; and to which he 
 ascribes many of the properties of this species 
 of food. * 
 
 * Cassava. An American plant, theja- 
 tropha manihat , contains the nutritive starch 
 cassava, curiously associated with a deadly 
 poisonous juice. The roots of jatropha are 
 squeezed in a bag. The cassava remains in 
 it; and the juice, which is used by the In- 
 dians to poison their arrows, gradually lets 
 fall some starch of an innocent and very nu- 
 tritious quality. The whole solid matter is 
 
 dried in smoke, ground, and made into 
 bread. * 
 
 * Cassius’s purple precipitate. See Gold.* 
 
 Castor. A soft greyish-yellow or light 
 
 brown substance, found in four hags in the 
 inguinal region of the beaver. In a warm 
 air it grows by degrees hard and brittle, and 
 of a darker colour, especially when dried in 
 chimneys, as is usually done. According to 
 Bouillon La Grange, it consists of a muci- 
 lage, a bitter extract, a resin, an essential oil, 
 in whieh its peculiar smell appears to reside, 
 and a flaky crystalline matter, much resem- 
 bling the adipocere of biliary calculi. 
 
 Castor is regarded as a powerful antispas- 
 modic. 
 
 Catechu. A brown astringent substance 
 formerly known by the name of Japan earth. 
 It is a dry extract, prepared from the wood 
 of a species of sensitive plant, the mimosa 
 catechu. It is imported into this country 
 from Bombay and Bengal. According to 
 Sir H. Davy, who analyzed it, that from 
 Bombay is of uniform texture, red- brown 
 colour, and specific gravity 1.39: that from 
 Bengal is more friable and less consistent, of 
 a chocolate colour externally, but internally 
 chocolate, streaked with red-brown, and spe- 
 cific gravity 1.28. The catechu from either 
 place differs little in its properties. Its taste 
 is astringent, leaving behind a sensation of 
 sweetness. It is almost wholly soluble in 
 water. 
 
 Two hundred grains of picked catechu 
 from Bombay afforded 109 grains of tannin, 
 68 extractive matter, 13 mucilage, 10 resi- 
 duum, chiefly sand and calcareous earth. 
 The same quantity from Bengal : tannin 97 
 grains, extractive matter 73, mucilage 16, 
 residual matter, being sand, with a small 
 quantity of calcareous and aluminous earths, 
 14. Of the latter the darkest parts appear- 
 ed to afford most tannin, the lightest most 
 extractive matter. The Hindoos prefer the 
 lightest coloured, which has probably most 
 sweetness, to chew with the betel-nut. 
 
 Of all the astringent substances we know, 
 catechu appears to contain the largest pro- 
 portion of tannin, and Mr Purkis found, 
 that one pound was equivalent to seven or 
 eight of oak bark for the purpose of tanning 
 leather. 
 
 As a medicine it lias been recommended 
 as a powerful astringent, and a tincture of 
 it is used for this purpose, hut its aqueous 
 solution is less irritating. Made into troches 
 with gum aruhic and sugar it is an elegant 
 preparation, and in this wav is said much to 
 assist the cleai^iess of the voice, and to be 
 remarkably serviceable in disorders of the 
 throat. 
 
 * Cat’s Eye. A mineral of a beautilu 
 appearance, brought from Ceylon. 
 
 Its colours are grey, green, brown, red, o 
 
CEL 
 
 CEM 
 
 various shades. Its internal lustre is shin- 
 ing, its fracture imperfectly conchoidal, and 
 it is translucent. From a peculiar play of 
 light, arising from white libres interspersed, 
 it has derived its name. The French call 
 the appearance chatoyant. It scratches 
 quartz, is easily broken, and resists the blow- 
 pipe. Its sp. gr. is *2.64. Its constituents 
 are, according to Klaproth, 9 5 silica, 1.75 
 alumina, 1.5 lime, and 0.25 oxide of iron. 
 It is valued for setting as a precious stone.* 
 
 Caustic (Lunar). Fused nitrate of sil- 
 ver. See Silver. 
 
 Causticity. All substances which have 
 so strong a tendency to combine with the 
 principles of organized substances, as to de- 
 stroy their texture, are said to be caustic. 
 The chief of these are the concentrated acids, 
 pure alkalis, and the metallic salts. 
 
 * Cautery Potential. Caustic.* 
 
 Cawk. A term by which the miners dis- 
 tinguish the opaque specimens of sulphate of 
 barytes. 
 
 * Celestine. Native sulphate of stron- 
 tites. This mineral is so named from its 
 occasional delicate blue colour ; though it is 
 frequently found of other shades, as white, 
 greyish and yellowish- white, and red. It 
 occurs both massive and crystallized. Some- 
 times also in fibrous and stellated forms. 
 According to Haiiy, the primitive form is a 
 right rhomboid al prism, of 104° 48' and 75° 
 12'. The reflecting goniometer makes these 
 angles 104° and 7 6°. The varieties of its 
 crystals may be referred to four or six-sided 
 prisms, terminated by two, four, or eight-sided 
 summits. It has a shining lustre, and is ei- 
 ther transparent, translucent, or opaque. It 
 scratches calcareous spar, but is scratched by 
 fluor. It is very brittle. Its sp. gr. is 3.6. 
 Before the blow-pipe it fuses into a white, 
 opaque, and friable enamel. 
 
 The three sub-species are, 1st, The com- 
 pact found in Montmartre near Paris, of a 
 yellowish-grey colour, in rounded pieces, of 
 a dull lustre, opaque, and consisting, bv 
 Vauquelin’s analysis, of 91.42 sulphate of 
 strontites, 8.33 carbonate of lime, and 0.25 
 oxide of iron. 2d, The fibrous, whose co- 
 lours are indigo-blue and bluish-grey ; some- 
 times white. It occurs both massive and 
 crystallized. Shining and somewhat pearly 
 lustre. It is translucent. Sp. grav. 3.83. 
 3d, 1 he foliated, ot a milk-white colour, 
 falling into blue. Massive and in grouped 
 crystals, of a shining lustre and straight foli- 
 ated texture. Translucent. Celestine occurs 
 most abundantly near Bristol in the red 
 marie formation ; and crystallized in red 
 sandstone, at Inverness in Scotland. 
 
 Mr Gruncr Ober Berg of Ilanover has 
 lately favoured the world with an analysis of 
 a crystallized celestine, found in the neigh- 
 bourhood ot that city, of rather peculiar 
 composition. Its sp. gr. is only 3.59, and 
 
 yet it contains a large proportion of sulphate 
 of barytes : 
 
 Sulphate of strontites, 
 
 73.000 
 
 Sulphate of barytes, 
 
 26.166 
 
 Ferruginous clay, 
 
 0.213 
 
 Loss, 
 
 0.621 
 
 - 
 
 100.000 
 
 Had the result been 75 of sulphate of stron- 
 tites -|- 25 sulphate of barytes, we should 
 have considered the mineral as a compound 
 of 4 primes of the first salt -f- 1 of the se- 
 cond. Now the analysis, in my opinion, 
 cannot be confided in, within these limits; 
 for the mingled muriates of the earths were 
 separated by digestion in 16 times their 
 weight of boiling alcohol, of a strength nofc 
 named. Besides, the previous perfect con- 
 version of the sulphates into carbonates, by 
 merely fusing the mineral with thrice its 
 weight of carbonate of potash, is, to say the 
 least, problematical. I)r Thomson adapts 
 M. Ober Berg’s analysis to 7 atoms of sul- 
 phate of strontian, and 2 atoms of sulphate 
 of barytes.* 
 
 Cement. Whatever is employed to unite 
 or cement together things of the same or 
 different kinds, may be called a cement. In 
 this sense it includes lutes, glues, and sol- 
 ders of every kind, which see ; but it is more 
 commonly employed to signify those of which 
 the basis is an earth or earthy salt. See 
 Lime. We shall here enumerate, chiefly 
 from the Philosophical Magazine, some ce- 
 ments that are used for particular purposes. 
 
 Seven or eight parts of resin, and one of 
 wax, melted together, and mixed with a 
 small quantity of plaster of Paris, is a very 
 good cement to unite pieces of Derbyshire 
 spar, or other stone. The stone should be 
 made hot enough to melt the cement, and 
 the pieces should be pressed together as 
 closely as possible, so as to leave as little as 
 may be of the cement between them. This 
 is a general rule in cementing, as the thin- 
 ner the stratum of cement interposed, the 
 firmer it will hold. 
 
 Melted brimstone used in the same way 
 will answer sufficiently well, if the joining 
 be not required to be very strong. 
 
 It sometimes happens, that jewellers, in 
 setting precious stones, break off pieces by 
 accident ; in this case they join them so that 
 it cannot easily be seen, with gum mastic, 
 the stone being previously made hot enough 
 to melt it. By the same medium cameos of 
 white enamel or coloured glass are often 
 joined to a real stone as a ground, to produce 
 the appearance of an onyx. Mastic is like- 
 wise used to cement false backs or doublets 
 to stones, to alter their hue. 
 
 The jewellers in Turkey, who are gene- 
 rally Armenians, ornament watch-cases and 
 other trinkets with gems, by glueing them 
 on. The stone is set in silver or gold, and 
 
CEM 
 
 GEM 
 
 the hack ot the setting made flat to corres- 
 pond with the part to which it is to be ap- 
 plied. It is then iixed on with the following 
 cement, j Isinglass, soaked in water till it 
 swells up and becomes soft, is dissolved in 
 French brandy, or in rum, so as to form a 
 strong glue. 1 wo small bits of gum gal- 
 banum, or gum ammoniacum, are dissolved 
 in two ounces of this by trituration ; and 
 five or six bits of mastic, as big as peas, 
 being dissolved in as much alcohol as will 
 render them fluid, are to be mixed witli this 
 by means of a gentle heat. This cement is 
 to be kept in a phial closely stopped ; and 
 when used, it is to be liquefied by immers- 
 ing the phial in hot water. This cement re- 
 sists moisture. 
 
 A solution of shell lac in alcohol, added to 
 a solution of isinglass in proof spirit, makes 
 another cement that will resist moisture. 
 
 So does common glue melted without 
 water, with half its weight of resin, with the 
 addition of a little red ochre to give it a 
 body. This is particularly useful for ce- 
 menting hones to their frames. 
 
 If clay and oxide of iron be mixed with 
 oil, according to Mr Gad of Stockholm, they 
 will form a cement that will harden under 
 water. 
 
 A strong cement, insoluble in water, may 
 be made from cheese. The cheese should 
 be that of skimmed milk, cut into slices, 
 throwing away the rind, and boiled till it 
 becomes a strong glue, which however does 
 not dissolve in the water. This water being 
 poured off, it is to be washed in cold water, 
 and then kneaded in warm water. This 
 process is to be repeated several times. The 
 glue is then to be put warm on a levigating 
 stone, and kneaded with quicklime. This 
 cement may he used cold, but it is better to 
 warm it ; and it will join marble, stone, or 
 earthen-ware, so that the joining is scarcely 
 to be discovered. 
 
 Boiled linseed oil, litharge, red lead, and 
 white lead, mixed together to a proper con- 
 sistence, and applied on each side of a piece 
 of flannel, or even linen or paper, and put 
 between two pieces of metal before they are 
 brought home, or close together, will make a 
 close and durable joint, that will resist boil- 
 ing water, or even a considerable pressure of 
 steam. The proportions of the ingredients 
 are not material, but the more the red lead 
 predominates, the sooner the cement will 
 dry, and the more the white lead the con- 
 trary. This cement answers well for join- 
 ing stones of any dimensions. 
 
 The following is an excellent cement for 
 iron, as in time it unites with it into one 
 mass. Take two ounces of muriate of am- 
 monia, one of flowers of sulphur, and 16 of 
 cast-iron filings or borings. Mix them well 
 in a mortar, and keep the powder dry. 
 
 When the cement is wanted for use, take 
 one part of this mixture, twenty parts of 
 clear iron borings or filings, grind them to- 
 gether in a mortar, mix them with water to 
 a proper consistence, and apply them be- 
 tween the joints. 
 
 Powdered quicklime mixed with bullock’s 
 blood is often used by coppersmiths, to lay 
 over the rivets and edges of the sheets of 
 copper in large boilers, as a security to the 
 junctures, and also to prevent cocks from 
 leaking. 
 
 Six parts of clay, one of iron filings, and 
 linseed oil sufficient to form a thick paste, 
 make a good cement for stopping cracks in 
 iron boilers. 
 
 Temporary cements are wanted in cutting, 
 grinding, or polishing optical glasses, stones, 
 and various small articles of jewellery, which 
 it is necessary to fix on blocks, or handles, 
 for the purpose. Four ounces of resin, a 
 quarter of an ounce of wax, and four ounces of 
 whiting made previously red-hot, form a good 
 cement of this kind ; as any of the above ar- 
 ticles may be fastened to it by heating them, 
 and removed at pleasure in the same man- 
 ner, though they adhere very firmly to it 
 when cold* Fitch, resin, and a small quan- 
 tity of tallow, thickened with brick-dust, is 
 much used at Birmingham for these pur- 
 poses. Four parts of resin, one of bees 
 wax, and one of brick-dust, likewise make a 
 good cement. This answers extremely well 
 for fixing knives and forks in their halts ; 
 but the manufacturers of cheap articles of this 
 kind too commonly use resin and brick-dust 
 alone. On some occasions, in which a very 
 tough cement is requisite, that will not crack 
 though exposed to repeated blows ; as in 
 fastening to a block metallic articles that are 
 to he cut with a hammer and punch, work- 
 men usually mix some tow with the cement, 
 the fibres of which hold its parts together. 
 
 * Mr Singer recommends the following 
 composition as a good cement for electrical 
 apparatus : Five pounds of resin, one of bees 
 wax, one of red ochre, and two table spoon- 
 fuls of plaster of Paris, all melted together. 
 A cheaper one for cementing voltaic plates 
 into wooden troughs is made with six pounds 
 of resin, one pound of red ochre, half a 
 pound of plaster of Paris, and a quarter of 
 a pint of linseed oil. The ochre and plaster 
 of Paris should he well dried, and added to 
 the other ingredients, in a melted state. * 
 
 * Cement, for buildings. See Mortar 
 Cements.* 
 
 Cementation. A chemical process, which 
 consists in surrounding a body in the solid 
 state with the pow der of some other bodies, 
 and exposing the whole for a time in a clos- 
 ed vessel, to a degree of heat not sufficient 
 to fuse the contents. Thus iron is converted 
 into steel by cementation w ith charcoal ; 
 
CER 
 
 CER 
 
 green bottle glass is converted into porcelain 
 by cementation with sand, &c. See Ikon and 
 Porcelain. 
 
 * Cerasin. The name given by Dr John 
 of Berlin to those gummy substances which 
 swell in cold water, but do not readily dis- 
 solve in it. Cerasin is soluble in boiling water, 
 but separates in a jelly when the water cools. 
 Water acidulated with sulphuric, nitric, or 
 muriatic acid, by the aid of a gentle heat, 
 forms a permanent solution of cerasin. Gum 
 tragacanth is the best example of this species 
 of vegetable product. * 
 
 * Cerate. The compound of oil or lard 
 with bees wax, used by surgeons to screen 
 ulcerated surfaces from the air. * 
 
 * Ceiun. A peculiar substance which 
 precipitates, on evaporation, from alcohol, 
 which has been digested on grated cork. 
 Subercerin would have been a fitter name. 
 Chevreul, the discoverer, describes this sub- 
 stance as consisting of small white needles, 
 which sink and merely soften in boiling 
 water. 1000 parts of boiling alcohol dissolve 
 2.42 of cerin, and only 2 of wax. Nitric 
 acid converts it into oxalic acid. It is inso- 
 luble in an alcoholic solution of potash.* 
 
 * Cerin. The name given by Dr John 
 to the part of common wax which dissolves 
 in alcohol.* 
 
 * Cerin. A variety of the mineral alla- 
 nite, lately examined by Berzelius. It con- 
 sists of oxide of cerium 28. 1 9, oxide of iron 
 20.72, oxide of copper 0.87, silica 30.17, 
 alumina 11.31, lime 9.12, volatile water 
 0.40.* 
 
 * Cerite. The siliciferous oxide of ce- 
 rium. This rare mineral is of a rose-red or 
 flesh-red colour, occasionally tinged with 
 clove- brown. Its powder is reddish-grey. 
 It is found massive and disseminated. In- 
 ternal lustre resinous, but scarcely glimmer- 
 ing. Its fracture is fine splintery, with in- 
 determinate fragments. It is opaque, scratch- 
 es glass, gives sparks with steel, is difficult to 
 break, scarcely yields to the knife, and gives 
 a greyish-white streak. It is infusible before 
 the blow-pipe ; but heat changes the grey 
 colour of the powder to yellow. It consists, 
 by Ilisinger’s analysis, of 18 silica, 68.59 
 oxide of cerium, 2 oxide of iron, 1.25 lime, 
 9.6 water and carbonic acid, and 0.56 loss, 
 in 100 parts. Klaproth found 54.5 oxide of 
 cerium, and 34.5 silica, in the hundred parts. 
 It is found only in the copper mine of Bast- 
 naes near Riddarhytta in Sweden, accom- 
 panied by the ores of copper, molybdena, 
 and bismuth. Its sp. gr. is from 4.6 to 4.9.* 
 
 * Cerium. The metal whose oxide exists 
 in the preceding mineral.* 
 
 To obtain the oxide of the new' metal, the 
 cerite is calcined, pulverized, and dissolved 
 in nitromuriatic acid. The filtered solution 
 being neutralized with pure potash, is to he 
 precipitated by tartrate of potash ; and the 
 
 precipitate, well washed, and afterward cal- 
 cined, is oxide of cerium. 
 
 * The attempts to obtain the pure metal, 
 by igniting the oxide, purified from iron by 
 oxalic acid, in contact with tartaric acid, oil, 
 and lampblack, have in a great measure fail- 
 ed. A white brittle carburet was only ob- 
 tained. * 
 
 Cerium is susceptible of two stages of 
 oxidation ; in the first it is white, and this 
 by calcination becomes of a fallow-red. 
 
 The white oxide exposed to the blow-pipe 
 soon becomes red, but does not melt, or even 
 agglutinate. With a large proportion of bo- 
 rax it fuses into a transparent globule. 
 
 The white oxide becomes yellowish in the 
 open air, but never so red as by calcination, 
 because it absorbs carbonic acid, which pre- 
 vents its saturating itself with oxygen, and 
 retains a portion of water, which diminishes 
 its colour. 
 
 Alkalis do not act on it ; but caustic pot- 
 ash in the dry way takes part of the oxygen 
 from the red oxide, so as to convert it into 
 the white without altering its nature. 
 
 * The protoxide of cerium is composed 
 by Hisinger of 85.17 metal -j- 14.83 oxy- 
 gen, and the peroxide of 79.3 metal -|- 20.7. 
 The protoxide has been supposed a binary 
 compound of cerium 5.75 -{- oxygen 1, and 
 the peroxide acompoundof 5.75 X 2 of ceri- 
 um -j- 3 oxygen. An alloy of this metal with 
 iron w as obtained by Vauquelin. 
 
 The salts of cerium are white or yellow 
 coloured, have a sw r eet taste, yield a white 
 precipitate with hydrosulphuret of potash, 
 but none with sulphuretted hydrogen ; a 
 milk-white precipitate, soluble in nitric and 
 muriatic acids, with ferroprussiate of potash 
 and oxalate of ammonia, none with infusion 
 of galls, and a white one with arseniate of 
 potash.* 
 
 Equal parts of the sulphuric acid and red 
 oxide, with four parts of water, unite by the 
 assistance of heat into a crystalline mass ; 
 which may be completely dissolved by add- 
 ing more acid, and heating them together 
 a long time. This solution yields, by gentle 
 evaporation, small crystals, some of an orange, 
 others of a lemon colour. The sulphate of 
 cerium is soluble in water only with an ex- 
 cess of acid. Its taste is acid and saccharine. 
 The sulphuric acid combines readily with 
 the white oxide, particularly in the state of 
 carbonate. The solution has a saccharine 
 taste, and readily affords w-hite crystals. 
 
 Nitric acid does not readily dissolve the 
 red oxide without, heat. With an excess of 
 acid, white deliquescent crystals are formed, 
 which are decomposable by heat. Their 
 taste is at first pungent, afterward very su- 
 gary. The white oxide unites more readily 
 with the acid. 
 
 Muriatic acid dissolves the red oxide with 
 effervescence. The solution crystallizes con- 
 
Cl I A 
 
 CHA 
 
 fusedly. The salt is deliquescent, soluble 
 in an equal weight of cold water, and in 
 three or four times its weight of alcohol. 
 The flame of this solution, if concentrated, 
 is yellow and sparkling ; if not, colourless ; 
 but on agitation it emits white, red, and pur- 
 ple sparks. 
 
 Carbonic acid readily unites with the 
 oxide. This is best done by adding car- 
 bonate of potash to the nitric and muriatic 
 solution of the white oxide, when a light 
 precipitate will be thrown down, which on 
 drying assumes a shining silvery appearance, 
 and consists of 23 acid + 65 oxide + 12 
 water. 
 
 The white oxide unites directly with tar- 
 taric acid, but requires an excess to render it 
 soluble. 
 
 * Cerumen of the ear. It is a yellow co- 
 loured secretion, which lines the external 
 auditory canal, rendered viscid and concrete 
 by exposure to air. It has a bitter taste, 
 melts at a low heat, and evolves a slightly 
 aromatic odour. On ignited coals, it gives 
 out a white smoke, similar to that of burn- 
 ing fat, swells, emits a fetid ammoniacal 
 odour, and is converted into a light coal. 
 Alcohol dissolves f of it, and on evaporation 
 leaves a substance resembling the resin of 
 bile. The j which remained are albumen 
 mixed with oil, which by incineration leave 
 soda and phosphate of lime. Hence, the 
 whole constituents are five ; albumen, an in- 
 spissated oil, a colouring matter, soda, and 
 calcareous phosphate. * 
 
 Ceruse, or White Lead. See Lead. 
 
 * Cetine. The name given by Chevreul to 
 spermaceti. According to Berard, who ana- 
 lyzed it on M. Gay Lussac’s plan, by passing 
 its vapour through ignited peroxide of cop- 
 per, cetine consists of 81 carbon, 6 oxygen, 
 and 13 hydrogen, in 100 parts. * 
 
 * Ceylanite. This mineral, the pleonaste 
 of Haiiv, comes from Ceylon, commonly in 
 rounded pieces, but occasionally in crystals. 
 The primitive form of its crystals is a regular 
 octohedron, in which form, or with the edges 
 truncated, it frequently occurs. Its colour is 
 indigo-blue, passing into black, which on 
 minute inspection appears greenish. It has 
 a rough surface, with little external lustre, 
 but splendent internally. The fracture is 
 perfect flat conchoidal, with very sharp-edged 
 fragments. It scarcely scratches quartz, 
 and is softer than spinell. It is easily broken, 
 has a sp. gr. of 3.77, and is infusible by the 
 blow-pipe. * 
 
 * Char a site. This mineral occurs in 
 
 crystals, whose primitive form is nearly a 
 cube, since the angle at the summit is only 
 93^°. It is found in that form, and also 
 with 6 of its edges truncated, and the trunca- 
 tures united 3 and 3 at the two opposite 
 angles, while the other six angles arc truncat- 
 
 ed. It occurs also in double six-sided pyra- 
 mids, applied base to base, having the six 
 angles at the base, and the three acute edges 
 of each pyramid truncated. It is white, or 
 with a tinge of rose colour, and sometimes 
 transparent. It scratches glass, fuses by the 
 blow-pipe into a white spongy mass, and has 
 a sp. gr. of 2.72. Its constituents are 43.33 
 silica, 22.66 alumina, 3.34 lime, 9.54 soda 
 and potash, water 21. It is found in scatter- 
 ed crystals iu the fissures of some trap rocks, 
 and in the hollows of certain geodes , disse- 
 minated in the same rocks. It occurs in the 
 quarry of Alteberg near Oberstein. * 
 
 Chalk. A very common species of cal- 
 careous earth, of an opaque white colour, very 
 soft, and without the least appearance of a 
 polish in its fracture. Its specific gravity is 
 from 2.4 to 2. 6, according to Kirwan. It 
 contains a little siliceous earth, and about 
 two per cent of clay. Some specimens, and 
 perhaps most, contain a little iron, and Berg- 
 man affirms that muriate of lime, or magnesia, 
 is often found in it ; for which reason he di- 
 rects the powder of chalk to be several times 
 boiled in distilled water, before it is dissolved 
 for the purpose of obtaining pure calcareous 
 earth. 
 
 * Chalk (Black). Drawing slate. The 
 colour of this mineral is greyish or bluish- 
 black. Massive. The principal fracture is 
 glimmering and slaty, the cross fracture dull, 
 and fine earthy. It is in opaque, tabular 
 fragments, stains paper black, streak glisten- 
 ing, and the same colour as the surface ; easily 
 cut and broken ; sp. gr. 2.4. ; becomes red in 
 the fire, and falls to pieces in water. It oc- 
 curs in primitive mountains, often accom- 
 panied by alum slate. It is used in crayon 
 drawing, whence its name.*' 
 
 * Chalk Stones. Gouty concretions whose 
 true nature was first discovered by Dr Wol- 
 laston, and described by him in his admirable 
 dissertation on urinary calculi, published in 
 the Phil. Trans, for 1797. See Gouty 
 Concretions.* 
 
 Chalk (Red). This is a clay coloured 
 by the oxide of iron, of which it contains 
 from 16 ' to 18 parts in the hundred, accord- 
 ing to Rinman. 
 
 Chalk (Spanish). The soap rock is fre- 
 quently distinguished by this name. 
 
 Characters (Chemical). The chemical 
 characters were invented by the earlier che- 
 mists, probably with no other view than to 
 save time in writing the names of substances 
 that frequently occurred, in the same manner 
 as w T e avoid repetitions b v the use of pronouns. 
 But the moderns seem to have considered 
 them as relics of alchcmistical obscurity, and 
 have almost totally rejected their use. ^ cry 
 little of system appears in the ancient charac- 
 ters of chemists : the characters of Bergman 
 are chiefly grounded on the ancient characters, 
 
CHA 
 
 with additions and improvements. But the 
 characters of Hassenfratz and Adet are 
 systematical throughout. The former are 
 exhibited in Plate III. and the latter in Plate 
 IV. 
 
 Charcoal. When vegetable substances 
 are exposed to a strong heat in the apparatus 
 for distillation, the fixed residue is called 
 charcoal. For general purposes, wood is 
 converted into charcoal by building it up in 
 a pyramidal fonn, covering the pile with clay 
 or earth, and leaving a few air-holes, which 
 are closed as soon as the mass is well lighted; 
 and by this means the combustion is carried 
 on in an imperfect manner. In the forest of 
 Benon, near Ptochelle, great attention is paid 
 to the manufacture, so that the charcoal 
 made there fetches 25 or 30 per cent more 
 than any other. The wood is that of the 
 black oak. It is taken from ten to fifteen 
 years old, the trunk as well as the branches, 
 cut into billets about four feet long, and not 
 split. The largest pieces, however, seldom 
 exceed six or seven inches in diameter. The 
 end that rests on the ground is cut a little 
 sloping, so as to touch it merely with an 
 edge, and they are piled nearly upright, but 
 never in more than one storey. The wood is 
 covered all over about four inches thick with 
 dry grass or fern, before it is enclosed in the 
 usual manner with clay; and when the wood 
 is charred, half a barrel of water is thrown 
 over the pile, and earth to the thickness of 
 five or six inches is thrown on, after which 
 it is left four- and- twenty hours to cool. The 
 
 CHA 
 
 wood is always used in the year in which it 
 is cut. 
 
 In charring wood it has been conjectured, 
 that a portion of it is sometimes converted 
 into a pyrophorus, and that the explosions 
 that happen in powder-mills are sometimes 
 owing to this. 
 
 * Charcoal is made on the great scale, by 
 igniting wood in iron cylinders, as I have 
 described under Acetic Acid. When the 
 resulting charcoal is to be used in the ma- 
 nufacture of gunpowder, it is essential that 
 the last portion of vinegar and tar be suf- 
 fered to escape, and that the reabsorption of 
 the crude vapours be prevented, by cutting 
 off the communication between the interior 
 of the cylinders and the apparatus for con- 
 densing the pyrolignous acid, whenever the 
 fire is withdrawn from the furnace. If this 
 precaution be not observed, the gunpowder 
 made with the charcoal would be of inferior 
 quality. 
 
 In the third volume of Tilloch’s Maga- 
 zine, we have some valuable facts on char- 
 coal, by Mr Mushet. He justly observes, 
 that the produce of charcoal in the small way, 
 differs from that on the large scale, in wdiich 
 the quantity of char depends more upon the 
 hardness, and compactness of the texture of 
 wood, and the skill of the workman in ma- 
 naging the pyramid of faggots, than on the 
 absolute quantity of carbon it contains. The 
 following is his table of results, reduced to 
 100 parts, from experiments on one pound 
 avoirdupois of wood. 
 
 Parts in 100. 
 
 
 Volatile 
 
 Matter. 
 
 Charcoal. 
 
 Oak, 
 
 76.895 
 
 22.682 
 
 Ash, 
 
 81.260 
 
 17.972 
 
 Birch, 
 
 80.717 
 
 17.491 
 
 Norway Pine, 
 
 80.441 
 
 1 9.204 
 
 Mahogany, 
 
 73.528 
 
 25.492 
 
 Sycamore, 
 
 79.20 
 
 19.734 
 
 Holly, 
 
 78.92 
 
 19.918 
 
 Scotch Pine, 
 
 83.095 
 
 16.456 
 
 Beech, 
 
 79.104 
 
 19.941 
 
 Klin, 
 
 79.655 
 
 19.574 
 
 Walnut, 
 
 78.521 
 
 20.663 
 
 American Maple, 
 
 79.331 
 
 19.901 
 
 Do. Black Beech, 
 
 77.512 
 
 21.445 
 
 Laburnum, 
 
 74.234 
 
 24.586 
 
 Lignum Vita;, 
 
 72.643 
 
 26.857 
 
 Sallow, 
 
 80.371 
 
 18.497 
 
 Chesnut, 
 
 76. 304 
 
 23.280 
 
 MM. Clement and Dcsormes say, that 
 ood affords one- half its weight of charcoal. 
 
 r 
 
 Ashes. 
 
 Charcoal by 
 
 Proust. 
 
 Rumford. 
 
 0.423 
 
 20. 
 
 43.00 
 
 0.768 
 
 1.792 
 
 17. 
 
 
 0.355 
 
 20. 
 
 Black Ash. 
 
 44.18 
 
 0.980 
 
 1.066 
 
 25. 
 
 Willow. 
 
 
 1.162 
 
 17. 
 
 Heart of Oak. 
 
 
 0.449 
 0. 955 
 
 19. 
 
 
 0.761 
 
 
 43.27 
 
 0.816 
 
 
 
 0.768 
 
 Guiacum. 
 
 42.23 
 
 1.033 
 
 1.180 
 
 24. 
 
 Poplar. 
 
 0.500 
 
 1.132 
 
 
 43.57 
 
 Lime. 
 
 0.416 
 
 
 43.59 
 
 consider the statements of Mr Mushet and 
 M. Proust, much more correct. They coin- 
 
 I 
 
CHE 
 
 cide with the experiments to which I have 
 referred in treating of the extraction of vine- 
 gar from wood. (See Acetic Acid). M. 
 Proust pays, that good pit-coals afford 70, 75, 
 or 80 per cent of charcoal or coak ; from 
 which only two or three parts in the hun- 
 dred of ashes remain after combustion. Til - 
 hch.'s Mag. vol. vi-ii.* 
 
 Charcoal is black, sonorous, and brittle, 
 and in general retains the figure of the ve- 
 getable it was obtained from. If, however, 
 the vegetable consist for the most part of 
 water or other fluids, these in their extrica- 
 tion will destroy the connexion of the more 
 fixed parts. In this case the quantity of 
 charcoal is much less than in the former. 
 The charcoal of oily or bituminous sub- 
 stances is of a light pulverulent form, and 
 rises in soot. This charcoal of oils is called 
 lamp black. A very fine kind is obtained 
 from burning alcohol. 
 
 Turf or peat has been charred lately in 
 France, it is said by a peculiar process, and, 
 according to the account given in Sonn ini’s 
 Journal, is superior to wood for this pur- 
 pose. Charcoal of turf kindles slower than 
 that of wood, but emits more flame, and 
 burns longer. In a goldsmith’s furnace it 
 fusqd eleven ounces of gold in eight 
 minutes, while wood charcoal required six- 
 teen. The malleability of the gold, too, was 
 preserved in the former instance, but not in 
 the latter. Iron heated red-hot by it in a 
 forge, was rendered more malleable. 
 
 From the scarcity of wood in this coun- 
 try, pit-coal charred, is much used instead of 
 charcoal by the name of Coak. See Carbon. 
 
 Chat, or Chaya-Root. This is the root 
 of the Oldenlandia umbellala , which grows 
 wild on the coast of Coromandel, and is 
 likewise cultivated there for the use of the 
 dyers and calico printers. It is used for 
 the same purposes as madder with us, to 
 which it is said to be far superior, giving the 
 beautiful red so much admired in the Ma- 
 dras cottons. 
 
 Cheese. Milk consists of butter, cheese, 
 a saccharine matter called sugar of milk, 
 and a small quantity of common salt, to- 
 gether with much water. 
 
 If any vegetable or mineral acid be mix- 
 ed with milk, the cheese separates, and, if 
 assisted by heat, coagulates into a mass. 
 The quantity of cheese is less when a mine- 
 ral acid is used. Neutral salts, and likewise 
 all earthy and metallic salts, separate the 
 cheese from the whey. Sugar and gum- 
 arabic produce the same effect. Caustic 
 alkalis will dissolve the curd by the assist- 
 ance of a boiling heat, and acids occasion a 
 precipitation again. Vegetable acids have 
 very little solvent power upon curd. This 
 accounts for a greater quantity of curd being 
 
 obtained when a vegetable acid is used. 
 
 ' 6 
 
 But what answers best is rennet, which is 
 made by macerating in water a piece of the 
 last stomach of a calf, salted and dried for 
 this purpose. 
 
 Scheele observed, that cheese has a consider- 
 able analogy to albumen, which it resembles 
 in being coagulable by fire and acids, solu- 
 ble in ammonia, and affording the same 
 products by distillation or treatment with 
 nitric acid. There are, however, certain 
 differences between them. Rouelle observ- 
 ed likewise, a striking analogy between 
 cheese and the gluten of wheat, and that 
 found in the feculre of green vegetables. 
 By kneading the gluten of wheat with a 
 little salt and a small portion of a solution 
 of starch, he gave it the taste, smell, and 
 unctuosity of cheese, so that after it had 
 been kept a certain time, it was not to be 
 distinguished from the celebrated Rochefort 
 cheese, of which it had all the pungency. 
 This caseous substance from gluten, as well 
 as the cheese of milk, appears to contain 
 acetate of ammonia, after it has been kept 
 long enough to have undergone the requisite 
 fermentation, as may be proved by examin- 
 ing it with sulphuric acid, and with potash. 
 The pungency of strong cheese, too, is de- 
 stroyed bv alcohol. 
 
 * In the 11th volume of Tilloch’s Ma- 
 gazine there is an excellent account of the 
 mode of making Cheshire cheese, taken from 
 the Agricultural Report of the county. “ If 
 the milk,” says the reporter, “ be set to- 
 gether very warm, the curd, as before ob- 
 served, will be firm ; in this case, the usual 
 mode is to take a common case-knife, and 
 make incisions across it, to the full depth of 
 the knife’s blade, at the distance of about one 
 inch ; and again crossways in the same man- 
 ner, the incisions intersecting each other at 
 right angles. The whey rising through these 
 incisions is of a fine pale-green colour. The 
 cheese-maker and two assistants then proceed 
 to break the curd ; this is performed by their 
 repeatedly putting their hands down into the 
 tub ; the cheese-maker, with the skimming- 
 dish in one hand, breaking every part of it 
 as they catch it, raising the curd from the 
 bottom, and still breaking it. This part of 
 the business is continued till the whole is 
 broken uniformly small ; it generally takes 
 up about 40 minutes, and the curd is then 
 left covered over with a cloth for about half 
 an hour to subside. If the milk has been set 
 cool together, the curd, as before mentioned, 
 will be much more tender, the whey will not 
 be so green, but rather of a milky appear- 
 ance.” The above account of cheese-mak- 
 ing is evidently at variance with that given 
 by Dr Thomson in the 4th volume of his 
 system.* 
 
 * Chemistry may be defined, the science 
 which investigates the composition of materia 
 
CHL 
 
 CHL 
 
 substances, and the permanent changes of 
 constitution which their mutual actions pro- 
 duce. * 
 
 * Chfnopodium Olidum. A plant re- 
 markable, according to MM. Chevalier and 
 Lasseigne, for containing uncombined am- 
 monia, which is probably the vehicle of the 
 remarkably nauseous odour which it exhales, 
 strongly resembling that of putrid fish. When 
 the plant is bruised with water, and the liquor 
 expressed and afterwards distilled, we pro- 
 cure a fluid which contains the subcarbonate 
 of ammonia, and an oily matter, which gives 
 the fluid a milky appearance. If the ex- 
 pressed juice of the chenopodium be evapo- 
 rated to the consistence of an extract, it is 
 found to be alkaline ; there seems to be acetic 
 acid in it. Its basis is said to be of an albu- 
 minous nature. It is stated also to con- 
 tain a small quantity of the substance which 
 the French call osmazome, a little of an aro- 
 matic resin, and a bitter matter, soluble both 
 in alcohol and water, as well as several saline 
 i bodies. The following is stated as the result 
 of their analysis, which, however, seems some- 
 what complex : 1. Subcarbonate of ammonia, 
 2. Albumen, 3. Osmazome, 4. An aromatic 
 resin, 5. A bitter matter, 6. Nitrate of pot- 
 ash in large quantity, 7. Acetate and phos- 
 phate of potash, S. Tartrate of potash. It is 
 said that 100 parts of the dried plant produce 
 I 18 of ashes, of which 5\ are potash.* 
 
 * Chert. See Horn stone.* 
 
 * Chiastolite. A mineral crystallized in 
 
 » 
 
 four-sided, nearly rectangular prisms. On 
 looking into the end of the prism, we perceive 
 ; in the axis of it a blackish prism, surrounded 
 i by the other, which is of a greyish, yellowish, 
 or reddish-white colour. From each anHe 
 
 O 
 
 of the interior prisms, a blackish line extends 
 to the corresponding angle of the exterior. 
 In each of these outer angles there is usually 
 a small rhomboidal space, filled with the same 
 dark substance which composes the central 
 prism. The black matter is the same clay- 
 slate with the rock in which the chiastolite is 
 imbedded. Fracture, foliated with double 
 cleavage. Translucent. Scratches glass. 
 Rubbed on sealing-wax, it imparts negative 
 ) electricity. Its sp. gr. is 2.94. Before the 
 blow-pipe it is convertible into a whitish 
 enamel. J lie only-mineral with which chias- 
 tolite or made can be confounded, were it 
 not crystallized, is steatite; but the latter 
 communicates positive electricity to sealing- 
 wax. It has been found in Britanny, in the 
 Pyrenees, in the valley of Barege, and in 
 Galicia in Spain, near St James of Compos- 
 ella. The interior black crystal is properly 
 m elongated four-sided pyramid.* 
 
 * Chlorates. Compounds of chloric acid 
 vith the salifiable bases. See Chloric 
 \cid.* 
 
 * Chloric Acid. See Acm (Chloric).* 
 
 * Chlorides. Compounds of chlorine 
 
 with combustible bodies. See Chlorine and 
 the respective substances.* 
 
 * Chlorine. The introduction of this 
 term, marks an era in chemical science. It 
 originated from the masterly researches of 
 Sir H. Davy on the oxymuriatic acid gas of 
 the French school, a substance which, after 
 resisting the most powerful means of decom- 
 position which his sagacity could invent, or 
 his ingenuity apply, he declared to be, ac- 
 cording to the true logic of chemistry, an 
 elementary body, and not a compound of 
 muriatic acid and oxygen, as was previously 
 imagined, and as its name seemed to denote. 
 He accordingly assigned to it the tenn chlo- 
 rine, descriptive of its colour ; a name now 
 generally" used. The chloridic theory of com- 
 bustion, though more limited in its applica- 
 tions to the chemical phenomena of nature, 
 than the antiphlogistic of Lavoisier, may 
 justly be regarded as of equal importance to 
 the advancement of the science itself. When 
 we now survey the Transactions of the Royal 
 Society for 1808, 1809, 1810, and 1811, we 
 feel overwhelmed with astonishment at the 
 unparalleled skill, labour, and sagacity, by 
 which the great English chemist, in so short 
 a space, prodigiously multiplied the objects 
 and resources of the science, while he pro- 
 mulgated a new code of laws, flowing from 
 views of elementary action, equally profound, 
 original, and sublime. The importance of 
 the revolution produced by his researches on 
 chlorine, will justify us in presenting a de- 
 tailed account of the steps by which it has 
 been effected. How entirely the glory of 
 this great work belongs to Sir H. Davy, not- 
 withstanding some invidious attempts in this 
 country, to tear the well-earned laurel from 
 his brow, and transfer it to the French che- 
 mists, we may readily judge by the follow- 
 ing decisive facts. 
 
 The second part of the Phil. Trans, for 
 1 809 contains researches on oxymuriatic acid, 
 its nature and combinations, by Sir II. Davy, 
 from which I shall make a few interesting 
 extracts. 
 
 “ In the Bakerian lecture for ] 808,” savs 
 he, “ I have given an account of the action of 
 potassium upon muriatic acid gas, by which 
 more than one- third of its volume of hydrogen 
 is produced; and I have stated, that muriatic 
 acid can in no instance be procured from 
 oxymuriatic acid, or from dry muriates, un- 
 less water or its elements he present. 
 
 “In the second volume of the Memoir es 
 D’Arcueil, MM. Gay Lussac and Thcnard 
 have detailed an extensive series of facts, 
 upon muriatic acid, and oxymuriatic acid. 
 Some of their experiments are similar to 
 those I have detailed in the paper just re- 
 ferred to; others arc peculiarly their own, 
 and of a very curious kind ; their general 
 conclusion is, that muriatic acid gas contains 
 about one quarter of its weight of water; 
 
CHL 
 
 CHL 
 
 and that oxymuriatic acid is not decomposa- 
 ble by any substances but hydrogen, or such 
 as can form triple combinations with it. 
 
 “ One of the most singular facts that I 
 have observed on this subject, and which I 
 have before referred to, is that charcoal, even 
 when ignited to whiteness in oxymuriatic or 
 muriatic acid gases, by the voltaic battery, ef- 
 fects no change in them, if it has been pre- 
 viously freed from hydrogen and moisture, 
 by intense ignition in vacuo. 
 
 “ This experiment, which I have several 
 times repeated, led me to doubt of the exist- 
 ence of oxygen in that substance, which has 
 been supposed to contain it, above all others, 
 in a loose and active state; and to make a 
 more rigorous investigation, than had hither- 
 to been attempted for its detection.” 
 
 He then proceeds to interrogate nature, 
 with every artifice of experiment and reason- 
 ing, till he finally extorts a confession of the 
 true constitution of this mysterious muriatic 
 essence. The above paper, and his Bakerian 
 lecture, read before the Royal Society in 
 Nov. and Dec. 1810, and published in the 
 first part of their transactions for 1811, pre- 
 sent the whole body of evidence for the un- 
 decompounded nature of oxymuriatic acid 
 gas, thenceforward styled chlorine, and they 
 will be studied in every enlightened age and 
 country, as a just and splendid pattern of in- 
 ductive Baconian logic. These views were 
 slowly and reluctantly admitted by the che- 
 mical philosophers of Europe. The hypothe- 
 sis of Lavoisier, that combustion was merely 
 the combination of oxygen with a basis, had 
 become as favourite an idol with the learned, 
 as the previous hypothesis of Stahl, that one 
 phlogistic principle pervaded all combustible 
 bodies, which was either evolved in heat and 
 light, or quietly transferred to an incombus- 
 tible, imparting that inflammability to the 
 new substance, which its fonner companion 
 had secretly lost. Stahl’s idea of combustion 
 5s the more comprehensive, and may still be 
 true ; Lavoisier’s as a general proposition, is 
 certainly false. 
 
 In 1812 Sir H. Davy published his Ele- 
 ments of Chemical Philosophy, containing 
 a systematic account of his new doctrines con- 
 cerning the combination of simple bodies. 
 Chlorine is there placed in the same rank 
 with oxygen, and finally removed from the 
 class of acids. In 1815, M. Thenard pub- 
 lished the first volume of his Traite de Chi- 
 mie Elementaire Theorique ct Pratique. I his 
 distinguished chemist, the fellow-labourer of 
 M. Gay Lussac, in those able researches on 
 the alkalis and oxymuriatic acid, which 
 
 form the honourable rivalrv of the French 
 
 * 
 
 school to the brilliant career of Sir II. Davy, 
 states at page 584. of the above volume, the 
 composition of oxymuriatic acid as follows: 
 “ Composition. The oxygenated muriatic 
 gas, contains the half of its volume of oxy- 
 
 gen gas, not including that which we may 
 suppose in muriatic acid. It thence follows, 
 that it is formed of 1.9185 of muriatic acid, 
 and 0.5517 of oxygen ; for the specific gra- 
 vity of oxygenated muriatic gas is 2.47, and 
 that of oxygen gas, 1.1054.” “ M. Chene- 
 
 vix first determined the proportion of its 
 constituent principles. MM. Gay Lussac 
 and Thenard determined it more exactly, and 
 shewed that we could not decompose the 
 oxygenated muriatic gas, but by putting it in 
 contact with a body capable of uniting with 
 the two elements of this gas, or with muria- 
 tic acid. They announced at the same time, 
 that they could explain all the phenomena 
 which it presents, by considering it as a sim- 
 ple, or as a compound body. However, this 
 last opinion appeared more probable to them. 
 M. Davy on the contrary, embraced the first, 
 admitted it exclusively, and sought to fortify 
 it, by experiments which are peculiar to him.” 
 P. 585. 
 
 In the second volume of M. Thenard’s 
 •work, published in 1814, he explains the 
 mutual action of chlorine and ammonia 
 gases, solely on the oxygenous theory. “ On 
 peut demontrer par ce dernier procede, que 
 le gas muriatique oxigene doit contenir la 
 moitie de son volume d’oxigene, uni a l’acide 
 muriatique.” P.147. — In the 4th volume 
 which appeared in 1816, we find the follow- 
 ing passages : “ Oxygenated muriatic gas . 
 Oxygenated muriatic gas, in combining with 
 the metals, gives rise to the neutral muriates. 
 Now, 107.6 of oxide of silver, contain 7.6 of 
 oxygen, and absorb 26.4 of muriatic acid, to 
 pass to the state of neutral muriate. Of 
 consequence, 348 of this last acid supposed 
 dry, and 100 of oxygen, form this gas. But 
 the sp, gr. of oxygen is 1.1034, and that of 
 oxygenated muriatic gas is 2.47 ; hence, this 
 contains the half of its volume of oxygen.” 
 P. 52. 
 
 The force of Sir II. Davy’s demonstra- 
 tions, pressing for six years on the pub- 
 lic mind of the Frencli philosophers, now 
 begins to transpire in a note to the above 
 passage. — “ We reason here,” says M. 
 Thenard, “ obviously, on the hypothesis, 
 which consists in regarding oxygenated 
 muriatic gas as a compound body.” This 
 pressure of public opinion becomes conspi- 
 cuous at the end of the volume. Among 
 the additions, we have the following decisive 
 evidence, of the lingering attachment to the 
 old theory of Lavoisier and Berthollet. — “ A 
 pretty considerable number of persons who 
 have subscribed for this work, desiring a de- 
 tailed explanation of the phenomena, which 
 oxygenated muriatic gas presents, on the 
 supposition that this gas is a simple body, 
 we are now going to explain these pheno- 
 mena, on this supposition, by considering 
 them attentively. The oxygenated muriatic 
 gas will take the name cf chlorine ; its com- 
 
CHL 
 
 CHL 
 
 binations with phosphorus, sulphur, azote, 
 metals, will be called chlorures ; the muria- 
 tic acid, which results from equal parts in 
 volume of hydrogen and oxygenated muria- 
 tic gases, will be hydrochloric acid; the 
 superoxygenated muriatic acid, will be 
 chlorous acid ; and the hyperox ygena ted 
 muriatic, chloric acid ; the first, comparable 
 to the hydriodic acid, and the last to the 
 iodic acid.” In fact, therefore, we evident- 
 ly see, that so far from the chloridic theory 
 originating in France, as has been more 
 than insinuated, it was only the researches 
 on iodine, so admirably conducted by M. 
 Gay Lussac, that by their auxiliary attack 
 of the oxygen hypothesis, eventually opened 
 the minds of its adherents, to the evidence 
 long ago advanced by Sir H. Davy. It will 
 be peculiarly instructive, to give a general 
 outline of that evidence, which has been mu- 
 tilated in some systematic works on chemis- 
 try, or frittered away into fragments. 
 
 Sir H. Davy subjected oxymuriatie gas, 
 to the action of many simple combustibles, 
 as well as metals, and from the compounds 
 formed, endeavoured to eliminate oxygen, 
 by the most energetic powers of affinity and 
 voltaic electricity, but without success, as the 
 1 following abstract will shew. 
 
 I lf oxymuriatie acid gas be introduced into 
 a vessel exhausted of air, containino; tin ; 
 and the tin be gently heated, and the gas in 
 sufficient quantity, the tin and the gas disap- 
 pear, and a limpid fluid, precisely the same 
 as Libavius’s liquor, is formed : If this sub- 
 t stance is a combination of muriatic acid and 
 oxide of tin, oxide of tin ought to be separ- 
 1 ated from it by means of ammonia. He ad- 
 > mitted ammoniacal gas over mercury to a 
 small quantity of the liquor of Libavius ; it 
 was absorbed with great heat, and no gas 
 was generated ; a solid result was obtained, 
 which was of a dull white colour : some of it 
 ■was heated, to ascertain if it contained oxide 
 of tin ; but the whole volatilized, producing 
 dense pungent fumes. 
 
 Another experiment of the same kind, 
 made with great care, and in which the am- 
 monia was used in great excess, proved that 
 the liquor of Libavius cannot be decom- 
 pounded by ammonia; but that it forms a 
 new combination with this substance. 
 
 He made a considerable quantity of the 
 solid compound of oxymuriatie acid and phos- 
 I phorus by combustion, and saturated it with 
 ammonia, by heating it in a proper receiver 
 filled with ammoniacal gas, on which it acted 
 with great energy, producing much heat ; 
 and they formed a white opaque powder. 
 Supposing that this substance was composed 
 of the dry muriates and phosphates of am- 
 monia ; as muriate o! ammonia is very vola- 
 tile, and as ammonia is driven off from phos- 
 phoric acid, by a heat below redness, he con- 
 ceived that, by igniting the product obtained, 
 
 lie should procure phosphoric acid ; he there- 
 fore introduced some of the powder into a 
 tube of green glass, and heated it to redness, 
 out of the contact of air, by a spirit lamp ; 
 but found, to his great surprise, that it was 
 not at all volatile nor decomposable at this 
 degree of heat, and that it gave off no gase- 
 ous matter. 
 
 The circumstance, that a substance com- 
 posed principally of oxymuriatie acid, and 
 ammonia, should resist decomposition or 
 change at so high a temperature, induced 
 him to pay particular attention to the pro- 
 perties of this new body. 
 
 It has been said, and taken for granted by 
 many chemists, that when oxymuriatie acid 
 and ammonia act upon each other, water is 
 formed ; he several times made the experi- 
 ment, and was convinced that this is not the 
 case. 
 
 He mixed together sulphuretted hydrogen- 
 
 in a high degree of purity, and oxymuriatie 
 
 acid gas, both dried, in equal volumes. In this. 
 
 instance the condensation was not -J— ; sul- 
 
 4 0 
 
 phur, which seemed to contain a little oxy- 
 muriatic acid, was formed on the sides of the 
 vessel ; no vapour was deposited ; and the 
 residual gas contained about JLH of muriatic 
 
 acid gas, and the remainder was inflammable. 
 
 When oxymuriatie acid is acted upon by 
 nearly an equal volume of hydrogen, a com- 
 bination takes place between them, and mu- 
 riatic acid gas results. When muriatic acid 
 gas is acted on by mercury, or any other me- 
 tal, the oxymuriatie acid is attracted from 
 the hydrogen, by the stronger affinity of the 
 metal ; and an oxymuriate, exactly similar to 
 that formed by combustion, is produced. 
 
 The action of water upon those com- 
 pounds, which have been usually considered 
 as muriates, or as dry muriates, but which 
 are properly combinations of oxymuriatie 
 acid with inflammable bases, may be easily 
 explained, according to these views of the 
 subject. When water is added in certain 
 quantities to Libavius’s liquor, a solid crys- 
 tallized mass is obtained, from which oxide 
 of tin and muriate of ammonia can be pro- 
 cured by ammonia. In this case, oxygen 
 may be conceived to be supplied to the tin, 
 and hydrogen to the oxymuriatie acid. 
 
 The compound formed by burning phos- 
 phorus in oxymuriatie acid, is in a similar 
 relation to water. If that substance be add- 
 ed to it, it is resolved into two powerful 
 acids; oxygen, it may be supposed, is fur- 
 nished to the phosphorus to form phosphoric 
 acid, hydrogen to the oxymuriatie acid to 
 form common muriatic acid gas. 
 
 He caused strong explosions from an elec- 
 trical jar to pass through oxymuriatie gas, 
 by means of points of platina, for several 
 hours in succession; but it seemed not to 
 undergo the slightest change. 
 
 He electrized the oxy muriates of phos- 
 
CHL 
 
 CIIL 
 
 phorus and sulphur for some hours, by the 
 power of the voltaic apparatus of 1000 
 double plates. No gas separated, but a mi- 
 nute quantity of hydrogen, which he was in- 
 clined to attribute to the presence of mois- 
 ture in the apparatus employed ; for he once 
 obtained hydrogen from Libavius’s liquor by 
 a similar operation. But he ascertained that 
 this was owing to the decomposition of wa- 
 ter adhering to the mercury ; and in some 
 late experiments made with 2000 double 
 plates, in which the discharge was from pla- 
 tina wires, and in which the mercury used 
 for confining the liquor was carefully boiled, 
 there was no production of any permanent 
 elastic matter. 
 
 Few substances, perhaps, have less claim 
 to be considered as acid, than oxymuriatic 
 acid- As yet we have no right to say that 
 it has been decompounded ; and as its ten- 
 dency of combination is with pure inflam- 
 mable matters, it may possibly belong to the 
 same class of bodies as oxygen. 
 
 May it not in fact be a peculiar acidifying 
 and dissolving principle, forming compounds 
 with combustible bodies, analogous to acids 
 containing oxygen or oxides, in their proper- 
 ties and powers of combination ; but differ- 
 ing from them, in being for the most part 
 decomposable by water? On this idea mu- 
 riatic acid may be considered as having hy- 
 drogen for its basis, and oxymuriatic acid for 
 its acidifying principle. And the phosphoric 
 sublimate as having phosphorus for its basis, 
 and oxymuriatic acid for its acidifying matter. 
 And Libavius’s liquor, and the compounds of 
 arsenic with oxymuriatic acid, may be regard- 
 ed as analogous bodies. The combinations 
 of oxymuriatic acid with lead, silver, mer- 
 cury, potassium, and sodium, in this view, 
 would be considered as a class of bodies re- 
 lated more to oxides than acids, in their 
 powers of attraction. — Bale. Z.cc. 1809. 
 
 On the Combinations of the Common Metals 
 with Oxygen and Oxymuriatic Gas. 
 
 Sir H. used in all cases small retorts of green 
 glass, containing from three to six cubical 
 inches, furnished with stop-cocks. The me- 
 tallic substances were introduced, the retort 
 exhausted and filled with the gas to be acted 
 upon, heat was applied by means of a spirit- 
 lamp, and after cooling, the results were 
 examined, and the residual gas analyzed. 
 
 All the metals that he tried, except silver, 
 lead, nickel, cobalt, and gold, when heated, 
 burnt in (he oxymuriatic gas, and the vola- 
 tile metals with flame. Arsenic, antimony, 
 tellurium, and zinc, with a white flame, 
 mercury with a red flame. lin became 
 ignited to whiteness, and iron and copper to 
 redness ; tungsten and manganese to dull 
 redness ; platina was scarcely acted upon at 
 the heat of fusion of the glass. 
 
 The product from mercury was corrosive 
 
 sublimate. That from zinc was similar in 
 colour to that from antimony, but was much 
 less volatile. 
 
 Silver and lead produced horn-silver and 
 horn-lead, and bismuth, butter of bismuth. 
 
 In acting upon metallic oxides by oxy- 
 muriatic gas, he found that those of lead, 
 silver, tin, copper, antimony, bismuth, and 
 tellurium, were decomposed in a heat below 
 redness, but the oxides of the volatile metals 
 more readily than those of the fixed ones. 
 The oxides of cobalt and nickel w ere scarce- 
 ly acted upon at a dull red-heat. The red 
 oxide of iron was not affected at a strong 
 red-heat, whilst the black oxide was readily 
 decomposed at a much lower temperature ; 
 arsenical acid underwent no change at the 
 greatest heat that could be given it in the 
 glass retort, whilst the white oxide readily 
 decomposed. 
 
 In cases where oxygen was given off, it 
 was found exactly the same in quantity as 
 that which had been absorbed by the metal. 
 Thus two grains of red oxide of mercury ab- 
 sorbed of a cubical inch of oxymuriatic 
 gas, and afforded 0.45 of oxygen. Two 
 grains of dark olive oxide from calomel de- 
 composed by potash, absorbed about ythI 
 of oxymuriatic gas, and afforded of 
 
 oxygen, and corrosive sublimate was produc- 
 ed in both cases. 
 
 In the decomposition of the white oxide of 
 zinc, oxygen was expelled exactly equal to 
 half the volume of the oxymuriatic acid ab- 
 sorbed. In the case of the decomposition of 
 the black oxide of iron, and the white oxide 
 of arsenic, the changes that occurred were of 
 a very beautiful kind ; no oxygen was given 
 off in either case, but butter of arsenic and 
 arsenical acid formed in one instance, and 
 the ferruginous sublimate and red oxide of 
 iron in the other. 
 
 General Conclusions and Observations , illus- 
 trated by Experiments. 
 
 Oxymuriatic gas combines with inflam- 
 mable bodies, to form simple binary com- 
 pounds ; and in these cases, when it acts 
 upon oxides, it either produces the expulsion 
 of their oxygen, or causes it to enter into 
 new combinations. 
 
 If it be said that the oxygen arises from 
 the decomposition of the oxymuriatic gas 
 and not from the oxides, it may be asked, 
 why it is always the quantity contained in 
 the oxide? and why in some cases, as those 
 
 W I 
 
 of the peroxides of potassium and sodium, it 
 bears no relation to the quantity of gas ? 
 
 If there existed anv acid matter in oxy- 
 
 * 
 
 muriatic gas, combined with oxygen, it 
 ought to be exhibited in the fluid compound 
 of one proportion of phosphorus, and two < f 
 oxymuriatic gas ; for this, on such an as- 
 sumption, should consist oi muriatic acid 
 
CIIL 
 
 CHL 
 
 (on the old hypothesis, free from water) and 
 phosphorous acid ; but this substance has no 
 effect on litmus paper, and does not act un- 
 der common circumstances on fixed alkaline 
 bases, such as dry lime or magnesia. Oxy- 
 muriatic gas, like oxygen, must be combined 
 in large quantity with peculiar inflammable 
 matter, to form acid matter. In its union 
 with hydrogen, it instantly reddens the driest 
 litmus paper, though a gaseous body. Con- 
 trary to acids, it expels oxygen from prot- 
 oxides, and combines with peroxides. 
 
 When potassium is burnt in oxymuriatic 
 gas, a dry compound is obtained. It potas- 
 sium combined with oxygen is employed, 
 the whole of the oxygen is expelled, and the 
 same compound formed. It is contrary to 
 sound logic to say, that this exact quantity 
 of oxygen is given off from a body not known 
 to be compound, when w r e are certain of its 
 existence in another ; and all the cases are 
 parallel. 
 
 Scheele explained the bleaching powers of 
 the oxymuriatic gas, by supposing that it 
 destroyed colours by combining with phlo- 
 giston. Berthollet considered it as acting 
 by supplying oxygen. He made an experi- 
 ment, which seems to prove that the pure 
 gas is incapable of altering vegetable colours, 
 and that its operation in bleaching depends 
 entirely upon its property of decomposing 
 water, and liberating its oxygen. 
 
 He filled a glass globe, containing dry 
 •pow'dered muriate of lime, wdth oxymuriatic 
 gas. He introduced some dry paper tinged 
 with litmus that had been just heated, into 
 another globe containing dry muriate of 
 lime ; after some time this globe was ex- 
 hausted, and then connected with the globe 
 containing the oxymuriatic gas, and by an 
 appropriate set of stop-cocks, the paper w F as 
 exposed to the action of the gas. No change 
 of colour took place, and after two days 
 there was scarcely a perceptible alteration. 
 
 Some similar paper dried, introduced into 
 gas that had not been exposed to muriate of 
 lime, was instantly rendered white. 
 
 It is generally stated in chemical books, 
 that oxymuriatic gas is capable of being con- 
 densed and crystallized at a low tempera- 
 ture. He found by several experiments 
 that this is not the case. The solution of 
 oxymuriatic gas in water freezes more readily 
 than pure water, but the pure gas dried by 
 muriate of lime undergoes no change what- 
 ever, at a temperature of 40 below 0° of 
 Fahrenheit. The mistake seems to have 
 arisen from the exposure of the gas to cold 
 in bottles containing moisture. 
 
 lie attempted to decompose boracic and 
 phosphoric acids by oxymuriatic gas, but with- 
 out success ; from which it seems probable, 
 that the attractions of boracium and phos- 
 phorus for oxygen are stronger than for oxy- 
 muriatic gas. And from the experiments 
 
 already detailed, iron and arsenic are analo- 
 gous in this respect, and probably some 
 other metals. 
 
 Potassium, sodium, calcium, strontium, 
 barium, zinc, mercury, tin, lead, and proba- 
 bly silver, antimony, and gold, seem to have 
 a stronger attraction for oxymuriatic gas 
 than for oxygen. 
 
 “ To call a body which is not known to 
 contain oxygen, and which cannot contain 
 muriatic acid, oxymuriatic acid, is contrary 
 to the principles of that nomenclature in 
 which it is adopted ; and an alteration of it 
 seems necessary to assist the progress of dis- 
 cussion, and to diffuse just ideas on the sub- 
 ject. If the great discoverer of this sub- 
 stance had signified it by any simple name, 
 it would have been proper to have recurred 
 to it ; but dephlogisticated marine acid is a 
 term which can hardly be adopted in the 
 present advanced era of the science. 
 
 After consulting some of the most emi- 
 nent chemical philosophers in this country, 
 it has been judged most proper to suggest a 
 name founded upon one of its obvious and 
 characteristic properties — its colour, and to 
 call it chlorine , or chloric gas. 
 
 Should it hereafter be discovered to be 
 compound, and even to contain oxygen, this 
 name can imply no error, and cannot neces- 
 sarily require a change. 
 
 Most of the salts w hich have been called 
 muriates, are not known to contain any mu- 
 riatic acid, or any oxygen. Thus Libavius’s 
 liquor, though converted into a muriate by 
 water, contains only tin and oxymuriatic gas, 
 and horn-silver seems incapable of being con- 
 verted into a true muriate.” — Bak. Lee. 1811. 
 
 We shall now exhibit a summary view of 
 the preparation and properties of chlorine. 
 
 Mix in a mortar 3 parts of common salt 
 and 1 of black oxide of manganese. Intro- 
 duce them into a glass retort, and add 2 
 parts of sulphuric acid. Gas will issue, 
 w hich must be collected in the water-pneuma- 
 tic trough. A gentle heat will favour its ex- 
 trication. In practice, the above pasty- con- 
 sistenced mixture is apt to boil over into the 
 neck. A mixture of liquid muriatic acid and 
 manganese is therefore more convenient for 
 the production of chlorine. A very slight 
 heat is adequate to its expulsion from the re- 
 tort. Instead of manganese, red oxide of 
 mercury, or puce-coloured oxide of lead, 
 may be employed. 
 
 This gas, as we have already remarked, is 
 of a greenish-yellow colour, easily recogniz- 
 ed by day-light, hut scarcely distinguishable 
 by that of candles. Its odour and taste are 
 disagreeable, strong, and so characteristic, 
 that it is impossible to mistake it for any 
 other gas. When we breathe it, even much 
 diluted with air, it occasions a sense of stran- 
 gulation, constriction of the thorax , and a 
 copious discharge from the nostrils. If 
 
CHL 
 
 CKL 
 
 
 respired in larger quantity, it excites violent 
 coughing, with spitting ot blood, and would 
 speedily destroy the individual, amid violent 
 distress. Its specific gravity is 2.4733. 
 lliis is better inferred from the specific gra- 
 vities of hydrogen and muriatic acid gases, 
 than from the direct weight of chlorine, from 
 the impossibility of confining it over mercury. 
 One volume of hydrogen, added to one of 
 chlorine, form two of the acid gas. Hence, 
 if from twice the specific gravity of muriatic 
 gas =: 2.5427, we subtract that of hydro- 
 gen = O.OG94, the difference 2.4733 is the 
 sp. gr. of chlorine. 100 cubic inches at mean 
 pressure and temperature weigh 75d grains. 
 See Gas. 
 
 In its perfectly dry state, it has no effect 
 on dry vegetable colours. With the aid of 
 a little moisture, it bleaches them into a 
 yellowish- white. Scheele first remarked this 
 bleaching property ; Berlhollet applied it to 
 the art of bleaching in France, and from 
 him Mr Watt introduced its use into Great 
 Britain. 
 
 If a lighted wax taper be immersed rapid- 
 ly into this gas, it consumes very fast, with a 
 dull reddish flame, and much smoke. The 
 taper will not burn at the surface of the gas. 
 Hence, if slowly introduced, it is apt to be 
 extinguished. The alkaline metals, as well 
 as copper, tin, arsenic, zinc, antimony, in 
 fine laminae or filings, spontaneously burn in 
 chlorine. Metallic chlorides result. Phos- 
 phorus also takes fire at ordinary tempera- 
 tures, and is converted into a chloride. Sul- 
 phur may be melted in the gas without tak- 
 ing fire. It forms a liquid chloride, of a 
 reddish colour. When dry, it is not altered 
 by any change of temperature. Enclosed in 
 a phial with a little moisture, it concretes 
 into crystalline needles, at 40° Fahr. 
 
 According to M. Thenard, water con- 
 denses, at the temperature of 68° F. and at 
 29.92 barom. 1^ times i-s volume of chlo- 
 rine, and forms aqueous chlorine, formerly 
 called liquid oxymuriatic acid. This com- 
 bination is best made in the second bottle of 
 a Woolfe’s apparatus, the first being charged 
 with a little water, to intercept the muriatic 
 acid gas, while the third bottle may contain 
 potash-water or milk of lime, to condense 
 the superfluous gas. M. Thenard says, that 
 a kilogramme of salt is sufficient for saturat- 
 ing from 10 to 12 litres of water. These 
 measures correspond to 2y libs, avoirdupois, 
 and from 21 to 25 pints English. There is 
 an ingenious apparatus for making aqueous 
 chlorine, described in Berth ol let’s Elements 
 of Dyeing, vol. i. ; which, however, the happy 
 substitution of slaked lime for water, by Mr 
 Charles Tennent of Glasgow, has supersed- 
 ed, for the purposes of manufacture. It 
 congeals by cold at 40° Fahr. and affords 
 crystallized plates, of a deep yellow, contain- 
 ing a less proportion of water than the liquid 
 
 combination. Hence when chlorine is pass- 
 ed into water at temperatures under 40°, the 
 liquid finally becomes a concrete mass, which 
 at a gentle heat liquefies with effervescence, 
 from the escape of the excess of chlorine. 
 Vv hen steam and chlorine are passed toge- 
 ther through a red-hot porcelain tube, they 
 are converted into muriatic acid and oxygen. 
 A like result is obtained by exposing aqueous 
 chlorine to the solar rays ; with this diffe- 
 rence, that a little chloric acid is formed. 
 Hence aqueous chlorine should be kept in a 
 dark place. Aqueous chlorine attacks al- 
 most all the metals at an ordinary tempera- 
 ture, forming muriates or chlorides, and heat 
 is evolved. It has the smell, taste, and co- 
 lour of chlorine ; and acts like it, on vege- 
 table and animal colours. Its taste is some- 
 what astringent, but not in the least degree, 
 acidulous. 
 
 When we put in a perfectly dark place, at 
 the ordinary temperature, a mixture of chlo- 
 rine and hydrogen, it experiences no kind of 
 alteration, even in the space of a great many 
 days. But if, at the same low temperature, 
 we expose the mixture to the diffuse light of 
 day, by degrees the two gases enter into che- 
 mical combination, and form muriatic acid 
 gas. There is no change in the volume of the 
 mixture, but the change of its nature may be 
 proved, by its rapid absorbability by water, 
 its not exploding by the lighted taper, and 
 the disappearance of the chlorine hue. To 
 produce the complete discoloration, we must 
 expose the mixture finally for a few minutes 
 to the sunbeam. If exposed at first to this 
 intensity of light, it explodes with great vio- 
 lence, and instantly forms muriatic acid gas. 
 The same explosive combination is produced 
 by the electric spark and the lighted taper. 
 M. Thenard says, a heat of 592° is sufficient 
 to cause the explosion. The proper propor- 
 tion is an equal volume of each gas. Chlo- 
 rine and nitrogen combine into a remarkable 
 detonating compound, by exposing the for- 
 mer gas to a solution of an ammoniacal salt. 
 See Nitrogrn. Chlorine is the most power- 
 ful agent for destroying contagious miasmata. 
 The disinfecting phials of Morveau evolve 
 this gas. See Chlorous Oxide.* 
 
 * Chlorite is a mineral usually friable 
 or very easy to pulverize, composed of a 
 multitude of little spangles, or shining small 
 grains, falling to powder under the pressure 
 of the fingers. There are four sub-species. 
 1. Chlorite earth. In green, glimmering and 
 
 somewhat pearly scales, with a shining green 
 streak. It adheres to the skin, and has a 
 greasy feel. Sp. gr. 2.6. It consists of 50 
 silica, 26 alumina, 1 .5 lime, 5 oxide ot iron, 
 1 7.5 potash. This mineral is found chiefly in 
 clay-slate, in Germany and Switzerland. 5t 
 Altenberg, in Saxony, it is intermingled with 
 sulphurets of iron and arsenic ; and amphi- 
 bole in mass. 2. Common chlorite. A 
 
CHL 
 
 CHL 
 
 massive mineral of a blackish-green colour, 
 a shining lustre, and a foliated fracture pass- 
 ing into earthy. Streak is lighter green ; 
 it is soft, opaque, easily cut and broken, and 
 feels greasy. Sp. gr. 2.83. Its constituents 
 are 26 silica, 18.5 alumina, 8 magnesia, 45 
 oxide of iron, and 2 muriate of potash. 3. 
 Chlorite slate . A massive, blackish- green 
 
 mineral, with resinous lustre, and curve slaty 
 or scaly-foliated fracture. Double cleavage. 
 Easily cut. Feels somewhat greasy. Sp. gr. 
 2.82. It occurs particularly along with clay- 
 slate, and is found in Corsica, Fahlun in Swe- 
 den, and Norway. 4. Foliated chlorite. Co- 
 lour between mountain and blackish -green. 
 Massive ; but commonly crystallized in six- 
 sided tables, in cylinders terminated by two 
 cones, and in double cones w ith the bases 
 joined. Surface streaked. Lustre shining 
 pearly; foliated fracture, translucent on the 
 edges ; soft, sectile, and folia usually flexible. 
 Feels rather greasy. Sp. gr. 2.82. It is 
 found at St Gothard, in Switzerland, and in 
 the Island of Java. Its constituents are 35 
 oilica, 18 alumina, 29.9 magnesia, 9.7 oxide 
 of iron, 2.7 water.* 
 
 * Chlorophane. A violet jluor spar , 
 found in Siberia.* 
 
 * Chlorides. Compounds of chlorine 
 with bases. See the respective bases.* 
 
 * Chloro-carronous Acid. The term 
 chi oro- carbonic which has been given to this 
 compound is incorrect, leading to the belief 
 of its being a compound of chlorine and aci- 
 dified charcoal, instead of being a compound 
 of chlorine and the protoxide of charcoal. 
 Chlorine has no immediate action on carbo- 
 nic oxide, when they are exposed to each 
 other in common day-light over mercury ; 
 not even when the electric spark is passed 
 through them. Experiments made by Dr 
 John Davy, in the presence of his brother 
 Sir II. Davy, prove that they combine ra- 
 pidly when exposed to the direct solar 
 beams, and one volume of each is condensed 
 into one volume of the compound. The re- 
 sulting gas possesses very curious properties, 
 approaching to those of an acid. From the 
 peculiar potency of the sunbeam in effect- 
 ing this combination, Dr Davy called it 
 phosgene gas. The constituent gases, dried 
 over muriate of lime, ought to be introduced 
 from separate reservoirs into an exhausted 
 globe, perfectly dry, and exposed for fifteen 
 minutes to bright sunshine, or for twelve 
 hours to day-light. The colour of the chlo- 
 rine disappears, and on opening the stop- 
 cock belonging to the globe under mercury 
 recently boiled, an absorption of one-half the 
 gaseous volume is indicated. The resulting 
 gas possesses properties perfectly distinct 
 from those belonging to either carbonic oxide 
 or chlorine. 
 
 It does not fume in the atmosphere. Its 
 odour is different from that of chlorine, 
 
 something like that which might be imagin- 
 ed to result from the smell of chlorine com- 
 bined with that of ammonia. It is in fact 
 more intolerable and suffocating than chlo- 
 rine itself, and affects the eyes in a pecu- 
 liar manner, producing a rapid flow of tears, 
 and occasioning painful sensations. 
 
 It reddens dry litmus paper ; and condenses 
 four volumes of ammonia into a white salt, 
 while heat is evolved. This ammoniacal 
 compound is neutral, has no odour, but a 
 pungent saline taste ; is deliquescent, decom- 
 posable by the liquid mineral acids, dissolves 
 without effervescing in vinegar, and sublimes 
 unaltered in muriatic, carbonic, and sulphu- 
 rous acid gases. Sulphuric acid resolves it 
 into carbonic and muriatic acids, in the pro- 
 portion of two in volume of the latter, and 
 one of the former. Tin, zinc, antimony, 
 and arsenic, heated in chloro-carbonous acid, 
 abstract the chlorine, and leave the carbonic 
 oxide expanded to its original volume. There 
 is neither ignition nor explosion takes place, 
 though the action of the metals is rapid. 
 Potassium acting on the compound gas pro- 
 duces a solid chloride and charcoal. White 
 oxide of zinc, with chloro-carbonous acid, 
 gives a metallic chloride, and carbonic acid. 
 Neither sulphur, phosphorus, oxygen, nor 
 hydrogen, though aided by heat, produce 
 any change on the acid gas. But oxygen 
 and hydrogen together, in due proportions, 
 explode in it ; or mere exposure to water, 
 converts it into muriatic and carbonic acid 
 gases. 
 
 From its completely neutralizing ammo- 
 nia, which carbonic acid does not ; from its 
 separating carbonic acid from the subcarbo- 
 nate of this alkali, while itself is not separa- 
 ble by the acid gases or acetic acid, and its 
 reddening vegetable blues, there can be no 
 hesitation in pronouncing the chloro-carbo- 
 nous compound to be an acid. Its saturating 
 powers indeed surpass every other substance. 
 None condenses so large a proportion of 
 ammonia. 
 
 One measure of alcohol condenses tw'elve 
 of chloro-carbonous gas without decompos- 
 ing it ; and acquires the peculiar odour and 
 pow er of affecting the eyes. 
 
 To prepare the gas in a pure state, a good 
 air pump is required, perfectly tight stop- 
 cocks, dry gases, and dry vessels. Its speci- 
 fic gravity may be inferred from the specific 
 gravities of its constituents, of which it is the 
 sum. Hence 2.4733 -f- 0.9722 = 5.4455, 
 is the specific gravity of chloro-carbonous 
 gas; and 100 cubic inches weigh 105.15. 
 giains. It appears that when hydrogen, car- 
 bonic oxide, and chlorine, mixed in equal 
 volumes, are exposed to light, muriatic and 
 chloro-carbonous acids are formed, in equal 
 proportions, indicating an equality of affini- 
 ty- 
 
 The paper in the Phil. Trans, for 1812, 
 
CHL 
 
 CHL 
 
 from which the preceding facts are taken, 
 does honour to the school of Sir H. Davy. 
 MM. Gay Lussac and Thenard, as well as 
 Dr Murray, made controversial investigations 
 on the subject at the same time, but without 
 success. M. Thenard has, however, recog- 
 nized its distinct existence and properties, by 
 the name of carbo- muriatic acid, in the 2d 
 volume of his System, published in 1814, 
 where he considers it as a compound of mu- 
 riatic and carbonic acids, resulting from the 
 mutual actions of the oxygenated muriatic 
 acid, and carbonic oxide.* 
 
 * Chlorous and Chloric Oxides, or the 
 protoxide and deutoxide of chlorine. 
 
 Both of these interesting gaseous com- 
 pounds were discovered by Sir H. Davy. 
 
 1st, The experiments which led him to tho 
 knowledge of the first, were instituted in 
 consequence of the difference he had observ- 
 ed between the properties of chlorine, prepar- 
 ed in different modes. The paper describing 
 the production and properties of the chlorous 
 oxide, was published in the first part of the 
 Phil. Trans, for 1811. To prepare it, we 
 put chlorate of potash into a small retort, 
 and pour in twice as much muriatic acid as 
 will cover it, diluted with an equal volume 
 of water. By the application of a gentle 
 heat, the gas is evolved. It must be collect- 
 ed over mercury. 
 
 Its tint is much more lively, and more 
 yellow than chlorine, and hence its illustri- 
 ous discoverer named it cuchlorinc. Its 
 smell is peculiar, and approaches to that of 
 burnt sugar. It is not respirable. It is 
 soluble in water, to which it gives a lemon 
 colour. Water absorbs 8 or 10 times its 
 volume of this gas. Its specific gravity is 
 to that of common air nearly as 2.40 to 1 ; 
 for 100 cubic inches weigh, according to Sir 
 PI. Davy, between 74 and 75 grains. If the 
 compound gas result from 4 volumes of 
 chlorine -{- 2 of oxygen, weighing 12.1154, 
 which undergo a condensation of one-sixth, 
 then the specific gravity comes out 2.42,5, 
 in accordance with Sir II. Davy’s experi- 
 ments. He found that 50 measures deto- 
 nated in a glass tube over pure mercury, 
 lost their brilliant colour, and became 60 
 measures; of which 40 were chlorine, and 
 20 oxygen. Dr Thomson states 2.407 for 
 the sp. gr., though his own data , when rightly 
 
 calculated upon, give 2.444. 
 
 This gas must be collected and examined 
 with much prudence, and in very small quan- 
 tities. A gentle heat, even that of the hand, 
 will cause its explosion, with such force as 
 to burst thin glass. From this facility of 
 decomposition, it is not easy to ascertain the 
 action of combustible bodies upon it. None 
 of the metals that burn in chlorine act upon 
 this "as at common temperatures ; but when 
 the oxygen is separated, they then inflame in 
 the chlorine. This may be readily exhibited, 
 
 by first introducing into the protoxide a lit- 
 tle Dutch foil, which will not be even tar. 
 nished ; but on applying a heated glass tube 
 to the gas in the neck of the bottle, decom- 
 position instantly takes place, and the foil 
 burns witli brilliancy. When already in 
 chemical union, therefore, chlorine has a 
 stronger attraction for oxygen than for me- 
 tals ; but when insulated, its affinity for the 
 latter is predominant. Protoxide of chlo- 
 rine has no action on mercury, but chlo- 
 rine is rapidly condensed by this metal into 
 calomel. Thus the two gases may be com- 
 pletely separated. When phosphorus is in- 
 troduced into the protoxide, it instantly 
 burns, as it would do in a mixture of two 
 volumes of chlorine and one of oxygen ; and 
 a chloride and acid of phosphorus result. 
 Lighted taper and burning sulphur likewise 
 instantly decompose it. When the protoxide 
 freed from water is made to act on dry vege- 
 table colours, it gradually destroys them, but 
 first gives to the blues a tint of red ; from which, 
 from its absorbability by water, and the strong- 
 ly acrid taste of the solution approaching to 
 sour, it may be considered as approximating 
 to an acid in its nature. Since 2 volumes 
 of chlorine weigh (2 X 2.4733) 4.9466, and 
 1 of oxygen 1.1111; we have 4.45 -f- 1 = 
 5.45 for the prime equivalent of chlorous 
 oxide, on the oxygen scale. The propor- 
 tion by weight in 100 parts is 81.65 chlorine 
 
 18.35 oxygen. 
 
 2d, Deutoxide of Chlorine , or Chloric 
 Oxide. “ On Thursday the 4th May, a 
 paper by Sir H. Davy was read at the Royal 
 Society, on the action of acids on hyper-oxy- 
 muriate of potash. When sulphuric acid is 
 poured upon this salt in a wine-glass, very 
 little effervescence takes place, but the acid 
 gradually acquires an orange colour, and a 
 dense yellow vapour, of a peculiar and not 
 disagreeable smell, floats on the surface. 
 These phenomena led the author to believe, 
 that the substance extricated from the salt 
 is held in solution by the acid. After various 
 unsuccessful attempts to obtain this substance 
 in a separate state, he at last succeeded by 
 the following method : About 60 grains of 
 
 the salt are triturated with a little sulphuric 
 acid, just sufficient to convert them into a 
 very solid paste. This is put into a retort, 
 which is heated by means of hot water. The 
 water must never be allowed to become boil- 
 ing hot, for fear of explosion. The heat 
 drives off the new gas, which may be received 
 over mercury. This new gas has a much 
 more intense colour than euchlorine. It 
 does not act on mercury. Water absorbs 
 more of it than of euchlorine. Its taste is 
 astringent. It destroys vegetable blues with- 
 out reddening them. When phosphorus is in- 
 troduced into it, an explosion takes place. 
 When heat is applied, the gas explodes with 
 more violence, and producing more fight 
 
CHL 
 
 CHO 
 
 than euchlorine. When thus exploded, two 
 measures of it are converted into nearly three 
 measures, which consist of a mixture of one 
 measure chlorine, and two measures oxygen. 
 Hence, it is composed of one atom chlorine 
 
 and four atoms oxygen.” 
 
 I have transcribed the above abstract of 
 Sir H. Davy’s paper, from the number of 
 Dr Thomson’s Annals for June 1815, in 
 order to confront it with the following state- 
 ment in his System, 5th edition, vol. i. page 
 189: “ The deutoxide of chlorine was dis- 
 covered about the same time by Sir Hum- 
 phry Davv and Count V r on Stadion of \ ienna ; 
 but Davy’s account of it was published sooner 
 than that of Count Von Stadion. Davy’s ac- 
 count is published in the Philosophical Trans- 
 actions for 1815, p. 214. Count Von Sta- 
 dion’s in Gilbert’s Annalen der Physick, 52. 
 179. published in February 1816.” 
 
 Sir H. Davy’s paper bears date “ Rome, 
 February 15th, 1815.” There is therefore 
 an interval of fully twelve months between 
 the transmission of Sir H. Davy’s discovery 
 for publication, and the promulgation of 
 Count Von Stadion’s paper ; and an interval 
 of nine months between the actual publica- 
 tion of the first, by the reading of it before 
 the Royal Society of England, and the ap- 
 pearance of the second, in Gilbert’s Annalen. 
 I do not wish to insinuate that the Count 
 copied from the English philosopher; but I 
 maintain, that according to every principle 
 of literary justice, the reputation of the dis- 
 covery entirely belongs to Sir H. Davy. 
 
 Even the volume of the Transactions for 
 1815, which one is left to infer might come 
 forth only in 1816, must have been publish- 
 ed earlier ; for Tilloch’s Magazine for De- 
 cember 1815, contains the whole of Sir H. 
 Davy’s paper. 
 
 The preceding abstract, circulated over 
 Europe seven or eight months before the 
 52d volume of Gilbert’s Annalen appeared, 
 is so copious as to require few additions. 
 
 Deutoxide of chlorine has a peculiar aro- 
 matic odour, umr.ixed with any smell of 
 chlorine. A little chlorine is always ab- 
 sorbed by the mercury during the explosion 
 of the gas. Hence the small deficiency of 
 the resulting measure is accounted for. At 
 common temperatures none of the simple 
 combustibles which Sir FI. Davy tried, de- 
 composed the gas, except phosphorus. The 
 taste of the aqueous solution is extremely 
 astringent and corroding, leaving for a long 
 while a very disagreeable sensation. The 
 action of liquid nitric acid on the chlorate of 
 potash affords the same gas, and a much 
 larger quantity of this acid may be safely 
 employed than of the sulphuric. But as the 
 gas must be procured by solution of the salt, 
 it is always mixed with about one-fifth of 
 oxygen. 
 
 Since two measures of this gas, at 212°, 
 explode and form three measures of mingled 
 
 gases, of which two are oxygen and one 
 chlorine ; its composition by weight is 
 Oxygen, 2.2222 4 primes, 4.00 47.33 
 
 Chlorine, 2.4733 1 do. 4.45 52.67 
 
 8.45 100.00 
 
 Its specific gravity is 2.3477 ; and hence 
 100 cubic inches of it weigh about 77 grains. 
 
 Having completed the account of this inte- 
 resting compound, it may be worth while to 
 copy a note from the 1 90th page of Dr Thom- 
 son’s 1st volume, to shew the consistency of 
 his opinions, in one leaf of his System. 
 “ According to Coimt Von Stadion, its con- 
 stituents are two volumes chlorine, and three 
 volumes oxygen. This would make it a 
 compound of one atom chlorine, and three 
 atoms oxygen. But the properties of the 
 substance described by the Count differ so 
 much from those of the gas examined by 
 Davy, that it is probable they are distinct 
 substances.” So that after all, Count Von 
 Stadion has got a deutoxide of chlorine to 
 himself, without interfering with Sir H. 
 Davy’s property. We shall leave him to 
 enjoy it, with the following intimation by his 
 commentator: — “ The reader will find an 
 account of the properties of the deutoxide of 
 chlorine of Count Von Stadion, in the An- 
 nals of Philosophy, vol. ix. p. 22.” 
 
 Chlorophile. The name lately given by 
 MM. Pelletier and Caventou to the green 
 matter of the leaves of plants. They ob- 
 tained it, by pressing and then washing in 
 water, the substance of many leaves, and af- 
 terwards'treating it with alcohol. A matter 
 was dissolved, which, when separated' by 
 evaporation, and purified by washing in hot 
 water, appeared as a deep green resinous 
 substance. It dissolves entirely in alcohol, 
 ether, oils, or alkalis ; it is not altered by 
 exposure to air ; it is softened by heat, but 
 does not melt; it burns with flame, and 
 leaves a bulky coal. Hot water slightly dis- 
 solves it. Acetic acid is the only acid that 
 dissolves it in great quantity. If an earthy 
 or metallic salt be mixed with the alcoholic 
 solution, and then alkali or alkaline subcar- 
 bonate be added, the oxide or earth is thrown 
 down in combination with much of the 
 green substance, forming a lake. These 
 lakes appear moderately permanent when ex- 
 posed to the air. It is supposed to be a pe- 
 culiar proximate principle. 
 
 The above learned term should he spelled 
 with a y, chlorophyle, to signify the green 
 of leaf, or leaf- green : chlorophile, with an i, 
 has a different etymology, and a different 
 meaning. It signifiesyimd of green. 
 
 Cholesterine. The name given by M. 
 Chevreul to the pearly substance of human 
 biliary calculi. It consists of 72 carbon, 
 6.66 oxygen, and 21.33 hydrogen, by Berard. 
 
 Cholesteric Acid. By heating cholcs- 
 terinc with its own weight of strong nitric 
 acid until it ceases to give off nitrous gas, 
 
CHR 
 
 CHR 
 
 MM. Pelletier and Caventou obtained a 
 yellow substance, which separated on cool- 
 ing and was scarcely soluble in water. 
 When well washed, this is cholesteric acid. 
 It is soluble in alcohol, and may be crystal- 
 lized by evaporation. It is decomposed by 
 a heat above that of boiling water, and gives 
 products having oxygen, hydrogen, and 
 charcoal, for their elements. It combines 
 with bases, and forms salts. Those of soda, 
 potash, and ammonia, are very soluble ; the 
 rest are nearly insoluble. 
 
 * Chromium. This rare metal may be 
 extracted either from the native chromate of 
 lead or of iron. The latter being cheapest 
 and most abundant, is usually employed. 
 
 The brown chromate of iron is not acted 
 upon by nitric acid, but most readily by ni- 
 trate of potash, with the aid of a red-heat. 
 A chromate of potash, soluble in water, is 
 thus formed. The iron oxide thrown out of 
 combination may be removed from the resi- 
 dual part of the ore by a short digestion in 
 dilute muriatic acid. A second fusion with 
 
 of nitre, will give rise to a new portion of 
 chromate of potash. Having decomposed 
 the whole of the ore, we saturate the alka- 
 line excess with nitric acid, evaporate and 
 crystallize. The pure crystals dissolved in 
 water, are to be added to a solution of 
 neutral nitrate of mercury ; wffience by 
 complex affinity, red chromate of mercury 
 precipitates. Moderate ignition expels the 
 mercury from the chromate, and the remain- 
 ing chromic acid may be reduced to the me- 
 tallic state, by being exposed in contact of 
 the charcoal from sugar, to a violent heat. 
 
 Chromium thus procured, is a porous 
 mass of agglutinated grains. It is very brittle, 
 and of a greyish-white, intermediate between 
 tin and steel. It is sometimes obtained in 
 needleform crystals, which cross each other 
 in all directions. Its sp. gravity is 5.9. It 
 is susceptible of a feeble magnetism. It re- 
 sists all the acids except nitromuriatic, which, 
 at a boiling heat, oxidizes it and forms a mu- 
 riate. M. Thenard describes only one oxide 
 of chromium ; but there are probably two, 
 besides the acid already described. 
 
 1. The protoxide is green, infusible, in- 
 decomposable by heat, reducible by voltaic 
 electricity, and not acted on by oxygen or 
 air. When heated to dull redness with the 
 half of its weight of potassium or sodium, it 
 forms a brown matter, which, cooled and 
 exposed to the air, burns with flame, and is 
 transformed into chromate of potash or soda, 
 of a canary-yellow colour. It is this oxide 
 which is obtained by calcining the chro- 
 mate of mercury in a small earthen retort 
 for about of an hour. The beak of the 
 retort is to be surrounded with a tube of wet 
 linen, and plunged into w r ater, to facilitate 
 the condensation of the mercury. The 
 oxide, newly precipitated from acids, has a 
 
 dark green colour, and is easily redissolved ; 
 but exposure to a dull red-heat ignites it, 
 and renders it denser, insoluble, and of a 
 light green colour. This change arises sole- 
 ly from the closer aggregation of the parti- 
 cles, for the weight is not altered. 
 
 2. The deutoxide is procured by exposing 
 the protonitrate to heat, till the fumes of 
 nitrous gas cease to issue. A brilliant 
 brown powder, insoluble in acids, and scarce- 
 ly soluble in alkalis, remains. Muriatic 
 acid digested on it, exhales chlorine, shew- 
 ing the increased proportion of oxygen in this 
 oxide. 
 
 5. The tritoxide has been already des- 
 cribed among the acids. It may be directly 
 procured, by adding nitrate of lead to the 
 above nitrochromate of potash, and di- 
 gesting the beautiful orange precipitate of 
 chromate of lead wdth moderately strong 
 muriatic acid, till its power of action be ex- 
 hausted. The fluid produced is to be passed 
 through a filter, and a little oxide of silver, 
 very gradually added, till the whole solution 
 becomes of a deep red tint. This liquor, by 
 slow evaporation, deposits small ruby-red 
 crystals, which are the hydrated chromic 
 acid. The prime equivalent of chromic acid 
 deduced from the chromates of barytes and 
 lead by Berzelius, is 6.544, if w^e suppose 
 them to be neutral salts. According to this 
 chemist, the acid contains double the oxygen 
 that the green oxide does. But if these 
 chromates be regarded as subsalts, then the 
 acid prime would be 13.088, consisting of 6 
 oxygen -f- 7.088 metal ; w r hile the protoxide 
 would consist of 3 oxygen -f 7.088 metal ; 
 and the deutoxide, of an intermediate pro- 
 portion.* 
 
 * Chrysoberyl. Cymopliane of Haiiy. 
 This mineral is usually got in round pieces 
 about the size of a pea, but it is found crys- 
 tallized in eight-sided prisms, terminated by 
 six-sided summits. Colour, asparagus green ; 
 lustre, vitreous; fracture, conchoidal; it is 
 semi-transparent, and brittle, but scratches 
 quartz and beryl. Sp. gr. 3.76. It is infu- 
 sible before the blow-pipe. It has double re- 
 fraction, and becomes electric by friction. 
 Its primitive form is a rectangular parallelo- 
 piped. Its constituents, according to Klap- 
 roth, are 71 alumina, 18 silica, 6 lime, and 
 \\ oxide of iron. 
 
 The summits of the prisms of chrysobe- 
 ryl, are sometimes so cut into facettes, that the 
 solid acquires 28 faces. It is found at Bra- 
 zil, Ceylon, Connecticut, and perhaps Nerts- 
 chink in Siberia. This mineral has nothing 
 to do with the chrysoberyl of Pliny, which 
 was probably a variety of beryl of a greenish - 
 yellow colour.* 
 
 Chrysocolla. The Greek name for 
 borax. 
 
 * Chrysolite. Peridot of Ilaiiy. Iopaz 
 of the ancients, while our topaz is their chry- 
 
CHY 
 
 CIM 
 
 l 
 
 solite. Chrysolite is the least hanl of* all the 
 gems. It is scratched by quartz and the 
 file. Its crystals are well formed compressed 
 prisms, of eight sides at least, terminated by 
 a wedged form or pyramidal summit, trun- 
 cated at the apex. Its primitive form is a 
 right prism, with a rectangular base. It 
 has a strong double refraction, which is ob- 
 served in looking across one of the large 
 sides of the summit, and the opposite face ot 
 the prism. The lateral planes are longitu- 
 dinally streaked. The colour is pistachio 
 green, and other shades. External lustre 
 splendent. Transparent; fracture, conchoi- 
 dal. Scratches felspar. Brittle. Sp. gr. 
 3.4. With borax, it fuses into a pale green 
 glass. Its constituents are 39 silica, 43.5 
 magnesia, 19 of oxide of iron, according to 
 Klaproth ; but Vauquelin found 38, 50.5, 
 and 9.5. Chrysolite comes from Egypt, 
 where it is found in alluvial strata. It has 
 also been found in Bohemia, and in the cir- 
 cle of Bunzlnu.* 
 
 * CHRVsoraASE. A variety of calcedony. 
 It is either of an apple or leek-green colour. 
 Its fracture is even, waxy, sometimes a little 
 splintery. Translucent, with scarcely any 
 lustre. Softer than calcedony, and rather 
 tough. Sp. gr. 2.5. A strong heat whitens 
 it. It consists of 96. 1 6 silica, 0.08 alumina, 
 0.83 lime, 0.08 oxide of iron, and 1 oxide of 
 nickel, to which it probably owes its colour. 
 It has been found hitherto only at Kosemiitz 
 in Upper Silesia. The mountains which en- 
 close it, are composed chiefly of serpentine, 
 potstone, talc, and other unctuous rocks that 
 almost all contain magnesia. It is found in 
 veins or interrupted beds in the midst of a 
 green earth which contains nickel. It is 
 used in jew'ellery.* 
 
 * Chusite. A mineral found by Saus- 
 sure in the cavities of porphyries in the en- 
 virons of Limbourg. It is yellowish or 
 greenish and translucent ; its fracture is some- 
 times perfectly smooth, and its lustre greasy ; 
 at other times it is granular. It is very 
 brittle. It melts easily into a translucid 
 enamel, enclosing air bubbles. It dissolves 
 entirely and without effervescence in acids. * 
 
 * Chyle. By the digestive process in the 
 stomach of animals, the food is converted 
 into a milky fluid, called chyme , which pass- 
 ing into the intestines is mixed with pan- 
 
 i creatic juice and bile, and thereafter resolved 
 into chyle and feculent matter. The former 
 is taken up by the lacteal absorbent vessels 
 of the intestines, w'hich coursing along the 
 mesenteric web, terminate in the thoracic 
 duct. This finally empties its contents into 
 the vena cava. 
 
 Chyle taken soon after the death of an 
 animal, from the thoracic duct, resembles 
 milk in appearance. It has no smell, but a 
 slightly aoido-saccharine taste ; yet it blues 
 
 reddened litmus paper, by its unsaturated al- 
 kali- Soon after it is draw n from the duct, 
 it separates by coagulation into a thicker and 
 thinner matter. 1 . The former, or curd, 
 seems intermediate between albumen and fi- 
 brin. Potash and soda dissolve it, with a 
 slight exhalation of ammonia. Water of 
 ammonia forms with it a reddish solution. 
 Dilute sulphuric acid dissolves the coagulum; 
 and very weak nitric acid changes it into 
 adipocere. By heat, it is converted into a 
 charcoal of difficult incineration, which con- 
 tains common salt and phosphate of lime, 
 with minute traces of iron. 2. from the 
 serous portion, heat, alcohol, and acids, pre- 
 cipitate a copious coagulum of albumen. If 
 the alcohol be hot, a little matter analogous 
 to the substance of brain is subsequently de- 
 posited. By evaporation and cooling, Mr 
 Brande obtained crystals analogous to the 
 sugar of milk. Dr Marcet found the chyle 
 of graminivorous animals thinner and darker, 
 and less charged with albumen, than that oi 
 carnivorous. In the former, the weight of 
 the fluid part to that of the coagulum was 
 nearly 2 to 1 ; but a serous matter after- 
 wards oozed out, which reduced the clot to 
 a very small volume.* 
 
 * Chyme. Dr Marcet examined chyme 
 from the stomach of a turkey. It w-as a 
 homogeneous, brownish opaque pulp, having 
 the smell peculiar to poultry. It was nei- 
 ther acid nor alkaline, and left one-fifth of 
 solid matter by evaporation. It contained 
 albumen. From the incineration of 1000 
 parts, 1 2 parts of charcoal resulted, in which 
 iron, lime, and an alkaline muriate were dis- 
 tinguished. See Digestion.* 
 
 Cimolite, or Cimolian Earth. The 
 cimolia of Pliny, which was used both me- 
 dicinally and for cleaning cloths by the 
 ancients, and which has been confounded 
 with fullers’ earth and tobacco-pipe clay, 
 has lately been brought from Argentiera, 
 the ancient Cimolus, by Mr Hawkins, and 
 examined by Klaproth. 
 
 It is of a light grayish- white colour, ac- 
 quiring superficially a reddish tint by ex- 
 posure to the air ; massive ; of an earthy, 
 uneven, more or less slaty fracture; opaque ; 
 when shaved with a knife, smooth and of a 
 greasy lustre ; tenacious, so as not without 
 difficulty to be powdered or broken ; and 
 adhering pretty firmly to the tongue. Its 
 specific gravity is 2. It is immediately pe- 
 netrated by water, and developed itself into 
 thin laminae of a curved slaty form. Tritu- 
 rated with water it forms a pappy mass; and 
 100 grains will give three ounces of water 
 the appearance and consistence of a thickish 
 cream. If left to dry after being thus ground, 
 it detaches itself in hard bands, somewliat 
 flexible, and still more difficult to pulverize 
 than before. 
 
CIN 
 
 CIV 
 
 It appeared on analysis to consist of silex 
 63, alumina 23, oxide of iron 1.25, water 
 12 . 
 
 Ground with water, and applied to silk 
 and woollen, greased with oil of almonds, 
 the oil was completely discharged by a slight 
 washing in water, after the stuffs had been 
 hung up a day to dry, without the least 
 injury to the beauty of the colour. Mr 
 Klaproth considers it as superior to our best 
 fuller’s earth ; and attributes its properties 
 to the minutely divided state of the silex, 
 and its intimate combination with the alu- 
 mina. It is still used by the natives of Ar- 
 gentiera for the same purposes as of old. 
 
 According to Olivier the island of Argen- 
 tiera is entirely volcanic, and the cimolian 
 earth is produced by a slow and gradual 
 decomposition of the porphyries, occasioned 
 by subterranean fires. He adds, that he 
 collected specimens of it in all the states 
 through which it passes. 
 
 * Cinchona. The quinquina and kina of 
 the French, is the bark of several species of 
 cinchona, which grow in South America. 
 Of this bark there are three varieties, the 
 red, the yellow, and the pale. 
 
 1. The red is in large, easily pulverized 
 pieces, which furnish a reddish-brown powder, 
 having a bitter astringent taste. The watery 
 infusion reddens vegetable blues, from some 
 free citric acid. It contains also muriates 
 of ammonia and lime. The bark contains 
 extractive, resin, bitter principle, and tannin. 
 2. The yellow Peruvian bark, was first 
 brought to this country about the year 1790; 
 and it resembles pretty closely in composi- 
 tion, the red species, only it yields a good 
 deal of kinate of lime in plates. 3. The 
 pale cinchona, is that generally employed in 
 medical practice, as a tonic and febrifuge. 
 M. Vauquelin made infusions of all the va- 
 rieties of cinchona he could procure, using 
 the same quantities of the barks and water, 
 and leaving the powders infused for the 
 same time. He observed, 1. That certain 
 infusions were precipitated abundantly by 
 infusion of galls, by solution of glue, and 
 tartar emetic. 2. That some were precipi- 
 tated by glue, but not by the two other re- 
 agents ; and 5. That others were, on the 
 contrary, by nutgalls and tartar emetic, 
 without being affected by glue. 4. And 
 that there were some which yielded no pre- 
 cipitate by nutgalls, tannin, or emetic tartar. 
 The cinchonas that furnished the first infu- 
 sion were of excellent quality ; those that 
 afforded the fourth were not febrifuge, 
 while those that gave the second and third, 
 were febrifuge, but in a smaller degree than 
 the first. Besides mucilage, kinate of lime, 
 and woody fibre, he obtained in his analyses, 
 a resinous substance, which appears not to 
 be identic in all the species of bark. It is 
 very bitter; very spluble in alcohol, in acids 
 
 and alkalis ; scarcely soluble in cold water, 
 but more soluble in hot. It is this body 
 which gives to infusions of cinchona, the 
 property of yielding precipitates by emetic 
 tartar, galls, gelatin ; and in it, the febrifuge 
 virtue seems to reside. It is this substance 
 in part, which falls down, on cooling decoc- 
 tions of cinchona, and from concentrated in- 
 fusions. A table of precipitations by glue, 
 tannin, and tartar emetic, from infusions of 
 different barks, has been given by M. Vau- 
 quelin ; but as the particular species are diffi- 
 cult to define, we shall not copy it.* 
 
 Cinchonin. See the preceding article. 
 
 Cinnabar. An ore of mercury, consist- 
 ing of that metal united with sulphur. 
 
 * Cinnamon Stone. The colours of 
 this rare mineral are blood-red, and hyacinth- 
 red, passing into orange-yellow. It is found 
 always in roundish pieces; lustre splendent; 
 fracture imperfect conchoidal ; fragments 
 angular; transparent and semi-transparent; 
 scratches quartz with difficulty ; somewhat 
 brittle; sp.gr. 3.53; fuses into a brownish- 
 black enamel. Its constituents are 38.8 si- 
 lica, 21.2 alumina, 31.25 lime, and 6.5 
 oxide of iron. It is found in the sand of 
 rivers, in Ceylon.* 
 
 Cipolin. The cipolin from Rome is a 
 green marble with white zones: it gives fire 
 with steel, though difficultly. One hun- 
 dred parts of it contains 67.8 of carbonate 
 of lime; 25 of quartz; 8 of schistus ; 0.2 of 
 iron, beside the iron contained in the schistus. 
 The cipolin from Autun, 83 parts carbo- 
 nate of lime, 12 of green mica, and one of 
 iron. 
 
 * Cistic Oxide. A peculiar animal pro- 
 duct, discovered by Dr Wollaston. It con- 
 stitutes a variety of urinary Calculus, which 
 see.* 
 
 * Citric Acid. Acid of limes. It has 
 been found nearly unmixed, with other acids, 
 not only in lemons, oranges, and limes, but 
 also in the berries of vaccinium nxycoccos, or 
 cranberry, vaccinium , vitis ideva , or red- 
 whortleberry, of birdcherry, nightshade, hip, 
 in unripe grapes and tamarinds. Goose- 
 berries, currants, bilberries, be:imberries, cher- 
 ries, strawberries, cloudberries, and rasp- 
 berries, contain citric acid mixed with an equal 
 quantity of malic acid. The onion yields 
 citrate of lime. See Acid (Citric).* 
 
 Civet is collected betwixt the anus and 
 the organs of generation of a fierce carnivo- 
 rous quadruped met with in China and the 
 East and West Indies, called a civet-cat, but 
 bearing a greater resemblance to a fox or 
 marten than a cat. 
 
 Several of these animals have been 
 brought into Holland, and afford a consi- 
 derable branch of commerce, particularly at 
 Amsterdam. The civet is squeezed out, in 
 summer every other day, in winter twice a- 
 week : the quantity procured at once w 
 
CLA 
 
 CLA 
 
 from two scruples to a drachm or more. 
 The juice thus collected is much purer and 
 finer than that which the animal sheds 
 against shrubs or stones in its native cli- 
 mates. 
 
 Good civet is of a clear yellowish or 
 brownish colour, not fluid, nor hard, but 
 about the consistence of butter or honey, 
 and uniform throughout; of a very strong 
 smell; quite offensive when undiluted; but 
 agreeable when only a small portion of 
 civet is mixed with a large one of other 
 substances. 
 
 * Civet unites with oils, but not with 
 alcohol. Its nature is therefore not resin- 
 ous.* 
 
 
 Clarification is the process of freeing 
 a fluid from heterogeneous matter or fecu- 
 lencies, though the term is seldom applied 
 to the mere mechanical process of straining, 
 for which see Filtration. 
 
 Albumen, gelatine, acids, certain salts, 
 lime, blood, and alcohol, in many cases 
 serve to clarify fluids, that cannot be 
 freed from their impurities by simple per- 
 colation. 
 
 Albumen or gelatine, dissolved in a small 
 portion of water, is commonly used for 
 fining vinous liquors, as it inviscates the 
 feculent matter, and gradually subsides 
 with it to the bottom. Albumen is parti- 
 cularly used for fluids, with which it will 
 combine when cold, as syrups ; it being 
 coagulated by the heat, and then rising in a 
 scum with the dregs. 
 
 Heat alone clarifies some fluids, as the 
 juices of plants, in which however the albu- 
 men they contain is probably the agent. 
 
 A couple of handfuls of marie, throw'n 
 into the press, will clarify cyder, or w^ater- 
 cyder. 
 
 Clay (Pure). See Alumina. 
 
 * Clay. The clays being opaque and 
 non-crystallized bodies, of dull fracture, af- 
 ford no good principle for determining their 
 species ; yet as they are extensively distri- 
 buted in nature, and are used in many arts, 
 they deserve particular attention. The argil- 
 laceous minerals are all sufficiently soft to be 
 scratched by iron ; they have a dull or even 
 earthy fracture ; they exhale, when breathed 
 on, a peculiar smell called argillaceous. The 
 clays form with w r ater a plastic paste, posses- 
 sing considerable tenacity, which hardens 
 with heat, so as to strike fire w'ith steel. 
 Maries and chalks also soften in w'ater, but 
 their paste is not tenacious, nor does it ac- 
 quire a siliceous hardness in the fire. The 
 affinity of the clays for moisture is manifest- 
 ed by their sticking to the tongue, and by 
 the intense heat necessary to make them per- 
 fectly dry. The odour ascribed to clays 
 breathed upon, is due to the oxide of iron 
 mixed with them. Absolutely pure clays, 
 emit no smell. 
 
 1. Porcelain earth , the kaolin cl the 
 Chinese. — This mineral is friable, meagre 
 to the touch, and, when pure, forms with 
 difficulty a paste with water. It is infusible 
 in a porcelain furnace. It is of a pure 
 white, verging sometimes upon the yellow 
 or flesh-red. Some present particles of mica, 
 w hich betray their origin to be from felspar 
 or graphic granite. It scarcely adheres to the 
 tongue. Sp. gr. 2.2. It is found in primi- 
 tive mountains, amid blocks of granite, form- 
 ing interposed strata. Kaolins are some- 
 times preceded by beds of a micaceous rock 
 of the texture of gneiss, but red and very 
 friable. This remarkable disposition has 
 been observed in the kaolin quarries ol 
 China, in those of Alen^on, and of Saint 
 Yriex near Limoges. The constituents of 
 kaolin are 52 silica, 47 alumina, 0.33 oxide 
 of iron ; but some contain a notable propor- 
 tion of water in their recent state. The 
 Chinese and Japanese kaolins are whiter 
 and more unctuous to the touch than those 
 of Europe. The Saxon has a slight tint of 
 yellow or carnation, which disappears in the 
 fire, and therefore is not owing to metallic 
 impregnation. At Saint Yriex the kaolin is 
 in a stratum and also in a vein, amid blocks 
 of granite, or rather the felspar rock, which 
 the Chinese call petuntze. The Cornish 
 kaolin is very white and unctuous to the 
 touch, and obviously is formed by the disin- 
 tegration of the felspar of granite. 
 
 2. Potters' clay , or jilastic clay . — The 
 clays of this variety are compact, smooth, 
 and almost unctuous to the touch, and may 
 be polished by the finger when they are dry. 
 They have a great affinity for water, form a 
 tenacious paste, and adhere strongly to the 
 tongue. The paste of some is even slightly 
 transparent. They acquire great solidity, 
 but are infusible in the porcelain furnace. 
 This property distinguishes them from com- 
 mon clays, employed for coarse earthen w r are. 
 Some of them remain wdiite, or become so 
 in a high heat ; others turn red. Sp. gr. 2. 
 The slaty potters’ clay of Werner has a dark 
 ash-grey colour ; principal fracture imper- 
 fectly conchoidal, cross fracture earthy ; 
 fragments tabular, rather light, and feels 
 more greasy than common potters’ clay. 
 Yauquelin’s analysis of the plastic clay of 
 Forges-les-Eaux, employed for making glass- 
 house pots, as well as pottery, gave 16 alu- 
 mina, 63 silica, 1 lime, 8 iron, and 10 waiter. 
 Another potters’ clay gave 33.2 and 43.5 of 
 alumina and silica, with 3.5 lime. 
 
 5. Loam . — This is an impure potters* clay 
 mixed with mica and iron ochre. Colour 
 yellowish- grey, often spotted yellow and 
 brown. Massive, with a dull glimmering 
 lustre from scales of mica. Adheres pretty 
 strongly to the tongue, and feels slightly 
 greasy. Its density is inferior to the pre- 
 ceding. 
 
 X 
 
CLA 
 
 CLI 
 
 4. Variegated clai/. — Is striped or spotted 
 with white, red, or yellow colours. Massive, 
 with an earthy fracture, verging on slaty. 
 Shining streak. Very soft, sometimes even 
 friable. Feels slightly greasy, and adheres 
 n little to the tongue. Sectile. It is found 
 in Upper Lusatia. 
 
 5. Slate clay. — Colour grey, or greyish- 
 yellow. Massive. Dull or glimmering 
 lustre, from interspersed mica. Slaty frac- 
 ture, approaching sometimes to earthy. Frag- 
 ments tabular. Opaque, soft, sectile, and 
 easily broken. Sp. gr. 2.6. Adheres to the 
 tongue, and breaks down in water. It is 
 found along with coal, and in the floetz trap 
 formation. 
 
 6. Clay stone. — Colour grey, of various 
 shades, sometimes red, and spotted or strip- 
 ed. Massive. Dull lustre, with a fine 
 earthy fracture, passing into fine grained 
 uneven, slaty or splintery. Opaque, soft, 
 and easily broken. Does not adhere to the 
 tongue, and is meagre to the touch. It has 
 been found on the top of the Pentland hills 
 in Scotland, and in Germany. 
 
 7. Adhesive slate. — Colour light greenish- 
 grey. Internal lustre dull ; fracture in the 
 large, slaty ; in the small, fine earthy. Frag- 
 ments slaty. Opaque. Shining streak. 
 Sectile. Easily broken or exfoliated. Ad- 
 heres strongly to the tongue, and absorbs 
 water rapidly with the emission of air bub- 
 bles, and a crackling sound. It is found at 
 Montmartre near Paris, between blocks of 
 impure gypsum, in large straight plates like 
 sheets of pasteboard. It is found also at 
 Menilmontant, enclosing menilite. Klap- 
 roth’s analysis is 62.5 silica, 8 magnesia, 0.5 
 alumina, 0.25 lime, 4 oxide of iron, 22 water, 
 and 0.75 charcoal. Its sp. gr. is 2.08. 
 
 8. Polishing slate of Werner. — Colour, 
 cream-yellow, in alternate stripes. Massive. 
 Lustre dull. Slaty fracture. Fragments ta^ 
 bular. Very soft, and adheres to the tongue. 
 Smooth, but meagre to the touch. Sp. gr. 
 in its dry state 0.6 ; when imbued with 
 moisture 1.9. It has been found only in Bo- 
 hemia. Its constituents are 79 sihea, 1 alu- 
 mina, 1 lime, 4 oxide of iron, and 14 water. 
 
 9. Common clay may be considered to be 
 the same as loam. — -Besides the above, we 
 have the analyses of some pure clays, the re- 
 sults of which shew a very minute quantity 
 of silica, and a large quantity of sulphuric 
 acid. Thus, in one analyzed by Bucholz, 
 there was 1 silica, .31 alumina, 0.5 lime, 0.5 
 oxide of iron, 21.5 sulphuric acid, 45 water, 
 and 0.5 loss. Simon found 19.35 sulphuric 
 acid in 100 parts. We must regard these 
 clays as subsulphates of alumina. 
 
 Clay-Slate. Argillaceous Schistus — 
 the Argillite of Kirwan. Colour, bluish- 
 grey, and greyish-black of various shades. 
 Massive. Internal lustre shining or pear- 
 ly. Fracture foliated. Fragments tabular. 
 
 Streak, greenish-white. Opaque. Soft. 
 
 Sectile. Easily broken. Sonorous, when 
 
 struck wdth a hard body. Sp. gr. 2.7. Its 
 constituents are 48.6 silica, 2.5:5 alumina, 
 1.6 magnesia, 11.3 peroxide of iron, 0.5 
 oxide of manganese, 4.7 potash, 0.3 carbon, 
 0. 1 sulphur, 7.6 water and volatile matter. 
 Clay-slate melts easily by the blow-pipe into 
 a shining scoria. This mineral is extensively 
 distributed, forming a part of both primi- 
 tive and transition mountains. The great 
 beds of it are often cut across by thin seams 
 of quartz or carbonate of lime, w hich divide 
 them into rhomboidal masses. Good slates 
 should not imbibe water. If they do, they 
 soon decompose by the weather. 
 
 * Clay Iron Stone. See Ores of Iron.* 
 
 * Climate. The prevailing constitution 
 of the atmosphere, relative to heat, wind, 
 and moisture, peculiar to any region. This 
 depends chiefly on the latitude of the place, 
 its elevation above the level of the sea, and 
 its insular or continental position. Springs 
 which issue from a considerable depth, and 
 caves about 50 feet under the surface, pre- 
 serve a uniform temperature through all the 
 vicissitudes of the season. This is the mean 
 temperature of that country. From a com- 
 parison of observations, Professor Mayer 
 constructed the following empirical rule for 
 finding the relation between the latitude and 
 the mean temperature, in centesimal degrees, 
 at the level of the sea. 
 
 Multiply the square of the cosine of the 
 latitude by the constant number 29, the ] no- 
 duct is the temperature. The variation of 
 temperature for each degree of latitude is 
 hence denoted centesimally with very great 
 precision, by half the sine of double the lati- 
 tude. 
 
 T ... , Mean temperatures. 
 
 Latitude. Cent< Fahr . 
 
 Height of curve of 
 congelation in feet. 
 
 0° 
 
 29° 
 
 84.2 
 
 15207 
 
 5 
 
 28.78 
 
 83.8 
 
 15095 
 
 10 
 
 28.13 
 
 82.6 
 
 14764 
 
 15 
 
 27.06 
 
 80.7 
 
 14220 
 
 20 
 
 25.61 
 
 78.1 
 
 13478 
 
 25 
 
 23.82 
 
 74.9 
 
 12557 
 
 30 
 
 21.75 
 
 71.1 
 
 11484 
 
 35 
 
 1 9.46 
 
 67. 
 
 10287 
 
 40 
 
 17.01 
 
 62.6 
 
 9001 
 
 45 
 
 14.5 0 
 
 58.1 
 
 7671 
 
 50 
 
 1 1.98 
 
 53.6 
 
 6334 
 
 55 
 
 9.54 
 
 49.2 
 
 5034 
 
 60 
 
 7.25 
 
 45.0 
 
 3818 
 
 65 
 
 5.18 
 
 41.3 
 
 2722 
 
 70 
 
 3.39 
 
 38. 1 
 
 1778 
 
 75 
 
 1 .94 
 
 35.5 
 
 1016 
 
 80 
 
 0.86 
 
 33.6 
 
 457 
 
 85 
 
 0.22 
 
 32.4 
 
 1 17 
 
 90 
 
 0.0 
 
 32.0 
 
 00 
 
 The 
 
 following 
 
 table represents the results 
 
 the direction of Mr Ferguson oi Faith, at 
 
CLI 
 
 CLI 
 
 Abbotshall in Fife, about 50 feet above the 
 level of the sea, in latitude 56° 10'. The 
 large and strong bulbs of the thermometers, 
 
 Had the thermometers been sunk deeper, 
 they would undoubtedly have indicated 47.7, 
 which is the mean temperature of the place, 
 as is shewn by a copious spring. 
 
 The lake of Geneva, at the depth of 1000 
 feet, was found by Saussurc to be 42° ; and 
 below 160 feet from the surface there is no 
 monthly variation of temperature. The lake 
 of Thun, at 570 of depth, and Lucerne at 
 640, had both a temperature of 41°, while 
 the waters at the surface indicated respec- 
 tively 64° and 68-|° Fahr. Barlocci observ- 
 ed, that the Lago Sabatino, near Rome, at 
 the depth of 490 feet, was only 44^°, while 
 the thermometer stood on its surface at 77°. 
 Mr Jardinc has made accurate observations 
 on the temperatures of some of the Scottish 
 lakes, by which it appears, that the tempera- 
 ture continues uniform nil the year round, 
 about 20 fathoms under the surface. In like 
 manner, the mine of Dannemora in Sweden, 
 which presents an immense excavation, 200 
 or 300 feet deep, was observed at a period 
 when the working was stopped, to have great 
 blocks of ice lying at the bottom of it. The 
 bottom of the main shaft of the silver mine 
 of Kongsberg in Norway, about 300 feet 
 leep, is covered with perpetual snow. Hence, 
 likewise, in the deep crevices on ./Etna and 
 :he Pyrenees, the snows are preserved all the 
 > r ear round. It is only, however, in such 
 confined situations that the lower strata of 
 tir are thus permanently cold. In a free 
 atmosphere, the gradation of temperature is 
 eversed, or the upper regions are colder, in 
 consequence of the increased capacity for 
 leat of the air, by the diminution of the den- 
 ity. In the milder climates, it will be 
 
 were buried in the ground at various depths, 
 while the stems rose above the surface, for 
 inspection. 
 
 sufficiently accurate, in moderate elevations, 
 to reckon an ascent of 540 feet for each 
 centesimal degree, or 100 yards for each de- 
 gree on Fahrenheit’s scale, of diminished 
 temperature. Dr Francis Buchanan found 
 a spring at Chitlong, in the lesser valley of 
 Nepal, in Upper India, which indicated the 
 temperature of 14.7 centesimal degrees, 
 which is 8.1° below the standard, for its pa- 
 rallel of latitude, 27° 38'. Whence, 8.1 X 
 540 = 4374 feet, is the elevation of that 
 valley. At the height of a mile this rule 
 would give about 33 feet too much. The 
 decrements of temperature augment in an 
 accelerated progression as we ascend. 
 
 Ben Nevis, the highest mountain in Great 
 Britain, stands in latitude 57°, where the 
 curve of congelation reaches to 4534 feet. 
 But the altitude of the summit of the moun- 
 tain is no more than 4380 feet ; and therefore, 
 during two or three weeks in July, the snow 
 disappears. The curve of congelation must 
 evidently rise higher in summer, and sink 
 lower in winter, producing a zone of fluctu- 
 ating ice, in which the glaciers arc formed. 
 
 In calculating the mean temperature of 
 countries at different distances from the 
 equator, the warmth has been referred solely 
 to the sun. But Mr Bald has published, in 
 the first number of the Edinburgh Philoso- 
 phical Journal, some facts apparently incom- 
 patible with the idea of the interior tempe- 
 rature of the earth being deducible from the 
 latitude ol the place, or the mean tempera- 
 ture at the surface. The following table 
 presents, at one view, the temperature of air 
 and water, in the deepest coal-mines in Great 
 Britain. 
 
 1816. 1817, 
 
 
 I foot. 
 
 2 feet. 
 
 3 feet. 
 
 4 feet. 
 
 1 foot. 
 
 2 feet. 
 
 3 feet. 
 
 4 feet. 
 
 January, 
 
 33° 
 
 36.3° 
 
 40.7° 
 
 43° 
 
 35.6 
 
 38.7 
 
 40.5 
 
 45.1 
 
 February, 
 
 33.7 
 
 36 
 
 39.0 
 
 42 
 
 37.0 
 
 40.0 
 
 41.6 
 
 42.7 
 
 March, 
 
 35 
 
 36.7 
 
 39.6 
 
 42.3 
 
 39.4 
 
 40.2 
 
 41.7 
 
 42.5 
 
 April, 
 
 39.7 
 
 38.4 
 
 41.4 
 
 43. 8 
 
 45.0 
 
 42.4 
 
 42.6 
 
 42.6 
 
 Mav, 
 
 44.0 
 
 43. 3 
 
 43.4 
 
 44.0 
 
 46.8 
 
 44.7 
 
 44.6 
 
 44.2 
 
 June, 
 
 51.6 
 
 50.0 
 
 47.1 
 
 45.8 
 
 51.1 
 
 49.4 
 
 47.6 
 
 47.8 
 
 July, 
 
 54.0 
 
 52.5 
 
 55.4 
 
 47.7 
 
 55.2 
 
 55.0 
 
 51.4 
 
 49.6 
 
 August, 
 
 50.0 
 
 52.5 
 
 50.6 
 
 49.4 
 
 53.4 
 
 53.9 
 
 52.0 
 
 50.0 
 
 September, 
 
 51.6 
 
 51.3 
 
 51.8 
 
 50.0 
 
 53.0 
 
 52.7 
 
 52.0 
 
 50.7 
 
 October, 
 
 47.0 
 
 49.3 
 
 49.7 
 
 49.6 
 
 45.7 
 
 49.4 
 
 49.4 
 
 49.8 
 
 November, 
 
 40.8 
 
 43.8 
 
 46.3 
 
 45.6 
 
 41.0 
 
 44.7 
 
 47.0 
 
 47.6 
 
 December, 
 
 35.7 
 
 40.0 
 
 43.0 
 
 46.0 
 
 37.9 
 
 40.8 
 
 44.9 
 
 46.4 
 
 Mean of 
 whole year. 
 
 43.8 
 
 44.1 
 
 45.1 
 
 46. 
 
 44.9 
 
 45.9 
 
 46.2 
 
 46.6 
 
CLI 
 
 CLI 
 
 Whitehaven Colliery , county of Cumberland. 
 Air at the surface, - - 55 ° Jf. 
 
 A spring at the surface, - 49 
 
 Water at the depth of 480 feet, GO 
 
 Air at same depth, - - G 3 
 
 Air at depth of 600 feet, - - 66 
 
 Difference between water at surface 
 and at 480 feet, - - 11 
 
 Workington Colliery, county of Cumberland. 
 Air at the surface, - 56 
 
 A spring at the surface, - 48 
 
 Water 180 feet down, 50 
 
 Water 504 feet under the level of the 
 ocean, and immediately beneath 
 the Irish sea, - - 60 
 
 Difference between water at surface 
 and bottom, - - 12 
 
 Teem Colliery, county of Durham. 
 
 Air at pit bottom, 444 feet deep, 68 
 Water at same depth, - - 61 
 
 Difference between the mean tempe- 
 'rature of water at surface = 49°, 
 and 444 feet down, - - 12 
 
 Percy Main Colliery, county of Northum- 
 berland. 
 
 Air at the surface, - - 42 
 
 Water about 900 feet deeper than the 
 level of the sea, and under the bed 
 of the river Tyne, 68 
 
 Air at the same depth, 70 
 
 At this depth Leslie’s hygrometer in- 
 dicated dryness = 83°. 
 
 Difference between mean temperature 
 of water at surface = 49°, and at 
 900 feet down, - - 19° 
 
 Jarrow Colliery , county of Durham. 
 
 Air at surface, - - 49^ 
 
 Water 882 feet down, - 68 
 
 Air at same depth, - - 70 
 
 Air at pit bottom, 64 
 
 Difference between the mean tempe- 
 rature of water at surface = 49°, 
 and 882 feet down, - 19 
 
 The engine-pit of Jarrow is the deep- 
 est perpendicular shaft in Great 
 Britain, being 900 feet to the foot 
 of the pumps. 
 
 Killingworth Colliery, county of Northum- 
 berland. 
 
 Air at the surface, - - 48 
 
 Air at bottom of pit, 790 feet down, 51 
 
 Air at depth of 900 feet from the 
 surface, after having traversed a 
 mile and a half from the bottom 
 of the downcast pit, 70 
 
 Water at the most distant forehead or 
 mine, and at the great depth of 
 1200 feet from the surface, - 74 
 
 Air at the same depth, - 77 
 
 Difference betwixt the mean tempe- 
 
 rature of the -water at the surface 
 = 4 9°, and water at the depth of 
 1200 feet, - - 25° I*. 
 
 Distilled water boils at this depth at 213 
 Do. do. at surface, - 2104 
 
 M. Humboldt has stated, that the tem- 
 perature of the silver mine of Valenciana in 
 New Spain is 11 ° above the mean tempera- 
 ture of Jamaica and Pondicherry, and that 
 this temperature is not owing to the miners 
 and their lights, but to local and geological 
 causes. To the same local and geological 
 causes we must ascribe the extraordinary 
 elevation of temperature observed by Mr 
 Bald. He further remarks, that the deeper 
 we descend, the drier we find the strata, so 
 that the roads through the mines require to 
 be watered, in order to prevent the horse- 
 drivers from being annoyed by the dust. 
 This fact is adverse to the hypothesis of the 
 heat proceeding from the chemical action of 
 water on the strata cf coal. As for the 
 pyrites intermixed with these strata, it does 
 not seem to be ever decomposed, while it is 
 in situ. The perpetual circulation of air for 
 the respiration of the miners, must prevent 
 the lights from having any considerable in- 
 fluence on the temperature of the mines. 
 
 The meteorological observations now made 
 and published with so much accuracy and 
 regularity in various parts of the world, will 
 soon, it is hoped, make us better acquainted 
 with the various local causes which modify 
 climates, than we can pretend to be at pre- 
 sent. The accomplished philosophical tra- 
 veller, M. de Humboldt, published an ad- 
 mirable systematic view of the mean tempe- 
 ratures of different places, in the third vo- 
 lume of the Memoirs of the Society of 
 Arcueil. His paper is entitled, of Isothermal. 
 Lines (lines of the same temperature), and: 
 the Distribution of Heat over the Globe. 
 By comparing a great number of observa- 
 tions made between 46° and 48° N. lat., he* 
 found, that at the hour of sun-set the tem- 
 perature is very nearly the mean, of that atJ 
 sun-rise and two hours after noon. Upon: 
 the whole, however, he thinks, that the two: 
 observations of the extreme temperatures^ 
 will give us more correct results. 
 
 The difference which we observe in culti- 
 vated plants, depends less upon mean tem- 
 perature, than upon direct light, and the se- 
 renity of the atmosphere ; but wheat will 
 not ripen if the mean temperature descend 
 to 47.6°. 
 
 Europe may be regarded as the western 
 part of a great continent, and subject to al 
 those influences, which make the western 
 sides of all continents warmer than the 1 
 eastern. The same difference that we ob-* 
 serve on the tw o sides of the Atlantic, exist : 
 on the two sides of the Pacific. In the nortl 
 of China, the extremes of the seasons an 
 
 13 
 
CLI 
 
 CLI 
 
 
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 fl 
 
 J) 
 
 
 much more felt than in the same latitudes 
 in New California, and at the mouth of the 
 Columbia. On the eastern side of North 
 America, we have the same extremes as in 
 China ; New- York has the summer of Rome, 
 and the winter of Copenhagen ; Quebec has 
 the summer of Paris, and the winter of 
 Petersburgh. And in the same way in 
 Pekin, which has the mean temperature of 
 Britain; the heats of summer are greater 
 than those at Cairo, and the cold of winter, as 
 severe as that at Upsal. This analogy be- 
 tween the eastern coasts of Asia and of 
 America, sufficiently proves, that the in- 
 equalities of the seasons, depend upon the 
 prolongation and enlargement of the conti- 
 nents towards the pole, and upon the fre- 
 quency of N. W. winds, and not upon the 
 proximity of any elevated tracts of coun- 
 try. 
 
 Ireland, says Humboldt, presents one of 
 the most remarkable examples of the com- 
 bination of very mild winters with cold sum- 
 mers; the mean temperature in Hungary 
 for the month of August is 71.6°; while 
 in Dublin it is only 60.8°. In Belgium 
 and Scotland, the winters are milder than at 
 Milan. 
 
 In the article Climate, Supplement to the 
 Encyclopaedia Britannica, the following very 
 simple rule is given, for determining the 
 change of temperature produced by sudden 
 rarefaction or condensation of air. Multi- 
 ply 25 by the difference between the density 
 of air , and its reciprocal , the product will be 
 the difference of temperature on the centigrade 
 scale. Thus, if the density be twice, or one 
 half 25° X (2 — \) = 37^° cent. = 67.5° 
 Fahr. indicates the change of temperature by 
 doubling the density or rarity of air. Were 
 it condensed 30 times, then, by this formula, 
 we have 749° for the elevation of tempera- 
 ture, or 25° (30 — But M. Gay Lus- 
 sac says, that a condensation of air into 
 one- fifth of its volume, is sufficient to ignite 
 tinder ; a degree of heat which he states at 
 300° centigrade = 572° Fahr. (Journal 
 of Science, vol. vii. p. 177). This experi- 
 mental result is incompatible with Professor 
 Leslie’s Formula, which gives only 1 1 2.5°, 
 for the heat produced by a condensation in- 
 to one-fifth. 
 
 It appears very probable, that the climates 
 of European countries were more severe in 
 ancient times than they are at present. 
 Caesar says, that the vine could not be culti- 
 vated in Gaul, on account of its winter-cold. 
 The rein-deer, now found only in the zone 
 of Lapland, was then an inhabitant of the 
 Pyrenees. The Tiber was frequently frozen 
 over, and the ground about Rome covered 
 
 with snow for several weeks together, which 
 almost never happens in our times. The 
 Rhine and the Danube, in the reign of 
 Augustus, were generally frozen over, for 
 several months of winter. The barbarians 
 who overran the Roman empire a few cen- 
 turies afterwards, transported their armies 
 and waggons across the ice of these rivers. 
 The improvement that is continually taking 
 place in the climate of America, proves, 
 that the power of man extends to pheno- 
 mena, which, from the magnitude and varie- 
 ty of their causes, seemed entirely beyond 
 his controul. At Guiana, in South America, 
 within five degrees of the line, the inhabi- 
 tants living amid immense forests, a century 
 ago, were obliged to alleviate the severity of 
 the cold, by evening fires. Even the dura- 
 tion of the rainy season has been shortened 
 by the clearing of the country, and the 
 warmth is so increased, that a fire now would 
 be deemed an annoyance. It thunders con- 
 tinually in the woods, rarely in the cultivated 
 parts. 
 
 Drainage of the ground, and removal of 
 forests, however, cannot be reckoned among 
 the sources of the increased warmth of the 
 Italian winters. Chemical writers have 
 omitted to notice an astronomical cause of 
 the progressive amelioration of the climates 
 of the northern hemisphere. In conse- 
 quence of the apogee portion of the terres- 
 trial orbit being contained between our ver- 
 nal and autumnal equinox, our summer 
 half of the year, or the interval which 
 elapses between the sun’s crossing the equa- 
 tor in spring, and in autumn, is about seven 
 days longer than our winter half year. 
 Hence also, one reason for the relative cold- 
 ness of the southern hemisphere.* 
 
 Isothermal Bands , a?id Distribution of Heat 
 over the Globe. 
 
 The temperatures are expressed in degrees 
 of Fahrenheit’s thermometer; the longitudes 
 are counted from east to west, from the first 
 meridian of the observatory of Paris. The 
 mean temperature of the seasons have been 
 calculated, so that the months of December, 
 January, and February, form the mean tem- 
 perature of the winter. The mark * is pre- 
 fixed to those places, the mean temperatures 
 ot which have been determined with the 
 most precision, generally by a mean of 8000 
 observations. 1 lie isothermal curves having 
 a concave summit in Europe, and two con- 
 vex summits in Asia and Eastern America, 
 the climate is denoted to which the indi- 
 vidual places belong : — 
 
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 * Clinkstone. A stone of an imperfect- 
 ly slaty structure, which rings like metal 
 when struck with a hammer. Its colour is 
 grey of various shades ; it is brittle ; as hard 
 as felspar, and translucent on the edges. It 
 occurs in columnar and tabular concretions. 
 Sp. gr. 2.57. Fuses easily into a nearly 
 colourless glass. Its constituents are 57.25 
 silica, 25.5 alumina, 2.75 lime, 8.1 soda, 
 3.25 oxide of iron, 0.25 oxide of manganese, 
 and 5 of water. — Klaproth. This stone ge- 
 nerally rests on basalt. It occurs in the 
 Ochil and Pentland hills, the Bass- rock, the 
 islands of Mull, Lamlash, and Islay, in 
 Scotland ; the Breidden hills in Montgo- 
 meryshire, and in the Devis Mountain, in 
 the county of Antrim. It is found in Upper 
 Lusace and Bohemia.* 
 
 * Clinometer. An instrument for mea- 
 suring the dip of mineral strata. It was ori- 
 ginally invented by R. Griffith, Esq. Pro- 
 fessor of Geology to the Dublin Society, 
 and subsequently modified by Mr Jardine 
 and Lord Webb Seymour. See a description 
 and drawing by the latter, in the third volume 
 of the Geological Transactions. Lord Webb’s 
 instrument was a very perfect one. It was 
 made by that unrivalled artist, Mr Trough- 
 ton. * 
 
 * Cloud. A mass of vapour, more or 
 less opaque, formed and sustained at con- 
 siderable heights in the atmosphere, probably 
 by the joint agencies of heat and electricity. 
 The first successful attempt to arrange the 
 diversified forms of clouds, under a few ge- 
 neral modifications, was made by Luke 
 Howard, Esq. We shall give here a brief 
 account of his ingenious classification. 
 
 The simple modifications are thus named 
 and defined. 1. Cirrhus. Parallel, flexuous, 
 or diverging fibres, extensible in any or in 
 all directions. 2. Cumulus. Convex or co- 
 nical heaps, increasing upwards from a hori- 
 zontal base. 5. Stratus. A widely extended, 
 continuous horizontal sheet, increasing from 
 below. 
 
 The intermediate modifications which re- 
 quire to be noticed are, 4. Cirro-cumulus. 
 Small well-defined roundish masses, in close 
 horizontal arrangement. 5. Cirro-stratus. 
 Horizontal, or slightly inclined masses, at- 
 tenuated towards a part or the whole of their 
 circumference, bent downward, or undulated, 
 separate or in groupes, consisting of small 
 clouds having these characters. 
 
 The compound modifications are, 6. Cu- 
 mulo- stratus. The cirro-stratus, blended 
 
 with the cumulus, and either appearing in- 
 termixed witli the heaps of the latter, or su- 
 peradding a wide-spread structure to its 
 base. 
 
 7. Cumido-cirro-slratus, vel Nimbus. Ihe 
 rain cloud. A cloud or system of clouds 
 from which rain is falling. It is a horizontal 
 sheet, above which the cirrus spreads, while 
 
 the cumulus enters it laterally and from be- 
 neath. 
 
 The cirrus appears to have the least den- 
 sity, the greatest elevation, the greatest va- 
 riety of extent and direction, and to appear 
 earliest on serene weather, being indicated 
 by a few threads pencilled on the sky. Be- 
 fore storms they appear lower and denser, 
 and usually in the quarter opposite to that 
 from which the storm arises. Steady high 
 winds are also preceded aDd attended by 
 cirrus streaks, running quite across the sky 
 in the direction they blow in. 
 
 The cumulus has the densest structure, is 
 formed in the lower atmosphere, and moves 
 along with the current next the earth. A 
 small irregular spot first appears, and is as 
 it were the nucleus on which they increase. 
 The lower surface continues irregularly 
 plane, while the upper rises into conical or 
 hemispherical heaps ; which may afterwards 
 continue long nearly of the same bulk, or 
 rapidly rise into mountains. They will be- 
 gin, in fair weather, to form some hours after 
 sunrise, arrive at their maximum in the hot- 
 test part of the afternoon, then go on dimi- 
 nishing and totally disperse about sunset. 
 Previous to rain, the cumulus increases ra- 
 pidly, appears lower in the atmosphere, and 
 with its surface full of loose fleeces or pro- 
 tuberances. The formation of large cumuli 
 to leeward in a strong wind, indicates the 
 approach of a calm with rain. When they 
 do not disappear or subside about sunset, 
 but continue to rise, thunder is to be expect- 
 ed in the night. The stratus has a mean 
 degree of density, and is the lowest of clouds, 
 its iuferior surface commonly resting on the 
 earth or water. This is properly the cloud 
 of night, appearing about sunset. It com- 
 prehends all those creeping mists which in 
 calm weather ascend in spreading sheets, 
 (like an inundation of water), from the bot- 
 tom of valleys, and the surfaces of lakes and 
 rivers. On the return of the sun, the level 
 surface of this cloud begins to put on the 
 appearance of cumulus, the whole at the 
 same time separating from the ground. The 
 continuity is next destroyed, and the cloud 
 ascends and evaporates, or passes off with 
 the appearance of the nascent cumulus. 
 This has long been experienced as a prog- 
 nostic of fair weather. 
 
 The cirrus having continued for some 
 time increasing or stationary, usually passes 
 either to the cirro-cumulus or the cirro-stra- 
 tus, at the same time descending to a lower 
 station in the atmosphere. T his modifica- 
 tion forms a very beautiful sky ; is frequent 
 in summer, an attendant on w arm and dry 
 weather. The cirro-stratus , when seen in 
 the distance, frequently gives the idea of 
 shoals of fish. It precedes wind and rain, 
 is seen in the intervals of storms; and some- 
 times alternates with the cirro-cumulus in 
 
COA 
 
 COA 
 
 the same cloud, when the different evolutions 
 form a curious spectacle. A judgment may 
 be formed of the weather likely to ensue by 
 observing which modification prevails at last. 
 The solar and lunar haloes , as well as the 
 parhelion and paraselene, (mock sun and 
 mock moon), prognostics of foul weather, 
 are occasioned by this cloud. The cumulo- 
 stratus precedes, and the nimbus accompanies 
 rain. See Rain. 
 
 Mr Howard gives a view of the origin of 
 clouds, which will be found, accompanied 
 with many useful remarks, in the 16th and 
 17th volumes of the Philos. Magazine.* 
 
 Clyssus. A word formerly used to denote 
 the vapour produced by the detonation of 
 nitre with any inflammable substance. 
 
 Coax. Coal is charred in the same man- 
 ner as wood to convert it into charcoal. An 
 oblong square hearth is prepared by beating 
 the earth to a firm flat surface, and puddling 
 it over with clay. On this, the pieces of 
 coal are piled up, inclining toward one ano- 
 ther, and those of the lower strata are set up 
 on their acutest angle, so as to touch the 
 ground with the least surface possible. The 
 piles are usually from 30 to 50 inches high, 
 from 9 to 16 feet broad, and contain from 
 40 to 100 tons of coal. A number of vents 
 are left, reaching from top to bottom, into 
 which the burning fuel is thrown, and they 
 are then immediately closed with small pieces 
 of coal beaten hard in. Thus the kindled 
 fire is forced to creep along the bottom, and 
 when that of all the vents is united, it rises 
 gradually, and bursts out on every side at 
 once. If the coal contain pyrites, the com- 
 bustion is allowed to continue a considerable 
 time after the disappearance of the smoke, to 
 extricate the sulphur, part of which will be 
 found in flowers on the surface : If it con- 
 tain none, the fire is covered up soon after 
 the smoke disappears, beginning at the bot- 
 tom and proceeding gradually to the top. 
 In 50, 60, or 70 hours the fire is in general 
 completely covered with the ashes of char 
 formerly made, and in 12 or 14 days the 
 coak may be removed for use. In this way 
 a ton of coals commonly produces from 700 
 to 1100 pounds of coak. 
 
 In this way the volatile products of the 
 goal, however, which might be turned to 
 good account, are lost : but some years ago, 
 IiOrd Durulonald conceived and carried into 
 effect, a plan for saving them. By burning 
 the coal in a range of 18 or 20 stoves, with 
 as little access of air as may be, at the bot- 
 tom ; and conducting the smoke, through 
 proper horizontal tunnels, to a capacious 
 close tunnel 100 yards or more in length, 
 built of brick, supported on brick arches, 
 and covered on the top by a shallow pond 
 of water; the bitumen is condensed in the 
 form of tar : J 20 tons of coal yield about 
 
 3\ of tar, though some coals are said to be 
 so bituminous as to afford of their weight. 
 Part of the tar is inspissated into pitch, 21 
 barrels of which arc made of 28 of tar ; and 
 the volatile parts arising in this process are 
 condensed into a varnish, used for mixing 
 with colours for out-door painting chiefly. 
 A quantity of ammonia too is collected, 
 and used for making sal ammoniac. The 
 cakes thus made are likewise of superior 
 quality. 
 
 * Coal. This very important order of 
 combustible minerals, is divided by Professor 
 Jameson into the following species and sub- 
 species. 
 
 Species 1. Brown coal, already described. 
 
 Species 2. Black coal, of which there are 
 four sub-species, slate coal, cannel coal, foli- 
 ated coal, and coarse coal. 
 
 1. Slate coal. Its colour is intermediate 
 between velvet- black, and dark greyish-black. 
 It has sometimes a peacock-tail tarnish. It 
 occurs massive, and in columnar and egg- 
 shaped concretions. It has a resinous lustre. 
 Principal fracture slaty ; cross fracture, im- 
 perfect conchoidal. Harder than gypsum, 
 but softer than calcareous spar. Brittle. 
 Sp. gr. 1.26 to 1.38. It burns longer than 
 cannel coal ; cakes more or less, and leaves 
 a slag. The constituents of the slate coal of 
 Whitehaven, by Kirw'an, are 56.8 carbon, with 
 43.2 mixture of asphalt and maltha, in which 
 the former predominates. This coal is found 
 in vast quantities at Newxastle ; in the coal 
 formation which stretches from Bolton, by 
 Allonby and Workington, to Whitehaven. In 
 Scotland, in the river district of Forth and 
 Clyde ; at Cannoby, Sanquhar, and Kircon- 
 nel, in Dumfries-shire ; in Thuringia, Saxo- 
 ny, and many other countries of Germany. 
 It sometimes passes into cannel and foliated 
 coal. 
 
 2. Cannel coal. Colour between velvet 
 and greyish- black. Massive. Resinous 
 lustre. Fracture, flat-conchoidal, or even, 
 fragments trapezoidal. Hardness as in the 
 preceding sub-species. Brittle. Sp. gr. 
 1.23 to 1.27. It occurs along with the pre- 
 ceding. It is found near Whitehaven, at 
 Wigan, in Lancashire, Brosely, in Shrop- 
 shire, near Sheffield ; in Scotland, at Gil- 
 merton and Muirkirk, where it is called par- 
 ret coal. It has been worked on the lathe 
 into drinking vessels, snuff-boxes, &c. 
 
 3. Foliated coal . Its colour is velvet- 
 
 black, sometimes with iridescent tarnish. 
 Massive, and in lamellar concretions. Re- 
 sinous or splendent lustre ; uneven fracture, 
 fragments approaching to trapezoidal. Softer 
 than cannel coal ; between brittle and sec- 
 tile. Easily broken. Sp.gr. 1.34 to 1.4. 
 The Whitehaven variety consists, by Kirwan, 
 of 57 carbon, 41.3 bitumen, and 1.7 ashes. 
 It occurs in the coal formations of this and 
 
COA 
 
 other countries. It is distinguished by its 
 lamellar concretions, splendent lustre, and 
 easy frangibility. 
 
 4. Coarse coal. Colour dark greyish- 
 black, inclining to brownish- black. Mas- 
 sive, and in granular concretions. Glisten- 
 ing lustre. Fracture imperfect scaly. Frag- 
 ments indeterminate angular. Hardness as 
 above. Easily frangible, Sp. gr. 1.454. 
 It occurs in the German coal formations. 
 To the above, Professor Jameson has added 
 soot-coal ; which has a dark greyish- black 
 colour ; is massive ; with a dull semi-metal- 
 lic lustre. Fracture uneven ; sometimes 
 earthy. Shining streak ; soils ; is soft, 
 light, and easily frangible. It burns with a 
 bituminous smell, cakes, and leaves a small 
 quantity of ashes. It occurs along with 
 slate-coal in West- Lothian and the Forth 
 district ; in Saxony and Silesia. 
 
 Species 3d. Glance-coal, of which the 
 Professor gives two sub-species, pitch- coal, 
 and glance-coal. 1. Pitch-coal. Colour vel- 
 vet-black. Massive, or in plates and botroi- 
 dal branches, with a woody texture. Splen- 
 dent and resinous. Fracture, large perfect 
 conchoidal. Fragments sharp-edged and 
 indeterminate angular ; opaque ; soft; streak 
 brown coloured. Brittle, Does not soil. 
 Sp. gr. 1.3. It burns with a greenish flame. 
 It occurs along with brown coal in beds, in 
 floetz, trap, and limestone rocks, and in bitu- 
 minous shale. It is found in the Isles of 
 Sky and Faroe ; in Hessia, Bavaria, Bohe- 
 mia, and Stiria. It is used for fuel, and for 
 making vessels and snuff-boxes. It is called 
 black amber in Prussia, and is cut into rosa- 
 yics and necklaces. It is distinguished by 
 its splendent lustre and conchoidal fracture. 
 It was formerly called jet, from the river 
 Gaga in Lesser Asia. 
 
 2. Glance-coal; of which we have four 
 kinds, conchoidal, slaty, columnar, and fi- 
 brous. The conchoidal has an iron-black 
 colour, inclining to brown, with sometimes a 
 tempered steel- tarnish. Massive and vesi- 
 
 cular. Splendent, shining and imperfect 
 xnetallic lustre. Fracture flat-conchoidal ; 
 fragments sharp-edged. Hardness as above. 
 Brittle, and easily frangible. In thin 
 pieces, it yields a ringing sound. It 
 burns without flame or smell, and leaves 
 a white coloured ash. Its constituents 
 are 96.66 inflammable matter, 2 alumina, 
 and 1.58 silica and iron. It occurs in 
 beds in clay-slate, grey-wacke, and alum- 
 slate; but it is more abundant in secondary 
 rocks, as in coal and trap formations. It 
 occurs in beds in the coal formations of Ayr- 
 shire, near Cumnock and Kilmarnock ; in 
 the coal district of the Forth ; and in Staf- 
 
 COA 
 
 fordshire. It appears to pass into slaty 
 glance-coal. 
 
 Slaty glance-coal. Colour iron-black. 
 Massive. Lustre shining, and imperfect 
 
 metallic. Principal fracture slaty ; coarse 
 
 fracture imperfect conchoidal. Fragments 
 trapezoidal. Softer than conchoidal glance- 
 coal. Easily frangible ; between sectile and 
 brittle. Sp. gr. 1.50. It burns without 
 flame or odour. It consists, by Dolomieu, 
 of 72.05 carbon, 13.19 silica, 5.29 alumina, 
 5,47 oxide of iron, and 8 loss. It occurs in 
 beds or veins in different rocks. In Spain, 
 in gneiss ; in Switzerland, in mica-slate and 
 clay-slate; in the trap rock of the Calton-hill, 
 Edinburgh ; in the coal formations of the 
 Forth district. It is found also in the 
 floetz districts of Westcraigs, in West- Lo- 
 thian, Dunfermline, Cumnock, Kilmarnock, 
 and Arran ; in Brecknock, Caermarthen- 
 shire, and Pembrokeshire, in England ; and 
 at Kilkenny, Ireland; and abundantly in the 
 United States. In this country it is called 
 blind coal. 
 
 Columnar glance-coal , Colour velvet- 
 
 black and greyish-black. Massive, disse- 
 
 minated, and in prismatic concretions. Lus- 
 tre glistening, and imperfect metallic. Frac- 
 ture conchoidal. Fragments sharp-edged.. 
 Opaque. Brittle. Sp. gr. 1.4. It burns 
 without flame or smoke. It forms a bed 
 several feet thick in the coal-field of San- 
 quhar, in Dumfries-shire ; at Saltcoats, in 
 Ayrshire, it occurs in beds and in green- 
 stone ; in basaltic columnar rows near Cum- 
 nock, in Ayrshire. 
 
 Fibrous coal. Colour dark greyish-black. 
 Massive, in thin layers, and in fibrous con- 
 cretions. Lustre glimmering, or pearly. It 
 soils strongly. It is soft, passing into fria- 
 ble. It burns without flame ; but some 
 varieties scarcely yield to the most intense 
 heat. It is met with in the different coal- 
 fields of Great Britain. Its fibrous concre- 
 tions and silky lustre distinguish it from all 
 the other kinds of coal. 
 
 It is not certain that this mineral is wood 
 mineralized. Several of the varieties may 
 be original carbonaceous matter, crystalliz- 
 ed in fibrous concretions. — Jameson. 
 
 Parts. 
 
 Charcoal. 
 
 Earth. 
 
 100 Kilkenny coal contain 
 
 97.5 
 
 3*7 
 
 Anthracite, 
 
 90.0 
 
 10.0 
 
 Ditto, 
 
 72.0 
 
 20.0 
 
 Ditto, 
 
 97.25 
 
 2.7 
 
 Coal of Notre Dame de Vaux 
 
 , 78.5 
 
 20. 
 
 Die following table exhibits the results of 
 Mr Mushet’s experiments on the carboniza- 
 tion and incineration of coals : — 
 
COA 
 
 COA 
 
 4 . 
 
 Volatile 
 
 matter. 
 
 Char- 
 
 coal. 
 
 Ashes . 
 
 Sp. gr.ol 
 coal. 
 
 Sp. gr. of 
 coak. 
 
 Welsh furnace coal, 
 
 8.50 
 
 38.068 
 
 3.432 
 
 1.337 
 
 1. 
 
 Alfreton do. do. 
 
 45.50 
 
 52.456 
 
 2.044 
 
 1.235 
 
 less than 1. 
 
 Butterly do. do. 
 
 42.85 
 
 52.882 
 
 4.288 
 
 1.264 
 
 1.1 
 
 Welsh stone do. 
 
 8.00 
 
 39.700 
 
 2.300 
 
 1.368 
 
 1.39 
 
 Welsh slaty do. 
 
 9.10 
 
 84.175 
 
 6. 725 
 
 1.409 
 
 
 Derbyshire cannel do. 
 
 47.00 
 
 48.362 
 
 4,638 
 
 1.278 
 
 1.657 
 
 Kilkenny coal, 
 
 4.25 
 
 92.877 
 
 2.873 
 
 1.602 
 
 Stone-coal found under basalt, 
 
 16.66 
 
 69,74 
 
 13.600 
 
 
 
 Kilkenny slaty coal, 
 
 15.00 
 
 80.475 
 
 6.525 
 
 1.445 
 
 
 Scotch cannel-coal, 
 
 56.57 
 
 39.430 
 
 4.000 
 
 
 
 Bonlavooneen do. 
 
 13.80 
 
 82.960 
 
 3.240 
 
 1.436 
 
 1.596 
 
 Corgee coal, !> Irish. 
 
 9.10 
 
 87.491 
 
 3.409 
 
 1.403 
 
 1.656 
 
 Queen’s County, No. 59. J 
 
 tO. 30 
 
 86.560 
 
 3.140 
 
 1.403 
 
 1.622 
 
 Stone-wood Giant’s Causeway, 
 
 55. 37 
 
 54.697 
 
 11.933 
 
 1.150 
 
 
 Oak wood, 
 
 80.00 
 
 19.500 
 
 0.500 
 
 
 
 It was remarked long ago by Macquer, 
 that nitre detonates with no oily or inflam- 
 mable matter, until such matter is reduced 
 to coal, and then only in proportion to the 
 carbonaceous matter it contains. Hence it 
 occurred to Mr Kirwan, that as coals appear 
 in distillation to be for the most part merely 
 compounds of carbon and bitumen, it should 
 follow, that by the decomposition of nitre, 
 the quantity of carbon in a given quantity of 
 every species of coal may be discovered, and 
 the proportion of bitumen inferred. This 
 celebrated chemist accordingly projected on 
 a certain portion of nitre in a state of fusion, 
 successive fragments of various kinds of coal, 
 till the deflagration ceased. Coal, when in 
 jine powder, was thrown out of the crucible. 
 The experiments seem to have been judi- 
 ciously performed, and the results are there- 
 fore entitled to as much confidence as the 
 method permits. Lavoisier and Kirwan 
 state, that about 1 3 parts of dry wood-char- 
 coal decompose 1 00 of nitre. 
 
 100 parts Charcoal. 
 
 Kilkenny coal, 97.3 
 Comp, cannel, 7.5.2 
 Swansey, 73.53 
 
 Leitrim, 71.43 
 
 Wigan, 61.73 
 
 Newcastle, 58.00 
 
 "Whitehaven, 57.0 
 Slaty-cannel, 47.62 
 Asphalt, 31.0 
 
 Maltha, 8.0 
 
 Bitumen. Earth. Sp.gr. 
 0 5.7 1 .526 
 
 21.68 maltha 3.1 1.232 
 23.14 mixt. 3.33 1.357 
 
 23.37 do. 5.20 1.351 
 
 36.7 do. 1.57 1.268 
 
 40.0 do. — 1.271 
 
 41.3 1.7 1.257 
 
 32.52 mal. 20.0 1.426 
 
 68.0 bitumen — 1.117 
 
 — 2.07 
 
 100 parts of the best English coal give, 
 of coak, - - 63. by Mr Jars. 
 
 *00 do. - - 73. Ilielm. 
 
 100 do. Newcastle do. 58. Dr Watson. 
 
 Mr Kirwan says he copied the result, for 
 Newcastle coal, from Dr Watson. 
 
 ike foliated or cubical coal, and slate 
 coal, are chiefly used as fuel in private 
 houses ; the caking coals, for smithy forges ; 
 
 the slate coal, from its keeping open, answers 
 best for giving great heats in a wind fur- 
 nace, as in distillation on the great scale ; 
 and glance coal is used for drying grain and 
 malt. The coals of South Wales contain 
 less volatile matter than either the English 
 or the Scotch ; and hence, in equal weight, 
 produce a double quantity of cast iron in 
 smelting the ores of this metal. Tt is sup- 
 posed that 3 parts of good Newcastle coals, 
 are equivalent as fuel, to 4 parts of good 
 Scotch coals. 
 
 W'erner has ascertained three distinct coal 
 formations, without including the beds of 
 coal found in sandstone and limestone forma- 
 tions. The first or oldest formation, he calls 
 the independent coal formation, because the 
 individual depositions of which it is compos- 
 ed, are independent of each other, and are 
 not connected. The second is that which 
 occurs in the newest floetz-trap formation ; 
 and the third occurs in alluvial land. Wer- 
 ner observes, that a fourth formation might 
 be added, which would comprehend peat 
 and other similar substances; so that we 
 would have a beautiful and uninterrupted 
 series, from the oldest formation to the peat, 
 which is daily forming under the eye. 
 
 The independent formation contains ex- 
 clusively coarse coal, foliated coal, cannel 
 coal, slate coal, a kind of pitch coal, and 
 slaty glance coal. The latter was first found 
 in this formation in Arran, Dumfries-shire, 
 Ayrshire, and at Westcraigs, by Professor 
 Jameson. The formation in the newest 
 floetz-trap contains distinct pitch coal, co- 
 lumnar coal, and conchoidal glance coal. 
 The alluvial formation contains almost ex- 
 clusively earth coal and bituminous wood. 
 The first formation besides coal, contains 
 three rocks which arc peculiar to it ; these 
 are a conglomerate, which is more or less 
 coarse-grained ; a friable sandstone, which is 
 always micaceous ; and lastly, slate-clay. But 
 besides these, there occur also beds of harder 
 
COA 
 
 COA 
 
 sandstone, marl, limestone, porphyritic stone, 
 bituminous shale, clay-ironstone ; and, as 
 discovered by Professor Jameson, greenstone, 
 amygdaloid, and graphite. The slate-clay 
 is well characterized, by the great variety of 
 vegetable impressions of such plants as flou- 
 rish in marshes and woods. The smaller 
 plants and reeds occur in casts or impres- 
 sions always laid in the direction of the 
 strata ; but the larger arborescent plants 
 often stand erect, and their stems are filled 
 with the substance of the superincumbent 
 strata, which seems to shew that these stems 
 are in their original position. The leaves 
 and stems resemble those of palms and ferns. 
 The central, northern and western coal 
 mines of England ; the river coal districts of 
 the Forth and the Clyde, and the Ayrshire, 
 and in part the Dumfries-shire coals, belong 
 to this formation, as well as the coals in the 
 northern and western parts of France. 
 
 I3y far the most valuable and extensive beds 
 of coal which have been found and wrought, 
 are in Great Britain. The general form of 
 our great independent coal-beds, is semi- 
 circular, or semi-elliptical, being the segment 
 of a great basin. The strata have a dip or 
 declination to the horizon of from 1 in 5, to 
 1 in 20. They are rarely vertical, and sel- 
 dom perfectly horizontal to any considerable 
 extent. Slips and dislocations of the strata, 
 however, derange more or less the general 
 form of the basin. 
 
 Those who wish to understand the most 
 improved modes of working coal mines, will 
 be amply gratified by consulting, A Report 
 on the Leinster Coal District , by Richard 
 Griffith, Esq. Professor of Geology, and 
 Mining Engineer to the Dublin Society. 
 The author has given a most luminous view 
 of Mr Buddie’s ingenious system of working 
 and ventilating, in which from 7-8ths to 
 9-10ths of the whole coal may be raised; 
 instead of only which was the proportion 
 obtained in the former modes. Mr Griffith 
 has since published some other reports, the 
 whole constituting an invaluable body of 
 mining information.* 
 
 * Coal Gas. When coal is subjected in 
 close vessels to a red heat, it gives out a vast 
 quantity of gas, which being collected and 
 purified, is capablo of affording a beautiful 
 and steady light, in its slow combustion 
 through small orifices. Dr Clayton seems 
 to have been the first who performed this ex- 
 periment, with the view of artificial illumina- 
 tion, though its application to economical 
 purposes was unaccountably neglected for 
 about GO years. At length Mr Murdoch of 
 the Soho Foundry, instituted a series of ju- 
 dicious experiments on the extrication of gas 
 from ignited coal ; and succeeded in esta- 
 blishing one of the most capital improve- 
 ments which the arts of life have ever deriv- 
 ed from philosophical research and sagacity. 
 
 In the year 1798, Mr Murdoch, after se- 
 veral trials on a small scale five years before, 
 constructed at the foundry of Messrs Bol- 
 ton and Watt, an apparatus upon a large 
 scale, which during many successive nights 
 was applied to the lighting of their principal 
 building ; and various new methods were 
 practised of washing and purifying the gas. 
 In the year 1805, the cotton-mill of Messrs 
 Philips and Lee, reckoned the most exten- 
 sive in the kingdom, was partly lighted bv 
 gas under Mr Murdoch’s direction ; and the 
 light was soon extended over the whole ma- 
 nufactory. In the same year, I lighted up 
 the large lecture-room of Anderson’s Insti- 
 tution with coal-gas, generated in the labo- 
 ratory ; and continued the illumination every 
 evening through that and the succeeding 
 winter. Hence I was induced to pay parti- 
 cular attention to the theory and practice of 
 its production and use. 
 
 If coal be put into a cold retort, and slowly 
 exposed to heat, its bitumen is merely vola- 
 tilized in the state of condensible tar. Little 
 gas, and that of inferior illuminating power, is 
 produced. This distillatory temperature may 
 be estimated at about G00° or 700° F. If the 
 retort be previously brought to a bright cherry- 
 red heat, then the coals, the instant after their 
 introduction, yield a copious supply of good 
 gas, and a moderate quantity of tarry and 
 ammoniacal vapour. But when the retort 
 is heated to nearly a white incondescence, 
 the part of the gas richest in light, is attenu- 
 ated into one of inferior quality, as I have 
 shewn in detailing Berthollet’s experiments 
 on Carburetted Hydrogen. A pound of 
 good cannel coal, properly treated in a small 
 apparatus, will yield 5 cubic feet of gas, 
 equivalent in illuminating power to a mould 
 candle six in the pound. See Candle. 
 
 On the great scale, however, 3^ cubic feet of 
 good gas are all that should be expected from 
 1 pound of coal. A gas jet, which consumes 
 half a cubic foot per hour, affords a steady 
 light equal to that of the above candle. 
 
 According to Mr Murdoch’s statement, 
 presented to the Royal Society, 2500 cubic 
 feet of gas were generated in Mr Lee’s retort 
 from 7 cwt. = 784 lbs. of cannel coal. This 
 
 is nearly 5j cubic feet for every pound of coal, 
 and indicates judicious management. The 
 price of the best Wigan cannel is 13^d. per 
 cwt. (22s. 6d. per ton) delivered at Mr Lee’s 
 mill at Manchester ; or about 8s. for the se- 
 ven hundred weight. About j of the above 
 quantity of good common coal at 10s. per 
 ton, is required for fuel to heat the retorts. 
 Nearly j of the weight of the coal remains 
 in the retort in the form of coak, which is 
 sold on the spot at Is. 4d. per cwt. Jhe 
 quantity of tar produced from each ton of 
 cannel coal, is from 11 to 12 ale gallons. 
 
 The economical statement for one year is 
 given by Mr Murdoch thus : 
 
 Q r 
 
COA 
 
 COA 
 
 Cost of 1 10 tons of cannel coal, L. 1 25 
 Ditto of 40 tons of common ditto, 20 
 
 145 
 
 Deduct the value of 70 tons of coak, 95 
 
 The annual expenditure in coal, without 
 allowing any thing for tar, is - 52 
 
 And the interest of capital, and wear and 
 tear of apparatus, - - 350 
 
 Making the total annual expense of the 
 
 gas apparatus about - - 600 
 
 That of candles to give the same light, 2000 
 If the comparison had been made upon 
 an average of three hours per day, 
 instead of two hours, (all the year 
 round), then the cost from gas would 
 be only - 650 
 
 Ditto candles, - 3000 
 
 The peculiar softness and clearness of this 
 light, with its almost unvarying intensity, 
 soon brought it into great favour with the 
 work-people. And its being free from the 
 inconvenience and danger, resulting from 
 the sparks and frequent snuffing of candles, 
 
 is a circumstance of material importance, 
 tending to diminish the hazard of fire, and 
 lessening the high insurance premium on 
 cotton- mills. The cost of the attendance 
 upon candles would be fully more than upon 
 the gas apparatus ; and upon lamps greatly 
 more, in such an establishment as Mr Lee’s. 
 The preceding statements are of standard 
 authority, far above the suspicion of empiri- 
 cism or exaggeration, from which many sub- 
 sequent statements by gas-book compilers are 
 by no means exempt. 
 
 At the same manufactory, Dr Henry has 
 lately made some useful experiments on 
 the quality of the gas disengaged from the 
 same retort at different periods of the decom- 
 position. I have united in the following 
 table, the chief part of his results. He col- 
 lected in a bladder the gas, as it issued from 
 an orifice in the pipe, between the retorts and 
 the tar pit ; and purified it afterwards by 
 agitation in contact of quicklime and water. 
 Ten cwt. or 1120 lbs. of coal were contain- 
 ed in the retorts. 
 
 
 
 100 measures 
 
 190 measures 
 
 100 measures 
 
 100 combustible 
 
 
 Hours from 
 
 of impure gas 
 
 of purified gas 
 
 of purified 
 
 gas, exclusive 
 
 
 contain, 
 
 contain, 
 
 i 
 
 gas 
 
 of azote, 
 
 
 commence- 
 
 
 
 
 Other 
 
 I 
 
 
 
 
 
 • 
 
 ment. 
 
 Sulph. 
 
 hydr. 
 
 Carb. 
 
 acid. 
 
 Olef. 
 
 infl. 
 
 gases. 
 
 Azote. 
 
 Cont. 
 
 oxyg. 
 
 Give 
 car. ac. 
 
 Take 
 
 Oxyg. 
 
 Carb. 
 
 acid. 
 
 "3 
 
 
 
 
 1 
 
 C 
 
 c 
 
 c3 
 
 i 
 
 a 
 
 ot 
 
 
 16 
 
 64 
 
 20 ; 
 
 180 
 
 94 
 
 225 
 
 118 
 
 CJ 
 
 c 
 
 1 
 
 3 
 
 qx 
 
 18 
 
 77X 
 
 4I! 
 
 ^4 
 
 210 
 
 112 
 
 220 
 
 117 
 
 cJ 
 
 ,bp 
 
 V ^ 
 
 S . 
 
 5 
 
 ol 
 Z 2 
 
 91 
 
 ~2 
 
 15 
 
 80 
 
 5 
 
 200 
 
 108 
 
 210 
 
 114 
 
 5 
 
 Qj , 
 
 Z 2 
 
 OX 
 
 13 
 
 72 
 
 15 
 
 176 
 
 94 
 
 206 
 
 108 
 
 
 7 
 
 2 
 
 91 
 
 -2 
 
 9 
 
 76 
 
 15 
 
 170 
 
 83 
 
 200 
 
 98 
 
 
 9 
 
 04 
 
 OX 
 
 "2 
 
 8 
 
 77 
 
 15 
 
 150 
 
 73 
 
 176 
 
 85 
 
 
 10i 
 
 0 
 
 2 
 
 6 
 
 74 
 
 20 
 
 120 
 
 54 
 
 150 
 
 70 
 
 
 12 
 
 0 
 
 04 
 
 4 
 
 76 
 
 20 
 
 82 
 
 36 
 
 103 
 
 45 
 
 o S 
 
 1 
 
 3 
 
 3 
 
 10 
 
 90 
 
 0 
 
 164 
 
 91 
 
 164 
 
 91 
 
 
 3 
 
 2 
 
 2 
 
 9 
 
 91 
 
 0 
 
 168 
 
 93 
 
 168 
 
 98 
 
 C 
 
 O 0 
 
 5 
 
 3 
 
 2 
 
 6 
 
 94 
 
 0 
 
 132 
 
 70 
 
 132 
 
 70 
 
 s 
 
 a d 
 
 7 
 
 1 
 
 3 
 
 5 
 
 80 
 
 15 1 
 
 120 
 
 64 
 
 140 
 
 75 
 
 G G 
 
 o o 
 
 9 
 
 1 
 
 91 
 
 2 
 
 2 
 
 89 
 
 9 
 
 112 
 
 60 
 
 123 
 
 66 
 
 Qj £ 
 
 11 
 
 1 
 
 1 
 
 0 
 
 85 
 
 15 
 
 90 
 
 43 
 
 106 
 
 50 | 
 
 Or Henry conceives that gas to have the 
 greatest illuminating power, which, in a 
 given volume, consumes the largest quantity 
 ot oxygen ; and that hence the gas of cannel 
 coal is one-third better, than the gas from 
 common coal. 3500 cubic feet of gas were 
 collected from 1120 pounds of the cannel 
 coal ; and only 3000 from the same weight 
 of the Clifton coal. 
 
 1 10 m the preceding table, we see also that 
 the gas which issues at the third hour con- 
 tains, in 100 parts, of sulphuretted hydrogen 
 and carbonic acid, each 2§, of azote 4|, ole- 
 fiant gas 14±, and of other inflammable gases 
 7 6 parts. 
 
 A cubic foot of carbonic acid weighs 800 
 gr. A cubic foot of sulphuretted hydrogen 
 
 weighs 620. The first takes about 1026 gr. 
 of lime for its saturation ; the second about 
 1070 ; and hence 1050, the quantity assign- 
 ed by Dr Henry for either, is sufficiently 
 exact. 100 cubic feet ot the above impure 
 gas, containing 5 cubic feet of these two 
 gases, will require at least 2100 grains of 
 lime, or about 5 oz. avoirdupois for their 
 complete condensation. 
 
 The proportion employed by Mr Lee, is 5 
 pounds of fresh burned lime to 200 cubic 
 feet of gas. r l he lime, after being slaked, is 
 sifted, and mixed with a cubic foot (7.48 
 wine gallons) of water. This quantity of 
 cream of lime, is adequate to the ordinary 
 purification of the gas. Yet it will still 
 slightly darken a card, coated with mois- 
 
COA 
 
 CO A 
 
 tened white lead. A second exposure to 
 lime makes it absolutely pure. 
 
 Measures. Oxygen. Carb. ac. 
 
 100 crude gas, consume 190 give 108 
 
 100 gas, once washed, 175 100 
 
 100 do. twice washed, 175 100 
 
 What is separated by the first washing is 
 probably vapour of bitumen or petroleum, 
 which would injure the pipes by its deposi- 
 tion, more than it would profit, by any in- 
 creased quantity of light. Though we thus 
 see that the second washing in the above 
 experiment condensed none of the olefiant 
 gas, it is prudent not to use unnecessary agi- 
 tation with a large body of water. 
 
 The carbonate of lead precipitated from a 
 cold solution of the acetate, by carbonate of 
 ammonia, washed with water, and mixed 
 with a little of that liquid into the consistence 
 of cream, is well adapted to the separation of 
 sulphuretted hydrogen from coal gas. The 
 carbonic acid may then be withdrawn from 
 the residuary gas, by a little water of potash. 
 W e must now determine the azote present, 
 which is easily done by firing a volume of 
 this gas with thrice its volume of pure oxy- 
 gen. What remains after agitation with 
 water of potash, is a mixture of azote and 
 oxygen. Explode it with hydrogen ; one- 
 third of the diminution of volume shews the 
 oxygen ; the rest is azote. We have now 
 to eliminate three quantities, viz. the volume 
 of olefiant gas, that of common carburetted 
 hydrogen, and that of carbonic oxide. Mr 
 Faraday has proved that chlorine acts pretty 
 speedily on the second species of carburetted 
 hydrogen, and therefore it cannot be em- 
 ployed with the view of condensing merely the 
 first species. In contact with moisture, chlo- 
 rine acts also rapidly on carbonic oxide, giv- 
 ing birth to muriatic and carbonic acids. If 
 we be therefore deprived of all known means 
 of chemical elimination, we shall find a ready 
 and successful resource in the doctrines of 
 specific gravity. In any mixture of two 
 solids, two liquids, or two gases, whose spe- 
 cific gravities are known, it is easy to infer 
 from the specific gravity of the compound 
 (when the mixture is effected without change 
 of volume) the relative weights of the two 
 constituents. Thus if we apply to an alloy 
 of gold and zinc, the old problem of Archime- 
 des, we shall determine exactly the propor- 
 tion of each metal present, because the vo- 
 lume of the alloy is very nearly the sum of 
 the volumes of its ingredients. I have long 
 applied this problem to gaseous mixtures, 
 and found it a very convenient means of 
 verification on many occasions, particularly 
 in examining the nature of the residuary air 
 in the lungs of the galvanized criminal, of 
 which an account is given in the 12th Num- 
 ber of the Journal of Science. 
 
 Problem. — In 100 measures of mixed 
 gases, consisting, for example , of olejiant gas, 
 carbonic oxide, and subcarburetted hydrogen, 
 in unknown proj)ortions, to determine the 
 quantity of each. The first step is to find 
 the quantity of the two denser gases, which 
 have the same specific gravity = 0.9720. 
 
 Rule. — Multiply by 100, the difference 
 between the specific gravity of the mixture, 
 and that of the lighter gas. Divide that 
 number, by the sum of the differences of the 
 sp. gr. of the mixture, and that of the denser 
 and lighter gas ; the quotient is the per-cen- 
 tage of the denser. See Gregory's Mechanics , 
 vol. i. p. 364. 
 
 Example. — A mixture of olefiant gas, 
 carbonic oxide, and subcarburetted hydro- 
 gen, has a sp. gr. of 0.638. 
 
 What is the proportion per cent of the first 
 two? 
 
 Sp. gr. of subcarb. hydrogen, is 0.555 ; 
 0.638 — 0.555 = 0.083 . • . 100 X 0.083 = 
 8.3 
 
 O 072 
 
 * “ difference 0.332 
 
 difference O.OS3 
 
 0 .555 
 
 sum = 0.415 
 
 And 
 
 8.3 
 
 0.415 
 
 = 20 == volume of the two heavier 
 
 gases ; and therefore there are 80 of the 
 lighter gas. Hence, having fired the whole 
 with oxygen, we must allow 160 of oxygen, 
 for saturating the 80 measures of the sub- 
 
 carburetted hydrogen. Then let us sup- 
 pose 35 cubic inches more oxygen to have 
 been consumed. We know that the satu- 
 rating power of olefiant gas, and of carbonic 
 oxide with oxygen, is in the ratio of 3 to 
 0.5. Therefore, the quantity of olef. gas = 
 35 — (20 X 0.5) 
 
 3 — 0.5 
 
 25 
 
 9.5 
 
 = 10 measures. 
 
 We see now, that a gas of sp. gr. 0.658 
 consists of 
 
 0.8 measures subcarb. hydrogen = 0.444 
 
 0.1 do. olefiant gas = 0.097 
 
 0.1 do. carb. oxide = 0.097 
 
 0.638 
 
 For further details see Gas. 
 
 l)r Henry gives, at the end of his experi- 
 ments, (Manchester Memoirs, vol. iii. second 
 scries), some hypothetical representations ot 
 the constitution of coal gases, in one of which 
 he assigns, 2 of carburetted hydrogen, 
 
 2 of carbonic oxide, 
 and 15 of pure hydrogen, in lSj 
 measures. 
 
 With mixtures of three gaseous bodies, 
 the problem of eliminating the proportion 
 of the constituents, by explosion with oxy- 
 gen, becomes complex, and several hypothe- 
 tical proportions may be proposed. Rut I 
 can hardly imagine, that pure hydrogen 
 should be disengaged from ignited coal. 
 There is no violation of the doctrine of mul- 
 tiple proportions, in conceiving a compound 
 to exist in which three or more atoms of 
 
COA 
 
 COA 
 
 hydrogen may be united with one of carbon. 
 Berthollet’s experiments render this view 
 highly probable. If the above hypothetical 
 numbers were altered to 1.6 ; 2.4; and 15 ; 
 their accordance with l)r Henry’s experi- 
 ments would be improved. Now, this is a 
 considerable latitude of adjustment. 
 
 The principles laid down at the com- 
 mencement of tliis article shew, that the 
 more uniformly the coal undergoes igneous 
 decomposition, the richer is the gas. Ihe 
 retorts, if cylindrical, should not exceed, 
 therefore, 12 or 14 inches diameter, and 
 six or seven feet in length. Compressed 
 cylinders, whose length is 4^ feet, breadth 
 2 feet, and inside vertical diameter about 
 10 inches, have been found to answer well 
 at Glasgow. The cast iron of which they 
 are composed, must be screened from the 
 direct impulse of the fire, by a case of fiie- 
 brick. 
 
 On the maximum quantity of gas pro- 
 curable from coal, it is difficult to acquire 
 satisfactory information, at the great gas 
 establishments. Exaggeration seems to be 
 the prevailing foible. Mr Accum gives the 
 following tables, as the maximum results of 
 his own experiments, made at the Royal 
 Mint gas-works: — 
 
 One chaldron = 27 cwt. of coal, produces, 
 
 experiments at the gas light and coak com- 
 pany's works, Westminster station, seem 
 to prove, that decided advantages attend 
 the continuance of the process for eight 
 hours, in preference to six, or any shorter 
 period. The average product of gas, from 
 one chaldron of Newcastle coals, at six 
 hours’ charges, he states at 8,300 cubic feet, 
 and at those of eight hours, at 10,000. On 
 76 retorts, worked for a week at the latter 
 rate, he gives a statement to prove, that 
 there is a saving of L.77. 18s. above the 
 former rate of working. Two men, one by 
 day, and one by night, can attend nine or 
 ten retorts, at eight hour charges, of 100 
 pounds of coal each. 
 
 Scotch cannel yields its gas most readily, 
 
 or, - - 1.00 
 
 Newcastle coal, - - 1.04 
 
 Gloucester Low Delph, - 1.08 
 
 Newcastle, Brown’s Wall’s* end, - 1.18 
 
 Warwickshire, - - 1.65 
 
 Hence, the latter kinds afford good gas, long 
 after the former are exhausted. 
 
 The following table by Mr Peckston, ex- 
 hibits the ratio at which the gas is evolved, 
 from Bewicke and Crastor’s Wall’s-end 
 coal, when the retorts are worked at eight 
 hours’ charges: — 
 
 Cubic feet 
 of gas. 
 
 Scotch cannel coal, - 19.890 
 
 Lancashire Wigan cannel, - 19.608 
 
 Yorkshire cannel, Wakefield, 18.860 
 
 Staffordsh ire coal, 1st variety, 9.748 
 
 By experim. at "’} 2d do. 10.225 
 
 Birmingham !> 3d do. 10.866 
 
 gas-works, J 4th do. 9.796 
 
 Gloucestershire coal, High Delph, 16.584 
 Do. Low Delph, 12.852 
 
 Do. Middle Delph, 12.096 
 
 Newcastle coal, Hartley, - 16.120 
 
 Cowper’s High Main, 1 5.876 
 Tanfield Moor, 16.920 
 Pontops, - 15.112 
 
 The following varieties of coal, according 
 to Mr Accum, contain a less quantity of 
 bitumen, and a larger quantity of carbon 
 than the preceding. They soften, swell, 
 and cake on the fire, and are w r cll calculated 
 for the production of coal gas : — 
 
 One chaldron produces, 
 
 Newcastle coal, Russel’s Wall’s-end, 16.876 
 Bcw’icke and Cras- 
 tor’s WaU’s-end, 16.897 
 
 Ileaton Main, 15.876 
 
 Bleyth, . 12.096 
 
 Eden Main, - 9.600 
 
 Primrose Main, 8.348 
 
 Concerning the duration of the decompo- 
 sition ot a retort -charge of one cwt. various 
 
 ►pinions are maintained. Mr Pockston’s 
 
 ( 
 
 Cubic feet. Sura. 
 During the 1st hour are ge- 
 
 nerated, 
 
 2000 
 
 
 2d, 
 
 1495 
 
 3495 
 
 3d, 
 
 1387 
 
 4882 
 
 4 th, 
 
 1279 
 
 6161 
 
 5th, 
 
 1189 
 
 7350 
 
 6 th, 
 
 991 
 
 8341 
 
 7 th, 
 
 884 
 
 9225 
 
 8 th, 
 
 775 
 
 10000 
 
 We have already explained the principles 
 of purifying gas by milk of lime. But pre- 
 vious to its agitation with that liquid, it 
 should be made to traverse a series of refri- 
 geratory pipes submersed under cold water. 
 A vast variety of apparatus, some very in- 
 genious, but many absurd, have been con- 
 trived wdthin these few years, for exposing 
 gas to lime in the liquid or dry state. Mr 
 Accum and Mr Peckston have been at 
 much pains in describing several of them. 
 The gas holder is now generally preferred of 
 a cylindrical shape, like an immense drum, 
 open at bottom ; and fiat, or slightly conical 
 at top. The diameter is from 33 to 45 
 feet in the large establishments, and the 
 height from 18 to 24. The average capa- 
 city is from 15000 to 20000 cubic feet. It 
 is suspended in a tank ot w r ater by a strong 
 iron chain fixed to the centre of its summit, 
 which passing round a pulley, bears the 
 counter-weight. When totally immersed in 
 water, the sheet-iron, of W’hich the gas hold- 
 er is composed, loses hydrostatically about 
 
COA 
 
 COA 
 
 TaT wc 'ght ; or if equipoised when im- 
 mersed, it becomes -fj heavier when in air, 
 minus the buoyancy of the included gas. 
 
 I he mean sp. gr. ot well purified coal-gas 
 by l)r Henry’s late experiments may be com- 
 puted at 0.676, to air called 1.000; or in 
 round numbers, its density may be reckoned 
 two-thirds of that of air. One cubic foot of 
 air weighs 527 gr., one cubic foot of gas 
 weighs 351 gr. ; the difference is 17G gr. 
 Hence, 40 cubic feet have a buoyancy of one 
 pound avoirdupois. 
 
 The hydrostatic compensation is obtained 
 by making the weight of that length of the 
 suspending chain which is between the top 
 of the immersed gasometer and the tan gen- 
 tial point of the pulley-wheel, equal to one- 
 Jifteenth the weight of the gasometer in 
 pounds, minus its capacity in cubic feet, di- 
 vided by twice 40> or 80. Thus, if its weight 
 be 4 tons, or 8960 lbs ; and its capacity 
 15000 cubic feet, a length of chain equal to 
 the height of the gasometer, or to its vertical 
 play, should weigh 597 lbs. without allow- 
 ing for buoyancy. In this case, the gasome- 
 ter, when out of water, would have the buoy- 
 ancy of that liquid, replaced by the passage 
 of these 597 lbs. to the opposite side of the 
 wheel-pulley, so that twice that 'weight = 
 
 I I 94 lbs. would then be added to the con- 
 stant counterpoise. When the gasometer again 
 sinks, and loses its weight by the displace- 
 ment of the liquid, successive links of the chain 
 come over above it, augmenting its weight, 
 and diminishing that of the counterpoise, 
 by a twofold operation, as in taking a weight 
 out of one scale, and putting it in the other. 
 
 But we must now introduce the correc- 
 tion for the buoyancy of the combustible gas. 
 In ordinary cases, we must regard it as hold- 
 ing a portion of petroleum vapour diffused 
 through it, and cannot fairly estimate its sp. 
 gravity at less than 0.750; whence nearly 
 50 cubic feet have a buoyancy of one pound 
 over the same bulk of atmospheric air. If 
 we divide 1 5000 by 50, the quotient = 300 
 is the double of what must be deducted in 
 pounds weight from the hydrostatic compen- 
 sation. Thus, 597 — 150 = 44 7, is the 
 •weight of the above portion of chain. When 
 the gasometer attains its greatest elevation, 
 these 447 lbs. hang on the opposite side of 
 the wheel, constituting an increased counter- 
 poise of twice 447 = 894, to which, if we 
 add the total buoyancy of the included gas 
 = S00 lbs. we have the sum 1 1 94, equal to 
 the total increase of the weight of the iron 
 vessel on its suspension in air. 
 
 The principles of the distribution of gas 
 are exhibited in the following table, given by 
 Mr Peckston. The gas-holder is worked at 
 a pressure of one vertical inch of water, and 
 each argand burner consumes five cubic feet 
 per hour. 
 
 Inter, diamr. 
 of pipe in 
 inches. 
 
 Cubic feet 
 passing per 
 hour. 
 
 Burners 
 
 supplied. 
 
 2 
 
 8 
 
 20 
 
 4 
 
 3 
 
 Ti 
 
 50 
 
 10 
 
 4 
 
 U 
 
 90 
 
 18 
 
 5 
 
 F 
 
 160 
 
 32 
 
 0 
 
 TT 
 
 250 
 
 50 
 
 7 
 
 Ti 
 
 580 
 
 76 
 
 1 
 
 500 
 
 100 
 
 9 
 
 2000 
 
 400 
 
 3 
 
 4500 
 
 900 
 
 4 
 
 8000 
 
 1600 
 
 5 
 
 1 2500 
 
 2500 
 
 6 
 
 18000 
 
 3600 
 
 7 
 
 24500 
 
 4900 
 
 8 
 
 32000 
 
 6400 
 
 9 
 
 40500 
 
 8100 
 
 10 
 
 50000 
 
 10000 
 
 12 
 
 72000 
 
 14400 
 
 14 
 
 98000 
 
 19.600 
 
 16 
 
 128000 
 
 25.600 
 
 18 
 
 1 62000 
 
 32.400 
 
 The following statement is given by Mr 
 Accum. An argand burner, which measures 
 in the upper rim half an inch in diameter 
 between the holes from which the gas issues, 
 when furnished with five apertures l-25th 
 part of an inch diameter, consumes two cubic 
 feet of gas in an hour, when the gas flame is 
 one and a half inch high. The illuminating 
 powder of this burner is equal to three tallow 
 candles eight in the pound. 
 
 An argand burner three-fourths of an inch 
 in diameter as above, and perforated with 
 holes l-30tli of an inch diameter (what num- 
 ber? probably 15) consumes three cubic feet 
 of gas in an hour when the flame is 2^ inches 
 high, giving the light of four candles eight 
 to the pound. And an argand burner seven- 
 eighths of an inch diameter as above, perfor- 
 ated with 18 holes l-32d of an inch diame- 
 ter, consumes, when the flame is three inches 
 high, four cubic feet of gas per hour, pro- 
 ducing the light of six tallow T candles eight 
 to the pound. Increased length of flame 
 makes imperfect combustion, and diminished 
 intensity of light. And if the holes be made 
 larger than l-25th of an inch, the gas is in- 
 completely burnt. The height of the glass 
 chimney should never be less than five inches. 
 
 The argand burner called No. 4. when 
 burnt in shops from sunset till nine o’clock, 
 is charged three pounds a-year. The dia- 
 meter of its circle of holes is five-eighths of 
 an inch, and of each hole l-52d of an inch. 
 It is drilled with 1 2 holes, 5-32ds of an inch 
 from the centre of one to the centre of ano- 
 ther. Height of this burner 1-g- inches. 
 
 No. 6. argand burner. 15 apertures of 
 
COA 
 
 COB 
 
 l-32d of an inch ; diameter of their circle 
 three-fourths of an inch ; height of burner 
 two inches ; charge per annum four guineas. 
 
 According to Mr Accum, one gas lamp, 
 consuming 4 cubic feet of gas in an hour, if 
 situated 20 feet distant from the main, 
 which supplies the gas, requires a tube not 
 less than a quarter of an inch in the bore ; 2 
 lamps, 3 feet distance, require a tube three- 
 eighths of an inch ; 3 lamps, 30 feet dis- 
 tance, require a tube three- eighths : 4 lamps 
 at 40 feet one-half inch bore ; 10 lamps, 
 at 100 feet distance, require a tube three- 
 fourths of an inch ; and 20, 150 feet distant, 
 
 inch bore. 
 
 We have seen that the average product in 
 London from 1 pound of coal in 8 hours, is 
 
 cubic feet. In the Glasgow coal gas esta- 
 blishment, which is conducted by engineers 
 skilled in the principles of chemistry and 
 mechanics, fully 4 cubic feet of gas are ex- 
 tracted from every pound of coal of the 
 splent kind in 4 hour charges, from retorts 
 containing each 1 20 lbs ; which is about 
 two- thirds of their capacity. The decom- 
 posing heat is much the same as that used in 
 .London, but the retorts are compressed cy- 
 linders, a little concave below. Hence in 
 8 hours, fully double the London quantity of 
 gas, is obtained from a retort in Glasgow. 
 
 An ingenious pupil of mine, lately em- 
 ployed by a projected gas company in Glas- 
 gow to visit the principal factories of gas in 
 England, made a series of accurate experi- 
 ments on its illuminating quality in the diffe- 
 rent towns. For this purpose, he carried along 
 with him a mould candle, six in the pound, 
 and a single-jet gas-nozzle. By attaching 
 this to a gas-pipe, and producing a flame of 
 determinate length, (three inches), he could 
 then, by the method of shadows, compare 
 the flame of the gas with that of his candle, 
 and ascertain their relative proportions of 
 light. He found that the average illumi- 
 nating power of the gas in the English es- 
 tablishments, was to that of the Glasgow 
 company, as four to five ; the worst being so 
 low as three to five, and the best as five to 
 the double product of gas obtained in the 
 six. If we therefore multiply this ratio, into 
 Glasgow gas- work, we shall have the pro- 
 portion of light generated here, and in Lon- 
 don, from an equal sized retort, in an equal 
 time, as 100 to 40. This result merits 
 entire confidence. Tn the sequel of the 
 article Light, in this Dictionary, instruc- 
 tions will be given how to calculate the 
 relative illuminating powers of different 
 flames. 
 
 When the tar is passed through ignited 
 iron pipes, it yields from 10 to 15 cubic feet 
 of gas per pound. IJie deposit of refractory 
 asphaltum, however, is very apt to obstruct 
 the pipes ; and the light afforded is perhaps 
 
 of inferior quality, llcncc tar is decompos- 
 ed in very few establishments. 
 
 The film of petroleum, which floats on 
 the water of the gasometer tank, and that 
 procured from the tar by distillation, have 
 been used instead of oil for street-lamps. 
 'Fhe lamp fountain is kept on the outside of 
 the glass lantern, and the flame is made 
 small, to prevent an explosion of the vapo- 
 rized naphtha. 
 
 1430 lbs. of tar by boiling yield nine 
 cwt. of good pitch. From a chaldron of 
 Newcastle coal about 200 lbs. of ammo- 
 niacal liquor are obtained; a solution chiefly 
 of the carbonate and sulphate. The strong- 
 est liquor comes from the caking coal. A 
 gallon, or S-§ lbs. usually requires for satu- 
 ration from fifteen to sixteen ounces of oil 
 of vitriol, sp. gr. 1.84. To obtain subcar- 
 bonate of ammonia, 125 lbs. of calcined 
 gypsum in fine powder are added to 108 
 gallons of the ammoniacai liquor. The 
 mixture is stirred, and the cask containing 
 it, is then closed for three or four hours. 
 Sixteen ounces of sulphuric acid are now 
 mixed in; and the whole allowed to remain 
 at rest for four or six hours. The supernatant 
 sulphate of ammonia is next evaporated till 
 it crystallize. One hundred weight of the 
 dry crystals is mixed with one-fourth of 
 their weight of dry chalk in powder, and 
 sublimed from a cylindrical iron retort into a 
 barrel- shaped receiver of lead. A charge of 
 120 lbs. of the mixture, is usually decom- 
 posed in the course of twenty-four hours. 
 One hundred weight of dry sulphate of am- 
 monia, is said to produce from sixty to sixtv- 
 five pounds of solid subcarbonate of ammo- 
 nia. If the sulphate of ammonia, mixed 
 with common salt, is exposed to a subliming 
 heat, sal ammoniac is obtained. For oil 
 gas, see Oil.* 
 
 Coating, or Lorication. Chaptal re- 
 commends a soft mixture of marly earth, first 
 soaked in water, and then kneaded with fresh 
 horse-dung, as a very excellent coating. 
 
 The valuable method used by Mr Willis 
 of Wapping to secure or repair his retorts used 
 in the distillation of phosphorus, deserves to 
 be mentioned here. The retorts are smeared 
 with a solution of borax, to which some 
 slaked lime has been added, and when dry, 
 they are again smeared with a thin paste of 
 slaked lime and linseed oil. This paste 
 being made somewhat thicker, is applied 
 with success, during the distillation, to mend 
 such retorts as crack by the fire. 
 
 * Cobalt. A brittle, somewhat soft, but 
 difficultly fusible metal, of a reddish-grey 
 colour, of little lustre, and a sp. gr. of 8.6. 
 Its melting point is said to be 130° Wedge- 
 wood. It is generally associated in its ores 
 with nickel, arsenic, iron, and copper ; and 
 the cobalt of commerce usually contains a 
 
COB 
 
 COB 
 
 proportion of these metals. To separate them, 
 calcine with 4 parts of nitre, and wash away, 
 with hot water, the soluble arseniate of pot- 
 ash. Dissolve the residuum in dilute nitric 
 acid, and immerse a plate of iron in the so- 
 lution, to precipitate the copper. Filter the 
 liquid and evaporate to dryness. Digest the 
 mass with water of ammonia, which will dis- 
 solve only the oxides of nickel and cobalt. 
 Having expelled the excess of alkali by a 
 gentle heat from the clear ammoniacal solu- 
 tion, add cautiously water of potash, which 
 will precipitate the oxide of nickel. Filter 
 immediately, and boil the liquid, which will 
 throw down the pure oxide of cobalt. It is 
 reduced to the metallic state by ignition in 
 contact with lamp-black and oil. Mr Lau- 
 gier treats the above ammoniacal solution 
 with oxalic acid. He then redissolves the 
 precipitated oxalates of nickel and cobalt in 
 concentrated water of ammonia, and exposes 
 the solution to the air. As the ammonia ex- 
 hales, oxalate of nickel, mixed with ammo- 
 nia, is deposited. The nickel is entirely se- 
 parated from the liquid by repeated crystal- 
 lizations. There remains a combination of 
 oxalate of cobalt and ammonia, which is 
 easily reduced by charcoal to the metallic 
 state. The small quantity of cobalt remain- 
 ing in the precipitated salt of nickel, is sepa- 
 rated by digestion in water of ammonia. 
 
 Cobalt is susceptible of magnetism, but in 
 a lower degree than steel and nickel. 
 
 Oxygen combines with cobalt in two pro- 
 portions ; forming the dark blue protoxide, 
 and the black deutoxide. The first dissolves 
 in acids without effervescence. It is pro- 
 cured by igniting gently in a retort the ox- 
 ide precipitated by potash, from the nitric 
 solution. Proust says, the first oxide con- 
 sists of 100 metal 19.8 oxygen ; and Ro- 
 thoff makes the composition of the deutoxide 
 100 -j- 36.77. If we call the first 18.5 
 and the second 37 ; then the prime equiva- 
 lent of cobalt will be 5.4 ; and the two ox- 
 ides will consist of 
 
 Protox 
 
 Cobalt, 5.4 
 Oxygen, 1.0 
 
 100 84.38 
 
 18.5 15.62 
 
 100.00 
 
 Deutox 
 
 Cobalt, 
 
 Oxygen, 
 
 5.4 
 
 2.0 
 
 100 73 
 
 37 _27 
 
 100 
 
 The precipitated oxide of cobalt, washed 
 and gently heated in contact with air, passes 
 into the state of black peroxide. 
 
 When cobalt is heated in chlorine, it takes 
 fire, and forms the chloride. The iodide, 
 phosphuret, and sulphuret of this metal have 
 not been much examined. 
 
 The salts of cobalt are interesting from 
 the remarkable changes of colour which they 
 can exhibit. 
 
 Their solution is red in the neutral state, 
 
 but green, with a slight excess of acid ; the 
 alkalis occasion a blue coloured precipitate 
 from the salts of pure cobalt, but reddish- 
 brown when arsenic acid is present; sul- 
 phuretted hydrogen produces no precipitate, 
 but hydrosulphurets throw down a black 
 powder, soluble in excess of the precipitant; 
 tincture of galls gives a yellowish- white pre- 
 cipitate ; oxalic acid throw’s dow’n the red ox- 
 alate. Zinc does not precipitate this metal. 
 
 T he sulphate is formed by boiling sulphu- 
 ric acid in the metal, or by dissolving the 
 oxide in the acid. Ry evaporation, the salt 
 may be obtained in acicular rhomboidai 
 prisms of a reddish colour. These are inso- 
 luble in alcohol, but soluble in 24 parts of 
 water. It consists, by the analysis of Bu- 
 
 cholz, of; 
 
 Expert. 
 
 
 Theory. 
 
 Acid, 
 
 26 or 
 
 1 prime 5.0 
 
 24.4 
 
 Protoxide, 
 
 30 
 
 1 do. 6.4 
 
 31. 4 
 
 Water, 
 
 44 
 
 8 do. 9. 
 
 44.2 
 
 
 100 
 
 20.4 
 
 
 Dr Thomson’s hypothetical synthesis dif- 
 fers widely from the experimental, in conse- 
 quence of his assuming 3.625 for an atom of 
 the metal, and 4.625 for that of its oxide. 
 He gives 28.57 acid -j- 26.43 protoxide -j- 
 45 water. 
 
 The nitrate forms prismatic red deliques- 
 cent crystals. It is decomposable by gentle 
 ignition. The muriate is easily formed by 
 dissolving the oxide in muriatic acid. The 
 neutral solution is blue when concentrated, 
 and red when diluted ; but a slight excess of 
 acid makes it green. According to Klaproth, 
 a solution of the pure muriate forms a sym- 
 pathetic ink, whose traces become blue when 
 the paper is heated ; but if the salt be con- 
 taminated with iron, the traces become green. 
 I find that the addition of a little nitrate of 
 copper to the solution forms a sympathetic ink, 
 which by heat gives a rich greenish-yellow 
 colour. When a small quantity of muriate 
 of soda, of magnesia, or of lime is added to 
 the ink, its traces disappear very speedily on 
 removal from the fire ; shewing that the 
 vivid green, blue, or yellow colour, is owing 
 to the concentration of the saline traces by 
 heat, and their disappearance, to the reabsorp- 
 tion of moisture. At a red heat, the greater 
 part of the muriate sublimes in a grey co- 
 loured chloride. The acetate forms a sym- 
 pathetic ink, whose traces being heated, be- 
 come of a dull blue colour. Hie arseniate 
 of cobalt is found native in a fine red efflo- 
 rescence, and in crystals. See Ores of Co- 
 balt. A cream- tartrate of cobalt may be 
 obtained in large rhomboidai crystals, by add- 
 ing the tartrate of potash to cobaltic solu- 
 tions, and slow evaporation. An ammonia- 
 nitrate of cobalt may be formed in red cubi- 
 cal crystals, by adding ammonia in excess to 
 the nitric solution, and evaporating at a very 
 gentle heat. They have a urinous taste, 
 
coc 
 
 COF 
 
 and are permanent in the air. The red oxa- 
 late is soluble in an excess of oxalic acid, and 
 hence neutral oxalate of potash is the proper 
 reagent for precipitating cobalt. The phos- 
 phate may be formed by double decomposi- 
 tion. It is an insoluble purple powder, 
 which, heated along with eight parts of gela- 
 tinous alumina, produces a beautiful blue 
 pigment, a substitute for ultra-marine. The 
 colouring power of oxide of cobalt on veri- 
 fiable mixtures, is greater perhaps than that 
 of any other metal. One grain gives a full 
 blue to 240 grains of glass. Zaffre is a 
 mixture of flint powder and an impure oxide 
 of cobalt, prepared by calcination of the ores. 
 Smalt and azure blue are merely cobaltic 
 glass in fine powder. See Glass.* 
 
 * Cobalus. The demon of mines, which 
 obstructed and destroyed the miners. The 
 church service of Germany formerly contain- 
 ed a form of prayer for the expulsion of the 
 fiend. The ores of the preceding metal be- 
 ing at first mysterious and intractable, were 
 nicknamed cobalt.* 
 
 * Coccolite. A mineral of a green co- 
 lour of various shades, which occurs, massive ; 
 in loosely aggregated concretions ; and crys- 
 tallized in six-sided prisms, with two opposite 
 acute lateral edges, and bevelled on the ex- 
 tremities, with the bevelled planes set on the 
 acute lateral edges ; or in four-sided prisms. 
 The crystals are generally rounded on the 
 angles and edges. The internal lustre is 
 vitreous. Cleavage, double oblique angular. 
 Fracture uneven. Translucent on the edges. 
 It scratches apatite, but not felspar. Is 
 brittle. Sp. gr. 3.3. It fuses with difficulty 
 before the blow-pipe. Its constituents are 
 silica 50, lime 24, magnesia 10, alumina 1.5, 
 oxide of iron 7, oxide of manganese 3, loss 
 4.5. Vauquelin . 
 
 It occurs along with granular limestone, 
 garnet, and magnetic ironstone, in beds 
 subordinate to the trap formation. It is 
 found at Arendal in Norway, Nericke in 
 Sweden, Barkas in Finland, the Hartz, 
 Lower Saxony, and Spain.* 
 
 Cochineal war, at first supposed to be a 
 grain, which name it still retains by way of 
 eminence among dyers, but naturalists soon 
 discovered that it was an insect. It is 
 brought to us from Mexico, where the insect 
 lives upon different species of the opuntia. 
 
 Fine cochineal, which has been well dried 
 and properly kept, ought to be of a grey 
 colour inclining to purple. The grey is 
 owing to a powder which covers it naturally, 
 a part of which it still retains: the purple 
 tinge proceeds from the colour extracted by 
 the water in which it has been killed. 
 Cochineal will keep a long time in a dry 
 place. Ilellot says, that he tried some, one 
 hundred and thirty years old, and found it 
 produce the same effect as new. 
 
 * MM. Pelletier and Caventou have 
 
 lately found that the very remarkable colour- 
 ing matter which composes the principal 
 part of cochineal, is mixed with a peculiar 
 animal matter, a fat like common fat, and 
 with different salts. The fat having been 
 separated by ether, and the residuum treated 
 with boiling alcohol, they allowed the alco- 
 hol to cool as they gently evaporated it, and 
 by this means they obtained the colouring 
 matter; but still mixed with a little fat and 
 animal matter. These were separated from 
 it, by again dissolving it in cold alcohol, 
 which left the animal matter untouched, and 
 by mixing the solution with ether ; and thus 
 precipitating the colouring matter in a state 
 of great purity, which ffiey have called car- 
 minium. It melts at 122° Fahr. becomes 
 puffy, and is decomposed, but does not yield 
 ammonia. It is very soluble in water, 
 slightly in alcohol, and not at all in ether, 
 unless by the intermediation of fat. Acids 
 change it from crimson, first to bright red, 
 and then to yellow; alkalis, and, generally 
 speaking, all protoxides turn it violet ; alu- 
 mina takes it from water. Lake is compos- 
 ed of carminium and alumina. Carmine is 
 a triple compound of an animal matter, car- 
 minium , and an acid which enlivens the co- 
 lour. The action of muriatic acid in chang- 
 ing the crimson colour of cochineal into a 
 fine scarlet, is similar. 
 
 Dr John calls the red colouring matter 
 cochenilin. He says, the insect consists of 
 
 Cochenilin, 50.0 
 
 Jelly, 10.5 
 
 Waxv fat, 10.0 
 
 y r 
 
 Gelatinous mucus, 14.0 
 
 Shining matter, 14.0 
 
 Salts, 1 . 5 
 
 100.0 
 
 * Coffee. The seeds of the cojfea arabica 
 are contained in an oval kernel, enclosed in 
 a pulpy berry, somewhat like a cherry. The 
 ripe fruit is allowed slightly to ferment, by 
 which the pulp is more easily detached from 
 the seeds. These are afterwards washed, 
 carefully dried in the sun, and freed from 
 adhering membranes by winnowing. Be- 
 sides the peculiar bitter principle, w’hich we 
 have described under the name caffein, coffee 
 contains several other vegetable products. 
 According to Cadet, 64 parts of raw coffee 
 consist of 8 gum, 1 resin, 1 extractive and 
 bitter principle, 3.5 gallic acid, 0.14 albu- 
 men, 43.5 fibrous insoluble matter, and 6.86 
 loss. Hermann found in 1920 grains of 
 
 Levant Coffee. Mart. Coffee. 
 
 Resin, 74 68 
 
 Extractive, 320 310 
 
 Gum, 130 144 
 
 Fibrous matter, 1 335 1 386 
 
 Loss, 61 12 
 
 1 920 1 920 
 
 The nature of the volatile fragrant princU- 
 
COH 
 
 COH 
 
 pie, developed in coffee by roasting, has not 
 been ascertained. The Dutch in Surinam 
 improve the flavour of their coffee by sus- 
 pending bags of it, for two years, in a dry 
 atmosphere. They never use new coffee,* 
 
 Coffee is diuretic, sedative, and a correc- 
 tor of opium. It should be given as medi- 
 cine in a strong infusion, and is best cold. In 
 spasmodic asthma it has been particularly 
 serviceable ; and it has been recommended 
 in gangrene of the extremities arising from 
 hard drinking. 
 
 O 
 
 * Cohesion, or attraction of cohesion, is 
 that power by which 'the particles of bodies 
 are held together. The absolute cohesion of 
 solids is measured by the force necessary to 
 pull them asunder. Heat is excited at the 
 same time. At the iron cable manufactory 
 of Captain Brown, a cylindrical bar of iron, 
 1^ inch diameter, was drawn asunder by a 
 force of 43 tons. Before the rupture, the 
 bar lengthened about 5 inches, and the sec- 
 tion of fracture was reduced nearly •§• of an 
 inch. About this part, a degree of heat was 
 generated, which, according to Mr Barlow 
 of Woolwich, rendered it unpleasant, if not 
 in a slight degree painful, to grasp the bar in 
 the hand. The same thing is shewn in a 
 greater degree in wire-drawing. When the 
 force is applied to compress the body, it be- 
 comes shorter in the direction of the force, 
 which is called the compression ; and the area 
 of its section at right angles to the force, ex- 
 pands. The cohesion, calculated from the 
 transverse strength, is as near, or perhaps 
 nearer, the real cohesion, than that obtained 
 by pulling the body asunder. The cohesive 
 force of metals is much increased by wire- 
 drawing, rolling, and hammering them. In 
 the elaborate tables of cohesion drawn up by 
 Mr Thomas Tredgold, and published in the 
 50th vol. of Tilloch’s Magazine, the specific 
 cohesion of plate glass (a pretty uniform 
 body) is denoted by unity. 
 
 The following table is the result of experi- 
 ments by George Rennie, jun. Esq. publish- 
 ed in the first part of the Phil. Transactions 
 for 1818. 
 
 Mr Rennie found a cubical inch of the 
 following bodies crushed by the following 
 weights : 
 
 lbs. av. 
 
 Elm, 1284 
 
 American pine, - 1606 
 
 White deal, - - - - 1928 
 
 English oak, - 3860 
 
 Ditto of five inches long, slipped with, 2572 
 
 Ditto of four inches, ditto, - 5147 
 
 A prism of Portland stone, two inches 
 long, - - - - 805 
 
 Ditto statuary marble, - - 3216 
 
 Craigleith stone, - 8688 
 
 Cubes of 1~ inch. 
 
 Sp. gr. 
 
 Chalk, - - - —1127 
 
 Brick of a pale red colour, 2.085 1265 
 
 Roe-stone, Gloucestershire, — 1449 
 
 Sp. gr. Ib. av. 
 
 Red brick, mean of two trials, 2.168 1817 
 
 Yellow face baked Hammer- 
 smith paviors, three times, — 2254 
 
 Burnt ditto, mean of two trials, — 3243 
 
 Stourbridge, or fine brick, — 3864 
 
 Derby grit, a red friable sand- 
 stone, - - - 2.316 7070 
 
 Derby grit from another quarry, 2.428 9776 
 
 Killaly white freestone, not stra- 
 tified, - 2.423 10264 
 
 Portland, - 2.428 10284 
 
 Craigleith, white freestone, 2.452 12346 
 
 Yorkshire paving, with the 
 
 strata, - 2.507 12856 
 
 Ditto, against the strata, 2.507 12356 
 
 White statuary marble, not 
 
 veined, - - - 2.760 13632 
 
 Bramley-Fall sandstone, near 
 
 Leeds, with strata, - 2.506 13632 
 
 Ditto, against strata, - 2.506 13632 
 
 Cornish granite, - - 2.662 14302 
 
 Dundee sandstone, or breccia, 
 
 two kinds, - - 2.530 14918 
 
 A two inch cube of Portland, 2.423 14918 
 Craigleith, with strata, 2.452 15560 
 
 Devonshire red marble, varie- 
 gated, - - - — 16712 
 
 Compact limestone, - 2.584 17354 
 
 Peterhead granite, hard close- 
 
 grained, - - - — 18636 
 
 Black compact limestone, Li- 
 merick, - 2.598 19924 
 
 Purbeck, - 2.599 20610 
 
 Black Brabant marble, 2.697 20742 
 
 Very hard freestone, - 2.528 21254 
 
 White Italian veined marble, 2.726 21783 
 Aberdeen granite, blue kind, 2.625 24556 
 
 Cubes of different metals of ^th inch were 
 crushed by the following weights : 
 
 Cast iron, - - - - 9773 
 
 Cast copper, ... 7318 
 
 Fine yellow brass, - - 10304 
 
 Wrought copper, - 6440 
 
 Cast tin, - 966 
 
 Cast lead, - - - - 483 
 
 Bars of different metals, six inches long, and 
 a quarter of an inch square, were suspend- 
 ed by nippers, and broken by the following 
 
 w r eights : 
 
 Cast iron, horizontal, - - 1166 
 
 Ditto, vertical, - - - 1218 
 
 Cast steel, previously tilted, - 8391 
 
 Blistered steel, reduced by the hammer, 8322 
 Shear steel ditto, - - - 7977 
 
 Swedish iron ditto, - - 4504 
 
 English iron ditto, - - 3492 
 
 Hard gun metal, mean of two trials, 2273 
 Wrought copper, reduced by hammer, 2112 
 Cast copper, - - - 1 192 
 
 Fine yellow' brass, - - 1123 
 
 Cast tin, - -96 
 
 Cast lead, - - - - 11* 
 
 For the experiments on the twist of bats 
 we must refer to the paper. 
 
COL 
 
 COM 
 
 The strengths of Swedish and English 
 iron do not bear the same proportion to each 
 other in these experiments, that they do 
 when we compare the trials of Count Sick- 
 ingen with those made at Woolwich, of which 
 an account was given in the Annals of Phi- 
 losophy, vii. 320. From that comparison, 
 the proportional strengths were as follows : 
 English iron, - 348.38 
 
 Swedish iron, - 549.25 
 
 But from Mr Rennie’s experiments, the pro- 
 portional strengths are : 
 
 English iron, - 348.38 
 
 Swedish iron, - 449.34 
 
 A very material difference, which ought to 
 be attended to. 
 
 The following Table contains a view of 
 some former experiments, on the cohesive 
 strengths or tenacities of bodies. 
 
 A wire _J inch of zinc breaks with 26 pounds. Mechenbroek. 
 
 1 u 
 Do. 
 
 lead 
 
 29} 
 
 Emerson. 
 
 Do. 
 
 tin 
 
 49} 
 
 do. 
 
 Do. 
 
 copper 
 
 299} 
 
 do. 
 
 Do. 
 
 brass 
 
 360 
 
 do. 
 
 Do. 
 
 silver 
 
 370 
 
 do. 
 
 Do. 
 
 iron 
 
 450 
 
 do. 
 
 Do. 
 
 gold 
 
 500 
 
 do. 
 
 A cylinder 1 inch iron 
 
 63320 
 
 Rum ford, 
 
 According to Sick ingen, the relative co- 
 hesive strengths of the metals are as fol- 
 lows : 
 
 Gold, 150955 
 
 Silver, 190771 
 
 Platina, 262361 
 Copper, 304696 
 Soft iron, 362927 
 Hardiron, 559880 
 
 A wire of iron 0.078 or —7-. of an inch, 
 
 will just support 549.25 pounds. Emer- 
 son’s number for gold is excessively incor- 
 rect. In general, iron is about 4 times 
 stronger than oak, and 6 times stronger 
 than deal.* 
 
 * Cohoration. The continuous redistil- 
 lation of the same liquid, from the same ma- 
 terials. * 
 
 Colcothar. The brown-red oxide of 
 iron, which remains after the distillation of 
 the acid from sulphate of iron : it is used for 
 polishing glass and other substances by artists, 
 who call it crocus, or crocus martis. 
 
 Cold. The privation of heat. See Ca- 
 loric, Congelation, and Temperature. 
 
 Colophony. Colophony, or black resin, 
 is the resinous residuum after the distillation 
 of the light oil, and thick dark reddish bal- 
 sam, from turpentine. 
 
 * Columbium. If the oxide of columbium 
 described under Acm (Columbic) be mixed 
 with charcoal, and exposed to a violent heat 
 in a charcoal crucible, the metal columbium 
 will be obtained. It has a dark grey colour; 
 and when newly abraded, the lustre nearly 
 of iron. Its sp. gr., when in agglutinated 
 particles, was found by Dr Wollaston to be 
 5.61. These metallic grains scratch glass, 
 and are easy pulverized. Neither nitric, mu- 
 riatic, nor nitro-muriatic acid produces any 
 change in this metal, though digested on it 
 for several days. It has been alloyed with 
 iron and tungsten. Sec Acid (Columbic.)* 
 
 * Colchicum Autumnale. A medicinal 
 plant, the vinous infusion of whose root has 
 been shewn by Sir E. Home to possess specific 
 powers of alleviating gout, similar to those 
 of the empirical preparation called Eau medi - 
 cinale E’Husson. The sediment of the in- 
 fusion ought to be removed by filtration, as 
 it occasions gripes, sickness, and vomiting. * 
 
 * Colophonite. A mineral of a blackish, 
 or yellowish-brown, or orange-red colour ; 
 of a resino- adamantine lustre; and conchoidal 
 fracture. Its sp. gr. is 4.0. It consists of 
 silica 35, alumina 13.5, lime 29.0, magnesia 
 6.5, oxide of iron 7.5, oxide of manganese 
 4.75, and oxide of titanium 0.5. It occurs 
 massive, in angulo-granular concretions, and 
 in rhomboidal dodecahedrons, whose surfaces 
 have a melted appearance. It is the resin- 
 ous garnet of Haiiy and Jameson. It is 
 found in magnetic ironstone at Arendal in 
 Norway. It occurs also in Piedmont and 
 Ceylon. * 
 
 * Combination. The intimate union of 
 the particles of different substances by che- 
 mical attraction, so as to form a compound 
 possessed of new and peculiar properties. 
 See Attraction, Equivalent, and Gas.* 
 
 * Combustible. A body which, in its 
 rapid union with others, causes a disengage- 
 ment of heat and light. To determine this 
 rapidity of combination, or intensity of che- 
 mical action, a certain elevation of tempera- 
 ture is necessary, which differs for every dif- 
 ferent combustible. This difference thrown 
 into a tabular form, would constitute their 
 scale of accendibiliiy , or degree of aecension. 
 
 Stahl adopted, and refined, on the vulgar 
 belief of the heat and light coming from the 
 combustible itself; Lavoisier advanced the 
 opposite and more limited doctrine, that the 
 heat and light proceeded from the oxygenous 
 gas, in air and other bodies, which he regard- 
 ed as the true pabulum of fire. Stahl’s opi- 
 nion is perhaps more just than Lavoisier’s; for 
 
COM 
 
 COM 
 
 many combustibles burn together, without 
 the presence of oxygen or of any analogous 
 fancied supporters ; as chlorine, and the ad- 
 juncts to oxygen, have been unphilosophical- 
 ly called. Sulphur, hydrogen, carbon, and 
 azote, are as much entitled to be styled sup - 
 porters, as oxygen and chlorine, for potassi- 
 um burns vividly in sulphuretted hydrogen, 
 and in prussine, and most of the metals, 
 burn with sulphur alone. Heat and light 
 are disengaged, with a change of proper- 
 ties, and reciprocal saturation of the com- 
 bining bodies. All the combustible gases 
 are certainly capable of affording heat, to the 
 degree of incandescence, as is shewn by their 
 mechanical condensation. 
 
 Sound logic would justify us in regard- 
 ing oxygen, chlorine, and iodine, to be in 
 reality combustible bodies; perhaps more so, 
 than these substances vulgarly called com- 
 bustible. Experiments with the condensing 
 syringe, and the phenomena of the decom- 
 position of euchlorine , prove that light as well 
 as heat, may be afforded by oxygen and chlo- 
 rine. If the body, therefore, which emits, 
 or can emit, light and heat in copious streams, 
 by its action on others, be a combustible, 
 then chlorine and oxygen merit that desig- 
 nation, as much as charcoal and sulphur. 
 Azote is declared by the expounders of the 
 Lavoisierian creed, to be a simple incombus- 
 tible. Yet its mechanical condensation proves 
 that it can afford, from its own resources, an 
 incandescent heat; and with chlorine, iodine, 
 and metallic oxides, all incombustibles on 
 the antiphlogistic notion, it forms compounds 
 possessed of combustible properties, in a pre- 
 eminent and a tremendous degree of con- 
 centration. It is melancholy to reflect with 
 what easy credulity, the fictions of the 
 Lavoisierian faith, have been received and 
 propagated by chemical compilers, some- 
 times sufficiently incredulous on subjects of 
 rational belief. See the next article. 
 
 The electric polarities unquestionably 
 shew, what no person can wish to deny, that 
 between oxygen, chlorine, iodine, on one 
 hand, and hydrogen, charcoal, sulphur, 
 phosphorus, and the metals, on the other, 
 there exist striking differences. The former 
 are attracted by the positive pole, the latter 
 by the negative, in voltaic arrangements. 
 But still nothing definitive can be inferred 
 from this fact ; because in the actions of 
 what are called combustibles, on each other, 
 without the presence of the other class, we 
 have an exhibition of opposite electrical po- 
 larities. Sulphur and metallic plates, by 
 mutual friction or mere contact, produce 
 electrical changes, which apparently prove 
 that sulphur should be ranked along with 
 oxygen, chlorine, and acids, apart from com- 
 bustibles, whose polarities are negative. Sul- 
 phuretted hydrogen in its electrical relations 
 
 to metals, ranks also with oxygen and acids. 
 IIow vague and fallacious a rule of classifi- 
 cation electrical polarity would afford, may 
 be judged of from the following unquestion- 
 able facts: “ Among the substances that 
 combine chemically, all those, the electrical 
 energies of which are well known, exhibit 
 opposite states ; thus copper and zinc, gold 
 and quicksilver, sulphur and the metals, the 
 acid and alkaline substances, afford apposite 
 instances. In the voltaic combination of 
 diluted nitrous acid, zinc and copper, as is 
 well knowm, the side of the zinc exposed to 
 the acid is positive. But in combinations of 
 zinc, water, and diluted nitric acid, the sur- 
 face exposed to the acid is negative ; though 
 if the chemical action of the acid on the 
 zinc had been the cause of the effect, it ought 
 to be the same in both cases.” On some 
 chemical agencies of electricity by Sir //. 
 Davy. Phil. Trans. 1807. 
 
 Combustibles have been arranged into 
 simple and compound. The former consist 
 of hydrogen, carbon, boron, sulphur, phos- 
 phorus, and nitrogen, besides all the metals. 
 The latter class comprehends the hydrurets, 
 carburets, sulphurets, phosphurets, metallic 
 alloys, and organic products.* 
 
 * Combustion. The disengagement of 
 heat and light which accompanies chemical 
 combination. It is frequently made to be 
 synonymous with inflammation, a term which 
 might be restricted, however, to that peculiar 
 species of combustion, in which gaseous 
 matter is burned. Ignition is the incandes- 
 cence of a body, produced by extrinsic means, 
 w ithout change of its chemical constitution. 
 
 Beecher and Stahl, feeling daily the neces- 
 sity of fire to human existence, and astonish- 
 ed with the metamot'phoscs which this power 
 seemed to cause charcoal, sulphur, and me- 
 tals to undergo, came to regard combustion 
 as the single phenomenon of chemistry. L n- 
 der this impression Stahl framed his chemi- 
 cal system, the Theoria C hem ice Dogmatical, 
 a title characteristic of the dogmatic spirit 
 with which it w r as inculcated by chemical 
 professors, as the infallible code of their 
 science for almost a century. When the dis-' 
 coveries of Scheele, Cavendish, and Priestley, 
 had fully demonstrated the essential part 
 which air played, in many instances of com- 
 bustion, the French school made a small 
 modification of the German hypothesis. In- 
 stead of supposing, with Stahl, that the heat 
 and light were occasioned by the emission of 
 a common inflammable principle from the 
 combustible itself, Lavoisier and his asso- 
 ciates dexterously availed themselves of 
 Black’s hypothesis of latent heat, and main- 
 tained, that the heat and light emanated 
 from the oxygenous air, at the moment ot 
 its union or fixation with the inflammable 
 basis. IIow thoroughly the chemical mind 
 
COM 
 
 COM 
 
 has been perverted by these conjectural no- 
 tions, all our existing systems of chemistry, 
 with one exception, abundantly prove. 
 
 Dr Robison, in his preface to Black’s lec- 
 tures, after tracing with perhaps superfluous 
 zeal, the expanded ideas of Lavoisier, to the 
 neglected germs of Hooke and Mayhow, 
 says, “ This doctrine concerning combustion, 
 the great, the characteristic phenomenon of 
 chemical nature, has at last received almost 
 universal adoption, though not till after 
 considerable hesitation and opposition ; and 
 it has made a complete revolution in chemi- 
 cal science.” The French theory of che- 
 mistry, as it was called, or hypothesis of 
 combustion, as it should have been named, 
 was for some time classed in certainty with 
 the theory of gravitation. Alas ! it is vanish- 
 ing with the luminous phantoms of the day ; 
 but the sound logic, the pure candour, the 
 numerical precision of inference, which char- 
 acterize Lavoisier’s elements, will cause his 
 name to be held in everlasting admiration. 
 
 It was the rival logic of Sir H. Davy, 
 aided by his unrivalled felicity of investiga- 
 tion, which first recalled chemistry from the 
 pleasing labyrinths of fancy, to the more 
 arduous but far more profitable and progres- 
 sive career of reason. Ilis researches on 
 combustion and flame, already rich in bless- 
 ings to mankind, would alone place him in 
 the first rank of scientific genius. I shall 
 give a pretty copious account of them, since 
 by some fatality it has happened, that in 
 our best and largest system, where so many 
 pages are devoted to the reveries of ancient 
 chemists, the splendid and useful truths, 
 made known by the great chemist of Eng- 
 land, have been totally overlooked. 
 
 Whenever the chemical forces which de- 
 termine either combustion or decomposition 
 are energetically exercised, the phenomena 
 of combustion, or incandescence with a 
 change of properties, are displayed. The 
 distinction, therefore, between supporters of 
 combustion and combustibles, on which some 
 late systems are arranged, is frivolous and 
 . partial. In fact, one substance frequently 
 acts in both capacities, being a supporter ap- 
 parently at one time, and a combustible at 
 another. But in both cases the heat and 
 light depend on the same cause, and merely 
 indicate the energy and rapidity with which 
 reciprocal attractions are exerted. 
 
 Thus, sulphuretted hydrogen is a combus- 
 tible with oxygen and chlorine ; a supporter 
 with potassium. Sulphur, with chlorine and 
 oxygen, has been called a combustible basis; 
 with metals it acts the part of a supporter ; 
 for incandescence and reciprocal saturation 
 result. In like manner, potassium unites so 
 powerfully with arsenic and tellurium as to 
 produce the phenomena of combustion. Nor 
 can we ascribe the phenomena to extrusion 
 of latent heat, in conscrpicnce of condensa- 
 
 tion of volume. The protoxide of chlorine, 
 a body destitute of any combustible consti- 
 tuent, at the instant of decomposition, evolves 
 light and heat with explosive violence ; and 
 its violence becomes one-half greater. Chlo- 
 ride and iodide of azote, compounds alike 
 destitute of any inflammable matter, accord- 
 ing to the ordinary creed, are resolved into 
 their respective elements with tremendous 
 force of inflammation ; and the first expands 
 into more than 600 times its bulk. Now, 
 by the prevailing hypothesis of latent heat, 
 instead of heat and light, a prodigious cold 
 ought to accompany such an expansion. 
 The chlorates and nitrates, in like manner, 
 treated with charcoal, sulphur, phosphorus, 
 or metals, deflagrate or detonate, while the 
 volume of the combining substances is great- 
 ly enlarged. The same thing may be said 
 of the nitrogurets of gold and silver. In 
 truth, the combustion of gunpowder, a phe- 
 nomenon too familiar to mankind, should 
 have been a bar to the reception of Lavoi- 
 sier’s hypothesis of combustion. The sub- 
 terfuges which have been adopted, and ad- 
 mitted, in order to reconcile them, are un- 
 worthy to be detailed. 
 
 From the preceding facts, it is evident, 
 1st, That combustion is not necessarily 
 dependent on the agency of oxygen ; 2d, 
 That the evolution of the heat, is not to be 
 ascribed simply to a gas parting with its la- 
 tent store of that ethereal fluid, on its fixation, 
 or combustion ; and, 5dly, That “no peculiar 
 substance or form of matter is necessary for 
 producing the effect, but that it is a general 
 result of the actions of any substances possess- 
 ed of strong chemical attractions, or different 
 electrical relations, and that it takes place in 
 all cases in which an intense and violent mo- 
 tion, can be conceived to be communicated to 
 the corpuscles of bodies.” 
 
 All chemical phenomena indeed may be 
 justly ascribed to motions among the ulti- 
 mate particles of matter, tending to change 
 the constitution of the mass. 
 
 It was fashionable for a while, to attribute 
 the caloric evolved in combustion, to a di- 
 minished capacity for heat of the resulting 
 substance. Some phenomena, inaccurately 
 observed, gave rise to this generalization. 
 On this subject I shall content myself with 
 stating the conclusions to which MM. Du- 
 long and Petit have come, in consequence of 
 their own recent researches on the laws of 
 heat, and those of Berard and Delaroche. 
 “ We may likewise,” say these able chemists, 
 “ deduce from our researches another very 
 important consequence for the general theory 
 of chemical action, that the quantity of heat 
 developed at the instant of the combination 
 of bodies, has no relation to the capacity of 
 the elements, and that in the greatest num- 
 ber of cases, this loss of heat is not followed 
 by any diminution in the capacity of the 
 
COM 
 
 COM 
 
 compounds formed. Thus, for example, the 
 combination of oxygen and hydrogen, or of 
 sulphur and lead, which produces so great a 
 quantity of heat, occasions no greater altera- 
 tion in the capacity of water, or of sulphuret 
 of lead, than the combination of oxygen 
 with copper, lead, silver, or of sulphur with 
 carbon, produces in the capacities of the 
 oxides of these metals, or of carburet of sul- 
 phur.” — “ We conceive, that the relations 
 which we have pointed out between the spe- 
 cific heats of simple bodies, and of those of 
 their compounds, prevent the possibility of 
 supposing, that the heatdeveloped in chemical 
 actions, owes its origin merely to the heat pro- 
 duced by change of state, or to that supposed 
 to be combined with the material molecules.” 
 Ann ales de Chimie el Physique, x. 
 
 Mr Dalton, iu treating of the constitution 
 of elastic fluids, lays it down as an axiom, 
 that diminution of volume, is the criteri- 
 on of chemical affinity being exercised ; and 
 hence maintains, that the atmospheric air is a 
 mere mixture. Thus, also, the extrication 
 of heat from chemical union, has been usu- 
 ally referred to the condensation of volume. 
 The following examples will shew the fallacy 
 of such crude hypotheses. 1. Chlorine and 
 hydrogen mixed, explode by the sunbeam, 
 electric spark, or inflamed taper, with the 
 disengagement of much heat and light ; and 
 the volume of the mixture, which is greatly 
 enlarged at the instant of combination, suffers 
 no condensation afterwards. Muriatic acid 
 gas, having the mean density of its com- 
 ponents, is produced. 2. When one volume 
 of olefiant gas and one of oxygen are deton- 
 ated together, three and a half gaseous vo- 
 lumes result, the greater part of the hydro- 
 gen remains untouched, and a volume and a 
 half of carbonic oxide is formed, with about 
 1-1 Oth of carbonic acid. 3. The following 
 experiments of M. Gay Lussac on liquid 
 combinations are to the same purpose. 1. A 
 saturated solution of nitrate of ammonia, at 
 the temperature of 61°, and of the density 
 1.302, was mixed with water in the propor- 
 tion of 44.05 to 33.76. The temperature of 
 the mixture sank 8.9°; but the density at 
 61° was 1.159, while the mean density was 
 only 1.151. 2. On adding water to the pre- 
 
 ceding mixture, in the proportion of 33.64 
 to 39.28, the temperature sank 3.4°, while 
 the density continued 0.003 above the mean. 
 Other saline solutions presented the same re- 
 sult, though none to so great a degree. 
 
 That the internal motions which accom- 
 pany the change in the mode of combination, 
 independent of change o f form, occasion the 
 evolution of heat and light, is evident from 
 the following observations of Berzelius : — 
 In the year 1811, when he was occupied 
 with examining the combinations of anti- 
 mony, he discovered, accidentally, that seve- 
 ral metalline antimoniates, when they begin 
 
 to grow red-hot, exhibit a sudden appear- 
 ance of fire, and then the temperature again 
 sinks to that of the surrounding combusti- 
 bles. lie made numerous experiments to 
 elucidate the nature of this appearance, and 
 ascertained that the weight of the salt was 
 not altered, and that the appearance took 
 place without the presence of oxygen. Be- 
 fore the appearance of fire, these salts are 
 very easily decomposed, but afterwards they 
 are attacked neither by acids nor alkaline 
 leys — a proof that their constituents are now 
 held together by a stronger affinity, or that 
 they are more intimately combined. Since 
 that time he has observed these appearances 
 in many other bodies, as, for example, in 
 green oxide of chromium, the oxides of tan- 
 talum and rhodium. (See Chromium). 
 
 Mr Edmund Davy found, that when a 
 neutral solution of platinum was precipitated 
 by hydro- sulphuret of potash, and the preci- 
 pitate dried in air deprived of oxygen, a 
 black compound was obtained, which when 
 heated out of the contact of air, gave out 
 sulphur, and some sulphuretted hydrogen 
 gas, while a combustion similar to that in 
 the formation of the metallic sulphurets ap- 
 peared, and common sulphuret of platinum 
 remained behind. When we heat the oxide 
 of rhodium, obtained from the soda-muriate, 
 water first comes over ; and on increasing 
 the temperature, combustion takes place, 
 oxygen gas is suddenly disengaged, and a 
 suboxide of rhodium remains behind. The 
 two last cases are analogous to that of the 
 protoxide of chlorine, the exichlorine of Sir 
 H. Davy. Gadolinite, the siliciate of yttiia, 
 w r as first observed by Dr Wollaston to dis- 
 play a similar lively incandescence. The 
 variety of this mineral with a glassy fracture, 
 answers better than the splintery variety. It 
 is to be heated before the blow-pipe, so that 
 the whole piece becomes equally hot. At a 
 red-heat it catches fire. The colour becomes 
 greenish -grey, and the solubility in acids is 
 destroyed. Two small pieces of gadolinite, 
 one of which had been heated to redness, 
 were put in aqua regia ; the first was dis- 
 solved in a few hours ; the second was not 
 attacked in two months. Finally, Sir II. 
 Davy observed a similar phenomenon on 
 heating hydrate of zirconia. 
 
 'fhe verbal hypothesis of thermoxygen by 
 Brugnatelli, with Dr Thomson’s supporters, 
 partial supporters, and semicombustion, need 
 not detain us a moment from the substantial 
 facts, the noble truths, first revealed by Sir 
 II. Davy, concerning the mysterious process 
 of combustion. Of the researches which 
 brought them to light it has been said, with- 
 out any hyperbole, that “ if Bacon were to 
 revisit the earth, this is exactly such a case 
 as w r e should chuse to place before him, in 
 order to give him, in a small compass, an 
 idea of the advancement which philosophy 
 
COM 
 
 COM 
 
 lias made since the time, when he had point- 
 ed out to her the route which she ought to 
 pursue.” 
 
 The coal mines of England, alike essen- 
 tial to the comfort of her population and 
 her financial resources, had become infested 
 with fire-damp, or inflammable air, to such 
 a degree as to render the mutilation and 
 destruction of the miners, by frequent and 
 tremendous explosions, subjects of sympathy 
 and dismay to the whole nation. l>y a late 
 explosion in one of the Newcastle collieries, 
 no less than one hundred and one persons 
 perished in an instant; and the misery heap- 
 ed on their forlorn families, consisting of more 
 than three hundred persons, is inconceivable. 
 To subdue this gigantic power was the task 
 which Sir H. Davy assigned to himself ; 
 and which, had his genius been baffled, the 
 kingdom could scarcely hope to see achiev- 
 ed by another. But the stubborn forces 
 of nature can only be conquered, as Lord 
 Bacon justly pointed out, by examining 
 them in the nascent state, and subjecting 
 them to experimental interrogation, under 
 every diversity of circumstance and form. 
 It was this investigation which first laid 
 open, the hitherto unseen and inaccessible 
 sanctuary of Fire. 
 
 As some invidious attempts, however, 
 have been made, to insinuate that Sir II. 
 Davy stole the germ of his discoveries from 
 the late Mr Tennant, it may be proper to pre- 
 face the account of them by the following 
 extract from “ Resolutions of a Meeting 
 
 o 
 
 held for considering the facts relating to the 
 Discovery of the Lamp of Safety.” 
 
 “ Soho Square , Nov. 20. 1817. 
 
 “ Sd. — That Sir II. Davy not only dis- 
 covered, independently of all others, and 
 without any knowledge of the unpublished 
 experiments of the late Mr Tennant on 
 Flame, the principle of the non- communica- 
 tion of explosions through small apertures, 
 but that he has also the sole merit of having 
 first applied it to the very important purpose 
 of a safety-lamp, which has evidently been 
 imitated in the latest lamps of Mr George 
 Stephenson. 
 
 (Signed) Joseph Banks, P. R. S. 
 
 William J. Brande. 
 
 Charles Hatchett. 
 
 William Hyde Wollaston. 
 
 Thomas Young.” 
 
 See the whole document in Tilloch’s Maga- 
 zine, vol. 50. p. 587. 
 
 The phenomena of combustion may be 
 conveniently considered under six heads : 
 1st, The temperature necessary to inflame 
 different bodies. 2 d, The nature of flame, 
 and the relation between the light and heat 
 which compose it. 3d, The heat disengaged 
 by different combustibles in burning. 4 th, 
 
 The causes which modify and extinguish com- 
 bustion, and of the safe-lamp. 5th, Invisible 
 combustion. 6th, Practical inferences. 
 
 1 st, Of the temperature necessary to in- 
 fame different bodies. 1st, A simple ex- 
 periment shews the successive combustibili- 
 ties of the different bodies. Into a long 
 bottle with a narrow neck, introduce a light- 
 ed taper, and let it burn till it is extinguished. 
 Carefully stop the bottle and introduce an- 
 other lighted taper. It will be extinguished, 
 before it reaches the bottom of the neck. 
 Then introduce a small tube, containing 
 zinc and dilute sulphuric acid, at the aperture 
 of which the hydrogen is inflamed. The 
 hydrogen will be found to bum in whatever 
 part of the bottle the tube is placed. After 
 the hydrogen is extinguished, introduce light- 
 ed sulphur. This will burn for some time; 
 and after its extinction phosphorus will be 
 as luminous as in the air, and, if heated in 
 the bottle, will produce a pale yellow flame 
 of considerable density. 
 
 Phosphorus is said to take fire when heat- 
 ed to 150° and sulphur to 550°. Hydrogen 
 inflames with chlorine at a lower temperature 
 than with oxygen. By exposing oxygen 
 and hydrogen, confined in glass tubes, to a 
 very dull red (about 800 F. ) they explode. 
 When the heat was about 700 F. they com- 
 bine rapidly with a species of silent com- 
 bustion. A mixture of common air and 
 hydrogen was introduced into a small copper 
 tube, having a stopper not quite tight ; the 
 copper tube was placed in a charcoal fire ; 
 before it became visibly red-hot an explosion 
 took place, and the stopper w r as driven out. 
 We see, therefore, that the inflaming tempe- 
 rature is independent of compression or rare- 
 faction. 
 
 The ratio of the combustibility of the dif- 
 ferent gaseous matters, is likewise to a certain 
 extent, as the masses of heated matters re- 
 quired to inflame them. Thus, an iron wire 
 l-40th of an inch, heated cherry-red, will 
 not inflame olefiant gas, but it will inflame 
 hydrogen gas. A wire of l-8th, heated to 
 the same degree, will inflame olefiant gas. 
 
 But a wire of an inch, must be heated 
 to whiteness to inflame hydrogen, though at 
 a low red-heat it will inflame bi-phosphu- 
 retted gas. Yet wire of l-40th, heated even 
 to whiteness, will not inflame mixtures of 
 fire-damp. Carbonic oxide inflames in the 
 atmosphere when brought into contact with 
 an iron wire heated to dull redness ; whereas 
 carburetted hydrogen is not inflammable, 
 unless the non is heated to whiteness, so 
 as to burn with sparks. 
 
 These circumstances will explain, why a 
 mesh of wire, so much finer or smaller, is 
 required to prevent the explosion from hy- 
 drogen and oxygen, from passing ; and why 
 so coarse a texture and wire are sufficient to 
 prevent the explosion of the fire-damp, for- 
 
COM 
 
 COM 
 
 tunately the least combustible of all the 
 inflammable gases known. The flame of 
 sulphur, which kindles at so low a tempera- 
 ture, will exist under refrigerating processes, 
 which extinguish the flame of hydrogen and 
 all carburetted gases. 
 
 Let the smallest possible flame be made 
 by a single thread of cotton immersed in oil, 
 and burning immediately upon the surface 
 of the oil. It will be found to yield a flame 
 about 1-SOtli of an inch in diameter. Let 
 
 a fine iron wire of of an inch, made 
 into a ring of 1-1 Oth of an inch diameter, 
 be brought over the flame. Though at such 
 a distance, it will instantly extinguish the 
 flame, if it be cold ; but if it be held above 
 the flame, so as to be slightly heated, the 
 flame may be passed through it without be- 
 ing extinguished. That the effect depends 
 entirely on the power of the metal to ab- 
 stract the heat of flame, is shewn by bringing 
 a glass capillary ring of the same diameter 
 and size over the flame. This being a much 
 worse conductor of heat, will not, even when 
 cold, extinguish it. If its size, however, be 
 made greater, and its circumference smaller, 
 it will act like the metallic wire, and require 
 to be heated to prevent it from extinguishing 
 the flame. Now, a flame of sulphur may 
 be made much smaller than that of hydrogen ; 
 one of hydrogen may be made much smaller 
 than that of a wick fed w r itn oil ; and that of 
 a wick fed with oil smaller than that of car- 
 buretted hydrogen. A ring of cool wire, 
 which instantly extinguishes the flame of 
 carburetted hydrogen, diminishes but slightly 
 the size of a flame of sulphur, of the same 
 dimensions. 
 
 By the following simple contrivance, we 
 may determine the relative facility of burn- 
 ing, among different combustibles. Prepare 
 a series of metallic globules of different sizes, 
 by fusion at the end of iron wires, and light 
 a series of very minute flames of different 
 bodies all of one size. If a globule l -20th 
 of an inch diameter be brought near an oil 
 flame of 1 -30th in diameter, it will extinguish 
 it, when cold, at the distance of a diameter. 
 The size of the spherule, adequate to the 
 extinction of the particular flame, will be a 
 measure of its combustibility. If the globule 
 be heated, however, the distance will dimi- 
 nish at which it produces extinction. At a 
 white heat, the globule, in the above instance, 
 does not extinguish it by actual contact, 
 though at a dull red- heat it immediately 
 produces the effect. 
 
 2d, Of the nature of fame, and of the re- 
 lation between the light and the heat which 
 compose it. The flame of combustible bodies 
 may in all cases be considered, as the com- 
 bustion of an explosive mixture of inflammable 
 gas, or vapour, with air. It cannot be re- 
 garded as a mere combustion, at the surrace 
 of contact, of the inflammable matter. This 
 
 fact is proved by holding a taper, or a piece 
 of burning phosphorus, within a large flame 
 made by the combustion of alcohol. The 
 flame of the taper, or of the phosphorus, will 
 appear in the centre of the other flame, prov- 
 ing that there is oxygen even in its interior 
 part. When a wire-gauze safe-lamp is made 
 to burn in a very explosive mixture of coal 
 gas and air, the light is feeble and of a pale 
 colour. Whereas the flame of a current of 
 coal gas burnt in the atmosphere, as is well 
 known by the phenomena of the gas lights, 
 is extremely brilliant. It becomes, therefore, 
 a problem of some interest, “ Why the com- 
 bustion of explosive mixtures, under different 
 circumstances, should produce such different 
 appearances?” In reflecting on the circum- 
 stances of these two species of combustion. 
 Sir H. Davy was led to imagine that the cause 
 of the superiority of the light of the stream of 
 coal gas, might be owing to the decomposition 
 of a part of the gas, towards the interior of 
 the flame, where the air was in the smallest 
 quantity, and the deposition of solid charcoal, 
 which first by its ignition, and afterwards by 
 its combustion, increased, in a high degree, 
 the intensity of the light. The following 
 experiments shew, that this is the true solu- 
 tion of the problem. 
 
 If we hold a piece of wire-gauze, of about 
 900 apertures to the square inch, over a 
 stream of coal gas issuing from a small pipe, 
 and if we inflame the gas above the wire- 
 gauze, left almost in contact with the orifice 
 of the pipe, it burns with its usual bright 
 light. On raising the wire-gauze so as to 
 cause the gas to be mixed w ith more air be- 
 fore it inflames, the light becomes feebler, 
 and at a certain distance the flame assumes 
 the precise character of that of an explosive 
 mixture burning within the lamp. But 
 though the light is so feeble in this case, the 
 heat is greater than when the light is much 
 more vivid. A piece of wire of platma, held 
 in this feeble blue flame, becomes instantly 
 white- hot. 
 
 On reversing the experiment by inflam- 
 ing a stream of coal gas, and passing a piece 
 of wire- gauze gradually from the summit of 
 the flame to the orifice of the pipe, the result 
 is still more instructive. It is found that 
 the apex of the flame, intercepted by the w ire- 
 gauze, affords no solid charcoal ; but in pass- 
 ing it downwards, solid charcoal is given off 
 in considerable quantities, and prevented 
 from burning by the cooling agency ot the 
 wire-gauze. At the bottom of the flame, 
 wdiere the gas burned blue, in its immediate 
 contact with the atmosphere, charcoal ceased 
 to be deposited in visible quantities. 
 
 The principle of the increase ot the brilli- 
 ancy and density of flame, by the production 
 and ignition of solid matter, appears to ad- 
 mit of many applications. Thus, olefiant 
 gas gi \ os the most brilliant white light of all 
 
COM 
 
 COM 
 
 combustible gases, because, as we learn from 
 JBerthollet’s experiments, related under car- 
 buretted hydrogen, at a very high tempera- 
 ture, it deposits a very large quantity ot solid 
 carbon. Phosphorus, which rises in vapour 
 at common temperatures, and the vapour of 
 which combines with oxygen at those tem- 
 peratures, is always luminous ; for each par- 
 ticle of acid formed, must, there is every 
 reason to believe, be white-hot. So few of 
 these particles, however, exist in a given 
 space, that they scarcely raise the tempera- 
 ture of a solid body exposed to them, though, 
 as in the rapid combustion of phosphorus, 
 where immense numbers are existing in a 
 small space, they produce a most intense 
 heat. 
 
 The above principle readily explains the 
 appearances of the different parts of the 
 flames of burning bodies, and of flame urged 
 by the blow-pipe. The point of the inner 
 blue flame, where the heat is greatest, is the 
 point where the whole of the charcoal is 
 burned in its gaseous combinations, without 
 previous deposition. 
 
 It explains also the intensity of the light 
 of those flames in which flxed solid matter is 
 produced in combustion, such as the flame 
 of phosphorus and of zinc in oxygen, &c. 
 and of potassium in chlorine, and the feeble- 
 ness of the light of those flames in which 
 gaseous and volatile matter alone is produc- 
 ed, such as those of hydrogen and of sul- 
 phur in oxygen, phosphorus in chlorine, Sec. 
 
 It offers means of increasing the light of 
 certain burning substances, by placing in 
 fcheir flames even incombustible substances. 
 Thus the intensity of the light of burning 
 sulphur, hydrogen, carbonic oxide, &c. is 
 wonderfully increased by throwing into them 
 oxide of zinc, or by placing in them very 
 fine amianthus or metallic gauze. 
 
 It leads to deductions concerning the 
 chemical nature of bodies, and various phe- 
 nomena of their decomposition. Thus ether 
 burns with a flame, which seems to indicate 
 the presence of olefiant gas in that substance. 
 Alcohol burns with a flame similar to that 
 of a mixture of carbonic oxide and hydro- 
 gen. Hence the first is probably a binary 
 compound of olefiant gas and water, and the 
 second of carbonic oxide and hydrogen. 
 \V hen protochloride of copper is introduced 
 into the flame of a candle or lamp, it affords 
 a peculiar dense and brilliant red light, 
 tinged with green and blue towards the 
 edges, which seems to depend upon the 
 chlorine being separated from the copper by 
 tlie hydrogen, and the ignition and combus- 
 tion of the solid copper and charcoal. 
 
 Similar explanations may be given of the 
 phenomena presented by the action of other 
 combinations of chlorine on flame; and it 
 is probable, in many of those cases, when 
 the colour of flame is changed by the 
 
 introduction of incombustible compounds, 
 that the effect depends on the production, 
 and subsequent ignition or combustion of 
 inflammable matter from them. Thus the 
 rose-coloured light given to flame by the 
 compounds of strontium and calcium, and 
 the yellow colour given by those of barium, 
 and the green by those of boron, may de- 
 pend upon a temporary production of these 
 bases, by the inflammable matter of the flame. 
 Dr Clarke’s experiments on the reduction 
 of barytes, by the hydroxygen lamp, is fa- 
 vourable to this idea. Nor should any sup- 
 posed inadequacy of heat in ordinary dame, 
 prevent us from adopting this conclusion. 
 Flame, or gaseous matter, heated so highly 
 as to be luminous, possesses a temperature 
 beyond the white heat of solid bodies, as is 
 shewn by the circumstance, that air not 
 luminous will communicate this degree of 
 beat. This is proved by a simple experi- 
 ment. Hold a fine wire of platinum about 
 l-20th of an inch from the exterior of the 
 middle of the dame of a spirit-lamp, and 
 conceal the dame by an opaque body. The 
 wire will become white-hot in a space, where 
 there is no visible light. The real tempe- 
 rature of visible dame is perhaps as high as 
 any we are acquainted with. Mr Tennant 
 used to illustrate this position, by fusiug a 
 small dlament of platinum, in the flame of a 
 common candle. 
 
 These views will probably offer illustra- 
 tions of electrical light. The voltaic arc of 
 dame from the great battery, differs in co- 
 lour and intensity, according to the substan- 
 ces employed in the circuit, and is indnitely 
 more brilliant and dense w ith charcoal than 
 with any other substance. May not this de- 
 pend, says Sir H. Davy, upon particles of 
 the substances separated by the electrical at- 
 tractions? And the particles of charcoal, be- 
 ing the lightest among solid bodies (as their 
 prime equivalent shews), and the least cohe- 
 rent, would be separated in the largest quan- 
 tities. 
 
 The heat of dames may be actually dimi- 
 nished by increasing their light (at least the 
 heat communicable to other matter), and vice 
 versa. The dame from combustion, which 
 produces the most intense heat amongst 
 those which have been examined, is that of a 
 mixture of oxygen and hydrogen compressed 
 in Newman’s blow-pipe apparatus. (See 
 Blow- Pipe). This flame is hardly visible 
 in bright day-light, yet it instantly fuses the 
 most refractory bodies ; and the light from 
 solid bodies ignited in it, is so vivid as to be 
 painful to the eye. This application cer- 
 tainly originated from Sir H. Davy’s dis- 
 covery, that the explosion from oxygen and 
 hydrogen would not communicate through 
 very small apertures, and he himself first 
 tried the experiment with a fine glass capil- 
 lary tube. The dame was not visible at the 
 
COM 
 
 COM 
 
 end of this tube, being overpowered by the 
 brilliant star ol the glass, ignited at the aper- 
 ture. 
 
 o. Of the heat disengaged by different com- 
 bustibles in the act of burning. 
 
 Lavoisier, Crawford, Dalton, and Rum- 
 ford, in succession, made experiments to de- 
 termine the quantity of beat evolved in the 
 
 combustion of various bodies. The appa- 
 ratus used by the last was perfectly simple, 
 and perhaps the most precise of the whole. 
 The heat was conducted by Rattened pipes 
 of metal, into the heart of a body of water, 
 and was measured by the temperature im- 
 parted. The following is a general table of 
 results : — 
 
 Substances burned, 1 lb. 
 
 Oxygen 
 consumed 
 in lbs. 
 
 Ice melted in lbs. 
 
 Lavoisier. 
 
 Crawford. 
 
 Dalton . 
 
 . | 
 
 Rumford. 
 
 Hydrogen, 
 
 7.5 
 
 295.6 
 
 480 
 
 320 
 
 
 Carburetted hydrogen, 
 
 4 
 
 
 
 85 
 
 
 Olefiant gas, 
 
 3.50 
 
 
 
 8S 
 
 
 Carbonic oxide, 
 
 0.58 
 
 
 
 25 
 
 
 Olive oil, 
 
 3.00 
 
 149 
 
 89 
 
 104 
 
 94.07 
 
 Rape oil, 
 
 3.0 
 
 
 
 
 124.10 
 
 Wax, - - - 
 
 5.0 
 
 133 
 
 97 
 
 104 
 
 126.24 
 
 Tallow, 
 
 3.0 
 
 96 
 
 
 104 
 
 111.58 
 
 Oil of turpentine, 
 
 
 
 
 60 
 
 
 Alcohol, 
 
 2.0? 
 
 
 
 58 
 
 67.47 
 
 Ether sulphuric, 
 
 3 
 
 
 
 62 
 
 107.03 
 
 Naphtha, 
 
 
 
 
 
 97.83 
 
 Phosphorus, 
 
 1.S3 
 
 100 
 
 
 60 
 
 
 Charcoal, 
 
 2.66 
 
 96.5 
 
 69 
 
 40 
 
 
 Sulphur, 
 
 1.00 
 
 
 
 20 
 
 
 Camphor, 
 
 
 
 
 70 
 
 
 Caoutchouc, 
 
 
 
 
 42 
 
 
 The discrepancies in the preceding table, 
 are sufficient to shew the necessity of new' ex- 
 periments on the subject. Count Rumford 
 made a series of experiments on the heat 
 given out during the combustion of different 
 w oods. He found that one pound of w ood 
 by burning, produced as much heat as would 
 have melted from about 34 to 54 pounds of 
 ice. The average quantity is about 40. MM. 
 Clement and Desormes find that woods give 
 out heat in the ratio of their respective quan- 
 tities of carbon ; which they state to be equal 
 to one-half of their total weight. Hence 
 they assign 48 pounds as the quantity of ice 
 melted, in burning one of wood. In treating 
 of acetic acid and carbon, I have already taken 
 occasion to state, that they appear greatly to 
 overrate the proportion of carbon in woods. 
 
 The preceding table is incorrectly given in 
 several respects by our systematic writers ; Dr 
 Thomson, for example, states, that 1 pound 
 of hydrogen consumes only 6 pounds of 
 oxygen, though the saturating proportion as- 
 signed by him is 8 pounds. The proportions 
 of oxygen consumed by olive oil, phosphorus, 
 charcoal, and sulphur, are all in like manner 
 erroneous. 
 
 In vol. i. p. 1S4. of Dr Black’s lectures, 
 we have the following notes. “ 100 pounds 
 weight of the best Newcastle coal, when ap- 
 plied by the most judiciously constructed 
 furnace, will convert about 1^ wine hogsheads 
 
 of water, into steam that supports the pres- 
 sure of the atmosphere.” 1^ hogsheads of 
 water, weigh about 790 pounds. Hence 1 part 
 of coal will convert nearly 8 parts of water 
 into steam. Count llumford says, that the 
 heat generated in the combustion of 1 pound 
 of pit-coal, would make 56j~y pounds of ice- 
 cold water boil. But we know that it re- 
 quires fully 5 \ times as much heat to convert 
 the boiling water into steam. Therefore, 
 
 7 -r- = 6 %-, is the weight of water that would 
 
 be converted into steam by one pound of 
 coal. 
 
 Mr Watt found, that it requires 8 feet 
 surface of boiler to be exposed to fire to boil 
 off one cubic foot of water per hour, and that 
 a bushel, or 84 pounds of Newcastle coal so 
 applied, will boil off from 8 to 12 cubic feet. 
 He rated the heat expended in boiling olf a 
 cubic foot of water, to be about six times as 
 much as would bring it to a boiling heat from 
 the medium temperature (55°), in this cli- 
 mate. The mean quantity is 10 cubic feet, 
 which weigh 625 pounds. Hence 1 pound 
 of coal burnt, is equivalent to boil off in 
 steam, nearly 7 } lbs of water, at the tempe- 
 rature of 55°. 
 
 In situations where wood was employed 
 for fuel to Mr Watt’s engines, he allowed three 
 times the weight of it, that he did of New- 
 castle coal. The cubical coal of the Glasgow 
 
COM 
 
 COM 
 
 coal district, is reckoned to have only J the 
 calorific power of the Newcastle coal ; and 
 the small coal or culm, requires to be used in 
 double weight, to produce an equal heat with 
 the larger pieces. A bushel of Newcastle 
 coal is equivalent to a hundred weight of the 
 Glasgow. v 
 
 I shall now describe the experiments re- 
 cently made on this subject by Sir H, Davy, 
 subservient to his researches on the nature of 
 dame. A mercurial gas-holder, furnished 
 with a system of stop-cocks, terminated in a 
 strong tube of platinum, having a minute 
 aperture. Above this, was fixed a copper 
 cup filled with olive oil, in which a thermo- 
 meter was placed. The oil was heated to 
 212°, to prevent any difference in the com- 
 munication of heat, by the condensation of 
 aqueous vapour; the pressure was the same 
 for the different gases, and they were con- 
 sumed as nearly as possible in the same time, 
 and the flame applied to the same point of 
 the copper cup, the bottom of which was 
 wiped after each experiment. The results 
 were as follows : — 
 
 Substances. 
 
 Rise of therm, 
 from 212° to 
 
 Oxygen Ratios of 
 consumed, heat. 
 
 Olefiant gas, 
 
 270° 
 
 6.0 
 
 9.66 
 
 Hydrogen, 
 
 238 
 
 1.0 
 
 26.0 
 
 Sulph. hydrogen, 252 
 
 5.0 
 
 6.66 
 
 Coal gas, 
 
 23 6 
 
 4.0 
 
 6.00 
 
 Carbonic oxide, 
 
 218 
 
 1.0 
 
 6,00 
 
 The data on which Sir II. calculates the 
 ratios of heat, are the elevations of tempera- 
 ture, and the quantities of oxygen consumed 
 conjointly. "YYe see that hydrogen produces 
 more heat in combustion than any of its com- 
 pounds, a fact accordant with Mr Dalton’s 
 results in the former table ; only Sir H. 
 Davy’s ratio is more than double that of Mr 
 Dalton’s, as to hydrogen, and carburetted 
 hydrogen. On this point, however, Sir H. 
 with his usual sagacity remarks, that it will 
 be useless to reason upon the ratios as exact, 
 for charcoal was deposited from both the 
 olefiant gas and coal gas during the experi- 
 ment, and much sulphur was deposited from 
 the sulphuretted hydrogen. It confirms, 
 however , the general conclusions, and proves 
 that hydrogen stands at the head of the scale, 
 and carbonic oxide at the bottom. It might 
 at first view be imagined, that, according to 
 this scale, the flame of carbonic oxide ought 
 to be extinguished by rarefaction at the same 
 degree as that of carburetted hydrogen ; but 
 it must be remembered, as has been already 
 shewn, that carbonic oxide is a much more 
 easily kindled, a more accendible gas. 
 
 4. Of the causes which modify or extin- 
 guish combustion or fame. 
 
 The earlier experimenters upon the Bov- 
 lean vacuum observed, that flame ceased in 
 highly rarefied air; but the degree of rare- 
 
 faction necessary for this effect has been dif- 
 ferently stated. On this point, Sir II. Davy’s 
 investigations are peculiarly beautiful and in- 
 structive. When hydrogen gas, slowly pro- 
 duced from a proper mixture, was inflamed 
 at a fine orifice of a glass tube, as in Priest- 
 ley’s philosophical candle, so as to make a jet 
 of flame of about 1 -6th of an inch in height, 
 and introduced under the receiver of an air- 
 pump, containing from 200 to ,300 cubical 
 inches of air, the flame enlarged as the re- 
 ceiver became exhausted ; and when the 
 gauge indicated a pressure, between 4 and 5 
 times less than that of the atmosphere, was 
 at its maximum of size ; it then gradually 
 diminished below, but burned above, till its 
 pressure was betw een 7 and 8 times less ; 
 when it became extinguished. 
 
 To ascertain whether the effect depended 
 upon the deficiency of oxygen, he used a larger 
 jet with the same apparatus, when the flame, 
 to his surprise, burned longer; even when 
 the atmosphere was rarefied 10 times; and 
 this in repeated trials. When the larger jet 
 was used, the point of the glass tube became 
 white-hot, and continued red-hot till the 
 flame was extinguished. It immediately 
 occurred to him, that the heat, communicated 
 to the gas by this tube, was the cause that 
 the combustion continued longer in the last 
 trials when the larger flame was used ; and 
 the following experiments confirmed the con- 
 clusion. A piece of wire of platinum was 
 coiled round the top of the tube, so as to 
 reach into and above the flame. The jet of 
 gas of l-6th of an inch in height was light- 
 ed, and the exhaustion made. The w ire of 
 platinum soon became white-hot in the cen- 
 tre of the flame, and a small point of wire 
 r.*ar the top fused. It continued white-hot, 
 till the pressure was 6 times less. When it 
 was 10 times, it continued red-hot at the 
 upper part, and as long as it was dull red, 
 the gas, though certainly extinguished below , 
 continued to burn in contact with the hot 
 wire, and the combustion did not cease, un- 
 til the pressure was reduced 13 times. 
 
 It appears from this result, that the flame 
 of hydrogen is extinguished in rarefied at- 
 mospheres, only when the heat it produces 
 is insufficient to keep up the combustion ; 
 which appears to he when it is incapable of 
 communicating visible ignition lo metal ; 
 and as this is the temperature required for 
 the inflammation of hydrogen, (see section 
 1st), at common pressure, it appears that its 
 combustibility is neither diminished nor in- 
 creased by rarefaction from the removal of 
 pressure. 
 
 According to this view, with respect to hy- 
 drogen, it should follow, that those amongst 
 other combustible bodies, which require less 
 heat for their accension, ought to hum in 
 more rarefied air than those that require 
 mole heat; and those which produce much 
 
COM 
 
 COM 
 
 heat in their combustion ought to burn, 
 other circumstances being the same, in more 
 rarefied air, than those that produce little 
 heat. Every experiment since made, con- 
 firms these conclusions. Thus olefiant gas, 
 which approaches nearly to hydrogen, in the 
 temperature produced by its combustion, 
 and which does not require a much higher 
 temperature for its accension, when its flame 
 was made by a jet of gas from a bladder 
 connected with a small tube, furnished with 
 a wire of platinum, under the same circum- 
 stances as hydrogen, ceased to burn when 
 the pressure was diminished between 10 and 
 1 1 times. And the flames of alcohol and of 
 the wax taper, which require a greater con- 
 sumption of caloric for the volatilization and 
 decomposition of their combustible matter, 
 were extinguished when the pressure was 5 
 or 6 times less without the wire of platinum, 
 and 7 or 8 times less when the wire was kept 
 in the flame. Light carburetted hydrogen, 
 which produces, as we have seen, less heat in 
 combustion than any of the common com- 
 bustible gases, except carbonic oxide, and 
 which requires a higher temperature for its 
 accension than any other, has its flame ex- 
 tinguished, even though the tube was fur- 
 nished with the wire when the pressure w as 
 below 1 -4 th. 
 
 The flame of carbonic oxide, which though 
 it produces little heat in combustion, is as 
 accendible as hydrogen, burned when the 
 wire was used, the pressure being l-6th. 
 
 The flame of sulphuretted hydrogen, the 
 heat of which is in some measure carried off 
 by the sulphur, produced by its decomposi- 
 tion during its combustion in rare air, when 
 burned in the same apparatus as the olefiant 
 and other gases, was extinguished when the 
 pressure was 1 - 7 th . 
 
 Sulphur, which requires a lower tempera- 
 ture for its accension, than any common in- 
 flammable substance, except phosphorus, 
 burned with a very feeble blue flame in air 
 rarefied 15 times; and at this pressure the 
 flame heated a wire of platinum to dull red- 
 ness; nor was it extinguished till the pressure 
 was reduced to l -20th. From the preceding 
 experimental facts we may infer, that the taper 
 w r ould be extinguished at a height of between 
 9 and 10 miles, hydrogen between 12 and 13, 
 and sulphur between 15 and 16. 
 
 Phosphorus, as has been shewn by M. 
 Van Marum, burns in an atmosphere rare- 
 fied 60 times. Sir II. Davy found, that 
 phosphu retted hydrogen produced a flash of 
 light when admitted into the best vacuum 
 that could be made, by an excellent pump of 
 Nairn’s construction. 
 
 Chlorine and hydrogen inflame at a much 
 lower temperature, than oxygen and hydro- 
 gen. Hence the former mixture explodes 
 when rarefied 24 times ; the latter ceases to 
 explode when rarefied 1 S times. Heat cx- 
 
 trinsically applied, carries on combustion, 
 when it wmuld otherwise be extinguished. 
 Camphor in a thick metallic tube, which 
 disperses the heat, ceases to burn in air rare- 
 fied 6 times; in a glass tube which becomes 
 ignited, the flame of camphor exists under a 
 ninefold rarefaction. Contact with a red- 
 hot iion, makes naphtha glow with a lam- 
 bent flame at a rarefaction of 30 times ; 
 though without foreign heat, its flame dies 
 at an atmospheric rarefaction of 6. If the 
 mixture of oxygen and hydrogen expanded 
 to its non-explosive tenuity, be exposed to 
 the ignition of a glass tube, the electric spark 
 will then cause an explosion, at least in the 
 heated portion of the gases. 
 
 We shall now detail briefly the effects of 
 rarefaction by heat on combustion and ex- 
 plosion. Under Caloric we have shewn, 
 that air by being heated from 32° to 212° 
 expands |-, or 8 parts become 1 1 ; hence 
 the expansion of one volume of air at 
 212° into 2^, or the augmentation of 1.5 = 
 
 which Sir H. Davy found to take place 
 when the enclosing glass tube began to 
 soften with ignition, will indicate 932°. 
 For J- : 180°: : : 720°, to which if we 
 
 add 212°, the sum is 932°. One of air at 21 2 
 becoming 2^, as took place in the other ex- 
 periment of Sir H. Davy, will give us 
 
 (180° X V°) + 212°= 812°, for the heat 
 of fusible metal luminous in the shade. I 
 believe these experiments to be much more 
 accurate than any hitherto given, relative to 
 the temperature of incandescence. This 
 philosopher, whose ingenuity of research is 
 usually guided by the most rigorous arith- 
 metic, estimates the first temperature from 
 the above data of Gay Lussac, at 1055° 
 Fahrenheit. I therefore hesitate to offer a 
 discordant computation. One volume of 
 air at 212°, should become at a temperature 
 of 1035°, according to the rule I use, 2.715 
 parts, instead of 2.5. 
 
 Sir H. introduced into a small glass tube 
 over well boiled mercury, a mixture of tw-o 
 parts of hydrogen and one of oxygen, and 
 heated the tube by a spirit-lamp, till the 
 volume of the gas was increased from 1 to 
 2.5. J3y means of a blow-pipe and another 
 lamp, he made the upper part of the tube 
 red-hot, when an explosion instantly took 
 place. This experiment refutes the notions 
 of M. de Grotthus, on the non-explosiveness 
 of that mixture, when expanded by heat. 
 He introduced into a bladder a mixture of 
 oxygen and nitrogen, and connected this 
 bladder with a thick glass tube of about one- 
 sixth of an inch in diameter, and three feet 
 long, curved so that it could be gradually 
 heated in a charcoal furnace ; two spirit- 
 lamps were placed under the tube, where it 
 entered the charcoal fire, and the mixture 
 was very slowly passed through. An ex- 
 
COM 
 
 COM 
 
 plosion took place, before the tube was red- 
 hot. This fine experiment shews, that ex- 
 pansion by heat, instead of diminishing the 
 accendibility of gases, enables them, on the 
 contrary, to explode apparently at a lower 
 temperature ; which seems perfectly reason- 
 able, as a part of the heat communicated by 
 any ignited body, must be lost in gradually 
 raising the temperature. 
 
 M. de Grotthus has stated, that if a glow- 
 ing coal be brought into contact with a mix- 
 ture of oxygen and hydrogen, it only rare- 
 fies them, but does not explode them. This 
 depends on the degree of heat communicat- 
 ed by the coal. If it is red in day-light, 
 and free from ashes, it uniformly explodes 
 the mixture. If its redness be barely visi- 
 ble in the shade, it will not explode them, 
 but cause their slow combination. The 
 general phenomenon is wholly unconnected 
 with rarefaction, as is shewn by the follow- 
 ing circumstance : When the heat is greatest, 
 and before the invisible combination is com- 
 pleted, if an iron wire, heated to whiteness, 
 be placed upon the coal within the vessel, the 
 mixture instantly explodes. 
 
 Subcarburetted hydrogen, or fire-damp, 
 as has been shewn, requires a very strong 
 heat for its inflammation. It therefore of- 
 fered a good substance for an experiment, on 
 the effect of high degrees of rarefaction, by 
 heat on combustion. One part of this gas, 
 and eight of air, were mixed together, and 
 introduced into a bladder furnished with a 
 capillary tube. This tube was heated till it 
 began to melt. The mixture was then pass- 
 ed through it, into the flame of a spirit-lamp, 
 when it took fire, and burned with its own 
 peculiar explosive light, beyond the flame of 
 the lamp ; and when withdrawn, though the 
 aperture was quite white-hot, it continued to 
 burn vividly. 
 
 That the compression in one part of an 
 explosive mixture, produced by the sudden 
 expansion of another part by heat, or the 
 electric spark, is not the cause of combus- 
 tion, as has been supposed by Mr Higgins, 
 M. Berthollet, and others, appears to be 
 evident from what has been stated, and is 
 rendered still more so by the following facts : 
 A mixture of bi-phosphuretted hydrogen gas 
 and oxygen, which explode at a heat a little 
 above that of boiling water, was confined by 
 mercury, and very gradually heated on a 
 sand bath. AVhen the temperature of the 
 mercury was 242°, the mixture exploded. 
 A similar mixture was placed in a receiver 
 communicating with a condensing syringe, 
 and condensed over mercury till it occupied 
 only one-fifth of its original volume. No ex- 
 plosion took place, and no chemical change had 
 occurred; for when its volume was restored 
 it was instantly exploded by the spirit-lamp. 
 
 It would appear then that the heat given 
 
 47 
 
 out by the compression of gases, is the real 
 cause of the combustion which it produces ; 
 and that at certain elevations of temperature, 
 whether in rarefied or compressed atmos- 
 pheres, explosion or combustion occurs ; that 
 is, bodies combine with the production of 
 heat and light. 
 
 Since it appears that gaseous matter ac- 
 quires a double, triple, quadruple, &c. bulk, 
 by the successive increments of 480° F. 2 
 X 480°, 5 X 480°, &c. we may gain ap- 
 proximations to the temperature of flame, by 
 measuring the expansion of a gaseous mix- 
 ture at the instant of explosion, provided the 
 resulting compound gas occupy, after cooling, 
 the same bulk as the sum of its constituents. 
 Now this is the case with chlorine and hy- 
 drogen, and with prussine and oxygen. The 
 latter detonated in the proportion of one to 
 two, in a tube of about two-fifths of an inch 
 diameter, displaced a quantity of water, 
 which demonstrated an expansion of 15 
 times their original bulk. Hence 15 X 480° 
 = 7200° of Fahr., and the real temperature 
 is probably much higher ; for heat must be 
 lost by communication to the tube and the 
 water. The heat of the gaseous carbon in 
 combustion in this gas, appears more intense 
 than that of hydrogen ; for it was found that 
 a filament of platinum was fused by a flame 
 of prussine (cyanogen) in the air, which was 
 not fused by a similar flame of hydrogen. 
 
 We have thus detailed the modifications 
 produced in combustion by rarefaction, me- 
 chanical and calorific. It remains on this 
 head to state the effects of the mixture of 
 different gases, and those of different cool- 
 ing orifices, on flame. 
 
 In Sir H. Davy’s first paper on the fire- 
 damp of coal mines, he mentioned that car- 
 bonic acid had a greater influence in destroy- 
 ing the explosive power of mixtures of fire- 
 damp and air, than azote ; and he supposed 
 the cause to be its greater density and capa- 
 city for heat, in consequence of which it 
 might exert a greater cooling agency, and 
 thus prevent the temperature of the mixture 
 from being raised to that degree necessary 
 for combustion. He subsequently made a 
 series of experiments with the view of deter- 
 mining how far this idea is correct, and 
 for the purpose of ascertaining the general 
 phenomena, of the effects of the mixture of 
 gaseous substances upon explosion and com- 
 bustion. 
 
 He took given volumes, of a mixture of 
 two parts of hydrogen and one part of oxy- 
 gen by measure, and diluting them with 
 various quantities of different elastic fluids, 
 he ascertained at what degree of dilution, 
 the power of inflammation by a strong spark 
 from a Leyden phial was destroyed. He 
 found that for one ot the mixture, inflamma- 
 tion was 
 
COM 
 
 COM 
 
 Prevented by 
 
 Of hydrogen, g 
 
 Oxygen, 9 
 
 Nitrous oxide, 1 1 
 
 Subcarburetted hydrogen, 1 
 
 Sulphuretted hydrogen, 2 
 
 Olefiant gas, X 
 
 Muriatic acid gas, 2 
 
 Chlorine, „ 
 
 Silicated fiuoric gas, j-Q 
 
 Azote, . 
 
 Carbonic acid, 
 
 The first column of the preceding table 
 shews, that other causes, besides density and 
 capacity for heat, interfere with the pheno- 
 mena. Thus nitrous oxide, which is nearly 
 one-third denser than oxygen, and which, 
 according to Delaroche and Berard, has a 
 greater capacity for heat, in the ratio of 
 1.5505 to 0.0765 by volume, has lower 
 powers of preventing explosion. Hydrogen 
 also, which is fifteen times lighter than oxy- 
 gen, and which in equal volumes has a 
 smaller capacity for heat, certainly has a 
 higher power of preventing explosion ; and 
 olefiant gas exceeds all other gaseous sub- 
 stances, in a much higher ratio than could 
 have been expected, from its density and 
 capacity. 
 
 I have deduced the third column, from Sir 
 H. Davy’s experiments on the relative times 
 in which a thermometer, heated to 1 60°, 
 when plunged into a volume of 21 cubic 
 inches of the respective gases at 52°, took to 
 cool down to 106°. Where an elastic fluid 
 exerts a cooling influence on a solid surface, 
 the effect must depend principally upon the 
 rapidity with which its particles change their 
 places ; but where the cooling particles are 
 mixed throughout a mass with other gaseous 
 particles, their effect must depend princi- 
 pally upon the power they possess of rapidly 
 abstracting heat from the contiguous parti- 
 cles ; and this will depend probably upon 
 two causes, the simple abstracting power by 
 which they become quickly heated, and their 
 capacity for heat, which is great in propor- 
 tion as their temperatures are less raised by 
 this abstraction. The power of elastic fluids 
 to abstract heat from solids, appears from 
 the above experiments to be in some inverse 
 ratio to their density ; and there seems to 
 be something in the constitution of the light 
 gases, which enables them to carry off heat 
 from solid surfaces in a different manner 
 from that in which they would abstract it in 
 gaseous mixtures, depending probably on the 
 mobility of their parts. Those particles 
 which are lightest must be conceived most 
 
 <D 
 
 capable of changing place, and would there- 
 fore cool solid surfaces most rapidly ; in the 
 cooling of gaseous mixtures, the mobility 
 of the particles can be of little consequence. 
 
 Whatever be the cause of the different 
 
 rermitted with Cooling power, air = 1. 
 
 6 
 
 2.66 
 
 7 
 
 1.12 
 
 10 
 
 •2 
 
 0.75 (the mean) 
 
 ■f 2. 1 3 (coal gas) 
 
 li. 
 
 1 \ 
 
 1 in 
 
 1 
 
 T 
 
 1.6 
 
 
 0.66 
 
 X % 
 
 1.33 
 
 - 
 
 0.727 
 
 cooling powers of the different elastic fluids 
 in preventing inflammation, very simple ex- 
 periments shew that they operate uniformly 
 with respect to the different species of com- 
 bustion ; and that those explosive mixtures, 
 or inflammable bodies, which require least 
 heat for their combustion, require larger 
 quantities of the different gases to prevent 
 the effect, and vice versa. Thus one of chlo- 
 rine and one of hydrogen still inflame when 
 mixed with eighteen times their bulk of oxy- 
 gen ; whereas a mixture of carburetted hydro- 
 gen and oxygen, in the proper proportions (one 
 and two) for combination, have their inflam- 
 mation prevented by less than three times 
 their volume of oxygen. A w ax taper was in- 
 stantly extinguished in air mixed with one- 
 tenth of silicated fluoric acid, and in air 
 mixed with one- sixth of muriatic acid gas ; 
 but the flame of hydrogen burned readily 
 in those mixtures ; and in mixtures which 
 extinguished the flame of hydrogen, the flame 
 of sulphur burned. ( See the beginning of* 
 section 1 st ). 
 
 In cases, however, in which the heat re- 
 quired for chemical union is very small, as 
 in the instance of hydrogen and chlorine, a 
 mixture which prevents inflammation will 
 not prevent combination, that is, the gases 
 will combine without anv flash. If two vo- 
 
 r 
 
 lumes of carburetted hydrogen be added to 
 a mixture of one of chlorine, with one of 
 hydrogen, muriatic acid is formed through- 
 out the mixture and heat produced, as was 
 evident from the expansion when the spark 
 passed, and the rapid contraction afterwards ; 
 bat the heat was so rapidly carried off bv the 
 quantity of carburetted hydrogen, that no 
 flash was visible. 
 
 Experiments on combustion in condensed 
 air, to see if the cooling power was much in- 
 creased thereby, shew that, as rarefaction 
 docs not diminish considerably the heat of 
 flame in atmospherical air, so neither does 
 condensation considerably increase it ; a cir- 
 cumstance of great importance in the consti- 
 tution of our atmosphere, which at all heights 
 or depths, at which man can exist, still pre- 
 serves the same relations to combustion. 
 
 It may be concluded from the general 
 law, that at high temperatures, gases not 
 concerned in combustion Mill have les* 
 
COM 
 
 COM 
 
 power of preventing that operation, and like- 
 wise that steam and vapours, which require 
 a considerable heat for their formation, will 
 have less effect in preventing combustion, 
 particularly of those bodies requiring low- 
 temperatures, than gases at the usual heat of 
 the atmosphere. Thus, a very large quantity 
 of steam is required to prevent sulphur from 
 burning. A mixture of oxygen and hydro- 
 gen will explode by the electric spark, 
 though diluted with five times its volume of 
 steam ; and even a mixture of air and car- 
 buretted hydrogen gas, the least explosive of 
 all mixtures, requires a third of steam to 
 prevent its explosion, whereas one- fifth of 
 azote will produce that effect. These trials 
 were made over mercury. Heat was ap- 
 plied to water over the mercury, and 37.5 
 for 1 00 parts = f, was regarded as the cor- 
 rection for the expansion of the gases. 
 
 We shall now treat of the effects of cooling 
 orifices on fame. The knowledge of the 
 cooling power of elastic media , in preventing 
 the explosion of the fire-damp, led the illus- 
 trious English chemist, to those practical re- 
 searches, which terminated in his grand dis- 
 covery of the w 7 ire- gauze safe-lamp. The 
 general investigation of the relation and ex- 
 tent of those powers, serves to elucidate the 
 opeiation of wire-gauze and other tissues or 
 systems of apertures, permeable to light and 
 air, in intercepting flame, and confirms the 
 views originally given of this marvellous 
 phenomenon. We have seen that fame is 
 gaseous matter, heated so highly as to be 
 luminous, and that to a degree of tempera- 
 ture beyond the w 7 hite heat of solid bodies ; 
 for air not luminous w'ill communicate this 
 degree of heat. When an attempt is made 
 to pass flame through a very fine mesh of 
 wh e-gauze or the common temperature, the 
 gauze cools each portion of the elastic mat- 
 ter that passes through it, so as to reduce its 
 temperature below that degree at which it is 
 luminous. This diminution of temperature 
 is proportional to the smallness of the mesh 
 and to the mass of the metal. The power 
 of a metallic or other tissue to prevent ex- 
 plosion, will depend upon the heat required 
 to produce the combustion, as compared 
 with that acquired by the tissue. Hence, 
 the flame of the most inflammable sub- 
 stances, and of those that produce most 
 heat m combustion, will pass through a 
 metallic tissue, that will interrupt the flame 
 of less inflammable substances, or those that 
 produce little heat in combustion. Or the 
 tissue being the same, and impermeable to all 
 «ames at common temperatures, the flames 
 of the most combustible substances, and of 
 those which produce most heat, will most 
 
 and d e 7 h aSS -n hr ° Ugh itj " hen k is he ^ed, 
 
 delr V^ 1 PaS " tllr ° Ugh k at a different 
 
 degree of temperature. In short, all the 
 circumstances which apply to the effect of 
 
 Z 
 
 cooling mixtures upon flame, will apply to 
 cooling perforated surfaces. Thus, the flame 
 of phosphuretted hydrogen, at common tem- 
 peratures, will pass through a tissue suffi- 
 ciently large, not to be immediately choaked 
 up by the phosphoric acid formed, and the 
 phosphorus deposited. If a tissue, contain- 
 ing above 700 apertures to the square inch, 
 be held over the flame of phosphorus or 
 phosphuretted hydrogen, it does not trans- 
 mit the flame till it is sufficiently heated to 
 enable the phosphorus to pass through it in 
 vapour. Phosphuretted hydrogen is decom- 
 posed by flame, and acts exactly like phos- 
 phorus. In like manner, a tissue of 100 
 apertures to the square inch, made of a wire 
 
 of will, at common temperatures, inter- 
 cept the flame of a spirit-lamp, but not that 
 of hydrogen. But when strongly heated, it 
 no longer arrests the flame of alcohol. A 
 tissue which will not interrupt the flame of 
 hydrogen when red-hot, will still intercept 
 that of olefiant gas; and a heated tissue, 
 which would communicate explosion from a 
 mixture of olefiant gas and air, will stop an 
 explosion from a mixture of fire-damp, or 
 carburetted hydrogen. The latter gas re- 
 quires a considerable mass of heated metal 
 to inflame it, or contact with an extensive 
 heated surface. An iron wire of 3 -20th of 
 an inch, and eight inches long, red-hot, 
 when held perpendicularly in a stream of 
 coal gas, did not inflame it; nor did a short 
 wire of one-sixth of an inch produce the ef- 
 fect, when held horizontally. But wire of 
 the latter size, when six inches of it were 
 red-hot, and when it was held perpendicu- 
 larly, in a bottle containing an explosive 
 mixture, so that heat was communicated 
 successively to portions of the gas, produced 
 its explosion. 
 
 The scale of gaseous accension, given in 
 the first section, explains, why so fine a 
 mesh of wire is required to hinder the explo- 
 sion from hydrogen and oxygen, to pass ; 
 and why so coarse a texture and wire, con- 
 troul the explosion of fire-damp. The ge- 
 neral doctrine, indeed, of the operation of 
 wire-gauze, cannot be better elucidated, 
 than in its effects upon the flame of sulphur. 
 When wire-gauze, of 600 or 700 apertures 
 to the square inch, is held over the flame, 
 fumes of condensed sulphur immediately 
 come through it, and the flame is intercept- 
 ed. The fumes continue for some instants, 
 but on the increase of the heat, they dimi- 
 nish ; and at the moment when they disap- 
 pear, which is long before the gauze becomes 
 red-hot, the flame passes; the temperature 
 at which sulphur burns being that at which 
 it is gaseous. 
 
 Where rapid currents of explosive mix- 
 tures, however, are made to act upon wire- 
 gauze, it is ot course much more rapidly 
 heated ; and therefore, the same mesh which 
 
COM 
 
 COM 
 
 arrests the flames of explosive mixtures at 
 rest, will sillier them to pass when in rapid 
 motion. But, by increasing the cooling sur- 
 face, by diminishing the apertures in size, or 
 increasing their depth, all flames , however 
 rapid their motion, map be arrested. Pre- 
 cisely the same law applies to explosions 
 acting in close vessels. Very minute aper- 
 tures, when they are only few in number, 
 will permit explosions to pass, which are ar- 
 rested by much larger apertures when they 
 fill a whole surface. A small aperture was 
 drilled at the bottom of a wire-gauze lamp, 
 in the cylindrical ring, which confines the 
 gauze. This, though less than yg- of an 
 inch in diameter, transmitted the flame, and 
 fired the external atmosphere, in conse- 
 quence of the whole force of the explosion 
 of the thin stratum of the mixture, includ- 
 ed within the cylinder, driving the flame 
 through the aperture. Had the whole ring, 
 however, been composed of such apertures 
 separated by wires, it would have been per- 
 fectly safe. 
 
 Nothing can demonstrate more decided- 
 ly, than these simple facts and observations, 
 that the interruption of flame, by solid tis- 
 sues, permeable to light and air, depends 
 upon no recondite or mysterious cause, but 
 on their cooling powers, simply considered 
 as such. When a light, included in a cage 
 of wire-gauze, is introduced into an explo- 
 sive atmosphere of fire-damp at rest, the 
 maximum of heat is soon obtained ; the ra- 
 diating power of the wire, and the cooling 
 effect of the atmosphere, more efficient from 
 the admixture of inflammable air, prevent 
 it from ever arriving at a temperature equal 
 to that of dull redness. In rapid currents 
 of explosive mixtures of fire-damp, which 
 heat common gauze to a higher tempera- 
 ture, twilled gauze, in which the radiating 
 surface is considerably greater, and the cir- 
 culation of air less, preserves an equable 
 temperature. Indeed, the heat communi- 
 cated to the wire by combustion of the fire- 
 damp in wire-gauze lamps, is completely in 
 the power of the manufacturer. By diminish- 
 ing the apertures, and increasing the mass 
 of metal, or the radiating surface, it may be 
 diminished to any extent. Thick twilled 
 gauze, made of wires ^j, 16 to the warp, 
 and 30 to the weft, rivetted to the screw, to 
 prevent the possibility of displacement, forms 
 a lamp cage, which, from its flexibility, can- 
 not be broken, and from its strength cannot 
 be crushed, except by a very violent blow. 
 The lamp which has been found most con- 
 venient for the miner, is that composed of a 
 cylinder of strong wire-gauze, fastened 
 round the flame by a screw, and in which 
 the wick is trimmed by a wire passing 
 through a safe aperture. Such have now 
 been used for many years, in the most dan- 
 gerous miues of England, without any acci- 
 
 dent. Whatever explosive disasters have 
 happened since, may be imputed to the ne- 
 glect, or gross and culpable mismanagement, 
 of that infallible protector. See Lamp. 
 
 When the fire-damp is inflamed in the 
 wire-gauze cylinders, coal dust thrown into 
 the lamp, bums with strong flashes and scin- 
 tillations. The miners were at first alarmed 
 by an effect of this kind, produced by the 
 dust naturally raised during the working of 
 the coals. 
 
 But Sir II. Davy shewed, by decisive ex- 
 periments, that explosion could never be 
 communicated by them, to the gas of any 
 mine. He repeatedly threw coal dust, pow- 
 dered rosin, and witch-meal, through lamps 
 burning in more explosive mixtures, than 
 ever occur in coal mines ; and though he 
 kept these substances floating in the explo- 
 sive atmosphere, and heaped them upon the' 
 top of the lamp when it was red-hot, no ex- 
 plosion could ever be communicated. Phos- 
 phorus or sulphur, are the only substances 
 which can produce explosion, by being ap- 
 plied to the outside of the lamp ; and sul- 
 phur, to produce the effect, must be appli- 
 ed in large quantities, and fanned by a 
 current of fresh air. He has even blown 
 repeatedly, fine coal dust mixed with minute 
 quantities of the finest dust of gunpowder, 
 through the lamp burning in explosive mix- 
 tures, without any communication of explo- 
 sion. The most timorous female might 
 traverse an explosive coal mine, guided by 
 the light of the double cylinder lamp, with- 
 out feeling the slightest apprehension. 
 
 5. We have now arrived at the most 
 curious of all Sir H.’s discoveries relative 
 to fire, namely, invisible combustion . 
 
 On passing mixtures of hydrogen and 
 oxygen through tubes heated below redness, 
 steam appeared to be formed without any 
 combustion. This led him to expose mix- 
 tures of oxygen and hydrogen to heat, in 
 tubes, in which they were confined by fluid 
 fusible metal. He found, that, by carefully 
 applying a heat between the boiling point of 
 mercury, which is not sufficient for the ef- 
 fect, and a heat approaching to the greatest 
 heat that can be given without making glass 
 luminous in darkness, the combination was 
 effected without any violence, and without 
 any light; and commencing with 212, the 
 volume of steam formed at the point of com- 
 bination, appeared exactly equal to that of 
 the original gases. So that the first effect 
 in experiments of this kind, is an expansion, 
 afterwards a contraction, and then the res- 
 toration of the primitive volume. 
 
 When this change is going on, if the heat 
 be quickly raised to redness, an explosion 
 takes place. With small quantities of gas, 
 the invisible combustion is completed in 
 less than a minute. It is probable that 
 the slow combination without combustion, 
 
COM 
 
 COM 
 
 long ago observed with respect to hydrogen 
 and chlorine, oxygen and metals, will hap- 
 pen at certain temperatures with most sub- 
 stances that unite by heat. On trying char- 
 coal, he found, that at a temperature which 
 appeared to be a little above the boiling point 
 of quicksilver, it converted oxygen pretty ra- 
 pidly into carbonic acid, without any lumi- 
 nous appearance ; and at a dull red-heat, the 
 elements of olefiant gas combined in a simi- 
 lar manner with oxygen, slowly and without 
 explosion. The effect ot the slow combina- 
 tion of oxygen and hydrogen is not connect- 
 ed with their rarefaction by heat, for it took 
 place when the gases were confined in a tube 
 by fusible metal, rendered solid at its upper 
 surface ; and certainly as rapidly, and with- 
 out any appearance of light. 
 
 As the temperature of flame has been 
 shewn to be infinitely higher than that ne- 
 cessary for the ignition of solid bodies, it ap- 
 peared probable, that in these silent com- 
 binations of gaseous bodies, when the in- 
 crease of temperature may not be sufficient to 
 render the gaseous matters themselves lumi- 
 nous, yet it still might be adequate to ignite 
 solid matters exposed to them. 
 
 Sir H. Davy had devised several experi- 
 ments on this subject. He had intended to 
 expose fine w'ires to oxygen and olefiant gas, 
 and to oxygen and hydrogen, during their 
 slow combination under different circum- 
 stances, when he was accidentally led to the 
 knowledge of Xhefact, and at the same time 
 to the discovery of a new and curious series 
 of phenomena. 
 
 He was making experiments on the in- 
 crease of the limits of the combustibility of 
 gaseous mixtures of coal gas and air, by in- 
 crease of temperature. For this purpose, a 
 small wire-gauze safe-lamp, with some fine 
 wire of platinum fixed above the flame, was 
 introduced into a combustible mixture, con- 
 taining the maximum of coal gas. When 
 the inflammation had taken place in the wire- 
 gauze cylinder, he threw in more coal gas, 
 expecting that the heat acquired by the mix- 
 ed gas, in passing through the wire-gauze, 
 would prevent the excess from extinguishing 
 the flame. The flame continued for two or 
 three seconds after the coal gas was intro- 
 duced ; and when it was extinguished, that 
 part of the wire of platinum which had been 
 hottest, remained ignited, and continued so 
 for many minutes. When it was removed 
 into a dark room, it was evident that there 
 was no flame in the cylinder. 
 
 It was immediately obvious that this was 
 the result which he had hoped to attain by 
 other methods, and the oxygen and coal gas 
 in contact with the hot wire, combined with- 
 out flame, and yet produced heat enough to 
 preserve the wire ignited, and keep up their 
 own secret combustion. The truth of this 
 conclusion was proved by introducing a heat- 
 
 ed wire of platinum into a similar mixture. 
 It immediately became ignited nearly to 
 whiteness, as if it had been in actual com- 
 bustion itself, and continued glowing for a 
 long while. When it was extinguished, the 
 inflammability of' the mixture was found to be 
 entirely destroyed . A temperature much below 
 ignition only, w r as necessary for producing 
 this curious phenomenon, and the wire was 
 repeatedly taken out and cooled in the at- 
 mosphere till it ceased to be visibly red ; yet 
 when admitted again, it instantly became 
 red-hot. 
 
 The same phenomena were produced w ith 
 mixtures of olefiant gas and air, carbonic 
 oxide, prussic gas, and hydrogen ; and in 
 this last case with a rapid production of wa- 
 ter. The degree of heat could be regulated 
 by the thickness of the wire. When of the 
 same thickness, the wire became more ignit- 
 ed in hydrogen, than in mixtures of olefiant 
 gas, and more in mixtures of olefiant gas, 
 than in those of gaseous oxide of carbon. 
 
 When the wire was very fine, as l- 80 th of 
 an inch in diameter, its heat increased in 
 very combustible mixtures, so as to explode 
 them. The same wire in less combustible 
 mixtures, continued merely bright red, or 
 dull red, according to the nature of the mix- 
 ture. In mixtures not explosive by flame 
 within certain limits, these curious pheno- 
 mena took place, whether the air or the in- 
 flammable gas was in excess. The same 
 circumstances occurred with certain inflam- 
 mable vapours. Those of ether, alcohol, oil 
 of turpentine, naphtha, and camphor, have 
 been tried. There cannot be a better mode 
 of illustrating the fact, than by an experi- 
 ment on the vapour of ether or of alcohol, 
 which any person may make in a minute. 
 Let a drop of ether be thrown into a cold 
 glass, or a drop of alcohol into a w r arm one ; 
 let a few coils of wire of platinum, of the 
 l- 60 th or l- 70 th of an inch, he heated at a 
 hot poker or a candle, and let it be brought 
 into the glass : In some part of the glass, it 
 will become glowing, almost white-hot, and 
 will continue so, as long as a sufficient quan- 
 tity of vapour and of air, remain in the 
 glass. 
 
 When the experiment on the slow com- 
 bustion of ether is made in the dark, a pale 
 phosphorescent light is perceived above the 
 wire, w r hich is of course most distinct when 
 the wire ceases to be ignited. This appear- 
 ance is connected with the formation of a 
 peculiar acrid volatile substance, possessed of 
 acid properties. See Acid (Lamfic). The 
 above experiment has been ingeniously varied 
 by sticking loosely on the wick of a spirit- 
 lamp, a coil of fine platinum wire, about qLjy 
 of an inch in thickness. There should be 
 about 1 6 ' spiral turns, one-half of which should 
 surround the w ick, and the other rise above 
 it. Having lighted the lamp for an instant. 
 
COM 
 
 COM 
 
 on blowing it out, the wire will become 
 brightly ignited, and will continue to glow 
 as long as any alcohol remains. A cylinder 
 of camphor may be substituted for both wick 
 and spirit. The ignition is very bright, and 
 exhales an odoriferous vapour. With oil of 
 turpentine, the lamp burns invisibly without 
 igniting the wire ; for a dense column of va- 
 pour is perceived to ascend from the wire, 
 diffusing a smell by many thought agreeable. 
 By adding essential oils in small quantities 
 to the alcohol, various aromas may he made 
 to perfume the air of an apartment, lint 
 the film of charcoal which in this case col- 
 lects on the platina coil, must be removed by 
 ignition over another spirit flame, otherwise 
 the effect ceases after a certain time. 
 
 The chemical changes in general, produced 
 by slow combustion, appear worthy of inves- 
 tigation. A wire of platinum introduced 
 under the usual circumstances into a mixture 
 of prussic gas (cyanogen), and oxygen in 
 excess, became ignited to whiteness, and the 
 yellow vapours of nitrous acid were observed 
 in the mixture. In a mixture of olefiant 
 gas, non-explosive from the excess of inflam- 
 mable gas, much carbonic oxide was formed. 
 Platinum and palladium, metals of low con- 
 ducting powers, and small capacities for heat, 
 alone succeed in producing the above pheno- 
 mena. A film of carbon or sulphur deprives 
 even these metals of this property. Thin 
 laminae of the metals, if their form admits of 
 a free circulation of air, answer as well as 
 fine wires ; and a large surface of platinum 
 may be made red-hot in the vapour of ether, 
 or in a combustible mixture of coal gas and 
 
 ur. 
 
 Sir II. Davy made an admirable practical 
 application of these new facts. By hanging 
 some coils of fine platinum wire, or a fine 
 sheet of platinum or palladium, above the 
 wick of the safe-lamp in the wire-gauze cy- 
 linder, he has supplied the coal-miner with 
 light in mixtures of fire-damp no longer ex- 
 plosive. Should the flame be extinguished 
 by the quantity of fire-damp, the glow of the 
 platinum will continue to guide him ; and 
 by placing the lamp in different parts of the 
 gallery, the relative brightness of the wire 
 will show the state of the atmosphere in 
 these parts. Nor can there be any danger 
 with respect to respiration wherever the wire 
 continues ignited ; for even this phenomenon 
 ceases, when the foul air forms about y of 
 the volume of the atmosphere. 
 
 Into a wire-gauze safe-lamp, a small cage 
 made of fine wire of platinum, of l-70th ot 
 an inch in thickness, was introduced, and 
 fixed by means of a thick wire of platinum, 
 about 2 inches above the lighted wick. This 
 apparatus was placed in a large receiver, in 
 which, by means of a gas-holder, the air 
 could be contaminated to any extent with 
 coal gas. As soon as there was a slight ad- 
 
 mixture of coal gas, the platinum became 
 ignited. The ignition continued to increase 
 till the flame of the wick was extinguished, 
 and till the whole cylinder became filled with 
 flame. It then diminished. When the 
 quantity of coal gas was increased so as to 
 extinguish the flame, the cage of platinum, at 
 the moment of the extinction, became white 
 hot, presenting a most brilliant light. By 
 increasing the quantity of the coal gas still 
 further, the ignition of the platinum became 
 less vivid. When its light was barely sensi- 
 ble, small quantities of air were admitted, and 
 it speedily increased. By regulating the ad- 
 mission of coal gas and air, it again became 
 white-hot, and soon after lighted the flame 
 in the cylinder, which as usual, by the addi- 
 tion of more atmospheric air, rekindled the 
 flame of the wick. 
 
 This beautiful experiment has been very 
 often repeated, and always with the same 
 results. When the wire for the support of 
 the cage, whether of platinum, silver, or 
 copper, was very thick, it retained sufficient 
 heat, to enable the fine platinum wire to re- 
 kindle in a proper mixture, half a minute 
 after its light had been entirely destroyed, by 
 an atmosphere of pure coal gas. The phe- 
 nomenon of the ignition of the platinum, 
 takes place feebly in a mixture consisting of 
 two of air and one of coal gas ; and bril- 
 liantly in a mixture consisting of three of 
 air and one of coal gas. The greater 
 the quantity of heat produced, the greater 
 may be the quantity of the coal gas, so that 
 a large tissue of wire made white-hot, will 
 burn in a more inflammable mixture (that is, 
 containing more inflammable gas), than one 
 made red-hot. If a mixture of three parts 
 of air and one of fire-damp, he introduced 
 into a bottle, and inflamed at its point of 
 contact with the atmosphere, it will not ex- 
 plode, but will burn like a pure inflammable 
 substance. If a fine wire of platinum, coil- 
 ed at its end, be slowly passed through the 
 flame, it will continue ignited in the body of 
 the mixture, and the same gaseous matter 
 will be found to be inflammable , and to be a 
 supporter of combustion. When a large 
 cage of ware of platinum is introduced into a 
 very small safe-lamp, even explosive mix- 
 tures of fire-damp are burned without flame ; 
 and by placing any cage of platinum in the 
 bottom of the lamp round the wick, the w ire 
 is prevented from being smoked. Care 
 should be taken of course, that no filament 
 of the platinum protrude through the wire- 
 gauze. It is tridy wonderful, that a slender 
 tissue of platinum, which does not cost one 
 shilling, and which is imperishable, should 
 afford in the dark and dangerous recesses of 
 a coal mine, a most brilliant light , perfectly 
 safe, in atmospheres in which the flame of 
 the safety- lamp is extinguished ; and which 
 glows in every mixture of carburet ted by- 
 
COM 
 
 COM 
 
 drogen gas that is respirable. When the at- 
 mosphere becomes again explosive, th e flame 
 is re-lighted. 
 
 It is no less surprising, that thus also we 
 can burn any inflammable vapour, either 
 with or without flame, at pleasure, and make 
 a slender wire consume it, either with a 
 white or red heat. 
 
 6. We shall conclude the subject of com- 
 bustion with some practical inferences. 
 
 The facts detailed on insensible combustion, 
 explain why so much more heat is obtained 
 from fuel, when it is burned quickly than 
 slowly ; and they shevr, that in all cases the 
 temperature of the acting bodies should be 
 kept as high as possible, not only because 
 the general increment of heat is greater, but 
 likewise because those combinations are pre- 
 vented, which, at lower temperatures, take 
 place without any considerable production 
 of heat. Thus, in the argand lamp, and in 
 the best fire-places, the increase of effect does 
 not depend merely upon the rapid current of 
 air, but likewise upon the heat preserved by 
 the arrangement of the materials of the chim- 
 ney, and communicated to the matters enter- 
 ing into inflammation. 
 
 These facts likewise explain, the source of 
 the great error, into Which Mr Dalton has 
 fallen in estimating the heat given out in the 
 combustion of charcoal; and they indicate 
 methods by which temperature may be in- 
 creased, and the limits to certain methods. 
 Currents of flame can never raise the heat of 
 bodies exposed to them, higher than a certain 
 degree, that is, their own temperature. But 
 by compression, there can be no doubt, that 
 the heat of flames from pure supporters and 
 combustible matter may be greatly increased, 
 probably in the ratio of their compression. 
 In the blow-pipe of oxygen and hydrogen, 
 the maximum of temperature is close to the 
 aperture from which the gases are disengag- 
 ed, that is, where their density is greatest. 
 Probably a degree of temperature far beyond 
 any that has yet been attained, may be pro- 
 duced by throwing the flame from compres- 
 sed oxygen and hydrogen into the voltaic 
 arc, and thus combining the two most power- 
 ful agents for increasing temperature. 
 
 The nature of the light, and form, of flames, 
 can now he clearly understood. When in 
 flames pure gaseous matter is burnt, the light 
 is extremely feeble. The density of a com- 
 mon flame, is proportional to the quantity of 
 solid charcoal, first deposited and afterwards 
 burned. I he form of the flame is conical, 
 because the greatest heat is in the centre of 
 llic explosive mixture. In looking stead- 
 fastly at flame, the part where the combus- 
 tible matter is volatilized is seen, and it ap- 
 peals dark, contrasted with the part in which 
 it begins to burn; that is, where it is so 
 mixed with air as to become explosive. The 
 heat diminishes towards the top of the flame, 
 
 because in this part the quantity of oxygen 
 is least. When the wick increases to a con- 
 siderable size, from collecting charcoal, it 
 cools the flame by radiation, and prevents a 
 proper quantity of air from mixing with its 
 central part ; in consequence, the charcoal 
 thrown off from the top of the flame is only 
 red-hot, and the greater part of it escapes 
 unconsumcd. 
 
 Idle intensity of the light of flames in the 
 atmosphere is increased by condensation, and 
 diminished by rarefaction, apparently in v. 
 higher ratio than their heat : More particles 
 capable of emitting light exist in the denser 
 atmospheres, and yet most of these particles 
 in becoming capable of emitting light, ab- 
 sorb heat, which could not be the case in the 
 condensation of a pure supporting medium. 
 
 The facts on rarefaction of inflammable 
 gases shew, that the luminous appearances of 
 shooting stars and meteors, cannot be owing 
 to any inflammation of elastic fluids, but 
 must depend on the ignition of solid bodies. 
 Dr Ilalley calculated the height of a meteor 
 at ninety miles, and the great American 
 meteor which threw down showers of stones, 
 was estimated at seventeen miles high. The 
 velocity of motion of these bodies must in all 
 cases be immensely great, and the heat pro- 
 duced by the compression of the most rare- 
 fied air, from the velocity of motion, must 
 be probably sufficient to ignite the mass. 
 All the phenomena may be explained, if 
 falling stars be supposed to be small solid 
 bodies moving round the earth in very eccen- 
 tric orbits, which become ignited only when 
 they pass with immense velocity through the 
 upper regions of the atmosphere; and if the 
 meteoric bodies which throw down stones 
 with explosions, he supposed to be similar 
 bodies which contain either combustible or 
 elastic matter. 
 
 When the common electrical or voltaic elec- 
 trical spark is taken in rare air, the light is 
 considerably diminished, as well as the heat. 
 Yet, in a receiver that contained air 60 times 
 rarer than that of the atmosphere, a piece of 
 wire of platinum, placed by Sir H. Davy in 
 the centre oi the luminous arc, produced by 
 the great voltaic apparatus of the Royal In- 
 stitution, became white-hot; and that this 
 w'as not OAving to the electrical conducting 
 powers of the platinum, was proved by re- 
 peating the experiment with a filament of 
 glass, which instantly fused in the same 
 position. It is evident from this, that elec- 
 trical heat and light may appear in atmos- 
 pheres, in which the flame of combustible 
 bodies could not exist ; and the fact is in- 
 teresting from its possible application in ex- 
 plaining the phenomena of tiie Aurora Bo- 
 realis and Australis . 
 
 T mall i/, we may establish it as an axiovi y 
 that combustion is not the great phcjiomenon 
 ( lf chemical nature ; but an adventitious ac - 
 
CON 
 
 CON 
 
 cidental accessory to chemical combination , or 
 decomposition j that is, to the internal motions 
 of the particles of bodies , tending to arrange 
 them , in a new chemical constitution. 
 
 Several cases of death, from spontaneous 
 combustion of the body, are on record. 
 The appearances resemble those which 
 would be produced by phosphuretted hy- 
 drogen. * 
 
 Comptonite. A new mineral, found in 
 drusy cavities, in ejected masses, on Mount 
 Vesuvius. It occurs crystallized, in straight 
 four-sided prisms, which are usually truncat- 
 ed on their lateral edges, so as to form eight- 
 sided prisms, terminated with flat summits. 
 Transparent, or semi-transparent. Gelati- 
 nizes with acids. It is sometimes accom- 
 panied with acicular Arragonite. It was 
 first brought to this country by Lord Comp- 
 ton, in 1818. 
 
 * Concretions (Morrid). Solid deposited, 
 formed by disease in the soft parts, or in the 
 cavities of animal bodies. The former are 
 usually called ossifications, as they seem to 
 consist of calcareous phosphate. They are 
 named, according to the part in which they 
 are deposited, pineal, salivary, pulmonary, 
 pancreatic, hepatic, prostatic, gouty. Depo- 
 sites in cavities are generally styled calculi, 
 from their resemblance to pebbles. These are 
 intestinal, gall-stones or biliary, renal, and 
 urinary. See the respective articles .* 
 
 * Congelation. In addition to the me- 
 thods pointed out under Caloric, for effect- 
 ing artificial congelation, we shall here des- 
 cribe the elegant mode by the air-pump, re- 
 cently perfected by Professor Leslie. 
 
 The very ingenious Dr Cullen seems to 
 have been the first who applied the vacuum 
 of an air-pump to quicken the evaporation 
 of liquids, witli a view to the abstraction of 
 heat, or artificial congelation. In the year 
 1755, he plunged a full phial of ether into a 
 tumbler of w r ater, and on placing it under the 
 receiver, and exhausting the air, the ether 
 boiled, and the surrounding water froze. 
 
 In the year 1777, Mr Edward Nairne, a 
 very eminent London optician, published in 
 the Transactions of the Royal Society, “ an 
 account of some experiments made with an 
 air-pump.” After stating that at a certain 
 point of rarefaction, the moisture about the 
 pump furnished an atmosphere of vapour, 
 which affected his comparative results with 
 the mercurial gauge and pear gauge, he 
 says, “ I now put some sulphuric acid 
 into the receiver, as a means of trying to 
 make the remaining contents of the receiver, 
 when exhausted as much as possible, to con- 
 sist of permanent air only, unadulterated with 
 vapour .” lie was thus enabled by this arti- 
 ficial dryness to exhibit certain electrical 
 phenomena to great advantage. The next 
 step which Mr Nairne took, was to produce 
 artificial cold by the air-pump. “ Having 
 
 lately received from my friend Dr Lind,’* 
 he says, “ some ether prepared by the inge- 
 nious Mr Woolfe, I was very desirous to try 
 wdiether I could produce any considerable 
 degree of cold by the evaporation of ether 
 under a receiver whilst exhausting.” Ac- 
 cordingly he succeeded in sinking a thermo- 
 meter, whose bulb was from time to time 
 dipped into the ether in vacuo, 103° below 
 56°, the temperature of the apartment. Mr 
 Nairne made no attempt to condense the va- 
 pour in vacuo by chemical means, and thus 
 to favour its renewed formation from the li- 
 quid surface ; which I consider to be the es- 
 sence of Professor Leslie’s capital improve- 
 ment, on Cullen’s plan of artificial refrigera- 
 tion. After Nairne’s removing the vapour 
 of water by sulphuric acid to produce artifi- 
 cial dryness , there w r as indeed but a slight 
 step to the production of artificial cold, by 
 the very same arrangement ; but still this 
 step does not appear to have been attempted 
 by any person from the year 1777 to 1810, 
 when Professor Leslie was naturally led to 
 make it, by the train of his researches on 
 evaporation and hygrometry. 
 
 The extreme rapidity of evaporation in 
 vacuo, may be inferred from Dr Robison’s 
 position, that all liquids boil in it, at a tem- 
 perature 120° to 125° lower than their 
 usual boiling point in the atmosphere. Could 
 we find a liquid or solid substance which 
 w ould rapidly imbibe alcohol, ether, or sul- 
 phuret of carbon, we would probably be 
 able to effect reductions of temperature pro- 
 digiously greater than any hitherto reached. 
 Water, however, has no doubt one advan- 
 tage, in the superior latent heat of its vapour, 
 which must compensate in a considerable 
 degree for its inferior rapidity of vaporiza- 
 tion. 
 
 In the month of June 1810, Professor 
 Leslie having introduced a surface of sul- 
 phuric acid under the receiver of an air- 
 pump, and also a watch-glass filled with 
 water, he found that after a few strokes of 
 the pump, the water was converted into a 
 solid cake of ice, which being left in the 
 rarefied medium, continued to evaporate, and 
 after the interval of about an hour, totally 
 disappeared. When the air has been rare- 
 fied 250 times, the utmost that under such 
 circumstances can perhaps be effected, the 
 surface of evaporation is cooled down 1 20° 
 Fahrenheit in winter, and would probably, 
 from more copious evaporation and conden- 
 sation, sink near 200° in summer. If the 
 air be rarefied only 50 times, a depression of 
 80°, or even 100°, will be produced. 
 
 We are thus enabled by this elegant com- 
 bination, to freeze a mass of water in the 
 hottest weather, and to keep it frozen, till it 
 gradually wastes away, by a continued but 
 invisible process of evaporation. 1 he only 
 thing required is, that the surface of the acid 
 
CON 
 
 CON 
 
 should approach tolerably near to that of the 
 water, and should have a greater extent ; for 
 otherwise the moisture would exhale more 
 copiously than it could be transferred and 
 absorbed, and consequently the dryness of 
 the rarefied medium would become reduced, 
 and its evaporating energy essentially im- 
 paired. The acid should be poured to the 
 depth of perhaps half an inch, in a broad flat 
 dish, which is covered by a receiver of a form 
 nearly hemispherical ; the water exposed to 
 congelation may be contained in a shallow cup, 
 about half the width of the dish, and haying 
 its rim supported by a narrow porcelain ring, 
 upheld above the surface of the acid by three 
 slender feet. It is of consequence that the 
 water should he insulated as much as possi- 
 ble, or should present only a humid surface 
 to the contact of the surrounding medium ; 
 for the dry sides of the cup might receive, by 
 radiation from the external air, such acces- 
 sions of heat, as greatly to diminish, if not 
 to counteract the refrigerating effects of eva- 
 poration. This inconvenience is in a great 
 measure obviated, by investing the cup with 
 an outer case, at the interval of about half an 
 inch. If both the cup and its case consist of 
 glass, the process of congelation is viewed 
 most completely ; yet when they are formed 
 of a bright metal, the effect appears, on the 
 whole, more striking. But the preferable 
 mode, and that which prevents any waste of 
 the powers of refrigeration, is to expose the 
 water in a saucer of porous earthen ware. 
 At the instant of congelation, a beautiful 
 network of icy spiculae pervades the liquid 
 mass. 
 
 The disposition of the water to fill the re- 
 ceiver with vapour, will seldom permit even 
 a good air-pump to produce greater rarefac- 
 tion than that, indicated by 3-10ths of an 
 inch of mercury, beneath the barometrical 
 height, at the time. But every practical 
 object may be obtained by more moderate 
 rarefactions, and a considerable surface of 
 acid. The process goes on more slowly, 
 but the ice is very solid, especially if the wa- 
 ter have been previously purged of its air by 
 distillation, or boiling for a considerable 
 time. If we use a receiver, with a sliding 
 wire passing down from its top through a 
 collar of leathers, and attach to it a disc of 
 glass ; on applying this to the surface of 
 the water cup, we may instantly suspend the 
 pioccss of congelation; and raising the disc 
 as suddenly, permit the advancement of the 
 process. 
 
 In exhibiting the different modifications 
 of this system of congelation to my pupils, I 
 have been accustomed for many years to re- 
 commend the employment of a series of cast- 
 iron plates, attachable by screws and stop- 
 cocks to the air-pump. Each iron disc has 
 a receiver adapted to it. Thus, we may 
 with one air-pump, successively put any 
 
 number of freezing processes in action. A 
 cast-iron drum of considerable dimensions 
 being filled with steam, by heating a small 
 quantity of water in it, will sufficiently expel 
 the air for producing the requisite vacuum. 
 When it is cooled by affusion of water, one 
 of the above transferrer plates being attached 
 to the stop- cock on its upper surface, would 
 easily enable us, without any air-pump, to 
 effect congelation by means of sulphuric 
 acid, in the attenuated atmosphere. Suppose 
 the capacity of the receiver, to be l-60th of 
 the iron cylinder; an aeriform rarefaction to 
 this degree would be effected in a moment 
 by a turn of the stop- cock ; and on its be- 
 ing returned, the moisture below would be 
 cut off, and the acid would speedily condense 
 the small quantity of vapour which bad as- 
 cended. 
 
 This cheap and powerful plan was pub- 
 licly recommended by me upwards of ten 
 years ago, when I had a glass model of it 
 made for class illustration. 
 
 The combined powers of rarefaction, 
 vaporization, and absorption, are capable 
 of effecting the congelation of quicksil- 
 ver. If this metal, contained in a hollow 
 pear-shaped piece of ice, be suspended by 
 cross threads near a broad surface of sulphuric 
 acid, under a receiver; on urging the rare- 
 faction, it will become frozen, and may be 
 kept in the solid state for several hours. Or 
 otherwise, having introduced mercury into 
 the large bulb of a thermometer, and attached 
 the stem to the sliding rod of the receiver, 
 place this over the sulphuric acid, and water 
 cup on the air-pump plate. After the air has 
 been rarefied about 50 times, let the bulb be 
 dipped repeatedly into the very cold but un- 
 frozen water, and again drawn up about an 
 inch. In this way it will become incrusted 
 with successive coats of ice, to the twentieth 
 of an inch thick. The cup of water being 
 now withdrawn from the receiver, the pen- 
 dent icicle cut away from the bulb, and the 
 surface of the ice smoothed with a warm 
 finger, the receiver is again to be replaced, 
 and the bulb being let down within half an 
 inch of the acid, the .exhaustion must be 
 pushed to the utmost. When the syphon - 
 gauge arrives at the tenth of an inch, the icy 
 crust opens with fissures, and the mercury 
 having gradually descended in the tube, till 
 it reach its point of congelation, or 39° be- 
 low zero, sinks by a sudden contraction al- 
 most into the cavity of the bulb. The ap- 
 paratus being now removed, and the ball 
 speedily broken, the metal appears a solid 
 shining mass, that will bear the stroke of a 
 hammer. A still greater degree of cold may 
 be produced, by applying the same process to 
 cool the atmosphere, which surrounds the 
 receiver. 
 
 When the acid has acquired one- tenth of 
 water, its refrigerating power is diminished 
 
CON 
 
 COP 
 
 only one-hundredth. When the quantity of 
 moisture is equal to one- fourth of the con- 
 centrated acid, the power of generating cold 
 is reduced by a twentieth ; and when the di- 
 lution is one-hall, the cooling powers become 
 one-half or probably less. Sulphuric acid is 
 hence capable of effecting the congelation of 
 more than twenty times its weight of water, 
 before it has imbibed nearly its own bulk of 
 that liquid, or has lost about one-eighth of its 
 refrigerating power. The acid should then 
 be removed and re- concentrated by heat. 
 
 The danger of using a corrosive acid in 
 unskilful hands, may be obviated by using 
 oatmeal, desiccated nearly to brownness be- 
 fore a kitchen- fire, and allowed to cool in 
 close vessels. With a body of this, a foot in 
 diameter, and an inch deep, Professor Leslie 
 froze a pound and a quarter of water, con- 
 tained in a hemispherical porous cup. Mu- 
 riate of lime in ignited porous pieces, may 
 also be employed as an absorbent. Even 
 mouldering trap or whinstoue, has been used 
 for experimental illustration with success. 
 
 By the joint operation of radiation and 
 evaporation from the surface of water, the 
 natives of India are enabled to procure a 
 supply of ice, when the temperature of the 
 air is many degrees above the freezing point. 
 Not far from Calcutta, in large open plains, 
 three or four excavations are made in the 
 ground, about 50 feet square, and 2 feet 
 deep, the bottom of which is covered to the 
 thickness of nearly a foot with sugar canes, 
 or dried stalks of Indian coru. On this bed 
 are placed rows of small unglazed earthen 
 pans, about an inch and a quarter deep, and 
 somewhat porous. In the dusk of the even- 
 ing* during the months of December, January, 
 and February, they are filled with soft water, 
 previously boiled and suffered to cool. When 
 the weather is very fine and clear, a great 
 part of the water becomes frozen during the 
 night. The pans are regularly visited at 
 sunrise, and their contents emptied into bas- 
 kets which retain the ice. These are now 
 carried to a conservatory made by sinking a 
 pit 14 or 15 feet deep, lined with straw un- 
 der a layer of coarse blanketing. The small 
 sheets of ice are thrown down into the cavity, 
 and rammed into a solid mass. I he mouth 
 of the pit is then closed up with straw and 
 blankets, and sheltered by a thatched roof. 
 
 For some additional facts, on this interest- 
 ing subject, see the sequel ot the article Dew. * 
 
 * Conite. An ash or greenish-grey colour- 
 ed mineral, which becomes brown on ex- 
 posure to the air. It is massive or stalactitic, 
 is dull internally, and has a small grained 
 uneven fracture. It is brittle ; sp. gr. 2.85. 
 It dissolves in nitric acid, with slight efferves- 
 cence, and blackens without fusing before 
 the blow-pipe. Its constituents are 61 .5 car- 
 bonate of magnesia, 28 carbonate ot lime, 
 
 3.5 oxide of iron, and 1 water. It is found 
 in the Meissner trap hill in Hessia, in Sax- 
 ony, and Iceland. Dr Macculloch has given 
 the name Conite to a purverulent mineral, as 
 fusible as glass, into a transparent bead, 
 which he found in Mull and Glenfarg, in 
 the trap hills of Kilpatrick, and the Isle of 
 Sky.* 
 
 Copal, improperly called gum copal, is a 
 hard, shining, transparent, citron-coloured, 
 odoriferous, concrete juice of an American 
 tree, but which has neither the solubility in 
 water common to gums, nor the solubility 
 in alcohol common to resins, at least in any 
 considerable degree. By these properties it 
 resembles amber. It may be dissolved by 
 digestion in linseed oil, rendered drying by 
 quicklime, with a heat very little less than 
 sufficient to boil or decompose the oil. This 
 solution, diluted with oil of turpentine, forms 
 a beautiful transparent varnish, which, when 
 properly applied, and slowly dried, is very 
 hard, and very durable. This varnish is ap- 
 plied to snuff-boxes, tea-boards, and other 
 utensils. It preserves and gives lustre to 
 paintings, and greatly restores the decayed 
 colours of old pictures, by filling up the 
 cracks, and rendering the surfaces capable 
 of reflecting light more uniformly. 
 
 Mr Sheldrake has found, that camphor has 
 a powerful action on copal ; for if powdered 
 copal be triturated with a little camphor, it 
 softens, and becomes a coherent mass; and 
 camphor added cither to alcohol or oil of 
 turpentine, renders it a solvent of copal. 
 Half an ounce of camphor is sufficient for a 
 quart of oil of turpentine, which should be 
 of the best quality ; and the copal, about the 
 quantity of a large walnut, should be broken 
 into very small pieces, but not reduced to a 
 fine powder. The mixture should be set on 
 a fire so brisk as to make the mixture boil 
 almost immediately; and the vessel Mr S. 
 recommends to be of tin or other metal, 
 strong, shaped like a wine-bottle with a long 
 neck, and capable of holding two quarts. 
 The mouth should be stopped with a cork, 
 in which a notch is cut to prevent the vessel 
 from bursting. It is probably owing to the 
 quantity of camphor it contains, that oil of 
 lavender is a solvent of copal. Camphor and 
 alcohol dissolve copal still more readily than 
 camphor and oil of turpentine. 
 
 Lewis had observed, that solution of am- 
 monia enabled oil of turpentine to dissolve 
 copal ; but it requires such nice management 
 of the fire that it seldom succeeds completely. 
 
 * In the 51st volume of Tilloch’s Ma- 
 gazine, Mr Cornelius ^ arley states, that 
 a good varnish may be made by pouring up- 
 on the purest lumps of copal, reduced to a 
 fine mass, in a mortar, colourless spirits of 
 turpentine, to about one-third higher tii.m 
 the copal, and triturating the mixture ocea- 
 
COP 
 
 COP 
 
 sionally in the course of the day. Next 
 morning it may be poured off into a bottle 
 for use. Successive portions of oil of tur- 
 pentine may thus be worked with the same 
 copal mass. Camphorated oil of turpentine, 
 and oil of spike- lavender, are also recom- 
 mended as separate solvents without tritura- 
 tion. The latter, however, though very good 
 for drawings or prints, will not do for var- 
 nishing pictures, as it dissolves the paint un- 
 derneath, and runs down while drying.* 
 
 Copper is a metal of a peculiar reddish- 
 brown colour ; hard, sonorous, very mallea- 
 ble and ductile ; of considerable tenacity, 
 and of a specific gravity from 8.6 to 8.9. 
 At a degree of heat far below ignition, the 
 surface of a piece of polished copper becomes 
 covered with various ranges of prismatic co- 
 lours, the red of each order being nearest 
 the end which has been most heated ; an 
 effect which must doubtless be attributed to 
 oxidation, the stratum of oxide being thick- 
 est where the heat is greatest, and growing 
 gradually thinner and thinner towards the 
 colder part. A greater degree of heat oxi- 
 dizes it more rapidly, go that it contracts 
 thin powdery scales on its surface, which 
 may be easily rubbed off; the fame of the 
 fuel becoming at the same time of a beauti- 
 ful bluish-green colour. In a heat, nearly 
 the same as is necessary to melt gold or sil- 
 ver, it melts, and exhibits a bluish-green 
 flame ; by a violent heat it boils, and is vola- 
 tilized partly in the metallic state. 
 
 Copper rusts in the air ; but the corroded 
 part is very thin, and preserves the metal 
 beneath from farther corrosion. 
 
 * We have two oxides of copper, the 
 black, procurable by heat, or by drying 
 the hydrated oxide, precipitated by potash 
 from the nitrate. Jt consists of 8 copper 
 + 2 oxygen. It is a deutoxide. The 
 protoxide is obtained by digesting a so- 
 lution ot muriate of copper with copper 
 turnings, in a close phial. The colour 
 passes Irom green to dark brown, and grey 
 crystalline grains are deposited. The solu- 
 tion ol these yields, by potash, a precipitate 
 of an orange colour, which is the protoxide. 
 It consists ot 8 copper -J- 1 oxygen. Prot- 
 oxide of copper has been lately found by Mr 
 Mushet, in a mass of copper, which had 
 been exposed to heat for a considerable time, 
 in one of the melting furnaces of the mint 
 under his superintendence. 
 
 Copper, in filings, or thin laminae, intro- 
 duced into chlorine, unites with flame into 
 the chloiide, of which there are two varie- 
 ties ; the protochloride, a fixed yellow sub- 
 stance, and the deutochloride, a yellowish- 
 brown pulverulent sublimate. 1. The crys- 
 tal I iiie grains deposited from the above mu- 
 riatic solution, are protochloride. The pro- 
 tochloride is conveniently made by heating 
 together two parts of corrosive sublimate^ 
 
 and one of copper filings. An amber- 
 coloured translucent substance, first discover- 
 ed by Hoyle, who called it resin of copper, 
 is obtained. It is fusible at a heat just be- 
 low redness ; and in a close vessel, or a ves- 
 sel with a narrow orifice, is not decomposed 
 or sublimed by a strong red-heat. Put if 
 air be admitted, it is dissipated in dense 
 white fumes. It is insoluble in water. It 
 effervesces in nitric acid. It dissolves silent- 
 ly in muriatic acid, from which it may be 
 precipitated by water. Py slow cooling of 
 the fused mass Dr John Davy obtained it 
 crystallized, apparently in small plates, semi- 
 transparent, and of a light yellow colour. 
 It consists, by the same ingenious chemist, of 
 
 Chlorine, 36 
 
 or 1 prime 
 
 = 4.45 
 
 55.8 
 
 Copper, 64 
 
 or 1 prime 
 
 8.00 
 
 64.2 
 
 100 
 
 
 12.45 
 
 100.0 
 
 2. Deutochloride is best made by slowly 
 evaporating to dryness, at a temperature not 
 much above 400° Fahr. the deliquescent 
 muriate of copper. It is a yellow powder. 
 Py absorption of moisture from the air, it 
 passes from yellow to white, and then green, 
 reproducing common muriate. Heat con- 
 verts it into protochloride, with the disen- 
 gagement of chlorine. Dr Davy ascertained 
 the chemical constitution of both these com- 
 pounds, by separating the copper with iron, 
 and the chlorine by nitrate of silver. The 
 deutochloride consists of 
 
 Chlorine, 55 2 primes 8.9 52.7 
 
 Copper, 47 1 do. 8.0 47.3 
 
 100 16.9 100.0 
 The iodide of copper is formed by drop- 
 ping aqueous hydriodate of potash into a so- 
 lution of any cupreous salt. It is an inso- 
 luble dark brown powder. 
 
 Phosphuret of‘ copper is made by project- 
 ing phosphorus into red-hot copper. It is 
 of a white colour, harder than iron, pretty 
 fusible, but not ductile. Its sp. gr. is 7.12. 
 It crystallizes in four-sided prisms. Proust, 
 its discoverer, says it consists of 20 phos- 
 phorus -|- 80 copper. 1.5 or 5.0 phospho- 
 rus + 8.0 copper, form the equivalent pro- 
 portions by theory. Ileat burns k out the 
 phosphorus, and scorifies the copper. 
 
 Sulphuret of copper is formed by mixing 
 together eight parts of copper filings, and 
 two of sulphur, and exposing the mixture to 
 a gentle heat. Whenever the sulphur is 
 raised a little above its melting temperature, 
 combustion suddenly pervades the whole 
 mass with explosive violence. 
 
 Ignition, with reciprocal saturation, con- 
 stitutes a true combustion, of which every 
 character is here. And since the experi- 
 ment succeeds perfectly well in vacuo , or in 
 azote, we are entitled to consider sulphur as 
 a true supporter of combustion, if this name 
 be retained in chemistry 5 a name indicat- 
 
COP 
 
 COP 
 
 ing, what no person can prove, that one of 
 the combining bodies is a mere supporter, 
 and the other a mere combustible. Com- 
 bustion is, on the contrary, shewn by this 
 beautiful experiment, to be independent of 
 those bodies vulgarly reckoned supporters. 
 Indeed, sulphur bears to copper the same 
 electrical relation, that oxygen and chlorine 
 bear to this metal. Hence sulphur is at 
 once a supporter and a combustible, in the 
 fullest sense ; a fact fatal to this technical 
 distinction, since one body cannot be possess- 
 ed of diametrically opposite qualities. 
 
 When a disc of copper, with an insulated 
 handle, is made to touch a disc of sulphur, 
 powerful electrical changes ensue ; and at a 
 higher temperature we see, that the recipro- 
 cal attractive forces, or the corpuscular 
 movements which accompany energetic affi- 
 nity, excite the phenomena of combustion. 
 To say that one of the combining bodies 
 contains a latent magazine of heat and light, 
 to feed the flame of the other body, is an 
 hypothesis altogether destitute of proof, 
 which should therefore have no place in one 
 of the exact sciences, far less be made the 
 groundwork of a chemical system. 
 
 Sulphuret of copper consists, according 
 to Berzelius, of very nearly 8 copper -}- 2 
 sulphur. We may regard it as containing 
 a prime of each constituent.* 
 
 The sulphuric acid, when concentrated 
 and boiling, dissolves copper. If water be 
 added to this, it forms a blue solution of 
 copper, which, by evaporation, affords blue 
 crystals, that require about four times their 
 weight of water to dissolve them. 
 
 The solutions of copper in sulphuric acid 
 are slightly caustic. Magnesia, lime, and 
 the fixed alkalis, precipitate the metal from 
 them in the form of oxide. ^ olatile alkali 
 precipitates all the solution of copper, but 
 redissolves the oxide, and produces a deep 
 blue colour. There are certain mineral 
 waters in Hungary, Sweden, Ireland, and in 
 various parts of England, which contain 
 sulphate of copper, and from which it is 
 precipitated by the addition of pieces of old 
 iron. 
 
 Nitric acid dissolves copper with great 
 rapidity, and disengages a large quantity of 
 nitrous gas. Bart ol the metal tails down 
 in the form of an oxide ; and the filtrated or 
 decanted solution, which is of a much deeper 
 blue colour than the sulphuric solution, af- 
 fords crystals by slow evaporation. ibis 
 salt is deliquescent, very soluble in water, 
 but most plentifully when the fluid is heat- 
 ed. Its solution, exposed to the air in shal- 
 low vessels, deposits an oxide ot a green 
 colour. Lime precipitates the metal ot a 
 pale blue, fixed alkalis of a bluish- white. 
 Volatile alkali throws down bluish flocks, 
 which are quickly redissolved, and produce 
 a lively blue colour in the fluid. 
 
 * The saline combinations of copper were 
 formerly called sales veneris , because Venus 
 was the mythological name of copper. They 
 have the following general characters : 1. 
 
 They are mostly soluble in water, and their 
 solutions have a green or blue colour, or ac- 
 quire one of these colours on exposure to 
 air. 2. Ammonia added to the solutions, 
 produces a deep blue colour. 3. Ferroprus- 
 siate of potash gives a reddish-brown preci- 
 pitate, with cupreous salts. 4. Gallic acid 
 gives a brown precipitate. 5. Hydrosul- 
 phuret of potash gives a black precipitate. 
 6. A plate of iron immersed in these solu- 
 tions throws down metallic copper, and very 
 rapidly if there be a slight excess of acid. 
 The protoxide of copper can be combined 
 with the acids only by very particular ma- 
 nagement. All the ordinary salts of copper 
 have the peroxide for a base. 
 
 Acetate of' copper. The joint agency of 
 air and acetic acid, is necessary to the pro- 
 duction of the cupreous acetates. By ex- 
 posing copper plates to the vapours of vine- 
 gar, the bluish-green verdigris is formed, 
 which by solution in vinegar constitutes ace- 
 tate of copper. This salt crystallizes in four- 
 sided truncated pyramids. Its colour is a fine 
 bluish-green. Its sp. gr. is 1.78. It has 
 an austere metallic taste ; and swallowed, 
 proves a violent poison. Boiling water dis- 
 solves one-fifth of the salt, of which it depo- 
 sits the greater part on cooling. It is solu- 
 ble also in alcohol. It effloresces by expo- 
 sure to air. By heat, in a retort, it yields 
 acetic acid, and pyro- acetic spirit. Sulphu- 
 retted hydrogen throws down the copper 
 from solutions of this salt, in the state of 
 sulphuret. Dr Thomson gives the follow- 
 ing account of its composition : “ Accord- 
 ing to Proust, the acetate of copper is 
 composed of 6 1 acid and water, 
 
 39 oxide, 
 
 100 
 
 “ If we suppose it a compound of 1 atom 
 acid, 1 atom oxide, and 8 atoms water, its 
 constituents will be 
 
 Acetic acid, 25.12 
 
 Peroxide of copper, 59.41 
 Water, 55.47 
 
 1 00.00 
 
 “ I consider these to be its true constitu- 
 ents.” Here we have an amusing specimen 
 of atomical reasoning; beginning the syllo- 
 gism with a supposition, and concluding it 
 with a certainty. 1 had occasion to ana- 
 lyze this salt with some care about two 
 years ago, and found it to consist by expe- 
 riment of 
 
 Exper. Theory. 
 
 Acetic acid, 52.0 2 atoms 13.26 51.98 
 
 Perox. of cop. 59.6 1 do. 10.00 59.-0 
 
 Water, S.4 1 do. 2.25 8.82 
 
 2 *.51 100.00 
 
 100.0 
 
COP 
 
 COP 
 
 Instead of 35\ per cent of water, which 
 the Doctor pitches on at random, it has not 
 9 ; and instead of only 25 of acid, it really 
 contains more than double that quantity. 
 The crystallized salt is a binacetate of copper. 
 
 The subacetate of Proust, obtained by dis- 
 solving verdigris in water, is said to consist 
 of acid and water, 37 
 Oxide, 63. 
 
 The proportion of 40 acid -j- 60 oxide, 
 is that of 1 atom of each, to use the hy- 
 pothetical term. Now Proust’s experiments 
 seem to leave uncertainty to the amount of 
 that difference. This salt should be called 
 probably the acetate. Proust’s insoluble 
 part of verdigris will become the subacetate. 
 This constitutes 44 per cent, and the other 
 56. But the proportions will fluctuate ; and 
 an intermixture of carbonate may be expect- 
 ed occasionally. 
 
 Arseniate of copper presents us with many 
 sub-species which are found native. The 
 arseniate may be formed artificially by di- 
 gesting arsenic acid on copper, or by adding 
 arseniate of potash to a cupreous saline solu- 
 tion. 
 
 1. Obtuse octohedral arseniate, consisting 
 of two four-sided pyramids, applied base to 
 base, of a deep sky-blue or grass-green colour. 
 Their sp. gr. is 2.88. They consist, accord- 
 ing to Chenevix, of 14.3 acid -J- 50 brown 
 oxide -j- 35.7 water. 2. Hexahcdrnl arse- 
 niate is found in fine six-sided laminae, di- 
 visible into thin scales. Its colour is a deep 
 emerald-green ; and its sp. gr. 2.548. It 
 consists, by Vauquelin, of 43 acid -j- 59 
 oxide — 1 8 water. When arseniate of am- 
 monia is poured into nitrate of copper, this 
 variety precipitates in small blue crystals. 
 5. Acute octohedral arseniate , composed of 
 two four-sided pyramids, applied base to 
 base, and sometimes in rhomboidal prisms, 
 with dehedral summits. It consists of 29 
 acid -(- 50 oxide •-(- 21 water. The last in- 
 gredient is sometimes wanting. 4. Trihe- 
 dral arseniate occurs also in other forms. 
 Colour bluish-green. It consists, by Che- 
 nevix, of 50 acid + 54 oxide 16 
 water. 5. Super arseniate. On evaporating 
 the supernatant solution in the second va- 
 riety artificially made, and adding alcohol, 
 M. Chenevix obtained a precipitate in small 
 blue rhomboidal crystals. They were com- 
 posed of 40.1 acid -j- 55.5 oxide 24.4 
 water. The following is a general table of 
 the composition of these arseniates: — 
 
 1 . 
 
 Acid. 
 
 1.00 
 
 Oxide. 
 
 3.70 
 
 Water. 
 
 2.50 
 
 2. 
 
 1.00 
 
 2.76 
 
 1.00 
 
 5. 
 
 1.00 
 
 1.72 
 
 0.70 
 
 4. 
 
 J.00 
 
 1.80 
 
 0.53 
 
 5. 
 
 It will 
 
 1.00 
 
 0.88 
 
 0.60 
 
 require the atomical 
 
 couch of Pro 
 
 crustes, to accommodate these proportions to 
 
 the number 14.5, recently pitched upon for 
 arsenic acid by Dr Thomson. 
 
 Arsenite of copper, called Scheele’s green, 
 is prepared by the old prescription of mixing 
 a solution of 2 parts of sulphate of copper in 
 44 of water, with a solution of 2 parts of 
 potash of commerce, and l of pulverized ar- 
 senious acid, also in 44 of water. Both so- 
 lutions being warm, the first is to be gradu- 
 ally poured into the second. The grass- 
 green insoluble precipitate is to be well 
 washed with water. 
 
 Carbonate of copper. Of this compound 
 there are three native varieties, the green, 
 the blue, and the anhydrous. According to 
 Mr R. Phillips, the following is the order of 
 their composition : — 
 
 
 1st. 
 
 £d. 
 
 3d. 
 
 Carbonic acid, 
 
 2.75 
 
 11.00 
 
 2.75 
 
 Deutox. copper, 
 
 10.00 
 
 30.00 
 
 10.00 
 
 W ater, 
 
 1.125 
 
 2. 25 
 
 0.00 
 
 Weights of primes, 
 
 13.875 
 
 45.25 
 
 12.75 
 
 The artificial carbonate, obtained by 
 Proust, on adding an alkaline carbonate to a 
 solution of the nitrate of copper, is the same 
 with the second kind. 
 
 Chlorate of copper is a deflagrating deli- 
 quescent green salt. 
 
 Fluate of copper is in small blue-coloured 
 crystals. 
 
 Hydriodate of copper is a greyish- white 
 powder. 
 
 Protomuriate of copper has already been 
 described in treating of the chlorides. 
 
 Deuto muriate, of copper, formed by dissolv- 
 ing the deutoxide in muriatic acid, or by 
 heating muriatic acid on copper filings, yields 
 by evaporation crystals of a grass-green co- 
 lour, in the form of rectangular parallele- 
 pipeds. Their sp. gr. is 1.68. They are 
 caustic, very deliquescent, and of course very 
 soluble in water. According to Berzelius, 
 it consists of acid, 40.2 
 Deutoxide, 59.8 
 
 100.0 
 
 The ammonia-nitrate evaporated, yields a 
 fulminating copper. Crystals of nitrate, 
 mixed with phosphorus, and struck with a 
 hammer, detonate. When pulverized, then 
 slightly moistened, and suddenly wrapt up 
 firm, in tin-foil, the nitrate produces an ex- 
 plosive combustion. The nitrate seems to 
 consist of a prime of acid a prime of dcu- 
 toxide, besides water of crystallization. 
 
 Subnitrate of copper is the blue precipi- 
 tate, occasioned by adding a little potash to 
 the neutral nitric solution. 
 
 Nitrite of copper is formed by mixing 
 nitrite of lead with sulphate of copper. 
 
 'The sulphate or blue vitriol of commerce 
 is a bisulphate. Its sp. gr. is 2.2. It con- 
 sists of 
 
COP 
 
 COP 
 
 Acid, 
 
 31.58 
 
 2 
 
 primes, 
 
 10.0 
 
 32.0 
 
 Oxide, 
 
 32.32 
 
 l 
 
 do. 
 
 10.0 
 
 52.0 
 
 Water, 
 
 56.30 
 
 10 
 
 do. 
 
 1 1.25 
 
 56.0 
 
 
 100.00 
 
 
 
 51.25 
 
 100.0 
 
 A mixed solution, of this sulphate and sal 
 ammoniac, forms an ink, whose traces are 
 invisible in the cold, but become yellow 
 when heated ; and vanish again as the paper 
 cools. 
 
 A neutral sulphate of copper may be form- 
 ed by saturating the excess of acid with oxide 
 of copper. It crystallizes in four-sided py- 
 ramids, separated by quadrangular prisms. 
 
 M. Proust formed a subsulphate by add- 
 ing a little pure potash to a solution of the 
 last salt. A green-coloured precipitate falls. 
 
 Protosulphite of copper is formed by pass- 
 ing a current of sulphurous acid gas through 
 the deutoxide of copper diffused in water. It 
 is deprived of a part of its oxygen, and com- 
 bines with the acid. The sulphate, simulta- 
 neously produced, dissolves in the water; 
 while the sulphite forms small red crystals, 
 from which merely long ebullition in water 
 expels the acid. 
 
 Sulphite of potash and copper is made by 
 adding the sulphite of potash to nitrate of 
 copper. A yellow fl occulent precipitate, 
 consisting of minute crystals, falls. 
 
 Ammonia- sulphate of copper is the salt 
 formed by adding water of ammonia to so- 
 lution of the bisulphate. It consists, accord- 
 ing to Berzelius, of 1 prime of the cupreous, 
 and 1 of the ammoniacal sulphate, combined 
 together; or 20.0 -{- 7.13 A- 14 .625 of 
 water. 
 
 Subsulphate of ammonia and copper is 
 formed bv adding alcohol to the solution of 
 the preceding salt, which precipitates the 
 subsulphate. It is the cuprum ammoniacum 
 of the pharmacopoeia. According to Berze- 
 lius, it consists of 
 
 Acid, 52.25 or nearly 2 primes, 
 
 Dcutox. of copper, 54.00 1 do. 
 
 Ammonia, 26.40 4 do. 
 
 Water, 7.55 2 do. 
 
 100.00 
 
 Sulphate of potash and copper is formed 
 by digesting bisulphate of potash on the 
 deutoxide or carbonate of copper. Its crys- 
 tals are greenish-coloured, flat parallelopipe- 
 dons. It seems to consist of 2 primes of sul- 
 phate of potash -|- 1 prime of bisulphate of 
 copper + 1 2 of water. 
 
 The following acids, antimonic, antimo- 
 nious, boracic, chromic, molybdic, phosphoric, 
 tungstic, form insoluble salts with deutoxide 
 of copper. The first two >n*e green, the 
 third is brown, the fourth and filth green, 
 and the sixth white. The benzoate is in 
 green crystals, sparingly soluble. 'I he oxa- 
 late is also green. The binoxalates of potash 
 and soda, with oxide of copper, give triple 
 
 salts, in green needle-form crystals. There 
 are also ammonia- oxalates in different varie- 
 ties. 1 artrate of copper forms dark bluish- 
 green crystals. Cream- tartrate of copper is 
 a bluish- green powder, commonly called 
 Brunswick green. 
 
 To obtain pure copper for experiment*, 
 we precipitate it in the metallic state, by 
 immersing a plate of iron in a solution of 
 the deutomuriate. The pulverulent copper 
 must be washed with dilute muriatic acid.* 
 
 In the wet way Brunswick or Friezland 
 green is prepared by pouring a saturated so- 
 lution of muriate of ammonia over copper 
 filings or shreds in a close vessel, keeping 
 the mixture in a warm place, and adding 
 more of the solution from time to time, till 
 three parts of muriate and two of copper 
 have been used. After standing a few weeks, 
 the pigment is to be separated from the un- 
 oxidized copper, by washing through a sieve; 
 and then it is to be well washed, and dried 
 slowly in the shade. This green is almost 
 always adulterated with ceruse. 
 
 This metal combines very readily with 
 gold, silver, and mercury. It unites imper- 
 fectly with iron in the way of fusion. Tin 
 combines with copper, at a temperature much 
 lower than is necessary to fuse the copper 
 alone. On this is grounded the method of 
 tinning copper vessels. For this purpose, 
 they are first scraped or scoured ; after which 
 they are rubbed with sal ammoniac. They 
 are then heated, and sprinkled with powder- 
 ed resin, which defends the clean surface of 
 the copper from acquiring the slight film of 
 oxide, that would prevent the adhesion of the 
 tin to its surface. The melted tin is then 
 poured in, and spread about. An extremely 
 small quantity adheres to the copper, which 
 may perhaps be supposed insufficient to pre- 
 vent the noxious effects of the copper, as per- 
 fectly as might be wished. 
 
 When tin is melted w ith copper, it com- 
 poses the compound called bronze. In this 
 metal the specific gravity is always greater 
 than w'ould be deduced by computation from 
 the quantities and specific gravities of its 
 component parts. The uses ot this hard, 
 sonorous, and durable composition, in the 
 fabrication of cannon, bells, statues, and 
 other articles, arc well known. Bronzes and 
 bell-metals are not usually made of copper 
 and tin only, but have other admixtures, con- 
 sisting of lead, zinc, or arsenic, according to 
 the motives of profit, or other inducements 
 of (he artist. But the attention of the philo- 
 sopher is more particularly directed to the 
 mixture of copper and tin, on account of its 
 being the substance of which the speculums 
 of reflecting telescopes are made. See Spe- 
 culum. The ancients made cutting instru- 
 ments of this alloy. A dagger analyzed by 
 Mr Hielm consisted of copper, and 16| 
 tin. 
 
COP 
 
 COP 
 
 Copper unites with bismuth, and forms a 
 reddish- white alloy. With arsenic it forms a 
 white brittle compound, called tombac. W ith 
 zinc it forms the compound called brass, and 
 distinguished by various other names, accord- 
 ing to the proportions of the two ingredients. 
 It is not easy to unite these two metals in 
 considerable proportions by fusion, because the 
 zinc is burnt or volatilized at a heat inferior 
 to that which is required to melt copper ; but 
 they unite very well in the way of cementa- 
 tion. In the brass works, copper is granu- 
 lated by pouring it through a plate of iron, 
 perforated with small holes and luted with 
 clay, into a quantity of water about four feet 
 deep, and continually renewed : to prevent 
 the dangerous explosions of this metal, it is 
 necessary to pour but a small quantity at a 
 time. There are various methods of com- 
 bining this granulated copper, or other small 
 pieces of copper, with the vapour ot zinc. 
 Calamine, which is an ore of zinc, is pound- 
 ed, calcined, and mixed with the divided 
 copper, together with a portion of charcoal. 
 These being exposed to the heat of a wind 
 furnace, the zinc becomes revived, rises in 
 vapour, and combines with the copper, which 
 it converts into brass. The heat must be 
 continued for a greater or less number of 
 hours, according to the thickness of the pieces 
 of copper, and other circumstances ; and at 
 tho end of the process, the heat being sud- 
 denly raised, causes the brass to melt, and 
 occupy the lower part of the crucible. The 
 most scientific method of making brass seems 
 to be that mentioned by Cramer. The pow- 
 dered calamine, being mixed with an equal 
 quantity of charcoal and a portion of clay, is 
 to be rammed into a melting vessel, and a 
 quantity of copper, amounting to two-thirds 
 of the weight of calamine, must be placed 
 on the top, and covered with charcoal. By 
 this management the volatile zinc ascends, 
 and converts the copper into brass, which 
 flows into the rammed clay ; consequently, 
 if the calamine contain lead, or any other 
 metal, it will not enter into brass, the zinc 
 alone being raised by the heat. 
 
 A fine kind of brass, which is supposed 
 to be made by cementation of copper plates 
 with calamine, is hammered out into leaves 
 in Germany ; and is sold very cheap in this 
 country, under the name of Dutch gold, or 
 Dutch metal. It is about five times as thick 
 as gold leaf ; that is to say, it is about one 
 sixty-thousandth of an inch thick. 
 
 Copper unites readily with antimony, and 
 affords a compound of a beautiful violet co- 
 lour. It does not readily unite with man- 
 ganese. With tungsten it forms a dark 
 brown spongy alloy, which is somewhat 
 ductile. See Ores of Copper. 
 
 * Verdegris, and other preparations of 
 copper, act as virulent poisons, when intro- 
 duced in very small quantities into the sto- 
 
 machs of animals. A few grains are suf- 
 ficient for this effect. Death is common- 
 ly preceded by very decided nervous dis- 
 orders, such as convulsive movements, teta- 
 nus, general insensibility, or a palsy of the 
 lower extremities. This event happens fre- 
 quently so soon, that it could not be occa- 
 sioned by inflammation or erosion of tho 
 primes vies ; and indeed, where these parts 
 are apparently sound. It is probable that 
 the poison is absorbed, and through the cir- 
 culation, acts on the brain and nerves. The 
 cupreous preparations are no doubt very 
 acrid, and if death do not follow their im- 
 mediate impression on the sentient system, 
 they will certainly inflame the intestinal 
 canal. The symptoms produced by a dan- 
 gerous dose of copper are exactly similar to 
 those which are enumerated under arsenic, 
 only the taste of copper is strongly felt. 
 The only chemical antidote to cupreous so- 
 lutions whose operation is well understood, 
 is water strongly impregnated with sulphu- 
 retted hydrogen. The alkaline hydrosul- 
 phurets are acrid, and ought not to be pre- 
 scribed. 
 
 But we possess in sugar, an antidote to 
 this poison of undoubted efficacy, though its 
 mode of action be obscure. M. Duval in- 
 troduced into the stomach of a dog, by 
 means of a caoutchouc tube, a solution in 
 acetic acid, of four French drachms of oxide 
 of copper. Some minutes afterwards he in- 
 jected into it four ounces of strong syrup. 
 Fie repeated this injection every half-hour, 
 and employed altogether 12 ounces of syrup. 
 The animal experienced some tremblings 
 and convulsive movements. But the last 
 injection was followed by a perfect calm. 
 The animal fell asleep, and awakened free 
 from any ailment. 
 
 Orfila relates several cases of individuals 
 who had by accident or intention swallowed 
 poisonous doses of acetate of copper, and 
 who recovered by getting large doses of 
 sugar. He uniformly found, that a dose of 
 verdigris which would kill a dog in the 
 course of an hour or two, might be swallow- 
 ed with impunity, provided it was mixed 
 with a considerable quantity of sugar. 
 
 As alcohol has the power of completely 
 neutralizing, in the ethers, the strongest mu- 
 riatic and hydriodic acids, so it would ap- 
 pear, that sugar can neutralize the oxides of 
 copper and lead. The neutral saccharate of 
 lead, indeed, was employed by Berzelius in 
 his experiments, to determine the prime equi- 
 valent of sugar. If we boil for half an hour, 
 in a flask, an ounce of white sugar, an ounce 
 of water, and 10 grains of verdigris, we ob- 
 tain a green liquid, which is not affected by 
 the nicest tests of copper, such as ferroprus- 
 siate of potash, ammonia, and the hydrosul- 
 phurets. An insoluble green carbonate of 
 copper remains at the bottom of the flask** 
 
CRI 
 
 CRU 
 
 CorprRAs. Sulphate of iron. 
 
 * Corals seem to consist of carbonate of 
 lime and animal matter, in equal propor- 
 tions.* 
 
 Cork is the bark of a tree of the oak kind, 
 very common in Spain and the other south- 
 ern parts of Europe. 
 
 By the action of the nitric acid it was 
 found to be acidified. See Acid (Suberic). 
 
 * Cork has been recently analyzed by 
 Chevreul by digestion, first in water and then 
 in alcohol. By distillation there came over 
 an aromatic principle, and a little acetic 
 acid. The watery extract contained a yel- 
 low and a red colouring matter, an undeter- 
 mined acid, gallic acid, an astringent sub- 
 stance, a substance containing azote, a sub- 
 stance soluble in water and insoluble in al- 
 cohol, gallate of iron, lime, and traces of 
 magnesia. 20 parts of cork treated in this 
 way, left 17.15 of insoluble matter. The 
 undissolved residue being treated a sufficient 
 number of times with alcohol, yielded a va- 
 riety of bodies, but which seem reducible to 
 three ; namely, cerin, resin, and an oil. The 
 ligneous portion of the cork still weighed 14 
 parts, which are called suber.* 
 
 Cork (Fossil). See Asbestos. 
 
 Corrosive Sublimate. See Mercury. 
 
 * Corundum. According to Professor 
 Jameson, this mineral genus contains 3 spe- 
 cies, viz. octohedral corundum, rhomboidal 
 corundum, and prismatic corundum. 
 
 1. Octohedral , is subdivided into S sub- 
 species, viz. automalite, ceylanite, and spinel. 
 
 2. Rhomboidal corundum, contains 4 sub- 
 species, viz. salamstone, sapphire, emery, and 
 corundum, or adamantine spar. 
 
 3. Prismatic , or chrysoberyl. See the se- 
 veral sub-species, under their titles in the 
 Dictionary.* 
 
 * Cotton’. This vegetable fibre is solu- 
 ble in strong alkaline leys. It has a strong 
 affinity for some earths, particularly alumina, 
 several metallic oxides, and tannin. Nitric 
 acid, aided by heat, converts cotton into ox- 
 alic acid.* 
 
 * Couch. The heap of moist barley about 
 16 inches deep on the malt- floor.* 
 
 * Cream. The oily part of milk, which 
 rises to the surface of that liquid, mixed with 
 a little curd and serum. When churned, 
 butter is obtained. Ileat separates the oily 
 part, but injures its flavour.* 
 
 Cream of Tartar. See Acid (Tar- 
 taric). 
 
 * Crichtonite. A mineral so called in 
 honour of Dr Crichton, physician to the 
 Emperor of Russia, an eminent mineralo- 
 gist. It has a velvet-black colour, and crys- 
 tallizes in very acute small rhomboids. 
 Imstre splendent, inclining to metallic ; frac- 
 ture conchoidal ; opaque ; scratches fluor spar, 
 but not glass. Infusible before the blow- 
 pipe. It occurs in primitive rocks along 
 
 with octahedrite. Professor Jameson thinks I 
 it may probably be a new species of titanium- 
 ore.* 
 
 Crocus. The yellow or saffron-coloured 
 oxides of iron and copper were formerly 
 called crocus martis and crocus veneris. 
 That of iron is still called crocus simply, by ! 
 the workers in metal who use it. 
 
 * Cross- stone. Ilarmotome, or pyramidal I 
 zeolite. Its colour is greyish- white, passing 
 into smoke-grey, sometimes massive, but 
 usually crystallized. Primitive form, a double 
 four-sided pyramid, of 121° 58' and 86° 36'. 
 Its principal secondary forms are, a broad 
 rectangular four-sided prism, rather acutely 
 acuminated on the extremities with 4 planes, 
 which are set on the lateral edges ; the pre- 
 ceding figure, in which the edges formed by 
 the meeting of the acuminating planes, that 
 rest on the broader lateral planes, are trun- 
 cated ; twin crystals of the first form, inter- 
 secting each other, in such a manner that a 
 common axis and acumination is formed, and 
 the broader lateral planes make four re-en- 
 tering angles. The crystals are not large. 
 The surface of the smaller lateral planes is 
 double-plumosely streaked. Lustre glisten- 
 ing, between vitreous and pearly. Of the 
 cleavage, 2 folia are oblique, and 1 parallel 
 to the axis. Fracture perfect conchoidal. 
 Translucent and semi-transparent. Harder 
 than fluor spar, but not so hard as apatite. 
 Easily frangible. Sp. gr. 2.35. It fuses 
 with intumescence and phosphorescence, into 
 a colourless glass. Its constituents are 49 
 silica, 16 alumina, 18 barytes, and 15 water, 
 by Klaproth. It has hitherto been found 
 only in mineral veins and agate-balls. It 
 occurs at Andreasberg in the Plartz, at 
 Kongsberg in Norway, at Oberstein, Stron- 
 tian in Argyllshire, and also near Old Kil- 
 patrick in Scotland. Jameson.* 
 
 * Croton Eleutheria. Cascarilla bark. 
 The following; is Trommsdorf’s analysis of 
 this substance, characterized by its emitting 
 the smell of musk when burned. Mucilage 
 and bitter principle 864 parts, resin 688, 
 volatile matter 72, water 48, woody fibres 
 3024; in 4696 parts.* 
 
 * Crusts, the bony coverings of crabs, 
 lobsters, &c. Mr Hatchett found them to 
 be composed of a cartilaginous substance, 
 like coagulated albumen, carbonate of lime, 
 and phosphate of lime. The great excess of 
 the second, above the third ingredient, dis- 
 tinguishes them from bones; while the quan- 
 tity of the third, distinguishes them from 
 shells. Egg-shells and snail-shells belong 
 to crusts in composition ; blit the animal 
 matter is in smaller quantity. By Merat- 
 Guillot, 100 parts of lobster crust, consist of 
 60 carbonate of lime, 14 phosphate of lime, 
 and 26 cartilaginous matter. 1 00 of hen’s 
 egg-shells, consist of 89.6 carbonate of lime, 
 5,7 phosphate of lime, 4.7 animal matter.* 
 
CRY 
 
 CRY 
 
 * Cryolite. A mineral which occuis 
 massive, disseminated, and in thick lamellar 
 concretions. Its colours are white and yel- 
 lowish-brown. Lustre vitreous, inclining to 
 pearly. Cleavage fourfold, in which the 
 folia are parallel with an equiangular four- 
 sided pyramid. Fracture uneven. Frans- 
 lucent. Harder than gypsum. Easily fran- 
 gible. Sp. gr. 2.95. It becomes more 
 translucent in w’ater. It melts in the heat 
 of a candle. Before the blow-pipe, it be- 
 comes first very liquid, and then assumes a 
 slaggy appearance. It consists, by Klaproth, 
 of 24 alumina, 36 soda, and 40 fluoric acid 
 and water. It is therefore a soda-fluate of 
 alumina. If w r e regard it as composed ot 
 definite proportions, we may have 
 
 1 
 
 prime alumina, 
 
 3.2 
 
 26.33 
 
 1 
 
 do. 
 
 soda, 
 
 3.95 
 
 32.51 
 
 2 
 
 do. 
 
 acid, 
 
 2.75 
 
 22.63 > 4L1G 
 
 2 
 
 do. 
 
 water, 
 
 2.25 
 
 18.a3 3 
 
 12.15 100.00 
 
 Yauquelin’s analysis of the same mineral 
 gives 47 acid and water, 32 soda, and 21 
 alumina. This curious and rare mineral 
 has hitherto been found only in West Green- 
 land, at the arm of the sea named Arksut, 
 SO leagues from the colony of Juliana Hope. 
 It occurs in gneiss. Mr Allan of Edin- 
 burgh had the merit of recognizing a large 
 quantity of this mineral, in a neglected heap 
 brought into Leith, from a captured Danish 
 vessel. It had been collected in Green- 
 land by that indefatigable mineralogist M. 
 Gieseke. * 
 
 * Cryophorus. The frost-bearer or car- 
 rier of cold, an elegant instrument invented 
 by Dr Wollaston, to demonstrate the rela- 
 tion between evaporation at low tempera- 
 tures, and the production of cold. If 32 
 grains of water, says this profound philoso- 
 pher, were taken at the temperature of 62°, 
 and if one grain of this were converted into 
 vapour by absorbing 960°, then the whole 
 
 960° 
 
 quantity would lose — — = 30°, and thus 
 
 be reduced to the temperature of 32°. If 
 from the 31 grains which still remain in the 
 
 state of water, four grains more were con- 
 verted into vapour by absorbing 960°, then 
 the remaining 27 grains must have lost 
 of 960° = 1 42°, which is rather more than 
 sufficient to convert the whole into ice. In 
 an experiment conducted upon a small scale, 
 the proportional quantity evaporated did not 
 differ much from this estimate. 
 
 If it be also true that water, in assuming 
 the gaseous state, even at a low temperature, 
 expands to 1800 times its former bulk, then 
 in attempting to freeze the small quantity of 
 water above mentioned, it would be requisite 
 to have a dry vacuum with the capacity of 
 5 X 1800= 9000 grains of water. But 
 let a glass tube be taken, having its internal 
 
 o 
 
 diameter about of an inch, with a ball at 
 each extremity of about one inch diameter, 
 and let the tube be bent to a right angle at 
 the distance of half an inch from each ball. 
 One of these balls should be somewhat less 
 than half full of water, and the remaining 
 cavity should be as perfect a vacuum as 
 can readily be obtained ; which is effected 
 by making the water boil briskly in the one 
 ball, before sealing up the capillary opening 
 left in the other. If the empty ball be im- 
 mersed in a freezing mixture of snow and 
 salt, the wafer in the other ball, though at 
 the distance of two or three feet, will be 
 frozen solid in the course of a very few mi- 
 nutes. The vapour contained in the empty 
 ball is condensed by the common operation 
 of cold, and the vacuum produced by this 
 condensation gives opportunity for a fresh 
 quantity to arise from the opposite ball, with 
 proportional reduction of its temperature.* 
 
 * Crystal. When fluid substances are 
 suffered to pass with adequate slowmess to 
 the solid state, the attractive forces frequent- 
 ly arrange their ultimate particles, so as to 
 form regular polyhedral figures, or geome- 
 trical solids, to w r hich the name of crystals 
 has been given. Most of the solids which 
 compose the mineral crust of the earth, are 
 found in the crystallized state. Thus granite 
 consists of crystals of quartz, felspar, and 
 mica. Even mountain masses like clay-slate, 
 have a regular tabulated form. Perfect 
 mobility among the corpuscles is essential to 
 crystallization. The chemist produces it either 
 by igneous fusion, or by solution in a liquid. 
 When the temperature is slow ly low-ered in 
 the former case, or the liquid slowly abstract- 
 ed by evaporation in the latter, the attractive 
 forces resume the ascendancy, and arrange 
 the particles in symmetrical forms. Mere ap- 
 proximation of the particles, however, is not 
 alone sufficient for crystallization. A hot 
 saturated saline solution, when screened from 
 all agitation, will contract by cooling into a 
 volume much smaller, than what it occupies 
 in the solid state, without crystallizing. Hence 
 the molecules must not onlv be brought with- 
 in a certain limit of each other, for their con- 
 creting into crystals ; but they must also 
 change the direction of their poles, from the 
 fluid collocation, to their position in the solid 
 state. 
 
 This reversion of the poles may be effect- 
 ed, 1st, By contact of any part of the fluid, 
 with a point of a solid, of similar composition 
 previously formed. 2d, Vibratory motions, 
 communicated either from the atmosphere, 
 or any other moving body, by deranging, 
 however slightly, the fluid polar direction, 
 will instantly determine the solid polar ar- 
 rangement, when the balance had been ren- 
 dered nearly even, by previous removal of 
 the interstitial fluid. On this principle we 
 explain the regular figures which particles of 
 
CRY 
 
 CRY 
 
 dust or iron assume, when they arc placed on 
 a vibrating plane, in the neighbourhood of 
 electrized or magnetized bodies. 3d, Nega- 
 tive or resinous voltaic electricity instantly 
 determines the crystalline arrangement, while 
 positive voltaic electricity counteracts it. On 
 this subject, I beg to refer the reader to an 
 experimental paper, which I published in the 
 fourth volume of the Journal of Science, 
 p. 106. Light also favours crystallization, as 
 is exemplified with camphor dissolved in 
 spirits, which crystallizes in bright, and re- 
 dissolves in gloomy weather. 
 
 It might be imagined, that the same body 
 would always concrete in the same, or at 
 least in a similar crystalline form. This 
 position is true, in general, for the salts 
 crystallized in the laboratory ; and on this 
 uniformity of figure, one of the principal 
 criteria between different salts depends. 
 But even these forms are liable to many 
 modifications, from causes apparently slight; 
 and in nature, we find frequently the same 
 chemical substance, crystallized in forms 
 apparently very dissimilar. Thus, carbo- 
 nate of lime assumes the form of a rhom- 
 boid, of a regular hexahedral prism, of 
 a solid terminated by 12 scalene angles, or 
 of a dodecahedron with pentagonal faces, 
 Sec . Bisulphuret of iron or martial pyrites 
 produces sometimes cubes and sometimes 
 regular octohedrons, at one time dodecahe- 
 drons with pentagonal faces, at another ico- 
 sahedrons with triangular faces, Sec. 
 
 While one and the same substance lends 
 itself to so many transformations, we meet 
 with very different substances, which present 
 absolutely the same form. Thus fluate of 
 lime, muriate of soda, sulphuret of iron, sul- 
 pliuret of lead, &c. crystallize in cubes, un- 
 der certain circumstances ; and in other 
 cases, the same minerals, as well as sulphate 
 of alumina and the diamond, assume the 
 form of a regular octohedron. 
 
 Rome de l’lsle first referred the study of 
 crystallization, to principles conformable to 
 observation. He arranged together, as far 
 as possible, crystals of the same nature. 
 Among the different forms relative to each 
 species, he chose one as the most proper, 
 from its simplicity, to be regarded as the 
 primitive form ; and by supposing it trun- 
 cated in different ways, lie deduced the other 
 forms from it, and determined a gradation, 
 a series of transitions between this same 
 form, and that of polyhedrons, which seemed 
 to be still further removed from it. To the 
 descriptions and figures which he gave of 
 the crystalline forms, he added the results of 
 the mechanical measurement of their princi- 
 pal angles, and showed, that these angles 
 were constant in each variety. 
 
 The illustrious Bergman, by endeavour- 
 ing to penetrate to the mechanism ot the 
 
 structure of crystals, considered the different 
 forms relative to one and the same substance, 
 as produced by a superposition of planes, 
 sometimes constant and sometimes variable, 
 and decreasing around one and the same 
 primitive form. He applied this primary 
 idea to a small number of crystalline forms, 
 and verified it with respect to a variety of 
 calcareous sparf by fractures, which enabled 
 him to ascertain the position of the nucleus, 
 or of the primitive form, and the successive 
 order of the laminae covering this nucleus. 
 Bergman, however, stopped here, and did 
 not trouble himself either with determining 
 the laws of structure, or applying calculation 
 to it. It was a simple sketch, of the most 
 prominent point of view in mineralogy, but 
 in which we see the hand of the same master 
 who so successfully filled up the outlines of 
 chemistry. 
 
 In the researches which M. Ilaiiy under- 
 took, about the same period, on the structure 
 of crystals, he proposed combining the form 
 and dimensions of integrant molecules with 
 simple and regular laws of arrangement, and 
 submitting these laws to calculation. This 
 work produced a mathematical theory, which 
 he reduced to analytical formulae, represent- 
 ing everyr possible case, and the application 
 of which to known forms leads to valuations 
 of angles, constantly agreeing with observa- 
 tion. 
 
 Theory of the structure of Crystals. 
 
 Primitive forms. — The idea of referring 
 to one of the same primitive forms, all the 
 forms which may be assumed by a mineral 
 substance, of which the rest may be regarded 
 as being modifications only, has frequently 
 suggested itself to various philosophers, who 
 have made crystallography their study. 
 
 The mechanical division of minerals, which 
 is the only method of ascertaining their true 
 primitive form, proves that this form is in- 
 variable while we operate upon the same sub- 
 stance, however diversified or dissimilar the 
 forms of the crystals belonging to this sub- 
 stance may be. Two or three examples will 
 serve to place this truth in its proper light. 
 
 Take a regular hexahedral prism of car- 
 bonate of lime (PI. XIII. figs. 1 and 2). 
 If we try to divide it parallel to the edges, 
 from the contours of the bases, we shall find, 
 that three of these edges taken alternately in 
 the upper part, for instance, the edges I f c 
 d, b m, may be referred to this division : 
 and in order to succeed in the same way 
 with respect to the inferior base, we must 
 choose, not the edges l' f, c d\ b m, which 
 correspond with the preceding, but the inter- 
 mediate edges d'f't b' c\ l' m. 
 
 f This is what has been called deni dc cochon y but 
 which M. Haiiy calls metastatic. 
 
CRY 
 
 CRY 
 
 The six sections will uncover an equal 
 number of trapeziums. 1'hree of the latter 
 are represented upon fig. 2. viz. the two 
 which intercept the edges l f c d, and are 
 designated by p p o o, a a k k, and that which 
 intercepts the lower edge d' fj and which is 
 marked by the letters n n i i . 
 
 Each of these trapeziums will have a 
 lustre and polish, from which we may easily 
 ascertain, that it coincides with one of the 
 natural joints of which the prism is the as- 
 semblage. We shall attempt in vain to di- 
 vide the prism in any other direction. But 
 if we continue the division parallel to the 
 first sections, it will happen that on one 
 hand the surfaces of the bases Will always 
 become narrower, while on the other hand, 
 the altitudes of the lateral planes will de- 
 crease ; and at the term at which the bases 
 have disappeared, the prism will be changed 
 into a dodecahedron (fig. 3.), with penta- 
 gonal faces, six of which, such as o o i O e, 
 o I k i i , &c. will be the residues of the planes 
 of the prism ; and the six others E A I o o, 
 O A' K i i, &c. will be the immediate result 
 of the mechanical division. 
 
 Beyqnd this same term, the extreme faces 
 will preserve their figure and dimensions, 
 while the lateral faces will incessantly dimi- 
 nish in height, until the points o, k, of the 
 pentagon o I k i i, coming to be confound- 
 ed with the points i, i, and so on with the 
 other points similarly situated, each pentagon 
 will be reduced to a simple triangle, as we 
 see in fig. 4. f 
 
 Lastly, when new sections have obliterat- 
 ed these triangles, so that no vestige of the 
 surface of the prism remains (fig. 1.), we 
 shall have the nucleus or the primitive form, 
 which will be an obtuse rhomboid (fig. 5.), 
 the grand angle of which E A I or E O I, 
 is 101° 32' 18". J 
 
 If we try to divide a crystal of another 
 species, we shall have a different nucleus. 
 For instance, a cube of fluate of lime will 
 give a regular octahedron, which we succeed 
 in extracting by dividing the cube upon its 
 eight solid angles, which will in the first 
 place discover eight equilateral triangles, and 
 we may pursue the division, always paral- 
 lel to the first sections, until nothing more 
 remains of the faces of the cube. The nu- 
 cleus of the crystals of sulphate of barytes 
 will be a straight prism with rhombous 
 bases; that of the crystals of phosphate of 
 
 f The points which are confounded, two and two, 
 upon this figure, are each marked with the two let- 
 ters which served to designate them when they were 
 separated, as in fig. 3. 
 
 t It is observed, that each trapezium, such as 
 ppoo (fig. 2.) uncovered by the first sections, is 
 very sensibly inclined from the same quantity, as well 
 upon the residue p p d e b m of the base, as upon the 
 residua oo/' /' of the adjacent plane. Setting out from 
 this equality of inclinations, we deduce from it, by cal- 
 culation, the value of the angles with the precision of 
 minutes and seconds, which mechanical measure- 
 ments arc not capable of attaining. 
 
 2 
 
 lime, a regular hexahedral prism ; that of 
 sulphuretted lead, a cube, &c.; and each of 
 these forms will be constant relative to the 
 entire species, in such a manner, that its 
 angles will not undergo any appreciable 
 variation. 
 
 Having adopted the word primitive form 
 in order to designate the nucleus of crystals, 
 M. Haiiy calls secondary forms , such varie- 
 ties as differ from the primitive form. 
 
 In certain species, crystallization also pro- 
 duces this last form immediately. 
 
 We may define the primitive form, a solid 
 of a constant form, engaged symmetrically 
 in all the crystals of one and the same 
 species, and the faces of which follow the 
 directions of the laminae which form these 
 crystals. 
 
 The primitive forms hitherto observed, 
 are reduced to six, viz. the parallelopipedon, 
 the octohedron, the tetrahedron, the regular 
 hexahedral prism, the dodecahedron with 
 rhombous planes, all equal and similar, and 
 the dodecahedron with triangular planes, 
 composed of two straight pyramids joined 
 base to base. 
 
 Forms of integrant Molecules. — The nu- 
 cleus of a crystal is not the last term of its 
 mechanical division. It may always be sub- 
 divided parallel to its different faces, and 
 sometimes in other directions also. The 
 whole of the surrounding substance is capa- 
 ble of being divided by strokes parallel to 
 those which take place with respect to the 
 primitive form. 
 
 If the nucleus be a parallelopipedon, which 
 cannot be subdivided except by blows paral- 
 lel to its faces, like that which takes place 
 with respect to carbonated lime, it is evident 
 that the integrant molecule will be similar 
 to this nucleus itself. 
 
 But it may happen that the parallelopipe- 
 don admits of further sections in other di- 
 rections than the former. 
 
 We may reduce the forms of the integrant 
 molecules of all crystals to three, which are, 
 the tetrahedron, or the simplest of the pyra- 
 mids ; the triangular prism, or the simplest 
 of all the prisms ; and the parallelopipedon, 
 or the simplest among the solids, which 
 have their faces parallel two and two. And 
 since four planes at least are necessary for 
 circumscribing a space, it is evident that the 
 three forms in question, in which the num- 
 ber of faces is successively four, five, and 
 six, have still, in this respect, the greatest 
 possible simplicity. 
 
 La ws to which the Structure is subjected. 
 — After having determined the primitive 
 forms, and those of the integrant molecules, 
 it remains to inquire into the laws pursued 
 by these molecules in their arrangement, in 
 order to produce these regular kinds of en- 
 velopes, which disguise one and the same 
 primitive form in so many different ways. 
 
 A 
 
 I 
 
CRY 
 
 CRY 
 
 Now, observation shows, that this sur- 
 rounding matter is an assemblage of lamina?, 
 which, setting out from the primitive form, 
 decrease in extent, both on all sides at once, 
 and sometimes in certain particular parts 
 only. This decrement is effected by regular 
 subtractions of one or more rows of integrant 
 molecules; and the theory, in determining 
 the number of these rows by means of cal- 
 culation, succeeds in representing all the 
 known results of crystallization, and even 
 anticipates future discoveries, indicating 
 forms which, being still hypothetical only, 
 may one day be presented to the inquiries 
 of the philosopher. 
 
 Decrements on the Edges . — Let 5 s' (fig. 6. 
 PI. XIII.) be a dodecahedron with rhombic 
 planes. This solid, which is one of the six 
 primitive forms of crystals, also presents it- 
 self occasionally as a secondary form, and in 
 this case it has as a nucleus, sometimes a 
 cube and sometimes an octohedron. Sup- 
 posing the nucleus to be a cube : — 
 
 In order to extract this nucleus, it is suffi- 
 cient successively to remove the six solid 
 angles composed of four planes, such as s, r, 
 t, Sec. by sections adapted to the direction of 
 the small diagonals. These sections will 
 display as many squares A E O I, E O O' 
 E', I O O' I' (fig. 7.), Sec. which will be the 
 faces of the cube. 
 
 Let us conceive that each of these faces is 
 subjected to a series of decreasing laminae 
 solely composed of cubic molecules, and that 
 every one of these laminae exceeds the suc- 
 ceeding one, towards its four edges, by a 
 quantity equal to one course of these same 
 molecules. Afterwards we shall designate 
 the decreasing laminae which envelope the 
 nucleus, by the name of lamince of superpo- 
 sition. Now, it is easy to conceive that the 
 different series will produce six quadrangu- 
 lar pyramids, similar in some respects to the 
 quadrangular steps of a column, which will 
 rest on the faces of the cube. Three of these 
 pyramids are represented in fig. 8. and have 
 their summits in s, t , r . 
 
 Now, as there are six quadrangular pyra- 
 mids, we shall therefore have twenty- four 
 triangles, such as O s I, O t I, Sec. But 
 because the decrement is uniform from s to 
 t y and so on with the rest; the triangles 
 taken two and two are on a level, and form 
 a rhomb s O t I. The surface of the solid 
 will therefore be composed of twelve equal 
 and similar rhombs, i. e. this solid will have 
 the same form with that which is the sub- 
 ject of the problem. This structure takes 
 place, although imperfectly, with respect to 
 the crystals called boracic spars. 
 
 The dodecahedron now under considera- 
 tion, is represented by fig. 8. in such a way 
 that the progress of the decrement may be 
 perceived by the eye. On examining the 
 figure attentively, we shall find that it has 
 
 been traced on the supposition, that the 
 cubic nucleus has on each of its edges 1 7 
 ridges of molecules; whence it follows, that 
 each of its faces is composed of 289 facets 
 of molecules, and that the whole solid is 
 equal to 4913 molecules. On this hypothe- 
 sis, there are eight laminae of superposition, 
 the last of which is reduced to a simple 
 cube, whose edges determine the numbers of 
 molecules which form the series 15, 13, 11, 
 9, 7, 5, 3, 1, the difference being 2, because 
 there is one course subtracted from each ex- 
 tremity. 
 
 Now, if instead of this coarse kind of 
 masonry, which has the advantage of speak- 
 ing to the eye, we substitute in our imagi- 
 nation the infinitely delicate architecture of 
 nature, we must conceive the nucleus as 
 being composed of an incomparably greater 
 number of imperceptible cubes. In this 
 case, the number of lamina? of superposition 
 will also be beyond comparison greater than 
 on the preceding hypothesis. By a neces- 
 sary consequence, the furrows which form 
 these lamince by the alternate projecting and 
 re-entering of their edges, will not be cog- 
 nizable by our senses ; and this is what 
 takes place in the polyhedra which crystal- 
 lization has produced at leisure, without be- 
 ing disturbed in its progress. 
 
 M. Haiiy calls decrements in breadth f 
 those in which each lamina has only the 
 height of a molecule ; so that their whole 
 effect, by one, two, three, &c. courses, is in 
 the way of breadth. Decrements in height 
 are those in which each lamina, exceeding 
 only the following one by a single course in 
 the direction of the breadth, may have a 
 height double, triple, quadruple, &c. to that 
 of a molecule : this is expressed by saying 
 that the decrement takes place by two 
 courses, three courses, &c. in height. 
 
 We are indebted to Dr Wollaston for 
 ideas on the ultimate cause of crystalline 
 forms, equally ingenious and profound. 
 They were communicated to the Royal So- 
 ciety, and published in their transactions for 
 the year 1813. 
 
 Among the known forms of crystallized 
 bodies, there is no one common to a greater 
 number of substances than the regular octo- 
 hedron, and no one in which a corresponding 
 difficulty has occurred with regard to deter- 
 mining which modification of its form is to 
 be considered as primitive; since in all these 
 substances the tetrahedron appears to have 
 equal claim to be received as the original 
 from which all their other modifications are 
 to be derived. 
 
 The relation of these solids to each other 
 is most distinctly exhibited to those who are 
 not much conversant with crystallography, 
 by assuming the tetrahedron as primitive, 
 for this may immediately be converted into 
 an octohedron by the removal of four smaller 
 
CIIY 
 
 CRY 
 
 1 
 
 I 
 
 li 
 
 ■ li 
 
 , 8 
 
 i\\ 
 
 p! ! 
 
 rc | 
 
 i; 
 
 ‘."l 
 
 i 
 
 in 
 
 tetrahedrons from its solid angles. (Plate 
 
 xiv.fig.i.) . 
 
 The substance which most readily admits 
 of division by fracture into these forms, is 
 fiuor spar; and there is no difficulty in ob- 
 taining a sufficient quantity for such experi- 
 ments. But it is not, in fact, either the 
 tetrahedron or the octohedron, which first 
 presents itself as the apparent primitive form 
 obtained by fracture. 
 
 If we forma plate of uniform thickness 
 by two successive divisions of the spar, pa- 
 rallel to each other, we shall find the plate 
 divisible into prismatic rods, the section of 
 which is a rhomb of 70° 52' and 109° 28 
 nearly; and if we again split these rods trans- 
 versely, we shall obtain a number of regular 
 acute rhomboids, all similar to each other, 
 having their superficial angles 60° and 120°, 
 and presenting an appearance of primitive 
 molecule, from which all the other modifica- 
 tions of such crystals might very simply be 
 derived. And we find, moreover, that the 
 whole mass of fiuor might be divided into, 
 and conceived to consist of, these acute 
 rhomboids alone, which may be put together 
 so as to fit each other without any interven- 
 ing vacuity. 
 
 But, since the solid thus obtained (as re- 
 presented fig. 2.) may be again split by na- 
 tural fractures at right angles to its axis (fig. 
 5.), so that a regular tetrahedron may be 
 detached from each extremity, while the re- 
 maining portion assumes the form of a re- 
 gular octohedron ; and since every rhomboid 
 that can be obtained, must admit of the same 
 division into one octohedron and two tetrahe- 
 drons, the rhomboid can no longer be re- 
 garded as the primitive form ; and since the 
 parts into which it is divisible are dissimilar, 
 we are left in doubt which of them is to have 
 precedence as primitive. 
 
 In the examination of this question, 
 whether we adopt the octohedron or the 
 tetrahedron as the primitive form, since 
 neither of them can fill space without leav- 
 ing vacuities, there is a difficulty in conceiv- 
 ing any arrangement in which the particles 
 will remain at rest : for, whether we suppose, 
 with the Abbe Haiiy, that the particles are 
 tetrahedral with octohedral cavities, or, on 
 the contrary, octohedral particles regularly 
 arranged with tetrahedral cavities, in each 
 case the mutual contact of adjacent particles 
 is only at their edges; and, although in such 
 an arrangement it must be admitted that 
 there may be an equilibrium, it is evidently 
 unstable, and ill adapted to form the basis 
 of any permanent crystal. 
 
 With respect to fiuor spar and such other 
 substances as assume the octohedral and 
 tetrahedral forms, all difficulty is removed, 
 says l)r Wollaston, by supposing the elemen- 
 tary particles to be perfect spheres, which, 
 by mutual attraction, have assumed that ar- 
 
 rangement which brings them as near to each 
 other as possible. 
 
 The relative position of any number of 
 equal balls in the same plane, when gently 
 pressed together, forming equilateral triangles 
 with each other (as represented perspectively 
 in fig. 4.), is familiar to every one ; and it is 
 evident that, if balls so placed were cemented 
 together, and the stratum thus formed were 
 afterwards broken, the straight lines in which 
 they would be disposed to separate would 
 form angles of 60° with each other. 
 
 If a single ball were placed any where at 
 rest upon the preceding stratum, it is evident 
 that it would be in contact wfith three of the 
 lower balls (as in fig. 5.), and that the lines 
 joining the centres of four balls so in contact, 
 or the planes touching their surfaces, w r ould 
 include a regular tetrahedron, having all its 
 equilateral triangles. 
 
 The construction of an octohedron, by 
 means of spheres alone, is as simple as that 
 of the tetrahedron. For, if four balls bo 
 placed in contact on the same plane, in form 
 of a square, then a single ball resting upon 
 them in the centre, being in contact with 
 each pair of balls, will present a triangular 
 face rising from each side of the square, and 
 the whole together will represent the superior 
 apex of an octohedron ; so that a sixth ball 
 similarly placed underneath the square will 
 complete the octohedral group, fig. 6 . 
 
 There is one observation with regard to 
 these forms that will appear paradoxical, 
 namely, that a structure, which, in this case, 
 w^as begun upon a square foundation, is really 
 intrinsically the same as that which is begun 
 upon the triangular basis. But if we lay 
 the octohedral group, which consists of six 
 balls, on one of its triangular sides, and, con- 
 sequently, with an opposite triangular face 
 uppermost, the tw r o groups, consisting of 
 three balls each, are then situated precisely 
 as they w r ould be found in two adjacent strata 
 of the triangular arrangement. Hence, in 
 this position, we may readily convert the oc- 
 tohedron into a regular tetrahedron, by ad- 
 dition of four more balls (fig. 7.). One 
 placed on the top of the three that are upper- 
 most forms the apex ; and if the triangular 
 base, on which it rests, be enlarged by ad- 
 dition of three more balls, regularly disposed 
 around it, the entire group of ten balls will 
 then be found to represent a regular tetra- 
 hedron. 
 
 For the purpose of representing the acute 
 rhomboid, tw>o balls must be applied at op- 
 posite sides of the smallest octohedral group, 
 as in fig. 9. And if a greater number of 
 balls be placed together, fig. 10. and 11. in 
 the same form, then a complete tetrahedral 
 group may be removed from each extremity, 
 leaving a central octohedron, as may be seen 
 in fig. 1 1. which corresponds to fig. 3. 
 
 Wo have seen, that by due application of 
 
CRY 
 
 CRY 
 
 spheres to each other, all the most simple 
 forms of one species of crystal will be pro- 
 duced, and it is needless to pursue any other 
 modifications of the same form, which must 
 result from a series of decrements produced 
 according to known laws. 
 
 Since then the simplest arrangement of the 
 most simple solid that can be imagined, af- 
 fords so complete a solution of one of the 
 most difficult questions in crystallography, 
 we are naturally led to inquire what forms 
 would probably occur from the union of 
 other solids most nearly allied to the sphere. 
 And it will appear that by the supposition 
 of elementary particles that are spheroidical, 
 we may frame conjectures as to the origin of 
 other angular solids well known to crystallo- 
 graphy's. 
 
 The obtuse Rhomboid. 
 
 If we suppose the axis of our elementary 
 spheroid to be its shortest dimension, a class 
 of solids will be formed which are numerous 
 in crystallography. It has been remarked 
 above, that by the natural grouping of spher- 
 ical particles, fig. 10. one resulting solid is an 
 acute rhomboid, similar to that of fig. 2. hav- 
 ing certain determinate angles, and its greatest 
 dimension in the direction of its axis. Now, 
 if other particles having the same relative 
 arrangement be supposed to have the form 
 of oblate spheroids, the resulting solid, fig. 
 12. will still be a regular rhomboid ; but the 
 measures of its angles will be different from 
 those of the former, and will be more or less 
 obtuse according to the degree of oblateness 
 of the primitive spheroid. 
 
 It is at least possible that carbonate of lime 
 and other substances, of which the forms are 
 derived from regular rhomboids as their pri- 
 mitive form, may, in fact, consist of oblate 
 spheroids as elementary particles. 
 
 Hexagonal Prisms. 
 
 If our elementary spheroid be on the con- 
 trary oblong, instead of oblate, it is evident 
 that, by mutual attraction, their centres will 
 approach nearest to each other when their 
 axes are parallel, and their shortest diameters 
 in the same plane (fig. 13.). The manifest 
 consequence of this structure would be, that 
 a solid so formed would be liable to split into 
 plates at right angles to the axes, and the 
 plates would divide into prisms of three or 
 six sides with all their angles equal, as oc- 
 curs in phosphate of lime, beryl, & c. 
 
 It may farther be observed, that the pro- 
 portion of the height to the base of such a 
 prism, must depend on the ratio between the 
 axes of the elementary spheroid. 
 
 The Cube. 
 
 Let a mass of matter be supposed to con- 
 sist of spherical particles all of the same size, 
 
 but of two different kinds in equal numbers, 
 represented by black and white balls; and 
 let it be required that, in their perfect inter- 
 mixture, every black ball shall be equally 
 distant from all surrounding white balls, and 
 that all adjacent balls of the same denomina- 
 tion shall also be equidistant from each other. 
 The Doctor shews, that these conditions will 
 be fulfilled, if the arrangement be cubical, and 
 that the particles will be in equilibria. Fig. 
 14. represents a cube so constituted of balls, 
 alternately black and white throughout. 
 The four black balls are all in view. The 
 distances of their centres being every way a 
 superficial diagonal of the cube, they are 
 equidistant, and their configuration repre- 
 sents a regular tetrahedron ; and the same is 
 the relative situation of the four white balls. 
 The distances of dissimilar adjacent balls 
 are likewise evidently equal ; so that the 
 conditions of their union are complete, as far 
 as appears in the small group : and this is 
 a correct representative of the entire mass, 
 that would be composed of equal and similar 
 cubes. 
 
 There remains one observation with re- 
 gard to the spherical form of elementary par- 
 ticles, whether actual or virtual, that must 
 be regarded as favourable to the foregoing 
 hypothesis, namely, that many of those sub- 
 stances, which we have most reason to think 
 simple bodies, as among the class of metals, 
 exhibit this further evidence of their simple 
 nature, that they crystallize in the octohedral 
 form, as they would do if their particles were 
 spherical. 
 
 But it must, on the contrary, be acknow- 
 ledged, that we can at present assign no rea- 
 son why the same appearance of simplicity 
 should take place in fluor spar, which is pre- 
 sumed to contain at least two elements ; and 
 it is evident that any attempts to trace a 
 general correspondence between the crystal- 
 lographical and supposed chemical elements 
 of bodies, must, in the present state of these 
 sciences, be premature. 
 
 Any sphere when not compressed will be 
 surrounded by twelve others, and, conse- 
 quently, by a slight degree of compression, 
 will be converted into a dodecahedron, ac- 
 cording to the most probable hypothesis of 
 simple compression. 
 
 The instrument for measuring the angles 
 of crystals is called a goniometer, of which 
 there are two kinds. 1 . The goniometer of M. 
 Carangeau, used by 31. Haiiy, consists of two 
 parallel blades, jointed like those of scissars, 
 and capable of being applied to a graduated 
 semicircular sector, which gives the angle to 
 which the joint is opened, in consequence of 
 the previous apposition of the two blades to 
 the angle of the crystal. 2. The reflective 
 goniometer of Dr Wollaston, an admirable 
 invention, which measures the angles of the 
 minutest possible crystals with the utmost 
 
CRY 
 
 CRY 
 
 precision. An account of this beautiful in- 
 strument may be found in the Phil. I rails, 
 for 1809, and in Tilloch’s Magazine for 
 February 1810, vol. 35. Mr William Phil- 
 lips published, in the 2d volume of the Geo- 
 logical Transactions, an elaborate series of 
 measurements with this goniometer. A stn - 
 ing example of the power of this instrument 
 in detecting the minutest forms with preci- 
 sion was afforded, by its application to a 
 crystalline jet-black sand, which Dr Clarke 
 got from the island Jean Mayen, in the 
 Greenland seas. “ Having therefore,” says 
 Dr Clarke, “ selected a crystal of this form, 
 but so exceedingly minute as scarcely to be 
 discernible to the naked eye, I fixed it upon 
 the moveable plane ot Dr Wollaston s re- 
 flecting goniometer. A double image was 
 reflected by one of the planes of the crystal, 
 but the image reflected by the contiguous 
 plane was clear and perfectly perceptible, by 
 which I was enabled to measure the angle of 
 inclination ; and after repeating the observa- 
 tion several times, I found it to equal 92° ox 
 
 M. Haiiy will no doubt accommodate his 
 results to these indications of Dr Wollaston’s 
 goniometer, and give his theory all the per- 
 fection which its scientific value and elegance 
 deserve. 
 
 M. Beudant has lately made many expe- 
 riments to discover, why a saline princi- 
 ple of a certain kind sometimes impresses its 
 crystalline form upon a mixture in which it 
 does not, by any means, form the greatest 
 part ; and also with the view of determining, 
 why one saline substance may have such an 
 astonishing number of secondary forms, as 
 we sometimes meet with. 
 
 The presence of urea makes common salt 
 take an octohedral form, although in pure 
 water it crystallizes in cubes, similar to its 
 primitive molecules. Sal ammoniac, which 
 crystallizes in pure water in octohedrons, by 
 means of urea crystallizes in cubes. A very 
 slight excess or deficiency of base in alum, 
 causes it to assume either cubical or octo- 
 hedral secondary forms ; and these forms 
 are so truly secondary, that an octohedral 
 crystal of alum, immerged in a solution 
 which is richer in respect to its basis, be- 
 comes enveloped with crystalline layers, which 
 give it at length the form of a cube. 
 
 The crystalline form in muddy solutions 
 acquires greater simplicity, losing all those 
 additional facets which would otherwise mo- 
 dify their predominant form. 
 
 Jn a gelatinous deposit, crystals are rarely 
 
 9 21°. Hence it is evident that these crys- 
 tals are not zircons, although they possess a 
 degree of lustre quite equal to that of zircon. 
 In this uncertainty, I sent a small portion ot 
 the sand to Dr Wollaston, and requested 
 that he would himself measure the angle ot 
 the particles exhibiting splendent surfaces. 
 Dr Wollaston pronounced the substance to 
 be pyroxene ; having an angle, according to 
 his observation, of 92^°. He also informed 
 me that the sand was similar to that ot Bol- 
 senna in Italy.” Such a ready means of 
 minute research forms a delightful aid to the 
 chemical philosopher, as well as the mine- 
 ralogist. M. Haiiy, by a too rigid adher- 
 ence to the principle of geometrical simpli- 
 city, obtained an erroneous determination of 
 the angles in the primary form of carbonate 
 of lime, amounting to 36 minutes ot a de- 
 gree. And by assigning to the magnesian 
 and ferriferous carbonates of lime the same 
 angle as to the simple carbonate, the error 
 became still greater, as vvill appear from the 
 following comparative measurements. 
 
 Error. 
 
 0° 56' 20" 
 
 1° 46' 20" 
 
 2° 31' 20" 
 
 found in groups, but almost alv/ays single, 
 and of a remarkable sharpness and regularity 
 of form, and they do not undergo any varia- 
 tions, but those which may result from the 
 chemical action of the substance forming the 
 deposite. Common salt crystallized in a so- 
 lution of borax, acquires truncations at the 
 solid angles of its cubes ; and alum crystal- 
 lized in muriatic acid, takes a form which 
 M. Beudant has never been able to obtain in 
 any other manner. 
 
 50 or 40 per cent of sulphate of copper 
 may be united to the rhomboidal crystalliza- 
 tion of sulphate of iron, but it reduces this 
 sulpftate to a pure rhomboid, without any 
 truncation either of the angles or the edges. 
 A small portion of acetate of copper reduces 
 sulphate of iron to the same simple rhom- 
 boidal form, notwithstanding that this form 
 is disposed to become complicated with ad- 
 ditional surfaces. Sulphate of alumina 
 brings sulphate of iron to a rhomboid, with 
 the lateral angles only truncated, or what 
 M. Haiiy calls his variete unitaire ; and 
 whenever this variety of green vitriol is found 
 in the market, where it is very common, we 
 may be sure, according to M. Beudant, that 
 it contains alumina. 
 
 Natural crystals mixed w ith foreign sub- 
 stances, are in general more simple than 
 others, as is shewn in a specimen of axinite 
 or violet schorl of Dauphine, one extremity 
 of which being mixed with chlorite, is re- 
 
 Observed angle by 
 Dr Wollaston’s 
 goniometer. 
 
 Carbonate of lime, 105° 5' 
 
 Magnesian carbonate, 106° 15' 
 Ferriferous carbonate, 107° 0' 
 
 Theoretic angle. 
 
 104° 28' 40" 
 104° 28' 40" 
 104° 28' 40" 
 
CRY 
 
 CUB 
 
 duced to its primitive form ; while the other 
 end, which is pure, is varied by many facets 
 produced by different decrements. 
 
 In a mingled solution of two or more 
 salts, of nearly equal solubility, the crystal- 
 lization of one of them may be sometimes 
 determined, by laying or suspending in the 
 liquid, a crystal of that particular salt. 
 
 M. Le Blanc states, that on putting into 
 a tall and narrow cylinder, crystals at diffe- 
 rent heights, in the midst of their saturated 
 saline solution, the crystals at the bottom in- 
 crease faster than those at the surface, and 
 that there arrives a period when those at the 
 bottom continue to enlarge, while those at 
 the surface diminish and dissolve. 
 
 Those salts which are apt to give up their 
 water of crystallization to the atmosphere, 
 and of course become efflorescent, may be 
 preserved by immersion in oil, and subse- 
 quent wiping of their surface. 
 
 In the Wernerian language of crystalliza- 
 tion, the following terms are employed : 
 When a secondary form differs from the 
 cube, the octohedron, &c. only in having 
 several of its angles or edges replaced by a 
 face, this change of the geometrical form is 
 called a truncation. The alteration in the 
 principal form produced by two new faces 
 inclined to one another, and which replace 
 by a kind of bevel, an angle, or an edge, is 
 called a bevelment. When these new faces 
 are to the number of three or more, they 
 produce what Werner termed a pointing, or 
 acumination . When two faces unite by an 
 edge in the manner of a roof, they have been 
 called culmination. . Replacement is occa- 
 
 sionally used for bevelment. 
 
 The reader will find some curious observa- 
 tions on crystallization, by Mr J. F. Daniel), 
 in the 1st volume of the Journal of Science. 
 
 Professor Mohs, successor to Werner in 
 Freyberg, Dr Weiss, professor of mineralogy 
 in Berlin, and M. Brochaut, professor of 
 mineralogy in Paris, have each recently pub- 
 lished systems of mineralogy. Pretty co- 
 pious details, relative to the first, are given 
 in the 3d volume of the Edinburgh Philoso- 
 phical Journal.* 
 
 In a paper in the Journal de Physique, 
 M. Le Blanc gives instructions for obtaining 
 crystals of large size. II is method is to 
 employ flat glass or china vessels : to pour 
 into these the solutions boiled down to the 
 point of crystallization : to select the neatest 
 of the small crystals formed, and put them 
 into vessels with more of the mother-water 
 of a solution that has been brought to crys- 
 tallize confusedly : to turn the crystals at 
 least once a-day ; and to supply them from 
 time to time with fresh mother- water. If 
 
 the crystals be laid on their sides, they will 
 increase most in length ; if on their ends, 
 most in breadth. When they have ceased 
 to grow larger, they must be taken out of 
 
 the liquor, or they will soon begin to dimi- 
 nish. It may be observed in general, that 
 very large crystals are less transparent than 
 those that are small. 
 
 The crystals of metals may be obtained by 
 fusing them in a crucible with a hole in its 
 bottom, closed by a stopper, which is to be 
 drawn out after the vessel has been removed 
 from the fire, and the surface of the metal 
 has begun to congeal. The same effect 
 may be observed if the metal be poured into 
 a plate or dish, a little inclined, which is to 
 be suddenly inclined in the opposite direc- 
 tion, as soon as the metal begins to congeal 
 round its edges. In the first method, the 
 fluid part of the metal runs out of the hole, 
 leaving a kind of cup lined with crystals : in 
 the latter way, the superior part, which is 
 fluid, runs off, and leaves a plate of metal 
 studded over with crystals. 
 
 The operation of crystallizing, or crystal- 
 lization, is of great utility in the purifying 
 of various saline substances. Most salts are 
 suspended in water in greater quantities at 
 more elevated temperatures, and separate 
 more or less by cooling. In this property, 
 and likewise in the quantity of salt capable 
 of being suspended in a given quantity of 
 water, they differ greatly from each other. 
 It is therefore practicable in general to sepa- 
 rate salts by due management of the tempe- 
 rature and evaporation. For example, if a 
 solution of nitre and common salt be eva- 
 porated over the fire, and a small quantity 
 be now and then taken out for trial, it will 
 be found, at a certain period of the concen- 
 tration, that a considerable portion of salt 
 will separate by cooling, and that this salt 
 is for the most part pure nitre. When this 
 is seen, the whole fluid may be cooled to se- 
 parate part of the nitre, after which, evapo- 
 ration may be proceeded upon as before. 
 This manipulation depends upon the diffe- 
 rent properties of the two salts with regard 
 to their solubility and crystallization in like 
 circumstances. For nitre is considerably 
 more soluble in hot than in cold water, 
 while common salt is scarcely more soluble 
 in the one case than in the other. The com- 
 mon salt consequently separates in crystals as 
 the evaporation of the heated fluid goes on, 
 and is taken out with a ladle from time to 
 time, whereas the nitre is separated by suc- 
 cessive coolings at proper periods. 
 
 * Cure Ore. Hexahedral Olivenite. Wur- 
 felerz. Wern. This mineral has a pistacio- 
 green colour, of various shades. It occurs 
 massive, and crystallized in the perfect cube; 
 in a cube with four diagonally opposite angles 
 truncated ; or in one truncated on all its 
 angles ; or finally, both on its edges and 
 angles. 
 
 The crystals are small, with planes smooth 
 and splendent. Lustre glistening. Cleavage 
 parallel with the truncations of the angles. 
 
DAP 
 
 DAT 
 
 Translucent. Streak straw- yellow. Harder 
 than gypsum. Easily frangible. Sp.gr. 3.0. 
 Fuses with disengagement of arsenical va- 
 pours. Its constituents are, 31 arsenic acid, 
 45.5 oxide of iron, 9 oxide of copper, 4 sili- 
 ca, and 1 0.5 water, by Chenevix. Vauquelin’s 
 analysis gives no copper nor silica, but 4S 
 iron, 18 arsenic acid, 2 to 3 carbonate of lime, 
 and 32 water. It is found in veins, accom- 
 panied with iron-shot quartz, in Tincroft 
 and various other mines of Cornwall, and at 
 St Leonard in the Haut- Vienne in France. 
 As an arseniate of iron, it might be ranked 
 among the ores of either this metal or 
 arsenic. — Jameson. * 
 
 Cupel. A shallow earthen vessel, some- 
 what resembling a cup, from which it derives 
 its name. It is made of phosphate of lime, 
 or the residue of burned bones rammed into 
 a mould, which gives it its figure. This 
 vessel is used in assays wherein the precious 
 metals are fused with lead, which becomes 
 converted into glass, and carries the impure 
 alloy with it. See Assay. 
 
 Cupellation. The refining of gold by 
 scorification with lead upon the cupel, is 
 called cupellation. See Assay. 
 
 Curd. The coagulura which separates 
 from milk upon the addition of acid, or other 
 substances. See Milk. 
 
 * Cyanite, or Kyanite. Disthene of 
 
 Haiiy. Its principal colour is Berlin-blue, 
 which passes into grey and green. It oc- 
 curs massive and disseminated, also in dis- 
 tinct concretions. The primitive form of its 
 crystals is an oblique four- sided prism ; and 
 the secondary forms are, an oblique four- 
 sided prism, truncated on the lateral edges, 
 and a twin crystal. The planes are streaked, 
 splendent, and pearly. Cleavage threefold. 
 Translucent or transparent. Surface of the 
 broader lateral planes as hard as apatite ; 
 that of the angles, as quartz. Easily fran- 
 gible. Sp. gr. 3.5. When pure it is idio- 
 electric. Some crystals by friction acquire 
 negative, others positive electricity ; hence 
 Haiiy’s name. It is infusible before tho 
 blow-pipe. It consists by Klaproth, of 43 
 silica, 55.5 alumina, 0.50 iron, and a trace 
 of potash. It occurs in the granite and 
 mica slate of primitive mountains. It is 
 found near Banchory in Aberdeenshire, and 
 Bocharm in Banffshire ; at Airolo on St 
 Gothard, and in various countries of Europe, 
 as well as in Asia and America. It is cut 
 and polished in India as an inferior sort of 
 sapphire. — Jameson .* 
 
 * Cyanogen. The compound base of 
 prussic acid. See Prussine. * 
 
 * Cymophane of Haiiy. The Chryso-v 
 
 BERYL. 
 
 D 
 
 D AMPS. The permanently elastic fluids 
 which are extricated in mines, and are 
 destructive to animal life, are called damps 
 by the miners. The chief distinctions made 
 by the miners, are choak-damp, which ex- 
 tinguishes their candles, hovers about the 
 bottom of the mine, and consists for the 
 most part of carbonic acid gas ; and fire- 
 damp, or hydrogen gas, w hich occupies the 
 superior spaces, and does great mischief by 
 exploding whenever it comes in contact with 
 their lights. See Gas, Combustion, & Lamp. 
 
 * Daourite. A variety of red schorl 
 from Siberia.* 
 
 * Daphnin. The bitter principle of 
 Daphne Alpina , discovered by M. Vau- 
 quelin. From the alcoholic infusion of this 
 bark, the resin was separated by its concen- 
 tration. On diluting the tincture with win- 
 ter, filtering, and adding acetate of lead, a 
 yellow daphnate of lead fell, from which sul- 
 phuretted hydrogen separated the lead, and 
 left the daphnin in small transparent crystals. 
 They are hard, of a greyish colour, a bitter 
 taste when heated, evaporate in acrid acid 
 vapours, sparingly soluble in cold, but mo- 
 derately in boiling water. It is stated, that 
 its solution is not precipitated by acetate of 
 lead ; yet acetate of lead is employed in the 
 first process to throw it down,* 
 
 * Datolite. Datholit of Werner. This 
 species is divided into two sub-species, viz. 
 Common Datolite, and Botroidal Datolite. 
 
 1. Common datolite. Colour white of 
 various shades, and greenish-grey, inclining 
 to celadine- green. It occurs in large coarse, 
 
 and small granular distinct concretions, and 
 crystallized. Primitive form, an oblique four- 
 sided prism of 109° 28' and 70° 32'. The 
 principal secondary forms, are the low oblique 
 four-sided prism, and the rectangular four- 
 sided prism, flatly acuminated on the ex- 
 tremities, with four planes which are set on the 
 lateral planes. The crystals are small and 
 in druses. Lustre shining and resinous. 
 Cleavage imperfect, parallel with the lateral 
 planes of the prism. Fracture fine grained, 
 uneven, or imperfect conchoidal. Translu- 
 cent or transparent. Fully as hard as apa- 
 tite. Very brittle, and difficultly frangible. 
 Sp. gr. 2.9. When exposed to the flame of 
 a candle it becomes opaque, and may then be 
 rubbed down between the fingers. Before 
 the blow-pipe it intumesces into a milk-white 
 coloured mass, and then melts into a globule 
 ol a pale rose colour. Its constituents are, 
 by Klaproth, silica 36.5, lime 35.5, boracic 
 acid 24.0, water 4, trace of iron and man- 
 ganese. It is associated with large foliaitecf 
 
DEC 
 
 DEL 
 
 granular calcareous spar, at the mine of 
 Nodebroe, near Arendal in Norway. It re- 
 sembles prehnite, but is distinguished by re- 
 sinous lustre, compact fracture, inferior hard- 
 ness, and not becoming electric by heating. — 
 Jameson.* 
 
 * l 2. Botroidal Datolite. Sec Botryo- 
 
 LITE.* 
 
 * Datura. A vcgeto-alkali obtained from 
 Datura Stramonium.* 
 
 * Dead- Sea Wateh. See Water.* 
 
 Decantation. The action of pouring off 
 
 the clearer part of a fluid by gently inclining 
 the vessel after the grosser parts have been 
 suffered to subside. 
 
 Decoction. The operation of boiling. 
 This term is likewise used to denote the 
 fluid itself which has been made to take up 
 certain soluble principles by boiling, Thus 
 we say a decoction of the bark, or other parts 
 of vegetables, of flesh, &c. 
 
 Decomposition is now understood to im- 
 ply the separation of the component parts or 
 principles of bodies from each other. 
 
 The decomposition of bodies forms a very 
 large part of chemical science. It seems 
 probable from the operations we are ac- 
 quainted with, that it seldom takes place but 
 in consequence of some combination or com- 
 position having been effected. It would be 
 difficult to point out an instance of the separ- 
 ation of any of the principles of bodies which 
 has been effected, unless in consequence of 
 some new combination. The only excep- 
 tions seem to consist in those separations 
 which are made by heat, and voltaic electri- 
 city. See Analysisj Gas, Metals, Ores, 
 .Salts, Mineral Waters. 
 
 * Decrepitation. The crackling noise 
 which several salts make when suddenly 
 heated, accompanied by a violent exfoliation 
 of their particles. This phenomenon has been 
 ascribed by Dr Thomson, and other chemi- 
 cal compilers, to the “ sudden conversion 
 of the water which they contain into steam.” 
 Hut the very example, sulphate of barytes, to 
 which these words are applied, is the strong- 
 est evidence of the falseness of the explana- 
 tion ; for absolutely dry sulphate of barytes 
 decrepitates furiously, without any possible 
 formation of steam, or any loss of weight. 
 The same thing holds with regard to common 
 salt, calcareous spars, and sulphate of potash, 
 which contain no water. In fact, it is the 
 salts which are anhydrous, or destitute of 
 water, which decrepitate most powerfully ; 
 those that contain water, generally enter into 
 tranquil liquefaction on being heated. Salts 
 decrepitate, for the same reason that glass, 
 quartz, and cast-iron crack, with an explosive 
 force, when very suddenly heated ; namely, 
 from the unequal expansion of the lamina; 
 which compose them, in consequence of their 
 being imperfect conductors of heat. i he 
 true cleavage of minerals may often be de- 
 
 tected in this 'way, for they fly asunder at 
 their natural fissures.* 
 
 * Delphinite. See Pistacite.* 
 
 * Delpiiinia. A new vegetable alkali, 
 recently discovered by MM. Lasseigne and 
 leneulle, in the Delphinium staphysagria , or 
 Stavesacre. It is thus obtained : 
 
 The seeds, deprived of their husks, and 
 ground, are to be boiled in a small quantity 
 of distilled water, and then pressed in a 
 cloth. The decoction is to be filtered, and 
 boiled for a few minutes with pure mag- 
 nesia. It must tli en be re-filtered, and the 
 residuum left on the filter is to be well 
 washed, and then boiled with highly recti- 
 fied alcohol, which dissolves out the alkali. 
 By evaporation, a white pulverulent sub- 
 stance, presenting a few crystalline points, is 
 obtained. 
 
 It may also be procured by the action of 
 dilute sulphuric acid, on the bruised but un- 
 shelled seeds. The solution of sulphate thus 
 formed, is precipitated by subcarbonate of 
 potash. Alcohol separates from this precipi- 
 tate the vegetable alkali in an impure state. 
 
 Pure delphinia obtained by the first pro- 
 cess, is crystalline while wet, but becomes 
 opaque on exposure to air. Its taste is bitter 
 and acrid. When heated it melts; and on 
 cooling becomes hard and brittle like resin. 
 If more highly heated, it blackens and is de- 
 composed. Water dissolves a very small 
 portion of it. Alcohol and ether dissolve it 
 very readily. The alcoholic solution renders 
 syrup of violets green, and restores the blue 
 tint of litmus reddened by an acid. It forms 
 soluble neutral salts with acids. Alkalis 
 precipitate the delphinia in a white gelatinous 
 state, like alumina. 
 
 Sulphate of delphinia evaporates in the air, 
 does not crystallize, but becomes a transpa- 
 rent mass like gum. It dissolves in alcohol 
 and water, and its solution has a bitter acrid 
 taste. In the voltaic circuit it is decom- 
 posed, giving up its alkali at the negative 
 pole. 
 
 Nitrate of delphinia, when evaporated to 
 dryness, is a yellow crystalline mass. If treated 
 with excess of nitric acid, it becomes con- 
 verted into a yellow matter, little soluble in 
 water, but soluble in boiling alcohol. This 
 solution is bitter, is not precipitated by pot- 
 ash, ammonia, or lime-water, and appears to 
 contain no nitric acid, though itself is not 
 alkaline. It is not destroyed by further 
 quantities of acid, nor does it form oxalic 
 acid. Strychnia and morphia take a red 
 colour from nitric acid, but delphinia never 
 does. The muriate is very soluble in water. 
 
 The acetate of delphinia does not crystal- 
 lize, but forms a hard transparent mass, bitter 
 and acrid, and readily decomposed by cold 
 sulphuric acid. The oxalate forms small 
 white plates, resembling in taste the preced- 
 ing salts. 
 
DEW 
 
 DEW 
 
 Delphinia, calcined with oxide of copper, 
 gave no other gas than carbonic acid. It 
 exists in the seeds of the stavesacre, in com- 
 bination with malic acid, and associated with 
 the following principles : 1. A brown bitter 
 
 principle, precipitable by acetate of lead, 
 2, Volatile oil. 3. Fixed oil. 4. Albumen. 
 5. Animalized matter. 6. Mucus. 7. Sac- 
 charine mucus. 8. Yellow bitter principle, 
 not precipitable by acetate oi lead. 9. Mine- 
 ral salts . — Annales de Chiniie et Physique, 
 vol. xii. p. 358.* 
 
 Deliquescence. The spontaneous as- 
 sumption of the fluid state by certain saline 
 substances, when left exposed to the air, 
 in consequence of the water they attract 
 from it. 
 
 Dephlegmation, Any method by which 
 bodies are deprived of water. 
 
 Dephlogisttcated. A term of the old 
 chemistry implying deprived of phlogiston, 
 or the inflammable principle, and nearly 
 synonymous with what is now expressed by 
 oxygenated, or oxidized. 
 
 Deph logistic ated Air. The same with 
 oxygen gas. 
 
 Derbyshire Spar. A combination of 
 calcareous earth with a peculiar acid called 
 the Fluoric, which see. 
 
 * Desiccation is most elegantly accom- 
 plished, by means of the air-pump and sul- 
 phuric acid, as is explained under Congela- 
 tion. * 
 
 Destructive Distillation. When organ- 
 ized substances, or their products, are exposed 
 to distillation, until the whole has suffered all 
 that the furnace can effect, the process is call- 
 ed destructive distillation. 
 
 Detonation. A sudden combustion and 
 explosion. See Combustion, Fulminating 
 Powders, and Gunpowder. 
 
 * Dew. The moisture insensibly depo- 
 sited from the atmosphere on the surface of 
 the earth. 
 
 The first facts which could lead to the just 
 explanation of this interesting, and, till very 
 lately, inexplicable natural phenomenon, are 
 due to the late Mr A. Wilson, professor of 
 astronomy in Glasgow, and his son. The 
 first stated, in the Phil. Trans, for 1771, that 
 on a winter night, during which the atmos- 
 phere was several times misty and clear 
 alternately, he observed a thermometer, sus- 
 pended in the air, always to rise from a half 
 to a whole degree, whenever the former 
 state began, and to fall as much as soon as 
 the weather became serene. Dr Patrick 
 Wilson communicated, in 1786, to the 
 Itoyal Society of Edinburgh, a valuable paper 
 on hoar-frost, which was published in the 
 first volume of their Transactions. It is re- 
 plete with new and valuable observations, 
 whose minute accuracy subsequent expe- 
 rience ha$ confirmed. Dr Wilson had pre- 
 viously, in 1781, described the surface of 
 
 snow, during a clear and calm night, to be 
 16° colder than air 2 feet above it; and in 
 the above paper he shews, that the deposition 
 of dew and hoar-frost is uniformly accom- 
 panied with the production of cold. He 
 was the first among philosophical observers 
 who noticed this conjunction. But the dif- 
 ferent force with which different surfaces 
 project or radiate heat being then unknown. 
 Dr Wilson could not trace the phenomena 
 of dew up to their ultimate source. This 
 important contribution to science has been 
 lately made by Dr Wells, in his very inge- 
 nious and masterly essay on dew. 
 
 1. Phenomena of Dew. 
 
 Aristotle justly remarked, that dew ap- 
 pears only on calm and clear nights. Dr 
 Wells shews that very little is ever deposited 
 in opposite circumstances; and that little 
 only when the clouds are very high. It is 
 never seen on nights both cloudy and windy ; 
 and if in the course of the night the weather, 
 from being serene, should become dark and 
 stormy, dew which had been deposited will 
 disappear. In calm weather, if the sky be 
 partially covered with clouds, more dew will 
 appear than if it were entirely uncovered. 
 
 Dew probably begins in the country to 
 appear upon grass, in places shaded from 
 the sun, during clear and calm weather, 
 soon after the heat of the atmosphere has de- 
 clined, and continues to be deposited through 
 the whole night, and for a little after sun- 
 rise. Its quantity will depend in some mea- 
 sure on the proportion of moisture in the at- 
 mosphere, and is consequently greater after 
 rain than after a long tract of dry weather ; 
 and in Europe, with southerly and westerly 
 winds, than with those which blow from the 
 north and the east. The direction of the sea 
 determines this relation of the winds to dew-. 
 For in Egypt, dew is scarcely ever observed 
 except while the northerly or Etesian winds 
 prevail. Hence also, dew is generally more 
 abundant in spring and autumn, than in 
 summer. And it is always very copious on 
 those clear nights which are followed by 
 misty mornings, which shew the air to be 
 loaded with moisture. And a clear morn- 
 ing, following a cloudy night, determines a 
 plentiful deposition of the retained vapour. 
 When warmth of atmosphere is compatible 
 with clearness, as is the case in southern lati- 
 tudes, though seldom in our country, the 
 dew becomes much more copious, because 
 the air then contains more moisture. Dew 
 continues to form with increased copiousness 
 as the night advances, from the increased re- 
 frigeration of the ground. 
 
 2. On the cause of dew. 
 
 Dew, according to Aristotle, is a species 
 of rain, formed in the lower atmosphere, in con- 
 sequence of its moisture being condensed by 
 the cold of the night into minute drops. Opi- 
 nions of this kind, says Dr Wells, are still 
 
DEW 
 
 DEW 
 
 entertained by many persons, among whom 
 is the very ingenious Professor Leslie. ( Relat. 
 of Heat and Moisture , p. 37. and 182.,/ A 
 fact, however, first taken notice of by Ger- 
 stin, who published his treatise on dew in 
 1773, proves them to be erroneous ; for he 
 found that bodies a little elevated in the air, 
 often become moist with dew, while similar 
 bodies, lying on the ground, remain dry, 
 though necessarily, from their position, as 
 liable to be wetted, by whatever falls from 
 the heavens, as the former. The above no- 
 tion is perfectly refuted, by what will presently 
 appear relative to metallic surfaces exposed 
 to the air in a horizontal position, which 
 remain dry, while every thing around them 
 is covered with dew. 
 
 After a long period of drought, when the 
 air was very still and the sky serene, Dr 
 Wells exposed to the sky, 28 minutes before 
 sunset, previously weighed parcels of wool 
 and swandown, upon a smooth, unpainted, 
 and perfectly dry fir table, 5 feet long, 3 
 broad, and nearly 3 in height, which had 
 been placed an hour before, in the sunshine, 
 in a large level grass field. The wool, j 2 
 minutes after sunset, was found to be 14° 
 colder than the air, and to have acquired no 
 weight. The swandown, the quantity of 
 which was much greater than that of the 
 wool, w’as at the same time 13° colder than 
 the air, and was also without any additional 
 weight. In 20 minutes more, the swandown 
 was 14^° colder than the neighbouring air, 
 and was still without any increase of its 
 weight. At the same time the grass was 15° 
 colder than the air four feet above the ground. 
 
 Dr Wells, by a copious induction of facts 
 derived from observation and experiment, 
 establishes the proposition, that bodies become 
 colder than the neighbouring air before they 
 are dewed. The cold therefore which Dr 
 "Wilson and Mr Six conjectured to be the 
 effect of dew, now appears to be its cause. 
 But what makes the terrestrial surface colder 
 than the atmosphere ? The radiation or pro- 
 jection of heat into free space. Now the 
 researches of Professor Leslie and Count 
 Rumford have demonstrated, that different 
 bodies project heat with very different degrees 
 of force. 
 
 In the operation of this principle, there- 
 fore, conjoined with the power of a concave 
 mirror of cloud or any other awning, to re- 
 flect or throw down again those calorific ema- 
 nations which would be dissipated in a clear 
 sky, we shall find a solution of the most mys- 
 terious phenomena of dew. Two circum- 
 stances must here be considered : — 
 
 1. The exposure of the particular surface 
 to be dewed, to the free aspect of the sky. 
 
 2. The peculiar radiating power of the 
 surface. I. Whatever diminishes the view of 
 the sky, as seen from the exposed body, ob- 
 structs the depression of its temperature, and 
 
 occasions the quantity of dew formed upon 
 it, to be less than would have occurred, if 
 the exposure to the sky had been complete. 
 
 Dr Wells bent a sheet of pasteboard into 
 the shape of a penthouse, making the angle 
 of flexure 90 degrees, and leaving both ends 
 open. I his was placed one evening with its 
 ridge uppermost, upon a grass-plat in the 
 direction of the wind, as well as this could 
 be ascertained. lie then laid 10 grains of 
 white, and moderately fine wool, not artifi- 
 cially dried, on the middle part of that spot 
 of the grass which was sheltered by the 
 roof, and the same quantity on another part 
 of the grass-plat, fully exposed to the sky. 
 In the morning the sheltered wool was found 
 to have increased in weight only 2 grains, but 
 that which had been exposod to the sky 16 
 grains. He varied the experiment on the same 
 night, by placing upright on the grass-plat a 
 hollow cylinder of baked clay, 1 foot diame- 
 ter, and feet high. On the grass round 
 the outer edge of the cylinder, were laid 10 
 grains of wool, which in this situation, as there 
 was not the least wind, would have receiv-. 
 ed as much rain, as a like quantity of wool, 
 fully exposed to the sky. But the quantity 
 of moisture acquired by the w ool, partially 
 screened by the cylinder from the aspect of 
 the sky tvas only about 2 grains, while that 
 acquired by the same quantity fully exposed, 
 was 1 6 grains. Repose of a body seems neces- 
 sary to its acquiring its utmost coolness, and 
 a full deposit of dew\ Gravel w'alks and 
 pavements project heat, and acquire dew, 
 less readily than a grassy surface. Hence 
 w r ool placed on the former has its tempera- 
 ture less depressed than on the latter, and 
 therefore is less bedewed. Nor does the 
 wool here attract moisture by capillary action 
 on the grass, for the same effect happens if it 
 be placed in a saucer. Nor is it by hvgro- 
 metric attraction, for in a cloudy night, wool 
 placed on an elevated board acquired scarce- 
 ly any increase of weight. 
 
 If wool be insulated a few’ feet from the 
 ground on a bad conductor of heat, as a 
 board, it will become still colder than when 
 in contact with the earth, and acquire fully 
 more dew’, than on the grass. At the wind- 
 ward end of the board, it is less bedewed 
 than at the sheltered end, because in the 
 former case, its temperature is nearer to that 
 of the atmosphere. Rough and porous sur- 
 faces, as shavings of wood, take more dew 
 than smooth and solid wood ; and raw silk 
 and fine cotton are more powerful in this 
 respect than even wool. Glass projects heat 
 rapidly, and is as rapidly coated with dew. 
 But bright metals attract dew much less 
 powerfully than other bodies. If we coat a 
 piece of glass, partially, with bright tin-foil, 
 or silver leaf, the uncovered portion of the 
 glass quickly becomes cold by radiation, on 
 exposure to a clear nocturnal sky, and ac- 
 
DEW 
 
 DEW 
 
 quires moisture; which beginning on those 
 parts most remote from the metal, gradually 
 approaches it. Thus also, if we coat outward- 
 ly a portion of a window pane with tin-foil, 
 in a clear night, then moisture will be depo- 
 sited inside, on every part except opposite to 
 the metal. But if the metal be inside, then 
 the glass under and beyond it will be sooner, 
 or most copiously bedewed. In the first case, 
 the tin-foil prevents the glass under it from 
 dissipating its heat, and therefore it can re- 
 ceive no dew ; in the second case, the tin- 
 foil prevents the glass which it coats, from 
 receiving the calorific influence of the apart- 
 ment, and hence it is sooner refrigerated by 
 external radiation, than the rest of the pane. 
 Gold, silver, copper, and tin, bad radiators of 
 heat, and excellent conductors, acquire dew 
 with greater difficulty than platina, which is 
 a more imperfect conductor; or than lead, 
 zinc, and steel, which are better radiators. 
 
 Hence dew which has formed upon a 
 metal will often disappear, while other sub- 
 stances in the neighbourhood remain wet ; 
 and a metal purposely moistened, will be- 
 come dry, while neighbouring bodies are 
 acquiring moisture. This repulsion of dew 
 is communicated by metals to bodies in con- 
 tact with, or near them. Wool laid on me- 
 tal acquires less dew, than wool laid on the 
 contiguous grass. 
 
 If the night becomes cloudy, after having 
 been very clear, though there be no change 
 with respect to calmness, a considerable al- 
 teration in the temperature of the grass al- 
 ways ensues. Upon one such night, the 
 grass, after having been 12° colder than the 
 -air, became only 2° colder ; the atmospheric 
 temperature being the same at both observa- 
 tions. On a second night, grass became 9° 
 warmer in the space of an hour and a half; 
 on a third night, in less than 45 minutes, 
 
 the temperature of the grass rose 15°, while 
 that of the neighbouringairincreasedonly5^°. 
 During a fourth night, the temperature of 
 the grass at half past 9 o’clock was 52°. In 
 20 minutes afterwards, it was found to be 
 39°, the sky in the mean time having become 
 cloudy. At the end of 20 minutes more, 
 the sky being clear, the temperature of the 
 grass was again 32°. A thermometer lying 
 on a grass-plat, will sometimes rise several 
 degrees, when a cloud comes to occupy the 
 zenith of a clear sky. 
 
 When, during a clear and still night, dif- 
 ferent thermometers, placed in different si- 
 tuations, w r ere examined, at the same time, 
 those which were situated where most dew 
 was formed, were always found to be the 
 lowest. On dewy nights the temperature 
 of the earth, half an inch or an inch be- 
 neath the surface, is always found much 
 warmer than the grass upon it, or the air 
 above it. The differences on five such nights, 
 were from 12 to 16 degrees. 
 
 In making experiments with thermome- 
 ters it is necessary to coat their bulbs with 
 silver or gold leaf, otherwise the glassy sur- 
 face indicates a lower temperature than that 
 of the air, or the metallic plate it touches. 
 Swandown seems to exhibit greater cold, on 
 exposure to the aspect of a clear sky, than 
 any thing else. When grass is 14° below 
 the atmospheric temperature, swandown is 
 commonly 15°. Fresh unbroken straw and 
 shreds of paper, rank in this respect with 
 swandown. Charcoal, lampblack, and rust 
 of iron, are also very productive of cold. 
 Snow stands 4° or 5° higher than swandow’n 
 laid upon it in a clear night. 
 
 The following tabular view r of observa- 
 tions by Dr Wells, is peculiarly instruc- 
 tive : — 
 
 Heat of the air 4 feet above the crass. 
 
 wool on a raised board, 
 
 swandown on the same, 
 
 surface of the raised board, 
 
 grass-plat. 
 
 6b. 45' 
 
 7 h. 
 
 7h.20' 
 
 7h.'10' 
 
 8h.45' 
 
 60i° 
 
 60|° 
 
 59° 
 
 53° 
 
 54° 
 
 5Si 
 
 5-4 
 
 51£ 
 
 
 44f 
 
 5-H 
 
 53 
 
 51 
 
 4 H 
 
 42i 
 
 58 
 
 57 
 
 5b\ 
 
 — 
 
 
 53 
 
 51 
 
 49i 
 
 49 
 
 42 
 
 The temperature always falls in clear 
 nights, but the deposition of dew, depending 
 on the moisture of the air, may occur or not. 
 Now, if cold were the effect of dew, the cold 
 connected with dew ought to lie always pro- 
 portional to the quantity of that fluid ; but? 
 this is contradicted by experience. On the 
 other hand, if it be granted that dew r is wa- 
 ter precipitated from the atmosphere, by the 
 cold of the body on wffiich it appears, the 
 same degree of cold in the precipitating body 
 may be attended with much, with little, or 
 
 with no dew, according to the existing state 
 of the air in regard to moisture, all of which 
 circumstances are found really to take place. 
 The actual precipitation of dew, indeed, ought 
 to evolve heat. 
 
 A very few degrees of difference of tem- 
 perature between the grass and the atmos- 
 phere is sufficient to determine the formation 
 of dew, w hen the air is in a proper state. 
 But a difference of even 30°, or more, some- 
 times exists, by the radiation of heat from 
 the earth to the heavens. And hence, the 
 
DEW 
 
 DEW 
 
 air near the refrigerated surface must be 
 colder than that somewhat elevated. Agree- 
 ably to Mr Six s observations, the atmos- 
 phere, at the height of 220 feet, is often, up- 
 on such nights, 10° warmer than what it is 
 seven feet above the ground. And had not 
 the lower air thus imparted some of its heat 
 to the surface, the latter would have been pro- 
 bably 40° under the temperature of the air. 
 
 Insulated bodies, or prominent points, are 
 sooner covered with hoar-frost and dew than 
 others ; because the equilibrium of their tem- 
 perature is more difficult to be restored. As 
 aerial stillness is necessary to the cooling effect 
 of radiation, we can understand why the hurt- 
 ful effects of cold, heavy fogs, and dews, oc- 
 cur chiefly in hollow and confined places, 
 and less frequently on hills. In like man- 
 ner, the leaves of trees often remain dry 
 throughout the night, while the blades of 
 grass are covered with dew. 
 
 No direct experiments can be made to as- 
 certain the manner in which clouds prevent 
 or lessen the appearance of a cold at night, 
 upon the surface of the earth, greater than 
 that of the atmosphere. But it may be con- 
 cluded from the preceding observations, that 
 they produce this effect almost entirely by 
 radiating heat to the earth, in return for that 
 which they intercept in its progress from the 
 earth towards the heavens. The heat extri- 
 cated by the condensation of transparent va- 
 pour into cloud must soon be dissipated ; 
 whereas, the effect of greatly lessening or 
 preventing altogether the appearance of a 
 greater cold on the earth than that of the air, 
 will be produced by a cloudy sky during the 
 w hole of a long night. 
 
 We can thus explain, in a more satisfac- 
 tory manner than has usually been done, the 
 sudden warmth that is felt in w' in ter, when a 
 fleece of clouds supervenes in clear frosty 
 weather. Chemists ascribed this sudden 
 and powerful change to the disengagement 
 of the latent heat of the condensed vapours ; 
 but Dr Wells’s thermometric observations on 
 the sudden alternations of temperature by 
 cloud and clearness, render that opinion un- 
 tenable. We find the atmosphere itself, in- 
 deed, at moderate elevations, of pretty uni- 
 form temperature, while bodies at the sur- 
 face of the ground suffer great variations in 
 their temperature. This single fact is fatal 
 to the hypothesis derived from the doctrines 
 of latent heat. 
 
 “ I had often,” says Dr Wells, “ smiled, 
 in the pride of half knowledge, at the means 
 frequently employed by gardeners, to pro- 
 tect tender plants from cold, as it appeared 
 to me impossible that a thin mat, or any 
 such flimsy substance, could prevent them 
 from attaining the temperature of the atmos- 
 phere, by which alone I thought them liable 
 to be injured. But when I had learned, 
 that bodies pn the surface of the earth be- 
 
 come, during a still and serene night, colder 
 than the atmosphere, by radiating their heat 
 to the heavens, I perceived immediately a 
 just reason for the practice, which I had be- 
 fore deemed useless. Being desirous, how- 
 ever, of acquiring some precise information 
 on this subject, i fixed perpendicularly, in 
 the earth of a grass-plat, four small sticks, 
 and over their upper extremities, which were 
 six inches above the grass, and formed the 
 corners of a square w hose sides were two feet 
 long, I drew tightly a very thin cambric 
 handkerchief. In this disposition of things, 
 therefore, nothing existed to prevent the free 
 passage of air from the exposed grass to that 
 which was sheltered, except the four small 
 sticks, and there was no substance to radiate 
 downwards to the latter grass, except the 
 cambric handkerchief.” 
 
 The sheltered grass, how r ever, was found 
 nearly of the same temperature as the air, 
 w hile the unsheltered w r as 5° or more colder. 
 One night the fully exposed grass was 1 1 ° 
 colder than the air; but the sheltered grass 
 w r as only 3° colder. Hence we see the power 
 of a very slight awning, to avert or lessen 
 the injurious coldness of the ground. To 
 have the full advantage of such protection 
 from the chill aspect of the sky, the covering 
 should not touch the subjacent bodies. Gar- 
 den w'alls act partly on the same principle. 
 Snow screens plants from this chilling radia- 
 tion. In warm climates, the deposition of 
 dewy moisture on animal substances hastens 
 their putrefaction. As this is apt to happen 
 only in clear nights, it was anciently sup- 
 posed that bright moonshine favoured ani- 
 mal corruption. 
 
 From this rapid emission of heat from the. 
 surface of the ground, w e can now explain 
 the formation of ice during the night in 
 Bengal, while the temperature of the air is 
 above 32°. The nights most favourable for 
 this effect, are those which are the calmest 
 and most serene, and on which the air is so 
 dry as to deposit little dew after midnight. 
 Clouds and frequent changes cf wind are 
 certain preventives of congelation. 300 
 persons are employed in this operation at one 
 place. The enclosures formed on the ground 
 are four or five feet wide, and have walls 
 only four inches high. In the§e enclosures, 
 previously bedded with dry straw, broad, 
 shallow, unglazed earthen pans are set, con- 
 taining unboiled pump-water. Wind, which 
 so greatly promotes evaporation, prevents the 
 freezing altogether, and dew forms in a 
 greater or less degree during the whole of 
 the nights most productive of ice. If eva- 
 poration were concerned in the congelation, 
 wetting the straw would promote it. But 
 Mr Williams, in the 83d vol. of the l’hil. 
 Trans, says, that it is tiecessciry to the suc- 
 cess of the process that the straw be dry. 
 In proof of this he mentions, that when. 
 
DIA 
 
 DIA 
 
 the straw becomes wet by accident it is re- 
 newed ; and that when he purposely wetted 
 it in some of the inclosures, the formation of 
 ice there was always prevented. Moist straw 
 both conducts heat and raises vapour from 
 the ground, so as to obstruct the congelation. 
 According to Mr Leslie, water stands at the 
 head of radiating substances. See Caloric.* 
 
 * Diallage. A species of the genus 
 Schiller spar. Diallage has a grass-green 
 colour. It occurs massive or disseminated. 
 Lustre glistening and pearly. Cleavage im- 
 perfect double. Translucent. Harder than 
 fluor spar. Brittle. Sp. gr. 5.1. It melts 
 before the blow-pipe into a grey or greenish 
 enamel. Its constituents are 50 silica, 1 1 
 alumina, 6 magnesia, J3 lime, 5.3 oxide of 
 iron, 1.5 oxide of copper, 7.5 oxide of chrome. 
 Vauquelin. It occurs in the island of Cor- 
 sica, and in Mont Rosa in Switzerland, along 
 with saussurite. It is the verde di Corsica 
 duro of artists, by whom it is fashioned into 
 ring-stones and snuff-boxes. It is the smar- 
 agdite of Saussure. 
 
 The diallage in the rock is called gabbro. * 
 
 * Diamond. Colours white and grey, 
 also red, brown, yellow, green, blue, and 
 black. The two last are rare. When cut 
 it exhibits a beautiful play of colours in the 
 sunbeam. It occurs in rolled pieces, and 
 also crystallized : 1st, In the octohedron, in 
 which each plane is inclined to the adjacent, 
 at an angle of 109° 28' 16". The faces are 
 usually curvilinear. This is the fundamental 
 figure. 2d, A simple three-sided pyramid, 
 truncated on all the angles. 3d, A segment 
 of the octohedron. 4th, Twin crystal. 5th, 
 Octohedron, with all the edges truncated. 6th, 
 Octohedron, flatly bevelled ou all the edges. 
 7th, Rhomboidal dodecahedron. 8th, Octo- 
 hedron with convex faces, in which each is 
 divided into three triangular ones, forming 
 altogether 24 faces. 9th, Octohedron, in 
 which each convex face is divided into six 
 planes, forming 48 in all. 10th, Rhomboi- 
 dal dodecahedron, with diagonally broken 
 planes. 1 1 th, A flat double three-sided py- 
 ramid. 12th, Very flat double three-sided 
 pyramid, with cylindrical convex faces. 1 5th, 
 Very flat double six-sided pyramid. 14th, 
 Cube truncated on the edges.* Crystal small. 
 Surface rough, uneven, or streaked. Lustre 
 splendent, and internally perfect adamantine. 
 Cleavage octohedral, or parallel to the sides 
 of an octohedron. Foliated structure. Frag- 
 ments octohedral or tetrahedral. Semi-trans- 
 parent. Refracts single. Scratches all known 
 minerals. Rather easily frangible. Streak 
 grey. Sp. gr. 3.4 to 3.6. It consists of 
 pure carbon, as we shall presently demon- 
 strate. V hen rubbed, whether in the rough 
 or polished state, it shews positive electricity ; 
 whereas rough quartz affords negative. It 
 becomes phosphorescent on exposure to the 
 sun, or the electric spark, and shines with a 
 
 fiery light. In its power of refracting light 
 it is exceeded only by red lead-ore, and or- 
 piment. It reflects all the light falling on 
 its posterior surface at an angle of incidence 
 greater than 24° 15', whence its great lustre 
 is derived. Artificial gems reflect the half 
 of this light. It occurs in imbedded grains 
 and crystals in a sandstone in Brazil, which 
 rests on chlorite and clay-slate. In India 
 the diamond bed of clay is underneath beds 
 of red or bluish- black clay ; and also in 
 alluvial tracts both in India and Brazil. 
 For the mode of working diamond mines, 
 and cutting and polishing diamonds, consult 
 Jameson s Mineralogy , vol i. p. 11. 
 
 The diamond is the most valued of all 
 minerals. Dr Wollaston has explained the 
 cutting principle of glaziers’ diamonds, with 
 his accustomed sagacity, in the Phil. Trans, 
 for 1816. 
 
 The weight, and consequently the value 
 of diamonds, is estimated in carats, one of 
 which is equal to four grains, and the price 
 of one diamond, compared to that of another 
 of equal colour, transparency, purity, form, 
 &c. is as the squares of the respective weights. 
 The average price of rough diamonds that 
 are worth working, is about L. 2 for the first 
 carat. The value of a cut diamond being 
 equal to that of a rough diamond of double 
 weight, exclusive of the price of workman- 
 ship, the cost of a wrought diamond of 
 
 1 
 
 carat 
 
 is 
 
 
 
 
 L.8 
 
 2 
 
 do. 
 
 is 
 
 2 2 
 
 X 
 
 L.8, = 
 
 32 
 
 3 
 
 do. 
 
 is 
 
 S 2 
 
 X 
 
 L.8, = 
 
 72 
 
 4 
 
 flo. 
 
 is 
 
 4 2 
 
 X 
 
 L.8, = 
 
 128 
 
 100 
 
 do. 
 
 is 
 
 100 2 
 
 X 
 
 00 
 
 II 
 
 80000, 
 
 This rule, however, is not extended to dia- 
 monds of more than 20 carats. The larger 
 ones are disposed of at prices inferior to their 
 value by that computation. The snow-white 
 diamond is most highly prized by the jewel- 
 ler. If transparent and pure, it is said to 
 be of the first water. 
 
 The carat grain is different from the Troy 
 grain. 156 carats make up the weight of 
 one oz. troy ; or 612 diamond grains are con- 
 tained in the Troy ounce. 
 
 From the high refractive pow r er of the 
 diamond, MM. Biot and Arago supposed 
 that it might contain hydrogen. Sir H. 
 Davy, from the action of potassium on it, 
 and its non- conduction of electricity, sug- 
 gested in his third Bakerian lecture that a 
 minute portion of oxygen might exist in it ; 
 and in his new experiments on the fluoric 
 compounds he threw out the idea, that it 
 might be the carbonaceous principle, com- 
 bined with some new, light, and subtle ele- 
 ment, of the oxygenous and chlorine class. 
 
 This unrivalled chemist, during his resi- 
 dence at Florence in March 1814, made 
 several experiments on the combustion of 
 the diamond and ot plumbago by means of 
 
DIA 
 
 DIA 
 
 the great lens in the cabinet of natural his- 
 toiy, the same instrument as that employed 
 in the first trials on the action of the solar 
 heat on the diamond, instituted in 1694 by 
 Cosmo III. Grand Duke of Tuscany. lie 
 subsequently made a series of researches on 
 the combustion of different kinds of charcoal 
 at Rome. His mode of investigation was 
 peculiarly elegant, and led to the most de- 
 cisive results. 
 
 He found that diamond, when strongly 
 ignited by the lens, in a thin capsule of pla- 
 tinum, perforated with many orifices, so as to 
 admit a free circulation of air, continued to 
 burn with a steady brilliant red light, visible 
 in the brightest sunshine, after it was with- 
 drawn from the focus. Some time after the 
 diamonds were removed out of the focus, 
 indeed, a wire of platina that attached them 
 to the tray was fused, though their weight was 
 only 1.84 grains. His apparatus consisted of 
 clear glass globes of the capacity of from 14 
 to 40 cubic inches, having single apertures 
 to which stop-cocks were attached. A small 
 hollow cylinder of platinum was attached to 
 one end of the stop- cock, and was mounted 
 with the little perforated capsule for con- 
 taining the diamond. When the experiment 
 was to be made, the globe containing the 
 capsule and the substance to be burned was 
 exhausted by an excellent air-pump, and 
 pure oxygen, from chlorate of potash, was 
 then introduced. The change of volume in 
 the gas after combustion was estimated by 
 means of a fine tube connected with a stop- 
 cock, adapted by a proper screw to the stop- 
 cock of the globe, and the absorption was 
 judged of by the quantity of mercury that 
 entered the tube, which afforded a measure 
 so exact, that no alteration however minute 
 could be overlooked. He had previously 
 satisfied himself that a quantity of moisture, 
 less than 1-1 00th of a grain, is rendered 
 evident by deposition on a polished surface 
 of glass ; for a piece of paper weighing one 
 grain was introduced into a tube of about 
 four cubic inches capacity, whose exterior 
 was slightly heated by a candle. A dew was 
 immediately perceptible on the inside of the 
 glass, though the paper, when weighed in a 
 balance turning with 1-1 00th of a grain, in- 
 dicated no appreciable diminution. 
 
 The diamonds were always heated to red- 
 ness before they were introduced into the 
 capsule. During their combustion, the glass 
 globe was kept cool by the application of 
 water to that part of it immediately above 
 the capsule, and where the heat was greatest. 
 
 From the results of his different experi- 
 ments, conducted with the most unexcep- 
 tionable precision, it is demonstrated, that 
 diamond affords no other substance by its 
 combustion than pure carbonic acid gas ; 
 and that the process is merely a solution of 
 
 diamond in oxygen, without any change in 
 the volume of the gas. It likewise appears, 
 that in the combustion of the different kinds 
 of charcoal, water is produced ; and that 
 from the diminution of the volume of the 
 oxygen, there is every reason to believe that 
 the water is formed by the combustion of 
 hydrogen existing in strongly ignited char- 
 coal. As the charcoal from oil of turpen- 
 tine left no residuum, no other cause but the 
 presence of hydrogen can be assigned for the 
 diminution occasioned in the volume of the 
 gas during its combustion. 
 
 The only chemical difference perceptible 
 between diamond and the purest charcoal is, 
 that the last contains a minute portion of 
 hydrogen ; but can a quantity of an ele- 
 ment, less in some cases than 1 -50,000th 
 part of the weight of the substance, occasion 
 so great a difference in physical and chemi- 
 cal characters ? The opinion of Mr Tennant, 
 that the difference depends on crystalliza- 
 tion, seems to be correct. Transparent solid 
 bodies are in general non-conductors of elec- 
 tricity ; and it is probable that the same cor- 
 puscular arrangements which give to matter 
 the power of transmitting and polarizing 
 light, are likewise connected with its relations 
 to electricity. Thus water, the hydrates of 
 the alkalis, and a number of other bodies 
 which are conductors of electricity when 
 fluid, become non-conductors in their crys- 
 tallized form. 
 
 That charcoal is more inflammable than 
 the diamond, may be explained from the 
 looseness of its texture, and from the hydro- 
 gen it contains. But the diamond appears 
 to burn in oxygen with as much facility as 
 plumbago, so that at least one distinction 
 supposed to exist between the diamond and 
 common carbonaceous substances is done 
 away by these researches. The power pos- 
 sessed by certain carbonaceous substances of 
 absorbing gases, and separating colouring 
 matters from fluids, is probably mechanical, 
 and dependent on their porous organic struc- 
 ture ; for it belongs in the highest degree 
 to vegetable and animal charcoal, and it does 
 not exist in plumbago, coak, or anthracite. 
 
 The nature of the chemical difference be- 
 tween the diamond and other carbonaceous 
 substances, may be demonstrated by igniting 
 them in chlorine, when muriatic acid is pro- 
 duced from the latter, but not the for- 
 mer. The visible acid vapour is owing to 
 the moisture present in the chlorine uniting 
 to the dry muriatic gas. But charcoal, after 
 being intensely ignited in chlorine, is not 
 altered in its conducting power or colour. 
 This circumstance is in favour of the opi- 
 nion, that the minute quantity of hydrogen 
 is not the cause of the great difference be- 
 tween the physical properties of the diamond 
 and charcoal.* 
 
DIG 
 
 DIG 
 
 It does not appear that any sum exceed- 
 ing one hundred and fifty thousand pounds 
 has been given for a diamond. 
 
 * Dichrojti. See Iolite. * 
 
 Digestion. The slow action of a solvent 
 
 upon any substance. 
 
 * Digestion. The conversion of food 
 into chyme in the stomach of animals by the 
 solvent power of the gastric juice. Some 
 interesting researches have been lately made 
 on this subject by Dr Wilson Philip and 
 Dr Prout. 
 
 Phenomena , fic. of digestion in a rabbit . — 
 A rabbit which had been kept without food 
 for twelve hours, was fed upon a mixture of 
 bran and oats. About two hours afterwards 
 it was killed, and examined immediately 
 while still warm, when the following cir- 
 cumstances were noticed : The stomach was 
 moderately distended, with a pulpy mass, 
 which consisted of the food in a minute state 
 of division, and so intimately mixed, that the 
 different articles of which it was composed 
 could be barely recognized. The digestive 
 process, however, did not appear to have 
 taken place equally throughout the mass, but 
 seemed to be confined principally to the su- 
 perficies, or where it was in contact with the 
 stomach. The smell of this mass was pecu- 
 liar, and difficult to be described. It might 
 be denominated fatuous and disagreeable. 
 On being wrapped up in a piece of linen, 
 and subjected to moderate pressure, it yield- 
 ed upwards of half a fluid ounce of an 
 opaque reddish-browm fluid, which instantly 
 reddened litmus paper very strongly. It 
 instantly coagulated milk, and, moreover, 
 seemed to possess the property of redissolv- 
 ing the curd, and converting it into a fluid, 
 very similar to itself in appearance. It w r as 
 not coagulated by heat or acids; and, in 
 short, did not exhibit any evidence of an al- 
 buminous principle. On being evaporated 
 to dryness, and burned, it yielded very copi- 
 ous traces of an alkaline muriate, with slight 
 traces of an alkaline phosphate and sul- 
 phate ; also of various earthy salts, as the 
 sulphate, phosphate, and carbonate oflime. 
 
 “ The first thing,” says Dr P. “ which 
 strikes the eye on inspecting the stomachs of 
 rabbits which have lately eaten, is, that the 
 new- is never mixed w ith the old food. The 
 former is always found in the centre sur- 
 rounded on all sides by the old food, except 
 that on the upper part betw een the new food 
 and the smaller curvature of the stomach, 
 there is sometimes little or no old food. If 
 the old and the new food are of different 
 kinds, and the animal be killed after taking 
 the latter, unless a great length of time has 
 elapsed after taking it, the line of separation 
 1 ls perfectly evident, so that the old may be 
 removed without disturbing the new food. 
 
 It appears that in proportion as the food 
 
 47 
 
 is digested, it is moved along the great cur- 
 vature, when the change in it is rendered 
 more perfect, to the pyloric portion. The 
 layer of food lying next the surface of the 
 stomach, is first digested. In proportion as 
 this undergoes the proper change, it is moved 
 on by the muscular action of the stomach, 
 and that next in turn succeeds to undergo 
 the same change. Thus a continual motion 
 is going on ; that part of the food wdiich lies 
 next the surface of the stomach passing to- 
 wards the pylorus, and the more central 
 parts approaching the surface.” 
 
 Dr Philip has remarked, that the great 
 end of the stomach is the part most usually 
 found acted upon by the digestive fluids after 
 death. 
 
 The follow'ing phenomena were observed 
 by Dr Prout : — 
 
 Comparative examination of the contents of 
 the duodena of two dogs , one of which had 
 been fed on vegetable food y the other on ani - 
 mal food only. The chymous mass from 
 vegetable food (principally bread) w'as com- 
 posed of a semi-fluid, opaque, yellowish- 
 white part, containing another portion of a 
 similar colour, but firmer consistence, mixed 
 with it. Its specific gravity was 1.056. It 
 showed no traces of a free acid, or alkali ; 
 but coagulated milk completely, when assist- 
 ed by a gentle heat. 
 
 That from animal food w r as more thick 
 and viscid than that from vegetable food, 
 and its colour was more inclined to red. Its 
 sp. gr. was 1 .022. It showed no traces of a 
 free acid or alkali, nor did it coagulate milk 
 even when assisted by the most favourable 
 circumstances. 
 
 On being subjected to analysis, these two 
 specimens w r ere found to consist of 
 
 . Chyme from Chyme from 
 
 vegetable food, animal food. 
 Water, - - 86.5 80.0 
 
 Gastric principle, united 
 
 with the alimentary 
 matters, and apparent- 
 ly constituting the 
 chyme, mixed with 
 excrementitious mat- 
 ter, 
 
 6.0 
 
 15.8 
 
 A 1 bu m i n ous m a t ter, part- 
 ly consisting of fibrin, 
 derived from the flesh 
 on which the animal 
 had been fed, 
 
 
 1.5 
 
 Biliary principle, 
 
 1.6 
 
 1.7 
 
 Vegetable gluten ? 
 
 5.0 
 
 
 Saline matters, 
 
 0.7 
 
 0.7 
 
 Insoluble residuum, 
 
 0.2 
 
 0.5 
 
 
 100.0 
 
 100.0 
 
 Very similar phenomena were observed in 
 other instances. Hut when the animal was 
 
DIP 
 
 DIS 
 
 opened at a longer period after feeding, Dr 
 Frout generally found much stronger evi- 
 dences of albuminous matter, not only in 
 the duodenum, but nearly throughout the 
 whole of the small intestines. The quanti- 
 ty, however, was generally very minute in 
 the ileum ; and where it enters the ccecuin, 
 no traces of this principle could be perceiv- 
 ed. See Sanguification.* 
 
 Digestive Salt. Muriate of potash. 
 
 Digester. The digester is an instrument 
 invented by Mr Papin about the beginning 
 of the last century. It is a strong vessel of 
 copper or iron, with a cover adapted to 
 screw on with pieces of felt or paper inter- 
 posed. A valve with a small aperture is 
 made in the cover, the stopper of which 
 valve may be more or less loaded either by 
 actual weights, or by pressure from an appa- 
 ratus on the principle of the steelyard. 
 
 The purpose of this vessel is to prevent 
 the loss of heat by evaporation. The solvent 
 power of water when heated in this vessel is 
 greatly increased. 
 
 * Diopside. A sub-species of oblique 
 
 edged augite. Its colour is greenish-white. 
 It occurs massive, disseminated, and crystal- 
 lized : 1. In low oblique four-sided prisms. 
 2. The same, truncated on the acute lateral 
 edges, bevelled on the obtuse edges, and the 
 edge of the bevelment truncated. 3. Eight- 
 sided prisms. The broader lateral planes 
 are deeply longitudinally streaked, the others 
 are smooth. Lustre shining and pearly. 
 Fracture uneven. Translucent. As hard 
 as augite. Sp. gr. 3.3. It melts with dif- 
 ficulty before the blow r -pipe. It consists of 
 57.5 silica, 18.25 magnesia, 16.5 lime, 6 
 iron and manganese. — Laugier. It is found 
 
 in the hill Ciarmetta in Piedmont; also in 
 the black rock at Mussa, near the town of 
 Ala, in veins along with epidote or pista- 
 cite, and hyacinth-red garnets. It is the 
 Alalite and Mussite of Bonvoisin.* 
 
 * Dioptase. Emerald, copper-ore.* 
 
 * Dippel’s animal oil, an oily matter obtain- 
 ed in the igneous decomposition of horns in 
 a retort. Rectified, it becomes colourless, 
 aromatic, and as light and volatile as ether. 
 It changes syrup of violets to a green, from 
 its holding a little ammonia in solution.* 
 
 * Dipyre. Schmelszstein. 
 
 Tins mineral is distinguished by tw r o char- 
 acters ; it is fusible with intumescence by 
 the blow-pipe, and it emits on coals a faint 
 phosphorescence. It is found in small 
 prisms, united in bundles, of a greyish or 
 reddish-white. These crystals are splendent, 
 hard enough to scratch glass ; their longitu- 
 dinal fracture is lamellar, and their cross frac- 
 ture conchoidal. Its sp. gr. is 2.63. The 
 primitive form appears to be the regular six- 
 sided prism. It consists of 60 silica, 24 
 alumina, 10 lime, 2 water, and 4 loss. — Vau- 
 quelin . It occurs in a white or reddish 
 
 steatite, mingled with sulphuret of iron, on 
 the right bank of the torrent of Mauleon in 
 the western Pyrenees.* 
 
 * Distillation. The vaporization and sub- 
 sequent condensation of a liquid, by means 
 of an alembic, or still and refrigeratory, or 
 of a retort and a receiver. The old distinc- 
 tions of distillatio per latus , per ascensum, 
 and per descensum , are now discarded. 
 
 Under Laboratory, a drawing and de- 
 scription of a large still of an ingenious con- 
 struction is given. The late celebrated Mr 
 Watt having ascertained, that liquids boiled 
 in vacuo at much lower temperatures than 
 under the pressure of the atmosphere, appli- 
 ed this fact to distillation ; but he seems, 
 according to Dr Black’s report of the ex- 
 periment, to have found no economy of fuel 
 in this elegant process; for the latent heat 
 of the vapour raised in vacuo , appeared to be 
 considerably greater than that raised in or- 
 dinary circumstances. Mr Henry Tritton 
 has lately contrived a very simple apparatus 
 for performing this operation in vacuo ; and 
 though no saving of fuel should be made, 
 yet superior flavour may be secured to the 
 distilled spirits and essential oils, in conse- 
 quence of the moderation of the heat. The 
 still is of the common form; but, instead of 
 being placed immediately over a fire, it is 
 immersed in a vessel containing hot water. 
 The pipe from the capital bends down and 
 terminates in a cylinder or barrel of metal, 
 plunged in a cistern of cold liquid. From 
 the bottom of this barrel, a pipe proceeds to 
 another of somewhat larger dimensions, which 
 is surrounded with cold water, and furnished 
 at its top with an exhausting syringe. 
 
 The pipe from the bottom of the still, for 
 emptying it, and that from the bottom of 
 each barrel, are provided with stop-cocks. 
 Hence, on exhausting the air, the liquid will 
 distil rapidly, when the body of the alembic 
 is surrounded with boiling water. W hen it 
 is wished to withdraw a portion of the dis- 
 tilled liquor, the stop-cock at the bottom of 
 the first receiver is shut, so that on opening 
 that at the second, in order to empty it, the 
 vacuum is maintained in the still. It is 
 evident that the first receiver may be sur- 
 rounded with a portion of the liquid to be 
 distilled, as I have already explained in 
 treating of alcohol. By this means the ut- 
 most economy of fuel may be observed. 
 
 The term distillation, is often applied in 
 this country, to the whole process of con- 
 verting malt or other saccharine matter, into 
 spirits or alcohol. 
 
 In making malt whisky, one part ot bruis- 
 ed malt, w ith from four to nine parts of bar- 
 ley-meal, and a proportion of seeds ot oats, 
 corresponding to that of the raw grain, is in- 
 fused in a mash-tun of cast iron, with from 
 12 to 13 wine gallons of water, at 150° 
 Fahr. for every bushel of the mixed farina- 
 
 4 
 
DIS 
 
 DIS 
 
 ceous matter. The agitation then given by 
 manual labour or machinery to break down 
 and equally diffuse the lumps of meal, con- 
 stitutes the process of mashing. This opera- 
 tion continues two hours or upwards, accord- 
 ing to the proportion of unmalted barley ; 
 during which the temperature is kept up, by 
 the affusion of seven or eight additional gal- 
 lons of water, a few degrees under the boil- 
 ing temperature. The infusion termed wort, 
 having become progressively sweeter, is al- 
 lowed to settle for two hours, and is run off 
 from the top, to the amount of about one- 
 third the bulk of water employed. About 
 eight gallons of more water, a little under 
 200° F. is now admitted to the ^residuum, 
 infused for nearly half an hour with agita- 
 tion, and then left to subside for an hour 
 and a half, when it is drawn off. Some- 
 times a third affusion of boiling water, equal 
 to the first quantity, is made, and this infu- 
 sion is generally reserved, to be poured on 
 new farina ; or it is concentrated by boiling, 
 and added to the former liquors. In Scot- 
 land, the distiller is supposed by law, to extract 
 per cent 14 gallons of spirits, sp. gr. 0.91917, 
 or 1 to 10 over proof, and must pay duty 
 accordingly. Hence, his wort must have 
 at least the strength of 55 \ pounds of sac- 
 charine matter, per barrel, previous to letting 
 it down into the fermenting tun ; and the 
 law does not permit it to be stronger than 
 75 pounds. Every gallon of the above spi- 
 rits contains 4.6 pounds of alcohol, sp. gr. 
 0.825, and requires for its production the 
 complete decomposition of twice 4,6 pounds 
 of sugar = 9.2 pounds. But since we can 
 never count on decomposing above four- 
 fifths of the saccharine matter of wort, we 
 must add one-fifth to 9.2 pounds, when we 
 shall have 11^ pounds for the weight of 
 saccharine matter, equivalent in practice to 
 one gallon of the legal spirits. Hence, the 
 distiller is compelled to raise the strength of 
 his wort up to nearly 70 pounds per barrel, 
 as indicated by his saccharometer. This con- 
 centration is to be regretted, as it materially 
 injures the flavour of the spirit. The thinner 
 worts of the Dutch, give a decided supe- 
 riority to their alcohols. At 62 pounds per 
 barrel, we should have about 12 per cent of 
 spirits of the legal standard. 
 
 lo prevent acetification, it is necessary to 
 cool the worts down to the proper fermenting 
 temperature of 70°, or 65°, as rapidly as 
 possible. Hence, they are pumped imme- 
 diately from the mash-tun into extensive 
 wooden troughs, two or three inches deep, 
 exposed in open sheds to the cool air; or 
 they are made to traverse the convolutions of 
 a pipe, immersed in cold w'ater. The wort 
 being now run into the fermenting tun, 
 yeast is introduced and added in nearly equal 
 successive portions, during three days ; 
 amounting in all to about one gallon, for 
 
 every tw r o bushels of farinaceous matter. 
 The temperature rises in three or four days, 
 to its maximum of 80° ; and at the end of 
 10 or 12 days the fermentation is complet- 
 ed ; the tuns being closed up during the last 
 half of the period. The distillers do not 
 collect the yeast from their fermenting tuns, 
 but allow it to fall down, on the supposition 
 that it enhances the quantity of alcohol. 
 
 The specific gravity of the liquid has now 
 probably sunk from 1.060, that of wort, equi- 
 valent to about 56 pounds per barrel, to 
 1 .005, or 1.000; and consists of alcohol mix- 
 ed with undecomposed saccharine and fari- 
 naceous matter. The larger the proportion 
 of alcohol, the more sugar will be preserved 
 unchanged ; and hence the impolicy of the 
 present laws on distillation. 
 
 Some years ago, when the manufacturer 
 paid a duty for the season, merely according 
 to the measurement of his still, it was his in- 
 terest to work it oft' with the utmost possible 
 speed. Hence the form of still and furnace 
 described under Laboratory, was contrived 
 by some ingenious Scotch distillers, by which 
 means they could w ork off in less than four 
 minutes, and recharge, an 80 gallon still ; an 
 operation which had a few years before 
 lasted several days, and which the vigilant 
 framers of the law', after recent investigation, 
 deemed possible only in eight minutes. The 
 W'aste of fuel was how’ever great. The du- 
 ties being now levied on the product of spi- 
 rit, the above contest against time no longer 
 exists. It has been supposed, but I think 
 on insufficient grounds, that quick distilla- 
 tion injures the flavour of spirits. This I 
 believe to depend, almost entirely, on the 
 mode of conducting the previous fermenta- 
 tion. 
 
 In distilling off the spirit from the fer- 
 mented w'ort or wash, a hydrometer is used 
 to ascertain its progressive diminution of 
 strength, and when it acquires a certain 
 weakness, the process is stopped by opening 
 the stop-cock of the pipe, which issues from 
 the bottom of the still, and the spent wash 
 is removed. There is generally introduced 
 into the still, a bit of soap, whose oily prin- 
 ciple spreading on the surface of the boiling 
 liquor, breaks the large bubbles, and of 
 course checks the tendency to froth up. The 
 spirits of the first distillation, called in Scot- 
 land low wines, are about 0.975 sp. gravity, 
 and contain nearly 20 per cent of alcohol of 
 0.82 5. Redistillation of the low wines , or 
 
 doubling , gives at first the fiery spirit called 
 first-shot, milky and crude, from the pre- 
 sence of a little oil. This portion is return- 
 ed into the low w ines. What flows next is 
 clear spirit, and is received in one vessel, till 
 its density diminish to a certain degree. 
 The remaining spirituous liquor, called 
 faints, is mixed with low wines, and subject- 
 ed to another distillation, 
 
 2 B 
 
DIS 
 
 DOL 
 
 ilie manufacturer is hindered bv law 
 liom sending out ot his distillery, stronger 
 spirits than 1 to 10 over hydrometer proof, 
 equivalent to sp. gr. 0.90917 ; or weaker spi- 
 rits than 1 in 6 under proof, whose sp. gr. 
 is 0.9385. 
 
 The following is said to be the Dutch 
 mode of making Geneva: — 
 
 One cwt. of barley malt and two cwts. of 
 rye meal are mashed with 4G0 gallons of 
 water, heated to 1G2° F. After th eflarime 
 have been infused for a sufficient time, cold 
 water is added, till the wort becomes equiva- 
 lent to 45 pounds of saccharine matter per 
 barrel. Into a vessel of 500 gallons capa- 
 city, the wort is now put at the temperature 
 of 80°, with half a gallon of yeast. The 
 fermentation instantly begins, and is finish- 
 ed in 48 hours, during which the heat rises 
 to 90°. The wash, not reduced lower than 
 1 2 or 1 5 pounds per barrel, is put into the still 
 along with the grains. Three distillations 
 are required ; and at the last, a few juniper ber- 
 ries and hops are introduced to communicate 
 flavour. The attenuation of 45 pounds in 
 the wort, to only 15 in the wash, shews that 
 the fermentation is here very imperfect and 
 uneconomical ; as indeed we might infer from 
 the small proportion of yeast, and the preci- 
 pitancy of the process of fermentation. On 
 the other hand, the very large proportion of 
 porter yeast in a corrupting state, used by 
 the Scotch distillers, eannot fail to injure the 
 flavour of their spirits. 
 
 Rum is obtained from the fermentation 
 of the coarsest sugar and molasses in the 
 West Indies, dissolved in water in the pro- 
 portion of nearly a pound to the gallon. 
 The yeast is procured chiefly from the rum 
 wort. The preceding details give sufficient 
 instruction for the conduct of this modifica- 
 tion of the process. 
 
 Sykes’ hydrometer is now universally used 
 in the collection of the spirit revenue in 
 Great Britain. It consists, first of a flat 
 stem, 3.4 inches long, which is divided on 
 both sides into 1 1 equal parts, each of which 
 is subdivided into two, the scale being num- 
 bered from 0 to 11. This stem is soldered 
 into a brass ball 1.6 inch in diameter, into 
 the under part of which is fixed a small conical 
 stem 1.13 inch long, at whose end is a pear- 
 shaped loaded bulb, half an inch in diameter. 
 The whole instrument, which is made of brass, 
 is 6.7 inches long. The instrument is accom- 
 panied with 8 circular weights, numbered 
 10, 20, 30, 40, 50, 60, 70, 80, and another 
 weight of the form of a parallelopiped. Each 
 of the circular weights is cut into its centre, 
 so that it can be placed on the inferior conical 
 stem, and slid down to the bulb; but in 
 consequence of the enlargement of the cone, 
 they cannot slip oft* at the bottom, but must 
 be drawn up to the thin part for this pur- 
 
 pose. I he square weight of the form of a 
 parallelopiped, has a square notch in one of 
 its sides, by which it can be placed on the 
 summit of the stem. In using this instru- 
 ment, it is immersed in the spirit, and press- 
 ed down by the hand to O, till the whole di- 
 vided part of the stem be wet. The force of 
 the hand required to sink it, will be a guide 
 in selecting the proper weight. Having 
 taken one of the circular weights, which is 
 necessary for this purpose, it is slipped on 
 the conical stem. The instrument is again 
 immersed and pressed down as before to O, 
 and is then allowed to rise and settle, at any 
 point of the scale. The eye is then brought 
 to the level of the surface of the spirit, and 
 the part of the stem cut by the surface, as 
 seen JYom below , is marked. The number 
 thus indicated by the stem is added to the 
 number of the weight employed, and with 
 this sum at the side, and the temperature of 
 the spirits at the top, the strength per cent is 
 found in a table of 6 quarto pages. “ The 
 strength is expressed in numbers denoting 
 the excess or deficiency per cent of proof- 
 spirit in any sample, and the number itself 
 (having its decimal point removed two places 
 to the left) becomes a factor, whereby tho 
 gauged content of a cask or vessel of such 
 spirit being multiplied, and the product be- 
 ing added to the gauged content, if over 
 proof, or deducted from it if under proof, 
 the result will be the actual quantity of 
 proof spirit contained in such cask or ves- 
 sel.”* 
 
 * Disthene. See Cyanite.* 
 
 * Distinct Concretions. A term in 
 Mineralogy.* 
 
 Docimastic Art. This name is given to 
 the art of assaying. See Assay, Blow-fife, 
 Analysis, and the several metals. 
 
 * Dolomite. Of this calcareo- magnesian 
 carbonate, we have three sub-species. 
 
 1 . Dolomite, of which there are two kinds. 
 
 § 1st, Granular Dolomite. 
 
 White granular. It occurs massive, and 
 in fine granular distinct concretions, loosely 
 aggregated. Lustre glimmering and pearly. 
 Fracture in the large, imperfect slaty. Faint- 
 ly translucent. As hard as fluor. Brittle, 
 Sp. gr. 2.85. It effervesces feebly with 
 acids. Phosphorescent on heated iron, or 
 by friction. Its constituents are 46.5 car- 
 bonate of magnesia, 52.08 carbonate of lime, 
 0.25 oxide of manganese, and 0.5 oxide of 
 iron. Klaproth. Beds of dolomite, con- 
 taining tremolite, occur in the island of Iona, 
 in the mountain group of St Gothard, in the 
 Appenines, and in Carinthia. A beautiful 
 white variety used by ancient sculptors, is 
 found in the Isle of Ten^dos. Jamc%n. 
 
 The flexible variety was first noticed in 
 the Borghese palace at Rome ; but the other 
 varieties of dolomite, and also common gra- 
 
DR A 
 
 DYE 
 
 nular limestone, may be rendered flexible, 
 by exposing them in thin and long slabs to 
 a heat of 480° Fahr. for 6 hours. 
 
 § 2d, Brown Dolomite , or magnesian lime* 
 stone of Tennant. 
 
 Colour, yellowish- grey and yellowish- 
 brown. Massive, and in minute granular 
 concretions. Lustre internally glistening. 
 Fracture splintery. Translucent on the 
 edges. Harder than calcareous spar. Brit- 
 tle. Sp. gr. of crystals, 2.8. It dissolves 
 slowly, and with feeble effervescence ; and 
 when calcined, it is long in re-absorbing car- 
 bonic acid from the air. Its constituents 
 are, lime 29.5, magnesia 20.3, carbonic acid 
 47.2. Alumina and iron 0.8. Tennant. 
 In the north of England it occurs in beds of 
 considerable thickness, and great extent, rest- 
 ing on the Newcastle coal formation. In the 
 Isle of Man, it occurs in a limestone which 
 rests on grey-wacke. It occurs in trap-rocks 
 in Fifeshire. When laid on land after being 
 calcined, it prevents vegetation, unless the 
 quantity be small. 
 
 To the preceding variety we must refer a 
 flexible dolomite found near Tinmouth Castle. 
 It is yellowish-grey, passing into cream-yel- 
 low. Massive. Dull. Fracture earthy. 
 Opaque. Yields readily to the knife. In 
 thin plates, very flexible. Sp. gr. 2.54; but 
 the stone is porous. It dissolves in acids as 
 readily as common carbonate of lime. Its 
 constituents are said to be 62 carbonate of 
 lime, and 36 carbonate of magnesia. When 
 made moderately dry, it loses its flexibility; 
 but when either very moist or very dry, it is 
 very flexible. 
 
 2d, Columnar Dolomite . Colour pale grey- 
 ish-white. Massive, and in thin prismatic 
 concretions. Cleavage imperfect. Fracture 
 uneven. Lustre vitreous, inclining to pearly. 
 Breaks into acicular fragments. Feebly 
 translucent. Brittle. Sp. gr. 2.76. Its 
 constituents are 51 carbonate of lime, 47 
 carbonate of magnesia, 1 carbonated hydrate 
 of iron. It occurs in serpentine in Russia. 
 
 5d, Compact Dolomite , or Gurhoflte. Co- 
 lour snow-white. Massive. Dull. Frac- 
 ture flat conchoidal. Slightly translucent on 
 the edges. Semi-hard. Difficultly frangi- 
 ble. Sp. gr. 2.76, When pulverized, it 
 dissolves with effervescence in hot nitric acid. 
 It consists of 70.5 carbonate of lime, and 
 29.5 carbonate of magnesia. It occurs in 
 veins in serpentine rocks, near Gurhoff, in 
 Lower Austria.* 
 
 * Draco- Mitigatus. Calomel. See Mer- 
 cury.* 
 
 * Dragon’s Blood. A brittle dark red 
 coloured resin, imported from the East Indies, 
 the product of pterocarpus draco , and dra- 
 C(ena draco. It is insoluble in water, but 
 soluble in a great measure in alcohol. The 
 solution imparts a beautiful red stain to hot 
 
 marble. It dissolves in oils. It contains a 
 little benzoic acid.* 
 
 * Drawing Slate. Black chalk. Co- 
 lour greyish- black. Massive. Lustre of 
 
 the principal fracture, glimmering ; of the 
 cross fracture, dull. Fracture of the former 
 6laty, of the latter, fine earthy. Opaque. 
 It writes. Streak same colour, and glis- 
 tening. Very soft. Sectile. Easily fran- 
 gible. It adheres slightly to the tongue. 
 Feels fine, but meagre. Sp. gr. 2. 11. It 
 is infusible. Its constituents are, silica 64.06, 
 alumina 11, carbon 11, water 7.2, iron 2.75. 
 It occurs in beds in primitive and transition 
 clay-slate, also in secondary formations. It 
 is found in the coal formation of Scotland, 
 and in most countries. It is used in crayon- 
 painting. The trace of bituminous shale 
 is brownish and irregular; that of black 
 chalk is regular and black. The best kind 
 is found in Spain, Italy, and France.* 
 
 Ductility. That property or texture of 
 bodies, which renders it practicable to draw 
 them out in length, while their thickness is 
 diminished without any actual fracture of 
 their parts. This term is almost exclusively 
 applied to metals. 
 
 Most authors confound the words malle- 
 ability, laminability, and ductility together, 
 and use them in a loose indiscriminate way ; 
 but they are very different. Malleability is 
 the property of a body which enlarges one 
 or two of its three dimensions, by a blow or 
 pressure very suddenly applied. Lamina- 
 bility belongs to bodies extensible in dimen- 
 sion by a gradually applied pressure : And 
 ductility is properly to be attributed to such 
 bodies as can be rendered longer and thinner 
 by drawing them through a hole of less area 
 than the transverse section of the body so 
 drawn. 
 
 Dyeing. r Ihe art of dyeing consists in 
 fixing upon cloths of various kinds any co- 
 lour which may be required, in such a man- 
 ner as that they shall not be easily altered 
 by those agents, to which the cloth will most 
 probably be exposed. 
 
 As there can be no cause by 'which any 
 colouring matter can adhere to any cloth, 
 except an attraction subsisting between the 
 two substances, it must follow^, that there 
 will be few tingeing matters capable of in- 
 delibly or strongly attaching themselves by 
 simple application. 
 
 Dyeing is therefore a chemical art. 
 
 The most remarkable general fact in the 
 art of dyeing, consists in the different de- 
 grees of facility, with which animal and 
 vegetable substances attract and retain co- 
 louring matter, or rather the degree of faci- 
 lity with which the dyer finds he can tinge 
 them with any intended colour. The chief 
 materials of stuff to be dyed are wool, silk, 
 cotton, and linen, of which the former two 
 
DYE 
 
 DYE 
 
 are more easily dyed than the latter. This 
 has been usually attributed to their greater 
 attraction to the tingeing matter. 
 
 Wool is naturally so much disposed to 
 combine with colouring matter, that it re- 
 quires but little preparation for the imme- 
 diate processes of dyeing ; nothing more 
 being required than to cleanse it, by scour- 
 ing, from a fatty substance, called the yolk, 
 which is contained in the fleece. For this 
 purpose an alkaline liquor is necessary ; but 
 as alkalis injure the texture of the wool, a 
 very weak solution may be used. For if 
 more alkali were present than is sufficient 
 to convert the yolk into soap, it would at- 
 tack the wool itself. Futrid urine is there- 
 fore generally used, as being cheap, and 
 containing a volatile alkali, which, uniting 
 with the grease, renders it soluble in water. 
 
 Silk, when taken from the cocoon, is co- 
 vered with a kind of varnish, which, be- 
 cause it does not easily yield either to wa- 
 ter or alcohol, is usually said to be soluble 
 in neither. It is therefore usual to boil the 
 silk wuth an alkali, to disengage this matter. 
 Much care is necessary in this operation, 
 because the silk itself is easily corroded or 
 discoloured. Fine soap is commonly used, 
 but even this is said to be detrimental ; and 
 the white China silk, which is supposed to 
 be prepared without soap, has a lustre supe- 
 rior to that of Europe. Silk loses about 
 one-fourth of its weight by being deprived 
 of its varnish. See Bleaching. 
 
 The intention of the previous prepara- 
 tions seems to be of two kinds. The first to 
 render the stuff or material to be dyed as 
 clear as possible, in order that the aqueous 
 fluid to be afterward applied, may be im- 
 bibed, and its contents adhere to the minute 
 internal surfaces. The second is, that the 
 stuff* may be rendered whiter and more ca- 
 pable of reflecting the light, and consequent- 
 ly enabling the colouring matter to exhibit 
 more brilliant tints. 
 
 Some of the preparations, however, though 
 considered merely as preparative, do really 
 constitute part of the dyeing processes them- 
 selves. Tn many instances a material is ap- 
 plied to the stuff, to which it adheres ; and 
 when another suitable material is applied, 
 the result is some colour desired. Thus we 
 might dye a piece of cotton black, by im- 
 mersing it in ink ; but the colour would be 
 neither good nor durable, because the parti- 
 cles of precipitated matter, formed of the 
 oxide of iron and acid of galls, are already 
 concreted in masses too gross either to enter 
 tlie cotton, or to adhere to it with any consi- 
 derable degree of strength. But if the cot- 
 ton be soaked in an infusion of galls, then 
 dried, and afterward immersed in a solution 
 of sulphate of iron (or other ferruginous 
 salt), the acid of galls being every- where dif- 
 fused though the body of the cotton, will re- 
 
 ceive the particles of oxide of iron, at the 
 very instant of their transition from the fluid, 
 or dissolved to the precipitated or solid state ; 
 by which means a perfect covering of the 
 black inky matter will be applied in close 
 contact with the surface of the most minute 
 fibres of the cotton. This dye w ill therefore 
 not only be more intense, but likewise more 
 adherent and durable. 
 
 The French dyers, and after them the 
 English, have given the name of mordant 
 to those substances which are previously ap- 
 plied to piece goods, in order that they may 
 afterward take a required tinge or dye. 
 
 It is evident, that if the mordant be uni- 
 versally applied over the whole of a piece of 
 goods, and this be afterward immersed in 
 the dye, it w ill receive a tinge over all its 
 surface ; but if it be applied only in parts, 
 the dye will strike in those parts only. The 
 former process constitutes the art of dyeing, 
 properly so called ; and the latter, the art of 
 printing wmollens, cottons, or linens, called 
 calico-printing. 
 
 In the art of printing piece goods, the 
 mordant is usually mixed with gum or 
 starch, and applied by means of blocks or 
 wooden engravings in relief, or from copper 
 plates, and the colours are brought out by 
 immersion in vessels filled with suitable 
 compositions Dyers call the latter fluid 
 the bath. The art of printing affords many 
 processes, in which the effect of mordants, 
 both simple and compound, is exhibited. 
 The following is taken from Berthollet. 
 
 The mordant employed for linens, intend- 
 ed to receive different shades of red, is pre- 
 pared by dissolving in eight pounds of hot 
 w T ater, three pounds of alum, and one pound 
 of acetate of lead, to which two ounces of 
 potash, and afterward two ounces of pow'- 
 dered chalk, are added. 
 
 In this mixture the sulphuric acid com- 
 bines with the lead of the acetate and falls 
 down, because insoluble, while the argilla- 
 ceous earth of the alum unites w ith the ace- 
 tic acid disengaged from the acetate of lead. 
 The mordant therefore consists of an argil- 
 laceous acetic salt, and the small quantities 
 of alkali and chalk serve to neutralize any 
 disengaged acid, which might be contained 
 in the liquid. 
 
 Several advantages are obtained by thus 
 changing the acid of the alum. First, the 
 argillaceous earth is more easily disengaged 
 from the acetic acid, in the subsequent pro- 
 cesses, than it would have been from the sul- 
 phuric. Secondly, this w r cak acid does less 
 harm when it comes to be disengaged by 
 depriving it of its earth. And thirdly, the 
 acetate of alumina not being crystallizable 
 like the sulphate, does not separate or cur- 
 dle by drying on the face of the blocks tor 
 printing, when it is mixed with gum or 
 starch. 
 
DYE 
 
 DYE 
 
 When the design has been impressed by 
 transferring the mordant from the face of 
 the wooden blocks to the cloth, it is then 
 put into a bath of madder, with proper at- 
 tention, that the whole shall be equally ex- 
 posed to this fluid. Here the piece becomes 
 of a red colour, but deeper in those places 
 where the mordant was applied. For some 
 of the argillaceous earth had before quitted 
 the acetic acid, to combine with the cloth ; 
 and this serves as an intermedium to fix the 
 colouring matter of the madder, in the same 
 manner as the acid of galls, in the former 
 instance, fixed the particles of oxide of iron. 
 With the piece in this state, the calico-prin- 
 ter has only therefore to avail himself of the 
 difference between a fixed and a fugitive 
 colour. He therefore boils the piece with 
 bran, and spreads it on the grass. The 
 fecula of the bran takes up part of the co- 
 lour, and the action of the sun and air ren- 
 ders more of it combinable with the same 
 substance. 
 
 In other cases, the elective attraction of 
 the stuff to be dyed has a more marked 
 agency. A very common mordant for 
 woollens is made by dissolving alum and 
 tartar together ; neither of which is decom- 
 posed, but may be recovered by crystalliza- 
 tion upon evaporating the liquor. Wool is 
 found to be capable of decomposing a solu- 
 tion of alum, and combining with its earth ; 
 but it seems as if the presence of disengaged 
 sulphuric acid served to injure the wool, 
 which is rendered harsh by this method of 
 treatment, though cottons and linens are 
 not, which have less attraction for the earth. 
 Wool also decomposes the alum, in a mix- 
 ture of alum and tartar; but in this case 
 there can be no disengagement of sulphuric 
 acid, as it is immediately neutralized by the 
 alkali of the tartar* 
 
 Metallic oxides have so great an attraction 
 for many colouring substances, that they 
 quit the acids in which they were dissolved, 
 and are precipitated in combination with 
 
 them. These oxides are also found by expe- 
 riment to be strongly disposed to combine 
 with animal Substances ; whence in many 
 instances they serve as mordants, or the me- 
 dium of union between the colouring parti- 
 cles and animal bodies. 
 
 I he colours which the compounds of me- 
 tallic oxides and colouring particles assume, 
 
 then, are the product of the colour peculiar 
 to the colouring particles, and of that pecu- 
 liar to the metallic oxide. 
 
 * The following are the dye-stuffs used by 
 the calico-printers for producing fast colours. 
 I lie mordants are thickened with gum, or 
 calcined starch, and applied with the block, 
 roller, plates, or pencil. 
 
 1. Black. The cloth is impregnated with 
 acetate of iron (iron liquor), and dyed in a 
 luitli of madder and logwood. 
 
 2. Purple . The preceding mordant of 
 iron, diluted ; with the same dyeing bath. 
 
 5 . Crimson . The mordant for purple, 
 
 united with a portion of acetate of alumina, 
 or red mordant, and the above bath. 
 
 4. Bed. Acetate of alumina is the mor- 
 dant, (see Alumina), and madder is the dye- 
 stuff. 
 
 5. Pale red of different shades. The pre- 
 ceding mordant diluted with water, and a 
 weak madder bath. 
 
 6. Brown or Pompadour. A mixed mor- 
 dant, containing a somewhat larger propor- 
 tion of the red than of the black ; and the 
 dye of madder. 
 
 7. Orange. The red mordant ; and a 
 bath first of madder, and then of quercitron. 
 
 8. Yellow. A strong red mordant ; and the 
 quercitron bath, whose temperature should 
 be considerably under the boiling point of 
 water. 
 
 9. Blue . Indigo, rendered soluble and 
 greenish-yellow coloured, by potash and or- 
 piment. It recovers its blue colour, by ex- 
 posure to air, and thereby also fixes firmly 
 on the cloth. An indigo vat is also made, 
 with that blue substance, diffused in water 
 with quicklime and copperas. These sub- 
 stances are supposed to deoxidize indigo, 
 and at the same time to render it soluble. 
 
 Golden-dye. The cloth is immersed al- 
 ternately in a solution of copperas and lime 
 water. The protoxide of iron precipitated 
 on the fibre, soon passes by absorption of 
 atmospherical oxygen, into the golden-co- 
 lourod deutoxide. 
 
 Buff. The preceding substances, in a more 
 dilute state. 
 
 Blue vat , in which white spots are left on 
 a blue ground of cloth, is made, by applying 
 to these points a paste composed of a solu- 
 tion of sulphate of copper and pipe-clay ; 
 and after they are dried, immersing it stretch- 
 ed on frames for a definite number of mi- 
 nutes, in the yellowish- green vat, of l part 
 of indigo, 2 of copperas, and 2 of lime, with 
 water. 
 
 Green. Cloth dyed blue, and well washed, 
 is imbued with the aluminous acetate, dried, 
 and subjected to the quercitron bath. 
 
 In the above cases, the cloth, after receiv- 
 ing the mordant paste, is dried, and put 
 through a mixture of cow dung and warm 
 water. It is then put into the dyeing vat 
 or copper. 
 
 Fugitive Colours. 
 
 All the above colours are given, by mak- 
 ing decoctions of the different colouring 
 woods ; and receive the slight degree of 
 fixity they possess, as well as great brilliancy, 
 in consequence of their combination or ad- 
 mixture with the nitro- muriate of tin. 
 
 1. Red is frequently made from Brazil 
 and Peachwood. 
 
EAR 
 
 EGG 
 
 2. Slack. A Strong extract of galls, and 
 deuto-nitrate of iron. 
 
 3. Purple, Extract of logwood and the 
 deuto- nitrate. 
 
 4. Yello w. Extract of quercitron bark, or 
 French berries, and the tin solution. 
 
 5. lilue, Prussian blue and solution of 
 tin. 
 
 Fugitive colours are thickened with gum- 
 tragacanth, which leaves the cloth in a softer 
 state than gum- Senegal ; the goods being 
 sometimes sent to market without being 
 washed.* 
 
 For the modes of using the different arti- 
 cles used in dyeing, see them, under their 
 respective names in the order of the alphabet. 
 
 ^ AGLE-SFONE. A clay ironstone. 
 
 — i • Earths. Fifteen years ago, few sub- 
 stances seemed more likely to retain a per- 
 manent place in chemical arrangements, than 
 the solid and refractory earths, which com- 
 pose the crust of the globe. Analysis had 
 shewn, that the various stony or pulverulent 
 masses, which form our mountains, valleys, 
 and plains, might be considered as resulting 
 from the combination or intermixture, in 
 various numbers and proportions, of nine 
 primitive earths, to which the following 
 names were given : 
 
 1. Barytes. 2. Strontites. 5. Lime. 4. 
 Magnesia. 5. Alumina, or clay. 6. Silica. 
 7. Glucina. 8. Zirconia. 9. Yttria. 
 
 Alkalis, acids, metallic ores, and native 
 metals, were supposed to be of an entirely 
 dissimilar constitution. 
 
 The brilliant discovery by Sir H. Davy 
 in 1808, of the metallic bases of potash, soda, 
 barytes, strontites, and lime, subverted the 
 ancient ideas regarding the earths, and 
 taught us to regard them as all belonging, 
 by most probable analogies, to the metallic 
 class. According to an ingenious sugges- 
 tion of Mr Smithson, silica, however, ought 
 to be ranked with acids, since it has the 
 power in native mineral compounds of neu- 
 tralizing the alkaline earths, as well as the 
 common metallic oxides. But as this pro- 
 perty is also possessed by many metallic 
 oxides, it can afford no evidence against the 
 metallic nature of the siliceous basis. Alu- 
 mina, by the experiments of Ehrman, may 
 be made to saturate lime, producing a glass ; 
 and the triple compounds of magnesia, alu- 
 mina,- and lime, are perfectly neutral, in 
 porcelain. We might therefore refer alu- 
 mina as well as silica, to the same class with 
 the oxides of antimony, arsenic, chromium, 
 columbium, molybdenum, titanium, and 
 tungsten. Alumina, however, bears to silica, 
 the same relation that oxide of antimony 
 does to that of arsenic ; the antecedent pair 
 acting the part of bases, while the consequent 
 pair act only as acids. The compound of the 
 fluoric principle with silica is of too myste- 
 rious a nature to be employed in this dis- 
 cussion. The almost universal function 
 which silica enjoys of saturating the alkaline 
 
 oxides in the native earthy minerals, 1*9 exhi- 
 bited, in a very striking manner, in Mr Al- 
 lan’s valuable Svnoptic Tables. From his 
 fifth to his fifteenth table of analyses, the co- 
 lumn of silica is always complete, whatever 
 deficiency or variation may occur in the co- 
 lumns of the earthy bases. At least, only a 
 very few exceptions need be made for the 
 oriental gems, which consist of strongly ag- 
 gregated alumina. 
 
 To the above nine earthy substances, Ber- 
 zelius has lately added a tenth, which he 
 calls thorina. We shall enter at present into 
 no further discussion concerning their place 
 in a systematic arrangement. Whatever may 
 be the revolutions of chemical nomenclature, 
 mankind will never cease to consider as 
 Earths, those solid bodies composing the 
 mineral 6trata, which are incombustible, co- 
 lourless, not convertible into metals, by all 
 the ordinary methods of reduction, or when 
 reduced by scientific refinements, possessing 
 but an evanescent metallic existence, and 
 which either alone, or at least when combin- 
 ed with carbonic acid, are insipid and inso- 
 luble in water. * 
 
 Earthen- ware. See Pottery. 
 
 Eau de Luce consists chiefly of the essen- 
 tial oil of amber and the volatile alkali. 
 
 Echini. Calcareous petrefactions of the 
 echinus, or sea hedgehog. 
 
 Effervescence is the commotion produc- 
 ed in fluids by some part of the mass sud- 
 denly taking the elastic form, and escaping 
 in numerous bubbles. 
 
 Efflorescence is the effect which takes 
 place when bodies spontaneously become 
 converted into a dry powder. It is almost 
 alwnvs occasioned by the loss of the w ater of 
 crystallization in saline bodies. 
 
 Eggs. The eggs of hens, and of birds in 
 general, are composed of several distinct 
 substances. 1. The shell, or external coat- 
 ing, which is composed of carbonate of lime 
 .72, phosphate of lime .2, gelatine .3. 1 he 
 
 remaining .23 are perhaps w ater. 2. A thin 
 white and strong membrane, possessing the 
 usual characters of animal substances. 5. The 
 white of the egg, for which see Albumen. 
 4. The yolk, w hich appears to consist of aa 
 oil of the nature of fat oils, united with a 
 
EL A 
 
 ELE 
 
 portion of serous matter, sufficient to render 
 it diffusible in cold water, in the form of an 
 emulsion, and concrescible by heat. Yolk 
 of egg is used as the medium for rendering 
 resins and oils diffusible in water. 
 
 * Eisenrahm. Red and brown ; the 
 scaly iron ore, and scaly manganese ore.* 
 
 * Elain. The oily principle of solid fats, 
 so named by its discoverer, M. Chevreul. 
 Chevreul dissolves the tallow in very pure hot 
 alcohol, separates the stearin by crystallization, 
 and then procures the elain , by evaporation of 
 the spirit. Rut M. Bracoimot has adopted 
 a simpler and probably a more exact method. 
 By squeezing tallow between the folds of 
 porous paper, the elain soaks into it, while 
 the stearin remains. The paper being then 
 soaked in water, and pressed, yields up its 
 oily impregnation. Elain has very much 
 the appearance and properties of vegetable 
 oil. It is liquid at the temperature of 60°. 
 Its smell and colour are derived from the 
 solid fats from which it is extracted. 
 
 Human elain is yellow, without odour. 
 Specific gravity 0.9 IS. 
 
 Elain of sheep ; colourless, a faint smell. 
 Sp. gr. 0.915. 
 
 Elain of ox ; colourless, and almost with- 
 out odour. Sp. gr. 0.915. 
 
 Ela'in of hog ; do. do. 0.9 1 5. 
 
 Elain of jaguar ; lemon colour, odorous. 
 0.914. 
 
 Elain of goose ; light lemon colour, little 
 odour. 0.929. 
 
 Solubility in alcohol of sp. gr. 0.7952. 
 
 Human ela'in; 11.1 gr. by 9 gr. at the 
 boiling point. 
 
 Elain of sheep ; 5.79 gr. by 5 gr. at do. 
 
 Ela'in of ox ; 5.8 gr. by 4. 7 gr. at do. 
 
 Ela'in of hog ; 1 1 .1 gr. by 9.0 gr. at do. 
 
 Ela'in of jaguar ; 3.35 gr. by 2.7 1 gr. at do. 
 
 Elain of goose ; 11. 1 gr. by 9.0 gr. at do. 
 
 Ela’in of the fat of ox, extracted by alcohol, 
 yields, by the action of potash, 
 
 Of saponified fat, 92 .6 parts. 
 
 Of soluble matter, 7.4 
 
 Those of the other fats yield, 
 
 Of saponified fat, 89 
 Of soluble matter, 11. 
 
 In M. Chevreul’s 7th memoir on fats, 
 published in the 7th vol. of the Ann. de 
 Chimie et Phys., he gives the following as 
 the composition of the oleates from sperma- 
 ceti : — 
 
 Oleic acid, 
 
 100 
 
 Barytes, 
 
 51.24 
 
 Strontian, 
 
 23. 1 8 
 
 Oxide of lead, 
 
 100.00 
 
 If we suppose the last a suboleate, the 
 equivalent of this oleic acid will be 28. The 
 oil or oleic acid of the delpliinus globiccps 
 is remarkably soluble in cold alcohol, 100 
 parts of which of sp. gr. 0.795, at 68°, dis- 
 solve J 23 of the oil. When that oil is freed 
 
 by cold from a crystallizable matter, 100 
 parts of alcohol, sp. gr. 0.820, dissolve 149.4 
 of oil at the atmospheric temperature. It 
 was slightly acid by the test of litmus, which 
 he ascribes to the presence of an aqueous 
 fluid. See Fat.* 
 
 * Elaolite. A sub-species of pyramidal 
 felspar. Colours, duck- brown, inclining to 
 green, and flesh-red, inclining to grey or 
 brown. Massive, and in granular concre- 
 tions. Lustre shining and resinous. Frac- 
 ture imperfect conchoidal. Faintly translu- 
 cent. Hardness as felspar. Easily frangi- 
 ble. Sp. gr. 2.6. Its powder forms a jelly 
 with acids. Before the blow-pipe, it melts 
 into a milk-white enamel. Its constitu- 
 ents are 46.5 silica, 30.25 alumina, 0.75 
 lime, 1 8 potash, 1 oxide of iron, and 2 water. 
 Klaproth. The blue is found at Launvig, 
 and the red at Stavern and Friedrickswarn, 
 both in the rock named zircon syenite. The 
 pale blue has an opalescence, like the cat’s 
 eye, which occasions it to be cut into email 
 ornaments. It is caWedfetlstein by Werner, 
 from its resinous nature. — Jameson.* 
 
 * Elecampane. From the root of the 
 inula hellenium, or elecampane, Rose first 
 extracted the peculiar vegetable principle 
 called inulin. M. Funke has since given 
 the following as the analysis of elecampane 
 root : — 
 
 A crystallizable volatile oil, 
 
 Inulin, 
 
 Extractive, 
 
 Acetic acid, 
 
 A crystallizable resin, 
 
 Gluten, 
 
 A fibrous matter (ligneous).* 
 
 * Electricity. The phenomena display- 
 ed by rubbing a piece of amber, constitute 
 the first physical fact recorded in the history 
 of science. Thales of Miletus, founder of 
 the Ionic school, ascribed its mysterious 
 power of attracting and repelling light bo- 
 dies to an inherent soul or essence, which, 
 awakened by friction, went forth and brought 
 back the small particles floating around. In 
 times near to our own, the same hypothesis 
 was resorted to, by the honourable Robert 
 Boyle. From electron, the Greek name of 
 amber, has arisen the science of electricity, 
 which investigates the attractions and repul- 
 sions, the emission of light, and explosions, 
 which are produced, not only by the friction 
 of vitreous, resinous, and metallic surfaces, 
 but by the heating, cooling, evaporation, 
 and mutual contact, of a vast number of 
 bodies. 
 
 1. General statement of electrical pheno- 
 mena. 
 
 If we rub, with a dry hand or a silk hand- 
 kerchief, a glass tube, and then approach it 
 to bits of paper or cotton, to feathers, or 
 which is better, gold leaf, it will first attract 
 these bodies, and then repel them. If the 
 
ELE 
 
 ELE 
 
 tube be held parallel to a table on which 
 they have been laid, an electrical dance will 
 be performed. If to the farther end of the 
 tube we hang a brass ball, by a thread of 
 linen, hemp, or a metallic wire, the ball will 
 participate with the rubbed tube, in its mys- 
 terious powers. But if the ball be suspend- 
 ed by a cord of silk, worsted, or hair, or by 
 a rod of glass, wax, or pitch, the attractive 
 and repulsive virtue will not pass into it. 
 
 When the atmosphere is dry, if we take in 
 one hand a rod of glass, and in the other a 
 stick of sealing-wax, and after having rubbed 
 them against silk or worsted, approach one 
 of them to a bit of gold leaf floating in the 
 air, it will first attract and then repel it. 
 While the film of gold is seen to avoid the 
 contact of the rod which it has touched, if 
 we bring the other rod into its neighbour- 
 hood, attraction will immediately ensue; and 
 this alternate attraction and repulsion may 
 be strikingly displayed by placing the two 
 excited rods at a small distance asunder, 
 with the gold leaf between. 
 
 If we suspend close together, by silk 
 threads, two cylinders of rush- pith, and 
 touch their lower ends with either the rub- 
 bed wax or glass, the pieces of pith will in- 
 stantly recede from each other at a consider- 
 able angle. If we now merely approach to 
 the bottom of the diverging cylinders, the 
 rod with which they had been touched, their 
 divergence will increase ; but if we approach 
 the other rod, they will instantly collapse 
 through their whole extent. When the rods 
 are rubbed in the dark, a lambent light seems 
 diffused over them, and a pungent spark 
 will pass into a knuckle brought near them. 
 If the person who makes these experiments 
 happens to stand on a cake of wax, or a stool 
 with glass feet, then, on rubbing the glass 
 tube, he will acquire the above attractive 
 and repulsive powers ; but the light bodies 
 repelled by the tube, will be attracted by his 
 body, and vice versa. Hence we see, that 
 the rubbing body acquires electrical proper- 
 ties, dissimilar to those acquired by the sub- 
 stances rubbed. 
 
 Such is a sketch of the elementary pheno- 
 mena of electricity. The science, in its 
 modern augmentation, seems to comprehend 
 almost every change of the corpuscular 
 world, however minute and mysterious, as 
 well as the long recognized and magnificent 
 meteors of the atmosphere. Let us now take 
 a methodical view of them, as far as the 
 limits of our work will permit. We shall 
 consider electrical phenomena under four 
 heads : — 
 
 1st, Of the Excitement of Electricity, or 
 the various means by which the electrical 
 equilibrium is disturbed. 
 
 2d, Of the Two Electricities. 
 
 3d, Of the Distribution of Electricity. 
 4th, Of the Voltaic Battery and its Ef- 
 
 fects : calorific, or igniting ; and decompos- 
 ing, or the chemical agencies of electricitv. 
 
 Concerning the nature of the electrical 
 essence, we are equally in the dark as con- 
 cerning the nature of caloric. The pheno- 
 mena may be referred in both cases, either 
 to a peculiar fluid, whose particles are en- 
 dowed with innate idio-repulsive powers, or 
 to a peculiar affection of the molecules of 
 common matter. 
 
 I. Of Electrical Excitement. 
 
 1. The mutual friction of all solids, whe- 
 ther similar or dissimilar, and of many fluids 
 against solids, will invariably excite electri- 
 cal phenomena, provided one of the bodies 
 be of such a nature as to obstruct the speedy 
 diffusion of the electrical virtue. Hence we 
 must commence with a list of electrical con- 
 ductors and non-conductors. 
 
 I st, The following substances conduct or 
 favour the rapid distribution of electricity. 
 Those at the head of the list possess a con- 
 ducting power greater than that of water, in 
 the proportion of three millions to one. 
 
 1. *Copper 
 
 2. Silver 
 
 3. Gold 
 
 4. Iron 
 
 5. Tin 
 
 6. Lead 
 
 7. Zinc 
 
 8. Platinum 
 
 9. Charcoal 
 
 10. Plumbago 
 
 1 1 . Strong acids 
 
 12. Soot and lamp- 
 black 
 
 1 3. Metallic ores 
 
 14. Metallic oxides 
 
 15. Dilute acids 
 
 16. Saline solutions 
 
 17. Animal fluids 
 
 1 8. Sea water 
 
 19. Water 
 
 20. Ice and snow 
 
 above 0° 
 
 21. Living vegetables 
 
 22. Living animals 
 
 23. Flame 
 
 24. Smoke 
 
 25. Vapour 
 
 26. Salts 
 
 27. Rarefied air 
 
 28. Dry earths 
 
 29. Massive minerals. 
 
 2d, The following 
 non-conductors, in the 
 ing power : 
 
 1. Shell lac 
 
 2. Amber 
 
 3. Resins 
 
 4. Sulphur 
 
 5. Wax 
 
 6. Asphaltum 
 
 7. Glass, and all vi- 
 trified bodies, 
 comprehending 
 diamond and 
 crystallized trans- 
 parent minerals. 
 
 8. Raw silk 
 
 9. Bleached silk 
 
 10. Dyed silk 
 
 11. Wool, hair, and 
 feathers 
 
 1 2. Dry gases 
 
 1 3. Dry paper, parch- 
 ment, and 
 leather 
 
 is a list of electrical 
 order of their insulat- 
 
 14. Baked wood, and 
 
 dried vegetables 
 
 15. Porcelain 
 
 16. Marble 
 
 17. Massive minerals, 
 
 non- metallic 
 
 18. Camphor 
 
 1 9. Caoutchouc 
 
 20. Lycopodium 
 
 2 1 . Dry chalk and 
 
 lime 
 
 22. Phosphorus 
 
 23. Ice below 0° of 
 Fahr. 
 
 24. Oils, of which the 
 densest are best 
 
 25. Dry metallic ox- 
 ides, including 
 fused alkaline 
 and earthy hy- 
 drate*. 
 
ELE 
 
 ELE 
 
 The general arrangement of the above lists 
 is tolerably correct, though it is probable that 
 phosphorus, when freed from adhering mois- 
 ture, would stand higher among insulators. 
 
 All material substances have been usually 
 divided into two classes ; of electrics, and 
 non-electrics. But this distinction is ground- 
 less, and calculated to mislead. Every sub- 
 stance is an electric, or capable by friction of 
 exhibiting electrical phenomena. Thus, it 
 we take any of the bodies in the first list, 
 which are commonly called non-electrics, for 
 instance a copper ball, and insulating it by a 
 rod of any convenient solid in the second 
 list, if we rub the ball with a piece of silk or 
 worsted, we shall find it to become electrical, 
 It will attract and repel light bodies, and 
 will give lucid sparks to a finger which ap- 
 proaches it. To account for these appear- 
 ances, it has been said that the electrical 
 equilibrium which constitutes the common 
 state of matter, is disturbed by the friction ; 
 and that one of the two bodies attracts to 
 itself a surcharge of the electrical fluid, 
 while the other remains in a deficient state, 
 whence the terms of positive and negative, 
 or plus and minus, have arisen. Many of 
 the appearances, however, are reconciled with 
 difficulty to a mere excess or deficiency of 
 one fluid ; and hence the hypothesis of a 
 compound fluid, susceptible of decomposition 
 by friction and other means, has been intro- 
 duced. The resulting fluids are necessarily 
 co-existent, the one appearing on the body 
 rubbed, and the other on the rubber ; but 
 since the one is most usually evolved on the 
 surface of glass, and the other on that of resins, 
 the first has been called the vitreous, and the 
 second the resinous electricity. These two 
 fluids, corresponding to the positive and ne- 
 gative of Franklin, by their reunion produce 
 a species of reciprocal neutralization, and 
 electrical repose. Some recent investigations 
 of that profound physico-geometer M. Pois- 
 son, render the second explanation the less im- 
 probable of the two. Let us always bear in 
 mind, however, that the hypothetical thread 
 which we employ at present, to tie together 
 the scattered facts of electricity, is probably 
 very different from the chain of nature. 
 
 There seems to be no physical quality com- 
 mon to the conductors, or to the non-con- 
 ductors. The crystalline arrangement al- 
 ways introduces non-conducting qualities, 
 more or less perfect, if we exclude the me- 
 tals. Thus carbon, in the pulverulent or 
 fibrous form, is an excellent conductor, but 
 crystallized in diamond, it becomes an insu- 
 lator. r l he same difference exists between 
 water and ice ; and, as is said, between pound- 
 ed and compact glass. If pounded glass be 
 indeed a conductor, it must, from my expe- 
 riments, be so in a very imperfect degree. 
 Glass, resins, and fats, which in the solid 
 
 state are non-conductors, become conductors 
 on being melted. 
 
 On the evolution of electricity by friction, 
 is founded the construction of our common 
 electrical machines. It was supposed at one 
 time, that their action was connected with 
 the oxidizement of the amalgam, which is 
 usually applied to the face of the rubber. 
 But Sir H. Davy having mounted a small 
 machine in a glass vessel, in such a manner 
 that it could be made to revolve in any 
 species of gas, found that it was active in 
 hydrogen, and more active in carbonic acid, 
 than even in the atmosphere. Indeed if we 
 recollect that the friction of surfaces of glass, 
 silk, or sealing-wax, is sufficient to produce 
 electrical appearances, we cannot suppose 
 oxidizement of metal to be essential to their 
 production. If we even impel a current of 
 air, or a minute stream of pure mercury, on 
 a plate of dry glass, electrical excitement 
 will result. 
 
 The electrical phenomena excited by fric- 
 tion, are generally so energetic, as to require 
 nothing but bits of any light matter for their 
 exhibition. When we have to detect the dis- 
 turbance of the electrical equilibrium, occa- 
 sioned by other and feebler causes, more re- 
 fined electroscopic means are required. The 
 most delicate of simple electroscopes con- 
 sist of two oblong narrow slips of gold leaf, 
 suspended from the centre of the brass cap 
 of a glass cylinder, about 2 inches diameter 
 and 6 inches long. The bottom of the cy- 
 linder should rest in a metallic sole ; from 
 which, on the opposite sides, two narrow 
 slips of tin-foil should raise up the inner sur- 
 face of the glass, to the level of the middle 
 of the pendent slips of gold leaf. Cou- * 
 lomb’s electroscope, which acts by the torsion 
 of a fibre of the silk worm, suspending in a 
 glass case a horizontal needle of shell lac, 
 terminated in a little disc of gilt paper, is 
 still more sensible, and is much employed by 
 the Parisian philosophers. Aided by either 
 of these instruments, we can observe the ex- 
 citement of electrical phenomena in the fol- 
 lowing cases, independent of friction. 
 
 2. In the fusion of inflammable bodies. 
 If we pour melted sulphur into an insulated 
 metallic cup, we shall find after it concretes, 
 that the sulphur and cup w ill be both elec- 
 trified ; the former with the vitreous, the lat- 
 ter with the resinous electricity ; or some- 
 times reversely. But Messrs Van Marum 
 and Troostwyck, from a series of experi- 
 ments which they made on a number of 
 bodies, w'ere led to conclude that the electri- 
 city was produced in such cases as the above, 
 either by the friction from change of bulk, 
 when the melted matter concretes, or from 
 the friction which the electrical bodies under- 
 go, when they spread upon the surfaces of 
 other bodies, upon which they are poured in 
 
ELE 
 
 ELE 
 
 the liquid state. When glacial phosphoric 
 acid congeals, and when calomel concretes in 
 sublimation, electrical phenomena are pro- 
 duced. The experiments of Henly on the 
 electricity excited during the concretion of 
 melted chocolate, do not seem easily explica- 
 ble on the principle of friction. When it is 
 cooled in the tin pans into which it is first 
 received, the electricity is strong, and con- 
 tinues for some time after it is removed. 
 When it is again melted and allowed to 
 cool, the electrical virtue is restored, but not 
 to its former strength. After the third or 
 fourth fusion, the electricity becomes ex- 
 tremely weak. When the chocolate is mixed 
 with a little olive oil before it is poured 
 out of the pan, it then becomes strongly 
 electrical. Now in so far as friction is con- 
 cerned, we should have the electrical pheno- 
 mena as decided at the fourth fusion, as the 
 first; and the presence of oil ought to lessen 
 the effect, as it diminishes the friction. It is 
 highly probable that the act of crystallization 
 always induces a chang-e of the electrical 
 equilibrium ; as the crystalline structure 
 changes the electrical relations in general. 
 
 3. Electricity produced by evaporation. 
 
 If on the cap of the gold leaf electroscope 
 
 we place a small metallic cup, containing a 
 little water, and drop into it a red-hot cin- 
 der, the gold leaves will instantly diverge to 
 a very considerable angle. Or if we insulate 
 a hot crucible of iron, copper, silver, or por- 
 celain, and pour into it a few drops of water, 
 alcohol, or ether, on connecting the crucible 
 with an electroscope, electrical phenomena 
 will appear. 
 
 4. Electricity produced by disengagement 
 of gas. 
 
 If into a platinum cup, resting on the top 
 of the electroscope, we put a little dilute sul- 
 phuric acid, and then throw in some iron 
 filings, or chalk, the gold leaves will diverge, 
 as the effervescence becomes active. The 
 same thing is producible with nitric acid and 
 copper filings. 
 
 5. Electricity produced by disruption of a 
 solid body. 
 
 If we suddenly tear asunder plates of 
 mica, break across a stick of sealing-wax, 
 cleave up a piece of dry and warm wood, or 
 scrape its surface with window glass, or 
 finally cause a bit of unannealed glass, such 
 as a Prince Rupert’s drop, to fly asunder by 
 snapping off a bit of its tail, the electrical 
 equilibrium will be disturbed. Most of these 
 cases may, however, be probably referred to 
 friction among the moleculae. To the same 
 head we may also refer the electricity excited 
 by sifting various powders and metallic filings 
 through a metallic sieve, or by dropping 
 them on insulated plates. 
 
 6. Electricity excited by change of tem- 
 perature. 
 
 M. Ilaiiy made the important discovery, 
 
 that the property of exhibiting electrical phe- 
 nomena by heat, belongs to those crystals 
 only whose forms are not symmetrical ; that 
 is to say, of which one extremity or side does 
 not correspond with the opposite. Thus, 
 for example, the variety of tourmaline which 
 he calls isogone , a prismatic crystal of nine 
 sides, terminated at one end with a three- 
 sided, and at the other with a six-sided pyra- 
 mid, when exposed to the temperature of 
 108° Fahr. shews no sign of electricity. 
 But if we plunge it for some minutes into 
 boiling water, and taking it out with small 
 forceps, by the middle of the prism, present 
 it to the cap of the electroscope, or to a pith 
 ball pendulum, already charged w ith a known 
 electricity, we shall find it will attract it w ith 
 one of its poles, and repel with the other. 
 The three-sided pyramid possesses the re- 
 sinous, and the six-sided the vitreous elec- 
 tricity. Although an elevation of tempera- 
 ture be necessary to develope this property, 
 it is not needed for its maintenance. It will 
 continue electrical for six hours after its tem- 
 perature has fallen to the former point, espe- 
 cially if it be laid on an insulating support. 
 In fact it loses its electricity, more slowly 
 than a piece of glass, in similar circum- 
 stances. 
 
 This property of attracting light bodies 
 when heated, was recognized by the ancients 
 in tourmaline, which was probably their lyn- 
 curium. The Dutch in Ceylon gave it the 
 name of Aschentrikker , from its attracting the 
 ashes, when a piece of it was laid near the 
 fire. It appears that a heat above 21L'°, im- 
 pairs its electrical activity ; and that it is 
 some time before it recovers its pristine vir- 
 tue. When the tourmaline is large, it is 
 capable of emitting flashes of electrical light. 
 The Brazilian or Siberian topaz exhibits 
 the same phenomena by being slightly heat- 
 ed. The topazes of Saxony, and the blue 
 topaz of Aberdeenshire, are electrical only 
 by friction. Boracite, mesotype, and crys- 
 tallized calamine, possess similar properties 
 of becoming electrical with heat. 
 
 7. Electricity produced by contact of dis- 
 similar bodies. If we take two flat discs, 
 one of silver or copper, and another of zinc, 
 each two or three inches diameter, furnished 
 with glass handles, and bring them into mo- 
 mentary contact by their flat surfaces, we 
 shall find, on separating them, that they are 
 both electrified. If we touch a disc of sul- 
 phur gently heated, with the insulated cop- 
 per plate, the electrical effects will be still 
 more striking. Acid crystals, touched with 
 metallic plates, yield electrical phenomena. 
 Finally, crystals of oxalic acid, brought into 
 contact with dry quicklime, develope electri- 
 city. On the excitation of electricity by con- 
 tact of dissimilar chemical bodies, is founded 
 the principle of galvanic action, and the con- 
 struction of the voltaic battery. Of this 
 
ELE 
 
 ELE 
 
 admirable apparatus we shall treat in the 
 sequel. 
 
 1 1. Of the two Electricities. 
 
 We have already stated, that the two elec- 
 tricities are always connate and simultaneous. 
 If they result from the decomposition of a 
 quiescent neutral compound fluid, we can 
 
 easily see that this co-existence is inevitable. 
 
 0 
 
 Hence also we can understand, how any 
 body by friction, may be made to exhibit 
 either of the two electricities, according to 
 the nature of the rubber. The only ex- 
 ception is the back of a living cat, which 
 gives vitreous electricity, with every rubber 
 hitherto tried. To know the species of elec- 
 tricity evolved, it is merely necessary to com- 
 municate beforehand, to the slips of gold 
 leaf, a known electricity, either from excited 
 glass or sealing wax. If they be divergent 
 with the former, then the approach of a body 
 similarly electrified, will augment the di- 
 vergence, but that of one oppositely electri- 
 fied will cause their collapse. 
 
 The following is a table of several sub- 
 stances which acquire the vitreous electricity, 
 when we rub them with those which follow 
 them in the list ; and the resinous electricity, 
 when rubbed with those that precede them. 
 
 The skin of a cat. 
 
 Polished or smooth glass. 
 
 Woollen stuff' or worsted. 
 
 Feathers. 
 
 Dry wood. 
 
 Paper. 
 
 Silk. 
 
 X^ac. 
 
 Roughened glass. 
 
 No visible relation can be pointed out be- 
 tween the nature or constitution of the sub- 
 stances, and the species of electricity, which 
 is developed by their mutual friction. The 
 only general law among the phenomena, is, 
 that the rubbing, and the rubbed body, al- 
 ways acquire opposite electricities. Sulphur 
 is vitreously electrified when rubbed with 
 every metal except lead, and resinously with 
 lead and every other kind of rubber. Resin- 
 ous bodies, rubbed against each other, ac- 
 quire alternately the vitreous and resinous 
 electricity ; but, rubbed against all other 
 bodies, they become resinously electrical. 
 
 bite silk acquires vitreous electricity with 
 black silk, metals, and black cloth ; and 
 resinous with paper, the human hand, hair, 
 und weasel’s skin. Black silk becomes 
 vitreously electrical with sealing-wax ; but 
 resinously with hare’s, weasel’s, and ferret’s 
 skins ; with brass, silver, iron, human hand, 
 and wdiite silk. Woollen cloth is strongly 
 vitreous w'ith zinc and bismuth, moderately 
 so with silver, copper, lead, and specular iron. 
 It is resinous with platina, gold, tin, anti- 
 mony, grey copper, sulphuret of copper, bi- 
 sulphuret of copper, sulphurets of silver, an- 
 timony, and iron. When two ribbons of 
 
 equal surface are excited by drawing one 
 lengthwise over a part of the other ; that 
 which has suffered friction in its whole 
 length, becomes vitreously, and the other, re- 
 sinously electrical. Dry air impelled on 
 glass becomes resinously electrical, and leaves 
 the glass in the opposite state. Silk stuff’s, 
 agitated in the atmosphere with a rapid mo- 
 tion, always take the resinous electricity, 
 while the air becomes vitreously electrified. 
 A ribbon of white silk, rubbed against a 
 well dyed black one, affords alw r ays marks 
 of vitreous electricity, but if the black silk be 
 much worn, and the white ribbon be heated, 
 it will yield signs of resinous electricity, and, 
 on cooling, it will again exhibit marks of 
 the vitreous. The general result which was 
 deduced by M. Coulomb, from his very 
 numerous and exact experiments on this 
 curious subject, is the following:. — 
 
 When the surfaces of two bodies are rub- 
 bed together, that whose component parts 
 recede least from each other, or elevate least 
 from their natural position of repose, appear, 
 in consequence, more disposed to assume the 
 vitreous electricity ; this tendency augments 
 if the surface experiences a transient com- 
 pression. Reciprocally, that surface whose 
 particles deviate most from their ordinary 
 position by the violence of the other, or by 
 any cause whatever, is, for that reason, more 
 disposed to take the resinous condition. 
 This tendency increases if the surface un- 
 dergo a real dilatation. The stronger is this 
 opposition of circumstances, the more en- 
 ergetic is the development of electricity, on 
 the two surfaces. It grow r s feebler in pro- 
 portion as their state becomes more similar. 
 Perfect equality would nullify the pheno- 
 mena, provided it could exist. Thus, when 
 a dry animal or vegetable substance is rub- 
 bed against a rough metallic surface, it ex- 
 hibits signs of resinous electricity. In this 
 case, its parts are forcibly separated. When, 
 on the other hand, it is rubbed on a polished 
 metal, which scarcely affects its surface, or 
 merely compresses the particles, it either af- 
 fords no evidence of electricity, or it exhibits 
 the vitreous kind. Ileat, by dilating the 
 pores, acts on the surfaces of bodies, as n 
 coarser rubber would do. It disposes them 
 to take the resinous electricity. Thus also 
 new black silk, strongly dyed, being rubbed 
 against a ribbon of white silk, takes always 
 the resinous electricity. But when the 
 black stuff' is w'orn, and the colour faded, if 
 we open the pores of the white ribbon by 
 heat, this acquires in its turn a greater tend- 
 ency to the resinous electricity than the black 
 silk, and, consequently, makes it vitreous. 
 This disposition vanishes, as might be ex- 
 pected, with the accidental cause that pro- 
 duced it, and the wdiite ribbon, on becoming 
 cold, re-acquires the vitreous electricity. 
 The black dye produces on wool the same 
 
ELE 
 
 ELE 
 
 effect as on silk. A white ribbon, rubbed 
 against white woollen stuff, gives always 
 signs of resinous electricity; but, against 
 wool dyed black, it affords signs of the vitre- 
 ous electricity. I have entered somewhat 
 minutely into the detail of the apparently 
 trifling causes which give birth to the one or 
 the other electricity, as they may tend to 
 throw some light on the electricities evolved 
 among chemical bodies by friction or simple 
 contact. It has been supposed, indeed, that 
 uncombined acids, alkalis, and metals, are 
 naturally and constantly in an electrized con- 
 dition, the first resinously, the second and 
 third vitreously. But of this position, there 
 is neither probability nor evidence. The 
 electricity produced by their contact, on an 
 extensive surface, with other bodies, is evi- 
 dently a disturbance of the pre-existing 
 equilibrium. A wire connected with the 
 most delicate electroscope of torsion, which 
 moves through 90° with a force of less than 
 1-1 00,000th of a grain, will indicate no elec- 
 tricity, when made to touch the most energe- 
 tic acid or alkaline body. 
 
 In describing the two electricities, we 
 must not omit the interesting observations of 
 Ehrman. There are substances of the im- 
 perfect conductor class, which are capable of 
 receiving only one kind of electricity, when 
 made to form links in the voltaic chain. M. 
 Ehrman styled them unipolar bodies. Per- 
 fectly dry soap, and the flame of phosphorus, 
 when connected with the two extremities of 
 the voltaic apparatus, and with the ground, 
 discharge only the resinous electricity. The 
 flames of alcohol, hydrogen, wax and oil, 
 discharge, under like circumstances, only the 
 vitreous electricity. All these bodies, how- 
 ever, when connected with only one pole of 
 
 the pile, and with the ground, destroy the 
 divergence of the leaves of the electroscope 
 attached to that pole. To render these re- 
 sults manifest, insulate in drv weather a 
 battery of about, 200 pairs of plates. Con- 
 nect with each extreme pole, the cap of a 
 gold leaf electroscope, by a moveable wire. 
 When either electroscope is brought in con- 
 tact with soap communicating with the 
 ground, the slight divergence of the gold 
 slips ceases. But, when the soap is con- 
 nected with both electroscopes, and also with 
 the ground, the divergence of the leaves of 
 the electroscope, attached to the zinc end or 
 vitreously electrified pole, will continue, while 
 the leaves of the other electroscope will col- 
 lapse. The inverse order of effects occurs, 
 or the zinc electroscope collapses, when the 
 flame of a taper is connected with both elec- 
 troscopes, and with the ground. 
 
 Mr Braude, in an ingenious paper pub- 
 lished in the Phil. Trans, for 1814, has en- 
 deavoured to explain the curious phenomena, 
 with regard to flames, in another way. As 
 some chemical bodies are supposed by him 
 to be naturally in the resinous, and others in 
 the positive electrical state, he supposes that 
 the positive flame will be attracted and neu- 
 tralize the negative polarity, while the ne- 
 gative flame will operate a similar restoration 
 of the equilibrum at the positive pole. To 
 determine the truth of this hypothesis, he 
 placed the flames of various bodies between 
 two insulated brass spheres, containing each 
 a delicate thermometer. His first experi- 
 ment verified Mr Cuthbertson’s observation, 
 that the flame of a candle communicates its 
 heat chiefly to the negative ball, both being 
 feebly electrified by a cylindrical machine of 
 Nairne’s construction. 
 
 Flames attracted by the 
 
 Positive Ball. Negative Ball. 
 
 Phosphuretted hydrogen, slightly. Olefiant gas. 
 
 Carbonic oxide in a small stream, doubtful. Sulphuretted hydrogen, slightly ; its sulpbur- 
 Ditto in large stream. ous acid vapour passed off' to the positive 
 
 The acid from the flame of sulphur. 
 
 Flame and acid fumes of phosphorus. 
 Stream of muriatic acid gas, shewn by coat 
 ing the balls with litmus paper. 
 
 Stream of nitrous acid. 
 
 Vapour of benzoic acid. 
 
 Ditto of amber. 
 
 4 ‘ The flame of oil, wax,” Ac. says Mr 
 Brande, “ must be considered as consisting 
 chiefly of those bodies in a state of vapour ; 
 and their natural electricities being positive, 
 it is obvious, that when connected with the 
 positive pole of the battery, and with a gold 
 
 ball. 
 
 Arsenuretted hydrogen; its arsenious acid 
 passed feebly to the other ball. 
 
 Hydrogen, result doubtful from equality of 
 attraction. 
 
 Flame of carburet of sulphur ; its acid fumes 
 passed to the positive. 
 
 Flame and alkaline fumes of potassium. 
 Flame of benzoic acid. 
 
 Flame of camphor. 
 
 Flame of resins. 
 
 Flame of amber. 
 
 leaf electrometer, the leaves will continue to 
 diverge; but when applied to the negative 
 pole, that electrical state will be annihilated 
 by the inherent positive energy of the flame, 
 and consequently the leaves of the negative 
 electrometer will not diverge. On the oilier 
 
ELE 
 
 ELE 
 
 hand, the flame of phosphorus is negatively 
 unipolar. Now it has been shewn that this 
 flame, (owing probably to the rapidity with 
 which it is forming a powerful acid, by com- 
 bination with a large quantity of oxygen), is 
 attracted by the positively electrified surface, 
 and consequently that it is itself negative, so 
 that it would transmit negative electricity to 
 the electrometer, but would annihilate the 
 negative power, and thus appear as an in- 
 sulator under the particular circumstances 
 which M. Ehrman has described.” I shall 
 not stop to investigate the justness of these 
 ingenious conclusions, Ihey do not affect 
 the unipolarity of dry soap; which on Mr 
 Brande’s theory of that of flames, should be 
 naturally and permanently in the state of 
 positive electricity; which we know it not 
 to be. 
 
 III. Of' the Distribution of Electricity. 
 
 Under this head we shall be able to arrange 
 several important phenomena, which, by their 
 disjunction, authors have frequently rendered 
 complex and difficult of comprehension. We 
 shall treat in the first place, of the distribu- 
 tion of either electricity, insulated in one 
 body, and in a system of bodies in contact ; 
 in the second place, the distribution of elec- 
 tricity in a system of contiguous bodies, not 
 in contact. 
 
 1. If we communicate electricity to an in- 
 sulated metallic sphere, we shall find the 
 whole electric power diffused over its sur- 
 face, and the particles in its interior, abso- 
 lutely devoid of the least electric virtue. Let 
 the ball of iron or brass have a bole of about 
 an inch diameter, reaching to its centre. Then 
 on touching the centre, with a metallic sphe- 
 rule attached to the end of a needle of lac, 
 and instantly applying it to a delicate electro- 
 scope, we shall perceive no sign of electricity 
 whatever. If the spherule, however, touch the 
 outer edge of the hole, or the surface of the 
 globe at any point, it will acquire a very 
 manifest electricity. Hence, if we apply for 
 a moment to the surface of an electrified 24 
 pound shot, two hemispherical cups of tin- 
 foil, furnished with insulating handles, we 
 shall find that the whole electrical virtue has 
 passed into the cups, whose weight may not 
 equal the ten-thousandth part of that of the 
 ball. This distribution is totally independent 
 of the nature of the substance, and is deduci- 
 ble from the law discovered by Coulomb, that 
 electrical attractions and repulsions, are in- 
 versely proportional to the squares of the dis- 
 tances. 
 
 Jf the body be spherical, the exterior elec- 
 trical stratum, which always coincides with the 
 surface of the body, will be the same with 
 the thin stratum in its interior. If the pro- 
 posed spheroid be an ellipsoid, the inner sur- 
 face of the electrical stratum, will be also a 
 concentric and similar ellipsoid, for it is de- 
 monstrated, that an elliptical stratum, whose 
 
 surfaces are thus concentric and similar, ex- 
 ercises no action on a point placed in its in- 
 terior. The thickness of the layer in each of 
 its points, is found generally determined by 
 this construction. It hence results, that this 
 thickness is greatest at the summit of the 
 greater axis, and least at the summit of the 
 smaller. The thicknesses corresponding to 
 the different summits, are to each other, as 
 the lengths of their respective axes. 
 
 2. Were the atmosphere, and the glass sup- 
 port, perfect non-conductors, the above distri- 
 bution would continue till some other body 
 was brought near to, or in contact with, the 
 ball. But the surface of even lackered glass, 
 yields slowly to the idio-repulsive power of the 
 electrical fluid ; and the atmosphere, partly by 
 its aqueous particles, and partly by its own 
 feebly conducting power, continually robs 
 the globe of its electricity. The immediate 
 aerial envelope no sooner acquires electric 
 impregnation, than it recedes, and is replaced 
 by a new sphere of gaseous particles. By 
 this intestine aerial movement of repulsion 
 and attraction, the ball, in a short time, loses 
 its excess of vitreous or resinous electricity, 
 and resumes the neutral state. By placing 
 it in the centre of a dry glass receiver, the 
 period of electrization may be prolonged, 
 but, sooner or later, the electric equilibrium 
 is restored between it, and the surrounding 
 matter. 
 
 3. If we bring into contact with the above 
 electrized ball, an unelectrified one of the 
 same bulk, but of a very different weight, 
 we shall find an equal distribution to take 
 place between them. An insulated disc or 
 spherule applied to the surface of each, will 
 be capable of affecting a graduated electro- 
 meter of torsion, to the same degree. We 
 thus perceive that bodies do not act on elec- 
 tricity, by any species of elective attraction or 
 affinity. They must be regarded merely as 
 vessels, in which this power is distributed, 
 agreeable to the laws of mechanics. 
 
 When the above globes are separated, 
 their electricities diffuse themselves uniform- 
 ly about them, and the quantities are found 
 equal when the surfaces are so. But if the 
 surfaces be unequal in any given ratio, it 
 then happens that the quantity of electricity 
 varies in a different ratio, which is less than 
 that of the surfaces. Thus Coulomb ascer- 
 tained, that when the surface of the smaller 
 globe was nearly one-fifteenth of that of the 
 larger, its quantity of electric fluid was one- 
 eleventh. The following is his general table 
 of results : — 
 
 Surface of sphere. 
 
 1 
 
 4 
 
 16 
 
 Density in little sphere, 
 whose surface = 1. 
 
 1 
 
 1.08 
 
 1.30 
 
 64 1.65 
 
 Infinite, less than 2.00 
 
 Do. calculated by M. Poisson, 1.65 
 
ELE 
 
 ELE 
 
 The difference therefore can never amount 
 to two. He placed two globes, each of two 
 inches diameter, in a line with a globe of 
 eight inches diameter ; the two smaller ones 
 being in contact, and one of them with the 
 larger. He found that the quantity of elec- 
 tricity of the smaller globe, most distant from 
 the greater, was to that of the intermediate, 
 as 2.54 to 1. Four globes of two inches 
 being placed in a row, successively in contact 
 with each other, and with a globe of eight 
 inches diameter, the ratio of the quantities of 
 electricity taken by the small globe, farthest 
 from the large one, and that nearest it, was 
 found to be 3.4 to 1. Having placed 24 
 globes, each of two inches diameter, in a like 
 series with the larger globe, Coulomb com- 
 pared the 24th little globe, that is to say, the 
 last in the row, with others in the same row, 
 and the results were as follows : — 
 
 24th to the 23d as 1.49 to 1 
 24th to the 1 2th as 1.7 to 1 
 24th to the 10th as 2,1 to 1 
 24th to the 1st 
 which was in contact 
 with the large globe, as 3.72 to 1 
 24 th to that of 
 
 the large globe, as 2,16 to 1, 
 
 When tw o electrified spheres, of equal size 
 in contact, are examined as to the state of the 
 electricity on the different points of their 
 surfaces, we have the following relations : -re- 
 position of the points Patio of the second thick,, 
 compared. ness to the first. 
 
 90° and 20° 
 
 insensible 
 
 90 
 
 30 
 
 0.2083 
 
 90 
 
 60 
 
 0.7994 
 
 90 
 
 90 
 
 1.0000 
 
 90 
 
 180 
 
 1.0576 
 
 If the diameters of the two globes be as 2 
 
 to 1. 
 
 90° and 30° 
 
 insensible 
 
 90 
 
 60 
 
 0.5882 
 
 90 
 
 90 
 
 1.0000 
 
 90 
 
 180 
 
 1.3333 
 
 That in 
 
 ordinary cases, 
 
 electricity is 
 
 fined on the surfaces of bodies, not merely 
 by the non-conducting faculty ol the air, but 
 by a species of mechanical pressure which air 
 exercises, becomes evident, when we lessen 
 the density of the air by exhaustion. I hough 
 the conducting aerial particles are thus great- 
 ly diminished in number, rendering the in- 
 sulation apparently more complete, yet the 
 electric pow r er now emanates with vast rapi- 
 dity, from the electrized ball, in visible corus- 
 cations. Rarefied air is therefore a good 
 conductor. 
 
 4. By touching various points of insulated 
 electrized bodies with a little disc of metallic 
 foil, cemented to the end of a needle ot lac, 
 which he applied to his electrometer, M. 
 Coulomb ascertained the variation of elec- 
 trical density, that exists at different points on 
 the surfaces of bodies, ot different forms and 
 
 magnitudes. He thus found, that towards the 
 extremities of all oblong conducting bodies, 
 whether thin plates, prisms, or cylinders, 
 there is a rapid augmentation of the electri- 
 city. He insulated a circular cylinder of 
 two inches diameter and thirty inches iu 
 length, terminated at each end with a hemi- 
 sphere. By comparing the quantities of 
 electricity accumulated at the centre, and at 
 various points, near to its extremities, he 
 found 
 
 Ratio of the second 
 
 electron) ctiic torsion 
 to the first. 
 
 Touched at the middle and 
 2 inches from the end, 1.25 
 
 And 1 from do. - 1.80 
 
 And at the end, - 2.30 
 
 When the cylinder becomes more and 
 more slender towards its extremities, the in- 
 crease of electricity becomes in these parts 
 more considerable, and more rapid. Lastly, 
 if the extremity of the cylinder be prolonged 
 like the apex of a cone, the accumulation 
 which occurs at this point becomes so strong, 
 that the resistance of the air is no longer 
 sufficient to retain the electricity on the sur- 
 face of the conducting body, and it escapes 
 in luminous coruscations, visible in the dark. 
 In this case, the uniform distribution of 
 electricity, extends to a very small distance 
 from the pointed extremity. We thus per- 
 ceive why bodies furnished w ith sharp projec- 
 tions, rapidly lose the electricity communicat- 
 ed to them. In like manner, a circular plate 
 of five inches diameter, when electrified, has at 
 its centre an intensity of 1, at one inch from 
 it 1.001, at two inches 1.005, at three inches 
 1,17, at four inches 1.52, at four and a half 
 inches 2.07, and at the border 2.9 times that 
 of the centre. We can thus understand 
 how electrical machines, furnished with elon- 
 gated prime conductors, furnish very vivid 
 sparks. 
 
 2. Of the distribution of electricity among 
 contiguous bodies, not in contact. 
 
 Let us examine first what happens when 
 two electrified spheres separated from contact, 
 are removed to a little distance from each 
 other. A very remarkable phenomenon is 
 then developed. We have seen, that during 
 contact, the electricity is of the same nature 
 on the two spheres. To fix our ideas, let us 
 suppose it to he vitreous. We have likewise 
 seen that it is null at the point of contact. 
 Now at the instant of separating the two 
 spheres, if their dimensions be unequal, this 
 nullity no longer exists. A part of the com- 
 bined electricity of the small sphere is de- 
 composed, and that which is of a nature op- 
 posite to the electricity of the great sphere, 
 namely the resinous in the present example, 
 is carried towards the point w here the contact 
 occurred. This effect diminishes according 
 as wc remove the two spheres from one ano- 
 ther, and it becomes null at a certain dis- 
 
ELE 
 
 ELE 
 
 tance, which depends on the ratio of their 
 radii. Then the point of the little sphere, 
 where the contact was, passes back into its 
 state during the contact, that is to say, it has 
 no species of electricity. Departing from 
 this term, if we augment the distance, the 
 electricity remains of the same nature over 
 the whole surface of the little sphere, and 
 that nature is the same as during the con- 
 tact. These phenomena are always peculiar 
 to the smaller of the two spheres, whatever 
 may be the quantity of electricity communi- 
 cated to them. On the larger sphere, the 
 electricity is always and throughout of the 
 same kind, as at the moment of contact. 
 
 In an experiment made by Coulomb, the 
 great globe being eleven inches, and the small 
 four in diameter, the opposition of the two 
 electricities continued till the distance be- 
 came two inches. When the diameter of 
 the latter was only two and a half inches, 
 the opposition continued till the distance 
 became two and a half inches, but not be- 
 yond. When the globes are equal, these 
 peculiarities do not take place. 
 
 When two oppositely electrized spheres are 
 gradually approached towards each other, the 
 thickness of the electric coating at the nearest 
 points of their two surfaces becomes greater, 
 and increases indefinitely as their distance di- 
 minishes. The pressure exercised by the elec- 
 tricity, against the plate of air interposed be- 
 tween the two bodies, augments progressively, 
 and terminates by overcoming the resistance 
 of the air. The fluid then escaping under 
 the form of a spark or otherwise, must pass 
 previous to the actual contact from one sur- 
 face to the other. 
 
 This action at a distance is a key to the 
 principal phenomena of electricity. 
 
 In our first inquiries we remarked, that 
 electrized bodies attract, or seem to attract, 
 all the light matters presented to them, with- 
 out its being necessary to develop in the 
 latter, the electric faculty, either by friction 
 or communication. But now we must con- 
 ceive that this development is spontaneous- 
 ly effected, by the mere influence at a dis- 
 tance of the electrized body, on the combined 
 electricities of the small bodies around. V bus 
 all the attractions, whether real or apparent, 
 which we observe, take place only between 
 electrized bodies. 
 
 When therefore an insulated conducting 
 body 13, which is in the natural state, is put 
 in presence of another insulated electrized 
 body A, the electricity distributed on the 
 surface of A, acts by influence on the two 
 combined and quiescent electricities of 13, 
 decomposes a quantity of them proportional 
 to the intensity of its action, resolving it into 
 its two constituent principles. Of these 
 two electricities become free, A attracts the 
 one, and repels the other. The second is 
 carried to the portion of the surface of 13, 
 
 which is most remote from A ; the first to 
 the contiguous surface. These two electri- 
 cities react in their turn on the free electri- 
 city of A, and even on its combined electri- 
 cities, of which one part is decomposed by 
 this reaction, and is separated, if the body A 
 be also a conductor. This new separation 
 induces a new decomposition of the combin- 
 ed electricity of 13, and thus in succession, 
 till the quantities of each principle become 
 free, or the two bodies come into an equili- 
 brium, by the balancing of all the attractive 
 and repulsive forces, which they mutually 
 exercise, in virtue of their similar or dissimi- 
 lar nature. 
 
 If A is vitreously electrized, and the con- 
 ductor B is a cylinder, the end of it adjoin- 
 ing to A will be resinous, and the remote 
 end vitreous, while the middle portion will 
 be nearly neutral. 
 
 If we now touch this remote end with a 
 third insulated conductor C, in the natural 
 state, and then remove it, we shall find it 
 charged with vitreous electricity. Or if we 
 touch the remote end of the second conduc- 
 tor w r ith a finger, and after withdrawing it 
 separate the first and second insulated con- 
 ductors, to a considerable distance, we shall 
 find that B has acquired electricity, indepen- 
 dent of the presence of A. Ilad we not 
 touched it, however, then on putting them 
 asunder, B, no longer exposed to the influ- 
 ence of A, would instantly recover its natu- 
 ral state. The two decomposed electricities 
 would in this case flow back from the extre- 
 mities, and recombining, restore the equili- 
 brium. If A was vitreous, the touch of an 
 unelectrified finger, would make B pass into 
 the resinously electrical state, by opening a 
 channel, so to speak, for the repelled vitreous 
 electricity to escape. We see also, how this 
 action and reaction may prodigiously in- 
 crease the intensity of an electricity origi- 
 nally very feeble. On this principle we can 
 at pleasure communicate to an insulated con- 
 ductor, either of the electricities, from one 
 electrified body or source. 
 
 Thus having excited a stick of sealing- 
 wax by rubbing it on the sleeve of our coat, 
 we may make this resinous electricity pro- 
 duce either the resinous or the vitreous state, 
 in the gold leaves of an electroscope. If we 
 hold the stick at a little distance, above the 
 cap of the electroscope, the leaves will im- 
 mediately diverge, and if we then remove it, 
 they will instantly collapse. If we now 
 touch the cap for an instant with the sealing- 
 wax, the leaves will acquire the same elec- 
 trical state ; they will continue divergent, 
 with resinous electricity. Let us restore the 
 natural state, by touching the cap with our 
 finger. Holding again the sealing-wax, a 
 little above the electroscope, let us then touch 
 its cap for a moment with our finger, and 
 after removing it w ithdraw the w'ax, we shall 
 
perceive the leaves continue to diverge, and 
 on trying the species of electricity, we shall 
 find it to be the vitreous ; for the approach 
 of excited wax will make the divergence 
 diminish, while that of excited glass will 
 make it increase. 
 
 These reciprocal attractions, repulsions, 
 and decompositions of the electrical com- 
 pound, explain perfectly the action of the 
 condenser of electricity as contrived by (Epi- 
 nus or Volta, and improved by Cuthbert- 
 son ; of the electrophorus ; of the Leyden 
 jar ; and in some measure, of that mysterious 
 apparatus, the voltaic battery. To this sub- 
 ject, all our preceding electrical researches 
 may be considered as merely introductory : 
 for this instrument constitutes the great link 
 between electricity and chemistry, deriving 
 probably its uninterrupted series of impulsive 
 discharges, and consequently its marvellous 
 power of chemical analysis, from the con- 
 joined agencies of electricity, and elective 
 attraction. 
 
 IV. Of Voltaic Electricity . 
 
 The accidental suspension of recently kill, 
 ed frogs, by copper hooks to the iron pali- 
 sades of his garden, was the occasion of the 
 celebrated Galvani observing certain convul- 
 sive movements, in the limbs of the animals, 
 which no known principle could explain, 
 and thenceforth of opening up to mankind, 
 a rich and boundless field in physical science. 
 As the practical nature of this work pre- 
 cludes us from entering into historical de- 
 tails, we shall at once proceed to describe 
 the present state of voltaic electricity and 
 electro-chemistry. Galvani had ascribed the 
 muscular movements to a series of dischar- 
 ges, of a peculiar electricity, inherent and in- 
 nate in living beings, to which the name 
 animal electricity, or the more mysterious 
 term galvanism, was for some time given. 
 Volta proved, that the phenomena proceeded 
 from the contact of the two dissimilar me- 
 tals, copper and iron, producing such a dis- 
 turbance of the electrical equilibrium, as was 
 sufficient to affect the most delicate of all 
 electroscopes, the irritability of a newly kill- 
 ed frog, though it was insensible to every 
 electroscope of human construction. He ful- 
 ly verified this fine theory, by shewing, that 
 a few contacts of the dissimilar metals, zinc 
 and silver, in the form of discs, furnished 
 with insulating handles, were capable of af- 
 fecting the common condenser of electricity. 
 Galvani, however anxious to defend his own 
 hypothesis, which linked his name to the 
 science, adduced some curious facts, which 
 proved, that muscular convulsions could be 
 produced in the limbs of dead frogs, alto- 
 gether independent of metals. This led 
 Volta to the further discovery, that other 
 dissimilar bodies besides metals, were capa- 
 ble by contact of disturbing the electrical 
 equilibrium. 
 
 ELK 
 
 Since a slender rod of silver and of 
 zinc, touching each other at one of their 
 ends, and at the other brought into con- 
 tact with the nerve and muscle, or spine 
 and toes of a dead frog, could excite power- 
 ful convulsions, it occurred to Volta, that a 
 repetition on a more extended surface, of 
 that simple series of two metals and mois- 
 ture, might produce a combined effect, ca- 
 pable of being felt by the human hand. By 
 a most philosophical prosecution of his own 
 principle, he happily succeeded in construct- 
 ing, by regular alternation of discs of silver, 
 zinc, and moistened cloth or pasteboard, 
 reared in a columnar form, the electro-che- 
 mical pile and battery, which will associate 
 the name of Volta to that of Galvani, 
 through each succeeding age. The com- 
 pound metallic arcs of copper and zinc, with 
 which he connected a circle of cups contain- 
 ing salt-water, to form his couronne dcs 
 tasses, may be regarded as the same apparatus, 
 in a horizontal, instead of a columnar ar- 
 rangement. The former construction was 
 happily modified by Mr Cruickshanks into 
 the voltaic trough ; while the latter has sug- 
 gested the arrangement of parallel porcelain 
 cells, into which a concatenated series of 
 compound metallic plates is immersed. 
 
 Amid the crowd of philosophers, who, 
 after Galvani and Volta, entered this ar- 
 duous field, two are pre-eminent for the in- 
 genuity and success of their investigations, 
 Dr Wollaston and Sir H. Davy, i he first 
 had the singular merit of tracing up the 
 analogy between the mysterious opera- 
 tions of galvanic, and of common electricity • 
 and afterwards invented an apparatus, by 
 which this agent can excite vivid ignition, in 
 almost a microscopic compass. Of the dis-) 
 coveries made by Sir H. Davy, in voltaic 
 electricity, and in chemistry, by the sagacious 
 application of its unlimited powers, it is dif- 
 ficult to speak in the cold language of philo- 
 sophy. They probably surpass in impor- 
 tance, as they do in splendour, the united 
 discoveries of preceding chemists ; and when 
 the breath of contemporary envy shall be 
 condensed in the cold grave, they will shine 
 forth on the diadem of English science, 
 companion gems, to the diamond of Newton. 
 
 1 shall now endeavour to give a brief sur- 
 vey of voltaic phenomena, conducting my 
 steps, by the researches of these philoso- 
 phers. 
 
 There are six great eras in electro-che- 
 mical science: — 1. Its first discovery by Gal- 
 vani ; 2. Volta’s discovery of the contact of 
 dissimilar metals, disturbing the electric equi- 
 librium ; 3. Volta’s invention of the pile ; 4. 
 The chemical power of this instrument, first 
 observed by Messrs Carlisle and Nicholson, 
 in the decomposition of water; 5. The iden- 
 tity of these chemical effects with those pro- 
 ducible by common electricity, first discover- 
 
ELE 
 
 ELE 
 
 ed and demonstrated by Dr Wollaston, in 
 his admirable “ Experiments on the Che- 
 mical Production and Agency of Electri- 
 city;” and lastly, The general laws of elec- 
 tro-chemical decomposition and transfer, re- 
 vealed by Sir H. Davy, in a series of me- 
 moirs, equally remarkable for genius and in- 
 dustry. It is but justice to this philosopher 
 to state, that the germ of his most splendid 
 discoveries, was manifestly formed and exhi- 
 bited, immediately after the construction of 
 the pile was announced. Volta’s celebrated 
 letter, descriptive of his invention, is dated 
 Como, March 20. 1 800 ; it was published 
 in the Philosophical Transactions, in the 
 autumn of that year; and in Nicholson’s 
 Journal, for September of the same year, we 
 have an important communication from Sir 
 H. Davy, then Superintendent of the Pneu- 
 matic Institution at Bristol. 
 
 Mr Carlisle having been favoured, by Sir 
 Joseph Banks, with a private perusal of Volta’s 
 letter, constructed a pile; and in the beginning 
 of May, assisted by Mr Nicholson, made seve- 
 ral experiments on the decomposition of wa- 
 ter, and the reddening of litmus by its means, 
 but out of delicacy to the Professor of Pavia, 
 these were not published till July. Mr 
 Nicholson, in a masterly account of Volta’s 
 discovery, Mr Carlisle’s, and his own, says, 
 “ We had been led by our reasoning on the 
 first appearance of hydrogen, to expect a de- 
 composition of the water; but it was with no 
 little surprise that we found the hydrogen 
 extricated at the contact with one wire, while 
 the oxygen fixed itself in combination with 
 the other wire, at the distance of almost two 
 inches. This new fact still remains to be 
 explained, and seems to point at some gene- 
 ral law, of the agency of electricity in chemi- 
 cal operations.” 
 
 “ Struck,” says Sir II. Davy, “ with the 
 curious phenomena noticed by Messrs Ni- 
 cholson and Carlisle, namely, the apparent 
 separate production of oxygen and hydrogen 
 from different wires, or from different parts 
 of the water completing the galvanic circle, 
 ^ny first researches were directed towards 
 ascertaining, if oxygen and hydrogen could 
 be separately produced from quantities of 
 water, not immediately in contact with each 
 other. He then proceeds to describe very 
 ingenious and decisive experiments, in which 
 he produced the distinct evolution of oxygen 
 and hydrogen, from water contained in two 
 separate glasses, even when the communica- 
 tion was made between them, through dead 
 muscular fibre, tnrough his own body, or 
 even through three persons. He next sub- 
 mits water, deprived of its loosely combined 
 oxygen by boiling, to the voltaic pile, and 
 obtains its two constituents in a pure state. 
 
 “ Reasoning,” says he “ on this separate 
 production of oxygen and hydrogen, from 
 different quantities of water, and on the cx- 
 
 ' 2 
 
 periments of Mr Henry, junior, on the ac- 
 tion of galvanic electricity on different com- 
 pound bodies, I was led to suppose, that the 
 constituent parts of such bodies (supposing 
 them immediately decomposable by the gal- 
 vanic influence), might be separately extri- 
 cated from the wires, and in consequence, 
 obtained distinct from each other .” After 
 submitting solution of potash to the voltaic 
 powers of 100 pairs of small plates, without 
 obtaining the expected decomposition, he ob- 
 serves, “ Surprised at these results, which 
 proved that no decomposition of potash had 
 taken place, and that that substance in this 
 mode of operating, only enabled the galvanic 
 influence to extricate oxygen and hydrogen 
 more rapidly from water, I was induced to 
 operate upon this substance in the way of 
 direct communication.” Still, only the water 
 was decomposed, as we might now expect. 
 He finally describes the decomposition of 
 water of ammonia, as well as sulphuric and 
 nitric acids, and concludes by correcting an 
 error into which Dr Henry had fallen, con- 
 cerning a supposed decomposition of potash. 
 “ If,” says he, “ the ratio between the 
 quantities of oxygen and hydrogen produced 
 from the different wires, be always the same, 
 whatever substances are held in solution by 
 the water connected with them, this nascent 
 hydrogen will become a powerful and accu- 
 rate instrument of analysis.” 
 
 Dr Wollaston coated the middle of a very 
 fine silver wire, for two or three inches, with 
 sealing-wax, and by cutting it through in 
 the middle of the wax, exposed a section of 
 the wire. The two coated extremities of the 
 wire thus divided, were immersed in a solu- 
 tion of sulphate of copper, placed in an elec- 
 tric circuit between the two conductors of a 
 cylindrical machine ; and sparks taken at 
 1-1 Oth of an inch distance, were passed by 
 means of them through the solution. After 
 100 turns of the machine, the wire which 
 communicated with (what is called) the ne- 
 gative conductor, had a precipitate formed 
 on its surface, which on being burnished, was 
 evidently copper ; but the opposite wire had 
 no such coating. 
 
 Upon reversing the direction of the cur- 
 rent of electricity, the order of the pheno- 
 mena was of course reversed ; the copper 
 being shortly redissolved by assistance of the 
 oxidating power of positive electricity, and a 
 similar precipitate formed on the opposite 
 wire. 
 
 A similar experiment, made with gold 
 wires of an inch diameter, in a solution 
 of corrosive sublimate, had the same suc- 
 cess. 
 
 If a piece of zinc and a piece of silver have 
 each one extremity immersed in the same 
 vessel, containing sulphuric or muriatic acid 
 diluted with a large quantity of water, the 
 zinc is dissolved and yields hydrotren <nis bv 
 
 'i * » O O w J 
 
ELE 
 
 ELE 
 
 decomposition of the water ; the silver not 
 being acted upon has no power of decompos- 
 ing water; but whenever the zinc and silver 
 are made to touch, or any metallic commu- 
 nication is made between them, hydrogen gas 
 is also formed at the surface of the silver. 
 Any other metal beside zinc, which, by the 
 assistance of the acid employed, is capable of 
 decomposing water, will succeed equally, if 
 the wire consists of a metal on which the 
 acid has no effect. 
 
 Experiments analogous to the former, and 
 equally simple, may also be made with many 
 metallic solutions. If, for instance, the so- 
 lution contains copper, it will be precipitated 
 by a piece of iron, and will appear on its 
 surface. Upon silver merely immersed in 
 the same solution, no such effect is pro- 
 duced ; but as soon as the two metals are 
 brought into contact, the silver receives a 
 coating of copper. 
 
 In the explanation of these experiments, 
 says Dr Wollaston, it is necessary to advert 
 to a point established by means of the elec- 
 tric pile. We know that when water is 
 placed in a circuit of conductors of electricity, 
 between the two extremities of a pile, if the 
 power is sufficient to oxidate one of the wires 
 of communication, the wire connected with 
 the opposite extremity affords hydrogen gas. 
 Since the extrication of hydrogen in this in- 
 stance, is seen to depend on electricity, it is 
 probable that, in other instances, electricity 
 may be also requisite for its conversion into 
 gas. It would appear, therefore, that in the 
 solution of a metal, electricity is evolved 
 during the action of the acid on it; and that 
 the formation of hydrogen gas, even in that 
 case, depends on a transition of electricity 
 between the fluid and the metal. 
 
 We see, moreover, in the experiments with 
 zinc, that this metal, without contact of any 
 other, has the power of decomposing water; 
 and we can have no reason to suppose that 
 the contact of the silver produces any new 
 power, but that h serves merely as a con- 
 ductor of electricity, and thereby occasions 
 the formation of hydrogen gas. In the next 
 experiment, the iron by itself has the power 
 of precipitating copper by means, it is pre- 
 sumed, of electricity evolved during its solu- 
 tion ; and here likewise the silver, by con- 
 ducting the electricity, acquires the power 
 of precipitating the copper in its metallic 
 state. 
 
 The explanation now given, with regard 
 to these voltaic combinations of single pairs, 
 receives additional confirmation from the 
 above comparative experiments with common 
 electricity. These shew, that the same trans- 
 fer of chemical power, and the same apparent 
 reversion of the usual order of chemical affi- 
 nities in the precipitation of copper by silver, 
 mav be effected by a common electrical ma- 
 chine. 
 
 The chemical agency of common electri- 
 city is thus proved to be the same with the 
 power excited by chemical means ; but since 
 a difference had been observed in the com- 
 parative facility with which the pile of Volta 
 decomposes water, and produces other effects 
 of oxidation and deoxidation of bodies ex- 
 posed to its action, Dr Wollaston was at 
 pains to remove this difficulty, and succeeded 
 in producing a very close imitation of the 
 galvanic phenomena, by common electricity. 
 
 It had been thought necessary to employ 
 powerful machines, and large Leyden jars, 
 for the decomposition of water ; but when he 
 considered that the decomposition must de- 
 pend on duly proportioning the strength of 
 the charge of electricity to the quantity of 
 water, and that the quantity exposed to its 
 action at the surface of communication, de- 
 pends on the extent of that surface ; by re- 
 ducing this, he effected the decomposition of 
 water by a much smaller machine. Having 
 procured a small wire of fine gold, and given 
 it as fine a point as he could, he inserted it 
 into a capillary glass tube, and after heating 
 the tube so as to make it adhere to the point, 
 and cover it in every part, he gradually ground 
 it down, till with a pocket lens he could 
 discover that the point of the gold was ex- 
 posed. 
 
 The success of this method exceeding his 
 expectations, he coated several wires in the 
 same manner, and found, that when sparks 
 from the conductors before mentioned were 
 made to pass through water, by means of a 
 point so guarded, a spark passing to the dis- 
 tance of one-eighth of an inch, would decom- 
 pose water, when the point exposed did not 
 exceed l-700th of an inch in diameter. 
 With another point which he estimated at 
 1-1 500th, a succession of sparks l-20th of 
 an inch in length afforded a current of small 
 bubbles of air. But in every way in which 
 he tried it, he observed that each wire gave 
 both oxygen and hydrogen gas, instead ot 
 their being formed separately as by the elec- 
 tric pile. 
 
 He is inclined to attribute the difference 
 in this respect to the greater intensity with 
 which it is necessary to employ common 
 electricity; for that positive and negative 
 electricity so excited, have each the same 
 chemical power as they are observed to have 
 in the electric pile, may be ascertained by 
 other means. 
 
 In the precipitation of copper by silver, an 
 instance of deoxidation by negative electri- 
 city has been mentioned ; the oxidating 
 power of positive electricity may be also 
 proved by its effect on vegetable colours. 
 
 Having coloured a card with a strong in- 
 fusion of litmus, he passed a current of elec- 
 tric sparks along it, by means of two fine 
 gold points, touching it at the distance of an 
 inch from each other. The effect, as in other 
 
ELE 
 
 ELE 
 
 cases, depending on the smallness of the 
 quantity of water, was most discernible when 
 the card was nearly dry. In this state a very 
 few turns of the machine were sufficient to 
 occasion a redness at the positive wire, very 
 manifest to the naked eye. The negative 
 wire being afterwards placed on the same 
 spot, soon restored it to its original blue co- 
 lour. By the voltaic pile, the same effects 
 are produced in a much less time. 
 
 Dr Wollaston concludes, that all the dif- 
 ferences discoverable in the effects of gal- 
 vanic and common electricity, may be owing 
 to the former being less intense, but pro- 
 duced in much larger quantity. 
 
 A wire connected with the zinc extremity 
 of a voltaic pile of 50 or 100 pairs, being 
 made to touch the brass cap of the electro- 
 scope, will cause the gold leaves instantly to 
 diverge with vitreous electricity ; a wire con- 
 nected with the copper end will make them 
 diverge with resinous electricity ; but a wire 
 from the middle of the pile will have no 
 effect on the electroscope. 
 
 If wires of platinum from the opposite 
 extremities of the pile be introduced into any 
 solution of a neutral salt, containing acid, 
 united to alkaline, earthy, or common metal- 
 lic matter; acid matter will collect round 
 the vitreously electrified or positive surface ; 
 alkali, earth, or oxide, round the resinously 
 electrified or negative surface. If two se- 
 parate vessels are employed to contain the 
 solution, connected by moist asbestos, it is 
 found that the acid collected in the vessel 
 containing the wire positively electrified, will 
 be in definite proportion to the matter col- 
 lected in the other cup ; that is, it will form 
 with it a neutrosaline compound. If aque- 
 ous muriatic acid be acted on by the wires, 
 hydrogen will separate at the negative sur- 
 face, and chlorine at the positive. 
 
 The preceding may be regarded as the 
 elementary and fundamental facts, discovered 
 with regard to voltaic electricity. Before 
 describing its greater and more complex 
 operations, we shall give an account of the 
 various modifications of the apparatus. 
 
 In the original trough of Cruikshanks, 
 the contact of every pair of copper and zinc 
 plates was secured by soldering their surfaces 
 together. Each compound metallic plate 
 being of a square form, was fixed tight by ce- 
 ment into groves cut in the sides, and across 
 the bottom, of the oblong mahogany box. 
 The cells between every pair of plates, were 
 filled with the neutrosaline or acidulous ex- 
 citing liquid. The difficulty of cleaning the 
 surfaces of the plates in this construction, 
 and an idea that the quantity of electricity 
 was proportional to the zinc surface exposed 
 to oxidizement, led to the revival of the 
 Couronnes des lasses arrangement. In this, 
 j the square plates of zinc and copper in each 
 I pair were placed parallel to each other, at a 
 
 distance of about half an inch, and soldered 
 together at the middle of one edge by a rec- 
 tangular narrow arc of copper. Each pair 
 •was fixed parallel to the preceding pair, and 
 at a distance corresponding to the width of 
 the cells in the porcelain trough, by screwing 
 their rectangular arcs to a rod of baked and 
 well varnished wood. Ten or a dozen pair* 
 of plates, from four to six inches diameter 
 each, could thus at once ha conveniently 
 plunged into, or removed from, the exciting 
 liquid. By connecting together a series of 
 these troughs, a very powerful battery was 
 obtained. More recently, Dr Wollaston has 
 rendered it probable that the igniting influ- 
 ence of the voltaic apparatus, is increased 
 by placing opposite to both surfaces of the 
 zinc, at the distance of one- eighth or one- 
 fourth of an inch, a copper plate. At least 
 the astonishing power of ignition, exhibited 
 by his pair of small plates, seems to warrant 
 that conclusion. 
 
 For compactness of structure, and conve- 
 nience in use, I prefer the original mahogany 
 box, and soldered pairs of plates, of Cruik- 
 shanks. The zinc surfaces may he easily 
 freed from adhering oxide, by a steel scraper 
 of a proper shape. Nor do I find that this 
 form of apparatus is notably inferior, in che- 
 mical effect, to the separate plates of the same 
 size in porcelain cells. Dr Hare of Phila- 
 delphia has lately contrived an ingenious 
 modification of Dr Wollaston’s single ignit- 
 ing pair, which, from its great power of ex- 
 citing heat, and its small electric intensity, 
 lie has styled a calorimotor. 
 
 When the plates arc very large, they must 
 be constructed on the plan of the porcelain 
 trough. In this way, Mr Children arranged 
 his gigantic battery, the most magnificent vol- 
 taic apparatus which the world has hitherto 
 seen. It consisted of 20 pairs of copper and 
 zinc plates, each plate six feet long and two 
 feet eight inches broad. Each pair is joined 
 at top by ribbons of lead, and lias a separate 
 wooden cell. They are suspended from a 
 beam of wood, and having counterpoises, are 
 easily raised or let down into their cells. 
 The power of this battery was first tried on 
 2d of July 1815. The cells were filled with 
 water 60 parts, and a mixture of nitric and 
 sulphuric acid one part, which was gradually 
 increased till the quantity of acid was dou- 
 bled. Conductors of lead conveyed the elec- 
 tricity to an adjoining shade, in which the 
 experiments were made. The power of the 
 battery was prodigious. It ignited six feet 
 in length of thick platinum wire; but could 
 not ignite an equal length of smaller plati- 
 num wire. This difference was ingeniously 
 ascribed by Dr Wollaston, to the cooling in- 
 fluence of the air, acting more efficaciously 
 on the slender mass of metal. Platinum, in 
 shorter lengths, was fused with great facility. 
 Iridium was melted into a globule, and 
 
ELE 
 
 X 
 
 ELE 
 
 proved to be a brittle metal. Tho compound 
 ore of iridium and osmium, was likewise 
 fused, but not perfectly. Charcoal kept at 
 a white heat, in chlorine and chlorocarbonous 
 gases, produced no change on them. Neither 
 tungsten nor uranium was any way changed 
 by this vast battery. 
 
 At a very early period of his illustrious 
 electro- chemical career, Sir H. Davy in- 
 vented various voltaic constructions, in which 
 either only one metal was employed, or no 
 metallic body at all. Among the scientific 
 news inserted in the Philosophical quarto 
 Journal for May 1801, we are told that he 
 had formed piles, consisting of the single 
 metals, silver, eopper, zinc, and lead ; and 
 that one of the arrangements was, a plate of 
 metal, cloth soaked in dilute nitrous acid, 
 cloth soaked in water, and cloth soaked in 
 solution of sulphuret of potash ; then ano- 
 ther plate of the same metal, and the three 
 cloths as before. It is added, that if a 
 trough be used with cells, and the separation 
 between the acid and the sulphuret of potash 
 
 be made by a plate of horn, instead of the 
 cloth imbibed with water, the two fluids 
 may be connected by a slip of wetted cloth, 
 hung over the upper edge of the horn. 
 This will complete the communication, with- 
 out occasioning any mixture, because water 
 is lighter than any of the other fluids. A 
 full account of these new and very curious 
 arrangements, was published in the Philoso- 
 phical Transactions for the above year, and 
 is copied into the December Number of Ni- 
 cholson’s Journal. 
 
 Silver or copper, in the above construc- 
 tion, forms an electrical apparatus, which, 
 with a series of fifty plates, will give shocks. 
 When the structure is that of a pile, the cloth 
 impregnated with the densest solution should 
 be undermost in each alternation ; and solu- 
 tion of common salt in the middle. 
 
 The following tables contain some series, 
 which form voltaic electrical combinations, 
 arranged in the order of their powers ; th© 
 most active substances being named first in 
 each column. 
 
 TABLES by Sir II. Davy , of some Electrical Arra ngements, which, by com- 
 bination, form voltaic batteries, composed of two conductors, and one imper- 
 fect conductor. 
 
 Zinc 
 
 Each of these is 
 
 Solutions of nitric acid. 
 
 Iron 
 
 the positive pole 
 
 of muriatic acid. 
 
 I in 
 
 to all the metals 
 
 of sulphuric acid. 
 
 Lead 
 
 below it, and ne- 
 
 of sal ammoniac. 
 
 Copper 
 
 gative with res- 
 
 of nitre. 
 
 Silver 
 
 peet to the me- 
 
 other neutral salts. 
 
 Gold 
 
 tals above it in 
 
 • 
 
 Platinum 
 
 the column. 
 
 
 Charcoal 
 
 
 
 TABLE II.— Of some Electrical arrangements , consisting of one conductor 
 
 and two imperfect conductors. 
 
 Solution of sulphur and potash 
 
 Copper 
 
 Nitric acid. 
 
 of potash 
 
 Silver 
 
 Sulphuric acid. 
 
 of soda 
 
 Lead 
 
 Muriatic acid. 
 
 
 Tin 
 
 Any solution con- 
 
 
 Zinc 
 
 taining acid. 
 
 
 Other metals 
 
 
 
 Charcoal 
 
 « 
 
 filled with solutions of sulphur and potash, 
 the copper is positive, and the iron negative 
 
 In all combinations in which one metal if 
 concerned, the surface opposite the acid if 
 negative, while that in contact with the solu- 
 tion of alkali and sulphur, or of alkali, ia 
 positive. 
 
 Every one who has a perception of the* 
 beautiful in philosophical research, must re- 
 gard this important law, discovered by Si* 
 II. Davy, with admiration. It promises ti 
 lead us eventually into the mysteries oS 
 electro-chemical action, further than any ge- 
 
 The metals having the strongest attraction 
 for oxvgen, are the metals which form the 
 positive pole, in all cases in which the fluid 
 menstrua act chemically, by affording oxy- 
 gen ; but when the fluid menstrua afford 
 * sulphur to the metals, the metal having the 
 strongest attraction for sulphur, under the 
 existing circumstances, determines the posi- 
 tive pole. Thus, in a series of copper and 
 iron, introduced into a porcelain trough, the 
 cells of which arc filled with water, or with 
 acid solutions, the iron is positive, and the 
 Conner negative ; but when the cells nre 
 
ELE 
 
 ELE 
 
 neral principle hitherto established. It gives 
 another fine analogy between electricity and 
 heat. For as the disengagement of the latter 
 power is always proportional to the intensity 
 of chemical combination, so in the present 
 case we see, that the intenser chemical action 
 is connected with the evolution of positive 
 electricity, while the feebler is associated 
 with the negative. The positive electricity, if 
 ■we judge from the appearance of its light, is 
 the more active of the two ; and it is known 
 to promote the most intense combinations of 
 bodies, viz. those with chlorine, iodine, and 
 oxygen. 
 
 The divergence of the leaves in the gold- 
 leaf electroscope, and more exactly, the se- 
 paration of the ball and disc in the electro- 
 meter of Coulomb, are proportional to the re- 
 silient force, or intensity of the electrical 
 agent. Hence the repetition of a series of 
 moderate sized voltaic plates, indicates the 
 same repulsing energy on these instruments, 
 as the same series of much larger plates. 
 With regard to imperfect conductors, like 
 the human body, or neutrosaline solutions, 
 the effects, namely, the shock, and transfer of 
 the elements, are also proportional to the 
 electrical intensity, or electroscopic indica- 
 tions. For these purposes, we need not en- 
 large the plates beyond a certain size, which 
 is relative to the conducting power of the 
 substances, through which the electrical ener- 
 gy is to be transmitted. But with excellent 
 conductors, like charcoal and the metals, the 
 quantity of electricity, and not its state of 
 condensation , is to be regarded. The in- 
 tensity is essential, to enable it to communi- 
 cate electrical polarities to a series of mate- 
 rial liquid molecules, or to force its way, so 
 to speak, through the animal frame. But 
 the same intensity is altogether superfluous 
 relative to metallic objects. To operate 
 changes on these, we must favour the evolu- 
 tion of a great mass of electrical power, by 
 using plates of extensive areas. ' 
 
 To prove the justness of these views, let 
 us bring into action, by the same exciting 
 liquid, a clean battery of 20 pairs of 1 
 inch, and 2Q pairs of 10 inch plates. On 
 exposing a small column of water, in a glass 
 tube, first to the one battery, and then to 
 the other, or on connecting, with the two 
 hands, first the extremities of the one, and 
 then those of the other, we shall perceive the 
 evolution of gases, or the shock, to be nearly 
 equal. While the energy of the larger bat- 
 tery is acting on the water or human body, 
 let two little cylinders of charcoal, connected 
 with the ends of the trough by metallic 
 wires, be made to touch each other, the elec- 
 trical excess will be sufficient to produce 
 vivid ignition at the points of contact. Sil- 
 ver leaf may be substituted for the charcoal, 
 with a similar effect. The little battery, 
 however, exhausts its energy on the column 
 
 of water. WTien thus employed, it will 
 give scarcely any sensation to the fingers, 
 and produce no effect on the charcoal or 
 leaf. Even the battery of Mr Children, 
 which, after igniting great lengths of plati- 
 num wire, to a whiteness insupportable to 
 the eye, fused it into globules ; and which 
 emitted from charcoal a light more dazzling 
 than the sunbeam, had no more effect on 
 water, and the living body, than an equal 
 series of little plates. 
 
 As Mr Children’s battery is the most 
 powerful in the world, in oalorific effect, so 
 that of 2000 pairs of plates, of 32 inches 
 each, furnished by the subscription of a few 
 patrons of science connected with the Royal 
 Institution, is the most powerful yet con- 
 structed in electro- chemical intensity. The 
 whole surface is 128000 square inches. 
 
 This battery, when the cells were filled 
 with 60 parts of water, mixed with one part 
 of nitric acid, and one of sulphuric acid, 
 afforded a series of brilliant and impressive 
 effects. When pieces of charcoal, about an 
 inch long, and one-sixth of an inch in dia- 
 meter, were brought within l-30thor l-40th 
 of an inch of each other, a bright spark was 
 produced, and more than half the volume of 
 the charcoal became ignited to whiteness ; 
 and by drawing back the points a little from 
 each other, a constant discharge took place, 
 through the heated air, in a space equal at 
 least to four inches, producing a most bril- 
 liant ascending arch of light, expanded and 
 conical in the middle. When any substance 
 was introduced into this arch, it instantly 
 became ignited. 
 
 Platinum melted in it, like wax in the 
 flame of a common candle. Quartz, the 
 sapphire, magnesia, lime, all entered into 
 fusion. Fragments of diamond, and points 
 of charcoal and plumbago, rapidly disappear- 
 ed, and seemed to evaporate in it, even when 
 the connexion was made in a receiver ex- 
 hausted by the air-pump ; but there was no 
 evidence of their having previously under- 
 gone fusion. 
 
 When the communication between the 
 points, positively and negatively electrified, 
 was made in air rarefied in the receiver of 
 the air-pump, the distance at which the dis- 
 charge took place increased as the exhaustion 
 proceeded, and when the atmosphere in the 
 vessel supported only an inch of mercury in 
 the barometrical gauge, the sparks passed 
 through a space of nearly half an inch. By 
 making the points recede from each other, 
 the discharge was made through 6 or 7 
 inches, producing a most beautiful corusca- 
 tion of purple light; the charcoal became in- 
 tensely ignited, and some platinum wire 
 attached to it, fused with brilliant scintilla- 
 tions, and fell in large globules upon the 
 plate of the pump. All the phenomena of 
 chemical decomposition were produced with 
 
ELE 
 
 ELE 
 
 intense rapidity, by this combination. When 
 the points ot charcoal were brought near 
 each other in non-conducting fluids, such as 
 oils, ethers, and chloridic compounds, bril- 
 liant sparks occurred, and elastic matter was 
 generated, Such, indeed, was the electric 
 intensity, that sparks were produced, even in 
 good imperfect conductors, such as the nitric 
 and sulphuric acids. 
 
 When the two conductors from the ends 
 of the combination, were connected with a 
 Leyden battery, one with the internal, the 
 other with the external coating, the battery 
 instantly became charged, and on removing 
 the wire, and making the proper connexions, 
 either a shock or a spark could be perceived ; 
 and the least possible time of contact was suf- 
 ficient to renew the charge to its full intensity. 
 
 The general facts of the connexion of the 
 increase of the different powers of the bat- 
 tery with the increase of the number, and 
 surface of the series, are very distinct ; but 
 to determine the exact ratio of the con- 
 nexion, is a problem not easy of solution. 
 
 MM. Gay Lussac and Thenard announc- 
 ed, that the power of chemical decomposi- 
 tion increases only as the cube root of the 
 number of plates ; but their experiments 
 were made with parts of piles, says Sir H. 
 Davy, very unfavourable for gaining accu- 
 rate results. In various trials made by him, 
 with great care, in the laboratory of the 
 Royal Institution, the results were altoge- 
 ther different. 
 
 The batteries employed were parts of the 
 above great combination, carefully insulated, 
 and similarly charged ; arcs of zinc and silver 
 presenting equal surfaces, arranged in equal 
 glasses, filled with the same kind of fluid, 
 were likewise used ; and the tubes were pre- 
 cisely similar, and filled with the same solu- 
 tion of potash. In these experiments, 10 
 pairs of plates produced 15 measures of gas; 
 20 pairs produced in the same time 49; 
 again, 10 pairs produced five measures; 40 
 pairs in the same time produced 78 mea- 
 sures. In experiments made with arcs, and 
 which seemed unexceptionable, 
 
 4 pairs produced 1 measure of 
 
 gas. 
 
 1 2 in the same time 9y 
 When 6 produced 1 
 
 30 - - 24.5. 
 
 Now, these quantities are nearly as the 
 squares of the number of pairs. 
 
 In batteries, whose plates have equal areas, 
 the calorific power has been said to be ns the 
 number. Sir II. Davy, however, found that 
 when the surface of each was 100 square 
 inches, 
 
 10 pairs ignited 2 inches of plat, wire l-80th 
 of an inch. 
 
 20 do. do. 5 inches, do. do. 
 
 10 do. do. 11 inches, do. do. 
 
 The results of experiments on higher num- 
 
 bers were not satisfactory, for 100 pairs, of 
 82 square inches each, ignited three inches 
 of platinum wire 1- 70th of an inch; and 
 1000 ignited only 13 inches. The charges 
 of exciting acid, were similar in both cases. 
 
 The ratio between the increase of calorific 
 power, and increased area of the plates, 
 is probably greater than even the square. 
 For 20 pairs of plates, containing each two 
 square feet, did not ignite one sixteenth as 
 much wire, as 20 pairs, containing each eight 
 square feet ; the acid employed being of the 
 same strength in botli cases. But great dif- 
 ficulties occur to ensure accuracy, in experi- 
 ments on extensive and powerful batteries. 
 
 In Sir H. Davy’s great Bakerian Lecture 
 on the chemical agencies of electricity, 
 published in the Phil. Trans, for 1807, and 
 most deservedly crowned by the National 
 Institute of France with the Napoleon prize, 
 he amply demonstrated that acids, which are 
 electrically negative, w ith respect to alkalis, 
 metals, and earths, are separated from these 
 bodies in the voltaic circuit at the positive 
 pole ; and alkalis, metals, and earths, are 
 separated from acids, at the negative surface. 
 He shewed further, that such are the attract- 
 ing powers of these surface:, that acids are 
 transferred through alkaline solutions, and 
 alkalis through acid solutions, to the poles 
 w here they have their points of repose. This 
 w r as exhibited by making a combination of 
 three agate cups, one containing sulphate of 
 potash, one weak nitric acid, and the third 
 distilled water. The three were connected 
 by asbestus moistened in pure water, in such 
 a manner, that the surface of the acid was 
 lower than the surface of the fluid, in the 
 other two cups. When tw r o wires of platina 
 from a powerful voltaic apparatus, are in- 
 troduced into the two extreme cups, tiie so- 
 lution of the salt being positively electrified, 
 a decomposition took place, and in a certain 
 time, a portion of potash was found dissolved 
 in the cup, in contact w ith the negative wire, 
 though the fluid in the middle cup was still 
 sensibly acid. 
 
 Such are the ehemico-analytical powers 
 of electricity, that not even insoluble com- 
 pounds are capable of resisting their energy; 
 for even glass, sulphate of barytes, fiuor spar, 
 gypsum, marble, Sec. when moistened and 
 placed in contact with electrified surfaces, 
 from the voltaic apparatus, are sensibly acted 
 on, and the alkaline, earthy, or acid matter, 
 slowly carried to the poles in the common 
 order. Not even the most solid aggregates, 
 nor the firmest compounds, are capable of 
 resisting this mode of attack. Its operation 
 is slow, but the results arc certain, and, 
 sooner or later, by means of it, bodies are 
 resolved into simpler forms of matter. 
 
 Till Sir II. Davy established the grand 
 law of electro-chemical decomposition, that 
 metals, inflammable bodies,' alkalis, earths, 
 
ELE 
 
 ELE 
 
 and oxides, are determined to the negative 
 surface or pole, and oxygen, chlorine, iodine, 
 and acids, to the positive pole, it had been 
 imagined that various substances might be 
 generated from pure water, by means of elec- 
 tricity, such as potash, soda, and muriatic 
 acid. A strict investigation of the circum- 
 stances under which these substances appear- 
 ed, led him to discover that they were always 
 furnished from the vesseis, or from impuri- 
 ties in the water, and enabled him to deter- 
 mine the general principles of electrical de- 
 composition, and to apply this power to the 
 resolution of several species of matter of un- 
 known nature into their elements, namely 
 the alkalis, earths, boracic and muriatic 
 acids, &c. 
 
 The intimate relation between the elec- 
 trical and chemical changes, is evident like- 
 wise in the general phenomena of the bat- 
 tery. The most powerful voltaic combina- 
 tions are formed by substances that act che- 
 mically, with most energy upon each other. 
 Such substances as undergo no chemical 
 changes in these combinations, exhibit no 
 electrical powers. Thus, zinc, copper, and 
 nitric acid, form a powerful battery ; while 
 silver, gold, and water, which do not act 
 chemically on each other, produce, in series 
 of the same number, no perceptible effect. 
 These circumstances, in the infancy of gal- 
 vanic research, led to the belief that the elec- 
 trical phenomena were entirely the results of 
 chemical changes ; and that as heat was pro- 
 duced by chemical action, under common 
 circumstances, so electricity resulted from it 
 under other circumstances. 
 
 This generalization seems, however, to be 
 incorrect. Zinc and copper, different metals 
 and oxalic acid, different metals and sulphur 
 or charcoal, exhibit electrical effects after 
 mere contact, and that in cases when not the 
 slightest chemical change can be observed. 
 If, in these experiments, indeed, chemical phe- 
 nomena are produced by the action of men- 
 strua, all electrical effects immediately cease. 
 
 The source of action of the voltaic appa- 
 ratus, seems to depend upon causes similar to 
 those which produce the accumulation in the 
 Leyden battery, namely, that influence at a 
 distance, or electrical induction, which was 
 fully treated of at the commencement of this 
 article. Hut its continuous action, or elec- 
 tro-motion, is connected with the decom- 
 position of the chemical menstrua between 
 the plates. Each plate of zinc, in the first 
 place, is made positive, and each plate of 
 copper negative, by contact; and all the 
 plates are so arranged with respect to each 
 other, as to have their electricities exalted by 
 induction, so that every single polar arrange- 
 ment heightens the electricity of every other 
 polar arrangement; and hence the accumu- 
 lation of power, or intensity, must increase 
 with the number of the series. When the 
 
 battery is connected in a circle, the effects 
 are demonstrated by its constant exhibition 
 of chemical agencies, and the powers exist 
 as long as there is any menstruum to decom- 
 pose. But when it is insulated, and the 
 extreme poles of zinc and copper are uncon- 
 nected, no effects whatever are perceived to 
 take place, no chemical changes go on, and 
 it exhibits its influence only by communicat- 
 ing very weak charges to the electrometer ; 
 the zinc termination of the pole communi- 
 cating a positive charge, the copper termina- 
 tion a negative charge. 
 
 A beautiful experiment of Sir II. Davy’s 
 proves, that each plate of the most oxidable 
 metal in the apparatus, is in the relation of 
 positive, and that each plate of the least oxid- 
 able, is in the relation of negative, while every 
 series is possessed of similar and equal polarity. 
 Forty rods of zinc of the same size, connected 
 with forty silver wires, precisely similar, were 
 introduced in the regular order, into similar 
 glasses, filled with a solution of muriate of 
 ammonia, rendered slightly acidulous by 
 muriatic acid. As long as the extreme 
 parts remained unconnected, no gas was dis- 
 engaged from the silver, and the zinc was 
 scarcely acted upon. When they were con- 
 nected, all the plates of zinc were dissolved 
 much more rapidly, and hydrogen gas was 
 evolved from every silver wire. In another 
 experiment, in which several of these wires, 
 at equal distances, were introduced into small 
 glass tubes, it was found that equal quantities 
 of hydrogen were produced. 
 
 There are no fluids known, except such 
 as contain water, which are capable of being 
 made the medium of connexion between the 
 metals or metal of the voltaic apparatus ; 
 and it is probable that the power of water to 
 receive double polarities, and to evolve oxy- 
 gen and hydrogen, is necessary to the con- 
 stant operation of the connected apparatus. 
 We may suppose also, that acids or saline 
 bodies increase the action, by affording ele- 
 ments which possess opposite electricities to 
 each other, when mutually excited. The 
 action of the chemical menstrua exposes 
 continually new surfaces of metal ; and the 
 electrical equilibrium may be conceived, in 
 consequence, to be alternately destroyed and 
 restored, the changes taking place in imper- 
 ceptible portions of time. 
 
 We may shew the manner in which aque- 
 ous fluids propagate electrical polarity among 
 their particles, by a very simple experiment. 
 Cut narrow filaments of tin-foil into lengths 
 of almost half an inch, and place them in a 
 line in the surface of an oblong trough of 
 water. On plunging into the water, at each 
 end, wires connected with the two extremi- 
 ties of an active voltaic battery, the metallic 
 filaments will immediately acquire polarity. 
 Their positive and negative poles will be- 
 come regularly opposed to each other, the 
 
ELE 
 
 EME 
 
 first depositing oxide, and the la 9 t evolving 
 hydrogen. The analogy with magnetic ac- 
 tions, is here very complete. 
 
 That the decomposition of the chemical 
 agents is connected with the energies of the 
 pile, is evident from all the experiments that 
 have been made. No sound objection has 
 been urged against the theory, that the con- 
 tact of the metals destroys the electrical 
 equilibrium, and that the chemical changes 
 restore it ; and, consequently, that the action 
 exists as long as the decompositions continue. 
 
 Volta called his admirable invention an 
 electro-motive apparatus, founding his theory 
 of its operation upon the Franklinian idea of 
 an electrical fluid, for which certain bodies 
 have stronger attractions than others. Ho 
 conceived that in his pile, the upper plate of 
 zinc attracts electricity from the copper, the 
 copper from the water, the water again from 
 the next plate of zinc, the next plate of zinc 
 from the next plate of copper, and so on. 
 This hypothesis applies happily to most of 
 the phenomena of the action of the insulated 
 pile, and the pile connected by either of its 
 extremities with the ground ; but does not 
 explain with the same facility* the powers of 
 the apparatus connected in a circle, in which 
 each plate of zinc must be supposed to have 
 the same quantity of electricity as each plate 
 of copper; for it can only, as Sir H. Davy 
 justly observes, receive as much as the cop- 
 per can give, unless indeed the phenomena 
 of the circular apparatus be considered as 
 depending upon the constant and rapid cir- 
 culation of the natural quantity of electrici- 
 ty in the different series, which requires the 
 proof of a constant power to attract electri- 
 city from one body, at the same time that it 
 is given off' to another. But the investiga- 
 tions of Coulomb and Poisson, already detail- 
 ed, fully demonstrate that electricity is not 
 distributed among different species of mat- 
 ter, by any kind of elective attraction. 
 
 Platinum melts with more facility at the 
 positive than at the negative pole, when it is 
 connected with charcoal ; but with sulphuric 
 acid, it becomes red-hot, only when it is ne- 
 gative, and the acid positive. In the calori- 
 fic effect in general, charcoal is most easily 
 ignited, next iron, platinum, gold, then cop- 
 per, and lastly, zinc. 
 
 See Sir II. Davy's Elements , and M. 
 Biot's TraitS de Physique , tome ii. chapitre 
 16; Ejfets cliimiques de l' Appareil electro - 
 moteur. 
 
 We shall retain the title Galvanism, 
 out of respect to its illustrious discoverer, 
 and place under it, some details concerning 
 the influence of this form of electricity on 
 living bodies. 1 * 
 
 * Electrum. Sec Ores of Gold. * 
 
 Elements. A term used by the earlier 
 chemists, nearly in the same sense as the mo- 
 derns use the term jirst principle. The chief, 
 
 and indeed very essential difference between 
 them is, that the ancients considered their 
 elements as bodies possessing absolute sim- 
 plicity, and capable of forming all other bo- 
 dies by their mutual combination ; whereas 
 the first principles of the moderns are consi- 
 dered as simple, merely in respect to the pre- 
 sent state of the art of analyzing bodies. 
 
 * Elemi. A resin, which exudes from 
 incisions made, in dry weather, through the 
 bark of the amyris elemifera , a tree which 
 grows in America. It is wrapped in flag 
 leaves, in long roundish cakes, semi-transpa- 
 rent, and of a yellow colour. It has a faint 
 fragrance.* 
 
 Eliquation. An operation, by means of 
 which a more fusible substance is separated 
 from another which is less fusible. It consists 
 in the application of a degree of heat suffi- 
 cient to fuse the former, but not the latter. 
 
 Elutriation. This word is used by che- 
 mists to denote the process of washing, which 
 carries off' the lighter earthy parts, while the 
 heavier metallic parts subside to the botom. 
 
 * Emerald. This genus contains two 
 species, the prismatic and rhomboidal. 
 
 1. Prismatic Emerald, Euclase of Haiiy. 
 Its colours are green, of various shades, and 
 sometimes sky-blue. It is found only crys- 
 tallized. The primitive form is a prism of 
 133° 24'. Its secondary forms are, an 
 oblique four-sided prism, variously modifi- 
 ed by accuminations and truncations. The 
 lateral planes are more or less longitudinally 
 streaked, giving the prisms a reed-like ap- 
 pearance. Lustre splendent. Cleavage per- 
 fect, in the direction of the smaller diagonals 
 of the prism. Fracture small conchoidal. 
 Fragments tabular. Transparent Refracts 
 double. Harder than quartz, but softer 
 than topaz. Easily frangible. Sp. gr. 2.9 
 to 3.3. Loses transparency, and then melts 
 before the blow-pipe. Its constituents are 
 35 to 36 silica, 18 to 19 alumina, 14 to 15 
 glucina, 2 to 3 iron, and 27 to 31 loss. The 
 last is chiefly water, and in some measure 
 alkali. Found in Peru and Brazil. It is a 
 beautiful mineral, but too brittle for jewellery. 
 
 2. Rhomboidal Emerald, of which there 
 are two sub-species, the precious emerald 
 and the beryl. Precious emerald is well 
 characterized by its emerald-green colour, of 
 various depths. It is generally crystallized. 
 The primitive form is an equiangular six- 
 sided prism, on which various truncations 
 are found. The lateral planes are smooth ; 
 the terminal planes rough. Lustre splen- 
 dent* Cleavage straight and four- fold. 
 Fracture imperfect conchoidal. Transparent. 
 Moderate double refraction. Nearly as hard 
 as topaz. Sp. gr. 2.6 to 2.77. Heated to 
 a moderate degree, it becomes of a blue co- 
 lour, but recovers its tint on cooling. At a 
 high heat, it fuses into a white vesicular 
 glass. Its constituents are, silica 64.5, alu- 
 
EMU 
 
 EMU 
 
 mina 1(5, glucina 13, oxide of chrome 3.25, 
 lime 1.6, water 2. Klaproth found 1. of 
 oxide of iron. It occurs in drusy cavities, 
 along with iron pyrites, calcareous spar, and 
 quartz, in veins that traverse clay-slate. 
 The most beautiful emeralds come from 
 Peru. As a gem, it is valued next to the 
 ruby. See Beryl, in its alphabetical 
 place.* » 
 
 * Emery. A sub-species of rhomboidal 
 corundum. Its colour is intermediate be- 
 tween greyish- black, and bluish-grey. It 
 occurs massive and disseminated, and also 
 in granular concretions. Lustre glistening 
 and adamantine. Fracture fine grained un- 
 even. Translucent on the edges. So very 
 hard as to scratch topaz. Difficultly fran- 
 gible. Sp. gr. 4.0. Its constituents are 
 86 alumina, 3 silica, 4 iron, and 7 loss. In 
 Saxony, it occurs in beds of talc and stea- 
 tite. It occurs abundantly in the Isle of 
 Naxos, and also at Smvrna. It is used for 
 polishing hard minerals and metals. Its 
 fine powder is obtained by trituration and 
 elutriation.* 
 
 * Emetin. Digest ipecacuan root, first 
 in ether and then in alcohol. Evaporate 
 the alcoholic infusion to dryness, redissolve 
 in water, and drop in acetate of lead. Wash 
 the precipitate, and then diffusing it in wa- 
 ter, decompose by a current of sulphuretted 
 hydrogen gas. Sulphuret of lead falls to 
 the bottom, and the emetin remains in solu- 
 tion. By evaporating the water, this sub- 
 stance is obtained pure. 
 
 Emetin forms transparent brownish-red 
 scales. It has no smell, but a bitter acrid 
 taste. At a heat somewhat above that of 
 boiling water, it is resolved into carbonic 
 acid, oil and vinegar. It affords no ammo- 
 nia. It is soluble both in water and alcohol, 
 but not in ether; and uncrystallizable. It 
 is precipitated by proto- nitrate of mercury 
 and corrosive sublimate, but not by tartar 
 emetic. Half a grain of emetin acts as a 
 powerful emetic, followed by sleep ; six 
 grains vomit violently, and produce stupor 
 and death. The lungs and intestines are 
 inflamed. Pelletier and Magendie, Ann. 
 de Chimic et Physique , iv. 172.* 
 
 Emfyreuma. This term is applied to 
 denote the peculiar smell produced by a con- 
 siderable heat upon vegetable or animal sub- 
 stances in closed vessels, or when burned 
 under circumstances which prevent the ac- 
 cess of air to a considerable part of the mass, 
 and consequently occasion an imperfect com- 
 bustion, or destructive distillation of the 
 parts so covered up by the rest of the mass. 
 
 Emulsion. An imperfect combination of 
 oil and water, by the intervention of some 
 other substance capable of combining with 
 both these substances. The substances are 
 either saccharine or mucilaginous. 
 
 I here are two kinds of enamel, the opaque 
 
 and the transparent. Transparent enamels 
 are usually rendered opaque by adding put- 
 tv, or the white oxide of tin, to them. The 
 basis of all enamels is therefore a perfectly 
 transparent and fusible glass. The oxide of 
 tin renders this of a beautiful white, the per- 
 fection of which is greater when a small 
 quantity of manganese is likewise added. If 
 the oxide of tin be not sufficient to destroy 
 the transparency of the mixture, it produces 
 a semi-opaque glass, resembling the opal. 
 
 Yellow enamel is formed by the addition 
 of oxide of lead, or antimony. Kunckel 
 likewise affirms, that a beautiful yellow may 
 be obtained from silver. 
 
 Red enamel is afforded by the oxide of 
 gold, and also by that of iron. The former 
 is the most beautiful, and stands the fire 
 very well, which the latter does not. 
 
 Oxide of copper affords a green ; manga- 
 nese, a violet ; cobalt, a blue ; and iron, a 
 very fine black. A mixture of these diffe- 
 ferent enamels produces a great variety of 
 intermediate colours, according to their na- 
 ture and proportion. In this branch of the 
 art, the coloured enamels are sometimes 
 mixed with each other, and sometimes the 
 oxides are mixed before they are added to 
 the vitreous bases. 
 
 * In the transactions of the Society of 
 Arts for 1817, a valuable list of receipts for 
 enamel colours is given by Mr Ii. Wynn, 
 for the communication of which a premium 
 w r as awarded. The following are Mr Wynn’s 
 fluxes : — 
 
 No. 1. Red lead, 
 
 Calcined borax, 
 Flint powder, 
 Flint glass, 
 
 8 parts. 
 
 Ii 
 1 a 
 o 
 
 6 
 
 10 
 
 I 
 
 1 
 
 1 
 
 3 
 
 9 * 
 
 No. 2. Flint glass, 
 
 White arsenic, 
 
 Nitre, 
 
 No. 3. Red lead, 
 
 Flint glass, 
 
 No. 4. Red lead, 
 
 Borax not calcined, 5\ 
 
 Flint glass, 8 
 
 No. 5. Flint glass, 6 
 
 Flux, No. 2. 4 
 
 Red lead, 8 
 
 After the fluxes have been melted, they 
 should be poured on a flag stone, wet with a 
 sponge ; or into a large pan of clean w^ater, 
 then dried, and finely pounded in a biscuit- 
 w'are mortar for use. 
 
 Yellow enamel. 
 
 Red lead, 8 
 
 Oxide of antimony, i 
 
 White oxide of tin, \ 
 
 Mix the ingredients well in a biscuit- ware 
 mortar, and having put them on a piece of 
 Dutch tile in the muffle, make it gradually 
 red-hot, and suffer it to cool. Take of this 
 mixture 1, of flux No. 4. 1^ ; grind them in 
 
EPI 
 
 EQU 
 
 water for use. By varying the proportions 
 of red lead and antimony, different shades of 
 
 colour may be obtained. 
 
 
 Orange. 
 
 
 Red lead, 
 
 12 
 
 Red sulphate of iron, 
 
 1 
 
 Oxide of antimony, 
 
 4 
 
 Flint powder, 
 
 3 
 
 After calcining these without melting, 
 fuse 1 part of the compound with 2F of flux. 
 
 Dark red. 
 
 
 Sulphate of iron calcined dark, 1 
 
 Flux, No. 4. G parts ) 
 Colcothar, I \ 
 
 of this 3 
 
 Light red. 
 
 
 Red sulphate of iron, 
 Flux, No. 1. 
 
 White lead, 
 
 1 
 
 S 
 
 H 
 
 Brown. 
 
 Manganese, 
 
 H 
 
 Red lead, 
 
 
 Flint powder, 
 
 4 
 
 See transactions of the Society, or the 
 Phil. Mag. vol. 51. Mr Tilloch justly ob- 
 serves, that borax should be used sparingly, 
 as it causes efflorescence, and decay of the 
 enamel colours.* 
 
 Entrochi. A genus of extraneous fos- 
 sils, usually of about an inch in length, and 
 made up of a number of round joints, which, 
 when separate and loose, are called trochi- 
 tee : they are composed of the same kind of 
 plated spar with the fossil shells of the echi- 
 ni, which is usually of a bluish-grey colour, 
 and are very bright where fresh broken : 
 they are all striated from the centre to the 
 circumference, and have a cavity in the mid- 
 dle. They seem to be the petrified arms of 
 that singular species of the sea star- fish, 
 called Stella arborescens. 
 
 * Epidote. Pistacite. — Werner. A sub- 
 species of prismatoidal augite. — Jameson. 
 Acanticone, from Norway. Colours, pista- 
 chio green, and green of darker shades. 
 Massive, in distinct granular or fibrous con- 
 cretions, and crystallized. The primitive 
 form is an oblique four-sided prism, in which 
 the lateral planes meet at angles of 11*1° 37' 
 and G5° 23'. The secondary forms are, 1. 
 Very oblique four-sided prisms, bevelled on 
 the extremities. 2. That figure truncated 
 on the acute edges, and flatly bevelled on the 
 extremities. 5. A broad unequiangular 
 six-sided prism, variously acuminated or 
 truncated. 4. A very oblique four-sided 
 prism, truncated on the obtuse lateral edges, 
 and doubly acuminated on the extremities 
 by four planes. The crystals are sometimes 
 reed-like, and the lateral planes are longitu- 
 dinally streaked ; but the truncating, acu- 
 minating, and bevelling planes, are smooth, 
 and the terminal planes diagonally streaked. 
 Lustre splendent, internally inclining to 
 pearly. Cleavage twofold. Fracture flat 
 
 conchoidal. 1 ranslucent. Harder than 
 felspar, but not so hard as quartz. Brittle. 
 Sp* gr. 3.45. Before the blow- pipe it is 
 converted into a brown coloured scoria, 
 which becomes black with heat. Its consti- 
 tuents are silica 37, alumina 21, lime 15, 
 oxide of iron 24, oxide of manganese 1.5, 
 water 1.5. Laugier found 2 6 alumina, 20 
 lime, and 13 oxide of iron. It occurs in 
 primitive beds and veins, along with augite, 
 garnet, hornblende, calcareous spar, copper 
 pyrites, See. It is found in Arran, in se- 
 condary syenite and clay-slate ; in Mainland 
 of Shetland, in syenite ; in the island of 
 Icolmkill, in a rock composed of red felspar 
 and quartz ; in the syenite of Glencoe ; in 
 similar rocks among the Malvern hills; in 
 quartz, at Wallow Crag, near Keswick ; in 
 Cornwall ; Arendal, in Norway ; in Bava- 
 ria, France, &c.* 
 
 Epidermis. If the human skin be ma- 
 cerated in hot water, it separates into two 
 parts, the cutis, or true skin, and the epider- 
 mis, or scarf skin. The continued action of 
 warm water at length dissolves the cutis, 
 but does not affect the epidermis, neither 
 does alcohol. Caustic alkali, however, dis- 
 solves it. It resembles coagulated albumen. 
 
 Epsom Salt. Sulphate of magnesia. 
 
 * Equivalents (Chemical). A term hap- 
 pily introduced into chemistry by Dr Wol- 
 laston, to express the system of definite ra- 
 tios, in which the corpuscular subjects of this 
 science reciprocally combine, referred to a 
 common standard, reckoned unity. If, with 
 this profound philosopher, we assume oxy- 
 gen as the standard, from its almost univer- 
 sal relations to chemical matter, then calling 
 it unity, we shall have, in the following ex- 
 amples, these ratios reduced to their lowest 
 terms, in which the equivalents will be Prime 
 ratios : — 
 
 The lowest ratio, or equivalent 
 
 prime of oxygen being 1.000 
 
 That of hydrogen will be 0. 1 25 
 
 Offluor? - - 0.375 
 
 Of carbon, - - 0.750 
 
 Of phosphorus, - 1 . 500 
 
 Of azote, - - 1.750 
 
 Of sulphur, - - 2.000 
 
 Of calcium, - - 2.550 
 
 Of sodium, - - 2.950 
 
 Of potassium, - 4.950 
 
 Of copper, - - 8.00 
 
 Of barium, - - 8.75 
 
 Of lead, - - 13.00, &c. 
 
 The substances in the above table, suscep- 
 tible of reciprocal saturation, can combine 
 with oxygen or with each other, not only 
 in proportions corresponding to these num- 
 bers, but also frequently in multiple or sub- 
 multiple proportions. We have therefore 
 two distinct propositions on this interesting 
 subject. 
 
EQU 
 
 1 st, The general reciprocity of the satu- 
 rating proportions. 
 
 2d, The multiple and submultiple pro- 
 portions of prime equivalents, in which any 
 one body may unite with any other body, to 
 constitute successive binary compounds. 
 
 The first proposition, or grand law of che- 
 mical combination, was discovered by J. 13. 
 Richter of Berlin, about the year 1 7 92. The 
 second, of equal importance, and more re- 
 condite, was discovered so early as the year 
 1790, by Mr W. Higgins. 
 
 Richter inferred his from the remarkable and 
 well established fact, that two neutral salts, in 
 reciprocally decom posing each other, give birth 
 to two new saline compounds, always perfectly 
 neutral. Thus, sulphate of soda being added 
 to muriate of lime, will produce perfectly neu- 
 tral sulphate of lime and muriate of soda. 
 The conclusions he drew were, 1st, That the 
 quantities of two alkaline bases, adequate to 
 neutralize equal w eights of any one acid, are 
 proportional to the quantities of the same 
 bases, requisite to neutralize the same weights 
 of every other acid. For example, 6 parts 
 of potash, or 4 of soda, neutralize 5 of 
 sulphuric acid; and 4.4 of potash are ade- 
 quate to the saturation of 5 of nitric acid. 
 Therefore, to find the quantity of soda equi- 
 valent to the saturation of this Tveight of 
 nitric acid, w r e need not make experiments, 
 but merely compute it by the proportional 
 rule of Richter. Thus, as 6 : 4.4 : : 4 : 2.95 ; 
 or in words, as the potash equivalent to the 
 sulphuric acid, is to the potash equivalent 
 to the nitric acid, so is the soda equivalent 
 to the first, to the soda equivalent to the 
 second. And again, if 6.5 potash saturate 
 5 ot muriatic acid gas, how much soda, by 
 Richter’s rule, will be required for the same 
 effect. We say 6 : 6.5 : : 4 : : 4.5. 3dly, 
 If 10.9 potash combine with 5 of carbonic 
 acid, how much soda will be equivalent to 
 that effect.. Now, 6. 10.9 : : 4 : 7.26. Here, 
 therefore, we have found, that if 6 potash be 
 
 EQU 
 
 equivalent to 4 soda, in saturating 5 of sul- 
 phuric acid, this ratio of 6 to 4, or 5 to 2, 
 will pervade all the possible saline combina- 
 tions ; so that whatever be the quantity of 
 potash, requisite to saturate 5, 1 0, &c. of any 
 other acid, two-thirds of that quantity of 
 soda will suffice. 
 
 In the same manner let us find out, for five 
 of sulphuric, or of any one standard acid, 
 the saturating quantity of ammonia, magne- 
 sia, lime, strontites, barytes, peroxide of cop- 
 per, and the other bases ; then their propor- 
 tions to potash, thus ascertained, for this 
 acid, will, by arithmetical reduction, give 
 their saturating quantity of every other acid, 
 whose relation to potash, or indeed to any 
 one of these bases, is known. 
 
 The experimental verification of this most 
 important law, occupied Richter from the 
 year 1791 to the year 1802, in which period 
 he published, in successive parts, a curious 
 work, entitled the Geometry of the Chemical 
 Elements, or Principles of Stechiometry. 
 We might have expected greater accuracy in 
 his investigations, from the circumstance, 
 that Dr Wollaston selected his statement of 
 the constituents of nitre, in preference to 
 those of all other chemists, in the construc- 
 tion of his admirable table of chemical pro- 
 portions. 
 
 With indefatigable zeal Richter examined, 
 by experiment, each acid, in its relation to the 
 bases, and then compared the results with 
 those given by calculation, presenting both in 
 an extensive series of tables. 
 
 It is curious that he does not seem to have 
 been aw'are, that all his tables might have 
 been reduced into a single one, of 21 num- 
 bers, divided into two columns, by means of 
 which, every question relating to the includ- 
 ed articles, might be solved by the rule of 
 three, or a sliding scale. The following 
 table, computed by Fischer from Richter’s 
 last tables, was inserted by the celebrated 
 Berthollet in a note to his chemical statics. 
 
 Bases. 
 
 
 Oxygen = l. 
 
 Acids. 
 
 Oxygen = 1. 
 
 Alumina, 
 
 525 
 
 2.625 
 
 Fluoric, 
 
 427 
 
 2.135 
 
 Magnesia, 
 
 615 
 
 3.075 
 
 Carbonic, 
 
 577 
 
 2.885 
 
 Ammonia, 
 
 672 
 
 3.36 
 
 Sebacic, 
 
 706 
 
 3.530 
 
 lame, 
 
 793 
 
 3. 965 
 
 Muriatic, 
 
 712 
 
 S.560 
 
 Soda, 
 
 859 
 
 4.245 
 
 Oxalic, 
 
 755 
 
 3.77 5 
 
 Strontian, 
 
 1329 
 
 6.645 
 
 Phosphoric, 
 
 979 
 
 4.895 
 
 Potash, 
 
 1605 
 
 8.025 
 
 Formic, 
 
 988 
 
 4.94 
 
 Barytes, 
 
 2222 
 
 1.111 
 
 Sulphuric, 
 
 1000 
 
 5.000 
 
 
 
 
 Succinic, 
 
 1209 
 
 6.045 
 
 
 
 
 Nitric, 
 
 1405 
 
 7.025 
 
 
 
 
 Acetic, 
 
 1480 
 
 7.400 
 
 
 
 
 Citric, 
 
 1683 
 
 8.415 
 
 
 
 
 Tartareous, 
 
 1694 
 
 8.470 
 
EQU 
 
 EQU 
 
 I have added the two columns under oxy- 
 gen, from which we see at once, that with the 
 exception of the bases lime, strontian, and soda, 
 and the acids carbonic, muriatic, sulphuric, 
 nitric, citric, and tartaric ; the numbers given 
 by Richter do not form tolerable approxima- 
 tions to the true proportions. The object of 
 the above table was, to give directly the 
 quantities of acid and alkali requisite for 
 mutual saturation. For example, 1605, op- 
 posite to potash, is the quantity of that al- 
 kali equivalent to neutralize 427 of fluoric 
 acid, 577 carbonic, 712 muriatic, 1000 sul- 
 phuric, &c. Each column affords also pro- 
 gressively increasing numbers. Those near- 
 est the top have the greatest acid or alkaline 
 energies, as measured by their powers of 
 saturation. The column of Richter gives, 
 therefore, as far as the analytical means of 
 his time permitted, a table of the relative 
 weights of what has since been hypotheti- 
 cally called the atoms. 
 
 2. But two chemical constituents fre- 
 quently unite in different proportions, form- 
 ing distinct and often dissimilar compounds. 
 Thus, oxygen and azote constitute in one 
 proportion, nitrous oxide, the intoxicating gas 
 of Sir H. Davy ; in a second proportion, ni- 
 tric oxide, the nitrous gas of Priestley ; in a 
 third proportion, nitrous acid ; and in a fourth 
 proportion, nitric acid. Is there any law re- 
 gulating these various compounds ; so that 
 knowing the first proportion, we may infer 
 the whole series? This question was first 
 answered in a work containing many curious 
 anticipations of discoveries, to which poste- 
 rior writers have laid claim ; I mean Mr 
 Higgins’s Comparative View of the Phlogis- 
 tic and Antiphlogistic Theory, printed in 
 1788, and published early in 1789. Besides 
 some additional facts, decisively hostile to 
 the hypothesis of phlogiston, this publication 
 distinctly advances the doctrine of multiple 
 proportion, with regard to the successive com- 
 pounds of the same constituents. Ihis was 
 likewise interwoven, with new and ingenious 
 views concerning gaseous and atomical com- 
 bination. Mr Higgins having felt himself 
 aggrieved at seeing discoveries, clearly an- 
 nounced by him in i789, brought forward 
 nineteen years afterwards by Mr Dalton, in 
 his own name, published in 1814 a book, 
 entitled, Experiments and Observations on 
 the Atomic Theory and Electrical Pheno- 
 mena. In this work he gives numerous 
 quotations from his Comparative View , which 
 abundantly establish his claim of priority to 
 the discovery of multiple proportions, and the 
 atomic thedry of chemistry. It is no fault 
 of Mr Higgins, that his first work partook 
 of the imperfect analyses of the day. Indeed 
 we have reason, on the contrary, to be sur- 
 prised at his rejection of many errors then 
 sanctioned by high authority, and his pro- 
 mulgation of many new truths, which might 
 
 appear, to contemporary writers, insulated, 
 or of little consequence, but to which subse- 
 quent researches have given a due place and 
 importance in the system of chemical know- 
 ledge. Who would deny to Columbus the 
 glory of discovering a new world, merely be- 
 cause the means of research placed within his 
 power, did not permit him to explore its ex- 
 tensive coasts? Is not that glory on the con- 
 trary greatly enhanced, by the very early pe- 
 riod at which ' the discovery was achieved, 
 while navigation as a science was still un- 
 known ? 1 shall quote a few passages, as ho 
 
 gives them, from his Comparative View, 
 which I think are decisive in this funda- 
 mental discussion. 
 
 “ Hepatic gas (sulphuretted hydrogen), as 
 shall be shewn, is hydrogen in its full extent, 
 holding sulphur in solution.” This fact, of 
 hydrogen not changing its volume, by com- 
 bining with sulphur, has been marked among 
 the valuable discoveries of later times. 
 
 “ Therefore, 100 grains of sulphur, re- 
 quire only 100 or 102 of the dry gravitating 
 matter of oxygen gas, to form sulphurous 
 acid. As sulphurous acid gas is very little 
 more than double the specific gravity of oxy- 
 gen gas, we may conclude, that the ultimate 
 particles of sulphur and oxygen contain the 
 same quantity of matter ; for oxygen gas 
 suffers no considerable diminution of its bulk, 
 by uniting to the quantity of sulphur neces- 
 sary for the formation of sulphurous acid. 
 It contracts 1-1 1th, as shall he shewn here- 
 after.” Compare with the above statements 
 the following from Dr Thomson’s System, 
 published in 1807. “ If this analysis bo 
 
 precise, it follows, that 100 cubic inches of 
 hydrogen gas, in order to be converted into 
 sulphuretted hydrogen, combine with 7.69 
 grains of sulphur, and are converted into 
 about 26.6 cubic inches; so that hydrogen 
 gas, by dissolving sulphur, is reduced to little 
 more than one-fourth of its original bulk. 
 Vol. i. p. 92. Sir II. Davy has since proved, 
 by accurate experiments, that hydrogen, in its 
 conversion into sulphuretted hydrogen, does 
 not change its bulk, agreeably to Mr Hig- 
 gins’s early enunciation. “ But as we know 
 the constituents of sulphuric acid, it is easy 
 thence to deduce the following as the pro- 
 portion of the ingredients of sulphurous, 
 acid : — 
 
 68 sulphur, 
 
 82 oxygen. 
 
 100 ” 
 
 System of Chemistry, 1807, vol. ii. p. 179. 
 The last is the result of l)r Thomson s own 
 experiments. Its true composition is now 
 known to be 100 of the gravitating matter of 
 oxygen to 100 ot sulphur, in conformity 
 with Mr Higgins. 
 
 The elementary proposition of Mr Dal- 
 ton’s atomical hypothesis, seems to be most 
 
EQU 
 
 explicitly announced in the following para- 
 graph of Mr Higgins. 
 
 il As two cubic inches of hydrogen gas 
 require but one cubic inch of oxygen gas to 
 condense them to water, we may presume, 
 that they contain an equal number of divi- 
 sions, and that the difference of the specific 
 gravity of those gases depends on the size of 
 their respective particles ; or we must sup- 
 pose, that an ultimate particle of hydrogen 
 requires two or three or more particles of 
 oxygen to saturate it. Were this the case, 
 water, or its constituents, might be obtained 
 in an intermediate state of combination, like 
 those of sulphur and oxygen, or azote and 
 oxygen, &c. This appears to be impossible ; 
 for in whatever proportion we mix hydrogen 
 or oxygen gases, or under whatever circum- 
 stances we unite them, the result is invaria- 
 bly the same. Water is formed, and the 
 surplus of either of the gases is left behind 
 unchanged.” — “ From these circumstances, 
 we have sufficient reason to conclude, that 
 water is composed of a single ultimate par- 
 ticle of oxygen, and an ultimate particle of 
 hydrogen, and that its atoms are incapable 
 of uniting to a third particle of either of its 
 constituents.” 
 
 Mr Higgins inculcates very strongly, that 
 when a body is capable of combining with 
 another in two proportions, the third particle 
 introduced is held by a much weaker affinity 
 than that which unites the particles of the 
 first or true binary compound. 
 
 “ In my opinion, the most perfect nitrous 
 acid contains 5 of oxygen and 1 of azote. 
 Nitrous gas, according to Kirwan, contains 
 2 volumes of oxygen gas, and 1 of azotic 
 gas. According to Lavoisier, 100 grains of 
 nitrous gas contain 32 grains of azote, and 
 68 of oxygen. I am of the former philoso- 
 pher’s opinion. I also am of opinion, that 
 every primary particle of azote is united to 2 
 of oxygen, and that the molecule thus form- 
 ed, is surrounded with one common atmos- 
 phere of caloric. 
 
 “ As this requires demonstration, let A in 
 the annexed diagram represent an ultimate 
 particle of azote, which attracts oxygen with 
 the force of 3 ; 
 
 Let a be a particle of oxygen, whose attrac- 
 tion to A we will suppose to be 3 more ; 
 hence they will unite with the force of 6 ; 
 the nature of this compound will be here- 
 after explained. Let us consider this to be 
 the utmost force of attraction that can sub- 
 sist between oxygen and azote. We will now 
 suppose a second particle of oxygen b to com- 
 bine with A ; they will only unite with the 
 force of 4i.” “ This I consider to be the 
 
 real structure of a molecule of nitrous gas. 
 Let a third particle of oxygen c unite to A, 
 
 EQU 
 
 it will combine only with the force of 4, 
 This is the state of the red molecules of ni- 
 trous vapour, or when condensed, the red ni- 
 trous acid.” “ We will suppose a fourth 
 particle of oxygen d to combine with A ; it 
 will unite with the force of 3^, and so on 
 with the rest of the particles of oxygen as 
 the diagram represents. This I consider to 
 be the state of a molecule of the pale or 
 straw-coloured nitrous acid. 
 
 “ When a fifth particle of oxygen e unites, 
 the force of union existing between the par- 
 ticles of the molecule is still diminished as is 
 represented by the diagram. The fractions 
 shew that the chemical attraction of azote 
 for oxygen is nearly exhausted. This is the 
 state of colourless nitrous acid ; and, in my 
 opinion, no more oxygen can unite to the 
 azote, having its whole force of attraction 
 expended in the particles a , 6, c, d, e. This 
 illustrates the nature of saturation or definite 
 proportions.” 
 
 “ We can readily perceive from the fore- 
 going demonstrations, that oxygen is retain- 
 ed with less force in the colourless nitrous 
 acid than in the straw-coloured ; and the 
 latter acid retains it with less force than the 
 red nitrous acid ; and nitrous gas holds it 
 with still more force than the red nitrous 
 acid. This accounts for the separation of 
 oxygen gas from the colourless nitrous acid 
 (nitric acid) when exposed to the sun, at the 
 same time that the acid becomes coloured. 
 Nitrous acid in any other state will afford no 
 oxygen, when exposed to the sun.” 
 
 “ Why the gaseous oxide should be more 
 soluble in w'ater than the nitrous gas, is what 
 I cannot account for, unless it be occasioned 
 by the smaller size of its calorific atmos- 
 pheres, which may admit its atoms to come 
 within the gravitating influence of that 
 fluid.” 
 
 It is impossible to deny the praise, of sin- 
 gular ingenuity, and justness, to the above 
 passages ; and every one must be struck 
 with their analogy, both as to atomical doc- 
 trines, and the calorific atmospheres of gases, 
 single and compound, with the language and 
 views expanded at full length in Mr Dal- 
 ton’s new system of Chemical Philosophy, 
 first framed about the year 1803, and pub- 
 lished in 1808. It appears that this philo- 
 sopher, after meditating on the definite pro- 
 portions, in which oxygen was shewn by M. 
 Proust to exist in the two oxides of the same 
 metal, on the successive combinations of 
 oxygen and azote, and the proportions of 
 various other chemical compounds, was final- 
 ly led to conclude, that the uniformity which 
 obtains in corpuscular combinations, re- 
 sults from the circumstance, that they con- 
 sist of one atom of the one constituent, 
 united generally with one atom of the other, 
 or with two or three atoms. And he further 
 
EQU 
 
 inferred, that the relative weights of these 
 ultimate atoms might be ascertained from 
 the proportion of the two constituents in a 
 neutral compound. 
 
 Chemistry is unquestionably under great 
 obligations to Mr Dalton, for the pains with 
 which he collated the various analyses of 
 chemical bodies, by different investigators; 
 and for establishing, in opposition to the 
 doctrine of indefinite affinity, taught by the 
 illustrious Berthollet, that the different com- 
 pounds of the same principles did not pass 
 into each other by imperceptible gradations, 
 but proceeded, per saltum, in successive 
 proportions, each a multiple of the first. 
 By correcting and extending Richter’s scale 
 of reciprocal saturation, and reviving Mr 
 Higgins’ long neglected discovery of mul- 
 tiple proportion, Mr Dalton has been no 
 mean contributor to the advancement of the 
 science. It is difficult to say how far his 
 figured groups of spherical atoms have been 
 beneficial or not. They may have had some 
 use in aiding the conception of learners, and 
 perhaps in giving a novel and imposing air 
 to the atomical fabric. But their arrange- 
 ment, and even their existence, are altoge- 
 ther hypothetical, and therefore ought to 
 have no place in physical demonstrations. 
 
 That water is a compound of an atom of 
 oxygen and an atom of hydrogen, is assumed 
 by Mr Dalton as the basis of his system. 
 But two volumes of hydrogen here combine 
 with one of oxygen. He therefore infers, 
 that an atom of hydrogen occupies double 
 the bulk, in its gaseous state, of an atom of 
 oxygen. These assumptions are obviously 
 gratuitous. I agree with Dr Prout in think- 
 ing that Sir H. Davy has taken a more 
 philosophical view of this subject. Guided 
 by the strict logic of chemistry, he places no 
 hypothesis at the foundation of his fabric. 
 
 Experiment shews, 1st, That in equal vo- 
 lumes oxygen weighs 1 6 times more than 
 hydrogen ; and 2dly, That water is formed by 
 the union of one volume of the former, and 
 two volumes of the latter gas, or by weight 
 of 8 to 1. We are not in the least autho- 
 rized to infer from this that an atom of oxy- 
 gen weighs 8 times as much as an atom of 
 hydrogen. For aught we know, water may 
 be a compound of 2 atoms of hydrogen, and 
 1 of oxygen ; in which case we should have 
 the proportion of the weights of the atoms, 
 as given by equal volumes, namely, 1 to 16. 
 There is no good reason for fixing on one 
 compound of hydrogen, more than on ano- 
 ther, in the determination of the basis of the 
 equivalent scale. If w r e deliberate on that 
 combination of hydrogen in which its agency 
 is apparently most energetic, namely, that 
 with chlorine, we would surely never think 
 of pitching on tiro volumes as its unity or 
 least proportion of combination ; for it is one 
 volume of hydrogen which unites with one 
 
 EQU 
 
 volume of chlorine, producing two volumes 
 of muriatic gas. Here, therefore, we see 
 that one volume of hydrogen is quite ade- 
 quate to effect, in an active gaseous body of 
 equal bulk, and 36 times its weight, an en- 
 tire change of properties. Should we as- 
 sume in gaseous chemistry, 2 volumes of 
 hydrogen, as the combining unit, or as re- 
 presenting an atom ; then it should never 
 unite in 3 volumes, or an atom and a half 
 with another gas. Ammonia, however, is a 
 compound of 3 volumes of hydrogen with 1 
 of azote; and if 2 volumes of hydrogen to 1 of 
 oxygen be called an atom to an atom, surely 
 3 volumes of hydrogen to 1 of azote should 
 be called an atom and a half to an atom. 
 Yet the Daltonian Commentator, on the se- 
 cond occasion, counts one volume an atom of 
 hydrogen, and on the first, two volumes an 
 atom. 
 
 We would steer clear of all these gratuitous 
 assumptions and contradictions, by making 
 a single volume of hydrogen represent its 
 atom, or prime equivalent. “ There is an 
 advantage,” says Dr Prout, “ in considering 
 the volume of hydrogen equal to the atom, 
 as, in this case, the specific gravities of most, 
 or perhaps all elementary substances, (hy- 
 drogen being one), will either exactly coin- 
 cide with, or be some multiple of the weights 
 of their atoms ; whereas, if we make the 
 volume of oxygen unity, the weights of the 
 atoms of most elementary substances, except 
 oxygen, will be double that of their specific 
 gravities, with respect to hydrogen. The 
 assumption of the volume of hydrogen, be- 
 ing equal to the atom, will also enable us to 
 find more readily, the specific gravities of 
 bodies in their gaseous state, (either with 
 respect to hydrogen, or atmospheric air), by 
 means of Dr Wollaston’s logometric scale. 
 
 “ If the views we have ventured to ad- 
 vance be correct, we may almost consider the 
 rrourr uXn of the ancients to be realized in 
 hy r drogen ; an opinion, by the by, not alto- 
 gether new. If we actually consider this to 
 be the case, and further consider the specific 
 gravities of bodies, in their gaseous state, to 
 represent the number of volumes condensed 
 into one ; or in other words, the number of 
 the absolute weight of a single volume of 
 the first matter vX*) wdiich they con- 
 
 tain, which is extremely probable ; multiples 
 in weight must always indicate multiples in 
 volume, and vice versa ; and the specific gra- 
 vities or absolute weights of all bodies in a 
 gaseous state, must be multiples of the spe- 
 cific gravity, or absolute weight of the first 
 matter, vXvi), because all bodies in a 
 
 gaseous state, which unite with one another, 
 unite with reference to their volume.” 
 
 From these ingenious observations, we per- 
 ceive the singular felicity of judgment, with 
 which Sir H. Davy made choice of tlx* 
 single volume of hydrogen, for the unit of 
 
EQU 
 
 primary combination, in his elements ot 
 chemical philosophy. 
 
 Mr Dalton’s prelections on the atomic the- 
 ory, and Dr Thomson's commentary, had ex- 
 cited but a feeble sensation in the chemical 
 world. That part of his system which treated 
 on caloric, was blended with so much mere hy- 
 pothesis, that chemists transferred a portion of 
 the scepticism thus created, to his collation of 
 primary and multiple combinations. It was 
 Dr Wollaston who first decided public opinion 
 in favour of the doctrine of multiple propoi- 
 tions, by his elegant paper on super-acid, and 
 sub-acid salts, inserted in the Philosophical 
 Transactions for 1808. I he object of the 
 atomic theory has been no where so happily 
 stated as by this philosopher, in the following 
 sentence : 
 
 “ But, since the publication of Mr Dal- 
 ton’s theory of chemical combination, as ex- 
 plained and illustrated by Dr Thomson, 
 (System, 5d edit.), the inquiry which I had 
 designed appears superfluous, as all the facts 
 I had observed are but particular instances 
 of the more general observation of Mr Dal- 
 ton, that in all cases the simple elements of 
 bodies are disposed to unite atom to atom 
 singly, or if either is in excess, it exceeds by 
 a ratio to be expressed by some simple mul- 
 tiple of the number of its atoms.” 
 
 It is evident from this passage, that the 
 principle which presented itself to Mr Dal- 
 ton, on a review of the labours of other che- 
 mists, had really occurred to Dr Wollaston 
 from his own , and that he would unques- 
 tionably have been speedily led to its full 
 developement. If Mr Dalton had ever chan- 
 ced to look into the neglected book of Hig- 
 gins, there would have been little merit in 
 his anticipation of what the advancement of 
 analytical precision would infallibly have re- 
 vealed in a very short period. 
 
 Dr Wollaston, in the above decisive pa- 
 per, demonstrates, that in the sub-carbo- 
 nate and crystallized carbonate of potash, 
 the relation of the carbonic acid to the 
 base, in the first, is exactly one-half of what 
 it is in the second. -The same law is shewn 
 to hold with regard to the two carbonates of 
 soda, and the two sulphates of potash ; and 
 being applied to his experiments on the com- 
 pounds of potash and oxalic acid, leads him 
 to conclude, that the neutral oxalate may he 
 considered as consisting of 2 particles potash, 
 1 acid; the binoxalate as 1 and 1, or 2 
 potash, with 2 acid; the quadroxalate as 1 
 and 2, or 2 potash, with 4 acid. 
 
 We cannot withhold from our readers 
 the following masterly observations, which 
 must make every one regret, that the first 
 developement of the atomic theory had not 
 fallen into such philosophical hands. 
 
 “ But an explanation which admits a 
 double share of potash in the neutral salts, 
 (the oxalates), is not altogether satisfactory ; 
 
 and I am farther inclined to think, that when 
 our views are sufficiently extended, to enable 
 us to reason with precision concerning the 
 proportions of elementary atoms, we shall 
 find the arithmetical relation alone will not 
 be sufficient to explain their mutual action, 
 and that we shall be obliged to acquire a 
 geometrical conception of their relative ar- 
 rangement, in all the three dimensions of 
 solid extension. 
 
 *‘ For instance, suppose the limit to the ap- 
 proach of particles, to he the same in all di- 
 rections, and hence their virtual extent to be 
 spherical, (which is the most simple hypo- 
 thesis) ; in this case, when different sorts 
 combine singly, there is hut one mode of 
 union. If they unite in the proportion of 
 two to one, the two particles will natu- 
 rally arrange themselves at opposite poles 
 of that to which they unite. If they be 
 three, they might be arranged with re- 
 gularity at the angles of an equilateral tri- 
 angle, in a great circle surrounding the single 
 spherule ; but in this arrangement, for want 
 of similar matter at the poles of this circle, 
 the equilibrium would be unstable, and 
 would he liable to be deranged by the slight- 
 est force of adjacent combinations ; but, when 
 the number of one set of particles exceeds in 
 the proportion of 4 to 1 , then, on the con- 
 trary, a stable equilibrium may again take 
 place, if the four particles are situated at the 
 angles of the four equilateral triangles com- 
 posing a regular tetrahedron. 
 
 “ But as this geometrical arrangement of 
 the primary elements of matter is altogether 
 conjectural, and must rely for its confirma- 
 tion or rejection upon future inquiry, T am 
 desirous that it should not be confounded 
 with the results of the facts and observations 
 related above, which are sufficiently distinct 
 and satisfactory with respect to the existence 
 of the law of simple multiples. It is per- 
 haps too much to hope, that the geometrical 
 arrangement of primary particles will ever 
 be perfectly known ; since, even admitting 
 that a very small number of these atoms 
 combining together, would have a tendency 
 to arrange themselves in the manner I have 
 imagined; yet until it is ascertained how 
 small a proportion the primary particles 
 themselves bear to the interval between 
 them, it may he supposed that surrounding 
 combinations, although themselves analogous, 
 might disturb this arrangement; and in that 
 case, the effect of such interference must 
 also be taken into the account, before any 
 theory of chemical combination can he ren- 
 dered complete.” 
 
 I am not aware, that any chemist has ad- 
 duced experimental evidence, to prove that 
 a “ stable equilibrium may again take place, 
 if the four particles are situated at the angles 
 of the four equilateral triangles composing 
 a regular tetrahedron.” I have, therefore, 
 
EQU 
 
 much pleasure In referring to my researches 
 on the constitution of liquid nitric acid, as 
 unfolding a striking confirmation of Dr 
 \\ ollaston s true philosophy of atomical 
 combination. When I wrote the following 
 sentence, I had no recollection whatever of 
 Dr Wollaston’s profound speculations on 
 tetrahedral arrangement. — “ We perceive, 
 that the liquid acid of 1.420, composed of 
 4 primes of water + * of dry acid, pos- 
 sesses the greatest power of resisting the in- 
 fluence of temperature to change its state. 
 It requires the maximum heat to boil it, 
 when it distils unchanged ; and the maxi- 
 mum cold to effect its congelation.” See 
 Acid (Nitric), in this Dictionary. 
 
 Here we have a fine example of the stability 
 of equilibrium, introduced by the combina- 
 tion of four atoms with one. The discovery 
 which I had also the good fortune to make 
 with regard to the constitution of aqueous 
 sulphuric acid, that the maximum condensa- 
 tion occurred, when one atom of the real 
 acid was combined with three atoms of 
 water, is equally consonant to Dr Wollas- 
 ton’s views. “ But in this arrangement,” 
 says Dr Wollaston, “ for want of similar 
 matter at the poles of this circle, the equili- 
 brium would be unstable, and would be 
 liable to be deranged by the slightest force 
 of adjacent combinations.” Compare with 
 this remark, the following sentence from 
 my paper on sulphuric acid, as published in 
 the Journal of Science, October 1817. — 
 “ The terms of dilution are, like logarithms, 
 a series of numbers in arithmetical progres- 
 sion, corresponding to another series, name- 
 ly, the specific gravities, in geometrical pro- 
 gression. For a little distance on both 
 sides of the point of greatest condensation, 
 the series converges with accelerated velo- 
 city, whence the 10 or 12 terms on either 
 hand, deviate a little from experiment.” 
 Pa^e 126. Or in other words, a small addi- 
 
 O 
 
 tion of water or of acid to the above atomic 
 group, produces a great change on the de- 
 gree of condensation ; which accords with 
 the position “ that the equilibrium would 
 be liable to be deranged by the slightest 
 force of adjacent combinations.” 
 
 While considering this part of Dr \\ ollas- 
 ton’s important paper, let me advert to the 
 curious facts pointed out in the article Ni- 
 tric Acid, relative to the compound of one 
 atom of dry acid and seven atoms water. 
 In my paper on the subject, published in the 
 eighth number of the Journal of Science, I 
 shewed, that this liquid combination was ac- 
 companied with the greatest condensation of 
 volume, and the greatest disengagement of 
 heat. In composing this Dictionary, 1 cal- 
 culated, for the first time, the atomical con- 
 stitution of the nitric acids employed by Mr 
 Cavendish, for congelation ; and found with 
 great satisfaction, that the same proportion 
 
 EQU 
 
 which had exhibited, in my experiments, the 
 most intense reciprocal action, as was indi- 
 cated both by the aggregation of particles, 
 and production of heat, was likewise that 
 which most favoured solidification. Such 
 acid congeals at — 2° ; but when either 
 stronger or weaker, it requires a much lower 
 temperature for that effect. 
 
 3. The next capital discovery’ in multiple 
 proportions, was made by M. Gay Lussac, 
 in 1808, and published by him in the second 
 volume of the Memoires d’ Arcueil. After 
 
 detailing a series of fine experiments, he de- 
 duces tlie following important inferences . 
 “ Thus it evidently appears, that all gases, 
 in their mutual action, uniformly combine 
 in the most simple proportions; and we 
 have seen, in fact, in all the preceding ex- 
 amples, that the ratio of their union is that 
 of 1 to 1, of 1 to 2, or of 1 to 3, by volume. 
 It is important to observe, that when we 
 consider the weights, there is no simple and 
 definite relation between the elements of a 
 first combination ; it is only when there is a 
 second between these same elements, that 
 the new proportion of that body which has 
 been added, is a multiple of the first. Gases, 
 on the contrary, in such proportions as can 
 combine, give rise alw’ays to compounds 
 whose elements are in volume multiples the 
 one of the other. 
 
 “ Not only do the gases combine in very 
 simple proportions, as w r c have just seen, 
 but moreover, the apparent contraction of 
 volume which they experience by combina- 
 tion, has likewise a simple relation with the 
 volume of the gases, or rather with the vo- 
 lume of one of them.” 
 
 By supposing the contraction of volume 
 of the two gaseous constituents of water to 
 be only equal to the whole volume of oxy- 
 gen added, he found the ratio of the density 
 of steam to be to that of air as 1 0 to 1 6 ; a 
 computed result in exact correspondence 
 with the experimental result lately obtained 
 in an independent method, by the same ex- 
 cellent philosopher. “ Ammoniacal gas is 
 composed in volume,” says he, “ of 3 parts 
 of hydrogen and 1 of azote, and its density, 
 compared to that of air, is 0.596 ; but if we 
 suppose the apparent contraction to be one- 
 half of the total volume, we find 0.594 for its 
 density. Thus it is demonstrated by this 
 nearly perfect accordance, that the apparent 
 contraction of its elements is precisely one- 
 half of the total volume or rather double the 
 volume of azote.” INI. Gay Lussac subjoins 
 to his beautiful memoir a table of gaseous 
 combination, which, with some modifications 
 derived from subsequent researches, will be 
 inserted under the article Gas. 
 
 The same volume of the Memoires pre- 
 sents another important discovery of 31. Gay 
 Lussac, on the subject of equivalent pro- 
 portions. It is entitled, On the relation 
 
EQU 
 
 P 
 
 which exists between the oxidation of metals, 
 and their capacity of saturation for the acids. 
 He here proves, by a series of experiments, 
 that the quantity of acid which the different 
 metallic oxides require for saturation, is in 
 the direct ratio of the quantity of oxygen, 
 which they respectively contain. “ I have 
 arrived at this principle,” says he, “ not by 
 the comparison of the known proportions of 
 the metallic salts, which are in general too 
 inexact to enable us to recognize this law, 
 but by observing the mutual precipitation of 
 the metals, from their solutions in acids.” 
 
 When we precipitate a solution of acetate 
 of lead, by a plate of zinc, there is formed a 
 beautiful vegetation known under the name 
 of the tree of Saturn; and which arises from 
 the reduction of the lead by a galvanic pro- 
 cess, as was first shewn by Silvester and Grot- 
 thus. We obtain at the same time a solu- 
 tion of acetate of zinc, equally neutral with 
 that of the lead, and entirely exempt from this 
 last metal. No hydrogen, or almost none, 
 is disengaged during the precipitation ; which 
 proves, that the whole oxygen necessary to 
 the zinc, for its becoming dissolved and sa- 
 turating the acid, has been furnished to it by 
 the lead. 
 
 If we put into a solution of sulphate of 
 copper, slightly acidulous, bright iron turn- 
 ings in excess, the copper is almost instantly 
 precipitated; the temperature rises, and no 
 gas is disengaged. The sulphate of iron 
 which we obtain, is that in which the oxide 
 is at a minimum, and its acidity is exactly 
 the same as that of the sulphate of copper 
 employed. 
 
 AVe obtain similar residts, by decomposing 
 the acetate of copper by lead, especially w-ith 
 the aid of heat. But since the zinc preci- 
 pitates the lead from its acetic solution, w’e 
 may conclude, that it would also precipitate 
 copper, from its combination with the acetic 
 acid. Experience is here in perfect accord- 
 ance with theory. 
 
 We know with what facility copper preci- 
 pitates silver, from its nitric solution. All 
 the oxygen which it needs for its solution, is 
 furnished to it by the oxide of silver; for no 
 gas is disengaged, and the acidity is un- 
 changed. r j he same thing happens with 
 copper, in regard to nitrate of mercury, and 
 to cobalt, in regard to nitrate of silver. 
 In these last examples, as in the preceding, 
 the precipitating metal, finds in the oxide of 
 the metal, which it precipitates, all the oxy- 
 gen which is necessary to it for its oxidize- 
 rnent, and for neutralizing to the same de- 
 gree the acid of the solution. 
 
 These incontestable facts naturally con- 
 duct to the principle announced above, that 
 the acid in the metallic salts, is directly pro- 
 portional to t Tie oxygen in their oxides. In 
 the precipitation ol one metal by another, 
 the quantity of oxygen in each oxide remains 
 
 EQU 
 
 the same, and consequently the larger dosa 
 of oxygen the precipitating metal takes, the 
 less metal will it precipitate. 
 
 M. Gay Lussac next proceeds to shew', 
 with regard to the same metals at their dif- 
 ferent stages of oxidizement, that they re- 
 quire of acid, a quantity precisely propor- 
 tional to the quantity of oxygen they may 
 contain; or that the acid in the salts, is 
 exactly proportional to the oxygen of the 
 oxides. A very important result of this 
 law, is the ready means it affords of deter- 
 mining the proportions of all the metallic 
 salts. The proportions of one metallic salt, 
 and the oxidation of the metals, being given, 
 we may determine those of all the salts of 
 the same genus; or the proportions of acid, 
 and of oxide, of all the metallic salts, and the 
 oxidation of a single metal being given, we 
 can calculate the oxidation of all the rest. 
 Since the peroxides require most acid, we can 
 easily understand how the salts containing 
 them, should be in general more soluble than 
 those with the protoxide. 
 
 M. Gay Lussac concludes his memoir 
 with this observation. When we precipitate 
 ametallic solution, by sulphuretted hydrogen, 
 either alone or combined with an alkaline 
 base, w r e obtain a sulphuret or a metallic hy- 
 drosulphuret. In the first case, the hydro- 
 gen of the sulphuretted hydrogen combines 
 with all the oxygen of the oxide, and the 
 sulphur forms a sulphuret with the metal; 
 in the second case, the sulphuretted hydro- 
 gen combines directly with the oxide, without 
 being decomposed, and its proportion is such, 
 that there is sufficient hvdrogen to saturate 
 all the oxygen of the oxide. The quantity 
 of hydrogen neutralized, or capable of being 
 so, depends therefore on the oxidation of the 
 metal, as well as the quantity of the sulphur, 
 which can combine with it. Of consequence, 
 the same metal forms as many distinct sul- 
 phurets, as it is susceptible of distinct stages 
 of oxidation in its acid solutions. And as 
 these degrees of oxidation are fixed, we may 
 also obtain sulphurets, of definite propor- 
 tions, which w'e can easily determine, accord- 
 ing to the quantity of oxygen to each metal, 
 and the proportions of sulphuretted hydro- 
 gen. 
 
 The next chemist who contributed essen- 
 tially to the improvement of the equivalent 
 ratios of chemical bodies, w»as Berzelius. 
 By an astonishing number of analyses, exe- 
 cuted for the most part with remarkable pre- 
 cision, he enabled chemical philosophers to 
 fix with corresponding accuracy, the equiva- 
 lent ratios reduced to their lowest terms, 
 lie himself took oxygen as the unit of pro- 
 portion. 
 
 The results of all this emulous culti- 
 vation, were combined and illustrated with 
 original researches, by Sir H. Davy, in bis 
 Elements of Chemical Philosophy published 
 
EQU 
 
 EQU 
 
 
 in 1812. In this system of truths, which 
 will never become obsolete, we find the 
 claims of Mr Higgins to the discovery of 
 the atomic theory justly advocated. 
 
 But what peculiarly characterizes this 
 chemical work, is the sound antihypothetical 
 doctrines which it inculcates on chemical 
 combination. “ Mr Higgins,” says Sir II. 
 “ has supposed that water is composed of 
 one particle of oxygen and one of hydrogen, 
 and Mr Dalton of an atom each ; but in the 
 doctrine of proportions derived from facts, it 
 is not necessary to consider the combining 
 bodies, either as composed of indivisible par- 
 ticles, or even as always united, one and one, 
 or one and two, or one and three proportions. 
 Cases will be hereafter pointed out, in which 
 the ratios are very different ; and at present, 
 as we have no means whatever of judging 
 either of the relative numbers, figures, or 
 weights, of those particles of bodies which 
 are not in contact, our numerical expressions 
 ought to relate only to the results of experi- 
 ments.” 
 
 He conceives that the calculations will be 
 much expedited, and the formulas rendered 
 more simple, by considering the smallest 
 proportion of any combining body, namely, 
 that of hydrogen, as the integer. This radi- 
 cal proportion of hydrogen, is the kvootyi vXr\ 
 of the ancient philosophers. 
 
 It has been objected by some, to our as- 
 suming hydrogen as the unit, that the num- 
 bers representing the metals, would become 
 inconveniently large. But this, could never 
 be urged by any person, acquainted with the 
 theory of numbers. For in what respect is it 
 more convenient to reckon barium 8.75 on 
 the atomic scale, or 8.75 X 16 = HO on 
 Sir H. Davy’s scale of experiment? or is it 
 any advantage to name, with Dr Thomson, 
 tin = 7.375, or to call it 118, on the plan of 
 the English philosopher? If the combining 
 ratios of all bodies be multiples of hydrogen, 
 as is probable, why not take hydrogen as the 
 unit? I think this question will not be an- 
 swered in the negative, by those who practise 
 the reduction of chemical proportions. Ihe 
 defenders of the Daltonian hypothesis, that 
 water consists of one atom oxygen to one 
 atom hydrogen, may refer to Dr Wollaston s 
 scale, as authority for taking oxygen as the 
 unit. But that admirable instrument, which 
 lias at once subjected thousands of chemical 
 combinations to all the dispatch and precision 
 of logometric calculation, is actually better 
 adapted to the hydrogen unit, than to the 
 oxygen. For if we slide down the middle 
 rule, till 10 on it stand opposite to 10 hydro- 
 gen on the left side, every thing on the scale 
 is given in accordance with Sir II. Davy’s 
 system of primary proportions, and M. Gay 
 Laissac’s theory of gaseous combination. 
 This valuable concurrence, as is well pointed 
 
 out by Dr Prout, we lose, by adopting the 
 volume of oxygen as radix. 
 
 In the first part of the Phil. Trans, for 
 1814, appeared Dr Wollaston’s description 
 of his scale of chemical equivalents, an in- 
 strument which has contributed more to fa- 
 cilitate the general study and practice of 
 chemistry than any other invention of man. 
 His paper is further valuable, in presenting 
 a series of numbers denoting the relative 
 primary proportions, or weights of the atoms 
 of the principal chemical bodies, both simple 
 and compound, determined with singular 
 sagacity, from a general review of the most 
 exact analyses of other chemists, as well as 
 his own. 
 
 Ihe list of substances which he has esti- 
 mated, are arranged on one or other side of 
 a scale of numbers, in the order of their re- 
 lative weights, nnd at such distances from 
 each other, according to their weights, that 
 the series of numbers placed on a sliding 
 scale can at pleasure be moved, so that any 
 number expressing the weight of a compound, 
 may be brought to correspond with the place 
 of that compound, in the adjacent column. 
 The arrangement is then such, that the 
 weight of any ingredient in its composition, 
 of any reagent to be employed, or precipi- 
 tate that might be obtained in its analysis, 
 will be found opposite the point, at which its 
 respective name is placed. 
 
 If the slider be drawn upwards, till 100 
 corresponds to muriate of soda, the scale 
 will then shew how much of each sub- 
 stance contained in the table, is equivalent to 
 100 of common salt. It shews, with regard 
 to the different views of this salt, that it con- 
 tains 46.6' dry muriatic acid, and 53.4 of 
 soda, or 39.8 sodium, and 13.6 oxygen ; or 
 if viewed as chloride of sodium, that it con- 
 tains 60.2 chlorine, and 39.8 sodium. With 
 respect to reagents, it may lie seen, that 283 
 nitrate of lead, containing 191 of litharge, 
 employed to separate the muriatic acid, 
 would yield a precipitate of 237 muriate of 
 lead, and that there would then remain in 
 solution, nearly 146 nitrate of soda. It may 
 at the same time be seen, that the acid in 
 this quantity of salt, would serve to make 
 232 corrosive sublimate, containing 185.5 
 red oxide of mercury ; or make 91.5 muriate 
 of ammonia, composed of 62 muriatic gas 
 (or hydi omuriatic acid), and 29.5 ammonia. 
 The scale shews also, that for the purpose of 
 obtaining the whole of the acid in distilla- 
 tion, the quantity of oil of vitriol required is 
 nearly 84, and that the residuum of this d is- 
 
 r ' _ 
 
 filiation would be 122 dry sulphate of soda, 
 from which might be obtained, by crystalliza- 
 tion, 277 of glauber salt, containing 155 
 water of crystallization. These, and many 
 more such answers, appear at once, by bare 
 inspection, as soon as the weight ot any sub- 
 
EQU 
 
 EQU 
 
 stance intended for examination is made, by 
 motion of the slider, correctly to correspond 
 with its place in the adjacent column. Now 
 surely the accurate and immediate solution 
 of so many important practical problems, is 
 an incalculable benefit conferred on the che- 
 mist. 
 
 With regard to the method of laying 
 down the divisions of this scale, those who 
 are accustomed to the use of other sliding 
 rules, and are practically acquainted with 
 their properties, will recognize upon the 
 slider itself, the common Gunter’s line of 
 numbers, (as it is called), and will be satis- 
 fied, that the results which it gives are the 
 same that would be obtained by arithmetical 
 computation. 
 
 Those who are acquainted with the doc- 
 trine of ratios, and with the use of logarithms 
 as measures of ratios, will understand the 
 principle on which this scale is founded, and 
 will not need to be told, that all the divi- 
 sions are logometric ; consequently, that the 
 mechanical addition and subtraction of ratios 
 here performed by juxtaposition, corres- 
 ponds in effect to the multiplication and di- 
 vision of the numbers, by w hich those ratios 
 are expressed in common arithmetical nota- 
 tion. 
 
 In his Essay on the cause of Chemical 
 Proportions, Berzelius proposed a system of 
 signs, to denote atomical combinations, 
 which it may be proper briefly to explain. 
 This sign is the initial letter, and by itself 
 always expresses one atom, volume, or prime 
 of the substance. When it is necessary to 
 indicate several volumes or primes, it is done 
 by prefixing the number ; for example, the 
 cuprous oxide, or protoxide of copper, is 
 composed of a prime of oxygen and a prime 
 of metal ; its sign is therefore Cu + O. 
 The cupric oxide, or deutoxide of copper, is 
 composed of 1 prime metal, and 2 primes 
 oxygen ; therefore its sign is Cu +20. In 
 like manner, the sign for sulphuric acid is 
 £+ 50 ; for carbonic acid, C + 20 ; for 
 water, 2 Zf+ O, &c. 
 
 W hen we express a compound prime of 
 the first order, or binary, we throw' away the 
 +, and place the number of primes above 
 the letter, as the index or exponent is 
 placed in arithmetic. For example, CuO 
 + SO- 5 = sulphate of copper; CuO 2 + 
 *a03 = bi-deutosulphate of copper, or per- 
 sulphate. These formulae have this advan- 
 tage, that if we take away the oxygen, w e 
 see at once the ratio between the radicals. 
 As to the primes of the second order, or 
 ternary compounds, it is but rarely of any 
 advantage to express them by formulae, as 
 one prime ; but if we wish to express them 
 in that way, we may do it by using the pa- 
 renthesis, as is done in algebraic formula? ; 
 for example, according to Berzelius, alum is 
 composed of 3 primes of sulphate of alu- 
 
 mina, and 1 of sulphate of potash. Its sym- 
 bol is 3( A1 0 2 + 2S0 3 ) + (Po 2 + 2S0 3 ). 
 The prime of ammonia is 3 HN ; viz. 3 
 primes hydrogen + 1 nitrogen. We shall 
 use these abbreviations in our table of equi- 
 valent primes, at the end of the volume. 
 
 To reduce analytical results, as usually 
 given for 100 parts, to the equivalent prime 
 ratios, or, in hypothetical language, to the 
 atomic proportions, is now a problem of per- 
 petual recurrence, with whieh students are 
 perplexed, as no rule has been given for its 
 ready solution. Though numerous examples 
 of its solution occur in this Dictionary, we 
 shall here explain it in detail. 
 
 As in all reasoning we must proceed from 
 what is known or determinate, to what is 
 unknown or indeterminate, so in every ana- 
 lysis, there must be one ingredient whose 
 prime equivalent is well ascertained. This 
 is employed as the common measure, and 
 the proportions of the rest are compared to 
 it. Let us take, for instance, Sir H. Davy’s 
 analvsis of fluate of lime, to determine the 
 unknown number, that should denote the 
 prime of fluoric acid. We know, first of all, 
 that 2 primes of oxygen = 2, combine with 
 1 of carbon = 0.75, to form the compound 
 prime 2.75 of carbonic acid. We likewise 
 know that carbonate of lime consists of 43.6 
 carbonic acid + 54.4 lime. We therefore 
 make this proportion, to determine the prime 
 equivalent of lime. 
 
 1. 43.6 : 54.4 : : 2.75 : 356 = prime of 
 lime. 
 
 2. We know that 100 parts of dry sul- 
 phate of lime, consist of 41.6 lime and 
 58.4 acid. Hence, to find the prime of sul- 
 phuric acid, we make this proportion : 
 
 41.6 : 58.4 :: 3.56 : 5 = prime of sul- 
 phuric acid. 
 
 3. Sir H. Davy obtained from 100 grains 
 of fluor spar in pow^der, acted on with re- 
 peated quantities of sulphuric acid, and 
 ignited, 175.2 grains of sulphate of lime. 
 Now r , since 100 grains of sulphate of lime 
 contain, as above, 41.6 of lime, w r e have this 
 proportion : 
 
 100 : 41.6 175.2: 72.88 = lime, cor- 
 
 responding to 175.2 grains of sulphate, and 
 which previously existed in the 100 gr. of 
 fluor spar. If from 100 we subtract 72.88, 
 the difference 27.12 is the fluoric acid, or 
 the other ingredient of the fluor, which satu- 
 rated the lime. Now to find its prime 
 equivalent, we say, 
 
 72. 88 ; 3.56 : : 2 < . 12 t 1.325 • — the prime 
 or atom of fluoric acid from Sir II. Davy’s 
 experiment. Had we taken Dr Thomson’s 
 number 3.625, as representing the atom of 
 lime, the atom of fluoric acid would come 
 out 1.301 o. As the Doctor had a particu- 
 lar hypothesis to support, which required the 
 weight of the acid atom to be a great deal less, 
 he deduces it, frem the same data , to be only 
 
EQU 
 
 EQU 
 
 1.0095. By what new process of arithmetic 
 he brought out this number, it is impossible 
 to conjecture. But no doubt he devoted 
 some pains to the computation, since he 
 rears on that unsubstantial basis, a loner 
 fabric of atomic induction. 
 
 We shall give another example, derived 
 from a more complex subject. 
 
 M. Vauquelin found, that 33 parts of 
 lime, saturated with sorbic acid, and care- 
 fully dried, weighed 100 grains. Hence 
 the difference, 67 grains, was acid. To find 
 its equivalent prime, we say. 
 
 As 33 : 67 : : 3.56 = the prime of lime 
 : 7.23 — the prime of the acid, But as he 
 brought it to absolute neutrality by a small 
 portion of potash, we may take 7.5 for the 
 prime. 
 
 M. Vauquelin subjected the acid, as it 
 exists in the dry sorbates of lead and copper, 
 
 to igneous analysis ; and obtained the fol- 
 lowing results : 
 
 Hydrogen, 16.8 
 
 Carbon, 28.3 
 
 Oxygen, 54.9 
 
 100.0 
 
 Now we must find such an assemblage of 
 the primes or atoms of these elements, as 
 will form a sum-total of 7.5 ; and at the 
 same time be to each other, in the above pro- 
 portions. The following very simple rule 
 will give a ready approximation ; and by a 
 common sliding scale, it may be worked by 
 inspection. 
 
 Multiply each proportion per cent, by the 
 compound prime, and compare the products 
 w r ith the multiples of the constituent primes. 
 You can then estimate the number of each 
 prime requisite to compose the whole. Thus 
 
 Theory. Experiment. 
 
 0.168 X 7-5 =» 1.2600 or 
 
 10 hydrogen 
 
 » 1.25 
 
 16.7 
 
 16.8 
 
 0.283 X 7.5 = 2.1225 
 
 3 carbon 
 
 = 2.25 
 
 30.0 
 
 28.3 
 
 0.549 X 7.5 = 4.1175 
 
 4 oxygen 
 
 = 4.00 
 
 53.3 
 
 54.9 
 
 
 
 7.50 
 
 100.0 
 
 100.0 
 
 The differences between these theoretical 
 and experimental proportions, are probably 
 within the limits of the errors of the latter, 
 in the present state of analysis. 
 
 If on Dr Wollaston’s scale, we mark with 
 a type or a pen, 2h, 3h, cScc. up to I Oh; 
 2c, 3c, 4c, 5c ; and 2n, 3n, 4n ; respec- 
 tively opposite to twice, thrice, &c. the atoms 
 of hydrogen, carbon, and nitrogen, as is 
 already done for oxygen, (with the exception 
 of the fourth, where copper stands), we shall 
 then have ready approximations to the prime 
 components, by inspection of the scale. 
 Move the sliding part, so that one of the 
 quantities per cent, may stand opposite the 
 nearest estimate of a multiple prime of that 
 constituent. Thus we know that hydrogen, 
 carbon, and oxygen, bear the relation to each 
 other of I, 6, 8; and, of course, the latter 
 two, that of 3 to 4. But 54.9 oxygen, be- 
 ing more than one-half of 100, the weight 
 of oxygen in the compound prime is more 
 than the half of 7.5, and therefore points to 
 4. Place 54.9 opposite 4 oxygen, (where 
 copper stands), we shall find 18 opposite 10 
 hydrogen, and 30.7 opposite 3 carbon. Here 
 we see the proportions of carbon and hydro- 
 gen, are both greater than by Vauquelin’s 
 analysis. Try 51 opposite 4 oxygen, then 
 opposite 3 carbon we have, 28.7, and oppo- 
 site 10 hydrogen 16.9. The proportions I 
 have calculated arithmetically above, seem 
 somewhat better approximations ; they were 
 deduced from hydrogen 0.12.5, and carbon 
 0.75, instead of 0.132 and 0.754, as on the 
 scale. 
 
 If the weight of the compound prime is 
 
 2<S 
 
 not given, then we must proceed to estimate 
 the nearest prime proportions, after inspec- 
 tion of those per cent. The scale may be 
 used with advantage, as just now explained. 
 
 The following case has been reckoned dif- 
 ficult of solution, and has been even involved 
 in an algebraic formula. Let us suppose a 
 vegetable acid, containing combined water, 
 whose prime equivalent is to be determined by 
 experiment. A crystallized salt is made with 
 it , for example, and a determinate quantity 
 of soda. Suppose the alkali to form 26 per 
 cent of the salt. The rest is water and acid. 
 Dissolve 1G0 grains, and add them to an in- 
 definite quantity of the solution cf any salt, 
 with whose base the vegetable acid forms an 
 insoluble compound. Dry and weigh this 
 precipitate. Without decomposing the lat- 
 ter, we have sufficient data for determining 
 the prime equivalent of the real acid. We 
 make this proportion : As the weight of 
 
 soda is, to its prime equivalent, so is the 
 weight of the precipitate, to the prime of the 
 compound. Suppose 148 grains of an inso- 
 luble salt of lead to have been obtained ; 
 then 26 : 3.95 : : 148 : 22. 1 = the prime of 
 the salt of lead. From this, if we deduct 
 the weight of the prime equivalent of oxide of 
 lead, =14, we have 8.1 for the prime equi- 
 valent of the acid. And the crystallized salt 
 must have consisted of, 
 
 Dry acid, 53.3 
 Soda, 26.0 
 
 Water, 20.7 
 
 100.0 
 
ETH 
 
 ETH 
 
 As the above numbers were assumed 
 merely for arithmetical illustration, the wa- 
 ter is not atomically expressed. Indeed the 
 problem of finding the acid prime, does not 
 require the salt to be either dried or weighed. 
 A solution would suffice. Saturate a known 
 weight of alkali, with an unknown quantity 
 of the crystallized acid. Add this neutral 
 solution, to a redundant quantity of solution 
 of nitrate of lead. Wash, dry, and weigh 
 the insoluble precipitate, and apply the above 
 rule. 
 
 There are three systems of equivalent 
 numbers at present employed : 1st, That 
 
 having oxygen as the radix ; 2d, That hav- 
 ing one volume of hydrogen, as the radix ; 
 3d, That having two volumes of hydrogen 
 as the radix, on the Daltonian supposition, 
 that two volumes of hydrogen contain the 
 same number of atoms, as one volume of 
 oxygen. As this hypothesis is destitute 
 of proof, it evidently should be discarded 
 from physical science. Since the volume of 
 hydrogen, is equal in weight to 1-1 6th the 
 weight of the volume of oxygen, the for- 
 mer two systems are mutually convertible, 
 by multiplying the number oxygen, in the 
 oxygen ratio, by 16, or 4 X 4, to obtain 
 the number in the hydrogen scale ; and this 
 is re-converted by the inverse operation, 
 namely, dividing by 16, or by 4X4. 
 
 Dr Wollaston’s scale, and Sir H. Davy’s 
 proportional numbers, are adapted to the idea 
 that water is a compound of 1 hydrogen -|- 
 7.5 oxygen by weight, or 15 -j- 1 by volume. 
 Their mutual conversion is therefore very 
 easy, for if we add to Dr Wollaston’s num- 
 ber, its half, the sum is Sir H. Davy’s ; and 
 of course, if we subtract from the number of 
 the latter, its third, the remainder is Dr 
 Wollaston’s number. There is one very 
 frequent variation in the weights of the 
 primes among the best writers, namely, 
 doubling or halving the number. This dif- 
 ference is occasioned generally by an uncer- 
 tainly about the first term or proportion in 
 which the body combines with oxygen ; 
 some chemists reckoning that a protoxide 
 which others consider a deutoxide. Thus 
 Sir H. Davy gives 103 as the number repre- 
 senting iron ; from which, if we deduct 
 = 34.3, the remainder 68.7 is near- 
 ly double of 34.5, the number of Dr Wol- 
 laston. But Mr Porrett has very ingenious- 
 ly shewn that perhaps ^ = 17.5, "is to be 
 preferred.* 2 
 
 Essences. Several of the volatile or es- 
 sential oils are called essences by the per- 
 fumers. 
 
 Ether. A very volatile fluid, produced 
 by the distillation of alcohol with an acid. 
 
 \\ hen strong sulphuric acid is poured 
 upon an equal weight of alcohol, the fluids 
 unite with a hissing noise and the produc- 
 tion of heat, at the same time that a fra- 
 
 grant vegetable smell is perceived, resem- 
 bling that of apples. It is much better and 
 safer, however, to add the acid by small 
 portions at a time, at such intervals as that 
 no perceptible heat may be produced. I he 
 mixture may be made in a glass retort, and 
 the distillation performed by regulated heat 
 on a sand-bath, a large tubulated receiver 
 being previously well adapted, and kept cool 
 by immersion in water, or the frequent ap- 
 plication of wet cloths. A bent glass tube 
 luted to the tubular of the receiver, and 
 having its extremity immersed in a little 
 water or mercury, will allow the gases to 
 escape, and confine the condensible vapour. 
 The first product is a fragrant spirit of 
 wine, which is followed by the ether, as soon 
 as the fluid in the retort begins to boil. At 
 this period, the upper part of the receiver is 
 covered, with large distinct streams of the 
 fluid which run down its sides. After the 
 ether has passed over, sulphurous acid arises, 
 which is known by its white fume and pecu- 
 liar smell. At this period the receiver must 
 be unluted and removed, care being taken 
 to avoid breathing the penetrating fumes 
 of the acid ; and the fire must at the same 
 time be moderated, because the residue in 
 the retort is disposed to swell. A light yel- 
 low oil, called sweet oil of wine, comes over 
 after the ether, and is succeeded by black 
 and foul sulphuric acid. The residue varies 
 in its properties according to the manage- 
 ment of the heat. If the fire be much in- 
 creased toward the end of the process, the 
 sulphurous acid that comes over, will be 
 mixed with vinegar. 
 
 The ether comes over mixed with alcohol 
 and some sulphurous acid. It was usual to 
 add some distilled water to this product, 
 which occasioned the ether to rise to the 
 top. Rectification is absolutely necessary, 
 if the ether have a sulphurous smell ; and 
 tliis is indeed the better method in all cases, 
 because the water added in the old method 
 always absorbs about one- tenth part of its 
 weight of ether, which cannot be recovered 
 without having recourse to distillation ; 
 and also because the ether is found to ab- 
 sorb a quantity of the water. Previous to 
 the rectification, a small quantity of black 
 oxide of manganese should be added, shak- 
 ing the mixture occasionally during 24 
 hours. Proust prefers clean slaked lime, as 
 recommended by Woolfe ; observing that the 
 bottle must not be above three parts filled, 
 and that it must be moved about in cold 
 water for some minutes before the cork is 
 taken out. 
 
 The inexperienced chemist must be re- 
 minded, that the extreme inflammability of 
 alcohol, and still more of ether; the danger 
 of explosion which attends the sudden mix- 
 ture and agitation of concentrated acids and 
 alcohol ; and the suffocating effect of the 
 
ETII 
 
 ETH 
 
 elastic fluids, which might fill the apartment 
 it inadvertently disengaged ; are all circum- 
 stances which require cautious management. 
 
 Sulphuric ether is a very fragrant, light, 
 and volatile fluid. Its evaporation produces 
 extreme cold. It is highly inflammable, 
 burns with a more luminous flame than alco- 
 hol, which is of a deep blue, and emits more 
 smoke. At 46° below 0 of Fahr. it becomes 
 solid. It dissolves essential oiis and resins, 
 and camphor very plentifully. By long di- 
 gestion it dissolves l-15th of sulphur in the 
 light, and 1-1 7th in the dark. This prepa- 
 ration Mr Favre recommends as an excel- 
 lent test of lead in wine, which it throws 
 down in a black precipitate. Mixed with 
 the muriatic solution of gold it retains a por- 
 tion of the metal in solution for some time. 
 
 * To give ether its utmost purity, we 
 must add to the common purified ether, dry 
 subcarbonate of potash in powder, till the 
 last portions are not wetted, and draw off 
 the ether by distillation. Its sp. gr. will fall 
 from 0.775 to 0.746. Being thus deprived 
 of its water, it must next be freed from alco- 
 hol, by digesting it on dry muriate of lime, 
 and decanting the supernatant liquid, which 
 is ether of sp. gr. 0.652 at 60°, according to 
 Lowitz. Distillation increases its density to 
 0. 7155 at 68°, according to M. T. de Saus- 
 sure. 
 
 Ether boils in the atmosphere at 98° F. 
 and in vacuo at — 20°. The density of its 
 vapour as determined by M. Gay Lussac, is 
 2.586, that of air being 1. Ether admitted 
 to any gas standing over mercury, doubles 
 its bulk at atmospheric temperatures. If 
 oxygen be thus expanded with ether, and 
 
 2 volumes of olefiant gas, 
 
 1 do. vapour of water, 
 
 then mixed with three times its bulk of pure 
 oxygen, on being kindled it explodes, form- 
 ing carbonic acid and water. By detonating 
 such a mixture M. de Saussure has lately 
 inferred ether to consist of 
 
 Hydrogen, 14.40 
 Carbon, 67.98 
 
 Oxygen, 17.62 
 
 100.00 
 
 These proportions per cent, correspond to 
 Olefiant gas, 80.05 
 Water, 1 9. 95 
 
 100.00 
 
 Or very nearly 5 primes olefiant gas, con- 
 sisting of 5 carbon -j- 5 hydrogen ; 
 
 Or (0.750 0.1 25) X 5 = 4.375 
 
 1 prime water, or 1 hy- ) 
 
 drogen + ‘ oxygen, y ' ° 
 
 5.500 
 
 Or 6 hydrogen 5 carbon 1 oxygen. 
 
 By passing ether through a red-hot por* 
 celain tube, it is resolved into heavy inflam- 
 mable air, a viscid volatile oil, a little con- 
 crete oil, and charcoal and water. 
 
 Ten parts of water combine with one of 
 ether. Sulphuric acid converts ether into 
 sweet oil of wine. If a very little ether be 
 thrown into a large bottle filled with chlo- 
 rine, a white vapour soon rises, followed by 
 explosion and flame. Charcoal is deposited, 
 and carbonic acid gas formed. 
 
 If we apply to ether that principle of re- 
 search invented by M. Gay Lussac, and so 
 successfully applied by him to iodine and 
 prussic acid, we shall find that, 
 
 *5= 0.9722 X 2 = 1.9444 
 = 0.6249 
 
 Condensed into one volume of vapour of ether, = 2.5695 
 Which is very nearly the experimental sp. gr. = 2.5860 
 
 On this view, the vapour of ether con- 
 tains one-half of the combined water, that 
 the vapour of alcohol does. 
 
 But two volumes of olefiant gas consist of 
 four volumes of hydrogen, and four ot car- 
 bon, in a condensed state ; and one volume 
 
 5 atoms hydrogen, = 0.1 25 
 4 carbon, =0.750 
 
 1 oxygen, = 1.000 
 
 These proportions differ from those of M. 
 de Saussure, in making the carbon a little 
 more, and the oxygen a little less, than he 
 found. 
 
 Ethers, exactly the same with the sulphu- 
 ric, may be obtained by passing alcohol 
 
 of aqueous vapour consists of one volume of 
 hydrogen, and half a volume of oxygen. 
 Hence the ratio of the weights of the consti- 
 tuents will become, on the hypothetical oxy- 
 gen scale, in which half a volume of oxygen 
 represents one atom, 
 
 X 5 = 0.625 ... 13.513 
 X 4 = 3.000 ... 21.622 
 x 1 = 1.000 ... 64.865 
 
 4.625 100.000 
 
 through phosphoric and arsenic acids con* 
 centrated and heated. 
 
 Another kind of ethers are those which 
 result from the combination of the alcohol 
 with the acid employed to make them, 
 Nine such ethers are known. Muriatic 
 
ETH 
 
 ether, nitric ether, hydriodic ether, acetic 
 ether, benzoic ether, oxalic ether, citric ether, 
 tartaric ether, gallic ether; the first four are 
 more volatile than alcohol ; the rest are much 
 less so, for they boil with more difficulty than 
 water. 
 
 Muriatic ether. It is formed by saturat- 
 ing alcohol with muriatic acid gas ; or still 
 better by mixing together equal bulks of al- 
 cohol and concentrated liquid muriatic acid, 
 and heating the mixture in a glass retort 
 connected with a Woolfe’s apparatus. The 
 first bottle should contain a quantity of 
 water, at about 80° F. ; the second should 
 be surrounded with ice. From 10 ounces of 
 acid, and an equal bulk of alcohol, 1.2 
 ounces of ether may be obtained. 
 
 Under the barometric pressure of SO 
 inches, this ether is always gaseous at 51 °, 
 and all higher temperatures. In the state of 
 gas it is colourless, and without action on 
 litmus, or violets. Its odour is very strong 
 and analogous to that of sulphuric ether ; its 
 taste is perceptibly saccharine ; and its sp. 
 gr. compared to that of air is 2.2 i 9. 
 
 In the liquid state at 40° F., its sp. gr. is 
 0.874. Poured on the palm of the hand it 
 immediately boils, and produces much cold. 
 At a dull red heat, muriatic ether is con- 
 verted into muriatic acid gas, and olefiant gas, 
 with, most probably, water; for M. Thenard 
 gave for its composition, from the mean of 
 many eudiometric, and other experiments, 
 acid 29.48 -j- carbon 36.6 + oxygen 25.28 
 + hydrogen 10.64 = 100. — Mem. d’Ar- 
 cueil, i. 343. Eight years thereafter, he 
 modified these results into 46.5 acid -j- 53.5 
 alcohol, (32.6 olef. gas -j- 20.9 water).— 
 Traite, iii. 277. 
 
 When a lighted taper is brought near the 
 surface of this ether, it immediately takes 
 fire, and burns with a greenish flame. Mu- 
 riatic gas, carbonic acid, and water result. 
 Similar products are obtained by firing a 
 mixture of its vapour with oxygen, either by 
 the taper or electric spark. If the oxygen 
 be to the vapour in the ratio of 3 to 1, a vio- 
 lent detonation takes place, which breaks 
 common eudiometers. 
 
 Water dissolves of muriatic ether a vo- 
 lume equal to its own, at mean pressure and 
 temperature. Ihe solution has a sweet and 
 cooling taste, analogous to that of pepper- 
 mint. Although it be very soluble in alco- 
 hol, water separates the whole of it. Chlo- 
 rine instantly decomposes muriatic ether. 
 Nitrate of silver and protonitrate of mercury, 
 two salts, which suddenly occasion precipi- 
 tates in waters containing muriatic acid, 
 either free or combined with a salifiable base, 
 produce no immediate cloud with this ether. 
 It is only after some hours contact that we 
 begin to perceive an action ; and even after 
 three months, the muriatic acid is not com- 
 pletely thrown down. These experiments 
 
 ETH 
 
 must be made in phials closed with well 
 ground stoppers. 
 
 The ether produced by treating certain 
 muriates, especially the fuming muriate, or 
 chloride of tin, with alcohol, is muriatic 
 ether. The only difference which exists be- 
 tween the former and this kind, is that the 
 ether formed with the acid, is a little more 
 volatile than the ether made with the chlorides. 
 
 Nitric ether. This ether is prepared by 
 distilling equal parts by weight of alcohol, 
 and the aquafortis of commerce. After hav- 
 ing introduced them into a retort capable of 
 holding double the bulk, it must be put in 
 connexion with a Woolfe’s apparatus, of which 
 the first bottle is empty, and the other four 
 half filled with saturated brine. The whole 
 bottles must be put into an oblong box, and 
 surrounded with a mixture of snow and salt. 
 We then apply a gentle heat from a charcoal 
 chauffer. As soon as the liquor begins to 
 boil, we must instantly withdraw the heat, 
 and, if necessary, check the violence of tho 
 ebullition by the application of a moist 
 sponge, or rag, to the retort. The operation 
 is finished when it spontaneously ceases to 
 boil. By this time the product forms a 
 little more than one-third of the alcohol and 
 acid employed. 
 
 But ether is not the sole product of the 
 operation. We obtain also much protoxide 
 of azote and water, a little azote, deutoxide 
 of azote, carbonic acid gas, nitrous acid gas, 
 acetic acid, and a substance easily carboniz- 
 ed. We are thus led to suppose that a por- 
 tion of the alcohol is completely decomposed 
 by the nitric acid, that it yields almost all 
 its hydrogen to the oxygen of this acid, and 
 that hence result all the products, besides 
 the ether, whilst the alcohol and the nitrous 
 acid unite to constitute the ether properly so 
 called. The whole ether comes over as well 
 as the azote, protoxide of azote, deutoxide of 
 azote, and carbonic acid. As to the water, 
 nitrous and acetic acids, they are disengaged 
 only in part, as well as a portion of the alco- 
 hol and nitric acid which escape their recipro- 
 cal action. In fact, the easily charred matter 
 remains in the retort along w ith a little acetic 
 acid, about 78 parts of nitric acid, 60 of 
 alcohol, and 284 of water, supposing that we 
 had operated upon 500 parts of alcohol, and 
 as much dilute nitric acid. 
 
 It is because there is formed so great a 
 quantity of gas, that the salt water and re- 
 frigeration are required. Without these pre- 
 cautions, the greater part of the ether w-ould 
 be carried off into the atmosphere ; and even 
 with them, some is always lost. 
 
 On u n luting the apparatus, there is found 
 in the first bottle a large quantity of yellow- 
 ish liquid, formed of much weak alcohol, of 
 ether, with nitrous, nitric, and acetic acids. 
 In the second, we find on the surface of the 
 salt water, a pretty thick stratum of ether, 
 
ETH 
 
 ETH 
 
 contaminated with a little add and alcohol. 
 In the third, a thinner layer of the same, 
 and so on. 
 
 These layers are to he separated from the 
 water by a long-necked funnel, mixed with 
 the liquid of the first bottle, and redistilled 
 from a retort by a gentle heat, into a receiver 
 surrounded with ice. The first product is 
 an ether, which may he entirely deprived of 
 acid, by being placed in contact with cold 
 quicklime in a phial, and decanted off it, in 
 about half an hour. From a mixture of 
 about 500 parts of alcohol, and as much acid, 
 about 100 parts of excellent ether may be 
 procured. 
 
 Nitric ether in its ordinary state is a liquid 
 of a yellowish-white colour. It has an 
 odour analogous to that of the preceding 
 ethers, hut much stronger, so that its inhala- 
 tion into the nostrils produces a species of 
 giddiness. It does not redden litmus. Its 
 taste is acrid and burning. Its sp. gr. is 
 greater than that of alcohol, and less than 
 that of water. It boils at 70° F. or at that 
 temperature sustains a column equal to 30 
 inches of mercury. Poured into the hand, 
 it. immediately boils, and creates consider- 
 able cold. It is sufficient to grasp in our 
 hands a phial containing it, to see bubbles 
 immediately escape. It takes fire very rea- 
 dily, and burns quite away, with a white 
 dame. 
 
 When agitated with 25 or 30 times its 
 weight of water, it is divided into three por- 
 tions. One, the smallest, is dissolved ; ano- 
 ther is converted into vapour ; and a third 
 is decomposed. The solution becomes sud- 
 denly acid; it assumes a strong smell of 
 apples ; and if, after saturating with potash 
 the acid which it contains, it be subjected to 
 distillation, we withdraw the alcohol, and 
 obtain a residue formed of nitrate of potash. 
 We see here that there is a separation, of one 
 part of the two bodies, which constitute the 
 ether. Left to itself in a well stopped bot- 
 tle, the ether suffers a spontaneous change, 
 for it becomes perceptibly acid. By distilla- 
 tion, acid is instantly developed, which shews 
 that heat favours its decomposition. If, in- 
 stead of exposing the nitric ether to a dis- 
 tilling heat, we make it traverse an ignited 
 tube, it is completely decomposed. '11.5 
 parts of ether thus decomposed, yielded 5.63 
 water, containing a little prussic acid ; 0.40 
 of ammonia; 0.80 oil; 0.30 of charcoal; 
 0.75 carbonic acid; 29.9 of gases, formed 
 -of deutoxide of azote, azote, subcarburetted 
 hydrogen, and oxide of carbon. The loss 
 amounted to 3.72. 
 
 It is very slowly decomposed by potash. 
 When combined with nitrous acid gas or 
 acetic acid, so intimate a union is effected, 
 1 hat in making the compound pass through 
 the most concentrated alkalis, only a small 
 portion of its acid is separated. According 
 
 to 3VI. Plienard, from whose excellent me- 
 moir in the first volume of the Memuires 
 (V Arcucil the above interesing facts are 
 taken, nitric ether is composed in the hum- 
 dred parts of 
 
 Carbon, 28.65 or 
 
 4 primes 
 
 3.0 
 
 Azote, 14.49 
 
 1 
 
 1.75 
 
 Hydrogen, 8.54 
 
 7 
 
 0.875 
 
 Oxygen, 48.52 
 
 5 
 
 5.000 
 
 10.625 
 
 Perhaps with a little management we 
 might coax these refractory atoms into a 
 better correspondence with M. Thenard’s 
 results ; but in such freaks of fancy, it is 
 foolish to indulge. This distinguished che- 
 mist indeed admitted, that the analysis is 
 imperfect; and promised to repeat it in 
 another and better way by explosion with 
 oxygen, of which gas, nitric ether, from its 
 great volatility, quintuples the volume, at 
 ordinary temperatures. 
 
 Hydriodic ether. M. Gay Lussac, to 
 whom the formation of this ether is due, ob- 
 tained it by mixing together equal bulks of 
 alcohol and a coloured hydriodic acid, sp. 
 gr. 1.700, distilling the mixture by the heat 
 of a water bath, and diluting with water the 
 product which gradually collects in the re- 
 ceiver. The ether precipitates in the form of 
 small globules, which have at first a milky 
 aspect, but which by their union form a 
 transparent liquid. It is purified by repeated 
 washings with water. 
 
 This ether does not redden litmus ; its 
 smell is strong, and analogous to that of the 
 rest. Its sp. gr. is 1.9206 at 72° F. It 
 assumes in the course of a few days a rose 
 colour, which becomes no deeper by time, 
 and which mercury and potash instantly re- 
 move, by seizing the iodine which occasions 
 it. 
 
 Hydriodic ether boils at 156° F. At or- 
 dinary temperatures, it does not kindle by 
 the approach of a lighted taper to its surface, 
 but only exhales purple vapours, when pour- 
 ed drop by drop on burning coals, Potas- 
 sium keeps in it, without alteration. Potash 
 does not instantaneously change it. The 
 same may he said of nitric and sulphurous 
 acids, as well as chlorine. By passing it 
 through an incandescent tube, it is convert- 
 ed into a carburetted inflammable gas ; into 
 dark brown hydriodic acid ; into charcoal ; 
 and flocculi, whose odour is pthereous, and 
 which M. Gay Lussac considers as a sort of 
 ether, formed of hydriodic acid, and of a ve- 
 getable product different from alcohol. These 
 flakes melt in boiling water, and assume on 
 cooling the transparency and colour of wax. 
 They are much less volatile than hydriodic 
 ether, and evolve much more iodine wheu 
 projected on glowing coals. 
 
 ICthcrs Jrom vegetable acids . Almost ail 
 the vegetable acids dissolve in alcohol, and 
 
ETH 
 
 ETH 
 
 separate from it again by distillation, with- 
 out any peculiar product being formed, how- 
 ever frequently we act upon the same quan- 
 tity of acid and alcohol. Such is the case at 
 least with the tartaric, citric, malic, benzoic, 
 oxalic, and gallic acid. But this cannot be 
 said of the acetic. The action of this acid 
 on alcohol is such, that by means of re- 
 peated distillations, the two bodies disappear, 
 and form a true ether ; whence it has been 
 inferred by M. lhenard, that this fluid is 
 probably the only one of the vegetable acids 
 at present known, which can exhibit by itself 
 the phenomena of etherization. But if in- 
 stead of putting the vegetable acids alone in 
 contact with alcohol, we add to the mixture 
 one of the concentrated mineral acids, we 
 can then produce with several of them com- 
 pounds analogous to the preceding ethers. 
 The mineral acid probably acts here by con- 
 densing the alcohol, and elevating the tem- 
 perature, to such a degree as to determine 
 the requisite chemical reaction. 
 
 Acetic ether was discovered by Scheele, 
 but first accurately examined by M. Thenard. 
 
 Take 100 parts of rectified alcohol, 63 
 parts of concentrated acetic acid, 17 parts of 
 sulphuric acid of commerce. After having 
 mixed the whole, introduce them into a tubu- 
 lated glass retort, connected with a large glo- 
 bular receiver surrounded with cold water. 
 On applying heat, the liquid enters into 
 ebullition; and when 123 parts of ether 
 have passed over, the process may be stop- 
 ped. To render it perfectly pure, we have 
 only to place it, for half an hour, in contact 
 with 10 or 12 parts of the caustic potash of 
 the apothecary, in a corked phial, and to 
 agitate from time to time. Two strata will 
 form ; the undermost thin, composed of 
 potash and acetate of potash dissolved in 
 water ; the uppermost much more consider- 
 able, consisting of pure ether, which may be 
 separated by a long-necked funnel. The 
 sulphuric acid does not enter at all into the 
 composition of this ether. It merely favours 
 the reaction of the alcohol and acetic acid. 
 This mode is much better than the old one, 
 of distilling many times over, the same mix- 
 ture of acetic acid and alcohol. Or we may 
 obtain an excellent acetic ether, very econo- 
 mically, by taking 3 parts of acetate of po- 
 tash, 3 of concentrated alcohol, and 2 of oil 
 of vitriol ; introducing the mixture into a 
 tubulated retort, and distilling to perfect 
 dryness ; then mixing the product with the 
 fifth part of its weight of oil of vitriol, and, 
 by a careful distillation, drawing off as much 
 ether as there was alcohol employed. 
 
 -Acetic ether is a colourless liquid, having 
 an 'agreeable odour of sulphuric ether and 
 acetic acid. It does not redden litmus pa- 
 per, or tincture of turnsole. Its taste is 
 .peculiar. Its sp. gr. is 0.866, at 44.5° F. 
 
 Under the ordinary atmospheric pressure, 
 it enters into ebullition at 1 60° Fahr. A 
 lighted taper brought near its surface at or- 
 dinary temperatures sets fire to it, and it burns 
 with a yellowish- white flame. Acetic acid 
 is developed in the combustion. It is not 
 changed by keeping. Water at 62° dissolves 
 a 7F part of its weight. When thus dissolv- 
 ed in water, it exercises no action on litmus, 
 and it preserves its characteristic odour and 
 taste. But when this solution is put in 
 contact with the half of its weight of caustic 
 potash, its odour and taste disappear. It is 
 now completely decomposed. Hence, if we 
 submit this liquid to distillation, alcohol 
 passes over, and acetate of potash remains. 
 Acetic ether is, like all the others, very solu- 
 ble in alcohol, and separable from alcohol by 
 water. Its other properties are unknown. 
 It is used only in medicine, as an exhilarant 
 and diuretic. 
 
 Benzoic ether. The presence of a mineral 
 acid is indispensable to its formation, as well 
 as that of the remaining vegetable ethers. 
 
 Take 30 parts of benzoic acid, 60 of alco- 
 hol, 15 of strong muriatic acid. Introduce 
 these ingredients mixed together into a tubu- 
 lated retort, and distil into a refrigerated 
 receiver, stopping the operation when two- 
 thirds have passed over. Atmospherical air, 
 and traces of muriatic acid, are the only 
 gaseous products. The first portion of the 
 liquid is alcohol charged with a little acid, 
 but the last will contain a certain quantity of 
 benzoic ether, which is easily separable by 
 water. A larger quantity of this ether re- 
 mains in the retort, covered by a pretty thick 
 stratum, consisting of alcohol, water, muria- 
 tic, and benzoic acids. By repeated affusions 
 of hot water into the retort, this stratum will 
 be finally dissolved. It is easy thus to pro- 
 cure benzoic ether. But as so made, it is 
 always contaminated with a portion of ben- 
 zoic acid, which renders it solid at ordinary 
 temperatures, and makes it act on litmus. 
 It may be purified by agitation with a small 
 quantity of alkaline solution, and subsequent 
 washing with water. There is no muriatic 
 acid found in this purified ether. 
 
 Ethers from oxalic acid , citric , tfc. When 
 we make a solution of 30 parts of oxalic 
 acid in 35 parts of pure alcohol, and having 
 added 10 parts of oil of vitriol, we subject 
 the whole to distillation till a little sulphuric 
 ether begins to be formed, we shall find that 
 nothing but alcohol slightly etherized has 
 passed into the receiver, and there remains 
 in the retort a brown coloured strongly acid 
 liquor, from which, on cooling, crystals of 
 oxalic acid fall down. But when we dilute 
 the residual liquor with water, a matter is 
 separated similar to what the benzoic acid 
 yielded, scarcely soluble in water, very abun- 
 dant, and which is obtained pure by washing 
 
ETH 
 
 EVA 
 
 it with cold water, and removing, by a little 
 alkali, the excess of acid which it retains. 
 
 If we treat in the same way, the citric and 
 malic acids, we obtain similar products. The 
 three substances resulting from these three 
 acids have analogous properties. They are 
 all yellowish, somewhat heavier than water, 
 void of smell, perceptibly soluble in water, 
 and very soluble in alcohol, from which they 
 are precipitated by water. They differ from 
 each other in taste. That made from oxalic 
 acid is faintly astringent; that from the 
 citric acid is very bitter. The first i9 the 
 only one which is volatile ; it is vaporized 
 with boiling water, and by this means it is 
 easily obtained white. When heated with a 
 solution of caustic potash, they are all three 
 decomposed, and yield alcohol, along with 
 their peculiar acids ; but no trace of sulphu- 
 ric acid. 
 
 Tartaric acid is also susceptible of com- 
 bining with alcohol like the preceding acids. 
 But it presents some curious phenomena. 
 The experiment, of its formation, must be 
 conducted in the same w'ay as with oxalic 
 acid. We must employ 30 parts of tartaric 
 acid, 35 of alcohol, 10 of oil of vitriol, and 
 distil the mixture till a little sulphuric ether 
 begins to be formed. If at this period we 
 •withdraw the heat from the retort, the liquor 
 will assume a syrupy consistence by cooling. 
 But in vain shall we pour in water, in hope 
 of separating, as in the preceding cases, a 
 peculiar combination of the vegetable acid 
 and alcohol. But let us add by degrees so- 
 lution of potash, we shall throw down much 
 cream of tartar ; then, after having just sa- 
 turated the redundant acid, if we evaporate 
 the liquid, and treat it in the cold with very 
 pure alcohol, we shall obtain, by evaporation 
 of the alcoholic solution, a substance which, 
 on cooling, will become more syrupy than 
 the matter was, before being treated with 
 potash and alcohol. This substance, which 
 is easily prepared in considerable quantity, 
 has a brown colour, and a very bitter and 
 slightly nauseous taste. It is void ot smell 
 and acidity, and is very soluble in water and 
 alcohol. It does not precipitate muriate of 
 lime, but copiously the muriate of barytes. 
 When calcined it diffuses dense fumes, which 
 have the odour of garlic, and at the same 
 time it leaves a charcoaly residue, not alka- 
 line, containing much sulphate ot potash. 
 Finally, if distilled with potash, it is resolved 
 into a very strong alcohol, and much tartrate 
 of potash. This substance is therefore a 
 combination analogous to the preceding. 
 But what is peculiar to it is its syrupy state, 
 and the property it possesses ot rendering 
 soluble in the most concentrated alcohol the 
 sulphate of potash, which of itself is insolu- 
 ble in ardent spirits. It is perhaps owing 
 to this admixture of sulphate of potash, that 
 
 it wants the oily aspect belonging to all the 
 other combinations of this genus. 
 
 These vegetable- acid ethers may be con- 
 sidered either as compounds of acid and al- 
 cohol, or of the ultimate constituents of the 
 former with those of the latter. * 
 
 Ethiops ( Martial). Black oxide of iron. 
 
 Etuiops (Mineral). The black sul- 
 phuret of mercury. 
 
 Evaporation. A chemical operation us- 
 ually performed by applying heat to any 
 compound substance, in order to dispel the 
 volatile parts. It differs from distillation in 
 its object, which chiefly consists in preserving 
 the more fixed matters, while the volatile 
 substances are dissipated and lost. And the 
 vessels are accordingly different, evaporation 
 being commonly made in open shallow ves- 
 sels, and distillation in an apparatus nearly 
 closed from the external air. 
 
 The degree of heat must be duly regulat- 
 ed in evaporation. When the fixed and 
 more volatile matters do not greatly differ in 
 their tendency to fly off, the heat must be 
 very carefully adjusted; but in other cases 
 this is less necessary. 
 
 As evaporation consists in the assumption 
 of the elastic form, its rapidity will be in pro- 
 portion to the degree of heat and the diminu- 
 tion of the pressure of the atmosphere. A cur- 
 rent of air is likewise of service in this process. 
 
 * In treating of alum, I alluded to a me- 
 thod of evaporating liquors lately introduced 
 into large manufactories. A water-tight 
 stone cistern, about three or four feet broad, 
 two feet deep, and 20, 30, or 40 feet long, 
 is covered above by a low brick arch. At 
 one extremity of this tunnel a grate is built, 
 and, at the other, a lofty chimney. When 
 the cistern is filled, and a strong fire kindled 
 in the reverberatory grate, the flame and hot 
 air sweep along the surface of the liquor, 
 raise the temperature of the uppermost stra- 
 tum, almost instantly, to near the boiling 
 point, and draw it off in vapour. The great 
 extent, rapidity and economy of this process, 
 recommend it to general adoption on the 
 great scale. 
 
 Mr Barry has lately obtained a patent for 
 an apparatus, by which vegetable extracts 
 for the apothecary may be made at a very 
 gentle heat and in vacuo. From these two 
 circumstances, extracts thus prepared differ 
 from those in common use, not only in their 
 physical, hut medicinal properties. The taste 
 and smell of the extract of hemlock made in 
 this way are remarkably different, as is the 
 colour both of the soluble and feculent parts. 
 The form of apparatus is as follows: — 
 
 The evaporating pan, or still, is a hemi- 
 spherical dish of cast-iron, polished on its 
 inner surface, and furnished with an air- 
 tight flat lid. From the centre of this a pipe 
 rises, and bending like the neck of a retort. 
 
EVA 
 
 EUD 
 
 it forms a declining tube, which terminates 
 in a copper sphere of a capacity three (four ?) 
 times greater than that of the still. There is 
 a stop-cock on that pipe, midway between the 
 still and the globe, and another at the under 
 side of the latter. 
 
 The manner of setting it to work is this : — 
 The juice, or infusion, is introduced through 
 a large opening into the polished iron still, 
 which is then closed, made air-tight, and 
 covered with water. The stop- cock, which 
 leads to the sphere, is also shut. Jn order 
 to produce the vacuum, steam, from a se- 
 parate apparatus, is made to rush, by a pipe, 
 through the sphere, till it has expelled all 
 the air, for which five minutes are commonly 
 sufficient. This is known to be effected, by 
 the steam issuing uncondensed. At that 
 instant the copper sphere is closed, the steam 
 shut off, and cold water admitted on its ex- 
 ternal surface. The vacuum thus produced 
 in the copper sphere, which contains four- 
 lifths of the air of the whole apparatus, is 
 now partially transferred to the still, by open- 
 ing the intermediate stop-cock. Thus, four- 
 fifths of the air in the still rush into the 
 sphere, and the stop-cock being shut again, 
 a second exhaustion is effected by steam in 
 the same manner as the first was; after 
 which, a momentary communication is again 
 allowed between the iron still and the re- 
 ceiver; by this means, four-fifths of the air 
 remaining, after the former exhaustion, are 
 expelled. These exhaustions, repeated five 
 or six times, are usually found sufficient to 
 raise the mercurial column to the height of 
 28 inches. The water bath, in which the 
 iron still is immersed, is now to be heated, 
 until the fluid that is to be inspissated begins 
 to boil, which is known by inspection through 
 a window in the apparatus, made by fasten- 
 ing on, air-tight, a piece of very strong glass ; 
 and the temperature at which the boiling 
 point is kept up, is determined by a thermo- 
 meter. Ebullition is continued until the 
 fluid is inspissated to the proper degree of 
 consistence, which also is tolerably judged of 
 by its appearance through the glass window. 
 The temperature of the boiling fluid is usual- 
 ly about 100° F. but it might be reduced to 
 nearly 90°. 
 
 In the sixtli volume of the Annals of 
 Philosophy, l)r Prout has described an in- 
 genious apparatus by means of which he can 
 subject substances, which he wishes thorough- 
 ly to dry, to the influence of a gentle heat, 
 conjoined with the desiccating power of sul- 
 phuric acid on bodies placed in vacuo. See 
 Congelation. 
 
 From M. Biot’s report, it seems to have 
 been ascertained in some French manufac- 
 tories, that evaporation goes on more rapidly 
 from a liquid boiling in a covered vessel, from 
 the top of which a pipe issues, than when the 
 liquid is freely exposed to the air ; the fuel 
 
 or heat applied, and extent of surface, being 
 the same in both cases.* 
 
 * Euchlorine. Protoxide of Chlorine.* 
 
 * Euclase. Prismatic Emerald.* 
 
 Eudiometer. An instrument for ascer- 
 taining the purity of air, or rather the quan- 
 tity of oxygen contained in any given bulk 
 of elastic fluid. Dr Priestley’s discovery of 
 the great readiness with which nitrous gas 
 combines with oxygen, and is precipitated in 
 the form of nitric acid, see Acid (Nitric), 
 was the basis upon which he constructed the 
 first instrument of this kind. 
 
 His method was very simple : a glass ves- 
 sel, containing an ounce by measure, was 
 filled with the air to be examined, which was 
 transferred from it to a jar of an inch and 
 half diameter inverted in water; an equal 
 measure of fresh nitrous gas was added to it * 
 and the mixture was allowed to stand two 
 minutes. If the absorption were very con- 
 siderable. more nitrous gas was added, till 
 all the oxygen appeared to be absorbed. 
 The residual gas was then transferred into a 
 glass tube two feet long, and one-third of an 
 inch wide, graduated to tenths and hun- 
 dredths of an ounce measure ; and thus the 
 quantity of oxygen absorbed was measured 
 by the diminution that had taken place. 
 
 Von Humboldt proposes that the nitrous 
 gas should be examined, before it is used, by 
 agitating a given quantity with a solution of 
 sulphate of iron. 
 
 Sir H. Davy employs the nitrous gas in a 
 different manner. He parses it into a satur- 
 ated solution of green muriate or sulphate of 
 iron, which becomes opaque and almost black 
 when fully impregnated with the gas. The 
 air to be tried is contained in a small gradu- 
 ated tube, largest at the open end, which is 
 introduced into the solution, and then gently 
 inclined toward the horizon, to accelerate the 
 action, which will be complete in a few 
 minutes, so as to have absorbed all the oxy- 
 gen. He observes, that the measure must 
 be taken as soon as this is done, otherwise 
 the bulk of the air will be increased by a 
 slow decomposition of the nitric acid formed. 
 
 Volta had recourse to the accension of 
 hydrogen gas. For this purpose, two mea- 
 sures of hydrogen are introduced into a gra- 
 duated tube with three of the air to be ex- 
 amined, and fired by the electric spark. The 
 diminution of bulk, observed after the ves- 
 sel had returned to its original temperature, 
 divided by three, gives the quantity of oxygen 
 consumed. 
 
 Phosphorus and sulphuret of potasli have 
 likewise been employed in eudiometry. 
 
 A piece of phosphorus may be introduced 
 by means of a glass rod into a tube contain- 
 ing the air to be examined standing over 
 water, and suffered to remain till it has ab- 
 sorbed its oxygen ; which, however, is a slow 
 process. Or a glass tube maybe filled with 
 
EUD 
 
 EUI) 
 
 mercury and inverted, and a piece of phos- 
 phorus, dried with blotting paper, introduced, 
 which will of course rise to the top. It is 
 there to be melted, by bringing a red-hot 
 iron near the glass, and the air to be admit- 
 ted by little at a time. At each addition the 
 phosphorus inflames; and, when the whole 
 has been admitted, the red-hot iron may be 
 applied again, to ensure the absorption of all 
 the oxygen. In either of these modes l-40th 
 of the residuum is to be deducted, for the 
 expansion of the nitrogen, by means of a little 
 phosphorus which it allbrds. 
 
 Professor Hope of Edinburgh employs a 
 very convenient eudiometer, when sulphuret 
 of potash or Sir II. Davy’s liquid is used. 
 It consists of two glass vessels, one to hold 
 the solution of sulphuret of potash, or other 
 eudiometric liquor, about two inches in dia- 
 meter, and three inches high, with a neck at 
 the top as usual, and a tubulure, to be closed 
 with a stopple in the side near the bottom : 
 the other is a tube, about eight inches and a 
 half long, with a neck ground to fit into that 
 of the former. This being filled with the 
 air to be examined, and its mouth covered 
 with a flat piece of glass, is to be intro- 
 duced under water, and there inserted into 
 the mouth of the bottle. Taking them out 
 of the water, and inclining them on one side, 
 they are to be well shaken, occasionally loos- 
 ening the stopper in a basin filled with water, 
 so as to admit this fluid to occupy the va- 
 cuum occasioned by the absorption. Bottles 
 of much smaller size than here mentioned, 
 which is calculated for public exhibition, 
 may generally be employed; and, perhaps, a 
 graduated tube, ground to fit into the neck 
 of a small phial, without projecting within it, 
 may be preferable on many occasions, loosen- 
 ing it a little under water, from time to time, 
 as the absorption goes on. 
 
 * Mr Dalton has written largely on the ni- 
 trous gas eudiometer. He says, that 21 mea- 
 sures of oxygen can unite with 36 measures, 
 or twice 36 — 72 measures, of nitrous gas ; 
 that is, 100 with 171.4 or 342.8. Phil. Mag. 
 vol. xxiii. and Manch. Mem. new scries, 1 . 
 
 M. Gay Lussac, in his excellent memoir 
 on nitrous vapour and nitrous gas, has prov- 
 ed, that no confidence can be reposed in these 
 directions of Mr Dalton for analyzing gases. 
 Nitrous gas is there fully demonstrated to be 
 a compound of equal volumes of oxygen and 
 azote, and the apparent contraction of their 
 volume is null ; for 100 of the one and 100 
 of the other produce exactly 200 of nitrous 
 gas. Nitric acid is composed of 100 parts 
 of azote, and 200 of oxygen, or of 100 oxy- 
 gen and 200 nitrous gas; — (100 o. -{- 
 100 az. ) Nitrous vapour, or, more accu- 
 rately speaking, nitrous acid gas, results 
 from the combination of 100 of oxygen with 
 300 of nitrous gas. Hence, by giving pre- 
 dominance alternately to tha oxygen and to 
 
 the nitrous gas, we obtain 300 of absorption 
 and nitric acid, or 400 of absorption and 
 nitrous acid. The nitrous acid gas is an 
 identical compound, very soluble in water, 
 which it colours at first blue, then green, 
 and lastly, orange-yellow'. This liquid, with 
 the alkalis, forms nitrites. These clear and 
 simple facts constitute the whole theory of 
 the formation of the nitrous and nitric acids, 
 by means of nitrous gas and oxygen, and per- 
 fectly explain the differences of the results of 
 all those who have operated with them. We 
 have now only to shew, how r we may render 
 the use of nitrous gas perfectly accurate in 
 eudiometry. 
 
 It is stated above, that we obtain nitric 
 acid and an absorption represented by three, 
 or nitrous acid and a diminution of volume 
 represented by four, every time, according as 
 the oxygen or nitrous gas predominates in 
 the mixture of these two gases. Now, since 
 the object is to withdraw the w'hole oxygen 
 from air, we must add the nitrous gas in ex- 
 cess to it, and cause thus a diminution of vo- 
 lume, four times greater than the volume of 
 the contained oxygen. Notwithstanding this 
 precaution, if w r e make the mixture in a very 
 narrow tube, the nitrous vapour would be 
 absorbed with difficulty by the water, on ac- 
 count of the narrow contact, and agitation 
 would become necessary. But in this case, 
 nitrous gas, to the amount of 10 or 12 per 
 cent, would be absorbed. It is from this 
 cause, that on mixing 100 parts of air with 
 100 of nitrous gas, very variable absorptions 
 were obtained, of which the mean was 93 ; 
 wdiilst air, containing at utmost 21 per cent 
 of oxygen, the absorption should be only 
 four times this quantity, or 84. Nor is it a 
 matter of indifference, to put the nitrous gas 
 in the tube before, or after the other gas ; 
 for if we introduce it first, there might be 
 formed both nitrous and nitric acids. Know- 
 ing these tw'O causes of error, it is easy to 
 avoid them, by obeying the following injunc- 
 tions of M. Gay Lussac. 
 
 Instead of selecting a very narrow tube, 
 as Mr Dalton prescribed, we must take a 
 very wide tube, a tumbler for example, and 
 after having introduced into it 100 of the air 
 to be examined, we must pass into it 100 
 parts of the nitrous gas. There is instantly 
 exhibited a red vapour, which disappears 
 very speedily without agitation, and after 
 half a minute, or a minute at most, the ab- 
 sorption may be regarded as complete. Me 
 transfer the residuum into a graduated tube, 
 and we shall find the absorption to be almost 
 uniformly 84 parts, provided atmospheric 
 air was used, one-fourth of which = 21, 
 indicates the quantity per cent of oxygen. 
 
 M. Gay Lussac shews, by numerous ex- 
 periments, the accuracy of the above process, 
 in varied circumstances. We have thus the 
 advantage of estimating the proportion of 
 
EUD 
 
 EUD 
 
 oxygen in any gas, by an absorption four 
 times greater than its own volume ; so that 
 the errors of experiment are reduced to one- 
 fourth, on the quantity of oxygen. Now, as we 
 can never commit a mistake of four degrees, 
 the error must be less than one per cent. 
 We must never agitate, or use an under pro- 
 portion of nitrous gas, nor yet carry its ex- 
 cess too far, on account of its solubility in 
 water. 
 
 An apparatus for analyzing gases, con- 
 taining oxygen or chlorine, by explosion 
 with hydrogen, was communicated by me to 
 the Royal Society of Edinburgh, and pub- 
 lished in the volume of their Transactions 
 for 1817 and 1818. 
 
 Description of an Apparatus for the Ana- 
 lysis of Gaseous Matter bp Explosion. By 
 
 Dr Ure. 
 
 The analysis of combustible gases, and 
 supporters of combustion, reciprocally, by 
 explosion, with the electric spark, furnishes, 
 when it can be applied, one of the speediest 
 and most elegant methods of chemical re- 
 search. The risk of failure to which the 
 chemist is exposed, in operating with the 
 simple tube, from the ejection of the mer- 
 cury, and escape or introduction of the air ; 
 or of injury from the bursting of the glass, 
 by the forcible expansion of some gaseous 
 mixtures, has given rise to several modifica- 
 tions of apparatus. 
 
 Volta’s mechanism, which is employed 
 very much at Paris, is complex and expen- 
 sive,-}- while it is hardly applicable to experi- 
 ments over mercury. Mr Pepys’ ingenious 
 contrivance, in which the glass tube is con- 
 nected with a metallic spring, to diminish 
 the shock of explosion, is liable also to some 
 of the above objections. 
 
 A very simple form of instrument occurred 
 to me about two years ago, in which the at- 
 mospheric air, the most elastic and economi- 
 cal of all springs, is employed to receive and 
 deaden the recoil. Having frequently used 
 it since that time, I can now recommend it 
 to the chemical world, as possessing every 
 requisite advantage of convenience, cheap- 
 ness, safety, and precision. 
 
 It consists of a glass syphon, having an 
 interior diameter of from 2-10ths to 4-10ths 
 of an inch. Its legs are of nearly equal 
 length, each being from six to nine inches 
 long. The open extremity is slightly funnel- 
 shaped ; the other is hermetically sealed ; 
 and has inserted near it, by the blow- pipe, 
 two platina wires. The outer end of the one 
 wire is incurvated across, so as nearly to 
 touch the edge of the aperture ; that of the 
 other is formed into a little hook, to allow a 
 small spherical button to be attached to it, 
 when the electrical spark is to be transmit- 
 
 t The price of the Apparatus is three guineas. 
 
 ted. The two legs of the syphon are from 
 one-fourth to one-half inch asunder. 
 
 The sealed leg is graduated, by introduc- 
 ing successively equal weights of mercury 
 from a measure glass tube. Seven ounces 
 troy and 66 grains, occupy the space of a 
 cubic inch ; and 54 J grains represent 
 part of that volume. The other leg may be 
 graduated also, though this is not necessary. 
 The instrument is then finished. 
 
 To use it, we first fill the whole syphon 
 with mercury or water, which a little practice 
 will render easy. We then introduce into 
 the open leg, plunged into a pneumatic 
 trough, any convenient quantity of the gases, 
 from a glass measure tube, containing them 
 previously mixed in determinate proportions. 
 Applying a finger to the orifice, we next re- 
 move it from the trough in which it stands, 
 like a simple tube ; and by a little dexterity, 
 we transfer the gas into the sealed leg of the 
 syphon. When we conceive enough to have 
 been passed up, we remove the finger, and 
 next bring the mercury to a level in both 
 legs, either by the addition of a few drops, 
 or by the displacement of a portion, by 
 thrusting down into it a small cylinder of 
 wood. We now ascertain, by careful in- 
 spection, the volume of included gas. Ap- 
 plying the fore-finger again to the orifice, so as 
 also to touch the end of the platina wire, we 
 then approach the pendent ball or button 
 to the electrical machine, and transmit the 
 spark. Even when the included gas is con- 
 siderable in quantity, and of a strongly ex- 
 plosive power, we feel at the instant nothing 
 but a slight push or pressure on the tip of the 
 finger. After explosion, when condensation 
 of volume ensues, the finger will feel pressed 
 down to the orifice by the superincumbent 
 atmosphere. On gradually sliding the fin- 
 ger to one side, and admitting the air, the 
 mercurial column in the sealed leg will rise 
 more or less above that in the other. We 
 then pour in this liquid metal, till the equili- 
 brium be again restored, when we read off 
 as before, without any reduction, the true re- 
 sulting volume of gas. 
 
 As we ought always to leave two inches 
 or more of air, between the finger and the 
 mercury, this atmospheric column serves as 
 a perfect recoil spring, enabling us to ex- 
 plode very large quantities without anv in- 
 convenience or danger. The manipulation 
 is also, after a little practice, as easy as that 
 of the single tube. But a peculiar advan- 
 tage of this detachable instrument is, to en- 
 able us to keep our pneumatic troughs, and 
 electrical machine, at any distance which 
 convenience may require ; even in different 
 chambers, which, in the case of wet weather, 
 or a damp apartment, may be found neces- 
 sary to ensure electrical excitation. In the 
 immediate vicinity of the water pneumatic 
 cistern, we know how often the electric 
 
EUP 
 
 EXC 
 
 spark refuses to issue from a good elcctro- 
 phorus, or even little machine. Besides, no 
 discharging rod or communicating wire is 
 here required. Holding the eudiometer in 
 the left hand, we turn the handle of the ma- 
 chine, or lift the electrophorus plate with the 
 right, and approaching the little ball, the ex- 
 plosion ensues. The electrician is well 
 aware, that a spark so small as to excite no 
 unpleasant feeling in the finger, is capable, 
 when drawn otf by a smooth ball, of inflam- 
 ing combustible gas. Even this trifling cir- 
 cumstance may be obviated, by hanging on a 
 slender wire, instead of applying the finger. 
 
 We may analyze the residual gaseous 
 matter, by introducing either a liquid or a 
 solid reagent. We first fill the open leg 
 nearly to the brim with quicksilver, and then 
 place over it the substance whose action on 
 the gas we wish to try. If liquid, it may 
 be passed round into the sealed leg among 
 the gas ; but if solid, fused potash, for ex- 
 ample, the gas must be brought round into 
 the open leg, its orifice having been previous- 
 ly closed with a cork or stopper. After a 
 proper interval, the gas being transferred 
 back into the graduated tube, the change of 
 its volume may be accurately determined. 
 With this eudiometer, and a small mercurial 
 pneumatic cistern, we may perform pneu- 
 matic analyses on a very considerable scale. 
 
 It may be desirable in some cases, to have 
 ready access to the graduated leg, in order to 
 dry it speedily. This advantage is obtained, 
 by closing the end of the syphon, not herme- 
 tically, but with a little brass cap screwed 
 on, traversed vertically by a platina wire in- 
 sulated in a bit of thermometer tube. After 
 the apparatus has been charged with gas for 
 explosion, we connect the spherical button 
 with the top of the wire. 
 
 With the above instrument I have explod- 
 ed half a cubic inch of hydrogen mixed with 
 a quarter of a cubic inch of oxygen ; as also, 
 a bulk nearly equal of an olefiant gas ex- 
 plosive mixture, without any unpleasant con- 
 cussion or noise; so completely does the air- 
 chamber abate the expansive violence, as well 
 as the loudness of the report. Projection of 
 the mercury, or displacement of the gas, is 
 obviously impossible. Edin. Phil. Trans. 
 January 1818.* 
 
 Euphorbium. A gum-resin exudingfrom 
 a large oriental shrub, Euphorbia officin. 
 Linn. 
 
 It is brought to us immediately from Bar- 
 bary, in drops of an irregular form ; some 
 of which upon being broken are found to 
 contain little thorns, small twigs, flowers, 
 and other vegetable matters ; others are 
 hollow, without any thing in their cavity: 
 the tears in general are of a pale yellow co- 
 lour externally, somewhat white withinside : 
 they easily break betwixt the fingers. Sp. gr. 
 2.124. Slightly applied to the tongue, they 
 
 affect it with a very sharp biting taste ; and, 
 upon being held for some time in the mouth, 
 prove vehemently acrimonious, inflaming and 
 exulcerating the fauces, & c. Euphorbium 
 is extremely troublesome to pulverize, the 
 finer part of the powder, which flies off, 
 affecting the head in a violent manner. The 
 acrimony is so great, as to render it abso- 
 lutely unfit for any internal use. It is 
 much employed in the veterinary art as an 
 epispastic : 
 
 * The following constituents were found in 
 Euphorbium by Braconnot : 
 
 Resin, - 
 
 Wax, 
 
 Mulate of lime, 
 Mulate of potash, 
 Water, 
 
 Woody matter, 
 Loss, 
 
 37.0 
 
 19.0 
 
 20.5 
 2.0 
 
 5.0 
 
 13.5 
 
 3.0 
 
 100.0 
 
 The resin is excessively acrid, poisonous, 
 reddish coloured, and transparent. It dis- 
 solves in sulphuric and nitric acid, but not in 
 alkalis, in which respect it differs from other 
 resins. Euphorbium itself is pretty soluble 
 in alcohol.* 
 
 * Excrements. The constituents of human 
 feces, according to the recent analysis of Ber- 
 zelius, are the following : 
 
 Water, - - - 
 
 Vegetable and animal remains, - 
 Bile, - - 
 
 Albumen, - - - 
 
 Peculiar extractive matter, 
 
 Salts, - - - 
 
 Slimy matter, consisting of picromel, 
 peculiar animal matter, and inso- 
 luble residue, - - 1 4.0 
 
 73.3 
 
 7.0 
 
 0.9 
 
 0.9 
 
 2.7 
 
 1.2 
 
 100.0 
 
 The salts were to one another, in the fol- 
 lowing proportions: 
 
 Carbonate of soda, 
 
 0.9 
 
 Muriate of soda, 
 
 0.1 
 
 Sulphate of soda, 
 
 0.05 
 
 Ammon, phos. magn. 
 
 0.05 
 
 Phosphate of lime, 
 
 0.1 
 
 1.20 
 
 Thaer and Einhof obtained, by ignition, 
 from 3840 grains of the excrements of cattle, 
 fed at the stall chiefly on turnips, the follow- 
 ing earths and salts : 
 
 Lime, - 
 
 Phosphate of lime, 
 
 Magnesia, - 
 Iron, - 
 
 Alumina with some manganese, 
 
 Silica, - 
 
 Muriate and sulphate of potash, 
 
 12 . 
 
 12.5 
 
 2.0 
 
 5.0 
 
 14.0 
 
 52.0 
 1.2 
 
 Exfansion. See Caloric. 
 
 98.7* 
 
FAT 
 
 FAT 
 
 Extract. When decoction is carried to 
 such a point as to afford a substance either 
 solid or of the consistence of paste, this re- 
 sidual product is called an extract. When 
 chemists speak ot extract, they most com- 
 monly mean the product of aqueous decoc- 
 tion ; but the earlier chemists frequently 
 speak of spirituous extract. 
 
 Extracts thus prepared are mixtures of 
 several of the materials of vegetables, whence 
 they differ greatly, according to the plants 
 from which they are obtained ; but modern 
 chemists distinguish by the name ot extiact, 
 or extractive matter , a peculiar substance, 
 supposed to be one of the immediate mate- 
 rials of vegetables, and the same in all, when 
 separated from any foreign admixture, except 
 as the proportion of its constituent principles 
 may vary. See Evaporation. 
 
 Eve. The humours of the eye had never 
 been examined with any degree of accuracy 
 till lately by M. Chenevix. Most of his ex- 
 periments were made with the eyes of sheep, 
 as fresh as they could be procured. 
 
 The aqueous humour is a clear, transpa- 
 rent liquid, with little smell or taste, and of 
 
 the temperature of 60°, its specific gravity is 
 ] .009. It consists of water, albumen, gela- 
 tine, and muriate of soda. 
 
 The crystalline contains a much larger 
 proportion of water, and no muriate. Its 
 
 specific gravity is 1.1. 
 
 The vitreous humour, when pressed 
 through a rag to free it from its capsules, 
 differed in nothing from the aqueous, either 
 in its specific gravity or chemical nature. 
 
 Fourcroy mentions a phosphate as con- 
 tained in these humours, but INI. Thenevix 
 could discover none. 
 
 The humours of the human eye gave the 
 same products, but the specific gravity of the 
 crystalline w r as only 1.079, and tiiat of the 
 aqueous and vitreous humours 1.0053. 
 
 The eyes of oxen differed only in the spe- 
 cific gravity of the parts, that of the crystal- 
 line being 1.0765, and that of the other hu- 
 mours 1.0088. 
 
 The specific gravity of the crystalline is 
 not equal throughout, its density increasing 
 from the surface to the centre. — Phil Trans . 
 1803. 
 
 ♦pAHLUNITE. Automalite , a subspc- 
 X cies of octohedral corundum.* 
 
 Farina. Vegetable flour. 
 
 * Fat. Concerning the nature of this im- 
 portant product of animalization, nothing de- 
 finite was known, till M. Chevreul devoted 
 himself with meritorious zeal and perseve- 
 rance to its investigation. He has already 
 published in the Annales de Chimie, seven 
 successive memoirs on the subject, each of 
 them surpassing its predecessor in interest. 
 We shall in this article give a brief abstract 
 of the whole. 
 
 By dissolving fat in a large quantity of 
 alcohol, and observing the manner in which 
 its different portions were acted upon by this 
 substance, and again separated from it, it is 
 concluded that fat is composed of an oily 
 substance , which remains fluid at the ordi- 
 nary temperature of the atmosphere ; and of 
 another fatty substance which is much less 
 fusible. Hence it follows, that fat is not 
 to be regarded as a simple principle, but as 
 a combination of the above two principles, 
 which may be separated without alteration. 
 One of these substances melts at about 45°, 
 the other at 100° ; the same quantity of al- 
 cohol which dissolves 3.2 parts of the oily 
 substance , dissolves 1.8 only of the fatty 
 substance ; the first is separated from the al- 
 cohol in the form of an oil ; the second in 
 that of small silky needles. See Elain. 
 
 Each of the constituents of natural fat 
 
 was then saponified by the addition of pot- 
 ash; and an accurate description given of 
 the compounds which weie formed, and of 
 the proportions of their constituents. The 
 oily substance became saponified more readi- 
 ly than the fatty substance ; the residual 
 fluids in both cases contained the sweet oily 
 principle ; but the quantity that proceeded 
 from the soap formed of the oily substance y 
 was four or five times as much as that from 
 the fatty substance ; the latter soap was 
 found to contain a much greater proportion 
 of the yearly matter than the former, in the 
 proportion of 7.5 to 2.9 ; the proportion of 
 the fluid fat was the reverse, a greater quan- 
 tity of this being found in the soap formed 
 from the oily substance of the fat. 
 
 When the principles which constitute fat 
 unite with potash, it is probable that they 
 experience a change in the proportion of 
 their elements; this change developes at 
 least three bodies, margarine , f uid fat , and 
 the sweet principle; and it is remarkable, 
 that it takes place without the absorption of 
 any foreign substance, or the disengagement 
 of any of the elements which are separated 
 from each other. As this change is effected 
 by the intermedium of the alkali, we may 
 conclude that the newly formed principles 
 must have a strong affinity for salifiable 
 bases, and will in many respects resemble 
 the acids ; and, in fact, they exhibit the 
 leading characters of acids in reddening lit- 
 
FAT 
 
 FAT 
 
 mug, in decomposing the alkaline carbonates 
 to unite to their bases, and in neutralizing 
 the specific properties of the alkalis. 
 
 Having already pointed out the analogy 
 between the properties of acids and the prin- 
 ciples into which fat is converted by means 
 of the alkalis, the next object was to examine 
 the action which other bases have upon fat, 
 and to observe the effect of water, and of 
 the cohesive force of the bases upon the pro- 
 cess ot saponification, I he substances which 
 the author subjected to experiment, were 
 soda, the four alkaline earths, alumina, and 
 the oxides of zinc, copper, and lead. After 
 giving a detail of the processes which he 
 employed with these substances respectively, 
 he draws the following general conclusions': 
 — Soda, barytes, strontian, lime, the oxide of 
 tine, and the protoxide of lead, convert fat 
 into margarine , fluid fat, the sweet principle, 
 the yellow colouring principle , and the odorous 
 principle , precisely in the same manner as 
 potash. Whatever be the base that has been 
 employed, the products of saponification al- 
 ways exist in the same relative proportion. 
 As the above mentioned bases form with 
 margarine and the fluid fat compounds 
 which are insoluble in water, it follows, that 
 the action of this liquid, as a solvent of soap, 
 is not essential to the process of saponifica- 
 tion. It is remarkable that the oxides of 
 zinc and of lead, which are insoluble in wa- 
 ter, and which produce compounds equally 
 insoluble, should give the same results with 
 potash and soda, a circumstance which 
 proves that those oxides have a strong al- 
 kaline pow'er. Although the analogy of 
 magnesia to the alkalis is, in other respects, 
 so striking, yet we find that it cannot con- 
 vert fat into soap under the same circum- 
 stances with the oxides of zinc and lead. 
 
 It was found that 100 parts of hog’s-lard 
 were reduced to the completely saponified 
 state by 16.36 parts of potash. See Elain 
 and Acid (Margaric). 
 
 The properties of spermaceti were next 
 examined : it melts at about 112°; it is not 
 much altered by distillation ; it dissolves 
 readily in hot alcohol, but separates as the 
 fluid cools ; the solution has no effect in 
 changing the colour of the tincture of lit- 
 mus, a circumstance, as it is observed, in 
 which it differs from margarine, a substance 
 which, in many respects, it resembles. 
 Spermaceti is capable of being saponified by 
 potash, with nearly the same phenomena as 
 when we submit hog’s-lard to the action ot 
 potash, although the operation is effected 
 with more difficulty. 
 
 The author’s general conclusion respect- 
 ing the fatty matter of dead bodies is, that 
 even after the lactic acid, the lactates, and 
 other ingredients which are less essential, 
 are removed from it, it is not a simple, am- 
 moniacal soap, but a combination of various 
 
 fatty substances with ammonia, potash, and 
 lime. The fatty substances which were se- 
 parated from alcohol, had different melting 
 points and different sensible properties. It 
 follows, from M. Chevreul’s experiments, 
 that the substance which is the least fusible, 
 has more affinity for bases than those which 
 are more so. It is observed, that adipocere 
 possesses the characters of a saponified fat ; 
 it is soluble in boiling alcohol in all propor- 
 tions, reddens litmus, and unites readily to 
 potash, not only without losing its weight, 
 but without having its fusibility or other 
 properties changed. 
 
 M. Chevreul has shown, that hog’s-lard, 
 in its natural state, has not the property of 
 combining with alkalis; but that it acquires 
 it by experiencing some change in the pro- 
 portion of its elements. This change being 
 induced by the action of the alkali, it fol- 
 lows that the bodies of the new formation 
 must have a decided affinity for the species 
 of body which has determined it. If we ap- 
 ply this foundation of the theory of saponi- 
 fication to the change into fat, which bodies 
 buried in the earth experience, we shall find 
 that it explains the process in a very satisfac- 
 tory manner. In reality, the fatty matter is 
 the combination of the two adipose sub- 
 stances with ammonia, lime, and potash ; 
 one of these substances has the same sensible 
 properties with margarine procured from 
 the soap of hog’s-lard ; the other, the 
 orange-coloured oil, excepting its colour, 
 appears to have a strong analogy with the 
 fluid fat. From these circumstances, it is 
 probable that the formation of the fatty mat- 
 ter may be the result of a proper saponifica- 
 tion produced by ammonia, proceeding from 
 the decomposition of the muscle, and by the 
 potash and lime, which proceed from the 
 decomposition of certain salts. 
 
 The author remarks, that he has hitherto 
 made use of periphrases when speaking of 
 the different bodies that he has been describ- 
 ing, as supposing that their nature was not 
 sufficiently determined. lie now, however, 
 conceives, that he may apply specific names 
 to them, which will both be more commo- 
 dious, and, at the same time, by being 
 made appropriate, will point out the relation 
 which these bodies bear to each other. The 
 following is the nomenclature which he 
 afterwards adopted : — The crystalline matter 
 of human biliary calculi is named chole- 
 sterine, from the Greek words % o\n bile, 
 and nptos solid ; spermaceti is named cetinc , 
 from xvros, a whale ; the fatty substance 
 and the oily substance, are named respec- 
 tively, stearine and ela'ine , from the words 
 <riao fat, and tXcuov oil ; margarine and the 
 fluid fat obtained after saponification, are 
 named margaric acid and oleic acid, while 
 the term cetic acid, is applied to what was 
 named saponified spermaceti. The marga- 
 
FAT 
 
 FAT 
 
 rates , oleates, and ce tales, will be the generic 
 names of the soaps or combinations which 
 these acids are capable of forming by their 
 union with salifiable bases. 
 
 Two portions of human fat were examin- 
 ed, one taken from the kidney the other 
 from the thigh : after some time they both 
 of them manifested a tendency to separate 
 into two distinct substances, one of a solid, 
 and the other of a fluid consistence; the two 
 portions differed in their fluidity and their 
 melting point. These variations depend 
 upon the different proportions of stearine 
 and elaine ; for the concrete part of fat is a 
 combination of the two with an excess of 
 stearine, and the fluid part is a combination 
 with an excess of elaine. The fat from the 
 other animals was then examined, principal- 
 ly with respect to their melting point and 
 their solubility in alcohol ; the melting 
 point was not always the same in the fat of 
 the same species of animal. When portions 
 of the fat of different sheep are melted sepa- 
 rately at the temperature of 122°, in some 
 specimens the thermometer descends to 
 98.5°, and rises again to 102°, while in 
 others it descends to 104°, and rises again 
 to 106°. A thermometer plunged into the 
 fat of the ox melted at 122°, descended to 
 98.5°, and rose again to 102°. When the 
 fat of the jaguar was melted at 104°, the 
 thermometer descended to 84°, and rose 
 again to about 85° ; but a considerable por- 
 tion of the fat still remained in a fluid state. 
 With respect to the solubility of the different 
 kinds of fat in alcohol, it was found that 
 100 parts of it dissolved 2.48 parts of human 
 fat, 2.26 parts of sheep’s fat, 2.52 parts of 
 the fat of the ox, 2.18 parts of the fat of the 
 jaguar, and about 2.8 parts of the fat of the 
 hog. 
 
 M. Chevreul next examines the change 
 which is produced in the different kinds 
 of fat respectively by the action of potash. 
 All the kinds of fat are capable of being 
 perfectly saponified, when excluded from 
 the contact of the air; in all of them there 
 was the production of the saponified fat and 
 the sweet principle; no carbonic acid was 
 produced, and the soaps formed contained 
 no acetic acid, or only slight traces of it. 
 'J he saponified fats had more tendency to 
 crystallize in needles than the fats in their 
 natural state ; they were soluble in all pro- 
 portions in boiling alcohol of the specific 
 gravity of ,821. The solution, like that of 
 the saponified fat of the hog, contained both 
 the margaric and the oleic acids. They 
 were less fusible than the fats from which 
 they were formed ; thus, when human fat, 
 after being saponified, was melted, the ther- 
 mometer became stationary at 95°, when 
 the fluid began to congeal ; in that of the 
 sheep, the thermometer fell to 118.5°, and 
 rose to 122°; in that of the ox it remained 
 
 stationary at 118.5°; and in that ot the ja- 
 guar at 96.5°. 
 
 The saponified fat of the sheep and t.ie 
 ox, had the same degree of solubility in pot- 
 ash and soda, as that of the hog. 
 
 100 parts of the fat of ~] 
 the sheep when sapo- ! 
 nified were dissolved J 
 
 by J 
 
 100 parts of the same ( 
 were dissolved by j 
 100 parts of the saponi- 
 fled fat of the ox were ^ 
 dissolved by J 
 
 100 parts of the same } 
 were dissolved by f 
 1 00 parts of the saponi- ~] 
 fied fat of the hog j* 
 were dissolved by J 
 100 parts of the same | 
 were dissolved by j 
 The following table contains the proportions 
 of the saponified fat, and of the matter solu- 
 ble in water, into which 100 parts of the fat 
 are capable of being changed : — 
 
 Human fat 
 
 Saponified fat, 95 
 
 Soluble matter, 5 
 
 Fat of the sheep. 
 Saponified fat, 95.1 
 
 Soluble matter, 4.9 
 
 Fat of the ox. 
 Saponified fat, 95 
 
 Soluble matter, 5 
 
 Fat of the hog. 
 Saponified fat, 94 . 7 
 
 Soluble matter, 5. 3 
 
 M. Chevreul next gives an account of the 
 analysis of fat by alcohol. 
 
 The method of analysis employed was to 
 expose the different kinds of fat to boiling 
 alcohol, and to suffer the mixture to cool ; 
 a portion of the fat that had been dissolved 
 was then separated in two state's of combi- 
 nation ; one with an excess of stearine was 
 deposited, the other with an excess of elaine 
 remained in solution. The first was sepa- 
 rated by filtration, and by distilling the fil- 
 tered fluid and adding a little water towards 
 the end of the operation, we obtain the se- 
 cond in the retort, under the form of an al- 
 coholic aqueous fluid. The distilled alcohol 
 which had been employed in the analysis of 
 human fat had no sensible odour; the same 
 was the case with that which had served for 
 the analysis of the fat of the ox, of the hog, 
 and of the goose. The alcohol which had 
 been employed in the analysis of the fat 
 of the sheep, had a slight odour of candle- 
 grease. 
 
 The varieties of stearine from the different 
 species of fat, were found to possess the 
 following properties: — They were all of a 
 
 beautiful white colour; entirely, or almost 
 without odour, insipid, and having no action 
 <2 E 
 
 a* 
 
 1 5.4 1 of potash. 
 
 10.27 of soda. 
 
 15.42 of potash. 
 10.24 of soda. 
 15.04 of potash. 
 10.29 of soda. 
 
FAT 
 
 FAT 
 
 upon litmus. — Stearine from man . The 
 
 thermometer which was plunged into it when 
 melted fell to I05.5°,and rose again to 120°. 
 By cooling, the stearine crystallized in very 
 fine needles, the surface of which was flat. — 
 Stearine of the sheep. The thermometer fell 
 to 104°, and rose again to 109.5°; it form- 
 ed itself into a flat mass; the centre, which 
 cooled more slowly than the edges, present- 
 ed small and finely radiated needles. — Stear- 
 ine of the ox. The thermometer fell to 103°, 
 and rose again to 1 1 1° ; it formed itself into 
 a mass, the surface of which was flat, over 
 which were dispersed a number of minute 
 stars visible by the microscope ; it was slight- 
 ly semi-transparent . — Stearine of the hog. 
 It exhaled the odour of hog’s-lard when it 
 was melted. The thermometer fell to 100.5°, 
 
 and rose again to 109.5°. By cooling, it 
 was reduced into a mass, the surface of which 
 was very unequal, and which appeared to be 
 formed of small needles. When it cooled 
 rapidly, the parts which touched the sides of 
 the vessel had the semi-transparency of coa- 
 gulated albumen . — Stearine of the goose. The 
 thermometer fell to 104°, and rose again to 
 109.5° ; it was formed into a flat mass. 
 
 With respect to the solubility of these 
 different bodies in alcohol, 100 parts of boil- 
 ing alcohol, of the specific gravity of 0.7952, 
 dissolved, 
 
 Of human stearine, 21.50 parts. 
 
 Of the stearine of the sheep, 16.07 
 Of the stearine of the ox, 15.48 
 Of the stearine of the hog, 1 8.25 . 
 
 Of the stearine of the goose, 36.00 
 
 The human stearine 
 produced, by saponi- 
 fication, 
 
 Stearine of the 
 sheep. 
 
 Stearine of the 
 ox. 
 
 Stearine of the 
 hog. 
 
 Stearine of the 
 goose. 
 
 i 
 
 i 
 
 l 
 
 r 
 
 1 
 
 Saponification by potash. 
 
 f It was fusible at 123.5° ; it crys- 
 Saponified fat, 94.9 <! tallized in small needles joined in 
 
 ^the form of a funnel. 
 
 The syrup of the sweet principle 
 weighed 8.6, the acetate O.S.f 
 f It began to become opaque at 
 ! 129°, and the thermometer became 
 
 Soluble matter, 5.1 
 
 i 
 
 Saponified fat, 94.6 
 
 { stationary at 127.5°; it crystallized 
 |Jn small fine radiated needles. 
 
 [“ The syrup of the sweet principle 
 Soluble matter, 5.4 < weighed 8, the acetate 0.6 ; it had a 
 
 l_rancid odour. 
 
 f It began to become solid at 1 29°, 
 ci 'cl i r nr i J but it was not perfectly so until 
 
 apom e at, Jo. j 25.5 ; it crystallized in small needles 
 
 (^united into flattened globules. 
 
 _ , , , { The syrup of the sweet principle 
 
 Soluble matter, 4.9 -< • , , ' 0 ,, . , ~ „ 
 
 ( weighed 9.8, the acetate 0.3. 
 
 [* It began to grow solid at 129°, 
 
 o • — -, /> r,. nr \ and the thermometer became station- 
 
 Sapomfied fat, 94.65^ ary at . u crystallized in smaU 
 
 ^needles united into flattened globules. 
 
 I _ . , , rnr ^ The syrup of the sweet principle 
 
 • Soluble matter, 5.35 < . , 
 
 ’ ( weighed 9, the acetate 0.4. 
 
 It became solid at 119°; it crys- 
 
 llized in needles united in the form 
 
 funnel. 
 
 ( The syrup of the sweet principle 
 ( weighed 8.2. 
 
 1 
 
 r 
 
 [“Saponified fat, 94 
 1 Soluble matter, 5.6 
 
 f i.‘ 
 
 .4 < talln 
 Lof a 
 
 All the soaps of stearine were analyzed by 
 the same process as the soap of the fat from 
 which they had been extracted ; there was 
 procured from them the pearly super-mar- 
 garate of potash and the oleate ; but the 
 first was much more abundant than the 
 second. The margaric acid of the stear- 
 ines had precisely the same capacity for 
 saturation as that which was extracted 
 from the soaps formed of fat. The mar- 
 garic acid of the stearine of the sheep was 
 
 f This means the salt which we obtain after having 
 neutralized by barytes the product of the distillation 
 of the aqueous fluid, which was procured from the 
 soap that had been decomposed fiy tartaric acid. 
 
 fusible at 144°, and that of the stearine of the 
 ox at 143.5°, while the margaric acids of 
 the hog and the goose, had nearly the same 
 fusibility with the margaric acid of the fat of 
 these animats. 
 
 On Spermaceti; or, as M. Chevreul tech- 
 nically calls it, celine. In the firth memoir, 
 in which we have an account of many of the 
 properties of this substance, it was stated, 
 that it is not easily saponified by potash, but 
 that it is converted bv this reagent into a 
 substance which is soluble in water, but has 
 not the saccharine flavour of the sweet prin- 
 ciple of oils ; into an acid analogous to the 
 margaric, to which the name of cctic "'a* 
 
FAT 
 
 FEL 
 
 applied ; and into another acid, which was 
 conceived to be analogous to the oleic. Since 
 he wrote the fifth memoir, the author has 
 made the following observations on this sub- 
 ject ; — 1. That the portion of the soap of 
 cetine which is insoluble in water, or the 
 cetate of potash, is in part gelatinous, and in 
 part pearly : 2. That two kinds ot crystals 
 were produced from the cetate of potash 
 which had been dissolved in alcohol : 3. 1 hat 
 the cetate of potash exposed, under a bell 
 glass, to the heat of a stove, produced a su- 
 blimate of a fatty matter which was not acid, 
 From this circumstance M. Chevreul was 
 led to suspect, that the supposed cetic acid 
 might be a combination, or a mixture of 
 margaric acid and of a fatty body which was 
 not acid; he accordingly treated a small 
 quantity of it with barytic water, and boiled 
 the soap which was formed in alcohol ; the 
 greatest part of it was not dissolved, and the 
 alcoholic solution, when cooled, filtered, and 
 distilled, produced a residuum of fatty mat- 
 ter which was not acid. The suspicion be- 
 ing thus confirmed, M. Chevreul determin- 
 ed to subject cetine to a new train of experi- 
 ments. Being treated with boiling alcohol, 
 a cetine was procured which was fusible at 
 3 20°, and a yellow fatty matter which began 
 to become solid at 89.5°, and which at 73.5° 
 contained a fluid oil, which was separated by 
 filtration. 
 
 Saponification of the Elaines by Potash . — 
 The determination of the soluble matter 
 which the ela'ines yield to water in the 
 process of saponification, is much more dif- 
 ficult than the determination of the same 
 point with respect to the stearines. The 
 stearines are less subject to be changed than 
 the ela'ines; it is less difficult to obtain the 
 stearines in a uniformly pure state ; besides 
 the saponified fats of the stearines being less 
 fusible than the saponified ela'ines, it is more 
 easy to weigh them without loss. The 
 ela'ines of the sheep, the hog, the jaguar, and 
 the goose, extracted by alcohol, yield by the 
 action of potash, 
 
 Of saponified fat., 89 parts, 
 
 Of soluble matter, 1 1 . 
 
 The ela'ine of the ox extracted in the same 
 manner yields, 
 
 Of saponified fat, 92.6 parts, 
 
 Of soluble matter, 7.4. 
 
 The different kinds of fat, considered in 
 their natural state, are distinguished from 
 each other by their colour, odour, and flu- 
 idity. 
 
 The stearines of the sheep, the ox. and the 
 hog, have the same degree of solubility in 
 alcohol ; the stearine of man is a little more 
 soluble, while that of the goose is twice as 
 much so. The ela'ines of man, of the sheep, 
 the ox, the jaguar, and the hog, have a spe- 
 cific gravity of about .915; that of the goose 
 of about .929. The ela'ines of the sheep, 
 
 the ox, and the hog, have the same solubili- 
 ty in alcohol ; the ela’ine of the goose is a 
 little more soluble. On the other hand, the 
 margaric acids of man, of the hog, of the ja- 
 guar, and of the goose, cannot be distinguish- 
 ed from each other; those of the sheep and 
 the ox differ a few degrees in their melting 
 point, and a little also in their form. As 
 for the slight differences which the oleic acids 
 present, they are not sufficiently precise for 
 us to be able to particularize them. See 
 Acid (Oleic). 
 
 Fecula. See Starch. 
 
 * Fecula. Green of plants. See Chlo- 
 rophyll.* 
 
 * Felspar. * This important mineral ge- 
 nus is distributed by Professor Jameson into 
 four species, viz. prismatic felspar, pyramidal 
 felspar, prismato- pyramidal felspar, and rhom- 
 boidal felspar. 
 
 I. Prismatic felspar has 9 sub-species; 
 1. Adularia ; 2. Glassy felspar ; 3. Ice- 
 
 spar ; 4. Common felspar ; 5. Labrador fel- 
 spar ; 6. Compact felspar ; 7. Clinkstone ; 
 8. Earthy common felspar ; and, 9. Porcelain 
 earth. 
 
 1. Adularia. Colour greenish-white ; iri- 
 descent ; and in thin plates, pale flesh-red by 
 transmitted light. Massive and crystallized. 
 Primitive form ; an oblique four-sided prism, 
 with 2 broad and 2 narrow lateral planes ; 
 the lateral edges are 1 20° and 60°. Secon- 
 dary forms ; an oblique four-sided prism, a 
 broad rectangular six-sided prism, a six- 
 sided table, and a rectangular four-sided 
 prism. Sometimes twin crystals occur. 
 
 The lateral planes of the prism are longi- 
 tudinally streaked. Lustre splendent, inter- 
 mediate between vitreous and pearly. Cleav- 
 age threefold. Fracture imperfect conchoidal. 
 Semi-transparent. A beautiful pearly light 
 is sometimes seen, when the specimen is 
 viewed in the direction of the broader lateral 
 planes. Refracts double. Harder than 
 
 apatite, but softer than quartz. Easily fran- 
 gible. Sp. gr. 2.5. It melts before the 
 blow-pipe, without addition, into a W'hite- 
 coloured transparent glass. Its constituents 
 are, 64 silica, 20 alumina, 2 lime, and 14 
 potash. — Vauquelin. 
 
 It occurs in contemporaneous veins, or 
 drusy cavities, in granite and gneiss, in the 
 island of Arran, in Norway, Switzerland, 
 France, and Germany. The finest crystals 
 are found in the mountain of Stella, a part 
 of St Gothard. Rolled pieces, exhibiting a 
 most beautiful pearly light, are collected in 
 the island of Ceylon. Moonstone adularia 
 is found in Greenland ; and all the varieties 
 in the United States. Under the name of 
 moonstone it is worked by lapidaries. Ano- 
 ther variety from Siberia is called sunstone 
 by the jewellers. It is of a yellowish colour, 
 and numberless golden spots appear distri- 
 buted through its whole substance. These 
 
FEL 
 
 FER 
 
 reflections of light are either from minute 
 fissures, or irregular cleavages of the mineral. 
 Hie aventurine felspar of Archangel appears 
 to be also sunstone. It is the hyaloidcs of 
 Theophrastus. 
 
 2* Glassy felspar. Colour greyish- white. 
 Crystallized in broad rectangular four-sided 
 prisms, bevelled on the extremities. Splen- 
 dent and vitreous. Cleavage threefold. 
 Fracture uneven. Transparent. Sp. gr. 
 2.57. It melts without addition into a grey 
 semi-transparent glass. Its constituents are, 
 68 silica, J 5 alumina, 14.5 potash, and 0.5 
 oxide of iron. — Klapr. It occurs imbedded 
 in pitch-stone porphyry in Arran and Rum. 
 
 3. Ice-spar. Colour greyish- white. Mas- 
 sive, cellular and porous ; and crystallized in 
 small, thin, longish six-sided tables. The 
 lateral planes are longitudinally streaked. 
 Lustre vitreous. Cleavage imperfect. Trans- 
 lucent and transparent. Hard as common 
 felspar, aud easily frangible. It occurs 
 along with nepheline, meionite, mica, and 
 hornblende, at Monte Somma near Naples. 
 
 4. Common felspar* Colours white and 
 red, of various shades ; rarely green and 
 blue. Massive, disseminated and crystalliz- 
 ed, in a very oblique four- sided prism ; an 
 acute rhombus ; elongated octohedron ; a 
 broad equiangular six-sided prism ; a rectan- 
 gular four-sided prism ; and twin crystals ; 
 which forms are diversified by various bevel- 
 ments and truncations. Cleavage threefold. 
 Lustre more pearly than vitreous. Fracture 
 uneven. Fragments rhomboidal ; and have 
 only four splendent faces. Translucent on 
 the edges. Less hard than quartz. Easily 
 frangible. Sp. gr. 2.57. It is fusible with- 
 out addition into a grey semi-transparent 
 glass. Its constituents are as follows : 
 
 Siberian green 
 felspar. 
 
 Silica, 62 .83 
 
 Alumina, 17.02 
 
 Lime, 3.00 
 
 Potash, 13.00 
 
 Oxide of iron, 1.00 
 
 Flesh-red Felspar from 
 felspar. Passau. 
 
 66.15 60.25 
 
 17.50 22.00 
 
 1.25 0.75 
 
 12.00 14.00 
 
 0.75 water, 1.00 
 
 96.85 08.25 98.00 
 
 Vauq. Hose. Rucholz. 
 
 Felspar is one of the most abundant mi- 
 nerals, as it forms a principal constituent 
 part of granite, and gneiss, and occurs occa- 
 sionally mixed with mica-slate and clay-slate. 
 It is also a constituent of whitestone and 
 syenite. It forms the basis of certain por- 
 phyries. Greenstone is a compound of 
 common felspar and hornblende. The most 
 beautiful crystals of it occur in the Alps of 
 Switzerland, in Lombardy, France, and Si- 
 beria, in veins of contemporaneous formation 
 with the granite and gneiss rocks. It occurs 
 abundantly in transition mountains, and in 
 those of the secondary class. Under the 
 
 name of petunze, it is an ingredient oi Chi- 
 
 20 
 
 nesc porcelain. When the green varieties 
 are spotted with white, they are named aven- 
 turine felspar. Another green variety from 
 South America is called the Amazon-stone, 
 from the river where it is found. 
 
 5. Labr adore felspar . Colour grey of va- 
 rious shades. When light falls on it in cer- 
 tain directions, it exhibits a great variety of 
 beautiful colours. It occurs massive, or in 
 rolled pieces. Cleavage splendent. Fracture 
 glistening. Lustre between vitreous and 
 pearly. It breaks into rhomboidal frag- 
 ments. I ranslucent in a very low degree. 
 Less easily frangible than common felspar. 
 Sp. gr. 2.6 to 2.7. It is less fusible than 
 common felspar. It occurs in roiled masses 
 of syenite, in which it is associated with 
 common hornblende, hyperstene, and mag- 
 netic ironstone, in the island of St Paul on 
 the coast of Labradore. It is found round 
 Laurwig in Norway. 
 
 6. Compact felspar. Colours, white, grey, 
 green and red. Massive, disseminated, and 
 crystallized in rectangular four-sided prism 3 . 
 Lustre glistening, or glimmering. Fracture 
 splintery and even. Translucent only on the 
 edges. Easily frangible. Sp. gr. 2.69. It 
 melts with difficulty into a whitish enamel. 
 Its constituents are, 51 silica, 30.5 alumina, 
 1 1.25 lime, 1.75 iron, 4 soda, 1.26 water. — 
 Klapr. It occurs in mountain masses, beds 
 and veins : in the Pentland hills, at Sala, 
 Dannemora, and Hallefors in Sweden ; in 
 the Saxon Erze-gebirge, and the Hartz. 
 
 7. Clinkstone ; which see. 
 
 8. Earthy common felspar. This seems 
 to be disintegrated common felspar. 
 
 9. Porcelain earth. See Clay. 
 
 II. Pyra midal felspar. See Scapolite, 
 and Elaolite. 
 
 III. Prismato-pyramidal felspar. See 
 Meionite. 
 
 IV. Rhomboidal felspar. See Nephe- 
 line. 
 
 Chiastolite and sodalite have also been an- 
 nexed to this species by Professor Jameson. * 
 
 * Fermentation. When aqueous com- 
 binations of vegetable or animal matter are 
 exposed to ordinary atmospherical tempera- 
 tures, they speedily undergo spontaneous 
 changes, to which the generic name of fer- 
 mentation has been given. Animal liquids 
 alone, or mixed with vegetables, speedily be- 
 come sour. The act which occasions this 
 alteration is called acetous fermentation, be- 
 cause the product is, generally speaking, ace- 
 tic acid, or vinegar. Put when a moderate- 
 ly strong solution of saccharine matter, or 
 saccharine matter and starch, or sweet juices 
 of fruits, suffer this intestine change, the re- 
 sult is an intoxicating liquid, a beer, or wine ; 
 whence the process is called vinous fermenta- 
 tion. An idterior change to which all moist 
 animal and vegetable matter is liable, accom- 
 panied by the disengagement of a vast quau- 
 
FEIt 
 
 titv of fetid gases, is called the putrefactive 
 fermentation. 
 
 Each of these processes goes on most ra- 
 pidly at a somewhat elevated temperature, 
 such as 80° or 100° F. It is for these rea- 
 sons, that in tropical countries, animal and 
 vegetable substances are so speedily decom- 
 posed. 
 
 As the ultimate constituents of vegetable 
 matter are oxygen, hydrogen, and carbon ; 
 and of animal matter, the same 3 principles 
 ivith azote, we can readily understand that 
 all the products of fermentation must be 
 merely new compounds of these three or four 
 ultimate -constituents. Accordingly, 100 
 parts of real vinegar, or acetic acid, are re- 
 solvable, by MM. Gay Lussac and Thenard’s 
 analysis, into 50.224 carbon 46.911 hy- 
 drogen and oxygen, as they exist in water, 
 + 2.863 oxygen in excess. In like manner, 
 wines are all resolvable into the same ulti- 
 mate components, in proportions somewhat 
 different. The aeriform results of putrefac- 
 tive fermentation are in like manner found 
 to be, hydrogen, carbon, oxygen, and azote, 
 variously combined, and associated with mi- 
 nute quantities of sulphur and phosphorus. 
 The residuary matter consists of the same 
 principles, mixed with the saline and earthy 
 parts of animal bodies. 
 
 Lavoisier was the first philosopher who 
 instituted, on right principles, a series of ex- 
 periments to investigate the phenomena of 
 fermentation, and they were so judiciously 
 contrived, and so accurately conducted, as to 
 give results, comparable to those derived from 
 the more rigid methods of the present day. 
 Since then M. Thenard and M. Gay Lussac 
 have each contributed most important re- 
 searches. By the labours of these three 
 illustrious chemists, those material metamor- 
 phoses, formerly quite mysterious, seem sus- 
 ceptible of a satisfactory explanation. 
 
 1. Vinous fermentation. As sugar is a 
 substance of uniform and determinate com- 
 position, it has been made choice of for de- 
 termining the changes which arise when its 
 solution is fermented into wine or alcohol. 
 Lavoisier justly regarded it as a true vegetable 
 oxide, and stated its constituents to be, 8 hy- 
 drogen, 28 carbon, and 64 oxygen, in 100 
 parts. By two different analyses of Berzelius, 
 we have, 
 
 Hydrogen, 6.802 6.891 
 
 Carbon, 44.115 42.704 
 
 Oxygen, 49.083 50.405 
 
 100.000 100.000 
 
 MM. Gay Lussac and Thenard’s analysis 
 ogives, 
 
 Hydrogen, 
 
 Oxygen, 
 
 Carbon, 
 
 6. 90 
 
 50.63 l 57 - 5;) water ’ 
 42.47 42.47 
 
 100,00 100.00 
 
 It has been said, that sugar requires to be 
 dissolved in at least 4 parts of water, and to 
 he mixed -with some yeast, to cause its fer- 
 mentation to commence. But this is a mis- 
 take. Syrup stronger than the above will 
 ferment in warm weather, without addition. 
 If the temperature he low, the syrup weak, 
 and no yeast added, acetous fermentation 
 alone, will take place. To determine the 
 vinous, therefore, w e must mix certain pro- 
 portions of saccharine matter, water, and 
 yeast, and place them in a proper tempera- 
 ture. 
 
 To observe the chemical changes which 
 occur, we must dissolve 4 or 5 parts of pure 
 sugar in 20 parts of water, put the solution 
 into a matrass, and add 1 part of yeast. 
 Into the mouth of the matrass a glass tube 
 must be luted, which is recurved, so as to 
 dip into the mercury of a pneumatic trough. 
 If the apparatus be now placed in a tempe- 
 rature of from 70° to 80°, we shall speedily 
 observe the syrup to become muddy, and a 
 multitude of air bubbles to form all around 
 the ferment. These unite, and attaching 
 themselves to particles of the yeast, rise 
 along with it to the surface, forming a stra- 
 tum of froth. The yeasty matter will then 
 disengage itself from the air, fall to the bot- 
 tom of the vessel, to reacquire buoyancy a 
 second time by attached air bubbles, and 
 thus in succession. If we operate on 3 or 
 4 ounces of sugar, the fermentation will be 
 very rapid during the first ten or twelve hours ; 
 it will then slacken, and terminate in the 
 course of a few days. At this period the 
 matter being deposited, which disturbed the 
 transparency of the liquor, this will become 
 clear. 
 
 The following changes have now taken 
 place : 1 . The sugar is wholly, and the 
 
 yeast partially, decomposed. 2. A quantity 
 of alcohol and carbonic acid, together nearly 
 in weight to the sugar, is produced. 3. A 
 white matter is formed, composed of hydro- 
 gen, oxygen. and carbon, equivalent to about 
 half the weight of the decomposed ferment. 
 The carbonic acid passes over into the pneu- 
 matic apparatus ; the alcohol may be separat- 
 ed from the vinous liquid by distillation, 
 and the white matter falls down to the bot- 
 tom of the matrass with the remainder of 
 the yeast. 
 
 The quantity of yeast decomposed is very 
 small. 100 parts of sugar require, for com- 
 plete decomposition, only two and a half of 
 that substance, supposed to be in a dry state. 
 It is hence very probable, that the ferment, 
 which has a strong affinity for oxygen, takes 
 a little of it from the saccharine particles, bv 
 a part of its hydrogen and carbon, and thus 
 the equilibrium being broken between the 
 constituent principles of the sugar, these so 
 react on each other, as to be transformed 
 into alcohol and carbonic acid. If we con- 
 
FER 
 
 FER 
 
 sider the composition of alcohol, we shall 
 find no difficulty in tracing the steps of this 
 transformation. If we take 40 of carbon + 
 CO of water, or its elements, as the true con- 
 stituents of sugar, instead of 42.47 -j- 57.53, 
 and convert these weights into volumes, we 
 shall have for the composition of that body, 
 very nearly, by weight, 
 
 1st, 1 volume vapour of carbon, = 0.4 1C 
 1 volume vapour of water, = 0.625, 
 or, 1 volume vapour of carbon, 
 
 1 ditto hydrogen gas, 
 
 % ditto oxygen ; 
 or, multiplying each by 3, 
 
 5 volumes vapour of carbon, 
 
 5 ditto hydrogen, 
 
 ditto oxygen, 
 
 2d, Let us bear in mind, that alcohol is 
 composed of, 
 
 _ i i » (2 vols. vap. of carb. 
 
 1 vol. olefiant gas = 4 ,, , , 1 , 
 
 & (2 vols. hydrogen. 
 
 £• . S 1 vol. hydrogen, 
 
 1 vol. vap. of water = -J T , J & 
 r (4 v °h oxygen. 
 
 3d, 1 vol. carbonic acid = 1 vol. oxygen 
 
 1 vol. vapour of carbon. 
 
 4. Neglecting the minute products which 
 the yeast furnishes, in the act of fermentation, 
 let us regard only the alcohol and carbonic 
 acid. We shall then see, on comparing the 
 composition of sugar to that of alcohol, that 
 to transform sugar into alcohol, we must 
 withdraw from it one volume of vapour of 
 carbon, and one volume of oxygen, which 
 form by their union one volume of carbonic 
 acid gas. Finally, let us reduce the volumes 
 into weights, we shall find, that 100 parts of 
 sugar ought to be converted, during fermen- 
 tation, into 51.55 of alcohol, and 48.45 of 
 carbonic acid. 
 
 Those who are partial to atomical lan- 
 guage will 6ee, that sugar may be repre- 
 sented by 
 
 Atoms. 
 
 3 vol. vap. of carb. = 3 = 2.250 40.00 
 
 3 do. hydrogen, = 3 = 0.575 6.66 
 
 £ do. oxygen, - == 3 = 3. OCX) 53.33 
 
 And alcohol, by 
 
 2 vol. carbon, 
 
 3 do. hydrogen, 
 
 ■J do. oxygen, - 
 
 5.625 99.99 
 
 2 = 1.500 52.16 
 
 3 = 0.375 15.04 
 
 1 = 1.000 34.80 
 
 And carbonic acid, by 
 1 vol. oxygen, - = 
 
 1 do. vap. of carb. = 1 
 
 o 
 
 2.875 100.00 
 
 2.00 72.72 
 
 0.75 27.28 
 
 100.00 
 
 If, therefore, from the sugar group, we 
 take away one atom of carbon, and two of 
 oxygen, to form the carbonic acid group be- 
 low, we leave an atomic assemblage for form- 
 ing alcohol, as in the middle. For this in- 
 teresting dcvclopeinent of the relation be- 
 
 tween the ultimate constituents of sugar on 
 the one hand, and alcohol and carbonic acid 
 on the other, we are indebted to M. Gay 
 Lussac. 
 
 The following beautiful comparison, by 
 the same philosopher, illustrates these meta- 
 morphoses : 
 
 Sulphuric ether is composed of 
 
 Dens, of vapour. 
 
 2 vol. olefiant gas, = 1.9444 ) 0 
 
 1 vol. vap. of wat. =0.6250 ) 
 
 And alcohol is composed cf 
 
 2vol. olefiant gas,= 1.9444 ) _ J _ 9 r ql9 
 
 2 do. vap. of water, = 1.2500 ) * 
 
 Hence to convert alcohol into ether, we 
 have only to withdraw from it one-half of its 
 constituent water. 
 
 Let us now see how far experiment agrees 
 with the theoretic deduction, that 100 parts 
 of sugar, by fermentation, should give birth to 
 51.55 of absolute alcohol, and 48.45 of car- 
 bonic acid. In Lavoisier’s elaborate experi- 
 ment, we find, that 100 parts of sugar afford-, 
 ed, Alcohol, 57.70 
 
 Carbonic acid, 35.34 
 
 95.04 
 
 Unfortunately, this great chemist has omit- 
 ted to state the specific gravity of his alcohol. 
 
 If we assume it to have been 0.8293, as 
 assigned for the density of h ighly rectified al- 
 cohol in the 8th table of the appendix to his 
 Elements, we shall find 100 parts of it to 
 contain, by Lowitz’s table, 87.23 of absolute 
 alcohol, if its temperature bad been 60°. 
 But as 54.5° was the thermometric point 
 indicated in taking sp. gravities, we must 
 reduce the density from 0.8295 to 0.827. 
 We shall then find 100 parts of it, to consist 
 of 88 of absolute alcohol, and 12 of water. 
 Hence, the 57.7 parts obtained by Lavoisier 
 will become 50.776 of absolute alcohol, 
 which is a surprising accordance with the 
 theoretical quantity 51.55. But about four 
 parts of the sugar, or l-25th, had not been 
 decomposed. If we add two parts of alco- 
 hol for this, we would have a small deviation 
 from theory on the other side. There is no 
 reasonable ground for questioning the accu- 
 racy of Lavoisier’s experiments on fermenta- 
 tion. Any person who considers the exces- 
 sive care he has evidently bestowed on them, 
 the finished precision of his apparatus, and 
 the complacency with which he compares 
 “ the substances submitted to fermentation, 
 and the products resulting from that opera- 
 tion, as forming an algebraic equation,” must 
 be convinced that the results are deserving 
 of confidence. Unlike the crude and con- 
 tradictory researches, which modern vanity 
 blazons in our Journals, those of Lavoisier 
 on fermentation, like the coeval inquiries of 
 Cavendish on air, will never become ob- 
 solete. 
 
 M. Thcnard, in operating on a solution of 
 
FER 
 
 FER 
 
 500 parts of sugar, mixed with 60 of yeast, 
 at the temperature of 59°, has obtained such 
 results as abundantly confirm the previous 
 determination of Lavoisier. The following 
 were the products : 
 
 Alcohol of 0.822, - 171.5 
 
 Carbonic acid, - - 94.6 
 
 Nauseous residue, - 12.0 
 
 Residual yeast, - - 40.0 
 
 518.1 
 
 Loss, - 41.9 
 
 separated from it ; and if we suppose with 
 Saussure, that absolute alcohol contains 8.3 
 per cent of water, then the products of sugar 
 decomposed by fermentation, according to 
 Saussure’s (Thenard’s he means) experi- 
 
 ments, are as follows : 
 
 Alcohol, 
 
 - 47.7 
 
 Carbonic acid. 
 
 35.34 
 
 83.04 
 
 Or in 100 parts, 
 
 Alcohol, 
 
 - 57.44 
 
 Carbonic acid, 
 
 42.56 
 
 360.0 
 
 The latter two ingredients may be disre- 
 garded in the calculation, as the weight of 
 the yeast is nearly equivalent to their sum. 
 
 Dividing 171.5 by 5, we have 57.17 for 
 the weight of alcohol of 0.822 from 100 of 
 sugar. In the same way we get 31.53 for 
 the carbonic acid. Now, spirit of wine of 
 0.822 contains 90 per cent of absolute alco- 
 hol. Whence, we find 51.453 for the quan- 
 tity of absolute alcohol by Thenard’s experi- 
 ment ; being a perfect accordance with the 
 theoretical deductions of M. Gay Lussac, 
 made at a subsequent period. 
 
 By M. Lavoisier. By M. Thenard. By theory. 
 From 100 sugar. From 100 do. 
 
 Abs. alco. 50.776 51.453 51.55 
 
 The coincidence of these three results seems 
 perfectly decisive. 
 
 In determining the density of absolute al- 
 cohol, M. Gay Lussac had occasion to ob- 
 serve, that when alcohol is mixed with water, 
 the density of the vapour is exactly the 
 mean between the density of the alcoholic 
 vapour, and that of the aqueous vapour, not- 
 withstanding the affinity which tends to unite 
 them. An important inference flows from 
 this observation. The experiments of M. de 
 Saussure, as corrected by M. Gay Lussac’s 
 theory of volumes, demonstrate, that the ab- 
 solute alcohol which they employed contains 
 no separable portion of water, but what is 
 essential to the existence of the liquid alco- 
 hol. Had any foreign water been present, 
 then the specific gravity of the alcoholic 
 vapour would have been proportionally di- 
 minished ; for the vapour of water is less 
 dense than that of alcohol, in the ratio of 1 
 to more than But since the sp. gravity 
 
 of alcoholic vapour is precisely that which 
 would result from the condensed union, of 
 one volume vapour of carbon, one volume of 
 hydrogen, and half a volume of oxygen, it 
 seems absurd to talk of such alcohol still 
 containing 8.3 per cent of water. 
 
 The writer of a long article on brewing , in 
 the supplement to the 5th edition of the 
 Encyclopaedia Britannica, makes the follow- 
 ing remarks in discussing M. Thenard’s re- 
 searches on fermentation. “ Now, alcohol 
 of the specific gravity 0.822 contains one- 
 tenth of its weight of water, which can be 
 
 100.00 
 
 “ This result approaches so nearly to that 
 of Lavoisier, that there is reason to suspect 
 that the coincidence is more than accidental.” 
 p. 480. 
 
 This insinuation against the integrity of 
 one of the first chemists in France, calls for 
 reprehension. But farther, M. Gay Lussac’s 
 account of the nature of alcohol and its va- 
 pour, was published a considerable time be- 
 fore the particle brewing appeared. Indeed 
 our author copies a considerable part of it, 
 so that the above error is less excusable. 
 
 The ferment or yeast is a substance which 
 separates under the form of flocculi, more or 
 less viscid, from all the juices and infusions 
 which experience the vinous fermentation.. 
 It is commonly procured from the beer ma- 
 nufactories, and is hence called the barm of 
 beer. It may be easily dried, and is actual- 
 ly exposed for sale in Paris under the form 
 of a firm but slightly cohesive paste, of a 
 greyish-white colour. This pasty barm, left 
 to itself in a close vessel, at a temperature 
 of from 55° to 70°, is decomposed, and un- 
 dergoes in some days the putrid fermenta- 
 tion. Placed in contact, at that tempera- 
 ture, with oxygen in a jar inverted over mer- 
 cury, it absorbs this gas in some hours, 
 and there is produced carbonic acid and a 
 little water. Exposed to a gentle heat, it 
 loses more than two-thirds of its weight, 
 becomes dry, hard, and brittle, and may in 
 this state be preserved for an indefinite 
 time. When it is more highly heated, it 
 experiences a complete decomposition, and 
 furnishes all the products which usually re- 
 sult from the distillation of animal substan- 
 ces. 
 
 It is insoluble in water and alcohol. 
 Boiling water speedily deprives it of its 
 power of readily exciting fermentation. — 
 In fact, if we plunge the solid yeast into 
 water for ten or twelve minutes, and place 
 it afterwards in contact with a saccharine 
 solution, this exhibits no symptom of fer- 
 mentation for a long period. By that heat, 
 the ferment does not seem to lose any of its 
 constituents, or to acquire others. Its habi- 
 tudes with acids and alkalis have not been 
 well investigated. From Thenard’s re- 
 
FER 
 
 FIB 
 
 searches, the fermenting principle in yeafct 
 seems to be of a caseous or glutinous nature. 
 
 It is to the gluten that wheat flour owes 
 iti property of making a fermentable dough 
 with water. I his flour paste may indeed 
 be regarded as merely a viscid and elastic 
 tissue of gluten, the interstices of which are 
 tilled with starch, albumen, and sugar. We 
 know that it is from the gluten that the 
 dough derives its property of rising on the 
 admixture of leaven. The leaven acting on 
 the sweet principle of the wheat, gives rise in 
 succession to the vinous and acetous fYrmen- 
 tations, and of consequence to alcohol, ace- 
 tic and carbonic acids. The latter gas tends 
 to fly off, but the gluten resists its disengage- 
 ment, expands like a membrane, forms a 
 multitude of little cavities, which give light- 
 ness and sponginess to the bread. For the 
 want of gluten, the flour of all those grains 
 and roots which consist chiefly of starch are 
 not capable of making raised bread, even 
 with the addition of leaven or yeast. There 
 does not appear to be any peculiar fermenta- 
 tion to which the name panary should be 
 given. * 
 
 When it is required to preserve fermented 
 liquors in the state produced by the first 
 stage of fermentation, it is usual to put 
 them into casks before the vinous process is 
 completely ended ; and in these closed ves- 
 sels a change very slowly continues to be 
 made for many months, and perhaps for 
 some years. 
 
 But if the fermentative process be suffered 
 to proceed in open vessels, more especially 
 if the temperature be raised to 90 degrees, 
 the acetous fermentation comes on. In this, 
 the oxygen of the atmosphere is absorbed ; 
 and the more speedily in proportion as the 
 surfaces of the liquor are often changed by 
 lading it from one vessel to another. The 
 usual method consists in exposing the fer- 
 mented liquor to the air in open casks, the 
 buno-hole of which is covered with a tile to 
 
 O 
 
 prevent the entrance of the rain. By the 
 absorption of oxygen which takes place, the 
 inflammable spirit becomes converted into 
 an acid. If the liquid be then exposed to 
 distillation, pure vinegar comes over instead 
 of ardent spirit. . 
 
 When the spontaneous decomposition is 
 suffered to proceed beyond the acetous pro- 
 cess, the vinegar becomes viscid and foul ; 
 air is emitted with an offensive smell ; vola- 
 tile alkali flies off; an earthy sediment is 
 deposited; and the remaining liquid, if any, 
 is mere water. This is the putrefactive 
 process. 
 
 The fermentation by which certain co- 
 louring matters are separated from vegeta- 
 bles, as in the preparation of woad and indi- 
 go, is carried much farther, approaching the 
 putrefactive stage. 
 
 It is not clearly ascertained what the yeast 
 
 or ferment performs in this operation. It 
 seems probable, that the fermentative process 
 in considerable musses would be carried on 
 progressively from the surface downwards; 
 and would, perhaps, be completed in one 
 part before it had perfectly commenced in 
 another, if the yeast, which is already in a 
 state of fermentation, did not cause the pro- 
 cess to begin in every part at once. See 
 Bread, Distillation, Putrefaction, Al- 
 cohol, Wine, Acid (Acetic), Vegetable 
 Kingdom. 
 
 * Fer roc va nates. See Acid (Ferro- 
 
 prussic). * 
 
 * Ferrocyanic Acid. See Acid (Ferro- 
 prussic).* 
 
 * Ferroprussic Acid, and Ferroprus- 
 siates. See Acid (Ferroprussic).* 
 
 * Ferruretted Chyazic Acid. The same 
 as Ferroprussic.* 
 
 * Fetstein. Elaolite. * 
 
 * Fibrin. A peculiar organic compound 
 found both in vegetables and animals. Vau- 
 quelin discovered it in the juice of the papaw 
 tree. It is a soft solid, of a greasy appear- 
 ance, insoluble in w r ater, which softens in the 
 air, becoming viscid, brown, and semi-trans- 
 parent. On hot coals it melts, throws out 
 greasy drops, crackles, and evolves the smoke 
 and odour of roasting meat. Fibrin is pro- 
 cured, however, in its most characteristic 
 state from animal matter. It exists in chyle, 
 it enters into the composition of blood ; of 
 it, the chief part of muscular flesh is formed ; 
 and hence it may be regarded as the most 
 abundant constituent of the soft solids of 
 animals. 
 
 To obtain it, we may beat blood, as it 
 issues from the veins, with a bundle of 
 twigs. Fibrin soon attaches itself to each 
 stem, under the form of long reddish fila- 
 ments, which become colourless by washing 
 them w T ith cold water. It is solid, white, 
 insipid, without smell, denser than water, 
 and incapable of affecting the hue of litmus 
 or violets. When moist it possesses a species 
 of elasticity ; by desiccation it becomes yel- 
 lowish, hard, and brittle. By distillation we 
 can extract from it much carbonate of am- 
 monia, some acetate, a fetid brown oil, and 
 gaseous products ; while there remains in 
 the retort a very luminous charcoal, very 
 brilliant, difficult of incineration, which leaves 
 after combustion, phosphate of lime, a little 
 phosphate of magnesia, carbonate of lime, 
 and carbonate of soda. 
 
 Cold water has no action on fibrin. Treat- 
 ed with boiling water, it is so changed as to 
 lose the property of softening and dissolving 
 in acetic acid. The liquor filtered from it, 
 yields precipitates with infusion of galls, and 
 the residue is white, dry, hard, and of an 
 agreeable taste. 
 
 When kept for some time in alcohol of 
 O.SIO, it gives rise to an ndipocerous matter, 
 
FIB 
 
 FIL 
 
 having a strong and disagreeable odour. 
 This matter remains dissolved in the alco- 
 hol, and may be precipitated by water. Ether 
 makes it undergo a similar alteration, but 
 more slowly. When digested in weak mu- 
 riatic acid, it evolves a little azote, and a 
 compound is formed, hard, horny, and which 
 washed repeatedly with water, is transformed 
 into another gelatinous compound. This 
 seems to be a neutral muriate, soluble in hot 
 water ; whilst the first is an acid muriate, 
 insoluble even in boiling water. Sulphuric 
 acid, diluted with six times its weight of 
 water, has similar effects. When not too 
 concentrated, nitric acid has a very different 
 action on fibrin, l or example, when its sp. 
 gr. is 1.25, there results from it at first a 
 disengagement of azote, while the fibrin be- 
 comes covered with fat, and the liquid turns 
 yellow. By digestion of 24 hours, the whole 
 fibrin is attacked, and converted into a pulve- 
 rulent mass of a lemon-yellow colour, which 
 seems to be composed of a mixture of fat 
 and fibrin, altered and intimatelv combined 
 w ith the malic and nitric or nitrous acids. 
 In fact, if we put this mass on a filter, and 
 wash it copiously with water, it will part 
 with a portion of its acid, will preserve the 
 property of reddening litmus, and will take 
 an orange hue. On treating it afterwards 
 with boiling alcohol, we dissolve the fatty, 
 matter ; and putting the remainder in con- 
 tact with chalk and water, an efflorescence 
 will be occasioned by the escape of carbonic 
 acid, and malate or nitrate of lime will re- 
 main in solution. 
 
 Concentrated acetic acid renders fibrin 
 soft at ordinary temperatures, and converts it 
 by the aid of beat into a jelly, which is solu- 
 ble in hot water, with the disengagement of 
 a small quantity of azote. This solution is 
 colourless, and possesses little taste. Evapo- 
 rated to dryness, it leaves a transparent resi- 
 due, which reddens litmus paper, and which 
 cannot he dissolved even in boilin water, 
 but by the medium of more acetic acid. 
 Sulphuric, nitric, and muriatic acids, preci- 
 pitate the animal matter, and form acid com- 
 binations. Potash, soda, ammonia, effect like- 
 wise the precipitation of this matter, provided 
 we do not use too great an excess of alkali ; for 
 then the precipitated matter would be redis- 
 solved. Aqueous potash and soda gradually 
 dissolve fibrin in the cold, without occasion- 
 ing any perceptible change in its nature ; 
 but with heat they decompose it, giving 
 birth to a quantity of ammoniacal gas, and 
 other usual animal products. Fibrin does 
 not putrify speedily when kept in water. It 
 shrinks on exposure to a considerable beat, 
 and emits the smell of burning horn. It is 
 composed, according to the analysis of MM. 
 Gay Lussac and Thenard, of 
 Carbon, 53.360 
 
 Azote, J 9.934 
 
 Oxygen, 1 9.685 \ 22.14 water 
 
 Hydrogen, 7.021 £ 4.56 hydrogen.* 
 
 * Fibrolite. Colours white and grey ; 
 crystallized in rhomboidal prisms, the angles 
 of whose planes are 80° and 100°. It is 
 glistening internally. Principal fracture 
 uneven. Harder than quartz. Sp. gr. 5.214. 
 Its constituents are alumina 58.25, silica 38, 
 iron and loss 5.75. It is found in the Car- 
 natic. — Jamesun .* 
 
 * Figurestone. See Bile ste-in. * 
 
 Filtration. An operation, by means of 
 
 which a fluid is mechanically separated from 
 consistent particles merely mixed with it. 
 It does not differ from straining. 
 
 An apparatus fitted up for this purpose is 
 called a filter. The form of this is various, 
 according to the intention of the operator. 
 A piece of tow, or wool, or cotton, stuffed 
 into the pipe of a funnel, will prevent the 
 passage of grosser particles, and by that 
 means render the fluid clearer which comes 
 through. Spunge is still more effectual. A 
 strip of linen rag wetted and hung over the 
 side of a vessel containing a fluid, in such a 
 manner as that one end of the rag may be 
 immersed in the fluid, and the other end 
 may remain without, below the surface, will 
 act as a syphon, and carry over the clearer 
 portion. Linen or, woollen stuffs may either 
 be fastened over the mouths of proper ves- 
 sels, or fixed to a frame, like a sieve, for the 
 purpose of filtering. All these are more 
 commonly used by cooks and apothecaries 
 than by philosophical chemists, who, for the 
 most part, use the paper called cap paper, 
 made up without size. 
 
 As the filtration of considerable quantities 
 of fluid could not be effected at once with- 
 out breaking the filter of paper, it is found 
 requisite to use a linen cloth, upon which 
 the paper is applied and supported. 
 
 Precipitates and ether pulverulent mat- 
 ters are collected more speedily by filtration 
 than by subsidence. Put there are many 
 chemists who disclaim the use of this me- 
 thod, and avail themselves of the latter only, 
 which is certainly more accurate, and liable 
 to no objection, where the powders are such 
 as will admit of edulcoration and drying in 
 the open air. 
 
 Some fluids, as turbid water, may be pu- 
 rified by filtering through sand. A large 
 earthen funnel, or stone bottle with the bot- 
 tom beaten out, may have its neck loosely 
 stopped with small stones, over which smaller 
 may be placed, supporting layers of gravel 
 increasing in fineness, and lastly covered to 
 the depth of a few inches with fine sand, all 
 thoroughly cleansed by washing. This ap- 
 paratus is superior to a filtering stone, as it 
 will cleanse water in large quantities, and 
 may readily be renewed when the passage is 
 obstructed, by taking out and washing the 
 upper stratum of sand. 
 
FLI 
 
 FLU 
 
 A filter for corrosive liquors may be con- 
 structed on the same principles of broken 
 and pounded glass. 
 
 k utE. See Caloric and Combustion. 
 
 * k ire- damp. See Combustion and Car- 
 
 BU RETTED IIyDROGEN.* 
 
 * Fish- scales are composed of alternate 
 layers ot membrane and phosphate of liine. * 
 
 * Fixed Air. Carbonic acid gas.* 
 
 Fixity. The property by which bodies 
 
 resist the action of heat, so as not to rise in 
 vapour. 
 
 * Flake-white. Oxide of bismuth.* 
 
 Flame. See Combustion. 
 
 * Flesh. The muscles of animals. They 
 consist chiefly of fibrin, with albumen, gela- 
 tin, extractive, phosphate of soda, phosphate 
 of ammonia, phosphate and carbonate of 
 lime, and sulphate of potash. See Muscle.* 
 
 * Flint. Colour generally grey, with 
 occasionally zoned and striped delineations. 
 Massive, in rolled pieces, tuberose and per- 
 forated. It rarely occurs in supposititious, 
 hollow, pyramidal or prismatic crystals. It 
 occurs often in extraneous shapes, as echi- 
 nites, coralites, madreporites, fungites, be- 
 lemnites, mytilites, &c. ; sometimes in lamel- 
 lar concretions. Internal lustre glimmering. 
 Fracture conchoidal. Fragments sharp- 
 edged. Translucent. Harder than quartz. 
 Easily frangible. Sp. gr. 2.59. Infusible 
 without addition, but whitens and becomes 
 opaque. Its constituents are 98 silica, 0.50 
 lime, 0.25 alumina, 0.25 oxide of iron, 1.0 
 loss. When two pieces of flint are rubbed 
 together in the dark, they phosphoresce, and 
 emit a peculiar smell. 
 
 It occurs in primitive, transition, secon- 
 dary, and alluvial mountains. In the first 
 two, in metalliferous and agate veins. In 
 secondary countries it is found in pudding- 
 stone, limestone, chalk, and amygdaloid. 
 In chalk it occurs in great abundance in 
 beds. These seem to have been both formed 
 at the same time. Werner, however, is of 
 opinion, that the tuberose and many other 
 forms, have been produced by infiltration. 
 In Scotland, it occurs imbedded in secon- 
 dary limestone in the island of Mull, and 
 near Kirkaldy in Fifeshire. In England, it 
 abounds in alluvial districts in the form of 
 gravel, or is imbedded in chalk. In Ire- 
 land it occurs in considerable quantities in 
 secondary limestone. It is found in most 
 parts of the world. Its principal use is for 
 gun flints, the mechanical operations of 
 which manufacture, are fully detailed by 
 Brogniart. The best flint for this purpose, 
 is the yellowish -grey. It is an ingredient in 
 pottery, and chemists use it for mortars.* 
 
 * Flinty-slate. Of this mineral there 
 are two kinds, common flinty-slate, and Ly- 
 dian stone. 
 
 1. Common . Colour ash-grey, with other 
 colours, in flamed, striped, and spotted deli- 
 
 neations. It is often traversed by quartz 
 veins. Massive, and in lamellar concretions. 
 Internally it is faintly glimmering. Frac- 
 ture in the great slaty, in the small splintery, 
 i ranslucent. Hard. Uncommonly diffi- 
 cultly frangible. Sp. gr. 2.63. It occurs 
 in beds, in clay-slate and grey-wacke ; and 
 in roundish and angular masses in sandstone. 
 It is found in different parts of the great 
 tract of clay- slate and grey-wacke which ex- 
 tends from St Abb’s-head to Portpatrick; 
 also in the Pentland hills near Edinburgh. 
 
 2. Lydian stone. Colour greyish-black, 
 which passes into velvet- black. It occurs 
 massive, and rolled in pieces with glistening 
 surfaces. Internally it is glimmering. Frac- 
 ture even. Opaque. Less hard than flint. 
 Difficultly frangible. Sp. gr. 2.6. It oc- 
 curs very frequently along with common 
 flinty-slate in beds in clay-slate. It is found 
 near Prague and Carlsbad in Bohemia, in 
 Saxony, the Hartz, and at the Moorfoot and 
 Pentland hills near Edinburgh. It is some- 
 times used as a touchstone for ascertaining 
 the purity of gold and silver. See Assay.* 
 
 * Floatstone. A sub-species of the in- 
 divisible quartz of Mohs. Spongiform quartz 
 of Jameson. Colour white of various shades. 
 In porous, massive, and tuberose forms. 
 Internally it is dull. Fracture coarse earthy. 
 Feebly translucent on the edges. Soft, but 
 its minute particles are as hard as quartz. 
 Bather brittle. Easily frangible. Peels 
 meagre and rough, and emits a grating 
 noise, when the finger is drawn across it. 
 Sp. gr. 0.49. Its constituents are silica 98, 
 carbonate of lime 2. — Vaug. It occurs en- 
 crusting flint, or in imbedded masses in a 
 secondary limestone at St Ouen near Paris. 
 — Jameson.* 
 
 Flour. The powder of the gramineous 
 seeds. Its use as food is well known. See 
 Bread. 
 
 FYowers. A general appellation used by 
 the elder chemists, to denote all such bodies 
 as have received a pulverulent form by sub- 
 limation. 
 
 Flowers of Vegetables. Dr Lewis in 
 his notes on Neumann’s Chemistry, gives a 
 cursory account of many experiments, made 
 with a view to ascertain how far the colour of 
 vegetable flowers might prove of use to the 
 dyer. Ife found very few capable of being 
 applied to valuable purposes. 
 
 * Fluates. Compounds of the salifiable 
 bases with fluoric acid.* 
 
 Fluidity. The state of bodies when 
 their parts are very readily moveable in all 
 directions with respect to each other. See 
 Caloric. 
 
 * Fluouoratfs. Compounds of fluoboric 
 acid with the salifiable bases.* 
 
 * Fluor. Octohedral fluor of Jameson. 
 It is divided into three sub-species, compact 
 fluor, foliated fluor, and earthy fluor. 
 
FLU 
 
 FOR 
 
 1. Compact. Colours, greenish- grey and 
 
 greenish-white. Massive. Dull or feebly 
 glimmering. Fracture even. Fragments 
 
 sharp-edged. Translucent. Flarder than 
 
 calcareous spar, but not so hard as apatite. 
 Brittle, and easily frangible. Sp. gr. o. 17. 
 It is found in veins, associated with fiuor 
 spar, at Stolberg in the Hartz. 
 
 2. Foliated. Colours, white, yellow, green, 
 and blue. Green cubes appear with white 
 angles. Massive, disseminated, and in dis- 
 tinct concretions. Crystallized in cubes, per- 
 fect or variously truncated and bevelled ; in 
 the rhomboidal dodecahedron, and the octo- 
 hedron, or double four-sided pyramid. I he 
 crystals are generally placed on one another, 
 and form druses; but are seldom single. 
 Surface smooth and splendent, or drusy and 
 rough. Internal lustre, specular-splendent, 
 or shining vitreous. Cleavage, fourfold 
 equiangular, parallel with the planes of an 
 octohedron. Fragments octohedral or tetra- 
 hedral. Translucent to transparent. Single 
 refraction. Harder than calcareous spar, 
 but not so hard as apatite. Brittle, and 
 easily frangible. Sp.gr. 3. Id. Before the 
 blow-pipe it generally decrepitates, gradually 
 loses its colour and transparency, and melts 
 without addition into a greyish- white glass. 
 When two fragments are rubbed together, 
 they become luminous in the dark. When 
 gently heated, it phosphoresces with a 
 blue and green light. By ignition it loses 
 its phosphorescent property. The violet blue 
 variety from Nertschinsky, called chlorophane , 
 when placed on glowing coals, does not de- 
 crepitate, but soon throws out a green light. 
 Sulphuric acid evolves from pulverized fiuor 
 spar acid fumes which corrode glass. Its 
 constituents, by Berzelius, are 72. 1 lime, 
 and 27.9 fluoric acid, It occurs principally 
 in veins that traverse primitive, transition, 
 and sometimes secondary rocks. It has 
 been found only in four places in Scotland, 
 near Monaltree in Aberdeenshire, in gneiss 
 in Sunderland, in secondary porphyry near 
 Gourock in Renfrewshire, and in the island 
 of Papastour, one of the Shetlands. It oc- 
 curs much more abundantly in England, be- 
 ing found in all the galena veins that tra- 
 verse the coal formation in Cumberland and 
 Durham ; in secondary or fioetz limestone in 
 Derbyshire ; and it is the most common 
 veinstone in the copper, tin, and lead veins, 
 that traverse granite, clay-slate, &c. in Corn- 
 wall and Devonshire. It is also frequent on 
 the Continent of Europe. It is cut into 
 ornamental forms. It has also been used as 
 a f i for ores ; whence its name Jiuor. — Ja- 
 meson. 
 
 3. Earthy jiuor. Colour, greyish-white 
 and violet-blue, sometimes very deep, it 
 occurs generally in crusts investing some 
 other mineral. Dull. Earthy. Friable. 
 
 Its constituents are the same as the preced- 
 ing. It occurs in veins along with fiuor 
 spar at Beeralstone in Devonshire; in Cum- 
 berland, in Saxony, and Norway.* 
 
 * Fluoric Acid. See Acid (Fluoric. )* 
 
 * Fluorine. The imaginary radical of 
 the above acid.* 
 
 * Fluosilicates. See Acid (Fluosili- 
 cic). * 
 
 Flux. A general term made use of to 
 denote any substance or mixture added to 
 assist the fusion of minerals. In the large 
 way, limestone and fusible spar are used as 
 fluxes. The fluxes made use of in assays, or 
 philosophical experiments, consist usually of 
 alkalis, which render the earthy' mixtures 
 fusible, by converting them into glass; or 
 else glass itself in powder. 
 
 Alkaline fluxes are either the crude flux, 
 the white flux, or the black flux. Crude 
 flux is a mixture of nitre and tartar, which 
 is put into the crucible with the .mineral 
 intended to be fused. The detonation of 
 the nitre with the inflammable matter of the 
 tartar, is of service in some operations ; 
 though generally it is attended with incon- 
 venience on account of the swelling of the 
 materials, which may throw them out of 
 the vessel, if proper care be not taken either 
 to throw in only a little of the mixture at a 
 time, or to provide a large vessel. 
 
 White flux is formed by projecting equal 
 parts of a mixture of nitre and tartar, by 
 moderate portions at a time, into an ignited 
 crucible. In the detonation which ensues, 
 the nitric acid is decomposed, and Hies off 
 with the tartaric acid, and the remainder 
 consists cf the potash in a state of consider- 
 able purity. This has been called fixed 
 nitre. 
 
 Black flux differs from the preceding, in 
 the proportion of its ingredients. In this 
 the weight of the tartar is double that of the 
 nitre ; on which account the combustion is 
 incomplete, and a considerable portion of the 
 tartaric acid is decomposed by the mere heat, 
 and leaves a quantity of coal behind, on 
 which the black colour depends. It is used 
 where metallic ores arc intended to be re- 
 duced, and effects this purpose, by combin- 
 ing with the oxygen of the oxide. 
 
 The advantage of M. Morvcau’s reducing 
 flux, seems to depend on its containing 
 no excess of alkali. It is made of eight 
 parts of pulverized glass, one of calcined bo- 
 rax, and half a part of powder of charcoal. 
 Care must be taken to use a glass which 
 contains no lead. 1 he white glasses contain 
 in general a large proportion, and the green 
 bottle glasses are not perhaps entirely free 
 from it. 
 
 Forge Furnace. The forge furnace 
 consists of a hearth, upon which a fire may 
 be made, and urged by the action of a large 
 
FUL 
 
 FUL 
 
 pair of double bellows, tbo nozzle of which 
 is inserted through a wall or parapet con- 
 structed for that purpose. 
 
 Black-lead pots, or small furnaces of every 
 desired form, may be placed, as occasions 
 require, upon the hearth ; and the tube of 
 the bellows being inserted into a hole in 
 the bottom of the furnace, it becomes easy 
 to urge the heat to almost any degree re- 
 quired. 
 
 * Formations. See Geology.* 
 
 * Formiates. Compounds of formic acid 
 with the saliliable bases.* 
 
 * Freezing. See Caloric, and Con- 
 gelation.* 
 
 * Fossil Copal, or Highgate resin. Its 
 colour is pale muddy yellowish-brown. It 
 occurs in irregular roundish pieces. Lus- 
 tre resinous. Semi-transparent. Brittle. 
 Yields easily to the knife. Sp. gr. 1.046. 
 When heated, it gives out a resinous aroma- 
 tic odour, melts into a limpid fluid, takes 
 lire at a lighted candle, and burns entirely 
 away before the blow-pipe. Insoluble in 
 potash ley. Found in the bed of blue clay 
 at Hischgate near London. Allan's Minera - 
 
 O O 
 
 logy.* 
 
 Frankincense. See Olibanum. 
 
 French Berries. The fruit of the H ham- 
 mis infeclorius, called by the French graines 
 d' Avignon. They give a pretty good yellow 
 colour, but void of permanency. When 
 used for dyeing, the cloth is prepared in the 
 same manner as for weld. 
 
 Friesland Green. Ammoniaco-muriate 
 of copper, the same with Brunswick green. 
 See Copper. 
 
 Fritt. The materials of glass are first 
 mixed together, and then exposed to calcina- 
 tion by a degree of heat not sufficient to melt 
 them. The mass is then called fritt. 
 
 Fruits of Vegetables. Sap Green is 
 prepared from the berries of buckthorn, and 
 Annotto is obtained from the pellicles of the 
 seeds of an American tree. See the words. 
 
 Fuliginous. Vapours which possess the 
 property of smoke ; namely, opacity, and the 
 disposition to apply themselves to surround- 
 ing bodies in the form of a dark coloured 
 
 O 
 
 powder. 
 
 * Fuller’s Earth. Colour greenish- 
 white, and other shades of green. Massive. 
 Bull. Fracture uneven. Opaque. Shin- 
 ing and resinous in the streak. A ery soft. 
 Sectile. Scarcely adheres to the tongue. 
 Feels greasy. Sp. gr. 1.7 to 2.2. It falls 
 into a powder with water, without the crack- 
 ling noise which accompanies the disintegra- 
 tion of bole. It melts into a brown spongy 
 scoria before the blow-pipe. Its constituents 
 are 53 silica, 10 alumina, 1.25 magnesia, 
 0.50 lime, 0.10 muriate of soda, trace of 
 potash, oxide of iron 9.75, water 24. — Klap- 
 roth. Bergman found 24 alumina, and only 
 0.7 oxide of iron. In England it occurs in 
 
 beds, sometimes above, sometimes below, the 
 chalk formation ; at Rosswcin in Upper Sax- 
 ony, under strata of greenstone slate ; and in 
 different places in Germany it is found im- 
 mediately under the soil. The best is found 
 in Buckinghamshire and Surry. When 
 good, it has a greenish- white, or greenish- 
 grey colour, falls into powder in water, ap- 
 pears to melt on the tongue like butter, 
 communicates a milky hue to water, and de- 
 posits very little sand when mixed with boil- 
 ing w r ater. The remarkable detersive pro- 
 perty on woollen cloth, depends on the alu- 
 mina, which should be at least one-fifth of the 
 whole, but not much more than one-fourth, 
 lest it become too tenacious. — Jameson .* 
 
 Fulminating and Fulmination. In a 
 variety of chemical combinations, it happens, 
 that one or more of the principles assume 
 the elastic state with such rapidity, that the 
 stroke against the displaced air produces a 
 loud noise. This is called fulmination, or 
 much more commonly detonation. 
 
 Fulminating gold, and fulminating pow- 
 der, are the most common substances of this 
 kind, except gunpowder. For the latter of 
 these, see the article Gunpowder. The ful- 
 minating powder is made by triturating in a 
 warm mortar, three parts by weight of nitre, 
 two of carbonate of potash, and one of 
 flowers of sulphur. Its effects, when fused 
 in a ladle, and then set on fire, are very 
 great. The whole of the melted fluid ex- 
 plodes with an intolerable noise, and the 
 ladle is commonly disfigured, as if it had re- 
 ceived a strong blow downwards. 
 
 If a solution of gold be precipitated by 
 ammonia, the product will be fulminating 
 gold. Less than a grain of this, held over 
 the flame of a candle, explodes with a very 
 sharp and loud noise. This precipitate, se- 
 parated by filtration, and washed, must be 
 dried without heat, as it is liable to explode 
 with no great increase of temperature ; and 
 it must not be put into a bottle closed with 
 a glass stopple, as the friction of this would 
 expose the operator to the same danger. 
 
 Fulminating silver may be made by pre- 
 cipitating a solution of nitrate of silver by 
 lime-water, drying the precipitate by expo- 
 sure to the air for two or three days, and pour- 
 ing on it liquid ammonia. When it is thus 
 converted into a black powder, the liquid 
 must be poured off, and the powder left to 
 dry in the air. It detonates with the gentlest 
 heat, or even with the slightest friction, so 
 that it must not be removed from the vessel 
 in which it is made. If a drop of water fall 
 upon it, the percussion will cause it to ex- 
 plode. It w r as discovered by Berthollct. 
 
 Brugnatelli made a fulminating silver by 
 powdering a hundred grains of nitrate of 
 silver, putting the powder into a beer glass, 
 and pouring on it, first an ounce of alcohol, 
 then as much concentrated nitrous acid. 
 
FUM 
 
 FUS 
 
 The mixture grows hot, boils, and an ether 
 is visibly formed, that changes into gas. Fy 
 degrees the liquor becomes milky and opaque, 
 and is filled with small white clouds. When 
 all the grey powder has taken this form, and 
 the liquor lias acquired a consistency, distill- 
 ed water must be added immediately to sus- 
 pend the ebullition, and prevent the matter 
 from being redissolved, and becoming a 
 mere solution of silver. Ihe white pre- 
 cipitate is then to be collected on a filter, 
 and dried. The force of this powder great- 
 ly exceeds that of fulminating mercury. It 
 detonates in a tremendous manner, on being 
 scarcely touched with a glass tube, the ex- 
 tremity of which has been dipped in con- 
 centrated sulphuric acid. A single grain, 
 placed on a lighted coal, makes a deafening 
 report The same thing happens, if it be 
 placed on a bit of paper, on an electric pile, 
 and a spark drawn from it. 
 
 Fulminating mercury was discovered by 
 Mr Howard. A hundred grains are to be 
 dissolved with heat in an ounce and half by 
 measure of nitric acid. The solution, when 
 cold, is to be poured on two ounce measures 
 of alcohol, and heat applied till an effer- 
 vescence is excited. As soon as the preci- 
 pitate is thrown down, it must be collected 
 on a filter, that the acid may not react on it; 
 washed, and dried by a very gentle heat. 
 It detonates with a very little heat or fric- 
 tion. 
 
 Three parts of chlorate of potash, and one 
 of sulphur, triturated in a metal mortar, 
 cause numerous successive detonations, like 
 the cracks of a whip, the reports of a pistol, 
 or the fire of musketry, according to the ra- 
 pidity and force of the pressure employed. 
 A few grains, struck with a hammer on an 
 anvil, explode with a noise like that of a 
 musket, and torrents of purple light appear 
 round it. Thrown into concentrated sul- 
 phuric acid, it takes fire, and burns with a 
 white flame, but without noise. 
 
 Six parts of the chlorate, one of sulphur, 
 and one of charcoal, detonate by the same 
 means, but more strongly, and with a redder 
 flame. 
 
 Sugar, gum, or charcoal mixed with the 
 chlorate, and fixed or volatile oils, alcohol, 
 or ether, made into a paste with it, detonate 
 very strongly by the stroke, but not by tri- 
 turation. Some of them take fire, but slowly 
 and by degrees, in the sulphuric acid. 
 
 All these mixtures, that detonate by the 
 stroke, explode much more loudly if previ- 
 ously wrapped up in double paper. 
 
 * Fulminations of the most violent kind 
 require the agency of azote or nitrogen ; as 
 we see not only in its compounds with the 
 oxides of gold, silver, and platina ; but still 
 more remarkably in its chloride and iodide. 
 See Nitrogen.* 
 
 1'uming Liquor. Th® fuming liquors of 
 
 Foyle and Libavius have been long known. 
 To prepare that of Foyle, which is a hidro- 
 guretted sulphuret of ammonia, three parts 
 of lime fallen to powder in the air, one of 
 muriate of ammonia, and one of flowers of 
 sulphur, are to be mixed in a mortar, and dis- 
 tilled with a gentle heat. The yellow liquor, 
 that first comes over, emits fetid fumes. It 
 is followed by a deeper coloured fluid, that 
 is not fuming. 
 
 The fuming liquor of Libavius is made by 
 amalgamating tin with half its w'eight of 
 mercury, triturating this amalgam with an 
 equal weight of corrosive muriate of mer- 
 cury, and distilling by a gentle heat. A 
 colourless fluid at first passes over : after 
 
 this, a thick vapour is thrown out at one 
 single jet with a sort of explosion, which 
 condenses into a transparent liquor, that 
 emits copious, white, heavy, acrid fumes on 
 exposure to the air. In a closely stopped 
 bottle, no fumes from it are perceptible; 
 but needle-shaped crystals form against the 
 top of the bottle, so as frequently to close the 
 aperture. 
 
 Cadet’s fuming liquor is prepared by dis- 
 tilling equal parts of acetate of potash and 
 arsenious acid, and receiving the product in- 
 to glass bodies, kept cool by a mixture of 
 ice and salt. The liquor produced, emits a 
 very dense, heavy, fetid, noxious vapour, and 
 inflames spontaneously in the open air. 
 
 * Fungates. The saline compounds of a 
 peculiar acid, which M. Braconnot has lately 
 extracted from mushrooms.* 
 
 * Fungin. The fleshy part of mushrooms, 
 deprived by alcohol and w ater of every thing 
 soluble. It seems to be a modification of 
 woody fibre.* 
 
 Furnace. See Laboratory. 
 
 Fusibility. That property by which bodies 
 assume the fluid state. 
 
 Some chemists have asserted that fusion is 
 simply a solution in caloric ; but this opinion 
 includes too many yet undecided questions, 
 to be hastily adopted. 
 
 Fusion. The act of fusing. Also the 
 state of a fused body. 
 
 Fustet. The wood of the rhus colinus , 
 or Venus’s sumach, yields a fine orange co- 
 lour, but not at all durable. 
 
 Fustic, or Yellow Wood. This wmod, 
 the viorus tinctoria , is a native of the West 
 Indies. It affords much yellow colouring 
 matter, which is very permanent. 
 
 The yellow given by fustic without any 
 mordant is dull, and brownish, but stands 
 well. The mordants employed with weld 
 act on it in a similar manner, and by their 
 means the colour is rendered more bright 
 and fixed. Ihe difference between them 
 is, that the yellow of fustic inclines more 
 to orange than that of weld ; and, as it 
 abounds more in colouring matter, a less 
 quantity will suffice. 
 
GAL 
 
 GAL 
 
 * ABBRONIT. Scapolite.* 
 
 VJy * Gadolinite. Prismatic gadolinite. 
 — Mobs. 
 
 Its colours are velvet-black, and black of 
 various shades. Massive and disseminated. 
 Rarely crystallized. Its primitive figureseems 
 to be an oblique four-sided prism, in which the 
 obtuse angle is nearly 110°. This prism 
 sometimes occurs with six lateral planes. 
 Lustre resinous inclining to vitreous. Frac- 
 ture conchoidal. Very faintly translucent 
 on the thinnest edges, and then it appears 
 blackish-green. Harder than felspar, but 
 softer than quartz. Streak greenish-grey. 
 Brittle; difficultly frangible. When pure it 
 does not affect the magnet. Sp. gr. 4.0 to 
 4.2. It intumesces very much before the 
 blow-pipe, and at length melts into an im- 
 perfect slag, which is magnetical. It loses 
 its colour in nitric acid, and gelatinizes. Its 
 constituents are 25.8 silica, 45 yttria, 16.69 
 oxide of cerium, 10.26 oxide of iron, 0.60 
 volatile matter. — Berzelius. It occurs along 
 with yttrotantalite at Ytterby in Sweden, in 
 beds of a coarse granular red felspar, which 
 are situated in mica slate ; at Finbo, near 
 Fahlun also in Sweden, in a coarse granular 
 granite, along with pyrophysalite and tin- 
 stone. — Jameson. * 
 
 * Gahnite. Automalite or octohedral 
 corundum.* 
 
 * Gallitzinite. Rutile. An ore of ti- 
 tanium.* 
 
 Galbanum exudes from the bubon galba- 
 num. This juice comes over in masses, com- 
 posed of white, yellowish, brownish-yellow, 
 and brown tears, unctuous to the touch, 
 softening betwixt the fingers; of a -bitterish, 
 somewhat acrid, disagreeable taste, and a 
 very strong smell ; generally full of bits of 
 stalks, leaves, seeds, and other foreign mat- 
 ters. 
 
 Galbanum contains more of a resinous 
 than gummy matter: one pound yields with 
 alcohol upward of nine ounces and a half of 
 resinous extract; but the gummy extract ob- 
 tained by water from the same quantity, 
 amounts only to about three ounces. The 
 resin is hard, brittle, insipid, and inodorous: 
 the gummy extract has somewhat of a nauseous 
 relish, but could not be distinguished to be a 
 preparation of galbanum. The whole smell, 
 flavour, and specific taste of this juice, reside 
 in an essential oil, which arises in distillation 
 both with water and spirit, and gives a strong 
 impregnation to both : from a pound of 
 galbanum are obtained, by distillation with 
 water, six drachms of actual oil, besides what 
 is retained by the water. In this respect 
 galbanum agrees with asafuetida, and differs 
 from ammoniacum. 
 
 Galena. The black ore of lead. 
 
 Gall of Animals. See Bile. 
 
 Gall-stones. Calculous concretions are 
 not unfrequently formed in the gall bladder, 
 and sometimes occasion great pain in their 
 passage through the ducts into the duode- 
 num, before they are evacuated. Of these 
 stones there are four different kinds. 
 
 1. The first has a white colour, and when 
 broken, presents crystalline plates, or striae, 
 brilliant and wdiite like mica, and having a 
 soft greasy feel. Sometimes its colour is 
 yellow or greenish ; and it has constantly a 
 nucleus of inspissated bile. Its sp. gravity 
 is inferior to that of water : Gren found the 
 specific gravity of one 0.803. When ex- 
 posed to a heat considerably greater than 
 that of boiling water, this crystallized cal- 
 culus softens and melts, and crystallizes 
 again when the temperature is lowered. It 
 is altogether insoluble in water ; but hot 
 alcohol dissolves it with facility. Alcohol, 
 of the temperature of 167°, dissolves one- 
 twentieth of its weight of this substance ; but 
 alcohol, at the temperature of 60°, scarcely 
 dissolves any of it. As the alcohol cools, the 
 matter is deposited in brilliant plates, resem- 
 bling talc or boracic acid. It is soluble in 
 oil of turpentine. When melted, it has the 
 appearance of oil, and exhales the smell of 
 melted w r ax ; when suddenly heated, it evapo- 
 rates altogether in a thick smoke. It is so- 
 luble in pure alkalis, and the solution has all 
 the properties of a soap. Nitric acid also 
 dissolves it ; but it is precipitated unaltered 
 by water. 
 
 This matter, which is evidently the same 
 with the crystals Cadet obtained from bile, 
 and which he considered as analogous to 
 sugar of milk, has a strong resemblance to 
 spermaceti. Like that substance, it is ot an 
 oily nature, and inflammable; but it differs 
 from it in a variety of particulars. Since it 
 is contained in bile, it is not difficult to see 
 how it may crystallize in the gall-bladder if 
 it happen to be more abundant than usual ; 
 and the consequence must be a gall-stone of 
 this species. Fourcroy found a quantity of 
 the same substance in the dried human liver. 
 He called it Adipocere. 
 
 2. The second species of biliary calculus 
 is of a round or polygonal shape, often ot a 
 grey colour externally, and brown within. 
 It is formed of concentric layers ot a matter 
 which seems to be inspissated bile ; and 
 there is usually a nucleus ot the white crys- 
 talline matter at the centre. For the most 
 part, there are many of this species ot calcu- 
 lus in the gall-bladder together : indeed it is 
 frequently filled with them. The calculi be- 
 longing to this species are often light and 
 
GAL 
 
 GAL 
 
 friable, and of a brownish-red colour. The 
 gall-stones of oxen used by painters, belong 
 to this species. These are also adipocere. 
 
 3. The third species of calculi are most 
 numerous of all. Their colour is often deep 
 brown or green ; and when broken, a num- 
 ber of crystals of the substance resembling 
 spermaceti are observable, mixed with inspis- 
 sated bile. The calculi belonging to these 
 three species are soluble in alkalis, in soap 
 ley, in alcohol, and in oils. 
 
 4. Concerning the fourth species of gall- 
 stone, very little is known witli accuracy. 
 Dr Saunders tells us, that he has met with 
 some gall-stone3 insoluble both in alcohol 
 and oil of turpentine; some of which do 
 not flame, but become red, and consume to 
 ashes like charcoal. Haller quotes several 
 examples of similar calculi. Gall-stones of- 
 ten occur in the inferior animals, particu- 
 larly in cows and hogs ; but the biliary con- 
 cretions of these animals have not hitherto 
 been examined with much attention. 
 
 Soaps have been proposed as solvents for 
 these calculi. The academy of Dijon has 
 published the success of a mixture of essence 
 of turpentine and ether. 
 
 Galls. These are the protuberances pro- 
 duced by the puncture of an insect on plants 
 and trees of different kinds. Some of them 
 are hard, and termed nut-galls ; others are 
 soft and spongy, and called berry-galls, or 
 apple-galls. The best are the nut-galls of 
 the oak, and those brought from Aleppo are 
 preferred. These are not smooth on the 
 surface, but tubercular, small, and heavy ; 
 and should have a bluish or blackish tinge. 
 
 Deyeux investigated the properties of galls 
 with considerable care ; and more lately Sir 
 II. Davy has examined the same subject. 
 The strongest infusion Sir H. Davy could 
 obtain at 56° F. by repeated infusion of dis- 
 tilled water, on the best Aleppo galls, broken 
 into small pieces, was of the specific gravity 
 of 1.068. Four hundred grains of this in- 
 fusion, evaporated at a heat below 200°, left 
 53 of solid matter, which consisted of about 
 0.9 tannin, and 0. 1 gallic acid, united to a 
 portion of extractive matter. One hundred 
 grains of the solid matter left, by incinera- 
 tion, nearly 4j, which were chiefly calcareous 
 matter, mixed w ith a small portion of fixed 
 alkali. 
 
 From 500 grains of Aleppo galls Sir II. 
 Davy -obtained, by infusion as above, 185 
 grains of solid matter, which on analysis ap- 
 peared to consist of tannin 130; mucilage, 
 and matter rendered insoluble by evapora- 
 tion, 12; gallic acid, with a little extractive 
 matter, 31 ; remainder, calcareous earth and 
 saline matter, 12. 
 
 I he use of galls in dyeing is very exten- 
 sive, and they are one of the principal' in- 
 gredients in making ink. Powdered galls 
 made into an ointment with hog’s lard arc 
 
 a very efficacious application in piles. They 
 are sometimes given internally as an astrin- 
 gent ; and in the intermittents, where the 
 bark has failed. The tubercles, or knots, on 
 the roots of young oaks, are said to possess 
 the same properties as the nut-galls, and to 
 be produced in a similar manner. 
 
 For their acid, see Acid (Gallic). 
 
 * Galvanism. The following article is 
 chiefly extracted from a paper, which was 
 read by me at the Glasgow Literary Society, 
 December 10. 1818, and published in the 
 Journal of Science and the Arts, of the fol- 
 lowing January. I have now subjoined a 
 few further observations, on the application 
 of voltaic electricity to the resuscitation of the 
 suspended functions of life. 
 
 Convulsions accidentally observed in the 
 limbs of dead frogs, originally suggested to 
 Galvani, the study of certain phenomena, 
 which from him have been styled Galvanic. 
 He ascribed these movements to an electrical 
 fluid or power, innate in the living frame, 
 or capable of being evolved by it, which he 
 denominated animal electricity. The Tor- 
 pedo , Gymnotus , and Silurus JElectriciis , fish 
 endowed with a true electrical apparatus, 
 ready to be called into action by an effort of 
 their will, were previously known to the na- 
 turalist, and furnished plausible analogies to 
 the philosopher of Bologna. Volta, to whom 
 this science is indebted for the most brilliant 
 discoveries on its principles, as well as for its 
 marvellous apparatus, justly called by his 
 name, advanced powerful arguments against 
 the hypothesis of Galvani. He ascribed the 
 muscular commotions, and other phenomena, 
 to the excitation of common electricity, by 
 arrangements previously unthought of by the 
 scientific world ; merely by the mutual con- 
 tact of dissimilar bodies, metals, charcoal, 
 and animal matter, applied either to each 
 other, or conjoined with certain fluids. And 
 at the present day, perhaps the only facts 
 which seem difficult to reconcile with the 
 beautiful theory of electro-motion, invented 
 by the Pavian professor, are some experi- 
 ments of Aldini, the nephew of the original 
 discoverer. 
 
 In these experiments, neither metals nor 
 charcoal were employed. Very powerful 
 muscular contractions seem to have been 
 excited, in some of the experiments, by 
 bringing a part of a warm-blooded, and of a 
 cold-blooded animal, into contact with each 
 other; as the nerve and muscle of a frog, 
 with the bloody flesh of the neck of a newly 
 decapitated ox. In other experiments, the 
 nerves and muscles of the same animal seem 
 to have operated Galvanic excitation ; and 
 again, the nerve of one animal acted with the 
 muscle of another. lie deduces from his 
 experiments, an inference in favour of his 
 uncle’s hypothesis, that a proper animal elec- 
 tricity is inherent in the body, which does 
 
GAL 
 
 GAL 
 
 not require the assistance of any external 
 agent, for its developement. Should we ad- 
 mit the reality of these results, we may per- 
 haps venture to refer them to a principle 
 analogous to Sir II. Davy’s pile, or voltaic 
 circuit, of two dissimilar liquids and char- 
 coal. I his part of the subject is however 
 involved in deep obscurity. 
 
 Many experiments have been performed, 
 in this country and abroad, on the bodies of 
 criminals, soon after their execution. Vas- 
 sali, Julio, and Rossi, made an ample set, on 
 several bodies decapitated at Turin. They 
 paid particular attention to the effect of gal- 
 vanic electricity on the heart, and other in- 
 voluntary muscles: a subject of much pre- 
 vious controversy. Volta asserted, that these 
 muscles are not at all sensible to this electric 
 power. Fowler maintained, that they were 
 affected ; but with difficulty and in a slight 
 degree. This opinion was confirmed by 
 Vassali; who further shewed, that the mus- 
 cles of the stomach, and intestines, might 
 thus also be excited. Aldini, on the con- 
 trary, declared, that he could not affect the 
 heart, by his most powerful galvanic arrange- 
 ments. 
 
 Most of the above experiments were how- 
 ever made, either without a voltaic battery, 
 or with piles, feeble in comparison with 
 those now employed. Those indeed per- 
 formed on the body of a criminal, at New- 
 gate, in which the limbs were violently agi- 
 tated ; the eyes opened and shut; the mouth 
 and jaws worked about, and the whole face 
 thrown into frightful convulsions, were made 
 by Aldini, with, I believe, a considerable 
 series of voltaic plates. 
 
 A circumstance of the first moment, in my 
 opinion, has been too much overlooked in 
 experiments of this kind, — that a muscular 
 mass through which the galvanic energy is 
 directly transmitted, exhibits very weak con- 
 tractile movements, in comparison with those 
 which can be excited by passing the influ- 
 ence along the principal nerve of the muscle. 
 Inattention to thisimportantdistinction, I con- 
 ceive to be the principal source of the slender 
 effects hitherto produced in such experiments 
 on the heart, and other muscles, independent 
 of the will. It ought also to be observed, that 
 too little distinction has been made between 
 the positive and negative poles of the battery ; 
 though there are good reasons for supposing, 
 that their powers on muscular contraction 
 are by no means the same. 
 
 According to Ritter, the electricity of the 
 positive pole augments, while the negative 
 diminishes the actions of life. Tumefaction 
 of parts is produced by the former; depres- 
 sion by the latter. The pulse of the hand, 
 be says, held a few minutes in contact with 
 the positive pole, is strengthened ; that of the 
 one in contact with the negative is enfeebled ; 
 the former is accompanied with a sense ol 
 
 heat, the latter with a feeling of coldness. 
 Objects appear to a positively electrified eye, 
 larger, brighter, and red ; while to one nega- 
 tively electrified, they seem smaller, less dis- 
 tinct, and bl uish,— colours indicating oppo- 
 site extremities of the prismatic spectrum. 
 1 be acid and alkaline tastes, when the tongue 
 is acted on in succession by the two electri- 
 cities, are well known, and have been inge- 
 niously accounted for by Sir II. Davy, in 
 his admirable Bakerian Lectures. The smell 
 of oxymuriatic acid, and of ammonia, are 
 said by Ritter, to be the opposite odours, 
 excited by the two opposite poles; as a full 
 body of sound and a sharp tone are the cor- 
 responding effects on the ears. These ex- 
 periments require verification. 
 
 Consonant in some respects, though not 
 in all, with these statements, are the doctrines 
 taught by a London practitioner, experienced 
 in the administration of medical electricity, 
 lie affirms, that the influence of the electri- 
 cal fluid of our common machines, in the cure 
 of disease, may be referred to three distinct 
 heads; first, the form of radii, when pro- 
 jected from a point positively electrified; se- 
 condly, that of a star, or the negative fire, 
 concentred on a brass ball; thirdly, the Ley- 
 den explosion. To each of these forms ho 
 assigns a specific action. The first acts as a 
 sedative, allaying morbid activity ; the second 
 as a stimulant ; and the last lias a deobstruent 
 operation, in dispersing chronic tumours. 
 An ample narrative of cases is given in con- 
 firmation of these general propositions. My 
 own experience leads me to suppose, that the 
 negative pole of a voltaic battery, gives more 
 poignant sensations than the positive. 
 
 But, unquestionably, the most precise and 
 interesting researches on the relation between 
 voltaic electricity and the phenomena of life, 
 are those contained in Dr Wilson Philip’s 
 Dissertations in the Philosophical Transac- 
 tions, as well as in his Experimental Inquiry 
 into the Laws of the Vital Inunctions, more 
 recently published. 
 
 In his earlier researches, he endeavoured 
 to prove, that the circulation of the blood, 
 and the action of the involuntary muscles, 
 were independent of the nervous influence. 
 In a late paper, read in January 1816, he 
 shewed the immediate dependence of the se- 
 cretory functions on the nervous influence. 
 
 The eighth pair of nerves distributed to 
 the stomach, and subservient to digestion, 
 were divided by incisions in the necks of 
 several living rabbits. After the operation, 
 the parsley which they ate remained without 
 alteration in their stomachs; and the ani- 
 mals, after evincing much difficulty of breath- 
 ing, seemed to die of suffocation. But when 
 in other rabbits, similarly treated, the gal- 
 vanic power was transmitted along the nerve, 
 below its section, to a disc of silver, placed 
 closely in contact with the skin of the ani- 
 
GAL 
 
 GAL 
 
 mal, opposite to its stomach, no difficulty of 
 breathing occurred. The voltaic action 
 being kept up for twenty-six hours, the 
 rabbits were then killed, and the parsley was 
 found in as perfectly digested a state, as that 
 in healthy rabbits fed at the same time ; and 
 their stomachs evolved the smell peculiar to 
 that of a rabbit during digestion. These ex- 
 periments were several times repeated with 
 similar results. 
 
 Hence it appears that the galvanic energy 
 is capable of supplying the place of the nerv- 
 ous influence, so that while under it, the 
 stomach, otherwise inactive, digests food as 
 usual. I am not, however, willing to adopt 
 the conclusion drawn by its ingenious author, 
 that the “ identity of galvanic electricity and 
 nervous influence is established by these ex- 
 periments.” They clearly shew a remark- 
 able analogy between these two powers, since 
 the one may serve as a substitute for the 
 other. It might possibly be urged by the 
 anatomist, that, as the stomach is supplied by 
 twigs of other nerves, which communicate 
 under the place of Dr Philips’ section of the 
 par vagum , the galvanic fluid may operate 
 merely as a powerful stimulus, exciting those 
 slender twigs to perform such an increase of 
 action, as may compensate for the w ant of 
 the principal nerve. The above experiments 
 were repeated on dogs, with like results; the 
 battery never being so strong as to occasion 
 painful shocks. 
 
 The removal of dyspnoea, as stated above, 
 led him to try galvanism as a remedy in 
 asthma. By transmitting its influence from 
 the nape of the neck to the pit of the sto- 
 mach, he gave decided relief in every one of 
 twenty- two cases, of which four were in pri- 
 vate practice, and eighteen in the Worcester 
 Infirmary. The power employed varied 
 from ten to twenty-five pairs. 
 
 The general inferences deduced by him 
 from his multiplied experiments, are, that 
 voltaic electricity is capable of effecting the 
 formation of the secreted fluids when applied 
 to the blood in the same w r ay in wfliich the 
 nervous influence is applied to it ; and that 
 it is capable of occasioning an evolution of 
 caloric from arterial blood. When the lungs 
 are deprived of the nervous influence, by 
 which their function is impeded, and even 
 destroyed, when digestion is interrupted, by 
 withdrawing this influence from the sto- 
 mach, these two vital functions are renewed 
 by exposing them to the influence of a gal- 
 vanic trough. “ Hence,” says he, “ gal- 
 vanism seems capable of performing all the 
 functions of the nervous influence in the 
 animal economy ; but obviously it cannot 
 excite the functions of animal life, unless 
 when acting on parts endowed with the liv- 
 ing principle.” 
 
 1 hese results of Dr Philip have been re- 
 cently confirmed by Dr Clarke Abel, of 
 
 Brighton, who employed, in one of the repe- 
 titions of the experiments, a comparatively 
 weak, and in the other a considerable power 
 of galvanism. In the former, although the 
 galvanism w r as not of sufficient power to oc- 
 casion evident digestion of the food, yet the 
 efforts to Vomit, and the difficulty of breath- 
 ing, constant effects of dividing the eighth 
 pair of nerves, were prevented by it. These 
 symptoms recurred when it was disconti- 
 nued, and vanished on its re- application. 
 ‘‘ The respiration of the animal,” he ob- 
 serves, “ continued quite free during the ex- 
 periment, except when the disengagement of 
 the nerves from the tin- foil, rendered a short 
 suspension of the galvanism necessary dur- 
 ing their readjustment.” “ The non-galva- 
 nized rabbit, breathed with difficulty, wheez- 
 ed audibly, and made frequent attempts to 
 vomit.” In the latter experiment, in which 
 the greater power of galvanism was employ- 
 ed, digestion went on as in Dr Philip’s ex- 
 periments. — Jour. Sc. ix. 
 
 M. Gallois, an eminent French physiolo- 
 gist, had endeavoured to prove, that the mo- 
 tion of the heart depends entirely upon the 
 spinal marrow, and immediately ceases when 
 the spinal marrow is removed or destroyed. 
 Dr Philip appears to have refuted this no- 
 tion, by the following experiments.- Rabbits 
 were rendered insensible by a blow on the 
 occiput ; the spinal marrow and brain were 
 then removed, and the respiration kept up by 
 artificial means: the motion of the heart, 
 and the circulation, were carried on as usual'. 
 W hen spirit of wine, or opium, w'as applied 
 to the spinal marrow or brain, the rate of the 
 circulation was accelerated. 
 
 These general physiological views will 
 serve, I hope, as no inappropriate introduc- 
 tion to the detail of the galvanic phenomena, 
 exhibited here on the 4th of November, in 
 the body of the murderer Clydesdale ; and 
 they may probably guide us to some valuable 
 practical inferences. 
 
 The subject of these experiments, was a 
 middle-sized, athletic, and extremely muscu- 
 lar man, about thirty years of age. He was 
 suspended from the gallows nearly an hour, 
 and made no convulsive struggle after he 
 dropped ; while a thief, executed along with 
 him, was violently agitated for a considerable 
 time. He was brought to the anatomical 
 theatre of our university in about ten mi- 
 nutes after he was cut down. Ilis face had 
 a perfectly natural aspect, being neither livid 
 n°i tumefied ; and there was no dislocation 
 of his neck. 
 
 Di Jell iay, the distinguished professor of 
 anatomy, having on the preceding day re- 
 quested me to perform the galvanic experi- 
 ments, I sent to his theatre with this viewr, 
 next morning, my minor voltaic battery, con- 
 sisting of 270 pairs of four inch plates, with 
 wires of communication, and pointed mo- 
 
GAL 
 
 GAL 
 
 tallic rods with insulating handles, for the 
 more commodious application of the electric 
 power. About five minutes before the po- 
 lice officers arrived with the body, the battery 
 was charged with a dilute nitro-sulphuric 
 acid, which speedily brought it into a state of 
 intense action. The dissections were skil- 
 fully executed by Mr Marshall, under the 
 superintendence of the professor. 
 
 Exp. 1. A large incision was made into 
 the nape of the neck, close below the occiput. 
 The posterior half of the atlas vertebra was 
 then removed by bone forceps, when the 
 spinal marrow was brought into view. A 
 profuse flow of liquid blood gushed from 
 the wound, inundating the floor. A con- 
 siderable incision was at the same time made 
 in the left hip, through the great gluteal 
 muscle, so as to bring the sciatic nerve into 
 sight ; and a small cut was made in the heel. 
 From neither of these did any blood flow. The 
 pointed rod connected with one end of the 
 battery, was now placed in contact with the 
 spinal marrow, while the other rod was ap- 
 plied to the sciatic nerve. Every muscle of 
 the body was immediately agitated with con- 
 vulsive movements, resembling a violent shud- 
 dering from cold. The left side was most 
 powerfully convulsed at each renewal of the 
 electric contact. On moving the second rod 
 from the hip to the heel, the knee being pre- 
 viously bent, the leg was thrown out with 
 such violence, as nearly to overturn one of 
 the assistants, who in vain attempted to pre- 
 vent its extension. 
 
 Exp. 2. The left phrenic nerve was now r 
 laid bare at the outer edge of the sterno- 
 thi/roideus muscle, from three to four inches 
 above the clavicle; the cutaneous incision 
 having been made by the side of the sterno- 
 cleido-mastoideus. Since this nerve is dis- 
 tributed to the diaphragm, and since it com- 
 municates with the heart through the eighth 
 pair, it was expected, by transmitting the 
 galvanic power along it, that the respiratory 
 process w'ould be renewed. Accordingly, a 
 small incision having been made under the 
 cartilage of the seventh rib, the point of the 
 one insulating rod was brought into contact 
 with the great head of the diaphragm, while 
 the other point was applied to the phrenic 
 nerve in the neck. This muscle, tne main 
 agent of respiration, was instantly contracted, 
 but with less force than w’as expected. Sa- 
 tisfied, from ample experience on the living 
 body, that more powerful effects can be pro- 
 duced in galvanic excitation, by leaving the 
 extreme communicating rods in close con- 
 tact with the parts to be operated on, while 
 the electric chain or circuit is completed, by 
 running the end of the wires along the top 
 of the plates in the last trough of either pole, 
 the other wire being steadily immersed in the 
 last cell of the opposite pole, 1 had imme- 
 diate recourse to this method, The success 
 
 of it was truly wonderful. Full, nay, labo- 
 rious breathing, instantly commenced. The 
 chest heaved, and fell ; the belly was pro- 
 truded, and again collapsed, with the relax- 
 ing and retiring diaphragm. This process 
 was continued, w ithout interruption, as long 
 as I continued the electric discharges. 
 
 In the judgment of many scientific gen- 
 tlemen who witnessed the scene, this respira- 
 tory experiment was perhaps the most strik- 
 ing ever made with a philosophical appara- 
 tus. Let it also be remembered, that for full 
 half an hour before this period, the body had 
 been w r ell nigh drained of its blood, and the 
 spinal marrow severely lacerated. No pulsa- 
 tion could be perceived meanwhile at the 
 heart or wrist ; but it may be supposed, that 
 but for the evacuation of the blood, — the 
 essential stimulus of that organ, — this phe- 
 nomenon might also have occurred. 
 
 Exp. 5. The supra-orbital nerve was laid 
 bare in the forehead, as it issues through the 
 supra-ciliary ybrarnm, in the eyebrow : the 
 one conducting rod being applied to it, and 
 the other to the heel, most extraordinary gri- 
 maces w r ere exhibited every time that the 
 electric discharges w^ere made, by running 
 the w f ire in my hand along the edges of the 
 last trough, from the 220th to the 270th 
 pair of plates; thus fifty shocks, each greater 
 than the preceding one, were given in two 
 seconds : every muscle in his countenance 
 was simultaneously thrown into fearful ac- 
 tion ; rage, horror, despair, anguish, and 
 ghastly smiles, united their hideous expres- 
 sion in the murderer’s face, surpassing far 
 the wildest representations of a Fuseli or a 
 Kean. At this period several of the specta- 
 tors were forced to leave the apartment from 
 terror or sickness, and one gentleman faint- 
 ed. 
 
 Exp. 4. The last galvanic experiment con- 
 sisted in transmitting the electric pow er from 
 the spinal marrow to the ulnar nerve, as it 
 passes by the internal condyle at the elbow r ; 
 the fingers now moved nimbly, like those of 
 a violin performer ; an assistant, who tried 
 to close the fist, found the hand to open for- 
 cibly, in spite of his efforts. When the one 
 rod was applied to a slight incision in the 
 tip of the fore-finger, the fist being previous- 
 ly clenched, that finger extended instantly ; 
 and from the convulsive agitation of the arm, 
 he seemed to point to the different spectators, 
 some of whom thought he had come to life. 
 
 About an hour was spent in these opera- 
 tions. 
 
 In deliberating on the above galvanic phe- 
 nomena, we are almost willing to imagine, 
 that if, without cutting into and wounding 
 the spinal marrow and blood-vessels in the 
 neck, the pulmonary organs had been set 
 a-playing at first, (as I proposed), by elec- 
 trifying the phrenic nerve, (which may be 
 done w ithout any dangerous incision), there 
 
GAL 
 
 GAL 
 
 is a probability that life might have been res- 
 tored. This event, however little desirable 
 with a murderer, and perhaps contrary to 
 law, would yet have been pardonable in one 
 instance, as it would have been highly ho- 
 nourable and useful to science. From the 
 accurate experiments of Dr Philip it appears, 
 that the action of the diaphragm and lungs is 
 indispensable towards restoring the suspend- 
 ed action of the heart and great vessels, sub- 
 servient to the circulation of the blood. 
 
 It is known, that cases of death-like le- 
 thargy, or suspended animation, from disease 
 and accidents, have occurred, where life has 
 returned, after longer interruption of its 
 functions, than in the subject of the preced- 
 ing experiments. It is probable, when ap- 
 parent dead) supervenes from suffocation with 
 noxious gases, &c. and when there is no 
 organic loesion, that a judiciously directed 
 galvanic experiment will, if any thing will, 
 restore the activity of the vital functions. 
 The plans of administering voltaic electri- 
 city hitherto pursued in such cases, are, in 
 my humble apprehension, very defective. No 
 advantage, we perceive, is likely to accrue 
 from passing electric discharges across the 
 chest, directly through the heart and lungs. 
 On the principles so well developed by Dr 
 Philip, and now illustrated on Clydesdale’s 
 body, we should transmit along the channel 
 of the nerves, that substitute for nervous in- 
 fluence, or that power which may perchance 
 awaken its dormant faculties. Then, indeed, 
 fair hopes may be formed of deriving exten - 
 sive benefit from galvanism ; and of raising 
 this wonderful agent to its expected rank, 
 among the ministers of health and life to 
 man. 
 
 I would, however, beg leave to suggest 
 another nervous channel, which I conceive to 
 be a still readier and more powerful one, to 
 the action of the heart and lungs, than the 
 phrenic nerve. If a longitudinal incision be 
 made, as is frequently done for aneurism, 
 through the integuments of the neck at the 
 outer edge of the sterno-mastoideus muscle, 
 about half-way between the clavicle and 
 ■angle of the lower jaw ; then on turning 
 over the edge of this muscle, we bring into 
 view the throbbing carotid, on the outside of 
 which, the par vagum , and great sympathetic 
 merve, lie together in one sheath. Here, 
 therefore, they may both be directly touched 
 and pressed by a blunt metallic conductor. 
 These nerves communicate directly, or indi- 
 rectly, with the phrenic ; and the superficial 
 nerve of the heart is sent off from the sym- 
 pathetic. 
 
 Should, however, the phrenic nerve be 
 aken, that of the left side is the preferable 
 of the two. From the position of the heart, 
 he left phrenic differs a little in its course 
 rom the right. It passes over the pericar - 
 Hum, covering the apex of the heart. 
 
 While the point of one metallic conductor 
 is applied to the nervous cords above des- 
 cribed, the other knob ought to be firmly 
 pressed against the side of the person, imme- 
 diately under the cartilage of the seventh 
 rib. The skin should be moistened with a 
 solution of common salt, or what is better, a 
 hot saturated solution of sal-ammoniac, by 
 which means, the electric energy will be 
 more effectually conveyed through the cuti- 
 cle, so as to complete the voltaic chain. 
 
 To lay bare the nerves above described, 
 requires, as I have stated, no formidable in- 
 cision, nor does it demand more anatomical 
 skill, or surgical dexterity, than every prac- 
 titioner of the healing art ought to possess. 
 We should always bear in mind, that the 
 subject of experiment is at least insensible to 
 pain ; and that life is at stake, perhaps irre- 
 coverably gone. And assuredly, it we place 
 the risk and difficulty of the operations, in 
 competition with the blessings, and glory 
 consequent on success, they will weigh as 
 nothing, with the intelligent and humane. 
 It is possible, indeed, that two small brass 
 knobs, covered with cloth moistened with so- 
 lution of sal ammoniac, pressed above and 
 below, on the place of the nerve, and the 
 diaphragmatic region, may suffice, without 
 any surgical operation : It may first be 
 
 tried. 
 
 Immersion of the body in cold water acce- 
 lerates greatly the extinction of life arising 
 from suffocation ; and hence less hopes need 
 be entertained, of recovering drowned per- 
 sons after a considerable interval, than when 
 the vital heat has been suffered to continue 
 with little abatement. None of the ordinary 
 practices judiciously enjoined by the Flumane 
 Society, should ever on such occasions be 
 neglected. For it is surely culpable to spare 
 any pains which may contribute, in the 
 slightest degree, to recal the fleeting breath 
 of man to its cherished mansion. 
 
 My attention has been again particularly 
 directed to this interesting subject, by a very 
 flattering letter which I lately received, from 
 the learned secretary of the lloyal Humane 
 Society. 
 
 In the preceding account, 1 had accidentally 
 omitted to state a very essential circumstance 
 relative to the electrization of Clydesdale. 
 The paper indeed was very rapidly written, 
 at the busiest period of my public prelec- 
 tions, to be presented to the society, as a sub- 
 stitute for the essay of an absent friend, and 
 was sent off to London, the morning after it 
 was read. 
 
 The positive pole or wire connected with 
 the zinc end of the battery, was that which I 
 applied to the nerve; and the negative, or 
 that connected with the copper end, was 
 that which I applied to the muscles. This 
 is a matter of primary importance, as the 
 following experiments will prove. 
 
GAM 
 
 GAR 
 
 Prepare the posterior limbs of a frog, for 
 voltaic electrization, leaving the crural nerves 
 connected, as usual, to a detached portion of 
 the spine. When the excitability has become 
 nearly exhausted, plunge the limbs into the 
 water of one wine glass, and the crural 
 nerves with their pendent portion of spine, 
 into that of the other. The edges of the two 
 glasses, should be almost in contact. Then 
 taking a rod ot zinc in one hand, and a rod 
 of silver (or a silver tea-spoon) in the other, 
 plunge the former into the water of the 
 limbs’ glass, and the latter into that of the 
 nerves’ glass, without touching the ' frog 
 itself, and gently strike the dry parts of the 
 bright metals together. Feeble convulsive 
 movements, or mere twitching of the fibres, 
 will be perceived at every contact. Reverse 
 now the position of the metallic rods, that 
 is, plunge the zinc into the nerves’ glass, and 
 the silver into the other. On renewing the 
 contact of the dry surfaces of the metal now, 
 very lively convulsions will take place ; and 
 if the limbs are skilfully disposed in a nar- 
 rowish conical glass, they will probably 
 spring out to some distance. This interest- 
 ing experiment may be agreeably varied in 
 the following way, with an assistant opera- 
 tor : Let that person seize in the moist fin- 
 ders of his left hand, the spine and nervous 
 cords of the prepared frog ; and in those of the 
 right hand, a silver rod ; and let the other 
 person lay hold of one of the limbs with his 
 right hand, while he holds a zinc rod in the 
 moist fingers of the left. On making the 
 metallic contact, feeble convulsive twitchings 
 will be perceived, as before. Holding still 
 the frog as above, let them merely exchange 
 the pieces of metal. On renewing the con- 
 tacts now, lively movements will take place, 
 which become very conspicuous, if one limb 
 be held nearly horizontal, while the other 
 hangs freely down. At each touch of the 
 voltaic pair, the drooping limb will start up, 
 and strike the hand of the experimenter. 
 
 It is evident, therefore, that for the pur- 
 poses of resuscitating dormant irritability of 
 nerves, or contractility of their subordinate 
 muscles, the positive pole must be applied to 
 the former, and the negative to the latter. 
 I need scarcely suggest, that to make the 
 above experiments analogous to the condition 
 of a warm-blooded animal, apparently dead, 
 the frog must have its excessive voltaic sen- 
 sibility considerably blunted, and brought 
 near the standard of the latter, before begin- 
 ning the experiments. Otherwise, that ani- 
 mal electroscope, incomparably more delicate 
 than the gold leaf condenser, will give very 
 decided convulsions with either pole. 
 
 At the conclusion of the article Caloric , 
 I have taken the liberty of suggesting some 
 simple and ready methods of supplying 
 warmth to the body of a drowned person.* 
 
 Gamboge is a concrete vegetable juice. 
 
 the produce of two trees, both called by the 
 Indians caracapulli (gambogia gutta Lin.), 
 and is partly of a gummy and partly of a 
 resinous nature. It is brought to us either 
 in form of orbicular masses, or of cylindrical 
 rolls of various sizes ; and is of a dense, 
 compact, and firm texture, and of a beauti- 
 ful yellow. It is chiefly brought to us from 
 Cambaja, in the East Indies, called also 
 Cambodja, and Cambcgia ; and hence it has 
 obtained its name of cambadium, cambo- 
 gium, gambogiurn. 
 
 It is a very rough and strong purge ; if 
 operates both by vomit and stool, and both 
 ways with much violence, almost in the in- 
 stant in which it is swallowed, but yet, as it 
 is said, without griping. The dose is from 
 two to four grains as a cathartic ; from four 
 to eight grains prove emetic and purgative. 
 The roughness of its operation is diminished 
 by giving it inaliquidform sufficiently diluted. 
 
 This gum resin is soluble both in water 
 and in alcohol. Alkaline solutions possess 
 a deep red colour, and pass the filter. Dr 
 Lewis informs us, that it gives a beautiful 
 and durable citron- yellow stain to marble, 
 whether rubbed in substance on the hot 
 stone, or applied, as dragon’s blood some- 
 times is. in form of a spirituous tincture. 
 When it is applied on cold marble, the stone 
 is afterward to be heated to make the colour 
 penetrate. 
 
 It is chiefly used as a pigment in water 
 colours, but does not stand. 
 
 Gangue. The stones which fill the cavi- 
 ties that form the veins of metals are called 
 the gangue, or matrix of the ore. 
 
 * Garnet. Professor Jameson divides this 
 mineral genus into 3 species, the pyramidal 
 garnet, dodecahedral garnet, and prismatic 
 garnet. 
 
 I. — Pyramidal contains 3 sub-species, \ e- 
 suvian, Egeran, and Gehlenite, which see. 
 
 II. — Dodecahedral garnet contains 9 sub- 
 species. 1. Pyreneite. 2. Grossulare. S- 
 Melanite. 4. Pyrope. 5. Garnet. 6. Al- 
 locbroite. 7. Colophonite. 8. Cinnamon- 
 stone. 9, Helvin. 
 
 III. — Prismatic garnet; the grenatite. 
 
 We shall treat here only of the garnet, 
 
 proper. Of this sub-species, we have two 
 kinds, the precious and common. 
 
 Precious or noble garnet. Colours dark 
 red, falling into blue. Seldom massive, 
 sometimes disseminated, most commonly 
 in roundish grains, and crystallized. 1. In 
 the rhomboidal dodecahedron, which is the 
 primitive form ; 2. Do. truncated on all 
 the edges ; 3. Acute double eight- sided py- 
 ramid ; and 4. Rectangular four-sided prism. 
 The surface of the grains is generally rough, 
 uneven, or granulated ; that of the crystals 
 is always smooth. Lustre externally glis- 
 tening ; internally shining, bordering on 
 
 splendent. Fracture conchoidal. Sometimes. 
 
 16 
 
GAS 
 
 GAS 
 
 it occurs in lamellar distinct concretions. 
 Transparent or translucent. Refracts single. 
 Scratches quartz, but not topaz. Brittle. 
 Rather difficultly frangible. Sp. gr. 4.0 to 
 4.2. Its constituents are, silica 39.66, alu- 
 mina 19.66, black oxide of iron S9.68, oxide 
 of manganese 1.80. — Berzelius. Before the 
 blow-pipe it fuses into a black enamel, or 
 scoria. It occurs imbedded in primitive 
 rocks, and primitive metalliferous beds. It 
 is found in various northern counties in 
 Scotland ; in Norway, Lapland, Sweden, 
 Saxony, France, &c. It is cut for ring- 
 stones. Coarse garnets are used as emery 
 for polishing metals. The following vitre- 
 ous composition imitates the garnet very 
 closely : 
 
 Purest white glass, 2 ounces 
 Glass of antimony, 1 ounce 
 Powder of Cassius, 1 grain 
 Manganese, 1 grain — Jameson. 
 
 The garnets of Tegu are most highly va- 
 lued. 
 
 Common garnet. Brown and green are 
 its most common colours. Massive, but 
 never in grains or angular pieces. Some- 
 times crystallized, and possesses all the forms 
 of the precious garnet. Lustre, shining or glis- 
 tening. Fracture, fine grained uneven. More 
 or less translucent ; the black kind nearly op- 
 aque, It is a little softer than precious garnet. 
 Rather difficultly frangible. Sp. gr. 3.7. Be- 
 fore the blow-pipe it melts more easily than 
 precious garnet. Its constituents are 38 silica, 
 20.6 alumina, 51.6 lime, 10.5 iron. — Vau- 
 quelin. It occurs massive or crystallized in 
 drusy cavities, in beds, in mica-slate, in clay- 
 slate, chlorite-slate, and primitive trap. It 
 is found at Kilranelagh and Donegal in Ire- 
 land ; at Arendal and Dramtnen in Nor- 
 way, and in many other countries. On ac- 
 count of its easy fusibility and richness in 
 iron, it is frequently employed as a llux in 
 smelting rich iron ores. It is sometimes 
 used instead of emery by lapidaries. — Jame- 
 son.* 
 
 * Gas. This name is given (o all per- 
 y elastic simple or compound, 
 
 except the atmosphere, to which the term 
 Air is appropriated. 
 
 I he solid state, is that in which, by the 
 predominance of the attractive forces, the 
 particles are condensed into a coherent aggre- 
 gate; the gaseous state, is that in which the 
 repulsive forces have acquired the ascendency 
 over the attractive; and the liquid condition 
 represents the equilibrium of these two 
 powers. Vapours are elastic fluids, which 
 have no permanence ; since a moderate re- 
 duction of temperature causes them to as- 
 sume the liquid or solid aggregation. 
 
 Cohesive attraction among homogeneous 
 particles, is the great antagonist to chemical 
 affinity, the attraction of composition, the 
 force which tends to bring into intimate 
 union, heterogeneous particles. Hence the 
 
 juxtaposition of two solids, of a solid and a 
 liquid, or even of two liquids, may never 
 determine their chemical combination, how- 
 ever strong their reciprocal affinity shall be. 
 
 In the case of tveo liquids, or a liquid 
 and a solid, mere juxtaposition requires, 
 that the denser body be undermost, and 
 that no disengagement of gas, or external 
 vibration, agitate the surfaces in contact. 
 Hence those world framers, who ascribe the 
 saltness of the sea to supposed beds of rock 
 salt at its bottom, have still the phenomenon 
 of the strong impregnation of the surface to 
 explain ; for the profound tranquillity which 
 is knowm to reign at very moderate depths 
 in this mighty mass, would forever prevent 
 the diffusion of the saturated brine below', 
 among the light waters above. Or if this 
 tranquillity be disputed, then progressive den- 
 sity from above downwards should be found, 
 and continually increasing impregnation. 
 Now none of these results has occurred. 
 But with gases in contact, there is no obsta- 
 cle from cohesive attraction, to the exertion 
 of their reciprocal affinities. Lienee, how- 
 ever feeble these may be, they never fail, 
 sooner or later, to cause an intimate mixture 
 of different gases, in which the ultimate par- 
 ticles approach within the limit correspond- 
 ing to their reciprocal action. The diffe- 
 rence of density may delay, but cannot pre- 
 vent uniform diffusion. Thus we see that 
 known pow r ers can account for the pheno- 
 mena. There is no need therefore of having 
 recourse to the strange hypothesis of Mr 
 Dalton, that one gas is a neutral unresisting 
 void with regard to another, into which it 
 w’ill rush by its innate expansive force. But 
 of this fancy sufficient notice has been taken, 
 in the article Air (Atmospheric). 
 
 The principle of gaseous combination, first 
 broached in the neglected treatise of Mr 
 Higgins, but since developed with consum- 
 mate sagacity from the original researches of 
 M. Gay Lussac, has thrown a new light on 
 pneumaticchemistry, which has been reflected 
 into all its mysterious departments, of animal 
 and vegetable analysis. Having given the 
 details under the article Equivalents {Che- 
 mical). we shall merely state in this place, 
 that the combinations of gaseous bodies, are 
 always effected in simple ratios of the vo- 
 lumes, so that if we represent one of the 
 terms by unity, or 1, the other is 1, 2, or at 
 most 3. Thus ammoniacal gas neutralizes 
 exactly a volume equal to its own, of the 
 gaseous acids. It is hence probable, that if 
 the alkalis and acids were in the elastic state, 
 they would all combine, each in equal vo- 
 lume with another, to produce neutral salts. 
 The capacity of saturation of the acids and 
 alkalis, measured by volumes, would then be 
 the same; and perhaps this would be the 
 best manner of estimation. In the follow- 
 
 ing tables ol gaseous combination, bodies 
 naturally in the solid state, like sulphur, 
 
GAS 
 
 GAS 
 
 carbon, and iodine, will be referred to their 
 gaseous densities, or the bulks which they 
 occupy relative to their weights, when diffus- 
 ed by chemical combination among the par- 
 ticles of a permanently elastic fluid. This 
 view of the subject, first introduced by M. 
 Gay Lussac, and happily exemplified in his 
 excellent memoir on iodine, will simplify our 
 representation of many compounds. Final- 
 ly, the apparent contractions or condensa- 
 tions of volume, which gases suffer by their 
 reciprocal affinity, have also simple ratios 
 with the volume of one of them ; a property 
 peculiar to gaseous bodies. We shall distri- 
 bute under the following heads, our general 
 observations on gases. 1 . Tabular views of 
 the densities, and combining ratios of the 
 gases. 2 . A description of their general 
 habitudes with solids and liquids. 3. An 
 account of the principal modes of analyzing 
 gaseous mixtures. 4. Of gasometry, or the 
 measurement of the density and volume of 
 gases. 
 
 1 . We are indebted to Dr Prout for an 
 able memoir on the relation between the 
 specific gravities of bodies in their gaseous 
 state, and the weights of their atoms, or 
 prime equivalents, inserted in the sixth vo- 
 lume of the Annals of Philosophy. His 
 observations are founded on M. Gay Lus- 
 sac’s doctrine of volumes. Dr Prout con- 
 siders atmospheric air as a chemical com- 
 pound, constituted by bulk of four volumes 
 of azote and one of oxygen ; and, reckoning 
 the atom of oxygen as 10 , and that of azote 
 as 17.5, it will be found to consist of one 
 atom of oxygen, and two atoms of azote, or 
 per cent of oxygen 22.22 
 Azote 77.77 
 
 Though almost all experiments have hitherto 
 led us to regard the atmosphere as contain- 
 ing 21 volumes in the 100 of oxygen, we 
 must, in this view, ascribe the excess of one 
 per cent to an error of observation. Now, 
 it is not improbable, that in the explosive 
 eudiometer with hydrogen over mercury, or 
 in the nitrous gas eudiometer over water, 
 one per cent of azote may be pretty uniform- 
 ly condensed. 
 
 Calling the prime equivalent of oxygen, 
 
 1 . 000 , and that of azote 1.75, as deduced 
 both from nitric acid and ammonia, we may 
 easily calculate the specific gravities of these 
 two gaseous elements of the atmospheric com- 
 pound, itself being represented in sp. gr. by 
 
 1 . 00 , and in the rela tive u 
 
 stituents, by 1 . 00 -{- 1.75 X 2 ; or 22.22 -\- 
 77.77. 
 
 The ancient problem of Archimedes, for 
 determining the fraud of the goldsmith, in 
 making king Hiero’s crown, which is so im- 
 portant in chemistry for computing the mean 
 density of a compound, the specific gravities 
 of whose two constituents are given ; and 
 for thence enabling us, by compaiing that 
 result, with the density found by experi- 
 
 ment, to discover the change of volume due 
 to the chemical action, is of peculiar value 
 in pneumatic investigations. It will enable 
 us to solve, without difficulty, the two fol- 
 lowing problems: — 
 
 1 st, Having given the specific gravity of a 
 mixed gas, and the specific gravities of its 
 two constituent gases, to determine the vo- 
 lume, and consequently the quantity of each, 
 present in the mixture. 
 
 2 d, Having given the specific gravity of a 
 mixed gas, and the proportions by weight 
 and volume of its constituents, to determine 
 the specific gravities of each of its consti- 
 tuents. In both cases, no chemical conden- 
 sation or expansion is supposed, and only 
 two gases are concerned. 
 
 1 st, Let d be the sp. gr. of the denser gas; 
 
 l of the lighter gas; 
 
 m mixed gas; 
 
 .r the volume of the denser gas ; 
 y of the lighter gas ; 
 
 v total volume of the compound. 
 
 v (in — l ) 
 
 Then x = — r- 7-7 r., and y =* 
 
 (i d — m)-\-(m — 1) J 
 
 v ( d — m) 
 
 (d — m) -|- (m — l) 
 
 from one or other of which formula?, the vo- 
 lume of one or other constituent may be 
 found ; and by multiplying the volume by 
 the specific gravity, its weight is given. The 
 same formula is stated in words under the 
 article Coal Gas. 
 
 2 d, When the specific gravities of the 
 components are sought ; the specific gravity 
 of the compound, as well as the volume and 
 weight of each component being given, we 
 have the following formula: — 
 
 Let x be the sp. gr. of that whose weight is 
 a and volume m. 
 
 y be the sp. gr. of that whose weight is 
 b and volume n. 
 
 Then mx mJ = 5 , the sp. gr. of the com- 
 
 m -J- 71 
 
 pound whose weight = 1. 
 
 But the volume of one body multiplied into 
 its specific gravity, is to the volume of ano- 
 ther, multiplied into its specific gravity, as the 
 weight of the first, is to that of the second, or 
 
 mx : ny : : a : b 
 
 any 
 
 And m 4- n — ny = — — } « s — * 
 
 6 
 
 Whence y = 
 
 (m-\-n)b 
 ' — y 
 
 an -f- bit 
 
 And x = 
 
 m — ny 
 m 
 
 Dr Prout has very ingeniously applied this 
 formula, to the determination of the specific 
 gravities of oxygen and azote, which arc, 
 Oxygen, 1.1111 
 
 Azote, 0.9723 
 
GAS 
 
 His investigation of the specific gravities of 
 hydrogen from that of ammonia, is conduct- 
 ed on principles still less disputable. Ihe 
 mean of the experimental results obtained by 
 MM. Biot and Arago and Sir H. Davy on 
 ammoniacal gas, is 0.5902. Now it has been 
 demonstrated, that 2 volumes of it are re- 
 solvable into 4 volumes of constituent gases, 
 of which 3 volumes are hydrogen and 1 
 azote. Hence if from double the specific 
 gravity of ammonia, we subtract the specific 
 gravity of azote, the remainder divided by 3 
 will be the specific gravity of hydrogen. Or, 
 putting the same thing into an algebraic 
 form, on the principle that the sum of the 
 weights divided by the sum of the volumes, 
 gives the specific gravity of the mixture, let 
 x be the specific gravity of hydrogen, then ex- 
 
 periment shews, that 
 
 3x-j- 0.9722 
 2 ~ 
 
 0.5902; 
 
 Whence x=z 
 
 2X0.5902 — 0.9722 
 ~~ 3 ~ 
 
 0.0694. 
 
 The density of hydrogen therefore is to that 
 of azote, atmospherical air, and oxygen, 
 
 GAS 
 
 \ 
 
 as 1 to 14, 1 to 14.4, and 1 to 16, respec- 
 tively. 
 
 And with regard to muriatic acid gas, it 
 is well known to result from the union of 
 chlorine and hydrogen in equal volumes, 
 without any condensation ; therefore if we 
 call the sp. gr. of the compound gas 1.278, 
 and from the double of that number deduct 
 the sp. gr. of hydrogen, we shall have the 
 
 sp. gr. of chlorine = 1.278 X 2 — 0.0694 
 — 2.4866, which may be converted into 
 the even number 2.5 without any chance of 
 error. See Sect. IV. 
 
 In the common tables of equivalent ratios, 
 adapted to the hypothesis that water is a 
 compound of one atom of oxygen and one 
 of hydrogen, or of half a volume of the for- 
 mer and one volume of the latter, w T e must 
 compute the ratios of gaseous combination, 
 among different bodies, by multiplying the 
 weight of their atom or their prime equiva- 
 lents by half the sp.gr. of oxygen =0.5555. 
 If the volume and sp. gr. of hydrogen were 
 reckoned unity, then the doctrine of volumes 
 and prime equivalents would coincide. 
 
 General Table of Gaseous Bodies , by Dr Ure. 
 
 Names. 
 
 Sp. gr. 
 air = 
 1. 00. 
 
 Weight 
 of 100 
 cu. inches 
 
 Weight 
 of prime 
 equiv. 
 oxygen 
 = 1. 
 
 Constituents 
 
 by 
 
 volume. 
 
 Resulting 
 
 volume. 
 
 Hydrogen, 
 
 0.0694 
 
 2.118 
 
 0.125 
 
 
 
 Carbon, 
 
 0.4 1 66 
 
 12.708 
 
 0.750 
 
 
 
 Subcarb. hydrogen, 
 
 0.5555 
 
 17.000 
 
 1.000 
 
 2 hyd. 4- 1 carb. 
 
 1 
 
 Ammonia, 
 
 0.5902 
 
 18.000 
 
 2.125 
 
 3 hyd. 4 - 1 azot. 
 
 2 
 
 Steam of water, 
 
 0.625 
 
 19.062 
 
 1.125 
 
 2 hyd. 4- 1 oxy. 
 
 
 Phosphorus, 
 
 0.833 
 
 25.42 
 
 1.500 
 
 
 Phosphur. hydrogen, 
 
 0.902 
 
 27.47 
 
 1.625 
 
 1 phos. 4 - 1 hyd. 
 
 1 
 
 Subphos. hydrogen, 
 
 0.9722 
 
 29.65 
 
 1.750 
 
 1 phos. 4 - 2 hyd. 
 
 1 
 
 Carbonous oxide, 
 
 0.9722 
 
 29.65 
 
 1.750 
 
 2 carb. -j- 1 oxy. 
 
 H 
 
 Carburetted hydrogen, 
 
 0.9722 
 
 29.65 
 
 0.875 
 
 1 carb. 4- 1 hyd. 
 
 1 
 
 Azote, 
 
 0.9722 
 
 29.65 
 
 1.750 
 
 
 Prussic acid, 
 
 0.9374 
 
 28.59 
 
 3.375 
 
 1 cyan. 4 - 1 hyd. 
 
 2 
 
 Atmospheric air, 
 
 1 .0000 
 
 30.519 
 
 4.500 
 
 1 oxy. 4* 4 azot. 
 
 5 
 
 Deutoxide of azote, 
 
 1.0416 
 
 31.77 
 
 5. 750 
 
 1 oxy. 4 - 1 azot. 
 
 2 
 
 Oxygen, 
 
 1.1111 
 
 33.888 
 
 1.000 
 
 
 
 Sulphur, 
 
 1.1111 
 
 33.888 
 
 2.000 
 
 
 
 Sulphuretted hydrogen, 
 
 1.1805 
 
 36.006 
 
 2.125 
 
 1 hyd. 4 - 1 snip. 
 
 1 
 
 Muriatic acid, 
 
 1.2840 
 
 39.183 
 
 4.6125 
 
 1 hvd. 4 - 1 chlo. 
 
 2 
 
 Carbonic acid, 
 
 1.5277 
 
 46.596 
 
 2.750 
 
 1 carb. 4 - 1 oxy. 
 
 1 
 
 Protoxide of azote, 
 
 1.5277 
 
 46.596 
 
 2.750 
 
 1 oxy. 4- 2 azote 
 
 1 J 
 
 A T. 
 
 Alcohol vapour, 
 
 1.6133 
 
 49.20 
 
 2.875 
 
 1 ol.gas 4 * 1 wa. 
 
 1 
 
 Cyanogen, 
 
 1.8055 
 
 55.07 
 
 3.25 
 
 icarb. 4- 1 azote 
 
 1 
 
 Chloroprussie acid, 
 
 2.1527 
 
 65. 69 
 
 7.75 
 
 l cya. 4- 1 chlo. 
 
 2 
 
 Muriatic ether, 
 
 2.219 
 
 67.68 
 
 10.375 
 
 Imur. 4-2 alco. 
 
 2 
 
 nilphurous acid, 
 
 2.222 
 
 67.77 
 
 4.Q00 
 
 1 oxy. 4 - 1 sulp. 
 
 1 
 
 Deutoxide of chlorine, 
 
 2.361 
 
 72.0 
 
 9.50 
 
 2 oxy. 4 - 1 chlo. 
 
 2 
 
 Fluoboric acid, 
 
 2.371 
 
 72.312 
 
 8.500 
 
 
 Protoxide of chlorine, 
 Chlorine, 
 
 2.44 
 
 2.500 
 
 74.42 
 
 76.25 
 
 5.50 
 
 4.50 
 
 2 oxy. 4 - 4 chlo. 
 
 5 
 
 Sulphuric ether vapour, 
 
 2.586 
 
 78.87 
 
 2.875 
 
 1 olef. 4- 1 wat. 
 
 1 
 
 Nitrous acid, 
 
 2.638 
 
 80.48 
 
 4.75 
 
 3 oxy. 4 - 2 azote 
 
 
 Constituent 
 
 prime 
 
 equivalents. 
 
 2 hyd. + 1 carb. 
 
 3 hyd. -f 1 azote 
 1 hyd. + 1 oxyg. 
 
 1 phos.-f 1 hyd. 
 
 1 phos. 4-2 hyd. 
 
 I carb. 4- 1 oxyg. 
 1 carb. + 1 hyd. 
 
 I cyan. + 1 hyd. 
 
 1 oxyg. 4 * 2 azote 
 
 2 oxyg. -f 1 azote 
 
 1 hyd. -j - 1 sulph. 
 
 1 hyd.-j-l chlor. 
 
 1 carb. -f- 2 oxyg. 
 
 1 oxyg. 4 - 1 azote 
 
 2 ol. gas 4-1 water 
 2 carb. 4- 1 azote 
 
 1 cyan. 4- 1 chlor. 
 
 1 mu. acid 4- 2 ale. 
 
 2 oxyg. 4 - 1 sulph 
 1 chlor. 4 - 4 oxyg. 
 
 1 oxyg. 4- 1 chlor. 
 
 4 olef. 4 - 1 water 
 
 3 oxyg. 4 - 1 azote 
 
GAS 
 
 GAS 
 
 Table of' Gaseous bodies — continued. 
 
 Names. 
 
 Sp. gr. 
 air = 
 1.00. 
 
 Weight 
 Of 100 
 cu. inches. 
 
 Weight 
 of prime 
 equiv. 
 oxvgerj 
 — 1 . 
 
 Constituents 
 
 by 
 
 volume. 
 
 Resulting 
 
 volume. 
 
 Constituent 
 
 prime 
 
 equivalents. 
 
 viulphuret of carbon, 
 
 2.644 
 
 80.6 6 
 
 4.750 
 
 2 carb. + 4 sulp. 
 
 2 
 
 2 sulph. 4 - 1 carb. 
 
 Sulphuric acid, 
 
 2.777 
 
 84.72 
 
 5.000 
 
 3 oxy. -f- 2 sulp. 
 
 2 
 
 Soxyg. 4 - l sulph. 
 
 Chlorocarbonous acid, 
 
 3.472 
 
 105.9 
 
 6.25 
 
 1 chi. -f lcar.ox. 
 
 2 
 
 1 chlor. 4 - lcar.ox. 
 
 Sal ammoniac, 
 
 3.746 
 
 114.3 
 
 6.75 
 
 2 am. -f 2 mur. 
 
 1 
 
 1 am. 4- 1 mu. acid 
 
 Nitric acid, 
 
 .3.7 5 
 
 114.37 
 
 6.75 
 
 5 oxy. 4 - 2 azote 
 
 2 
 
 5 oxyg. 4 - 1 azote 
 
 Hydriodic acid, 
 Oil of turpentine, 
 
 4.340 
 
 5.013 
 
 132.37 
 
 152.9 
 
 15.625 
 
 1 hyd.-j- liodin. 
 
 2 
 
 L hyd. 4 - 1 iodine 
 
 Chloric acid, 
 
 5.277 
 
 1 60.97 
 
 9.5 
 
 3 oxy. 4-2 chlo. 
 
 2 
 
 5 oxyg. 4 - 1 chlor. 
 
 Fluobqrate of ammonia, 
 
 5.902 
 
 180. 
 
 10.625 
 
 2 am. 4 - 2 ftuoh. 
 
 1 
 
 1 am. 4- 1 fluobor. 
 
 Subfluob. ammonia, 
 
 7.10 
 
 216.7 
 
 12.750 
 
 4 am. 4-2fluob. 
 
 1 
 
 2 am. 4 - 1 fluobor. 
 
 Tritosubfluob. ammonia, 
 Fluosilicate of ammonia, 
 
 8.26 , 
 
 252. 
 
 14.875 
 
 6 am. 4 - 2 fiuob. 
 2 am. 4- 1 acid 
 
 1 
 
 3 am. 4-1 fluobor. 
 
 In the preceding table I have endeavoured 
 to assemble the principal features of gaseous 
 combination. For the properties of these 43 
 different gases, see the separate articles in 
 the Dictionary. 
 
 II. Of the general habitudes of gaseous 
 matter with solids and liquids. Mr Dal- 
 ton has written largely on these relations; 
 but his results are so modified by speculation, 
 that it is difficult to distinguish fact from 
 hypothesis. Dr Henry, however, made some 
 good researches on the subject of this divi- 
 sion, but they have since been so much ex- 
 tended and improved by M. de Saussure, that 
 I shall take his elaborate researches for my 
 guide. His Memoir on the absorption of the 
 
 gases by different bodies was originally read 
 to the Geneva Society on the 16th April 
 1812, and appeared in Gilbert’s Annalgn 
 der Physik for July 1814, from which it was 
 translated into the 6 th volume of the Annals 
 of Philosophy. 
 
 1. Of the absorption of unmixed gases by 
 solid bodies. 
 
 Of all solid bodies charcoal is the most 
 remarkable in its action on the gases. In 
 M. de Saussure’s experiments, the red-hot 
 charcoal was plunged under mercury, and 
 introduced, after it became cool, into the gas 
 to be absorbed, without ever coming into 
 contact with atmospherical air. 
 
 TABLE of the Volumes of Gases absorbed by one volume of 
 
 Gabes. 
 
 Charcoal. 
 
 Meer- 
 
 schaum. 
 
 Adhesive 
 
 slate. 
 
 Lignif. 
 
 asbestus. 
 
 Saxon 
 
 hydroph. 
 
 Quartz. 
 
 Ammonia, 
 
 90 
 
 15 
 
 1 1.3 
 
 12.75 
 
 64 
 
 10 
 
 Muriatic acid, 
 
 85 
 
 — 
 
 — 
 
 — 
 
 17 
 
 — 
 
 Sulphurous acid, 
 
 65 
 
 — 
 
 — 
 
 — 
 
 7.37 
 
 — 
 
 S vi 1 ph u re 1 1 ed hydrogen. 
 
 55 
 
 11.7 
 
 — 
 
 — 
 
 — 
 
 — 
 
 Nitrous oxide, 
 
 40 
 
 O. ! 5 
 
 — 
 
 — 
 
 — 
 
 — — 
 
 Carbonic acid, 
 
 35 
 
 5.26 
 
 2. 
 
 1.7 
 
 1.0 
 
 0.6 
 
 Olefiant gas, 
 
 35 
 
 3.70 
 
 1.5 
 
 1.7 
 
 0.8 
 
 .0-6 
 
 Carbonic oxide, 
 
 9.42 
 
 1.17 
 
 0.55 
 
 0.58 
 
 — 
 
 — 
 
 Oxvoen, 
 
 9. 25 
 
 1.49 
 
 0.7 
 
 0.47 
 
 0.6 
 
 0.45 
 
 Azote, 
 
 7.5 
 
 1.6 
 
 0.7 
 
 0.47 
 
 0.6 
 
 0.45 
 
 Oxcarburetted hydrogen £ 
 from moist charcoal, } 
 Hydrogen, 
 
 5.0 
 
 0.85 
 
 0.55 
 
 0.41 
 
 
 ■ — 
 
 1.7 5 
 
 0.44 
 
 0.48 
 
 0.31 
 
 0.4 
 
 0.37 
 
 The absorption was not increased by al- 
 lowing the charcoal to remain in contact 
 .with the gases aftpr 21 hours; with the ex- 
 
 ception of oxygen, which goes on condens- 
 ing for years, in consequence of the slow 
 formation and absorption of carbonic acid. 
 
 I 
 
GAS 
 
 GAS 
 
 If the charcoal be moistened, the absorption 
 of all those gases that have not a very strong 
 affinity for water, is distinctly diminished. 
 Thus boxwood charcoal, cooled under mer- 
 cury, and drenched in water while under 
 the mercury, is capable of absorbing only 1 5 
 volumes of carbonic acid gas; although, be- 
 fore being moistened, it could absorb 35 
 volumes of the same gas. Dry chaicoal, 
 saturated with any gas, gives out, on immer- 
 sion in water, a quantity corresponding to 
 the diminution of its absorbing power. Dur- 
 ing the absorption of gas by charcoal, an 
 elevation of temperature takes place, pro- 
 portional to the rapidity and amount of tiie 
 absorption. The vacuum of the air-pump 
 seems to possess the same influence as heat, 
 in rendering charcoal capable of absorbing 
 gaseous matter. A transferrer with a small 
 jar containing a piece ol charcoal was ex- 
 hausted, and being then plunged into a 
 pneumatic trough, was filled with mercury. 
 The charcoal was next introduced into a 
 gas, and absorbed as much of it, as after 
 having been ignited. As the rapid absorp- 
 tion of carbonic acid gas by charcoal can 
 raise the thermometer 25°, so its extraction 
 by the air-pump, sinks it 7. 5°. 
 
 Though charcoal possesses the highest ab- 
 sorbent power, yet it is common to all bodies 
 which possess a certain degree of porosity, 
 after they have been exposed to the action of 
 an air-pump. Meerschaum, like charcoal, 
 absorbs a greater bulk of rare than dense gas. 
 Dried woods, linen threads, and silks, also 
 absorb the gases. Of ammonia, hazel ab- 
 sorbs 100 volumes, mulberry 88, linen thread 
 68, silk 78 ; of carbonic acid, in the above 
 order, 1.1, 0.46, 0.62, 1.1 ; of this gas, fir 
 absorbed 1.1, and w ool 1 . 7. 
 
 The rate of absorption of different gases, 
 appears to be the same, in all bodies of simi- 
 lar chemical properties. All the varieties of 
 asbestus condense more carbonic acid gas, 
 than oxygen gas; but woods condense more 
 hydrogen, than azote. Yet the condensa- 
 tions themselves in different kinds of asbestus, 
 or wood, or charcoal, are very far from be- 
 ing equal. Ligniform asbestus absorbs a 
 greater volume of carbonic acid gas, than 
 rock-cork ; so does hydrophane than the 
 swimming quartz of St Ouen, and the quartz 
 -of Vauvert; and the absorption of gases by 
 boxwood charcoal, is much greater than by 
 fir charcoal. These differences are not in 
 the least altered, if, instead of equal vo- 
 lumes, equal weights of charcoal be employ- 
 ed. It is curious that a piece of solid char- 
 coal absorbs volumes, and the same re- 
 duced into fine powder absorbs only three vo- 
 lumes. The absorbing power of most kinds 
 of charcoal increases as the specific gravity 
 increases; and it is obvious, that the pores 
 must become smaller and narrower with the 
 increase of density. Charcoal from cork, 
 
 of a specific gravity not exceeding 0.1, ab- 
 sorbed no sensible quantity of atmospheric 
 air. Charcoal from fir, sp.gr. 0.4, absorb- 
 ed times its volume of atmospherical air ; 
 that from boxw’ood, sp. gr. 0.6, absorbed 
 of air ; and pit-coal of vegetable origin from 
 Russiberg, sp. gr. 1.526, absorbed 10^ times 
 its volume of air. Rut, as the density aug- 
 ments, w r e arrive at a limit, when the pores 
 become too small to allow gases to enter. 
 Thus, the black-lead of Cumberland, con- 
 taining 0.96 of carbon, sp. gr. 2. 17, produces 
 no alteration on atmospherical air. But this 
 correspondence between the power of ab- 
 sorbing, and the specific gravity, is only ac- 
 cidental. Accurate experiments shew re- 
 markable deviations from this rule. The 
 different kinds of charcoal, whether of simi- 
 lar or dissimilar sp. gravities, always differ 
 from each other in their organization. They 
 cannot be considered as resembling a sponge, 
 whose pores and density may be modified by 
 pressure. 
 
 On the whole, it appears that the property 
 of condensing gases, possessed by some solids, 
 is wdthin certain limits, in the inverse ratio 
 of the internal diameter of the pores of the 
 absorbing bodies. But besides the porosity, 
 there are other tw r o circumstances which 
 must be attended to in these absorptions: 
 
 1. The different affinities which exist be- 
 tween the gases and the solid bodies; and, 
 
 2. The power of expansion of the gases, or 
 the opposition they make to their condensa- 
 tion, at different degrees of heat and atmos- 
 pherical pressure. 
 
 The experiments hitherto described relate 
 to the absorption of a single gas, not mixed 
 with any other. But, when a piece of char- 
 coal saturated w'ith either oxygen, hydrogen, 
 azote, or carbonic acid, is put into another 
 gas, it allows a portion of the first to escape, 
 in order to absorb into its pores a portion of 
 the second gas. The volume of gas thus 
 expelled from charcoal by another gas, varies 
 according to the proportion, in which both 
 gases exist in the unabsorbed residue. The 
 quantity expelled is greater, the greater the 
 excess of the expelling gas. Yet it is not 
 possible, in close vessels, to expel the whole 
 of one gas, out of charcoal, by means of an- 
 other ; a small quantity always remains in the 
 charcoal. 
 
 Two gases, united by absorption in char- 
 coal, often experience a greater condensation 
 than each would in a separate state. For 
 example, the presence of oxygen gas in char- 
 coal facilitates the condensation of hydrogen 
 gas ; the presence of carbonic acid gas, or of 
 azote, facilitates the condensation of oxygen 
 gas; and that of hydrogen, the condensation 
 of azote. Yet, this effect does not take place 
 in all cases, with the four gases now men- 
 tioned ; for the presence of azote in char- 
 coal does not promote the absorption of car- 
 
GAS 
 
 GAS 
 
 bonic acid gas. When the absorption of 
 one of the four named gases, has been faci- 
 litated by another of them, no perceptible 
 combination between the two takes place, at 
 least within the interval of some days. So, 
 for example, notwithstanding the assertion of 
 Rouppe and Van Noorden, no separation of 
 water appears, when charcoal saturated with 
 hydrogen at the common temperatures is 
 put into oxygen gas; or when the experi- 
 ment is reversed. Nor has azote and hydro- 
 gen been united in this way into ammonia, 
 or azote and oxygen into nitric acid. 
 
 2. Absorption of gases by liquids. 
 
 “ That all gases are absorbed by liquids,’* 
 says M. de Saussure, “ and that most of 
 them are again separated by heat, or the di- 
 
 minution of external pressure, has been long 
 known. We now possess accurate results 
 respecting the rate of this absorption. For 
 a set ot careful and regular experiments on 
 this subject, we are indebted to Dr Henry of 
 Manchester. Mr Dalton has a little altered 
 some of these results ; and, by means of 
 them, has contrived a theory which not only 
 explains the absorption of gases by water, 
 but by all other liquids ; but it is in oppo- 
 sition to most of the results which I have 
 obtained by means of solid porous bodies.” 
 The following table exhibit-, the volumes 
 of the different gases absorbed, according to 
 the accurate experiments of Saussure, by 
 100 volumes of 
 
 Gases. 
 
 Water. 
 
 Alcohol 
 sp. gr. 
 0.84. 
 
 Naphtha 
 sp- gr. 
 0.784. 
 
 Oil of lav. 
 ender sp. 
 gr. 0.88. 
 
 Olive oil. 
 
 Satur. 
 
 solution 
 
 mur.pot. 
 
 Sulphurous acid, 
 
 4378 
 
 11577 
 
 
 
 
 
 Sulphuretted hydrogen, 
 
 253 
 
 606 
 
 
 
 
 
 Carbonic acid, 
 
 106 
 
 186 
 
 169 
 
 191 
 
 151 
 
 61 
 
 Nitrous oxide, 
 
 76 
 
 153 
 
 254 
 
 275 
 
 150 
 
 21 
 
 Olefiant gas, 
 
 15.3 
 
 127 
 
 261 
 
 209 
 
 122 
 
 10 
 
 Oxygen gas, 
 
 6.5 
 
 16.25 
 
 — 
 
 — 
 
 — 
 
 — 
 
 Carbonous oxide, 
 
 6.2 
 
 14.50 
 
 20 
 
 15.6 
 
 14.2 
 
 5.2 
 
 Oxycarburetted hydrogen, 
 
 5.1 
 
 7.0 
 
 
 
 
 
 Hydrogen, 
 
 4.6 
 
 5.1 
 
 
 
 
 
 Azote, 
 
 4.1 
 
 4.2 
 
 
 
 
 
 The above liquids were previously freed 
 from air, as completely as possible, by long 
 and violent boiling. But those which would 
 have been altered or dissipated by the appli- 
 cation of such a heat, as oils, and some saline 
 solutions, were freed from air by means of 
 the air-pump. To produce a speedy and 
 complete absorption, a large quantity of those 
 gases w'hich are absorbed only in small quan- 
 tity by liquids, as azote, oxygen, and hydro- 
 gen, was put, w ith a small quantity of the 
 liquid, into a flask, which was furnished with 
 an excellent ground stopper. The flask was 
 agitated for a quarter of an hour. This me- 
 thod is difficult and requires much attention. 
 With respect to all the gases of which the 
 liquid absorbs more than l -7th of its bulk, 
 M. de Saussure proceeded in the following 
 manner: — He placed them over mercury, 
 in a tube fully 1^ inches internal diameter, 
 and let up a column of the absorbing liquid, 
 from about to 2j inches long. The ab- 
 sorption w r as promoted by agitation, and its 
 quantity was not determined till the gas and 
 the liquid had been in contact for several 
 days. 
 
 A hundred volumes of water absorb about 
 five volumes of atmospherical air, when the 
 mass of air is very great, in comparison of 
 that of the water. 
 
 “ From these experiments,” says M. de 
 Saussure, “ it appears, contrary to Dalton’s 
 assertion, that the absorption of gases, by 
 
 different liquids, not glutinous, as water and 
 alcohol, is very far from being similar. The 
 alcohol, as w r e see, often absorbs twice as 
 much of them, as the water does. In gases 
 which are absorbed in small quantities, this 
 difference is not so striking, because, with 
 respect to them, the absorptions of the alco- 
 hol can be less accurately determined, on 
 account of the air which still remains in it, 
 after being boiled. 
 
 “ These experiments agree no better with 
 the law which Dalton thinks he has ascertain- 
 ed in the absorption of different gases by one 
 and the same liquid ; for I And too great a dif- 
 ference between the quantity of carbonic acid, 
 sulphuretted hydrogen, and nitrous oxide 
 gases, absorbed by the same liquids (which 
 Dalton considers as completely equal), to be 
 able to ascribe it to errors in the experi- 
 ments.” 
 
 3. Of the influence of chemical affinity 
 on the absorption of the gases. 
 
 If such an influence did not exist, the 
 gases would be absorbed by all liquids in the 
 same order. Table of the volumes of gases 
 absorbed by 1 00 volumes of 
 
 Names of Naph. Oil of lav. Olive Solution 
 
 gases. sp. 
 
 gr. 0.784. sp 
 
 i. gr. 0.88. 
 
 oil. mur. pot. 
 
 Oletiant gas, 
 
 261 
 
 209* 
 
 122 
 
 10 
 
 Nitrous oxide, 
 
 254 
 
 275 
 
 150 
 
 21 
 
 Carbonic acid, 
 
 169 
 
 191 
 
 151 
 
 61 
 
 Carbo. oxide, 
 
 20 
 
 15.6 
 
 14.2 
 
 5.2 
 
 “ It follows, 
 
 ” says M. 
 
 de Saussure, “ 
 
 from 
 
GAS 
 
 GAS 
 
 these experiments, that in liquids, as well as 
 in solid bodies, great differences take place, 
 in the order in which gases are absorbed by 
 them, and that, in consequence, these ab- 
 sorptions are always owing to the influence 
 of chemical affinity. Solid bodies appear, 
 under the same circumstances, to produce a 
 greater condensation of all gases, in contact 
 with which they are placed, than liquid 
 bodies do. I have met with no liquid which 
 absorbs so great a volume of carbonic acid, 
 olefiant gas, azotic gas, carbonous oxide, and 
 nitrous oxide, as charcoal and meerschaum 
 do. The difference is probably owing to 
 this circumstance, that liquids, in consequence 
 of the great mobility of their parts, cannot 
 compress the gases so strongly as is neces- 
 sary for greater condensation, certain cases 
 excepted, when very powerful chemical af- 
 
 1 hough the influence of the viscidity of a 
 liquid be small with regard to the amount of 
 the absorption, yet it increases the time ne- 
 cessary for the condensation of the gas. In 
 general, the lightest liquids possess the great- 
 est power of absorbing gases ; with the ex- 
 ception of those cases where peculiar affini- 
 ties interfere. 
 
 Influence of the barometrical pressure 
 on the absorption of gases by liquids. 
 
 M. dc Saussure shews that in liquids the 
 quantities of gases absorbed are as the com- 
 pressions; while in solid bodies, on the con- 
 trary, as the gases become less dense, the 
 absorption seems to increase. Dr llcnry 
 had previously demonstrated, that the quan- 
 tity of carbonic acid taken up by water, is 
 
 Unities come to their assistance; as, for ex- 
 ample, the affinity of ammonia and muriatic 
 acid for water. Only in these rare cases do 
 liquids condense a greater quantity of gases 
 than solid bodies. According to Thomson, 
 water in the mean temperature of the atmos- 
 phere absorbs 516 times its bulk of muriatic 
 acid gas, and 780 times its bulk of ammo- 
 niacai gas.” In the articles muriatic acid 
 and ammonia in this Dictionary, I have shewn 
 these determinations of Dr Thomson to be 
 erroneous. 
 
 4. Influence of the viscidity, and the spe- 
 cific gravity of liquids on their absorption of 
 gases. Carbonic acid gas was placed in con- 
 tact with one volume of the different liquids. 
 The temperature in all the experiments was 
 62.5°. 
 
 proportional to the compressing force ; a 
 fact long ago well known and applied bv 
 Schweppe, Paul, and other manufacturers of 
 aerated alkaline waters. 
 
 6. Simultaneous absorption of several gases 
 by water. 
 
 M. de Saussure thinks it probable, that the 
 absorption of the different gases at the same 
 time by liquids, is analogous to what he ob- 
 served w’ith respect to solid bodies. Henry, 
 Dalton, Van Humboldt, and Gay Lussac, 
 had already remarked, that water saturated 
 witli one gas, allows a portion of that gas to 
 escape, as soon as it comes in contact with 
 another gas. “ It is indeed evident, accord- 
 ing to Dalton’s theory,” says M. de Saussure, 
 “ that two gases absorbed into a liquid, 
 
 Liquids 
 
 Sp. gr. 
 
 Volume of 
 car. acid gas 
 absorbed. 
 
 100 parts of the solution, contain 
 
 Alcohol, 
 
 0. 808 
 
 2.6 
 
 
 
 
 Sulph. ether, 
 
 0.727 
 
 2.17 
 
 
 
 
 Oil of lavender, 
 
 0.880 
 
 1.91 
 
 
 
 
 Oil of thyme, 
 
 0.890 
 
 1.88 
 
 
 
 
 Spirit of wine, 
 
 0.840 
 
 1.87 
 
 
 
 
 Rectified naphtha, 
 
 0.784 
 
 1.69 
 
 
 
 
 Oil of turpentine, 
 
 0.860 
 
 1.66 
 
 
 
 
 Linseed oil, 
 
 0.940 
 
 1.56 
 
 
 
 
 Olive oil, 
 
 0.915 
 
 1.51 
 
 
 
 
 Water, 
 
 1.000 
 
 1.06 
 
 
 
 
 Sal ammoniac, 
 
 1.078 
 
 0.75 
 
 27.53 
 
 crystals 
 
 sat. sol. 
 
 Gum arabic, 
 
 1.092 
 
 0.75 
 
 25. 
 
 gum, 
 
 
 Sugar, 
 
 1.104 
 
 0.72 
 
 25. 
 
 sugar, 
 
 
 Alum, 
 
 1.047 
 
 0. 70 
 
 9.14 
 
 cry. al. 
 
 sat, sol. 
 
 Sulphate of potash, 
 
 1.077 
 
 0.62 
 
 9.42 
 
 c. s. 
 
 sat. sol. 
 
 Muriate of potash, 
 
 1.168 
 
 0.61 
 
 26.0 
 
 c. s. 
 
 sat. sol. 
 
 Sulphate of soda, 
 
 1.105 
 
 0.58 
 
 11.14 
 
 dry salt, 
 
 sat. sol. 
 
 Nitre, 
 
 1.139 
 
 0.57 
 
 20.6 
 
 sat. sol. 
 
 Nitrate of soda, 
 
 1.206 
 
 0.45 
 
 26.4 
 
 
 sat. sol. 
 
 Sulphuric acid, 
 
 1.840 
 
 0.45 
 
 
 
 
 Tartaric acid, 
 
 1.285 
 
 0.41 
 
 55.37 
 
 c. acid. 
 
 sat. sol. 
 
 Common salt, 
 
 1.212 
 
 0.529 
 
 29. 
 
 s. sat. sol. 
 
 Muriate of lime, 
 
 1.402 
 
 0.261 
 
 40.2 
 
 ignited 
 
 salt, sat. sol. 
 
GAS 
 
 GAS 
 
 should really occupy always the same room, 
 as they would occupy, if each of them had 
 been absorbed singly, at the degree of den- 
 sity which it has in the mixture.” To ob- 
 tain results on this subject, approaching to 
 accuracy, he was obliged to make mixtures, 
 of carbonic acid with oxygen, hydrogen, and 
 azotic gases ; for the last three gases are ab- 
 sorbed by water, in so small a proportion, 
 that the different condensations which take 
 place, cannot be confounded with errors in 
 the experiments. 
 
 1. Water and a mixture of equal measures 
 of carbonic acid and hydrogen gas. 
 
 He brought 100 measures of water, at the 
 temperature of 62^°, in contact with 434 
 measures of equal volumes of carbonic acid 
 and hydrogen. The absorption amounted 
 to 47.5 volumes, of which 44 were carbonic 
 acid, and 3.5 hydrogen. If we compare the 
 space which the absorbed gases occupy in 
 the water, with that which they would occu- 
 py, according to the preceding table of ab- 
 sorption of unmixed gases, we find that the 
 presence of one of the gases has favoured 
 the absorption of the other, as far as the re- 
 lative space goes, wdiich each would occupy 
 separately in the water. 
 
 2. Water and a mixture of equal parts of 
 carbonic acid, and oxygen gas. 
 
 100 volumes of water at 62^° absorbed 
 from 390 volumes of this mixture 52.1 vo- 
 lumes, of which 47.1 volumes were carbonic 
 acid, and 5 volumes oxygen gas. Here also 
 the condensation is greater than when the 
 gases are separate. 
 
 3. Water and a mixture of carbonic acid 
 gas and azote. 
 
 100 volumes of w r ater absorbed from 357.6 
 volumes of this mixture, at the above tem- 
 perature, 47.2 volumes, of which 43.9 vo- 
 lumes were carbonic acid, and 3.3 azote. 
 
 The results of these experiments, as we 
 perceive, agree completely with each other ; 
 but none of them corresponds with Dalton’s 
 theory, according to which, the volume of 
 carbonic acid absorbed, should be just one- 
 half of that of the absorbing liquid ; and 
 likewise the volumes of the other gases ab- 
 sorbed should be much smaller than M. de 
 Saussure found them actually to be. A 
 mixture of oxygen and hydrogen gases, in 
 the proportions for forming water, by agita- 
 tion with that liquid, were absorbed in the 
 proportion of 5^ volumes to 100 volumes of 
 the liquid. In an appendix, M. de Saussure 
 describes minutely the judicious precautions 
 he took to insure precision of result; which 
 leave little doubt of the accuracy of his ex- 
 periments, and the justness of his conclusions. 
 They are as fatal to Mr Dalton’s mechanical 
 fictions concerning the relation ol liquids 
 and gases, as MM. Dulong and Petit’s re- 
 cent researches have been to his geometrical 
 fictions on the phenomena of heat. 
 
 III. Of Gaseous Analysis. 
 
 This department of chemistry, whose great 
 importance was first shewn by Cavendish, 
 Priestley, and Berthollet, has lately acquired 
 new value in consequence of M. G. Lussac’s 
 doctrine of volumes, his determination of the 
 specific gravities of vapours, and sagacious 
 application of both principles, to the deve- 
 lopement of many combinations hitherto in- 
 tricate and inexplicable. 
 
 Let us first take a general view of the 
 characters of the different gases. Some of 
 them are coloured, others diffuse white va- 
 pours in the air; some relume a taper, pro- 
 vided a point of its wick remains ignited ; 
 others are acid and redden tincture of lit- 
 mus; one set have no smell, or but a faint 
 one ; a second set are very soluble in water; a 
 third are soluble in alkaline solutions; and a 
 fourth are themselves alkaline. Some gases 
 possess several of these characters at once. 
 
 1. The coloured gases are nitrous acid, chlo- 
 rine, the protoxide and dcutoxide of chlorine. 
 The first is red, the rest yellowish-green, or 
 yellowish. 
 
 2. Gases producing white vapours in the air. 
 Muriatic acid, fluoboric, fluosilicic, and hy- 
 driodic. 
 
 3. Gases inflammable in air by contact of 
 the lighted taper. Hydrogen, subcarburetted 
 and carburctted hydrogen, subphosphuretted 
 and phosphuretted hydrogen, sulphuretted 
 hydrogen, arsenuretted hydrogen, tellurctted 
 hydrogen, potassurotted hydrogen, carbonous 
 oxide, prussine or cyanogen. 
 
 4. Gases which rekindle the expiring taper. 
 Oxygen, protoxide of azote, nitrous acid, and 
 the oxides of chlorine. 
 
 5. Acid gases, which redden litmus. Ni- 
 trous, sulphurous, muriatic, fluoboric, bydrio- 
 dic, fluosilicic, chlorocarbonous, and carbonic 
 acid ; the oxides of chlorine, sulphuretted 
 hydrogen, telluretted hydrogen, and prus- 
 sine. 
 
 6. Gases destitute of smell, or possessing but 
 a feeble one. Oxygen, azote, hydrogen, 
 subcarburetted and carburctted hydrogen, 
 carbonic acid, protoxide of azote. 
 
 7. The smell of all the others is insupport- 
 able, and frequently characteristic. 
 
 8. Gases very soluble in water, namely, of 
 which water dissolves more than 30 times its 
 volume, at ordinary pressure and tempera- 
 ture. Fluoric acid, muriatic, fluosilicic, ni- 
 trous, sulphurous, and ammonia. 
 
 9. Gases soluble in alkaline solutions. Acids, 
 nitrous, sulphurous, muriatic, fluoboric, hv- 
 driodic, fluosilicic, chlorine, carbonic, chio- 
 rocarbonous ; and the two oxides of chlorine, 
 sulphuretted hydrogen, telluretted hydrogen, 
 and ammonia. 
 
 10. Alkaline gases. Ammonia and potas- 
 suretted hydrogen. 
 
 Such is a general outline of the charac- 
 teristics of the gaset. The great problem 
 
GAS 
 
 GAS 
 
 which new presents itself is, to determine by 
 experiments the nature of any single gas, or 
 gaseous mixture , which may come before us . 
 
 X • 
 
 We first fill a little glass tube with it, 
 and expose it to the action ot a lighted taper. 
 If it inflames, it is one of the 1 1 above enu- 
 merated, and must be discriminated by the 
 following methods. 
 
 1. If it takes fire spontaneously on con- 
 tact with air, producing a very acid matter, 
 it is phosphuretted hydrogen. Subphosphu- 
 retted hydrogen, or the bihydroguret ot phos- 
 phorus, does not spontaneously inflame. 
 
 2. If water be capable of decomposing it, 
 and transforming it suddenly into hydrogen 
 gas and alkali, which we can easily ascertain 
 by transferring the test tube filled with it, 
 from the mercurial trough, to a glass con- 
 taining water, it is potassuretted hydrogen. 
 I found in my experiments on the produc- 
 tion of potassium, by passing pure potash 
 over ignited iron turnings, ot which some 
 account was published in 1809, that potas- 
 suretted hydrogen spontaneously inflamed. 
 M. Sementini has made the same observa- 
 tion. 
 
 S. If it has a nauseous odour, is insoluble 
 in water, leaves on the sides of the test tube 
 in which we burn it, a chesnut brown depo- 
 site, like hydruret of arsenic, and if, after 
 agitation with the quarter of its volume of 
 aqueous chlorine, a liquid is formed, from 
 which sulphuretted hydrogen precipitates 
 yellow flocculi, it is arsenuretted hydrogen 
 gas. 
 
 4. If it has a strong smell of garlic or 
 phosphorus, if it does not inflame spontane- 
 ously, if the product of its combustion strong- 
 ly reddens litmus, and if, on agitation with 
 an excess of aqueous chlorine, a liquor re- 
 sults, which, after evaporation, leaves a very 
 sour syrupy residuum, it is subphosphuretted 
 hydrogen. 
 
 5. If it has no smell or but a faint one, 
 and if it be capable of condensing one-half 
 its volume of oxygen in the explosive eudi- 
 ometer, it is hydrogen. 
 
 6. If it has a faint smell, be capable of 
 condensing in the explosive eudiometer one- 
 half of its volume of oxygen, and of produc- 
 ing a volume of carbonic acid equal to its 
 own, which is ascertained by absorbing it 
 with aqueous potash, it is carbonous oxide. 
 
 7. If it has a faint smell, if one of the 
 products of combustion is carbonic acid, and 
 if the quantity of oxygen which it condenses 
 by the explosive eudiometer, corresponds to 
 twice or thrice its volume, then it is either 
 subc.arburelted or carburetted hydrogen. 
 
 8. If it diffuses the odour of rotten eggs, 
 if it blackens solutions of lead, if it leaves a 
 deposite of sulphur when we burn it, in the 
 test tube, and if it be absorbable by potash, 
 it is sulphuretted hydrogen . 
 
 9. If it has a fetid odour, approaching to 
 that of sulphuretted hydrogen, if it is ab- 
 sorbable by potash, if it is soluble in water, 
 if it forms with it a liquid which, on exposure 
 to air, lets fall a brown pulverulent hydruret 
 of tellurium; and lastly, if on agitation with 
 an excess of aqueous chlorine, there results a 
 muriate of tellurium, yielding a white preci- 
 pitate with alkalis, and a black with the by- 
 drosulphurets, it is teliuretted hydrogen. 
 
 10. Prussine is known by its offensive and 
 very peculiar smell, and its burning with a 
 purple flame. 
 
 II. 
 
 If the gas be non-inflammable, but ab- 
 sorbable by an alkaline solution, it will be 
 one of the 13 following : muriatic acid, fluo- 
 boric, fluosilicic, hydriodic, sulphurous, ni- 
 trous, chlorocarbonous, carbonic ; or chlorine, 
 the oxides of chlorine, prussine, or ammonia. 
 The first four, being the only gases which 
 produce white vapours with atmospheric air, 
 from their strong affinity for w r ater, are thus 
 easily distinguishable from all others. The 
 fuosilicic gas is recognized by the sepa- 
 ration of silica, in w'hite flocculi, by means 
 of water; and hydriodic gas, because chlorine 
 renders it violet, with the precipitation of 
 iodine. 
 
 Muriatic acid gas, from its forming with 
 solution of silver a w hite precipitate insoluble 
 in acids, but very soluble in ammonia, and 
 from its yielding with oxide of manganese a 
 portion of chlorine. Fluoboric gas , by the 
 very dense vapours wdiich it exhales, and by 
 its instantly blackening paper plunged into 
 it. Nitrous acid gas is distinguished by its 
 red colour. Protoxide of chlorine, because it 
 is of a lively greenish-yellow hue, because it 
 exercises no action on mercury at ordinary 
 temperatures, and because, on bringing ignit- 
 ed iron or glass in contact with it, it is de- 
 composed with explosion into oxygen and 
 chlorine. 
 
 Deutoxide of chlorine is of a still brighter 
 yellowish-green than the preceding*, and has 
 a peculiar aromatic smell. It does not red- 
 den, but blanches vegetable blues. At 212° 
 it explodes, evolving oxygen and chlorine.. 
 Chlorine is distinguished by its fainter yel- 
 lowish-green colour, by its suffering no change 
 on being heated, by its destroying colours, 
 and by its rapid combination with mercury at 
 common temperatures. Sulphurous acid by 
 its smell of burning sulphur. Ammonia b y 
 its odour, alkaline properties, and the dense 
 w hite vapoursit forms with gaseousacids. Chlo- 
 rocarbonous gas is converted by a very small 
 quantity of water into aqueous muriatic acid, 
 and carbonic acid, which rests above. Zinc or 
 antimony, aided by heat, resolves it into carbo- 
 nous oxide gas, while a solid metallic chloride 
 is formed. With the oxides of the same 
 metals, it forms chlorides, and carbonic 
 acid, while in each case the quantity of ga- 
 
GAS 
 
 GAS 
 
 seous oxide of carbon, and carbonic acid dis- 
 equal to the volume of chloro- 
 carbonous gas operated on. Carbonic acid 
 gas is colourless, and void of smell, while all 
 the othei gases absorbable by the alkalis have 
 a strong odour. It hardly reddens even 
 \eiy dilute tincture of litmus; it gives a 
 white cloud with lime water, from which a 
 precipitate falls, soluble with effervescence in 
 vinegar. 
 
 III. 
 
 If, finally, the gas be neither inflammable 
 nor capable of being absorbed by a solution 
 of potash, it will be oxygen, azote, protoxide 
 ot azote, or deutoxide o! azote. Oxygen can 
 be mistaken only for the protoxide of azote. 
 The property it possesses of rekindling the 
 expiring wick of a taper, distinguishes it 
 from the two other gases. They are more- 
 over characterized, 1st, Because oxygen is 
 void of taste, and capable of condensing in the 
 explosive eudiometer, twice its volume of hy- 
 drogen gas ; th q protoxide oj' azote because it 
 has a sweet taste, is soluble in a little less than 
 half its volume of cold water, and because 
 when detonated with its own volume of hy- 
 drogen, we obtain a residuum, containing 
 much azote. The two other gases are dis- 
 tinguished thus : Deutoxide of' azote is co- 
 lourless, and when placed in contact with 
 atmospherical air or oxygen, it becomes red, 
 passing to the state of nitrous acid vapour. 
 Azote is void of colour, smell, and taste, 
 extinguishes combustibles, experiences no 
 change on contact with air, and produces no 
 cloud with lime water. 
 
 Under the different gases, the reader will 
 find their discriminating characters minutely 
 detailed. We shall conclude this article with 
 a method of solving readily an intricate and 
 common problem in gaseous analysis, for 
 which no direct problem has I believe been 
 yet offered. Allusion has been made to it 
 in treating of coal gas, and the plan pointed 
 out in a popular way. 
 
 Analytical problem . — In a mixture consti- 
 tuted like purified coal gas, of three inflam- 
 mable gases, such as olefiant gas, carburetted 
 hydrogen, and carbonous oxide, inseparable 
 by ordinary chemical means, to determine 
 directly the quantity of each. 
 
 1. By the rule given at the commence- 
 ment of the present article gas, find from the 
 specific gravity of the mixed gases the pro- 
 portion of the light carburetted hydrogen. 
 The remainder is the bulk of the other two 
 gases. Detonate 100 measures of the mixed 
 gas with excess of oxygen in an explosive 
 eudiometer. Observe the change of volume, 
 and ascertain the expenditure of oxygen. 
 Of the oxygen consumed, allow two volumes 
 for every volume of light carburetted hydro- 
 gen, sp. gr. 0.555, previously found, by the 
 hydrostatic rule, to be present. The remain- 
 ing volumes of oxygen have gone to the 
 
 combustion of heavy carburetted hydrogen, 
 or olefiant gas and carbonous oxide. Then, 
 
 Let m = measure of oxygen equivalent 
 to 1 of first gas, 
 
 n = do. do. to 1 of second gas, 
 p = measures of oxygen actually 
 consumed, 
 
 100 or s = volume of mixture of these two 
 gases, 
 
 x = volume of first gas, 
 
 s x =3 volume of second gas, 
 
 p — ns 
 x — 1 . 
 
 m — n 
 Examples. 
 
 1 st, 100 measures of purified coal gas, 
 were found, by the hydrostatic problem, to 
 contain 76 of subcarburetted hydrogen ; and 
 exploded in the eudiometer, they were found 
 to consume 187 cubic inches of oxygen. By 
 condensing with potash the carbonic acid form- 
 ed, we learn the volume of residuary oxygen. 
 But the solution of the problem is otherwise 
 independent of the quantity of carbonic acid, 
 generated in the present experiment. We see 
 from the table of the gases, that 1 volume of 
 olefiant gas is equivalent to 5 of oxygen ; 
 and 1 volume carbonous oxide, to one-half 
 volume oxygen. Therefore, deducting for 
 the 76 of subcarbonate, 152 measures of oxy- 
 gen, the remaining 5 5 have gone to the 24 
 measures of the two denser gases. Hence 
 
 Olefiant gas, or x = 35 ^ — 9- 2, 
 
 2.5 
 
 And 24 — 9.2 = 14.8 = the carbonous 
 oxide. 
 
 2 d, 100 measures of a mixture of olefiant 
 gas, and carbonous oxide, take 236 of oxy- 
 gen : What is the proportion of olefiant gas? 
 
 (0.5 X 100) 
 
 x or olefiant = 256 — v — = 74.4, 
 
 2.5 
 
 consequently 25.6 are carbonous oxide. 
 
 This problem is applicable to every mix- 
 ture of two inflammable gases. The hydro- 
 static problem I have been accustomed for 
 years to apply to mixtures of two gases, 
 whose specific gravities are considerably dif- 
 ferent, as carbonic acid and atmospheric air, 
 and with a delicate balance, and globe con- 
 taining 100 cubic inches, it gives a good ac- 
 cordance with chemical experiment. 
 
 I employed this method for verification, in 
 examining the air extracted from the lungs 
 of the criminal’s dead body, galvanized at 
 Glasgow in Nov. 1818. 
 
 Generally, if we wish to get an approximate 
 knowledge of the proportion of two gases in a 
 mixture, we may adopt the following plan. 
 Poise the exhausted globe or flask, at one 
 arm of a delicate balance. Then, connect 
 its stop- cock w ith the gasometer, bladder, or 
 jar, containing the gaseous mixture. Intro- 
 duce an unmeasured quantity, great or small, 
 relative to the capacity of the globe ; for it is 
 
GAS 
 
 GAS 
 
 not necessary that the density of the air in the 
 globe should be equal to that of the atmos- 
 phere. In fact, it may happen, that the 
 whole quantity of the gaseous mixture may 
 not be equal to more than one-third, one- 
 half, or three- fourths of the capacity of the 
 globe. For instance, in the case ot the cri- 
 minal, I took a globe, capable of receiving 
 greatly more than the aerial contents of his 
 lungs. An unknown quantity of the mixed 
 gases being now in the globe, we suspend it 
 at the balance, and note the increase of 
 weight. We then open the stop-cock, and 
 allow the atmosphere to enter, till an equili- 
 brium of pressure ensues. The additional 
 weight occasioned by the atmospheric air, 
 must be converted into bulk, at the rate of 
 30. 5 1 9 gr. for 1 00 cubic inches. Deducting 
 this bulk from the known capacity of our globe 
 or flask, leaves a remainder, which is the vo- 
 lume of the gaseous mixture first introduced ; 
 knowing its weight and volume, we infer its 
 specific gravity ; and from its specific gravity, 
 by the hydrostatic problem, we deduce the 
 proportion of each gas in the mixture. 
 
 IV. Of the method of determining the 
 specific gravity of gases, and of the modifi- 
 cation of their volume from variation of 
 pressure and temperature. — The specific 
 gravity of a gas is the weight of a certain 
 volume of it, compared to the same volume 
 of air or water. Air is now assumed as the 
 standard for gases, as water is for liquids ; 
 and the same hydrostatic method is appli- 
 cable to both elastic and inelastic fluids. 
 We determine the specific gravity of a gas, 
 with an air-pump, balance, and globe or flask, 
 having a stop-cock attached to its orifice. 
 We proceed thus: — Wo poise the globe at 
 the end of a balance, with its stop- cock 
 open : we next exhaust it, and weigh it in 
 that state. The difference of the two weigh- 
 ings is the apparent weight of the volume of 
 atmospheric air withdrawn from it. We 
 verify that first estimate, by opening the 
 stop-cock, and noting the increase of weight 
 occasioned by the ingress of the air. Hav- 
 ing again exhausted, exactly to the same de- 
 gree, by the mercurial gauge, as before, 
 we poise. This gives us for the third time, 
 the weight of air contained by the globe. 
 The mean of the three trials is to be taken. 
 We now attach it, by the screw of the stop- 
 cock, to a gasometer or jar, containing gas 
 desiccated by muriate of lime over mercury, 
 and opening the communication, allow the 
 air to enter till an equilibrium of pressure 
 with the atmosphere is established. In this 
 stage of the operation, we must avoid grasp- 
 ing the globe with our hands, and we must 
 see that the mercury in the inside and out- 
 side of the jar stands truly on a level. On 
 re- suspending the globe at the balance, we 
 find the weight of the included gas, which 
 being divided by the weight of the air for- 
 
 merly determined, gives a quotient, which is 
 the specific gravity of the gas in question. 
 When the utmost precision is required, we 
 should again exhaust the globe, again poise 
 it, and filling it with the gas, again ascertain 
 its sp. gravity under the bulk of the globe. 
 Even a third repetition is sometimes neces- 
 sary to secure final accuracy. We should 
 always terminate the operations, by a new 
 weighing of the atmospheric air, lest its 
 temperature or pressure may have changed 
 during the course of the experiments. It is 
 obvious, that this method differs in no re- 
 spect from that practised long ago by the 
 Hon. Robert Boyle, and by Sir Charles 
 Blagden, (See Alcohol), with liquids, and 
 is that which, I suppose, every public tea- 
 cher of physics, like myself, explains and 
 exhibits annually to his pupils. With re- 
 gard to liquids, it is necessary to bring them 
 to a standard temperature, which in this 
 country is 60° F. But, as the comparison 
 of gases with air, is always made at the in- 
 stant, our only care need be, that the gas 
 and atmosphere are in the same state as to 
 temperature and moisture, and that the 
 equilibrium of pressure be insured to the 
 gas, by bringing the liquid which confines 
 it to a level, on the inside and outside of the 
 jar. 
 
 If the gases stand over water, it is desira- 
 ble to weigh them in somewhat cold weather, 
 when the thermometer is, for example, at 
 40° ; for then, the quantity of aqueous va- 
 pour they contain is exceedingly small. Or 
 otherwise, we should place the atmospheric 
 air we use for the standard of comparison 
 in the very same circumstances, over water, 
 at 60° for instance ; and then with regard to 
 those gases whose density differs little from 
 that of the atmosphere, no correction for va- 
 pour need be considered. 
 
 From the experiments of M. de Saussure, 
 and those of MM. Clement and Desormes, 
 we learn that the same bulk of different 
 gases standing over water gives out, on being 
 transmitted over dry muriate of lime, the 
 same quantity of that liquid; which, for 100 
 cubic inches, is, by the first philosopher, 
 0.35 of a grain troy at 5 7° F., and by the 
 second, 0.1256 at 54°. We shall, perhaps, 
 not err, by considering the weight to be one- 
 third of a grain at 60°. Now, for 100 cu- 
 bic inches of hydrogen, which in the dry 
 state weigh only 2.1 18, one-third of a grain 
 is nearly one-seventh of the whole, equiva- 
 lent to 14 cubic inches of dry gas. But for 
 oxygen, of which 100 cubic inches weigh 
 nearly 34 grains, onc-third of a grain forms 
 only one 1 10th of the whole. 
 
 The quantity of moisture, present in air 
 or gas, at any temperature, may indeed be 
 directly determined from my tablo of the 
 elasticity of aqujous vapour. If we multi- 
 ply 19, which is the weight in grains of 100 
 
GAS 
 
 GAS 
 
 cubic inches of steam at 212°, by the num- 
 ber 0.515 opposite 60° in my table, we shall 
 have a product, which, divided by SO, will 
 give a quotient, = the weight of aqueous 
 vapour in 100 inches of any gas standing 
 over water at the given temperature. Thus 
 
 19 x 0.516 i • u • i 
 
 j () = 0.327, which is very nearly 
 
 0.33, as stated above. See infra. 
 
 The above plan of taking the specific 
 gravity of gases, I believe to be the best, as 
 it was the earliest. Having publicly prac- 
 tised and taught it for 17 years, unconscious 
 of the slightest merit, I was not a little 
 amused at perceiving this old hydrostatic 
 method recently claimed as a new discovery 
 or invention. 
 
 We have seen, in treating of caloric, that 
 all gaseous matter changes its volume by 
 one 480th part, for the variation of 1° of 
 Fahrenheit’s thermometer. This quantity 
 is in decimals = 0-0020833. Hence, if 
 we assume the volume to be equal to unity 
 at 50°, and successively add or subtract that 
 decimal quantity, for every thermometric de- 
 gree above or below that temperature, we 
 shall have the following table of reduction : — 
 
 TABLE of Reduction on Gaseous Volumes, 
 
 for Variations of Temperature above or 
 
 below 60°, by Dr Uke. 
 
 Temp. 
 
 Volume. 
 
 Temp. 
 
 Volume. 
 
 60° 
 
 1.000000 
 
 59° 
 
 1.002083 
 
 61 
 
 0.997916 
 
 58 
 
 1.004166 
 
 62 
 
 0.995833 
 
 57 
 
 1.006249 
 
 63 
 
 0.993750 
 
 56 
 
 1.008333 
 
 64 
 
 0.991666 
 
 55 
 
 1.010416 
 
 65 
 
 0.989583 
 
 54 
 
 1.012499 
 
 66 
 
 0.987500 
 
 53 
 
 1.014583 
 
 67 
 
 0.985416 
 
 52 
 
 1.016666 
 
 68 
 
 0.983333 
 
 51 
 
 1.018749 
 
 69 
 
 0.981250 
 
 50 
 
 1.020833 
 
 70 
 
 0.979166 
 
 49 
 
 1.022916 
 
 71 
 
 0.977083 
 
 48 
 
 1.024999 
 
 72 
 
 0.975000 
 
 47 
 
 1.027083 
 
 73 
 
 0.972916 
 
 46 
 
 1.029166 
 
 74 
 
 0.970833 
 
 45 
 
 1.031249 
 
 75 
 
 0.968750 
 
 44 
 
 1.033333 
 
 76 
 
 0.9 66666 
 
 43 
 
 1.035416 
 
 77 
 
 0.961583 
 
 42 
 
 1.037499 
 
 78 
 
 0.962500 
 
 41 
 
 1.039583 
 
 79 
 
 0.960416 
 
 40 
 
 1.041666 
 
 SO 
 
 6.958333 
 
 39 
 
 1.043749 
 
 81 
 
 0.956250 
 
 38 
 
 1.045833 
 
 82 
 
 0.954166 
 
 37 
 
 1.047916 
 
 83 
 
 0.952083 
 
 36 
 
 1.049999 
 
 84 
 
 0.950000 
 
 35 
 
 1.052083 
 
 85 
 
 0.947916 
 
 34 
 
 1.054166 
 
 86 
 
 0.945833 
 
 33 
 
 1.056249 
 
 87 
 
 0.943750 
 
 32 
 
 1.058333 
 
 88 
 
 0.941666 
 
 31 
 
 1.060416 
 
 89 
 
 0.939583 
 
 SO 
 
 1.062499 
 
 90 
 
 0.937500 
 
 29 
 
 1.064583 
 
 91 
 
 0.935416 
 
 28 
 
 1 .066666 
 
 Temp. 
 
 Voliime. 
 
 Temp. 
 
 Volume. 
 
 92° 
 
 0.933333 
 
 27° 
 
 1.068749 
 
 93 
 
 0.931250 
 
 26 
 
 1.070833 
 
 94 
 
 0.929166 
 
 25 
 
 1.072916 
 
 95 
 
 0.927083 
 
 24 
 
 1.074999 
 
 96 
 
 0.925000 
 
 23 
 
 1.077083 
 
 97 
 
 0.922916 
 
 22 
 
 1.079166 
 
 98 
 
 0.920833 
 
 21 
 
 1.081249 
 
 99 
 
 0.918750 
 
 20 
 
 1.083333 
 
 100 
 
 0.916666 
 
 
 
 Use of the above Table. 
 
 Opposite the temperature of the gas, we 
 find a number, which being multiplied into 
 the volume of the gas, however expressed, 
 gives the true volume at 60°. The table 
 printed in some books, in which unity is 
 placed at 32°, and 1.375 at 212°, can be 
 regarded merely as a specimen of multipli- 
 cation. In practical chemistry, we seldom 
 think of reducing experimental volumes to 
 the standard of 32° F. 
 
 The bulk of a gas being inversely as the 
 pressure, it will necessarily increase as the 
 barometer falls , and decrease as it rises* 
 Hence, to reduce the volume of a gas at 
 any pressure, to what it would be under 
 the mean pressure of 30 inches of mer- 
 cury ; multiply the volume by the parti- 
 cular barometrical pressure, and divide the 
 product by SO ; the quotient is the true 
 volume. If the gas be contained in a 
 vessel over mercury, so that the liquid me- 
 tal stands in the inside of the tube higher 
 than on the outside, it is evident that the 
 gas will be compressed by a less weight 
 than the ambient atmosphere, in proportion 
 to the difference of the mercurial levels. If 
 that difference were 10 inches, then one- 
 third of the incumbent pressure would be 
 counterbalanced, and the gas would become 
 bulkier by one-third. Hence, we must sub- 
 tract this difference of mercurial levels, from 
 the barometric altitude at the instant, and 
 use this reduced number or remainder, as 
 the proper multiplier in the above rule. In- 
 stead of reducing the volume of a gas to 
 what it would be under a mean pressure of 
 SO inches, it is often desirable to reduce it 
 to another barometrical height, which exist- 
 ed perhaps at the commencement of the ex- 
 perimental investigation. Thus, in applying 
 the eudiometer by slow combustion of phos- 
 phorus, we must wait for 24 hours, till the 
 experiment be finished. But in that pe- 
 riod, and in our fickle climate, the mercury 
 of the barometer may have moved an inch 
 or more. The general principle, that the 
 volume is inversely as the pressure, measur- 
 ed by the length of the mercurial column, 
 affords the following simple rule: — Multi- 
 ply the bulk of the gas by the existing 
 height of the barometer, and divide the pro- 
 duct by the original height, the quotient is 
 the height at the commencement of the ex- 
 periment. The barometric pressure is esti- 
 
GAS 
 
 GAS 
 
 mated by the inches on its scale, minus the 
 difference of mercurial levels in the pneu- 
 matic apparatus. By bringing the two sur- 
 faces to one horizontal plane, this correction 
 vanishes. The facility of doing so with my 
 eudiometer, is one of its chief advantages. 
 
 If we are operating in the water pneu- 
 matic cistern, we can in general bring the 
 two surfaces to a level. If not, we must 
 allow' one inch of mercurial pressure for 
 15.6 inches of water; and, of course, l-10th 
 of a barometrical inch, for every inch and 
 third of water. 
 
 M. Gay Lussac contrived a very ingeni- 
 ous apparatus, to determine the change of 
 volume, which an absolutely dry gas under- 
 goes, when water is admitted to it, in mi- 
 nutely successive portions, till it (or the 
 space it occupies) becomes saturated. He 
 deduced from these accurate experiments, the 
 following formula, whose results coincide 
 perfectly with those deducible from Mr 
 Dalton’s and my experiments on the elastic 
 force of aqueous vapour. 
 
 When a perfectly dry gas is admitted to 
 moisture, its volume, v , augments, and be- 
 v p 
 
 comes ■ — ; in which p — the barome- 
 
 . V —f \ 2 
 
 trie altitude, in inches, and f *= the elastic 
 force of steam at the given temperature. 
 Hence, 100 cubic inches of dry air, weigh- 
 ing 30.519 grains, become 101.75, when 
 transferred over water at 60°. Therefore, 
 100 cubic inches of such aeriform matter, 
 standing in a jar on the hydro-pneumatic 
 trough, must consist of, 
 
 98.28 cubic inches dry air = 29.99 gr. 
 
 1.72 aqueous vapour = 0.327 gr. 
 
 Weight of 100 cubic inches of 
 air, over water at 60° 
 
 For hydrogen we shall have, 
 98.28 inches dry gas - : 
 1.72 aqueous vapour 
 
 = 50.517 
 
 = 2.08157 
 = 0.32680 
 
 Weight of 1 00 cu. in. moist gas = 2.40857 
 Hence its sp. gr. compared to that of dry 
 2.40837 
 
 air, will be = 
 
 30.519 
 
 0.07891, and com- 
 
 , . . 2.40837 
 
 pared to moist air = — - - = 0.07944. 
 
 1 or chlorine we shall have (making the sp. 
 gr. of the dry gas = 2.5), 
 
 98.28 cubic inches - = 74.9857 
 
 1.72 aqueous vapour - = 0.3268 
 
 Weight of 100 cu. in. of moist chi. == 75.5125 
 Hence, its sp. gr. compared to that of dry 
 
 air, will be = = 2.4677, and com- 
 
 »>U. 519 
 
 spared to moist air = — ■ ^ ^ — 2 48416 
 
 30.317 * 
 
 . N°' v > tlie first is almost the density as- 
 signed long ago by MM. Gay Lussac and 
 
 2 
 
 Thenard ; on which, if we make the correc- 
 tion for aqueous vapour present in it, on ac- 
 count of this gas never being collected over 
 mercury, we shall have its true specific grav. 
 = 2.5. Sir H. Davy brought out a num- 
 ber still nearer 2.5, than that of M. Gay 
 Lussac. His chlorine was probably com- 
 pared with air somewhat moist, and may 
 therefore be considered as readily reducible, 
 by a minute correction, to 2.5. The reason 
 assigned by Dr Thomson (Annals for Sept, 
 and Oct. 1820,) for the former erroneous 
 estimates of the sp. gravity of that gas, can- 
 not surely apply to the two first chemists of 
 the age ; namely, that the chlorine they pre- 
 pared as the standard of comparison, was 
 impure. I think the true reason is that, 
 which I have now given. 
 
 For olefiant and carbonic oxide gases, we 
 shall have, 
 
 98.28 cubic inches - = 29.1564 
 
 1.72 vapour - - =- 0.3268 
 
 Weight of 1 00 cub. in. of moist gas = 29*4832 
 Hence, its sp. gr. compared to that of dry 
 29.4832 
 
 air, will be = ~ ■■■ -— == 0.966, and to 
 
 moist air 
 
 30.519 
 29.4832 
 
 30.517 
 
 = 0.972 5. 
 
 G 
 
 Dr Thomson appears to have collected 
 his chlorine, olefiant gas, and carbonic oxide, 
 over water. Hence, his late results on them, 
 if at 60° F. are erroneous ; and instead of 
 confirming the theoretical numbers deducible 
 from Higgins’s atomic doctrine, and M. Gay 
 Lussac’s theory of volumes, they are incon- 
 sistent with both. One might suppose that 
 he had prepared his apparatus for measuring 
 gaseous specific gravity, in the workshop of 
 Procrustes. But far be it from me, to retort 
 on him, the insinuation which he throws out 
 against M. Thenard in his System of Che- 
 mistry, vol. iv. p. 385. : “ This result ap- 
 proaches so nearly that of Lavoisier (Prout), 
 that there is reason to suspect that the coin- 
 cidence is more than accidental.” In fact, 
 Dr Thomson’s present experiments in the 
 above case, would prove a great deal too much. 
 Kvery result indeed which he sets down in 
 the above two journals, is logically deducible 
 from pre-existing facts, and in my appre- 
 hension, does not add an iota to the strength 
 of their former evidence. There are many 
 niceties to be observed, before we can obtain, 
 by experiment , the exact densities of gaseous 
 matter. On this subject the reader may 
 consult, with much advantage, Biot’s Trciite 
 dc Physique, vol. 1st, where geometry and 
 experiment go hand in hand, notwithstand- 
 ing Dr Thomson’s condemnation of it, in 
 the following words : “ Indeed, to be con- 
 vinced of the little utility of mere mathema- 
 tical formulas, towards promoting this sci- 
 ence without the aid of experiment, the 
 
GEL 
 
 GEO 
 
 reader has only to peruse the chemical part 
 of Biot’s Traite de Physique, where he will 
 find abundance of specimens of most elabo- 
 rate mathematical investigations, which leave 
 every subject precisely in the state in which 
 they found it.” Annals of Phil, for Sept. 
 1820. Let me recommend to the doctor, 
 Biot’s chapter on the sp. gr. of gases, and 
 not to vilify a book, by the unacknowledged 
 aid of which, he has given an air of original 
 research to his article Decomposition, in the 
 Supplement to the Enc. Brit. 5th edit.* 
 
 Gastric Juice, is separated by glands 
 placed between the membranes which line 
 the stomach ; and from these it is emitted 
 into the stomach itself. 
 
 From various experiments it follows : 
 
 1. That the gastric juice reduces the ali- 
 ments into a uniform magma, even out of 
 the body, and in vitro ; and that it acts in 
 the same manner on the stomach after death ; 
 which proves that its effect is chemical, and 
 almost independent of vitality. 2. That the 
 gastric juice effects the solution of the ali- 
 ments included in tubes of metal, and con- 
 sequently defended from any trituration. 3. 
 That though there is no trituration in mem- 
 branous stomachs, this action powerfully as- 
 sists the effect of the digestive juices in ani- 
 mals with a muscular stomach, such as ducks, 
 geese, pigeons, &c. Some of these animals, 
 bred up with sufficient care that they might 
 not swallow stones, have nevertheless broken 
 spheres and tubes of metal, blunted lancets, 
 and rounded pieces of glass, which were in- 
 troduced into their stomachs. Spallanzani 
 has ascertained, that flesh, included in 
 spheres sufficiently strong to resist the mus- 
 cular action, was completely digested. 4. 
 That gastric juice acts by its solvent power, 
 and not as a ferment; because the ordinary 
 and natural digestion is attended with no 
 disengagement of air, or inflation, or heat, 
 or, in a word, with any other of the pheno- 
 mena of fermentation. 
 
 * Gehlenite. A mineral substance, al- 
 lied to Vesuvian. Its colours are olive- 
 green, leek-green, green of other shades, and 
 brow n. It occurs crystallized in rectangu- 
 lar four-sided prisms, which are so short as 
 to appear tables. Lustre glistening, often 
 dull. Cleavage imperfect, but three-fold 
 rectangular. Fracture fine splintery. J rans- 
 lucent on the edges. Rather easily frangi- 
 ble. Harder than felspar, but softer than 
 quartz. Sp. gr. 2.98. It melts before the 
 blow-pipe into a brownish-yellow transpa- 
 rent glass. It is found along with calcare- 
 ous spar in the valley of Fassa in the i viol. 
 Its constituents arc, lime 35.5, silica 29.64, 
 alumina 24.8, oxide of iron 6.56, volatile 
 matter 3.3. * 
 
 Gelatin, Gelly, or Jflly, an animal 
 substance, soluble in water, capable of as- 
 suming a well-known elastic or tremulous 
 
 consistence, by cooling, when the water is not 
 too abundant, and liquefiable again bv in- 
 creasing its temperature. This last property 
 distinguishes it from albumen, which be- 
 comes consistent by heat. It is precipitated 
 in an insoluble form by tannin, and it is this 
 action of tannin on gelatin that is the foun- 
 dation of the art of tanning leather. See 
 Glue. 
 
 * According to the analysis of MM. Gay 
 Lussac and Thenard, gelatin is composed of 
 Carbon, - 47.881 
 
 Oxygen, - 27.207 
 
 Hydrogen, - 7.914 
 
 Azote, - - 16.998 
 
 100 . 000 * 
 
 Gems* This word is used to denote such 
 stones as are considered by mankind as pre- 
 cious. These are the diamond, the ruby, 
 the sapphire, the topaz, the chrysolite, the 
 beryl, the emerald, the hyacinth, the ame- 
 thyst, the garnet, the tourmalin, the opal ; 
 and to these may he added, rock crystal, the 
 finer flints of pebbles, the cat’s eye, the ocu- 
 lus mundi, or hydrophanes, the chalcedony, 
 the moon-stone, the onyx, the carnelian, the 
 sardonyx, agates, and the Labrador-stone ; 
 for which, consult the several articles respec- 
 tively. 
 
 Geodes. A kind of sctites, the hollow of 
 which, instead of a nodule, contains only 
 loose earth, and is commonly lined with 
 crystals. 
 
 * Geognosy. See Geology.* 
 
 * Geology. A description of the struc- 
 ture of the earth. This study may be divid- 
 ed, like most others, into tw'o parts ; obser- 
 vation and theory. By the first we learn the 
 relative positions of the great rocky or mi- 
 neral aggregates that compose the crust of 
 our globe ; through the second, we endea- 
 vour to penetrate into the causes of these 
 collocations. A valuable work has been 
 lately published, comprehending a view' of 
 both parts of the subject, by Mr Greenough, 
 to which I refer my readers for much in- 
 struction, communicated in a very interesting 
 manner. The plan of this work permits me 
 merely to give in this place an outline of the 
 general arrangement of the great mineral 
 masses, as ascertained by Werner, and des- 
 cribed by Professor Jameson. 
 
 There is a great class of rocks, which lies 
 under every other, but never over any of 
 them ; it is therefore reckoned by Werner 
 the oldest or first formed. It is denominat- 
 ed the primitive class. The rocks belonging 
 to this class, have a crystalline appearance, 
 indicating that they have been precipitated 
 from a state of chemical solution. They are 
 principally composed of siliceous, argillace- 
 ous, and magnesian earths. Granite, gneiss, 
 mica-slate, clay-slate, serpentine, porphyry, 
 and syenite, are of this kind. Of these, 
 
GEO 
 
 GEO 
 
 granite is the oldest, and syenite is the new- 
 est. 
 
 To this succeeds another considerable class 
 of rocks, which Werner denominates transi- 
 tion. In this class, which is principally com- 
 posed of chemical productions, mechanical 
 depositions first make their appearance, but 
 in the earlier part in inconsiderable quantity. 
 
 Limestone first occurs in considerable 
 quantity in this class. 
 
 Greywacke, greywacke slate, and transi- 
 tion limestone, are the predominating rocks 
 of this class. 
 
 Still newer, and consequently lower, than 
 the transition class, is the extensive class 
 of fioetz rocks. Here mechanical deposites 
 occur in great quantity, and the proportion 
 of chemical precipitate decreases. The prin- 
 cipal rocks are limestone and sandstone ; to 
 these may be added gypsum, salt, and great 
 accumulations of inflammable matter in the 
 state of coal. 
 
 Still newer and lower is the class of allu- 
 vial rocks, which are almost entirely com- 
 posed of mechanical deposites. Sand, clay, 
 loam, and coal, are the principal earthy mas- 
 ses that belong to this class. 
 
 The newest of all, is the class of volcanic 
 rocks. Different kinds of lava and tuff in- 
 clude nearly all the variety of rocks belong- 
 ing to this class. 
 
 In the first class, we observe several rocks 
 always disposed in conformable and unbro- 
 ken stratification, and in which the newer 
 and newer strata, have always a lower and 
 lower level. Gneiss, mica-slate, and clay- 
 slate, are of this kind. The granite stretches 
 under them uninterruptedly, and sometimes 
 rises up through them, or juts up in the form 
 * of single caps or great masses ; so that the 
 gneiss, and other rocks, are disposed on its 
 surface, sometimes in a concave, sometimes 
 in a convex direction, sometimes saddle- 
 shaped, and frequently mantle-shaped. It 
 is evident, from the relations of the strata, 
 that granite w ill frequently form the greatest 
 heights on the surface of the globe. 
 
 Porphyry has a very different kind of stra- 
 tification from the preceding rocks. It oc- 
 curs sometimes broken, sometimes unbroken. 
 V hen broken, it presents caps, upfillings, 
 and shield-shaped stratifications. When un- 
 broken, it forms widely extended masses. 
 Its position is unconfbrmable and overlying. 
 
 Greywacke occurs sometimes in an un- 
 confbrmable position ; also in caps, upfill- 
 ings, and shield-shaped, and frequently man- 
 tle-shaped strata, surrounding the older 
 mountains. 
 
 ihe limestone and sandstone formations 
 are usually disposed in a mantle-shape 
 around the older formations ; sometimes 
 they are broken, hut more frequently un- 
 broken. They are very common and widely 
 distributed formations. 
 
 Coal again shew's a very peculiar charac- 
 ter. Its original extent is not considerable ; 
 it even appears interrupted and broken ; but 
 its internal characters shew that its present 
 apparently broken appearance is its original 
 one. It occurs commonly in trough and 
 basin-shaped hollows, and its strata have con- 
 sequently a concave direction. 
 
 The rocks of the newest Jloctz-trap forma- 
 tion are distinguished from the older by their 
 unconformable overlying, and broken strati- 
 fication. In these respects, they nearly agree 
 with porphyry. When the continuity of 
 the formation is broken, it occurs in caps, 
 upfillings, and rarely shield- shaped. 
 
 Table off the different Mountain Rocks . 
 
 Class I. 
 
 Primitive rocks. 
 
 1. Granite. 
 
 2. Gneiss. 
 
 5. Mica- slate. 
 
 4. Cl ay- si ate. 
 
 5. Primitive limestone. 
 
 6. Primitive trap. 
 
 7. Serpentine. 
 
 8. Porphyry. 
 
 9. Syenite. 
 
 10. Topaz- rock. 
 
 11. Quartz-rock. 
 
 12. Primitive flinfy-slate. 
 
 13. Primitive gypsum. 
 
 * 
 
 14. White- stone. 
 
 Class II. 
 
 Transition rocks . 
 
 1. Transition limestone. 
 
 2. Transition trap. 
 
 3. Greywacke. 
 
 4. Transition flinty-slate. 
 
 5. Transition gypsum. 
 
 Class III. 
 
 Fioetz rocks . 
 
 1. Old red sandstone, or first sandstone 
 
 formation. 
 
 2. First or oldest fioetz limestone. 
 
 3. First or oldest fioetz gypsum. 
 
 4. Second or variegated sandstone forma- 
 
 tion. 
 
 5. Second fioetz gypsum. 
 
 6. Second fioetz limestone. 
 
 7. Third fioetz limestone. 
 
 8. Rock-salt formation. 
 
 9. Chalk formation. 
 
 10. Fioetz- trap formation. 
 
 11. Independent coal formation. 
 
 12. Newest floetz-trap formation. 
 
 Class IV. 
 
 Alluvial rocks. 
 
 1. Peat. 
 
 2. Sand and gravel. 
 
GEO 
 
 GEO 
 
 3. Loam. 
 
 4. Bog- iron ore. 
 
 5. Nagelfluh. 
 
 6 . Calc-tuff. 
 
 7. Calc-sinter. 
 
 Class V. 
 
 Volcanic rocks. 
 
 * Pseudo- volcanic rocks. 
 
 1. Burnt clay. 
 
 2. Porcelain jasper. 
 
 ?>. Earth slag;. 
 
 © 
 
 4. Columnar clay ironstone. 
 
 5. Polier, or polishing slate. 
 
 * * True volcanic rocks. 
 
 1. Ejected stones and ashes. 
 
 2. Different kinds of lava. 
 
 3. The matter of muddy eruptions. 
 
 Professor Jameson has lately announced 
 a new volume on geology, which will most 
 probably exhibit some modification of the 
 above arrangements, to which Mr G^eenough, 
 and other accurate practical geologists, have 
 made several objections. 
 
 The ancient history of the globe, which 
 may be regarded as the ultimate object of 
 geological researches, is undoubtedly one of 
 the most curious subjects that can engage the 
 attention of enlightened men. The lowest 
 and most level parts of the earth, when pe- 
 netrated to a very great depth, exhibit no- 
 thing but horizontal strata, composed of va- 
 rious substances, and containing almost all 
 of them innumerable marine productions. 
 Similar strata, with the same kind of produc- 
 tions, compose the hills even to a great 
 height. Sometimes the shells are so nume- 
 rous as to constitute the entire body of the 
 stratum. They are almost every- where in 
 such a perfect state of preservation, that even 
 the smallest of them retain their most deli- 
 cate parts, their sharpest ridges, and ten derest 
 processes. They are found in elevations far 
 above the level of every part of the ocean, 
 and in places to which the sea could not be 
 conveyed by any presently existing cause. 
 They are not merely enclosed in loose sand, 
 but are often increased and penetrated on all 
 sides by the hardest stones. Every part of 
 the earth, every hemisphere, every continent, 
 every island of any size, exhibits the same 
 phenomenon. We are therefore forcibly 
 led to believe, not only that the sea has at 
 one period or another covered all our plains, 
 
 but that it must have remained there for a 
 long time, and in a state of tranquillity ; 
 w T hich circumstance was necessary for the 
 formation of deposites so extensive, so thick, 
 in part so solid, and containing exuviae so 
 perfectly preserved. A nice and scrupulous 
 comparison of the forms, contexture, and 
 composition of these shells, and of those 
 which still inhabit the sea, cannot detect the 
 slightest difference between them. They 
 
 26 
 
 have therefore once lived in the sea, and 
 been deposited by it ; the sea consequent- 
 ly must have rested in the places where 
 the deposition has taken place. Hence it is 
 evident, that the basin or reservoir containing 
 the sea has undergone some change, either in 
 extent, situation, or both. 
 
 The traces of revolutions become still 
 more apparent and decisive when we ascend 
 a little higher, and approach nearer to the 
 foot of the great chain of mountains. There 
 are still found many beds of shells ; some of 
 these are even larger and more solid ; the 
 shells are quite as numerous, and as entirely 
 preserved ; but they are not of the same 
 species with those which were found in the 
 less elevated regions. The strata which 
 contain them are not so generally horizon- 
 tal ; they have various degrees of inclina- 
 tion, and are sometimes situated vertically. 
 While in the plains and low hills it was ne- 
 cessary to dig deep in order to detect the 
 succession of the strata, here we perceive 
 them by means of the valleys, which time or 
 violence has produced, and which disclose 
 their edges to the eye of the observer. 
 
 Thus the sea, previous to the formation of 
 the horizontal strata, had formed others, 
 which by some means have been broken, 
 lifted up, and overturned in a thousand 
 ways. But the sea has not alw r ays deposited 
 stony substances of the same kind. It has 
 observed a regular succession as to the na- 
 ture of its deposites ; the more ancient the 
 strata are, so much the more uniform and 
 extensive are they ; and the more recent they 
 are, the more limited are they, and the more 
 variation is observed in them at small dis- 
 tances. Thus the great catastrophes which 
 have produced revolutions in the basins of 
 the sea, were preceded, accompanied, and 
 followed by changes in the nature of the 
 fluid, and of the substances which it held in 
 solution ; and when the surface of the seas 
 came to be divided by islands and projecting 
 ridges, different changes took place in every 
 separate basin. 
 
 These irruptions and retreats of the sea 
 have neither been slow' nor gradual ; most of 
 the catastrophes which have occasioned them 
 have been sudden ; and this is easily proved, 
 especially w ith regard to the last of them, or 
 the Mosaic deluge, the traces of which are 
 very conspicuous. In the northern regions 
 it has left the carcases of some large quadru- 
 peds, w hich the ice had arrested, and which 
 are preserved even to the present day, with 
 their skin, their hair, and their flesh. If 
 they had not been frozen as soon as killed, 
 they must have been quickly decomposed by 
 putrefaction. But this perpetual frost could 
 not have taken possession of the regions 
 which these animals inhabited, except by the 
 same cause w hich destroyed them ; this cause 
 must therefore have been as sudden as its 
 
GIL 
 
 GIL 
 
 effect. The two most remarkable pheno- 
 mena of this kind, and which must for ever 
 banish all idea of a slow and gradual revo- 
 lution, are the rhinoceros, discovered in 1771 
 on the banks of the Vilhoui , and the ele- 
 phant, recently found by M. Adams near 
 the mouth of the Sena. This last retained 
 its flesh and skin, on which was hair of two 
 kinds ; one short, fine, and crisped, resem- 
 bling wool ; and the other like bristles. I he 
 flesh was still in such high preservation, that 
 it was eaten by dogs. Every part of the 
 globe bears the impress of these great and 
 terrible events so distinctly, that they must 
 be visible to all who are qualified to read 
 their history in the remains which they have 
 left behind . — See Cuvier s Theory of the 
 Earth. 
 
 I shall conclude this article by stating, 
 that this naturalist, the most learned of the 
 present day, as well as Eolomieu, Deluc, 
 and Greenough, concur in thinking that not 
 above 5000 or 6000 years have elapsed since 
 the period of the deluge, which agrees with 
 the Mosaic epoch of that catastrophe. * 
 
 * Germination. The vital develope- 
 ment of a seed, when it first begins to grow.* 
 
 Gilding. The art of covering the sur- 
 faces of bodies with gold. 
 
 The gold prepared for painting is called 
 shell-gold or gold-powder, and may be ob- 
 tained by amalgamating one part of gold 
 with eight of quicksilver, and afterward eva- 
 porating the latter, which leaves the gold in 
 the form of powder ; or otherwise the metal 
 may be reduced to powder by mechanical 
 trituration. For this purpose, gold leaf must 
 be ground with honey or strong gum-water 
 for a long time; and w r hen the powder is 
 sufficiently fine, the honey or gum may be 
 washed off with W'ater. 
 
 For cold gilding by friction, a fine linen 
 rag is steeped in a saturated solution of gold 
 till it has entirely imbibed the liquor ; this 
 rag is then dried over a fire, and afterward 
 burned to tinder. Now, when any thing is 
 to be gilded, it must be previously well bur- 
 nished ; a piece of cork is then to be dipped, 
 first into a solution of salt in water, and af- 
 terward into the black powder ; and the 
 piece, after it is burnished, rubbed with it. 
 
 bor water gilding, the solution of gold 
 may be evaporated till it is of an oily con- 
 sistence, suffered to crystallize, and the crys- 
 tals dissolved in water be employed instead 
 of the acid solution. It this be copiously 
 diluted with alcohol, a piece of clean iron 
 will be gilded by being steeped therein. Or 
 add to the solution about three times its 
 quantity of sulphuric ether, which will soon 
 take up the nitro- muriate of gold, leaving 
 the acid colourless at the bottom of the ves- 
 sel, which must then be drawn off. Steel 
 dipped into the ethereal solution for a mo- 
 
 ment ; and instantly washed in clean water, 
 will be completely and beautifully covered 
 with gold. The surface of the steel must 
 be w'ell polished, and wiped very clean. 
 
 For the method called Grecian gilding, 
 equal parts of sal ammoniac and corrosive 
 sublimate are dissolved in nitric acid, and a 
 solution of gold is made in this menstruum ; 
 upon this the solution is somewhat concen- 
 trated, and applied to the surface of silver, 
 which becomes quite black ; but, on being 
 exposed to a red heat, it assumes the appear- 
 ance of gilding. 
 
 The method of gilding silver, brass, nr 
 copper, by an amalgam, is as follows : Eight 
 parts of mercury, and one of gold, are incor- 
 porated together by heating them in a cruci- 
 ble. As soon as the gold is perfectly dis- 
 solved, the mixture is poured into cold wa- 
 ter, and is then ready for use. 
 
 Before the amalgam can be laid upon the 
 surface of the metal, this last is brushed over 
 with dilute aquafortis, in wdiich it is of ad- 
 vantage that some mercury may have been 
 dissolved. Some artists then wash the me- 
 tal in fair water, and scour it a little with 
 fine sand, previous to the application of the 
 gold ; but others apply it to the metal while 
 still wet with the aquafortis. But in either 
 case the amalgam must be laid on as uni- 
 formly as possible, and spread very evenly 
 with a brass-wire brush, wetted from time 
 to time with fair w r ater. The piece is then 
 laid upon a grate, over a charcoal fire, or in 
 a small oven or furnace adapted to this pur- 
 pose. The heat drives off the mercury, and 
 leaves the gold behind. Its defects are then 
 seen, and may be remedied by successive 
 applications of more amalgam, and addi- 
 tional application of heat. The expert ar- 
 tists, however, make these additional appli- 
 cations while the piece remains in the fur- 
 nace, though the practice is said to be highly 
 noxious on account of the mercurial fumes. 
 After this it is rubbed with gilders’ wax, 
 which may consist of four ounces of bces>’ 
 wax, one ounce of verdigris, and . one ounce 
 of sulphate of copper ; then expose it to a 
 red heat, which burns off the w ax ; and, 
 lastly, the work is cleared with the scratch 
 brush, and burnished, if necessary, with a 
 steel tool. The use of the wax seems to 
 consist merely in covering defects, by the 
 diffusion of a quantity of red oxide of cop- 
 per, which is left behind after the burning. 
 
 The gilding of iron by mere heat is per- 
 formed by cleaning and polishing its sur- 
 face, and then heating it till it has acquired 
 a blue colour. When this has been done, 
 the first layer of gold leaf is put on, slightly 
 burnished down, and exposed to a gentle 
 fire. It is usual to give three such layers, 
 or four at the most, each consisting of a 
 single leal lor common works, or two for 
 
GIL 
 
 GLA 
 
 extraordinary ones. The heating is re- 
 peated at each layer, and last of all the work 
 is burnished. 
 
 The gilding of buttons is done in the fol- 
 lowing way : When the buttons, which are 
 of copper, are made, they are dipped into 
 dilute nitric acid to clean them, and then 
 burnished with a hard black stone. They 
 are then put into a nitric solution of mer- 
 cury, and stirred about with a brush, till 
 they are quite white. An amalgam of gold 
 and mercury is then put into an earthen 
 vessel with a small quantity of dilute nitric 
 acid, and in this mixture the buttons are 
 stirred, till the gold attaches to their sur- 
 face. They are then heated over the fire, 
 till the mercury begins to run, when they 
 arc thrown into a large cap made of coarse 
 wool and goat’s hair, and in this they are 
 stirred about with a brush. The mercury 
 is then volatilized by heating over the fire 
 in a pan, to the loss of the article, and in- 
 jury of the workmen’s health ; though the 
 greater part might be recovered, with less 
 injury to the operators. By act of parlia- 
 ment, a gross of buttons, of an inch diame- 
 ter, are required to have five grains of gold 
 on them ; but many are deficient even of 
 this small quantity. 
 
 Painting with gold upon porcelain or glass 
 is done with the powder of gold, which re- 
 mains behind after distilling the aqua regia 
 from a solution of that metal. It is laid on 
 with borax and gum-water, burned in, and 
 polished. The gilding of glass is commonly 
 effected by covering the part with a solution 
 of borax, and applying gold leaf upon it, 
 which is afterward fixed by burning. 
 
 Gilding in oil is performed by means of a 
 paint sold under the name of gold size. It 
 consists of drying oil, (that is to say, linseed 
 oil boiled upon litharge), and mixed with 
 yellow ochre. It is said to improve in its 
 quality by keeping. This is laid upon the 
 work ; and when it has become so dry as to 
 adhere to the fingers without soiling them, 
 the gold leaf is laid on, and pressed down 
 with cotton. This method of gilding is 
 proper for work intended to be exposed to 
 the weather. 
 
 The method of gilding in burnished gold 
 consists in covering the work with parch- 
 ment size and whiting, thinly laid on at five 
 or six different times. T his is covered with 
 a yellow size made of Armenian bole, a lit- 
 tle wax, and some parchment size ; but in 
 this, as in most other compositions used in 
 the arts, there are variations which depend 
 on the skill or the caprice of the artists. 
 'When the size is dry, the gold is applied 
 upon the surface previously wetted with 
 clear water. A certain number of hours 
 after this application, but previous to the 
 perfect hardening of the composition, the 
 gold may be very highly burnished with a 
 
 tool of agate made for this purpose. This 
 gilding is fit only for work within doors ; 
 for it readily comes off upon being wetted. 
 
 The edges of the leaves of books are 
 gilded by applying a composition of one 
 part Armenian bole, and one quarter of a 
 part of sugar-candy, ground together with 
 white of eggs. This is burnished while the 
 book remains in the press, and the gold is 
 laid on by means of a little water. 
 
 Leather is gilded either with leaf-brass or 
 silver, but most commonly by the latter, in 
 which case a gold coloured varnish is laid 
 over the metal. Tin-foil may be used in- 
 stead of silver leaf for this less perfect gild- 
 ing, upon such works as do not possess flexi- 
 bility. 
 
 * Glass. Most of the treatises which I 
 have seen on the manufacture of glass, illus- 
 trate a well known position, that it is easy to 
 write a large volume, which shall communi- 
 cate no definite information. There are five 
 distinct kinds of glass at present manufac- 
 tured : — 
 
 1. Flint glass, or glass of lead. 
 
 2. Plate glass, or glass of pure soda. 
 
 3. Crown glass, the best window-glass. 
 
 4. Broad glass, a coarse window-glass. 
 
 5. Bottle, or coarse green glass. 
 
 1 . Flint Glass, so named because the sili- 
 ceous ingredient was originally employed in 
 the form of ground flints. It is now made 
 of the following composition : — 
 
 Purified Lynn sand, 100 parts 
 
 Litharge or red lead, 60 
 
 Purified pearl ash, 50 
 
 To correct the green colour derived from 
 combustible matter, or oxide of iron, a lit- 
 tle black oxide of manganese is added, and 
 sometimes nitre and arsenic. The fusion is 
 accomplished usually in about thirty hours. 
 
 2. Plate Glass. Good carbonate of soda 
 procured by decomposing common salt with 
 pearl ash, is employed as the fiux. The 
 proportion of the materials is, 
 
 Pure sand, 
 
 43.0 
 
 Dry subcarbonate of soda, 
 
 26.5 
 
 Pure quicklime, 
 
 4. 
 
 Nitre, 
 
 1.5 
 
 Broken plate glass, 
 
 25.0 
 
 
 100.0 
 
 About seventy parts of good plate glass 
 may be run off from these materials. 
 
 3. Crown, orjinc Window-glass. This is 
 made of sand vitrified by the impure barilla, 
 manufactured by incineration of sea weed, 
 on the Scotch and Irish shores. The most 
 approved composition, is 
 
 By measure. By weight. 
 
 Fine sand purified, 5 — 200 
 Best kelp ground, 1 1 — 330 
 These ingredients are mixed, and then 
 thrown into the fritting arch, where the sul- 
 phur of the kelp is dissipated, and the mat- 
 
GLA 
 
 GLA 
 
 ters are thoroughly incorporated, forming, 
 when withdrawn at the end of four hours, a 
 greyish- white tough mass, which is cut into 
 brick shaped pieces, and after concretion and 
 cooling, piled up for use. By long keeping, 
 a soda efflorescence forms on their surface. 
 They are then supposed to have become more 
 valuable. These bricks are put into the melt- 
 ing pots, and sometimes a proportion of com- 
 mon salt is thrown in towards the end of the 
 operation, if the vitrification has been imper- 
 fect. Under the article sulphate of soda , 
 in this Dictionary, retained from the old edi- 
 tion, there is the following sentence. “ Pajot 
 des Charmes has made some experiments on 
 it in fabricating glass; with sand alone, it 
 would not succeed, but equal parts of carbo- 
 nate of lime, sand, and dried sulphate of so- 
 da, produced a clear solid, pale yellow glass.” 
 In the Annals of Philosophy for Jan. 1817, 
 we find the following notice from Schweig- 
 ger’s Journal, xv. 89. : Gehlen, some time 
 before his death, was occupied with experi- 
 ments on the preparation of glass, by means 
 of sulphate of soda. Professor Schw'eigger 
 has lately published the result of his trials, 
 lie found that the following proportions were 
 the best : — 
 
 Sand, - - - - 100 
 
 Dry sulphate of soda, - 50 
 
 Dry quicklime in powder, - 1 7 to 20 
 
 Charcoal, - 4 
 
 This mixture aKvays gives a very good 
 glass without any addition whatever. Dur- 
 ing the fusion, the sulphuric acid is decom- 
 posed and drawn off, and the soda unites 
 with the silica. The sulphate of soda vitri- 
 fies very imperfectly, when mixed alone with 
 the silica. The vitrification succeeds better 
 when quicklime is added, and it succeeds 
 completely, when the proportion of charcoal 
 iu the formula is added ; because the sulphu- 
 ric acid is thereby decomposed and dissipated. 
 This decomposition may be either effected 
 during the making of the glass, or before, at 
 the pleasure of the workmen. 
 
 4. Iiroad Glass. This is made of a mix- 
 ture of soap boilers’ waste, kelp, and sand. 
 The first ingredient consists of lime used for 
 rendering the alkali of the soap boiler caus- 
 tic, the insoluble matter of his kelp or barilla, 
 and a quantity of salt and water, all in a pas- 
 ty state. The proportions necessarily vary. 
 
 2 of the waste, 1 of kelp, and 1 of sand, form 
 a pretty good broad glass. They are mixed 
 together, dried, and fritted. 
 
 5. Jtottle Glass is the coarsest kind. It 
 is made of soaper’s waste and river sand, in 
 proportions which practice must determine 
 according to the quantity of the w'aste ; 
 some soap boilers extracting more saline mat- 
 ter, and others less from their kelps. Com- 
 mon sand and lime, with a little common 
 clay and sea salt, form a cheap mixture for 
 bottle glass. * 
 
 As far as observation has hitherto directed 
 us, it appears to be a general rule, that the 
 hardness, brittleness, elasticity, and other 
 mechanical properties of congealed bodies, 
 are greatly affected by the degree of rapidity 
 with which they assume the solid state. 
 This, which no doubt is referable to the 
 property of crystallization, and its various 
 modes, is remarkably seen in steel and other 
 metals, and seems to obtain in glass. W hen 
 a drop of glass is suffered to fall into w ater, 
 it is found to possess the remarkable pro- 
 perty of flying into minute pieces, the in- 
 stant a small part of the tail is broken off. 
 This, which is commonly distinguished by 
 the name of Prince Rupert’s drop, is similar 
 to the philosophical phial, which is a small 
 vessel of thick glass suddenly cooled by ex- 
 posure to the air. Such a vessel possesses 
 the property of flying in pieces, when the 
 smallest piece of flint or angular pebble is 
 let fall into it, though a leaden bullet may be 
 dropped into it from some height without 
 injury. Many explanations have been offer- 
 ed, to account for these and other similar 
 appearances, by referring to a supposed me- 
 chanism or arrangement of the particles, 
 or sudden confinement of the matter of heat. 
 The immediate cause, however, appears to 
 be derived from the fact, that the dimensions 
 of bodies suddenly cooled remain larger, 
 than if the refrigeration had been more gra- 
 dual. Thus the specific gravity of steel har- 
 dened by sudden cooling in water is less, 
 and its dimensions consequently greater than 
 that of the same steel gradually cooled. It 
 is more than probable, that an effect of the 
 same nature obtains in glass; so that the 
 dimensions of the external and suddenly 
 cooled surface remain larger than are suited 
 to the accurate envelopement of the interior 
 part, which is less slowly cooled. In most 
 of the metals, the degree of flexibility they 
 possess, must be sufficient to remedy this 
 inaccuracy as it takes place ; but in glass, 
 which, though very elastic and flexible, is 
 likewise excessively brittle, the adaptation of 
 the parts, urged different ways by their dis- 
 position to retain their respective dimensions, 
 and likewise to remain in contact, by virtue 
 of the cohesive attraction, can be maintained 
 only by an elastic yielding of the whole, as 
 far as may be, which wdll therefore remain 
 in a state of tension. It is not therefore to 
 be wondered at, that a solution of continuity 
 of any part of the surface should destroy 
 this equilibrium of elasticity; and that the 
 sudden action of all the parts at once, of so 
 brittle a material, should destroy the conti- 
 nuity of the whole, instead of producing an 
 equilibrium of any other kind. 
 
 Though the facts relating to this disposi- 
 tion of glass too suddenly cooled, are numer- 
 ous and interesting to the philosopher, yet 
 
GLA 
 
 GLI 
 
 they constitute a serious evil with respect to 
 the uses of this excellent material. The re- 
 medy of the glass- maker consists in anneal- 
 ing the several articles, which is done by 
 placing them in a furnace near the furnace 
 of fusion. The glasses are first put into the 
 hottest part of this furnace, and gradually 
 removed to the cooler parts at regular inter- 
 vals of time. By this means the glass cools 
 very slowly throughout, and is in a great 
 measure free from the defects of glass which 
 has been too hastily cooled. 
 
 M. Reaumur was the first who made any 
 direct experiments upon the conversion of 
 glass into porcelain. Instances of this ef- 
 fect may be observed among the rubbish of 
 brick-kilns, where pieces of green bottles 
 are not unfrequently subjected by accident, 
 to the requisite heat ; but the direct process 
 is as follows : A vessel of green glass is to 
 be filled up to the top with a mixture of 
 white sand and gypsum, and then set in a 
 large crucible upon a quantity of the same 
 mixture, with which the glass vessels must 
 also be surrounded and covered over, and 
 the whole pressed down rather hard. The 
 crucible is then to be covered with a lid, the 
 junctures well luted, and put into a potter’s 
 kiln, where it must remain during the whole 
 time that the pottery is baking ; after which, 
 the glass vessel will be found transformed 
 into a milk-white porcelain. The glass, on 
 fracture, appears fibrous, as if it were com- 
 posed merely of silken threads laid by the 
 side of each other : it has also quite lost the 
 smooth and shining appearance of glass, is 
 very hard, and emits sparks of fire when 
 struck with steel, though not so briskly as 
 real porcelain. Lewis observed, that the 
 above-mentioned materials have not exclu- 
 sively this effect upon glass; but that pow- 
 dered charcoal, soot, tobacco-pipe clay, and 
 bone-ashes, produce the same change. It is 
 remarkable, that the surrounding sand be- 
 comes in some measure agglutinated by this 
 process, which, if continued for a sufficient 
 length of time, entirely destroys the texture 
 of the glass, and renders it pulverulent. 
 
 The ancient stained glass has been much 
 admired, and beautiful paintings on this 
 substance have been produced of late years. 
 The colours are of the nature of those used 
 in enamelling, and the glass should have no 
 lead in its composition. Mr Brogniart has 
 made many experiments on this subject. 
 The purple of Cassius, mixed with six parts 
 of a flux composed of borax and glass made 
 with silex and lead, produces a very beauti- 
 ful violet, but liable to turn blue. Red 
 oxide of iron, prepared by means of the nitric 
 acid and subsequent exposure to fire, and 
 mixed with a flux of borax, sand, and a 
 small portion of minium, produces a fine 
 red. Muriate of silver, oxide of zinc, white 
 £lay, and'the yellow oxide of iron, mixed to- 
 
 gether without any flux, produce a yellow, 
 light or deep, according to the quantity laid 
 on, and equal in beauty to that of the an- 
 cients. A powder remains on the surface 
 after baking, which may easily be cleaned 
 off. Blue is produced by oxide of cobalt, 
 wdth a flux of silex, potash, and lead. To 
 produce a green, blue must be put on one 
 side of the glass, and yellow on the other ; 
 or a blue may be mixed with yellow oxide 
 of iron. Black is made by a mixture of 
 blue w ith the oxides of manganese and iron. 
 
 The bending of the glass, and alteration 
 of the colours, in baking, are particularly to 
 be avoided, and require much care. Gyp- 
 sum has been recommended for their sup- 
 port, but this frequently renders the glass 
 white, and cracked in all directions, probably 
 from the action of the hot sulphuric acid on 
 the alkali in the glass. Mr Brogniart 
 placed his plates of glass, some of them 
 much larger than any ever before painted, 
 on very smooth plates of earth or porcelain 
 unglazed, which he found to answer extreme- 
 ly w r ell. 
 
 * Glauber Salt. Native sulphate of 
 soda. Its colours are greyish and yellowish- 
 white. It occurs in mealy efflorescences, 
 prismatic crystals, and imitative shapes. 
 Lustre vitreous. Cleavage three-fold. Frac- 
 ture conchoidal. Soft. Brittle. Sp. gr. 
 2.2 to 2.5. Taste at Hrst cooling, then sa- 
 line and bitter. Its solution does not, like 
 that of Epsom salt, afford a precipitate with 
 an alkali. Its constituents are, sulphate of 
 soda 67 ; carbonate of sodalGy; muriate 
 of soda 11 ; carbonate of lime 5.64. It oc- 
 curs along with rock salt and Epsom salt, 
 on the borders of salt lakes, and dissolved 
 in the waters of lakes and the ocean ; in 
 efflorescences on moorish ground ; also on 
 sandstone, marl-slate, and walls. It is found 
 at Eger in Bohemia, on meadow’-ground, 
 as an efflorescence, and in galleries ot mines 
 in several places. * — Jameson. 
 
 * Glauberite. Colours greyish- white, 
 and wine-yellow. Crystallized in very low 
 oblique four-sided prisms, the lateral edges 
 of which are 104° 28', and 75° 52'. Late- 
 ral planes transversely streaked : terminal 
 planes smooth. Shining. Fracture foliat- 
 ed or conchoidal. Softer than calcareous 
 spar. Transparent. Brittle. Sp. gr. 2.7. 
 It decrepitates before the blow-pipe, and 
 melts into white enamel. In water it be- 
 comes opaque, and is partly soluble. Its 
 constituents arc, dry sulphate of lime 49 ; 
 dry sulphate of soda 51. It is found im- 
 bedded in rock-salt, at Villaruba, near 
 Oeana, in New Castile in Spain.* — Jame- 
 son. 
 
 Glazing. See Pottery. 
 
 Glimmer. A name occasionally applied 
 to micaceous earths. 
 
 * Gliadise. See Gluten.* 
 
GLU 
 
 GLU 
 
 Glucina. This earth was discovered by 
 Vauquelin, first in the aqua marina, and 
 afterward in the emerald, in the winter of 
 1798. Its name is derived from its distin- 
 guishing character of forming with acids 
 salts that are sweet to the taste. The fol- 
 lowing is his method of obtaining it: — 
 
 Let 100 parts of beryl, or emerald, be re- 
 duced to a fine powder, and fused in a sil- 
 ver crucible with 500 ot pure potash. Let 
 the mass be diffused in water, and dissolved 
 by adding muriatic acid. Evaporate the so- 
 lution, taking care to stir it toward the end : 
 mix the residuum with a large quantity of 
 water, and filter, to separate the silex. Pre- 
 cipitate the filtered liquor which contains 
 the muriates of alumina and glucina, with 
 carbonate of potash ; wash the precipitate, 
 and dissolve it in sulphuric acid. Add a 
 certain quantity of sulphate of potash, eva- 
 porate, and crystals of alum will be obtain- 
 ed. When no more alum is afforded by 
 adding sulphate of potash and evaporating, 
 add solution of carbonate of ammonia in ex- 
 cess, shake the mixture well, and let it stand 
 some hours, till the glucina is redissolved by 
 the excess of carbonate of ammonia, and no- 
 thing but the alumina remains at the bottom 
 of the vessel. Filter the solution, evaporate 
 to dryness, and expel the acid from the car- 
 bonate of glucina, by slight ignition in a 
 crucible. Thus 15 or 16 per cent of pure 
 glucina will be obtained. 
 
 Glucina thus obtained, is a white, soft 
 powder, light, insipid, and adhering to the 
 tongue. It does not change vegetable blues. 
 It does not harden, shrink, or agglutinate by 
 heat; and is infusible. It is insoluble in 
 water, but forms with it a slightly ductile 
 paste. It is dissolved by potash, soda, and 
 carbonate of ammonia ; but not by pure am- 
 monia. It unites with sulphuretted hydro- 
 gen. Its salts have a saccharine taste, with 
 somewhat of astringency. 
 
 * Sir H. Davy’s researches have rendered 
 it more than probable, that glucina is a com- 
 pound of oxygen and a peculiar metallic 
 substance, which may be called glucinum. 
 By heating it along with potassium, the lat- 
 ter was converted for the most part into pot- 
 ash, and dark coloured particles, having a 
 metallic appearance, were found diffused 
 through the mass, which regained the earthy 
 character by being heated in the air, and by 
 the action of water. In this last case, hydro- 
 gen was slowly disengaged. According to 
 Sir H. Davy, the prime equivalent of glu- 
 cina would be 5.6 on the oxygen scale, and 
 that of glucinum 2.6. These are very nearly 
 the equivalents of lime, and calcium. From 
 the composition of the sulphate, Berzelius 
 infers the equivalent to be 3.2, and that of 
 its basis 2.2.* 
 
 Glue. An inspissated jelly made from 
 the parings of hides and other offals, by 
 
 boiling them in water, straining through a 
 wicker basket, suffering the impurities to 
 subside, and then boiling it a second time. 
 The articles should first be digested in lime- 
 water, to cleanse them from grease and 
 dirt; then steeped in water, stirring them 
 well from time to time; and lastly, laid in a 
 heap, to have the water pressed out, before 
 they are put into the boiler. Some recom- 
 mend, that the water should be kept as 
 nearly as possible to a boiling heat, without 
 suffering it to enter into ebullition. In this 
 state it is poured into flat frames or moulds, 
 then cut into square pieces when congealed, 
 and afterward dried in a coarse net. It is 
 said to improve by age ; and that glue is 
 reckoned the best, which swells consider- 
 ably without dissolving by three or four 
 days infusion in cold water, and recovers 
 its former dimensions and properties by dry- 
 ing. 
 
 Shreds or parings of vellum, parchment, 
 or white leather, make a clear and almost 
 colourless glue. 
 
 Gluten (Vegetable). If wheat-flour be 
 made into a paste, and washed in a large 
 quantity of water, it is separated into three 
 distinct substances ; a mucilaginous saccha- 
 rine matter, which is readily dissolved in 
 the liquor, and may be separated from it by 
 evaporation ; starch, which is suspended in 
 the fluid, and subsides to the bottom by re- 
 pose ; and gluten, which remains in the 
 hand, and is tenacious, very ductile, some- 
 what elastic, and of a brown-grey colour. 
 The first of these substances does not essen- 
 tially differ from other saccharine mucilages. 
 The second, namely, the starch, forms a 
 gluey fluid by boiling in water, though it is 
 scarcely, if at all, acted upon by that fluid 
 when cold. Its habitudes and products 
 with the fire, or with nitric acid, are nearly 
 the same as those of gum and of sugar. It 
 appears to be as much more remote from 
 the saline state than gum, as gum is more 
 remote from that state than sugar. 
 
 The vegetable gluten, though it existed 
 before the washing, in the pulverulent form, 
 and has acquired its tenacity and adhesive 
 qualities from the water it has imbibed, is 
 nevertheless totally insoluble in this fluid. 
 It has scarcely any taste. When dry, it is 
 semi-transparent, and resembles glue in its 
 colour and appearance. If it be drawn out 
 thin, when first obtained, it may be dried by 
 exposure to the air ; but if it be exposed to 
 warmth and moisture while wet, it putrefies 
 like an animal substance. The dried glu- 
 ten applied to the flame of a candle, 
 crackles, swells, and burns, exactly like a 
 feather, or piece of horn. It affords the 
 same products by destructive distillation as 
 animal matters do; is not soluble in alcohol, 
 oils, or ether; and is acted upon by acids 
 and alkalis, when heated. According to 
 
GOL 
 
 GNE 
 
 ftouelle, it is the same with the caseous sub- 
 bailee of milk. 
 
 Gluten of 11 heat. — M. Taddey, an Italian 
 chemist, has lately ascertained that the glu- 
 ten of wheat may be decomposed into two 
 principles, which he has distinguished by the 
 names, gliadine (from yXia, gluten), and 
 ximome (from ferment). They are 
 
 obtained in a separate state by kneading the 
 iresh gluten in successive portions of alco- 
 hol, as long as that liquid continues to be- 
 come milky, when diluted with water. The 
 alcohol solutions being set aside, gradually 
 deposit a whitish matter, consisting of small 
 filaments of gluten, and become perfectly 
 transparent. Being now left to slow evapo- 
 ration, the gliadine remains behind, of the 
 consistence of honey, and mixed with a little 
 yellow resinous matter, from which it may 
 be freed, by digestion in sulphuric ether, in 
 which gliadine is not sensibly soluble. The 
 portion of the gluten not dissolved by the 
 alcohol is the zimome. 
 
 Properties of Gliadine . — When dry, it has 
 a straw-yellow colour, slightly transparent, 
 and in thin plates, brittle, having a slight 
 smell, similar to that of honeycomb, and, 
 when slightly heated, giving out an odour 
 similar to that of boiled apples. In the 
 mouth, it becomes adhesive, and has a 
 sweetish and balsamic taste. It is pretty 
 soluble in boiling alcohol, which loses its 
 transparence in proportion as it cools, and 
 then retains only a small quantity in solu- 
 tion. It forms a kind of varnish in those 
 bodies to which it is applied. It softens, 
 but does not dissolve in cold distilled water. 
 At a boiling heat it is converted into froth, 
 and the liquid remains slightly milky. It is 
 specifically heavier than water. 
 
 The alcoholic solution of gliadine becomes 
 milky, when mixed with water, and is preci- 
 pitated in white flocks by the alkaline car- 
 bonates. It is scarcely affected by the mi- 
 neral and vegetable acids. Dry gliadine 
 dissolves in caustic alkalis and in acids. It 
 swells upon red-hot coals, and then contracts 
 in the manner of animal substances. It 
 burns with a pretty lively flame, and leaves 
 behind it a light spongy charcoal, difficult to 
 incinerate. Gliadine, in some respects, ap- 
 proaches the properties of resins ; but differs 
 from them in being insoluble in sulphuric 
 ether. It is very sensibly affected by the in- 
 fusion of nut-galls. It is capable of itself of 
 undergoing a slow fermentation, and pro- 
 duces fermentation in saccharine substances. 
 
 From the flour of barley, rye, or oats, no 
 gluten can be extracted, as from that of 
 ■wheat, probably because they contain too 
 small a quantity.* See Zimome. 
 
 * Gneiss. A compound rock, consisting 
 of felspar, quartz, and mica, disposed in 
 slates, from the predominance of the mica 
 scales. Its structure is called by Werner, 
 
 granular-slaty. This geognostic formation 
 is always stratified ; contains sometimes 
 crystals of schorl, tourmaline, and garnet, 
 and is peculiarly rich in metallic ores.* 
 
 Gold is a yellow metal, of specific gra- 
 vity 19.3. It is soft, very tough, ductile, 
 and malleable ; unalterable and fixed, whe- 
 ther exposed to the atmosphere, or to the 
 strongest heat of furnaces. Powerful burn- 
 ing mirrors have volatilized it; and it has 
 been driven up in fumes, in the metallic 
 state, by flame urged upon it by a stream of 
 oxygen gas. The electric shock converts it 
 into a purple oxide, as may be seen by trans- 
 mitting that commotion through gold leaf, 
 between two plates of glass ; or by causing 
 the explosive spark of three or more square 
 feet of coated glass, to fall upon a gilded 
 surface. A hefct of 32° W. or perhaps 
 1500° F. is required to melt it, which does 
 not happen till after ignition. Its colour 
 when melted, is of a bluish-green ; and the 
 same colour is exhibited, by light transmit- 
 ted through gold leaf. 
 
 The limits of the ductility and malleability 
 of gold are not known. 
 
 The method of extending gold used by 
 the gold-beaters, consists in hammering a 
 number of thin rolled plates between skins 
 or animal membranes. By the weight and 
 measure of the best wrought gold leaf, it is 
 found, that one grain is made to cover 56j 
 square inches ; and from the specific gravity 
 of the metal, together with this admeasure- 
 ment, it follows, that the leaf itself is 
 
 gWddO P art °f an inch thick. This, how- 
 ever, is not the limit of the malleability of 
 gold ; for the gold-beaters find it necessary 
 to add three grains of copper in the ounce 
 to harden the gold, which otherwise would 
 pass round the irregularities of the newest 
 skins, and not over them ; and in using the 
 old skins, which are not so perfect and 
 smooth, they proceed so far as to add twelve 
 grains. The wire which is used by the lace- 
 makers, is drawn from an ingot of silver, 
 previously gilded. In this way, from the 
 known diameter of the wire, or breadth 
 when flattened, and its length, together with 
 the quantity of gold used, it is found, by 
 computation, that the covering of gold is 
 only one 12th part of the thickness of gold- 
 leaf, though it still is so perfect as to 
 exhibit no cracks when viewed by a micro- 
 scope. 
 
 No acid acts readily upon gold but aqua 
 regia, and aqueous chlorine. Chromic acid 
 added to the muriatic, enables it to dissolve 
 gold. 
 
 The small degree ot concentration, ot 
 which aqueous chlorine is susceptible, and 
 the imperfect action of the latter acids, ren- 
 der aqua regia the most convenient solvent 
 for this metal. 
 
 When gold is immersed in aqua regia. 
 
GOL 
 
 GOL 
 
 nn effervescence takes place; the solution 
 tinges animal matters of a deep purple, and 
 corrodes them. By careful evaporation, fine 
 crystals of a topaz colour are obtained. The 
 gold is precipitated from its solvent, by a 
 great number of substances. Lime and mag- 
 nesia precipitate it in the form of a yellowish 
 powder. Alkalis exhibit the same appear- 
 ance ; but an excess of alkali redissolves the 
 precipitate. The precipitate of gold obtain- 
 ed from aqua regia by the addition of a fixed 
 alkali, appears to be a true oxide, and is so- 
 luble in the sulphuric, nitric, and muriatic 
 acids ; from which, however, it separates by 
 standing, or by evaporation of the acids. 
 Gallic acid precipitates gold of a reddish 
 colour, very soluble in the nitric acid, 
 to which it communicates a fine blue co- 
 lour. 
 
 Ammonia precipitates the solution of gold 
 much more readily than fixed alkalis. This 
 precipitate, which is of a brown, yellow, or 
 orange colour, possesses the property of de- 
 tonating with a very considerable noise 
 when gently heated. It is known by the 
 name of fulminating gold. The presence of 
 ammonia is necessary to give the fulminat- 
 ing property to the precipitate of gold ; and 
 it will be produced by precipitating it with 
 fixed alkali, from an aqua regia previously 
 made by adding sal ammoniac to nitric acid; 
 or by precipitating the gold from pure aqua 
 regia, by means of sal ammonia, instead of 
 the ammonia alone. The fulminating gold 
 weighs one-fourth more than the gold made 
 use of. A considerable degree of precaution 
 is necessary in preparing this substance. It 
 ought not to be dried but in the open air, at 
 a distance from a fire, because a very gentle 
 heat may cause it to explode. Several fatal 
 accidents have arisen from its explosion, 
 in consequence of the friction of ground 
 stoppers in bottles containing this substance, 
 of which a small portion remained in the 
 neck. 
 
 Fulminating gold, when exposed by Ber- 
 thollet to a very gentle heat in a copper 
 tube, with the pneumatical apparatus of 
 mercury, was deprived of its fulminating 
 quality, and converted into an oxide at the 
 same time that ammoniacal gas was disen- 
 gaged. From this dangerous experiment it 
 is ascertained, that fulminating gold consists 
 of oxide of gold combined with ammonia. 
 The same eminent philosopher caused ful- 
 minating gold to explode in copper vessels. 
 Nitrogen gas was disengaged, a few drops 
 of water appeared, and the gold was re- 
 duced to the metallic form. In this experi- 
 ment he infers, that the ammonia was de- 
 composed ; that the nitrogen, suddenly as- 
 suming the elastic state, caused the explo- 
 sion, while the oxygen of the oxide united 
 'vith the hydrogen of the alkali, and formed 
 the water. 
 
 This satisfactory theory was still farther 
 confirmed by the decomposition of fulminat- 
 ing gold, which takes place in consequence 
 of the action of the concentrated sulphuric 
 acid, of melted sulphur, fat oils, and ether ; 
 all which deprived it of its fulminating qua- 
 lity, by combining with its ammonia. 
 
 Sulphurets precipitate gold from its sol- 
 vent, the alkali uniting with the acid, and 
 the gold falling down combined with the 
 sulphur ; of which, however, it may be de- 
 prived by moderate heat. 
 
 Most metallic substances precipitate gold 
 from aqua regia : lead, iron, and silver, pre- 
 cipitate it of a deej) and dull purple colour ; 
 copper and iron throw it down in its me- 
 tallic state ; bismuth, zinc, and mercury, like- 
 wise precipitate it. A plate of tin, immers- 
 ed in a solution of gold, affords a purple 
 powder, called the purple powder of Cassius, 
 which is used to paint in enamel. 
 
 Ether, naphtha, and essential oils, take 
 gold from its solvent, and from liquors, 
 which have been called potable gold. Ihe 
 gold which is precipitated by evaporation of 
 these fluids, or by the addition of sulphate 
 of iron to the solution of gold, is of tiie ut- 
 most purity. 
 
 Most metals unite with gold by fusion. 
 With silver it forms a compound, which is 
 paler in proportion to the quantity of silver 
 added. It is remarkable, that a certain pro- 
 portion, for example, a fifth part, renders it 
 greenish. From this circumstance, as well 
 as from that of a considerable proportion of 
 these metals separating from each other by 
 fusion, in consequence of their different spe- 
 cific gravities, when their proportions do not 
 greatly differ, it should seem, that their 
 union is little more than a mere mixture 
 without combination ; for, as gold leaf trans- 
 mits the green rays of light, it will easily 
 follow, that particles of silver, enveloped in 
 particles of gold, will reflect a green instead 
 of a white light. 
 
 A strong heat is necessary to combine 
 platina with gold : it greatly alters the co- 
 lour of the gold, if its weight exceed the 
 forty-seventh part of the mass. 
 
 Mercury is strongly disposed to unite 
 with gold, in all proportions with which it 
 forms an amalgam : this, like other amal- 
 gams, is softer the larger the proportion of 
 mercury. It softens and liquefies by heat, 
 and crystallizes by cooling. 
 
 Lead unites with gold, and considerably 
 impairs its ductility, one-fourth of a grain to 
 an ounce rendering it completely brittle. 
 Copper renders gold less ductile, harder, 
 more fusible, and of a deeper colour. This 
 is the usual addition in coin, and other ar- 
 ticles used in society. Tin renders it brittle 
 in proportion to its quantity ; but it is a com- 
 mon error of chemical writers to say, that the 
 slightest addition is sufficient for this pur- 
 
GOU 
 
 GRA 
 
 pose. When alloyed with tin, however, it 
 will not bear a red heat. With iron it forms 
 a grey mixture, which obeys the magnet. 
 1 his metal is very hard, and is said to be 
 much superior to steel for the fabrication of 
 cutting instruments. Bismuth renders gold 
 white and brittle ; as do likewise nickel, 
 manganese, arsenic, and antimony. Zinc 
 produces the same effect ; and, when equal 
 in weight to the gold, a metal of a fine grain 
 is produced, which is said to be well adapted 
 to form the mirrors of reflecting telescopes, 
 on account of the fine polish it is susceptible 
 of, and its not being subject to tarnish. The 
 alloys of gold with molybdena are not known. 
 It could not be mixed with tungsten, on ac- 
 count of the infusibility of this last substance. 
 Mr Hatchett gives the following order of 
 different metals, arranged as they diminish 
 the ductility of gold : bismuth, lead, anti- 
 mony, arsenic, zinc, cobalt, manganese, nic- 
 kel, tin, iron, platina, copper, silver. The 
 first three were nearly equal in effect ; and 
 die platina was not quite pure. 
 
 For the purposes of coin Mr Hatchett 
 considers an alloy of equal parts of silver and 
 copper as to be preferred, and copper alone 
 as preferable to silver alone. 
 
 * The peroxide of gold thrown down by 
 potash, from a solution of the neutral muri- 
 ate, consists, according to Berzelius, of 100 
 gold and 12 oxygen. It is probably a trit- 
 oxide. The protoxide-of a greenish colour, 
 is procured by treating with potash-water 
 muriate of gold, after heat has expelled the 
 chlorine. It seems to consist of 100 metal 
 + 4 oxygen. The prime equivalent of gold 
 comes out apparently 25.* 
 
 The gold coins of Great Britain contain 
 eleven parts of gold, and one of copper. See 
 Assay, Gilding, and Ores of Gold. 
 
 * Gorgonia Norilis. The red coral. It 
 consists of an interior stem, composed of 
 gelatinous matter and carbonate of lime, with 
 a cortex, consisting of membrane with car- 
 bonate of lime, coloured by some unknown 
 substance. * 
 
 Goulard’s Extract. A saturated solu- 
 tion of subacetate of lead. See Lead. 
 
 * Gouty Concretions. These have been 
 called chalk-stones from their appearance, 
 but Dr Wollaston first demonstrated their 
 true composition to be uric acid, combined 
 with ammonia, and thus explained the mysteri- 
 ous pathological relation between gout and 
 gravel. See Concretion (Urinary). 
 
 Gouty concretions are soft and friable. 
 They are insoluble in cold, but slightly in 
 boiling water. An acid being added to this 
 solution, seizes the soda, and the uric acid 
 is deposited in small crystals. These con- 
 cretions dissolve readily in water of potash. 
 An artificial compound may be mado by 
 triturating uric acid and soda with warm 
 water, which exactly resembles gouty con- 
 cretions, in its chemical constitution. * 
 
 * Grainer. The lixivium obtained 11 
 infusing pigeons’ dung in water, is used flj 
 giving flexibility to skins in the process || \ 
 tanning, and is called the grainer.* 
 
 * Grammatite. See Tremolite.* 
 
 * Granatite. See Grenatite.*. 
 
 * Granite. A compound rock, consist! 
 ing of quartz, felspar, and mica, each crystuli 
 lized and cohering by mutual affinity, witl I 
 out any basis or cement. The felspar conli 
 monly predominates, and the mica is in smal 1 
 est quantity. The colours of the felspar ail 1 
 white, red, grey, and green. The quartz I 
 light grey, and the mica dark. The granuh || 
 crystals vary exceedingly in size, in differei ll 
 granite rocks. Occasionally granite is stn j 
 titied ; but sometimes no stratification can t J r 
 perceived. Large globular masses, calle I , 
 rolling stones, are frequently met with, con J i 
 posed each of concentric lamellar concrcll 
 tions. Schorl, garnet, and tinstone, are frell 
 quently present in granite. Tin and iron 
 are the only metals abundantly found in th;|| 
 rock. It contains molybdena, silver, coppei || 
 lead, bismuth, arsenic, titanium, tungstei I 
 and cobalt. It is, however, poorer in orel 
 than many other rock formations.* 
 
 Granulation; the method of dividin I 
 metallic substances into grains or small par jj 
 tides, in order to facilitate their combination ! 
 with other substances, and sometimes fol 
 the purpose of readily subdividing them b | 
 weight. 
 
 This is done either by pouring the melted 
 metal into water, or by agitating it in a bo: I 
 until the moment of congelation, at which inj 
 stant it becomes converted into a powder. 
 
 Various contrivances are used to prevent! 
 danger, and insure success, in the several 
 manufactories that require granulation. Cop 1 
 per is granulated for making brass, by pour I 
 ing it through a perforated ladle into a cover | 
 ed vessel of water with a moveable fals* | 
 bottom. A compound metal, consisting 
 chiefly of lead, is poured into water througll 
 a perforated vessel of another kind, for mak I 
 ing small-shot, in which the height above tin 
 surface of the fluid requires particular ad I 
 justment. In a new manufactory of thiil 
 kind, the height is upward of 100 feet. 
 
 * Graphite. llhomboidal graphite o j 
 Jameson, or plumbago, of which he give:! 
 two sub-species, the scaly and compact. 
 
 1st, Seal y Graphite. Colour dark steel- 1 
 grey, approaching to iron-black. It occur?! 
 massive, disseminated and crystallized. Thtj 
 primitive form is a rhomboid. 1 he second- 1 
 ary form is the equiangular six-sided table J 
 Lustre splendent, metallic. Cleavage single | 
 Fracture scaly foliated. Streak shining an< I 
 metallic. Hardness sometimes equal to tha , | 
 of gypsum. 
 
 Perfectly sectile. Rather difficultly fran-l 
 gible. It writes and soils. Streak on paper I 
 black. Feels very greasy. Sp. gr. Iron I 
 1.9 to 2,4. 
 
GRE 
 
 GUI 
 
 2d, Compact Graphite . Colour rather 
 
 blacker than preceding. Massive, disseminat- 
 ed and in columnar concretions. Internal 
 lustre glimmering and metallic. Fracture 
 small grained uneven, passing into conchoidah 
 When heated in a furnace, it burns without 
 flame or smoke, forming carbonic acid, and 
 leaving a residuum of iron. Its constituents 
 are, carbon 91, iron 9. — Berthollet. It some- 
 times contains nickel, chromium, manganese, 
 and oxide of titanium. It usually occurs in 
 beds, sometimes disseminated and in imbedded 
 masses, in granite, gneiss, mica- slate, clay- 
 slate, foliated granular limestone, coal and 
 trap formations. It is found in gneiss in 
 Glen Strath Farrar in Inverness-shire; in the 
 coal formation near Cumnock in Ayrshire, 
 where it is imbedded in greenstone, and in 
 columnar glance-coal. At Borrodale in 
 Cumberland, it occurs in beds of very vary- 
 ing thickness, included in a bed of trap, which 
 is subordinate to clay-slate ; and in many 
 places on the continent, and elsewhere. 
 The finer kinds are first boiled in oil, and 
 then cut into tables for pencils. Grates are 
 blackened with it, and crucibles formed of a 
 mixture of it and clay. — Jameson.* 
 
 Gravity, a term used by physical writers 
 to denote the cause, by which all bodies move 
 toward each other, unless prevented by some 
 other force or obstacle. See Attraction. 
 
 Gravity (Specific). See Specific Gra- 
 vity. 
 
 For the specific gravities of different kinds 
 of elastic fluids, see the table at the article 
 Gas. 
 
 * Greywacke. A mountain formation, 
 consisting of two similar rocks, which alter- 
 nate with, and pass into each other, called 
 greywacke, and greywacke- si ate. The first 
 possesses the characters of the formation. It 
 is a rock composed of pieces of quartz, flinty- 
 slate, felspar, and cl ay- slate, cemented by a 
 clay-slate basis. These pieces vary in size 
 from a hen’s egg to little grains. When the 
 texture becomes exceedingly fine grained, 
 the rock constitutes greywacke-slate. Its 
 colour is usually ash or smoke-grey, with- 
 out the yellowish- grey, or greenish-tinge, fre- 
 quent in primitive slate. It has not the con- 
 tinuous lustre of primitive slate, but glim- 
 mers from interspersed scales of mica. It 
 contains quartz veins, but no beds of quartz. 
 Petrefactions are found in it. These rocks 
 are stratified, forming, when alone, round- 
 backed hills, with deep valleys between them. 
 Immense beds of trap, flinty-slate, and tran- 
 sition limestone, are contained in this forma- 
 tion ; as well as numerous metallic ores in 
 beds and large veins.* 
 
 * Greek Fire. Asphaltum is supposed 
 to have been its chief constituent, along with 
 nitre and sulphur.* 
 
 * Green- earth. Colour celandine- green, 
 and green of darker shades. Massive, and 
 
 In globular and amygdaloidal shaped pieces, 
 sometimes hollow, or as encrusting agate balls. 
 Dull. Fracture earthy. Opaque. Feebly 
 glistening in the streak. Soft and sectile. 
 Rather greasy. Adheres slightly to the tongue. 
 Sp. gr. 2.6. Before the blow-pipe, it is 
 converted into a black vesicular slag. Its 
 constituents are silica 53, oxide of iron 28, 
 magnesia 2, potash 10, water 6. It is a fre- 
 quent mineral in the amygdaloid of Scotland, 
 England, Ireland, Iceland, and the Faroe 
 Islands. It occurs in Saxony, near Verona, 
 the Tyrol, and Hungary. It is the moun- 
 tain-nreen of artists in water colours. Its 
 
 O * 
 
 colour is durable, but not so bright as that 
 from copper. The green-earth of Verona, of 
 which the analysis is given above, is most 
 esteemed. — Jameson .* 
 
 * Greenstone. A rock of the trap for- 
 mation, consisting of hornblende and felspar, 
 both in the state of grains, or small crystals. 
 The hornblende is commonly most abundant, 
 and communicates a green tinge to the fel- 
 spar. * 
 
 * Guiacum. A resinous looking sub- 
 stance, extracted from the very dense wood 
 of a tree growing in the West Indies, called 
 
 guiacum ojfficinale. 
 
 It differs however from resins in its habi- 
 tudes with nitric acid, as Mr Hatchett first 
 shewed. Its sp. gr. is 1.229. Its colour is 
 yellowish- brown, but it becomes green on 
 exposure to light. It is transparent and 
 breaks with a resinous fracture. Its odour is 
 not disagreeable, but when a very little of its 
 powder, mixed with water, is swallowed, it 
 excites a very unpleasant burning sensation 
 in the fauces and stomach. Heat fuses it, 
 with the exhalation of a somewhat fragrant 
 smell. 
 
 Water dissolves a certain portion of it, ac- 
 quiring a brownish tinge, and sweetish taste. 
 The soluble matter is left when the water is 
 evaporated. It constitutes 9 per cent of the 
 whole, and resembles what some chemists 
 call extractive. 
 
 Guiacum is very soluble in alcohol. This 
 solution, which is brown coloured, is decom- 
 posed by water. Aqueous chlorine throws 
 down a pale blue precipitate from it. 
 
 Guiacum dissolves readily in alkaline leys, 
 and in sulphuric acid ; and in the nitric with 
 effervescence. From the solution in the last 
 liquid, oxalic acid may be procured by eva- 
 poration, but no artificial tannin can be ob- 
 tained, as from the action of nitric acid on the 
 other resins. 
 
 Guiacum distilled in close vessels, leaves 
 SO. 5 per cent of charcoal, being nearly 
 double the quantity from an equal weight of 
 the common resins. From Dr Wollaston’s 
 experiments, it would appear that both air 
 and light are necessary to produce the change 
 in guiacum from yellow to green. And Mr 
 Braude found that this green colour was 
 
GUN 
 
 GUN 
 
 more rapidly brought on in oxygon, than in 
 common air. With nitric acid, or chlorine, 
 it becomes green, next blue, and lastly 
 brown.* 
 
 formerly guiacum was much commend- 
 ed in siphilis and other complaints ; at pre- 
 sent it is used chiefly in rheumatism, dis- 
 solved in liquid ammonia. 
 
 Guano. A substance found on many of 
 the small islands in the South Sea, which are 
 the resort of numerous flocks of birds, par- 
 ticularly of the ardea and phamicopteros 
 genus. It is dug from beds 50 or 60 feet 
 thick, and used as a valuable manure in 
 Peru, chiefly for Indian corn. It is of a 
 dirty yellow colour, nearly insipid to the 
 taste, but has a powerful smell partaking of 
 castor and valerian. According to the ana- 
 lysis of Fourcroy and Vauquelin, about one- 
 fourth of it is uric acid partly saturated with 
 ammonia and lime. It contains likewise 
 oxalic acid, partly saturated with ammonia 
 and potash ; phosphoric acid combined with 
 the same bases and with lime ; small quan- 
 tities of sulphate and muriate of potash, and 
 ammonia ; a small portion of fat matter ; 
 and sand, partly quartzose, partly ferruginous. 
 
 Gum. The mucilage of vegetables. The 
 principal gums are, 1. The common gums, 
 obtained from the plum, the peach, the cherry 
 tree, Sec. — 2. Gum Arabic, which flows na- 
 turally from the acacia in Egypt, Arabia, 
 and elsewhere. This forms a clear trans-, 
 parent mucilage with water. — 3. Gum Se- 
 neca, or Senegal. It does not greatly differ 
 from gum Arabic: the pieces are larger 
 and clearer ; and it seems to communicate a 
 higher degree of the adhesive quality of water. 
 It is much used by calico-printers and others. 
 The first sort of gums are frequently sold by 
 this name, but may be known by their darker 
 colour. — 4. Gum Adragant or Tragacanth. 
 It is obtained from a small plant of the same 
 name growing in Syria, and other eastern 
 parts. It comes to us in small white con- 
 torted pieces resembling worms. It is usu- 
 ally dearer than other gums, and forms a 
 thicker jelly with water. 
 
 Mr Willis has found, that the root of the 
 common blue-bell, hyacintbus non scriptus, 
 dried and powdered, affords a mucilage, 
 possessing all the qualities of that from gum 
 Arabic. Lord Dundonald has extracted a 
 mucilage also from lichens. 
 
 Gums treated with nitric acid afford the 
 acid of sugar. 
 
 Gum (Elastic). See Caoutchouc. 
 
 Gum Resin. The principal gum resins 
 are frankincense, scammony, asafcctida, aloes, 
 gum ammoniac, and gamboge. 
 
 Gunpowder. This well known powder 
 is composed of 75 parts, by weight, of nitre, 
 16 of charcoal, and 9 of sulphur, intimately 
 blended together by long pounding in wooden 
 
 mortars, with a small quantity of water. 
 This proportion of the materials is the mosi 
 effectual. But the variations of strength in 
 different samples of gunpowder are generally 
 occasioned by the more or less intimate divi- 
 sion and mixture of the parts. The reason 
 of this may be easily deduced from the con- 
 sideration, that nitre does not detonate until 
 in contact with inflammable matter; whence 
 the whole delonation will be more speedy, 
 the more numerous the surfaces of contact. 
 The same cause demands, that the ingredi- 
 ents should be very pure, because the mix- 
 ture of foreign matter not only diminishes 
 the quantity of effective ingredients which it 
 represents, but likewise prevents the contacts 
 by its interposition. 
 
 The nitre of the third boiling is usually 
 chosen for making gunpowder, and the 
 charcoal of light woods is preferred to that 
 of those which are heavier, most probably 
 because this last, being harder, is less pulve- 
 rable. 
 
 The requisite peunding of the materials is 
 performed in the large way by a mill, in 
 which w’oeden mortars are disposed in rows, 
 and in each of which a pestle is moved by 
 the arbor of a water-w'heel ; it is necessary 
 to moisten the mixture from time to time 
 with water, which serves to prevent its being 
 dissipated in the pulverulent form, and like- 
 wise obviates the danger of explosion from 
 the heat occasioned by the blows. Tw r elve 
 hours’ pounding is in general required to 
 complete the mixture ; and when this is 
 done, the gunpowder is in fact made, and 
 only requires to be dried to render it fit for 
 use. 
 
 The granulation of gunpowder is per- 
 formed by placing the mass, while in the 
 form of a stiff paste, in a wire sieve, cover- 
 ing it with a board, and agitating the whole ; 
 by this means it is cut into small grains or 
 parts, which, when of a requisite dryness, 
 may be rendered smooth or glossy by rolling 
 them in a cylindrical vessel or cask. Gun- 
 powder in tins form takes fire more speedily 
 than if it be afterw ard reduced to powxler, as 
 may be easily accounted for from the cir- 
 cumstance, that the inflammation is more 
 speedily propagated through the interstices 
 of the grains. But the process of granula- 
 tion does itself, in all probability, weaken 
 the gunpowder, in the same manner as it is 
 weakened by suffering it to become damp ; 
 for, in this last case, the nitre, which is the 
 only soluble ingredient, suffers a partial so- 
 lution in the water, and a separation in crys- 
 tals of greater or less magnitude ; and ac- 
 cordingly the surfaces of contact are render- 
 ed less numerous. 
 
 Berthollet found, that the elastic product, 
 afforded by the detonation of gunpowder, 
 consisted of two parts nitrogen gas, and one 
 
GYP 
 
 GYP 
 
 carbonic acid gas. The sudden extrication 
 and expansion of these airs are the cause of 
 the effects of gunpowder. 
 
 * Gypsum. This genus contains 2 spe- 
 cies, by Professor Jameson ; the prismatic, 
 and the axifrangible. 
 
 I . — Prismatic gypsum or anhydrite . Mu- 
 riacit. — Werner. Of this there are 5 sub- 
 
 species. 
 
 1. Sparry anhydrite. See Cube-STAK. 
 
 2. Scaly anhydrite. Colour white of va- 
 rious shades passing into smalt-blue. Mas- 
 sive, and in granular concretions. Lustre 
 splendent, pearly. Cleavage imperfect and 
 curved. Translucent on the edges. Easily 
 broken. Sp.gr. 2.96. Its constituents are, 
 lime 41.75, sulphuric acid 55, mur. of soda 
 ] .0. It is found in the salt mines of the 
 Tyrol, 5088 feet above the level of the sea. 
 
 5. Fibrous anhydrite. Colours, red, blue, 
 and grey. Massive, and in coarse fibrous 
 concretions. Lustre, glimmering and pearly. 
 Translucent on the edges. Rather easily 
 frangible. Spec. grav. 3. It is found in 
 the salt mines on the continent. The blue 
 is sometimes cut into ornaments. 
 
 4. Convoluted anhydrite. Colour, dark 
 milk-white. Massive, and in distinct con- 
 cretions. Lustre, glimmering and pearly. 
 Fracture fine splintery. Translucent on the 
 edges. Sp.gr. 2. 85. Its constituents are, 
 42 lime, 56.5 sulphuric acid, 0.25 muriate 
 of soda. It occurs in the salt mines of 
 Bochnia, and at Wieliczka in Poland. It 
 has been called picrre de tripes , from its con- 
 voluted concretions. 
 
 5. Compact anhydrite. Colour grey, some- 
 times with spotted delineations. Massive, 
 and in distinct granular concretions. Fee- 
 bly glimmering. Fracture small splintery. 
 Translucent. Hardness and constituents as 
 in the preceding. Sp. gr. 2.95. 
 
 II . — Axifrangible gypsum. 
 
 This species contains, according to Pro- 
 fessor Jameson, 6 sub-species; sparry gyp- 
 sum, foliated, compact, fibrous, scaly foliated, 
 and earthy gypsum. 
 
 1. Sparry gypsum or selenite. Colours, 
 grey, white, and yellow, with occasional 
 iridescence. Massive, disseminated, and 
 crystallized. Its primitive form is an oblique 
 four-sided prism, with angles of 113° 8' 
 and 66° 5 l 2l . The following are some of 
 the secondary forms: 1. Six-sided prism, 
 generally broad, and oblique angular, and 
 four smaller lateral planes. 2. Lens. 3. 
 Twin crystals, formed either by two lenses, 
 or by two six-sided prisms, pushed into each 
 other in the direction of their breadth. 4. 
 Quadruple crystal, from two twin crystals 
 pushed into each other in the direction of 
 their length. Lustre splendent, pearly. 
 C leavage threefold. Fragments rhomboidal. 
 Semi-transparent, and transparent. Refracts 
 double, fields to the nail. Scratches talc, 
 
 but not calcareous spar. Sectile. Easily 
 frangible. In thin pieces flexible, but inelas- 
 tic. Sp. gr. 2.3. It exfoliates and melts 
 into a white enamel, which falls into a white 
 powder. Its constituents are, 33.9 lime, 
 4.3.9 sulphuric acid, 21 water, and 2.1 loss; 
 Bucliolz. It occurs principally in the floetz 
 gypsum formation in thin layers ; Jess fre- 
 quently in rock salt ; frequently in the Lon- 
 don blue clay. Crystals are daily forming 
 in gypsum hills, and in old mines. It is 
 found in blue clay, at Shotover-hill, near 
 Oxford ; Newhaven, Sussex ; around Paris, 
 and all over the continent. It was used in 
 ancient times for window-glass. Hence it 
 was called glacies marine, and lapis specula- 
 ris. 
 
 2. Foliated granular gypsum. Colours, 
 white, grey, and red ; sometimes in spotted 
 or striped delineations. Massive, and in 
 distinct concretions, or crystallized in small 
 conical lenses. Lustre, glistening, pearly. 
 Cleavage as selenite. Translucent. Very 
 soft, sectile, and easily frangible. Sp. gr. 2.3. 
 Its constituents are, 32 lime, 30 sulphuric 
 acid, and 38 water, according to Kirwan. 
 It occurs in beds in primitive rocks, as gneiss 
 and mica-slate; in transition clay-slate; but 
 most abundantly in beds in the rocks of the 
 floetz class. It is there associated with sele- 
 nite, compact gypsum, fibrous gypsum, rock- 
 salt, stinkstone, and limestone. It is found 
 in Cheshire and Derbyshire, at Liineburg, 
 and other places on the continent. The 
 foliated and compact gypsum, when pure 
 and capable of receiving a good polish, are 
 termed alabaster by artists, who fashion them 
 into statues and vases. The coarser kinds 
 are used in small quantities in agriculture ; 
 and are converted by calcination into stucco. 
 
 3. Compact gypsum. Colours, white of 
 various shades, grey, blue, red, and yellow. 
 Massive. Dull. Fracture fine splintery. 
 Translucent on the edges. Soft, sectile, 
 and easily frangible. Sp. gr. 2.2. Its con- 
 stituents are, 34 lime, 48 sulphuric acid, 18 
 water. — Gerhard. It occurs in beds, along 
 with granular gypsum, Sec. It is found in 
 the Campsie hills; in Derbyshire; at Ferry- 
 bridge, Yorkshire, and in various places on 
 the continent. 
 
 4. Fibrous gypsum. Colours, white, grey, 
 and red. Massive and dentiform, and in 
 fibrous distinct concretions. Lustre, glisten- 
 ing and pearly. Translucent. Soft, sectile, 
 and easily frangible. Its constituents are, 
 53. lime, 44.13 sulphuric acid, 21 water. 
 It occurs along with the other sub-species, 
 in red sandstone near Moffat ; in the Forth 
 river near Belfast; in Cumberland, York- 
 shire, Cheshire, &c. When cut m cabachon, 
 and polished, it reflects a light, not unlike 
 that ol the cat’s eye, and is sometimes sold 
 as that stone. 
 
 5. Scaly foliated gypsum. Colour white. 
 
 47 
 
HEA 
 
 HE A 
 
 Massive, disseminated, and in distinct con- 
 cretions. Lustre, glistening and pearly. 
 Fracture small scaly foliated. Opaque, or 
 translucent on the edges. Soft, passing in- 
 to friable. Sectile and easily frangible. It 
 occurs along with selenite, at Montmartre 
 near Paris, in the third lloetz formation of 
 Werner. 
 
 6. Earthy gypsum. Colour yellowish- 
 white. Composed of fine scaly or dusty 
 particles. Feebly glimmering. Feels mea- 
 gre or rather fine. Soils slightly. Light. 
 It is found immediately under the soil in 
 beds several feet thick, resting on gypsum, 
 in Saxony, Switzerland, and Norway* — Ja- 
 meson. * 
 
 HEMATITES. An ore of iron.* 
 Hair. From numerous experi- 
 ments M. Vauquelin infers, that black hair 
 is formed of nine different substances, name- 
 
 iy; 
 
 1. An animal matter, which constitutes 
 the greater part. 2. A white concrete oil in 
 small quantity. 3. Another oil of a greyish 
 green colour, more abundant than the for- 
 mer. 4. Iron, the state of which in the 
 hair is uncertain. 5. A few particles of 
 oxide of manganese. 6. Phosphate of lime. 
 
 7. Carbonate of lime, in very small quantity. 
 
 8. Silex, in a conspicuous quantity. 9. 
 Lastly, a considerable quantity of sulphur. 
 
 The same experiments shew, that red hair 
 differs from black only in containing a red 
 oil instead of a blackish- green oil ; and that 
 white hair differs from both these only in the 
 oil being nearly colourless, and in containing 
 phosphate of magnesia, which is not found 
 in them. 
 
 * Harmotome. Cross-stone.* 
 
 * Hartshorn, (Spirit of). See Ammo- 
 nia.* 
 
 * Hajjyne. Colour blue of various shades. 
 It occurs imbedded in grains, and rarely 
 crystallized ; in acute oblique double four- 
 sided pyramids, variously truncated. Ex- 
 ternally it is generally smooth, and edges 
 rounded. Lustre splendent, to glistening, and 
 vitreous. Cleavage quintuple. Fracture im- 
 perfect conchoidal. Transparent and translu- 
 cent. Harder than apatite, but softer than 
 felspar. Brittle. Easily frangible. Sp.gr. 
 2.7. It melts with difficulty before the 
 blow-pipe, into a white nearly opaque vesi- 
 cular bead. With borax it melts into a 
 transparent wine-vellow glass. With acids, 
 it forms a transparent jelly. Its constituents 
 are, silica 30, alumina 15, lime 13.5, sul- 
 phuric acid 12, potash 11, iron 1, loss 17.5. 
 — Vauquelin i but by Gmelin, we have sili- 
 ca 55.48, alumina 18.S7, lime 11.79, sul- 
 phuric acid 12.6, potash 15.45, iron 1.16, 
 loss 3.45. It occurs imbedded in the basalt 
 rocks of Albano and Frescati. Professor 
 Jameson thinks it nearly allied to azure- 
 stone. * 
 
 * Heavy Spar. Baryte. This genus is 
 divided by Professor Jameson into 4 species ; 
 
 rhomboidal, prismatic, diprismatic, and axi- 
 frangible. 
 
 1. Ilhomhoidal baryte , or Wilherite. Co- 
 lours, white, grey, and yellow. Massive. 
 Disseminated, in various imitative shapes, and 
 crystallized. The primitive form is a rhom- 
 boid of 88° 6' and 91° 54'. The secondary 
 forms are, the equiangular six-sided prism, 
 truncated, or acutely acuminated, and the 
 acute double six-sided pyramid. Prisms 
 scopiformly grouped, or in druses. Lustre 
 glistening, and resinous. Cleavage three- 
 fold. Principal fracture uneven. Translu- 
 cent. Harder than calcareous spar. Easily 
 frangible. Sp. gr. 4.3. Before the blow- 
 pipe it decrepitates slightly, and melts rea- 
 dily into a white enamel ; soluble with effer- 
 vescence in dilute nitric acid. It is carbo- 
 nate of barytes, with occasionally 1 per cent 
 of carbonate of strontites and sulphate of 
 barytes. It occurs in Cumberland and Dur- 
 ham, in lead veins that traverse a secondary 
 limestone, which rests on red sandstone. It 
 is an active poison, and is employed for kill- 
 ing rats. 
 
 2. Prismatic baryte, or Heavy spar. Of 
 this there are 9 sub-species; earthy, com- 
 pact, granular, curved lamellar, straight la- 
 mellar, fibrous, radiated, columnar, and pris- 
 matic. They are all sulphates of barytes in 
 composition. On account of its forms of 
 crystallization, we shall describe the fresh 
 straight lamellar heavy spar. 
 
 Its colours are white, grey, blue, green, 
 yellow, red, and brown. Massive, in distinct 
 concretions, and crystallized. The primitive 
 form is an oblique four-sided prism of 101° 
 53'. The following are the secondary forms : 
 the rectangular four-sided table ; the oblique 
 four-sided table, perfect or variously trun- 
 cated or bevelled ; the longish six-sided table, 
 perfect or bevelled ; the eight-sided table, per- 
 fect or bevelled. Lustre splendent, between 
 resinous and pearly. Cleavage, parallel with 
 the planes of the primitive prism. Frag- 
 ments rhomboidal and tabular. Translucent 
 or transparent, and refracts double. Scratches 
 calcareous spar, but is scratched bv fiuor 
 spar. Brittle. Sp. gr. 4.1 to 4.6. It de- 
 crepitates briskly before the blow-pipe, and 
 then melts into a white enamel. It phos- 
 
HEA 
 
 HEP 
 
 phoresces on glowing coals with a yellow 
 light. It is sulphate of barytes, with 0.85 
 sulphate of strontites, and 80 oxide of iron. 
 It is found almost always in veins, which oc- 
 cur in granite, gneiss, mica-slate, and other 
 rocks. The flesh-red variety is often accom- 
 panied with valuable ores. In Great Bri- 
 tain, it occurs in veins of different primitive 
 and transition rocks, and in secondary lime- 
 stone, &c. in the lead mines of Cumberland, 
 Durham, and Westmoreland. 
 
 3. Z)i-prismatic baryte , or Strontianile . — 
 Colour, pale asparagus- green, yellowish- 
 white, and greenish-grey. Massive, in dis- 
 tinct concretions, and crystallized. The pri- 
 mitive form is an oblique four-sided prism, 
 bevelled on the extremities. Secondary 
 figures are, the acicular six-sided prism, and 
 the acicular acute double six-sided pyramid. 
 Lustre glistening or pearly. Cleavage, in 
 the direction of the lateral planes of the pri- 
 mitive form. Fracture fine grained uneven. 
 Translucent. Harder than calcareous spar, 
 but softer than fluor. Brittle. Sp. gr. 3.7. 
 Infusible before the blow-pipe, but becomes 
 white and opaque, tingeing the flame of a dark 
 purple colour. It is soluble with efferves- 
 cence in dilute nitric or muriatic acid ; and 
 paper dipped in the solutions thus produced, 
 burns with a purple flame. Its constituents 
 are, 
 
 Strontian, 
 
 61.21 
 
 69.5 
 
 62.0 
 
 74.0 
 
 Carbonic acid, 
 
 50.20 
 
 30.0 
 
 50.0 
 
 25.0 
 
 Water, 
 
 8.50 
 
 0.5 
 
 8.0 
 
 0.5 
 
 
 100.0 
 
 100.0 
 
 100.0 
 
 100.0 
 
 Hope. Klapr . Telle. Bucholz. 
 
 It occurs at Strontian in Argyllshire, in 
 veins that traverse gneiss, along with galena, 
 heavy spar, and calcareous spar. “ The pe- 
 culiar earth which characterizes this mineral, 
 was discovered by Dr Hope, and its various 
 properties were made known to the public in 
 his excellent Memoir on Strontites, inserted 
 in the Transactions of the Royal Society of 
 Edinburgh, for the year ] 790.”— Jameson, 
 vol. ii. whose account of the preceding spe- 
 cies, is a model of mineralogical description. 
 
 4. Axifrangrble baryte , or Cclestine. — Of 
 this there are five sub-species ; foliated, pris- 
 matic, fibrous, radiated, and fine granular. 
 We shall describe the foliated, and refer to 
 Professor Jameson’s work for the rest. 
 
 Colours white, grey, blue, and flesh-red. 
 Massive, in lamellar concretions, and crys- 
 tallized ; in the rectangular four-sided table, 
 in which the terminal planes are bevelled, 
 and in the rectangular four-sided table, be- 
 velled on the terminal edges. Lustre splen- 
 dent, pearly. Cleavage threefold. Frac- 
 ture uneven ; fragments rhomboidal. Trans- 
 lucent. Scratches calcareous spar, but is 
 scratched by fluor spar. Sectile, and easily 
 frangible. Sp. gr. 5.9. It melts before the 
 blow-pipe into a white friable enamel, with- 
 
 o 
 
 out very sensibly tingeing the flame. It is 
 sulphate of strontites, with about 2 per cent 
 of sulphate of barytes. It occurs in trap- 
 tuff, in the Calton-hill at Edinburgh, and in 
 red sandstone at Inverness. It is abundant 
 in the neighbourhood of Bristol. — Jameson . * 
 
 Heat. See Caloric. 
 
 * Heliotrope. A sub-species of rhom- 
 boidal quartz. Colour, green of various 
 shades. The blood and 6carlet-red, and the 
 ochre- yellow dots and spots, are owing to 
 disseminated jasper. Massive, and in angu- 
 lar and rolled pieces. Lustre glistening, re- 
 sinous. Fracture conchoidal. Translucent 
 on the edges. Easily frangible. Hard, 
 but softer than calcedony. Rather heavy. 
 Sp. gr. 2.65. It is infusible before the 
 blow-pipe. Its constituents are, silica 84, 
 alumina 7.5, and iron 5. It is found in 
 rocks belonging to the secondary trap forma- 
 tion. The finest heliotrope comes from 
 Bucharia and Siberia. A variety is found in 
 the island of Rume in Scotland. It is cut 
 into seals and snuff-boxes. The Siberian 
 wants the red spots. — Jameson .* 
 
 Heliotrotium. Turnsole. See Archil. 
 
 * Hellebore. The root of a plant formerly 
 used in medicine, but now nearly discarded 
 from practice, in consequence of the violence 
 of its operation. Vauquelin ascribes its 
 acrimony to a peculiar oil, which he separat- 
 ed from the infusion in alcohol, by distilling 
 off the latter. It is very poisonous. Orfila 
 says, on the contrary, that the poisonous qua- 
 lity of hellebore root resides in a principle 
 soluble in water ; that the powdered root is 
 more certainly fatal, when applied to a 
 wound, than when swallowed ; that the 
 white hellebore is more active than the 
 black ; and that the alkaline extract, which 
 forms a part of the tonic pills of Bacher, is 
 also very powerful. Vomiting is the only 
 antidote.* 
 
 * Hematjn. The colouring principle of 
 logwood, the hematoxylon campechianum of 
 botanists. 
 
 On the watery extract of logwood, digest 
 alcohol for a day, filter the solution, evapo- 
 rate, add a little water, evaporate gently 
 again, and then leave the liquid at rest. 
 Hematin is deposited in small crystals, which 
 after washing with alcohol, are brilliant, and 
 of a reddish-white colour. Their taste is 
 bitter, acrid, and slightly astringent. 
 
 Hematin forms an orange- red solution 
 with boiling water, becoming yellow as it 
 cools, but recovering, with increase of heat, 
 its former hue. Excess of alkali converts it 
 first to purple, then to violet, and lastly, to 
 biown : in which state the hematin seems to 
 be decomposed. Metallic oxides unite with 
 hematin, forming a blue-coloured compound. 
 Gelatin throws down reddish flocculi. Per- 
 oxide of tin, and acid, merely redden it.* 
 Hepar Sulphujus. A name anciently 
 
HOR 
 
 HOR 
 
 given to tilkaline nmi earthy sulphurets, from 
 tJieir liver-brown colour.* 
 
 Hepatic Air. Sulphuretted hydrosen 
 gas. * 
 
 * Hepatite, Fetid, straight, lamellar, 
 heavy spar. A variety of lamellar barytes, 
 containing a minute portion of sulphur; in 
 consequence of which, when it is heated or 
 rubbed, it emits a fetid sulphurous odour.* 
 
 * Highgate Resin. See Fossil Copal.* 
 
 * Hollow Spar. Chiast elite.* 
 
 * Holmite. A new mineral, which oc- 
 curs crystallized in the form of an oblique 
 four-sided prism, and having a sp. gr. of 3.597. 
 Its constituents are 27 lime, 21 carbonic 
 acid, 6-| alumina, 6 \ silica, 29 oxide of iron, 
 and 10 water,* 
 
 * Hone. The whet-slate of mineralo- 
 gists.* 
 
 * IIonet. It is supposed to consist of 
 sugar, mucilage, and an acid. * 
 
 * Honey-Stone. Mellite. Crystal- 
 Harz of Mohs; the pyramidal honey-stone 
 of Jameson. Colour, honey-yellow. Rare- 
 ly massive, but very distinctly crystallized. 
 The primitive form, is a pyramid of 118° 4' 
 and 93° 22'. The following are some of 
 the secondary figures: l.sf, The primitive 
 pyramid, truncated on the apices, or on the 
 apices and angles ; 2d, These truncations 
 giving rise to a low rectangular four-sided 
 prism, or to an irregular rhomboidal dode- 
 cahedron ; 3d, The angles in the common 
 base flatly bevelled. Lustre splendent. 
 Cleavage pyramidal. Fracture conchoidal. 
 Semi-transparent. Refracts double. Hard- 
 er than gypsum, but not so hard as calcareous 
 spar. Brittle. Sp. gr. 1.56. Before the 
 blow-pipe it becomes white and opaque, with 
 black spots, and is at length reduced to ashes. 
 Heated in a glass tube, it becomes black. 
 Friction makes it slightly resino- electric. 
 Its constituents are, 16 alumina, 46 mellitic 
 acid, and 38 water. 
 
 It occurs superimposed on bituminous 
 wood and earth coal, and is usually accom- 
 panied with sulphur, at Artern in Thuringia. 
 See the sequel of amber, for the criteria be- 
 tween it and mellite,* 
 
 * HomheRc/s Pykopiiorus. Ignited mu- 
 riate of lime.* 
 
 * Hoofs of Animals. Coagulated albu- 
 men, like horn.* 
 
 * Horn. An animal substance, chiefly 
 membranous, composed of coagulated albu- 
 men, with a little gelatin, and about half a 
 per cent of phosphate of lime. But the horns 
 of the buck and hart are of a different na- 
 ture, being intermediate between bone and 
 horn. * 
 
 * Horn Silver. Chloride of silver. * 
 
 * Hornblende. A sub-species of straight- 
 edged augile. There are three varieties of 
 hornblende; the common, hornblende-slate, 
 and basaltic hornblende. 
 
 1. Common hornblende. Colour, green- 
 ish-black, and black of other shades. Mas- 
 sive, disseminated and crystallized, in a broad, 
 thin, very oblique, four-sided prism, and in 
 a six-sided prism. The lateral planes of the 
 prism are deeply longitudinally streaked. 
 Lustre shining, pearly. Cleavage twofold 
 and oblique angular. Fracture uneven. The 
 black hornblende is opaque, the green, trans- 
 lucent on the edges. Harder than apatite, 
 but not so hard as felspar. Mountain- green 
 streak. When breathed on, it yields a pecu- 
 liar smell. Difficultly frangible. Sp. gr. 
 3.25. It melts before the blow-pipe, with 
 violent ebullition into a greyish- black colour- 
 ed glass. Its constituents are, 42 silica, 1 2 
 alumina, 11 lime, 2.25 magnesia, SO oxide 
 of iron, 0.25 ferruginous manganese, and 
 0.75 water, with a trace of potash. It is an 
 essential ingredient of the mountain rocks, 
 syenite and greenstone, and it occurs fre- 
 quently in granite, gneiss, &c. It is found 
 abundantly in the British Islands, and on the 
 Continent. 
 
 2. Hornblende-slate . Colour intermediate- 
 between greenish-black and blackish-green. 
 Massive. Lustre glistening, or pearly. Frac- 
 ture straight slaty. Fragments tabular. 
 Opaque. Streak greenish. Semi- hard. Dif- 
 ficultly frangible. It occurs in beds in gneiss, 
 in Aberdeenshire, Banffshire, and Argyll- 
 shire, in many parts of England and Ireland, 
 and abundantly on the Continent. 
 
 3. Basaltic hornblende. Colour, velvet- 
 black, or brownish-black. It occurs crys- 
 tallized, in the following figures: — a unequi- 
 angular six-sided prism ; and the six-sided 
 prism both variously acuminated. Lustre 
 of the cleavage, which is double, is splen- 
 dent, approaching to pearly. Fracture small 
 grained uneven. Opaque. Rather harder 
 than common hornblende, and more easily 
 frangible. Streak dark greyish- white. Sp.gr. 
 3.16. It fuses into a black glass. Its con- 
 stituents are, 47 silica, 26 alumina, 8 lime, 
 2 magnesia, 15 oxide of iron, and 0.5 water. 
 It occurs imbedded in basalt, along with 
 olivine and augite, at Arthur’s Seat, near 
 Edinburgh, in Fifeshire, and the Islands of 
 Mull, Canna, Eigg, and Skye. In the ba- 
 saltic rocks of England, Ireland, and the 
 Continent. — Jameson. * 
 
 * Hohnstonk. Professor Jameson’s ninth 
 sub-species of rhomboidal quartz. He di- 
 vides it into splintery hornstone, conchoidal 
 hornstone, and woodstone. 
 
 1 . Splintery hornstone . C olours grey, red, 
 and green. Massive, in balls, lenticular, 
 and in six-sided prismatic supposititious crys- 
 tals. Dull. Fracture splintery, and some- 
 what like horn in appearance, whence the 
 name. Translucent on the edges. Less 
 hard than quartz or flint. Difficultly fran- 
 gible. Sp. gr. 2.6. Infusible before the 
 blow-pipe. Its constituents are, 98.25 silica. 
 
HYA 
 
 0.75 alumina, 0.50 oxide of iron, 0.50 water. 
 Jt occurs in veins in primitive countries, 
 along with ores of silver, lead, zinc, copper, 
 and iron, and forming the basis of hornstone 
 porphyry. It is found in Arran, Perthshire, 
 Argyllshire, and many other counties of 
 Scotland, and abundantly on the Continent. 
 Hornstone porphyry at Efsdale in Sweden, 
 is cut into vases, candlesticks, &c. and the 
 pedestal of the statue of Gustavus III. at 
 ' Stockholm, is formed of it. 
 
 2. Conchoidal hornstone. Colours grev, 
 white, and red. Massive, stalactitic, and 
 rarely in supposititious crystals, whose figures 
 originate from calcareous spar. Lustre glim- 
 merino:. Fracture conchoidal. Less trans- 
 lucent than the preceding kind, but some- 
 what harder. Rather difficultly frangible. 
 Sp. gr. 2.58. It occurs in metalliferous 
 veins and agate veins, and along with clay- 
 stone in the Pentland-liills. 
 
 3. Woodstone. Colours ash-grey and grey- 
 ish-black. The various shades of colour, 
 are in clouded and striped delineations. It 
 occurs in rolled pieces, and in the shape of 
 trunks, branches, and roots. Surface uneven. 
 Dull or glistening. Cross fracture imperfect 
 conchoidal, longitudinal, fibrous. Translu- 
 cent on the edges. Hard in a low degree. 
 Rather difficultly frangible. Sp. gr. 2.63. 
 It is found imbedded in sandy loam in allu- 
 vial soil. It occurs near Lough Neagh, in 
 Ireland; at Chemnitz and Hilbersdorf, in 
 Upper Saxony. It receives a good polish,* 
 
 - — Jameson. 
 
 * Horseradish Root, yields by distilla- 
 tion, an acrid oil, denser than water.* 
 
 * Hospital Ulcer, the matter of, consists 
 of a peculiar morbid secretion. It has been 
 successfully treated by washing with dilute 
 nitrate of mercury, nitric acid, and aqueous 
 chlorine.* 
 
 * H umite. A mineral of a reddish- 
 brown colour, which occurs crystallized in 
 octohedrons, more or less truncated or bevel- 
 led. Planes transversely streaked. Lustre 
 shining. Transparent. Scratches quartz 
 with difficulty. It occurs at Somma, near 
 Naples, in a rock composed of grey-coloured 
 granular topaz. It was named by Count 
 Bournon, in honour of Sir Abr. Hume, 
 Bart, a distinguished cultivator of miner- 
 alogy. * 
 
 * Hyacinth. A sub-species of pyramidal 
 zircon. Colours, red, brown, more rarely 
 yellow, green, and grey. It occurs in an- 
 gular grains, and crystallized in a rectangu- 
 lar four-sided prism, variously acuminated 
 or truncated. Crystals are small. Lustre 
 specular-splendent. Cleavage fourfold. Frac- 
 ture small conchoidal. Semi-transparent or 
 transparent, and refracts double. Harder 
 than quartz, but softer than topaz. Rather 
 easily frangible. Sp. gr. 4.6 to 4.78. Be- 
 fore the blow-pipe it loses its colour, but not 
 
 HYD 
 
 its transparency, and is 
 stituents are, 
 
 infusible. Its con- 
 
 from Ceylon, 
 
 from Experilty. 
 
 Zircon, 70.00 
 
 66.00 
 
 Silica, 25.00 
 
 31.00 
 
 Oxide of iron, 0.50 
 
 2.00 
 
 Loss, 4.50 
 
 1.00 
 
 100.00 
 
 200.00 
 
 Klaproth. 
 
 Vauquelin * 
 
 It occurs imbedded in gneiss and syenite, 
 in basalt and lava, and dispersed through 
 alluvial soil; in Auvergne; near Pisa; in the 
 trap rocks round Lisbon; by Professor Jame- 
 son in a rolled mass of syenite in the shire 
 of Galloway ; and abundantly in Ceylon. 
 
 The darker varieties are deprived of their 
 colour by heat, a fact of which artists avail 
 themselves to make zircon resemble diamond. 
 It is esteemed as one of the gems by lapi- 
 daries. — Ja meson. * 
 
 * Hyalite. Colours yellowish and grey- 
 ish-white. Generally small reniform, bo- 
 troidal, or stalactitic. Lustre splendent. 
 Fracture small conchoidal. Translucent. 
 Moderately hard. Sp. gr. 2.2. Infusible 
 before the blow-pipe. Its constituents are y 
 92 silica, 6.33 water. It has been hitherto 
 found principally near Frankfort on the 
 Maine, where it occurs in fissures in vesicu- 
 lar basalt and basaltic greenstone. It is cut 
 into ringstones.* 
 
 * Hydrargyllite. Wavellite •* 
 
 * Hydrates. Compounds, in definite 
 proportions, of metallic oxides with water.* 
 
 * Hydriodates. Salts consisting of hy- 
 diiodicacid, combined in definite proportions, 
 with oxides.* 
 
 * H ydriodic Acid. See Acid (IIydrio- 
 dic) and Iodine.* 
 
 * Hydrochloric Acid. Muriatic acid 
 gas; a compound of chlorine and hydro- 
 gen. * 
 
 * Hydrocyanic Acid. See Acid (Prus- 
 sic).* 
 
 * Hydrogen Gas. The lightest species of 
 ponderable matter hitherto known. It was 
 discovered by Mr Cavendish in 1766. It 
 can be procured only from water, of which 
 it forms an essential constituent. 
 
 Into a phial furnished with a bent tube 
 fitted to its cork, or into a retort, put some 
 pieces of pure redistilled zinc, or harpsi- 
 chord iron wire, and pour on them sulphuric 
 acid diluted with 5 times its bulk of water. 
 An effervescence will ensue, occasioned by 
 the decomposition of the water, and disen- 
 gagement of hydrogen, which may be col- 
 lected in the pneumatic apparatus. For 
 very accurate researches, it must be received 
 in jars over mercury, and exposed to the 
 joint action of dry muriate of lime, and a 
 low temperature. It is thus freed from hy- 
 grometric water. In this state its specific 
 gravity is 0.0694 at 60° F. and 30 inches of 
 
HYD 
 
 HYD 
 
 barom. pressure. 100 cubic inches weigh 
 2. 1 1 8 grains. It is therefore about 1 4.4 
 times less dense than common air ; 16 times 
 less dense than oxygen, and 1 4 times less 
 dense than azote. In the article Gas, I have 
 shewn, that when it stands over water at 
 60°, its sp. gr. acquires an increase of nearly 
 one-seventh; and it becomes about 0.0790. 
 From the great rarity of hydrogen, it is em- 
 ployed for the purpose of inflating varnished 
 silk bags, which are raised in the air, under 
 the name of balloons. See Aerostation.* 
 
 This gas is colourless, and possessed of all 
 the physical yjroperties of air. It has usually 
 a slight garlic odour, arising probably from 
 arsenical particles derived from the zinc. 
 When water is transmitted over pure iron in 
 a state of ignition, it yields hydrogen free 
 from smell. It is eminently combustible, 
 and, if pure, burns with a yellowish-white 
 flame ; but from accidental contamination, 
 its flame has frequently a reddish tinge. If a 
 narrow jar tilled with hydrogen, be lifted 
 perpendicularly, with the bottom upwards, 
 and a lighted taper be suddenly introduced, 
 the taper will be extinguished, but the gas 
 will burn at the surface, in contact with the 
 air. Animal life is likewise speedily extin- 
 guished by the respiration of this gas, though 
 Sir H. Davy has shewn, that if the lungs be 
 not previously exhausted by a forced expira- 
 tion, it may be breathed for a few seconds 
 without much seeming inconvenience. For 
 its point of accension, see Combustion ; and 
 for its habitudes with liquids and solids, see 
 Gas. 
 
 When five measures of atmospheric air are 
 mixed with two of hydrogen, and a lighted 
 taper, or an electric spark, applied to the 
 mixture, explosion takes place, three mea- 
 sures of gas disappear, and moisture is de- 
 posited on the inside of the glass. When 
 two measures of hydrogen, mixed with one 
 of oxygen, are detonated, the whole is con- 
 densed into water. Thus, therefore, we see 
 the origin of the name hydrogen , a term de- 
 rived from the Greek to denote the water- 
 former, See Water. II a bottle contain- 
 ing the effervescing mixture of iron and di- 
 lute sulphuric acid, be shut with a cork, 
 having a straight tube of narrow bore fixed 
 upright in it, then the hydrogen will issue 
 in a jet, which being kindled, forms the phi- 
 losophical candle of Dr Priestley. If a long 
 glass tube be held over the flame, moisture 
 will speedily bedew its sides, and harmonic 
 tones will soon begin to sound. Mr Fara- 
 day, in an ingenious paper inserted in the 
 10th number of the Journal of Science, 
 states, that carbonic oxide produces, by the 
 action of its flame, similar sounds, and that 
 therefore the effect is not due to the affec- 
 tions of aqueous vapour, as had formerly 
 been supposed. lie shews, that the sound 
 is nothing more than the report of a con- 
 
 47 
 
 tinued explosion, agreeably to Sir II. Davy’s 
 just theory of the constitution of flame. 
 Vapour of ether, made to burn from a small 
 aperture, produces the same sonorous effect 
 as the jet of hydrogen, of coal gas, or olefiant 
 gas, on glass and other tubes. Globes from 
 seven to two inches in diameter, with short 
 necks, give very low tones ; bottles, Florence 
 flasks and phials, always succeeded ; air jars 
 from four inches diameter to a very small 
 size, may be used. Some angular tubes were 
 constructed of long narrow slips of glass and 
 wood, placing three or four together, so as to 
 form a triangular or square tube, tying them 
 round with pack-thread. These held over 
 the hydrogen jet, gave distinct tones. 
 Hydrogen, combined with oxygen, 
 
 With- 
 
 forms water. 
 
 Chlorine, 
 
 muriatic acid. 
 
 Iodine, 
 
 liydriodic acid. 
 
 Prussine, 
 
 prussic acid. 
 
 Carbon, 
 
 subcarb. and carb. hvdr. 
 
 Azote, 
 
 ammonia. 
 
 Phosphorus 
 
 subphos. and phos. hydr. 
 
 Sulphur, 
 
 sulph. and subsul. hydr. 
 
 Arsenic, 
 
 arsenuretted hydrogen. 
 
 Tellurium, 
 
 telluretted hydrogen. 
 
 Potassium, 
 
 potassuretted hydrogen. 
 
 For an 
 
 account of these several com- 
 
 pounds, see the respective bases. From the 
 proportion in which it combines with these 
 bodies, its prime equivalent on the oxygen 
 radix, is fixed at 0.1 25. It is the body which 
 gives the power of burning with flame to all 
 the substances used for the economical pro- 
 duction of heat and light. 
 
 In that invaluable repository of philoso- 
 phical facts, Tilloch’s Magazine, we have 
 the following notice of the effect of hydro- 
 gen gas on the voice : “ The Journal Bri- 
 tannique , published at Geneva by Prevost, 
 contains the following article : ‘ Maunoir 
 was one day amusing himself w ith Paul at 
 Geneva, in breathing pure hydrogen air. He 
 inspired it with ease, and did not perceive 
 that it had any sensible effect on him, either 
 in entering his lungs, or passing out. But 
 after he had taken in a very large dose, he 
 was desirous of speaking, and was astonish- 
 ingly surprised at the sound of his voice, 
 which was become soft, shrill, and even 
 squeaking, so as to alarm him. Paul made 
 the same experiment on himself, and the 
 siime effect w'as produced. I do not know 
 whether any thing similar has occurred in 
 breathing any of the other gases.’ ” Vol . iv. 
 page 214. 
 
 In the article arsenuretted hydrogen , under 
 Arsenic, in this w r ork, a sentence at the 
 middle of the column should read thus, 
 “ By subtracting from the specific gravity 
 of the arsenuretted gas, that of hydrogen gas 
 
 X y on’ we h ave ^ ie P ro P ort ’ on °f arsenlc 
 present; 0.55520 — 0.09716 = 0.45804 
 • — the arsenic in 100 measures of arsenu- 
 
HYD 
 
 HYD 
 
 retted hydrogen ; which gives the propor- 
 tion by weight of about five arsenic to one 
 hydrogen,” &c.* 
 
 * Hydroguret of sulphur. See Sulphur. 4 * 
 
 Hydrometer. The best method of weigh- 
 ing equal quantities of corrosive volatile 
 fluids, to determine their specific gravities, 
 appears to consist in enclosing them in a 
 bottle with a conical stopper, in the side of 
 which stopper a fine mark is cut with a file. 
 The fluid being poured into the bottle, it is 
 easy to put in the stopper, because the re- 
 dundant fluid escapes through the notch, 
 or mark, and may be carefully wiped off. 
 Equal bulks of water, and other fluids, are 
 by this means weighed to a great degree of 
 accuracy, care being taken to keep the tem- 
 perature as equal as possible, by avoiding 
 any contact of the bottle with the hand, or 
 otherwise. The bottle itself shows with 
 much precision, by a rise or fall of the liquid 
 in the notch of the stopper, whether any 
 such change have taken place. See Specific 
 Gravity and Alcohol. 
 
 The hydrometer of Fahrenheit consists of 
 a hollow ball, with a counterpoise below, 
 and a very slender stem above, terminating 
 in a small dish. The middle, or half length 
 
 of the stem, is distinguished by a fine line 
 across. In this instrument every division of 
 the stem is rejected, and it is immersed in 
 all experiments to the middle of the stem, 
 by placing proper weights in the little dish 
 above. Then, as the part immersed is con- 
 stantly of the same magnitude, and the whole 
 weight of the hydrometer is known, this last 
 weight added to the weights in the dish, will 
 be equal to the weight of fluid displaced by 
 the instrument, as all writers on hydrostatics 
 prove. And accordingly, the sp. gravities for 
 the common form of the tables will be had 
 by the proportion : 
 
 As the whole weight of the hydrometer 
 and its load, when adjusted in distill- 
 ed water, 
 
 Is to the number 1000, &c. 
 
 So is the whole weight when adjusted 
 in any other fluid 
 
 To the number expressing its specific 
 gravity. 
 
 The hydrometers, or pese- liqueurs, of 
 Baume, though in reality comparable with 
 each other, are subject in part to the defect, 
 that their results, having no independent 
 numerical measure, require explanation to 
 those who do not know the instruments. 
 
 Baume' s Hydrometer for Spirits . 
 
 Temperature 55° Fahrenheit, or 10° Reaumur. 
 
 Deg. 
 
 Sp. Grav. 
 
 Deg. 
 
 Sp. Grav. 
 
 Deg. Sp 
 
 . Grav. 
 
 Deg. 
 
 Sp. Grav. 
 
 Deg. 
 
 Sp. Grav. 
 
 10 = 
 
 - ] .000 
 
 17 
 
 = .949 
 
 23 = 
 
 .909 
 
 29 
 
 = .874 
 
 35 
 
 = .842 
 
 11 
 
 .990 
 
 18 
 
 .942 
 
 24 
 
 .903 
 
 30 
 
 .868 
 
 36 
 
 .837 
 
 12 
 
 .985 
 
 19 
 
 .935 
 
 25 
 
 .897 
 
 31 
 
 .862 
 
 37 
 
 .832 
 
 18 
 
 .977 
 
 20 
 
 .928 
 
 26 
 
 .892 
 
 32 
 
 .857 
 
 38 
 
 .827 
 
 14 
 
 .970 
 
 21 
 
 .922 
 
 27 
 
 .886 
 
 33 
 
 .852 
 
 39 
 
 .822 
 
 15 
 
 16 
 
 .965 
 
 .955 
 
 22 
 
 .915 
 
 28 
 
 .880 
 
 34 
 
 .847 
 
 40 
 
 .817 
 
 With regard to the hydrometer for salts, 
 the learned author of the first part of the 
 Encyclopaedia, Guyton de Morveau, who by 
 no means considers this an accurate instru- 
 ment, affirms, that the sixty-sixth degree 
 
 corresponds nearly with a specific gravity of 
 1.848 ; and as this number lies near the 
 extreme of the scale, I shall use it to deduce 
 the rest. 
 
 Baume s Hydrometer for Salts. 
 
 Temperature 55° Fahrenheit, or 10° Reaumur. 
 
 Deg. 
 
 Sp. Grav. 
 
 Deg. 
 
 Sp. Grav. 
 
 Deg. 
 
 Sp. Grav. 
 
 Deg. 
 
 Sp. Grav. 
 
 Deg. 
 
 Sp. Grav. 
 
 0 : 
 
 = 1.000 
 
 15 = 
 
 = 1.114 
 
 30 = 
 
 = 1.261 
 
 45 = 
 
 = 1.455 
 
 60 = 
 
 = 1.717 
 
 3 
 
 1.020 
 
 18 
 
 1.140 
 
 33 
 
 1.295 
 
 48 
 
 1.500 
 
 63 
 
 1.779 
 
 6 
 
 1.040 
 
 21 
 
 1.170 
 
 36 
 
 1.333 
 
 51 
 
 1.547 
 
 66 
 
 1.848 
 
 9 
 
 1.064 
 
 24 
 
 1 . 200 
 
 39 
 
 1.373 
 
 54 
 
 1.5 94 
 
 69 
 
 1.920 
 
 12 
 
 1.089 
 
 27 
 
 1.2.30 
 
 42 
 
 1.414 
 
 57 
 
 1.659 
 
 72 
 
 2.000 
 
 It may not be amiss to add, however, that 
 in the Philosophical Magazine, Mr Bingley, 
 the assay-master cl the mint, has given the 
 following numbers as the specific gravity of 
 nitric acid, found to answer to the degrees 
 
 of an areometer of Baume by actual trial ; 
 temperature about 60° Fahr. But his ap- 
 pears to have been a different instrument, as 
 it was graduated only from 0 to 50°. 
 
JAS 
 
 JAS 
 
 Deg. Sp. Grav. 
 18= J . 1 50 
 20 1.167 
 
 26 1.216 
 28 1.233 
 
 Deg. Sp. Grav. 
 
 29 = 1.250 
 
 30 1.267 
 
 31 1.275 
 
 32 1.285 
 
 Deg. Sp. Grav. 
 
 34 = 1.300 
 
 35 1.312 
 
 36 1.333 
 
 37 1.342 
 
 Deg. Sp. Grav. 
 
 38 = 1.350 
 
 39 1.358 
 
 40 1.S67 
 
 41 1.383 
 
 Deg. Sp. Grav, 
 
 42 = 1.400 
 
 43 1.416 
 
 45 1.455 
 
 There are a variety of hydrometers used 
 for determining the strength of ardent spi- 
 rit. See Alcohol and Distillation. 
 
 * IIydiiothane. A variety of opal, 
 which has the property of becoming trans- 
 parent on immersion in water. It is also 
 called oculus 7tiundi. We must be careful 
 to immerse them only in pure water, and to 
 withdraw them whenever they have acquired 
 their full transparency. If we neglect these 
 precautions, the pores will soon become filled 
 with earthy particles deposited from the wa- 
 ter, and the hydropbane will cease to exhibit 
 tills curious property, and will remain always 
 more or less opaque.* 
 
 * XI ydrosulpku rjets. Compounds of 
 
 sulphuretted hydrogen with the salifiable 
 bases.* 
 
 * Hydrothionic Acit>. Sulphuretted hy- 
 drogen, the hydrosulphuric acid of M. Gay 
 Tussac. * 
 
 * Hyperstene. Labradore schillerspar. 
 
 Colour between greyish and greenish-black, 
 but nearly copper-red on tlie cleavage. 
 Massive, disseminated, and in thin curved 
 lamellar concretions. Lustre shining, me- 
 tallic pearly. Cleavage double oblique an- 
 gular. Opaque. Streak greenish-grey. Hard 
 as felspar. Brittle. Sp. gr. 5.4. Infusible 
 before the blow-pipe. Its constituents are, 
 54.25 silica, 14 magnesia, 2.25 alumina, 1.50 
 lime, 24.5 oxide of iron, 1 water, and a trace 
 of manganese. It has been found in Labra- 
 dore, Greenland, and by Dr M‘Culloch in 
 the Isle of Skye. It has a beautiful copper- 
 red colour when cut and polished into ring- 
 stones or broaches. * 
 
 '* IIypophosphorous Acid. See Acid 
 
 (H YPOPHOSPHOROUs). * 
 
 * Hyposulphurous Acid. See Acid 
 
 (H YPOSULPH UltOU.s). * 
 
 * Hyposulphuric Acid. See Acid (IIy- 
 posulphuric), which three acids are treated 
 of under the phosphoric and sulphuric. 
 
 I & J 
 
 * TADE. See Nephrite.* 
 
 *1 * Jalap. A root used in medicine 
 
 as a purgative. By M. Henry’s analysis, the 
 constituents of three different varieties of this 
 root are, 
 
 Jal. leger. 
 
 Jal. sain. 
 
 Jal. pique. 
 
 Itesin, 
 
 60 
 
 48 
 
 72 
 
 Ex tract, 
 
 75 
 
 140 
 
 J 25 
 
 Starch, 
 
 95 
 
 102 
 
 103 
 
 Woody fibre, 
 
 270 
 
 210 
 
 200 
 
 
 500 
 
 500 
 
 500* 
 
 * Jargon. See Zircon.* 
 
 * Jasper. A sub-species of the rhomboi- 
 dal quartz of Professor Jameson. He enu- 
 merates five kinds : Egyptian jasper, striped, 
 porcelain, common, and agate jasper. 
 
 I. Egyptian jasper, of which there is red 
 and brown. 1'he first is flesh-red, blood- 
 red, yellow, and brown, in ring-shaped de- 
 lineations. In roundish pieces. Dull. Frac- 
 ture conchoidal. Feebly translucent on the 
 edges. Hard. Easily frangible. Sp. gr. 
 2.63. It is found imbedded in red clay- 
 ironstone at Baden, and is cut into orna- 
 ments. 
 
 The brown has its various shades of co- 
 lour disposed in concentric stripes, alternat- 
 ing with black stripes. In spheroidal mas- 
 ses. Lustre glimmering. Fracture con- 
 
 choidal. Feebly translucent on the edges. 
 As hard as hornstone. Sp. gr. 2.6. It is 
 infusible. It occurs loose in the sands of 
 Egypt. It is cut into ornaments. 
 
 2. Striped jasper. Colours, grey, green, 
 yellow, red, arranged in stripes, in flamed or 
 spotted delineations. Massive in whole beds. 
 Dull. Fracture conchoidal. Opaque. Less 
 hard than Egyptian jasper. Rather easily 
 frangible. Sp. gr. 2.5. It occurs in se- 
 condary clay-porphyry in the Pentland- 
 hills, and near Friburg in Saxony. It fe- 
 ceives a fine polish. 
 
 3. Porcelain jasper. Colours grey, blue, 
 yellow, generally of one colour, or with 
 clouded delineations. Massive, and cracked 
 irydl directions. Lustre glistening. Frac- 
 ture conchoidal. Opaque. Easily frangi- 
 ble, and not very hard. Sp. gr. 2.5. Fuses 
 into a white or grey glass. Its constituents 
 are 60.75 silica, 27.25 alumina, 3 magne- 
 sia, 2.5 oxide of iron, and 5.66 potash. It 
 is always found along with burnt clay and 
 earth slags. According to erner, it is slate- 
 clay converted into a kind of porcelain, by the 
 heat of a pseudo-volcano, from beds of burn- 
 ing coal. It is found on the coast of life- 
 shire, in Shropshire, and Warwickshire, and 
 some parts of Germany, where immense beds 
 of coal appear. 
 
IND 
 
 IND 
 
 4. Common jasper. Colours red and 
 brown. Massive. Lustre, from shining to 
 dull. Fracture conchoidal. Opaque. Hard 
 in a low degree. Rather easily frangible. 
 Sp. gr. 2.6. Infusible before the blow-pipe, 
 becoming at last white. It occurs princi- 
 pally in veins as a constituent of agate. It 
 is found in the Pentland-hills, and in trap 
 and transition rocks in Ayrshire and Dum- 
 fries- shire. It receives a good polish. 
 
 5. Agate jasper. Colours yellowish-white 
 .and reddish-white. Massive. Dull. Frac- 
 ture flat conchoidal. Opaque. Hard in a 
 low degree. It occurs in layers in agate 
 balls, in many places.* 
 
 Ice. See Caloric, Thermometer, Wa- 
 ter. 
 
 * Iceland Star. See Calcareous Spar.* 
 
 * Ice-spar. A sub-species of felspar.* 
 
 * Ichthyoththalmite. See Apophyllite.* 
 
 Ichthyocolla. Fish glue, or Isinglass. 
 
 * I doc rase. See Vesuvian.* 
 
 * Jelly, of ripe currants and other berries; 
 a compound of mucilage and acid, which 
 Joses its gelatinizing power by long boiling.* 
 
 * Jenite. See Lievrite,* 
 
 * Jet. See Pitch Coal.* 
 
 Ignis Fatuus. A luminous appearance 
 <or flame, frequently seen in the night in 
 different country places, and called in Eng- 
 land Jack with a lantern , or Will with the 
 wisp. It seems to be mostly occasioned by the 
 extrication of phosphorus from rotting leaves 
 arid other vegetable matters. It is probable, 
 that the motionless ignes fatui of Italy which 
 are seen nightly on the same spot, are pro- 
 duced by the slow combustion of sulphur, 
 emitted through clefts and apertures in the 
 soil of that volcanic conntry. 
 
 Incineration. The combustion of vege- 
 table or animal substances, for the purpose 
 of obtaining their ashes or fixed residue. 
 
 Incombustible Clotii. See Asbestos. 
 
 Indigo. A blue colouring matter ex- 
 tracted from a plant called Anil, or the In- 
 digo Plant. 
 
 In the preparation of this drug, the herb 
 is put into a vat or cistern, called the steep- 
 ing trough, and there covered with water. 
 
 I be matter begins to ferment sooner or later, 
 according to the warmth of the weather and 
 the maturity of the plant; sometimes in six 
 or eight hours, and sometimes in not less 
 than twenty. The liquor grows hot, throws 
 up a plentiful froth, thickens by degrees, and 
 acquires a blue colour inclining to violet 
 At this time, without touching the herb, the 
 liquor impregnated with its tincture, is let 
 out by cocks in the bottom into another vat 
 placed for that purpose, so as to be com- 
 manded by the first. 
 
 In the second vat, called the bcatim* vat. 
 the liquor is strongly and incessantly beaten 
 with a kind of buckets fastened to poles, till 
 the colouring matter is united into a body. 
 
 As soon as it is judged, from the blue co- 
 lour of the liquid, that the beating is suffi- 
 cient, it is left at rest for two hours; after 
 which the clear liquor is drawn ofF by cocks 
 in the side of the vat, and the blue part is 
 discharged by another cock into a third vat, 
 where it i 9 suffered to settle for some time 
 longer ; then conveyed in a half fluid state 
 into bags of cloth, to strain off' moi^ of its 
 moisture; and lastly, exposed to the air in 
 the shade in shallow wooden boxes, till it is 
 thoroughly dry. 
 
 Bergman examined this drug. He found, 
 that one-ninth part of the indigo was taken 
 up by boiling it in water. The parts dis- 
 solved were partly mucilaginous, partly as- 
 tringent, and partly saponaceous. The so- 
 lution of alum, and of sulphate of iron as 
 xvell as of copper, precipitate the astringent 
 portion. 
 
 Bergman mixed one part of well pulver- 
 ized indigo with eight parts of colourless sul- 
 phuric acid, of the specific gravity of 1.900, 
 in a glass vessel slightly closed. The acid 
 very quickly acted upon the indigo, and 
 excited much heat. After a digestion of 
 twenty-four hours, the solution was effect- 
 ed ; but the mixture was opaque and 
 black. 
 
 If the sulphuric acid be first diluted in 
 the water, it attacks only the earthy prin- 
 ciple which is mixed wdth the indigo, and 
 some of the mucilaginous parts. 
 
 The fixed alkalis saturated with carbonic 
 acid, separate a very fine blue powder from 
 the solution of indigo, which is deposited 
 very slowly. 
 
 The concentrated nitric acid attacks in- 
 digo with so much activity, as to set it on 
 fire. 
 
 The muriatic acid by digestion, and even 
 boiling upon indigo, takes up only the earthy 
 matter, the iron, and a little of the extrac- 
 tive matter, which gives it a brown co- 
 lour, hut in no respect attacks the blue 
 colour. 
 
 Pure or caustic fixed alkali dissolves 
 some matters foreign to the colouring mat- 
 ter of the indigo, but acts very little on the 
 colouring particles. Pure volatile alkali 
 has nearly the same effect. Precipitated 
 indigo is speedily dissolved in the cold in 
 the alkalis, whether fixed or volatile, if 
 pure or caustic. The blue colour is gra- 
 dually changed to a green, and at last de- 
 stroyed. 
 
 Bergman concludes, from his analysis, 
 that 100 parts of good indigo contain of 
 mucilaginous matter, separable by water 1 2, 
 resinous matter soluble in alcohol 6, earthy 
 matter taken up by the acetic acid, which 
 does not attack the iron, here, in the state 
 of oxide, 22, oxide of iron taken up by the 
 muriatic acid 1 3. 
 
 There remained 47 parts, which are the 
 
IND 
 
 IND 
 
 colouring matter, nearly in a state of purity, 
 and afforded by distillation, carbonic acid 2, 
 alkaline liquor 8, empyreumatic oil 9, coal 
 23. 
 
 The solubility of indigo in alkalis, ap- 
 pears to be produced by the abstraction of 
 part of the oxygen it had absorbed. This 
 appears to be well established from the 
 experiment of Bergman, wherein equal 
 weights of sulphate of iron and indigo, 
 and double the weight of lime, are mixed 
 together in water, and produce a solution of 
 the indigo in the lime-water. But if the 
 iron of the sulphate, be previously oxidized 
 to a higher degree, by boiling it in much 
 water for several hours, and subsequent 
 evaporation, the solution will not be effect- 
 ed, because the precipitated iron is no longer 
 disposed to absorb oxygen. Or again, if 
 indigo be added to a solution of caustic fixed 
 alkali, and orpiment be added (which con- 
 sists of arsenic and sulphur), the indigo is 
 soon dissolved, and takes a green colour. If 
 the arsenic corresponding with the orpiment 
 be only added, the bath will never be fit for 
 the dyer; but if the quantity of sulphur it 
 ought to contain be added, the appearances 
 of solution will speedily be had. 
 
 It follows, therefore, that indigo contains 
 oxygen in its natural state ; that in this state 
 it will not unite with lime or alkalis ; but 
 that substances capable of depriving it of 
 part of its oxygen, render it soluble in lime 
 or alkalis ; and lastly, that the natural state 
 of the indigo is restored by the contact of 
 oxygen which it absorbs. In this last way 
 it is that the blue dye is effected. The piece 
 comes out of the vat of the same colour as 
 the solution ; viz. green ; but becomes blue 
 by exposure to the air. The alkali, or lime, 
 is carried off by the washing, and the indigo 
 remains combined with the stuff, by this 
 means dyed. 
 
 * M. Chevreul has given the following 
 results of a very elaborate analysis of Guati- 
 mala Indigo. 
 
 f Ammonia, 12 
 
 By water 
 
 | Disoxygenized indigo, 
 ) Green matter, 
 
 Bitter matter, 
 f Green matter, 
 
 By alcohol Red matter, 
 
 (_ Indigo, 
 
 -r, . . . I Red matter, 
 
 By muriatic acid < , , fl . 
 
 J t Carbonate of lime, 
 
 30 
 
 Oxide of iron and alumina, 
 Silica, 
 
 Pure indigo, 
 
 6 
 
 2 
 
 2 
 
 3 
 
 45 
 
 100 
 
 When commercial indigo is exposed to a 
 heat of about 400° F. it evolves a beautiful 
 crimson smoke, which may be condensed in 
 crystalline needles, which are supposed to 
 be pure indigo. The blue vat of the dyer 
 
 contains indigo deoxidized by protoxide of 
 iron, and rendered soluble in its yellow-green 
 state by lime-water. If a portion of this 
 solution be exposed in the air, in a shallow 
 vessel, the indigo will speedily absorb ox- 
 ygen, and precipitate in its usual state of 
 an insoluble blue powder. This being dried, 
 and digested in a mixture of alcohol and 
 muriatic acid, becomes also pure indigo, by 
 the abstraction of all the resin and lime. In 
 this state, it is a soft powder, of an intensely 
 deep blue, verging sometimes on purple. 
 It is unchangeable by the air. Every sub- 
 stance which has a great affinity for oxygen, 
 when digested with indigo, deprives it of the 
 blue colour, and converts it, either perma- 
 nently or for a time, to a yellow or greenish- 
 yellow hue. Thus, if into the sulphate of 
 indigo above described, are put a few pieces 
 of iron or zinc, the nascent hydrogen seizes 
 its oxygen, and discolours it. Sulphuric acid, 
 rendered smoking by a little sulphurous acid, 
 is a better solvent of indigo than pure oil of 
 vitriol. By boiling a little sulphur in this, 
 its solvent power is improved. Nitric acid, 
 digested on indigo, converts it into Mr Hat- 
 chett’s artificial tannin, a bitter principle, 
 with oxalic and benzoic acids. 
 
 When indigo is mixed with liquid fer- 
 mentable materials, it is speedily deoxidized. 
 Bergman shewed long ago, that no gas, ex- 
 cept carbonic acid, was disengaged from 
 the distillation of indigo in close vessels. 
 This seems to coincide with Dr Thomson’s 
 late analysis, in which he exposed pure in- 
 digo to the action of ignited peroxide of 
 copper, and collected the gaseous products, 
 which led him to assign the following as its 
 composition : — 
 
 Oxygen, 46.154 
 Carbon, 40.384 
 
 Azote, 13.462 
 
 100.000 
 
 The total want of hydrogen in this vege- 
 table substance, is a very singular and inter- 
 esting result. He says, that indigo, in the 
 state of a greenish-yellow soluble pigment, 
 is composed of 5 atoms Oxygen, 5.00 
 7 Carbon, 5.25 
 1 Azote, 1.75 
 
 12.00 
 
 The addition of a single atom of oxygen, 
 renders the pigment blue and insoluble. 
 “ Thus,” adds he, “ indigo exhibits a striking 
 refutation of the old notion, that acidity is 
 owing to the union of oxygen with an acidi- 
 fiable basis. Blue indigo approaches much 
 nearer to the nature of a salifiable base, than 
 an acid ; but deoxidized indigo, seems to 
 possess acid powers, for it becomes capable 
 of uniting with alkalis, and alkaline earths. 
 Annals of Philosophy for June 1820.* 
 
INK 
 
 INK 
 
 \ 
 
 Jkk. Every liquor or pigment used for 
 writing or printing, is distinguished by the 
 name of ink. Common practice knows only 
 black and red. 
 
 Of black ink there are three principal 
 kinds : 1. Indian ink; 2. Printers’ ink; and, 
 
 3. Writing ink. 
 
 The Indian ink is used in China for writ- 
 ing with a brush, and tor painting upon the 
 soft flexible paper of Chinese manufacture. 
 It is ascertained, as well from experiment as 
 from information, that the cakes ot this ink 
 are made of lampblack and size, or animal 
 glue, with the addition of perfumes or other 
 substances not essential to its quality as an 
 ink. The fine soot from the flame of a 
 lamp or candle, received by holding a plate 
 over it, mixed with clean size from shreds of 
 parchment or glove-leather not dyed, will 
 make an ink equal to that imported. 
 
 Good printers’ ink is a black paint, smooth 
 and uniform in its composition, of a firm 
 black colour, and possesses a singular apti- 
 tude to adhere to paper thoroughly impreg- 
 nated with moisture. 
 
 The consistence and tenacity of the oil in 
 this composition are greatly increased, and 
 its greasiness diminished, by means of fire. 
 Linseed oil or nut oil is made choice of for 
 this use. The nut oil is supposed to be the 
 best, and is accordingly preferred for the 
 black ink, though the darker colour it ac- 
 quires from the fire renders it less fit for the 
 red. It is said, that the other expressed oils 
 cannot be sufficiently freed from their unctu- 
 ous quality. 
 
 Ten or twelve gallons of the oil are set 
 over the fire in an iron pot, capable of hold- 
 ing at least half as much more; for the oil 
 swells up greatly, and its boiling over into 
 the fire would be very dangerous. When 
 it boils it is kept stirring with an iron ladle ; 
 and if it do not itself take fire, it is kindled 
 with a piece of flaming paper or wood; for 
 simple boiling, without the actual accension 
 of the oil, does not communicate a sufficient 
 degree of the drying quality required. The 
 oil is suffered to burn for half an hour or 
 more, and the flame being then extinguish- 
 ed, by covering the vessel close, the boiling 
 is afterward continued with a gentle heat, 
 till the oil appears of a proper consistence ; 
 in which state it is called varnish. It is ne- 
 cessary to have two kinds of this varnish, a 
 thicker and a thinner, from the greater or 
 less boiling, to be occasionally mixed to- 
 gether, as different purposes may require ; 
 that which answers well in hot weather be- 
 ing too thick in cold, and large characters 
 not requiring so stiff’ an ink as small ones. 
 
 The thickest varnish, when cold, may be 
 drawn into threads like weak glue ; by which 
 criterion the workmen judge of the due boil- 
 ing, small quantities being from time to time 
 taken out and dropped upon a tile for this 
 
 purpose. It is very viscid and tenacious, 
 like the soft resinous juices, or thick turpen- 
 tine. Neither water nor alcohol dissolves 
 it ; but it readily enough mingles with fresh 
 oil, and unites with mucilages into a mass 
 diffusible in water in an emulsive form. 
 Boiling with caustic alkali produces a soapy 
 compound. It is by washing with hot scap- 
 lees ai>d a brush that the printers clean their 
 types. The oil loses from one-tenth to one- 
 eighth of its weight by the boiling into the 
 thick varnish. 
 
 It is affirmed, that varnish containing 
 either turpentine or litharge, particularly the 
 latter, is more adhesive than other varnish, 
 and presents a great difficulty in cleaning 
 the types, which soon become clogged. Very 
 old oil requires neither of these additions. 
 New oil can hardly be brought into a proper 
 state for drying, so as not to set off, without 
 the use of turpentine. 
 
 Lampblack is the common material to 
 give the black colour, of which two ounces 
 and a half are sufficient for sixteen ounces 
 of the varnish. Vermilion is a good red. 
 They are ground together on a stone with a 
 muller, in the same manner as oil paints. 
 
 The ink used by copperplate printers dif- 
 fers in the oil, which is not so much boiled 
 as to acquire the adhesive quality. This 
 would render it less disposed to enter the 
 cavities of the engraving, and more difficult 
 either to be spread or wiped off’. The black 
 is likewise of a different kind. Instead of 
 lampblack, or sublimed charcoal, the Frank- 
 fort black is used, which is a residual or dens- 
 er charcoal, said to be made from vine-twigs. 
 This is softer and less gritty than the ivory 
 or other blacks prepared among us, and, no 
 doubt, contains more coal than any animal 
 residue, as all these abound with phosphate 
 of lime. It is said, that lampblack gives 
 always a degree of toughness to the ink, 
 which the Frankfort black does not; but the 
 goodness of the colour seems to be the lead- 
 ing inducement for the use of the latter. A 
 pale or brown black can be much more easily 
 endured in a book, than in the impression of 
 an engraving. 
 
 We have no good explanation of what 
 happens with regard to the chemical effect 
 of boiling and burning upon the oil for 
 printers’ use. 
 
 Common ink for writing is made by add- 
 ing an infusion or decoction of the nut-gall 
 to sulphate of iron, dissolved in water. A 
 very fine black precipitate is thrown down, 
 the speedy subsidence of which is prevented 
 by the addition of a proper quantity of gum- 
 arabic. This is usually accounted for by the 
 superior affinity of the gallic acid, which, 
 combining with the iron, takes it from the 
 sulphuric, and falls down. But it appears 
 as if this were not the simple state of the 
 facts ; for the sulphuric acid in ink is not so 
 
INK 
 
 INK 
 
 for disengaged as to act speedily upon fresii 
 iron, or give other manifestations of its pre- 
 sence in an uncombined state. According 
 to Deyeux, the iron in ink is partly in the 
 state of a gal late. 
 
 JNI. Ribau court paid particular attention 
 to the process for making black ink, and 
 from his experiments he draws the following 
 inferences: — That logwood is a useful in- 
 gredient in ink, because its colouring matter 
 is disposed to unite with the oxide of iron, 
 and renders it not only of a very dark co- 
 lour, but less capable of change from the ac- 
 tion of acids, or of the air. Sulphate of 
 copper, in a certain proportion, gives depth 
 and firmness to the colour of the ink. Gum- 
 arabic, or any other pure gum, is of service, 
 by retarding the precipitation of the fcculse ; 
 by preventing the ink from spreading or 
 sinking into the paper; and by affording it 
 a kind of compact varnish, or defence from 
 the air when dry. Sugar appears to have 
 some bad qualities, but is of use in giving 
 a degree of fluidity to the ink, which per- 
 mits the dose of gum to be enlarged beyond 
 what the ink would bear without it. Water 
 is the best solvent. 
 
 Lewis had supposed, that the defects of 
 ink arise chiefly from a want of colouring 
 matter. But the theory, grounded on the 
 fact discovered by M. Ribaucourt, requires, 
 that none of the principles should be in ex- 
 cess. 
 
 It is doubtful whether the principles of 
 the galls be well extracted by maceration ; 
 and, it is certain, that inks made in this way 
 flow pale from the pen, and are not of so 
 deep a black as those wherein strong boiling 
 is recurred to. 
 
 From all the foregoing considerations M. 
 R. gives these directions for the composition 
 of good ink : — 
 
 Take eight ounces of Aleppo galls (in 
 coarse powder); four ounces of logwood (in 
 thin chips) ; four ounces of sulphate of iron ; 
 three ounces of gum-arabic (in powder) ; 
 one ounce of sulphate of copper ; and one 
 ounce of sugar-candy. Boil the galls and 
 logwood together in twelve pounds of water 
 for one hour, or till half the liquid has eva- 
 porated. Strain the decoction through a 
 hair sieve, or linen cloth, and then add the 
 other ingredients. Stir the mixture, till the 
 whole is dissolved, more especially the gum; 
 after which, leave it to subside for twenty- 
 four hours. Then decant the ink, and pre- 
 serve it in bottles of glass or stone ware, well 
 corked. 
 
 Many recommend, that the sulphate of iron 
 should be calcined to whiteness. Mr Desor- 
 meaux, jun. an ink manufacturer in Spital- 
 fields, has given the following in the Philo- 
 sophical Magazine, as the result of much 
 experience -.—-Boil four ounces of logwood 
 about an hour in six beer quarts ol water, 
 
 adding boiling water from time to time ; 
 strain while hot; and when cold add water 
 enough to make the liquor five quarts. Into 
 this put one pound averdup. of blue galls 
 coarsely bruised ; four ounces of sulphate of 
 iron calcined to whiteness ; three ounces of 
 coarse brown sugar; six ounces of gum- 
 arabic ; and J ounce of acetate of copper, tri- 
 turated with a little of the decoction to a 
 paste, and then thoroughly mixed with the 
 rest. This is to be kept in a bottle uncorked 
 about a fortnight, shaking it twice a-day, after 
 which it may be poured from the dregs, and 
 corked up for use. 
 
 Dr Lewis uses vinegar for his menstruum; 
 and M. Ribaucourt has sulphate of copper 
 among his ingredients. I have found an 
 inconvenience from the use of either, which, 
 though it does not relate to the goodness of 
 the ink, is sufficiently great, in their practical 
 exhibition, to forbid their use. The acid of 
 the vinegar acts so strongly upon the pen, 
 that it very frequently requires mending; 
 and the sulphate of copper has a still more 
 unpleasant effect on the penknife. It sel- 
 dom happens when a pen requires mending, 
 that the ink is wiped very perfectly from it; 
 and often, when the nib only is to be taken 
 of!’, it is done without wiping at all. When- 
 ever this is the case, the ink immediately de- 
 posits a film of copper upon the knife, and 
 by superior elective attraction of the sulphu- 
 ric acid, a correspondent portion of the edge 
 of the knife is dissolved, and is by this means 
 rendered incapable of cutting till it has been 
 again set upon tlie hone. 
 
 If a little sugar be added to ink, a copy 
 of the writing may easily be taken off', by 
 laying a sheet of thin unsized paper, damped 
 with a sponge, on the written paper, and 
 passing lightly over it a flat iron very mo- 
 derately heated. 
 
 Inks of other colours may be made from a 
 strong decoction of the ingredients used in 
 dyeing, mixed with a little alum and gum- 
 arabic. For example, a strong decoction of 
 Brazil wood, with as much alum as it can 
 dissolve, and a little gum, forms a good red 
 ink. These processes consist in forming a 
 lake, and retarding its precipitation by the 
 gmu. See Lake. 
 
 O 
 
 On many occasions it is of importance to 
 employ an ink indestructible by any process, 
 that will not equally destroy the material on. 
 which it is applied. Mr Close has recom- 
 mended for this purpose twenty-five grains 
 of copal in powder dissolved in 200 grains 
 of oil of lavender, by the assistance of gentle 
 beat, and then mixed with two and a halt 
 grains of lampblack, and half a grain of in- 
 digo; or 120 grains of oil of lavender, seven- 
 teen grains of copal, and sixty grains of ver- 
 milion. A little oil of lavender, or of tur- 
 pentine, may be added, if the ink be tound 
 too thick. Mr Sheldrake suggests, that a 
 
INK 
 
 I NT 
 
 mixture of genuine asphaltum dissolved in 
 oil of turpentine, amber varnish, and lamp- 
 black, would be still superior. 
 
 When writing with common ink has been 
 effaced by means of aqueous chlorine, the 
 vapour of sulphuret of ammonia, or immer- 
 sion in water impregnated with this sul- 
 phuret, will render it again legible. Or, if 
 the paper that contained the writing be put 
 into a weak solution of prussiate of potash, 
 and, when it is thoroughly wet, a little sul- 
 phuric acid be added to the liquor, so as to 
 render it slightly acidulous, the same pur- 
 pose will be answered. 
 
 Mr Haussman has given some composi- 
 tions for marking pieces of cotton or linen, 
 previous to their being bleached, which are 
 capable of resisting every operation in the 
 processes both of bleaching and dyeing, and 
 consequently, might be employed in mark- 
 ing linen for domestic purposes. One of 
 these consists of asphaltum dissolved in 
 about four parts of oil of turpentine, and 
 with this is to be mixed lampblack, or black 
 lead in fine powder, so as to make an ink of 
 a proper consistence for printing with types. 
 Another, the blackish sulphate left after ex- 
 pelling oxygen gas from oxide of manganese 
 with a moderate heat, being dissolved and 
 filtered, the dark grey pasty oxide left on the 
 filter is to be mixed with a very little solution 
 of gum-tragacanth, and the cloth marked 
 with this is to be dipped in a solution of pot- 
 ash or soda, mild or caustic, in about ten 
 parts of water. 
 
 Among the amusing experiments of the 
 art of chemistry, the exhibition of sympathe- 
 tic inks holds a distinguished place. With 
 these the writing is invisible, until some re- 
 agent gives it opacity. We shall here men- 
 tion a few out of the great number, that a 
 slight acquaintance with chemistry may sug- 
 gest to the student. 1. If a weak infusion 
 of galls bo used, the writing will be invisible 
 till the paper be moistened with a weak 
 solution of sulphate of iron. It then be- 
 comes black, because these ingredients form 
 ink. 2. If paper be soaked in a weak infu- 
 sion oi galls, and dried, a pen dipped in the 
 solution of sulphate of iron will write black 
 on that paper, but colourless on any other 
 paper. 3. I he diluted solutions of gold and 
 silvei remain colourless upon the paper, till 
 exposed to the sun s light, which gives a 
 dark colour to the oxides, and renders them 
 visible. 4. Most of the acids, or saline so- 
 lutions, being diluted, and used to write 
 with, become visible by heating before the 
 fire, which concentrates them, and assists 
 their action on the paper. 5. Diluted prus- 
 si.tte of potash affords blue letters when wet- 
 ted with the solution of sulphate of iron, 
 b. I lie solution of cobalt in aqua regia, 
 lien diluted, affords an ink which becomes 
 green when held to the fire, but disappears 
 
 again when suffered to cool. This has been 
 used in fanciful drawings of trees, the green 
 leaves of which appear when warm, and va- 
 nish again bv cold. If the heat be continued 
 too long after the letters appear, it rentiers 
 them permanent. 7. If oxide of cobalt be 
 dissolved in acetic acid, and a little nitre 
 added, the solution will exhibit a pale rose 
 colour when heated, which disappears on 
 cooling. 8. A solution of equal parts of 
 sulphate of copper and muriate of ammonia, 
 gives a yellow colour when heated, that dis- 
 appears when cold. 
 
 Sympathetic inks have been proposed as 
 the instruments of secret correspondence. 
 But they are of little use in this respect, 
 because the properties change by a few days 
 remaining on the paper ; most of them have 
 more or less of a tinge when thoroughly dry ; 
 and none of them resist the test of heating 
 the paper till it begins to be scorched. 
 
 * Nitrate of silver for a surface impreg- 
 nated with carbonate of soda, and muriate of 
 gold for one impregnated with protomuriate 
 of tin, form good indelible inks.* 
 
 Insects. Various important products are 
 obtained from insects. The chief are, 1, 
 Cantharides ; 2. Millepedes ; 3. Cochineal ; 
 4. Kermes ; 5. Lac ; 6 . Silk ; 7. Wax. 
 
 Instruments (Chemical). See Balance, 
 Thermometer, Laboratory. 
 
 * Intestinal Concretions. For a des- 
 cription of such of these as occur in the infe- 
 rior animals, see Bezoar. 
 
 I shall here insert an account of a very 
 curious concretion extracted from the rectum 
 of a woman in Perthshire, in the year 1817. 
 She is, I believe, still alive. It was sent to 
 me by her physician, Dr Kennedy of Dun- 
 ning. The following paper was written at 
 the time, and an abstract published in a 
 London Medical Journal, in the autumn of 
 the same year. 
 
 The form of the concretion, is a compress- 
 ed cylinder, the length and larger diameter, 
 each one inch ; the smaller diameter, three 
 quarters of an inch. In hardness, it is equal 
 to wax, but without its tenacity. One of 
 the ends, which is polished, and glistening, 
 exhibits the appearance of concentric laminae, 
 formed of circular brown lines, in a yellow 
 basis. Its sides have the lustre, and marbled 
 appearance, of Castile soap. Its internal 
 structure, is granular, approaching to crys- 
 talline, with radiations from the centre to 
 the circumference, of brown and bright yel- 
 low lines, possessed of pearly lustre. It is 
 friable between the fingers, covering them, 
 on pressure, with a mealy powder, of but 
 little unctuosity. 
 
 Its weight is 167.5 grains. Specific gra- 
 vity of the mass seems at first inferior to that 
 of distilled water ; for it floats on it for a 
 little, but it afterwards sinks to the bottom. 
 In a solution of muriate of soda, sp. gr. 
 
INT 
 
 1NT 
 
 1.0135, a fragment of it remains suspended 
 in any part of the fluid. This, therefore, ia 
 its specific gravity. 
 
 Its odour is strong, but by no means dis- 
 agreeable. It is decidedly musky, or more 
 precisely that of ambergris. 
 
 MS ater has no action on it, nor does it 
 affect the purple of litmus. It remains 
 solid in boiling water. When it is heated 
 to the temperature of about 400° F., it fuses 
 into a black mass, and exhales a copious 
 white smoke, in the odour of which, we may 
 recognize that of ambergris, mixed with the 
 smell of burning fat. Exposed in a platina 
 capsule to a dull red heat, it burns with 
 much flame, and smoke, leaving no appre- 
 ciable residuum. 
 
 It dissolves rapidly in sulph. ether, forming 
 an amber-coloured liquid. When the ether 
 evaporates away, white glistening scales, of 
 a micaceous appearance, are left. 
 
 Ten parts of hot alcohol dissolve one of it, 
 but as the alcohol cools, the greater part pre- 
 cipitates in these soft crystalline scales, while 
 the surface of the liquid becomes covered 
 with a beautiful iridescent pellicle, present- 
 ing stellated radiations. 
 
 Naphtha, the fixed, and volatile oils, readi- 
 ly act upon it, forming bright yellow solu- 
 tions. 
 
 Small fragments of it, exposed on a sand- 
 bath, for two days, in a glass capsule, 
 containing the water of pure potash, were 
 not found to be altered in their size or 
 appearance. Neither does liquid ammonia, 
 digested on it, produce the slightest effect. 
 In these respects, it possesses more analogies 
 with ambergris, than with any other sub- 
 stance I know. I was hence led to imagine 
 that the white smoke which it exhales at a 
 moderate heat, was benzoic acid, which this 
 substance is said copiously to contain. 
 
 An alcoholic solution of the concretion 
 was therefore added to water of ammonia, 
 when a milky liquid was produced by the 
 separation of the substance, in a finely divided 
 state. This mixture was evaporated to dry- 
 ness by a gentle heat, in order to get rid 
 of the alcohol and uncombined ammonia. 
 Warm water was then digested on the resi- 
 duum, and the whole poured on a filter. 
 The liquid which passed through, should 
 have contained benzoate of ammonia, pro- 
 vided any benzoic acid existed in the con- 
 cretion. It was divided into two portions. 
 Into one of these, a few drops of dilute sul- 
 phuric acid were poured ; and the acidulous 
 fluid was then concentrated by evaporation 
 in a glass capsule ; but on cooling, it afford- 
 ed no traces of benzoic acid. An extremely 
 minute quantity of benzoate of ammonia, 
 treated in the same way, for comparison, 
 gave the characteristic crystals of that acid. 
 The other portion, was added to a neutral 
 solution of red muriate of iron, but no pre- 
 
 cipitate ensued. A very small particle of 
 crystallized benzoate of ammonia being add- 
 ed to the same muriate, speedily gave the 
 brown precipitate, but produced no change 
 whatever on solutions, perfectly neutral, of 
 the green muriate and sulphate ; a fact of 
 consequence to shew the state of oxidize- 
 ment, in which iron exists in a mineral, or 
 saline combination, indicating also an easy 
 method of separating the two oxides of this 
 metal. From the above experiments, we 
 may infer, with much probability, that the 
 concretion contains no benzoic acid. 
 
 Nitric acid, sp. gravity 1.300, digested on 
 it, at a gentle heat, and then cooled, con- 
 verted the substance into bright yellow glo- 
 bules, denser and less friable than the origi- 
 nal matter, and somewhat semi-transparent, 
 like impure rosin. There was, however, no 
 true solution by the acid ; nor was the com- 
 bustibility in the least impaired by the ope- 
 ration. 
 
 As our Institution possesses specimens of 
 very fragrant ambergris, said to have been 
 imported in the genuine state from Persia, I 
 was desirous to compare their chemical rela- 
 tions, with those of this morbid concretion. 
 Two of the pieces of ambergris differ in 
 many respects from one another. The first 
 is of a light grey colour, with resinous look- 
 ing points interspersed through it, and has a 
 density considerably greater than water. It 
 is 1.200. When heated in water to the 
 temperature of 130°, it falls dow n into light 
 spongy fragments. The second has a spe- 
 cific gravity of 0.959; it is darkish brown 
 on the outside, and light brown within. In 
 W'ater heated to the above degree, it softens 
 into a viscid substance like treacle. Both 
 are readily dissolved in warm alcohol, but 
 the latter yields the richer golden- coloured 
 solution. As the alcohol cools, a separa- 
 tion of brilliant scales is perceived. With 
 ether, naphtha, the fixed and volatile oils, the 
 phenomena exhibited by ambergris are abso- 
 lutely the same, as those presented by the 
 concretion, with these solvents. The alco- 
 holic solution mixed with liquid ammonia, 
 gives a similar milky emulsion. 
 
 The lighter specimen of ambergris, exposed 
 to a gentle heat over a lamp, in glass tube 
 sealed at one end, fuses, and evolves a vola- 
 tile oil in dense vapour, which is condensed 
 on the upper part of the tube. A viscid 
 substance like tar, remains at the bottom. 
 The oil resembles the succinic, and has, like 
 it, a disagreeable empyreumatic odour. The 
 denser ambergris, being subjected to heat in 
 like circumstances, fuses less readily and 
 completely, emits the same volatile empy- 
 reumatic oil, accompanied with crystalline 
 needles, decidedly acidulous. I hese are 
 either the benzoic or succinic acid. They 
 precipitate peroxide of iron from the neutral 
 red muriate. The smell of the accompany- 
 
INT 
 
 IOD 
 
 in<r oil, is certainly that of amber ; but I 
 have hitherto obtained too small quantities 
 of the acid, to be able to determine to which 
 of the two it belongs. The following expe- 
 riments were made with this view. My first 
 object was to discover a good criterion for 
 discriminating benzoic from succinic acid. 
 In operating necessarily on small quantities, 
 the distinction becomes peculiarly difficult. 
 Both are volatile, crystallizable, and fall 
 down with peroxide of iron, from saline so- 
 lutions of this metal. After many trials I 
 finally fell on the following plan, which an- 
 swers very well, even with pretty minute 
 portions. I saturated each acid, with am- 
 monia ; evaporated to a dry crystalline mass, 
 by a gentle heat. Into a small glass tube, 
 sealed at one end, I introduced a portion of 
 the benzoate. The tube was recurved. I 
 exposed the bottom where the salt was 
 placed, to the heat of a lamp, but very cau- 
 tiously. Pungent ammoniacal gas was ex- 
 haled, and the water of crystallization that 
 distilled over, was found strongly impreg- 
 nated with ammonia. To avoid all fallacy 
 in this result, I slightly supersaturated the 
 ammonia beforehand, with the acid. In the 
 middle of the tube, pure benzoic acid w^as 
 found, in acicular crystals. The succinate 
 of ammonia, on the contrary, sublimes with- 
 out decomposition. 
 
 I now took a few grains of the dense am- 
 bergris, digested with alcohol, added water 
 of ammonia, boiled, filtered, and evaporated 
 to dryness. The quantity of saline matter 
 obtained, was, however, too minute, even for 
 the above mode of applying an analytical 
 criterion, with satisfaction ; and being un- 
 willing to consume more than a few grains 
 of a specimen, belonging to a public esta- 
 blishment, I preferred waiting till some fu- 
 ture opportunity might occur of examining 
 genuine ambergris. 
 
 From the lighter, and by its outward ap- 
 pearance, more characteristic specimen, of 
 ambergris, I could not obtain even a trace 
 of benzoic acid, though I modified the tem- 
 perature for sublimation, and other circum- 
 stances, in every way I could think of. The 
 oil that rose would not redden the most deli- 
 cate litmus paper. 
 
 In open capsules, fragments of the amber- 
 gris, being exposed to a pretty strong heat, 
 exhaled the copious subfeetid smoke ; and 
 afterwards burned with the yellow flame, ex- 
 hibited by the concretion. Fragments of 
 the concretions, exposed to heat in a glass 
 tube, fused, evolved the heavy smoke, which 
 condensed into a viscid empyreumalic smell- 
 ing oil, and in every respect comported itself 
 like the light ambergris. 
 
 I therefore must infer it to be a modifica- 
 tion of ambergris. It differs decidedly from 
 the adipocere of dead bodies, which forms 
 an emulsion with cold water, is fusible in 
 
 boiling water, gives a soap, with evolution of 
 ammonia, when treated with potash, and 
 yields a clear solution, when gently heated 
 with liquid ammonia. It resembles, how- 
 ever, in many respects the cholesterine of 
 biliary calculi ; and I have no doubt that 
 cholesterine from altered bile, is the true 
 origin of ambergris in the whale, as well as 
 of this morbid concretion. 
 
 The concretion is almost wholly soluble in 
 hot alcohol ; while only one-third of adipo- 
 cere dissolves in that menstruum at the boil- 
 ing point. 
 
 From ordinary fatty matter it is entirely 
 distinguishable, by its solubility in ether and 
 alcohol, its refusing to combine with alkalis, 
 and the high temperature required for its 
 fusion. 
 
 With regard to their place of formation in 
 the animal system, ambergris and this mor- 
 bid concretion agree. They are both gene- 
 rated in the rectum, or greater intestines. 
 The pliyseter macrocephalus of Linnaeus, is 
 the species of whale which affords ambergris. 
 In the examination of Captain Coffin before 
 the Privy- Council in 1791, he stated, that 
 he found 362 ounces of ambergris in the 
 intestines of a female whale, struck off 
 the coast of Guinea ; part of it was voided 
 from the rectum on cutting up the blubber, 
 and the remainder was within the intestinal 
 canal. 
 
 The whales that contain ambergris are 
 said to be always lean and sickly, yield but 
 very little oil, and seem almost torpid. 
 Hence when a spermaceti whale has this ap- 
 pearance, and does not emit feces on being 
 harpooned, the fishers generally expect to 
 find ambergris within it. Whether it be the 
 cause or the effect of disease, is problemati- 
 cal, though the latter seems the more rational 
 conjecture. It may in succession be both. 
 The above remarkable fact of the sex of the 
 whale, may lead to an inquiry, whether this 
 morbid production, found also in the human 
 subject, be peculiar to females, and con- 
 nected with lactation. 
 
 In the second volume of Dr Monro’s 
 Outlines of the Anatomy of the Fluman 
 Body in its sound and diseased state, we 
 have the analysis of several al vine concretions 
 by Dr Thomas Thomson. The results obtain- 
 ed by this eminent chemist, shew that the 
 specimens which he examined, were of a 
 totally different nature from the preceding 
 concretion. * 
 
 * Iodine. A peculiar or undecompound- 
 ed principle. The investigation of this sin- 
 gular substance will always be regarded as a 
 great era in chemistry. It was then that 
 chemical philosophers first felt the necessity 
 of abandoning Lavoisier’s partial and incor- 
 rect hypothesis of oxygenation, and of em- 
 bracing the sound and comprehensive doc- 
 trines of Sir II. Davy on chemical theory, 
 
IOD 
 
 IOI) 
 
 lirst promulgated in his masterly researches 
 
 on Chlorine • 
 
 Iodine was accidentally discovered, in 
 18i2, by M. de Gourtois, a manufacturer of 
 saltpetre at 1 aris. In his processes for pro- 
 curing soda trom the ashes of sea- weeds, hs 
 found the metallic vessels much corroded ; 
 and in searching tor the cause of the corro- 
 sion, he made this important discovery. But 
 for this circumstance, nearly accidental, one 
 of the most curious of substances might have 
 remained for ages unknown, since nature 
 has not distributed it, in either a simple or 
 compound state, through her different king- 
 doms, but has confined it, to what the Ro- 
 man satirist considers as the most worthless of 
 things, the vile sea-weed. 
 
 Iodine derived its first illustration from 
 MM. Clement and Desormes, names associ- 
 ated always with sound research. In their 
 memoir, read at a meeting of the Institute, 
 these able chemists described its principal 
 properties. They stated its sp. gr. to be 
 about 4 ; that it becomes a violet-coloured gas 
 at a temperature below that of boiling wa- 
 ter; whence its name, like a violet , 
 
 was derived ; that it combines with the me- 
 tals, and with phosphorus and sulphur, and 
 likewise with the alkalis and metallic oxides; 
 that it forms a detonating compound with 
 ammonia ; that it is soluble in alcohol, and 
 still more soluble in ether ; and that by its 
 action upon phosphorus and upon hydrogen, 
 a substance having the characters of muriatic 
 acid is formed. In this communication they 
 offered no decided opinion respecting its na- 
 ture. 
 
 In 1813 Sir H. Davy happened to be on 
 a visit to Paris, receiving, amid the political 
 convulsions of France, the tranquil homage 
 due to his genius. “ When M. Clement 
 shewed iodine to me, he believed that the 
 hydriodic acid was muriatic acid ; and M. 
 Gay Lussac, after his early experiments, 
 made originally with M. Clement, formed 
 the same opinion, and maintained it, when I 
 Jirst stated to him my belief, that it was a 
 new and peculiar acid, and that iodine was a 
 substance analogous in its chemical relations 
 to chlorine .” — Sir H. Davy on the Analogies 
 between the undecompounded substances ; Jour- 
 nal <rf Science and the Arts , vol. i. p. 284. 
 
 We see therefore with what intuitive sa- 
 gacity the English philosopher penetrated 
 the mystery which hung at first over iodine. 
 Its full examination, in its multiplied rela- 
 tions to simple and compound bodies, was 
 immediately entered on with equal ardour 
 by him, and M. Gay Lussac. Of the rela- 
 tive merits of the researches, and importance 
 of the results, of these pre-eminent chemists, 
 it is not for me to become an arbiter. I 
 shall content myself with offering a metho- 
 dical view of the facts brought to light on 
 iodine and the iodides, referring for its other 
 
 combinations to what I have already stated 
 on the hydriodic and iodic acids. 
 
 Iodine has been found in the following 
 sea-weeds, the alga? aquaticae of Linnaeus :~ 
 
 Fucus cartilagineus, 
 membranaceus, 
 filamentous, 
 rubens, 
 nodosus 
 serratus, 
 siliquosus, 
 
 Fucus palmatus, 
 filum, 
 digitatus, 
 saccharim us, 
 Ulva umbilicalis, 
 pavonia, 
 linza, and in 
 
 sponge. 
 
 Dr Fyfe has shewn, in an ingenious paper, 
 published in the first volume of the Edin. 
 Phil. Journal, that on adding sulphuric acid 
 to a concentrated viscid infusion of these 
 alga? in hot water, the vapour of iodine is 
 exhaled. 
 
 But it is from the incinerated sea-weed, 
 or kelp, that iodine in quantities, is to be ob- 
 tained. Dr W ollaston first communicated 
 a precise formula for extracting it. Dissolve 
 the soluble part of kelp in water. Concen- 
 trate the liquid by evaporation, and separate 
 all the crystals that can be obtained. Four 
 the remaining liquid into a clean vessel, and 
 mix with it an excess of sulphuric acid. Boil 
 this liquid for some time. Sulphur is preci- 
 pitated, and muriatic acid driven off. De- 
 cant oil’ the clear liquid, and strain it through 
 wool. Put it into a small flask, and mix it 
 with as much black oxide of manganese, as 
 used before of sulphuric acid. Apply to the 
 top of the flask a glass tube, shut at one 
 end. Then heat the mixture in the flask. 
 The iodine sublimes into the glass tube. 
 None can be obtained from sea- water. 
 
 In repeating this process with care, I ob- 
 tained from similar quantities of kelp such 
 variable products of iodine, that I was in- 
 duced to institute a series of experiments in 
 1814, for discovering the causes of these 
 anomalies, and for procuring iodine at an 
 easier jrate. The result, which was success- 
 ful, I communicated to the world in the 50th 
 volume of the Philosophical Magazine. In- 
 stead of procuring this interesting element 
 in only a few grains, I have been able to 
 extract ounces at a time, and at a mode- 
 rate expense. I shall here transcribe the 
 outlines of my method. 
 
 As several of the Scotch soap manufac- 
 turers use scarcely any other alkaline matter 
 for their hard soaps except kelp, it occurred 
 to me that in some of their residuums a sub- 
 stance might be found rich in iodine. Ac- 
 cordingly, after some investigation, I found a 
 brown liquid, of an oily consistence, from 
 which I expected to procure what I wanted, 
 and I therefore instituted a series of experi- 
 ments on the best mode of extraction. 
 
 The specific gravity of this liquid, as ob- 
 tained at different times, is pretty uniformly 
 1.374. It converts vegetable blues to green, 
 
IOD 
 
 IOD 
 
 thus indicating free alkali. Of this the ma- 
 nufacturer is aware, for he returns the liquid 
 occasionally into his kelp leys. Its boiling 
 point is 2,55° Fahr. Eight ounces apotheca- 
 ries’ measure require precisely one measured 
 ounce of sulphuric acid for their neutraliza- 
 tion. Supposing this quantity of acid com- 
 bined with soda, it would indicate one part 
 of pure soda in eleven by weight of the li- 
 quid. But the chief part of the alkali is not 
 uncombined ; for an immense quantity of 
 sulphurous acid, and a little sulphuretted 
 hydrogen gases, escape during the affusion 
 of the sulphuric acid. 
 
 “ 100 grains of the liquid yield 3.8 cubic 
 inches of gas, chiefly sulphurous acid, and 
 sulphur is at the same time deposited. From 
 this last circumstance one would expect a 
 greater proportion of sulphuretted hydrogen ; 
 but the disengaged gas possesses the peculiar 
 smell and pungency of burning sulphur, 
 blanches the petals of the red rose, but shews 
 scarcely any action on paper dipped in satur- 
 nine solutions. On the instant of decompo- 
 sition of the sulphite and hydroguretted sul- 
 phuret of soda existing in the liquid, the 
 nascent sulphurous acid of the former may 
 be supposed to decompose the nascent sul- 
 phuretted hydrogen of the latter; their atoms 
 of oxygen and hydrogen uniting, with preci- 
 pitation of the sulphur. I can in no other 
 way account for the very copious separation 
 of sulphur, while very little sulphuretted 
 hydrogen appears.” I now find the liquid to 
 contain hyposulphite of soda. 
 
 From 8 liquid ounces = 1 1 by weight, 
 213 grains of sulphur are obtained. The 
 saturated liquid has a specific gravity of 
 1.443, a bright yellow colour, and does not 
 change the purple colour of infusion of red 
 cabbage. 
 
 Having described the substance which 
 I used, I shall now state, in a few words, 
 the best method of taking the iodine out of 
 
 it : — 
 
 “ The brown iodic liquid of the soap- 
 boiler, was heated to about 230° F. poured 
 into a large stone- ware basin, of which it 
 filled about one- half, and saturated by the 
 addition of the suitable quantity of sulphuric 
 acid as above stated. It is advantageous to 
 dilute the acid previously, with its own bulk 
 of water. -f- On cooling the mixture, a large 
 quantity of saline crystals, is found adhering 
 to the sides and bottom of the vessel. These 
 are chiefly, sulphate of soda, with a very 
 little sulphate of potash, and a few beautiful 
 •oblong rhomboidal plates of hydriodate of 
 soda. Sulphur is mixed with these crystals. 
 
 Filter the above cold liquid, through 
 woollen cloth. To every 12 oz. apothecaries’ 
 
 f W hen concentrated acid is added, the offerves- 
 conce is very violent; the liquid reddens wherever 
 !; e acul fall5 > ailtl a little purple vapour of iodine 
 
 20 
 
 measure, add 1000 grains of black oxide oi 
 manganese in powder. Put this mixture in- 
 to a glass globe, or large matrass witn a 
 wide neck, over which a glass globe is in- 
 verted, and apply heat with a charcoal chauf- 
 fer. The less diffusive flame of a lamp, is 
 apt to crack the bottom of the matrass ; 
 particularly, if a large quantity of materials 
 be employed. To prevent the heat from 
 acting on the globular receiver, a thin disc 
 of wood, having a round hole in its 
 centre, is placed over the shoulder of the 
 matrass. 
 
 “ Iodine now sublimes very copiously, and 
 is readily condensed in the upper vessel. 
 As soon as this becomes warm, another is to 
 be put in its place; and thus the two may 
 be applied in rotation, as long as the violet 
 vapour rises. 
 
 “ From the above quantity of liquid, by this 
 treatment, I obtain from 180 to 200 grains 
 of iodine, perfectly pure. It is withdrawn 
 from the globes, most conveniently by a 
 little water, which dissolves iodine very spar- 
 ingly, as is well known. It may be purified 
 by a second sublimation from lime. 
 
 “ If the manganese be increased much be- 
 yond the above proportion, the product of 
 iodine is greatly decreased. If thrice the 
 quantity be used, for example, a furious 
 effervescence takes place, nearly the whole 
 mixture is thrown out of the matrass, with 
 a kind of explosive violence, and hardly any 
 iodine is procured, even though the materials 
 should be saved, by the relatively large ca- 
 pacity of the vessel that contains them. If, 
 on the other hand, one-half of the prescrib- 
 ed quantity of manganese be used, much 
 hydriodic acid rises along with the iodine, 
 and washes it perpetually down the sides of 
 the balloon. Or if, during the proper and 
 successful sublimation of iodine, the weight 
 of manganese be doubled, the violet vapours 
 instantly cease. Nor will sugar or starch 
 restore to the mixture, the power of exhaling 
 the iodine. 
 
 “ The same interruption of the process is 
 occasioned by using an excess of sulphuric 
 acid. For, if to the mixture of 1 2 oz. of 
 saturated liquid, with 1000 or 1100 grains 
 manganese, an additional half ounce mea- 
 sure of sulphuric acid be poured in, tho 
 violet vapour disappears, and the sublima- 
 tion of iodine is at an end. Quicklime now 
 added so as to saturate the excess of acid, 
 will not restore the production of iodine. 
 
 “ The best subliming temperature is 232° 
 
 “ Iodine, in open vessels, readily evaporates 
 at much lower temperatures, even at the 
 usual atmospheric heats. When it is spread 
 thin on a plate of glass, it the eye he placed 
 in the same piano, the violet vapour becomes 
 very obvious at tho temperature of 100° F. 
 If left in the open air, it will speedily eva- 
 
IOD 
 
 IOD 
 
 porate altogether away, even at 50° or 60°. 
 W hen kept in a phial stopped with a com- 
 mon cork, the iodine also disappears, while 
 the cork will become friable,, in its texture, 
 and of a brownish-yellow colour. 
 
 a 240 grains of nitric acid, specific gravity 
 1.490, saturate 1000 grains of the brown li- 
 quid. Sulphurous acid is abundantly ex- 
 haled as before. After filtration, a bright 
 golden coloured liquid is obtained. On 
 adding to this liquid a little manganese, 
 iodine sublimes ; but the quantity procur- 
 able in this way, seems to be proportionally 
 less than by the sulphuric acid.” 
 
 I have described a new form of apparatus, 
 for sublimation, in the above paper, by which 
 beautiful crystals may easily be procured, 
 without risk of injuring their form. 
 
 Iodine is a solid, of a greyish-black colour 
 and metallic lustre. It is often in scales 
 similar to those of micaceous iron ore, some- 
 times in rhomboidal plates, very large and 
 very brilliant. It has been obtained in 
 elongated octohedrons, nearly half an inch 
 in length ; the axes of which were shewn by 
 Dr Wollaston to be to each other, as the 
 numbers 2, 3, and 4, at least so nearly, that 
 in a body so volatile, it is scarcely possible to 
 detect an error in this estimate, by the reflec- 
 tive goniometer. Its fracture is lamellated, 
 and it is soft and friable to the touch. Its 
 taste is very acrid, though it be very sparing- 
 ly soluble in water. It is a deadly poison. 
 It gives a deep brown stain to the skin, 
 which soon vanishes by evaporation. In 
 odour, and power of destroying vegetable 
 colours, it resembles very dilute aqueous 
 chlorine. The sp. gr. of iodine at 62\° is 
 4.948. It dissolves in 7000 parts of water. 
 The solution is of an orange- yellow colour, 
 and in small quantity tinges raw starch of a 
 purple hue, which vanishes on heating it. 
 It melts, according to M. Gay Lussac, at 
 227° F. and is volatilized under the com- 
 mon pressure of the atmosphere, at the tem- 
 perature of 350°. By my experiments, it 
 evaporates pretty quickly at ordinary tempe- 
 ratures. Boiling water aids its sublimation, 
 as is shewn in the above process of extrac- 
 tion. The sp. gr. of its violet vapour is 
 8.678. It is a non-conductor of electricity. 
 When the voltaic chain is interrupted by a 
 small fragment of it, the decomposition of 
 water instantly ceases. 
 
 Iodine is incombustible, but; with azote it 
 forms a curious detonating compound ; and 
 in combining with several bodies, the in- 
 tensity of mutual action is such as to pro- 
 duce the phenomena of combustion. Its 
 combinations with oxygen and chlorine, have 
 been already described, under iodic and chlo- 
 riodic acids. 
 
 With a view of determining whether it 
 was a simple or compound form of matter, 
 Sir II. Davy exposed it to the action ol the 
 
 highly inflammable metals. When its va- 
 pour is passed over potassium heated in a 
 glass tube, inflammation takes place, and the 
 potass,um burns slowly with a pale blue 
 light. I heie was no gas disengaged when 
 the experiment was repeated in a mercurial 
 apparatus. I he iodide of potassium is white, 
 fusible at a red-heat, and soluble in water. 
 It has a peculiar acrid taste. When acted 
 on by sulphuric acid, it effervesces, and iodine 
 appears. It is evident that in this experi- 
 ment there had been no decomposition ; the 
 result depending merely on the combination 
 of iodine with potassium. By passing the 
 vapour of iodine over dry red-hot potash, 
 formed from potassium, oxygen is expelled, 
 and the above iodide results. Hence we 
 see, that at the temperature of ignition, the 
 affinity between iodine and potassium, is su- 
 perior to that of the latter for oxygen. But 
 iodine in its turn is displaced by chlorine, at 
 a moderate heat, and if the latter be in ex- 
 cess, chloriodic acid is formed. M. Gay 
 Lussac passed vapour of iodine in a red- 
 heat over melted subcarbonate of potash ; 
 and he obtained carbonic acid and oxygen 
 gases, in the proportions of two in volume 
 of the first, and one of the second, precisely 
 those which exist in the salt. 
 
 The oxide of sodium, and the subcarbo- 
 nate of soda, are also completely decomposed 
 by iodine. From these experiments it would 
 seem, that this substance ought to disengage 
 oxygen, from most of the oxides ; but this 
 happens only in a small number of cases. 
 The protoxides of lead and bismuth are the 
 only oxides not reducible by mere heat, with 
 which it exhibited that power. Barytes, 
 strontian, and lime, combine with iodine, 
 without giving out oxygen gas, and the 
 oxides of zinc and iron undergo no altera- 
 tion in this respect. From these facts we 
 must conclude, that the decomposition of the 
 oxides by iodine depends less on the con- 
 densed state of the oxygen, than upon the 
 affinity of the metal for iodine. Except 
 barytes, strontian, and lime, no oxide can 
 remain in combination with iodine at a red- 
 lieat. For a more particular account of 
 some iodides, see AciD(HYDRtomc) ; the com- 
 pounds of which, in the liquid or moist state, 
 are hydriodates, but change, on drying, into 
 iodides, in the same way as the muriates be- 
 come chlorides. 
 
 From the proportion of the constituents in 
 hydriodic acid, 1 5.5 has been deduced, as 
 the prime equivalent of iodine. 
 
 M. Gay Lussac says, “ Sulphate of potash 
 was not altered by iodine; but, what may ap- 
 pear astonishing, I obtained oxygen with the 
 ffuate of potash, and the glass tube in which 
 the operation was conducted was corroded. 
 On examining the circumstances of the ex- 
 periment, I ascertained that the fluate be- 
 came alkaline when melted in a platinum 
 
IOD 
 
 IOD 
 
 crucible. This happened to the fluate over 
 which I passed iodine. It appears then that 
 the iodine acts upon the excess of alkali, and 
 decomposes it. The heat produced disen- 
 gages a new portion of fluoric acid or its ra- 
 dical, which corrodes the glass ; and thus by 
 degrees the fluate is entirely decomposed.” 
 These facts seem to give countenance to the 
 opinion, that the fluoric is an oxygen acid ; 
 and that the salt called fluate of potash is not 
 a fluoride of potassium. See Acid (Fluo- 
 ric). 
 
 Iodine forms with sulphur a feeble com- 
 pound, of a greyish-black colour, radiated 
 like sulphuret of antimony. When it is 
 distilled with water, iodine separates. 
 
 Iodine and phosphorus combine with great 
 rapidity at common temperatures, producing 
 heat without light. From the presence of a 
 little moisture, small quantities of hydriodic 
 acid gas are exhaled. 
 
 Oxygen expels iodine from both sulphur 
 and phosphorus. 
 
 “ Hydrogen, whether dry or moist, did 
 not seem,” says M. Gay Lussac, “ to have 
 any action on iodine at the ordinary tempe- 
 rature ; but if, as was done by M. Clement, 
 in an experiment in which I was present, we 
 expose a mixture of hydrogen and iodine to 
 a red-heat in a tube, they unite together, and 
 hydriodic acid is produced, which gives a 
 reddish-brown colour to water.” Sir H. 
 Davy, with his characteristic ingenuity, threw 
 the violet-colOured gas upon the flame of hy- 
 drogen, when it seemed to support its com- 
 bustion. He also formed a compound of 
 iodine with hydrogen, by heating to redness 
 the two bodies in a glass tube. See Acid 
 (Hydriodic). 
 
 Charcoal has no action upon iodine, either 
 at a high or low temperature. Several of 
 the common metals, on the contrary, as zinc, 
 iron, tin, mercury, attack it readily, even at 
 a low temperature, provided they be in a di- 
 vided state. Though these combinations 
 take place rapidly, they produce but little 
 heat, and but rarely any light. 
 
 I he compound of iodine and zinc, or 
 iodide of zinc, is white. It melts readily, 
 and is sublimed in the state of fine acicular 
 four-sided prisms. It is very soluble in wa- 
 ter, and rapidly deliquesces in the air. It 
 dissolves in water, without the evolution of 
 any gas. The solution is slightly acid, and 
 does not crystallize. The alkalis precipitate 
 from it white oxide of zinc ; while concen- 
 trated sulphuric acid disengages hydriodic 
 acid and iodine, because sulphurous acid is 
 produced. The solution is a hydriodate of 
 oxide of zinc. When iodine and zinc are 
 made to act on each other under water in 
 vessels hermetically sealed, on the application 
 of a slight heat, the water assumes a deep 
 reddish-brown colour, because, as soon as 
 
 o r 
 
 m A 
 
 hydriodic acid is produced, it dissolves iodine 
 in abundance. But by degrees, the zinc 
 supposed to be in excess, combines with the 
 whole iodine, and the solution becomes co- 
 lourless like water. 
 
 Iron is acted on by iodine in the same 
 way as zinc ; and a brown iodide results, 
 which is fusible at a red-hcat. It dissolves 
 in water, forming a light green solution, like 
 that of muriate of iron. When the dry 
 iodide was heated, by Sir FI, Davy, in a 
 small retort containing pure aramoniacal gas, 
 it combined with the ammonia, and formed 
 a compound which volatilized without leav- 
 ing any oxide. 
 
 The iodide of tin is very fusible. When 
 in powder, its colour is a dirty orange- yel- 
 low, not unlike that of glass of antimony. 
 When put into a considerable quantity of 
 water, it is completely decomposed. Hy- 
 driodic acid is formed, which remains in so- 
 lution in the water, and the oxide of tin 
 precipitates in white flocculi. If the quan- 
 tity of water be small, the acid being more 
 concentrated, retains a portion of oxide of 
 tin, and forms a silky orange-coloured salt, 
 which may be almost entirely decomposed by 
 water. Iodine and tin act very well on each 
 other, in water of the temperature of 212°. 
 By employing an excess of tin, we may ob- 
 tain pure hydriodic acid, or at least an acid 
 containing only traces of the metal. The 
 tin must be in considerable quantity, because 
 the oxide which precipitates on its surface, 
 diminishes very much its action on iodine. 
 
 Antimony presents, with iodine, the same 
 phenomena as tin ; so that we might employ 
 either for the preparation of hydriodic acid, 
 if we were not acquainted with preferable 
 methods. 
 
 The iodides of lead, copper, Lv'smuth, sil- 
 ver, and mercury, are insoluble in water, 
 while the iodides of the very oxidizable me- 
 tals, are soluble in that liquid. If we mix a 
 hydriodate with the metallic solutions, all the 
 metals which do not decompose water will 
 give precipitates, while those which decom- 
 pose that liquid, will give none. This is at 
 least the case with the above mentioned 
 metals. 
 
 There are two iodides of mercury ; the 
 one yellow, the other red ; both are fusible 
 and volatile. The yellow or protiodide, con- 
 tains one-half less iodine than the deutiodide. 
 The latter, when crystallized, is a bright 
 crimson. In general there ought to be for 
 each metal as many iodides, as there aro 
 oxides and chlorides. All the iodides are 
 decomposed by concentrated sulphuric and 
 nitric acids. The metal is converted into an 
 oxide, and iodine is disengaged. They are 
 likewise decomposed by oxygen at a red- 
 hcat, if we except the iodides of potassium, 
 sodium, lead, and bismuth. Chlorine like- 
 
IRI 
 
 I III 
 
 wise separates iodine from all the iodides ; 
 but iodine, on the other hand, decomposes 
 most of the sulphurets and phosphurets. 
 
 W hen iodine and oxides act upon each 
 other in contact with water, very different 
 results take place, from those above describ- 
 ed. The water is decomposed; its hydrogen 
 unites with iodine, to form hydriodic acid ; 
 while its oxygen, on the other hand, pro- 
 duces with iodine, iodic acid. All the ox- 
 ides, however, do not give the same results. 
 We obtain them only with potash, soda, 
 barytes, strontian, lime, and magnesia. The 
 oxide of zinc, precipitated by ammonia from 
 its solution in sulphuric acid, and well wash- 
 ed, gives no trace of iodate and hydriodate. 
 
 We shall treat of the compound of iodine 
 and azote under the article Nitrogen. 
 
 From all the above recited facts, we are 
 warranted in concluding iodine to be an un- 
 decompounded body. In its specific gravity, 
 lustre, and magnitude of its prime equivalent, 
 it resembles the metals ; but in all its che- 
 mical agencies, it is analogous to oxygen and 
 chlorine. It is a non-conductor of electri- 
 city, and possesses, like these two bodies, the 
 negative electrical energy with regard to 
 metals, inflammable, and alkaline substances ; 
 and hence, when combined with these sub- 
 stances in aqueous solution, and electrized in 
 the voltaio circuit, it separates at the posi- 
 tive surface. But it has a positive energy 
 with respect to chlorine ; for when united to 
 chlorine, in the chloriodic acid, it separates 
 at the negative surface. This likewise cor- 
 responds with their relative attractive energy, 
 since chlorine expels iodine from all its com- 
 binations. Iodine dissolves in carburet of 
 sulphur, giving, in very minute quantities, 
 a fine amethystine tint to the liquid. 
 
 Iodide of mercury has been proposed for 
 a pigment ; in other respects, iodine has not 
 been applied to any purpose of common life. 
 M. Orfila swallowed 6' grains of iodine ; and 
 w r as immediately affected with heat, constric- 
 tion of the throat, nausea, eructation, saliva- 
 tion, and cardialgia. In ten minutes he had 
 copious bilious vomitings, and slight colic 
 pains. His pulse rose from 70 to about 90 
 beats in the minute. By swallowing large 
 quantities of mucilage, and emollient clys- 
 ters, he recovered, and felt nothing next day 
 but slight fatigue. About 70 or 80 grains 
 proved a fatal dose to dogs. They usually 
 died on the fourth or fifth day.* 
 
 Iridium. Mr Tennant, on examining the 
 black powder left after dissolving platina, 
 which from its appearance had been suppos- 
 ed to consist chiefly of plumbago, found it 
 contained two distinct metals, never before 
 noticed, which he has named iridium and 
 osmium. The former of these w 7 as observ- 
 ed soon after by Descostils, and by Vauque- 
 lin. 
 
 To analyze the black powder, Mr Tennant 
 
 put it into a silver crucible, with a large pro- 
 portion of pure dry soda, and kept it in a 
 red-heat for some time. The alkali being 
 then dissolved in water, it had acquired a 
 deep orange or brownish- yellow colour, but 
 much of the powder remained undissolved. 
 This digested in muriatic acid, gave a dark- 
 blue solution, which afterward became of a 
 dusky olive-green ; and finally, by continu- 
 ing the heat, of a deep red. The residuum 
 being treated as before with alkali, and so on 
 alternately, the wdiole appeared capable of 
 solution. As some silex continued to be 
 taken up by the alkali, till the whole of the 
 metal was dissolved, it seems to have been 
 chemically combined with it. The alkaline 
 solution contains oxide of osmium, with a 
 small proportion of iridium, which separates 
 spontaneously in dark-coloured thin flakes 
 by keeping it some weeks. 
 
 The acid solution contains likewise both 
 the metals, but chiefly iridium. By slow 
 evaporation, it affords an imperfectly crystal- 
 lized mass ; which, being dried on blotting- 
 paper, and dissolved in water, gives by eva- v 
 poration distinct octohedral crystals. These / 
 crystals, dissolved in w'ater, produce a deep 
 red solution, inclining to orange. Infusion 
 of galls occasions no precipitate, but instantly 
 renders the solution almost colourless. Mu- 
 riate of tin, carbonate of soda, and prussiate 
 of potash, produce nearly the same effect. 
 Ammonia precipitates the oxide, but, possi- 
 bly from being in excess, retains a part in 
 solution, acquiring a purple colour. The 
 fixed alkalis precipitate the greater part of 
 the oxide, but retain a part in solution, this 
 becoming yellow. All the metals that Mr 
 Tennant tried, except gold and platina, pro- 
 duced a dark or black precipitate from the 
 muriatic solution, and left it colourless. 
 
 The iridium may be obtained pure, bv ex- 
 posing the octohedral crystals to heat, which 
 expels the oxygen and muriatic acid. It 
 was white, and could not be melted by any 
 heat Mr Tennant could employ. It did not 
 combine with sulphur, or with arsenic. Lead 
 unites with it easily, but is separated by cu- 
 peliation, leaving the iridium on the cupel as 
 a coarse black powder. Copper forms with 
 it a very malleable alloy, which, after cupel- 
 lation, with the addition of lead, leaves a 
 small proportion of the iridium, but much less 
 than in the preceding instance. Silver forms 
 with it a perfectly malleable compound, the 
 surface of which is tarnished merely by cu- 
 pellation ; yet the iridium appears to be dif- 
 fused through it in fine powder only. Gold 
 remains malleable, and little altered in co- 
 lour, though alloyed with a considerable pro- 
 portion ; nor is it separable either by cupel- 
 lation or quartation. If the gold or silver 
 be dissolved, the iridium is left as a black 
 powder. 
 
 The French chemists observed, that this 
 
IRO 
 
 new metal gave a red colour to the triple 
 salt of platina and sal ammoniac, was not 
 altered by muriate of tin, and was precipitat- 
 ed of a dark brown by caustic alkali. Vau- 
 quelin added, that it was precipitated by 
 galls, and by prussiate of potash ; but Mr 
 Tennant ascribes this to some impurity. 
 
 Mr Tennant gave it the name of iridium, 
 from the striking variety of colours it affords 
 while dissolving in muriatic acid. 
 
 l)r Wollaston has observed, that among 
 the grains of crude platina, there are some 
 scarcely distinguishable from the rest but by 
 their insolubility in nitro-muriatic acid. 
 They are harder, however, when tried by 
 the file ; not in the least malleable ; and of 
 the specific gravity of 1 9.5. These appeared 
 to him to be an ore, consisting entirely of 
 two new metals. 
 
 * Vauquelin has since succeeded in form- 
 ing sulphuret of iridium, by heating a mix- 
 ture of ammonia-muriate of iridium and sul- 
 phur. It is a black powder consisting of 1 00 
 iridium -J- 33.3 sulphur ; whence, supposing 
 it a neutral compound, the prime equivalent 
 of iridium would be 6.0. The same chemist 
 has also alloyed iridium with lead, copper, 
 and tin. They are all malleable ; and con- 
 siderably hardened by the presence of the 
 iridium.* 
 
 Iron is a metal of a bluish white colour, 
 of considerable hardness and elasticity ; very 
 malleable, and exceedingly tenacious and 
 ductile. This metal is easily oxidized. A 
 piece of iron wire, immersed in a jar of oxy- 
 gen gas, being ignited at one end, will be 
 entirely consumed by the successive combus- 
 tion of its parts. It requires a very intense 
 heat to fuse it ; on which account it can only 
 be brougiit into the shape of tools and 
 utensils by hammering. This high degree 
 of infusibility would deprive it of the most 
 valuable property of metals, namely, the 
 uniting of smaller masses into one, if it did 
 not possess another singular and advantage- 
 ous property, which is found in no other 
 metal except platina ; namely, that of weld- 
 ing. In a white heat, iron appears as if 
 covered with a kind of varnish ; and in this 
 state, if two pieces be applied together, they 
 will adhere, and may be perfectly united by 
 forging. 
 
 When iron is exposed to the action of moist 
 air or water, it acquires weight by gradual 
 oxidation, and hydrogen gas escapes : this is 
 a very slow operation. But if the steam of 
 water be made to pass through a red-hot gun 
 barrel, or through an ignited copper or glass 
 tube, containing iron wire, the iron becomes 
 converted into an oxide, while hydrogen gas 
 passes out at the other end of the barrel. By 
 the action of stronger heat this becomes a red- 
 dish-brown oxide. The yellow rust, formed 
 wuen iron is long exposed to damp air, is not a 
 
 IRO 
 
 simple oxide, as it contains a portion of car- 
 bonic acid. 
 
 The concentrated sulphuric acid scarcely 
 acts on iron, unless it is boiling. If the acid 
 be diluted witli two or three parts of water, 
 it dissolves iron readily, without the assis- 
 tance of heat. During this solution, hydro- 
 gen gas escapes in large quantities. 
 
 The green sulphate of iron is much more 
 soluble in hot than cold water; and there- 
 fore crystallizes by cooling, as well as by eva- 
 poration. The crystals are efflorescent and 
 fall into a white powder by exposure to a dry 
 air, the iron becoming more oxidized than be- 
 fore. A solution of sulphate of iron, ex- 
 posed to the air, imbibes oxygen ; and a por- 
 tion of the iron, becoming peroxidized, falls 
 to the bottom. 
 
 Sulphate of iron is not made in the direct 
 way, because it can be obtained at less charge 
 from the decomposition of martial pyrites. 
 It exists in two states, one containing oxide 
 of iron, with 0.22 of oxygen, which is of a pale 
 green, not altered by gallic acid, and giving 
 a white precipitate with prussiate of potash. 
 The other, in which the iron is combined 
 with 0.50 of oxygen, is red, not crystallizable, 
 and gives a black precipitate with gallic acid, 
 and a blue with prussiate of potash. In the 
 common sulphate, these two are often mixed 
 in various proportions. 
 
 Sulphate of iron is decomposed by alkalis 
 and by lime. Caustic fixed alkali precipi- 
 tates the iron in deep green flocks, which are 
 dissolved by the addition of more alkali, and 
 form a red tincture. 
 
 Vegetable astringent matters, such as nut- 
 galls, the husks of nuts, logwood, tea, &c. 
 which contain tannin and gallic acid, preci- 
 pitate a fine black fecula from sulphate of 
 iron, which remains suspended for a consider- 
 able time in the fluid, by the addition of gum- 
 arabic. This fluid is well known by the 
 name of ink. See Ink. 
 
 The beautiful pigment, well known in the 
 arts by the name of prussian blue, is like- 
 wise a precipitate afforded by sulphate of iron. 
 
 Concentrated nitric acid acts very strongly 
 upon iron filings, much nitrous gas being 
 disengaged at the same time. The solution 
 is of a reddish-brown, and deposits the oxide 
 of iron after a certain time ; more especially 
 if the vessel be left exposed to the air. A 
 diluted nitric acid affords a more permanent 
 solution of iron of a greenish colour, or 
 sometimes of a yellow colour. Neither of 
 the solutions affords crystals, but both deposit 
 the oxide of iron by boiling, at the same 
 time that the fluid assumes a gelatinous ap- 
 pearance. 
 
 Diluted muriatic acid rapidly dissolves 
 iron at the same time that a large quantity 
 of hydrogen is disengaged, and the mixture 
 becomes hot. 
 
IRQ 
 
 IRO 
 
 If iron filings be triturated with muriate 
 of ammonia, moistening the mixture ; then 
 drying, powdering, and again triturating ; 
 and lastly subliming with a heat quickly 
 raised ; yellow or orange-coloured flowers 
 will rise, consisting of a mixture of muriate 
 of ammonia, with more or less muriate of 
 iron. These, which were called flowers of 
 steefl and still more improperly ens veneris , 
 were once much esteemed ; but are now little 
 used, as they are nauseous in solution, and 
 cannot very conveniently be given in any 
 other form. 
 
 Carbonic acid, dissolved in water, com- 
 bines with a considerable quantity of iron, 
 in proportion to its mass. 
 
 Phosphoric acid unites with iron, but very 
 slowly. The union is best effected by adding 
 an alkaline phosphate to a solution of one of 
 the salts ofiron, when it will fall down in a 
 white precipitate. This acid is found com- 
 bined with iron in the bog ores, and being 
 at first taken for a peculiar metal, was called 
 sidei'ite by Bergman. 
 
 Liquid fluoric acid attacks iron with vio- 
 lence ; the solution is not crystallizable, but 
 thickens to a jelly, which may be rendered 
 solid by continuing the heat. The acid may 
 be expelled by heating it strongly, leaving a 
 fine red oxide. 
 
 Borate of iron may be obtained by preci- 
 pitating a solution of the sulphate with 
 neutral borate of soda. 
 
 Arsenic acid likewise unites with iron. 
 This arseniate is found native. 
 
 Chromate of iron has been found in the 
 department of Var in France, and else- 
 where. 
 
 Sulphur combines very readily with iron. 
 A mixture of iron filings and flowers of sul- 
 phur being moistened, or made into a paste, 
 with water, becomes hot, swells, adheres to- 
 gether, breaks, and emits watery vapours of 
 an hepatic smell. If the mixture be consi- 
 derable in quantity, as for example, one 
 hundred pounds, it takes fire in twenty or 
 thirty hours, as soon as the aqueous vapours 
 cease. 
 
 By fusion with iron, sulphur produces a 
 compound of the same nature as the pyrites, 
 and exhibiting the same radiated structure 
 w hen broken. If a bar of iron be heated to 
 whiteness, and then touched with a roll of 
 sulphur, the two substances combine, and 
 drop down together in a fluid state. Mr 
 Hatchett found, that the magnetical pyrites 
 contains the same proportion as the artificial 
 sulphuret. 
 
 Phosphorus may be combined with iron 
 by adding it, cut into small pieces, to fine 
 iron wire heated moderately red in a cru- 
 cible ; or by fusing six parts of iron clip- 
 pings, w ith six of glacial phosphoric acid, 
 and one of charcoal powder. This plios- 
 pliuret is magnetic; and Mr Hatchett re- 
 
 marks, that iron, which in its soft or pure 
 stale cannot retain magnetism, is enabled 
 to do so when hardened by carbon, sulphur, 
 or phosphorus, unles the dose be so great as 
 to destroy the magnetic property, as in most 
 of the natural pyrites and plumbago. 
 
 The combination of carbon with iron is of 
 all the most important, and under the names 
 of Cast- Iron and Steel will be considered ia 
 the latter part of the present article. 
 
 Iron unites with gold, silver, and platina. 
 When heated to a white-heat, and plunged 
 in mercury, it becomes covered with a coat- 
 ing of that metal. Mr A. Aitken unites an 
 amalgam of zinc and mercury with iron fil- 
 ings, and then adds muriate of iron, when a 
 decomposition takes place, the muriatic acid 
 combining with the zinc, and the amalgam 
 ofiron and mercury assuming the metallic 
 lustre by kneading, assisted with heat. Iron 
 and tin very readily unite together. Iron 
 does not unite easily with bismuth, at least 
 in the direct way. This alloy is brittle and 
 attractible by the magnet, even with three- 
 fourths of bismuth. As nickel cannot be 
 purified from iron without the greatest diffi- 
 culty, it may be presumed, that these sub- 
 stances readily unite. Arsenic forms a brit- 
 tle substance in its combination with iron- 
 Cobalt forms a hard mixture with iron, which 
 is not easily broken. Manganese is almost 
 always united with iron in the native state. 
 Tungsten forms a brittle, whitish-brown, bard 
 alloy, of a compact texture, when fused 
 with white crude iron. The habitudes of 
 iron with molybdena are not known. 
 
 Iron is the most diffused, and the most 
 abundant of metallic substances. Few mi- 
 neral bodies or stones are without an admix- 
 ture of this metal. Sands, clays, the waters 
 of rivers and springs, are scarcely ever per- 
 fectly free from it. The parts of animal and 
 vegetable substances likewise afford iron in 
 the residues they leave after incineration. It 
 has been found native, in large masses, in 
 Siberia, and in the internal parts of South 
 America. This metal, however, in its native 
 state is scarce : most iron is found in the state of 
 oxide, in ochres, bog ores, and other friable 
 earthy substances, of a red, brown, yellow, or 
 black colour. The magnet or loadstone, is 
 an iron ore. Iron is also found in combina- 
 tion with the sulphuric acid, cither dissolved 
 in water, or in the form of sulphate. 
 
 In the large iron-works, it is usual to 
 roast or calcine the ores of iron, previous 
 to their fusion ; as well for the purpose 
 of expelling sulphureous or arsenical parts, 
 as to render them more easily broken into 
 fragments of a convenient size for melting. 
 The mineral is melted or run down, in 
 large furnaces, from 16 to SO feet high ; 
 and variously shaped, either conical or ellip- 
 tical, according to the opinion of the iron- 
 master. Near the bottom of the furnace is 
 
IRO 
 
 IRO 
 
 an aperture for the insertion of the pipe of 
 large bellows, worked by water or steam, or 
 of other machines for producing a current o t 
 air ; and there are also holes at proper parts 
 of the edifice, to be occasionally opened, to 
 permit the scoria? and the metal to flow out, 
 as the process may require. Charcoal or 
 coak, with lighted brushwood, is first thrown 
 in; and when the whole inside of the fur- 
 nace has acquired a strong ignition, the ore 
 is thrown in by small quantities at a time, 
 with more of the fuel, and commonly a por- 
 tion of limestone, as a flux ; the ore gradually 
 subsides into the hottest part of the furnace, 
 where it becomes fused ; the earthy part be- 
 ing converted into a kind of glass ; while the 
 metallic part is reduced by the coal, and falls 
 through the vitreous matter to the lowest 
 place.° The quantity of fuel, the additions, 
 and the heat, must be regulated, in order to 
 obtain iron of any desired quality ; and this 
 quality must likewise, in the first product, 
 be necessarily different, according to the 
 nature of the parts which compose the ore. 
 
 The iron which is obtained from the smelt- 
 ing furnaces is not pure ; and may be dis- 
 tinguished into three states : white crude iron, 
 which is brilliant in its fracture, and exhibits 
 a crystallized texture, more brittle than the 
 other kinds, not at all malleable, and so hard 
 as perfectly to withstand the file : grey crude 
 iron, which exhibits a granulated and dull 
 texture when broken ; this substance is not 
 so hard and brittle as the former, and is used 
 in the fabrication of artillery and other 
 articles which require to be bored, turned or 
 repaired : and black cast-iron,' which is still 
 rougher in its fracture ; its parts adhere to- 
 gether less perfectly than those of the grey 
 crude iron. 
 
 In order to convert it into malleable iron, 
 it is placed on a hearth, in the midst of char- 
 coal, urged by the wind of two pair of bel- 
 lows. As soon as it becomes fused, a work- 
 man continually stirs it with a long iron in- 
 strument. During the course of several 
 hours it becomes gradually less fusible, and 
 assumes the consistence of paste. In this 
 state it is carried to a large hammer, the re- 
 peated blows of which drive out all the parts 
 that still partake of the nature of crude iron 
 so much as to retain the fluid state. 13 y 
 
 repeated heating and hammering, more of 
 the fusible iron is forced out ; and the re- 
 mainder, being malleable, is formed into a 
 bar or other form for sale. Crude iron loses 
 upwards of one-fourth of its weight in the 
 process of refining; sometimes indeed one- 
 half. 
 
 Purified or bar iron is soft, ductile, flex- 
 ible, malleable, and possesses all the qualities 
 which have been enumerated under this ar- 
 ticle as belonging exclusively to iron. When 
 a bar of iron is broken, its texture appears 
 fibrous; a property which depends upon the 
 
 mechanical action of the hammer, while the 
 metal is cold. Ignition destroys this fibrous 
 texture, and renders the iron more uniform 
 throughout ; but hammering restores it. ^ . 
 
 If the purest malleable iron be beddeCt in 
 pounded charcoal, in a covered crucible, and 
 kept for a certain number of hours in a 
 strong red-heat, (which time must be longei 
 or shorter, according to the greater or less 
 thickness of the bars of iron), it is found, 
 that by this operation, which is called cemen- 
 tation, the iron has gained a small addition of 
 weight, amounting to about the hundred and 
 fiftieth, or the two-hundredth part ; and is 
 remarkably changed in its properties. 1 1 is 
 much more brittle and fusible than before. 
 Its surface is commonly blistered when it 
 comes out of the crucible ; and it requires 
 to be forged, to bring its parts together into 
 a firm and continuous state. This cement- 
 ed iron is called steel. It may be welded 
 like bar iron, if it have not been fused, or 
 over-cemented ; but its most useful and ad- 
 vantageous property is that of becoming ex- 
 tremely hard when ignited and plunged into 
 cold water. The hardness produced is great- 
 er in proportion as the steel is hotter, and 
 the water colder. The colours which appear 
 on the surface of steel slowly heated are yel- 
 lowish-white, yellow, gold colour, purple, 
 violet, deep blue, yellowish- white ; after 
 which the ignition takes place. These signs 
 direct the artist in tempering or reducing 
 the hardness of steel to any determinate stan- 
 dard. If steel be too hard, it will not be 
 proper for tools which are intended to have 
 a fine edge, because it will be so brittle, that 
 the edge will soon become notched ; if it be 
 too soft, it is evident, that the edge will bend 
 or turn. Some artists ignite their tools, and 
 plunge them into cold water: after which, 
 they brighten the surface of the steel upon a 
 stone : the tool being then laid upon char- 
 coal, or upon the surface of melted lead, or 
 placed in the flame of a candle, gradually 
 acquires the desired colour; at which instant 
 they plunge it into water. If a hard tem- 
 per be desired, the piece is dipped again, 
 and stirred about in the cold water as soon 
 as the yellow tinge appears. If the purple 
 appear before the dipping, the temper will 
 be fit for gravers, and tools used in work- 
 ing upon metals; if dipped while blue, it 
 will be proper for springs, and for instru- 
 ments used in the cutting of soft substances, 
 such as cork, leather, and the like ; but if 
 the last pale colour be waited for, the hard- 
 ness of the steel will scarcely exceed that of 
 iron. When soft steel is heated to any one 
 of these colours, and then plunged into wa- 
 ter, it does not acquire nearly so great a de- 
 gree of hardness, as if previously made quite 
 hard, and then reduced by tempering. The 
 degree of ignition required to harden steel 
 is different in the different kinds. The best 
 
IRQ 
 
 IIIO 
 
 kinds require only a low red-heat. The 
 harder the steel, the more coarse and gra- 
 nulated its fracture will be ; and as this is 
 not completely remedied by the subsequent 
 tempering, it is advisable to employ the 
 least heat capable of affording the requisite 
 hardness. 
 
 The usual time required fer the cementa- 
 tion of steel is from six to ten hours. If 
 the cementation be continued too long, the 
 steel becomes porous, brittle, of a darker 
 fracture, more fusible, and incapable of be- 
 ing forged or welded. On the contrary, steel 
 cemented with earthy infusible powders, is 
 gradually reduced to the state of forged iron 
 again. Simple ignition produces the same 
 effect; but is attended with oxidation of the 
 surface. The texture of steel is rendered 
 more uniform by fusing it before It is made 
 into bars : this is called cast steel ; and is 
 rather more difficultly wrought than com- 
 mon steel, because it is more fusible, and is 
 dispersed under the hammer if heated to a 
 white-heat. 
 
 The English steel made by cementation, 
 and afterward fused, and sold under the 
 name of cast steel, in bars, plates, and other 
 forms, possesses great reputation for its uni- 
 formity of texture, and other good qualities. 
 I have been informed by various authorities, 
 of which the respectability and connexions 
 are calculated to produce the most absolute 
 confidence, that all the prime steels of Eng- 
 land are made from Swedish iron, known in 
 this country by the name of steel iron, of 
 three different marks, the first of which 
 indicates the best quality, and the third the 
 worst. 
 
 The conversion of iron into steel, either 
 by fusion, viz. the direct change of crude 
 iron into steel, or by cementation of bar 
 iron, presents many objects of interesting in- 
 quiry. From various experiments of Berg- 
 man, it appeared, that good crude iron, kept 
 for a certain time in a state of fusion, with 
 such additions as appeared calculated to 
 produce little other effect than that of de- 
 fending the metal from oxidation, became 
 converted into steel with loss of weight. 
 These facts are conformable to the general 
 theory of Vandermonde, Monge, and Ber- 
 thollet : for, according to their researches, it 
 should follow that part of the carbon in the 
 crude iron was dissipated, and the remain- 
 der proved to be such in proportion as con- 
 stitutes steel. The same chemist cemented 
 crude iron with plumbago, or carbonate of 
 iron, and found that the metal had lost no 
 weight. Morveau repeated the experiment 
 with grey crude iron. The loss of weight 
 was little, if any. The metal exhibited the 
 black spot by the application of nitric acid, 
 as steel usually does, but it did not harden 
 by ignition and plunging in water. Hence I 
 conclude, that it was scarcely altered ; for 
 
 crude irons also exhibit the black spot, and 
 cannot by common management acquire the 
 hardness of steel. 
 
 By pursuing this train of reflection, it 
 will follow, that, since crude iron differs 
 from steel only in the superabundance of 
 carbon, it ought to be capable of extreme 
 hardness, if ignited to that degree, which is 
 requisite to combine the greater part of this 
 carbon with the iron, and then suddenly 
 cooled. This is accordingly found to be the 
 case. If the grey crude iron, commonly 
 distinguished by our founders by the name 
 of soft metal, be heated to a white-heat, and 
 then plunged into water, it becomes very 
 hard, much whiter, denser, and more metal- 
 lic in its appearance ; and will bear a pretty 
 good edge fit for gravers, for the use of turn- 
 ers in iron or steel. In these tools the angle 
 of the planes which form the edge is about 
 45°. The hardness of this kind of iron is 
 not considerably diminished but by ignition 
 continued for a length of time, which is a 
 fact also conformable to what happens in 
 steel. For the cast steel will be softened 
 nearly as much by annealing to the straw 
 colour, as the harder steels are by annealing 
 to a purple or full blue. 
 
 Some of our artists have taken advantage 
 of this property of soft crude iron in the fa- 
 brication of axles and collars for wheel- 
 work ; for this material is easily filed and 
 turned in its soft state, and may afterward 
 be hardened 60 as to endure a much longer 
 time of w ear. 
 
 The founders who cast wdieels and other 
 articles of mechanism, are occasionally em- 
 barrassed by this property. For, as the 
 metal is poured into their moulds of moist- 
 ened sand, the evaporation of the water car- 
 ries off a great portion of the heat, and cools 
 the iron so speedily, as to render it extreme- 
 ly hard, wdiite, and close in its texture. 
 This is most remarkable in sucli portions of 
 the metal, as have the greatest distance to 
 run from the git or aperture of reception. 
 For these come in contact successively with 
 a larger portion of the sand, and are there- 
 fore more suddenly cooled. I have seen 
 the teeth of cog-wheels altogether in this 
 state, w'hile the rim and other parts of the 
 wheel remained soft. The obvious remedy 
 for this defect is to increase the number of 
 gits, and to have the sand as dry as possible 
 or convenient. In other articles this pro- 
 perty has been applied to advantage, parti- 
 cularly in the steel rollers for large laminat- 
 ing mills. 
 
 I have been informed by a workman, that 
 ignited iron, suddenly plunged into the soft 
 leather of a shoe, becomes very hard on its 
 surface, which must arise from an instanta- 
 neous effect of case hardening. 
 
 The increase of dimensions acquired by 
 steel in hardening is such, that, in general, 
 
IRO 
 
 IRO 
 
 pieces of work finished soft will not fit their 
 places when hardened. 
 
 The fineness of grain in hard steel, as ex- 
 hibited in its fracture, is various according 
 to the quality of the metal, and the temper 
 it has received. The harder the steel the 
 coarser the grain. But in like circumstan- 
 ces, fine steel has the closest grain, and is 
 ever the most uniform in its appearance. 
 Workmen avail themselves much of this 
 indication. In general a neat curve lined 
 fracture, and even grey texture, denote 
 good steel ; and the appearance of threads, 
 cracks, or brilliant specks, denotes the con- 
 trary. But the management of the forging 
 and other circumstances of manufacturing 
 will modify these indications ; and the steel 
 that is good for some purposes, may be less 
 suited to others. 
 
 It is found, that steel is more effectually 
 hardened in cold than in warm water, and 
 at like temperatures more effectually in mer- 
 cury than in water. Oil is found to harden 
 the surface of steel much more than its in- 
 ternal part, so that it resists the file, but is 
 much less easily broken by the hammer. 
 Tallow differs from oil in the heat which 
 becomes latent for its fusion; and accord- 
 ingly, solid tallow is an excellent material 
 for hardening drills and other small articles. 
 The makers of files cover them with the 
 grounds of beer and common salt, which as- 
 sist their hardening, and keep the surface 
 from scorifying. The mucilage of the beer 
 supplies a coally matter ; and the fused salt 
 forms a varnish in the fire and defends the 
 steel. Very small articles heated in a candle 
 are found to be hardened perfectly by sud- 
 denly whirling them in the cold air ; and 
 thin bars or plates of steel, such as the mag- 
 netic needle of a compass, acquire a good 
 degree of hardness by being ignited, then 
 laid on a plate of cold lead, and suddenly 
 covered with another plate. These would 
 be unequally hardened, and bend, if plunged 
 in water. 
 
 The black spot which remains upon steel, 
 or crude iron, after its surface has been cor- 
 roded by acids, consists of plumbago, which 
 remains after the iron has disappeared by so- 
 lution. 
 
 Solution in the sulphuric or muriatic acid 
 not only exhibits the plumbago contained 
 in iion, but likewise possesses the advantage 
 of showing the state of its reduction by the 
 quantity of hydrogen gas which is disengag- 
 ed : for the quantity of this gas, in like cir- 
 cumstances, is proportional to that of the 
 iron which is converted into oxide. It is 
 found, that the white crude iron affords the 
 least quantity of hydrogen in proportion to 
 its bulk, and leaves a moderate portion of 
 plumbago; the grey crude iron affords more 
 hydrogen, and more plumbago than the 
 v'hitc; and the soltest bar iron affords most 
 
 hydrogen of any, and little or no plumbago. 
 The quantities of hydrogen gas, at a me- 
 dium, by ounce measures, were 62, afforded 
 by 100 grains of the white crude iron; 71 
 by the grey crude iron ; and 77 by the malle- 
 able iron. 
 
 Iron is one of the principal ingredients 
 for dyeing black. The stuff is first prepared 
 with a bath of galls and logwood, then with 
 a similar bath to which verdegris is added, 
 and lastly dyed in a similar bath, with the 
 addition of sulphate of iron. If it be wish- 
 ed, that the colour should be particularly 
 fine, the stuff should previously be dyed of a 
 deep blue : otherwise a brown may be first 
 given with the green husks of walnuts. Silk 
 however must not be previously blued with 
 indigo, and sumach may be substituted in- 
 stead of galls. Leather, prepared by tanning 
 with oak bark, is blackened by a solution of 
 sulphate of iron. 
 
 Cotton has a very strong affinity for oxide 
 of iron, so that, if it be immersed in a solu- 
 tion of any salt of iron, it assumes a chamois 
 colour, more or less deep according to the 
 strength of the solution. The action of the 
 air on the oxide of iron deepens the colour ; 
 and if the shade were at first deep, the tex- 
 ture of the stuff is liable to be corroded by 
 it. To prevent this, the cotton should be 
 immersed in the solution cold, carefully 
 wrung, and immediately plunged into a ley 
 of potash mixed with a solution of alum. 
 After having lain in this four or five hours, 
 it is to be wrung, washed, and dried. 
 
 In order to prevent gun-barrels from rust- 
 ing they are frequently browned. This is 
 done by rubbing it over when finished with 
 aquafortis or spirit of salt diluted with water, 
 and laying it by for a week or two till a 
 complete coat of rust is formed. A little 
 oil is then applied, and the surface, being 
 rubbed dry, is polished by means of a hard 
 brush and a little bees’ wax. 
 
 The yellow spots called iron moulds, which 
 are frequently occasioned by washing ink 
 spots with soap, may in general be removed 
 by lemon-juice, or the oxalic or citric acids ; 
 or by muriatic acid diluted with five or six 
 parts of water, but this must be washed off 
 in a minute or two. Ink spots may readily 
 be removed by the same means. If the 
 iron mould have remained so long, that the 
 iron is very highly oxidized, so as to be in- 
 soluble in the acid, a solution of an alkaline 
 sulphuret may be applied, and, after this has 
 been well washed off, the acid will remove 
 the stain. 
 
 * To the preceding details, which are se- 
 lected from Mr Nicholson’s work, I shall 
 subjoin a short systematic view of the chemi- 
 cal nature and relations of iron. 
 
 I. Of pure iron. 
 
 Its specific gravity is 7.7, but it maybe 
 made 7.8 by hammering. Under the article 
 
IRO 
 
 IRO 
 
 Cohesion, the tenacity of iron is given in re- 
 ference to other solids. In malleability it 
 is much inferior to gold, silver, and copper ; 
 though in ductility it approaches these me- 
 tals ; for iron wires .of l-150.th of an inch, 
 are frequently drawn. Its melting point is 
 estimated by Sir G. Mackenzie at 158° 
 Wedgewood ; the extreme heat of our che- 
 mical furnaces. 
 
 Dr Wollaston first shewed, that the forms 
 in which native iron is disposed to break, 
 are those of the regular octohedron and te- 
 trahedron, or rhomboid, consisting of these 
 forms combined. In a specimen possessed 
 by this philosopher, the crystalline surfaces 
 appear to have been the result of a process 
 of oxidation which has penetrated the mass to* 
 a considerable depth in the direction of its 
 laminae ; but in the specimen which is in 
 the possession of the Geological Society, the 
 brilliant surfaces that have been occasioned 
 by forcible separation from the original 
 mass, exhibit also the same configurations as 
 are usual in the fracture of octohedral crys- 
 tals, and are found in many simple metals. 
 This spontaneous decomposition of the me- 
 tal in the direction of its crystalline laminae 
 is a new and valuable fact. 
 
 From Mr Daniell’s ingenious experiments 
 on the mechanical structure of iron, deve- 
 loped by solution, we learn, that a mass of 
 bar iron which had undergone all the opera- 
 tions of p uddling and rolling , after being left 
 in liquid muriatic acid, till saturation, pre- 
 sented the appearance of a bundle of fasces, 
 whose fibres run parallel through its whole 
 length. At its two ends, the points were 
 perfectly detached from each other, and the 
 rods were altogether so distinct, as to appear 
 ,to the eye to be but loosely compacted. 
 
 1 1. Compounds of iron. 
 
 1. Oxides; of which there are two, or per- 
 haps three. 
 
 1. The oxide, obtained either by digest- 
 ing an excess of iron filings in water, by the 
 combustion of iron wire in oxygen, or by 
 adding pure ammonia to solution of green 
 copperas, and drying the precipitate out of 
 contact of air, is of a black colour, becoming 
 white by its union with water, in the hy- 
 drate, attractible by the magnet, but more 
 feebly than iron. By a mean of the experi- 
 ments of several chemists, its composition 
 seems to be, 
 
 Iron, 100 77.82 5.5 
 
 Oxygen, 28.5 22.18 1.0 
 
 Whence the prime equivalent of iron comes 
 out, we perceive, 3.5. Sir II. Davy’s num- 
 ber, reduced to the oxygen scale, is 0.86, 
 one-half of which, 3.43, is very nearly the 
 determination of Berzelius. But Mr Por- 
 rett, in an ingenious paper published in the 
 Annals of Philosophy for October 1819, 
 conceives that to make the theoretical pro- 
 
 portions relative to iron, harmonize with the 
 experimental results, we must consider 1 .75, 
 or the half of 3.5, as its true prime equiva- 
 lent, or lowest term of combination. The 
 protoxide will then consist of 2 primes of 
 iron to 1 of oxygen. 
 
 M. Thenard, in his Traite, vol. ii. p. 73. 
 says, the above oxide, obtained by decompos- 
 ing protosulphate of iron by potash or soda, 
 and washing the precipitate in close vessels 
 with water deprived of its air, consists, ac- 
 cording to M. Gay Lussac, of 100 parts of 
 iron, and 25 of oxygen. This determina- 
 tion would make the atom of iron 4.0 ; and 
 is probably incorrect. This proportion is 
 proved, he adds, by dissolving a certain 
 quantity of iron in dilute sulphuric acid, 
 and collecting the evolved hydrogen. Now, 
 by this method extreme precision should be 
 ensured. 
 
 2. Deutoxide of M. Gay Lussac. He 
 forms it, by exposing a coil of fine iron wire, 
 placed in an ignited porcelain tube, to a cur- 
 rent of steam, as long as any hydrogen comes 
 over. There is no danger, he says, of gene- 
 rating peroxide in this experiment, because 
 iron once in the state of deutoxide, has no 
 such affinity for oxygen, as to enable it to 
 decompose water. It may also, he states, 
 be procured by calcining strongly a mixture 
 of 1 part of iron and 3 parts of the red oxide 
 in a stone-ware crucible, to the neck of 
 which a tube is adapted to cut otf the con- 
 tact of air. But this process is less certain 
 than the first, because a portion of peroxide 
 may escape the reaction of the iron. But we 
 may dispense with the trouble of making it, 
 adds M. Thenard, because it is found abun- 
 dantly in nature. He refers to this oxide, 
 the crystallized specular iron ore of Klba, 
 Corsica, Dalecarlia, and Sweden, lie also 
 classes under this oxide, all the magnetio 
 iron ores ; and says, that the above described 
 protoxide does not exist in nature. From 
 the synthesis of this oxide by steam, M. Gay 
 Lussac has determined its composition to be 
 Iron, 100 72.72 
 
 Oxygen, S7.5 27.28, which Mr Porrett 
 
 reconciles to theory, by representing it us 
 consisting of 
 
 3 primes iron, 5.25 72.5 100 
 
 2 oxygen, 2.00 27.5 68 
 
 5. The red oxide. It may be obtained by 
 mnitinn; the nitrate, or carbonate; by calcin- 
 ing iron in open vessels ; or simply by treat- 
 ing the metal with strong nitric acid, then 
 washing and drying the residuum. Colco- 
 thar of vitriol, or thorough calcined copperas, 
 may be considered as peroxide of iron. It 
 exists abundantly native in the red iron ores. 
 It seems to be a compound of, 
 
 By Mr Porrett. 
 
 Iron, 100 70 =4 primes. 
 
 Oxygen, 43 30 = S primes. 
 
IRO 
 
 IRQ 
 
 2. Chlorides of iron ; of which there are 
 two, first examined in detail by Dr John 
 Davy. 
 
 The protochloride may be procured by 
 heating to redness, in a glass tube with a 
 very small orifice, the residue, which is ob- 
 tained by evaporating to dryness the green 
 muriate of iron. It is a fixed substance, re- 
 quiring a red-heat for its fusion. It has a 
 greyish variegated colour, a metallic splen- 
 dour, and a lamellar texture. It absorbs 
 chlorine, when heated in this gas, and be- 
 comes entirely converted into the volatile 
 deutochloride. It consists, by Dr Davy, of 
 Iron, 46,57 
 Chlorine, 53.43 
 By Mr Forrett, 
 
 2 primes iron, 5.5 43.7.5 100.0 
 
 1 chlorine, 4.5 56.25 128.7 
 
 The deutochloride may be formed by the 
 
 combustion of iron wire in chlorine gas, or 
 by gently heating the green muriate in a 
 glass tube. It is the volatile compound, 
 described by Sir H. Davy in his celebrated 
 Bakerian lecture on oxymuriatic acid. It 
 condenses after sublimation, in the form of 
 small brilliant iridescent plates. 
 
 It consists, by Dr Davy, of iron, 35.1 
 
 chlorine, 64.9 
 
 By Mr Porrett, 
 
 4 primes iron, 7.0 34.14 100.00 
 
 3 chlorine, 15.5 65.86 192.85 
 
 5. For the iodide of iron, see Iodine. 
 
 4. Sulphurets of iron ; of which, accord- 
 ing to Mr Porrett, there are four, though 
 only two arc usually described, his protosul- 
 pliuret, and persulphuret. 
 
 The prolosulphuret of iron exists in na- 
 ture. It has the metallic appearance of 
 bronze, but its powder is blackish-grey. It 
 is in fact the magnetic pyrites of mineralogy, 
 which see among the Ores of iron. By the 
 analyses of Mr Hatchett and Professor 
 Proust, it seems to consist of iron, 63 
 
 sulphur, 37 
 
 Mr Porrett represents it as composed of 
 
 2 primes iron = 3.5 63.75 100 
 
 1 sulphur 2.0 56.25 57 
 
 Ilis deutosulphate and tritosulphate are as 
 
 folio ws : 
 Deutos. 
 
 3 
 
 primes iron, 
 
 5.25 
 
 57 
 
 100 
 
 
 2 
 
 sulphur, 
 
 4.00 
 
 43 
 
 76 
 
 Tritos. 
 
 4 
 
 primes iron, 
 
 7.0 
 
 54 
 
 100 
 
 
 3 
 
 sulphur, 
 
 6.0 
 
 46 
 
 86 
 
 lie conceives, that in Proust’s experiments, 
 as related in the 1st volume of Nicholson’s 
 8vo Journal, descriptions of compounds cor- 
 responding to those two sulphurets are given. 
 
 The protosulphuret, is the cubic iron py- 
 rites of the mineralogist. It consists, by Mr 
 Porrett, of 
 
 1 prime iron, 1.75 46.5 100.0 
 
 I sulphur, 2.00 53.5 114.2; and 
 
 flic mean of Mr Hatchett’s celebrated expe- 
 
 riments on pyrites, published on the Phil. 
 Trans, for 1804, gives of iron, 100 
 
 sulphur, 115 
 
 5. Carburets of iron. These compounds 
 form steel, and probably cast-iron ; though 
 the latter contains also some other ingre- 
 dients. The latest practical researches on 
 the constitution of these carburets, are those 
 of Mr Daniel!, above quoted. 
 
 A mass of steel just taken from the cruci- 
 ble in which it had been fused, was subject- 
 ed to the action of muriatic acid. It was of 
 a radiated texture. When withdrawn from 
 the solvent, it presented a high crystalline 
 arrangement, composed of minute brilliant 
 plates. A bar of steel of an even granular 
 fracture being broken into two, the pieces 
 were heated in a furnace to a cherry- red. 
 In this state one of them was plunged into 
 cold water, and the other allow'ed to cool 
 gradually by the slow' extinction of the fire. 
 They were then both placed in muriatic 
 acid, to which a few drops of nitric acid had 
 been added. The softened piece of steel 
 was readily attacked ; but it required a pe- 
 riod five times greater to saturate the acid 
 with the hard piece. When the solvent had 
 ceased to act on both, they were examined. 
 The hard steel was exceedingly brittle, its 
 surface was covered with small cavities like 
 w'orm-eaten wood, but its texture was very 
 compact, and not at all striated. The other 
 piece was inelastic and flexible, and present- 
 ed a fibrous and wavy texture. On this 
 texture, the excellence of iron for mechanical 
 purposes is known to depend ; and the parts 
 not fibrous are thrown off by the processes of 
 puddling and hammering. By cutting the 
 iron bars into short pieces repeatedly, tying 
 them in bundles, and w'elding them toge- 
 ther, a similar interlacement of fibres is given 
 . ^ 
 to this valuable metal, as to flax and hemp, 
 
 by carding and spinning. May not the su- 
 perior quality of the Damascus sw'ord blades, 
 w'hich is still a problem, says Mr Daniell, to 
 our manufacturers, be owing to some such 
 management ? A specimen of while cast- 
 iron , of a radiated fracture, took just three 
 times as long to saturate a given portion of 
 acid, as a cube of grey cast-iron , or a mass 
 of bar iron. Its texture, after this action, 
 appeared to be composed of a congeries of 
 plates, aggregated in various positions, some- 
 times producing stars upon the surface, from 
 the intersection of their edges. A small bar 
 of , cold short iron, exceedingly brittle, and 
 presenting in its fracture bright and polished 
 surfaces, resembling antimony, after the action 
 of the acid, proved to be fibrous. A rod of 
 hot short iron presented, at the end of the 
 operation, a closely compacted mass of very 
 small fibres, perfectly continuous. The con- 
 geries was twisted, but the threads preserved 
 their parallelism. 
 
IRO 
 
 IRQ 
 
 MM. Berzelius and Stromeyer produced a 
 compound, which they consider as a com- 
 bination of iron, carbon, and silicium, the un- 
 known basis of silica. They mixed into a 
 paste with gum or linseed oil, very pure iron, 
 eilex, and charcoal, and heated the mixture 
 very intensely in a covered crucible. They 
 inferred that silicium, in the metallic or in- 
 flammable state, existed in the product, be- 
 cause the sum of the iron and silex extracted 
 from the alloy, very sensibly exceeded the 
 total weight of the alloy ; because the alloy 
 gave a much greater quantity of hydrogen, 
 with muriatic acid, than the iron alone which 
 it contained would have afforded ; and be- 
 cause there is no known combination of a 
 metal with an earth, which requires the suc- 
 cessive operation of the most powerful agents 
 to decompose it, as this alloy did. The colour 
 of this compound was that of common steel. 
 
 The quantities of the component parts, 
 however, of this alloy, differed very mate- 
 rially, from those of the purified carburet 
 obtained from cast-iron. The former varied 
 from the proportions of 
 
 Iron, 85.3 to 96. 1 
 Silicium, 9.2 2.2 
 
 Carbon, 5.3 1.6 
 
 The artificial compound was highly mag- 
 netical, while the triple carburet is not. Mr 
 Daniell, in examining by solution in acid, a 
 cube of grey cast-iron, obtained a porous 
 spongy substance, untouched by the men- 
 struum. It was easily cut oft' by a knife; 
 had a dark grey colour somewhat resembling 
 plumbago, and when placed in considerable 
 quantity on blotting paper to dry, it sponta- 
 neously heated, ignited and scorched the 
 paper. Its properties were not impaired by 
 being left for weeks in the solution of iron, 
 or in water. After a series of elaborate 
 analytical experiments, Mr Daniell infers 
 the composition of this cast-iron to be, 
 
 Iron, 84.66 
 
 Foreign matter, 1 5. 34 
 
 silex, 10.43 
 
 double carbur. 4.91 
 
 15.34 
 
 And 100 grains of the double carburet of 
 iron and silex upon an average of 5 experi- 
 ments, gave the following results : 
 
 lied oxide ) 3I 2 _ 28 . 0 b] ac k ox ide 
 or iron, } 
 
 Silex, 22.3 = 20.6 oxide of silicium ? 
 
 Carbon, 5 1 .4 = 5 1 .4 
 
 104.9 100.0 
 
 Although the existence of silicium in the 
 metallic state alloyed with iron, is not ac- 
 tually demonstrated by the preceding expe- 
 riments, yet it is rendered extremely proba- 
 ble. But, as Mr Daniell remarks, much 
 • remains to be done to complete our know- 
 ledge of tbe nature of cast-iron. 
 
 The composition of steel is also very va- 
 
 riable. According to M. Vauquelin, the 
 carbon forms y^Q part, on an average. By 
 enclosing diamonds in cavities of soft iron, 
 and igniting, the former disappeared, and 
 the inner surface of the latter was converted 
 into steel. Mr Clouet makes the carbon in 
 cast-iron = of the whole weight. But 
 Berzelius makes the latter species a very 
 complex compound. A specimen of very 
 pure cast-iron analyzed by him, yielded, 
 
 Iron, 98.83 
 
 Silicium, 0.50 
 
 Magnesium, 0.20 
 
 Manganese, 4.57 
 
 Carbon, S.90 
 
 100.00 
 
 Mr Mushethas inserted in several volumes 
 of the Phil. Magazine, many excellent papers 
 on the manufacture and habitudes of iron. 
 In the 5th volume of the Manchester Me- 
 moirs, a good account of the process used 
 at Sheffield for converting cast-iron into 
 pure iron, and pure iron into steel, has been 
 published by Mr Joseph Collier. He has 
 given a drawing of the steel furnace of ce- 
 mentation. I regret that the limits of this 
 work prevent me from transcribing their 
 valuable communications. I shall merely 
 annex Mr Mushet’s table of the proportions 
 of carbon corresponding to different carburets 
 of iron. 
 
 pgqj Soft cast steel. 
 
 ~lT)J) Common cast steel. 
 
 -gy The same, but harder, 
 yg The same too hard for drawing, 
 gy White cast-iron. 
 o\) Mottled cast-iron, 
 yy Black cast iron. 
 
 Graphite or plumbago, is also a carburet 
 of iron; containing about 10 per cent of 
 metal, which calling the prime of iron 1.75, 
 makes it a compound of 21 primes of car- 
 bon to 1 of metal. This congregation of 
 carbonaceous atoms, by a singular enough 
 coincidence, is precisely that assigned by 
 Dr Thomson, in his analysis of coal, as the 
 number clustered round azote, a body whose 
 atomic weight is also 1.75. Sec Annals of 
 Phil, for August 1819, p. 95. ibis ana- 
 logy may perhaps be regarded, by those who 
 hunt after harmonic numbers, as at once a 
 demonstration of the atom of iron being 
 1.75; and of an atom of carbon requiring 
 for saturation 21 atoms of a substance, 
 whose prime equivalent is to its own, as 
 1.75 is to 0.75. It is, however, rather un- 
 lucky for this fancy, that cyanogen or prus- 
 sine has been discovered. 
 
 Pure iron becomes instantly magnetic, 
 when presented to a magnetic bar; and as 
 speedily loses its magnetism, when the bar 
 is withdrawn. Its coercive power, in resist- 
 
IRO 
 
 IRO 
 
 ing the decomposition or recomposition of 
 the austral and boreal magnetisms, is ex- 
 tremely feeble. But when iron is combined 
 with oxygen, carbon, sulphur or phospho- 
 rus, it acquires the magneto-coercive virtue, 
 which attains a maximum of force, with cer- 
 tain proportions of the constituents, hitherto 
 undetermined. Mr Hatchett is the only 
 chemist who has adverted to this subject, in 
 a philosophical manner. — “ Speaking gene- 
 rally of the carburets, sulphurets, and phos- 
 phurets of iron, I have no doubt,” says he, 
 4< but that, by accurate experiments, we shall 
 find, that a certain proportion of the ingre- 
 dients of each, constitutes a maximum in the 
 magnetical power of these three bodies.” 
 
 The most useful alloy of iron, is that with 
 tin, in tin-plate. The surface of the iron 
 plates is cleaned first, by steeping in a crude 
 bran- vinegar, and then in dilute sulphuric 
 acid ; after which they are scoured bright 
 w r ith hemp and sand, and deposited in pure 
 w r ater, to prevent oxidation. Into a pot, 
 containing equal parts of grain and block- 
 tin in a state of fusion, covered with tallow, 
 the iron plates are immersed in a vertical 
 direction, having been previously kept for 
 about an hour in melted tallow. From 
 300 to 400 plates are tinned at a time : each 
 parcel requires an hour and a half for mu- 
 tual incorporation of the metals. After 
 lifting out the tinned plates, the stria? are 
 removed from their surfaces, and under 
 edges, by subsequent immersion, in melted 
 tin, and then in melted tallow, wiping the 
 surfaces at the same time with a hempen 
 brush. 
 
 Very curious and instructive experiments 
 on the alloys of steel with several metals, 
 with a view to improve cutting instruments 
 and reflecting mirrors, have been lately 
 made in the laboratory of the Royal Institu- 
 tion, of which an account is inserted in the 
 18th number of the Journal of Science. 
 
 Alloys of steel with platinum, rhodium, 
 gold, and nickel, may be obtained when the 
 heat is sufficiently high. This is so remark- 
 able with platinum, that it will fuse when in 
 contact with steel, at a heat at which the 
 steel itself is not affected. 
 
 I here are some very curious circum- 
 stances, attending the alloy of silver. If 
 steel and silver be kept in fusion together 
 for a length of time, an alloy is obtained, 
 which appears to be very perfect, while the 
 metals are in the fluid state, but on solidify- 
 ing and cooling, globules of pure silver are 
 expressed from the mass, and appear on the 
 surface of the button. If an alloy of this 
 kind, be forged into a bar, and then dissect- 
 ed, by the action of dilute sulphuric acid, 
 the silver appears not in combination with 
 the steel, but in threads throughout the 
 mass; so that the whole has the appearance 
 of a bundle of fibres of silver and steel, as 
 
 if they had been united by welding. The 
 appearance of these silver fibres is very 
 beautiful; they are sometimes one-eighth 
 of an inch in length, and suggest the idea 
 of giving mechanical toughness to steel, 
 where a very perfect edge may not be re- 
 quired. The most interesting result is the 
 following: — When 1 of silver and 500 steel 
 were properly fused together, a very perfect 
 button was produced ; no silver appeared on 
 its surface ; when forged and dissected by 
 an acid, no fibres were seen, although ex- 
 amined by a high magnifying power. The 
 specimen forged remarkably well, although 
 very hard ; it had, in every respect, the most 
 favourable appearance. By a delicate test, 
 every part of the bar gave silver. This al- 
 loy is decidedly superior to the very best 
 steel, and this excellence is unquestionably 
 owing to combination with a minute portion 
 of silver. It has been repeatedly made, and 
 always with success. Various cutting tools 
 have been made from it of the best quality. 
 Mr Stodart, a very eminent cutler, assisted 
 at these experiments, which must give the 
 public confidence in their practical results. 
 
 Equal parts by weight, of platinum and 
 steel, form a beautiful alloy, which takes a 
 fine polish, and does not tarnish ; the colour 
 is the finest imaginable for a mirror. The 
 ep. gr. of this beautiful compound is 9.862. 
 The proportions of platinum that appear to 
 improve steel for edge instruments, are from 
 1 to 5 per cent. While an alloy of 10 pla- 
 tinum with 80 steel, ;after lying many 
 months exposed, had not a speck on its sur- 
 face; an alloy of 10 nickel with 80 plati- 
 num, was in the same circumstances covered 
 with rust. 
 
 Ihe alloys of steel with rhodium, would 
 prove highly valuable, were it not for the 
 scarcity of the latter metal. 
 
 There is a species of steel made in India, 
 called ivootz , possessed of excellent quali- 
 ties, which seems to have been successfully 
 imitated in these late experiments at tho- 
 Royal Institution. In a previous number 
 of the same Journal, (14th), Mr Faraday 
 had detailed a minute, and apparently, a 
 very accurate analysis, operated on a part of 
 one of the cakes of wootz, presented by the 
 Right lion. Sir Joseph Banks, to Mr Sto- 
 dart. 460 grains gave 0.3 of a grain of si- 
 lex, 0.6 of a grain of alumina. 420 grains* 
 of the best English steel, furnished by Mr 
 Stodart, afforded no earths whatever. The 
 imitative synthesis was performed in the fol- 
 lowing wav : — 
 
 1 me steel in small pieces, and, in some 
 instances, good iron being mixed with char- 
 coal powder, were intensely heated for a, 
 long time. Thus, carburets, having a dark- 
 green metallic colour, were formed highly- 
 crystallized, resembling somevrhat the Iflack 
 ore of tellurium. When broken, the facets 
 
IRO 
 
 IRO 
 
 .of small buttons, not weighing riiore than 
 500 grains, were frequently above the eighth 
 ot an inch in width. I he results of several 
 experiments on its composition, which ap- 
 peared very uniform, gave 94.56 iron + 
 5.64 carbon. r l his being broken and rub- 
 bed to powder in a mortar, was mixed with 
 pure alumina, and the whole intensely heat- 
 ed in a close crucible for a considerable 
 time. On being removed from the furnace 
 and opened, an alloy was obtained of a 
 white colour, a close granular texture, and 
 very brittle. This, when analyzed, gave 
 6.4 per cent of alumina, and a portion of 
 carbon not accurately estimated. 700 of 
 good steel, with 40 of the alumina alloy, 
 were fused together, and formed a very 
 good button perfectly malleable. This, on 
 being forged into a little bar, and the sur- 
 face polished, gave, on the application of 
 sulphuric acid, the beautiful damask, pecu- 
 liar to wootz. A second experiment was 
 made with 500 grains of the same steel, and 
 67 of the alumina alloy, which also proved 
 good. It forged well, and gave the damask. 
 This specimen had all the appreciable cha- 
 racters of the best Bombay wootz. It is 
 highly probable, that the much admired 
 sabres of Damascus, are made from this 
 steel ; and if this be admitted, there can be 
 little reason to doubt, that the damask itself 
 is merely an exhibition of crystallization. 
 Wootz requires for tempering, to be heated 
 fully 40° F. above the best English cast 
 steel ; and affords a liner and more durable 
 edge. 
 
 When soft steel is ignited to a cherry-red, 
 and suddenly plunged in cold water, it is 
 rendered so hard as to resist the tile, and 
 nearly as brittle as glass. The tempering of 
 steel consists in reducing this excessive hard- 
 ness to a moderate degree, by a gentle heat- 
 ing, which also restores its toughness and 
 elasticity. In the year 1789, Mr Hartley 
 obtained a patent for a mode of tempering 
 cutting instruments of steel, by immersion 
 in oil, heated to a regulated temperature, 
 measured by a thermometer. This was cer- 
 tainly a great improvement, both in point of 
 precision and despatch, on the common me- 
 thod of heating the instrument over a flame, 
 till a certain colour, produced by a film of 
 oxide, appears on its surface. These colours 
 are, 
 
 At 480° F. a very faint yellow, for lancets. 
 
 450 a pale straw-colour for razors 
 and surgeons’ instruments. 
 
 470 a full yellow, for penknives. 
 
 490 a brown colour, for scissars and 
 chisels for cutting cold iron. 
 
 510 a brown, with purple spots, for 
 axes and plane-irons. 
 
 55 0 a purple, for table-knives and 
 
 large shears. 
 
 a bright blue, for swords, vvatch- 
 
 - springs, truss-springs, and 
 bell-springs. 
 
 500 a full blue, for small fine saws, 
 daggers, &c. 
 
 .600 dark-blue, verging on black, is 
 the softest of all the grada- 
 tions, when the metal be- 
 comes fit only for hand and 
 pit-saws, which must be soft, 
 that their teeth may bear 
 sharpening by the file, and 
 setting by the hammer, or 
 pliers. 
 
 If the steel be heated still further, it be- 
 comes perfectly soft. When tools having a 
 thick back and thin edge, like penknives, 
 are to be tempered, they are placed with 
 their back on a plate of hot iron or on hot 
 sand ; otherwise they would become too soft 
 at the edge, before the backs would be suffi* 
 ciently heated. To prevent warping of long 
 blades, or bars for magnets, they are gene- 
 rally hardened by being plunged vertically 
 into water. It is evident, that melted pew'- 
 ter, covered with grease, may be used in- 
 stead of hot oil for tempering steel ; the heat 
 being regulated by a thermometer. 
 
 Salts of iron* 
 
 These salts have the following general 
 characters : — 
 
 1. Most of them are soluble in water; 
 those with the protoxide for a base, are ge- 
 nerally erystallizable ; those with the per- 
 oxide, are generally not; the former are in- 
 soluble. the latter soluble in alcohol. 
 
 2. Ferroprussiate of potash throws down 
 a blue precipitate, or one becoming blue in 
 the air. 
 
 5. Infusion of galls gives a dark purple 
 precipitate, or one becoming so in the air. 
 
 4. Hydrosulphuret of potash or ammonia 
 gives a black precipitate ; but sulphuretted 
 hydrogen merely deprives the solutions of 
 iron of their vel low-brown colour. 
 
 5. Phosphate of soda gives a whitish pre- 
 cipitate. 
 
 6. Benzoate of ammonia, yellow. 
 
 7. Succinate of ammonia, flesh-coloured 
 with the peroxide. 
 
 1. Protcicetate of iron forms small prisma- 
 tic crystals, of a green colour, a sweetish 
 styptic taste, and a sp. gr. 1.S68. 
 
 2. Peracetate of iron forms a reddish- 
 brown un erystallizable solution, much used 
 by the calico printers, and prepared by keep- 
 ing iron-turnings, or pieces of old iron, for 
 six months immersed in redistilled pyrolig- 
 nous acid. See Acid (Acetic). 
 
 3. Protarseniate of iron exists native in 
 crystals, and may be formed in a pulverulent 
 state, by pouring arseniate of ammonia into 
 sulphate of iron. It is insoluble, and con- 
 sists, according to Chenevix, of 38 acid, 43 
 oxide, and 19 water, in 100 parts. 
 
 4. Perarscniate f iron may be formed by 
 
 550 
 
IRQ 
 
 IRQ 
 
 pouring arseniate of ammonia into peracetate 
 of iron ; or by boiling nitric acid on the 
 protarseniate. It is insoluble. 
 
 5. Antimoniate oj'iron is white, becoming 
 yellow, insoluble. 
 
 6. Borate , pale yellow, insoluble. 
 
 7. Benzoate , yellow, do. 
 
 8. Prolocarbonate , greenish, soluble. 
 
 9. Per carbonate , brown, insoluble. 
 
 10. Chromate, blackish, do. 
 
 1 1. Protocitrate , brown crystals, soluble. 
 
 12. Protoferroprussiate, white insoluble. 
 
 13. Perferroprussiate , white, do. 
 
 This constitutes the beautiful pigment 
 
 called prussian blue. When exposed to a 
 heat of about 400°, it takes fire in the open 
 air ; but in close vessels it is decomposed, 
 apparently, into carburetted hydrogen water, 
 and hydrocyanate of ammonia, which come 
 over ; while a mixture of charcoal and oxide 
 of iron remains in the state of a pulverulent 
 pyrophorus, ready to become inflamed with 
 contact of air. I have already considered 
 the constitution of prussian blue, in treating 
 of the Acid (Ferroprussic) ; and have 
 little farther to add to what is there stated 
 concerning this intricate compound. I per- 
 ceive that Dr Thomson has recently publish- 
 ed (Ann. of Phil, for September 1820) a 
 new igneous analysis of prussian blue. He 
 gives now satisfactory evidence, that hydro- 
 cyanate of ammonia is one of the products, 
 which his former short notice left somewhat 
 in doubt. But the details of his analysis 
 are blended with so many theoretical suppo- 
 sitions, that instead of clearing up the mat- 
 ter, they seem to involve it in greater mys- 
 tery. 
 
 I shall avail myself, however, of this op- 
 portunity of presenting my readers with the 
 valuable investigations of M. Robiquet on 
 the nature of prussian blue, published in the 
 1 2th vol. of the Ann. de Chimie et Physique . 
 
 When sulphuric acid is added to prussian 
 blue, it makes it perfectly white, apparent- 
 ly by abstracting its w ater ; for the blue co- 
 lour returns on dilution of the acid, and if 
 the strong acid be poured off, it yields no 
 traces of either prussic acid or iron. On 
 submitting pure prussian blue for some time 
 to the action of sulphuretted hydrogen wa- 
 ter, small brilliant crystals of a yellowish co- 
 lour appeared, which became blue in the air, 
 and were protoprussiate of iron. M. Robi- 
 quet has succeeded in obtaining the acid 
 of prussian blue in a solid crystalline state , by 
 a different process from Mr Porrett’s. Strong 
 muriatic acid, in large quantity, being mixed 
 with pure prussian blue, and left for some 
 time, the sediment becomes of a green colour, 
 and then yellow. If water be added to this 
 mixture, it is again rendered blue ; but if 
 no water be added, and if it be allowed to 
 stand in a narrow vessel, the sediment falls 
 to the bottom, and a deep red-brown solu- 
 
 tion covers it.- This is an acid solution of 
 muriate of iron, and cannot be made to pro- 
 duce a blue by any method tried. The sedi- 
 ment was allowed to contract itself for seve- 
 ral days, and the supernatant liquor being 
 drawn off by a little syphon, the washing w T as 
 then repeated with concentrated muriatic 
 acid as before, until the process w r as suppos- 
 ed to be complete. The magma was now 
 collected into a capsule, and placed in a re- 
 ceiver, containing much lime, to dry. When 
 dry it was digested in alcohol, filtered and 
 evaporated spontaneously, and a number of 
 small crystals w r ere obtained. These crys- 
 tals were separated, w’ashed in fresh alcohol, 
 and again crystallized ; and w ere then the 
 pure acid of prussian blue, or the ferrochya- 
 zic acid of Mr Porrett. 
 
 These crystals appear at times to be tetra- 
 hedral ; they are white when pure ; but be- 
 come slightly blue by exposure to the air. 
 They have no odour ; their taste is acid and 
 peculiar, without being like that of prussic 
 acid. They are soluble in water and alco- 
 hol. The colourless solution produces an 
 immense precipitate of prussian blue, in per- 
 sulphate of iron. The acid perfectly satu- 
 rates potash, and produces the common tri- 
 ple prussiate of potash. If it be heated, a 
 considerable quantity of prussic acid first 
 passes off, the remainder becomes of a deep 
 blue colour, and insoluble. When heated in 
 close vessels, the prussic acid is given off as 
 before, perfectly pure, and no other effect 
 takes place, if the temperature be below that 
 of boiling mercury. The residue is yellow- 
 ish-brown, but becomes nearly black in the 
 air ; it contains ammonia* and the iron is in 
 such a state of combination, that it is not 
 affected either by sulphuric acid or the mag- 
 net. If this residuum be heated still higher, 
 then prussic acid in small quantities, and 
 hydrogen and azote, in the proportion of one 
 to two, come off, and charcoal and metallic 
 iron remain. No carbonic acid is found in 
 this experiment ; hence the iron is in the' 
 metallic state in the acid. M. Robiquet con- 
 cludes from this experiment, that the pecu- 
 liar acid is a combination of prussic acid 
 and cyan u ret (prusside) of iron, formed by 
 affinities so powerful, that the poisonous 
 properties of the prussic acid are entirely- 
 neutralized and lost. 
 
 “ It results,” says M. Robiquet, “ from 
 what has been said, — 
 
 “ 1. That potash is an essential element 
 in the white prussiate of iron. 
 
 “ 2. That the protoprussiate of iron is 
 slightly soluble in water, capable of being 
 crystallized, and of a yellow colour. 
 
 “ 3. That the acid of prussian blue, and 
 of triple prussiate in general, is a combina- 
 tion of iron, cyanogen, and prussic acid. 
 
 “ 4. That prussian blue, and the triple 
 prussiates in general, arc formed of a cyanu- 
 
ISE 
 
 1 110 
 
 ret and a liydrocyanate (a prusside and prus- 
 siate). 
 
 “ 5. 4 hat it is probable that prussian 
 blue owes its colour to a certain quantity of 
 water.” 
 
 These curious details of M. Braconnot 
 have the air of chemical research, and do 
 him much honour. 
 
 I consider Mr Forrett’s process for obtain- 
 ing crystallized ferroprussic acid to be more 
 elegant than M. Robiquet’s. Ho dissolved 
 58 gr. of crystallized tartaric acid in spirit 
 of wine, and poured the solution into a phial 
 containing 50 gr. of ferruretted chyazate of 
 potash dissolved in 2 or 3 drachms of warm 
 water : by this process the whole of the tar- 
 taric acid will combine with, and precipitate 
 the potash, in the state of supertartrate of 
 potash, and the alcoholic fluid will contain 
 nothing but ferruretted chyazic acid, which 
 may be obtained from it, in small crystals, 
 generally resembling a cube, by spontaneous 
 evaporation. — Annals of ‘ Philosophy J'or Sep- 
 tember 1818. 
 
 14. Protogallate, colourless, soluble. 
 
 15. Pergallate , purple, insoluble. 
 
 16. Protomuriate , green crystals, very so- 
 luble. 
 
 17. Permuriate, brown, uncrystallizable, 
 very soluble. See the chlorides of iron pre- 
 viously described. 
 
 18. Protonitrate , pale green, soluble. 
 
 1 9. Perniirate, brown, do. 
 
 20. Protoxalate , green prisms, do. 
 
 21. Peroxalate, yellow, scarcely soluble. 
 
 22. Protophosphate , blue, insoluble. 
 
 23. Perphosphate , white, do. 
 
 24. Protosuccinate, brown crystals, solu- 
 ble. 
 
 25. Persuccinate , brownish- red, insoluble. 
 
 26. Protosulphate, green vitriol, or copper- 
 as. It is generally formed by exposing native 
 pyrites to air and moisture, when the sulphur 
 and iron both absorb oxygen, and form the 
 salt. There is, however, an excess of sul- 
 phuric acid, which must be saturated by 
 digesting the lixivium of the decomposed 
 pyrites with a quantity of iron plates or 
 turnings. 
 
 It forms beautiful green crystals, which 
 arc transparent rhomboidal prisms, whose 
 faces are rhombs with angles ol 79° 50' and 
 100° 10', inclined to each other at angles 
 of 98° 57' and 81° 23'. Sp. gr. 1.84. Its 
 taste is harsh and styptic. It reddens vege- 
 table blues. Two parts of cold and three- 
 fourths of boiling water dissolve it. It does 
 not dissolve in alcohol. Exposure to air 
 converts the surface of the crystals into a red 
 deutosulphatc. A moderate heat whitens it, 
 by separating the water of crystallization, and 
 a stronger heat drives off the sulphuric acid. 
 Its constituents are 28.9 acid, 28.o prot- 
 oxide, and 45 water, according to Berzelius; 
 
 consisting, by Mr Porrett’s views, of 1 prime 
 acid -J- 2 oxide 7 water. 
 
 27. Persulphate. Of this salt there seems 
 to be four or more varieties, having a ferre- 
 ous base, which consists, by Mr Porrett, of 4 
 primes iron + 3 oxygen = 10 in weight, 
 from which their constitution may be learned. 
 
 The tartrate and pertartrate of iron may 
 also be formed ; or, by digesting cream of 
 tartar with water on iron filings, a triple salt 
 may be obtained, formerly called tartarizod 
 tincture of Mars. 
 
 Iron is one of the most valuable articles of 
 the materia medica. The protoxide acts as 
 a genial stimulant and tonic, in all cases of 
 chronic debility not connected with organic 
 congestion or inflammation. It is peculiarly 
 efficacious in chlorosis. It appears to me 
 that the peroxide and its combinations are 
 almost uniformly irritating, causing heart- 
 burn, febrile heat, and quickness of pulse. 
 Many chalybeate mineral waters contain an 
 exceedingly minute quantity of protocarbo- 
 nate of iron, and yet exercise an astonishing 
 power in recruiting the exhausted r ’rame. I 
 believe their virtue to be derived simply from 
 the metal being oxidized to a minimum, and 
 diffused by the agency of a mild acid through 
 a great body of water, in which state it is 
 rapidly taken up by the lacteals, and speedily 
 imparts a ruddy hue to the wan countenance. 
 I find that these qualities may be imitated 
 exactly, by dissolving 3 grains of sulphate of 
 iron, and 60 of bicarbonate of potash, in a 
 quart of cool water, with agitation in a close 
 vessel.* 
 
 * Ikon-flint. Eeisenkiesel. — JPerncr. 
 
 Colours, brown and red. Massive, and 
 crystallized in small equiangular six-sided 
 prisms, acuminated on both extremities. It 
 occurs commonly in small angulo-granular 
 distinct concretions. Lustre, vitreo- resinous. 
 Fracture small conchoidal. Opaque. Gives 
 sparks with steel. Rather difficultly frangi- 
 ble. Sp.gr. 2.6 to 2.8. Infusible. Its 
 constituents are 93.5 silica, 5 oxide of iron, 
 and 1 volatile matter. The red iron-flint 
 contains 21.7 oxide of iron, and 76.8 silica. 
 It occurs in veins 1 in ironstone, and in trap- 
 rocks, near Bristol, in the island of Rath- 
 lin, at Dunbar, and in many parts of Ger- 
 many. — Jameson.* 
 
 * Isatis Tinctoria. The plant used for 
 dyeing, called icoad.* 
 
 * Iserine. Colour, iron-black. In small 
 obtuse angular grains. Lustre, splendent or 
 glistening, and metallic. Fracture conchoi- 
 dal. Opaque. Harder than felspar. Brit- 
 tle. Retains its colour in the streak. Sp. 
 gr. 4.6. It melts into a blackish-brown 
 glass, which is slightly attracted by the mag- 
 net. The mineral acids have no effect on it, 
 but oxalic acid extracts a portion of the tita- 
 nium. Its constituents are ‘18 oxide of tita- 
 
KER 
 
 nium, 48 oxide of iron, and 4 uranium, by 
 J)r Thomson’s analysis of the iserine, found 
 in the bed of the river Don, in Aberdeen- 
 shire ; but, by Klaproth, it consists of 28 
 oxide of titanium, and 72 oxide of iron. On 
 the continent it has hitherto been found only 
 in the lofty Riesengebirge, near the origin 
 of the stream called the Iser, disseminated 
 in granite sand ; and in alluvial soil along 
 with pyrope in Bohemia. — Jameson .* 
 
 Isinglass. This substance is almost 
 wholly gelatine ; 100 grains of good dry is- 
 inglass containing rather more than 98 of 
 matter soluble in water. 
 
 Isinglass is made from certain fish found 
 
 o 
 
 in the Danube, and the rivers of Muscovy. 
 Willoughby and others inform us, that it is 
 made of the sound of the Beluga ; and Neu- 
 mann, that it is made of the Huso German- 
 orum, and other fish, which he has frequent- 
 ly seen sold in the public markets of Vienna. 
 Mr Jackson remarks, that the sounds of cod, 
 properly prepared, afford this substance ; and 
 that the lakes of America abound with fish 
 from which the very finest sort may be ob- 
 tained. 
 
 Isinglass receives its different shapes in 
 the following manner: — 
 
 The parts of which it is composed, par- 
 ticularly the sounds, are taken from the fish 
 while sweet and fresh, slit open, washed from 
 their slimy sordes, divested of a very thin 
 membrane which envelops the sound, and 
 then exposed to stiffen a little in the air. 
 In this state, they are formed into rolls about 
 the thickness of a finger, and in length ac- 
 cording to the intended size of the staple : a 
 thin membrane is generally selected for the 
 centre of the roll, round which the rest are 
 folded alternately, and about half an inch of 
 each extremity of the roll is turned inwards. 
 
 Isinglass is best made in the summer, as 
 frost gives it a disagreeable colour, deprives 
 
 KER 
 
 it of weight, and impairs its ^gelatinous prin- 
 ciples. 
 
 Isinglass boiled in milk forms a mild nu- 
 tritious jelly, and is thus sometimes employ- 
 ed medicinally. This, when flavoured by 
 the art of the cook, is the blanc-manger of 
 our tables. A solution of isinglass in water, 
 with a very small proportion of some balsam, 
 spread on black silk, is the court- plaster of 
 the shops. 
 
 Ivoiiy. The tusk, or tooth of defence of 
 the male elephant. It is an intermediate 
 substance, between bone and horn, not ca- 
 pable of being softened by fire, not altoge- 
 ther so hard and brittle as bone. Sometimes 
 it grows to an enormous size, so as to weigh 
 near two hundred pounds. 
 
 The entire tooth is of a yellowish, brown- 
 ish, and sometimes a dark brown colour on 
 the outside, internally white, hollow towards 
 the root, and so far as was inserted into the 
 jaw, of a blackish brown- colour. The finest, 
 whitest, smoothest, and most compact ivory 
 comes from the island of Ceylon. The 
 grand consumption of this commodity is for 
 making ornamental utensils, mathematical 
 instruments, cases, boxes, balls, combs, dice, 
 and an infinity of toys. The workmen have 
 methods also of tingeing it of a variety of 
 colours. 
 
 Merat Guillot obtained from 100 parts of 
 ivory, 24 gelatine, 64 phosphate of lime, and 
 0. 1 carbonate of lime. 
 
 The coal of ivory is used in the arts under 
 the denomination of ivory-black. Particular 
 vessels are used in the manufactory of this 
 pigment, for the purpose of rendering it per- 
 fectly black. 
 
 Some travellers speak of the tooth of the 
 sea-horse as an excellent ivory ; but it is too 
 hard to be saw'ed or wrought like ivory. It 
 is used for making artificial teeth. 
 
 K ali. See Potash. 
 
 Kaolin. The Chinese name of por- 
 celain clay. 
 
 Kedria I errestris. Barbadoes tar. See 
 Bitumen. 
 
 * Kelp. Incinerated sea-weed. See 
 Soda. * 
 
 Kermes ( coccus ilicisy Lin.) is an insect 
 found in many parts of Asia, and the south 
 of Europe. 
 
 On account of their figure, they were a 
 1 long time taken for the seeds of the tree on 
 which they live ; whence they were called 
 ! grains of kermes . They also bore the name 
 •of vermilion. 
 
 Io dye spun worsted with kermes, it is 
 
 first boiled half an hour in water with bran, 
 then tw r o hours in a fresh bath with one-fifth 
 of Roman alum, and one-tenth of tartar, to 
 which sour water is commonly added ; after 
 which it is taken out, tied up in a linen bag, 
 and carried to a cool place, where it is left 
 some days. To obtain a full colour, as much 
 kermes as equals three-fourths, or even the 
 whole of the weight of the wool, is put into 
 a warm bath, and the wool is put in at the 
 first boiling. As cloth is more dense than 
 wool, either spun or in the fleece, it requires 
 one-fourth less of the salts in the boiling, and 
 of kermes in the bath. 
 
 i he colour that kermes imparts to wool 
 has much lens bloom than the scarlet made 
 
LAB 
 
 LAB 
 
 with cochineal ; whence the latter has ge- 
 nerally been preferred, since the art of 
 heightening its colour by means of solution 
 of tin has been known. 
 
 Kermes Mineral. See Antimony. 
 
 * Kiffekill. See Meerschaum.* 
 
 * Kinate of Lime. A salt which forms 
 t per cent of cinchona. See Acid (Kinic).* 
 
 Kino. A few years ago this was intro- 
 duced into our shops and medical practice 
 by the name of a gum ; but Dr Duncan has 
 
 shown that it is an extract. * It contains 
 also a species ot tannin, whence it is used as 
 an astringent in diarrhoeas.* 
 
 * Klebschiefer. Adhesive slate.* 
 
 * Konite. See Conite.* 
 
 * Koumiss. A vinous liquid, which the 
 Tartars make by fermenting mare’s milk. 
 Something similar is prepared in Orkney 
 and Shetland.* 
 
 Kupfer Nickel. See Nickel, 
 
 L ABDANUM. A resin of a species of 
 cistus in Candia, of a blackish colour. 
 The country people collect it by means of 
 a stall', at the end of which are fastened many 
 leather thongs, which they gently strike on 
 the trees. They form it into cylindrical 
 pieces, which are called labdanum in torlis. 
 It is greatly adulterated by the addition of 
 black sand. It has been used in cephalic 
 and stomachic plasters and perfumes. 
 
 Laboratory. A place properly fitted up 
 for the performance of chemical operations. 
 
 As chemistry is a science founded entirely 
 on experiment, we cannot hope to under- 
 stand it well, without making such experi- 
 ments as verify most of the known funda- 
 mental operations, and also such as reason- 
 ing, analogy, and the spirit of inquiry, never 
 fail to suggest to those, whose taste and suit- 
 able talents lead them to this essential part 
 of experimental philosophy. Besides, when 
 a person himself observes, and operates, he 
 must perceive, even in the most common 
 operations, a great variety of small facts, 
 which must necessarily be known, but which 
 are not mentioned either in books or in me- 
 moirs, because they are too numerous, and 
 would appear too minute. Lastly, there are 
 many qualities in the several agents, of 
 which no just notion can be given by writ- 
 ing, and which are perfectly well known as 
 soon as they have been once made to strike 
 our senses. 
 
 Many people think, that a laboratory level 
 with the ground is most convenient, for the 
 sake of water, pounding, washing, Sec. It 
 certainly has these advantages ; but it is also 
 subject to very great inconvenience from 
 moisture. 
 
 Constant moisture, though not very con- 
 siderable and sensible in many respects, is a 
 very great inconvenience in a chemical labo- 
 ratory. In such a place, most saline matters 
 become moist in time, and the inscriptions 
 fall off, or are effaced ; the bellows rot ; 
 the metals rust ; the furnaces moulder, and 
 every thing almost spoils. A laboratory, 
 therefore, is more advantageously placed 
 
 above than below the ground, that it may be 
 as dry as possible. The air must have free 
 access to it ; and it must even be so con- 
 structed, that, by means of two or more op- 
 posite openings, a current of air may be ad- 
 mitted, to carry off' any noxious vapours or 
 dust. 
 
 In the laboratory a chimney ought to be 
 constructed, so high that a person may easily 
 stand under it, and as extensive as is possible ; 
 that is, from one wall to another. The fun- 
 nel of this chimney ought to be as high as is 
 possible, and sufficiently contracted to make 
 a good draught. As charcoal only is burnt 
 under this chimney, no soot is collected in 
 it ; and therefore it need not be so wide as 
 to allow a chimney-sweeper to pass up into it. 
 
 Under this chimney may be constructed 
 some brick furnaces, particularly a melting 
 furnace, a furnace for distilling with an 
 alembic, and one or two ovens like those in 
 kitchens. The rest of the space ought to be 
 filled up with stands of different heights, 
 from a foot to a foot and a half, on which 
 portable furnaces of all kinds are to be 
 placed. These furnaces are the most con- 
 venient, from the facility of disposing them 
 at pleasure ; and they are the only furnaces 
 which are necessary in a small laboratory. 
 A double pair of bellows of moderate size 
 must also be placed as commodiously under 
 the chimney, or as near as the place will 
 allow. These bellows are sometimes mount*- 
 ed in a portable frame; which is sufficiently 
 convenient when the bellows are not more 
 than eighteen or twenty inches long. These 
 bellows ought to have a pipe directed to- 
 ward the hearth where the forge is to be 
 placed. 
 
 The necessary furnaces are, the simple fur- 
 nace, for distilling with a copper alembic ; a- 
 lamp furnace ; two reverberatory furnaces 
 of different sizes, for distilling with retorts ; 
 an air or melting furnace, an essay furnace, 
 and a forge furnace. 
 
 Under the chimney, at a convenient 
 height, must be a row of hooks driven into 
 the back and side walls; upon which are to 
 
LAB 
 
 LAB 
 
 be hung small shovels ; iron pans ; tongs ; 
 straight, crooked, and circular pincers ; 
 pokers ; iron rods, and other utensils for dis- 
 posing the fuel and managing the crucibles. 
 
 To the walls of the laboratory ought to 
 be fastened shelves of different breadths and 
 heights ; or these shelves may be suspended 
 by hooks. The shelves are to contain glass 
 vessels, and the products of operations, and 
 ought to be in as great a number as is pos- 
 sible. In a laboratory where many experi- 
 ments are made, there cannot be too many 
 shelves. 
 
 The most convenient place for a stone or 
 leaden cistern, to contain water, is a corner 
 of the laboratory, and under it a sink ought 
 to be placed with a pipe, by which the 
 water poured into it may discharge itself. 
 As the vessels are always cleaned under this 
 cistern, cloths and bottle brushes ought to 
 be hung upon hooks fastened in the walls 
 near it. 
 
 In the middle of the laboratory a large 
 table is to be placed, on which mixtures are 
 to be made, preparations for operations, so- 
 lutions, precipitations, small filtrations ; in a 
 word, whatever does not require fire, except- 
 ing that of a lamp. 
 
 In convenient parts of the laboratory are 
 to be placed blocks of wood upon mats ; one 
 of which is to support a middle-sized iron 
 mortar ; another to support a middle-sized 
 marble, or rather hard stone mortar ; a third 
 to support an anvil. Near the mortars are 
 to be hung searces of different sizes and fine- 
 ness ; and near the anvil a hammer, files, 
 rasps, small pincers, scissars, sheers, and 
 other small utensils, necessary to give me- 
 tals a form proper for the several operations. 
 
 Two moveable trestles ought to be in a la- 
 boratory, which may serve to support a large 
 filter mounted upon a frame, when it is re- 
 quired. This apparatus is removed occa- 
 sionally to the most convenient place. 
 
 Charcoal is an important article in a la- 
 boratory, and it therefore must be placed 
 within reach ; but as the black dust which 
 flies about it whenever it is stirred, is apt to 
 soil every thing in the laboratory, it had bet- 
 ter be in some place near the laboratory, to- 
 gether with some furze, which is very con- 
 venient for kindling fires quickly. This 
 place serves, at the same time, for contain- 
 ing bulky things, which are not often want- 
 ed ; such as furnaces, bricks, tiles, clay, fire- 
 clay, quicklime, sand, and many other things 
 necessary for chemical operations. 
 
 Lastly, a middle-sized table, with solid 
 feet, ought to be enumerated among the 
 large moveables of a laboratory, the use of 
 which is to support a porphyry, or levigating 
 stone, or rather a very hard and dense grit- 
 stone, together with a muller made of the 
 same kind of stone. 
 
 Ihe other small moveables or utensils of 
 
 2 
 
 a laboratory are, small hand mortars of iron, 
 glass, agate, and Wedgwood’s w r are, and 
 their pestles ; earthen, stone, metal, and 
 glass vessels, of different kinds, funnels, and 
 measures. 
 
 Some white writing paper, and some un- 
 sized paper for filters ; a large number of 
 clean straws, eight or ten inches long, for 
 stirring mixtures in glasses, and for support- 
 ing paper filters placed in glass funnels. 
 
 Glass tubes for stirring and mixing corro- 
 sive liquors ; spatulas of wood, ivory, metal, 
 and glass. 
 
 Thin pasteboards, and horns, very conve- 
 nient for collecting matters bruised with wa- 
 ter upon the levigating stone, or in mortars ; 
 corks of all sizes ; bladders and linen strips 
 for luting vessels. 
 
 A good portable pair of bellows ; a good 
 steel for striking fire ; a glue-pot, with its 
 little brush ; lastly, a great many boxes, of 
 various sizes, for containing most of the 
 above-mentioned things, and which are to be 
 placed upon the shelves. 
 
 Beside these things, some substances are 
 so necessary in most chemical operations, 
 that they may be considered as instruments 
 requisite for the practice of this science. 
 These substances are called reagents, which 
 see under Ores (Analysis or), and Waters 
 (Mineral). 
 
 All metals, which ought to be very pure. 
 
 A person provided with such instruments 
 and substances, may at once perform many 
 chemical experiments. 
 
 The general observations of Macquer up- 
 on the conducting of chemical processes, are 
 truly valuable and judicious. Method, order, 
 and cleanliness, are essentially necessary in a 
 chemical laboratory. Every vessel and uten- 
 sil ought to be w r ell cleansed as often as it is 
 used, and put again into its place : labels 
 ought to be put upon all the substances. These 
 cares, which seem to be trifling, are however 
 very fatiguing and tedious ; but they are also 
 very important, though frequently little ob- 
 served. When a person is keenly engaged, 
 experiments succeed each other quickly ; 
 some seem nearly to decide the matter, and 
 others suggest new ideas : he cannot but 
 proceed to them immediately, and he is led 
 from one to another : he thinks he shall 
 easily know again the products of the first 
 experiments, and therefore he does not take 
 time to put them in order: he prosecutes 
 with eagerness the experiments which he has 
 last thought of ; and in the mean time, the 
 vessels employed, the glasses and bottles fill- 
 ed, so accumulate, that lie cannot any longer 
 distinguish them ; or at least, he is uncer- 
 tain concerning many of his former pro- 
 ducts. This evil is increased, if a new scries 
 of operations succeed, and occupy all the 
 laboratory ; or if he be obliged to quit it for 
 some time, every thing then goes into con- 
 
LAB 
 
 LAB 
 
 fusion. Thence it frequently happens, that 
 he loses the fruits of much labour, and that 
 lie must throw away almost all the products 
 of his experiments. 
 
 When new researches and inquiries are 
 made, the mixtures, results, and products of 
 all the operations ought to be kept a long 
 time, distinctly labelled and registered ; for 
 these things, when kept some time, frequent- 
 ly present phenomena, that were not at all 
 suspected. Many fine discoveries in che- 
 mistry have been made in this manner ; and 
 many have certainly been lost by throwing 
 away too hastily, or neglecting the products. 
 
 Since chemistry offers many views for the 
 improvement of many important arts ; as it 
 presents prospects of many useful and pro- 
 fitable discoveries ; those who apply their 
 labours in this way ought to be exceedingly 
 circumspect, not to be led into a useless ex- 
 pense of money and time. In a certain set 
 of experiments, some one is generally of an 
 imposing appearance, although in reality it is 
 nothing more. Chemistry is full of these 
 half successes, which serve only to deceive 
 the unwary, to multiply the number of trials, 
 and to lead to great expense before the fruit- 
 lessness of the search is discovered. By these 
 reflections we do not intend to divert from 
 all such researches, those whose taste and 
 talents render them fit for them ; on the con- 
 trary, we acknowledge, that the improvement 
 of the arts, and the discovery of new objects 
 of manufacture and commerce, are undoubt- 
 edly the finest and most interesting part of 
 chemistry, and which make that science truly 
 valuable ; for without these ends, what would 
 chemistry be but a science purely theoretical, 
 and capable of employing only some abstract 
 and speculative minds, but useless to society? 
 We acknowledge also, that the successes in 
 this kind of chemical inquiry are not rare ; 
 and that their authors have sometimes ac- 
 quired fortunes, so much the more honour- 
 able, as being the fruits of their talents and 
 industry. But we repeat, that, in these re- 
 searches, the more dazzling and near any 
 success appears, the more circumspection, 
 and even distrust is necessary. See Ana- 
 lysis, Attraction, Balance. 
 
 The plates annexed, with the following 
 explanations of them, will give the student 
 an idea of a large variety of the most useful 
 and necessary articles of a chemical appa- 
 ratus. 
 
 Plate II. fig. 1. Crucibles or pots, made 
 either of earth, black lead, forged iron, or 
 platina. They are used for roasting, calci- 
 nation, and fusion. 
 
 Fig. 2. Cucurbits, matrasses, or bodies, 
 which are glass, earthen, or metallic vessels, 
 usually of the shape of an egg, and open at 
 top. They serve the purposes ot digestion, 
 ewaporation, &c. 
 
 Pig. 3. Retorts are globular vessels of 
 
 earthen ware, glass, or metal, with a neck 
 bended on one side. Some retorts have an- 
 other neck or opening at their upper part, 
 through which they may bo charged, and 
 the opening may be afterwards closed with 
 a stopple. These are called tubulated re- 
 torts. A Welter’s tube of safety may be in- 
 serted in this opening, instead of a stopple. 
 See Plate VII. fig. J. b and e. 
 
 lleceivors are vessels, usually of glass, of 
 a spherical form, with a straight neck, into 
 which the neck of the retort is usually in- 
 serted. When any proper substance is put 
 into a retort, and heated, its volatile parts 
 pass over into the receiver, where they are 
 condensed. Sec fig 5. and Plate V. fig. 2. k. 
 
 Fig. 4. The alembic is used for distilla- 
 tion, when the products are too volatile to 
 admit of the use of the last mentioned appa- 
 ratus. The alembic consists of a body a, to 
 which is adapted a head b. The head is of 
 a conical figure, and has its external circum- 
 ference or base depressed lower than its neck, 
 so that the vapours which rise, and are con- 
 densed against its sides, run down into the 
 circular channel formed by its depressed 
 part, from whence they are conveyed by the 
 nose or beak c, into the receiver d. This 
 instrument is less simple than the retort, 
 which certainly may be used for the most 
 volatile products, if care be taken to apply a 
 gentle heat on such occasions. But the 
 alembic has its conveniences. In particu- 
 lar the residues of distillations may be easily 
 cleared out of the body a ; and in experi- 
 ments of sublimation, the head is very con- 
 venient to receive the dry products, while the 
 more volatile and elastic parts pass over into 
 the receiver. 
 
 Fig. 6. Represents the large stills used in 
 the distillation of ardent spirits. a repre- 
 sents the body, and b the head, as before. 
 Instead of using a refrigeratory or receiver, 
 the spirit is made to pass through a spiral 
 pipe called the worm, which is immersed in 
 a tub of cold water d. During its passage 
 it is condensed, and comes out at the lower 
 extremity, e, of the pipe, in a fluid form. 
 
 The manner in which the excise laws for 
 Scotland were framed, rendering it advan- 
 tageous to the distillers in that country to 
 
 O # " 
 
 have stills of small capacity, which they 
 could work very quickly, their ingenuity 
 was excited to contrive the means of effect- 
 ing this. It was obvious, that a shallow still, 
 with a broad bottom completely exposed to 
 a strong heat, would best answer the pur- 
 pose : and this was brought to such perfec- 
 tion, that a still of the capacity ot 40 gallons 
 in the body, and three in the head, charged 
 with 16 gallons of wash, could be worked 
 480 times in 24 hours. Fig. 7. is a vertical 
 section of this still, a , the bottom, joined 
 to b, the shoulder, with solder, or rivets, or 
 screws and lute, c, the turned- up edge ot 
 
LAB 
 
 LAB 
 
 the bottom, against which, and on a level 
 with a , the brick- work of the coping of the 
 flue rests, preventing the flame from getting 
 up to touch c. d , the discharge pipe, e e, 
 the body of the still. /, section of the central 
 steam escape pipe, g, section of one of the 
 lateral steam escape pipes ; h , outside view 
 of another, i i i i, inferior apertures of la- 
 teral steam pipes ; k k k k, their superior aper- 
 tures. 1 1 , bottom scraper, or agitator, which 
 may either be made to apply close to the 
 bottom, or to drag chains ; m, the upright 
 shaft of this engine, as it is called ; n the 
 horizontal wheel with its supporters, o, its 
 vertical wheel. p, its handle and shaft ; 
 n, support of the shaft, r, froth and ebulli- 
 tion jet-breaker, resting on the cross bar s. 
 tf, its upright shaft, u, its cup-mouthed col- 
 lar, filled w r ith wool and grease, and held 
 down by a plate and screws. v> general 
 steam escape pipe, or head. The charge pipe, 
 and the sight hole, for the man who charges 
 it to see when it is sufficiently full, are not 
 seen in this view. 
 
 The best construction of a furnace has 
 not been well ascertained from experience. 
 There are facts which shew, that a fire made 
 on a grate near the bottom of a chimney, of 
 equal width throughout, and open both above 
 and below, will produce a more intense heat 
 than any other furnace. What may be the 
 limits for the height of the chimney is not 
 ascertained from any precise trials ; but 
 thirty times its diameter would not probably 
 be too high. It seems to be an advantage 
 to contract the diameter of a chimney, so 
 as to make it smaller than that of the fire- 
 place, when no other air is to go up the 
 chimney than what has passed through the 
 fire ; and there is no prospect of advantage 
 to be derived from widening it. 
 
 Plate V. fig. <3. exhibits the wind or air 
 furnace for melting, a is the ash-hole,/ an 
 opening for the air. c is the fire-place, con- 
 taining a covered crucible, standing on a sup- 
 port of baked earth, which rests on the grate. 
 d is the passage into c, the chimney. At d 
 a shallow crucible or cupel may be placed in 
 the current of the flame, and at x is an 
 earthen or stone cover, to be occasionally 
 taken off for the purpose of supplying the 
 fire with fuel. 
 
 Fig. 2 is a reverberatory furnace, a a the 
 ash-pit and fire-place, bb body of the fur- 
 nace. c c. dome, or reverberating roof of the 
 furnace, dd chimney, ee door of the ash- 
 pit* //door of the fire-place, gg handles 
 of the body. 1\ aperture to admit the head of 
 the retort, i i handles of the dome, k re- 
 ceiver. 1 1 stand of the receiver, m m retort, 
 represented in the body by dotted lines. 
 
 Another reverberatory furnace, a little 
 differing in figure, may be seen in Plate 1. 
 fig. 2. 
 
 M. Chcnevix lias constructed a wind fur- 
 
 nace, which is in some respects to be pre- 
 ferred to the usual form. The sides, instead 
 of being perpendicular, are inverted, so that 
 the hollow space is pyramidical. At the bot- 
 tom the opening is 13 inches square, and 
 at the top but eight. The perpendicular 
 height is 17 inches. This form appears to 
 unite the following advantages: — 1st, A 
 great surface is exposed to the air, which, 
 having an easy entrance, rushes through the 
 fuel with great rapidity; 2d, The inclined 
 sides act in some measure as reverberating 
 surfaces ; and 3d, The fuel falls of itself, 
 and is always in close contact with the cru- 
 cible placed near the grate. The late Dr 
 Kennedy of Edinburgh, whose opinion on 
 this subject claims the greatest weight, found 
 that the strongest heat in our common wind 
 furnaces was within two or three inches of 
 the grate. This, therefore, is the most ad- 
 vantageous position for the crucible, and still 
 more so when w r e can keep it surrounded 
 with fuel. It is inconvenient, and danger- 
 ous for the crucible, to stir the fire often to 
 make the fuel fall, and the pyramidical form 
 renders this unnecessary. It is also more 
 easy to avoid a sudden bend in the chimney, 
 by the upper part of the furnace advancing 
 as in this construction. In plate V. fig. 1. 
 a is a grate ; c and c are two bricks, which 
 can be let in at pleasure to diminish the ca- 
 pacity ; b is another grate, which can be 
 placed upon the bricks c and c for smaller 
 purposes; d and d are bricks which can be 
 placed upon the grate b to diminish the up- 
 per capacity, so that, in fact, there are four 
 different sizes in the same furnace. The 
 bricks should all be ground down to the 
 slope of the furnace, and fit in with tolerable 
 accuracy. They are totally independent of 
 the pyramidical form of the furnace. 
 
 Mr Aikin’s portable blast furnace is com- 
 posed of three parts, all made out of the 
 common thin black lead melting pots, sold 
 in London for the use of the goldsmiths. 
 The lower piece c, fig. 6. is the bottom of 
 one of these pots, cut off so low as only to 
 leave a cavity of about an inch deep, and 
 ground smooth above and below. The out- 
 side diameter, over the top, is five inches 
 and a half. The middle piece or fire-place 
 a, is a larger portion of a similar pot, with a 
 cavity about six inches deep, and measuring 
 seven inches and a half over the top, outside 
 diameter, and perforated with six blast holes 
 at the bottom. These two pots are all that 
 are essentially necessary to the furnace for 
 most operations; but when it is wished to 
 heap up fuel jibove the top of a crucible 
 contained, and especially to protect the eyes 
 from the intolerable glare of the fire when in 
 full height, an upper pot b is added, of the 
 same dimensions as the middle one, and with 
 a large opening in the side, cut to allow the 
 exit of the smoke and flame. It has also 
 
LAB 
 
 LAB 
 
 an iron stem, with a wooden handle (an old 
 chisel answers the purpose very well) for re- 
 moving it occasionally. The bellows, which 
 are double (d), are firmly fixed, by a little 
 contrivance which will take off and on, to a 
 heavy stool, as represented in the plate; and 
 their handle should be lengthened so as to 
 make them work easier to the hand. To 
 increase their force, on particular occasions, 
 a plate of lead may be firmly tied on the 
 wood of the upper ilap. The nozzle is re- 
 ceived into a hole in the pot c, which con- 
 ducts the blast into its cavity. Hence the 
 air passes into the fire-place «, through six 
 holes of the size of a large gimlet, drilled at 
 equal distances through the bottom of the 
 pot, and all converging in an inward direc- 
 tion, so that, if prolonged, they would meet 
 about the centre of the upper part of the 
 fire. No luting is necessary in using this 
 furnace, so that it may be set up and taken 
 down immediately. Coak, or common cin- 
 ders, taken from the fire when the coal ceases 
 to blaze, sifted from the dust, and broken 
 into very small pieces, forms the best fuel 
 for higher heats. The fire may be kindled 
 at first by a few lighted cinders, and a small 
 quantity of wood charcoal. The heat which 
 this little furnace will afford is so intense, 
 that its power was at first discovered acci- 
 dentally by the fusion of a thick piece of cast 
 iron. The utmost heat procured by it was 
 167° of Wedgwood’s pyrometer, when a 
 Hessian crucible was actually sinking down 
 in a state of porcelaneous fusion. A steady 
 heat of 15S°or 160° may be depended on, 
 if the fire be properly managed, and the bel- 
 lows worked with vigour. 
 
 The process of cupellation may be exhi- 
 bited in a lecture, or performed at other 
 times, by means of this furnace. The me- 
 thod consists in causing a portion of the blast 
 to be diverted from the fuel, and to pass 
 through a crucible in which the cupel is 
 placed. This arrangement supplies air; 
 and the whole may be seen by a sloping 
 tube, run through the cover of the crucible. 
 
 Charcoal is the material most commonly 
 used in furnaces. It produces an intense 
 heat without smoke, but it is consumed very 
 fast. Coak or charred pit-coal produces a 
 very strong and lasting heat. Neither of 
 these produces a strong heat at a distance 
 from the fire. Where the action of flame is 
 required, wood or coal must he burned. 
 Several inconveniences attend the use of 
 coal, as its fuliginous fumes, and its aptitude 
 to stop the passage of air by becoming fused. 
 It is used, however, in the reverberatory fur- 
 naces of glass-houses, and is the best ma- 
 terial where vessels are to be supplied with a 
 great quantity of heat at no great intensity, 
 such as in distilleries, &c. 
 
 Frequently, however, the flame of an Ar- 
 gand lamp may be employed very conve- 
 
 niently for chemical purposes. PI. VI. fig. 2. 
 is a representation of a lamp furnace, as it 
 is perhaps not very properly called, as im- 
 proved by Mr Accum. it consists of a brass 
 rod screwed to a foot of the same metal, 
 loaded with lead. On this rod, which may 
 be unscrewed in the middle for rendering 
 it more portable, slide three brass sockets 
 with straight arms, terminating in brass 
 rings of different diameters. The largest 
 measures four inches and a half. These 
 rings serve for supporting glass alembics, 
 retorts, Florence flasks, evaporating basins, 
 gas bottles, Sec . ; for performing distillations, 
 digestions, solutions, evaporations, saline 
 fusions, concentrations, analyses with the 
 pneumatic apparatus, Sc c. if the vessels 
 
 require not to he exposed to the naked fire, 
 a copper sand-bath maybe interposed, which 
 is to be previously placed in the ring. By 
 means of a thumb-screw acting on the rod 
 of the lamp, each of the brass rings may be 
 set at different heights, or turned aside, ac- 
 cording to the pleasure of the operator. Be- 
 low these rings is a fountain-lamp on Ar- 
 gand’s plan, having a metallic valve within, 
 to prevent the oil from running out while 
 the reservoir is put into its place. This 
 lamp also slides on the main brass rod by 
 means of a socket and thumb- screw. It is 
 therefore easy to bring it nearer, or to move 
 it further, at pleasure, from the vessel, which 
 may remain fixed ; a circumstance which, 
 independent of the elevation and depression 
 of the wicks of the lamp, affords the advan- 
 tage of heating the vessels by degrees after 
 they are duly placed, as well as of augmenting 
 or diminishing the heat instantly ; or for 
 maintaining it for several hours at a certain 
 degree, without in the least disturbing the 
 apparatus suspended over it. It may there- 
 fore be used for producing the very gentle 
 heat necessary for the rectification of ethers, 
 or the strong heat requisite for distilling 
 mercury. Hie chief improvement of this 
 lamp consists in its power of affording an 
 intense heat by the addition of a second cy- 
 linder, added to that of the common lamp of 
 Argand. This additional cylinder encloses 
 a wick of one inch and a half in diameter, 
 and it is by this ingenious contrivance, which 
 •was first suggested by Mr Webster, that a 
 double flame is caused, and more than three 
 times the heat of an Argand’s lamp of the 
 largest size is produced. 
 
 Every effect of the most violent heat or 
 furnaces may be produced by the flame of a 
 candle or lamp, urged upon a small particle 
 of any substance, by the blow-pipe. 1 his 
 instrument is sold by the ironmongers, and 
 consists merely of a brass pipe about one- 
 eighth of an inch diameter at one end, ana 
 the other tapering to a much less size, with 
 a very small perforation for the wind to 
 escape. The smaller end is bended on one 
 
LAB 
 
 LAB 
 
 side. For philosophical or other nice pur- 
 poses the blow-pipe is provided with a bowl 
 or enlargement, a (PI. V. fig. 5.), in which 
 the vapours of the breath are condensed 
 and detained, and also with three or four 
 small nozzles, b> with different apertures, to 
 be slipped on the smaller extremity. These 
 are of use when larger or smaller flames are 
 
 O 
 
 to be occasionally used, because a larger 
 flame requires a large aperture, in order 
 that the air may effectually urge it upon the 
 matter under examination. 
 
 There is an artifice in the blowing through 
 this pipe, which is more difficult to describe 
 than to acquire. The effect intended to be 
 produced is a continual stream of air for 
 many minutes, if necessary, without ceasing. 
 This is done by applying the tongue to the 
 roof of the mouth, so as to interrupt the 
 communication between the mouth and the 
 passage of the nostrils ; by which means the 
 operator is at liberty to breathe through 
 the nostrils, at the same time that by the 
 muscles of the lips he forces a continual 
 stream of air from the anterior part of the 
 mouth through the blow-pipe. When the 
 mouth begins to be empty, it is replenished 
 by the lungs in an instant, while the tongue 
 is withdrawn from the roof of the mouth, 
 and replaced again in the same manner as in 
 pronouncing the monosyllable tut . In this 
 way the stream may be continued for a long 
 time without any fatigue, if the flame be not 
 urged too impetuously, and even in this case 
 no other fatigue is felt than that of the mus- 
 cles of the lips. 
 
 A wax candle, of a moderate size, but 
 thicker wick than they are usually made 
 with, is the most convenient for occasional 
 experiments ; but a tallow candle will do 
 very well. The candle should be snuffed 
 rather short, and the wick turned on one 
 side toward the object, so that a part of it 
 should lie horizontally. The stream of air 
 must be blown along this horizontal part, as 
 near as may be without striking the wick. 
 If the flame be ragged and irregular, it is a 
 proof, that the hole is not round or smooth • 
 and it the flame have a cavity through it, the 
 aperture of the pipe is too large. When the 
 hole is of a proper figure and duly propor- 
 tioned, the flame consists of a neat luminous 
 blue cone, surrounded by another flame of 
 a more faint and indistinct appearance. The 
 st longest heat is at the point of the inner 
 flame. 
 
 The body intended to be acted on by the 
 blow-pipe ought not to exceed the size of a 
 peppercorn. It may be laid upon a piece 
 of' close-grained, well- burned charcoal ; un- 
 less it be of such a nature as to sink into the 
 pores of this substance, or to have its pro- 
 perties affected by its inflammable quality. 
 .Such bodies may be placed in a small spoon 
 inadc of pure gold or silver, or platina. 
 
 Many advantages may be derived from 
 the use of this simple and valuable instru- 
 ment. Its smallness, which renders it suit- 
 able to the pocket, is no inconsiderable re- 
 commendation. The most expensive ma- 
 terials, and the minutest specimens of bo- 
 dies, may be used in these experiments ; 
 and the whole process, instead of being car- 
 ried on in an opaque vessel, is under the eye 
 of the observer from beginning to end. It 
 is true, that very little can be determined in 
 this way concerning the quantities of pro- 
 ducts ; but, in most cases, a knowledge of 
 the contents of any substance is a great ac- 
 quisition, which is thus obtained in a very 
 short time, and will at all events serve to 
 show the best and least expensive way of 
 conducting processes with the same matters 
 in the larger way. 
 
 The blow-pipe has deservedly of late years 
 been considered as an essential instrument 
 in a chemical laboratory, and several at- 
 tempts have been made to facilitate its use 
 
 bv the addition of bellows, or some other 
 * 
 
 equivalent instruments. These are doubt- 
 less very convenient, though they render it 
 less portable for mineralogical researches* 
 It will not, here, be necessary to enter into 
 any description of a pair of double bellows 
 fixed under a table, and communicating 
 with a blow-pipe which passes through the 
 table. Smaller bellows, of a portable size 
 for the pocket, have been made for the same 
 purpose. The ingenious chemist will find 
 no great difficulty in adapting a bladder to 
 the blow-pipe, which, under the pressure 
 of a board, may produce a constant stream 
 of air, and may be replenished, as it becomes 
 empty, by blowing into it with bellows, or 
 the mouth, at another aperture furnished 
 with a valve opening inwards. 
 
 The chief advantage these contrivances 
 have over the common blow- pipe is, that 
 they may be filled with oxygen gas, which 
 increases the activity of combustion to an 
 astonishing degree. The vapour from al- 
 cohol has likewise been employed, and an 
 ingenious contrivance for this purpose by 
 Mr Hooke is represented, PI. V. fig. 4. a is 
 a hollow sphere for containing alcohol, rest- 
 ing upon a shoulder in the ring o. If the 
 bottom be made flat instead of spherical, 
 the action of the flame will then be greater. 
 
 ^ is a bent tube with a jet at the end, to 
 convey the alcohol in the state of vapour 
 into the flame at q ; this tube is continued in 
 the inside up to c, which admits of a bcinn- 
 filled nearly, without any alcohol running 
 over, d is a safety valve, the pressure of 
 which is determined at pleasure, by screw- 
 ing higher or lower on the pillar c, the two 
 milled nuts f and g carrying the steel arm 
 //, which rests on the valve, i is an opening 
 for putting in the alcohol, k is the lamp’ 
 which adjusts to different distances from it. 
 
LAB 
 
 LAB 
 
 by sliding up or down the two pillars l l. 
 I he distance of the dame q from the jet is 
 regulated by the pipe which holds the wick 
 being a little removed from the centre of the 
 brass piece m, and of course revolving in a 
 circle, n the mahogany stand. 
 
 lor the various habitudes of bodies when 
 examined by the blow-pipe, see Blow- pipe. 
 
 Little need be said concerning the man- 
 ner of making experiments with duid bodies 
 in the common temperature of the atmos- 
 phere. Basins, cups, phials, matrasses, and 
 other similar vessels, form the whole appa- 
 ratus required for the purpose of containing 
 the matters intended to be put together ; 
 and no other precaution or instruction is re- 
 quired, than to use a vessel of such materials 
 as shall not be corroded or acted upon by its 
 contents, and of sufficient capacity to admit 
 of any sudden expansion or frothing of the 
 duid, if expected. This vessel must be placed 
 in a current of air, if noxious fumes arise, in 
 order that these may be blown from the ope- 
 rator. 
 
 The method of making experiments with 
 permanently elastic duids, or gases, though 
 simple, is not so obvious. W e live im- 
 
 mersed in an atmosphere not greatly differ- 
 ing in density from these duids, which for 
 this reason are not sufficiently ponderous to 
 be detained in open vessels by their weight. 
 Their remarkable levity, however, affords a 
 method of confining them by means of other 
 denser duids. Dr Priestley, whose labours 
 so far exceeded those of his predecessors 
 and contemporaries, both in extent and 
 importance, that he may with justice be 
 styled the father of this important branch of 
 natural philosophy, used the following appa- 
 ratus. 
 
 PI. V I. fig. 1 . a represents a wooden ves- 
 sel or tub ; k, k, k, is a shelf dxed in the tub. 
 When this apparatus is used, the tub is to 
 be filled with w r ater to such a height, as to 
 rise about one inch above the upper surface 
 of the shelf, b, g, f, are glass jars inverted 
 with their mouths downward, which rest 
 upon the shelf. If these, or any other ves- 
 sels open only at one end, be plunged under 
 the water, and inverted after they are filled, 
 they will remain full, notwithstanding their 
 being raised out of the w ater, provided their 
 mouths be kept immersed ; for in this case, 
 the water is sustained by the pressure of the 
 atmosphere, in the same manner as the mer- 
 cury in the barometer. It may without 
 difficulty be imagined, that it common air, 
 or any other fluid resembling common air 
 in lightness and elasticity, be suffered to en- 
 ter these vessels, it will rise to the upper 
 part, and the surface of the water will sub- 
 side. If a bottle, a cup, or any other vessel, 
 in that slate which is usually called empty, 
 though really full of air, be plunged into the 
 water with its mouth downwards, scarce 
 
 any water w ill enter, because its entrance is 
 opposed by the elasticity of the included 
 air ; but if the vessel be turned up, it im- 
 mediately fills, and the air rises in one or 
 more bubbles to the surface. Suppose this 
 operation to be performed under one of the 
 jars which are filled with water, the air will 
 ascend as before; but instead of escaping, it 
 will be detained in the upper part of the 
 jar. In this manner, therefore, we see, that 
 air may be emptied out of one vessel into 
 another by an inverted pouring, in which the 
 air is made to ascend from the low r er vessel i 
 to the upper g } in which the experiments are 
 performed, by the action of the weightier 
 fluid, exactly similar to the common pouring 
 of denser fluids, detained in the bottoms of 
 open vessels, by the simple action of gravity. 
 When the receiving vessel has a narrow neck, 
 the air may be poured through a glass fun- 
 nel h. 
 
 c ( Ibid.) is a glass body or bottle, the bot- 
 tom of which is blown very thin, that it may 
 support the heat of a candle suddenly applied, 
 without cracking. In its neck is fitted, by 
 grinding, a tube d, curved neatly in the form 
 of the letter s. This kind of vessel is very 
 useful in various chemical operations, for 
 which it will be convenient to have them of 
 several sizes. In the figure, the body c is 
 represented as containing a fluid, in the act 
 of combining with a substance that gives out 
 air, which passes through the tube into the 
 jar b, under the mouth of which the other 
 extremity of the tube is placed. At e is a 
 small retort of glass or earthenware, the 
 neck of which being plunged in the water, 
 beneath the jar is supposed to emit the 
 elastic fluid, extricated from the contents of 
 the retort, which is received in the jar. 
 
 When any thing, as a gallipot, is to be 
 supported at a considerable height within a 
 jar, it is convenient to have such wire stands 
 as are represented fig. 3. These answer 
 better than any other, because they take up 
 but little room, and are easily bent to any 
 figure or height. 
 
 In order to expel air from solid substances 
 by means of heat, a gun-barrel, with the 
 touch-hole screwed up and rivetted, may be 
 used instead of an iron retort. The subject 
 may be placed in the chamber of the barrel, 
 and the rest of the bore may be filled with 
 dry sand, that has been well burned, to expel 
 whatever air it might have contained. The 
 stem of a tobacco-pipe, or a small glass tube, 
 being luted in the orifice of the barrel, the 
 other extremity must be put into the fire, 
 that the heat may expel the air from its con- 
 tents. This air will of course pass through 
 the tube, and may be received under an in- 
 verted vessel, in the usual manner. 
 
 But the most accurate method of procur- 
 ing air from several substances by means of 
 heat, is to put them, if they w ill bear it, into 
 
LAB 
 
 LAB 
 
 phials full of quicksilver, with the mouths 
 inverted in the same, and then throw' the 
 focus of a burning lens or mirror upon them. 
 For this purpose, their bottoms should be 
 round and very thin, that they may not be 
 liable to fly with the sudden application of 
 heat. The body c, PI. VI. fig. 1. answers 
 this purpose very well. 
 
 Many kinds of air combine with water, 
 and therefore require to be treated in an ap- 
 paratus, in which quicksilver is made use ot. 
 This fluid being very ponderous, and of con- 
 siderable price, it is an object of convenience, 
 as well as economy, that the trough and ves- 
 sels should be smaller than when water is 
 used. See PI. VII. fig. 1 
 
 When trial is to be made of any kind of 
 air, whether it be fit for maintaining com- 
 bustion, the air may be put into a long nar- 
 row glass vessel, the mouth of which, being 
 carefully covered, may be turned upward. A 
 bit of wax candle being then fastened to the 
 end of a wire, which is bent so that the flame 
 of the candle may be uppermost, is to be let 
 down into the vessel, which must be kept 
 covered till the instant of plunging the light- 
 ed candle into the air. 
 
 Where the change of dimensions, which 
 follows from the mixture of several kinds of 
 air, is to be ascertained, a graduated narrow 
 cylindrical vessel may be made use of. The 
 graduations may be made by pouring in 
 successive equal measures of water into this 
 vessel, and marking its surface at each ad- 
 dition. The measure may be afterward 
 used for the different kinds of air, and the 
 change of dimensions will be shown by the 
 rise or fall of the mercury or water in the 
 graduated vessel. The purity of common 
 air being determinable by the diminution 
 produced by the addition of nitric oxide 
 gas, these tubes have been called eudiometer 
 tubes. 
 
 Some substances, more especially powders, 
 cannot conveniently be put into a phial, or 
 passed through a fluid. When air is to be 
 extricated from, or added to these, there is 
 no better method, than to place them on a 
 stand under the receiver of the air-pump, 
 and exhaust the common air, instead of ex- 
 cluding it by water or mercury. This pro- 
 cess requires a good air-pump, and careful 
 management, otherwise the common air will 
 not be well excluded. 
 
 It is frequently an interesting object, to 
 pass the electric spark through different 
 kinds of air, either alone or mixed together. 
 
 _ # O 
 
 In tins case a metallic wire may be fastened 
 in the upper end of a tube, and the sparks 
 or shock may be passed through this wire 
 to the mercury or water used to confine the 
 air. If there be reason to apprehend, that 
 an expansion in the air may remove the 
 mercury or water beyond the striking dis- 
 tance, another wire may be thrust up to re- 
 ceive the electricity, or two wires may be 
 
 cemented into opposite holes in the sides of 
 an hermetically sealed tube. Holes may be 
 made in glass, for this and other chemical 
 uses, by a drill of copper or soft iron, with 
 emery and w r ater; and where this instru- 
 ment is wanting, a small round file with 
 water will cut a notch in small vessels, such 
 as phials or tubes, though with some dan- 
 ger of breaking them. In some electrical 
 experiments of the kind here mentioned,, 
 there is reason to expect a fallacious result 
 from the wires being burned by the explo- 
 sion or spark. For this reason, the electri- 
 city may be made to pass through the legs of 
 a syphon, containing the air which is under 
 consideration in the upper part of its cur- 
 vature. One of the vessels, in which the 
 legs of the syphon rest, must therefore be 
 insulated ; and if any watery fluid be used 
 to confine the air, it is generally supposed 
 that no combustion takes place. 
 
 It is sometimes desirable to impregnate 
 water for medicinal purposes with some gas, 
 as the carbonic acid, and for this the appa- 
 ratus of Dr Nootli is very effectual and con- 
 venient. It consists of three glass vessels, 
 PI. VI. fig. 4 . The low^er vessel c contains 
 the effervescent materials ; it has a small ori- 
 fice at d, stopped with a ground stopper, at 
 which an additional supply of either acid or 
 w'ater, or chalk, may be occasionally intro- 
 duced. The middle vessel b is open, both 
 above and below. Its inferior neck is fitted 
 by grinding into the neck h of the lower 
 vessel. In the former is a glass valve, form- 
 ed by two pieces of tube, and a plano-con- 
 vex lens, which is moveable, betw een them, 
 as represented in fig. 5. This valve opens 
 upwards, and suffers the air to pass ; but 
 the water cannot return through the tubes, 
 partly because the orifice is capillary, and 
 partly because the fiat side of the lens covers 
 the hole. The middle vessel is furnished 
 with a cock e, to draw off’ its contents. 
 The upper vessel a is fitted, by grinding, 
 into the upper neck of the middle vessel. 
 Its inferior part consists of a tube that passes 
 almost as low as the centre of the middle 
 vessel. Its upper orifice is closed by a 
 ground stopperyi When this apparatus is 
 to be used, the effervescent materials are put 
 into the low’er vessel, the middle vessel is 
 filled with pure water, and put into its 
 place ; and the upper vessel is stopped, and 
 likewise put in its place. The consequence is, 
 that the carbonic acid gas, passing through 
 the valve at h , ascends into the upper part 
 of the middle vessel b, where, by its elasti- 
 city, it reacts on the water, and forces part 
 up the tube into the vessel « ; part of the 
 common air, in this last, being compressed, 
 and the rest escaping by the stopper, which 
 is made of a conical figure, that it may be 
 easily raised. As more carbonic acid is ex- 
 tricated, more water rises, till at length the 
 water in the middle vessel falls below the 
 
LAB 
 
 LAB 
 
 lower orifice of the tube. The gas then 
 passes through the tube into the upper ves- 
 sel, and expels more of the common air by 
 raising the stopper. In this situation the 
 water in both vessels being in contact with a 
 body of carbonic acid gas, it becomes strong- 
 ly impregnated with this gas, after a certain 
 time. This effect may be hastened by tak- 
 ing off the middle and upper vessels toge- 
 ther, and agitating them. 
 
 The valve is the most defective part of 
 this apparatus ; for the capillary tube does 
 not admit the air through, unless there is a 
 considerable quantity condensed in the lower 
 vessel ; and the condensation has in some in- 
 stances burst the vessel. 
 
 Modern discoveries respecting bodies in 
 the aeriform state have produced several ca- 
 pital improvements in the vessels used for 
 distillation. It was common with the ear- 
 liest chemists, to make a small hole in the 
 upper part of their retorts, that the elastic 
 vapours might escape, which would other- 
 wise have burst the vessels. By this means 
 they lost a very considerable part of their 
 products. Sometimes too it is requisite, to 
 obtain separately the condensable fluid that 
 comes over, and the gases that are and are 
 not soluble in water. For this purpose a se- 
 ries of receivers, more or less in number as 
 the case may require, is generally employ- 
 ed, as in PI. VII. fig. 1. which represents 
 what is called Woolfe’s apparatus, though 
 in fact its original inventor was Glauber, 
 with some subsequent improvements. The 
 vapour that issues from the retort being con- 
 densed in the receiver a, the gas passes on 
 through a bent tube into the bottle c, which 
 is half filled with water. The gas, not ab- 
 sorbed by this water, passes through a simi- 
 lar bent tube to d, and so on to more, if it 
 be thought necessary ; while the gas that is 
 not absorbable by water, or condensable, at 
 its exit from the last bottle is conveyed by 
 a recurved tube into a jar g, standing in a 
 mercurial troughj^ 
 
 It often happens in chemical processes, 
 from the irregularity of the heat, or other 
 circumstances, that the condensation is more 
 rapid in proportion to the supply of vapour 
 at some period of the same operation than 
 in others ; which would endanger the fluid’s 
 being forced backward, by the pressure of 
 the atmosphere, into the receiver, or even into 
 the retort. To prevent this, Mr Woolfe’s 
 bottles had a central neck, beside the two 
 here delineated, for the insertion of a tube of 
 safety, the lower extremity of which opened 
 underneath the water, and the upper com- 
 municated w r ith the atmosphere, so as to sup- 
 ply air in case of sudden absorption. See 
 PI. VII. fig. 3. h . Instead of this, how- 
 ever, a curved Welter’s tube is now general- 
 ly used, as more convenient. Into this tube 
 water is poured, till the ball b, or c, fig. I. is 
 
 half full : when absorption takes place, the 
 water rises in the ball till none remains in 
 the tube, and then the air rushes in : on the 
 other hand, no gas can escape, as it has to 
 overcome the pressure of a high column of 
 water in the perpendicular tube. 
 
 Another contrivance to prevent retrograde 
 pressure is that of Mr Pepys. This consists 
 in placing over the first receiver a glass ves- 
 sel, the neck of which is ground into it, 
 and furnished with a glass valve, similar to 
 that in Nooth’s apparatus, so that whenever 
 sudden condensation takes place in the re- 
 ceiver, its effect is merely to occasion a va- 
 cuum there. 
 
 An ingenious modification of Woolfe’s 
 apparatus is that of Mr Knight, PI. VI. fig. 
 6. a a a represent three vessels, each ground 
 into the mouth of that below it. b b b glass 
 tubes, the middles of which are ground into 
 the neck of their respective vessels, the upper 
 extremity standing above the surface of the 
 liquor in the vessel, and the lower extremity 
 reaching nearly to the bottom of the vessel 
 beneath, e a Welter’s tube to prevent ab- 
 sorption. J' an adapter ground to fit the 
 receiver ; to which any retort may be joined 
 and luted before it is put into its place, c a 
 tube for conveying the gas into a pneumatic 
 trough. The foot of the lowest vessel, d, 
 slides in between two grooves in a square 
 wooden foot, to secure the apparatus from 
 oversetting. A stopple fitted to the upper 
 vessel, instead of the adapter J] converts it 
 into a Nooth’s apparatus, the materials being 
 put into the vessel a, and in this case it has 
 the advantage of not having a valve liable to 
 be out of order. 
 
 A very simple and commodious form of a 
 Woolfe’s apparatus is given by the late Dr 
 W. Hamilton, at the end of his translation of 
 Berthollet on Dyeing; see PI. VII. fig. S. a 
 is the retort, the neck of which is ground into 
 and passed through the thick collar b, re- 
 presented separately at b, with its ground 
 stopple a, which may be put in when the 
 neck of the retort is withdrawn. The col- 
 lar b is ground into the wide neck of the 
 receiver c, the narrow neck of which is 
 ground into the wide neck of d. d , e, J) 
 
 and g, are connected in a similar manner ; 
 and into the small necks of d, e, and are 
 ground the tubes t, k, and /, so curved, that 
 their lower extremities nearly reach the hot- 
 tom of the receiver into which they open. 
 From the last receiver proceeds the recurved 
 tube tn, opening under an inverted cup n, a 
 hole in the bottom of which conveys the gas 
 issuing from it into one of the bottles placed 
 in the moveable frame p, which has a heavy 
 leaden foot to keep it steady in the centre of 
 a flat pan of water, in which the mouths of 
 the bottles are immersed. In the receiver d 
 is a tube of safety h. The receivers arc 
 placed on a stand a little inclined, and kept 
 
LAB 
 
 LAC 
 
 steady by slips of wood hollowed out to fit 
 their curvatures, as represented at s s. This 
 apparatus requires no lute ; has no bent 
 tubes that are difficult to adjust, and liable 
 to break ; and the retort may be removed at 
 any stage of the process, either to find the 
 weight it has lost, or for any other purpose, 
 the receiver being meanwhile closed with 
 the stopple. Similar advantages attend Mr 
 Knight’s. 
 
 When it is required to pass an aeriform 
 fluid through a red-hot substance, such an ap- 
 paratus as that of Barruel, PI. I. fig* 2. may 
 be employed. In this, three gun- barrels, b, 
 c, d, are placed horizontally in a reverbera- 
 tory furnace a, about two inches distance 
 from each other. From the extremity of 
 the central barrel c, a bent tube k conveys 
 the gas to the jar m, in the pneumatic 
 trough 1. The other extremity of c is con- 
 nected with d by the curved tube i; d with 
 b by the curved tube h ; and the other end 
 of 6 with the bottley'by the tube e. When 
 this apparatus is employed for obtaining car- 
 bonic oxide, the part of each barrel exposed 
 to the lire being filled with charcoal pressed 
 lightly in, but not rammed hard ; carbonate 
 of lime diluted with a very little water being 
 poured into the bottle^/; and the junctures 
 being all well luted, the fire is to be kindled. 
 A s soon as the barrels are red-hot, sulphuric 
 acid is to be poured into the funnel g, and 
 the carbonic acid gas expelled, traversing 
 three portions of red-hot charcoal, will com- 
 pletely saturate itself with it before it reaches 
 the receiver m. 
 
 Plate VII. fig. 2. represents the different 
 parte of the apparatus required for measuring 
 the quantity of elastic fluid given out during 
 the action of an acid on calcareous soils. The 
 bottle for containing the soil is represented 
 at a ; b the bottle containing the acid, fur- 
 nished with a stop-cock ; c the tube con- 
 nected with a flaccid bladder d ; f a gradu- 
 ated measure ; e the bottle for containing the 
 bladder. When this instrument is used, a 
 given quantity of soil is introduced into a ; 
 b is filled with muriatic acid, diluted with an 
 equal quantity of water ; and the stop-cock, 
 being closed, is connected with the upper 
 orifice of a, which is ground to receive it. 
 The tube c is introduced into the lower ori- 
 fice of a, and the bladder connected with it 
 placed in its flaccid state in c, which is filled 
 with water. The graduated measure is plac- 
 ed under the tube of e. When the stop- 
 cock of b is turned, the acid flows into a, 
 and acts upon the soil ; the elastic fluid ge- 
 nerated, passes through c into the bladder, 
 and displaces a quantity of water in e equal 
 to it in bulk, and this water flows through 
 the tube into the graduated measure; the 
 water in which gives, by its volume, the in- 
 dication of the proportion of carbonic acid 
 disengaged lroin the soil; for every ounce 
 
 measure of which, two grains of carbonate 
 of lime may be estimated. See Carbonate, 
 Eudiometer, and Vapour. 
 
 Labrador Stone. See Felspar. 
 
 Lac, is a substance well known in Eu- 
 rope, under the different appellations of 
 stick-lac, shell-lac, and seed-lac. The first 
 is the lac in its natural state, encrusting small 
 branches or twigs. Seed-lac is the stick-lac 
 separated from the twigs, appearing in a 
 granulated form, and probably deprived of 
 part of its colouring matter by boiling. 
 Shell-lac is the substance which has under- 
 gone a simple purification, as mentioned be- 
 low. Beside these we sometimes meet with 
 a fourth, called lump-lac, which is the seed- 
 lac melted and formed into cakes. 
 
 Lac is the product of the coccus lacca, 
 which deposits its eggs on the branches of a 
 tree called Bihar, in Assam, a country bor- 
 dering on Thibet, and elsewhere in India. 
 It appears designed to answer the purpose 
 of defending the eggs from injury, and af- 
 fording food for the maggot in a more ad- 
 vanced state. It is formed into cells, finish- 
 ed with as much art and regularity as a 
 honeycomb, but differently arranged ; and 
 the inhabitants collect it twice a-year, in the 
 months of February and August. For the 
 purification, it is broken into small pieces, 
 and put into a canvass bag of about four feet 
 long, and not above six inches in circum- 
 ference. Two of these bags are in constant 
 use, and each of them held by two men. 
 The bag is placed over a fire, and frequently 
 turned, till the lac is liquid enough to pass 
 through its pores; when it is taken off the 
 fire, and twisted in different directions by 
 the men who hold it, at the same time dragg- 
 ing it along the convex part of a plantain 
 tree prepared for this purpose ; and while 
 this is doing, the other bag is beating, to be 
 treated in the same way. The mucilaginous 
 and smooth surface of the plantain tree pre- 
 vents its adhering ; and the degree of pres- 
 sure regulates the thickness of the coating 
 of lac, at the same time that the fineness of 
 the bag determines its clearness and trans- 
 parency. 
 
 Analyzed by Mr Hatchett, stick-lac gave 
 in 100 parts, resin 68, colouring extract 
 10, wax 6, gluten 5.5, extraneous substances 
 6.5; seed-lac, resin, 88.5, colouring extract 
 2.5, wax 4.5, gluten 2 ; shell-lac, resin 90.9, 
 colouring extract 0.5, wax 4, gluten 2.8. 
 The gluten greatly resembles that of wheat, 
 if it be not precisely the same ; and the wax 
 is analogous to that of the myrica eerifera. 
 
 In India, lac is fashioned into rings, 
 beads, and other trinkets ; sealing-wax, var- 
 nishes, and lakes for painters, are made from 
 
 it; it is much used as a red dye, and wool 
 • * ' 
 
 tinged with it is employed as a fucus by the 
 ladies; and the resinous part, melted and 
 mixed with about thrice its weight of finely 
 
LAK 
 
 LAM 
 
 powdered sand, forms polishing stones. The 
 lapidaries mix powder of corundum with it 
 in a similar manner. 
 
 1 lie colouring matter is soluble in water; 
 but 1 part of borax to 5 of lac, renders the 
 whole soluble by digestion in water, nearly 
 at a boiling heat. This solution is equal 
 for many purposes to spirit varnish, and is 
 an excellent vehicle lor water colours, as 
 when once dried, water has no effect on it. 
 Lixivium of potash, soda, and carbonate of 
 soda, likewise dissolve it. So does nitric acid, 
 if digested upon it in sufficient quantity 48 
 hours. 
 
 The colouring matter of the lac loses 
 considerably of its beauty by keeping any 
 length of time ; but when extracted fresh, 
 and precipitated as a lake, it is less liable to 
 injury. Mr Stephens, a surgeon in Bengal, 
 sent home a great deal prepared in this way, 
 which afforded a good scarlet to cloth pre- 
 viously yellowed with quercitron ; but it 
 would probably have been better, if, instead 
 of precipitating with alum, he had employed 
 a solution of tin, or merely evaporated the 
 decoction to dryness. 
 
 Lac is the basis of the best sealing-wax. 
 
 * Lactates. Definite compounds of lac- 
 tic acid with the salifiable bases.* 
 
 Lacquer. Solution of lac in alcohol. 
 
 Lake. This term is used to denote a 
 species of colours formed by precipitating 
 colouring matter with some earth or oxide. 
 The principal lakes are, Carmine, Fiorcnce- 
 lake, and lake from Madder. 
 
 For the preparation of Carmine , four 
 ounces of finely pulverized cochineal are to 
 be poured into four or six quarts of rain or 
 distilled water, that has been previously boil- 
 ed in a pewter kettle, and boiled with it for 
 the space of six minutes longer; (some ad- 
 vise to add, during the boiling, two drachms 
 of pulverized crystals of tartar). Eight 
 scruples of Roman alum in powder are then 
 to be added, and the whole kept upon the 
 fire one minute longer. As soon as the gross 
 pow der has subsided to the bottom, and the 
 decoction is become clear, the latter is to be 
 carefully decanted into large cylindrical 
 glasses covered over, and kept undisturbed, 
 till a fine powder is observed to have settled 
 at the bottom. The superincumbent liquor 
 is then to be poured off from this powder, 
 and the powder gradually dried. From the 
 decanted liquor, which is stiil much colour- 
 ed, the rest of the colouring matter may be 
 separated by means of the solution of tin, 
 when it yields a carmine little inferior to the 
 other. 
 
 For the preparation of Florentine lake, 
 the sediment of cochineal, that remained in 
 the kettle, may be boiled with the requisite 
 quantity of water, and the red liquor like- 
 wise, that remained after the preparation of 
 tiic carmine mixed with it, and the whole 
 
 precipitated with the solution of tin. 'Die 
 red precipitate must: be frequently edulcor- 
 ated with water. Exclusively of this, two 
 ounces of fresh cochineal, and one of crys- 
 tals, of tartar, are to be boiled with a suffi- 
 cient quantity of water, poured off clear, and 
 precipitated with the solution of tin, and 
 the precipitate washed. At the same time, 
 two pounds of alum are also to be dissolved 
 in water, precipitated with a lixivium of pot- 
 ash, and the white earth repeatedly washed 
 with boiling water. Finally, both precipi- 
 tates are to be mixed together in their liquid 
 state, put upon a filter, and dried. For the 
 preparation of a cheaper sort, instead of co- 
 chineal, one pound of Brazil wood may be 
 employed in the preceding manner. 
 
 For the following process for making a 
 lake from madder , the Society of Arts voted 
 Sir II. C. Englefield their gold medal. En- 
 close two ounces troy of the finest Dutch 
 crop madder in a bag of fine and strong cali- 
 co, large enough to hold three or four times 
 as much. Put it into a large marble or 
 porcelain mortar, and pour on it a pint of 
 clear soft water cold. Press the bag in 
 every direction, and pound and rub it about 
 with a pestle, as much as can be done with- 
 out tearing it, and when the water is loaded 
 with colour, pour it off. Repeat this process 
 till the water comes oft’ but slightly tinged, 
 for which about five pints will he sufficient. 
 Heat all the liquor in an earthen or silver 
 vessel, till it is near boiling, and then pour 
 it into a large basin, into which a troy ounce 
 of alum dissolved in a pint of boiling soft 
 water has been previously put. Stir the 
 mixture together, and while stirring, pour in 
 gently about an ounce and half of a saturat- 
 ed solution of subcarbonate of potash. Let 
 it stand till cold to settle; pour oft’ the clear 
 yellow liquor; add to the precipitate a quart 
 of boiling soft water, stirring it well ; and 
 when cold, separate by filtration the lake, 
 which should weigh half an ounce. If less 
 alum be employed, the colour will be some- 
 what deeper; with less than three- fourths 
 of an ounce, the whole of the colouring 
 matter will not unite with the alumina. 
 Fresh madder root is equal, if not superior, 
 to the dry. 
 
 Almost all vegetable colouring matters 
 may be precipitated into lakes, more or less 
 beautiful, by means of alum or oxide of 
 tin. 
 
 La Mr. Sec Light. 
 
 * Lamp of Safety, for coal mines, the in- 
 valuable and splendid invention ot Sir II. 
 Davy. For an account of the principles on 
 which it acts, see Combustion, ^e shall 
 here describe its construction. 
 
 In the parts of coal-mines where danger 
 was apprehended trom fire-damp, miners had 
 been accustomed to guide themselves, or to 
 work, by the light afforded by the sparks of 
 
LAM 
 
 LAM 
 
 steel, struck off from a wheel of flint. Hut 
 even this apparatus, though much less dan- 
 gerous than a candle, sometimes produced 
 explosions of the fire-damp. 
 
 A perfect security from accident is, how- 
 ever, offered to the miner in the use of a 
 safe- lamp, which transmits its light, and is 
 fed with air, through a cylinder of iron or 
 copper wire-gauze ; and tiiis fine invention 
 has the advantage of requiring no machinery, 
 no philosophical knowledge to direct its u$e, 
 and is made at a very cheap rate. 
 
 The apertures in the gauze should not be 
 
 more than of an inch square. As the 
 fire-damp is not inflamed by ignited wire, 
 the thickness of the wire is not of importance, 
 but wire from to of an inch in dia- 
 meter is the most convenient. 
 
 The cage or cylinder should be made by 
 double joinings, the gauze being folded over 
 in such a manner, as to leave no apertures. 
 When it is cylindrical, it should not be more 
 than two inches in diameter; for in larger 
 cylinders, the combustion of the fire-damp 
 renders the top inconveniently hot ; and a 
 double top is always a proper precaution, 
 fixed \ or ^ of an inch above the first top. 
 
 The gauze cylinder should be fastened to 
 the lamp, by a screw of four or five turns, 
 and fitted to the screw by a tight ring. All 
 joinings in the lamp should be made with 
 hard solder ; and the security depends upon 
 the circumstance, that no aperture exists in 
 the apparatus, larger than in the wire gauze. 
 
 The parts of the lamp are, 
 
 1. The brass cistern which contains the 
 oil, pierced near the centre with a vertical 
 narrow tube, nearly filled with a wire which 
 is recurved above, on the level of the burner, 
 to trim the wick, by acting on the lower end 
 of the wire, with the fingers. It is called 
 the safety- trimmer. 
 
 2. The rim, in which the wire-gauze cover 
 is fixed, and which is fastened to the cistern 
 by a moveable screw. 
 
 3. An aperture for supplying oil, fitted 
 with a screw or a cork, and which communi- 
 cates with the bottom of the cistern by a tube ; 
 and a central aperture for the wick. 
 
 4. The wire-gauze cylinder, which should 
 not have less that 625 apertures to the square 
 inch. 
 
 5. The second top ^ of an inch above the 
 first, surmounted by a brass or copper plate, 
 to which the ring of suspension is fixed. 
 
 6. Four or six thick vertical w ires, joining 
 the cistern below, with the top plate, and 
 serving as protecting pillars round the cage. 
 
 When the wire-gauze safe-lamp is lighted 
 and introduced into an atmosphere gradually 
 mixed with fire-damp, the first effect of the 
 fire-damp is to increase the length and size 
 of the flame. When the inflammable gas 
 forms as much as ^ of the volume of the 
 
 air, the cylinder becomes filled with a feeble 
 blue flame, but the flame of the wick appears 
 burning brightly within the blue flame, and 
 the light of the wick augments till the fire- 
 damp increases to jr or j, when it is lost in 
 the flame of the fire-damp, which in this case 
 fills the cylinder with a pretty strong light. 
 As long as any explosive mixture of gas exists 
 in contact with the lamp, so long it will give 
 light, and when it is extinguished, which 
 happens when the foul air constitutes as 
 much as y of the volume of the atmosphere, 
 the air is no longer .proper for respiration ; 
 for though animal life will continue where 
 flame is extinguished, yet it is always with 
 suffering. By fixing a coil of platinum wire 
 above the wick, ignition will continue in the 
 metal when the lamp itself is extinguished, 
 and from the ignited wire, the wick may be 
 again rekindled, on going into a less inflam- 
 mable atmosphere. 
 
 “ We have frequently used the lamps 
 where the explosive mixture was so high, as 
 to heat the wire-gauze red-hot ; but on exa- 
 mining a lamp which has been in constant 
 use for three months, and occasionally sub- 
 jected to this degree of heat, I cannot per- 
 ceive that the gauze cylinder of iron wire is 
 at all impaired. I have not, however, thought 
 it prudent, in our present state of experience, 
 to persist in using the lamps under such cir- 
 cumstances, because I have observed, that in 
 such situations the particles of coal dust 
 floating in the air, fire at the gas burning 
 within the cylinder, and fly off in small lu- 
 minous sparks. This appearance, I must 
 confess, alarmed me in the first instance, but 
 experience soon proved that it was not dan- 
 gerous. 
 
 “ Besides the facilities afforded by tins 
 invention, to the working of coal-mines, 
 abounding in fire-damp, it has enabled the 
 directors and superintendents to ascertain, 
 with the utmost precision and expedition, 
 both the presence, the quantity, and correct 
 situation of the gas. Instead of creeping 
 inch by inch with a candle, as is usual, along 
 the galleries of a mine suspected to contain 
 fire-damp, in order to ascertain its presence, 
 we walk firmly oil with the safe-lamps, and, 
 with the utmost confidence, prove the actual 
 state of the mine. By observing attentively 
 the several appearances upon the flame of the 
 lamp, in an examination of this kind, the 
 cause of accidents which happened to the 
 most experienced and cautious miners, is 
 completely developed ; and this has hitherto 
 been in a great measure matter of mere con- 
 jecture. 
 
 “ It is not necessary that I should enlarge 
 upon the national advantages which must 
 necessarily result from an invention, calcu- 
 lated to prolong our supply of mineral coal, 
 because I think them obvious to every re— 
 
LEA 
 
 LEA 
 
 fleeting mind ; but I cannot conclude, with- 
 out expressing my highest sentiments of ad- 
 miration for those talents, which have de- 
 veloped the properties, and controlled the 
 power, of one of the most dangerous ele- 
 ments, which human enterprize has hitherto 
 had to encounter.” — See Letter to Sir H. 
 Davy, in Journal of Science, vol.i. p.302. 
 by John Buddie, Esq. generally and justly 
 esteemed the most scientific coal-miner in 
 the kingdom.* 
 
 * Lana Philosothica. The snowy flakes 
 of white oxide, which rise and float in the 
 nir, from the combustion of zinc. * 
 
 Lampblack. The finest lampblack is pro- 
 duced by collecting the smoke from a lamp 
 with a long wick, which supplies more oil 
 than can be perfectly consumed, or by suffer- 
 ing the flame to play against a metalline 
 cover, which impedes the combustion, not 
 only by conducting off part of the heat, but 
 by obstructing the current of air. Lamp- 
 black, however, is prepared in a much 
 cheaper way, for the demands of trade. The 
 dregs which remain after the eliquation of 
 pitch, or else small pieces of fir-wood, are 
 burned in furnaces of a peculiar construc- 
 tion, the smoke of which is made to pass 
 through a long horizontal flue, terminating 
 in a close boarded chamber. The roof of 
 this chamber is made of coarse cloth, through 
 which the current of air escapes, while the 
 soot remains behind. 
 
 Lapis Infernalis. Potash. 
 
 Lapis Lazuli. Azure-stone. 
 
 Lapis Nephritic us. See Nephrite. 
 
 Lapis Ollaius. Potstone. 
 
 Lava. See Volcanic Products. 
 
 Lazuli (Lapis). Azure-stone. 
 
 Lead, is a white metal of a considerably 
 blue tinge, very soft and flexible, not very 
 tenacious, and consequently incapable of being 
 drawn into fine wire, though it is easily ex- 
 tended into thin plates under the hammer. 
 Its sp. gr. is 11.55. It melts at 612°. In 
 a strong heat it boils, and emits fumes ; dur- 
 ing which time, if exposed to the air, its 
 oxidation proceeds with considerable rapi- 
 dity. Lead is brittle at the time of congela- 
 tion. In this state it may be broken to 
 pieces with a hammer, and the crystallization 
 of its internal parts will exhibit an arrange- 
 ment in parallel lines. 
 
 Lead is not much altered by exposure to 
 air or water, though the brightness of its 
 surface, when cut or scraped, very soon goes 
 off. It is probable that a thin stratum of 
 oxide is formed on the surface, which defends 
 the rest of the metal from corrosion. 
 
 * There are certainly two, perhaps three 
 oxides of lead : 
 
 1. The powder precipitated by potash from 
 the solution of the nitrate of lead, being dried, 
 forms the yellow protoxide. "When some- 
 what vitrified, it constitutes litharge, and 
 
 combined with carbonic acid, white lead or 
 ceruse. It has been obtained by M. Ilouton- 
 Labillardiere, in dodecahedral white crystals, 
 about the size of a pin-head, by slow deposi- 
 tion, from a solution of litharge in soda. 
 Heat volatilizes it. It is of very great im- 
 portance to know accurately the composition 
 of this oxide of lead, especially in consequence 
 of its great influence in the analyses of or- 
 ganic bodies. The mean of Berzelius’s last 
 experiments, as detailed in the 5th vol. of 
 the A f/iandlingar i Fysik , and translated into 
 the Ann. of Phil, for February 1820, gives 
 us 7.73 for the quantity of oxygen, com- 
 bined with 100 of lead in 107.73 of the prot- 
 oxide, whence the prime equivalent of lead 
 comes out 12.9366. The very near ap- 
 proach of this to 13, will justify us in adopt- 
 ing this round number ; and in estimating 
 the equivalent of the protoxide at 14. The 
 pigment massicot is merely this oxide. 
 
 2. When massicot has been expose^ for 
 about 48 hours to the flame of a reverbera- 
 tory furnace, it becomes red-lead, or minium. 
 This substance has a sp. gr. of 8.94. At a 
 red-heat, it gives out oxygen, and passes in- 
 to vitrified protoxide. It consists of 100 
 lead + ii .08 oxygen ; and it may be re- 
 presented as a compound of 2 primes of lead 
 + 3 oxygen ; or of 1 prime protoxide -J- 1 
 prime peroxide. 
 
 3. If upon 100 parts of red-lead, we di- 
 
 gest nitric acid of the sp. gr. 1.26, 92.5 parts 
 will be dissolved, but 7.5 of a dark-brown 
 powder will remain insoluble. This is the 
 peroxide of lead, and consists of 100 lead 
 -}- 15.4 oxygen; or 13 2 = 15. 
 
 By passing a stream of chlorine through 
 red-lead diffused in water, we obtain a solu- 
 tion, which yields by potash an abundant 
 precipitate of the brown oxide of lead. From 
 100 of minium, 6S of the peroxide may be 
 obtained. It is tasteless, and with muriatic 
 acid evolves chlorine. When heated, oxygen 
 is disengaged, and protoxide remains. The 
 red-lead of commerce is often very impure, 
 containing yellow oxide, sulphate of lead, 
 submuriate of lead and silica. 
 
 Chloride of lead is formed, either by plac- 
 ing lead in chlorine, or by exposing the 
 muriate to a moderate heat. It is a semi- 
 transparent greyish- white mass, somewhat 
 like horn, whence the old name of plumbum 
 corneum. It is fixed at a red-heat in close 
 vessels, but it evaporates at that temperature 
 in the open air. By Dr Davy’s analysis, it 
 consists of chlorine 25. 7 S -|- lead 74.22 ; or 
 4.5 -f 15. 
 
 The iodide is easily formed, by heating 
 tho two constituents. It has a fine yellow 
 colour. It precipitates when we pour hydrio- 
 date of potash into a solution of nitrate of lead. 
 
 The salts of lead have the protoxide for 
 their base, and are distinguishable by the 
 follow ing general characters ; — 
 
LEA 
 
 LEA 
 
 1. The salts which dissolve in water, 
 usually give colourless solutions, which have 
 an astringent sweetish taste. 
 
 2. Placed on charcoal they all yield, by the 
 blow-pipe, a button of lead. 
 
 3. Ferroprussiate of potash occasions in 
 their solutions a white precipitate. 
 
 4. Hydrosulphuret of potash, a black pre- 
 cipitate, 
 
 5. Sulphuretted hydrogen, a black preci- 
 pitate. 
 
 6. Gallic acid, and infusion of galls, a 
 white precipitate. 
 
 7. A plate of zinc, a w hite precipitate, or 
 metallic lead.* 
 
 Most of the acids attack lead. The sul- 
 phuric does not act upon it, unless it be con- 
 centrated and boiling. Sulphurous acid gas 
 escapes during this process, and the acid is 
 decomposed. When the distillation is car- 
 ried on to dryness, a saline white mass re- 
 mains, a small portion of which is soluble in 
 water, and is the sulphate of lead ; it affords 
 crystals. The residue of the white mass is 
 an insoluble sulphate of lead. * It consists of 
 5 acid-j- 14 protoxide.* 
 
 Nitric acid acts strongly on lead. 
 
 * The nitrate solution, by evaporation, 
 yields tetrahedral crystals, which are white, 
 opaque, possess considerable lustre, and 
 have a sp. gr. of 4. They dissolve in 7.6 
 parts of boiling water. They consist of 6.75 
 acid -{-14 protoxide ; or nearly 1 -f- 2. 
 
 A subnitrate may be formed in pearl co- 
 loured scales, by boiling in water, equal 
 weights of the nitrate and protoxide. 
 
 A subnitrite of lead may be formed, by 
 boiling a solution of 10 parts of the nitrate, 
 on 7. 8 of metallic lead. If more of the metal 
 be used, a quadro- subnitrite results. By 
 saturating one-half of the oxide of the sub- 
 nitrite, with the equivalent proportion of 
 sulphuric acid, a neutral nitrite is formed.* 
 
 Muriatic acid acts directly on lead by heat, 
 oxidizing it and dissolving part of its oxide. 
 
 The acetic acid dissolves lead and its 
 oxides ; though probably the access of air 
 may be necessary to the solution of the 
 metal itself in this acid. White lead, or 
 ceruse , is made by rolling leaden plates spi- 
 rally up, so as to leave the space of about 
 an inch between each coil, and placing 
 them vertically in earthen pots, at the bot- 
 tom of which is some good vinegar. The 
 pots are to be covered, and exposed for a 
 length of time to a gentle heat in a sand- 
 bath, or by bedding them in dung. The 
 vapour of the vinegar, assisted by the ten- 
 dency of the lead to combine with the oxy- 
 gen which is present, corrodes the lead, 
 and converts the external portion into a 
 white substance which comes off in flakes, 
 when the lead is uncoiled. The plates are 
 thus treated repeatedly, until they are cor- 
 roded through. Ceruse is the only w'hite 
 
 used in oil paintings. Commonly it is adul - 
 terated with a mixture of chalk in the shops. 
 
 It may be dissolved without difficulty in the 
 acetic acid, and affords a crystallizabie salt, 
 called sugar ojlead from its sweet taste. I his, 
 like all the preparations of lead, is a deadly 
 poison. The common sugar of lead is an 
 acetate ; and Goulard’s extract, made by 
 boiling litharge in vinegar, a subacetate. The 
 power of this salt, as a coagulator of mucus, 
 is superior to the other. If a bit of zinc be 
 suspended by brass or iron wire, or a thread, 
 in a mixture of water and the acetate of lead, 
 the lead will be revived, and form an arbor 
 Saturni. 
 
 * The acetate, or sugar of lead, is usually 
 crystallized in needles, which have a silky 
 appearance. They are flat four-sided prisms 
 with dihedral summits. Its sp. gr. is 2.345. 
 
 It is soluble in three and a half times its 
 weight of cold water, and in somewhat less 
 
 O # 
 
 of boiling water. Its constituents are 26.96 
 acid + 58.71 base + 14.32 water. — Ber- 
 zelius. 
 
 The subacetate crystallizes in plates, and 
 is composed of 13.23 acid -{- 86.77 base; or 
 1 prime -}- 3. In the extensive and excellent 
 sugar of lead works of Mr Mackintosh, and of 
 Mr Ramsay, at Glasgow, this salt is occasion- 
 ally formed in large flat rhomboidal prisms, 
 which Dr Thomson supposes to consist of five 
 atoms oxide of lead, four atoms acetic acid, 
 and 19 atoms water; while he considers the 
 ordinary acetate as a compound of one atom 
 acid, one atom oxide, and three atoms water. 
 The sulphuret, sulphate, carbonate, phos- 
 phate, arseniate, and chromate of lead, are 
 found native, and will be described among 
 its Orf.s. 
 
 When lead is alloyed with an equal weight 
 of tin, or perhaps even less, it ceases to be 
 acted on by vinegar. Acetate and subace- 
 tate of lead in solution, have been used as 
 external applications to inflamed surfaces, 
 and scrofulous sores, and as eye-washes. In 
 some extreme cases of haunorrhagy from 
 the lungs and bowels, and uterus, the former 
 salt has been prescribed, but rarely and in 
 minute doses, as a corrugant or astringent. 
 The colic of the painters, and that formerly 
 prevalent in certain counties of England, 
 from the lead used in the cyder presses, shew 
 the very deleterious operation of the oxide, or 
 salts of this metal, when habitually introduc- 
 ed into the system in the minutest quantities 
 at a time. Contraction of the thumbs, par- 
 alysis of the hand, or even of the extremities, 
 have not unfrequently supervened. A course 
 of sulphuretted hydrogen waters, laxative*, 
 of which sulphur, castor-oil, sulphate of 
 magnesia, or calomel, should be preferred, a 
 mercurial course, the hot sea-bath, and elec- 
 tricity, are the appropriate remedies. 
 
 Dealers in wines have occasionally sweet- 
 ened them when acescent, with litharge or its 
 
LEA 
 
 LEP 
 
 salts. This deleterious adulteration may be 
 detected by sulphuretted hydrogen water, 
 which will throw down the lead in the state 
 of a dark brown sulphuret. Or subcar- 
 bonate of ammonia, which is a more delicate 
 test, may be employed to precipitate the lead 
 in the state of a white carbonate ; which, on 
 being washed and digested with sulphuretted 
 hydrogen water, -will instantly become black. 
 If the white precipitate be gently heated, it 
 will become yellow, and, on charcoal before 
 the blow-pipe, it will yield a globule of lead. 
 Chromate of potash, will throw down from 
 saturnine solutions, a beautiful orange-yellow 
 powder. Burgundy wine, and all such as 
 contain tartar, will not hold lead in solution, 
 in consequence of the insolubility of the 
 tartrate. 
 
 The proper counter-poison for a dangerous 
 dose of sugar of lead, is solution of Epsom or 
 Glauber salt, liberally swallowed ; either of 
 which medicines instantly converts the pois- 
 onous acetate of lead into the inert and in- 
 noxious sulphate. The sulphuret of potash, 
 so much extolled by Navier, instead of be- 
 ing an antidote, acts itself as a poison on the 
 stomach. * 
 
 Oils dissolve the oxide of lead, and be- 
 come thick and consistent ; in which state 
 they are used as the basis of plasters, cements 
 for w r ater- works, paints, &c. 
 
 Sulphur readily dissolves lead in the dry way, 
 and produces a brittle compound, of a deep 
 grey colour and brilliant appearance, which 
 is much less fusible than lead itself; a pro- 
 perty which is common to all the combina- 
 tions of sulphur with the more fusible metals. 
 
 The phosphoric acid, exposed to heat to- 
 gether with charcoal and lead, becomes con- 
 verted into phosphorus, which combines with 
 the metal. This combination does not 
 greatly differ from ordinary lead ; it is mal- 
 leable, and easily cut with a knife; but it 
 loses its brilliancy more speedily than pure 
 lead ; and when fused upon charcoal with 
 the blow-pipe, the phosphorus burns, and 
 leaves the lead behind. 
 
 Litharge fused with common salt decom- 
 poses it ; the lead unites with the muriatic 
 acid, and forms a yellow compound, used as 
 a pigment. The same decomposition takes 
 place in the humid way, if common salt be 
 macerated with litharge ; and the solution 
 will contain caustic alkali. 
 
 Lead unites with most of the metals. 
 Gold and silver are dissolved by it in a slight 
 red-heat. Both these metals are said to be 
 rendered brittle by a small admixture of 
 lead, though lead itself is rendered more 
 ductile by a small quantity of them. Pla- 
 tina forms a brittle compound with load ; 
 mercury amalgamates with it ; but the lead 
 is separated from the mercury by agitation, 
 in the form of an impalpable black powder, 
 oxygen being at the same time absorbed. 
 
 Copper and lead do not unite but with a 
 strong heat. If lead be heated so as to boil 
 and smoke, it soon dissolves pieces of cop- 
 per thrown into it; the mixture, when cold, 
 is brittle. The union of these two metals 
 is remarkably slight ; for, upon exposing the 
 mass to a heat no greater than that in which 
 lead melts, the lead almost entirely runs off 
 by itself. This process is called eliquation. 
 The coarser sorts of lead, which owe their 
 brittleness and granulated texture to an ad- 
 mixture of copper, throw it up to the surface 
 on being melted by a small beat. Iron 
 docs not unite with lead, as long as both 
 substances retain their metallic form. Tin 
 unites very easily with this metal, and forms 
 a compound, which is much more fusible 
 than lead by itself, and is, for this reason, 
 used as a solder for lead. Two parts of 
 lead and one of tin, form an alloy more fusi- 
 ble than cither metal alone : this is the solder 
 of the plumbers. Bismuth combines readily 
 with lead, and affords a metal of a fine close 
 grain, but very brittle. A mixture of eight 
 parts bismuth, five lead, and three tin, will 
 melt in a heat which is not sufficient to cause 
 water to boil. Antimony forms a brittle 
 alloy with lead. Nickel, cobalt, manganese, 
 and zinc, do not unite with lead by fusion. 
 
 All the oxides of lead are easily revived 
 with heat and carbon. 
 
 Leather. The skins of animals prepared 
 by maceration in lime-water, and afterward 
 with astringent substances. See Tanning. 
 
 * Leaves of Plants. See Chloropiiyle.* 
 
 Lees (Soap). See Potash; also Soap. 
 
 Lemons. See Acid (Citric). 
 
 * Lemnian Earth, or Sphragide. Co- 
 lour yellowish -grey, and frequently marbled 
 with rusty spots. Dull. Fracture fine 
 earthy. Meagre to the feel. Adheres 
 slightly to the tongue. When plunged in 
 water, it falls to pieces with disengagement 
 of air-bubbles. Its constituents are, 66 sili- 
 ca, 14.5 alumina, 0.25 magnesia, 0.25 lime, 
 3.5 soda, 6 oxide of iron, 8.5 water. — Alnp- 
 roth. It has hitherto been found only in the 
 Island of Stalimene, (ancient Lemnos). It 
 is reckoned a medicine in Turkey ; and is 
 dug up only once a-year, with religious so- 
 lemnities, cut into spindle-shaped pieces, and 
 stamped with a seal. It was esteemed an 
 antidote to poison and the plague in 
 Homer’s time; a virtue to which it has not 
 the slightest claim.* 
 
 * Lefidolite. Colour peach-blossom red, 
 sometimes grey. Massive, and in small con- 
 cretions. Lustre glistening, pearly. Cleavage 
 single. Fracture, coarse splintery. Feebly 
 translucent. Soft. Rather sectile. Rather 
 easily frangible. Sp. gr. 2.6 to 2.8. It in- 
 tumesces before the blow-pipe, and melts 
 easily into a milk-white translucent globule. 
 Its constituents are 54 silica, 20 alumina, 18 
 potash, 4 fluate of lime, .3 manganese, and 1 
 
LIG 
 
 LIG 
 
 i ro n.— Vauquelin. It occurs in limestone 
 
 at Dalmally, and on the north side of Loch- 
 fine ; on the east side of Loch-leven, nearly 
 opposite the Inn at Balachulish. It is found 
 in many places on the continent. On ac- 
 count of its beautiful colour, it has been cut 
 into snuff-boxes, but it is rather soft and 
 greasy to the aspect. — Jameson. * 
 
 *■ Leucite. Dodecahedral zeolite ol 
 Jameson. Colour white, whence its name. 
 Generally in roundish imbedded grains, or 
 crystallized in acute double eight-sided py- 
 ramids. Internal lustre shining. Cleavage 
 imperfect. Fracture imperfect conchoidal. 
 Translucent. Refracts single. Harder than 
 apatite, but softer than felspar. Brittle. Sp. 
 gr. 2.5. With borax it fuses into a brown- 
 ish transparent glass. Its constituents are 
 56 silica, 20 alumina, 20 potash, 2 lime, and 
 2 loss. — Vavquelin. It is almost peculiar 
 to Italy, occurring in trap-rocks and lavas, at 
 Albano, Frascati, and near Naples.* 
 
 * Libavius, smoking liquor of ; deuto- 
 chloride of tin.* 
 
 Levigation. The mechanical process of 
 grinding the parts of bodies to a fine paste, 
 by rubbing the flat face of a stone called the 
 muller, upon a table or slab called the stone. 
 Some fluid is always added in this process. 
 The advantage of levigation with a stone and 
 muller, beyond that of triturating in a mor- 
 tar, is, that the materials can more easily be 
 scraped together, and subjected to the action 
 of the muller, than in the other case to that 
 of the pestle ; and, from the flatness of the 
 two surfaces, they cannot elude the pressure. 
 
 * Lievrite or Yenite. Colour black. 
 Massive ; in distinct concretions ; and crys- 
 tallized ; in oblique or almost rectangular 
 four-sided prisms, varying from acicular to 
 the thickness of an inch. Lateral planes 
 longitudinally streaked. Lustre glistening, 
 semi- metallic. Fracture uneven. Opaque. 
 Scratches glass, and gives a few sparks with 
 steel, but is scratched by adularia. Streak 
 unchanged. Easily frangible. Sp. gr. 3.9. 
 Magnetic on being heated ; its colour at the 
 same time changing to reddish-brown. It 
 melts into an opaque black bead, having a 
 metallic aspect, and magnetic. Its constitu- 
 ents are 30 silica, 12.5 lime, 57.5 oxide of 
 iron and oxide of manganese, the last of 
 which forming only 2 or 3 parts. It occurs 
 in primitive limestone in the island of Elba.* 
 
 * Light. The agent of vision. 
 
 Some philosophers regard light as consist- 
 ing of particles of inconceivable minuteness, 
 emitted in succession by luminous bodies, 
 which move in straight lines, at the rate of 
 200,000 miles per second. 
 
 Others conceive that it consists in certain 
 undulations communicated by luminous bo- 
 dies, to an etherial fluid which fills all space. 
 This fluid is composed oi‘ the most subtile 
 
 matter, is highly elastic, and the undulations 
 are propagated through it with great velocity, 
 in spherical superficies proceeding from a 
 centre. This view derives great plausibility 
 from its happy application by Huygens, to 
 explain a very difficult class of optical phe- 
 nomena, the double refraction of calcareous 
 spar and other bodies. 
 
 The common refraction is explained by 
 Huygens on the supposition, that the undu- 
 lations in the luminous fluid are propagated 
 in the form of spherical waves. The double 
 refraction is explained on the supposition, 
 that the undulations of light, in passing 
 through the calcareous spar, assume a sphe- 
 roidal form ; and this hypothesis, though it 
 does not apply with the same simplicity as 
 the former, yet admits of such precision, that 
 a proportion of the axes of the spheroids 
 may be assigned, which will account for the 
 precise quantity of the extraordinary refrac- 
 tion, and for all the phenomena dependent 
 on it, which Huygens had studied with great 
 care, and had reduced to the smallest num- 
 ber of general facts. 
 
 “ That these spheroidal undulations ac- 
 tually exist,” says the celebrated Playfair, 
 
 “ he would after all be a bold theorist who 
 should affirm ; but that the supposition of 
 their existence is an accurate expression of 
 the phenomena of double refraction,, cannot 
 be doubted. When one enunciates the hy- 
 pothesis of the spheroidal undulations, he in 
 fact expresses in a single sentence all the 
 phenomena of double refraction. The hy- 
 pothesis is therefore the means of represent- 
 ing these phenomena, and the laws which 
 they obey, to the imagination or the under- 
 standing ; and there is perhaps no theory in 
 optics, and but very few in natural philoso- 
 phy, of which more can be said. Theory 
 therefore, in this instance, is merely to be re- 
 garded as the expression of a general law, 
 and in that light I think it is considered by 
 La Place.” 
 
 Dr Young has selected from Sir Isaac 
 Newton’s various writings, many passages 
 favourable to the admission of the undula- 
 tory theory of light, or of a luminiferous 
 ether pervading the universe, rare and elastic 
 in a high degree. “ Is not the heat (of the 
 warm room) conveyed through the vacuum 
 by the vibrations of a much subtiler medium 
 than air ? And is not this medium the same 
 with that medium by which light is reflected 
 and refracted, and by whose vibrations light 
 communicates heat to bodies, and is put into 
 fits of easy reflection and easy transmission ? 
 And do not the vibrations of this medium in 
 hot bodies contribute to the intenseness and 
 duration of their heat? And do not hot bo- 
 dies communicate their heat to contiguous 
 cold ones, by the vibrations of this medium, 
 propagated from them into the cold ones? 
 47 
 
LIG 
 
 LIG 
 
 And is not tills medium exceedingly more 
 rare and subtile than the air, and exceeding- 
 ly more elastic and active ? And doth it not 
 readily pervade all bodies? And is it not by 
 its elastic force expanded through all the 
 heavens?” — “ It any one would ask how a 
 medium can be so rare, let him tell me how 
 an electric body can by friction emit an ex- 
 halation so rare and subtile, and yet so po- 
 tent ? And how the effluvia of a magnet can 
 pass through a plate of glass without resist- 
 ance, and yet turn a magnetic needle beyond 
 the glass?” — Optics, Qu. 18. 22. “ Were I 
 to assume an hypothesis, it should be this, if 
 propounded more generally, so as not to de- 
 termine what light is, farther than that it is 
 something or other capable of exciting vi- 
 brations in the ether; for thus it will be- 
 come so general, and comprehensive of other 
 hypotheses, as to leave little room for new 
 ones to be invented.” — Birch , iii. 249. 
 
 Dr Young shews, that many phenomena 
 inexplicable on the notion of radiating cor- 
 puscles, are easily reconciled to the theory of 
 undulation. “ On the whole,” says this 
 profound philosopher, “ it appears that the 
 few optical phenomena, which admit of ex- 
 planation by the corpuscular system, are 
 equally consistent with this theory; that 
 many others which have been long known, 
 but never understood, become by these 
 means perfectly intelligible; and that several 
 new facts are found to be thus, only, reduci- 
 ble to a perfect analogy with other facts, and 
 to the simple principles of the undulatory 
 system.” — Nat. Phil. vol. ii. p. 651. 
 
 I think, however, that the new discoveries 
 on polarized light may be more easily re- 
 ferred to the corpuscular than undulatory 
 hypothesis. 
 
 The physical affections of light are foreign 
 to this work. Its chemical relations are 
 alone to be considered. These may be con- 
 veniently referred to four heads: — 
 
 1. Of the mean refractive and dispersive 
 powers of different bodies. 
 
 2. Of the action of the different prismatic 
 colours on chemical matter. 
 
 3. Of the polarization of light. 
 
 4. Of the absorption and disengagement 
 of light or phosphorescence. 
 
 1. Newton first discovered that certain 
 bodies exercise on light a peculiar attractive 
 force. When a ray passes obliquely from 
 air into any transparent liquid or solid sur- 
 face, it undergoes at entrance an angular 
 flexure, which is called refraction. The 
 variation of this departure from the rectili- 
 neal path for any particular substance, de- 
 pends on the obliquity of the ray to the re- 
 fracting surface ; so that the sine of the angle 
 of refraction, is to that of the angle of inci- 
 dence, in a constant ratio. Now Newton 
 found, that unctuous or inflammable bodies 
 occasioned a greater deviation in the lumi- 
 
 nous rays than their attractive mass or den- 
 sity gave reason to expect. Hence he con- 
 jectured, that both diamond and water con- 
 tained combustible matter,— a sagacious an- 
 ticipation of future chemical discovery. 
 
 Dr W ollaston invented a very ingenious 
 apparatus, in which, by means of a rectan- 
 gular prism of flint glass, the index of re- 
 fraction of each substance is read off at 
 once by a vernier, the three sides of a move- 
 able triangle performing the operations of 
 
 reduction, in a very compendious manner 
 
 Phil. Trans. 1802, or Nicholson s Journal , 
 8vo. vol. iv. p. 89. 
 
 But transparent media occasion not merely 
 a certain flexure of the white sunbeam, called 
 the mean refraction , they likewise decompose 
 it into its constituent colours. This effect is 
 called dispersion. Now the mean refractive 
 and dispersive powers of bodies are not pro- 
 portional to each other. In some refracting 
 media, the mean angle of refraction is larger, 
 whilst the angle of dispersion is smaller ; and 
 in other refracting media, the mean angle of 
 refraction is smaller, whilst the angle of dis- 
 persion is larger. In short, the knowledge 
 of the mean refractive power of a given 
 substance, will not enable us to determine its 
 dispersive power, and vice versa. 
 
 From the refractive power of bodies we 
 may in many cases infer their chemical con- 
 stitution. For discovering the purity of 
 essential oils, an examination with Dr Wol- 
 laston’s instrument may be of considerable 
 utility, on account of the smallness of the 
 quantity requisite for trial. “ In oil of 
 cloves, for instance, I have met with a wide 
 difference. The refractive power of genuine 
 oil of cloves is as high as 1.535 ; but I have 
 also purchased oil by this name which did 
 not exceed 1.498, and which had probably 
 been adulterated by some less refractive oil.” 
 This fine idea, suggested by Dr Wollaston, 
 has been happily prosecuted by M. Biot, with 
 regard to gaseous compounds. I shall first 
 give general tables of the refractive and dis- 
 persive powers of different bodies, and then 
 make some remarks on their chemical ap- 
 plications : — 
 
 Index 
 
 A vacuum, 
 
 Atmospheric air, (mean), 
 
 Ice, W. 
 
 Ice, Brewster, 
 
 Water, 1 
 
 Vitreous humour, ) Cryolite. B. 
 Ether, Wol. 
 
 Albumen, W. 
 
 Alcohol, W. 
 
 Saturated solut. of salt, Cavallo, 
 Solution of sal ammoniac, 
 
 Nitric acid, sp. gr. 1.48, W. 
 Fluor spar, W. 
 
 Sulphuric spar, W. 
 
 Spermaceti, melted, V . 
 
 of Refraction. 
 1.00000 
 1 .00033 
 1.31000 
 1.30700 
 1.336 
 1.344 
 1.35S 
 1.360 
 1.370 
 1.375 
 1.382 
 1.410 
 1.433 
 1.435 
 1.446 
 
 
 
LIG 
 
 LIG 
 
 Index of Refraction. 
 
 Crystalline; lens of an ox, W. 1.447 
 
 Alum, W. 1.457 
 
 Tallow melted, W* 1*460 
 
 Borax, C. 1.467 
 
 Oil of lavender, W. 1.467 
 
 C. (1.469) 
 
 Oil of peppermint, ^ • 1*468 
 
 Oil of olives, ^ • 1*469 
 
 Oil of almonds, W. 1.4.0 
 
 Oil of turpentine, rectified, W» 1.470 
 
 13 o. common, W. 1.476 
 
 Essence of lemon, "W. 1*476 
 
 Butter, cold, ^\* l*^ 8 ^ 
 
 Linseed oil, ^ 
 
 Do. strongest do. W. (1.657) 
 
 Tallow, cold, ^ • 1*49 
 
 Sulphate of potash, W. 1.495 
 
 Oil of nutmeg, "W* 1.497 
 
 French plate-glass, "W. 1.500 
 
 English plate-glass, ^ * 1.504 
 
 Oil of amber, W. 1.505 
 
 Balsam of capivi, "W • 1 *50 J 
 
 Gum-arabic, W. 1.514 
 
 Dutch plate-glass, W. 1.517 
 
 Caoutchouc, W. 1.524 
 
 Nitre, C. 1.524 
 
 Selenite, W. 1.525 
 
 Crown glass, common, W. 1.525 
 
 Canada balsam, W. 1.528 
 
 Centre of the crystalline of “1 
 
 fish, and dry crystalline > W. 1.530 
 of an ox, J 
 
 Pitch, 
 
 W. 
 
 
 Radcliffe crown-glass, W. 
 
 1.533 
 
 Anime, 
 
 W. 
 
 1 .535 
 
 Copal, 
 
 W. 
 
 1.555 
 
 Oil of cloves, 
 White wax, cold, 
 Elemi, 
 
 Mastic, 
 
 W. 
 
 . 
 
 1.535 
 
 Arseni ate of potash, 
 Sugar after fusion, 
 Spermaceti cold, 
 Red sealing-wax, 
 
 > W. 
 
 
 Oil of sassafras, 
 
 w. 
 
 1.53(7 
 
 Bees-wax, 
 
 w. 
 
 1.542 
 
 Boxwood, 
 
 w. 
 
 
 Colophony, 
 
 w. 
 
 1.543 
 
 Old plate- glass, 
 
 w. 
 
 1.545 
 
 Rock crystal, (double), W. 
 
 1.547 
 
 Amber, 
 
 w. 
 
 1.547 
 
 
 c. 
 
 (1.556) 
 
 Opium, 
 
 w. 
 
 
 Mica, 
 
 w. 
 
 
 Phosphorus, 
 
 w. 
 
 1.579 
 
 Horn, 
 
 w. 
 
 
 Flint-glass, 
 
 w. 
 
 ( 1.583 
 i 1.586 
 
 Benzoin, 
 
 w. 
 
 
 Guiacum, 
 
 w. 
 
 1.596 
 
 Balsam of Tolu, 
 
 w. 
 
 1.600 
 
 Index of Refraction. 
 
 Sulphate of barytes, (double R.) W. 
 
 1.646 
 
 Iceland spar, (strongest), 
 
 W. 
 
 1.657 
 
 Gum dragon, 
 
 w. 
 
 
 Carburet of sulphur, 
 
 Br. 
 
 1.680 
 
 White sapphire, 
 
 W. 
 
 1.768 
 
 Muriate of antimony, variable, W. 
 
 
 Arsenic, (a good test), 
 
 W. 
 
 1.811 
 
 Spinelle ruby, 
 
 W. 
 
 1.812 
 
 Jargon, 
 
 W. 
 
 1.950 
 
 Glass of antimony, 
 
 W. 
 
 1.980 
 
 Native sulphur, 
 
 W. 
 
 2.040 
 
 Do. 
 
 Brewster, 
 
 2.115 
 
 Plumbago, 
 
 W. 
 
 
 Phosphorus, 
 
 Brewster, 
 
 2.224 
 
 Diamond, Newton, bv Dr W. 
 
 2.440 
 
 Do. 
 
 Rodion, 
 
 2.755 
 
 Realgar, 
 
 Brewster, 
 
 2.510 
 
 Chromate of lead, (least refr.),do. 
 
 2.479 
 
 Do. (greatest refr.) do. 
 
 2.926 
 
 TABLE II . — Refracting Powers of Gases 
 for the temperature of 52° F. and j)r as- 
 sure 30, by MM. Piot and Arago. 
 
 Atmospheric air, 
 
 - 
 
 1 . 00000 
 
 Oxygen, 
 
 
 0.86161 
 
 Azote, 
 
 
 1.05408 
 
 Hydrogen, 
 
 
 6.61436 
 
 Ammonia, 
 
 - 
 
 2.16851 
 
 Carbonic acid, 
 
 
 1.00476 
 
 Subcarburetted hydrogen, 
 
 - 
 
 2.09270 
 
 Muriatic acid gas, 
 
 - 
 
 1.19625 
 
 TABLE III. — Dispersive Powers. 
 
 Cryolite, 
 
 Brewster, 0.022 
 
 Fluor spar, 
 
 do. 
 
 0.022 
 
 Water, 
 
 do. 
 
 0.055 
 
 Diamond, 
 
 do. 
 
 0.038 
 
 Flint glass, (highest), 
 
 do. 
 
 0.052 
 
 Carburet of sulphur, 
 
 do. 
 
 0.115 
 
 Phosphorus, 
 
 do. 
 
 0.128 
 
 Sulphur, 
 
 do. 
 
 0.150 
 
 Oil of cassia, 
 
 do. 
 
 0.159 
 
 Realgar, 
 
 do. 
 
 0.255 
 
 Chromate of lead, (least refr.) do. 
 
 0.262 
 
 Do. (greatest 
 
 refr. do. 
 
 0.400 
 
 Carburet of sulphur exceeds all fluid bo- 
 dies in refractive power, surpassing even 
 flint-glass, topaz, and tourmaline ; and in 
 dispersive power it exceeds every fluid sub- 
 stance, except oil of cassia, holding an inter- 
 mediate place between phosphorus and bal- 
 sam of Tolu. 
 
 Dr Brewster has further shewn, that all 
 doubly refracting crystals have two disper- 
 sive powers. 
 
 From Table II.it appears, that the refrac- 
 tive power of hydrogen gas greatly surpas- 
 ses not only that of the other gases, but of 
 all known bodies. This principle exists in 
 great abundance, in resins, oils, and gums, 
 where it is united to carbon and oxvgen ; 
 2 L 
 
L1G 
 
 LIG 
 
 and we must probably ascribe to it, the emi- 
 nent refractive power of these combustibles, 
 so justly observed by Newton. This elFect 
 oi hydrogen is finely displayed in ammonia, 
 whose retractive power is more than double 
 that of air ; and much superior to that of 
 water. 
 
 But since every substance ought to intro- 
 duce into its combinations, its peculiar cha- 
 racter, and preserve in them to a certain de- 
 gree, the force with which it acts on light, 
 let us endeavour to calculate in this point of 
 view, the refractive influence of the consti- 
 tuents of a compound. From our know- 
 ledge of the extreme tenuity of light, it is 
 probable, that the influence of a moderate 
 chemical condensation, ought to affect its 
 operations very slightly ; for whether it be 
 an ether or a corpuscular emanation, the ex- 
 cessive minuteness of its particles, compared 
 to the distances between the molecules of 
 bodies, ought to render the change of dis- 
 tance among the latter, unimportant. Con- 
 sequently, the refracting powers of bodies 
 ought to differ verv little from those of their 
 elements, unless a very great degree of con- 
 densation has taken place. 
 
 Hence, if we multiply the proportions of 
 azote and oxygen respectively, by their re- 
 fractive powers, we shall obtain products, 
 whose sums will coincide with the refractive 
 power of the atmosphere. Thus, 100 parts 
 by weight of the atmosphere, consist of azote 
 77.77 -j- oxygen 22.22. If we multiply 
 each of these numbers by the number repre- 
 senting the refractive power of the body, and 
 making a small correction for the carbonic 
 acid present, we shall have for the sum of 
 the products 1.0000. 
 
 Ammonia, however, furnishes a more in- 
 teresting example of the application of these 
 principles. 
 
 The refractive power of hydro- 
 gen is, - 6.61456 
 
 of azote, 1.05408 
 
 of ammonia, 2.16851 
 
 Let x be the weight of the constituent, 
 whose refractive power is, a 
 
 it = 100 — x — that whose power is b 
 and call the refractive 
 
 power of the compound, c 
 
 c I 
 
 Then x = . In the present case, 
 
 a — b 
 
 x 
 
 2,16851 -- 1.08408 
 6/6M56 — 7.03408 
 
 = 0.203 and 
 
 100 — x = 0.797 ~ the azote in 100 parts 
 of ammonia; which may be regarded as an 
 approximation. The true proportions given 
 by the equivalent ratios are, 0.823 azote -j- 
 0.177 hydrogen. If the refractive power 
 of ammonia were 2.0218, then the chemical 
 and optical analysis would coincide. 
 
 If we calculate on the above data, what 
 OPght to be the refractive power of water, as 
 
 a compound of 8 parts of oxygen + I 
 1 hydrogen, we shall obtain the number 
 1.50065', which being multiplied by 0.45502, 
 the absolute refractive power of air, when 
 we take the density of water for unity, we 
 shall have a product = 0.67984. Now, 
 according to Newton’s estimate, which M. 
 Biot has found to be exact, the refractive 
 power of water is 0.7845. Hence, we see, 
 that the compound has acquired an increas- 
 ed refractive force by condensation, above 
 the mean of its constituents, in the ratio of 
 100 to 86f. 
 
 llays of light, in traversing the greater 
 number of crystallized bodies, are commonly 
 split into two pencils ; one of which, called } 
 the ordinary ray, follows the common laws 
 of refraction, agreeably to the preceding | 
 tables, wdiilst the other, called the extraordi- 
 nary ray, obeys very different law's. This 
 phenomenon is produced in all transparent 
 crystals, whose primitive form is neither a 
 cube nor a regular octohedron. The division 
 of the beam is greater or less, according to 
 the nature of the crystal, and the direction 
 in which it is cut. But of all known sub- 
 stances, that which produces this phenome- 
 non in the most energetic manner, is the 
 rhomboidal carbonate of lime commonly call- 
 ed island spar. 
 
 2. Of the action of the different coloured , 
 ravs. If the white sunbeam, admitted 
 through a small hole of a window-shutter 
 into a darkened room, be made to pass 
 through a triangular prism of glass, it will 
 be divided into a number of splendid colours 
 which may be thrown upon a sheet of paper. 
 Newton ascertained, that if this coloured 
 image, or spectrum as it is called, be divided i 
 into 560 parts, the red will occupy 45, the | 
 orange 27, the yellow 48, the green 60, the ji 
 blue 60, the indigo 40, and the violet 80. 
 The red rays being least bent by the prism, i 
 from the direction of the white beam, are .( 
 said to be least refracted or the least refran- 
 gible; while the violet rays being always at . 
 the other extremity of the spectrum, are call- j 
 ed the most refrangible. According to l)r 
 Wollaston, when the beam of light is only 
 l-20th of an inch bread, and received by the 
 eye at the distance of 10 feet., through a clear 
 prism of flint-glass, only four colours aj>- 
 pear; red, yellowish- green, blue, and violet. 
 
 If the differently coloured rays of light 
 thus separated by the prism, be concentred 
 on one spot by a lens, they w ill reproduce 
 colourless light. Newton ascribes the diiTe- 
 rent colours of bodies, to their power ot ab- 
 sorbing all the primitive colours, except the 
 peculiar one which they reflect, and of 
 which colour they therefore appear to our 
 eye. 
 
 According to Sir William Ilerschel, the 
 different coloured rays possess very different 
 powers of illumination. The lightest green, 
 
LIG 
 
 LIG 
 
 or deepest yellow, which are near the centre, 
 throw more light on a printed page than any 
 of the rays towards either side of the spec- 
 trum. Sir H. Davy remarks, that as there 
 are more green rays in a given part of the 
 spectrum than blue rays, the difference of 
 illuminating power may depend on this cir- 
 cumstance. The rays separated by one 
 prism, are not capable of being further di- 
 vided by being passed through another ; and 
 in their relations to double refraction and 
 reflection, they appear to agree with direct 
 light. An object illuminated by any of the 
 rays in the spectrum, is seen double through 
 island crystal, in the same manner as if it 
 had been visible by white light. 
 
 Under Caloric, we have stated the power 
 of heating which the different coloured rays 
 of the spectrum apparently possess. Sir H. 
 Englefield, and M. Berard, confirmed the 
 results of Sir W. Herschel, with regard to 
 the progressive increase of calorific influence 
 from the violet to the red extremity of the 
 spectrum ; and they also found with him, 
 that a calorific influence extended beyond 
 the limit of the red light, into the unillumi- 
 nated space. M. Berard, however, observed, 
 that the maximum of effect was in the light, 
 and not beyond it. This ingenious philoso- 
 pher made a pencil of the sunbeam pass 
 across a prism of island spar. The division 
 of the rays formed two spectra , which pre- 
 sented the same properties with the single 
 spectrum. Both possessed the calorific vir- 
 tue in the same manner and degree. M. 
 Berard polarized a beam of light by reflec- 
 tion from a mirror ; and he found that in 
 all the positions in which light ceased to be 
 reflected, heat also ceased to appear. The 
 thermometer in the focus of the apparatus 
 was no longer affected. Thus, we see, that 
 the obscure heat-making principle, accom- 
 panies the luminous particles, and obeys the 
 same laws of action. 
 
 If the white luna cornea , the muriate of 
 silver moistened, be exposed to the different 
 rays in the prismatic spectrum, it will be 
 found, that no effect is produced upon it, 
 in the least refrangible rays, which occasion 
 heat without light ; that only a slight disco- 
 loration will be occasioned by the red rays; 
 that the blackening power will be greater 
 in the violet than in any other ray ; and that 
 beyond the violet, in a space perfectly ob- 
 scure to our eyes, the darkening effect will 
 be manifest on the muriate. 
 
 This fine observation, due to M. Ritter 
 and Dr Wollaston, proves, that there are 
 rays more refrangible than the rays producing 
 light and heat. As it appears, from the ob- 
 servations of M. Berthollet, that muriatic 
 acid gas is formed when horn-silver is black- 
 ened by light, the above rays may be called 
 hydrogenating. Sir H. Davy found, that a 
 ^mixture of chlorine and hydrogen acted 
 
 more rapidly upon each other, combining 
 without explosion, when exposed to the red 
 rays, than when placed in the violet rays ; 
 but that solution of chlorine in water be- 
 came solution of muriatic acid most rapidly, 
 when placed in the most refrangible rays in 
 the spectrum. He also observed, that tho 
 puce- coloured oxide of lead, when moistened, 
 gradually gained a tint of red in the least 
 refrangible rays, and at last became black, 
 but was not affected in the most refrangible 
 rays. The same change was produced by 
 exposing it to a current of hydrogen gas. 
 The oxide of mercury from calomel and wa- 
 ter of potash, when exposed to the spectrum, 
 was not changed in the most refrangible 
 rays, but became red in the least refrangible, 
 which must have been owing to the absorp- 
 tion of oxygen. The violet rays produced 
 upon moistened red oxide of mercury, the 
 same effect as hydrogen gas. 
 
 Dr Wollaston found, that guaiac, exposed 
 to the violet rays, passed rapidly from yellow 
 to green; and MM. Gay Lussac and lhe- 
 nard applied to the same influence a gaseous 
 mixture of hydrogen and chlorine, when ex- 
 plosion immediately took place. By placing 
 small bits of card, coated with moist horn- 
 silver, or little phials of those mixed gases, 
 in the different parts of the spectrum, M. 
 Berard verified the former observations of 
 the chemical power acquiring a maximum 
 In the violet ray, and existing even beyond 
 it ; but he also found, that by leaving the 
 tests a sufficient time in the indigo and blue 
 rays, a perceptible effect was produced upon 
 them. He concentrated by a lens all that 
 portion of the spectrum which extends from 
 the green to the extreme boundary of the 
 violet ; and by another lens he collected the 
 other half of the spectrum, comprehending 
 the red. The latter formed the focus of a 
 white light, so brilliant, that the eye could 
 not endure it ; yet in two hours it produced 
 no sensible change on muriate of silver. On 
 the contrary, the focus of the other half of 
 the spectrum, whose light and heat were far 
 less intense, blackened the muriate in ten 
 minutes. The investigations of Delaroche 
 enable us, in some measure, to reduce these 
 dissimilar effects of light to a common prin- 
 ciple. See Caloric. 
 
 In Mr Brando’s late Bakerian lecture on 
 the composition and analysis of coal and oil 
 gases, this ingenious chemist shews, that the 
 light produced by these, or by olefiant gas, 
 even when concentrated so as to produce a 
 sensible degree of heat, occasioned no change 
 on the colour of muriate of silver, nor on a 
 mixture of chlorine and hydrogen ; while 
 the light emitted by electrized charcoal, 
 speedily affects the muriate, causes these 
 gases to unite rapidly, and sometimes with 
 explosion. The concentrated light of the 
 moon, like that of the gases, produced no 
 
LIG 
 
 LIG 
 
 change. ITe concludes with stating, that he 
 found the photometer of Mr Leslie ineffec- 
 tual. lie employed one filled with the va- 
 pour of ether (renewable from a column of 
 that fluid), which he found to be more deli- 
 cate. 
 
 The general facts, says Sir II. Davy, of 
 the refraction and effects of the solar beam, 
 offer an analogy to the agencies of electricity. 
 In the voltaic circuit, the maximum of heat 
 seems to be at the positive pole, where the 
 power of combining with oxygen is given to 
 bodies, and the agency of rendering bodies 
 inflammable is exerted at the opposite sur- 
 face ; and similar chemical effects are pro- 
 duced by negative electricity, and by the 
 most refrangible rays of the solar beam. In 
 general, in nature, the effects of the solar 
 rays are very compounded. Healthy vege- 
 tation depends upon the presence of the so- 
 lar beams, or of light ; and whilst the heat 
 gives fluidity and mobility to the vegetable 
 juices, chemical effects likewise are occa- 
 sioned, oxygen is separated from them, and 
 inflammable compounds formed. Plants de- 
 prived of light become white, and contain an 
 excess of saccharine and aqueous particles ; 
 and flowers owe the variety of their hues to 
 the influence of the solar beams. Even ani- 
 mals require the presence of the rays of the 
 sun, and their colours seem materially to de- 
 pend upon the chemical influence of these 
 rays; a comparison between the polar and 
 tropical animals, and between the parts of 
 their bodies exposed, and those not exposed 
 to light, shews the correctness of this opi- 
 nion. 
 
 III. Polarization of Light. 
 
 This new branch of optical science, sprung 
 from the ingenuity of Malus. It has been 
 since cultivated chiefly by M. Iliot in Prance, 
 and by Dr Brewster in this kingdom. I 
 am happy to observe, that Mr Herschel has 
 lately entered the lists under very favourable 
 auspices. 
 
 If a solar ray fall on the anterior surface 
 of an unsilvered mirror plate, making an 
 angle with it of 35° 25', the ray will be re- 
 flected in a right line, so that the angle of 
 reflection will ho equal to the angle of inci- 
 dence. In any point of its reflected path, 
 receive it on another plane of similar glass, 
 it will suffer in general a second partial re- 
 flection. But this reflection will vanish, or 
 become null, if the second plate of glass 
 form an angle of 35° 25' with the first re- 
 flected ray, and at the same time be turned, 
 so that the second reflection is made in a 
 plane perpendicular to that in which the first 
 reflection takes place. Por the sake of illus- 
 tration, suppose that the plane of incidence 
 of the ray on the first glass, coincides with 
 the plane of the meridian, and that the re- 
 flected rav is vertical. Then, if we make 
 
 the second inclined plate revolve, it will turn 
 
 26 
 
 around the reflected ray, forming always i 
 with it the same angle ; and the plane ir* 
 which the second reflection takes place, will 
 necessarily be directed towards the different 
 points of the horizon, in different azimuths., ( 
 This being arranged, the following pheno-<| J 
 mena will be observed. 
 
 When the second plane of reflection is< 
 directed in the meridian, and consequently 
 coincides with the first, the intensity of theMi 
 light reflected by the second glass is at itsn 
 maximum. 
 
 In proportion as the second plane, in it*i 
 revolution, deviates from its parallelism with 
 the first, the intensity of the reflected light 
 will diminish. 
 
 Finally, when the second plane of reflec- 
 tion is placed in the prime vertical, that is 
 east and west, and consequently perpendicu- 
 lar to the first, the intensity of the reflection 
 of light is absolutely null on the two sur- 
 faces of the second glass, and the ray is en- 
 tirely transmitted. 
 
 Preserving the second plate at the same 
 inclination to the horizon, if we continue to 
 make it revolve beyond the quadrant now 
 described, the phenomena will be reproduced 
 in the inverse order; that is, the intensity of' 
 the light will increase, precisely as it dimi- 
 nished, and it wflll become equal, at equal 
 distances from the east and west. Hence, 
 when the second plane of reflection returns 
 once more to the meridian, a second maxi- 
 mum of intensity equal to the first recurs. 
 
 From these experiments it appears, that 
 the ray reflected by the first glass, is not re- 
 flected by the second, under this incidence, 
 when it is presented to it by its east and w r est 
 sides ; but that it is reflected, at least in part, 
 when it is presented to the glass by any two 
 others of its opposite sides. Now if we re- 
 gard the ray as an infinitely rapid succession 
 of a series of luminous particles, the faces of 
 the ray are merely the successive faces of 
 these particles. We must hence conclude, 
 that these particles possess faces endowed 
 with different physical properties, and that 
 in the present circumstance, the first reflec- 
 tion has turned towards the same sides of 
 space, similar faces, or faces equally endowed 
 at least with the property under considera- 
 tion. It is this arrangement of its molecules 
 w’hich Malus named the polarization of light, 
 assimilating the effect of the first glass to 
 that of a magnetic bar, which would turn a 
 series of magnetic needles, all in the same 
 direction. 
 
 Hitherto w r e have supposed that the ray, 
 whether incident or reflected, formed with 
 the tw r o mirror, plates an angle of 55° 25' ; 
 for it is only under this angle that the phe- 
 nomenon is complete. Without changing 
 the inclination of the ray to the first plate, 
 if we varv never so little the inclination ci 
 the second, the intensity of the reflected light 
 
LIG 
 
 LIG 
 
 no longer null in any azimuth, but it be- 
 comes the feeblest possible in the prime ver- 
 tical, in which it was formerly null. 
 
 Similar phenomena may be produced by 
 substituting for the mirror glasses, polished 
 plates, formed for the greater part of trans- 
 parent bodies. The two planes of reflection 
 must always remain rectangular, but they 
 must be presented to the luminous ray, at 
 different angles, according to their nature. 
 Generally, all polished surfaces have the 
 property of thus polarizing, more or less 
 completely, the light which they reflect un- 
 der certain incidences ; but there is for each 
 of them a particular incidence, in which the 
 polarization it impresses is most complete, 
 and for a great many, it amounts to the 
 whole of the reflected light. 
 
 When a ray of light has received polari- 
 zation in a certain direction, by the processes 
 now described, it carries with it this property 
 into space, preserving it without perceptible 
 alteration, when we make it traverse perpen- 
 dicularly a considerable mass of air, water, 
 or any substance possessed of single refrac- 
 tion. But the substances which exercise 
 double refraction, in general alter the polari- 
 zation of the ray, and apparently in a sud- 
 den manner, and communicate to it a new 
 polarization of the same nature, but in ano- 
 ther direction. It is only in certain direc- 
 tions of the principal section, that the ray 
 can escape this disturbing force. The fol- 
 lowing may be regarded as the most general 
 view of this subject. 
 
 When the particles of light pass through a 
 crystallized body, endowed with double re- 
 fraction, they experience different move- 
 ments round their centre of gravity, which 
 depend on the nature of the forces which the 
 particles of the crystal exercise on them. 
 Sometimes the effect of these forces is limit- 
 ed to the above polarization , or to the ar- 
 ranging all the particles of one ray, parallel 
 to each other, so that their homologous faces 
 are turned towards the same parts of space. 
 W hen this disposition occurs, the luminous 
 molecules preserve it, in the whole extent of 
 the crystal, and experience no more move- 
 ment around their centre of gravity. But 
 there exists other cases, in which the mole- 
 cules that traverse the crystal are not fixed 
 in any constant position. During the time 
 of their passage, they oscillate round their 
 centre of gravity, with velocities, and accord- 
 ing to periods, which may he calculated. 
 Lastly, they sometimes revolve round their 
 own axes, with an uninterrupted movement 
 of rotation. The former is called fixed po- 
 larization, the latter moveable. 
 
 In the Phil. Trans, for 1813, we have the 
 first of a scries of very interesting papers on 
 polarized light by Dr Brewster. This relates 
 chiefly to some curious properties of agate. 
 J fie plate of agate which he employed, was 
 
 bounded by parallel faces, was about the fif- 
 teenth of an inch thick, and was cut into a 
 plane, perpendicular to the laminae, of which 
 it was composed. When the image of a 
 taper reflected from water at an angle of 
 52° 45', so as to acquire the property dis- 
 covered by Mains, was viewed through the 
 plate of agate, so as to have its laminae pa- 
 rallel to the plane of reflection, the flame 
 appeared perfectly distinct, but when the 
 agate was turned round, so that its laminae 
 became perpendicular to the plane of reflec- 
 tion, the light which formed the image of 
 the taper suffered total reflection, and not 
 one ray of it penetrated the agate. If a ray 
 of light incident upon one plate of agate is 
 received, after transmission, upon another 
 plate of the same substance, having its lami- 
 nae parallel to those of the former, the light 
 will find an easy passage through the second 
 plate ; but if the second plate has its lamina? 
 perpendicular to those of the first, the light 
 will be wholly reflected, and the luminous 
 object will cease to be visible. 
 
 In a second important communication in 
 1814, on the affections of light transmitted 
 through crystallized bodies, after suggesting 
 that the cultivation of this department of phy- 
 sics may enable us to explain the forms and 
 structure of crystallized bodies, a prediction 
 which he himself has since happily fulfilled, 
 the Doctor states, that if the light polarized 
 by agate, is incident at a particular angle 
 upon any transparent body, so that the plane 
 of reflection is perpendicular to the laminae 
 of the agate, it will experience a total refrac- 
 tion ; if it is transmitted through another 
 plate of agate, having its laminae at right 
 angles to those of the plate by which the 
 light is polarized, it will suffer total refec- 
 tion ; and if it is examined by a prism of 
 Iceland crystal, turned round in the hand of 
 the observer, it will vanish and reappear in 
 every quadrant of its circular motion. The 
 pencil of rays to which this remarkable pro- 
 perty is communicated, is surrounded by a 
 large mass of nebulous light, which extends 
 about 7° SO' in length, and 1° T in breadth 
 on each side of the bright image. This ne- 
 bulous light never vanished with the bright 
 image which it enclosed, but was obviously 
 affected with its different. changes, increasing 
 in magnitude as the bright image diminished, 
 and diminishing as the bright image regain- 
 ed its lustre. Light polarized by the agate, 
 or by any other means, is depolarized, or 
 partly restored to its original state, by being 
 transmitted in a particular direction through 
 a plate of mica, or any other crystallized 
 body. 
 
 IV. Of the Production of Light. 
 
 Some philosophers refer the origin of all 
 luminous phenomena to the sun, whose 
 beams are supposed to penetrate, and com- 
 bine with, the different forms of terrestrial 
 
LIG 
 
 LIG 
 
 matter. But we learn from Scripture, that 
 light pre-existed before this luminary, and 
 that its subsequent condensation in his orb, 
 was a particular act of Almighty Power. 
 The phosphorescence of minerals, buried 
 since the origin of things in the bowels of 
 the earth, coincides strictly with the Mosaic 
 account of the creation. We shall therefore 
 regard light, the first-born element of Chaos, 
 as an independent essence, universally dis- 
 tributed through the mineral, vegetable, and 
 animal world, capable of being disengaged 
 from its latent state by various natural and 
 artificial operations. These are 
 
 1. Friction. 
 
 To this head, belong electrical light, and 
 that evolved from the attrition of pieces of 
 quartz, even under water. 
 
 2. Condensation and expansion. If at- 
 mospheric air or oxygen be suddenly com- 
 pressed in a glass syringe, or if a glass ball, 
 filled with the latter, be suddenly broke in 
 vacuo , a fiash of light is instantly perceived. 
 
 3. Heat. If air which has been heated 
 up to 900° of Fahrenheit, and which is in 
 itself obscure, be made to fall on pieces 
 of metal, earth, Sec. it will speedily com- 
 municate to them the power of radiating 
 
 light. The brilliant flame exhibited in the 
 
 burning of charcoal and phosphorus, is shewn 
 
 in the article Combustion, to be merely the 
 
 ignition of the solid particles of these bodies. 
 
 At a certain elevation of temperature, about 
 
 800° Fahr. all solid bodies begin to give 
 
 out light. The same effect is produced in 
 
 vacuo by transmitting voltaic electricity 
 
 through a metallic wire. To this section, 
 
 we must also refer the phosphorescence of 
 
 minerals. This curious phenomenon seems 
 
 to have been first described bv Benvenuto 
 
 ¥ 
 
 Cellini, in his Treatise on Jewellery, pub- 
 lished near the beginning of the 16th cen- 
 tury. In the year 1663, Mr Boyle observed, 
 that diamond, when slightly heated, rubbed, 
 or compressed, emitted a light almost equal 
 to that of the glow-worm. 
 
 The most complete account which we 
 have of mineral phosphorescence, is that re- 
 cently given by Dr Brewster in the first vo- 
 lume of the Edinburgh Phil. Journal. His 
 method of examination was ingenious and 
 accurate. He never reduced the body td 
 powder, but placed a fragment of it upon a 
 thick mass of hot iron, or, in delicate ex- 
 periments, introduced it into the bottom of a 
 pistol barrel, heated a little below redness. 
 
 The following table presents his results : 
 
 Names of the Minerals. 
 
 Colour of the Minerals. 
 
 Colour and Intensity of the 
 Light. 
 
 Fluor spar, 
 
 Pink, 
 
 Green, 
 
 • 
 
 Purple, 
 
 Bluish, 
 
 
 Bluish-white, 
 
 Blue, 
 
 Compact fluor, 
 
 Yellowish, 
 
 Fine green, 
 
 Sandy fluor, 
 
 White, 
 
 White sparks, 
 
 Calcareous spar, 
 
 Yellow, 
 
 Yellow, 
 
 Limestone from north of Ireland, 
 
 Transparent, 
 
 Yellowish, 
 Yellowish- red, 
 
 Phosphate of lime, 
 
 Pink, 
 
 Yellow, 
 
 Arragonite, 
 
 Dirty white, 
 
 Reddish- yellow, 
 
 Carbonate of barytes, 
 
 Whitish, 
 
 Pale white, 
 
 Harmotome, 
 
 Colourless, 
 
 Reddish-yellow, 
 
 Dipyre, 
 
 White, 
 
 Specks of light, 
 
 Grammatite from Glentilt, 
 
 
 Yellow, 
 
 Cornwall, 
 
 ■ — 
 
 Bluish, 
 
 Topaz, Aberdeenshire, 
 
 Blue, 
 
 Bluish, 
 
 , Brazilian, 
 
 Yellow, 
 
 Faint yellowish, 
 
 , New Holland, 
 
 White, 
 
 Bluish, 
 
 Rubellite, 
 
 Reddish, 
 
 Scarlet, 
 
 Sulphate of lime, 
 
 Yellowish, 
 
 Faint light, 
 
 of barytes. 
 
 Yellow, 
 
 Pale light, 
 
 Slate colour, 
 
 Pale light, 
 
 strontites, 
 
 Bluish, 
 
 A fragment shone pretty 
 
 lead, 
 
 Transparent, 
 
 bright, 
 
 Faint and by fits, 
 
 Anhydrite, 
 
 Reddish, 
 
 Faint light, 
 
 Sodalite, 
 
 Dark green, 
 
 Pretty bright, 
 
 Bitter spar, 
 
 Yellowish, 
 
 Faint white, 
 
 lied silver ore, 
 
 Red, 
 
 Pretty bright, but flitting, 
 
 Barystrontianite, 
 
 White, 
 
 Faint, 
 
 Arseniatc of lead, 
 
 Yellowish, 
 
 Bright white, 
 
LIG 
 
 LIG 
 
 Names of the Minerals. 
 
 Sphene, 
 
 Tremolite, 
 
 Mica, 
 
 from Waygatz, 
 
 Titanium sand, 
 
 Hornstone, 
 
 Table spar, Dognatska, 
 Lapis lazuli, 
 
 Spodumene, 
 
 Titanite, 
 
 Cyanite, 
 
 Calamine, 
 
 Augite, 
 
 Petalite, 
 
 Abestus, rigid, 
 
 Datholite, 
 
 Corundum, 
 
 Anatase, 
 
 Tungstate of lime, 
 
 Quartz, 
 
 Amethyst, 
 
 Obsidian, 
 
 Mesotype from Auvergne, 
 Glassy actinolite, 
 
 Ruby silver, 
 
 Muriate of silver, 
 Carbonate of copper, 
 Green telesie, 
 
 
 Colour of the Minerals. 
 
 Yellow, 
 
 Whitish, 
 
 Greenish, 
 
 Black, 
 
 Brown, 
 
 Black, 
 
 Grey, 
 
 Whitish, 
 
 Blue, 
 
 Greenish, 
 
 Reddish, 
 
 Yellowish-white, 
 
 Brown, 
 
 Green, 
 
 Reddish tinge, 
 
 Colour and Intensity of the 
 Light. 
 
 Transparent, 
 
 Brown, 
 
 Dark, 
 
 Yellowish-white, 
 
 The phosphorescence of 
 these nine minerals was 
 observed in the pistol bar- 
 rel. 
 
 Bright white, 
 Reddish-yellow, 
 
 Whitish, 
 
 W r hite specks, 
 
 Pretty bright, 
 
 Feeble speck3, 
 
 Yellowish, 
 
 Yellowish, 
 
 Faint, 
 
 Faint, 
 
 Extremely faint, 
 
 Bluish, 
 
 Faint, 
 
 Pretty bright, 
 
 Blue and very bright, 
 Pretty bright, 
 
 Bright, 
 
 Bright, 
 
 Reddish- yellow', 
 
 Brilt. like a burning coal, 
 Very faint, 
 
 Faint, 
 
 Pretty bright; dirty blue, 
 Very faint, 
 
 Little specks, 
 
 Rather bright, 
 
 Blue, 
 
 Verv faint, 
 
 y 7 
 
 Pale blue, & pretty bright. 
 
 The phosphorescence of anatase is entire- 
 ly different from that of the other minerals. 
 It appears suddenly like a flame, and is soon 
 over. Dr Brewster found, in opposition to 
 what Mr Wedgwood had stated, that ex- 
 posure of green fluor spar to the heat of a 
 common fire in a crucible for half an hour, 
 entirely deprived it of phosphorescence. 
 Though he placed one fragment for several 
 days in the beams of a summer sun, and even 
 exposed it to the bright light near the focus 
 of a burning glass, he could not succeed in 
 obtaining from it the slightest indication of 
 phosphorescence. The light emitted in 
 combustion belongs to the same head. The 
 phosphoric light of minerals has the same 
 properties as the direct light of the sun, ac- 
 cording to Dr Brewster. 
 
 4 . Light emitted from bodies in conse- 
 quence of the action of extraneous light. 
 To this section we refer solar phosphori. 
 The most powerful of these is the artificial 
 compound of Canton. If w’e mix three 
 parts of calcined oyster shells in powder, 
 with one of flowers of sulphur, and ramming 
 the mixture into a crucible, ignite it for half 
 an hour, we shall find, that the bright parts 
 will, on exposure to the sunbeam, or to the 
 common day-light, or to an electrical explo- 
 sion, acquire the faculty of shining in the dark, 
 so as to illuminate the dial of a watch, and 
 make its figures legible. It will, indeed, 
 
 after a while, cease to shine ; but if we keep 
 the powder in a well corked phial, a new 
 exposure to the sunbeam will restore the 
 luminescence. Oyster shells, stratified with 
 sulphur, in a crucible, and ignited, yield a 
 more powerful phosphorescent substance than 
 the powder. It also must he kept in a close 
 phial. When the electric discharge is trans- 
 mitted along the surfaces of certain bodies, 
 or a little above them, a somewhat durable 
 phosphorescence is occasioned, which pro- 
 bably belongs to this division. 
 
 Sulphate of barytes gives a bright green light, 
 
 Carbonate 
 Acetate of potash, 
 Succinic acid, 
 Loaf sugar, 
 Selenite, 
 Rock-crystal, 
 Quartz, 
 
 Borax, 
 
 Boracic acid, 
 
 Do. less brilliant, 
 Brilliant green light, 
 Do. more durable, 
 Do. 
 
 Do. but transient, 
 Light red, and then white, 
 
 talogue 
 
 Dull white light, 
 Faint green light, 
 Bright green light. 
 Mr Skrimshire has given an extensive ca- 
 of such substances in Nicholson’s 
 Journal, 8vo. vols. 15, 16, and 19. He 
 shews that Canton’s pyrophorus yields more 
 light by this treatment than any other body ; 
 but that almost every native mineral, except 
 metallic ores and metals, becomes more or 
 less luminous after the electric explosion. A 
 slate from Colly Weston, Northamptonshire, 
 which effervesced with acids, gives a beauti- 
 
LIG 
 
 LIM 
 
 fill effect. M hen the explosion of a jar is 
 taken above the centre of a piece some inches 
 square, not only the part above the discharg- 
 ing rods is luminous, but the surface of the 
 plate appears bespangled, with very minute 
 brilliant points to some distance from its 
 centre ; and when the points of the dis- 
 chargers rest upon the surface of the slate, 
 these minute spangles are detached and scat- 
 tered about the table in a luminous state. 
 
 .5. Light emitted during chemical changes, 
 independent of heat, or in which no percep- 
 tible heat is developed. The substances from 
 which such light is emitted, are principally 
 the following : — 
 
 Marine animals, both in a living state and 
 when deprived of life. As instances of the 
 first may be mentioned, the shell-fish called 
 pholas , the medusa phosphorea } and various 
 other mollusca. When deprived oflife, ma- 
 rine fishes, in general, seem to abound with 
 this kind of light. The flesh of quadrupeds 
 also evolves light. In the class of insects, 
 are many which emit light very copiously, 
 particularly several species o fjulgora, or lan- 
 tern-fly; and of lampyris or glow-worm; 
 also the scolopendra electnca , and a species 
 of crab called cancer Julgens. Rotten wood 
 
 is well known to evolve light copiously, as 
 well as peat-earth. 
 
 Dr Ilulme, in an elaborate dissertation on 
 this light, published in the Phil. Trans, for 
 1790, establishes the following important 
 propositions : — 
 
 1. The quantity of light emitted by dead 
 animal substances, is not in proportion to 
 the degree of putrefaction in them, as is 
 commonly supposed ; but, on the contrary, 
 the greater the putrescence, the less light is 
 evolved. It would seem, that this element, 
 endowed with pre-eminent elasticity, is the 
 first to escape from the condensed state of 
 combination in which it had been imprison- 
 ed by the powers of life ; and is followed, 
 after some time, by the relatively less clastic 
 gases, whose evolution constitutes putrefac- 
 tion. 
 
 2. This light is a constituent chemical 
 principle of some bodies, particularly of ma- 
 rine fishes, from which it may be separated 
 by a peculiar process, retained and rendered 
 permanent for some time. A solution of 1 
 part of sulphate of magnesia, in 8 of water, 
 is the most convenient menstruum for ex- 
 tracting, retaining and increasing, the bril- 
 liancy of this light. Sulphate and muriate 
 of soda, also answer in a proper state of di- 
 lution with water. When any of the saline 
 solutions is too concentrated, the light dis- 
 appears, but instantly bursts forth again 
 from absolute darkness, by dilution with wa- 
 ter. I have frequently made this curious ex- 
 periment with the light procured from whit- 
 jng. Common water, lime-water, fermented 
 
 liquors, acids even very dilute, alkaline leys, 
 and many other bodies, permanently extin- 
 guish this spontaneous light. Boiling water 
 destroys it, but congelation merely suspends 
 its exhibition; for it reappears on liquefac- 
 tion. A gentle heat increases the vividness 
 of the phenomenon, but lessens its duration. 
 
 We shall conclude the subject of light 
 with the following important practical fact 
 and practical problem. 
 
 1. Count Rumford has shewn that the 
 quantity of light emitted by a given portion 
 of inflammable matter in combustion, is pro- 
 portional in some high ratio to the elevation 
 of temperature ; and that a lamp having 
 many wicks very near each other, so as mu- 
 tually to increase their heat, burns with in- 
 finitely more brilliancy than the Argand’s 
 lamps in common use. 
 
 2. To measure the proportional intensities 
 of two or more lights. Tlace them a few 
 inches asunder, and at the distance of a few 
 feet or yards from a screen of white paper, 
 or a white wall. On holding a small card, 
 near the wall, two shadows will be projected 
 on it, the darker one by the interception of 
 the brighter light, and the lighter shadow 
 by the interception of the duller light. 
 Bring the fainter light nearer to the card, 
 or remove the brighter one further from it, 
 till both shadows acquire the same intensity; 
 which the eye can judge of with great preci- 
 sion, particularly from the conterminous 
 shadows at the angles. Measure now the 
 distances of the two lights from the wall or 
 screen, square them, and you have the ratio 
 of illumination. Thus if an Argand flame, 
 and a candle, stand at the distances of 10 
 feet and 4 feet, respectively, when their sha- 
 dows are equally deep, we have 10 2 and 4 2 , 
 or 100 and 16, or 6-q; and 1, for their rela- 
 tive quantities of light.* 
 
 * Lilalite. The mineral Lepidolite.* 
 
 * Lime. The oxide of calcium, one 
 of the primitive earths. This subject has 
 been already treated of under Calcium. W e 
 shall add here, that in preparing the bleach- 
 ing powder, calcined magnesian limestone 
 would be an excellent substitute for common 
 lime ; and it may be had abundantly from 
 many districts both of England and Ireland. 
 Scotland seems to possess little of it. See 
 Dolomite. 
 
 The most important applications of lime are 
 to agriculture and building ; on which sub- 
 jects Sir H. Davy has given some excellent 
 observations. 
 
 Quicklime in its pure state, whether in 
 powder, or dissolved in water, is injurious to 
 plants. Grass is killed by watering it with 
 lime water. But lime in its state ot combi- 
 nation with carbonic acid, is a useful ingre- 
 dient in soils. Calcareous earth is found in 
 the ashes of the greater number of plants j 
 
LIM 
 
 LIM 
 
 and exposed to the air, lime cannot long 
 continue caustic, but soon becomes united 
 to carbonic acid. 
 
 When lime, whether freshly burnt or 
 slacked, is mixed with any moist fibrous 
 vegetable matter, there is a strong action 
 between the lime and the vegetable matter, 
 and they form a kind of compost together, 
 of which a part is usually soluble in water. 
 
 By this kind of operation, lime renders 
 matter which was before comparatively in- 
 ert, nutritive; and as charcoal and oxygen 
 abound in all vegetable matters, it becomes 
 at the same time converted into carbonate of 
 lime. 
 
 Mild lime, powdered limestone, marles, or 
 chalks, have no action of this kind upon 
 vegetable matter : by their action they pre- 
 vent the too rapid decomposition of sub- 
 stances already dissolved ; but they have no 
 tendency to form soluble matters. 
 
 It is obvious from these circumstances, 
 that the operation of quicklime, and marie 
 or chalk, depends upon principles altogether 
 different. Quicklime, in the act of becom- 
 ing mild, prepares soluble out of insoluble 
 matter. 
 
 It is upon this circumstance that the ope- 
 ration of lime in the preparation for wheat 
 crops depends ; and its efficacy in fertilizing 
 peats, and in bringing into a state of culti- 
 vation all soils abounding in hard roots or 
 dry fibres, or inert vegetable matter. 
 
 The solution of the question, whether 
 quicklime ought to be applied to a soil, de- 
 pends upon the quantity of inert vegetable 
 matter that it contains. The solution of the 
 question, whether marie, mild lime, or pow- 
 dered limestone, ought to be applied, de- 
 pends upon the quantity of calcareous mat- 
 ter already in the soil. All soils are improv- 
 ed by mild lime, and ultimately by quick- 
 lime, which do not effervesce with acids; 
 and sands more than clays. 
 
 When a soil, deficient in calcareous mat- 
 ter, contains much soluble vegetable manure, 
 the application of quicklime should always 
 be avoided, as it either tends to decompose 
 the soluble matters by uniting to their car- 
 bon and oxygen so as to become mild lime, 
 or it combines with the soluble matters, and 
 forms compounds having less attraction for 
 vvatei than the pure vegetable substance. 
 
 I he case is the same with respect to most 
 animal manures ; but the operation of the 
 lime is different in different cases, and de- 
 pends upon the nature of the animal matter. 
 Time forms a kind of insoluble soap with 
 oily matters, and then gradually decomposes 
 them by separating from them oxygen and 
 carbon. It combines likewise with the ani- 
 mal acids, and probably assists their decom- 
 position by abstracting carbonaceous matter 
 Tom them combined with oxvgen ; and 
 consequently it must render them less nutri- 
 
 tive. It tends to diminish likewise the nu- 
 tritive powers of albumen from the same 
 causes ; and always destroys, to a certain 
 extent, the efficacy of animal manures, either 
 by combining with certain of their elements, 
 or by giving to them new arrangements. 
 Lime should never be applied with animal 
 manures, unless they are too rich, or for the 
 purpose of preventing noxious effluvia. It 
 is injurious when mixed with any common 
 dung, and tends to render the extractive 
 matter insoluble. 
 
 In those cases in which fermentation is 
 useful to produce nutriment from vegetable 
 substances, lime is always efficacious, as 
 with tanners’ bark. 
 
 The subject of the application of the mag- 
 nesian limestone is one of great interest. 
 
 Magnesia has a much weaker attraction 
 for carbonic acid than lime, and will remain 
 in (lie state of caustic or calcined magnesia 
 for many months, though exposed to the air. 
 And as long as any caustic lime remains, 
 the magnesia cannot be combined with car- 
 bonic acid, for lime instantly attracts carbonic 
 acid from magnesia. 
 
 When a magnesian limestone is burnt, the 
 magnesia is deprived of carbonic acid much 
 sooner than the lime ; and if there is not 
 much vegetable or animal matter in the soil 
 to supply, by its decomposition, carbonic 
 acid, the magnesia will remain for a long 
 while in the caustic state ; and in this state 
 acts as a poison to certain vegetables. And 
 that more magnesian lime may be used upon 
 rich soils, seems to be owing to the circum- 
 stance, that the decomposition of the manure 
 in them supplies carbonic acid. But mag- 
 nesia in its mild state, i. e. fully combined 
 with carbonic acid, seems to be always an 
 useful constituent of soils. 
 
 The Lizard Downs which contain magne- 
 sian earth, bear a short and green grass, 
 which feeds sheep producing excellent mut- 
 ton ; and the cultivated parts are amongst the 
 best corn lands in the county of Cornwall. 
 
 It is obvious, from what has been said, 
 that lime from the magnesian limestone may 
 be applied in large quantities to peats ; and 
 that where lands have been injured by the 
 application of too large a quantity of magne- 
 sian lime, peat will be a proper and efficient 
 remedy. 
 
 There are two modes in which lime acts 
 as a cement : in its combination with water, 
 and in its combination with carbonic acid. 
 
 Vv hen quicklime is rapidly made into a 
 paste with water, it soon loses its softness, 
 and the water and the lime form together a 
 solid coherent mass, which consists, of 1 part 
 of water to 3 parts of lime. When hydrate 
 of lime, w hilst it is consolidating, is mixed 
 with red oxide of iron, alumina, or silica, 
 the mixture becomes harder, and more colie- 
 i ent than when lime alone is used; and it 
 
LIM 
 
 LIM 
 
 appears that this is owing to a certain de- 
 gree of chemical attraction between hydrate 
 of lime and these bodies ; and they render 
 it less liable to decompose by the action of 
 the carbonic acid in the air, and less soluble 
 in water. 
 
 I he basis of all cements that are used for 
 works which are to be covered with water, 
 must be formed from hydrate of lime ; and 
 the lime made from impure limestones an- 
 swers this purpose very well. Puzzolana is 
 composed principally of silica, alumina, and 
 oxide of iron ; and it is used mixed with 
 lime to form cements intended to be employ- 
 ed under water. Mr Smeaton, in the con- 
 struction of the Eddystone light-house, used 
 a cement composed of equal parts by weight 
 of slacked lime and puzzolana. Puzzolana 
 is a decomposed lava. Tarras, which was 
 formerly imported in considerable quantities 
 from Holland, is a mere decomposed basalt: 
 two parts of slacked lime and one part of 
 tarras form the principal part of the mor- 
 tar used in the great dykes of Holland. 
 Substances which will answer all the ends of 
 puzzolana and tarras are abundant in the 
 British islands. An excellent red tarras 
 may be procured in any quantities from the 
 Giants’ Causeway, in the north of Ireland; 
 and decomposing basalt is abundant in many 
 parts of Scotland, and in the northern dis- 
 tricts of England in which coal is found. 
 
 Parker’s cement, and cements of the same 
 kind made at the alum works of Lord Dun- 
 das and Lord Mulerave, are mixtures of cal- 
 cined ferruginous, silicious, and aluminous 
 matter, with hydrate of lime. 
 
 The cements which act by combining 
 with carbonic acid, or the common mortars, 
 are made by mixing together slacked lime 
 and sand. These mortars, at first solidify 
 as hydrates, and are slowly converted into 
 carbonate of lime by the action of the car- 
 bonic acid of the air. Mr Tennant found 
 that a mortar of this kind, in three years 
 and a quarter, had regained 65 per cent of 
 the quantity of carbonic acid gas, which con- 
 stitutes the definite proportion in carbonate 
 of lime. The rubbish of mortar from houses 
 owes its power to benefit lands principally 
 to the carbonate of lime it contains, and the 
 6and in it ; and its state of cohesion renders 
 it particularly fitted to improve clayey soils. 
 
 The hardness of the mortar in very old 
 buildings depends upon the perfect conver- 
 sion of all its parts into carbonate of lime. 
 The purest limestones are the best adapted 
 for making this kind of mortar ; the magne- 
 sian limestones make excellent water ce- 
 ments, but act with too little energy upon 
 carbonic acid gas to make good common 
 mortar. 
 
 The Romans, according to Pliny, made 
 their best mortar a year before it was used ; 
 
 so that it was partially combined with car- 
 bonic acid gas before it was employed. 
 
 In burning lime there are some particular 
 precautions required for the different kinds 
 of limestones. In general, one bushel of 
 coal is sufficient to make four or five bushels 
 of lime. The magnesian limestone requires 
 less fuel than the common limestone. In 
 all cases in which a limestone containing 
 much aluminous or siliceous earth is burnt, 
 great care should be taken to prevent the fire 
 from becoming too intense; for such lime 
 easily vitrifies, in consequence of the affinity 
 of lime for silica and alumina. And as in 
 some places there are no other limestones 
 than such as contain other earths, it is im- 
 portant to attend to this circumstance. A 
 moderately good lime may be made at a low 
 red-heat ; but it will melt into a glass at a 
 white- heat. In limekilns for burning such 
 lime, there should be always a damper. 
 
 In generalj when limestones are not mag- 
 nesian, their purity will be indicated by their 
 loss of weight in burning; the more they 
 lose, the larger is the quantity of calcareous 
 matter they contain. The magnesian lime- 
 stones contain more carbonic acid than the 
 common limestones ; and all of them lose 
 more than half their weight by calcination. 
 
 The most important compounds of lime, 
 are treated of under the different acids and 
 combustibles. * 
 
 * Limestone. A genus of minerals, which 
 Professor Jameson divides into the four fol- 
 lowing species: 1. Rhomb-spar ; 2. Dolo- 
 mite ; 3. Limestone ; and, 4. Arragonite. 
 We shall consider the third species here. 
 The same excellent mineralogist divides 
 limestone into twelve sub-species. 
 
 1. Foliated limestone ; of which there are 
 tw o kinds, calcareous spar, and foliated gra- 
 nular limestone. The first will he found in 
 its alphabetical place in the Dictionary. 
 
 Granular foliated limestone. Colour white, 
 of various shades ; sometimes it is spotted. 
 Massive, and in distinct angulo- granular con- 
 cretions. Lustre glistening, between pearly 
 and vitreous. Fracture foliated. 1 ranslu- 
 cent. Hard as calcareous spar. Brittle. 
 Sp. gr. Carrara marble 2.717. It generally 
 phosphoresces when pounded, or when thrown 
 on glowing coals. Infusible. Effervesces 
 •with acids. It is a pure carbonate of lime. 
 It occurs in beds in granite, gneiss. &c. and 
 rarely in secondary rocks. It is found in all 
 the great ranges of primitive rocks in Europe. 
 Parian marble, Pentelic marble, the Marmo 
 Greco, the w hite marble of Luni, of Carrara, 
 and of Mount Ilymettus, the translucent 
 white marble of statuaries, and flexible white 
 marble, are the chief of the white marbles 
 which the ancients used for sculpture ami 
 architecture. 1 fie red antique marble, Rosso 
 antico of the Italians, and Egyptian of the 
 
LIM 
 
 LIM 
 
 ancients ; the Verde antico, an indeterminate 
 mixture of white marble and green serpen- 
 tine ; yellow antique marble ; the antique 
 Cipolin marble, marked with green-coloured 
 zones, caused by talc or chlorite ; and Afri- 
 can breccia marble, are the principal colour- 
 ed marbles of the ancients. The Scottish 
 marbles are, the red and white Tiree, the 
 former of which contains hornblende, sahlite, 
 mica, and green earth; the Iona marble, 
 harder than most others, consisting of lime- 
 stone and tremolite, or occasionally a dolo- 
 mite ; the Skye marble ; the Assynt in Su- 
 therland, introduced into commerce by Mr 
 Joplin of Gateshead. It is white and grey, 
 of various shades. The Glentilt marble ; the 
 Balachulish ; the Boyne ; the Blairgowrie ; 
 and the Glenavon. Hitherto but few mar- 
 bles of granular foliated limestone have been 
 quarried in England. The Mona marble is 
 not unlike Verde antico . The black marbles 
 of Ireland, now so generally used by archi- 
 tects, are Lucullites. The Torecn in the 
 county of Waterford, is a fine variegated 
 sort ; and a grey marble beautifully clouded 
 with white, has been found near Kilcrump, 
 Sn the same county. At Loughlougher in 
 Tipperary, a fine purple marble is found. 
 The county of Kerry affords several varie- 
 gated marbles. Of the continental marbles 
 a good account is given by Professor Jame- 
 son, Mineralogy , vol. ii. p.502. 
 
 2d Sub-species. Compact limestone ; of 
 which there are three kinds, common com- 
 pact limestone, blue Vesuvian limestone, and 
 roestone. 
 
 Common compact limestone has usually 
 a grey colour, with coloured delineations. 
 Massive, corroded, and in various extraneous 
 shapes. Dull. Fracture fine splintery. Trans- 
 lucent on the edges. Softer than the pre- 
 ceding sub-species. Easily frangible. Streak 
 greyish-white. Sp. gr. 2.6 to 2.7. It effer- 
 vesces with acids, and burns into quicklime. 
 It is a carbonate of lime, with variable and 
 generally minute proportions of silica, alu- 
 mina, iron, magnesia, and manganese. It 
 occurs principally in secondary formations, 
 along with sandstone, gypsum, and coal. 
 Many animal petrifactions, and some vege- 
 table, are found in it. It is rich in ores of 
 lead and zinc ; the English mines of the 
 foimer metal being situated in limestone. 
 When it is so hard as to take a polish, it is 
 worked as a marble, under the name of 
 shell, or lumaccella marble. It abounds in 
 the sandstone and coal formations, both in 
 Scotland and England ; and in Ireland it is 
 a very abundant mineral in all the districts, 
 where clay-slate , and red-sandstone occur! 
 J lie I lorentine marble, or ruin marble, is a 
 compact limestone. Seen at a distance, slabs 
 of this stone resemble drawings done in 
 bistre. 
 
 2, Blue Vesuvian limestono. Colour 
 
 dark bluish-grey, partly veined with white. 
 Roiled and uneven on the surface, frac- 
 ture fine earthy. Opaque. Streak white. 
 Semi-hard in a low degree. Feels heavy. 
 Its constituents are, lime 58, carbonic acid 
 28.5, water somewhat ammoniacal 11, mag- 
 nesia 0.5, oxide of iron 0.25, carbon 0.25, 
 and silica 1.25. — Klaproth. It is found in 
 loose masses among unaltered ejected mine- 
 rals, in the neighbourhood of Vesuvius. In 
 mosaic work, it is used for representing the 
 sky. 
 
 o. Roestone. Colours brown and grey. 
 Massive, and in distinct concretions, which 
 are round granular. Dull. Opaque. Frac- 
 ture of the mass round granular. Approach- 
 ing to soft. Brittle. Sp. gr. 2. G to 2.68. 
 It dissolves with effervescence in acids. It 
 occurs along with red-sandstone and lias 
 limestone. In England this rock is called 
 Bath-stone, Ketton-stone, Portland-stone, 
 and Oolite. It extends, with but little in- 
 terruption, from Somersetshire to the banks 
 of the Humber in Lincolnshire. It is used 
 in architecture, but it is porous, and apt to 
 moulder away, as is seen in the ornamental 
 w ork of the Chapel of Henry VIII. 
 
 5d Sub-species. Chalk, which see. 
 
 4th. Agaric mineral, or Rock-milk. Co- 
 lour white. In crusts or tuberose pieces. 
 Dull. Composed of fine dusty particles. 
 Soils strongly. Feels meagre. Adheres 
 slightly to the tongue. Light, almost super- 
 natant. It dissolves in muriatic acid with 
 effervescence, being a pure carbonate of lime. 
 It is found on the north side of Oxford, be- 
 tween the Isis and the Cherwell, and near 
 Chipping Norton ; as also in the fissures of 
 limestone caves on the Continent. It is 
 formed by the attrition of water on limestone 
 rocks. 
 
 5th Sub-species. Fibrous limestone ; of 
 which there are two kinds, satin-spar, or the 
 common fibrous ; and fibrous calc- sinter. 
 Satin-spar. White of various shades. Mas- 
 sive, and in distinct fibrous concretions. 
 Lustre glistening and pearly ; fragments 
 splintery ; feebly translucent ; as hard as cal- 
 careous spar ; easily frangible ; sp. gr. 2.7. 
 Its constituents are, lime 50.8, carbonic 
 acid 47.6 ? Stromeyer says it contains some 
 per cents of gypsum. It occurs in thin 
 layers in clay- slate at Aldstone-moor in Cum- 
 berland ; in layers and veins in the middle 
 district of Scotland, as in Fifesliire. It is 
 sometimes cut into necklaces, &c. 
 
 Fibrous calc-sinter. It is used as marble, 
 and the ancients formed it into unguent- 
 vases, the alabaster-box of Scripture. See 
 Calc-sinter. 
 
 6th Sub-species. 1 ufaceous limestone, or 
 Calc-tuff. Colour grey. Massive, and in 
 imitative shapes, enclosing leaves, bones, 
 shells, Sc c. Dull, fracture fine grained 
 uneven. Opaque. Soft. Feels rough* 
 
L1M 
 
 L1M 
 
 Brittle. It is pure carbonate of lime. It oc- 
 curs in beds, generally in the neighbourhood 
 of rivers ; near Starly-burn in Fifeshire, and 
 other places. Used for lime. 
 
 7 th Sub-species. Pisiform limestone, or 
 Peastone. Colour yellowish- white. Mas- 
 sive, and in distinct concretions, which are 
 round granular, composed of others which 
 are very thin and concentric lamellar. In 
 the centre there is a bubble of air, a grain 
 of sand, or of some mineral matter. Dull. 
 Fracture even. Opaque. Soft. Brittle. 
 Sp. gr. 2.532. It is carbonate of lime. It 
 is found in great masses in the vicinity of 
 Carlsbad in Bohemia. 
 
 8th Sub-species. Slate -spar. Schiefers- 
 path. Colour white, of various shades. 
 Massive, and in distinct curved lamellar con- 
 cretions. Lustre glistening and pearly. 
 Feebly translucent. Soft ; between sectile 
 and brittle. Feels rather greasy. Sp. gr. 
 2.63. Its constituents are carbonate of lime, 
 with three per cent of oxide of manganese. 
 It occurs in primitive limestone, in metalli- 
 ferous beds and in veins. It is found in 
 Glentilt; in Assynt; in Cornwall; and near 
 Granard in Ireland. 
 
 9th Sub-species. Aphrite, which see. 
 
 10th Sub-species. Lucullite ; of which 
 there are three kinds, compact, prismatic, 
 and foliated. 
 
 § 1. Compact is subdivided into the com- 
 mon or black marble ; and the stinkstone. 
 
 a. The common compact. Colour grey- 
 ish-black. Massive. Glimmering. Frac- 
 ture fine grained uneven. Opaque. Semi- 
 liard. Streak, dark ash-grey. Brittle. 
 Sp. gr. 5. When two pieces are rub- 
 bed together, a fetid urinous odour is 
 exhaled, which is increased by breathing 
 on them. It burns white, but forms a 
 black- coloured mass with sulphuric acid. 
 Its constituents are, lime 53.38, carbonic 
 acid 41.5, carbon 0.75, magnesia and ox- 
 ide of manganese 0.12, oxide of iron 0.25, 
 silica 1.13, sulphur 0.25, muriates and sul- 
 phates of potash with water 2.62. — John. It 
 is said to occur in beds in primitive and older 
 secondary rocks. Hills of this mineral oc- 
 cur in the district of Assynt in Sutherland. 
 Varieties of it are met with in Derbyshire ; 
 at Kilkenny ; in the counties of Cork and 
 Galway. The consul Lucullus admired it 
 so much, as to give it his name. It is the 
 Nero antico ol the Italians. 
 
 b. Stinkstone , or Swinestone. Colour white, 
 of many shades, cream-yellow, grey, black, 
 and brown. Massive, disseminated, and in 
 distinct granular concretions. Dull. Frac- 
 ture splintery. Opaque. Semi-hard. Streak 
 greyish-white. Emits a fetid odour on fric- 
 tion. Brittle. Sp. gr. 2.7. The same che- 
 mical characters as the preceding. Its con- 
 stituents are, 88 carbonate of lime, 4.15 
 silica, 5.1 alumina, 1.47 oxide of iron, 0.5S 
 
 oxide of manganese, 0.S0 carbon, 0.58 lime; 
 sulphur, alkali, salt, water, 2.20. — John. It 
 occurs in beds in secondary limestone, alter- 
 nating occasionally with secondary gypsum 
 and beds of clay. It is found in the vici- 
 nity of North Berwick, resting on red sand- 
 stone, and in the parish of Kirbean in Gal- 
 loway. It is employed for burning into 
 lime. 
 
 § 2. Prismatic lucullite. Colours black, 
 grey, and brown. Massive, in balls, and in 
 distinct concretions. External surface some- 
 times streaked. Internal lustre shining. 
 Cleavage threefold. Translucent on the 
 edges. Semi-hard. Streak grey coloured. 
 Brittle. When rubbed it emits a strongly 
 fetid urinous smell. Sp. gr. 2.67. When 
 its powder is boiled in water, it gives out a 
 transient hepatic odour. The water becomes 
 slightly alkaline. It dissolves with effer- 
 vescence in muriatic acid, leaving a charcoaly 
 residuum. Its constituents resemble those 
 of the preceding. It occurs in balls, in 
 brown dolomite, at Building-hill, near Sun- 
 derland. It was at one time called madre- 
 porite . 
 
 § 3. Foliated or sparry lucullite. Colours 
 white, grey, and black. Massive, dissemi- 
 nated and crystallized in acute six-sided py- 
 ramids. Internal lustre glimmering. Frag- 
 ments rhomboidal. Translucent. Semi- 
 hard. Brittle. Emits on friction a urinous 
 smell. Sp. gr. 2.65. In other respects 
 similar to the preceding. It is found in 
 veins at Andreasberg, in the Hartz. 
 
 lltli Sub-species. Marie; of whieh there 
 are two kinds, earthy and compact. Earthy 
 marie has a grey colour, consists of fine dusty 
 particles, feebly cohering; dull; soils slight- 
 ly ; is light ; effervesces with acids ; and 
 emits a urinous smell when first dug up. 
 Its constituents are carbonate of lime, with a 
 little alumina, silica, and bitumen. It oc- 
 curs in beds in the secondary limestone and 
 gypsum formations in Thuringia and Mans- 
 feld. Compact marie has a grey colour ; is 
 massive, vesicular, or in flattened balls ; con- 
 tains petrifactions ; dull ; fracture earthy, 
 but in the great slaty ; yields to the nail ; 
 opaque; streak greyish- white ; brittle; feels 
 meagre ; sp. gr. 2.4. It intumesces before 
 the blow-pipe, and melts into a greenish- 
 black slag. It effervesces with acids. Its 
 constituents are carbonate of lime 50, silica 
 12, alumina 52, iron and oxide of manga- 
 nese 2. — Kir wan. 1 1 occurs in beds in the se- 
 condary floetz limestone. It is frequent in 
 the coal formations of Scotland and England. 
 
 12th Sub-species. Bituminous marie-slate. 
 Colour greyish-black. Massive, and fre- 
 
 quently with impressions of fishes and plants. 
 Lustre glistening. Fracture slaty. Opaque. 
 Shining streak. Soft. Sectile. Frangible, 
 
 Sj). gr. 2. 66. 1 1 is said to be carbonate of lime, 
 with albumen, iron, and bitumen. It occurs 
 
LIT 
 
 LIT 
 
 in floetz limestone. It frequently contains 
 cupreous minerals, petrified fishes, and fossil 
 remains of cryptogamous plants. It abounds 
 in the Ilartzgebirge. — Jameson .* 
 
 Liquefaction. A chemical term, in some 
 instances synonymous with the word fusion^ 
 in others with the word deliquescence , and 
 in others again with the word solution. 
 
 * Liquidity. See Caloric.* 
 
 Liquor of Flints. See Silica. 
 
 * Litjhia. A new alkali. It was disco- 
 vered by M. Arfredson, a young chemist ot 
 great merit, employed in the laboratory ot 
 M. Berzelius. It was found in a mineral 
 from the mine of Uten, in Sweden, called 
 petalite, by M. d’Andrada, who first distin- 
 guished it. Sir LI. Davy demonstrated by 
 voltaic electricity, that the basis ot this alkali 
 is a metal, to which the name of lithium has 
 been given. 
 
 Berzelius gives the following simple pro- 
 cess as a test for litliia in minerals : — 
 
 A fragment of the mineral, the size of a 
 pin’s head, is to be heated with a small ex- 
 cess of soda, on a piece of platinum foil, by a 
 blow-pipe for a couple of minutes. The 
 stone is decomposed, the soda liberates the 
 lithia, and the excess of alkali preserving the 
 whole fluid at this temperature, it spreads 
 over the foil, and surrounds the decomposed 
 mineral. That part of the platinum near to 
 the fused alkali becomes of a dark colour, 
 which is more intense, and spreads over a 
 larger surface, in proportion as there is more 
 lithia in the mineral. The oxidation of the 
 platinum does not take place beneath the 
 alkali, but only around it, where the metal is 
 in contact with both air and lithia. Potash 
 destroys the reaction of the platinum on the 
 lithia, if the lithia be not redundant. The 
 platinum resumes its metallic surface, after 
 having been washed and heated. 
 
 Lithia may be obtained by fusing petalite 
 with potash, dissolving the whole in muriatic 
 acid, evaporating to dryness, and digesting 
 in alcohol. The muriate of lithia being 
 very soluble in that fluid, is taken up, while 
 the other salts remain. By a second eva- 
 poration and solution in alcohol, it is obtain- 
 ed perfectly pure. The muriate is itself a salt 
 very characteristic of the alkali. It may 
 easily be decomposed by carbonate of silver ; 
 and the carbonate thus procured, when treat- 
 ed with lime, yields pure lithia. Dr Gme- 
 lin fused petalite with five times its weight 
 of nitrate of barytes, at a white-heat, in a 
 platinum crucible ; digested the mass in 
 muriatic acid ; evaporated the solution to 
 dryness ; dissolved in water ; separated the 
 silica ; and added rather more sulphuric acid 
 than was equivalent to the barytes. The 
 sulphate of barytes w r as got rid of by solution 
 in water and filtration. The liquid was now 
 concentrated by evaporation to expel the ex- 
 cess of muriatic acid. It was then supersa- 
 
 turated with carbonate of ammonia, which 
 threw down the alumina and the oxide oi 
 iron. The filtered liquid w r as evaporated to 
 dryness, and the residue was ignited, to drive 
 olf the ammoniacal sulphate and muriate; 
 The remainder w r as dissolved in vvater^ and 
 hydrosulphuret of ammonia was added to 
 the solution to separate the manganese. Be- 
 ing now filtered, evaporated, and ignited, it 
 was pure sulphate of lithia, from which he 
 obtained the carbonate by adding acetate of 
 barytes, and decomposing the resulting ace- 
 tate of lithia by a red-heat. 
 
 The first is the process of M. Vauquelin, 
 and is vastly the simpler of the tw r o. The 
 most complete account, however, which we 
 have of lithia and its compounds, is that of 
 Dr Gmelin. He had the benefit indeed of 
 M. Vauquelin’s very able researches, pub- 
 lished in the Ann. de Chimie et Flips, vii. 
 287. Dr Gmelin’s memoir is inserted in 
 the 62d volume of Gilbert’s Annalen. 
 
 Caustic lithia has a very sharp burning 
 taste. It destroys the cuticle of the tongue, 
 like potash. It does not dissolve w ith great 
 facility in w ater, and appears not to be much 
 more soluble in hot than in cold w r ater. In 
 this respect it has an analogy wfith lime. 
 Heat is evolved during its solution in water. 
 
 When exposed to the air, it does not at- 
 tract moisture, but absorbs carbonic acid, and 
 becomes opaque. When exposed for an 
 hour to a white- heat in a covered platinum 
 crucible, its bulk does not appear to be dimi- 
 nished ; but it has absorbed a quantity of 
 carbonic acid. 
 
 It dissolves only in small quantity in al- 
 cohol of the specific gravity 0.85. When 
 weak alcohol is added to an aqueous solution 
 of lithia in a well stopped phial, no change 
 takes place at first ; but after some hours the 
 lithia precipitates in the state of a white 
 powder. 
 
 Lithia unites with sulphur, according to 
 Vauquelin. Sulphuret of lithia has a yellow 
 colour, dissolves readily in water, and is de- 
 composed by acids in the same w r ay as the 
 other alkaline sulphurets. 
 
 Phosphorus decomposes water with the 
 help of caustic lithia. If we heat in a retort 
 phosphorus with a solution of caustic lithia 
 in water, phosphuretted hydrogen gas is dis- 
 engaged, which catches fire when it comes 
 into the air. 
 
 Neutral sulphate of lithia forms small pris- 
 matic crystals, having a good deal of lustre, 
 sometimes constituting pretty long, but nar- 
 row tables. When exposed to the air, they 
 undergo only an insignificant efflorescence. 
 This salt has a saline and scarcely bitter 
 taste. It dissolves pretty readily in w-ater, 
 and melts when exposed to a temperature 
 scarcely reaching a red-heat. 
 
 Bisulphate of lithia dissolves in water with 
 greater facility than the neutral salt. It 
 
LIT 
 
 LIT 
 
 forms six-sided tables, in which two of the 
 faces, which are parallel to each other, far 
 exceed the remaining ones in length. When 
 exposed to a very high temperature, it gives 
 out sulphurous acid and oxygen gas, and is 
 converted into the neutral sulphate. 
 
 According to Arfredson, this bisalt dis- 
 solves with more difficulty in water than, the 
 neutral salt. 
 
 Phosphate of lithia . — Phosphoric acid, 
 when dropped into the solution of sulphate 
 of lithia, occasions no precipitate. But when 
 the uncombined acid is saturated by ammo- 
 nia, the phosphato of lithia is precipitated in 
 the state of white Hocks, w hich are insoluble 
 in w ater. 
 
 When a drop of phosphoric acid is let fall 
 into a very dilute solution of carbonate of 
 lithia, no precipitate falls ; but when the li- 
 quid is heated, the carbonic acid gas is dis- 
 engaged, and phosphate of lithia falls down. 
 From this it would seem, that the solubility 
 of phosphate of lithia in water is owing to 
 the presence of the carbonic acid. 
 
 There exists likewise a biphosphate of lithia. 
 It is obtained by dissolving the neutral salt 
 in phosphorio acid. By a very slow evapo- 
 ration of this solution, we obtain transparent 
 granular crystals. 
 
 Nitrate of lithia forms four-sided prisms 
 with rhomboidal bases. It has a very pun- 
 gent taste, and seems to surpass almost all 
 other salts in deliquescency. In a very hot 
 day, it crystallized in the sun ; but deli- 
 quesced again in the shade. It dissolves in 
 the strongest alcohol. 
 
 Carbonate of lithia constitutes a wliite 
 powder. It dissolves with great difficulty in 
 cold water. According to Vauquelin, 100 
 parts of water dissolve scarcely one part of 
 this salt. It is more soluble in hot water. 
 A solution of carbonate of lithia containing 
 only 1- 1000th of its weight of the salt, acts 
 strongly as an alkali. 
 
 0.535 gramme effused carbonate of lithia 
 were, by means of sulphuric acid and ex- 
 posure to a strong heat, converted into 0.765 
 of neutral sulphate of lithia. Now this 
 quantity of sulphate contains 0.2436 of lithia. 
 
 Hence 0.535 of carbonate of lithia are 
 composed of 
 
 Lithia, 0.2436 
 
 Carbonic acid, 0.2914 
 
 0.5350 
 
 Or in the 100 parts, 
 
 Lithia, 45.54 
 
 Carbonic acid, 54.46 
 
 100.00 
 
 But the oxygen in 
 
 45.54 lithia is = 19.09 
 54.46 carbonic acid= 39.59 
 and 2 X 19*09 = 38.18, a number difler- 
 ing but little from 39.59. 
 
 I he solution of carbonate of lithia is de- 
 composed by lime and barytes water. It is 
 insoluble in alcohol. 
 
 The platinum crucible in which carbonate 
 of lithia has been exposed to a red-heat, gives 
 obvious indications of having been attacked, 
 its surface assuming a dark olive-green co- 
 lour ; but the metallic lustre is again restor- 
 ed by rubbing the crucible with coarse sand 
 and water. 
 
 Muriate of lithia forms small regular cubes 
 very similar to common salt in their taste. 
 The easiest method of obtaining the crystals, 
 is to expose the solution to the sun in a bot 
 day. The crystals deliquesce very speedily 
 when exposed to the air, but not with so 
 much rapidity as nitrate of lithia. This salt 
 does not melt when exposed to the red-heat 
 produced by the action of a spirit lamp ; but 
 when exposed in a platinum crucible, not 
 completely covered, to an incipient white- 
 lieat, it is fused into the chloride. 
 
 Chromate of lithia forms orange-yellow 
 crystals, which appear to contain an excess 
 of acid. They are oblique parallelopipeds 
 with rhomboidal bases. Sometimes they ex- 
 hibit a dendritical vegetation. This salt is 
 soluble in water. 
 
 Oxalate of lithia . — A portion of carbonate 
 of lithia w r as saturated with oxalic acid. 
 The neutral salt crystallizes with difficulty. 
 The crystals have the appearance of small 
 opaque protuberances, and dissolve with fa- 
 cility in water. To the neutral solution of 
 oxalate of lithia w'as added a quantity of 
 oxalic acid, exactly equal (o that already 
 combined with the lithia. By evaporation, 
 small transparent granular crystals of binoxa- 
 lute of lithia were obtained. They appeared 
 to dissolve with facility in w r ater, though not 
 to be so soluble as the neutral salt. 
 
 Neutral tartrate of lithia dissolves with 
 facility in water, but does not crystallize, 
 forming a white opaque mass, which does 
 not deliquesce wffien exposed to the air. 
 When tartaric acid is added to the solution 
 of the neutral tartrate, no crystallizable bi- 
 tartrate is formed ; but perhaps we may de- 
 duce the existence of such a salt from the 
 fact, that when the solution is evaporated, no 
 crystals of tartaric acid make their appear- 
 ance. 
 
 When the solution is evaporated to dry- 
 ness, vve obtain a white opaque mass, which 
 exhibits no appearance of crystallization, and 
 which dissolves with facility in water. 
 
 Acetate of lithia, when evaporated, forms 
 a syrupy mass, which cracks on cooling ; so 
 that the glass looks as if it had burst. This 
 matter deliquesces in the air, and sometimes, 
 while attracting moisture, crystalline plates 
 appear in it. 
 
 Tartrate of lithia and potash . — If the ex- 
 cess of acid of bitartrate ol potash be satu- 
 rated by means of carbonate oi lithia, we 
 
LIT 
 
 LIT 
 
 obtain, by spontaneous evaporation, a salt 
 which forms large crystals, having the shape 
 of four-sided prisms terminated by parallelo- 
 grams, with angles very nearly right. The 
 diagonals of these terminal faces are distinct- 
 ly marked, and the four triangles formed by 
 means of them are streaked parallel to the 
 edges of these faces. This salt dissolves 
 readily in water, and has a saline and scarce- 
 ly bitter taste. When exposed to the air, it 
 effloresces slightly, and only on the sur- 
 face. 
 
 Tartrate of lithia and soda . — Bitartrate of 
 soda was neutralized by means of carbonate 
 of lithia. By spontaneous evaporation, the 
 liquid deposited long rectangular four-sided 
 prisms, frequently terminated by an oblique 
 face. This salt dissolves with facility in wa- 
 ter, and effloresces only slightly, and on the 
 surface. Its taste is purely saline, and not 
 strong. 
 
 Muriate of platinum does not form a 
 double salt with muriate of lithia. Potash 
 and lithia, therefore, may be very well dis- 
 tinguished from each other by means of 
 muriate of platinum. 
 
 From the preceding account of the salts of 
 lithia, we see that they have many properties 
 in common with the salts of soda. Like 
 them, they are neither precipitated by mu- 
 riate of platinum, nor by tartaric acid. They 
 may, however, be distinguished from the 
 salts of soda by the following properties : 
 When their concentrated solutions are mixed 
 with a concentrated solution of carbonate of 
 soda, a precipitate falls. They are likewise 
 precipitated by phosphate of soda and phos- 
 phate ot ammonia, when no uncombined 
 acid is present. 
 
 In reference to analytical chemistry, it may 
 be remarked, that lithia, potash, and soda, if 
 they should exist in the same compound, may 
 be separated in the following way : — 
 
 Lithia may be precipitated by means of 
 phosphoric acid and an excess of caustic am- 
 monia. The phosphate of lithia may be 
 dissolved in acetic acid, and the phosphoric 
 acid precipitated by means of acetate of lead, 
 &c. 
 
 When lithia exists in a compound with 
 potash, this last alkali may be precipitated 
 by means of muriate of platinum. 
 
 I rom the results of the preceding experi- 
 ments, we see, says Dr Gmelin, that if 10 
 be the equivalent number for oxygen, the 
 equivalent number for lithium is I 3.83, and 
 for lithia 23.83 ; that for carbonate of lithia 
 by calculation 51.32; but, according to the 
 preceding experiment, 52.32, See. 
 
 Placed in the voltaic circuit, Sir II. Davy 
 shewed, that it was decomposed with the 
 same phenomena as the other alkalis. A 
 portion of its carbonate being fused in a pla- 
 tinum capsule, the platinum was rendered 
 positive, and a negative wire brought to the 
 
 upper surface. The alkali decomposed with 
 bright scintillations, and the reduced metal 
 being separated, afterwards burned. The 
 particles were very similar to sodium. A 
 globule of quicksilver made negative, and 
 brought into contact with the alkaline salt, 
 soon became an amalgam of lithium, and 
 had gained the power of acting on water, 
 with the evolution of hydrogen, and forma- 
 tion of alkali. 
 
 M. Vauquelin concludes from his experi- 
 ments, that 100 parts of lithia contain 43.5 
 of oxygen, and 56.5 of metallic base; a 
 quantity which, he observes, is greater than 
 that of all the other alkalis. The Editors 
 of the Ann. de Chimie remark, that accord- 
 ing to this estimate, the equivalent number 
 of the metal is 12.97, of its oxide 22.97, of 
 its dry sulphate 72.97, and of its crystallized 
 sulphate 82.97. These numbers are adapt- 
 ed to the oxygen radix of 10. Dr Gmelin’s 
 analysis of lithia, makes its composition to 
 be, by his own reduction, 
 
 Lithium, 58.05 
 
 Oxygen, 41.95 
 
 100.00 
 
 His neutral sulphate consists of, 
 
 Crystallized. Dry. 
 
 Sulphuric acid, 58.34 68. 15 5.000 
 
 Lithia, 27.2 5 51.85 2.3367 
 
 Water, 14.41 
 
 The prime equivalent of lithia inferred from 
 this analysis, approaches much nearer to M. 
 Vauquelin ’s number, than that deduced by 
 Dr Gmelin himself. If we convert this 
 prime ratio into per cent proportions, we shall 
 have lithia a compound, 
 
 Of Lithium, 57.205 1.3367 
 
 Oxygen, 42.795 1.0000 
 
 I' rom his analysis of the carbonate, the 
 prime equivalent of lithia comes out, as near- 
 ly as possible, 2.3. We are therefore war- 
 ranted to consider 1.5 as the prime of lithium, 
 from the concurring experiments, both of M. 
 Vauquelin and Dr Gmelin. I cannot see 
 how the Doctor’s own ingenious and accu- 
 rate experiments on these two salts, permit- 
 ted him to make so erroneous an estimate of 
 the equivalent of lithia, as 23.83, instead of 
 23f or 23.* 
 
 * Lithic Acid. See Acid (Lithic).* 
 
 * Lithomarge. Stone-marrow, a mineral 
 of which there are two kinds, the friable, 
 and the indurated. 
 
 Friable Lithomarge. Colour white, mas- 
 sive, and sometimes in crusts. Particles 
 scaly, and feebly glimmering. Streak shin- 
 ing. Slightly cohering. Soils slightly. 
 Feels rather greasy. Adheres to the tongue. 
 Light. Phosphoresces in the dark. Its con- 
 stituents aie, silica 32, alumina 26.5, iron 
 
 21, muriate of soda 1.5, and water 17.0 
 
 Klaproth . It occurs commonly in tin-stone 
 veins. 
 
LOG 
 
 LUT 
 
 Indurated Lithomarge. Colours, yel- 
 lowish and reddish- white. Massive, and 
 amygdaloidal. Dull. Fracture, line earthy. 
 Opaque. Streak shining. Soft, sectile, and 
 easily frangible. Adheres strongly to the 
 tongue, heels fine, and greasy. Sp. grav. 
 2.44. Infusible before the blow-pipe ; some 
 varieties phosphoresce, and others, when 
 moistened, afford an agreeable smell like 
 that of nuts. Its constituents are, silica 
 45.25, alumina 36.5, oxide of iron 2.75. 
 water 14, and a trace of potash. — Klaproth. 
 It occurs in veins in porphyry, gneiss, Sec. at 
 Rochlitz in Saxony, and at Zbblitz. — Jame- 
 son .* 
 
 Litmus. Sec Archil. 
 
 Liver of Sulphur. See Sulphur. 
 
 Lixiviation. The application of water 
 to the fixed residues of bodies, for the pur- 
 pose of extracting the saline part. 
 
 Lixivium. A solution obtained by lixivi- 
 ation. 
 
 Loadstone. See Ores of Iron. 
 
 * Loam. See Clay.* 
 
 Logwood. The tree which yields it is 
 called by Linnaeus, Ilcematoxylum campe- 
 chianum. 
 
 Logwood is so heavy as to sink in water, 
 hard, compact, of a fine grain, capable of 
 being polished, and scarcely susceptible of 
 decay. Its predominant colour is red, ting- 
 ed with orange, yellow, and black. 
 
 It yields its colour, both to spirituous and 
 watery menstrua. Alcohol extracts it more 
 readily and copiously than water. The co- 
 lour of its dyes is a fine red, inclining a lit- 
 tle to violet or purple, which is principally 
 observable in its watery decoction. This, 
 left to itself, becomes in time yellowish, and 
 at length black. Acids turn it yellow ; al- 
 kalis deepen its colour, and give it a purple 
 or violet hue. 
 
 Stuffs would take only a slight and fading 
 colour from decoction of logwood, if they 
 were not previously prepared with alum and 
 tartar. A little alum is added also to the 
 bath. By these means they acquire a pretty 
 good violet. 
 
 A blue colour may be obtained from log- 
 wood, by mixing verdegris with the bath, 
 and dipping the cloth till it has acquired the 
 proper shade. 
 
 The great consumption of logwood is for 
 blacks, to which it gives a lustre and vel- 
 vety cast, and for greys of certain shades. It 
 is also of very extensive use for different 
 compound colours, which it would be diffi- 
 cult to obtain of equal beauty and variety, 
 by means of drugs affording a more perma- 
 nent dye. 
 
 Juice of logwood is frequently mixed with 
 that of brasil, to render colours deeper; their 
 proportion being varied according to the 
 shade desired. 
 
 Logwood is used for dyeing silk, violet. 
 
 For this, the silk must be scoured, alumed, 
 and washed ; because, without aluming, it 
 would take only a reddish tinge, that would 
 not stand wetting. To dye silk thus, it 
 must be turned in a cold decoction of log- 
 wood, till it has acquired the proper colour : 
 if the decoction were used hot, the colour 
 would be in stripes and uneven. 
 
 Bergman has already observed, that a fine 
 violet might be produced from logwood, by 
 impregnating the silk with solution of tin. 
 In fact, we may thus obtain, particularly by 
 mixing logwood and brasil in various pro- 
 portions, a great number of fine shades, more 
 or less inclined to red, from lilac to violet. 
 See Hem ati n. 
 
 * Lomonite, or Laumonite. Di-prismatic 
 Zeolite.* 
 
 * Lucullite. See Limestone, 10th spe- 
 cies.* 
 
 Lumachella. See Limestone. 
 
 Luna Cornea. Muriate of silver. Sec 
 Silver. 
 
 Lunar Caustic. Nitrate of silver, fused 
 in a low heat. See Silver. 
 
 Lute. The lutes with which the joinings 
 of vessels are closed, are of different kinds, 
 according to the nature of the operations to 
 be made, and of the substances to be distilled 
 in these vessels. 
 
 When vapours of watery liquors, and such 
 as are not corrosive, are to be contained, it 
 is sufficient to surround the joining of the 
 receiver to the nose of the alembic, or of 
 the retort, with slips of paper or of linen, 
 covered with flour-paste. In such cases 
 also slips of wet bladder are very convenient- 
 ly used. 
 
 'When more penetrating and dissolving 
 vapours are to be contained, a lute is to be 
 employed of quicklime slacked in the air, 
 and beaten into a liquid paste with whites of 
 eggs. This paste is to be spread upon linen 
 6lips, which are to be applied exactly to the 
 joining of the vessels. This lute is very con- 
 venient, easily dries, becomes solid, and suf- 
 ficiently firm. Of this lute, vessels may be 
 formed hard enough to bear polishing on the 
 wheel. 
 
 Lastly, when acid, and corrosive vapours 
 are to be contained, we must then have re- 
 course to the lute calledyht lute. This lute 
 is made by forming into a paste some dried 
 clay finely powdered, sifted through a silken 
 scarce, and moistened with water, and then 
 by beating this paste well in a mortar with 
 boiled linseed oil, that is, oil which has been 
 rendered drying by litharge dissolved in it, 
 and fit for the use of painters. This lute 
 easily takes and retains the form given to 
 it. It is generally rolled into cylinders ot 
 a convenient size. These are to be applied, 
 by flattening them, to the joinings ot the ves- 
 sels, which ought to be perfectly dry, because 
 the least moisture would prevent the lute 
 
MAD 
 
 MAD 
 
 from adhering. When the joinings are well 
 closed with this fat lute, the whole is to be 
 covered with slips of linen spread with lute 
 of lime and whites of eggs. These slips are 
 to be fastened with packthread. The se- 
 cond lute is necessary to keep on the fat 
 lute, because this latter remains soft, and 
 does not become solid enough to stick on 
 alone. 
 
 Fine porcelain clay, mixed with a solution 
 of borax, is well adapted to iron vessels, the 
 
 part received into an aperture being smeared 
 with it. 
 
 Lycotodium. The fine dust of lycopodi- 
 um, or clubmoss, is properly the seeds of the 
 plant, and when diffused or strewed in the 
 air, it takes fire from a candle, and burns off 
 like a flash of lightning. It is used in the 
 London theatres. 
 
 * Lydian Stone. Flinty slate.* 
 
 * Lythuodes, See Scapolite.* 
 
 M aceration. The steeping of a 
 
 body in a cold liquor. 
 
 Madder, a substance very extensively em- 
 ployed in dyeing, is the root of the rubia 
 tinctorum. 
 
 Although madder will grow both in a stiff 
 clayey soil, and in sand, it succeeds better in 
 a moderately rich, soft, and somewhat sandy 
 soil : it is cultivated in many of the provinces 
 of France, in Alsace, Normandy, and Pro- 
 vence : the best of European growth is that 
 which comes from Zealand. 
 
 The best roots are about the thickness of 
 a goose quill, or at most of the little finger ; 
 they are semi-transparent, and of a reddish 
 colour; they have a strong smell, and the 
 bark is smooth. 
 
 Ilellot ascribes the superiority of the mad- 
 der which comes from the Levant to the cir- 
 cumstance of its having been dried in the 
 open air. 
 
 The red colouring matter of madder may 
 be dissolved in alcohol, and on evaporation, 
 a residuum of a deep red is left. Fixed al- 
 kali forms in this solution a violet, the sul- 
 phuric acid a fawn-coloured, and the sul- 
 phate of potash a fine red precipitate. Pre- 
 cipitates of various shades may be obtained 
 by alum, nitre, chalk, sugar of lead, and the 
 muriate of tin. 
 
 The quantity of aqueous chlorine required 
 to destroy the colour of a decoction of mad- 
 der, is double what is necessary to destroy 
 that of a decoction of an equal weight of 
 brasil wood. 
 
 Wool would receive from madder only a 
 perishable dye, if the colouring particles 
 were not fixed by a base, which occasions 
 them to combine with the stuff more inti- 
 mately, and which in some measure defends 
 them from the destructive influence of the 
 air. For this purpose, the woollen stuffs 
 are first boiled for two or three hours with 
 alum and tartar, after which they are left to 
 drain ; they arc then slightly wrung and 
 put into a linen bag, and carried into a cool 
 place, where they are suffered to remain for 
 some days. 
 
 o 
 
 am 
 
 The quantities of aluin and tartar, as well 
 as their proportions, vary much in different 
 manufactories. Hellot recommends five 
 ounces of alum and one ounce of tartar to 
 each pound of wool; if the proportion of 
 tartar be increased to a certain degree, in- 
 stead of a red, a deep and durable cinnamon 
 colour is produced, because, as we have 
 seen, acids have a tendency to give a yel- 
 low tinge to the colouring particles of mad- 
 der. Berthollet found, that, by employing 
 one-half tartar, the colour sensibly bordered 
 more on the cinnamon than when the pro- 
 portion was only one- fourth of the alum. 
 
 In dyeing with madder, the batli must 
 not be permitted to boil, because that degree 
 of heat would dissolve the fawn-coloured 
 particles, which are less soluble than the red, 
 and the colour would be different from that 
 which we wish to obtain. 
 
 The quantity of madder which Mr Poer- 
 ner employs is only one-third of the weight 
 of the wool, and Schaeffer advises only one- 
 fourth. 
 
 If wool be boiled for two hours with one- 
 fourth of sulphate of iron, then washed, and 
 afterward put into cold water with one- fourth 
 of madder, and then boiled for an hour, a 
 coffee colour is produced. Bergman adds, 
 that, if the wool have not been soaked, and if 
 it be dyed with one part of sulphate of iron 
 and two of madder, the brown obtained bor- 
 ders upon a red. 
 
 Berthollet employed a solution of tin in 
 various ways, both in the preparation and in 
 the maddering of cloth. He used different 
 solutions of tin, and found that the tint was 
 always more yellow or fawn-coloured, though 
 sometimes brighter than that obtained by the 
 common process. 
 
 Mr Guhliche describes a process for dye- 
 ing silk with madder: for one pound of silk 
 lie orders a bath of four ounces cf alum, and 
 one ounce of a solution of tin ; the liquor is 
 to be left to settle, when it is to be decanted, 
 and the silk carefully soaked in it, and left 
 for twelve hours; and after this preparation, 
 it is to be immersed in a bath containing 
 M 
 
MAD 
 
 MAD 
 
 half a pound of madder softened by boiling 
 with an infusion of galls in white wine; this 
 bath is to be kept moderately hot for an 
 hour, after which it is to be made to boil for 
 two minutes. When taken from the bath, 
 the silk is to be washed in a stream of w'ater, 
 and dried in the sun. Mr Guhliche com- 
 pares the colour thus obtained, which is very 
 permanent, to the Turkey red. If the galls 
 be left out, the colour is clearer* A great 
 degree of brightness may be communicated 
 to the first of these, by after tvard passing it 
 through a bath of brasil wood, to which one 
 ounce of solution of tin has been added: the 
 colour thus obtained, he says, is very beauti- 
 ful and durable. 
 
 The madder red of cotton is distinguished 
 into two kinds : one is called simple madder 
 red; the other, which- is much brighter, is 
 called Turkey or Adrianople red, because 
 it comes from the Levant, and has seldom 
 been equalled in brightness or durability by 
 our artists. 
 
 Galls or sumach dispose thread and cotton 
 to receive the madder colour, and the pro- 
 per mordant is acetate of alumina. 
 
 The nitrate and muriate of iron as a mor- 
 dant, produces a better effect than the sul- 
 phate and acetate of the same metal ; they 
 afford- a beautiful, well saturated violet colour. 
 
 The Adrianople red possesses a degree of 
 brightness, which it is difficult for us to ap- 
 proach by any of the processes hitherto men- 
 tioned. 
 
 Some years ago, Mr Papillon set up a 
 dyehouse for this red at Glasgow ; and in 
 1790 the commissioners for manufactures in 
 Scotland paid him a premium, for communi- 
 cating his process to the late Prof. Black, on 
 condition of its not being divulged for a cer- 
 tain term of years. The time being expired, 
 it has been made public, and is as follows : — 
 
 Step. I. — For 100 lbs. of cotton, you must 
 have 100 lb. of Alicant barilla, 20 lb. of pearl 
 ashes, 100 lb. of quicklime.. 
 
 The barilla is to be mixed with soft water 
 in a deep tub, which has a small hole near 
 the bottom of it, stopped at first with a peg. 
 This hole is to be covered in the inside with 
 a cloth supported by two bricks, that the ashes 
 may he prevented from running out at it, or 
 stopping it up, while the ley filters through it. 
 Under this tub must be another, to receive 
 the ley, and pure water is to be passed re- 
 peatedly through the first tub, to lorm leys of 
 different strength, which are kept separate 
 until their strength is examined. The strong- 
 est required for use must float an egg, and is 
 called the ley of six degrees of the French 
 hydrometer. The weaker are afterwards 
 brought to this strength by passing them 
 through fresh barilla ; but a certain quantity 
 of the weak, which is of two degrees ol the 
 above hydrometer, is reserved for dissolving 
 the oil, the gum, and the salt, which arc used 
 
 in subsequent parts of the process. This Icy 
 of two degrees is called the weak barilla 
 liquor ; the other the strong. 
 
 Dissolve the pearl ashes in ten pails, of 
 four gallons each, of soft water, and the lime 
 in fourteen pails. 
 
 Let all the liquors stand till they become 
 quite clear, and then mix ten pails of each. 
 
 Boil the cotton in this mixture five hours, 
 then wash it in running water, and dry it. 
 
 Step. II. Bain bis, or Grey steep. — Take a 
 sufficient quantity (ten pails) of the strong 
 barilla water in a tub, and mix with it two 
 pailfuls of sheep’s dung ; then pour into it 
 two quart bottles of sulphuric acid, one 
 pound of gum-arabic, and one pound of sal 
 ammoniac, both previously dissolved in a 
 sufficient quantity of weak barilla water; 
 and, lastly, twenty-five pounds of olive oily 
 previously dissolved, or well mixed with two i 
 pails of the weak barilla water. 
 
 The materials of this steep being well 
 mixed, tread down the cotton into it until it 
 is well soaked ; let it steep twenty-four hours, i 
 then wring it hard and dry it. 
 
 Steep it again twenty- four hours, and again 
 wring and dry it. 
 
 Steep it a third time twenty-four hours, 
 after which wring and dry it; and, lastly, 
 wash it well and dry it. 
 
 Step. III. The white steep. — This part of 
 the process is precisely the same with the 
 last in every particular, except that the sheep’s 
 dung is omitted in the composition of the 
 steep; 
 
 Step. TV. Gall steep. — Boil twenty-five 
 pounds of bruised galls in ten pails of river 
 water, until four or five are boiled away y 
 strain the liquor into a tub, and pour cold 
 water on the galls in the strainer to wash out 
 of them all their tincture. 
 
 As soon as the liquor is become milk- 
 warm, dip your cotton, hank by hank, hand- 
 ling it carefully all the time, and let it steep 
 twenty- four hours. Then wring it care- 
 fully and equally, and dry it well without 
 washing. 
 
 Step. V. First alum steep. — Dissolve twen- 
 ty-five pounds of Roman alum in fourteen 
 pails of warm water, without making it boil, 
 scum the liquor well, add two pails of strong 
 barilla water, and then let it cool until it is 
 lukewarm. 
 
 Dip your cotton, and handle it hank by j 
 hank, and let it steep twenty-four hours; j 
 wring it equally, and dry it well without ! 
 washing. 
 
 Step. VI. Second alum steep. — 1 his is 
 in every particular like the last ; but after the 
 cotton is dry, steep it six hours in the river, B 
 and then wash and dry it. 
 
 Step. VII. Dyeing steep. — The cotton is 
 dyed by about ten pounds at once, lor which 
 take about two gallons and a half ot bul- 
 locks’ blood, mix it in the copper with twcu- 
 
MAG 
 
 MAG 
 
 ty-eight palls of milk-warm water, stir it 
 well, add twenty-five pounds of madder, and 
 lastly, stir all well together. Then having 
 beforehand put the cotton on sticks, dip it in- 
 to the liquor, and move and turn it constantly 
 one hour, during which gradually increase 
 the heat until the liquor begins to boil at the 
 end of the hour. Then sink the cotton, and 
 boil it gently one hour longer ; and lastly 
 wash it and dry it. 
 
 Take out so much of the boiling liquor, 
 that what remains may produce a milk- warm 
 heat with the fresh water with which the cop- 
 per is again filled up, and then proceed to 
 make up a dyeing liquor, as above, for the 
 next ten pounds of cotton. 
 
 Step. VIII. The firing steep . — Mix equal 
 parts of the grey steep liquor and of the 
 white steep liquor, taking five or six pails of 
 each. Tread down the cotton into this mix- 
 ture, and let it steep six hours : then wring 
 it moderately and equally, and dry it without 
 washing. 
 
 Step. IX. Brightening steep .— Ten pounds 
 of white soap must be dissolved very care- 
 fully and completely in sixteen or eighteen 
 pails of warm water : if any little bits of the 
 soap remain undissolved, they will make 
 spots in the cotton. Add four pails of strong 
 barilla water, and stir it well. Sink the cot- 
 ton in this liquor, keeping it down with cross 
 sticks, and cover it up ; boil it gently two 
 hours, then wash it and dry it, and it is fi- 
 nished. 
 
 * Madrepores. A species of coral, the 
 zoophyte of naturalists. They consist of 
 carbonate of lime, and a little animal mem- 
 branaceous substance.* 
 
 Magistery. Chemists formerly applied 
 this term to almost all precipitates: at pre- 
 sent it is applied only to a few, which have re- 
 tained the name from habitual usage. 
 
 Magistery of Bismuth. See Bismuth. 
 
 * Magnesia. One of the primitive earths, 
 having a metallic basis, called magnesium. It 
 has been found native in the state of hydrate. 
 
 Magnesia may be obtained, by pouring in- 
 to a solution of its sulphate a solution of 
 subcarbonate of soda, washing the precipitate, 
 drying it, and exposing it to a red-heat. It 
 is usually procured in commerce, by acting 
 on magnesian limestone with the impure 
 muriate of magnesia, or bittern of the sea- 
 salt manufactories. The muriatic acid goes 
 to the lime, forming a soluble salt, and leaves 
 behind, the magnesia of both the bittern and 
 limestone. Or the bittern is decomposed by 
 a crude sub- carbonate of ammonia, obtained 
 from the distillation of bones in iron cylin- 
 ders. Muriate of ammonia and subcarbonate 
 of magnesia result. The former is evaporat- 
 ed to dryness, mixed with chalk and sublim- 
 ed. Subcarbonate of ammonia is thus reco- 
 vered, with which a new quantity of bittern 
 
 may bo decomposed ; and thus in ceaseless 
 repetition, forming an elegant and economi- 
 cal process. 100 parts of crystallized Epsom 
 salt, require for complete decomposition 56 
 of subcarbonale of potash, or 44 dry subcar- 
 bonate of soda, and yield 16 of pure magne- 
 sia after calcination. 
 
 Magnesia is a white, soft powder. Its sp. 
 gr. is 2.5 by Kirwan. It renders the syrup 
 of violets, and infusion of red cabbage, green, 
 and reddens turmeric. It is infusible, ex- 
 cept by the hydroxygen blow-pipe. It has 
 scarcely any taste, and no smelL It is 
 nearly insoluble in water ; but it absorbs a 
 quantity of that liquid with the production of 
 heat. And when it is thrown down from 
 the sulphate by a caustic alkali, it is combin- 
 ed with water constituting a hydrate, which, 
 however, separates at a red-heat. It con- 
 tains about one-fourth its weight of water. 
 
 When magnesia is exposed to the air, it 
 very slowly attracts carbonic acid. It com- 
 bines with sulphur, forming a sulphuret. 
 
 The metallic basis, or magnesium, may be 
 obtained in the state of amalgam with mer- 
 cury, by electrization, as is described under 
 Barium ; but a much longer time is neces- 
 sary. Sir II. Davy succeeded also in de- 
 composing magnesia, by passing potassium in 
 vapour through it, heated to whiteness, in a 
 tube of platinum out of the contact of air. 
 He then introduced a small quantity of mer- 
 cury, and heated it gently for some time in 
 the tube. An amalgam was obtained, which, 
 by distillation, out of the contact of the 
 atmosphere, afforded a dark- grey metallic 
 film, infusible at the point at which plate- 
 glass softened, and which in the process of 
 the distillation of the mercury, rendered the 
 glass black at its point of contact with it. 
 This film burned with a red light when heat- 
 ed strongly, and became converted into a 
 white powder, which had the character of 
 magnesia. When a portion of magnesium 
 was thrown into water, it sunk to the bot- 
 tom, and effervesced slowly, becoming cover- 
 ed with a white powder. By adding a little 
 muriatic acid to the water, the effervescence 
 was violent. The metal rapidly disappeared, 
 and the solution was found to contain mag- 
 nesia. No direct experiments have as yet 
 been made, to determine the proportions of the 
 elements in magnesia ; but from experiments 
 made on the combination of this substance 
 with sulphuric acid, assuming that they are 
 in single proportions, Dr Wollaston infers 
 the equivalent of magnesia to be 2.46. Hence 
 magnesium will be 1.46. M. Gay Lussac 
 has lately experimented, with his charac- 
 teristic accuracy, on the sulphate of magne- 
 sia, and finds it, when crystallized, a com- 
 pound of dry sulphate of magnesia, 48.57 
 
 water, 51.45 
 
 The equivalent number for the dry sul- 
 
MAG 
 
 MAG 
 
 phate is 7.47129, whence that for magnesia 
 is 2.47 1 29, approaching very nearly to Dr 
 Wollaston’s determination. 
 
 When magnesia is strongly heated in con- 
 tact with 2 volumes of chlorine, this gas is 
 absorbed, and 1 volume of oxygen is disen- 
 gaged. Hence it is evident that there exists 
 a combination of magnesium and chlorine, 
 or a true chloride. The salt called muriate 
 of magnesia, is a compound of the chloride 
 and water. When it is acted on by a strong 
 heat, by far the greatest part of the chlorine 
 unites to the hydrogen of the water, and 
 rises in the form of muriatic acid gas ; while 
 the oxygen of the decomposed water, com- 
 bines with the magnesium to form magnesia. 
 
 Magnesia is often associated with lime in 
 minerals, and their perfect separation be- 
 comes an interesting problem in analysis. 
 M. Longchamp has published a valuable pa- 
 per on the subject, in the 12th volume of the 
 Ann. de Chirn. ct Phi/s. 
 
 He considers subcarbonate of ammonia as 
 the best reagent for separating the two 
 earths. Care must be taken to Alter the so- 
 lution from the calcareous precipitate, shortly 
 after the addition of the subcarbonate. If it 
 stand 1 2 or 1 8 hours, subcarbonate of magne- 
 sia falls with the carbonate of lime. 100 parts 
 of solution of pure muriate of lime gave, with 
 subcarbonate of ammonia, 1.5475 parts of 
 carbonate of lime : 100 of the same solution, 
 previously mixed with muriate of magnesia 
 in excess, yielded 1.5585 parts. Alkaline 
 subcarbonates dissolve the subcarbonate of 
 magnesia ; but caustic potash precipitates 
 magnesia perfectly, either with or without 
 heat. He objects to the method of separat- 
 ing these earths, by first converting them 
 into sulphates ; first, on account of the great 
 difficulty of driving off the water from the 
 sulphates of magnesia; secondly, from the 
 difficult solubility of heated and dry sul- 
 phate of magnesia in water ; and, thirdly, 
 because the sulphate of magnesia is partly 
 decomposed at very high beats. 
 
 Magnesia is chiefly used as an antacid, 
 purgative, and lithontriptic in medicine. 
 When incautiously used for a long time, it 
 may produce very serious evils, of which a 
 remarkable case is narrated by Mr Brande, 
 in the 1st volume of his Journal. A lady 
 was recommended to take magnesia, in con- 
 sequence of some very severe nephritic at- 
 tacks, accompanied witli the passage ol gra- 
 vel. She was desired to take a tea-spoonful 
 every night ; and Henry’s calcined magne- 
 sia was preferred, as that always operated 
 upon the bowels, and “ carried itself ofl,” 
 which other magnesia did not, but, on the 
 contrary, felt heavy and uneasy in the sto- 
 mach. The dose was gradually increased to 
 two tea-spoonfuls, in order to produce effect 
 upon the bowels, which this quantity never 
 failed to do. The symptoms for which it 
 
 *47 
 
 xvas ordered, were soon removed, but the 
 plan was persevered in for two years and a 
 half, with little intermission ; so that as the 
 average weight of a tea- spoonful is at least 
 40 grains, and the average dose was a tea- 
 spoonful and a half, it may be presumed 
 that she took, during the above period, be- 
 tween 9 and 10 pounds troy. “ In the 
 course of the last autumn, she became sensi- 
 ble of a tenderness in the left side, just above 
 the groin, connected with a deep seated 
 tumour, obscurely to be felt upon pressure, 
 and subject to attacks of constipation, with 
 painful spasmodic action of the bowels, tenes- 
 mus, and a highly irritable state of stomach. 
 These attacks recurred every two or three 
 weeks, varying in violence, but requiring the 
 use of active remedies. Several irregular 
 lumps, of a soft light brown substance, were 
 voided, having the appearance of a large mass 
 broken down, and when dry extremely fri- 
 able. A part of each was subjected to ana- 
 lysis, and found to consist entirely of subcar- 
 bonate of magnesia, concreted by the mucus 
 of the bowels, in the proportion of about 40 
 per cent. She was cured by the use of other 
 purgatives.” Another case is mentioned, in 
 which not only large quantities of a concre- 
 tion of a similar description were voided, but 
 upon examination after death, which took 
 place perhaps six months after any magnesia 
 had been taken, a collection, supposed to be 
 from four to six pounds, was found imbedded 
 in the head of the colon, which was of course 
 much distended. 
 
 The most important magnesian salts are 
 described under the acids.* 
 
 * Magnesia (Hydrate of). This mine- 
 ral was found by Dr Bruce of New York, 
 in small veins in serpentine at Hoboken, in 
 New Jersey. Colour white. Massive. Lus- 
 tre pearly. Fracture foliated or radiated. 
 Semi- transparent in the mass; transparent 
 in single folia. Soft, and somewhat elastic. 
 Adheres slightly to the tongue. Sp. gr. 2.18. 
 Soluble in acids. Its constituents are mag- 
 nesia 70, water SO, which approaches to 1 
 prime equivalent of each. — Jameson.* 
 
 * Magnesian Limestone. See Dolomite.* 
 
 * Magnesite. Colour yellowish-grey, or 
 yellowish- white, and marked with spots. It 
 occurs massive, tuberose, reniform, and vesi- 
 cular. Surface rough. Dull. Fracture con- 
 choidal. Fragments rather sharp-edged. 
 Opaque. Scratched by fluor spar, but it 
 scratches calcareous spar. It adheres pretty 
 strongly to the tongue. It feels rather 
 meagre. Streak dull. Rather easily fran- 
 gible. Sp. gr. 2.881. Infusible; but be- 
 fore the blow-pipe it becomes so hard as to 
 scratch glass. Its constituents are, 46 mag- 
 nesia, 51 carbonic acid, 1 alumina, 0.25 
 ferruginous manganese, 0.16 lime, 1 water. 
 — Buckolz . It is found at Ilrubschitz in 
 Moravia, in serpentine rocks.* 
 
MAN 
 
 MAN 
 
 * Magnetic Iron Ore, and Pyrites. See 
 Ores of Iron.* 
 
 * Malachite. See Ores of CorrER. * 
 
 * Malacolite. Sahlite.* 
 
 * Malates and Malic Acid. See Acid 
 (Sorbic). 
 
 * Malleability. See Ductility.* 
 
 * Maltha. The mineral tallow of Kir- 
 wan, said to have been found on the coast of 
 Finland. It resembles wax. Its sp. gr. is 
 
 0.77. It is white, brittle, stains paper like 
 oil, melts with a moderate heat, and burns 
 with a blue flame and much smoke. It dis- 
 solves readily in oil, and imperfectly in hot 
 alcohol.* 
 
 Manganese. A metal of a dull whitish 
 colour when broken, but which soon grows 
 dark by oxidation, from the action of the air. 
 It is hard, brittle, though not pulverizable, 
 and rough in its fracture ; so difficultly fusi- 
 ble, that no heat yet exhibited has caused it 
 to run into masses of any considerable mag- 
 nitude. Its sp. gr. is 8.0. When broken 
 in pieces it falls into a powder by spontane- 
 ous oxidation. 
 
 * Manganese heated in oxygen, or chlo- 
 rine, takes fire and forms an oxide or chlo- 
 ride. It is difficult to decide on the oxides 
 of manganese. 
 
 According to Sir FI. Davy there are two 
 oxides only, the olive and the black ; Mr 
 Brande has three, the olive, dark-red, and 
 black ; M. Thenard has four, the green, the 
 white (in the state of hydrate), the chesnut- 
 brown, and the black ; Berzelius has five, 
 the first grey, the second green, the third 
 and fourth are not well defined, and the fifth 
 is the black. 
 
 In this perplexity it will be prudent to 
 rest on the authority of Sir II. Davy. 
 
 1. The first oxide may be obtained by 
 dissolving common black manganese, in sul- 
 phuric or nitric acid, adding a little sugar, 
 and precipitating by solution of potash. A 
 white powder is obtained, which being heat- 
 ed to redness out of the contact of air, be- 
 comes yellow, puce-coloured, and lastly red- 
 brown. To be preserved, it should lie wash- 
 ed in boiling water, previously freed from 
 air, and then uried by distilling off the mois- 
 ture in a retort filled with hydrogen. The 
 dark olive oxide, when examined in large 
 quantities, appears almost black ; but when 
 spread upon white paper, its olive tint is ap- 
 parent. It takes fire when gently heated, 
 increases in weight, and acquires a browner 
 tint. It slowly absorbs oxygen from the air, 
 even at common temperatures. It dissolves 
 in acids without effervescence. The white 
 powder obtained above, is the hydrated prot- 
 oxide. The different tints which it assumes 
 by exposure to air, are ingeniously supposed 
 by Sir^ II. Davy, to depend on the forma- 
 tion of variable quantities of the black-brown 
 oxide, which probably retains the water con- 
 
 tained in the white hydrate, and is hence 
 deep puce-coloured. 
 
 2. The black peroxide. Its sp. gr. is 4. It 
 does not combine with any of the acids. It 
 yields oxygen when heated ; and by intense 
 ignition passes in a great measure into the 
 protoxide. According to Sir H. Davy, the 
 
 olive oxide consists of 
 
 Manganesium, - 79 
 
 Oxygen, - - 2L 
 
 And the black oxide, of 
 
 Manganesium, - C 9 
 
 Oxygen, about - 31 
 
 lie considers the first as a deutoxide, 
 whence the prime equivalent is inferred to 
 be 7.533. 
 
 7.533 mct.-j- 2. ox. 
 
 -j-20. 
 
 3. 
 
 The olive oxide, 
 
 Or, - - 80. 
 
 The black oxide will be, 7.533 
 Or, - - 71.5 
 
 The compound of the 
 first with water is a 
 deutohydrate, or 7.533 
 The olive oxide becomes green by the ac- 
 tion of potash, whence Sir H. accounts for 
 the mistakes of chemists relative to a green 
 
 O 
 
 + 
 
 4 - 28.5 
 
 2.25 vv. 
 
 oxide. In this case there is a combination. 
 See Cameleon Mineral. 
 
 Dr Thomson pitches on the number 3.5 
 for the atom of manganese, from the re- 
 searches of John and Berzelius. The con- 
 fidence due to his authority in this case may 
 he judged of from the following narrative : 
 “ Dr John acknowledges, that his analyses 
 of these oxides is by no means to be depend- 
 ed on. Berzelius’s statement is rather theo- 
 retical than experimental. Fie even doubts 
 
 of the existence of his first oxide, the onlv 
 
 * 
 
 one he examined ; and he has advanced no 
 proof that there exists any difference between 
 his second and third oxide.” — “ Hence it is 
 evident, that protoxide (the green oxide of 
 John) of manganese is composed of 
 Manganese, 3.5 100 
 
 Oxygen, 1. 28.75 
 
 “ This very nearly coincides with Ber- 
 zelius’s third oxide. And in reality his 
 third oxide is the protoxide of manganese.” 
 System , vol. i. pp. 403 and 404. 5th ed. 
 
 He takes his proportions in the peroxide, 
 from Berzelius’s “theoretical considerations,” 
 to the exclusion of Sir FI. Davy’s “ experi- 
 ments.” The perehloride may be conve- 
 niently obtained by igniting the muriate of 
 manganese. It thus appears as a pale pink- 
 coloured substance, semi-transparent, and in 
 brilliant scales. It is a compound of 7.533 
 metal -j- 9 chlorine, from the experiments 
 of Dr John Davy. Probably a protocblo- 
 ridc may be formed. 
 
 Sir FI. Davy is inclined to believe, that 
 the olive oxide is the only one which enters 
 into combination with vitrifiable substances. 
 
 The salts of manganese have been little 
 studied. They are mostly soluble in water. 
 
MAN 
 
 MAN 
 
 Ferroprussiate of potash gives a 
 
 white 
 
 pitate. 
 
 
 Hydrosulphuret, 
 
 white 
 
 Sulphuretted hydrogen, 
 
 0 
 
 Gallic acid, 
 
 0 
 
 Succinate and benzoate of am. 
 
 0* 
 
 Concentrated sulphuric acid attacks man- 
 ganese, at the same time that hydrogen gas is 
 disengaged. If sulphuric acid be added, and 
 drawn off by distillation several times from 
 the black oxide, by a heat nearly approach- 
 ing to ignition, in a glass vessel, it is found, 
 that oxygen gas is disengaged toward the 
 -end of each process, and part of the oxide is 
 dissolved. The solution of the sulphate 
 made from the metal itself is colourless. If 
 it be made from the black oxide, it is a pur- 
 plish-red ; but this colour is destroyed by 
 the light of the sun, and again restored by 
 removing the solution into the dark. 
 
 Sulphurous acid dissolves the oxide, tak- 
 ing part of its oxygen, which converts it into 
 sulphuric acid, and thus forming a sulphate 
 with the remaining oxide. 
 
 Nitric acid dissolves manganese with effer- 
 vescence, and the escape of nitrous gas. A 
 spongy, black, and friable matter remains, 
 which is a carburet of iron. The solution 
 does not afford crystals. The oxide is more 
 readily soluble in nitrous acid. 
 
 Manganese is dissolved in the usual man- 
 ner by muriatic acid. The solution of man- 
 ganese in muriatic acid scarcely affords crys- 
 tals ; but a deliquescent saline mass by eva- 
 poration, which is soluble in alcohol. 
 
 In the dry way, the oxide of manganese 
 combines with such earths and saline sub- 
 stances as are capable of undergoing fusion 
 in a strong heat. These experiments are 
 most advantageously performed by the blow- 
 pipe, which see. 
 
 This metal melts readily with most of the 
 other metals, but rejects mercury. Gold and 
 iron are rendered more fusible by a due ad- 
 dition of manganese ; and the latter metal is 
 rendered more ductile. Copper becomes less 
 fusible, and is rendered whiter, but of a co- 
 lour subject to tarnish. 
 
 The ore of manganese, which is known in 
 Derbyshire by the name of black wadd, is 
 remarkable for its spontaneous inilammation 
 with oil. It is of a dark brown colour, of a 
 friable earthy appearance, partly in powder, 
 and partly in lumps. If halt a pound ot 
 this be dried before a fire, and afterward 
 suffered to cool for about an hour ; and it 
 be then loosely mixed or kneaded with two 
 ounces of linseed oil ; the whole, in some- 
 thing more than half an hour, becomes gra- 
 dually hot, and at length bursts into flame. 
 This effect wants explanation. It seems, in 
 some measure, to resemble the inflammation 
 of oils by the nitric acid. 
 
 Manganese was used chiefly by glass- 
 makers °aud potters ; but the important dis- 
 
 covery of chlorine has greatly extended its 
 utility. See Bleaching.* 
 
 Manna. Several vegetables afford man- 
 na ; but the ash, the larch, and the alhagi, 
 afford it in the largest quantities. 
 
 The ash which affords manna grows na^ 
 turally in all temperate climates ; but Cala- 
 bria and Sicily appear to be the most natu- 
 ral countries to this tree. 
 
 The manna flows naturally from this tree, 
 and attaches itself to its sides in the form of 
 white transparent drops ; but the extraction 
 of this juice is facilitated by incisions made 
 in the tree during summer. 
 
 Its smell is strong, and its taste sweetish 
 and slightly nauseous ; if exposed on hot 
 coals, it swells up, takes fire, and leaves a 
 light bulky coal. 
 
 Water totally dissolves it, whether hot or 
 cold. If it he boiled with lime, clarified with 
 white of egg, and concentrated by evapora- 
 tion, it affords crystals of sugar. 
 
 Manna affords, by distillation, water, acid, 
 oil, and ammonia : its coal affords fixed al- 
 kali. 
 
 This substance forms the basis of many 
 purgative medicines. 
 
 * Manures. Animal and vegetable matters 
 introduced into the soil, to accelerate vege- 
 tation, and increase the production of crops. 
 They have been used since the earliest pe- 
 riods of agriculture. But the manner in 
 which manures act, the best manner of ap- 
 plying them, and their relative value and 
 durability, were little understood, till the 
 great chemist, who gave new lustre to the 
 whole science, turned his mind to this, its 
 darkest, but most important application. I 
 conceive it wall be doing a service to society, 
 to aid the diffusion of the light springing from 
 the invaluable researches of Sir II. Davy, by 
 inserting the following short abstract from 
 his Agricultural Chemistry. 
 
 The pores in the fibres of the roots of 
 plants are so small, that it is with difficulty 
 they can he discovered by the microscope ; 
 it is not therefore probable, that solid sub- 
 stances can pass into them from the soil. lie 
 tried an experiment on this subject : some 
 impalpable powdered charcoal procured by 
 washing gunpowder, and dissipating the sul- 
 phur by heat, was placed in a phial contain- 
 ing pure water, in which a plant of pepper- 
 mint was growing ; the roots of the plant were 
 pretty generally in contact with the char- 
 coal. The experiment was made in the be- 
 ginning of May 1805; the growth of tlx> 
 plant was very vigorous during a fortnight, 
 when it was taken out of the phial ; the 
 roots were cut through in different parts ; 
 but no carbonaceous matter could be dis- 
 covered in them, nor were the smallest fibrils 
 blackened by charcoal, though this must have 
 been the case had the charcoal been absorbed 
 iu a solid form. 
 
MAN 
 
 No substance is more necessary to plants 
 than carbonaceous matter; and if this can- 
 not be introduced into the organs of plants 
 except in a state of solution, there is every 
 jreason to suppose, that other substances less 
 essential will be in the same case. 
 
 He found, by some experiments made in 
 1804, that plants introduced into strong fresh 
 solutions of sugar, mucilage, tanning prin- 
 ciple, jelly, and other substances, died ; but 
 that plants lived in the same solutions after 
 they had fermented. At that time, he sup- 
 posed that fermentation was necessary to pre- 
 pare the food of plants ; but he afterwards 
 found, that the deleterious effect of the re- 
 cent vegetable solutions, was owing to their 
 Being too concentrated ; in consequence of 
 which the vegetable organs were probably 
 clogged with solid matter, and the transpira- 
 tion by the leaves prevented. In the begin- 
 ning of June, in the next year, he used so- 
 lutions of the same substances, but so much 
 diluted, that there was about only one two- 
 hundredth part of solid vegetable or animal 
 matter in the solutions. Plants of mint grew 
 luxuriantly in all these solutions ; but least 
 so in that of the astringent matter. He wa- 
 tered some spots of grass in a garden with 
 the different solutions separately, and a spot 
 with common water : the grass watered with 
 solutions of jelly, sugar, and mucilage, grew 
 most vigorously ; and that watered with the 
 solution of the tanning principle grew better 
 than that watered -with common water. 
 
 Vegetable and animal substances deposited 
 in the soil, as is shewn by universal experi- 
 ence, are consumed during the process of 
 vegetation ; and they can only nourish the 
 plant by affording solid matters capable of 
 being dissolved by water, or gaseous sub- 
 stances capable of being absorbed by the 
 fluids in the leaves of vegetables ; but such 
 parts of them as are rendered gaseous, and 
 that pass into the atmosphere, must produce 
 a comparatively small effect, for gases soon 
 become diffused tnrough the mass of the sur- 
 rounding air. The great object in the ap- 
 plication of manure, should be to make it 
 afford as much soluble matter as possible to 
 the roots of the plant ; and that in a slow 
 and giadual manner, so that it may be en- 
 tirely consumed in forming its sap and or- 
 ganized parts. 
 
 Whenever manures consist principally of 
 n atter soluble in water, it is evident that 
 their fermentation or putrefaction should be 
 prevented as much as possible ; and the only 
 cases in which these processes can be useful, 
 arc when the manure consists principally of 
 vegetable or animal fibre. The circum- 
 stances necessary for the putrefaction of ani- 
 mal substances, are similar to those required 
 for the fermentation of vegetable substances; 
 a temperature above the freezing point, the 
 presence of water, and the presence of oxy- 
 
 MAN 
 
 gen, at least in the first stage of the pro- 
 cess. 
 
 To prevent manures from -decomposing, 
 they should be preserved dry, defended from 
 the contact of air, and kept as cool as possi- 
 ble. 
 
 All green succulent plants contain saccha- 
 rine or mucilaginous matter, with woody 
 fibre, and readily ferment. They cannot, 
 therefore, if intended for manure, be used 
 too soon after their death. 
 
 Rape cake , which is used with great suc- 
 cess as a manure, contains a large quantity 
 of mucilage, some albuminous matter, and a 
 -small quantity of oil. This manure should 
 be used recent, and kept as dry as possible 
 before it is applied. It forms an excellent 
 dressing for turnip crops ; and is most eco- 
 nomically applied by being thrown into the 
 soil at the same time with the seed. Who- 
 ever wishes to see tin’s practice in its highest 
 degree of perfection, should attend Mr Coke’s 
 annual sheep -shearing, at Holkham. 
 
 Sea-iveeds, consisting of different species of 
 fuci, alga?, and conferva?, are much used as a 
 manure on the sea coasts of Britain and 
 Ireland. This manure is transient in ks 
 effects, and does not last for more than a 
 single crop, which is easily accounted for 
 from the large quantity of water, or the ele- 
 ments of water, it contains. It decays with- 
 out producing heat when exposed to the at- 
 mosphere, and seems, as it were, to melt 
 down and dissolve away. He has seen large 
 heaps entirely destroyed in less than two 
 years, nothing remaining but a little black 
 fibrous matter. 
 
 The best farmers in the west of England 
 use it as fresh as it can be procured ; and the 
 practical results of this mode of applying it 
 are exactly conformable to the theory of its 
 operation. 
 
 When straw is made to ferment, it be- 
 comes a more manageable manure ; but there 
 is likewise, on the whole, a great loss of nu- 
 tritive matter. More manure is perhaps sup- 
 plied for a single crop ; but the land is less 
 improved than it would be, supposing the 
 whole of the vegetable matter could be fine- 
 ly divided and mixed with the soil. 
 
 Lord Meadowbank states, that one part 
 of dung is sufficient to bring three or four 
 parts of peat into a state in which it is fitted 
 to be applied to land ; but of course the 
 quantity must vary according to the nature 
 of the dung and of the peat. In cases in 
 which some living vegetables are mixed with 
 the peat, the fermentation will be more rea- 
 dily effected. 
 
 Manures, from animal substances, in ge- 
 neral, require no chemical preparation to fit 
 them for the soil. The great object of the 
 farmer js to blend them with the earthy con- 
 stituents in a proper state of division, and to 
 prevent their too rapid decomposition. 
 
MAN 
 
 MAN 
 
 Fish forms a powerful manure, in what- 
 ever state it is applied ; but it cannot be 
 ploughed in too fresh, though the quantity 
 should be limited. Mr Young records an 
 experiment, in which herrings spread over a 
 held, and ploughed in for wheat, produced 
 so rank a crop, that it was entirely laid be- 
 fore harvest. 
 
 Hones are much used as a manure in the 
 neighbourhood of London. After being 
 broken, and boiled for grease, they are sold 
 to the farmer. The more divided they are, 
 the more powerful are their effects. The 
 expense of grinding them in a mill would ' 
 probably be repaid by the increase of their 
 fertilizing powers ; and in the state of pow- 
 der they might be used in the drill hus- 
 bandry, and delivered with the seed, in the 
 same manner as rape-cake. 
 
 During the putrefaction of urine the 
 greatest part of the soluble animal matter 
 that it contains is destroved ; it should con- 
 sequently be used as fresh as possible ; but 
 if not mixed with solid matter, it should be 
 diluted with water, as when pure it contains 
 too large a quantity of animal matter to form 
 a proper fluid nourishment for absorption by 
 the roots of plants. 
 
 Putrid urine abounds in ammoniacal salts ; 
 and though less active than fresh urine, is a 
 very powerful manure. 
 
 Amongst excrementitious solid substances 
 used as manures, one of the most powerful 
 is the dung of birds that feed on animal food, 
 particularly the dung of sea birds. The 
 guano , which is used to a great extent in 
 South America, and which is the manure 
 that fertilizes the sterile plains of Peru, is a 
 production of this kind. 
 
 It contains a fourth part of its weight of 
 uric acid, partly saturated with ammonia, 
 and partly with potash ; some phosphoric 
 acid combined with the bases, and likewise 
 with lime. Small quantities of sulphate and 
 muriate of potash, a little fatty matter, and 
 some quartzose sand. 
 
 j\ r ight-soil, it is well known, is a very 
 powerful manure, and very liable to decom- 
 pose. 
 
 The disagreeable smell of night-soil may 
 be destroyed by mixing it with quicklime; 
 and if exposed to the atmosphere in thin 
 layers strewed over with quicklime in fine 
 weather, it speedily dries, is easily pulve- 
 rized, and in this state mav be used in the 
 same manner as rape-cake, and delivered 
 into the furrow with the seed. 
 
 The Chinese, who have more practical 
 knowledge of the use and application of 
 manures than any other people existing, mix 
 their night-soil with one- third of its weight 
 of a fat marie, make it into cakes, and dry it 
 by exposure to the sun. These cakes, we 
 are informed by the French missionaries, 
 
 have no disagreeable smell, and form a com- 
 mon article of commerce of the empire. 
 
 After night-soil, pigeons' dung comes next 
 in order, as to fertilizing power. 
 
 If the pure dung of cattle is to be used as 
 manure, like the other species of dung which 
 have been mentioned, there seems no reason 
 why it should be made to ferment except in 
 the soil; or if suffered to ferment, it should 
 be only in a very slight degree. The grass 
 in the neighbourhood of recently voided 
 dung, is always coarse and dark green ; 
 some persons have attributed this to a noxi- 
 ous quality in unfermenting dung; hut it 
 seems to be rather the result of an excess of 
 food furnished to the plants. 
 
 A slight incipient fermentation is un- 
 doubtedly of use in the dunghill ; for by 
 means of it a disposition is brought on in 
 the woody fibre to decay and dissolve, when 
 it is carried to the land, or ploughed into 
 the soil ; and woody fibre is always in great 
 excess in the refuse of the farm. 
 
 Too great a degree of fermentation is, 
 however, very prejudicial to the composite 
 manure in the dunghill ; it is better that 
 there should be no fermentation at all before 
 the manure is used, than that it should be 
 carried too far. 
 
 Within the last seven years Mr Coke has 
 entirely given up the system formerly adopt- 
 ed on his farm, of applying fermented dung ; 
 and he has found, that his crops have been 
 since as good as they ever were, and that his 
 manure goes nearly twice as far. 
 
 In cases when farm-yard dung cannot be 
 immediately applied to crops, the destructive 
 fermentation of it should be prevented very 
 carefully. 
 
 The surface should be defended as much 
 as possible from the oxygen of the atmos- 
 phere ; a compact marie, or a tenacious clay, 
 offers the best protection against the air ; 
 and before the dung is covered over, or, as 
 it were, sealed up, it should be dried as 
 much as possible. If the dung is found 
 at any time to heat strongly, it should 
 be turned over, and cooled by exposure to 
 air. 
 
 If a thermometer plunged into the dung 
 does not rise to above 100 degrees of Fahr. 
 there is little danger of much aeriform mat- 
 ter Hying off. If the temperature is higher, 
 the dung should be immediately spread 
 abroad. 
 
 When a piece of paper moistened in mu- 
 riatic acid held over the steams arising from 
 a dunghill gives dense fumes, it is a certain 
 test that the decomposition is going too iar, 
 for this indicates that volatile alkali is disen- 
 gaged. 
 
 When dung is to be preserved for any 
 time, the situation in which it is kept is ot 
 importance. It should, it possible, be de- 
 
MAS 
 
 MEL 
 
 fended from the sun. To preserve it under 
 sheds would be of great use ; or to make 
 the site of a dunghill on the north side of a 
 wall. 
 
 Soot, which is principally formed from 
 the combustion of pit- coal or coal, generally 
 contains likewise substances derived from 
 animal matters. This is a very powerful 
 manure. 
 
 It is well fitted to be used in the dry state, 
 thrown into the ground with the seed, and 
 requires no preparation. Lime should never 
 be applied with animal manures, unless they 
 are too rich, or for the purpose of prevent- 
 ing noxious effluvia. It is injurious when 
 mixed with any common dung, and tends to 
 render the extractive matter insoluble. 
 
 “ The doctrine of the proper application 
 of manures from organized substances,” says 
 this eloquent writer, “ offers an illustration 
 of an important part of the economy of na- 
 ture, and of the happy order in which it is 
 arranged. 
 
 “ The death and decay of animal sub- 
 stances tend to resolve organized forms into 
 chemical constituents ; and the pernicious 
 effluvia disengaged in the process, seem to 
 point out the propriety of burying them in 
 the soil, where they are fitted to become the 
 food of vegetables. The fermentation and 
 putrefaction of organized substances in the 
 free atmosphere, are noxious processes ; be- 
 neath the surface of the ground they are 
 salutary operations. In this case, the food 
 of plants is prepared where it.. can be used; 
 and that which would offend the senses and 
 injure the health, if exposed, is converted by 
 gradual processes into forms of beauty and 
 of usefulness ; the fetid gas is rendered a 
 constituent of the aroma of the flower, and 
 what might be poison, becomes nourishment 
 to animals and to man.”* 
 
 * Marble. See Limestone.* 
 
 Marcasite. See Pyrites. 
 
 Marle. See Limestone. 
 
 Marmor Metallicum. Native sulphate 
 of barytes. 
 
 * Mars. The mythological and alche- 
 mistical name of iron.* 
 
 Massicot. Yellow oxide of lead. See 
 Lead. 
 
 Mastic. A resinous substance in the 
 form of tears, of a very pale yellow colour, 
 and farinaceous appearance, having little 
 smell, and a bitter astringent taste. It flows 
 naturally from the tree, but its produce is 
 accelerated by incisions. The lesser turpen- 
 tine tree and the lentiscus afford the mastic 
 of commerce. 
 
 No volatile oil is obtained from this sub- 
 stance when distilled with water. Pure al- 
 cohol and oil of turpentine dissolve it ; water 
 scarcely acts upon it; though by mastica- 
 tion it becomes soft and tough, like wax. 
 When chewed a little while, however, it is 
 
 white, opaque, and brittle, so as not to lie 
 softened again by chewing. The part inso- 
 luble in alcohol much resembles in its pro- 
 perties caoutchouc. It is used in fumiga- 
 tions, in the composition of varnishes, and is 
 supposed to strengthen the gums. 
 
 Matrass. See Laboratory. 
 
 Matrix. The earthy or stony matter 
 which accompanies ores, or envelopes them 
 in the earth. 
 
 * Meadow- ore. Conchoidal Bog Iron- 
 ore.* 
 
 Measures. The English measures ot 
 capacity are according to the following table : 
 One gallon, wine mea- V four ts . 
 
 sure, is equal to ) 
 
 One quart, - two pints. 
 
 One pint, - - 28.875 cubic inches. 
 
 The pint is subdivided by chemists and 
 apothecaries into 1 6 ounces. 
 
 The gallon, quart, and pint, ale measure, 
 are to the measures of the same denomina- 
 tions, wine measure, respectively, as 282 to 
 231. See Acid (Muriatic). 
 
 The Paris foot is equal to 12.789 Eng- 
 lish inches, or to the English foot as 114 
 to 107. For measures of weight, see Ba- 
 lance. 
 
 * Meerschaum. KefFekil of Kirwan. 
 Colours, yellowish and greyish-white. Mas- 
 sive. Dull. Fracture fine earthy. Frag- 
 ments angular. Opaque. Streak slightly 
 shining. Does not soil. Very soft, sectile, 
 but rather difficultly frangible. Adheres 
 strongly to the tongue. Feels rather greasy. 
 Sp.gr. 1.2 to 1.6. Before the blow-pipe, 
 it melts on the edges into a white enamel. 
 Its constituents are, silica 41.5, magnesia 
 18.25, lime 0.50, water and carbonic acid 39. 
 — Klaproth. It occurs in the veins in the ser- 
 pentine of Cornwall. When first dug, it is 
 soft, greasy, and lathers like soap. Hence 
 the Tartars use it for washing clothes. In 
 Turkey it is made into tobacco-pipes, from 
 meerschaum dug in Natolia, and near 
 Thebes. See Jameson’s mineralogy for an 
 entertaining account of the manufacture.* 
 
 * IVIeionite. Prismato-pyramidal felspar. 
 Colour, greyish-white. Massive, but more 
 frequently crystallized. The primitive form 
 is a pyramid, in which the angles are 136° 
 22', 63° 22'. Its secondary forms are, rec- 
 tangular four-sided prisms, variously acumi- 
 nated or truncated. The crystals are small, 
 smooth and splendent. Lustre vitreous. 
 Cleavage, double rectangular. Transpa- 
 rent. Harder than common felspar, but 
 softer than quartz. Easily frangible. Sp. 
 gr. 2.6. Easily fusible before the blow- 
 pipe, with intumescence. It occurs along 
 with ceylanitc and nepheline, in granular 
 limestone, at Monte Somma near Naples.* 
 
 * Melanite. Colour, velvet-black. In 
 roundish giains, but more frequently crys- 
 tallized, in a rhomboidal dodecahedron, trim- 
 
MEN 
 
 MER 
 
 cated on all the edges. Surface of the grains 
 rough and uneven ; that of the crystals shin- 
 ing. Fracture flat conchoidal. Opaque. As 
 hard as quartz. Rather easily frangible. 
 Sp. gr. 3.73. Its constituents are, silica 35.5, 
 alumina 6, lime 32.5, oxide of iron 25.25, 
 oxide of manganese 0.4, loss 0.35. It is 
 found in a rock at Frescati near Rome, and 
 in the basalt of Bohemia.* 
 
 * Mellates. Compounds of mellitic acid 
 with the salifiable bases.* 
 
 * Meli.ite, or Honey -stone. Colour 
 lioney-yellow. Rarely massive. Crystalliz- 
 ed. Its primitive figure is a pyramid of 
 118° 4', and 95° 22'. The secondary figures 
 are ; the primitive, truncated on the apices ; 
 on the apices and angles of the common 
 base ; and the angles on the common base 
 bevelled. Externally smooth and splendent. 
 Cleavage pyramidal. Fracture perfect con- 
 choidal. Semi-transparent. Refracts double, 
 in the direction of the pyramidal plane. 
 Harder than gypsum, but softer than cal- 
 careous spar. Brittle. Sp. gr. 1.4 to 1.6. 
 Before the blow-pipe, it becomes white and 
 opaque, with black spots, and is at length 
 reduced to ashes ; when heated in a close 
 vessel, it becomes black. It is slightly resino- 
 electric by friction. Its constituents are, 
 alumina 1 6, mellitic acid 46, water of crys- 
 tallization 38. — Klaproth. It occurs super- 
 imposed on bituminous wood, and earth coal, 
 and is usually accompanied with sulphur. 
 It has hitherto been found only at Artern in 
 Thuringia.* 
 
 * Melting. See Caloric, change oj' 
 state.* 
 
 * Menaciianite. Colour grevish-black. 
 
 Occurs only in very small flattish angular 
 grains, which have a rough glimmering sur- 
 face. Glistening; adamantine, or semi- me- 
 tallic lustre. Cleavage, imperfect. Opaque. 
 Not so hard as magnetic iron- sand. Brittle. 
 Retains its colour in the streak. Sp. gr. 
 4.3 to 4.4. It is attractible by the magnet, 
 but in a much weaker degree, than magnetic 
 iron-stone. Infusible without addition. It 
 tinges borax of a greenish colour. Its con- 
 stituents are oxide of iron 51, oxide of titani- 
 um 45.25, oxide of manganese 0.25, silica 
 3.5. — Klaproth. It is found, accompanied 
 
 with fine quartz-sand, in the bed of a rivulet 
 which enters the valley of Manaccan in Corn- 
 wall.* 
 
 * Menilite. A sub-species of indivisible 
 quartz. It is of two kinds; the brown and 
 the grey. Brown menilite is chesnut-brown, 
 inclining to liver-brown. It occurs tuberose. 
 External surface, rough and dull ; internal 
 glistening. It has sometimes a tendency to 
 lamellar distinct concretions. Fracture very 
 flat conchoidal. Translucent on the edges. 
 Scratches glass. Easily frangible. Sp. gr. 
 2.17. Infusible. Its constituents are, silica 
 8J.5, alumina 1, lime 0.5, oxide of iron 0.5, 
 
 water and carbonaceous matter 1 1.0. Found 
 at Menil Montant near Paris, imbedded in 
 adhesive slate, as flint is in chalk. 
 
 Grey Menilite. Colour yellowish-grey. 
 Tuberose. Internally glimmering or dull. 
 Fracture as above. Semi-hard in a high 
 degree. Easily frangible. Sp. gr. 2.3. It 
 occurs at Argenteuil near Paris, imbedded 
 in a clayey marie. — Jameson.* 
 
 * Mephitic Acid. Carbonic Acid.* 
 
 Menstruum. A word synonymous with 
 
 solvent. 
 
 Mercury is distinguished from all other 
 metals by its extreme fusibility, which is 
 such, that it does not take the solid state 
 until cooled to the thirty-ninth degree below 
 0 on Fahrenheit’s thermometer ; and of 
 course it is always fluid in the temperate cli- 
 mates of the earth. Its colour is white, and 
 rather bluer than silver. In the solid state 
 it is malleable its specific gravity is IS. 6. 
 It is volatile, and rises in small portions at 
 the common temperature of the atmosphere, 
 as is evinced by several experiments, more 
 especially in a vacuum, such as obtains in the 
 upper part of a barometer tube. At the 
 temperature of about 65 6° it boils rapidly, 
 and rises copiously in fumes. When expos- 
 ed to such a heat as may cause it to rise 
 quickly in the vaporous form, or about 600°, 
 it gradually becomes converted into a red 
 oxide, provided oxygen be present. This 
 was formerly known by the name of pre- 
 cipitate per se. A greater heat, however, 
 revives this metallic oxide, at the same time 
 that the oxygen is again extricated. Ten 
 days or a fortnight’s constant heat is required 
 to convert a few grains of mercury into pre- 
 cipitate per se in the small way. 
 
 From this volatility of mercury, it is com- 
 monly purified by distillation. 
 
 Mercury is not perceptibly altered by mere 
 exposure to the air ; though by long agita- 
 tion, with access of air, it becomes converted 
 into a black powder or oxide, which gives 
 out oxygen by heat, the metal being at the 
 same time revived. 
 
 * When calomel or protochloride of mer- 
 cury is acted on by potash- water, it yields 
 the pure black protoxide ; and when corro- 
 sive sublimate or the deutoehloride is treated 
 in the same way, it affords the red deutoxide. 
 The former oxide, heated with access of air, 
 slowly changes into the latter. The consti- 
 tuents of the first arc 100 metal -}- 4 oxy- 
 gen ; of the second 100 + 8. Hence the 
 prime equivalent of mercury is 25. At a 
 red-heat both oxides emit their oxygen, and 
 pass to the metallic state. A moderate heat 
 converts the black oxide, partly into running 
 mercury, and partly into red oxide. The 
 deutoxide, as usually prepared from the ni- 
 
 f The reader will find an ample account of the 
 freezing of quicksilver in Dr Illagden’s History, vol. 
 Ixxxiii. of the Philosophical Transactions. 
 
MER 
 
 MER 
 
 irate by gentle calcination, is in brilliant red 
 scales, which become of an orange hue when 
 finely comminuted. It frequently contains 
 a little undecomposed subnitrate. 
 
 By triturating mercury with unctuous or 
 viscid matters, it is changed partly into prot- 
 oxide, and parily into very minute globules. 
 Bv exposing mercurial ointment to a mode- 
 rate heat, the globules fall down, while a 
 proportion of the oxide remains combined 
 with the grease. This light grey chemical 
 compound is supposed to possess all the vir- 
 tues of the dark coloured ointment, and to 
 be cheaper and more convenient in the ap- 
 plication. Mr Donovan, who introduced it, 
 forms it directly by exposing a mixture of 1 
 part of black oxide, and 24 parts of hog’s- 
 lard, to a heat of 350°, for about two hours. 
 
 Red oxide of mercury is acrid and poison- 
 ous, and carries these qualities into its saline 
 combinations. The protoxide is relatively 
 bland, and is the basis of all the mild mercu- 
 rial medicines. 
 
 1. When mercury is heated in chlorine, it 
 burns with a pale red flame, and the sub- 
 stance called corrosive sublimate is formed. 
 This deutochloride may also be formed by 
 mixing together equal parts of dry bi-deuto- 
 sulphate of mercury and common salt, and 
 subliming. The corrosive sublimate rises, 
 and incrusts the top of the vessel, in the 
 form of a beautiful white semi-transparent 
 mass, composed of very small prismatic 
 needles. It may be obtained in cubes, and 
 rhomboidal prisms, or quadrangular prisms, 
 with their sides alternately narrower, and 
 terminated by dihedral summits. Its sp. gr. 
 is 5.14. Its taste is acrid, stypto- metallic, 
 and eminently disagreeable. It is a deadly 
 poison. Twenty parts of cold water dissolve 
 it, and less than one of boiling water. 100 
 parts of alcohol at the boiling temperature 
 dissolve 88 of corrosive sublimate ; and at 
 70° they dissolve 37.5 parts. The constitu- 
 ents of this chloride are, — 
 
 Mercury, 25 73.53 
 
 Chlorine, 9 26.47 
 
 It may be recognized by the following 
 characters : It volatilizes in white fumes, 
 which seem to tarnish a bright copperplate, 
 but really communicate a coating of metal- 
 lic mercury, which appears glossy wdiite on 
 friction. When caustic potash is made to 
 act on it, with heat, in a glass tube, a red 
 colour appears, which by gentle ignition va- 
 nishes, and metallic mercury is then found 
 to line the upper part of the tube in minute 
 globules. Solution of corrosive sublimate 
 reddens litmus paper ; but changes syrup of 
 violets to green. Bicarbonate of potash 
 throws down from it a deep brick-red 
 precipitate, from which metallic mercury 
 rnay be procured by heating it in a tube. 
 •Caustic potash gives a yellow precipitate ; 
 
 but if the solution be very dilute, a white 
 cloud only is occasioned, which becomes 
 yellowish-red on subsidence. Lime-water 
 causes a deep yellow, verging on red. Wa- 
 ter of ammonia forms a white precipitate, 
 which becomes yellow on being heated. 
 With sulphuretted hydrogen and hydrosul- 
 pliurets, a black or blackish-brown precipi- 
 tate appears. Nitrate of silver throws down 
 the curdy precipitate characteristic of muria- 
 tic acid ; and the protomuriate of tin gives 
 a white precipitate. The proper antidote to 
 the poison of corrosive sublimate, is the 
 white of egg or albumen, which converts it 
 into calomel. Sulphuretted hydrogen water 
 may also be employed, along with emetics. 
 From six to twelve grains were the mortal 
 doses employed by Orfila in his experiments 
 on dogs. They died in horrible convulsions 
 generally in tw'O hours. But when, with the 
 larger quantity, the whites of eight eggs 
 were throwm into the stomach, the animals 
 soon recovered, after vomiting. Corrosive 
 sublimate, digested with albumen for some 
 time, was given in considerable doses, with 
 impunity. The instructions given under 
 arsenic, for examination of the bowels of a 
 person supposed to be poisoned, are equally 
 applicable to poisoning by corrosive subli- 
 mate ; and the appearances are much the 
 same. 
 
 2. Protochloride of mercury, mercurius 
 dulcis, or calomel , is usually formed from the 
 deutochloride, by triturating four parts of the 
 latter w ith three of quicksilver, till the glo- 
 bules disappear, and subjecting the mixture 
 to a subliming heat. By levigating and 
 edulcorating wdth warm water the sublimed 
 greyish-w'hite cake, the portion of soluble 
 corrosive sublimate wdiich had escaped de- 
 composition is removed. It may also be 
 made by adding solution of protonitrate of 
 mercury to solution of common salt. The 
 protochloride or calomel precipitates. The 
 following is the process used at Apotheca- 
 ries’ Hall, London : 50 lbs. of mercury are 
 boiled with 70 lbs. of sulphuric acid, to dry- 
 ness, in a cast-iron vessel ; 62 lbs. of the dry 
 salt are triturated with 40 § lbs. of mercury, 
 until the globules disappear, and 34 lbs. of 
 common salt are then added. This mixture 
 is submitted to heat in earthen vessels, and 
 from 95 to 100 lbs. of calomel are the re- 
 sult. It is w'ashed in large quantities of dis- 
 tilled water, after having been ground to a 
 fine and impalpable powder. 
 
 When protochloride of mercury is very 
 slowly resublimed, four-sided prisms, termi- 
 nated by pyramids, are obtained. It is near- 
 ly tasteless and insoluble, and is purgative in 
 doses of five or six grains. Its sp. gr. is 
 7.176. Exposure to air darkens its surface. 
 When two pieces are rubbed in the dark, 
 they phosphoresce. It is not so volatile .'is 
 the deutochloride. Nitric acid dissolves 
 
MER 
 
 MER 
 
 
 calomel, converting it into corrosive subli- 
 mate. Protochloride of mercury is com- 
 posed of 
 
 Mercury, 25. 84.746 
 
 Chlorine, 4.5 15.254 
 
 We have also two sulphurcts of mercury; 
 the black or ethiops mineral; and the red or 
 cinnabar. 
 
 The lirst is easily made by heating or tri- 
 turating the ingredients together, or by add- 
 ing a hydrosulphuret of alkali to a mercurial 
 saline solution. It consists of 
 
 Mercury, 25 92.6 
 
 Sulphur, 2 7.4 
 
 'When the black sulphuret is exposed to a 
 red-heat in earthen pots, cinnabar sublimes, 
 which, when reduced to powder, is of a beau- 
 tiful red colour, and is used as a pigment under 
 the name of vermilion. Its sp. gr. is about 
 10. It is insoluble, insipid, and burns with 
 a blue flame. If it be mixed with half its 
 weight of iron filings, and distilled in a re- 
 tort, it yields pure mercury. It is deutosul- 
 phuret, and consists of 
 
 Mercury, 25 86.2 
 
 Sulphur, 4 15.8 
 
 The salts of mercury have the following 
 general characters : — 
 
 O 
 
 1. A dull red-heat volatilizes them. 
 
 2. Ferroprussiate of potash gives a white 
 precipitate. 
 
 3. Hydrosulphuret, black. 
 
 4. Muriate of soda, with the protosalts, 
 white. 
 
 5. Gallic acid, orange-yellow. 
 
 6. Plate of copper, quicksilver.* 
 
 The sulphuric acid does not act on this 
 metal, unless it be well concentrated and 
 boiling. For this purpose mercury is poured 
 into a glass retort, with nearly twice its weight 
 of sulphuric acid. As soon as the mixture 
 is heated, a strong effervescence takes place, 
 sulphurous acid gas escapes, the surface of 
 the mercury becomes white, and a white 
 powder is produced : when the gas ceases to 
 come over, the mercury is found to be con- 
 verted into a white, opaque, caustic, saline 
 mass, at the bottom of the retort, which 
 weighs one-third more than the mercury, 
 and is decomposed by heat. Its fixity is 
 considerably greater than that of mercury 
 itself. If the heat be raised, it gives out a 
 considerable quantity of oxygen, the mercury 
 being at the same time revived. 
 
 Water resolves it into two salts, the bisul- 
 phate and subsulphate; the latter is ot a yel- 
 low 'colour. Much washing is required to 
 produce this colour, if cold water be used ; 
 but if a large quantity of hot water be poured 
 on, it immediately assumes a bright lemon 
 colour. In this state it is called turbith 
 mineral. The other affords by evaporation 
 small, needly, deliquescent crystals. 
 
 The fixed alkalis, magnesia, and lime, 
 precipitate oxide ot mercury from its solu- 
 
 tions ; these precipitates are reducible in 
 closed vessels by mere heat without addition. 
 
 The nitric acid rapidly attacks and dis- 
 solves mercury, at the same time that a large 
 quantity of nitrous gas is disengaged ; and 
 the colour of the acid becomes green during 
 its escape. Strong nitric acid takes up its 
 own weight of mercury in the cold ; and 
 this solution will bear to be diluted with 
 water. But if the solution be made with 
 the assistance of heat, a much larger quan- 
 tity is dissolved ; and a precipitate will be 
 afforded by the addition of distilled water, 
 which is of a yellow colour if the water be 
 hot, or white if it be cold ; and greatly re- 
 sembles the turbith mineral produced with 
 sulphuric acid : it has accordingly been call- 
 ed nitrous turbith. 
 
 All the combinations of mercury and ni- 
 tric acid are very caustic, and form a deep i 
 purple or black spot upon the skin. They 
 afford crystals, which differ according to the I 
 state of the solution. When nitric acid has < 
 taken up as much mercury as it can dissolve 
 by heat, it usually assumes the form of a 
 white saline mass. When the combination 
 of nitric acid and mercury is exposed to a 
 gradual and long continued low heat, it gives 
 out a portion of nitric acid, and becomes 
 converted into a bright red oxide, still retain- 
 ing a small portion of acid. This is known 
 by the name of red precipitate, and is much 
 used as an escharotic. 
 
 When red precipitate is strongly heated, 
 a large quantity of oxygen is disengaged, 
 together with some nitrogen, and the mer- 
 cury is sublimed in the metallic form. 
 
 Nitrate of mercury is more soluble in hot 
 than cold water, and affords crystals by cool- 
 ing. It is decomposed by the affusion of a 
 large quantity of water, unless the acid be in 
 excess. 
 
 A fulminating preparation of mercury was 
 discovered by Mr Howard. A hundred 
 grains of mercury are to be dissolved by heat 
 in an ounce and half by measure of nitric 
 acid. This solution being poured cold into 
 two ounces by measure of alcohol in a glass 
 vessel, heat is to be applied, till effervescence 
 is excited. A white vapour undulates on 
 the surface, and a powder is gradually preci- 
 pitated, which is immediately to be collected 
 on a filter, well washed, and cautiously dried 
 with a very moderate heat. This powder 
 detonates loudly by gentle heat, or slight 
 friction. 
 
 The acetic and most other acids combine 
 with the oxide of mercury, and precipitate it 
 from its solution in the nitric acid. 
 
 When one part of native sulphuret of an- 
 timony is triturated or accurately mixed with 
 two parts of corrosive sublimate, and exposed 
 to distillation, the chlorine combines with 
 the antimony, and rises in the form ot the 
 compound called butter of antimony ; while 
 
MER 
 
 MET 
 
 the sulphur combines with the mercury, and 
 forms cinnabar. If antimony be used instead 
 of the sulphuret, the residue which rises last 
 consists of running mercury, instead of cin- 
 nabar. 
 
 Mercury, being habitually fluid, very rea- 
 dily combines with most of the metals, to 
 which it communicates more or less of its 
 fusibility. When these metallic mixtures 
 contain a sufficient quantity of mercury to 
 render them soft at a mean temperature, 
 they are called amalgams. 
 
 It very readily combines with gold, silver, 
 lead, tin, bismuth, and zinc ; more difficultly 
 with copper, arsenic, and antimony ; and 
 scarcely at all with platina or iron: it does 
 not unite with nickel, manganese, or cobalt ; 
 and its action on tungsten and molybdena is 
 not known. Looking-glasses are covered 
 on the back surface with an amalgam of tin. 
 See Silvering. 
 
 Some of the uses of mercury have already 
 been mentioned in the present article. The 
 amalgamation of the noble metals, water- 
 gilding, the making of vermilion, the silver- 
 ing of looking-glasses, the making of barome- 
 ters and thermometers, and the preparation 
 of several powerful medicines, are the prin- 
 cipal uses to which this metal is applied. 
 
 Scarcely any substance is so liable to adul- 
 teration as mercury, owing to the property 
 which it possesses of dissolving completely 
 some of the baser metals. This union is so 
 strong, that they even rise along with the 
 quicksilver when distilled. The impurity of 
 mercury is generally indicated by its dull 
 aspect; by its tarnishing, and becoming co- 
 vered with a coat of oxide, on long exposure 
 to the air ; by its adhesion to the surface of 
 glass ; and, w hen shaken with w r ater in a 
 bottle, by the speedy formation of a black 
 powder. Lead and tin are frequent impuri- 
 ties, and the mercury becomes capable of 
 taking up more of these, if zinc or bismuth 
 be previously added. In order to discover 
 lead, the mercury may be agitated with a 
 little water, in order to oxidize that metal. 
 Pour off* the water, and digest the mercury 
 with a little acetic acid. This will dissolve 
 the oxide of lead, which will be indicated by 
 a blackish precipitate with sulphuretted wa- 
 ter. Or to tliis acetic solution add a little 
 sulphate of soda, which will precipitate a sul- 
 phate of lead, containing, when dry, 72 per 
 cent of metal. If only a very minute quan- 
 tity of lead be present in a large quantity of 
 mercury, it may be detected by solution in 
 nitric acid, and the addition of sulphuretted 
 water. A dark brown precipitate will ensue, 
 and will subside if allowed to stand a few 
 days. One part of lead may thus be sepa- 
 rated from 15263 parts of mercury. l>is- 
 mutli is detected by pouring a nitric solu- 
 tion, prepared without heat, into distilled 
 
 water; a white precipitate will appear if this 
 metal be present. Tin is manifested, in like 
 manner, by a weak solution of nitro-muriate 
 of gold, which throw's down a purple se- 
 diment; and zinc by exposing the metal to 
 beat. 
 
 The black oxide is rarely adulterated, as it 
 would be difficult to find a substance well 
 suited to this purpose. If well prepared, it 
 may be totally volatilized by heat. 
 
 The red oxide of mercury by nitric acid is 
 very liable to adulteration with red lead. It 
 should be totally volatilized by heat. 
 
 Red sulphuret of mercury is frequently 
 adulterated with red lead; which may be 
 detected by heat. 
 
 Corrosive muriate of mercury. If there be 
 any reason to suspect arsenic in this salt, the 
 fraud may be discovered as follows : Dis- 
 solve a small quantity of the sublimate in 
 distilled water; add a solution of carbonate 
 of ammonia till the precipitation ceases, and 
 filter the solution. If, on the addition of 
 a few drops of ammoniated copper to this 
 solution, a precipitate of a yellowish-green 
 colour be produced, the sublimate contains 
 arsenic. 
 
 Sub-muriate of mercury, or calomel, 
 should be c6mpletely saturated with mer- 
 cury. This may be ascertained by boiling, 
 for a few minutes, one part of calomel with 
 a thirty-second part of muriate of ammonia 
 in ten parts of distilled water. When car- 
 bonate of potash is added to the filtered so- 
 lution, no precipitation will ensue, if the 
 calomel be pure. This preparation, when 
 rubbed in an earthen mortar w'ith pure am- 
 monia, should become intensely black, and 
 should exhibit nothing of an orange hue. 
 
 * Mesotyfe. Prismatic zeolite. This 
 species of the genus zeolite, is divided by 
 Professor Jameson into three sub-species, 
 the fibrous zeolite, natrolite, and mealy zeo- 
 lite ; which see.* 
 
 * Metals. The most numerous class of 
 undecompounded chemical bodies, distin- 
 guished by the following general charac- 
 ters : — 
 
 1. They possess a peculiar lustre, which 
 continues in the streak, and in their smallest 
 fragments. 
 
 2. They are fusible by heat ; and in fusion 
 retain their lustre and opacity. 
 
 3. They are all, except selenium, excellent 
 conductors both of electricity and caloric. 
 
 4. Many of them may be extended under 
 the hammer, and are called malleable; or 
 under the rolling press, and are called lamin- 
 able; or drawn into wire, and are called 
 ductile. This capability of extension, de- 
 pends in some measure on a tenacity peculiar 
 to the metals, and which exists in* the dif- 
 ferent species with very different degrees of 
 force. See Cohesion. 
 
MET 
 
 MET 
 
 5. \Y lien their saline combinations are 
 electrized, the metals separate at the resino- 
 electric or negative pole. 
 
 6 . When exposed to the action of oxygen, 
 chlorine, or iodine, at an elevated tempera- 
 ture, they generally take fire, and, combin- 
 ing with one or other of these three element- 
 ary dissolvents in definite proportions, are 
 converted into earthy or saline looking bo- 
 dies, devoid of metallic lustre and ductility, 
 called oxides, chlorides, or iodides. 
 
 7. They are capable of combining in their 
 melted state with each other, in almost every 
 proportion, constituting the important order 
 of metallic alloys; in which the character- 
 istic lustre and tenacity are preserved. See 
 Allot. 
 
 8. From this brilliancy and opacity con- 
 jointly, they reflect the greater part of the 
 light which falls on their surface, and hence 
 form excellent mirrors. 
 
 9. Most of them combine in definite pro- 
 portions with sulphur and phosphorus, form- 
 ing bodies frequently of a semi-metallic as- 
 pect ; and others unite with hydrogen, car- 
 bon and boron, giving rise to peculiar gase- 
 ous or solid compounds. 
 
 10. Many of the metals are capable of as- 
 suming, by particular management, crystal- 
 line forms ; which are, for the most part, 
 either cubes or octohedrons. 
 
 The relations of the metals to the various 
 objects of chemistry, are so complex and 
 diversified, as to render their classification a 
 task of peculiar difficulty. I have not seen 
 any arrangement to which important objec- 
 tions may not be offered ; nor do I hope to 
 present one which shall be exempt from cri- 
 ticism. The main purposes of a methodical 
 distribution are to facilitate the acquirement, 
 retention, and application of knowledge. 
 With regard to metals in general, I conceive 
 these purposes may be to a considerable ex- 
 
 tent attained, by beginning with those which 
 are most eminently endowed with the cha- 
 racters of the genus, which most distinctly* 
 possess the properties that constitute their 
 value in common life, and which caused the 
 early inhabitants of the earth to give to the 
 first metallurgists a place in mythology* 
 Happy had their idolatry been always con- 
 fined to such real benefactors ! 
 
 Inventas aut qui vitam excoluere per artes^ 
 
 Quique sui memores, alios fecere merendo. 
 
 By arranging metals according to the de- 
 gree in which they possess the obvious qua- 
 lities of unaiterability, by common agents, te- 
 nacity and lustre, we also conciliate their most 
 important chemical relations, namely, those to 
 oxygen, chlorine and iodine; since their me- 
 tallic pre-eminence is, popularly speaking, in- 
 versely as their affinities for these dissolvents. 
 In a strictly scientific view, their habitudes 
 with oxygen, should perhaps be less regarded 
 in their classification, than with chlorine, for 
 this element has the most energetic attrac- 
 tions for the metals. But, on the other 
 hand, oxygen, which forms one- fifth of the 
 atmospheric volume, and eight-ninths of the 
 aqueous mass, operates to a much greater 
 extent among metallic bodies, and incessant- 
 ly modifies their form, both in nature and 
 art. Now the order we propose to follow 
 will indicate very nearly their relations to 
 oxygen. As we progressively descend, the 
 influence of that beautiful element progres- 
 sively increases. Among the bodies near 
 the head, its powers are subjugated by the 
 metallic constitution ; but among those near 
 the bottom, it exercises an almost despotic 
 sway, which Volta’s magical pile, directed 
 by the genius of Davy, can only suspend for 
 a season. The emancipated metal soon re- 
 lapses under the dominion of oxygen. 
 
MET 
 
 MET 
 
 General Table of the Metals . 
 
 
 
 
 Colour of precipitates by 
 
 NAMES. 
 
 Sp. gr. 
 
 Precipitants. 
 
 Ferroprussiate 
 of potash. 
 
 Infusion of galls. 
 
 Hydrosul- 
 
 phurets. 
 
 Sulphuretted 
 
 hydrogen. 
 
 1 Platinum 
 
 2 Gold 
 
 3 Silver 
 
 4 Palladium 
 
 5 Mercury 
 
 6 Copper 
 
 7 Iron 
 
 8 Tin 
 
 9 Lead 
 
 10 Nickel 
 
 11 Cadmium 
 
 12 Zinc 
 
 13 Bismuth 
 
 14 Antimony 
 
 15 Manganese 
 
 16 Cobalt 
 
 17 Tellurium 
 
 18 Arsenic 
 
 19 Chromium 
 
 20 Molybdenum 
 
 21 Tungsten 
 
 22 Columbium 
 
 23 Selenium 
 
 24 Osmium 
 
 25 Rhodium 
 
 26 Iridium 
 
 27 Uranium 
 
 28 Titanium 
 
 29 Cerium 
 
 30 Wodanium 
 
 31 Potassium 
 
 32 Sodium 
 
 33 Lithium 
 
 34 Calcium 
 
 35 Barium 
 
 36 Strontium 
 
 37 Magnesium 
 
 38 Yttrium 
 
 39 Glucinum 
 
 40 Aluminum 
 
 41 Thorinum 
 
 42 Zirconium 
 
 43 Silicium 
 
 21.47 
 
 19.30 
 
 10.45 
 
 11.8 
 
 13.6 
 
 8.9 
 7.7 
 
 7.29 
 
 11.35 
 
 8.4 
 8.6 
 
 6.9 
 9.88 
 
 6.70 
 
 8. 
 
 8.6 
 
 6.115 
 
 C8.35 ? 
 75. 76 ? 
 5.90 
 8.6 
 
 17.4 
 5.6? 
 
 4.3? 
 
 ? 
 
 10.65 
 
 18.68 
 
 0.0 
 
 ? 
 
 ? 
 
 11.47 
 
 0.865 
 
 0.972 
 
 Mur. amiKion. 
 
 C Sulph. iron 
 £ Nitr. mercury 
 Common salt 
 Prus. mercury 
 Common salt. 
 
 Heat 
 
 Iron 
 
 Succin. soda 
 with perox. 
 
 Corr. sublim. 
 
 Sulph. soda 
 Sulph. potash ? 
 Zinc 
 
 Aik. carbonates 
 Water 
 f Water 
 7 Zinc 
 Tartr. pot. 
 
 Aik. carbonates 
 C Water 
 7_ Antimony 
 
 Nitr. lead 
 
 Do. 
 
 Do.? 
 
 Mur. lime ? 
 Zinc or inf. galls 
 CIron 
 
 (.Sulphite aram. 
 
 Mercury- 
 
 Zinc? 
 
 Do.? 
 
 Ferropr. pot. 
 Inf. galls 
 Oxal. aram. 
 Zinc 
 
 CMur. plat. 
 (.Tart, acid 
 
 0 
 
 Yellowish-white 
 
 White 
 Deep orange 
 White passing 
 to yellow 
 Red-brown 
 Blue, or white 
 passing to blue 
 
 White 
 
 Do. 
 
 Do. 
 
 Do. 
 
 Do. 
 
 Do. 
 
 With dilute so- 
 lutions white 
 White 
 
 Brown-yellow 
 
 0 
 
 White 
 
 Green 
 Brown 
 Dilute acids 
 Olive 
 
 0 
 
 0 
 
 Brown-red 
 
 Grass-green 
 
 Milk-white 
 
 Pearkgrey 
 
 0 
 
 0 
 
 Green ; met. 
 Yel.-brown 
 
 Orange-yellow 
 
 Brown 
 Protox. 0 
 Perox. black 
 
 0 
 
 White 
 Grey- white 
 0 
 0 
 
 Yellow 
 
 White from wa- 
 ter 
 
 0 
 
 Yellow- white 
 Yellow 
 
 Brown 
 Deep brown 
 
 Orange 
 
 Purple passing to 
 deep blue 
 
 0 
 
 Chocolate 
 
 Red-brown 
 
 0 
 
 0 
 
 0 
 
 Yellow 
 
 Black 
 
 Blackish-brown 
 
 Brownish-black 
 
 Rack 
 
 Black 
 
 ! } rotox. black 
 3 erox. yellow 
 ! Black 
 Do. 
 
 Orange-yellow 
 
 White 
 
 Black-brown 
 
 Orange 
 
 White 
 
 Black 
 
 Blackish 
 
 Yellow 
 
 Green 
 
 Chocolate 
 
 0 
 
 Brown -yellow 
 
 Grass-green 
 
 White 
 
 0 
 
 Black met. powd. 
 
 Yellow 
 
 Black 
 
 Black-brown 
 
 Black 
 
 Do. 
 
 0 
 
 Brown 
 
 Black 
 
 0 
 
 Orange-yellow 
 Yellowish-white 
 l Black-brown 
 
 Orange 
 
 Vlilkiness 
 
 0 
 
 Yellow 
 
 Brown 
 
 0 
 
 0 
 
 0 
 
 0 
 
 The first 1 2 are malleable ; and so are the 
 31st, 32d, and 33d in their congealed state. 
 
 The first 16 yield oxides, which are neutral 
 salifiable bases. 
 
 The metals 17, 18, 19, 20, 21, 22, and 
 23, are acidifiable by combination with oxy- 
 gen. Of the oxides of the rest, up to the 
 31st, little is known. The remaining me- 
 tals form, with oxygen, the alkaline and 
 earthy bases. 
 
 The order of their affinity for oxygen, as 
 far as it has been ascertained, is stated in the 
 table of Elective Attraction of oxygen and 
 the metals. 
 
 We shall now give an example of the 
 method of analyzing a metallic alloy, of sil- 
 ver, copper, lead, bismuth, and tin. 
 
 Let it be dissolved, with the aid of heat, 
 
 in an excess of nitric acid, sp. gr. 1.23. 
 Evaporate the solution almost to dryness, 
 and pour water on the residuum. We shall 
 thus obtain a solution of the nitrates of sil- 
 ver, copper, and lead, while the oxides of tin 
 and bismuth will be left at the bottom. By 
 exposing the latter mixture, to the action of 
 nitric acid, the oxide of bismuth will be se- 
 parated from that of tin. To determine the 
 proportions of the other metals, we pour first 
 into the hot and pretty dilute solution, mu- 
 riatic acid, which will throw down the silver. 
 After filtration, we add sulphate of soda, to 
 separate the lead ; and finally, carbonate of 
 potash to precipitate the zinc. The quan- 
 tity of each metal, may now be deduced from 
 the weight of each precipitate, according to 
 f its specific nature, agreeably to the principles 
 
MET 
 
 MET 
 
 of composition, given under the individual 
 metals. See Ores ( Analysis of)* 
 
 * Meteorolites, or Meteoric Stones, are 
 peculiar solid compounds of earthy and me- 
 tallic matters, of singular aspect and com- 
 position, which occasionally descend from 
 the atmosphere, usually from the bosom of a 
 luminous meteor. This phenomenon affords 
 an instructive example of the triumph of 
 human testimony, over philosophical scepti- 
 cism. Hie chronicles of almost every age, 
 had recorded the fall of ponderous stony or 
 earthy masses from the air, but the evidence 
 had been rejected by historians, forsooth, be- 
 cause the phenomenon was not within the 
 range of their philosophy. At length the so- 
 ber and solid researches of physical science, 
 put to shame the incredulity of the meta- 
 physical school. 
 
 “ While all Europe,” says the celebrated 
 Vauquelin, “ resounded with the rumour of 
 stones fallen from the heavens, and while 
 philosophers, distracted in opinion, were fram- 
 ing hypothesis to explain their origin, each 
 according to his own fanev, the lion. Mr 
 Howard, an able English chemist, was pur- 
 suing in silence the only route which could 
 lead to a solution of the problem. He col- 
 lected specimens of stones which had fallen 
 at different times, procured as much infor- 
 mation as possible respecting them, compared 
 the physical or exterior characters of these 
 bodies ; and even did more, in subjecting 
 them to chemical analysis, by means as in- 
 genious as exact. 
 
 “It results from his researches, that the 
 stones which fell in England, in Italy, in 
 Germany, in the East Indies, and in other 
 places, have all such a perfect resemblance, 
 that it is almost impossible to distinguish 
 them from each other ; and what renders the 
 similitude more perfect and more striking is, 
 that they are composed of the same prin- 
 ciples, and nearly in the same proportions.” 
 
 I have given this just and handsome tri- 
 bute to English genius in the form of a 
 quotation from the French chemist; by ap- 
 propriating the language to one’s self, as has 
 been practised in a recent compilation, the 
 force of the compliment is in a great mea- 
 sure done away. 
 
 “ I should have abstained,” continues M. 
 Vauquelin, “ from any public notice of an 
 object, which lias been treated of in so able 
 a manner by the English chemist, if he him- 
 self had not induced me to do so, during his 
 residence in Earis; had not the stones which 
 I analyzed been from another country ; and 
 had not the interest excited by the subject, 
 rendered this repetition excusable. 
 
 “ It is therefore to gratify Mr Howard; 
 to give, if possible, more weight to his ex- 
 periments; and to enable philosophers to 
 place full confidence in them, rather than to 
 offer any thing new, that I publish this me- 
 
 moir.” Journal dcs Mines, No. 7 6 ; and 
 T Mock's Mag. vol. xv. p. 346. 
 
 It is remarkable, that all the stones, at 
 whatever period, or in whatever part of the 
 world, they may have fallen, have appeared, 
 as far as they have been examined, to consist 
 of the same substances ; and to have nothing 
 similar to them, not only among the mine- 
 rals in the neighbourhood of the places where 
 they were found, but among all that have 
 hitherto been discovered in our earth, as far 
 as men have been able to penetrate. For 
 the chemical analysis of a considerable num- 
 ber of specimens we are particularly indebted 
 to Mr Howard, as well as to Klaproth and 
 Vauquelin, and a precise mineralogical de- 
 scription of them has been given by the Count 
 do llournon and others. 
 
 They are all covered with a thin crust of 
 a deep black colour, they are without gloss, 
 and their surface is roughened with small 
 asperities. Internally they are greyish, and 
 of a granulated texture, more or less fine. 
 Four different substances are interspersed 
 among their texture, easily distinguished by 
 a lens. The most abundant is from the size 
 of a piu’s head to that of a pea, opaque, with 
 a little lustre like that of enamel, of a grey 
 colour sometimes inclined to brown, and 
 hard enough to give faint sparks with steel. 
 Another is a martial pyrites, of a reddish- 
 yellow colour, black when powdered, not 
 very firm in its texture, and not attractible 
 by the magnet. A third consists of small 
 particles of iron in a perfectly metallic state, 
 which give to the mass the quality of being 
 attracted by the magnet, though in some 
 specimens they do not exceed two per cent 
 of the whole weight, while in others they 
 extend to a fourth. These are connected 
 together by a fourth of an earthy consistence 
 in most, so that they may be broken to pieces 
 by the fingers with more or less difficulty. 
 The black crust is hard enough to emit 
 sparks with steel, but may be broken by a 
 stroke with a hammer, and appears to possess 
 the properties of the very attractible black 
 oxide of iron. Their specific gravity varies 
 from 3.352 to 4.281. 
 
 The crust appears to contain nickel united 
 with iron, but Mr Hatchett could not deter- 
 mine its proportion. The pyrites he esti- 
 mates at iron .68, sulphur .13, nickel .06, 
 extraneous earthy matter .IS. In the met- 
 allic particles disseminated through the mass, 
 the nickel was in the proportion of one part, 
 or thereabout, to three of iron. 1 he hard 
 separate bodies gave silex .50, magnesia . 1 5, 
 oxide of iron .34, oxide of nickel .025 ; and 
 the cement, or matrix, silex .48, magnesia 
 .18, oxide of iron .34, oxide of nickel .025. 
 The increase of weight in both these arose 
 from the higher oxidation of the iron. 1 hese 
 proportions are taken from the stones that Ic'd 
 at Benares on the 19th of December 1798. 
 
MET 
 
 MET 
 
 The solitary masses of native iron, that 
 have been found in Siberia, Bohemia, Sene- 
 gal, and South America, likewise agree in 
 the circumstance of being an alloy of iron 
 and nickel ; and are either of a cellular tex- 
 ture, or have earthy matter disseminated 
 among the metal. Hence, a similar origin 
 has been ascribed to them. 
 
 Laugier, and afterward Thenard, found 
 chrome likewise, in the proportion of about 
 one per cent, in different meteoric stones they 
 examined. 
 
 In all the instances in which these stones 
 have been supposed to fall from the clouds, 
 and of which any perfect account has been 
 given, the appearance of a luminous meteor, 
 exploding with loud noise, has immediately 
 preceded, and hence has been looked to as 
 the cause. The stones likewise have been 
 more or less hot, when found immediately 
 after their supposed fall. Different opinions 
 however have been entertained on this sub- 
 ject, which is certainly involved in much 
 difficulty. Some have supposed them to be 
 merely projected from volcanoes; while others 
 have suggested, that they might be thrown 
 from the moon ; or be bodies wandering 
 through space, and at length brought within 
 the sphere of attraction of our planet. 
 
 Various lists of the periods, places, and ap- 
 pearances of these showers of stony and earthy 
 matters, have been given from time to time 
 in the scientific Journals. The latest and 
 most complete is that published in the 1st 
 vol. of the Ed. Phil. Journ. compiled partly 
 from a printed list by Cliladni, and partly 
 from a manuscript one of Mr Allan, read 
 some years ago, at the Royal Society of 
 Edinburgh. It appears that Domenico Troili, 
 a Jesuit, published at Modena, in 1766, a 
 work entitled, Della Caduta di vn Sasso dall 
 Aria, ragionamento, in which the ingenious 
 author proves, in the clearest manner, both 
 from ancient and modern history, that stones 
 had repeatedly fallen from the heavens. 
 This curious dissertation ( ragionamento ) is 
 in the possession of Mr Allan. The com- 
 piler of the new list justly observes, that no- 
 thing can shew more strikingly the univer- 
 sality and obstinacy of that scepticism which 
 discredits every thing that it cannot under- 
 stand, than the circumstance that his work 
 should have produced so little effect, and 
 that the numerous falls of meteoric stones 
 should have so long been ranked among the 
 inventions of ignorant credulity. 
 
 Mr Howard’s admirable dissertation was 
 published in the Phil. Trans, for 1802. It 
 is reprinted in the 13th vol. of Tilloch’s Ma- 
 gazine, and ought to be studied as a pattern 
 ol scientific research. The following Table 
 is copied from the above Journal : — 
 
 9 
 
 Chronological List of Meteoric Stones. 
 Sect. 1 .—Before the Christian Era. 
 
 Division I. — -Containing those which can 
 be referred pretty nearly to a date. 
 
 A. C. 
 
 1478. The thunderstone in Crete, men- 
 tioned by Malchus, and regarded probably 
 as the symbol of Cvbele. — Chronicle of 
 Paros, 1. 1 8, 1 9. 
 
 1451. Shower of stones which destroyed 
 the enemies of Joshua at Beth-horon. — 
 Joshua , chap. x. 11. 
 
 1200. Stones preserved at Orchomenos.— 
 Dausanias. 
 
 1168. A mass of iron upon Blount Ida in 
 Crete. — Chronicle of Paros , 1. 22. 
 
 705 or 704. The Ancyle or sacred shield, 
 which fell in the reign of Numa. It had 
 nearly the same shape as those which fell 
 at the Cape and at Agram. — Plutarch , in 
 Num . 
 
 654. Stones which fell upon Blount Alba, 
 in the reign of Tullus Piostilius. — “ Cre- 
 bri cecidere coelo lapides. — Liv. 1. 31. 
 
 644. Five stones which fell in China, in 
 the country of Song. — De Guignes. 
 
 466. A large stone at iEgospotamos, which 
 Anaxagoras supposed to come from the 
 sun. It was as large as a cart, and of a 
 burnt colour. — “ Qui lapis etiam nunc 
 ostenditur, magnitudine vehis, colore adus- 
 toP — Plutarch, Pliny, lib. ii. cap. 58. 
 
 465. A stone near Th ebes. — Scholiast of 
 Pindar . 
 
 461. A stone fell in the Marsh of Ancona. 
 Valerius Maximus, Liv. lib. vii. cap. 28. 
 
 545. A shower of stones fell near Rome. 
 — Jul. Obsequens. 
 
 211. Stones fell in China, along with a 
 falling star. — De Guignes, &c. 
 
 205 or 206. Fiery stones. — Plutarch, Fab. 
 Max. cap. 2. 
 
 192. Stone fell in China. — Dc Guignes. 
 
 17 6. A stone fell in the Lake of Blars. — 
 
 “ Lapidem in Agro Crustumino in Ixicum 
 Mart is de coelo cecidisse.” — Liv. xli. 3. 
 
 90 or 89. “ Eodem causam dicente , lateribus 
 coctis pluisse, in ejus anni acta relatum 
 est — Plin. Mat. Hist. lib. ii. cap. 56. 
 
 89. Two large stones fell at Yong in 
 China. The sound was heard over 40 
 leagues. — De Guignes. 
 
 56 or 52. Spongy iron fell in Lucania. — Plin. 
 
 46. Stones fell at Acilla. — Cccsar. 
 
 58. Six stones fell in Leang in China. — 
 Dc Guignes. 
 
 29. Four stones fell at Po in China. — De 
 Guignes. 
 
 22. Eight stones fell from heaven, in 
 China. — De Guignes. 
 
 12. A stone fell at Ton-Kouan. — De 
 Guignes . 
 
 N 
 

 MET 
 
 9. Two stones fell in China Be Guignes. 
 
 6 . Sixteen stones fell in Ning-Tcheon, and 
 other two in the same year Be Guignes. 
 
 Bivision II . — Containing those, of which the 
 date cannot be determined. 
 
 '1 he Mother of the Gods which fell at Pes- 
 sinus. 
 
 The stone preserved at Abydos. — Plin. 
 
 The stone preserved at Cassandria. — Plin. 
 The Black stone, and also another preserved 
 in the Caaba of Mecca. 
 
 The “ Thunderbolt, black in appearance 
 like a hard rock, brilliant and sparkling,” 
 of which the blacksmith forged the sword 
 of Antar. — See Quarterly Review, vol. 
 xxi. p. 225. and Antar , translated by T. 
 Hamilton, Esq. p. 152. 
 
 Perhaps the stone preserved in the Corona- 
 tion Chair of the Kings of England. 
 
 Sect. 2. — AJler the Christian Era . 
 
 P. c. 
 
 A stone in the country of the Vocontini. — 
 Plin. 
 
 452. Three large stones fell in Thrace. — 
 Cedrenus and Marcellini , Chronicon, p. 29. 
 — u Hoc tempore,” says Marcellinus, “ tres 
 magni lapides e ccelo in Thracia cecide- 
 runt .” 
 
 Sixth Century. Stones fell upon Mount 
 Lebanon, and near Emisa in Syria. — 
 Bamascius. 
 
 About 570. Stones near Bender in Arabia. 
 
 — Alkoran , vi. 1 6. and cv. 3. and 4. 
 
 648. A fiery stone at Constantinople. — 
 Several Ch ro n icles. 
 
 82 3. A shower of pebbles in Saxony. 
 
 852. A stone fell in Tabavistan, in July or 
 August. — Be Sacy and Quatremere. 
 
 897. A stone fell at Ahmedabad. — Quatre- 
 mere. In 892, according to the Chron. 
 Syr. 
 
 951. A stone fell near Augsburg. — Alb. 
 Stad, and others. 
 
 998. Two stones fell, one near the Elbe, 
 and the other in the town of Magdeburg. 
 — Cosmas and Spangcnberg. 
 
 1009. A mass of iron fell in Djordjan. — 
 
 Avicenna. 
 
 1021. Stones fell in Africa between the 
 24th July and the 21st of August. — Be 
 
 Sacy. 
 
 1112. Stones or iron fell near Aquileja. — 
 
 Volvasor. 
 
 1135 or 1136. A stone fell at Oldisleben, 
 in Thuringia. — Spangcnberg , and others. 
 1164. During Pentecost, iron fell in Mis- 
 nia. — Fabricius. 
 
 1198. A stone fell near Paris. 
 
 1249. Stones fell at Quedlinbourg, Ballen- 
 stadt and Blankenburg, on the 26th July. 
 — Spangcnberg and Rivander. 
 
 Thirteenth Century. A stone fell at urz- 
 burg. — Scholtus, Phys. Cur. 
 
 Between 1251 and 1363. Stones fell at 
 
 MET 
 
 Welixoi-Ussing in Russia. — Gilbert’s yin- 
 nal. tom. 35. 
 
 1280. A stone fell at Alexandria in Egypt# 
 — Be Sacy. 
 
 1304, Oct. 1. Stones fell at Friedland or 
 Eriedberg. — Ivranz and Spangenberg. 
 
 1305. Stones fell in the country of the 
 Vandals. 
 
 1328, Jan. 9. In Mortahiah and Dakha- 
 liah. — Quatremere. 
 
 1368. A mass of iron in the Duchy of 
 Oldenburg. — Siebrand, Meyer. 
 
 1379, May 26. Stones fell at Minden in 
 Hanover. — Lerbecius. 
 
 1438. A shower of spongy stones at Roa, 
 near Burgos in Spain. — Proust. 
 
 A stone fell near Lucerne. — Cysat. 
 
 1491, March 22. A stone fell near Crema. 
 — Simoneta. 
 
 1492, Nov. 7. A stone of 260 lb. fell at 
 Ensisheim near Sturgau, in Alsace. It is 
 now in the library of Colmar, and has 
 been reduced to 150 lb. — Trithemius* 
 Hirsaug. Annal. Conrad Gesner, Liber de 
 Rerum Fossilium Figuris, cap. 3. p. 66. 
 in his Ojiera, Zurich, 1565. 
 
 1496, Jan. 26. or 28. Three stones fell be- 
 tween Cesena and Bertonori. — Buriel and 
 Sabellicus. 
 
 1510. About 1200 stones, one of which 
 weighed 120 lb. and others 60 lb. fell in 
 a field near the river Abdua. — “ Color 
 
 Jerrugineus, durities eximia, odor sulphu- 
 rous .” — Surius, Comment. Cardan, Be 
 rerum Varietate , lib. xiv. c. 72. 
 
 1511, Sept. 4. Several stones, some of 
 which weighed 1 1 lb. and others 8 lb. 
 fell at Crema. — Giovanni del Prato, and 
 others. 
 
 1520, May. Stones fell in Arragon. — 
 
 Biego de Soyas. 
 
 1540, April 28. A stone fell in the 
 Limousin. — Ronav. de St Amable. 
 
 Between 1 540 and 1 550. A mass of iron 
 fell in the forest of Naunhoff. — Chronicle 
 of the Mines of Misnia. 
 
 Iron fell in Piedmont. — Mercati and 
 
 Scaliger. 
 
 1548, Nov. 6. A black mass fell at Mans- 
 field in Thuringia. — Ronav. de St Amablx. 
 
 1552, May 19. Stones fell in Thuringia 
 near Schlossingen. — Spangenberg. 
 
 1559. Two large stones, as large as a 
 man’s head, fell at Miscolz in Hungary, 
 which are said to be preserved in the 
 Treasury at Vienna. — Sthuansi. 
 
 1561, May 17. A stone called the Arx 
 Julia , fell at Torgau and Eilenborg. — 
 Gesner and Be Root. 
 
 1580, May 27. Stones fell near Gottingen. 
 — Range. 
 
 1581, July 26. A stone, 39 lb. weight, fell 
 in Thuringia. It was so he* .hat no per- 
 son could touch it. — Rinhard , Olearius. 
 
 1583, Jan. 9. Stones fell at Castrovillari. 
 — Casto, Mercati, and Imperati. 
 
MET 
 
 MET 
 
 1583, in the Ides of Jan. A 6tone of 30 
 lb. resembling iron, fell at Rosa in Lava- 
 die. 
 
 March 2. A stone fell in Piedmont 
 
 of the size of a grenade. 
 
 1591, June 19. Some large stones fell at 
 Kunersdorf. — Lucas. 
 
 1596, March 1. Stones fell at Crevalcose. 
 — Mittarelli. 
 
 In the Sixteenth Century, not in 1603. A 
 stone fell in the kingdom of Valencia. — 
 Ccesius and the Jesuits of Coimbra. 
 
 1618, August. A great fall of stones took 
 place in Styria. — Stammes. 
 
 - A metallic mass fell in Bohemia. — 
 
 Kronland. 
 
 1621, April 17. A mass of iron fell about 
 100 miles S. E. of Lahore. — Jelian Guir's 
 Memoirs. 
 
 1622, Jan. 10. A stone fell in Devonshire. 
 — Rumph. 
 
 1628 , April 9. Stones fell near Hatford in 
 Berkshire ; one of them weighed 24 lb. — 
 Gent. Mag. Dec. 1796. 
 
 1634, Oct. 27. Stones fell in Charollois.— - 
 Morinus. 
 
 1635, June 21. A stone fell at Vago in 
 Italy. 
 
 — July 7. or Sept. 29. A stone, weigh- 
 
 ing about 1 1 oz. fell at Calce. — Valisnieri, 
 Opere, vi. 64. 
 
 1636, March 6. A burnt looking stone 
 fell between Sagan and Dubrow in Si- 
 lesia. — Lucas and Cluverius. 
 
 1637, Nov. 29. Gassendi says, a stone of 
 a black metallic colour, fell on Mount 
 Vaision, between Guilliaume and Perne 
 in Provence. It weighed 54 lb. and had 
 the size and shape of the human head. 
 Its specific gravity was 3.5. — Gassendi , 
 Opera, p. 96. Lyons, 1658. 
 
 1642, August 4. A stone weighing 4 lb. 
 fell between Woodbridge and Aldborough 
 in Suffolk. — Gent. Mag. Dec. 1796. 
 
 1643, or 1644. Stones fell in the sea. — 
 IVuof brain. 
 
 1647, beb. 18. A stone fell near Fwicxau. 
 -—Schmid. 
 
 August. Stones fell in the bailliage 
 
 of Stolzenem in Westphalia. — Gilbert's 
 Annal. 
 
 Between 1647 and 1654. A mass fell in 
 the sea. — Willman. 
 
 1650, August 6. A stone fell at Dordrecht. 
 
 — Senguesd. 
 
 1654, March 30. Stones fell in the Island 
 of bunen. — Barlholinus. 
 
 A large stone fell at Warsaw. — Petr. Borel- 
 lus. 
 
 A small stone fell at Milan, and killed a 
 b ran ci scan. —Museum Septalianum. 
 
 1668, June 19. or 21. Two stones, one 
 300 lb. and the other 200 lb. weight, fell 
 near Verona. — Legal lois, Conversations, 
 &c. Paris 1672, Valisnieri, Opere , ii. p. 
 
 64. 66. Montanan and Francisco Carli, 
 who published a letter, containing several 
 curious notices respecting the fall of stones 
 from the heavens. 
 
 1671, Feb. 27. Stones fell in Suabia.— 
 Gilbert's Annal. tom. xxxiii. 
 
 1673. A stone fell in the fields near Diet** 
 ling. — “ Nostris temporibus in partibus 
 Galilee Cispadanee, lajiis magnec quantitatis 
 e nubibus cecidit ." — See Leonardus, de 
 Gemmis , lib. i. cap. 5. ; and Memorie della 
 Societa Colombaria Fiorentina, 1747, vol. 
 i. diss. vi. p. 1 4. 
 
 1674, Oct. 6. Tw r o large stones fell near 
 Glaris. — Scheuchzer. 
 
 Between 1675 and 1677. A stone fell into 
 a fishing-boat near Copinshaw. — Wal- 
 lace’s Account of Orkney , and Gent. Mag. 
 July 1806. 
 
 1 677, May 28. Several stones, which pro- 
 bably contained copper, fell at Ermun- 
 dorf near Roosenhaven. — Misi, Nat. Cur . 
 1677. App. 
 
 1680, May 18. Stones fell at London. — 
 
 King. 
 
 1697, Jan. 13. Stones fell at Pentolina 
 near Sienna. — Soldani after Gabrieli. 
 
 1698, May 19. A stone fell at Walhing. 
 
 — Scheuchzer. 
 
 1 70 6, June 7. A stone of 72 lb. fell at La- 
 rissa in Macedonia. It smelled of sul- 
 phur, and was like the scum of iron. — » 
 Paul Lucas. 
 
 1722, June 5. Stones fell near Scheftlas 
 in F reisingen . — Meichelbeck. 
 
 1723, June 22. About 33 stones, black 
 and metallic, fell near Plestowitz in Bo- 
 hemia. — Rost and Stepling. 
 
 1727, July 22. Stones fell at Lilaschitz in 
 Bohemia. — Stepling. 
 
 1738, August 18. Stones fell near Carpen- 
 tras. — Castillon. 
 
 1740, Oct. 25. Stones fell at Rasgrad. — 
 Gilbert's Annal. tom. 1. 
 
 — — to 1741. A large stone fell in winter 
 in Greenland. — Egede. 
 
 1743. Stones fell at Liboschitz in Bohemia. 
 — Stepling. 
 
 1750, Oct. 1. A large stone fell at Niort 
 near Coutance. — Huard and Lalande. 
 
 1751, May 26. Two masses of iron of 71 
 lb. and 16 lb. fell in the district of 
 A gram, the capital of Croatia. The 
 largest of these is now in Vienna. 
 
 1753, Jan. A stone fell in Germany, in 
 Eichstadt. — Cavallo, iv. 377. 
 
 July 3. Four stones, one of w hich 
 
 weighed 13 lb. fell at Strkow r , near Tabor. 
 — Stepling, “ De Phivia lapidea , mini 
 1753, ad Strkow, et ejuscausis, meditatio," 
 p. 4. — Prag. 1754. 
 
 Sept. Two stones, one of 20 lb. and 
 
 the other of 1 1 lb. fell near the villages 
 of Liponas and Pin in Brene. — Lalande 
 and Richard. 
 
MET 
 
 MET 
 
 17.55, July. A stone fell in Calabria, at 
 Terranuova, which weighed 7 lb. oz. 
 — Domin . Tata. 
 
 1766, end of July. A stone fell at Albcreto 
 in Modena. — Troili. 
 
 August 15. A stone fell at Norellara. 
 
 * — Troili. 
 
 1768, Sept. 1.3. A stone fell near Luce in 
 Maine. It was analyzed by Lavoisier, &c. 
 — Mem. Acad. Tar. 
 
 A stone fell at Aire. — Mem. Acad. Par. 
 
 1768, Nov. 20. A stone, weighing S8 lb. 
 fell at Mauerkirchen in Bavaria. — Lnhof. 
 
 1773, Nov. 17. A stone, weighing 9 lb. 1 
 oz. fell at Sena in Arragon. — Proust. 
 
 1775, Sept. 19. Stones fell near llodach in 
 Cobourg. — Gilbert's Annul, tom. xxiii. 
 
 ——or 1776. Stones fell at Obruteza in 
 Volhynia. — Gilbert's Ami al. tom. xxxi. 
 
 1776 or 1777, Jan. or Feb. Stones fell 
 near Fabriano. — Soldani and Amoretti. 
 
 177 9. Two stones, weighing 3^ oz. each, 
 fell at Pettiswoode in Ireland. — Pingley, 
 in Gent. Mag. Sept. 1796. 
 
 1780, April 1. Stones fell near Beeston in 
 England. — Evening Post. 
 
 1782. A stone fell near Turin. — Tata and 
 Amoretti. 
 
 1785, Feb. 19. Stones fell at Eichstadt. — 
 Picket and Stalz. 
 
 1787, Oct. 1. Stones fell in the province 
 of Charkow in Russia. — Gilbert's Annul. 
 tom. xxxi. 
 
 1790, July 24. A great shower of stones 
 fell at Barbotan near Roquefort, in the 
 vicinity of Bourdeaux. A mass, 15 inches 
 in diameter, penetrated a hut, and killed 
 a herdsman and a bullock. Some of the 
 stones weighed 25 lb. and others 30 lb. — 
 Eomet. 
 
 1791, May 17. Stones fell at Cassel-Ber- 
 ardenga, in Tuscany. — Soldani. 
 
 1794, June 16. Twelve stones, one of 
 which weighed 1-k oz. fell at Sienna. 
 
 o 
 
 Howard and Klaproth have analyzed these 
 stones. — Phil. Trans. 1794, p. 103. 
 
 1795, April 13. Stones fell at Ceylon.— 
 Peck. 
 
 Dec. 13. A large stone, weighing 55 
 
 lb. fell near Wold Cottage in Yorkshire. 
 No light accompanied the fall. — Gent. 
 Mag. 1796. 
 
 1796, Jan. 4. Stones fell near Belaja-Ferk- 
 wa in Russia. — Gilbert's Annul, tom. 
 
 XXXV. 
 
 Feb. 19. A stone of 10 lb. fell in 
 
 Portugal. — Southey’s Letters from Spain. 
 
 1798, March 8. or 12. Stones, one of which 
 was the size of a calf’s head, fell at Sales. 
 — Marquis de Tree. 
 
 Dec. 19. Stones fell in Bengal. — 
 
 Howard , Lord Valerilia. 
 
 1799, April 5. Stones fell at Batanrouge 
 on the Mississippi. — Pc fast Chronicle if 
 the War. 
 
 1801, Stones fell on the Island of Tonne- 
 lier3. — Tory de St Vincent. 
 
 1802 , Sept. Stones fell in Scotland? Month- 
 ly Magazine, Oct. 1802. 
 
 1803, April 26. A great fall of stones took 
 place at Aigle. They were about three 
 thousand in number, and the largest 
 weighed about 17 lb. 
 
 Oct. 5. Stones fell near Avignon. — 
 
 Bibl. Brit. 
 
 Dec. 1 3. A stone fell near Eggen- 
 
 felde in Bavaria, weighing 3i lb. — Lnhof. 
 
 1804, April 5. A stone fell at Possil, near 
 Glasgow. 
 
 1807. A stone fell at Dordrecht. 
 
 — Van Peek. Ctdkoen. 
 
 1805, March 25. Stones fell at Doroninsk 
 in Siberia. — Gilbert's Annul, tom. xxix. 
 and xxxi. 
 
 June. Stones, covered with a black 
 
 crust, fell in Constantinople. 
 
 1806, March 15. Two stones fell at St 
 Etienne and Valence ; one of them weigh- 
 ed 8 lb. 
 
 — May 17. A stone weighing lb. 
 fell near Basingstoke in Hampshire. — 
 Monthly Magazine. 
 
 1807, March 13. (June 17, according to 
 Lucas). A stone of 160 lb. fell at Fim- 
 ochin, in the province of Smolensko in 
 Russic> — Gilbert's Annal. 
 
 — Dec. 14. A great shower of stones 
 fell near Weston in Connecticut. Masses 
 of 20 lb. 25 lb. and 35 lb. were found. — 
 Silliman and Kingsley. 
 
 1 808, April 1 9. Stones fell at Borgo San- 
 Donino. — Guidotti and Spagnoni. 
 
 May 22. Stones weighing 4 lb. or 5 
 
 lb. fell near Stannern in Moravia. — Pibl. 
 Brit. 
 
 Sept. 3. Stones fell at Lissa in Bo- 
 hemia. — He Schreibers. 
 
 1809, June 17. A stone of 6 oz. fell on 
 board an American vessel, in latitude 30° 
 58' N., and longitude 70° 25' W. — Pibl. 
 Brit. 
 
 1810, Jan. 50. Stones, some of which 
 weighed about 2 lb. fell in Caswell coun- 
 ty, North America. — Phil. Mag. vol. 
 xxxvi. 
 
 July. A great stone fell at Shahabad 
 
 in India. It burned five villages, and 
 killed several men and women. — Phil. 
 Mag. xxxvii. p. 236. 
 
 Aug. 10. A stone weighing 7f lb. 
 
 fell in the county of Tipperary in Ireland. 
 — Phil. Mag. vol. xxxviii. 
 
 Nov. 23. Stones fell at Mortelle, 
 
 Yillcrai, and Moulinbrule, in the depart- 
 ment of the Loiret; one of them weighed 
 40 lb. and the other 20 lb. — Nich . Jour- 
 nal , vol. xxx ix. p. 158. 
 
 1811, March 12 or 13* A stone of 15 lb. 
 
 fell in the village of Kongliuhowsh, near 
 
 20 
 
MET 
 
 MET 
 
 Romea in Russia.— Bruce’s American 
 Journal , No. 3. 
 
 1811, July 8. Stones, one of which weighed 
 3^ oz. fell near Balanguillas in Spain. — 
 Bill. Brit. tom. xlviii. p. 162. 
 
 1812, April 10. A shower of stones fell 
 near Thoulouse. 
 
 — April 15. A stone, the size of a child’s 
 
 head, fell at Erxleben. A specimen of it 
 is in the possession of Professor Hauss* 
 man of Brunswick. — Gilbert's Annal. xl. 
 and xli. 
 
 Aug. 5. Stones fell at Chantonay. — 
 
 Brochant . 
 
 1813, March 14. Stones fell at Cutro in 
 Calabria, during a great fall of red dust. 
 — Bibl. Brit. Oct. 1813. 
 
 _ Sept. 9. and 10. Several stones, one 
 of which weighed 17 lb. fell near Lime- 
 rick in Ireland. — Phil. Mag. 
 
 1814, Feb. 5. A stone fell near Bacharut 
 in Russia. — Gilbert's Annal. tom. 1. 
 
 — Sept. 5. Stones, some of which weighed 
 1 8 lb. fell in the vicinity of Agen. — Phil. 
 Mag. vol. xlv. 
 
 — Nov. 5. Stones, of which 19 were 
 
 found, fell in the Doab in India. — Phil. 
 
 Mag. 
 
 1815, Oct. 3. A large stone fell at Chas- 
 signy near Langres. — Pistollct. 
 
 1816, A stone fell at Glastonbury in 
 Somersetsh ire. — P/i i l. Mag. 
 
 1817, May 2. and 3. There is reason to 
 think, that masses of stone fell in the 
 Baltic after .the great meteor of Gotten- 
 burg. — Chladni. 
 
 1818, Feb. 15. A great stone appears to 
 have fallen at Limoge, but it has not 
 been disinterred. — Gazette de France , Feb. 
 25. 1818. 
 
 — July 29. O. S. A stone of 7 lb. fell 
 at the village of Slobodka in Smolensko. 
 It penetrated nearly 16 inches into the 
 ground. It had a brown crust with me- 
 tallic spots. 
 
 List of Masses of Iron supposed to have 
 
 FALLEN FROM THE HEAVENS. 
 
 Sect. 1 . — Spongy or Cellular Masses 
 containing Nickel. 
 
 1. The mass found by Pallas in Siberia, to 
 which the Tartars ascribe a meteoric ori- 
 gin. — Voyages de Pallas, tom. iv. p. 545. 
 Paris 1793. 
 
 2. A fragment found between Eibenstock 
 and Johanngeorgenstadt. 
 
 3. A fragment probably from Norway, and 
 in the imperial cabinet of Vienna. 
 
 4. A small mass weighing some pounds, 
 and now at Gotha. 
 
 5. Two masses in Greenland, out of which 
 the knives of the Esquimaux were made. 
 — See Ross’s Account oJ‘ an Expedition to 
 the Arctic Regions. 
 
 Sect. 2. — Solid Masses where the Iron exists 
 in Rhomboids or Octohcdrons , composed of* 
 Strata , and containing Nickel. 
 
 1. The only fall of iron of this kind, is 
 that which took place at Agram, in 1751. 
 
 2. A mass of the same kind lias been found 
 on the right bank of the Senegal. — Com- 
 pagnon, Forster , Goldberrxj. 
 
 3. At the Cape of Good Hope ; Strome- 
 yer has lately detected cobalt in this mass. 
 — Van Marum and Dankelman ; Brando's 
 Journal , vol. vi. 1 62. 
 
 4. In different parts of Mexico. — Sonnc- 
 schmidt , Humboldt , and the Gazette de 
 Mexico, tom. i. and v. 
 
 5. In the province of Bahia in Brazil. It 
 is seven feet long, four feet wide, and two 
 feet thick, and its weight about 14,000 lb. 
 — Mornay and Wollaston; Phil. Trans . 
 1816, p. 270. 281. 
 
 6. In thej jurisdiction of San Jago del 
 Estera. — Rubin de Cadis, in the Phil. 
 Trans. 1788, vol. lxxviii. p. 37. 
 
 7. At Elbogen in Bohemia. — Gilbert' s An- 
 nal. xlii. and xliv. 
 
 8. Near Lenarto in Hungary. — -Ditto, xlix. 
 The origin of the following masses seems to 
 
 be uncertain, as they do not contain nic- 
 kel, and have a different texture from the 
 preceding : — 
 
 1. A mass found near the Red River, and 
 sent from New Orleans to New York. — 
 Journ. des Mines 1812, Bruce's Journ. 
 
 2. A mass at Aix-la-Chapelle containing 
 arsenic. — Gilbert's Annal. xlviii. 
 
 3. A mass found on the hill of Brianza in 
 the Milanese. — Chladni in Gilbert's An- 
 nal. 1. p. 275. 
 
 4. A mass found at Groskamdorf, and 
 containing, according to Klaproth, a little 
 lead and copper. 
 
 Nickel or chromium is found to be the 
 constant associate of the iron in the meteor- 
 olites. It is characteristic of meteoric iron, 
 as it is never found in mineral native iron. 
 
 Nickel has been hitherto regarded as the sole 
 characteristic ingredient of meteoric stones, 
 but from the analyses of some late meteoro- 
 lites, it would appear, that this metal is oc- 
 casionally absent, while chromium is always 
 found. Hence the latter has come to be 
 viewed as the constant characteristic. 
 
 The phenomenon of red snow observed at 
 Baffin’s Bay, lias of late excited some specu- 
 lation, being supposed to be a meteoric pheno- 
 menon. But Mr Bauer has proved by micro- 
 scopic examination, that the colouring par- 
 ticles consist of a new' species of the ureda , 
 which grows upon the snow', to which he has 
 given the appropriate name of uredo nivalis. 
 He found the real diameter of an individual 
 full growm globule of this fungus, to be the 
 one thousand six hundredth part of an inch. 
 Hence, in order to cover a single square inch, 
 two million five hundred and sixty thousand 
 
MIC 
 
 MIL 
 
 of them are necessary. Journal of Science, 
 vol. vii.p. 222.* 
 
 * Meteorology. See Climate, Dew, 
 Rain.* 
 
 * Miasmata. Vapours or effluvia, which 
 by their application to the human system, are 
 capable of exciting various diseases, of which 
 the principal are intermittent, remittent, and 
 yellow fevers, dysentery and typhus. That 
 of the last is generated in the human body 
 itself, and is sometimes called the typhoid 
 fomes. The other miasmata are produced 
 from moist vegetable matter, in some un- 
 known state of decomposition, The conta- 
 gious virus of the plague, small-pox, measles, 
 chincough, cynanche maligna, and scarlet 
 fever, as well as of typhus and the jail fever, 
 operates to a much more limited distance 
 through the intermedium of the atmosphere, 
 than the marsh miasmata. Contact of a dis- 
 eased person is said to be necessary for the 
 communication of plague ; and approach 
 within 2 or 3 yards of him, for that of typhus. 
 The Walcheren miasmata extended their pes- 
 tilential influence to vessels riding at anchor, 
 fully a quarter of a mile from the shore. 
 
 The chemical nature of all these poisonous 
 effluvia is little understood. They undoubt- 
 edly consist, however, of hydrogen, united 
 with sulphur, phosphorus, carbon, and azote, 
 in unknown proportions, and unknown states 
 of combination. The proper neutralizers or 
 destroyers of these gasiform poisons, are nitric 
 acid vapour, muriatic acid gas, and chlorine. 
 The last two are the most efficacious ; but 
 require to be used in situations from which the 
 patients can be removed at the time of the 
 application. Nitric acid vapour may, how- 
 ever, be diffused in the apartments of the 
 sick, without much inconvenience. Bed- 
 clothes, particularly blankets, can retain the 
 contagious fomes, in an active state, for al- 
 most any length of time. Hence, they ought 
 to be fumigated, with peculiar care. The 
 vapour of burning sulphur or sulphurous 
 acid is used in the East, against the plague. 
 It is much inferior in power to the other an- 
 tiloimic reagents.* 
 
 * Mica. Professor Jameson subdivides this 
 mineral species into ten sub-species, viz. mica, 
 pinite, lepidolite, chlorite, green earth, talc, 
 nacrite, potstone, steatite, and figure-stone. 
 
 Mica. Colours, yellowish and greenish- 
 grey. Massive, disseminated, and crystalliz- 
 ed. Its primitive figure is a rhomboid. The 
 secondary forms are ; an equiangular six- 
 sided prism, or table ; a rectangular four- 
 sided prism, or table ; and a six-sided pyra- 
 mid. Lateral planes smooth and splendent ; 
 terminal, longitudinally streaked. Lustre 
 pearly, or semi- metallic. Cleavage single. 
 Fragments tabular and splintery. Translu- 
 cent. Sectile. Streak grey-coloured. Harder 
 than gypsum, but not so hard as calcareous 
 spar. Feels meagre or smooth. Elastic- 
 
 flexible. Sp. gr. 2.65. Before the blow- 
 pipe it melts into a greyish-white enamel. 
 
 Its constituents are, silica 47, alumina 22, 
 oxide of iron 15.5, oxide of manganese 1.75, 
 potash 14.5. — Klaproth. It occurs along 
 with felspar and quartz in felspar and gneiss. 
 
 It sometimes forms short beds, in granite 
 and other primitive rocks. Most of the 
 mica of commerce is brought from Siberia, 
 where it is used for window-glass.* 
 
 Microcosmic Salts. A triple salt of soda, 
 ammonia, and phosphoric acid, obtained from i 
 urine, and much used in assays by the blow r - 
 pipe. 
 
 * Miemite ; of which there are two kinds, 
 the granular and prismatic, both sub-species 
 of dolomite. 
 
 Granular miemite. Colour pale asparagus- 
 green. Massive, in granular distinct con- 
 cretions, and crystallized in flat double three- 
 sided pyramids. Lustre splendent, pearly. 
 Cleavage threefold oblique angular. Trans- 
 lucent. Semi-hard. Brittle. Sp. gr. 2.885. 
 
 It dissolves slowly, and with little efferves- 
 cence, in cold nitric acid. Its constituents 
 are, carbonate of lime 55, carbonate of mag- 
 nesia 42.5, carbonate of iron, with a little 
 manganese, 3.0. It is found at Miemo in 
 Tuscany, imbedded in gypsum, at Hall in 
 the Tyrol, and in Greenland. 
 
 Prismatic miemite. Colour asparagus- 
 green. It occurs in prismatic distinct con- 
 cretions, and crystallized in flat rhomboids, 
 which are deeply truncated on all their 
 edges. Internally shining. Fracture passes 
 from concealed foliated to splintery. Strongly 
 translucent. As hard as the former. Sp. 
 gr. 2.885. It dissolves like the other. Its 
 constituents are, lime 33, magnesia 14.5, 
 oxide of iron 2.5, carbonic acid 47.25, water 
 and loss 2.75. — Klupr. It occurs in cobalt 
 veins that traverse sandstone, at Gliicksbruun 
 in Gotha.* 
 
 Milk is a well knowm fluid, secreted in 
 peculiar vessels of the females of the human 
 species, of quadrupeds, and of cetaceous ani- 
 mals, and destined for the purpose of nou- 
 rishing their young. 
 
 When milk is left to spontaneous decom- 
 position, at a due temperature, it is found 
 to be capable of passing through the vinous, 
 acetous, and putrefactive fermentations. It 
 appears, however, probably on account of 
 the small quantity of alcohol it affords, that 
 the vinous fermentation lasts a very short 
 time, and can scarcely be made to take place 
 in every part of the fluid at once by the ad- 
 dition of any ferment. This seems to be 
 the reason, why the Tartars, who make a 
 fermented liquor, or wine, from mare’s milk, 
 called 'koumiss, succeed by using large quan- 
 tities at a time, and agitating it very fre- 
 quently. They add as a ferment a sixth 
 part of water, and an eighth part ot the 
 sourest cow’s milk they can get, or a smaller 
 
MIL 
 
 MIN 
 
 portion of koumiss already prepared : cover 
 the vessel with a thick cloth, and let it stand 
 in a moderate warmth for 24 hours : then 
 beat it with a stick, to mix the thicker and 
 thinner parts, which have separated : let it 
 stand again 24 hours in a high narrow ves- 
 sel, and repeat the beating, till the liquor is 
 perfectly homogeneous. This liquor will 
 keep some months, in close vessels, and a 
 cold place ; but must be well mixed by 
 beating or shaking every time it is used. 
 They sometimes extract a spirit from it by 
 distillation. The Arabs prepare a similar 
 liquor by the name of leban , and the Turks 
 by that of yaoart. Eton informs us, that, 
 when properly prepared, it may be left to 
 stand till it becomes quite dry ; and in this 
 state it is kept in bags, and mixed with wa- 
 ter when wanted for use. 
 
 The saccharine substance, upon which the 
 fermenting property of milk depends, is held 
 in solution by the whey, which remains after 
 the separation of the curd in making cheese. 
 This is separated by evaporation in the large 
 way, for pharmaceutical purposes, in various 
 parts of Switzerland. When the whey has 
 been evaporated by heat, to the consistence 
 of honey, it is poured into proper moulds, 
 and exposed to dry in the sun. If this crude 
 sugar of milk be dissolved in water, clarified 
 with whites of eggs, and evaporated to the 
 consistence of syrup, white crystals, in the 
 form of rhomboidal parallelopipedons, are 
 obtained. 
 
 Sugar of milk has a faint saccharine taste, 
 and is soluble in three or four parts of water. 
 It yields by distillation the same products 
 that other sugars do, only in somewhat diffe- 
 rent proportions. It is remarkable, however, 
 that the empyreumatic oil has a smell resem- 
 bling flowers of benzoin. It contains an 
 acid frequently called the saccholactic ; but 
 as it is common to all mucilaginous sub- 
 stances, it has been termed mucic. See 
 Acid (Mucic). 
 
 The kinds of milk that have been chemi- 
 cally examined, are mare’s, woman’s, ass’s, 
 goat’s, sheep’s, and cow’s. We have here 
 placed them according to the proportion of 
 sugar they afforded ; and this, Parmentier 
 observes, was precisely of the same quality in 
 all, while all the other parts varied in quality 
 as well as quantity in the different milks. 
 With regard to the whey , they rank in the 
 following order ; ass’s, mare’s, woman’s, 
 cows, goat’s, sheep’s: to cream ; sheep’s, 
 woman’s, goat's, cow’s, ass’s, mare’s : to 
 butter; sheep’s, goat’s, cow’s, woman’s : to 
 cheese; sheep’s, goat’s, cow’s, asVs, woman’s, 
 mare’s. Parmentier could not make any 
 butter from the cream of woman’s, ass’s, or 
 mare’s milk ; and that from sheep he found 
 always remained soft. From their general 
 properties, he has divided them into two 
 
 classes, one abounding in serous and saline 
 parts, which includes ass’s, mare’s, and wo- 
 man’s ; the other rich in caseous and butyra- 
 ceous parts, which are cow’s, goat s, and 
 sheep’s. 
 
 * Cream, sp.gr. 1.0244 by Berzelius’s ana- 
 lysis, consists of butter 4.5, cheese 5. 5, wocy 
 92. Curd, by the analysis of MM. Cay 
 Lussac and Thenard, is composed of 
 Carbon, 59.781 
 Oxygen, 11.400 
 Hydrogen, 7.429 
 Azote, 21.381 
 
 100.000 
 
 Whey always reddens vegetable blues, from 
 the presence of lactic acid. Milk, according 
 to Berzelius, consists of, 
 
 Water, - 
 
 928.75 
 
 Curd, with a little cream, 
 
 28.00 
 
 Sugar of milk, 
 
 55.00 
 
 Muriate of potash, 
 
 1.70 
 
 Phosphate of potash, 
 
 0.25 
 
 Lactic acid, acetate of potash, 
 
 ) 
 
 with a trace of lactate of 
 
 k 6.00 
 
 iron, - 
 
 ) 
 
 Earthy phosphates, 
 
 0.50 
 
 
 1000.00 
 
 Since both cream and water affect the spe- 
 cific gravity of milk alike, it is not possi- 
 ble to infer the quality of milk from the in- 
 dications merely of a specific gravity instru- 
 ment. We must first use as a lactometer, a 
 graduated glass tube, in which we note the 
 thickness of the stratum of cream afforded, 
 after a proper interval, from a determinate 
 column of new milk. We then apply to the 
 skimmed milk, a hydrometric instrument, 
 from W'hich we learn the relative propor- 
 tions of curd and whey. Thus, the com- 
 bination of the two instruments furnishes a 
 tolerably exact lactometer.* 
 
 * Milk-quartz. See Quartz*. 
 
 ♦Mineralogy. That department of natu- 
 ral history which teaches us to describe, re- 
 cognize, and classify, the different genera and 
 species of the objects of inorganic nature. 
 As the greater part of these are solids, ex- 
 tracted from the earth by mining, they are 
 called Minerals. The term Fossil is now 
 commonly restricted to such forms of organic 
 bodies, as have been penetrated with earthy 
 or metallic matters. 
 
 Professor Mohs of Frcyberg, has lately 
 published a work, replete with profound ge- 
 neral views on mineralogy, which promises 
 to place the science on a surer basis than it 
 has hitherto stood. 
 
 Werner first taught mineralogists to con- 
 sider the productions of inorganic nature in 
 a state of mutual connexion, resulting from 
 mineralogical similarity. Thus, heavy spar is 
 plainly more similar to calcareous spar, than 
 
MIN 
 
 MIN 
 
 felspar is ; felspar than garnet ; garnet than 
 iron-glance; iron-glance than native gold; 
 and so on. 
 
 A collection of species connected by the 
 highest , and at the same time, equal degrees 
 ot natural-history similarity, is named a 
 genus. ihe same occurs in zoology and 
 botany. Thus, the wolf, dog, fox ; the lion, 
 tiger, eat, unite into genera. Individuals 
 whose forms belong to two different systems 
 of crystallizations, cannot be united in the 
 same species. Radiated hepatic, and cristated 
 iron pyrites, therefore, constitute a distinct 
 species. Yet this species is so similar to that 
 ol common iron pyrites (tessular), that we 
 must unite them into one genus. 
 
 An ol der comprehends several analogous 
 genera ; and a class, analogous orders. 
 
 The specific character consists particularly 
 of three characters. These are the crystalline 
 forms, (including cleavage), the degrees of 
 hardness, and the specific gravity. The crys- 
 talline forms mav be reduced in all cases to 
 
 J 
 
 one of Jour Systems of Crystallization ; 
 the Rhombohedral ; the Pyramidal, de- 
 rived from a four-sided isosceles pyramid ; the 
 Prismatic, derived from a scalene four-sided 
 pyramid ; and lastly the Tessular, or that 
 which is derived from the hexahedron. 
 
 When we wish to determine the species 
 to which any mineral belongs, by means of a 
 tabular view, we must first ascertain either its 
 primitive form or cleavage, and afterwards 
 the hardness and specific gravity. The de- 
 grees of hardness are expressed by Mohs in 
 the following manner: — 
 
 1 expresses the hardness of Talc, 
 
 2 Gypsum, 
 
 5 Calcareous spar, 
 
 4 Fluor spar, 
 
 5 Apatite, 
 
 G Felspar, 
 
 7 Quartz, 
 
 8 Topaz, 
 
 9 Corundum, 
 
 10 Diamond. 
 
 Professor Mohs has arranged minerals in- 
 to three classes. 
 
 I. Character of the first class. 
 
 If solid ; sapid. No bituminous odour. 
 Sp. gr. under 8.8. It has 4 orders. 
 
 Order I. Gas. Expansible. Not acid. 
 
 9. Water. Liquid. Without odour or 
 sapidity. Sp. gr. 1. 
 
 8. Acid. Acid. Specific gravity, 0.001 5 
 to 8.7. 
 
 4. Salt. Not acid. Sp. gr. 1.2 to 2.9. 
 
 II. Character of the second class. 
 
 Insipid. Sp. gr. above 1.8. 
 
 Order 1 . Haloide (salt-like). Not metal- 
 lic. Streak uncoloured. 
 
 If pyramidal or prismatic; H. hardness 
 zsz I and less. If tessular, H. = 4.0. If 
 
 single, perfect, and eminent faces of cleavage ; 
 sp. gr. = 2.4 and less. 
 
 H. = 1.5 to 5.0. If under 2.5, sp. gr — 
 
 2.4 and less. Sp. gr*= 2.2 to 3.3. & lf 2.4 
 and less; H. under 2.5; and no resinous 
 lustre. 
 
 Order 2. Baryte. 
 
 Not metallic. If admantine or imperfect 
 metallic lustre ; sp. gr. = 6.0, and more. 
 Streak uncoloured, or orange-yellow. If 
 orange- yellow ; sp. gr. = 6.0 and more, 
 and H. = 3.0 and less. 
 
 II. = 2.5 to 5.0. If 5.0 ; sp. gr. under 
 
 4.5. 
 
 Sp. gr. = 3.3 to 7.2. If under 4.0 and II. 
 = 5.0 ; cleavage diprismatic. 
 
 Order 3. Aerate (Horny). 
 
 Not metallic. Streak uncoloured. No 
 single eminent cleavage. FI. = 1.0 to 2.0. 
 Sp. gr. =5.5. 
 
 Order 4. Malachite. 
 
 Not metallic. Colour blue, green, brown. 
 If brown, colour of streak : H. = S.O 
 
 and less; and sp. gr. above 2.5. If un- 
 coloured streak ; sp. gr. = 2.2 and less ; and 
 I I. = 3.0. No single eminent faces of cleav- 
 age. H. = 2.0 to 5.0. Sp. gr. = 2.0 to 
 
 4.6. 
 
 Order 5. Mica. 
 
 If metallic : Sp. gr. under 2.2. If not 
 metallic: Sp. gr. above 2.2. If yellow 
 streak; pyramidal. Single eminent cleavage. 
 II. = 1.0 to 4.5. If above 2.5 ; rhombohe- 
 dral. Sp. gr. = J. 8 to 5.6. If under 2.5; 
 metallic. If above 4.4 ; streak uncoloured. 
 Order 6. Spar. 
 
 Not metallic. Streak uncoloured, brown. 
 If rhombohedral ; sp. gr. 2.2 and less, or 
 H. = 6.0. 
 
 II. = 3.5 to 7. If 4.0 and less; single 
 eminent cleavage. If above 6.0 ; sp. gr. 
 under 2.5, or above 2.8 ; and pearly lustre. 
 Sp. gr. = 2.0 to 3.7. If above 3.3 ; hemi- 
 prismatic, or H. = 6.0 ; and no adamantine 
 lustre. If 2.4 and less; not without traces 
 of form and cleavage. 
 
 Order 7. Gem. 
 
 Not metallic. Streak uncoloured. II. 
 = 5.5 to 10. If 6.0 and less ; sp. gr. = 
 
 2.4 and less; and no traces of form and 
 
 cleavage. Sp. gr. = 1.9 to 4.7. 11 under 
 
 3.8 ; no pearly lustre. 
 
 Order 8. Ore. 
 
 If metallic ; black. If not metallic; ada- 
 mantine, or imperfect metallic lustre. If 
 yellow or red streak ; II. = 8.5 and more ; 
 and sp. gr. = 4.8 and more. II brown or 
 black streak: II. = 5.0 and more, or per- 
 fectly prismatoidal. H. = 2.5 to 7.0. If 
 
 4.5 and less; red, yellow, or black streak. It 
 
 6.5 and more; and streak uncoloured; sp. 
 gr. =6.5 and more. Sp. gr. = 5.4 to 7.4. 
 
 Order 9. Metal. 
 
 Metallic. Not black. If grey; malle- 
 able; and sp. gr. = 7.4 and more. II. = 
 
MIN 
 
 0.0 to 4.0 or malleable. Sp. gr. = 5.7 to 
 
 20 . 0 . 
 
 Order 10. Pyrites . 
 
 Metallic. H. = 3.5 to 6.5. If 4.5 and 
 less ; sp. gr. under 5.0. Sp. gr. — 4. 1 to 
 7.7. If 5.3 and less; colour yellow or red. 
 
 Order 11. Glance . 
 
 Metallic. Grey, black. H. 1.0 to 4.0. 
 Sp. gr. = 4.0 to 7.6. If under 5.0 ; and 
 single perfect cleavage ; lead-grey. If above 
 7.4; lead- grey. 
 
 Order 1 2. Blende. 
 
 If metallic ; black. If not metallic ; ada- 
 mantine lustre. If brown streak; uncoloured. 
 Sp. gr. between 4.0 and 4.2 ; and the form 
 tessular. Tf red streak ; sp. gr. = 4.5 and 
 more ; and H. = 2.5 and less. 
 
 H. = 1.0, 4.0. Sp. gr. = 5.9, 8.2. If 
 4.3 and more ; streak red. 
 
 Order 15. Sulphur. 
 
 Not metallic. Colour red, yellow, or 
 brown. Prismatic. H. = 1.0 to 2.5. Sp. 
 gr. = 1.9 to 3.6. If above 2.1 ; streak 
 yellow, or red. 
 
 Glass III. 
 
 If fluid ; bituminous odour. If solid ; 
 insipid. Sp. gr. under 1.8. 
 
 Order 1. Basin. 
 
 Fluid, solid. Streak uncoloured, yellow, 
 brown, black. H. = 0.0 to 2.5. Sp. gr.*= 
 0.7 to 1.6. If 1.2 and more; streak un- 
 coloured. 
 
 Order 2. Coal. 
 
 Solid. Streak, brown, black. II. = 0.1 
 to 2.5. Sp. gr. = 1.2 to 1.5. 
 
 Genera. 
 
 Class I. Order 1. Gas. 
 
 Genera. 1. Hydrogen. 2. Atmospheric«ur. 
 
 Order 2. Water. 
 
 Genus. 1. Atmospheric water. 
 
 Order 5. Acid. 
 
 Genera. 1. Carbonic. 2. Muriatic. 3. 
 Sulphuric. 4. Boracic ; and 5. Arsenic. 
 
 Order 4. Salt. 
 
 Genera. 1. Natron-salt. 2. Glauber- 
 salt. 5. Nitre-salt. 4. Rock-salt. 5. Am- 
 moniac-salt. 6. Vitriol-salt; comprising as 
 species, the sulphates of iron, copper and 
 zinc. 7. Epsom-salt,. 8. Alum-salt. 9. Bo- 
 rax-salt. 10. Brythine-salt (heavy-salt). 
 Glauberite. 
 
 Class II. Order 1. Ilaloidc . 
 
 Genera. 1. Gypsum-haloide. 2. Cryonc- 
 haloidc. 5. Alum-haloide. 4. Fluor-haloide. 
 5. Calc-haloide. 
 
 Order 2. Baryte. 
 
 Genera. 1. Parach rose- baryte (altered 
 colour). 2. Zinc- baryte. 3. Scheelium- 
 baryte. 4. Ilal-baryte. 5. Lead baryte. 
 
 Order 3. Karate . 
 
 Genera. 1. Pearl-kerate. 
 
 Order 4. Malachite. 
 
 Genera. 1. Staphyline-malachite (grape 
 like). 2. Liroconc-malachite (form un- 
 
 MIN 
 
 i 
 
 known). 5. Olive-malachite. 4. Azure- 
 malachite. 5. Emerald-malachite. 6. Ha- 
 broneme-malachite (fine threaded). 
 
 Order 5. Mica . 
 
 Genera. 1. Euchlore-mica (bright green). 
 
 2. Antimony-mica. 5. Cobalt-mica. 4. 
 Iron-mica. 5. Graphite-mica. 6. Talc- 
 mica. 7. Pearl-mica. 
 
 Older 6. Spar. 
 
 Genera. 1. Schiller- spar. 2. Disthene- 
 spar. 5. Triphane-spar. 4. Dystome-spar 
 (difficult to cleave). 5. Kouphone-spar 
 (light). 6. Petaline-spar. 7. Felspar. 8. 
 Augite-spar. 9. Azure- spar. 
 
 Order 7. Gem. 
 
 Genera. 1. Andalusite. 2. Corundum. 
 
 3. Diamond. 4. Topaz. 5. Emerald. 6. 
 Quartz. 7. Axinite. 8. Chrysolite. 9. Bo- 
 racite. 10. Tourmaline. 11. Garnet. 12. 
 Zircon. 13. Gadolinite. 
 
 Order 8. Ore. 
 
 Genera . 1. Titanium -ore. 2. Zinc-ore. 
 
 3. Copper-ore. 4. Tin-ore. 5. Scheelium- 
 ore. 6. Tantalum-ore. 7. Uranium-ore. 
 8. Cerium- ore. 9. Chrome-ore. 10. Iron- 
 ore. 1 1 . Manganese-ore. 
 
 Order 9. Metal. 
 
 Genera. 1. Arsenic. 2. Tellurium. 3. 
 Antimony. 4. Bismuth. 5. Mercury. 6. 
 Silver. 7. Gold. 8. Platina. 9. Iron. 
 10. Copper. 
 
 Order 10. Pyrites. 
 
 Genera. 1. Nickel-pyrites. 2. Arsenic- 
 pyrites. 5. Cobalt-pyrites. 4. Iron -pyrites. 
 5. Copper- pyrites. 
 
 Order 11. Glance. 
 
 Genera. 1. Copper-glance. 2. Silver- 
 glance. 3. Lead-glance. 4. Tellurium- 
 glance. 5. Molybdena-glanee. 6. Bismuth- 
 glance. 7. Antimony-glance. 8. Melane- 
 glance (black). 
 
 Order 12. Blende. 
 
 Genera. 1 . Glance-blende. 2. Garnet- 
 blende. 3. Purple-blende. 4. Ruby- blende. 
 Order 1 3. Sulphur. 
 
 1. Sulphur. 
 
 Class III. Order 1. Basin. 
 
 Genus. Melichrone- resin (honey-colour- 
 ed). 
 
 Order 2. Coal. 
 
 Genus. Mineral-coal. 
 
 Such are the Genera of Professor Mohs. 
 I would willingly have introduced a view of 
 the species; but his symbols of their crystal- 
 line structure, and forms, would require a 
 detailed explanation, inconsistent with the 
 limits of this work. An account of his new 
 system of crystallography is given by one of 
 his pupils in the 5d vol. of the Edin. Phil. 
 Journal. But the Professor promises soon 
 to publish that system himself ; which, if we 
 may judge from the luminous exposition' of 
 the characteristic of his Natural History 
 System, recently published, will be an im- 
 mense ’cnnisition to mineralogical science.* 
 
MOIt 
 
 * Mineral Caoutchouc. See Caout- 
 chouc.* 
 
 * Mineral Charcoal. See Charcoal 
 (Mineral).* 
 
 * Mineral Oil. See Petroleum.* 
 
 * Mineral Pitch. See Bitumen.* 
 
 Mineralizer. Metallic substances are 
 
 said to be mineralized, when deprived of 
 their usual properties by combination with 
 some other substance. 
 
 Minium. lied oxide of lead. 
 
 Mirrors. See Speculum j also Silver- 
 ing. 
 
 * Mispiceel. Common arsenical pyrites.* 
 
 * Mocha- stone. See Agate.* 
 
 * Molybdate of Lead. See Ores of 
 Lead. * 
 
 Molybdenum. A metal which has not yet 
 been reduced into masses of any magnitude ; 
 but has been obtained only in small separate 
 globules, in a blackish brilliant mass. This 
 may be effected by making its acid into a 
 paste with oil, bedding it in charcoal in a 
 crucible, and exposing it to an intense heat. 
 The globules are grey, brittle, and extreme- 
 ly infusible. By heat it is converted into a 
 white oxide, which rises in brilliant needle- 
 formed flowers, like those of antimony. 
 Nitric acid readily oxidizes and acidifies the 
 metal. Nitre detonates with it, and the re- 
 maining alkali combines with its oxide. 
 
 Molybdenum unites with several of the 
 metals, and forms brittle or friable com- 
 pounds. No acid acts on it but the nitric 
 and nitromuriatic. Several acids act on its 
 oxide, and afford blue solutions. See Acid 
 (Molybdic). 
 
 * The sp. gr. of molybdenum is 8.611. 
 When dry molybdate of ammonia is ignited 
 in a crucible with charcoal powder, it is con- 
 verted into the brown oxide of the metal. 
 This has a crystallized appearance, a copper- 
 brown colour, and a sp. gr. of 5 . 66 . It 
 does not form salts with acids. The deu- 
 toxide is molybdous acid, which see.* 
 
 * Montmartrite. Its colour is yellowish ; 
 it occurs massive, but never crystallized. It 
 is soft. It effervesces with nitric acid. It 
 is a compound of 83 sulphate of lime, and 
 1 7 carbonate of lime, which is found at 
 Montmartre, near Paris. It stands the 
 weather, which common gypsum does not 
 bear.* 
 
 * Moonstone. A variety of Adularia.* 
 
 * Moor- coal. See Coal. * 
 
 * Morass-ore. Bog-iron ore.* 
 
 * Moroxylates. Compounds of moroxy- 
 lic acid, with the salifiable bases.* 
 
 * Moroxylic Acid. See Acid (Moiioxy- 
 Lic).* 
 
 * Morphia. A new vegetable alkali, 
 extracted from opium, of which it constitutes 
 the narcotic principle. It was first obtained 
 pure, by M. Serturner, about the year 1817. 
 
 Two somewhat different processes for pro- 
 
 MOIt 
 
 curing it, have been given by M. Robiquet, 1 1 
 and M. Choulant. 
 
 According to the former, a concentrated 
 infusion of opium is to be boiled with a 
 small quantity of common magnesia for a 
 quarter of an hour. A considerable quanti- 
 ty of a greyish deposite falls. This is to be 
 washed on a filter with cold water, and, when l 
 
 dry, acted on by weak alcohol for some time, \ 
 
 at a temperature beneath ebullition. In this i 
 w ay very little morphia, but a great quan- 
 tity of colouring matter, is separated. The t ! 
 acid matter is then to be drained on a filter, 
 washed with a little cold alcohol ; and 
 after w'ards boiled with a large quantity of 
 highly rectified alcohol. This liquid being 
 filtered while hot, on cooling it deposits the 
 morphia in crystals, and very little coloured. 
 
 The solution in alcohol and crystallization 
 being repeated two or three times, colourless 
 morphia is obtained. 
 
 The theory of this process is the follow- 
 ing : — Opium contains a meconiate of mor- 
 phia. The magnesia combines w ith the me- 
 conic acid, and the morphia is displaced. 
 
 Choulant directs us to concentrate a dilute 
 watery infusion of opium, and leave it at rest 
 till it spontaneously let fall its sulphate of 
 lime in minute crystals. Evaporate to dry- 
 ness ; redissolve in a little water, and throw 
 down any remaining lime and sulphuric 
 acid, by the cautious addition, first of oxalate 
 of ammonia, and then of muriate of barytes. 
 Dilute the liquid with a large body of water, 
 and add caustic ammonia to it, as long as any 
 precipitate falls. Dissolve this in vinegar, and 
 throw it dow n again with ammonia. Digest 
 on the precipitate about twice its weight of 
 sulphuric ether, and throw' the whole upon 
 a filter. The dry powder is to be digested 
 three times in caustic ammonia, and as often 
 in cold alcohol. The remaining powder be- 
 ing dissolved in twelve ounces of boiling 
 alcohol, and the filtered hot solution being 
 set aside for 18 hours, deposits colourless 
 transparent crystals, consisting of double 
 pyramids. By concentrating the supernatant 
 alcoholic solution, more crystals may be ob- 
 tained. 
 
 Dr Thomson directs us to pour caustic 
 ammonia into a strong infusion of opium, 
 and to separate the brownish-white precipi- 
 tate by the filter; to evaporate the infusion to 
 about one-sixth of its volume, and mix the 
 concentrated liquid with more ammonia. A 
 new deposite of impure morphia is obtained. 
 Let the whole of the deposites be collected 
 on the filter, and washed with cold water. 
 When well drained, pour a little alcohol on 
 it, and let the alcoholic liquid pass through 
 the filter. It will carry oft' a good deal of 
 the colouring matter, and very little of the 
 morphia. “ Dissolve the impure morphia 
 thus obtained, in acetic acid, and mix the 
 solution, which has a very deep brown colour, 
 
MOR 
 
 MOU 
 
 with a sufficient quantity of ivory-black. 
 This mixture is to be frequently agitated for 
 24 hours, and then thrown on the filter. The 
 liquid passes through quite colourless. If 
 ammonia be now dropped into it, pure mor- 
 phia falls in the state of a white powder. If 
 we dissolve this precipitate in alcohol, and 
 evaporate that liquid slowly, we obtain the 
 morphia, in pretty regular crystals. It is 
 perfectly white, has a pearly lustre, is desti- 
 tute of smell, but has an intensely bitter 
 taste, and the shape of the crystals in all my 
 trials, was a four-sided rectangular prism.” 
 Annals of Phil. June 1820. On the above 
 process I have only to remark, that the acetic 
 solution must contain a good deal of phos- 
 phate of lime, derived from the ivory-black ; 
 and that therefore those who have used that 
 precipitate for morphia in medicine, have 
 been disappointed. The subsequent solution 
 in alcohol, however, and crystallization, ren- 
 der it pure. 
 
 M. Choulant says, it crystallizes in double 
 four-sided pyramids, whose bases are squares 
 or rectangles. Sometimes in prisms with 
 trapezoidal bases. 
 
 It dissolves in 82 times its weight of boil- 
 ing water, and the solution on cooling de- 
 posits regular, colourless transparent crystals. 
 It is soluble in 56 times its weight of boiling 
 alcohol, and in 42 times its weight of cold 
 alcohol, of 0.92. It dissolves in eight times 
 its weight of sulphuric ether. All these so- 
 lutions change the infusion of brazil-wood 
 to violet, and the tincture of rhubarb to 
 brown. The saturated alcoholic and ethere- 
 ous solutions, when rubbed on the skin, leave 
 a red mark. 
 
 Sulphate of morphia crystallizes in prisms, 
 which dissolve in twice their weight of dis- 
 tilled water. They are composed of 
 Acid, 22 .5.00 
 
 Morphia, 40 9.09 
 
 Water, 38 
 
 100 
 
 Nitrate of morphia yields needle-form crys- 
 tals in stars, which are soluble in \\ times 
 their weight of distilled water. Its con- 
 stituents are, 
 
 Acid, 20 6.75 
 
 Morphia, 36 12.15 
 
 Water, 44 
 
 100 
 
 Muriate of morphia, is in feather-shaped 
 crystals, and needles. It is soluble in 10§ 
 times its weight of distilled water. Its 
 constituents are, 
 
 Acid, 35 4.625 
 
 Morphia, 41 5.132 
 
 Water, 24 
 
 100 
 
 The acetutc crystallizes in needles ; the 
 
 tartrate in prisms ; and the carbonate In short 
 prisms. Dr Thomson states the ultimate 
 constituents of morphia to be, 
 
 Hydrogen, 0.0555 
 Carbon, 0.4528 
 Oxygen, 0.4917 
 
 1.0000 
 
 from the analysis of one grain, by ignited 
 peroxide of copper. lie imagines the atom 
 to be either 40.25, or 20.125. The former 
 number approaches to that of Pelletier and 
 Caventou ; the latter is much greater than 
 any of Choulant’s, deduced from the above 
 saline combinations, the mean of which gives 
 about 8.25. 
 
 Morphia acts w 7 ith great energy on the 
 animal economy. A grain and a half taken 
 at three different times, produced such vio- 
 lent symptoms upon three young men of 1 7 
 years of age, that Sertiirner was alarmed, 
 lest the consequences should have proved 
 fatal. 
 
 Morphia, according to its discoverer, melts 
 in a gentle heat; and in that state has very 
 much the appearance of melted sulphur. 
 On cooling, it again crystallizes. It burns 
 easily; and when heated in close vessels, 
 leaves a solid, resinous, black matter, having 
 a peculiar smell.* 
 
 * Mortar Cement. A mixture of lime, 
 and siliceous sand, used in masonry for ce- 
 menting together the stones and bricks of a 
 building. The most precise ideas which w 7 e 
 have on this subject, were given by Sir II. 
 Davy in his Agric. Chem. See Lime.* 
 
 * Mosaic Gold. See Aurum Musivum.* 
 
 * Mother of Pearl shells are composed 
 of alternate layers of coagulated albumen 
 and carbonate of lime, in the proportion, by 
 Mr Hatchett, of 24 of the former aud 76 of 
 the latter, in 1 00 parts. * 
 
 Mother Water. When sea-w 7 ater, or 
 any other solution containing various salts, 
 is evaporated, and the crystals taken out ; 
 there always remains a fluid containing deli- 
 quescent salts, and the impurities, if present. 
 This is called the mother water. 
 
 Mould. See Soil, Manure, and Ana- 
 lysis (Vegetable). 
 
 * Mountain Blue. Malachite ; carbo- 
 nate of copper. * 
 
 * Mountain Cork and Mountain Leath- 
 er. See Asbestus. * 
 
 * Mountain Green. Common copper 
 green ; a carbonate of copper. * 
 
 * Mountain or Bock Wood. See As-’ 
 
 BESTUS.* 
 
 * Mountain Soap. Colour pale brown- 
 ish-black. Massive. Dull. Fracture fine 
 earthy. Opaque. Streak shining. Writes, 
 but does not soil. Soft. Sectile. Easily 
 frangible. Adheres strongly to the tongue. 
 Feels very greasy. It is light, bordering on 
 rather heavy. It occurs in trap-rocks in 
 
NAT 
 
 NEE 
 
 ilu. island oi Skye. It is used in crayon- 
 painting.* 
 
 Mucilage. An arjueous solution of 
 gum. * 
 
 IVIucus. lhis, according to Dr Bostock, 
 is one ot the primary animal fluids, perfectly 
 distinct from gelatine. 
 
 ilie subacetate ol lead does not affect ge- 
 latin ; on the other hand, tannin, which is a 
 delicate test of gelatin, does not affect mucus. 
 Doth these reagents, however, precipitate 
 albumen ; but the oxymuriate of mercury, 
 which will indicate the presence of albumen 
 dissolved in LOGO parts of water, precipitates 
 neither mucus nor gelatin. Thus we have 
 three distinct and delicate tests for these 
 three different principles. 
 
 Gum appears to resemble mucus in its 
 properties. One grain of gum-arabic, dis- 
 solved in 200 of water, was not affected by 
 oxymuriate of mercury, or by tannin, but 
 was immediately precipitated by subacetate 
 of lead. 
 
 Muffle. A small earthen oven, made 
 and sold by the crucible manufacturers. It 
 is to be fixed in a furnace, and is useful for 
 cupellation, and other processes which de- 
 mand access of air. 
 
 * Muriacite. Gypsum.* 
 
 * Muriatic Acid. See Acid (Muriatic).* 
 
 * Muricalcite. Rhomb-spar.* 
 
 Muscles of Animals. See Fibrin and 
 
 Flesh.* 
 
 * Muscovy Glass. Mica.* 
 
 * Mushrooms. See Boletus.* 
 
 * Mussite. Diopside.* 
 
 * Must. The juice of grape, composed of 
 water, sugar, jelly, gluten, and bitartrate of 
 potash. From a French wine pint of must , 
 the Marquis de Bullion extracted half an 
 ounce of sugar, and 1-1 6th of an ounce of 
 tartar. Proust says, the muscadine grape 
 contains about 30 per cent of a peculiar spe- 
 cies of sugar. By fermentation, it forms 
 wine.* 
 
 * Myricin. The ingredient of w r ax which 
 remains after digestion with alcohol. It is 
 insoluble likewise in w ater and ether ; but 
 very soluble in fixed and volatile oils. Its 
 melting point is about 1 20°. Sp. gr. 0.90. 
 Its consistence is waxy.* 
 
 * Myrrh. A gum-resin, which consists, 
 according to Braconnot, of 
 
 Resin, containing some volatile oil, 53.68 
 Gum, - 66.32 
 
 100.00 
 
 N 
 
 AC RITE. See Talcite. * 
 
 * Nadelstein. Rutile.* 
 
 * Nails, consist of coagulated albumen, 
 with a little phosphate of lime. * 
 
 Nankin Dye. See Iron, tow r ards the 
 end. 
 
 * Naphtha. A native combustible li- 
 quid, of a yellowish-white colour ; perfectly 
 fluid and shining. It feels greasy, exhales an 
 agreeable bituminous smell, and has a spe- 
 cific gravity of about 0.7. It takes fire on 
 the approach of flame, affording a bright 
 white light. It occurs in considerable springs 
 on the shores of the Caspian Sea, in Sicily 
 and Italy. It is used instead of oil, and 
 differs from the petroleum obtained by dis- 
 tilling coal tar, only by its greater purity and 
 lightness. By Dr Thomson’s recent analy- 
 sis of a specimen of naphtha from Persia, 
 whose sp. gr. was 0.753, and boiling point 
 320°, it appears to be composed of carbon 
 82.2 -f- hydrogen 14.8, with perhaps a little 
 azote. * 
 
 Naples Yellow. According to Professor 
 Beckmann, this colour is prepared by cal- 
 cining lead with antimony and potash in a 
 reverberatory furnace. 
 
 * Natron. Native carbonate of soda, of 
 which there are two kinds, the common and 
 radiated. See Soda.* 
 
 * Natrolite. A sub-species of prismatic 
 zeolite or mesotype. Colour yellowish. Mas- 
 sive, in plates, and reniform. Seldom crys- 
 tallized. Crystals acicular. Lustre glisten- 
 ing, pearly. Translucent on the edges. Sp. 
 gr. 2.2. Before the blow-pipe it becomes 
 first black, then red, intumesces, and melts 
 into a white compact glass. Its constituents 
 are, silica 48.0, alumina 24.25, natron, 16.5, 
 oxide of iron 1.75, and water 9. It occurs 
 in chalkstone porphyry in Wurtemberg and 
 Bohemia, and in the trap-tuff hill named the 
 Bin, behind Bruntisland in Scotland.* 
 
 * Needle Ore. Acicular bismuth-glance.* 
 
 * Needle Zeolite. Colour greyish- white. 
 Massive ; in distinct concretions ; and crys- 
 tallized in acicular rectangular four-sided 
 prisms, variously acuminated and truncated. 
 The lateral planes are longitudinally streak- 
 ed. Glistening, inclining to pearly. Cleav- 
 age tw ofold, in the direction of the lateral 
 plane of the prism. Translucent. Refracts 
 double. As hard as apatite. Brittle. Sp. 
 gr. 2.3. It intumesces before the blow -pipe, 
 and forms a jelly with acids. It becomes 
 electric by heating, and retains tins property 
 some time after it has cooled. The free ex- 
 tremity of the crystal, with the acumination, 
 shews positive, and the attached end nega- 
 tive electricity. Its constituents are, silica 
 
NIC 
 
 NIC 
 
 50.24, alumina 29.3, lime 9.40, water 10. 
 It occurs in secondary trap-rocks near the 
 village of Old Kilpatrick in Scotland.* 
 
 * Nepheline. Rhomboidal felspar. Co- 
 Hour white. Massive and crystallized. The 
 
 primitive form is a di- rhomboid of 152° 44', 
 and 56° 15'. The secondary forms are, a 
 perfect equiangular six-sided prism ; the 
 same truncated on the terminal edges ; and 
 a thick six-sided table, with the lateral edges 
 all truncated. The crystals form druses. 
 Lustre splendent, vitreous. Cleavage four- 
 fold. Fracture conchoidal. Translucent 
 and transparent. As hard as felspar. Sp. 
 gr. 2.6 to 2.7. It melts with difficulty be- 
 fore the blow- pipe. Its constituents are, 
 
 silica 46, alumina 49, lime 2, oxide of iron 1. 
 It occurs in drusy cavities, along with cey- 
 lanite, vesuvian, and meionite, at Monte 
 Somma, near Naples, in drusy cavities, in 
 granular limestone.* 
 
 * Nephrite. Of which mineral there are 
 two kinds ; common nephrite and axe-stone. 
 
 Common nephrite. Colour leek-green. 
 Massive and in rolled pieces. Dull. Frac- 
 ture coarse splintery. Translucent. Nearly 
 as hard as rock-crystal. Difficultly frangi- 
 ble. Feels rather greasy. Rather brittle. 
 Sp. gr. 3. It melts before the blow-pipe into 
 a white enamel. Its constituents are, silica 
 50.5, magnesia SI, alumina 10, iron 5.5, 
 chrome 0.05, water 2.75. Nephrite occurs 
 in granite and gneiss, in Switzerland ; and in 
 veins that traverse primitive greenstone in 
 the Hartz. The most beautiful come from 
 Persia and Egypt. The South American 
 variety is called Amazon- stone, from its lo- 
 cality.* See Axe Stone. 
 
 * Nerium Tinctorium. A tree growing 
 in Ilindostan, which, according to Dr Rox- 
 burgh, affords indigo.* 
 
 * Neutralization. When acid and al- 
 kaline matter are combined in such propor- 
 tions that the compound does not change the 
 colour of litmus or violets, they are said to 
 be neutralized.* 
 
 Nickel is a metal of great hardness, of a 
 uniform texture, and of a colour between 
 silver and tin ; very difficult to be purified, 
 and magnetical. It even acquires polarity 
 by the touch. It is malleable, both cold 
 and red-hot; and is scarcely more fusible 
 than manganese. Its oxides, when pure, 
 are reducible by a sufficient heat without 
 combustible matter ; and it is little more 
 tarnished by heating in contact with air, 
 than platina, gold, and silver. Its specific 
 gravity when cast, is 8.279 ; when forged, 
 8 . 666 . 
 
 Nickel is commonly obtained from its sul- 
 phuret, the kufernickel of the Germans, in 
 which it is generally mixed also with arsenic, 
 iron, and cobalt. This is first roasted, to 
 drive off the sulphur and arsenic, then mix- 
 ed with two parts of black llux, put into a 
 
 crucible, covered with muriate of soda, and 
 heated in a forge furnace. The metal thus 
 obtained, which is still very impure, must be 
 dissolved in dilute nitric acid, and then eva- 
 porated to dryness ; and after this process 
 lias been repeated three or four times, the 
 residuum must be dissolved in a solution of 
 ammonia, perfectly free from carbonic acid. 
 Being again evaporated to dryness, it is now 
 to be well mixed with two or three parts of 
 black flux, and exposed to a violent heat in 
 a crucible for half an hour or more. 
 
 According to Richter, the oxide is more 
 easily reduced, by moistening with a little 
 oil. Thenard advises to pour chloride of 
 lime on the oxide of nickel, and shake them 
 well together, before the ammonia is added ; 
 as thus the oxides of cobalt and iron, if pre- 
 sent, will be so much saturated with oxygen, 
 as to be insoluble in the ammonia, and con- 
 sequently may be separated. 
 
 M. Chenevix observed, that a very small 
 portion of arsenic prevents nickel from being 
 affected by the magnet. Richter found the 
 same. When it is not attractible, therefore, 
 we may be pretty certain that this is present. 
 To separate the arsenic, M. Chenevix boiled 
 the compound in nitric acid, till the nickel 
 was converted into an arseniate ; decompos- 
 ed this by nitrate of lead, and evaporated the 
 liquor, not quite to dryness. He then pour- 
 ed in alcohol, which dissolved only the nitrate 
 of nickel. The alcohol being decanted and 
 evaporated, he redissolved the nitrate in wa- 
 ter, and precipitated by potash. The preci- 
 pitate, w r ell washed and dried, he reduced in 
 a Hessian crucible lined with lampblack, 
 and found it to be perfectly magnetic ; but 
 this property was destroyed again, by alloy- 
 ing the metal with a small portion of arsenic. 
 Alloying it with copper weakens this pro- 
 perty. 
 
 * There are two oxides of nickel ; the dark 
 ash-grey, and the black. If potash be added 
 to the solution of the nitrate or sulphate, and 
 the precipitate dried, we obtain the protoxide. 
 It may be regarded as a compound of about 
 100 metal with 28 of oxygen ; and the prime 
 equivalent of the metal will become 3.6, 
 while that of the protoxide will be 4.6. The 
 peroxide was formed by Thenard, by passing 
 chlorine through the protoxide diffused in 
 water. A black insoluble peroxide remains 
 at the bottom. 
 
 Little is known of the chloride, iodide, 
 sulphuret, or phosphuret of this metal. A 
 compound, resembling meteoric iron, has 
 been made, by fusing together about 5 or 10 
 parts of nickel with 95 or 90 of iron. The 
 meteoric iron from Baffin’s- Bay contains 5 
 per cent of nickel ; the Siberian contains 10 
 per cent, by Mr Children’s accurate analysis. 
 — See Journal of Science, vol.ix. 
 
 I he salts ot nickel possess the following 
 general characters. They have usually a 
 
NIT 
 
 NIT 
 
 green colour, and yield a white precipitate 
 with ferroprussiate of potash. Ammonia 
 dissolves the oxide of nickel. Sulphuretted 
 hydrogen and infusion of galls occasion no 
 precipitate. The hydrosulphuret of potash 
 throws down a black precipitate. Their 
 composition has been very imperfectly ascer- 
 tained. * 
 
 The sulphuric and muriatic acids have 
 little action upon nickel. The nitric and 
 nitro- muriatic are its most appropriate sol- 
 vents. The nitric solution is of a tine grass- 
 green colour. Carbonate of potash throws 
 down from it a pale apple-green precipitate, 
 which, when well washed and dried, is very 
 light. One part of metal gives 2.927 of this 
 precipitate, which by exposure to a white- 
 heat becomes blackish-grey, barely inclining 
 to green, and weighing only 1.285. By con- 
 tinuing the fire it is reduced. 
 
 When ammonia is added in excess to a 
 nitric solution of nickel, a blue precipitate is 
 formed, which changes to a purple-red in a 
 few hours, and is converted to an apple- 
 green by an acid. If the precipitate retain 
 its blue colour, copper is present. 
 
 * Nicotin. A peculiar principle obtain- 
 ed by Vauquelin from tobacco. It is colour- 
 less, and has the peculiar taste and smell of 
 the plant. It dissolves both in water and 
 alcohol; is volatile, poisonous, and precipi- 
 table from its solutions by tincture of galls. 
 — Ann. de Chimie , tom. lxxi. * 
 
 * Nigrine. An ore of titanium.* 
 
 Nihil Album. A name formerly given 
 
 to the flowers or w r hite oxide of zinc. 
 
 * Nitrates. Compounds of nitric acid 
 with the salifiable bases. * 
 
 Nitre. The common name of the nitrate 
 of potash. See Acid (Nitric).* 
 
 * Nitrogen, or Azote, an important ele- 
 mentary, or undecompounded principle. As 
 it constitutes four-fifths of the volume of at- 
 mospheric air, the readiest mode of procur- 
 ing azote, is to abstract its oxygenous asso- 
 ciate, by the combustion of phosphorus, or hy- 
 drogen. It may also be obtained from ani- 
 mal matters, subjected in a glass retort to 
 the action of nitric acid, diluted with 8 or 10 
 times its weight of w r afer. 
 
 Azote possesses all the physical properties 
 of air. It extinguishes flame and animal 
 life. It is absorbable by about 100 volumes 
 of water. Its spec, gravity is 0.9722. 100 
 
 cubic inches weigh 29. 65 grains. It has 
 neither taste nor smell. It unites with oxy- 
 gen in four proportions, forming four im- 
 portant compounds. These are 
 
 1. Protoxide of azote, or nitrous oxide. 
 
 2. Deutoxide of azote, nitrous gas, or ni- 
 tric oxide. 
 
 5. Nitrous acid. 
 
 4. Nitric acid. 
 
 1. Nitrous oride or protoxide of azote , w*as 
 discovered by DrPriestiey in 1772, but was 
 
 first accurately investigated by Sir H. Davy 
 in 1799. Ihe best mode of procuring it, is 
 to expose the salt called nitrate of ammonia, 
 to the flame of an Argand lamp, in a glass 
 retort. When the temperature reaches 400° 
 F. a whitish cloud will begin to project itself 
 into the neck of the retort, accompanied by 
 the copious evolution of gas, which must 
 be collected over mercury for accurate re- 
 searches, but for common experiments may 
 be received over w’ater. It has all the phy- 
 sical properties of air. It has a sweet taste, 
 a faint agreeable odour, and is condensible 
 by about its own volume of w r ater, previous- 
 ly deprived of its atmospheric air. This 
 property enables us to determine the purity 
 of nitrous oxide. A taper plunged into this 
 gas, burns with great brilliancy ; the fiarae 
 being surrounded with a bluish halo. But 
 phosphorus may be melted and sublimed in 
 it, without taking fire. When this combus- 
 tible is introduced into it, in a state of vivid 
 combustion, the brilliancy of the flame is 
 greatly increased. Sulphur and most other 
 combustible bodies, require a higher degree 
 of heat for their combustion in it, than in 
 either oxygen or common air. This may be 
 attributed to the counteracting affinity of the 
 intimately combined azote. Its sp. grav. is 
 1.5277. 100 cubic inches weigh 46.6 gr. 
 
 It is respirable, but not fitted to support life. 
 Sir H. Davy first shewed, that by breathing 
 a few quarts of it, contained in a silk bag, 
 for two or three minutes, effects analogous 
 to those occasioned by drinking fermented 
 liquors, were produced. Individuals, who 
 differ in temperament, are, however, as we 
 might expect, differently affected. 
 
 Sir H. Davy describes the effect it had 
 upon him, as follows : — “ Having previously 
 closed my nostrils, and exhausted my lungs, 
 I breathed four quarts of nitrous oxide from 
 and into a silk bag. The first feelings were 
 similar to those produced in the last experi- 
 ment, (giddiness) ; but in less than half a 
 minute the respiration being continued, they 
 diminished gradually, and were succeeded 
 by a sensation analogous to gentle pressure 
 on all the muscles, attended by an highly 
 pleasurable thrilling, particularly in the 
 chest and the extremities. The objects 
 around me became dazzling, and my hearing 
 more acute. Towards the last inspiration 
 the thrilling increased, the sense of muscular 
 power became greater, and at last an irresis- 
 tible propensity to action was indulged in. 
 I recollected but indistinctly what followed ; 
 I know that my motions were various and 
 violent. 
 
 “ These effects very soon ceased after res- 
 piration. In ten minutes I had recovered 
 my natural state of mind. Ihe thrilling in 
 the extremities continued longer than the 
 other sensations.” 
 
 “ The gas has been breathed by a very 
 
NIT 
 
 NIT 
 
 great number of persons, and almost every 
 one has observed the same things. On 
 some few, indeed, it has no effect whatever, 
 and on others the effects are always pain- 
 ful. 
 
 “ Mr J. W. Tobin, (after the first imperfect 
 trials), when the air was pure, experienced 
 sometimes sublime emotions with tranquil 
 gestures, sometimes violent muscular action, 
 with sensations indescribably exquisite ; no 
 subsequent debility — no exhaustion ; — his 
 trials have been very numerous. Of late 
 he has only felt sedate pleasure. In Sir 
 H. Davy the effect is not diminished. 
 
 “ Mr James Thomson. Involuntary laugh- 
 ter, thrilling in his toes and fingers, exqui- 
 site sensations of pleasure. A pain in the 
 back and knees, occasioned by fatigue the 
 day before, recurred a few minutes after- 
 wards. A similar observation, we think, 
 we have made on others ; and we impute it 
 to the undoubted power of the gas to increase 
 the sensibility or nervous power, beyond any 
 other agent, and probably in a peculiar man- 
 ner. 
 
 “Mr Thomas Pople. At first unpleasant 
 feelings of tension ; afterwards agreeable 
 luxurious languor, with suspension of mus- 
 cular power; lastly, powers increased both 
 of body and mind. 
 
 “ Mr Stephen Hammick, surgeon of the 
 Royal Hospital, Plymouth. In a small 
 dose, yawning and languor. It should be 
 observed that the first sensation has often 
 been disagreeable, as giddiness ; and a few 
 persons, previously apprehensive, have left 
 off inhaling as soon as they felt this. Two 
 larger doses produced a glow r , unrestrainable 
 tendency to muscular action, high spirits and 
 more vivid ideas. A bag of common air 
 was first given to Mr Hammick, and he ob- 
 served that it produced no effect. The 
 same precaution against the delusions of 
 imagination was of course frequently taken. 
 
 “ Mr Robert Southey could not distinguish 
 between the first effects and an apprehen- 
 sion of which he was unable to divest him- 
 self. His first definite sensations w'ere, a full- 
 ness and dizziness in the head, such as to 
 induce a fear of falling. This was succeed- 
 ed by a laugh which was involuntary, but 
 highly pleasurable, accompanied with a pe- 
 culiar thrilling in the extremities, a sensation 
 perfectly new and delightful. For many 
 hours after this experiment, he imagined 
 that his taste and smell were more acute, 
 and is certain that he felt unusually strong and 
 cheerful. In a second experiment, he felt 
 pleasure still superior, and has once poeti- 
 cally remarked, that he supposes the atmos- 
 phere ol the highest of all possible heavens 
 to be composed of this gas. 
 
 Robert Kinglake, M. D. Additional 
 freedom and power of respiration, succeed- 
 ed by an almost delirious, but highly plea- 
 
 surable sensation in the head, which became 
 universal w r ith increased tone of the muscles. 
 At last, an intoxicating placidity absorbed 
 for five minutes all voluntary powder, and left 
 a cheerfulness and alacrity for several hours. 
 A second stronger dose produced a perfect 
 trance for about a minute ; then a glow per- 
 vaded the system. The permanent effects 
 were an invigorated feeling of vital pow r er, 
 and improved spirits. By both trials, par- 
 ticularly by the former, old rheumatic feel- 
 ings seemed to be revived for the moment. 
 
 “ Mr Wedgwood breathed atmospheric air 
 first, without knowing it was so. He de- 
 clared it to have no effect, which confirmed 
 him in his disbelief of the power of the gas. 
 After breathing this some time, however, 
 he threw the bag from him, kept breathing 
 on laboriously with an open mouth, holding 
 his nose with his left hand, without power to 
 take it away, though aware of the ludicrous- 
 ness of his situation ; all his muscles seemed 
 to be t.hrowm into vibrating motions ; he had 
 a violent inclination to make antic gestures, 
 seemed lighter than the atmosphere, and a9 
 if about to mount. Before the experiment, 
 he was a good deal fatigued after a long 
 ride, of which he permanently lost all sense. 
 In a second experiment, nearly the same 
 effect, but with less pleasure. In a third, 
 much greater pleasure.” Res. on nit. ox. 
 
 I have often verified these pleasurable 
 effects, on myself and my pupils. The causes 
 of failure, in most cases, I believe to be, im- 
 pure gas, a narrow' tube or stop-cock, or pre- 
 cipitate breathing, from fear. If a little sul- 
 phate or muriate be mixed with the nitrate 
 of ammonia, it will not yield an intoxicating’ 
 gas. I use a pretty w ide glass tube, fixed 
 to the mouth of a large bladder. 
 
 I find that mice, introduced into a jar 
 containing nitrous oxide, die almost instant- 
 ly ; while in azote, hydrogen, and carbonic 
 acid, they struggle for a little wdiile. 
 
 This gaseous compound may be analyzed 
 by the combustion of hydrogen, carbon, or 
 phosphorus in it. If we mix 100 volumes 
 of nitrous oxide with 100 of hydrogen; and 
 detonate the mixture in an explosive eudio- 
 meter, nothing will remain but 100 mea- 
 sures of azote. Hence 50 measures of oxy- 
 gen, the equivalent quantity of 100 of hydro- 
 gen, must have existed in the oxide. It 
 therefore consists of 100 measures of azote 
 + 50 of oxygen, condensed by reciprocal 
 attraction, into only 100 measures. 
 
 Now 100 vol. of azote, weigh 0.9722 
 
 f HI - 11 
 
 50 of oxygen, — — = 0.5555 
 
 1.5277 
 
 *his synthetic sum, exactly coincides with 
 the specific gravity of the compound. It is 
 therefore composed by weight of one prime 
 
NIT 
 
 NIT 
 
 equivalent of azote, = 1.75 63. 64 
 
 one of oxygen, ='1.00 36.36 
 
 2.7 5 100.00 
 
 Ihe weight of the compound prime, is the 
 same with that of carbonic acid. 
 
 Iron wire burns with brilliancy in the 
 above gas, but it is soon extinguished. 
 
 2. J) cut oxide of' azote, or 'nitric oxide, was 
 
 first described by Dr Priestley in 1772. Into 
 
 a glass retort, containing copper turnings, 
 
 pour nitric acid diluted with 6 or 8 times its 
 
 quantity of water, and apply a gentle heat. 
 
 A gas comes over, which may be collected 
 
 over water ; but for exact experiments, it 
 
 should be received over mercury. Its sp.gr. 
 
 is 1.0416. 100 cubic inches weigh 36.77 
 
 grains. Water condenses only about J_ of 
 7 . .... 26 
 its volume of nitric oxide. But a solution 
 
 of proto-sulphate or proto-muriate of iron, 
 absorbs it very copiously, forming a dark co- 
 loured liquid, wfiich is used for condensing 
 oxygen, in the eudiometer of Sir H. Davy. 
 
 When a jar of nitric oxide is opened in 
 the atmosphere, red fumes appear, in conse- 
 quence of the absorption of oxygen, and for- 
 mation of nitrous acid. When an animal is 
 made to inhale this gas, it is instantly des- 
 troyed by the formation of this acid, and 
 condensation of the oxvgen, in its lime’s. 
 When a burning taper is immersed in this 
 gas, it is extinguished ; as well as the flame 
 of sulphur. But inflamed phosphorus burns 
 in it, with great splendour. A mixture of 
 hydrogen gas and nitric oxide, burns with a 
 lambent green flame, but does not explode 
 by the electric spark ; though Fourcroy says 
 that it detonates on being passed through an 
 ignited porcelain tube. The pyrophorus of 
 Homberg spontaneously burns in it. 
 
 It is decomposable by several of the me- 
 tals, w hen they are heated in it, such as arse- 
 nic, zinc, and potassium in excess. It oxi- 
 dizes them, and affords half its volume of 
 azote. Charcoal ignited in it, by a burning 
 glass, produces half a volume of azote, and 
 half a volume of carbonic acid. All these 
 analytical experiments concur to shew’ - , that 
 nitric oxide consists of oxygen and azote, in 
 equal volumes. Hence, if we take the mean 
 w'eigh t of a volume of each gas, we shall 
 have that of the gaseous compound ; or, its 
 
 sp. gr. 
 
 Az0t0 ’ 2.083; 
 
 1, 1.11115 
 
 Sum. Hf. sum or sp. gr 
 3 1.0416 
 
 Oxygen 
 
 If we convert these into equivalent ratios, 
 we shall have the gas composed of 
 
 1 prime of azote = 1.75 46.66 
 
 2 primes oxygen = 2.00 53.33 
 
 100.00 
 
 When this deutoxide is exposed at ordi- 
 nary temperatures, to bodies which have a 
 strong attraction for oxygen, such as the sul- 
 
 phites, protomuriate of tin, and the alkaline 
 hydrosulphurets, two volumes of it are con- 
 verted into one volume of the protoxide. We 
 see here, that when one prime of oxygen is 
 ubsti acted, the remaining one enters into a 
 denser state of union with azote. 
 
 For the habitudes of this gas with hydro- 
 gen, see Ammonia ; and with oxygen, see 
 Eudiometer, and Nitric and Nitrous 
 Acids. 
 
 Azote combines with chlorine and iodine, 
 to form two very formidable compounds. 
 
 1. The chloride of azote was discovered 
 about the beginning of 1 812, by M. Dulong; 
 but its nature was first investigated and as- 
 certained by Sir II. Davy. 
 
 But into an evaporating porcelain basin, 
 a solution of one part of nitrate or muriate 
 of ammonia in 10 of water, heated to about 
 100°, and invert into it a wide mouthed 
 bottle filled with chlorine. As the liquid 
 ascends by the condensation of the gas, oily- 
 looking drops are seen floating on its sur- 
 face, which collect together, and fall to the 
 bottom in large globules. This is chloride 
 of azote. By putting a thin stratum of 
 common salt into the bottom of the basin, 
 we prevent the decomposition of the chloride 
 of azote, by the ammoniacal salt. It should 
 be formed only in very small quantities. 
 The chloride of azote thus obtained, is an 
 oily-looking liquid; of a yellow colour; and 
 a very pungent intolerable odour, similar to 
 that of chloro-carbonous acid. Its sp. gr. is 
 1.653. When tepid water is poured into a 
 glass containing it, it expands into a volume 
 of clastic fluid, of an orange colour, which 
 diminishes as it passes through the water. 
 
 “ I attempted,” says Sir II. Davy', “ to 
 collect the products of the explosion of the 
 new substance, by applying the heat of a 
 spirit-lamp to a globule of it, confined in a 
 curved glass tube over water : a little gas was 
 at first extricated ; but long before the water 
 had attained the temperature of ebullition, a 
 violent flash of light was perceived, with a 
 sharp report ; the tube and glass were broken 
 into small fragments, and I received a se- 
 vere wound in the transparent cornea of the 
 eye, which has produced a considerable inflam- 
 mation of the eye, and obliges me to make 
 this communication by an amanuensis. This 
 experiment proves what extreme caution is 
 necessary in operating on this substance, for 
 the quantity I used was scarcely as large as 
 a grain of mustard- seed.” — Fhil. Tran. 1 81 3, 
 part I. It evaporates pretty rapidly in the 
 air; and in»vacuo it expands into a vapour, 
 which still possesses the power of exploding 
 by heat. When it is cooled artificially in 
 water, or the ammoniacal solution, to 40° F., 
 the surrounding fluid congeals ; but when 
 alone, it may be surrounded with a mixture 
 of ice and muriate of lime, without freezing. 
 
 It gradually disappears in water, produe- 
 
NIT 
 
 ing azote ; while the water becomes acid, ac- 
 quiring the taste and smell of a weak solu- 
 tion of nitro-muriatic acid. 
 
 With muriatic and nitric acids, it yields 
 azote; and with dilute sulphuric acid, a 
 mixture of azote and oxygen. In strong so- 
 lutions of ammonia it detonates ; with weak 
 ones, it affords azote. 
 
 When it was exposed to pure mercury, 
 out of the contact of water, a white powder 
 (calomel) and azote were the results. “ The 
 action of mercury on the compound,” says 
 Sir II. “• appeared to offer a more correct 
 and less dangerous mode of attempting its 
 analysis ; but on introducing two grains, 
 under a glass tube filled with mercury and 
 inverted, a violent detonation occurred, by 
 which I was slightly wounded in the head 
 and hands, and should have been severely 
 wounded, had not my eyes and face been 
 defended by a plate of glass, attached to a 
 proper cap ; a precaution very necessary in 
 all investigations of this body.” — Phil. Trans. 
 1813, part 2d. In using smaller quantities, 
 and recently distilled mercury, he obtained 
 the results of the experiments, without any 
 violence of action. 
 
 From his admirable experiments on the 
 analysis of this formidable substance, by mer- 
 cury, by muriatic acid, and from the discolo- 
 ration of sulphate of indigo, we may infer its 
 composition to be 
 
 4 vol. of chlorine = 10. 4 primes 18.0 
 
 1 of azote = 0.9722 1 1.75 
 
 or very nearly 10 by weight of chlorine to 1 
 of azote. 
 
 A small globule of it, thrown into a glass 
 of olive oil, produced a most violent explo- 
 sion ; and the glass, though strong, was 
 broken into fragments. Similar effects were 
 produced by its action on oil of turpentine 
 and naphtha. When it was thrown into ether 
 or alcohol, there was a very slight action. 
 When a particle of it was touched under 
 water by a particle of phosphorus, a brilliant 
 light was perceived under the water, and 
 permanent gas was disengaged, having the 
 characters of azote. 
 
 When quantities larger than a grain of 
 mustard-seed were used for the contact with 
 phosphorus, the explosion was always so vio- 
 lent as to break the vessel in which the ex- 
 periment was made. On tinfoil and zinc it 
 exerted no action ; nor on sulphur and re- 
 sin. Hut it detonated most violently when 
 i ’thrown into a solution of phosphorus in ether 
 i or alcohol. 
 
 The mechanical force of this compound in 
 'detonation, seems superior to that of any 
 ♦other known, not even excepting the ammo- 
 miacal fulminating silver. The velocity of 
 ■its action appears to he likewise greater. I 
 •touched a minute globule of it, in a platina 
 ^poon resting on a table, with a fragment of 
 Iphosphorus at the point of a penknife. The 
 
 NIT 
 
 blade was instantly shivered into fragments 
 by the explosion. 
 
 Messrs Porrett, Wilson, and Rupert Kirk, 
 brought 125 different substances in contact 
 with it. The following were the only ones 
 which caused it to explode: — 
 
 ►Supersulphuretted hydrogen. 
 Phosphorus. 
 
 Phosphuret of lime. 
 
 Phosphuretted camphor. 
 
 Camphuretted oil. 
 
 Phosuhuretted hydrogen gas. 
 Caoutchouc. 
 
 Myrrh. 
 
 Palm oil. 
 
 Ambergris. 
 
 Whale oil. 
 
 Linseed oil. 
 
 Olive oil. 
 
 Sulphuretted oil. 
 
 Oil of turpentine. 
 
 - tar. 
 
 amber. 
 
 petroleum. 
 
 orange-peel. 
 
 Naphtha. 
 
 Soap of silver. 
 
 — mercury. 
 
 ■ copper. 
 
 lead. 
 
 manganese. 
 
 Fused potash. 
 
 Aqueous ammonia. 
 
 Nitrous gas. — Nich . Jo urn* vol. 34. 
 
 2. Iodide of azote. Azote does not combine 
 directly with iodine. We obtain the combina- 
 tion only by means of ammonia. It was disco- 
 vered by M. Courtois, and carefully examined 
 by M. Colin. When ammoniacal gas is passed 
 over iodine, a viscid shining liquid is imme- 
 diately formed of a brownish-black colour, 
 which, in proportion as it is saturated with 
 ammonia, loses its lustre and viscosity. No 
 gas is disengaged during the formation of 
 this liquid, which may be called iodide of 
 ammonia. It is not fulminating. When 
 dissolved in water, a part of the ammonia is 
 decomposed ; its hydrogen forms hydriodic 
 acid ; and its azote combines with a portion 
 of the iodine, and forms the fulminating 
 powder. We may obtain the iodide of azote 
 directly, by putting pulverulent iodine into 
 common water of ammonia. This indeed is 
 the best way of preparing it ; for the water 
 is not decomposed, and seems to concur in 
 the production of this iodide, only by deter- 
 mining the formation of hydriodate of am- 
 monia. 
 
 The iodide of azote is pulverulent, and of 
 a brownish- black colour. It. detonates from 
 the smallest shock, and from heat, with a 
 feeble violet vapour. When properly pre- 
 pared, it often detonates spontaneously. 
 Hence, after the black powder is formed. 
 
OBS 
 
 OBS 
 
 and the liquid ammonia decanted off, we 
 must leave the capsule containing it in per- 
 fect repose. 
 
 When this iodide is put into potash water, 
 azote is disengaged, and the same products 
 are obtained, as when iodine is dissolved in 
 that akaline lixivium. The hydriodate of 
 ammonia, which has the property of dissolv- 
 ing a great deal of iodine, gradually decom- 
 poses the fulminating powder, while azote is 
 set at liberty. Water itself lias this pro- 
 perty, though in a much lower degree. As 
 the elements of iodide of azote are so feebly 
 united, it ought to be prepared with great 
 precautions, and should not be preserved. 
 In the act of transferring a little of it from 
 a platina capsule to a piece of paper, the 
 whole exploded in my hands, though the 
 friction of the particles on each other was 
 inappreciably small. 
 
 Both Sir II. Davy and M. Gay Lnssac 
 have exploded their iodide in glass tubes, 
 and collected the results. The latter states, 
 “ that if we decompose a gramme (15.444 
 grains) of the fulminating powder, we ob- 
 tain, at the temperature of 32°, and under 
 the pressure of 30 inches of mercury, a ga- 
 seous mixture amounting to 0.1152 litre, 
 (7.03 cubic inches), and composed of 0.08 64 
 of the vapour of iodine, and 0.0288 of azote.” 
 — Ann. de Chimie, xci. Now 0.0864 is to 
 0.0288 as 3 to 1 exactly. Therefore the de- 
 tonating powder consists of 
 S vols. of theva. of iod.= 8.63 X 3 = 25.89 
 1 vol. of azote = = 0.9722 
 
 or reduced to the oxygen equivalent scale, it 
 consists of 
 
 5 primes of iodine = 46.5 96.37 
 
 1 azote = 1.75 3.63 
 
 100.00 
 
 Azote has hitherto resisted all attempts to 
 decompose it. Sir II. Davy volatilized the 
 highly combustible metal potassium in azote 
 over mercury, and passed the voltaic flame 
 of 2000 double plates through the vapour, 
 but the azote underwent no change. He 
 made also many other attempts to decom- 
 pose it, but they were unsuccessful. 
 
 In my experiments on the ammoniacal 
 salts, I found, that when dry lime and mu- 
 riate of ammonia were iguited together in a 
 
 Reaumur porcelain tube, connected with 
 water in a V oolfe’s apparatus, a portion of 
 ammonia constantly disappeared, or was an- 
 nihilated, while nothing but water was ob- 
 tained to replace that loss. “ Of the tight- 
 ness of the apparatus 1 am well assured. 
 Indeed I have performed the experiment, 
 with a continuous glass tube, sealed and bent 
 down at one end like a retort, while the other 
 end was drawn into a small tube, which pass- 
 ed under a jar on the mercurial pneumatic 
 shelf. The middle part was kept horizontal 
 and artificially cooled. The sealed end con- 
 tained the mixture of lime and sal ammoniac. 
 A brush flame of a large alcohol blow- pipe 
 was made to play very gently on the end of 
 the tube at first, but afterwards so powerfully, 
 as to keep it ignited for some time. The sal 
 ammoniac recovered, did not exceed three- 
 fourths of that originally employed.” The 
 sal ammoniac was regenerated by saturating 
 the ammonia with muriatic acid, and cautious 
 evaporation. See Ann. of Phil. September 
 1817. 
 
 The strongest arguments for the compound 
 nature of azote are derived from its slight ten- 
 dency to combination, and from its being 
 found abundantly in the organs of animals, 
 which feed on substances that do not contain 
 it. 
 
 Its uses in the economy of the globe are 
 little understood. This is likewise favourable 
 to the idea that the real chemical nature is as 
 yet unknown, and leads to the hope of its 
 being decomposable. 
 
 It would appear that the atmospheric 
 azote and oxygen spontaneously combine in 
 other proportions, under certain circum- 
 stances, in natural operations. Thus we find, 
 that mild calcareous or alkaline matter, 
 favours the formation of nitric acid, in cer- 
 tain regions of the eartli ; and that they are 
 essential to its production in our artificial ar- 
 rangements, for forming nitre from decom- 
 posing animal and vegetable substances.* 
 
 Nitrous Acid. See Acid (Nitrous). 
 
 Noble Metals. This absurd name lias 
 been bestowed on the perfect metals, gold, 
 silver, and platina. 
 
 * Novaculite. Whktsi.ate. * 
 
 * Nux Vomica. See Strychnia.* 
 
 O 
 
 * ^BSIDIAN. Of this mineral there 
 Jk arc two kinds, the translucent and 
 transparent. 
 
 1. Translucent obsidian. Colour velvet- 
 black. Massive. Specular splendent, frac- 
 ture perfect conchoidal. Translucent, or 
 translucent on the edges. Hard. Very brit- 
 
 tle. Easily frangible. Streak grey. Sp. gr. 
 2.57. It melts, or becomes spongy before the 
 blow-pipe. Its constituents are, silica <8, alu- 
 mina 10, lime 1, soda 1.6, potash 6, oxide ot 
 iron 1. — Vauq. It occurs in beds in por- 
 
 phyry, and various secondary trap rocks in 
 Iceland and Tokay. 
 
OIL 
 
 OIL 
 
 2. Trcinsjmrcnt . Colour duck-blue. Mas- 
 sive and in brown grains. Splendent. Frac- 
 ture perfect conchoidal. Perfectly transpa- 
 rent. Hard. Brittle. Sp. gr. 2 .56. It 
 melts more easily than the translucent obsi- 
 dian, and into a white muddy glass. Its con- 
 stituents are, silica 81, alumina 9.5, lime 
 0.33, oxide of iron 0.60, potash 2.7, soda 4.5, 
 water 0.5. — Klaproth. It occurs imbedded 
 
 in pearl-stone porphyry. It is found at 
 Marekan, near Ochotsk in Siberia, and in 
 the Serro de las Novajas in Mexico.* 
 
 * Ochre. An ore of iron. * 
 
 * Ochroits. Cerite.* 
 
 * Octohedrite. Pyramidal titanium-ore.* 
 
 * Oetites. Clay-ironstone.* 
 
 * Oil of Vjtriol. See Acm (Sulphu- 
 ric).* 
 
 Oil. The distinctive characters of oil are 
 inflammability, insolubility in water, and 
 fluidity, at least in a moderate temperature. 
 Oils are distinguished into iixed or fat oils, 
 which do not rise in distillation at the tem- 
 perature of boiling water; and volatile or es- 
 sential oils, which do rise at that temperature 
 with water, or under 320° by themselves. 
 
 The volatile oil obtained by attenuating 
 animal oil, by a number of successive distil- 
 lations, is called Dippel’s animal oil. 
 
 Monnet asserts, that, by mixing acids with 
 animal oil, their rectification may be very 
 much facilitated. 
 
 The addition of a little ether, before re- 
 distiliation of old essential oils, improves the 
 flavour of the product. See Plain and 
 Acm (Oleic). 
 
 * MM. Gay Lussac and Thenard, ana- 
 lyzed olive oil in 1 808, by igniting a deter- 
 minate quantity of it, mixed with chlorate of 
 potash, and ascertaining the products ; they 
 found it to consist of 
 
 Carbon, 77.213 
 Hydrogen, 13.360 
 Oxygen, 9.427 
 
 100.000 
 
 Or Carbon, 77.213 
 
 ox. and by dr. in the pro- 7 
 portions for forming water, \ 
 
 Hydrogen excess, 12.075 
 If the pernitrate of mercury, made by 
 dissolving 6 parts of mercury in 7.5 parts of 
 nitric acid, of sp.gr. 1.36 at common tempe- 
 ratures, be mixed with olive oil, in the course 
 of a few hours, the mixture, if kept cold, be- 
 comes solid; but if mixed with the oil of 
 grains, it does not solidify. M. Pontet pro- 
 poses therefore this substance as a test of the 
 purity or adulteration of olive oil; for the 
 resulting mixture, after standing 12 hours, fo 
 more or less solid, as the oil is more or less 
 pure. The nature of the white, hard, and 
 opaque mixture, formed by olive oil, and the 
 nitrate of mercury, has not been ascertained. 
 See Acid Maugauic, ELain, and Fat.* 
 
 * Oil Gas. It has been long known to 
 chemists, that wax, oil, tallow, &c. when 
 passed through ignited tubes, are resolved 
 into combustible gaseous matter, which burns 
 with a rich light. Messrs Taylor and Mar- 
 tineau have availed themselves skilfully of 
 this fact, and contrived an ingenious appara- 
 tus for generating oil gas on the great scale, 
 as a substitute for candles, lamps, and coal 
 gas. I shall insert here, a brief account of 
 their improvements. 
 
 The advantages of oil gas, when contrasted 
 with coal gas, are the following : — The mate- 
 rial from which it is produced containing no 
 sulphur or other matter by which the gas is 
 contaminated, there are no objections to its 
 use on account of the suffocating smell in 
 close rooms. It does no sort of injury to 
 furniture, books, plate, pictures, paint, &c. 
 All the costly and offensive operation of 
 purifying the gas by lime, &c. is totally 
 avoided when it is obtained from oil. No- 
 thing is contained in oil gas which can pos- 
 sibly injure the metal of which the convey- 
 ance pipes are made. 
 
 The economy of light from oil gas may 
 be judged of from the following table : — 
 
 Argand burner oil gas, per hour, - 
 Argand lamps spermaceti oil, - Zd. 
 Mould candles, - - 
 
 Wax candles, - - 14d. 
 
 The oil gas has a material advantage over 
 coal gas, from its peculiar richness in ole- 
 fiant gas, which renders so small a volume 
 necessary, that one cube foot of oil gas will 
 be found to go as far as four of coal gas. 
 This circumstance is of great importance, as 
 it reduces in the same proportion the size of 
 the gasometers, which are necessary to con- 
 tain it: this is not only a great saving of ex- 
 pense in the construction, but is a material 
 convenience where room is limited. 
 
 In the course of their first experiments, 
 Messrs John and Philip Taylor were sur- 
 prised to find, that the apparatus they em- 
 ployed gradually lost its power of decompos- 
 ing oil, and generating ga9. On investiga- 
 tion, they discovered that the metallic retorts 
 which had originally decomposed oil and 
 produced gas in abundance, ceased in a very 
 great degree to possess this power, although 
 no visible change had taken place in them. 
 
 The most perfect cleaning of the interior 
 of the retort did not restore the effect, and 
 some alteration appears to be produced on 
 the iron by the action of the oil, at a high 
 temperature. 
 
 Fortunately, the experiments on this sub- 
 ject led to a most favourable result, for it 
 was found, that by introducing fragments of 
 brick into the retorts, a great increase of the 
 decomposing power was obtained, and the 
 apparatus has been much improved by a cir- 
 cumstance which at one time appeared to 
 threaten its success. 
 
OLI 
 
 OPA 
 
 A small portion of the oil introduced into 
 the retort, still passed of! undecomposed, and 
 being changed into a volatile oil, it carried 
 'with it a great portion of caloric, which ren- 
 dered the construction of the apparatus more 
 difficult than was at first anticipated; but 
 by the present arrangement of its parts, this 
 difficulty is fully provided for, and the vola- 
 tilized oil is made to return into the oil re- 
 servoir, from whence it again passes into the 
 retort, so that a total conversion of the whole 
 into gas is accomplished without trouble, or 
 the escape of any unpleasant smell. 
 
 A general idea of the process may be 
 formed from the following account of it : — 
 
 A quantity of oil is placed in an air-tight 
 vessel, in such a manner, that it may How 
 into retorts which are kept at a moderate 
 red-heat; and in such proportions as may 
 regulate the production of gas to a conveni- 
 ent rate; and it is provided, that this rate 
 may be easily governed at the will of the 
 operator. 
 
 The oil, in its passage through the retorts, 
 is principally decomposed, and converted in- 
 to gas proper for illumination, having the 
 great advantages of being pure and free from 
 sulphurous contamination, and of supporting 
 a very brilliant flame, with the expenditure 
 of very small quantities. 
 
 As a further precaution to purify the gas 
 from oil, which may be suspended in it in 
 the state of vapour, it is conveyed into a 
 wash' vessel, where, by bubbling through 
 water, it iT further cooled and rendered fit 
 for use ; and passes by a proper pipe into a 
 gasometer, from which it is suffered to 
 branch off in pipes in the usual manner. 
 
 The oil gas which I have been accustom- 
 ed to make has only a double illuminating 
 power, compared to good coal gas. — See a 
 drawing of an elegant apparatus, erected by 
 Messrs P. and M. at the Apothecaries’ Hall 
 London, in the 15th number of the Journal 
 of Science and the Arts.* 
 
 * Oisanite. Pyramidal titanium- ore.* 
 
 * Olefiant Gas. A compound of one 
 prime of carbon and one of hydrogen, to 
 which I have given the name of Carburet- 
 ted Hydrogen, to distinguish it from the 
 gas resulting from one prime of carbon and 
 two of hydrogen, which I have called sub- 
 carburetted hydrogen.* 
 
 * Oleic Acid. See Acid (Oleic).* 
 
 Oleosaccharum. This name is given to 
 
 a mixture of oil and sugar, incorporated 
 with each other, to render the oil more easi- 
 ly diffusible in watery liquors. 
 
 Oleum Vini. See Ether. 
 
 O libanum. A gum resin, the product of 
 the Juniperus Lycia, Linn . brought from 
 Turkey and the East Indies, usually in 
 drops or tears. The best is of a yellowish- 
 white colour, solid, hard, and brittle : when 
 
 chewed for a little time, it renders the spittle 
 
 26 
 
 white, and impresses an unpleasant bitterish 
 taste; laid on burning coals, it yields an 
 agreeable smell. 
 
 * Olivenite. An ore cf copper.* 
 Olivine. A sub-species of prismatic 
 
 chrysolite. Its colour is olive-green. It 
 occurs massive and in roundish pieces. 
 Rarely crystallized in imbedded rectangular 
 four-sided prisms. Lustre shining. Clea- 
 vage, imperfect double. Fracture, small- 
 grained uneven. Translucent. Less hard 
 than chrysolite. Brittle. Sp. gr. 5.24. With 
 borax it melts into a dark green bead. It 
 loses its colouring iron in nitric acid. Its 
 constituents are, silica 50, magnesia 38 .5, 
 lime 0.25, oxide of iron 12. It occurs in 
 basalt, greenstone, porphyry and lava, and 
 generally accompanied with augite. It is 
 found in the Lothians, Hebrides, nortli of 
 Ireland, Iceland, France, Bohemia, &c.* 
 
 * Ollaris Lapis. See Potstonf.. * 
 
 * Omphacite. Colour pale leek-green. 
 Massive, disseminated, and in narrow radiat- 
 ed concretions. Lustre, glistening and resi- 
 nous. Fracture, fine-grained uneven. Feebly 
 translucent. As hard as felspar. Sp. gr. 
 3.3. It occurs in primitive rocks with pre- 
 cious garnet, in Carinthia. It is a variety 
 of augite.* 
 
 * Onyx. Calcedony, in which there is 
 an alternation of white, black, and dark- 
 brown layers.* 
 
 * Opacity. The faculty of obstructing 
 the passage of light.* 
 
 * Otal. A sub-species of the indivisible 
 quartz of Mohs. 
 
 Of opal there are seven kinds, according 
 to Professor Jameson. 
 
 1. Precious opal. Colour milk-white, in- 
 clining to blue. It exhibits a beautiful play 
 of many colours. Massive, disseminated, 
 in plates and veins. Lustre splendent. 
 Fracture, perfect conchoidal. Translucent, 
 or semi-transparent. Semi-hard in a high 
 degree. Brittle. Uncommonly easily fran- 
 gible. Sp. gr. 2.1. Before the blow-pipe it 
 whitens and becomes opaque, but does nat 
 fuse. Its constituents are, silica 90, water 
 10. It occurs in small veins in clay-por- 
 phyry, with semi-opal, at Czscherwenitza, in 
 Upper Hungary ; and in trap rocks, at 
 Sandy Brae, in the north of Ireland. Some 
 of them become transparent by immersion 
 in water; and are called oculus mundi, hy- 
 drophane, or changeable opal. 
 
 2. Co-mmon opal. Colour milk-white. 
 Massive, disseminated, and in angular pieces. 
 Lustre splendent. Fracture perfect conchoi- 
 dal. Semi-transparent. Scratches glass. 
 Brittle. Adheres to the tongue. Infusible. 
 Its constituents are, silica 93.5, oxide of iron 
 1, water 5. — Klaproth. It occurs in veins 
 along with precious opal in clay-porphyry, 
 and in metalliferous veins in Cornwall, Ice- 
 land, and the north of Ireland. 
 
OPO 
 
 ORE 
 
 • 
 
 3. Fire opal. Colour hyacinth- red. Lus- 
 tre splendent. In distinct concretions. Frac- 
 ture perfect conchoidal. Completely trans- 
 parent. Hard. Uncommonly easily fran- 
 gible. Sp. gr. 2.12. Ileat changes the co- 
 lour to pale flesh- red. Its constituents are, 
 silica 92, water 7.7 5, iron 0.25. It has 
 been found only at Zimapan in Mexico, 
 in a particular variety of hornstone por- 
 phyry. 
 
 4. Mother-of-pearl opal , or Cackolong . It 
 is described under Caci-iolong, as a variety 
 of calcedony. 
 
 5. Semi-opal . Colours white, grey, and 
 brown ; sometimes in spotted, striped, or 
 clouded delineations. Massive, disseminat- 
 ed, and in imitative shapes. Lustre glisten- 
 ing. Fracture conchoidal. Translucent. 
 Semi-hard. Rather easily frangible. Sp. 
 gr. 2.0. Infusible. Its constituents are, si- 
 lica 85, alumina 3, oxide of iron 1.75, car- 
 bon 5, ammoniacal water 8, bituminous oil 
 0.33. — Klaproth. It occurs in porphyry and 
 amygdaloid, in Greenland, Iceland, and 
 Scotland, in the Isle of Rume, &c. 
 
 6. Jasper opal , or Ferruginous opal . Co- 
 lour scarlet-red, and grey. Massive. Lus- 
 tre shining. Fracture perfect conchoidal. 
 Gpaque. Between hard and semi- hard. 
 Easily frangible. Sp. gr. 2.0. Infusible. 
 Its constituents are, silica 43.5, oxide of iron 
 47.0, water 7.5. — Klaproth. It is found in 
 porphyry at Tokay in Hungary. 
 
 7. Wood opal. Colours very various. In 
 branched pieces and stems. Lustre shining. 
 Fracture conchoidal. Translucent. Semi- 
 hard in a high degree. Easily frangible. 
 Sp. gr. 2.1. It is found in alluvial land at 
 Zastravia in Hungary.* 
 
 * Opium. See Morphia, and Acid (Me- 
 con ic). In the 8th and 9th volumes of the 
 Journal of Science, and in the 1st of the 
 Edinburgh Phil. Journal, are two valuable 
 papers on the manufacture of British opium ; 
 the first by the Rev. G. Swaync, the second 
 by Mr Young. The manufacture of Indian 
 opium, has been of late years greatly improv- 
 ed by Dr Fleming, M. P., under whose su- 
 perintendence that important department was 
 placed by the Marquis of Wellesley. 
 
 According to Orfila, a dangerous dose of 
 opium is rather aggravated than counteract- 
 ed by vinegar. The proper remedy is a 
 powerful emetic, such as sulphate of zinc, or 
 sulphate of copper. See an interesting and 
 well treated case, in the 1st volume of the 
 Medico- Chirurgical Trans, by Dr Marcet 
 and Mr Astley Cooper.* 
 
 Opobalsam. The most precious of the 
 balsams is that commonly called Balm of 
 Gilead, Opobalsam urn, Balsanneleon, Bal- 
 samum verum album, /Egyptiacum, Judai- 
 cum, Syriacum, e Mecca, See. This is the 
 produce of the amyris opobalsamum, L. 
 
 i he true balsam is ol a pale yellowish 
 
 colour, clear and transparent, about the con- 
 sistence of Venice turpentine, of a strong, 
 penetrating, agreeable, aromatic smell, and 
 a slightly bitterish pungent taste. By age it 
 becomes yellower, browner, and thicker, los- 
 ing by degrees, like volatile oils, some of its 
 finer and more subtile parts. To spread, 
 when dropped into w r ater, all over the sur- 
 face, and to form a fine, thin, rainbow- 
 coloured cuticle, so tenacious that it may bo 
 taken up entire by the point of a needle, 
 were formerly infallible criteria of the ge- 
 nuine opobalsam. Neumann, however, had 
 observed, that other balsams, when of a cer- 
 tain degree of consistence, exhibit these phe- 
 nomena equally with the Egyptian. Accord- 
 ing to Bruce, if dropped on a woollen cloth, 
 in its pure and, fresh state, it may be washed 
 out completely and readily with simple wa- 
 ter. 
 
 Opodeldoc. A solution of soap in alco- 
 hol, with the addition of camphor, and vola- 
 tile oils. It is used externally against rheu- 
 matic pains, sprains, bruises, and other like 
 complaints. 
 
 OropANAX. A concrete gummy resinous 
 juice, obtained from the roots of an umbel- 
 liferous plant, the pastinaca opopanax, Linn. 
 which grows spontaneously in the warmer 
 countries, and bears the colds of this. The 
 juice is brought from Turkey and the East 
 Indies, sometimes in round drops or tears, 
 but more commonly in irregular lumps, of a 
 reddish-yellow colour on the outside, with 
 specks of white; imvardly of a paler colour, 
 and frequently variegated with large white 
 pieces. It has a peculiar strong smell, and 
 a bitter, acrid, somewhat nauseous taste. 
 
 * Ores. The mineral, bodies, from which 
 metals are extracted. 
 
 I. Antimony, Ores of 
 
 1. Native antimony, of which there are 
 two species ; dodecahedral, and octohedral. 
 
 1. Dodecahedral. Colour tin- white. Mas- 
 sive and crystallized in an octohcdron and 
 dodecahedron. Harder than calcareous spar* 
 Sp. gr. 6.7. It comsists of 98 antimony, 
 1.0 silver, and 0.25 iron. It is found in 
 argentiferous veins in the gneiss mountains 
 of Chalanches in Dauphiny, and at Andreas- 
 berg in the Harts. 
 
 2. Octohedral antimony ; of which there 
 are two sub-species, the antimonial silver, 
 and arsenical silver. See Ores of Silver. 
 
 II. Antimony Glance. Under this ge- 
 nus are ranged the following species, sub- 
 species, and kinds. 
 
 1. Compact grey antimony. Colour light 
 lead- grey. Massive. Soft. Easily frangi- 
 ble. Sp. gi . 4.4. bound in Iluel Boys 
 mine in Cornwall. 
 
 2. Foliated grey antimony. Colour like 
 the preceding. Cleavage prismatic. Not 
 particularly brittle. Sp. gr. 4.4. 
 
 3. liudiutcd grey antimony . Colour com- 
 
ORE 
 
 ORE 
 
 mon lead-grey. Massive, and crystallized in 
 four and six-sided prisms, and sometimes in 
 acicular crystals. Lustre metallic. Sp. gr. 
 4.4. It melts by the llame of a candle. Its 
 constituents are, antimony 75, sulphur 25. 
 These minerals occur in veins, in primitive 
 and transition mountains. This occurs in 
 Glendinning in Dumfries-shire ; in Cornwall, 
 &c. 
 
 4. Plumose grey antimony. Colour be- 
 tween dark lead-grey and smoke-grey. Mas- 
 sive, and in capillary glistening crystals. 
 Lustre semi-metallic. Very soft. It melts 
 into a black slag. It contains antimony, 
 sulphur, arsenic, iron, and silver. It occurs 
 in veins in primitive rocks, at Andreasberg 
 in the Hartz, &c. 
 
 5. Axifrangible antimony glance, or JBour- 
 nonite . Colour blackish lead- grey. Mas- 
 sive and crystallized. Primitive form, an 
 oblique four- sided prism, which occurs va- 
 riously modified by truncation, &c. Lustre 
 metallic. Cleavage axifrangible. Fracture 
 conchoidal. Brittle. Sp. gr. 5.7. Its con- 
 stituents are, lead 4 ‘2.62, antimony 24.23, 
 copper 12.8, iron 1.2, sulphur 17. — Hatchett. 
 It is found near Endellion in Cornwall. 
 
 6. Prismatic antimony glance. Colour 
 blackish lead-grey. Primitive form, an 
 oblique four-sided prism. Lustre metallic. 
 Cleavage in the direction of the smaller dia- 
 gonal of the prism. Sp. gr. 5.75. 
 
 III. Antimony ochre. Colour straw-yellow, 
 inerusting crystals of grey antimony. Dull. 
 Fracture earthy. Very soft. Brittle. Whitens 
 and evaporates before the blow- pipe, It oc- 
 curs in veins in Saxony, &c. 
 
 IV. Nickeliferous grey antimony. Colour 
 steel-grey. Massive. Shining. Cleavage 
 double rectangular. Fragments cubical. 
 Brittle. Sp. gr. 6. to 6.7. It melts before 
 the blow-pipe, emitting white vapour of arse- 
 nic. It communicates a green colour to 
 nitric acid. Tt consists of antimony, with 
 arsenic 61.68, nickel 23. 33, sulphur 14.16, 
 silica, with silver and lead, 0.83, and a trace 
 of iron. It occurs in veins near Freussberg 
 in Nassau. 
 
 V. Prismatic white antimony. Colour 
 white. Massive and crystallized, in a rec- 
 tangular four- sided prism, an oblique four- 
 sided prism, a rectangular four-sided table, 
 a six-sided prism, and in acicular and capil- 
 lary crystals. Lustre pearly or adamantine. 
 Cleavage in the direction of the lateral planes. 
 Translucent. Sectile. Sp. gr. 5.0 to 5.6. 
 It melts and volatilizes in a white vapour. Its 
 constituents are, oxide of antimony 86, oxides 
 of antimony and iron 3, silica 8. It occurs 
 in veins in primitive rocks, in Bohemia and 
 Hungary. 
 
 VI. Prismatic antimony -blende, or red an- 
 timony. 
 
 a. Common. Colour cherry-red. Mas- 
 sive, in flakes, and crystallized. Primitive 
 
 form, an oblique four-sided prism. Crystals 
 delicate, capillary. Adamantine. Translu- 
 cent on the edges. Brittle. Sp. gr. 4.5 to 
 4.6. It melts and evaporates before the 
 blow-pipe. It consists of antimony 67.5, 
 oxygen 10.8, sulphur 19.7. — Klapr. It oc- 
 curs at Braunsdorf in Saxony. 
 
 b . Tinder antimony-blende. Colour muddy 
 cherry-red. In flexible tinder like leaves. 
 Feebly glimmering. Opaque. Streak shin- 
 ing. Friable. Sectile and flexible. It con- 
 tains oxide of antimony 33, oxide of iron 40, 
 oxide of lead 16, sulphur 4, with some silver. 
 — Link. It occurs in the Carolina and Do- 
 
 rothea mines at Clausthal. 
 
 II. — Arsenic. 
 
 1. Native arsenic. Fresh fracture, whit- 
 ish lead-grey. Massive, and in imitative 
 shapes. Feebly glimmering. Harder than 
 calcareous spar. Streak shining, metallic. 
 When struck, it has a ringing sound, and 
 emits an arsenical odour. Sp. gr. 5.75. It 
 occurs in veins in primitive rocks, at Kongs- 
 berg in Norway, Sec. 
 
 2. Oxide of arsenic; common, capillary, 
 and earthy. 
 
 a. Common oxide has a white colour ; 
 occurs in crystalline crusts ; has a shining 
 lustre; uneven fracture; and is soft and 
 semi-transparent. 
 
 b. The capillary occurs in silky, snow- 
 white, shining, capillary crystals. 
 
 c. The earthy is yellowish- white ; in 
 crusts. Dull, opaque, and friable. It oc- 
 curs at Andreasberg in the Hartz. 
 
 3. Arsenical pyrites. 
 
 a. Common arsenical pyrites. Mispickel. 
 Fresh fracture silver- white. Massive and in 
 prismatic concretions. Crystallized in oblique 
 four- sided prisms. Lustre splendent metal- 
 lic. Fracture coarse-grained. Cleavage in 
 the direction of the perpendicular prism. 
 Sometimes as hard as felspar. Brittle. It 
 emits an arsenical smell on friction. Sp. gr. 
 5.7 to 6.2. Before the blow-pipe it yields 
 a copious arsenical vapour. Its constituents 
 are, arsenic 43.4, iron 34.9, sulphur 20.1. 
 It occurs in primitive rocks, in Cornwall and 
 Devonshire, and at Alva in Stirlingshire. 
 
 b. Argentiferous arsenical pyrites. Colour 
 silver-white. Disseminated, and in very small 
 acicular oblique four-sided prisms. Shining 
 and metallic. Besides arsenic and iron, it 
 contains from 0.01 to 0.10 of silver. It has 
 been found in Saxony ; and is used as an 
 ore of silver. 
 
 4. Pharmacolite, or arsenic-bloom. C o- 
 
 lour reddish- white. As a coating of balls, 
 
 or in delicate capillary shining silky crystals. 
 Semi-transparent, or opaque. Soft. Soils. 
 Sp. gr. 2.64. Its constituents are, lime 25, 
 arsenic acid 50.44, water 24.56. It occurs 
 in veins along with tin-white cobalt, at An- 
 dreasberg, &c. 
 
 5. Orpiment. 
 
ORE 
 
 ORE 
 
 а. Red, ruby sulphur , or hemi-prismatic 
 sulphur. Colour aurora-red ; massive ; in 
 flakes, and crystallized in oblique tour-sided 
 prisms. Lustre inclining to adamantine. 
 Fracture uneven. Translucent. Streak 
 orange-yellow coloured. As hard as talc. 
 Brittle. Sp. gr. 5.35. It melts and burns 
 with a blue flame. It is idio-electric by tiic- 
 tion. Its constituents are, arsenic 69, sul- 
 phur 51. It occurs in primitive rocks at 
 Andreasberg, &c. 
 
 б. Yellow orpiment, or prismatoidal sul- 
 phur. Colour perfect lemon-yellow. Mas- 
 sive, imitative, and crystallized in oblique 
 four-sided prisms, and in flat double four- 
 sided pyramids. Cleavage prismatoidal. 
 Translucent. Harder than the red. Flexi- 
 ble, but not elastic. Splits easily. Sp. gr. 
 3.5. Its constituents are arsenic 62, sulphur 
 38. It occurs in veins in floetz rocks ; and 
 along with red silver in granite at W ittichen 
 in Swabia. 
 
 III. — Bismuth. 
 
 1. Native or octohedral bismuth. Fresh 
 fracture silver-white, inclining to red. Mas- 
 sive and crystallized in an octohedron, tetra- 
 hedron, and cube. Lustre splendent, me- 
 tallic. Cleavage fourfold. Harder than 
 gypsum. Malleable. Sp. gr. 8.9 to 9.0. 
 It melts by the flame of a candle. It occurs 
 in veins in mica-slate, &c. at St Columb 
 and Botallack, in Cornwall ; and in Saxony 
 
 2. Bismuth- glance. 
 
 a. Aciculur bismuth- glance. Colour dark 
 lead-grey. Disseminated, and crystallized 
 in oblique four or six-sided prisms. Lus- 
 tre splendent, metallic. Fracture uneven. 
 Opaque. Brittle. Sp.gr. 6.1 to 6. 2. it 
 fuses before the blow-pipe into a steel- grey 
 globule. Its constituents are, bismuth 43.2, 
 lead 24.52, copper 12.1, sulphur 11.58, 
 nickel 1.58, tellurium 1.32, gold 0.79. It 
 occurs imbedded in quartz near Beresof in 
 Siberia. It is also called needle ore . 
 
 b. Prismatic bismuth-glance. Colour pale 
 lead-grey. Massive, and crystallized in aci- 
 cular and capillary oblique four and six-sided 
 prisms. Lustre splendent, metallic. It 
 soils ; is brittle ; and harder than gypsum. 
 Sj). gr. 6.1 to 6.4. It melts in the flame of 
 a candle. Its constituents are bismuth 60, 
 sulphur 40. It occurs in veins in Cornwall, 
 &c. 
 
 a. Cupreous bismuth. Colour light lead- 
 grey. Massive. Shining. Sectile. Its 
 constituents are, bismuth 47. 24, copper 34.6 6, 
 sulphur 12.58. It occurs in veins in gra- 
 nite near Wittichen in Furstembcrg. 
 
 O 
 
 b. Bismuth ochre. Colour straw- yellow. 
 Massive. Lustre inclines to adamantine. 
 Opaque. Soft. Brittle. Sp.gr. 4.37. It 
 dissolves with effervescence in acids. Its 
 constituents are, oxide of bismuth 86.5, oxide 
 ol iron 5.2, carbonic acid 4.1, water 3.4. It 
 
 occurs along with red cobalt. It is found at 
 St Agnes in Cornwall. 
 
 IV. — Cerium. See Allanite, Cekitf, 
 Gadolinite, Orthite, Yttkockkite. A 
 fluate and subfliiate of cerium have been 
 also discovered at Finbo in Sweden. 
 
 V. — Cobalt Ores. 
 
 1. Hcxahedral cobalt pyrites , or silver- 
 white cobalt. Colour silver-white. Massive, 
 and crystallized in the cube, octohedron, 
 cube truncated, pentagonal dodecahedron, 
 icosahedron. Splendent, and metallic. 
 Cleavage hexahedral. Fracture conchoidal. 
 Semi-hard. Brittle. Streak grey. Sp. gr. 
 6.1 to 6.3. Before the blow-pipe it gives 
 out an arsenical odour; and, after being 
 roasted, colours glass of borax smalt blue. 
 Its constituents are, cobalt 44, arsenic 55, 
 sulphur 0.5. Iron is sometimes present. 
 It occurs in primitive rocks at Skutterend, 
 in Norway. It is the principal ore of co- 
 balt. 
 
 2. Octohedral cobalt pyrites. 
 
 a. The tin-white ; of which there is the 
 compact and radiated. The compact has a 
 tin-white, and sometimes rather dark colour. 
 It occurs massive and crystallized in the 
 cube, octohedron, and rhomboidal dodecahe- 
 dron, truncated on the six four- edged angles. 
 Crystals generally rent and cracked. Lustre 
 splendent, metallic. Brittle. Sp. gr. 6.0 to 
 6.6. Its constituents are, arsenic 74.22, co- 
 balt 20 5, iron 3.42, copper 0.16, sulphur 
 0.89. It occurs in granite, gneiss, &c. in 
 Cornwall, Saxony, Sec. 
 
 The radiated ; colour tin- white, inclining 
 to grey. Massive, and in distinct radiated 
 concretions. Lustre glistening, metallic. 
 Softer than the compact. Its constituents, 
 are, arsenic 65.75, cobalt 28, oxide of iron 
 5.0, oxide of manganese 1.25. It occurs in 
 clay-slate at Schneeberg. 
 
 b. Grey octohedral cobalt pyrites. Colour 
 light steel-grey. Massive, and tubiform. 
 Dull, and tarnished externally. Internally 
 splendent metallic. Fracture even. Streak 
 shining. Brittle. When struck, emits an 
 arsenical odour. Sp.gr. 6. 155. It contains 
 19.6 of cobalt, with iron and arsenic. It 
 occurs in granite, gneiss, Sec. It is found in 
 Cornwall, Norway, Sec. It affords a more 
 beautiful blue smalt than any of the other 
 cobalt minerals. 
 
 Cobalt-kies. Colour pale steel-grey. 
 Massive, and in cubes. Lustre metallic. 
 Fracture uneven. Serai-hard. Its consti- 
 tuents are, cobalt 43.2, sulphur 38.5, copper 
 14.4, iron 5.55. It occurs in a bed of gneiss, 
 in Sweden. 
 
 3. lied cobalt. 
 
 a. Radiated red cobalt, or cobalt-bloom. 
 Colour crimson-red, passing into pench-blos- 
 sona. Massive, imitative, and crystallized, 
 in a rectangular four-sided prism, or a 
 
ORE 
 
 ORE 
 
 compressed acute double six-sided pyramid. 
 Crystals acicular. Shining. Translucent. 
 Rather sectile, Sp. gr. 4.0 to 4.3. It tinges 
 borax glass-blue. Its constituents are, co- 
 balt 89, arsenic acid 58, water 23. It occurs 
 in veins in primitive, transition, and second- 
 ary rocks. It is found at Alva in Stirling- 
 shire, in Cornwall, Sec. 
 
 b. Earthy reel cobalt , or cobalt-crust. Co- 
 lour, peach-blossom red. Massive, and imi- 
 tative. Friable. Dull. Sectile. Streak 
 shining. Does not soil. 
 
 c. Slaggy red cobalt. Colour muddy crim- 
 son-red. In crusts and reniform. Smooth. 
 Shining. Fracture conchoidal. Translu- 
 cent. Soft and brittle. It occurs at Ftirs- 
 temberg. 
 
 4. Cobalt-ochre. 
 
 a. Black. The earthy-black has a dark 
 brown colour; is friable, has a shining streak, 
 and feels meagre. The indurated black has 
 a bluish-black colour; occurs massive and 
 imitative ; has a glimmering lustre ; fine 
 earthy fracture ; is opaque ; soft ; sectile ; 
 soils ; sp. gr. 2. to 2.4. It consists of black 
 oxide of cobalt, with arsenic and oxide of 
 iron. These two sub-species occur usually 
 together ; in primitive or secondary moun- 
 tains ; at Alderly Edge, Cheshire, in red 
 sandstone; at Ilowth, near Dublin, in slate- 
 clay. 
 
 b. Brown cobalt-ochre . Colour liver- 
 brown. Massive. Dull. Fracture, fine 
 
 earthy. Opaque. Streak shining ; soft, sec- 
 tile, light. It consists of brown ochre of 
 cobalt, arsenic, and oxide of iron. It occurs 
 chiefly in secondary mountains. It is found 
 at Kamsdorf, in Saxony. 
 
 c. Yellow cobalt-ochre. Colour muddy 
 straw-yellow. Massive and incrusting. Rent. 
 Dull. Fracture line earthy. Streak shin- 
 ing. Soft and sectile. Sp.gr. 2.67, after 
 absorbing water. It is the purest of the co- 
 balt-ochres. It is found with the preceding. 
 It contains silver. 
 
 5. The sulphate of cobalt is found at Fiber, 
 near Hannau, in Germany. It consists of 
 sulphuric acid 19*74, oxide of cobalt 38.71, 
 water 41.55. It has a light Hesli-red co- 
 lour ; and a stalaetitical form. Streak yel- 
 lowish-white. Taste styptic. 
 
 VI. — Copper Ores. 
 
 1. Octahedral, or native copper. Colour 
 copper-red, frequently incrusted with green 
 Massive, imitative, and crystallized ; in the 
 perfect cube ; the cube truncated, on the 
 angles, on the edges, and on the edges and 
 angles; the garnet dodecahedron; perfect 
 octohedron ; and rectangular four-sided 
 prism. Lustre glimmering, metallic. Frac- 
 ture hackly. Streak splendent, metallic. 
 Harder than silver. Completely malleable. 
 Flexible, but not elastic. Difficultly fran- 
 gible. Sp. gr. 8.4 to 8.7. It consists of 
 99.8 of copper, with a trace of gold and 
 
 iron. It occurs in veins, in granite, gneiss, 
 &c, and is found chiefly in Cornwall. 
 
 2. Oclohedral red copper ore. 
 
 a. Foliated red copper ore. Colour dark 
 cochineal-red. Massive, and crystallized, in 
 the perfect octohedron, which is the primi- 
 tive form ; in the octohedron, truncated on 
 the angles ; on the edges, with each angle 
 acuminated with four planes; bevelled on 
 the edges, and each angle acuminated with 
 eight planes. Lustre adamantine, inclining 
 to semi- metallic. Cleavage fourfold. Trans- 
 lucent on the edges, or translucent. Streak 
 muddy tile- red. Hardness between calca- 
 reous and fluor spar. Brittle. Sp. gr. 5.6 
 to G.O. 
 
 b. Compact red copper ore. Colour be- 
 tween lead-grey and cochineal- red. Massive 
 and reniform. Lustre semi- metallic. Frac- 
 ture even. Opaque. Streak tile-red. Brittle. 
 
 c. Capillary red copper ore. Colour car- 
 mine-red. In small capillary crystals. Lus- 
 tre adamantine. Translucent. 
 
 The whole of these red ores are deutoxides 
 of copper, and are easily reduced to the me- 
 tallic state before the blow-pipe. They dis- 
 solve with effervescence when thrown in 
 powder into nitric acid ; and a green nitrate 
 results. In muriatic acid no effervescence 
 
 takes place. They occur principally in veins 
 that traverse primitive and transition rocks ; 
 abundantly in the granite of Cornwall. I he 
 earthy red copper ore, which is rare, is a 
 sub-species of the preceding. 
 
 d. Tile ore. The earthy tile ore has a 
 hyacinth-red colour. It occurs massive and 
 incrusting copper pyrites. It is composed 
 of dull dusty particles. It soils slightly, and 
 feels meagre. It occurs in veins, as at Lau- 
 terberg in the Hartz. The indurated tile 
 ore has an imperfect flat conchoidal fracture; 
 a streak feebly shining ; and is intermediate 
 between semi -hard and soft. It is an inti- 
 mate combination of red copper ore and 
 
 brown iron ochre, containing from 10 to oO 
 per cent of copper. 
 
 3. Black copper , or black oride of copper. 
 Colour between bluish and brownish-black. 
 It occurs massive, and thinly coating copper 
 pyrites. It is composed of dull dusty parti- 
 cles, which scarcely soil. Streak slightly 
 shining. Before the blow-pipe it emits a 
 sulphureous odour, melts into a slag, and 
 communicates a green colour to borax. It 
 is said to be an oxide of copper with oxide of 
 
 "on. It occurs at Carh arrack and lincrolt 
 nines, in Cornwall. 
 
 4. Emerald copper , or dioptase. Colour 
 ?merald green. It occurs only crystallized. 
 The primitive form is a rhomboid of l-o 3 
 58'. The only secondary form at present 
 known, is the equiangular six-sided prism. 
 Lustre shining, pearly. Cleavage threefold. 
 Fracture small conchoidal. 1 ranslucent. As 
 [jard as apatite. Brittle. Sp. gr. 3.8. It 
 
ORE 
 
 ORE 
 
 becomes a chesnut-brown before the blow- 
 pipe, and tinges the flame green, but is in- 
 fusible ; with borax it gives a bead of cop- 
 oer. Its constituents are, oxide of copper 
 28.57, carbonate of lime 42.83, silica 28.57. 
 — Vauq. By Lowitz, it consists of 55 oxide 
 of copper, 33 silica, and 12 water, in 100. 
 It is found in the land of Kirguise, 125 
 leagues from the Russian frontier, where it 
 is associated with malachite and limestone. 
 
 5. Blue copper , or prismatic malachite , of 
 which there are two kinds, the radiated and 
 earthy. 
 
 The radiated has an azure-blue colour. 
 Massive, imitative, and crystallized. Its pri- 
 mitive form is an oblique prism. Ihe se- 
 condary forms are, an oblique four- sided 
 prism, variously bevelled, and a rectangular 
 four-sided prism, or eight-sided prism, acu- 
 minated with four planes. Lustre vitreous. 
 Cleavage threefold, Fracture imperfect con- 
 choidal. Translucent. Colour of the streak, 
 lighter. Harder than calcareous spar. Brittle. 
 Sp. gr. 3.65. It is soluble with effervescence 
 in nitric acid. With borax it yields a me- 
 tallic globule, and colours the flux green. 
 Its constituents are, copper .56, carbonic acid 
 25, oxygen 12.5, water 6.5. — Vauquelin . It 
 is found at Leadhills in Dumfries-shire, and 
 Wanlockhead in Lanarkshire, and at Iluel- 
 Virgin and Carh arrack in Cornwall, and in 
 many places on the Continent. 
 
 b. Earthy blue copper. Colour smalt-blue. 
 Massive. Friable. Sp. gr. 3.354. It is 
 found in Norway, Sec. 
 
 The velvet-blue copper belongs to the same 
 species. Lustre glistening and pearly. It has 
 been found only at Oravicza in the Bannat, 
 along with malachite and the brown iron- 
 stone. 
 
 6. Malachite ; of which there are, the 
 fibrous and compact. 
 
 a. Fibrous malachite. Colour perfect eme- 
 
 rald-green. Imitative, and crystallized, in 
 oblique four-sided prisms, variously bevelled 
 or truncated ; and in an acute-angular three- 
 sided prism. Crystals short, capillary, and 
 acicular. Lustre pearly or silky. Trans- 
 lucent, or opaque. Softer than blue copper. 
 Streak pale green. Brittle. Sp. gr. 3.66. 
 Before the blow- pipe it decrepitates, and be- 
 comes black. Its constituents are, copper 
 58, carbonic acid 18, oxygen 12.5, water 
 11.5. — Klaproth. It occurs principally in 
 
 veins. It is found at Sandlodge in Main- 
 land, one of the Shetlands; at Landidno in 
 Caernarvonshire ; and in the mines of Ar- 
 endal in Norway. 
 
 b. Compact malachite. Colour emerald- 
 green. Massive, imitative, and in four-sided 
 prisms. Glimmering and silky. Fracture, 
 small grained uneven. Opaque. Streak 
 pale green. Sp. gr. 3.65. In veins, which 
 traverse different rocks in Cornwall, Nor- 
 "ay, &c. Brown copper i win Hindustan is 
 
 placed after this mineral by Professor Jame- 
 son. Its colour is dark blackish-brown. 
 Massive. Soft. Sp. gr. 2.62. It efferves- 
 ces in acids, letting fall a red powder. Its 
 constituents are, carbonic acid 16.7, deut- 
 oxide of copper 60.75, deutoxide of iron 
 
 19.5, silica 2.1. — Dr Thomson . 
 
 7. Copper-green. 
 
 Common copper-green, or chrysocolla, con- 
 tains three sub-species. 
 
 a. Conchoidal copper-green. Colour ver- 
 digris-green. Massive, imitative, and in- 
 crusting. Glistening. Fracture conchoidal. 
 Translucent. Harder than gypsum. Easily 
 frangible. Sp. gr. 2.0 to 2.2. It becomes 
 black and then brown before the blow-pipe, 
 but does not fuse. It melts and yields a 
 metallic globule with borax. Its constitu- 
 ents are, copper 40, oxygen 10, carbonic 
 acid 7, water 17, silica 26. — Klaproth. It 
 accompanies malachite. It is found in 
 Cornwall, Sec. 
 
 Siliceous copper , or kieselkupjer , is a varie- 
 ty of the above. Colour asparagus- green. 
 In crusts. Glistening. Fracture even or 
 earthy. Opaque. Soft. Its constituents 
 are, copper 37.8, oxygen 8, water 21.8, sili- 
 ca 29, sulphate of iron 5. 
 
 b. Earthy iron-shot copper-green. Colour 
 olive-green. Massive and in crusts. Friable. 
 Opaque. Sectile. 
 
 c. Slaggy iron- shot copper -green. Colour 
 blackish-green. Massive. Glistening. Frac- 
 ture conchoidal. Opaque. Soft. Easily 
 frangible. It is probably a compound of 
 conchoidal copper-green and oxide of iron. 
 Both occur together, and pass into each 
 other. It occurs in Cornwall, along with 
 olivenite. 
 
 8. Prismatic vitriol , blue vitriol , or sulphate 
 of copper . Colour dark sky-blue. Massive, 
 imitative, and crystallized. The primitive 
 figure is an oblique four-sided prism, in 
 which the lateral edges are 1 24° 2', and 55° 
 58' ; with edges and angles often truncated. 
 Shining. Cleavage double. Fracture con- 
 choidal. Translucent. Harder than gyp- 
 sum. Sp. gr, 2.1 to 2.2. Taste nauseous, 
 bitter, and metallic. Its solution coats iron 
 with metallic copper. Its constituents are, 
 oxide of copper 32.13, sulphuric acid 31,57, 
 water 36.3. — Berzelius. It occurs along 
 with copper pyrites, in Parys-mine in An- 
 glesea, and in Wicklow. 
 
 9. Pris matic olivenite , or phosphate of cop- 
 per. Colour emerald-green. Massive, and 
 in oblique four-sided prisms of 1 10°. Cleav- 
 age double oblique. Glistening. Fracture 
 splintery. Opaque. Streak verdigris- green. 
 As hard as apatite. Brittle. Sp. gr. 4. to 
 
 4.5. Fuses into a brownish globule. Its 
 constituents are, oxide of copper 68.13, phos- 
 phoric acid 30.95. It is found at Virnebirg 
 on the Rhine, along with quartz, red copper 
 ore, &c. 
 
ORE 
 
 ORE 
 
 1 0. JDi-prismatic olivenite , or lenticular cop- 
 per. Colour sky-blue. Massive, but gene- 
 rally crystallized. In very oblique four-sided 
 prisms, bevelled ; in rectangular double four- 
 sided pyramids ; shining ; fracture uneven ; 
 translucent. Harder than gypsum. Brittle. 
 Sp. gr. 2.85. Converted by the blow-pipe 
 into a black friable scoria. Its constituents 
 are, oxide of copper 49, arsenic acid 14, 
 water 85. — Chenevix . Found in Cornwall. 
 
 1 1. Acicular olivenite. a. Radiated or cup- 
 reous arseniate oj' iron. Colour dark verdi- 
 gris-green. Massive, imitative and in Hat 
 oblique four-sided prisms, acuminated or trun- 
 cated. Lustre glistening pearly. Translu- 
 cent on the edges. As hard as calcareous 
 spar. Brittle. Sp. gr. 3.4. 
 
 b. Foliated acicular olivenite ; arseniate 
 copper. Colour dark olive- green. In an- 
 gulo-granular concretions, and in small crys- 
 tals; which are oblique four-sided prisms ; and 
 acute double four-sided pyramids. Glistening. 
 Fracture conchoidal. Translucent. Streak 
 olive-green. As hard as calcareous spar. 
 Brittle. Sp. gr. 4.2 to 4.5. It boils, and gives 
 a hard reddish-brown scoria before the blow- 
 pipe. Its constituents are, oxide of copper 
 60, arsenic acid 39.7. — Chenevix. In the 
 copper mines of Cornwall. 
 
 c. Fibrous acicular olivenite. Colour 
 olive-green. Massive, reniform, and in 
 capillary and acicular oblique four- sided 
 prisms. Glistening and pearly. Opaque. 
 As hard as calc-spar. Brittle. Fibres 
 sometimes flexible. Streak brown or yel- 
 low. Sp. gr. 4.1 to 4.2. Its constituents 
 are, oxide of copper 50, arsenic acid 29, water 
 21. It occurs in Cornwall. 
 
 d. Earthy acicular olivenite. Colour olive- 
 green. Massive and in crusts. Dull. Frac- 
 ture fine earthy. Opaque. Very soft. It 
 is found in Cornwall. 
 
 12. Atacamite, or mu riate of copper. 
 
 a. Compact. Colour leek-green. Massive, 
 and in short needle-shaped crystals, which 
 are oblique four-sided prisms, bevelled or trun- 
 cated. Shining and pearly. Translucent on 
 the edges. Soft. Brittle. Sp. gr. 4.4 ? It 
 tinges the flame of the blow-pipe of a bright 
 green and blue, muriatic acid rises in va- 
 pours, and a bead of copper remains on the 
 charcoal. It dissolves without effervescence 
 in nitric acid. Its constituents are, oxide of 
 copper 73.0, water 16.9, muriatic acid 10.1. 
 — Klaproth. It occurs in veins in Chili, and 
 Saxon v. 
 
 b. Arenaceous alacamite, or copper- sand. 
 Colour grass-green. In glistening scaly par- 
 ticles. It does not soil. It is translucent. 
 Its constituents are, oxide of copper 63, water 
 12, muriatic acid 10, carbonate of iron 1, 
 mixed siliceous sand 11. It is found in the 
 sand of the river Lipes 200 leagues beyond 
 Copiapu in the desert of Atacama, which 
 separates Chili from Peru. 
 
 1 3. Copper Pyrites. 
 
 a. Octahedral copper pyrites. On the fresh 
 
 fracture, its colour is brass-yellow ; but it is 
 usually tarnished. Massive, imitative and 
 crystallized ; in a regular octohedron, perfect, 
 truncated or bevelled ; and in a perfect or 
 truncated tetrahedron. Glistening. Frac- 
 ture uneven. Hardness from calcareous to 
 fluorspar. Brittle. Sp. gr. 4.1 to 4.2. Before 
 the blow-pipe, on charcoal, it decrepitates, 
 emits a greenish-coloured sulphureous smoke, 
 and melts into a black globule, which as- 
 sumes metallic lustre. It tinges borax green. 
 Its constituents are, copper SO, iron 53, sul- 
 phur 12. — Chenevix. It contains sometimes 
 
 a little gold or silver. It occurs in all tho 
 great classes of rocks. It is found near 
 Tynedrum in Perthshire ; at the mines of 
 Ecton ; at Pary’s mountain ; abundantly in 
 Cornwall ; and in the county of Wicklow in 
 Ireland. The rich ores are worked for cop- 
 per ; the poor, for sulphur. 
 
 b. Tetrahedral copper pyrites ; of which 
 species there are two sub-species, grey copper 
 and black copper. 
 
 Grey-copper. Colour steel-grey. Massivo 
 and crystallized; in the tetrahedron, truncated 
 or bevelled; and in the rhomboidal dodeca- 
 hedron. Splendent. Fracture uneven. Hard- 
 ness as calcareous spar and fluor. Brittle. 
 Sp. gr. 4.4 to 4.9. Its constituents are, cop- 
 per 41, iron 22.5, sulphur 10, arsenic 24.1, 
 silver 0.4. — Klaproth. It occurs in beds and 
 veins in Cornwall, and many other places. 
 
 Black copper. Colour iron-black. Mas- 
 sive and crystallized; in the tetrahedron, per- 
 fect, bevelled, or truncated. Splendent. 
 Fracture conchoidal. Brittle. Sp. gr. 4.85. 
 Its constituents arc, copper 39, antimony 
 
 19.5, sulphur 26, iron 7.5, mercury 6.25. — 
 Klaproth. The mercury is accidental. It 
 occurs in veins in the Harlz, and in Peru. 
 
 14. White copper. Colour between silver- 
 white, and brass- yellow. Massive and dis- 
 seminated. Glistening and metallic. Frac- 
 ture uneven. Semi-hard. Brittle. Sp. gr. 
 
 4.5. It yields before the blow-pipe a white 
 arsenical vapour, and melts into a greyish- 
 black slag. It contains 40 per cent of cop- 
 per ; the rest being iron, arsenic and sulphur. 
 It occurs in primitive and transition rocks. 
 It is found in Cornwall and Saxony. 
 
 15. Copper- glance^ or vitreous copper. 
 
 Rh o mboidal copper-gla n ce. 
 
 § 1. Compact. Colour, blackish lead- 
 grev. Massive, in plates and crystallized. 
 Primitive form, a rhomboid. Secondary 
 forms ; a low equi-angular six-sided prism, 
 and a double six-sided pyramid. Glistening, 
 metallic. Harder than gypsum. Perfectly 
 sectile. Rather easily frangible. Sp. gr. 
 5.5 to 5.8. Its constituents arc, copper 78.05, 
 iron 2.25, sulphur 18.5, silica 0.75. — KIh- 
 proth . 
 
 $ 2. Foliated. Its constituents are, cop- 
 
ORE 
 
 ORE 
 
 -per 79.5, sulphur 19, iron 0.75, quartz 1. 
 — Ullmann . It occurs in primitive rocks. 
 It is found also in transition rocks, at Fass- 
 ney-burn in East Lothian ; in Ayrshire ; at 
 ♦Middleton Tyas in Yorkshire ; in Cornwall, 
 •&c. 
 
 16. Variegated copper. Colour, between 
 copper-red and pinchbeck-brown. Massive, 
 in plates, and crystallized in six-sided prisms. 
 Glistening, metallic. Soft. Easily frangi- 
 ble. Specific gravity, 5. It is fusible, but 
 not so easily as copper- glance, into a globule, 
 which acts powerfully on the magnetic nee- 
 -dle. Its constituents are, copper 69.5, sul- 
 phur 19, iron 7.5, oxygen 4. — Klaproth . 
 lit occurs in gneiss, mica- slate, &c. It is 
 found in Cornwall. 
 
 VII. — Gold Ores. 
 
 1. Ilexahedral , or native gold. 
 
 a. Gold-yellow native gold. Colour, per- 
 fect gold-yellow. Disseminated, in grains, 
 and crystallized ; in the octohedron, perfect 
 mr truncated ; in the cubo- octohedron ; in 
 •the cube, perfect or truncated ; in the dou- 
 Ible eight-sided pyramid ; in the tetrahedron, 
 ;and rhomboidal dodecahedron. Splendent. 
 
 Fracture, fine hackly. Soft. Dfficultly frang- 
 ible. Malleable. Sp. gr. from 17 to 19, 
 :and so low as 12. Fusible into a glo- 
 bule. It is gold with a very minute por- 
 tion of silver and copper. It occurs in 
 many very different rocks ; and in almost 
 • every country. See an extensive enumera- 
 ■ tion of localities, in Jameson’s Mineralogy. 
 
 b. Brass-yelloiv native gold , occurs capil- 
 lary ; in octohedrons, and in six-sided tables. 
 Specific gravity, 12.713. Its constituents 
 are, gold 96.9, silver 2, iron 1.1. It is 
 found in the gold mines of Hungary, in Si- 
 beria, &c. 
 
 c. Greyish-yellow native gold. Colour 
 brass-yellow verging on steel-grey. In small 
 Hattish grains. Never crystallized. It is 
 said to contain platina. It is rather denser 
 than the last. It occurs along with platina 
 and magnetic iron-ore in South America. 
 
 d. Argentiferous gold , or electrum. Co- 
 lour, pale brass-yellow. In small plates, 
 and imperfect cubes. Its constituents are, 
 64 gold, 36 silver. It occurs along with 
 massive heavy spar in Siberia. Klaproth 
 says, it is acted on neither by nitric nor ni- 
 tro-muriatic acid. See Tellurium Ores. 
 
 VIII. — Iridium Ore. Colour, pale steel- 
 grey. In very small irregular flat grains. 
 Lustre shining and metallic. Fracture foli- 
 ated. Brittle. Harder than platina. Sp. 
 gr. 1 9.5. By fusion with nitre, it acquires 
 a dull black colour, but recovers its original 
 colour and lustre, by heating with charcoal. 
 It consists of iridium, with a portion of os- 
 mium. It occurs in alluvial soil in South 
 America, along with platina.— -Wollaston. 
 
 IX I ro.n Ores. 
 
 I. Native , or octohedral iron. 
 
 а. Terrestrial native iron. Colour, steel- 
 grey. Massive, in plates and leaves- Glis- 
 tening, and metallic. Fracture hackly. 
 Opaque. Malleable. Hard. Magnetic* 
 Its constituents are, iron 92.5, lead 6, cop- 
 per 1.5* — Klaproth. It is found with brown 
 iron-stone and quartz in a vein, in the moun- 
 tain of Oulle, in the vicinity of Grenoble, &c. 
 
 б. Meteoric native iro?i . Colour, pale 
 steel-grey, inclining to silver- white. Gene- 
 rally covered with a thin brownish crust of 
 oxide of Iron. It occurs ramose, imperfect 
 globular, and disseminated in meteoric- 
 stones. Surface, smooth and glistening. 
 Internally, it is intermediate between glim- 
 mering and glistening, and the lustre is me- 
 tallic. Fracture hackly. Fragments blunt- 
 edged. Yields a splendent streak. Inter- 
 mediate between soft and semi- hard. Mal- 
 leable. Flexible, but not elastic. Very dif- 
 ficultly frangible. Sp. gr. 7,575. Its con- 
 stituents are, 
 
 A gram. 
 
 Arctic. 
 
 Mexico. 
 
 Siberian. 
 
 Iron, 96.5 
 
 97 
 
 96.75 
 
 90.54 
 
 Nickel, 5.5 
 
 5 
 
 3.25 
 
 9.46 
 
 100.0 
 
 100 
 
 100.00 
 
 100.00 
 
 Klapr. 
 
 JBrande. 
 
 Klapr. 
 
 Children. 
 
 The American native iron contains 0.10 of 
 nickel; the Siberian 0.17; and the Sene- 
 gambian 0.05 and 0.06. — Howard. It ap- 
 pears to be formed in the atmosphere, by 
 some process hitherto unknown to us. See 
 Meteorolite, and Jameson s Mineralogy, iii. 
 p. 101. 
 
 II. Iron-ore. 
 
 a. Octohedral iron-ore , of which there are 
 three kinds. 
 
 § 1. Common magnetic iron-ore . Colour, 
 iron-black. Massive, in granular concre- 
 tions, and crystallized ; in the octohedron, 
 truncated, bevelled and cuneiform ; rhom- 
 boidal dodecahedron ; rectangular four-sid- 
 ed prism ; cube ; tetrahedron ; equi-angular 
 six-sided table ; and twin crystal. Splen- 
 dent, and metallic. Cleavage fourfold. 
 Fracture uneven. Streak black. Harder 
 than apatite. Brittle. Specific gravity, 4.3 
 to 5. 2. Highly magnetic, with polarity. Be- 
 fore the blow-pipe it becomes brown, and 
 does not melt ; it gives glass of borax a dark 
 green colour. Its constituents are, peroxide 
 of iron 69, protoxide of iron 31. — Berzelius . 
 It occurs in beds of great magnitude, in pri- 
 mitive rocks, at Unst ; at St Just in Corn- 
 wall ; at Arendal in Norway, &c. It affords 
 excellent bar-iron. 
 
 § 2. Granular magnetic iron-ore , or non- 
 sand. Colour very dark iron-black. In 
 small grains and octohedral crystals. Glim- 
 mering. Fracture conchoidal. Brittle. 
 Streak black. Sp. gr. 4.6 to 4.8. Mag- 
 netical with polarity* Its constituents are 
 
ORE 
 
 *QRE 
 
 oxide of iron 85.5, oxide of titanium 14, 
 oxide of manganese 0.5 — Klaproth. It oc- 
 curs imbedded in basalt, Sec. It is found in 
 I iteshire, in the Isle of Skye, in the river 
 Dee in Aberdeenshire, &c. 
 
 § 3. Earthy magnetic iron-ore. Colour 
 bluish-black. In blunt-edged rolled pieces. 
 Dull. Fracture, line grained uneven. O- 
 paque. Soft. Streak black, shining. Soils. 
 Sectile. It emits a faint clayey smell when 
 breathed on. Sp. gr. 2.2. It occurs in the 
 iron mines of Arendal in Norway. 
 
 b. Ilhomboidal iron-ore ; of which there 
 are three sub-species. 
 
 § 1. Specular iron-ore , iron-glance, or fer 
 oligiste of ‘the French. Of this there are two 
 kinds, the common and micaceous. Com- 
 mon specular iron-ore . Colour dark steel- 
 grey. Massive, disseminated, and crystal- 
 lized. Prim, form ; a rhomboid, or double 
 three-sided pyramid, in which the angles are 
 87° 9' and 92° 51'. The secondary figures 
 are, the primitive form variously bevelled, 
 truncated and acuminated ; the flat rhom- 
 boid ; equiangular six-sided table ; low equi- 
 angular six-sided prism ; and very acute six- 
 sided pyramid. Lustre, splendent metallic. 
 Cleavage threefold. Fracture imperfect 
 conchoidal. Streak cherry-red. Hardness, 
 between felspar and quartz. Father diffi- 
 cultly frangible. Sp. gr. 5.2. Magnetic in 
 a slight degree. Its constituents are, reddish- 
 brown oxide of iron 94.38, phosphate of 
 lime 2.75, magnesia 0. 1 6, mineral oil ? 1.25. 
 — - Hisingcr . It occurs in beds in primitive 
 
 mountains. It is found at Cumberhead in 
 Lanarkshire ; at Norberg in Westmannland, 
 in Norway, Sec. It affords an excellent mal- 
 leable iron. 
 
 ^Micaceous specular iron-ore. Colour iron- 
 black. Massive, disseminated and in small 
 thin six-sided tables, intersecting one another 
 so as to form cells. Splendent, metallic. 
 Cleavage, single curved-foliated. Translu- 
 cent in thin plates. Streak cherry-red. As 
 hard as the above. Most easily frangible. 
 Sp. gr. 5.07. It slightly affects the magnet. 
 It is peroxide of iron. It occurs in beds in 
 mica- slate. It is found at Dunkeld, and 
 Benmore in Perthshire ; in several parts of 
 England and Norway, Sec. The iron it af- 
 fords is sometimes cold short, but is vvell 
 fitted for cast ware. It is characterized by 
 its high degree of lustre, openness of its 
 cleavage, and easy frangibility. It affords 
 from 70 to 80 per cent of iron. 
 
 § 2. lied iron-ore ; of which there are 
 four kinds, the scaly, ochry, compact, and 
 fibrous. 
 
 Scaly red iron-ore , or red iron froth. Co- 
 lour dark steel-grey, to brownish-red. fri- 
 able, and consists of semi-metallic shining 
 scaly parts, which arc sometimes translucent 
 and soil strongly. Its constituents are, iron 
 
 66, oxygen 28.5, silica 4.25, -alumina 1.25. 
 — Henry. But Bucholz found it to be a 
 
 pure red oxide of iron, mixed with a little 
 quartz sand. It occurs in veins in primitive 
 rocks. It is found at Ulverstone in Lan- 
 cashire ; in Norway, &c. 
 
 Ochry red iron-ore , or red ochre. Colour 
 brownish-red. Friable. Dusty dull par- 
 ticles. Soils. Streak, blood- red. Easily 
 frangible. Sp. gr. 2.947. It occurs in 
 veins, with the preceding ore. It melts 
 more easily than any of the other ores of this 
 metal, and affords excellent malleable iron. 
 
 Compact red iron- ore. Colour between 
 dark steel-grey and blood- red. Massive, 
 and in supposititious crystals ; which are an 
 acute double six-sided pyramid from calcare- 
 ous spar; and a cube from fluor spar and 
 iron pyrites. Lustre metallic. Fracture 
 even. Streak pale blood-red. Easily frangi- 
 ble. Sp. gr. 4.232. When pure it does 
 not affect the magnet. Its constituents are 
 oxide of iron 70.5? oxygen 29.5? — Bu- 
 cholz. It occurs in beds and veins in gneiss, 
 Sec. It affords good bar and cast-iron. 
 
 Fibrous red iron-ore , or red hematite, 
 Colour between browmish-red and dark steel- 
 grey. Massive, imitative, and in supposi- 
 titious double six-sided pyramids from cal- 
 careous spar. Glistening, semi-metallic. 
 Opaque. Streak blood-red. Brittle. Sp. 
 gr. 4.74. Its constituents are, 90 oxide of 
 iron, silica 2, lime 1, water 3. — Daubuis- 
 son. It occurs with the compact. It 
 affords excellent malleable and cast-iron. 
 Its pow^ler is used for polishing tin, silver, 
 and gold vessels; and for colouring iron 
 brown. 
 
 
 § 3. Bed clay iron-ore , or stone ; of which 
 the varieties are, the ochry, the columnar, 
 the lenticular, and jaspery. The first is used 
 for red crayons ; and is called red- chalk. It 
 
 occurs in Ilessia, Sec. The second consists 
 of 50 oxide of iron, 13 water, 32 silica, and 
 7 alumina. — Brocchi. It is rare, and is 
 
 called a pseudo-volcanic product. It affords 
 excellent iron. It consists of oxide ot iron 
 64, alumina 23, silica 7.5, water 5. The 
 jaspery is found in Austria. 
 
 c. Prismatic iron-ore , or brown iron-stone ; 
 Of this we have four sub-species. 
 
 § 1. Ochry brown iron-ore. '\ellowish- 
 brown ; massive ; dull ; fracture, earthy ; 
 soils; soft; sectile. Its constituents are, 
 peroxide of iron 83, water 12, silica 5. It 
 occurs with the following. 
 
 § 2. Compact. Colour passes to clove- 
 brown. Massive, and in supposititious crys- 
 tals from pyrites. Dull. Brittle. Sp. gr. 
 3 to 3.7. It contains 84 peroxide of iron, 
 1 1 water, and 2 silica. It affords about 50 
 per cent of good bar iron. 
 
 §3. Fibrous. Clove-brown. Imitative; 
 and in supposititious crystals. Splendent ex- 
 
ORE 
 
 OR£ 
 
 ternally. Glimmering internally. Opaque. 
 Harder than apatite. Brittle. Sp. gr. 3.9. 
 Streak pale yellowish- brown. Its consti- 
 tuents are, 80.25 oxide of iron, 15 water, 
 3.75 silica. — Vauquelin. 
 
 The preceding sub-species occur most fre- 
 quently in transition and secondary moun- 
 tains. They are found in veins in sand-stone, 
 along with heavy spar, at Cumberhead in 
 Lanarkshire, &c . They melt easily, and af- 
 ford from 40 to CO per cent of good bar, 
 but indifferent cast-iron. Good steel may 
 be made from it. 
 
 § 4. Brown clciy iron-ore ; of which there 
 are five kinds, the common, the pisiform, 
 the reniform, the granular, and umber. 
 
 The first occurs massive ; has a flat con- 
 ehoidal fracture; a brown streak; and is 
 soft. It contains 69 oxide of iron, 3 man- 
 ganese, 13 water, 10 silica, and 3 alumina. 
 The second has a yellowish-brown colour. 
 It occurs in small solid spherical grains, com- 
 posed of concentric concretions. Sp. gr. 
 5.142. It consists of 48 oxide of iron, 31 
 alumina, 15 silica, and 6 water. — Vauquelin. 
 It is found in hollows in shell limestone, at 
 Galston in Ayrshire, &c. It yields from 
 40 to 50 per cent of iron ; and in Dalmatia 
 it is used as small shot. The third has a 
 yellowish-brown colour. Massive, and imi- 
 tative; in concentric lamellar concretions, 
 which often include a loose nodule. Glim- 
 mering. Sectile. Its constituents are, per- 
 oxide of iron 76, water 14, silica 5, oxide of 
 manganese 2. It occurs in iron-shot clay in 
 secondary rocks. It is found in East and 
 Mid Lothian, in Colebrookdale, Sec. It 
 yields an excellent iron. The fourth, or 
 granular, occurs massive and in grains. 
 Fracture thick slaty. Streak yellowish- 
 brown. Soft. Brittle. Sp. gr. 3. It oc- 
 curs in beds between the red limestone of the 
 salt formation, and the lias limestone. It is 
 found in Bavaria, France, Sec. It affords 
 about 40 per cent of good iron. Fifth , 
 Umber. Colour clove-brown. Massive. 
 Dull. Fracture, flat conchoidal. Soft. 
 Sectile. Soils strongly. Feels meagre. 
 Adheres strongly to the tongue, and readily 
 falls to pieces in water. Sp. gr. 2.06. It 
 consists of oxide of iron 48, oxide of man- 
 ganese 20, silica 13, alumina 5, water 14. — 
 Klaproth. It occurs in beds in the Island of 
 Cyprus. It is used as a pigment. 
 
 Bog iron-ore is arranged as a variety of 
 the above. There are three kinds of it. 
 
 § 1 . Meadow ore, or friable bog iron-ore. 
 Colour pale yellowish-browm. Friable. 
 Dull. Fracture, earthy. Soils. It feels 
 meagre, but fine. 
 
 § 2. Swamp ore, or indurated bog iron-ore. 
 Colour dark yellowish -brown. Corroded 
 and vesicular. Dull. Earthy. Very soft. 
 Sectile. Sp. gr. 2.944. 
 
 § 3. Meadow ore, or conchoidal bog iron- 
 
 ore. Blackish-brown. Massive, and tube- 
 rose. Glistening. Fracture small con- 
 choidal. Streak yellowish-grey. Soft. Sp. 
 gr. 2.6. Its constituents are, oxide of iron 
 66, oxide of manganese 1 .5, phosphoric acid 
 8, water 23. — Klaproth. By Vauquelin ’s 
 
 experiments it seems to contain also chrome, 
 magnesia, silica, alumina, and lime ; zinc 
 and lead are likewise occasionally present. 
 
 It belongs to a recent formation ; Werner’s 
 ingenious theory of which is given by Pro- 
 fessor Jameson, vol. xiii. p. 247. It is found 
 in the Highlands of Scotland, in Saxony, 
 &c. The second is most easily reduced, and 
 affords the best iron. 
 
 Bitchy iron-ore , may also be placed here. 
 Its colour is blackish-brown. Massive. 
 Glistening. Fracture flat conchoidal. Trans- 
 lucent on the edges. Liard. Streak yel- 
 lowish-grey. Brittle. Sp. gr. 3.562. Its 
 constituents are, phosphoric acid 27, man- 
 ganese 42, oxide of iron 81. — Vauquelin. 
 It occurs near Limoges in LTance. 
 
 Iron sinter. Colour brown. Massive 
 and imitative. Glistening. Fracture flat 
 conchoidal. Translucent. Soft. Brittle. 
 Sp. gr. 2.4. Its constituents are, water 25, 
 oxide of iron 67, sulphuric acid 8. — Klaproth. 
 It occurs in the galleries of old mines in 
 Saxony and Silesia. 
 
 III. Iron pyrites . 
 
 § 1. Hexahedral, or common iron pyrites. 
 Colour perfect bronze-yellow. Massive, 
 imitative, and crystallized ; in cubes, vari- 
 ously bevelled. Lustre from specular- splen- 
 dent, to glistening, and metallic. Cleavage, 
 hexahedral. Fracture uneven. Harder 
 than felspar, but softer than quartz. Brittle. 
 When rubbed it emits a strong sulphureous 
 smell. Sp. gr. 4.7 to 5. It burns with a 
 bluish flame, and sulphureous odour before 
 the blow-pipe. It afterwards changes into 
 a brownish-coloured globule, which is at- 
 tractive by the magnet. Its constituents 
 are, sulphur 52.5, iron 47.5. — Hatchett. 
 Silver and gold are occasionally present It 
 occurs in beds in various mountains. It is 
 worked for sulphur or copperas. 
 
 § 2. Prismatic iron pyrites. 
 
 a. Radiated pyrites. Colour pale bronze- 
 
 yellow. Most usually imitative, or crystal- 
 lized. Primitive form, is an oblique four- 
 sided prism, in which the obtuse angle is 
 106° 36'. Secondary forms, are the above 
 variously bevelled ; and the wedge-shaped 
 double four-sided pyramid. Harder than 
 felspar. Sp. gr. 4.7 to 5.0. Its constitu- 
 ents are, sulphur 53.6, iron 46.4 Hatchett. 
 
 It is much rarer than the preceding. It is 
 found in Cornwall, Isle of Sheppy, See. 
 
 b. Hepatic or liver jn/rites. Colour pale 
 brass-yellow. Massive and imitative. Glim- 
 mering and metallic. Fracture even. Sp. 
 gr. 4.834. It occurs in veins in primitive 
 rocks. It is found in Derbyshire, &c. 
 
ORE 
 
 ORE 
 
 c. Cellular pyrites. Colour bronze-yellow. 
 
 Cellular. Surface of the cells drusy. Frac- 
 ture Hat conch oidal. It occurs in veins at 
 
 J ohanngeorgenstadt in Saxony. 
 
 d. Spear pyrites. Colour between bronze- 
 yellow and steel-grey. Crystallized in twin 
 or triple crystals. Fracture uneven. It oc- 
 curs in veins in primitive rocks, associated 
 with brown coal. 
 
 d. Cockscomb pyrites. Colour as above. 
 Crystallized in double four-sided pyramids. 
 Glistening and metallic. It occurs in Der- 
 byshire. 
 
 § 3. Ilhotnboidal iron pyrites , or magnetic 
 pyrites. 
 
 a. Foliated magnetic. Colour between 
 bronze-yellow and copper- red. Massive, 
 and sometimes crystallized, in a regular six- 
 eided prism, truncated ; and in a six-sided 
 pyramid. Splendent and metallic. Sp. gr. 
 4.4 to 4.6. It occurs In Saxony. 
 
 b. Compact magnetic. Same colour. Mas- 
 sive. It affects the magnetic needle. Its 
 constituents are, sulphur 36. 5, iron 65.5. — 
 Hatchett. It is found in Galloway and Caer- 
 narvonshire. 
 
 I V. Native salts of iron. 
 
 a. The Prismatic chrome-ore. Colour be- 
 tween steel-grey and iron-black. Massive, 
 and in oblique four-sided prisms, acuminated 
 with four planes. Lustre imperfect metallic. 
 Fracture small grained uneven. Opaque. 
 Hardness, between apatite and felspar. 
 Streak dark-brown. Sp. gr. 4.4 to 4.5. 
 Some varieties are magnetic, others not. It 
 is infusible before the blow-pipe. With 
 borax, it forms a beautiful green-coloured 
 mass. The constituents of the French are, 
 oxide of iron 34.7, oxide of chrome 43, alu- 
 mina 20.3, silica 2. — Haiiy. The Siberian 
 contains 34 oxide of iron, 53 oxide of 
 chrome, 1 1 alumina, 1 silica, and 1 man- 
 ganese. — Laugier. It occurs in primitive 
 serpentine. It is found in the islands of 
 Unst and Fetlar, in Scotland ; and also at 
 Portsoy in Banffshire. In considerable quan- 
 tity in serpentine on the Bare-hills near Bal- 
 timore. 
 
 b. Sparry iron , or carbonate of iron. Co- 
 lour pale yellowish- grey. Massive, dis- 
 seminated, and crystallized. The primitive 
 form is a rhomboid of 107°. The follow- 
 ing are some of the secondary forms: — the 
 primitive rhomboid, perfect or truncated ; 
 a still flatter rhomboid ; the spherical lenti- 
 cular form ; the saddle-shaped lens ; the 
 equiangular six-sided prism. Glistening 
 and pearly. Cleavage threefold. Fracture 
 foliated. Translucent on the edges, or 
 opaque. Streak white or yellowish-brown. 
 Harder than calcareous spar. Sp. gr. 3.6 
 to 5.9. It blackens, and becomes magnetic 
 before the blow-pipe. It effervesces with 
 muriatic acid. Its constituents are, oxide ot 
 
 iron 57.5, carbonic acid 36, oxide of man- 
 ganese o.5, lime 1.25.— Klaproth. It oc- 
 curs in veins in granite, and in limestone. 
 
 In small quantities in Britain. In great 
 quantity at Schmalkalden in Ilessia. It 
 aifords an iron well suited for making steel. 
 
 c. lthomboidal vitriol, or green vitriol. 
 Colour emerald-green. Primitive form of 
 the crystals is a rhomboid, with edges of 81° |I 
 2S' and 98° 37'; and plane angles of 100° 
 
 10' and 79° 50'. Vitreous or pearly lustre. 
 Cleavage threefold. Fracture flat conchoi- 
 dal. Semi-transparent. Refracts double. I 
 As hard as gypsum. Sp. gr. 1.9 to 2.0. | 
 
 Taste sweetish, styptic, and metallic. Be- i 
 fore the blow-pipe, on charcoal, it becomes 
 magnetic. Its constituents are, oxide of iron 
 25.7, sulphuric acid 28.9, water 45.4. — 
 Berzelius. It results from the decomposi- 
 tion of iron pyrites. 
 
 d. Arseniate of iron. See Cube Ore. 
 
 e. Blue iron , or phosphate of iron. 
 
 Prismatic blue iron. 
 
 § 1. Foliated blue iron. Colour dark in- 
 digo-blue. Primitive form an oblique four- i| 
 sided prism. The secondary forms are, a 
 broad rectangular four-sided prism, trun- 
 cated; and an eight-sided prism. Shining. 
 Cleavage straight, single. Translucent. As 
 hard as gypsum. Streak, paler blue. Sec- 
 tile, and easily frangible. Flexible in thin 
 pieces. Sp. gr. 2.8 to 5.0. Its constituents 
 are, oxide of iron 41.25, phosphoric acid 
 19.25, water 31.25, iron-shot silica 1.25, 
 alumina 5. — Fourcroy and Laugier. It 
 occurs in St Agnes’s in Cornwall. 
 
 § 2. Fibrous blue iron. Colour indigo- 
 blue. Massive, and in delicate fibrous con- 
 cretions. Glimmering and silky. Opaque. 
 Soft It occurs in syenite at Stavcrn in 
 Norway. 
 
 § 3. Earthy blue iron. Colour as above. 
 Friable, and in dusty particles. Soils slight- 
 ly. Rather light. Before the blow-pipe it 
 loses its blue colour, becomes reddish-brown, 
 and lastly, melts into a black coloured slag, 
 attractible by the magnet. Its constituents 
 are, oxide of iron 47, phosphoric acid 32, 
 water 20. — Klaproth. It occurs in nests in 
 clay-beds. In several of the Shetland islands, 
 and in river mud at Toxteth, near Liverpool. 
 
 4. Tungstate of iron. See Ores of Tun g- 
 sten. 
 
 5. Blue ironstone. Colour indigo-blue. 
 Massive, and with impressions of crystals of 
 brown iron ore. Glimmering, or dull. 
 Fracture coarse grained uneven. Opaque. 
 Semi-hard. Rather brittle. Sp. gr. 3.2. — 
 Klaproth. It loses its colour by heat ; and 
 with borax forms a clear bead. Its consti- 
 tuents are, oxide of iron 40.5, silica 50, lime 
 1.5, natron 6, water 3. It occurs on the 
 banks of the Orange River in Southern 
 Africa. 
 
ORE 
 
 ORE 
 
 X. — Lead- Ores. 
 
 1 . Galena or lead-glance . 
 
 Hexahedral galena. 
 
 § 1. Common. Colour fresh lead-grey. 
 Massive, imitative, and crystallized in cubes, 
 octohedrons, rectangular four-sided prisms, 
 broad unequiangular six-sided prisms, six- 
 sided tables, and three-sided tables. Specu- 
 lar splendent, to glimmering. Lustre me- 
 tallic. Cleavage hexahedral. Fragments 
 cubical. Harder than gypsum. Sectile and 
 frangible. Sp. gr. 7. to 7.6. Before the 
 blow-pipe it flies in pieces, then melts, emit- 
 ting a sulphureous odour, while a globule of 
 lead remains. Its constituents are, lead 8o , 
 sulphur 16.41, silver 0.08. — Westrumb. It 
 
 occurs in beds, See. in various mountain 
 rocks. At Leadhills in Lanarkshire, &c. 
 Nearly all the lead of commerce is obtained 
 from galena. The ore is roasted and then 
 reduced with turf. 
 
 § 2. Compact galena. Colour somewhat 
 darker than the preceding. Massive, shining, 
 metallic. Fracture flat conchoidal. Streak 
 more brilliant. It consists of sulphuret of 
 lead, sulphuret of antimony, and a small 
 portion of silver. It is found at Leadhills 
 in Lanarkshire, in Derbyshire, &c. 
 
 § 3. Friable galena. Colour dark fresh 
 lead-grey. Massive and in thick flakes. 
 Sectile. It is found only around Freyberg. 
 
 Blue lead. Colour between very dark 
 indigo-blue and dark lead-grey. Massive, 
 and crystallized in regular six-sided prisms. 
 Feebly glimmering. Soft. Sectile. Sp. 
 gr. 5.461. It is conjectured to be sulphuret 
 of lead, intermixed with phosphate of lead. 
 It occurs in veins. It has been found in 
 Saxony and France. 
 
 Cobaltic galena. Colour fresh lead-grey. 
 Minutely disseminated in exceedingly small 
 crystals, aggregated in a moss-like form. 
 Shining and metallic. Scaly foliated. 
 Opaque. Soft. Soils feebly. It commu- 
 nicates a smalt-blue colour to glass of bo- 
 rax. It occurs near Clausthal in the Iiartz. 
 
 2. Lead spar. 
 
 § 1 . Tri-prismatic lead spar, or sulphate 
 oj * lead. Colours yellowish and greyish- 
 white. Massive and crystallized. In the 
 primitive form the vertical prism is 120°. 
 The principal crystallizations are, an oblique 
 four-sided prism, variously bevelled or trun- 
 cated; and a broad rectangular four-sided 
 pyramid. Lustre shining, adamantine. Frac- 
 ture conchoidal. Translucent. As hard 
 as calcareous spar. Streak white. Brittle. 
 Sp. gr. 6.3. It decrepitates before the blow- 
 pipe, then melts, and is soon reduced to the 
 metallic state. Its constituents are, oxide of 
 lead 70.5, sulphuric acid 25.75, water 2.25. 
 — Klaproth. It occurs in veins along with 
 galena at Wanlockhead in Dumfries-shire, 
 Leadhills, Pary’s mine, and Penzance. 
 
 § 2. Pyramidal lead spar , or yellow lead 
 
 spar. Colour wax-yellow. Massive, cel- 
 lular, and crystallized. Its primitive form 
 is a pyramid, in which the angles are 99° 
 40' and 131° 45'. Its secondary forms are, 
 the pyramid variously truncated, on the 
 angles and summits, and a regular eight- 
 sided table. Lustre resinous. Cleavage 
 fourfold. Fracture uneven. Translucent. 
 As hard as calcareous spar. Brittle. Sp. 
 gr. 6.5 to 6.8. — Mohs. (5.706, Hatchett). 
 Its constituents are, oxide of lead 58.4, mo- 
 lybdic acid 38, oxide of iron 2.08, silica 
 0.28. — Hatchett. It occurs at Bleiberg in 
 
 Carinthia. 
 
 § 3. Prismatic lead spar, or red lead spar. 
 Colour hyacinth-red. Crystallized, in long 
 slightly oblique four-sided prisms, variously 
 bevelled, acuminated or truncated. Splen- 
 dent, adamantine. Fracture uneven. Trans- 
 lucent. Streak between lemon-yellow and 
 orange-yellow. Harder than gypsum. Sec- 
 tile. Easily frangible. Sp. gr. 6.0 to 6.1. 
 Before the blow-pipe it crackles and melts in- 
 to a grey slag. It does not effervesce with 
 acids. Its constituents are, oxide of lead 
 63.96, chromic acid 36.4. — Vauquelin . It 
 occurs in veins in gneiss in the gold mines 
 of Beresofsk in Siberia. 
 
 § 4. Rhomboidal lead spar. 
 
 a. Green lead spar. Colour, grass-green. 
 
 Imitative or crystallized. The primitive form 
 is a di-rhomboid, or a flat equiangular double 
 six-sided pyramid. The secondary forms 
 are, the equiangular six-sided prism, various- 
 ly truncated and acuminated. Splendent. 
 Fracture uneven. Translucent. Sometimes 
 as hard as flucr. Brittle. Sp. gr. 6.9 to 
 7.2. It dissolves in acids without efferves- 
 cence. Its constituents are, oxide of lead 
 80, phosphoric acid 18, muriatic acid 1.62, 
 oxide of iron, a trace. — Klaproth. It occurs 
 
 along with galena at Leadhills, and Wan- 
 lockhead ; at Alston in Cumberland, &c. 
 
 b. Brown lead spar. Colour, clove-brown. 
 Massive and crystallized; in an equiangular 
 six-sided prism ; and an acute double three- 
 sided pyramid. Glistening, resinous. Feebly 
 translucent. Streak greyish-white. Brittle. 
 Sp. gr. 6.91 . It melts before the blow r -pipe, 
 and during cooling, shoots into acicular 
 crystals. It dissolves without effervescence 
 in nitric acid. Its constituents are, oxide of 
 lead 78.58, phosphoric acid 19.73, muriatic 
 acid 1.65. It occurs in veins that traverse 
 gneiss. It is found at Miess in Bohemia. 
 
 § 5. Hi-prismatic lead spar. 
 
 a. White lead spar. Carbonate of lead. 
 Colour, white. Massive and crystallized ; 
 in a very oblique four-sided prism ; a un- 
 equiangular six-sided prism; acute double 
 six-sided pyramid ; oblique double four- 
 sided pyramid ; long acicular crystals ; and 
 in twin and triple crystals. Lustre, adaman- 
 tine. Fracture small conchoidal. Trans- 
 lucent. Befracts double in a inch decree 
 
 _ o o 
 
OIIE 
 
 OIIE 
 
 Harder than calcareous spar. Brittle. Sp. 
 gr. 6.2 to 6.6. It dissolves with efferves- 
 cence in muriatic and nitric acids. It yields 
 a metallic globule with the blow-pipe. Its 
 constituents are, oxide of lead 82, carbonic 
 acid 16, water 2. — Klaproth. It occurs in 
 
 veins at Leadhills in Lanarkshire. 
 
 b. Black lead spar. Colour, greyish -black. 
 Massive, cellular and seldom crystallized, in 
 very small six-sided prisms. Splendent, me- 
 tallo-adamantine. Fracture uneven. Streak 
 whitish-grey. Its constituents are, oxide of 
 lead 79, carbonic acid 18, carbon 2. — Lam- 
 padius. It occurs in the upper part of veins, 
 at Leadhills, &c. 
 
 c. Earthy lead spar. Colour, yellowish- 
 grey. Massive. Glimmering. Opaque. 
 Streak, brown. Very soft. Sp. gr. 5.5 79. 
 Its constituents are, oxide of lead 66, car- 
 bonic acid 12, water 2.25, silica 10.5, alu- 
 mina 4.75, iron and oxide of manganese 
 2.25. — John. It is found at Wanlockhead. 
 
 Corneous lead ore , or muriate of lead. 
 Colour, greyish- white. Crystallized, in an 
 oblique four-sided prism, variously trun- 
 cated, bevelled, and acuminated. Splendent 
 and adamantine. Cleavage threefold. Frac- 
 ture conchoidal. Transparent. Soft. Sec- 
 tile and easily frangible. Sp. gr. 6.065. It 
 melts into an orange- coloured globule. Its 
 constituents are, oxide of lead 85.5, muriatic 
 acid 8.5, carbonic acid 6. — Klaproth. It is 
 found in Cromford-level near Matlock in 
 Derbyshire. 
 
 Arseniate of lead. 
 
 § 1. Ren form. Colour, reddish-brown. 
 Shining. Fracture conchoidal. Opaque. 
 Soft and brittle. Sp. gr. 3.933. It gives 
 out arsenical vapours with the blow-pipe. It 
 colours glass of borax lemon-yellow. Its 
 constituents are, oxide of lead 35, arsenic 
 acid 25, water 10, oxide of iron 14, silver 
 1.15, silica 7, alumina 2. It is found in 
 Siberia. 
 
 § 2. Filamentous. Colours, green or 
 yellow. In acicular six-sided prisms, or in 
 silky fibres. Slightly flexible and easily 
 frangible. Sp. gr. 5.0 to 6.4. Its consti- 
 tuents are, oxide of lead 69.76, arsenic acid 
 26.4, muriatic acid 1.58. — Gregor. It oc- 
 curs in Cornwall. 
 
 § 3. Earthy arseniate. Colour, yellow. 
 In crusts. Friable. It occurs at St Prix in 
 France. 
 
 Native minium. Colour scarlet-red. Mas- 
 sive, amorphous, and pulverulent. It is 
 found in Grassington-moor, Craven. Mr 
 Smithson thinks this mineral is produced by 
 the decay of galena or lead-glance. 
 
 XI. — Manganese Ores. 
 
 1. Prismatic manganese ore. 
 
 § 1. Grey manganese ore. 
 
 a. Fibrous grey manganese ore. Colour, 
 dark steel-grey. Massive, imitative, and in 
 very delicate acicular crystals, and in thin 
 
 and long rectangular four-sided tables. 
 Shining and splendent Soils strongly. Soft. 
 Brittle. It occurs in the Westerwald. 
 
 b. Jladtatcd. Colour, dark steel- grey. 
 Massive, imitative, and crystallized. The 
 primitive form is an oblique four-sided 
 prism, in which the largest angle is about 
 100°. Secondary forms are, the primitive 
 bevelled, or acuminated, or spicular crystals. 
 Cleavage prismatic. Streak dull-black. 
 Soils. Soft. Brittle. Sp. gr. 4.4 to 4,8. 
 Shining and metallic. Its constituents arc, 
 black oxide of manganese 90.5, oxygen 2.25, 
 water 7. — Klaproth. It occurs in the vici- 
 nity of Aberdeen, in Cornwall, Devonshire, 
 &c. 
 
 Ci Foliated. Colour between steel-grer 
 and iron-black. Massive and crystallized in 
 short oblique four-sided prisms. Shining, 
 metallic. Cleavage prismatic. Fracture 
 uneven. Other characters, as above. Sp. gr. 
 3.742. It is found in Devonshire. 
 
 d. Compact. Fracture even, or flat con- 
 choidal. Sp. gr. 4. to 4.4. Other charac- 
 ters as preceding. Its constituents are, yel- 
 low oxide of manganese ? 50, oxygen 33, 
 barytes 1 4, silica 1 to 6. Analysis doubtful. 
 It occurs at Upton Pyne in Devonshire. 
 
 e. Earthy. Friable. It consists of semi- 
 metallic feebly glimmering fine scaly parti- 
 cles, which soil strongly. It occurs in the 
 mine Johannis in the Erzegebirgc. It tinges 
 borax purple ; and effervesces with muriatic 
 acid, giving out chlorine. These five kinds 
 occur in granite, gneiss, &c. either in veins 
 or in large cotemporaneous masses. 
 
 § 2. Black manganese ore. 
 
 a. Compact. Colour, between bluish- 
 black and steel-grey. Massive, imitative, 
 and in curved lamellar concretions. Glim- 
 mering and imperfect metallic lustre. Frac- 
 ture conchoidal. Streak shining, with colour 
 unchanged. Semi-hard. Brittle. Sp. gr. 
 4.75. 
 
 b. Fibrous. Massive, imitative, and in 
 delicate scopiform concretions. Fragments 
 cuneiform and splintery. Its other charac- 
 ters as above. It yields a violet-blue glass 
 with borax. It occurs in veins in the Erze- 
 gebirge. It yields a good iron ; but acts 
 very powerfully on the sides of the furnace. 
 It is called black hematite. 
 
 c. Foliated. Colour brownish-black. Crys- 
 tallized sometimes in acute double four- 
 sided pyramids. Shining. Cleavage single, 
 and curved foliated. Streak dark reddish- 
 brown. Brittle. It is supposed to consist 
 of iron and manganese. 
 
 § 3. Scaly brown manganese ore. Colour 
 between steel-grey and clove-brown. In 
 crusts. Massive and imitative. Friable. 
 Composed of shining scaly particles. Soils 
 strongly. Feels greasy. It gives to glass 
 of borax, an olive- green colour. It occurs 
 in drusy cavities in brown hematite. It is 
 
ORE 
 
 found near Sandlodge in Mainland, one of 
 | the Shetlands. 
 
 4. Manganese-blende . 
 
 Prismatic. Colour, iron-black. Massive, 
 iin distinct concretions, and sometimes crys- 
 jtallized. Primitive form, an oblique four- 
 ssided prism, which becomes variously modi- 
 ffied by truncations on the lateral edges. 
 Xustre splendent, and semi-metallic. Streak 
 greenish. Harder than calcareous spar. 
 Easily frangible. Before the blow-pipe it 
 .gives out sulphur, and tinges borax violet- 
 :blue. Its constituents are, oxide of manga- 
 mese 82. sulphur 11 . 5 , carbonic acid 5.—— 
 .Klaproth. Oxide of manganese 85, sulphur 
 1 5 . — Vauquelin. It is found in Cornwall. 
 
 5. Phosphate of manganese . Colour, 
 
 ] brownish -black. Massive and disseminated. 
 Glistening. Fracture flat conchoidal. Semi- 
 transparent, in splinters. Scratches glass. 
 
 Streak yellowish- grey. Brittle. Sp. gr. 3.5 
 <to 3.7. It is fusible into a black enamel. 
 Its constituents are, oxide of manganese 42, 
 ♦oxide of iron 31, phosphoric acid 27. It 
 ♦occurs in a coarse granular granite at Li- 
 moges in France. 
 
 6 . Rhomboidal red manganese . 
 
 a. Foliated. Colour, bright rose-red. 
 
 Massive, imitative, and crystallized in rbom- 
 'boids. Shining, pearly. Cleavage rhom- 
 Iboidal. Translucent on the edges. Hard- 
 iness between fluor and calcareous spar. 
 Brittle. Sp. gr. 3.3 to 5.6 . Before the 
 
 Iblow-pipe it first becomes dark brown, and 
 then melts into a reddish-brown bead. Its 
 constituents are, oxide of manganese 52.6, 
 isilica 39.6, oxide of iron 4.6, lime 1.5, vola- 
 tile ingredients 2.75. — Berzelius. It occurs 
 iin beds of specular iron ore in gneiss hills in 
 Sweden and Siberia. The specimens of the 
 latter are cut into ornamental stones. 
 
 b. Fibrous. Colours, rose-red and flesh- 
 red. Massive and in distinct prismatic fi- 
 Ibrous concretions. Glistening and pearly. 
 Fragments splintery. Feebly translucent. 
 It occurs in Transylvania and Hungary. 
 
 c. Compact. Colour, pale rose-red. Mas* 
 :sive or reniform. Glimmering. Sp. gr. 3.3 
 to 3.9. Its constituents are, oxide of man- 
 ganese 61, silica 50, oxide of iron 5 , alumi- 
 *a 2 . — Lampad. It occurs at Kapnik in 
 Transylvania. 
 
 Pitchy i^on ore may be regarded as a phos- 
 phate of manganese. 
 
 XII. — Mercury Ores. 
 
 1 . Native mercury. 
 
 a. Fluid mercury. See Mercury. It 
 ♦occurs principally in rocks of the coal forma- 
 tion, associated with cinnabar, corneous mer- 
 cury, Sec. Small veins of it are rarely met 
 with in primitive rocks, accompanied with 
 native silver, Sc c. It is found at Idria, in 
 the Friaul ; Niderslana in Upper Hungary ; 
 in the Palatinate ; Deux-Fonts, &c. 
 
 2 
 
 ORE 
 
 b. Dodecahedral mercury , or native amal- 
 gam. 
 
 § 1. Fluid , or semi-fluid amalgam. Co- 
 lour tin-white. In roundish portions ; and 
 crystallized, in a rhomboidal dodecahedron, 
 rarely perfect. Splendent, When cut, it 
 emits a creaking sound. As hard as talc, 
 Sp. gr. 10.5. Its constituents are, mercury/ 
 74, silver 25. It is found at Deux-Ponts. 
 
 §2. Solid amalgam. Colour, silver- white. 
 Massive and disseminated. Fracture flat 
 conchoidal. As hard as gypsum. Brittle. 
 Creaks strongly when cut. Sp. gr. 10.5. 
 The mercury flies off before the blow-pipe. 
 Its constituents are, mercury 74, silver 25. 
 —FLeyer. Mercury 64, silver 36. — Klap- 
 roth. It is found in Hungary, the Deux- 
 Ponts, Sec. 
 
 2. Cinnabar , or prismato-rhomboidal ruby- 
 blende. 
 
 a. Dark red cinnabar. Colour cochineal- 
 red. Massive, disseminated, imitative, and 
 crystallized. Primitive form a rhomboid. 
 Secondary forms; a regular six-sided prism, 
 an acute rhomboid and a six-sided ta- 
 ble. Splendent, adamantine. Translucent. 
 Streak scarlet-red, shining. Harder than 
 gypsum. Sectile and easily frangible. Sp. 
 gr. 6.7 to 8.2. It melts, and is volatilized 
 with a blue flame, and sulphureous odour. 
 Its constituents are, mercury 84.5, sulphur 
 
 14.75. — Klaproth , 
 
 b. Bright red cinnabar. Colour bright 
 scarlet-red. Massive, and in delicate fibrous 
 concretions. Glimmering and pearly. Frac- 
 ture earthy. Opaque. Streak, shining. 
 Soils. Friable. It occurs in rocks of clay- 
 slate, talc-slate, and chlorite-slate ; in veins 
 at Horzowitz in Bohemia ; at Idria, Sec. 
 
 c. Hepatic cinnabar. 
 
 § 1. Compact. Colour between cochineal- 
 red and dark lead- grey. Massive. Glim- 
 mering and semi-metallic. Streak shining. 
 Opaque. Soft. Sectile. Sp. gr. 7.2. Its 
 constituents are, mercury 81.8, sulphur 
 
 13.75, carbon 2.3, silica 0.65, alumina 
 0.55, oxide of iron 0.2, copper 0.02, water 
 0.73. 
 
 § 2. Slaty mercurial hepatic ore. Colour 
 as above, but sometimes approaching to 
 black. Massive, and in roundish concre- 
 tions. Lustre shining, semi-metallic. Frac- 
 ture curved slaty. Most easily frangible. 
 Streak cochineal-red, inclining to brown. 
 Rather lighter than the compact. It occurs 
 in considerable masses in slate-clay and bi- 
 tuminous shale. It is most abundant in 
 Idria. 
 
 3. Corneous mercury , or horn quicksilver. 
 
 Pyramidal corneous mercury. Colour 
 
 ash-grey. Vesicular, with interior crystalli- 
 zations ; which are, a rectangular four-sided 
 prism, variously acuminated, and a double 
 four- sided pyramid. Crystals very minute. 
 
ORE 
 
 Shining, adamantine. Cleavago single. Faint- 
 ly translucent. Soft. Seetile and easily fran- 
 gible. It is totally volatilized before the 
 blow-pipe, with a garlic smell. It is soluble 
 in water, and the solution mixed with lime- 
 water, gives an orange-coloured precipitate. 
 Its constituents are, oxide of mercury 76, 
 muriatic acid 16.4, sulphuric acid 7.6. — 
 Klaproth. It occurs in Bohemia, &c. 
 
 XIII. — Molybdena Ores. 
 
 Rhomboidal molybdena. Colour fresh 
 
 lead-grey. Massive, in plates, and some- 
 times crystallized. Primitive form is a rhom- 
 boid. Secondary figures are, a regular six- 
 sided table, and a very short six-sided prism, 
 flatly acuminated on both extremities. Splen- 
 dent, metallic. Cleavage single. Opaque. 
 Streak on paper, bluish-grey ; on porcelain, 
 greenish-grey. Soils slightly. Harder than 
 talc. Easily frangible. Splits easily. In 
 thin leaves flexible, but not elastic. Seetile, 
 approaching to malleable. Feels greasy. Sp. 
 gr. 4.4 to 4.6. It emits a sulphureous 
 odour before the blow- pipe. It is soluble, 
 
 with violent effervescence, in carbonate of 
 soda. Its constituents are, molybdena 60, 
 sulphur 40. — Bucliolz. It occurs dissemin- 
 ated in granite, gneiss, &c. It is found in 
 Glenelg in Inverness-shire, at Peterhead, at 
 Corybuy at the head of Loch Creran, in 
 Cornwall, &c. 
 
 Molybdena ochre. Colour sulphur-yellow. 
 Disseminated and incrusting molybdena. 
 Friable ; dull. In Corybuy and Norway. 
 
 For molybdate of lead , see Lead Ores. 
 
 XIV. — Nickel Ores. 
 
 1. Native nickel. Colour brass- yellow'. 
 In delicate capillary crystals. Shining and 
 metallic. Crystals rigid. Brittle. It con- 
 sists, according to Klaproth, of nickel, with 
 a small quantity of cobalt and arsenic. It 
 occurs in veins in gneiss, in Saxony. 
 
 2. Nickel pyrites , or copper-nickel. 
 
 Prismatic nickel pyrites. Colour copper- 
 
 red, becoming black. Massive, disseminated, 
 imitative, and crystallized, in oblique four- 
 sided prisms. Shining, metallic. Harder 
 than apatite. Rather difficultly frangible. 
 Sp. gr. 7.5 to 7.7. It emits an arsenical 
 vapour before the blow-pipe, and then fuses 
 into a dark scoria, mixed with metallic grains. 
 It yields a dark green solution with nitro- 
 muriatic acid. Its constituents are nickel 
 and arsenic, with accidental admixtures of 
 cobalt, iron, and sulphur. It generally oc- 
 curs in primitive rocks. It is found in small 
 quantities at Leadhills and Wanlockhead, 
 and in the coal field of Linlithgowshire. 
 
 Black nickel. Colour dark greyish- black. 
 Massive, and in crusts. Dull. Earthy frac- 
 ture. Soft. Streak shining. Soils slightly. 
 It forms an apple-green coloured solution 
 with nitric acid, which lets fall a white pre- 
 cipitate with arsenic acid. It occurs in veins 
 
 ORE 
 
 that traverse bituminous marle-slato at Rie- 
 gelsdorf. 
 
 Nickel ochre. Colour apple- green. In ar* 
 efflorescence. Dull. fracture splintery „ 
 Soft. Feels meagre. It gives to glass o! 
 borax a hyacinth-red colour. It occurs at 
 Leadhills, at Alva in Stirlingshire, and in 
 Saxony. It consists of oxide of nickel 67. 
 oxide of iron 23.2, water 1.5, loss S.S. — 
 Lampadius. 
 
 XV. — Palladium Ore. 
 
 Native palladium. Colour pale steel-grey, 
 passing into silver-white. It occurs in smalS 
 grains. Lustre metallic. Fracture diverg- 
 ing fibrous. Opaque. Sp. gr. 11.8 to 12.148. 
 It is infusible, but on the addition of sul 
 phur, it melts. It forms a deep red solution 
 with nitric acid. It consists of palladium s 
 alloyed with a minute portion of platina and 
 iridium. It is found in grains along with 
 grains of native platina, in the alluvial gold 
 districts in Brazil. — Wollaston. 
 
 XVI. — Platina Ore. Colour very light 
 steel-grey. In flat small grains. Shining and 
 metallic. Nearly as hard as iron. Malleable. 
 Sp. gr. 17.7. It is found in the grey silver 
 ore of Guadalcanal in Spain, in Clioco, in 
 New Granada, and in the province of Bar- 
 bacoas. It is peculiar to an alluvial tract 
 of 600 leagues, where it is associated with 
 grains of native gold, zircon, spinel, quartz, 
 and magnetic ironstone. It is not true, that 
 this metal occurs near Carthagena, or Santa 
 Fe, or in the islands of Porto Rico and 
 Barbadoes, or in Peru, although these dif- 
 ferent localities are mentioned by authors. 
 The grey copper ore of Guadalcanal in Spain 
 contains from 1 to 10 per cent of platina. 
 
 XVII. — Silver Ores. 
 
 1 . Hexahedral, or native silver. 
 
 a. Common native silver. Colour pure 
 
 silver-white. Disseminated, in plates or 
 membranes, imitative, and crystallized ; in a 
 cube ; octohedron ; tetrahedron ; rhomboidal 
 dodecahedron ; leucite form ; and six-sided 
 table. Crystals microscopic. Shining and 
 metallic. Fracture line hackly. Streak 
 
 splendent. Harder than gold, tin, lead ; 
 but softer than iron, platina, and copper. 
 Perfectly malleable. Flexible, and difficultly 
 frangible. Sp. gr. 10 to 10.4. Its consti- 
 tuents are, metallic silver 99, metallic anti- 
 mony 1, with a trace of copper and arsenic. 
 — John. It occurs principally in veins in 
 
 primitive mountains. In granite in the 
 Erzegebirgc. In gneiss and mica-slate in 
 Saxony, Bohemia, and Norway. In clay- 
 slate in Ireland. In clay-porphyrv at Alva, 
 in the Ochil Hills, Stirlingshire. For a co- 
 pious list of localities, see Jameson s Miner- 
 alogy. 
 
 b. Auriferous native silver. Colour be- 
 tween brass- vellow’ and silver-white. Dis- 
 
 9 
 
 seminated, in membranes, and crystallized in 
 
ORE 
 
 ORE 
 
 cubes. Its sp. gr. is greater than that of the 
 preceding. Its constituents are, silver 72, 
 gold 28. — Fordyce. It occurs in veins in 
 primitive rocks at Kongsberg in Norway. 
 
 2. Silver-glance , or vitreous silver. 
 
 § 1. Hcxahedral. 
 
 a. Compact. Colour dark blackisb lead- 
 
 grey. Massive, imitative, and crystallized; in 
 a cube, octohedron,rbomboidal dodecahedron, 
 and double eight-sided pyramid. Glisten- 
 ing, metallic. Cleavage rhomboidal. Harder 
 than gypsum. Completely malleable. Flex- 
 ible, but not elastic. Difficultly frangible. 
 Sp. gr. 5.7 to 6.1. Before the blow-pipe it 
 loses its sulphur, and a bead of pure silver 
 remains. Its constituents are, silver 85, Sul- 
 phur 15. — Klaproth. It is one of the most 
 
 frequent of the ores of silver. It occurs in 
 mica- slate, clay- slate, greywacke, and sel- 
 domer in granite. It is found in Cornwall 
 
 b. Earthy. Colour bluish-black. In 
 crusts. Friable or solid. Dull. Feebly 
 translucent. Streak shining, metallic. Soils 
 a little. Easily frangible. Sectile. It is 
 easily fused by the blow- pipe. It is a sul- 
 phuret of silver. 
 
 § 2. Rhomboidal silver- glance. Colour 
 between iron-black and blackish lead-grey. 
 Crystallized. Primitive form, a rhomboid. 
 Secondary figures; an equiangular six-sided 
 prism, an equiangular six-sided table, and a 
 double six-sided pyramid. The tabular crys- 
 tals often intersect each other, forming cells. 
 Highly splendent, and metallic. Soft. Sec- 
 tile. Easily frangible. Sp. gr. 5.7 to 6.1. 
 It melts with difficulty. Its constituents 
 are, silver 66.5, " sulphur 1 2, antimony 10, 
 iron 5, copper and arsenic 0.5, earthy sub- 
 stances 1.0. It occurs in gneiss, Sec. It is 
 found in the district of Freyberg. 
 
 2. White silver. Colour very light lead- 
 grey. Massive, disseminated, and always 
 associated with lead-glance. Glistening and 
 metallic. Fracture even. Soft. Sectile. 
 Easily frangible. Sp. gr. 5.5 to 5.6. Be- 
 fore the blow-pipe it melts and partly eva- 
 porates, leaving a bead of impure silver, sur- 
 rounded by a yellow powder. Its consti- 
 tuents are, lead 41, silver 9.25, antimony 
 
 21.5, iron 1.75, sulphur 22, alumina 1, sili- 
 ca 0.75. — Klaproth. It occurs in gneiss. 
 It is found near Freyberg. 
 
 5. Grey silver or carbonate of silver. Co- 
 lour ash-grey. Massive and disseminated. 
 Glistening. Fracture uneven. Soft. Streak 
 more shining. Brittle. Heavy. Easily 
 reduced before the blow-pipe. Its consti- 
 tuents are, silver 72.5, carbonic acid 12, 
 oxide of antimony, and a trace of copper 
 
 15.5. — Selb. It occurs in veins that traverse 
 granite in the Black Forest. 
 
 4. Antimonial silver, or Dodecaiixdral 
 Antimony. See Appendix. 
 
 4. Arsenical silver. Colour on the fresh 
 surface, tin- white, which tarnishes greyish- 
 
 black. Massive, and reniform. Fracture 
 small-grained uneven. Flarder than anti- 
 monial silver. Streak shining. Sectile, and 
 easily frangible. Sp. gr. 9.44. Before the 
 blow-pipe the antimony and arsenic are 
 volatilized with a garlic smell; while a glo- 
 bule of silver remains, which is more or less 
 pure. Its constituents are, arsenic 35, iron 
 44.25, silver 12.75, antimony 4. It gene- 
 rally occurs along with native arsenic. It is 
 found in the Hartz. 
 
 6. Bismuthic silver. Colour pale lead- 
 grey. Disseminated, and rarely crystallized 
 in capillary crystals. Glistening and metal- 
 lic. Soft. Sectile. Easily frangible. Its 
 constituents are, bismuth 27, lead 33, silver 
 15, iron 4.3, copper 0.9, sulphur 16.3.-— 
 Klajnoth. It has been found only in the 
 Friedrich- Christian Mine in the Black Fo- 
 rest, in veins, in gneiss. 
 
 7. Ruby-blende. 
 
 § 1. Rhomboidal ruby-blende. 
 
 a. Dark red silver. Colour between co- 
 chineal-red, and dark lead- grey. Massive, 
 in membranes, and crystallized. Prim, 
 form, a rhomboid of 109° 28'. Secondary 
 forms, an equiangular six-sided prism, various- 
 ly truncated and accumulated ; and an equi- 
 angular double six-sided pyramid. Splen- 
 dent and adamantine. Cleavage rhomboi- 
 dal. Semi-transparent. Streak cochineal- 
 red. Harder than gypsum. Sectile. Easi- 
 ly frangible. Sp. gr. 5. 2 to 5.7. Before 
 the blow-pipe, it first decrepitates, then melts 
 with a slight effervescence, leaving a globule 
 of silver. Its constituents are, silver 60, an- 
 timony 20.3, sulphur 14.7, oxygen 5. — 
 Klaproth. It occurs in veins in gneiss, &c. 
 It is found in the silver mines of Kongs- 
 berg, and in those of the Hartz. 
 
 § 2. Light red silver. Colour cochineal- 
 red. Streak aurora-red, passing into cochi- 
 neal-red. Sp. gr. 5.5 to 5.9. In other re- 
 spects, as preceding. Its constituents are, 
 silver 54.27, antimony 16.3, sulphur 17.75, 
 oxygen 11. 85. — Vauquelin. It occurs at 
 
 Andreasberg in the Hartz. 
 
 XVIII. — Tantalum Ores. 
 
 1. Prismatic tantalum ore . Columbitc 
 
 Hatchett. Colours greyish and brownish- 
 black. Massive, disseminated, and crystal- 
 lized in oblique four-sided prisms. Semi- 
 metallic adamantine lustre. Fracture coarse- 
 grained uneven. Opaque. As hard as fel- 
 spar. Difficultly frangible. Sp. gr. 6.0 to 
 6.3. It does not fuse with glass of borax. 
 Its constituents are, 
 
 Wollaston. 
 
 oxide of tantalum, 85 80 
 
 oxide of iron, 10 15 
 
 oxide of manganese, 4 5 
 
 Finland. N. American 
 or Columbitc. 
 
 It occurs in a coarse red granite in Fin- 
 land, and in Massachussct’s Bay, in North 
 America. 
 
ORE 
 
 ORE 
 
 2. Yttrotantalite. Colours iron-black and 
 yellowish-brown. Imbedded in angular 
 pieces, and crystallized in oblique four-sided 
 and in six-sided prisms. Resinous, metallic 
 lustre. Fracture conchoidal. Opaque. 
 Scratches glass. Streak grey-coloured. Easi- 
 ly frangible. Sp. gr. 5.4 to 5.68. It decre- 
 pitates, but does not fuse with the blow-pipe. 
 Its constituents are, oxide of tantalum 57, 
 yttria 20.25, lime 6.25, oxide of iron 8.5, 
 oxide of uranium 05, tungstic acid 8.25. It 
 occurs along with gadolinite in a bed of 
 flesh-red felspar in gneiss at Ytterby in Swe- 
 den. 
 
 XIX. — Tellurium Ores. 
 
 1. Hexahedral or native tellurium. Co- 
 lour tin- white. Massive, disseminated, and 
 in rectangular four-sided prisms, acuminated 
 with four planes. Shining, metallic. Cleav- 
 age hexahedral. As hard as gypsum. Ra- 
 ther brittle. Sp. gr. 6.1 to 6.2. It melts as 
 easily as lead, emits a thick white smoke, 
 and burns with a light-green colour, and a 
 pungent acrid odour, like that of horse-rad- 
 ish. Its constituents are, tellurium 92.55, 
 iron 7.2, gold 0.25. It occurs in veins in 
 greywacke, at Facebay, in Transylvania, and 
 in Norway. 
 
 2. Prismatic black tellurium. Colour be- 
 tween blackish lead-grey and iron-black. 
 Massive, in flakes, and crystallized. Primi- 
 tive figure, an oblique four-sided prism. 
 Secondary forms are, an oblique four-sided 
 table, a six-sided table, an eight-sided table, 
 and an acute double four-sided pyramid. 
 Splendent and metallic. Fragments tabular. 
 Harder than talc. Sectile. Soils slightly. 
 The thin leaves and tables are flexible. Sp. 
 gr. 7.0 to 7.2. It melts very easily before 
 the blow-pipe. Its constituents are telluri- 
 um 32.2, lead 54, gold 9, sulphur 3, copper 
 1.3, silver 0.5. — Klaproth. It is worked for 
 the gold it contains. It is found at Naygag, 
 in Transylvania. 
 
 3. Prismatic gold glance. 
 
 § 1. Graphic gold glance , or tellurium. 
 Colour steel-grey. Massive, in leaves and 
 crystallized. Primitive form, an oblique 
 four- sided prism. Splendent, metallic. 
 Cleavage prismatic. Fracture fine-grained 
 uneven. As hard as gypsum. Brittle. 
 Soils slightly. Sp. gr. 5.7 to 5.8. Before 
 the blow-pipe it burns with a green flame, 
 and is volatilized. Its constituents are, tel- 
 lurium 60, gold 30, silver 10. It occurs in 
 porphyry in Transylvania. 
 
 § 2. Yellow gold glance , or yellow telluri- 
 um. Colour silver-white, inclining to brass- 
 yellow. Disseminated and crystallized, in 
 four-sided acicular prisms, which are rare. 
 Splendent, metallic. Cleavage prismatic. 
 Fracture small-grained uneven. Sp. gr. 5.7 
 to 5.8. Its constituents are, tellurium 44.75, 
 gold 26.75, lead 19.5, silver 8.5, sulphur 
 
 0. 5. — Klaproth. It occurs in veins in por- 
 phyry at Naygag, in Transylvania. 
 
 XX. — Tin Ores. 
 
 1. Pyramidal tin ore. 
 
 § 1. Common tin ore , or tinstone. Colour 
 blackish-brown. Massive, disseminated, but 
 most frequently crystallized. Primitive form, 
 a double four-sided pyramid, in which the 
 angles are 133° 36' and 67° 42'. Secondary 
 figures are, the primitive truncated ; a rec- 
 tangular four-sided prism, variously truncat- 
 ed or acuminated, and twin crystals. Splen- 
 dent, and adamantine. Fracture uneven. 
 From semi-transparent to opaque. Streak 
 greyish- white. As hard as felspar, some- 
 times as quartz. Easily frangible. Sp. gr. 
 6.5 to 7.0. Before the blow- pipe it decre- 
 pitates, and becomes paler, and is reduced to 
 the metallic state. Its constituents are, tin 
 77.5, iron 0.25, oxygen 21.5, 6ilica 0.75. 
 It occurs in granite, gneiss, &c. ; and in an 
 alluvial form, in what are in Cornwall called 
 stream ivorks. There are only three tin dis- 
 tricts in Europe ; Cornwall, which is the 
 most considerable ; the Erzegebirge ; and 
 Monte lley, in Gallicia. 
 
 § 2. Cornish tin ore , or wood-tin. Colour 
 hair-brow'n. In rolled and imitative shapes. 
 Glistening. Opaque. Softer than common 
 tinstone. Streak grey, inclining to brown. 
 Brittle. Sp. gr. 6.4. Its constituents are, 
 oxide of tin 91, oxide cf iron 9. — Vauquelin. 
 It occurs along with stream-tin. 
 
 2. Tin pyrites. Colour between steel-grey 
 
 and brass-yellow. Massive and disseminat- 
 ed. Glistening and metallic. Fracture 
 uneven. Yields easily to the knife. Brit- 
 tle. Sp. gr. 4.35. Not magnetic. Before 
 the blow-pipe it exhales a sulphureous va- 
 pour, and melts easily. Its constituents arc, 
 tin 34, copper 36, iron 5, sulphur 25, earthy 
 matter 2. — Klaproth. It has been found 
 
 only in Cornwall, in granite, at St Michael’s 
 Mount. 
 
 XXI. — Titanium Ores. 
 
 1. Prismatic titanium ore , or sphene. 
 
 a. Common sphene. Colours, reddish, yel- 
 lowish, and reddish-brown. It occurs in 
 granular concretions, and crystallized in the 
 following forms : A low j very oblique four- 
 
 sided prism, bevelled or truncated ; a broad 
 six-sided prism ; a rectangular four-sided 
 prism ; an oblique double four-sided pyra- 
 mid. Shining and adamantine. Fracture 
 imperfect conchoidal. Streak greyish or 
 yellowish- white. Harder than apatite. Brit- 
 tle. Sp. gr. 3.4 to 3.6. Before the blow- 
 pipe it is fusible w r ith difficulty into a brown- 
 ish-black enamel. Its constituents are, ox- 
 ide of titanium 46, silica 36, lime 16, w ater 
 
 1. — Klaproth. It occurs in the syenite ot 
 Criffle, and other hills in Galloway; in the 
 syenite of Inveraray ; on the south side of 
 Loch- Ness; the granite of Aberdeen; th* 
 
ORE 
 
 ORE 
 
 syenite of Culloden, in Inverness-shire; in 
 the floetz rocks of Mid- Lothian ; and at 
 Arendal, in Norway. 
 
 b. Foliated sphene. Colour yellow. Mas- 
 sive, in straight lamellar concretions, and 
 crystallized as the preceding. Lustre splen- 
 dent. Cleavage double. Fracture imper- 
 fect conchoidal. Translucent. It occurs 
 at La Portia, in Piedmont, St Gothard, and 
 Arendal. 
 
 2. Prismato -pyramidal titanium ore. 
 
 a . Futile . Colour reddish-brown. Mas- 
 sive and crystallized. Primitive figure, a 
 pyramid of 1 17° 2' and 84° 48'. Secondary 
 forms are, a long rectangular four-sided 
 prism ; four- sided prism ; six-sided prism ; and 
 aeicular crystals. The crystals are occasion- 
 ally curved. Splendent or glistening. Streak 
 brown. Translucent. Harder than apatite. 
 Brittle. Sp. gr. 4.255. — Lowry. It is pure 
 oxide of titanium, with a little oxide of iron. 
 It occurs in the granite of Cairngorm, the 
 limestone of Rannoch, and in the rocks of 
 Ben Gloe, where it was discovered by Dr 
 M‘Culloch. 
 
 b. Iserine. Colour iron-black. In obtuse 
 angular grains, and in rolled pieces. Splen- 
 dent and metallic. Fracture conchoidal. 
 Harder than felspar. Opaque. Brittle. 
 Sp. gr. 4.6. Before the blow-pipe it melts 
 into a blackish-brown coloured glass, which 
 is slightly attracted by the magnet. Its con- 
 stituents are, oxide of titanium 28, oxide of 
 iron 72. — Klaproth; or oxide of titanium 
 48, oxide of iron 48, oxide of uranium 2. — 
 Thomson. It occurs imbedded in gneiss, 
 and disseminated in granite sand, along with 
 iron sand, in the bed of the river Don, in 
 Aberdeenshire. 
 
 c. Menachanite. Colour greyish- black. 
 In small flattish angular grains. Glimmering 
 or semi- metallic. Opaque. Brittle. Sp. 
 gr. 4.427. It is attractible by the magnet. 
 Its constituents are, oxide of iron 51, oxide of 
 titanium 45.25, oxide of manganese 0.25, 
 silica 3.5. — Klaproth. It is found in the valley 
 of Manaccan in Cornwall. 
 
 3. Pyramidal titanium ore , or octohedrite. 
 Colour passes from indigo-blue to brown. 
 Crystallized. Its primitive form is a pyra- 
 mid of 97° 38' and 137° 10'. The follow- 
 ing are secondary figures ; the pyramid trun- 
 cated on the extremities, and double four- 
 sided pyramid, variously acuminated. Lustre 
 splendent, adamantine. Cleavage fourfold. 
 Translucent. Harder than apatite. Brittle. 
 Sp. gr. 3.8 to 3.9. It is oxide of titanium. 
 It is found in Dauphiny. 
 
 XXII. — Tungsten Ores. 
 
 1. Pijramidal tungsten, or scheelium. 
 Colour white. Massive, and sometimes 
 crystallized. The primitive form iu a rather 
 acute double four-sided pyramid. Secondary 
 forms are ; the primitive figure bevelled on 
 the angles ; a very acute double four-sided 
 
 pyramid ; a flat double four- sided pyramid ; 
 a square lenticular figure ; and a flat double 
 four-sided pyramid. Shining. Fracture 
 uneven. Cleavage ninefold. Translucent. 
 Harder than fluor spar. Brittle. Sp. gr. 
 6. to 6.1. Its constituents are, oxide of 
 tungsten 65, lime 31, silica 4. — Scheele ; 
 oxide of tungsten 75.25, lime 18.70, silica 
 1.56, oxide of iron 1.25, oxide of manganese 
 
 0.75. — Klaproth. It occurs along with tin- 
 stone and wolfram, in Cornwall ; in Sweden ; 
 Saxony, &c. 
 
 2. Wolfram. 
 
 Prismatic wolfram. Colour black. Mas- 
 sive and crystallized. Primitive form is an 
 oblique four-sided prism of 120°. Second- 
 ary forms are ; the oblique four-sided prism, 
 bevelled, truncated or acuminated ; and a 
 twin crystal. Shining. Fracture uneven. 
 Opaque. Streak dark reddish-brown. Har- 
 der than apatite. Brittle. Sp. gr. 7.1 to 7.4. 
 Its constituents are, tungstic acid 67, oxide of 
 manganese 6.25, oxide of iron 18.10, silica 
 1 .5. — Vauquelin. It occurs in gneiss in the 
 island of Ilona of the Hebrides, and in 
 Cornwall. 
 
 XXIII. — Uranium Ores. 
 
 1. Ur an ochre. 
 
 a. Friable. Colour lemon-yellow. It 
 occurs as a coating on pitch ore. It is com- 
 posed of dull, weakly cohering particles. It 
 feels meagre. 
 
 b. Indurated. Colour straw-yellow\ 
 Massive and superimposed. Glimmering. 
 Opaque. Soft. Sp. gr. 3.15. The yel- 
 low varieties are pure oxide of uranium. 
 The brownish and reddish contain a little 
 iron. It is found in Bohemia and Saxony. 
 
 2. Indivisible uranium , or pitch ore. Co- 
 lour greenish-black. Massive, reniform and 
 in distinct concretions. Shining. Hardness 
 between apatite and felspar. Opaque. 
 Brittle. Sp. gr. 6.4 to 6.6. Its constituents 
 are, oxide of uranium 86.5, black oxide of 
 iron 2.5, galena 6.0, silica 5 . — Klaproth. It 
 occurs in primitive rocks. It is found in 
 Cornwall. 
 
 3. Uranite , or uran mica. 
 
 Pyramidal uran mica. Colour grass- 
 green. In flakes and crystallized. Primi- 
 tive form, a pyramid in which the angles are 
 95° 13' and 144° 56'. The secondary forms 
 are, a rectangular four-sided table or short 
 prism, and a four-sided table variously be- 
 velled and truncated. Shining. Cleavage 
 fourfold and rectangular. Transparent and 
 translucent. Scratches gypsum, but not 
 calcareous spar. Streak green. Sectile. Not 
 flexible. Easily frangible. Sp.gr. 3.1 to 
 3.2. It decrepitates violently before the 
 blow r -pipe on charcoal ; loses about 33 per 
 cent by ignition, and acquires a brass-yellow 
 colour. Its constituents are, oxide of uranium, 
 with a trace of oxide of lead 74.4, oxide of 
 copper 8.2, water 1 5.4.— Gregor. It occur* 
 
ORE 
 
 ORE 
 
 in veins in primitive rocks. It is found in 
 Cornwall and Saxony. 
 
 XXIV. — Wodanium Ores. 
 
 Woodan pyrites. Colour dark tin- white. 
 In vesicular massive portions. Lustre shin- 
 ing and metallic. Fracture uneven. Opaque. 
 Harder than Hu or, but softer than apatite. 
 Brittle. Sp. gr. 5.192. It contains 20 per 
 cent of wodanium, combined with sulphur, 
 arsenic, iron, and nickel. It is said to occur 
 at Topschau in Hungary. 
 
 XXV. — Zinc Ores. 
 
 1 . Red zinc , or red oxide of zinc. Colour 
 blood-red. Massive, disseminated, On the 
 fresh fracture, shining. Cleavage single. 
 Fracture conchoidal. Translucent on the 
 edges. Easily scratched by the knife. Brittle. 
 Streak brownish-yellow. Sp.gr. 6.2 2. It 
 is soluble in the mineral acids. Its consti- 
 tuents are, zinc 76, oxygen 16, oxides of 
 manganese and iron 8. — Bruce. It has been 
 found in New Jersey, North America. 
 
 2. Zinc blende. 
 
 Dodecahedral zinc blende. 
 
 a. Yellow. Wax-yellow, and several other 
 colours, inclining to green. Massive, dis- 
 seminated, and crystallized in octohedrons, 
 rhomboidal dodecahedrons, and twin crystals. 
 Splendent and adamantine. Cleavage dode- 
 cahedral, or sixfold. Translucent. Refracts 
 single. Streak yellowish-grey. Harder than 
 calcareous spar. Brittle. Sp. gr. 4. to 4.2. 
 It becomes phosphorescent by friction. Its 
 constituents are, zinc 64, sulphur 20, iron 5, 
 fluoric acid 4, silica 1, water 6. — Bergmann. 
 It occurs in veins, associated with galena. 
 It is found at Clifton mine, near Tyndrum, 
 in Perthshire, also in Flintshire. Fine spe- 
 cimens are found in Bohemia. 
 
 b. Brown zinc blende. 
 
 § 1. Foliated. Colour reddish-brown. 
 Massive, disseminated, and crystallized, in a 
 rhomboidal dodecahedron, an octohedron, a 
 tetrahedron, and acicular crystals. Lustre 
 between pearly and adamantine. Cleavage 
 sixfold or tessular. Translucent. Streak 
 yellowish-brown. Sp. gr. 4.048. Its con- 
 stituents are, zinc 58.8, sulphur 2 5.5, iron 
 8.4, silica 7.0. — Dr Thomson. It occurs in 
 veins and beds, in primitive and transition 
 rocks. It is found in the Clifton lead mine, 
 near Tyndrum ; at Cumberhead in Lanark- 
 shire ; at Leadhills ; and in all the lead 
 mines in England and Wales. 
 
 § 2. Fibrous. Colour dark reddish-brown. 
 Massive, reniform, and in radiated concre- 
 tions. Glistening, inclining to pearly. O- 
 paque. Its constituents are, zinc 62, iron 3, 
 lead 5, arsenic 1, sulphur 21, alumina 2, wa- 
 ter 4. It occurs in Iluel- Unity copper mine 
 in Cornwall. 
 
 c. Black zinc blende. Colour between 
 greyish and velvet- black. Massive, dissemi- 
 nated, and crystallized in the same figures 
 as brown blende. Shining, adamantine. 
 
 Opaque. I he blood- red variety is translu- 
 cent on the edges and angles. Streak dark 
 yellowish-brown. Sp. gr. 4. 1665. Its con- 
 stituents are, oxide of zinc 55, iron 12, arse- 
 nic 5, sulphur 26, water 4. The black 
 blende from Naygag, besides zinc, iron, and 
 manganese, contains a portion of auriferous 
 silver. It occurs in veins in gneiss, in Swe- 
 den, Saxony, Sec. 
 
 Of the Analysis and Reduction of 
 Ores. 
 
 By consulting the table of metallic precl- 
 pitants, and studying the peculiar habitudes 
 of 1;he individual metals and earths, the reader 
 may acquire a knowledge of the methods of 
 separating them from one another, and de- 
 termining the proportion of each. The li- 
 mits of the present work permit me to offer 
 merely a short account of the best modes of 
 analyzing a few of the principal ores on the 
 6mall scale, and of reducing them on the 
 large. 
 
 1. Antimony. 
 
 1. Native antimony was skilfully examin- 
 ed by Klaproth, the father of accurate ana- 
 lysis, as follows: On 100 grains of the pul- 
 verized mineral, he poured strong nitric acid, 
 which attacked it with vehemence, convert- 
 ing it into an oxide ; which being precipi- 
 table by water, he diluted the solution with 
 this liquid, and then filtered. The clear 
 liquid was treated with muriatic acid, which 
 threw down the silver present, in the state of 
 muriate, equivalent to 1 grain of the precious 
 metal. Prussiate of potash then indicated ^ 
 of a grain of iron. The oxide of antimony 
 was now dissolved in muriatic acid, the solu- 
 tion diluted with water, and a piece of zinc 
 being introduced, precipitated 98 grains of 
 metallic antimony. Hence the 100 grains 
 of native antimony from Andreasberg, con- 
 sisted of metallic antimony, 98 
 
 silver, - 1 
 
 iron, - 0.25 
 
 99.25 
 
 Dr Thomson has committed a curious 
 mistake in describing this analysis. He says, 
 “ When the acid emitted no longer any 
 nitrous gas, the mixture was diluted with 
 water, and thrown upon a filter. The solu- 
 tion was then treated until nitrate of silver. 
 The precipitate yielded by reduction, 1 grain 
 of silver.” — System, 5th edition, iii. p. 608. 
 How 1 grain of silver was obtained by treat- 
 ing the solution with nitrate of silver, it is 
 not for me to divine. 
 
 2. Fibrous red antimonial ore. Klaproth 
 digested 100 grains with muriatic acid, mix- 
 ed with a few drops of nitrous, in a long- 
 necked matrass. There was a grey residuum 
 of 1 1- grains of sulphur. “ The antimony 
 contained in the solution was precipitated in 
 the state of a white oxide, by diluting it with 
 
ORE 
 
 ORE 
 
 water, and the small portion of the metal 
 still remaining in that fluid, was afterwards 
 entirely thrown down by means of potash. 
 The oxide thus procured was redissolved in 
 muriatic acid, the solution diluted with six 
 times its quantity of water, and once more 
 combined with such a proportion of the same 
 solvent, as was necessary in order to redis- 
 solve entirely that portion of the oxide which 
 the affused water had precipitated. After 
 the dilute solution had, in this manner, again 
 been rendered clear, its ingredient antimony 
 was reproduced as metallic antimony, by im- 
 mersing polished iron in the liquor. It 
 weighed, when collected, edulcorated, and 
 dried, 6 7\ grains.” — Klaproth's Analytical 
 Essays , vol. ii. p. 1 43. English Translation. 
 From the above result, and Thenard’s state- 
 ment of the constitution of the oxide, Klap- 
 roth inferred, that the mineral consisted of, 
 Metallic antimony, 67.5 
 Oxygen, - 10.8 
 
 Sulphur, - 19.7 
 
 98.0 
 
 It is painful to be obliged again to point 
 out a very absurd error in Dr Thomson’s 
 account of this analysis. He says, “ The 
 solution was diluted with water. The whole 
 precipitated in the state of a white powder ; 
 for potash threw nothing from the liquid.” 
 It is hard to say whether the matter or expres- 
 sion be here more remarkable. Potash did 
 throw something from the liquid; and must 
 do so, because oxide of antimony is soluble 
 in an excess of muriatic acid ; on which fact, 
 indeed, this and the preceding analysis are 
 founded. 
 
 3. “ Sulphuret of antimony is to be treated 
 with nitro-muriatic acid. The sulphur and 
 the muriate of silver (if any silver be pre- 
 sent) will remain. Water precipitates the 
 antimony ; sulphuric acid the lead ; and am- 
 monia the iron,” — Thomsons System , 5th 
 edition, i ii. 609. This paragraph betrays a 
 strange forgetfulness of the first principles of 
 chemistry ; for, in the first place, nitro- 
 muriatic acid will acidify a portion of the 
 sulphur, and therefore the sulphur will not 
 remain ; in the second place, a portion of 
 oxide of antimony will continue combined 
 with the excess of muriatic acid ; and, in the 
 third place, the acidified sulphur will throw 7 
 down, at first, the lead in the state of insolu- 
 ble sulphate, along with the muriate of sil- 
 ver. 
 
 If the pulverized sulphuret of antimony 
 be acted on by nitric acid, with heat ; and 
 water be afterwards added, a precipitate will 
 fall, consisting of oxide of antimony, with 
 sulphur and sulphate of lead. Sulphate of 
 silver being very soluble in dilute nitric acid, 
 will remain in the liquid. Muriate of soda 
 will throw down the silver, without affecting 
 
 the lead, if the solution be hot and some- 
 what dilute. The lead, if any remain, may 
 then be precipitated by sulphate of soda in 
 equivalent quantity, or by hydrosulphuret of 
 ammonia ; by muriate of barytes, the sul- 
 phuric acid resulting from acidification of 
 the sulphur may be ascertained; and by fer- 
 roprussiate of potash, the iron. On the first 
 precipitate obtained by afftision of water, if 
 muriatic acid be digested, the oxide of anti- 
 mony will be taken up, and may be recover- 
 ed in the metallic state, by immersing a 
 piece of zinc or iron in the muriatic solution. 
 Lastly , the sulphur may be separated from 
 the sulphate of lead by ustulation. 
 
 Metallic antimony is best obtained from 
 the sulphuret, by igniting it, after careful 
 ustulation, with half its weight of crude 
 tartar. The metal will be found at the bot- 
 tom of the crucible. Or the ustulated oxide, 
 mixed with oil, fat, and pounded charcoal, is 
 to be ignited till drops of the metal begin to 
 appear; and nitre equal to 1-1 6th of the 
 weight of the oxide is then to be gradually 
 injected. Or we form the martial regulus of 
 antimony (antimony containing a little iron 
 and sulphur), by adding 16 ounces of the 
 sulphuret to six ounces of iron nails, ignited 
 to whiteness in a crucible. When the whole 
 are in fusion, inject gradually two ounces of 
 pulverized nitre ; then cover the crucible, 
 and urge the heat for a little. Seven or 
 eight ounces of the regulus will be found at 
 the bottom. By repeating the fusion, and 
 projection of nitre, tw r o or three times, the 
 regulus may be brought nearer to the state 
 of pure metal. 
 
 In what follows, I shall confine myself to 
 the detail of a few ingenious and exact ana- 
 lyses. 
 
 2. Bismuth Ores. 
 
 The following analysis of a complex me- 
 tallic mineral by Klaproth is peculiarly in- 
 structive. 
 
 Examination in the humid way of the 
 bismuthic silver ore from Schaupbach, in the 
 Black Forest, in Suabia. 
 
 (a.) Upon 300 grains of this ore, be pour- 
 ed three ounces of nitric acid, diluted with 
 one ounce of water. The residuum being* 
 acted on with more acid, both solutions were 
 mixed, and evaporated to a small volume; 
 during which process, there separated from 
 the fluid some crystalline grains, consisting 
 of nitrate of lead. 
 
 (b . ) The concentrated solution bad a green- 
 ish colour. When afterwards diluted with 
 just as much water as was requisite to re- 
 dissolve that crystalline sediment, it was pour- 
 ed into a large quantity of water. This last 
 immediately acquired a milky appearance, in 
 a high degree, and deposited a white preci- 
 pitate, which weighed 44^ grains, when col- 
 lected, lixiviated, and dried in the air, and 
 
ORE 
 
 ORE 
 
 proved, on further examination, to be oxide 
 of bismuth. 
 
 (c.) Into the liquor, that had been freed 
 from this oxide, and was entirely clear and 
 colourless, he then dropped muriatic acid as 
 long as it was rendered turbid by it. The 
 precipitate, which now fell, did not appear 
 to be mere muriate of silver ; for this reason 
 he digested it for some time with a moder- 
 ately strong nitric acid. A considerable por- 
 tion of it was thus redissolved, and left pure 
 horn-silver behind; which, upon careful col- 
 lection, and desiccation in a brisk heat, 
 weighed 46 grains. Thus, the portion of 
 pure silver is determined at 34| grains. 
 
 (cf.) I he nitric acid that had been affused 
 upon the precipitate obtained by the muriatic 
 (c), yielded by dilution with much water, 32 
 grains more of oxidized bismuth ; which, 
 with the preceding 44-| (6), gave together 
 16\ grains. In order to ascertain the pro- 
 portion of reguline bismuth in this ore, he 
 dissolved 100 grains of bismuth in nitric 
 acid ; and after having concentrated the so- 
 lution by evaporation, he poured it into a 
 large quantity of water. When, of the pre- 
 cipitate thus produced, nothing more would 
 fall down, on adding more water, he collect- 
 ed it, on the filter, washed it, and suffered 
 it to dry perfectly in the air. It then weigh- 
 ed 88 grains. To the water which had been 
 separated from it, muriatic acid was added by 
 drops; whereby a new precipitate ensued, 
 weighing 32 grains, after edulcoration and 
 drying. 
 
 As, by the result of this comparative ex- 
 periment, 100 grains of bismuth have, up- 
 on the whole, given 123 grains of oxide, it 
 follows that the 76£ grains of oxide (d), ob- 
 tained from 300 grains of this ore, contain 
 
 (52^ grains of metallic bismuth. 
 
 ( e . ) The remainder of the fluid was fur- 
 ther reduced by evaporation ; and in this 
 process, muriate of lead separated from it in 
 delicate broad striated crystals. This liquor 
 was then combined with such a quantity of 
 sulphuric acid, as was requisite to redissolve 
 those crystals, and a second time evaporated 
 to a consistence of pap. The precipitate 
 which thence ensued, was sulphate of lead, 
 weighing 19 grains, when duly collected, 
 washed and dried. 
 
 ( f.) What still remained of the solution, 
 after its having been freed from the lead be- 
 fore contained in it, was saturated with caus- 
 tic ammonia added in excess. In this way, 
 a brown ferruginous precipitate was pro- 
 duced ; which was rapidly attracted by the 
 magnet, and weighed 14 grains, when, after 
 previous desiccation, it had been moistened 
 with linseed oil, and well ignited. For these 
 we must reckon 10 grains of metallic iron. 
 
 (g.) The liquor which had been super- 
 saturated with ammonia, and which, by its 
 
 blue colour, shewed that it held copper in 
 solution, was saturated to excess wfith sul- 
 phuric acid. On immersing then a piece of 
 polished iron into it, two grains of copper 
 were deposited. 
 
 (//.) The grey residue of the ore, that was 
 left behind by the nitric acid (a), weighed 
 178 grains. But when its sulphureous part 
 had been deflagrated, in a crucible gently 
 heated, it weighed only 140* grains. This 
 determines the portion of sulphur at 37* 
 grains. 
 
 (i.) These 140^ grains were digested with 
 three ounces of muriatic acid, in a heat of 
 ebullition ; and the process was repeated 
 once more with 1* ounce of the same acid. 
 Ihese solutions, by means of evaporation, 
 yielded till the end, muriate of lead in tender 
 spicular, and likewise in broad striated crys- 
 tals ; which, when again dissolved in the re- 
 quisite quantity of boiling water, then com- 
 bined with sulphuric acid, and evaporated, 
 yielded 89 grains of sulphate of lead. Thus, 
 the whole quantity of this sulphate, includ- 
 ing the 1 9 grains mentioned at (<?), amount- 
 ed to 188 grains; for which, according to 
 comparative experiments, 76 grains of re- 
 guline lead must be put in the computation. 
 
 (k.) That portion of the ore examined, 
 which still remained after all the constituent 
 parts before mentioned had been discovered, 
 consisted merely of the grey quartzose ma- 
 trix; the weight of which, in the ignited 
 state, amounted to 70 grains. 
 
 Therefore, these 300 grains of bismuthic 
 silver ore were decomposed into 
 
 Lead, (t) 
 
 76.00 
 
 Exclu. of mat. 
 33.00 
 
 Bismuth, ( d ) 
 
 62.20 
 
 27.00 
 
 Silver, (c) 
 
 34.50 
 
 15.00 
 
 Iron, (/) 
 
 10.00 
 
 4.30 
 
 Copper, ( g ) 
 
 2.00 
 
 0.90 
 
 Sulphur, ( h ) 
 
 87.50 
 
 16.30 
 
 Quartzose matrix, (&) 70.00 
 
 
 • 
 
 292.20 
 
 96.5 
 
 3. Analysis of Cerite by Vauquelin : — 
 The specimen was of a slight rose colour; 
 and sufficiently hard to scratch glass. Sp. 
 gr. 4.53. Streak greyish. It reddened with 
 calcination, losing 12 per cent. 
 
 (a.) 100 grains of this mineral, in fine 
 powder, were mixed with ten times their 
 weight of nitro-muriatic acid, and subjected 
 to ebullition for an hour ; the mixture being 
 diluted with water, and filtered, left on the 
 filter a brown dust, which was dried and 
 fused with caustic potash. The mixture 
 being diluted with w r ater, and then dissolved 
 in muriatic acid, evaporated to dryness, and 
 redissolved in w r ater, left a powder which, 
 when collected on a filter, w'ashed and cal- 
 cined, weighed 17 parts; it was pure silex, 
 still slightly coloured yellow. 
 
ORE 
 
 ORE 
 
 (6.) The nitro- muriatic solution being eva- 
 porated to dryness, and its residuum redis- 
 solved in water, left about one part of silex, 
 coloured by a little oxide of cerium. 
 
 (c.) The same solution, freed from silex, 
 and united to the washings of the silex, was 
 decomposed by ammonia ; the oxide of ce- 
 rium and the oxide of iron, precipitated by 
 this means, were separated from the liquid 
 by filtration. The oxalic acid added to this 
 liquid, formed a precipitate, which, by cal- 
 cination, gave two parts of lime. 
 
 ( d .) The metallic oxides united and cal- 
 cined, weighed 70 parts; they had a beauti- 
 ful reddish-brown colour. To separate the 
 iron from the cerium, the whole was dissolved 
 in muriatic acid ; the solution being concen- 
 trated to evaporate the excess of acid, then 
 diluted with water, and decomposed by tar- 
 trate of potash, there was formed a very 
 abundant white precipitate, which being 
 washed till it contained no more foreign 
 salts, then dried and calcined, gave 67 parts 
 of oxide of cerium. 
 
 (e.) The water from the washing of the 
 tartrate of cerium, being united and mixed 
 with hydrosulphuret of potash, gave a pre- 
 cipitate which became black in the air. It 
 was oxide of iron, the weight of which, after 
 calcination, was two parts. 
 
 Thus, 100 parts of cerite furnished by this 
 analysis, 
 
 Silica, (a) (6) - - 17 
 
 Lime, (c) 2 
 
 Oxide of iron, (d) - 2 
 
 Oxide of cerium, (<?) - - 67 
 
 Water and carbonic acid, by estimate, 12 
 
 100 
 
 4. Copper Ores. Analysis of Siberian 
 malachite, by Klaproth : — 
 
 (a.) 100 grains of malachite reduced to 
 powder by trituration, were dissolved in ni- 
 tric acid ; which was effected without leav- 
 ing any residue. The solution had a bright 
 blue colour ; and was saturated to excess 
 with ammonia; but the precipitate produced 
 was entirely and without tardiness redissolv- 
 ed by the excess of the alkali. This shewed 
 that the malachite here examined was per- 
 fectly free from iron, and similar admix- 
 tures. 
 
 (6.) He combined 100 grains of triturated 
 malachite, with a sufficient quantity of sul- 
 phuric acid, previously diluted with five parts 
 of water, and accurately weighed together 
 with the vessel. After the malachites had 
 been wholly dissolved, which was effected 
 gradually, and with a moderately strong 
 effervescence, the loss of weight occasioned 
 by the carbonic acid gas, that was extricated, 
 was found to consist of 18 gr. 
 
 (c.) 100 grains of the same powdered ma- 
 lachite*, were ignited at a moderate heat in 
 
 n covered crucible. The black residue had 
 lost 29i| grains in weight. If from these be 
 subtracted 18 grains for the carbonic acid, 
 the remaining 11^ grains of loss will consist 
 of water. 
 
 (d.) And lastly, 100 grains, which had 
 been dissolved in dilute sulphuric acid, and 
 precipitated by zinc, yielded 58 grains of 
 pure copper. 
 
 In consequence of these experiments, the 
 Siberian malachites consist of 
 Copper, 58 
 
 Carbonic acid, 18 
 Oxygen, 12.5 
 Water, 11.5 
 
 100.0 
 
 5. Gold Ores. A very instructive ana- 
 lysis of the Transylvanian auriferous lamellar 
 ore, from Naygag, by Klaproth : — 
 
 (a.) 1000 grains, freed in the best possible 
 manner from the stony matrix, were tritu- 
 rated, and digested at a moderate heat, first 
 with ten ounces of muriatic acid, to which 
 nitric acid was gradually added. A violent 
 action then took place, and the black colour 
 of the powdered ore rapidly disappeared. 
 While the fluid was yet hot, it was poured 
 upon a filter ; and the residue was once 
 more digested with five ounces of muriatic 
 acid, and the whole filtered. In a short 
 time acicular crystals were deposited in the 
 solution, which was yellow, and likewise on 
 the filtering paper. These crystals w T ere 
 covered with boiling hot water, till they 
 were all dissolved ; after which only the 
 quartzose portion of the matrix and some 
 6ulphur remained. 
 
 ( b .) The sulphurous ingredient in the ore, 
 had united into a coherent mass, and could 
 therefore be easily removed from the earthy 
 residue. Its weight was 17^ grains. Burn- 
 ed on a moderately heated calcining test, it 
 left 3^ grains of blackish residuum, which 
 was dissolved in muriatic acid and added to 
 the foregoing solution. Hence the quantity 
 of sulphur was 14 grains. 
 
 (c.) That portion of the matrix which 
 consisted of white grains of quartz, weighed 
 in the dry state 440^ grains. This beiDg 
 mixed w T ith four times its quantity of car- 
 bonate of potash, w r as melted to vitrifaction. 
 On breaking the crucible, a few globules of 
 silver were found dispersed ; which, however, 
 could not be well collected. But from ano- 
 ther experiment, to be mentioned in the se- 
 quel, it resulted, that this silver may be esti- 
 mated at c 2\ grains. Whence, since in the 
 present case, it was in the state of muriate, 
 3^ grains are to be subtracted, so that of the 
 above stated weight 437 grains remain. 
 
 (d.) The solution ( a ) from which, on addi- 
 tion of the edulcorating water, a white tel- 
 luric oxide fell down in a great quantity, 
 
ORE 
 
 ORE 
 
 was concentrated by evaporation ; during 
 which process that precipitate again entirely 
 dissolved. On the other hand, numerous 
 crystals of muriate of lead were deposited 
 from the liquor, even while warm; which 
 being taken out, the evaporation was carried 
 on as long as any more of them appeared. 
 These crystals, when collected, were care- 
 fully rinsed, by dropping upon them muria- 
 tic acid, and highly dried. They weighed 
 330 grains, equivalent to 248 grains of lead 
 ill the metallic state. 
 
 (c.) After the concentrated solution had 
 been thus freed from lead, he diluted it a 
 little with water, and added a large quantity 
 of spirit of wine, as long as any white preci- 
 pitate fell. The mixture having stood for a 
 while in a gentle warmth, that precipitated 
 was collected on the filter, edulcorated with 
 ardent spirit, redissolved in muriatic acid, 
 and precipitated again in the state of a pure 
 telluric oxide, by means of caustic soda, and 
 by strictly watching the precise point of sa- 
 turation. This oxide, washed and dried, gave 
 in the balance 178 grains, which correspond 
 to 1 48 grains of reguline tellurium. 
 
 (jl) For the purpose of ascertaining the 
 proportion of gold, he now reduced the fluid, 
 from which the tellurium had been separated, 
 by distilling off' the spirit of wine in a retort ; 
 diluted again the concentrated solution with 
 water ; and lastly, dropped into it a nitric 
 solution of mercury, prepared without the 
 assistance of heat ; adding this nitrate, until 
 ho brown precipitate any longer appeared, 
 and till the white precipitate which succeed- 
 ed the brown, no more changed its own co- 
 lour. After this the mixture was placed in 
 a warm temperature, where the white preci- 
 pitate, which was owing to the nitrated mer- 
 cury added in excess, again gradually disap- 
 peared. The brown precipitate, which fell 
 to the bottom as a heavy powder, was the 
 gold sought for. When collected and fused 
 with nitrate of potash, it gave a bead of pure 
 gold, weighing 41-§ grains. 
 
 (g.) The liquor was now saturated with 
 carbonate of soda, in a boiling heat. A 
 copious bluish- grey precipitate ensued, which 
 turned black-brown by ignition. Digested 
 with muriatic acid, it dissolved again clearly, 
 and gave out oxygenated muriatic acid gas. 
 By combining this solution with liquid car- 
 bonate of ammonia to a considerable degree 
 of supersaturation, a greyish-white precipi- 
 tate was produced ; which, collected, washed, 
 and dried, weighed 92 grains, and proved to 
 be a somewhat iron shot, carbonated oxide 
 of manganese. ' 
 
 ( h .) The ammoniacal lixivium (g) ap- 
 peared of a blue colour. After being super- 
 saturated with sulphuric acid, by which it 
 was again rendered colourless, a small plate 
 of polished iron was introduced, and the ves- 
 
 sel put in a warm place. The iron became 
 
 gradually coated with copper, the weight of 
 
 which after drying was six grains. 
 
 Therefore the 1000 grains Exclusive of the 
 
 were decomposed into matrix oi quartz 
 
 r aod mangane- 
 
 6ian ore. 
 
 Lead, (d) 248.0 54.0 
 
 Tellurium, (e) 148.0 32.2 
 
 Gold > (/) 41.5 9.0 
 
 Silver, ( c ) 2.5 0.5 
 
 Copper, (A) 6.0 1.3 
 
 Sulphur, (5) 14.0 3.0 
 
 Oxide of manganese, (g) 92.0 
 
 Quartz, (c) 437.0 100.0 
 
 Loss, 
 
 989.0 
 
 11.0 
 
 1000.0 
 
 6. Iron Ores are usually analyzed by fu- 
 sion. On this subject, there is a valuable essay 
 by Mr Mushet, in the 4th volume of the Phil. 
 Magazine. In the hematites iron ore, for 1 
 pound avoirdupois, he commonly added 6 
 ounces dried chalk, and of an ounce of 
 charcoal ; and for the splinty blue ore also a 
 similar mixture. From both of these mix- 
 tures, he obtained the richest sort of crude 
 iron. The kidney ore will admit of a dimi- 
 nution of chalk, and a small addition of 
 glass. One pound avoirdupois of this va- 
 riety will be accurately assayed by the addi- 
 tion of 5 ounces chalk, 1 ounce glass, and ^ 
 of an ounce of charcoal. The same propor- 
 tion of mixtures will also accurately reduce 
 the small pieces of this ore, commonly of a 
 soft greasy consistence, mixed with small 
 fragments of the hematites and the kidney, 
 and will give out the iron which they con- 
 tain, supercarburetted. A mixture of this 
 soft ore, with kidney, is preferred to the 
 richer variety, at the iron manufactories. 
 The Lancashire ore consists chiefly of this 
 compound, and the poorer in iron has always 
 a decided preference given it, at the blast- 
 furnace. The Elba ore may be reduced 
 into smooth carburetted iron, by exposing to 
 a melting heat 2 ounces of it mixed with 2 
 ounces of chalk, 1^ ounce bottle-glass, and 
 i ounce of charcoal. To the Islay iron ore, 
 and the Norwegian, Danish, and Swedish, 
 Mr Mushet adds, for every pound, 7 ounces 
 of dried chalk, 5 of bottle-glass, and 1 of 
 charcoal. By carburetted iron is meant cast- 
 iron. 
 
 I shall now give an outline of Mr Hat- 
 chett’s much admired analysis of the mag- 
 netical pyrites. 
 
 (a.) 100 grains reduced to a fine powder, 
 were digested with two ounces of muriatic 
 acid, in a glass matrass placed in a sand-bath, 
 A strong effervescence ensued, occasioned 
 by the production of sulphuretted hydrogen 
 gas; and a pale yellowish-green solution 
 
ORE 
 
 ORE 
 
 was formed. The residuum was then again 
 digested with two parts of muriatic acid, 
 mixed with one of nitric acid ; and a quan- 
 tity of pure sulphur was obtained, which, 
 being dried, weighed 14 grains. 
 
 (b.) The acid in which the residuum had 
 been digested, w'as added to the first muriatic 
 solution ; some nitric acid was also poured 
 in to promote the oxidizement of the iron, 
 and thereby to facilitate the precipitation of 
 it by ammonia, which was added after the 
 liquor had been boiled for a considerable 
 time. The precipitate thus obtained was 
 boiled with lixivium of potash ; it w r as then 
 edulcorated, dried, made red-hot with w'ax 
 in a covered porcelain crucible, and com- 
 pletely taken up by a magnet, and being 
 weighed, amounted to 80 grains. 
 
 (c.) The lixivium of potash was examined 
 by muriate of ammonia, but no alumina w r as 
 obtained. 
 
 (d.) To the filtered liquor, from which the 
 iron had been precipitated by ammonia, mu- 
 riate of barytes was added, until it ceased to 
 produce any precipitate ; this w'as then di- 
 gested w ith some very dilute muriatic acid ; 
 was collected, washed, and after exposure to 
 alow red-heat, for a few minutes in a cruci- 
 ble of platinum, weighed 155 grains. If 
 therefore the quantity of sulphur converted 
 into sulphuric acid by the preceding opera- 
 tions, and precipitated by barytes, be calcu- 
 lated according to the experiments of M. 
 Chenevix, then, 155 grains of sulphate of 
 barytes, will denote nearly 22.5 of sulphur, 
 (21. Dr Wollaston’s scale); so that w'ith the 
 addition outlie 14 grains previously obtained 
 in substance, the total quantity will amount 
 to 36.5, (35). 
 
 ( e .) Moreover, from what has been stated, 
 it appears, that the iron which was obtained 
 in the form of black oxide, weighed 80 
 grains; and by adding these 80 grains to 
 the 36.5 of sulphur, an increase of weight is 
 found = 16.5. This was evidently owing 
 to the oxidizement of the iron, which in the 
 
 magnetical pyrites, exists quite or very nearly 
 in the metallic state ; but by the operations 
 of the analysis, has received this addition. 
 The real quantity of iron must on this ac- 
 count be estimated at 63.5. 100 grains, 
 
 therefore, of the magnetical pyrites yielded, 
 
 Sulphur, j (“j jJJ (14> } 36.5 (35) 
 Iron > (e) = 63.5 (62.22) 
 
 100.0 97.22 
 
 This analysis was repeated in a similar 
 manner, excepting that the whole was digest- 
 ed in nitric acid, until the sulphur was en- 
 tirely converted into sulphuric acid. To the 
 liquor which remained after the separation of 
 the iron by ammonia, muriate of barytes was 
 added, as before, and formed a precipitate 
 
 winch weighed 245 grains. Now these, by 
 Dr Wollaston’s scale, are equivalent to nearly 
 33.5 of sulphur. Hence it would appear, 
 that a little sulphur is dissipated, in the form 
 of sulphurous acid, by this mode of opera- 
 tion. 
 
 The theoretical equivalent proportions of 
 magnetic pyrites are, 
 
 Sulphur, 36.363 2.00 
 
 Iron, 63.636 3.50 
 
 We thus see, that Mr Hatchett’s final 
 statement is almost exact, in consequence of 
 M. Chenevix’s erroneous estimate of the 
 composition of sulphuric acid and sulphate 
 of barytes, making a compensation for the 
 experimental deviation, or loss ; amounting 
 on the iron to 1.416, and on the sulphur to 
 1.3 63, in the 100 parts. 
 
 Analysis of arseniate of* iron, by M. Che- 
 nevix : — 
 
 100 grains boiled with potash left 58.5. 
 The liquor treated by nitrate of lead, gave 
 of arseniate of lead, a quantity w hich be es- 
 timated as equivalent to 5 1 of arsenic acid. 
 The 58.5 left 4, which muriatic acid could 
 not dissolve, and which were silica. Ammo- 
 nia dissolved 9, and there remained 45.5 of 
 oxide of iron. This analysis presents the 
 following results : 
 
 Arsenic acid, 
 
 31.00 
 
 Oxide of iron, 
 
 45.50 
 
 Oxide of copper, 
 
 9.00 
 
 Silica, 
 
 4.00 
 
 Water, by inference, 
 
 10.50 
 
 
 100.00 
 
 7. Lead Ore. Analysis of yellow' lead 
 
 ore from Wanlockhead, by Klaproth: 
 
 (a.) Upon 100 grains of this ore finely 
 levigated, dilute nitric acid was poured and 
 heated. They dissolved, and only a few in- 
 considerable flocks escaped the action of the 
 solvent. The filtered colourless solution, 
 when treated with nitrate of silver, gave 10-J 
 muriate of silver, which indicates, says Klap- 
 roth, 1.62 grains dry muriatic acid. 
 
 (6.) Sulphuric acid was then presented to 
 the solution. It precipitated the lead con- 
 tained in that fluid in the state of sulphate; 
 which having suffered a red-heat, weighed 
 108f grains; for which 80 grains of oxide 
 of lead must be allowed. 
 
 (c.) The excess of sulphuric acid being 
 separated by means of nitrate of barytes, am- 
 monia w'as added to the saturation of the 
 nitric acid, and the phosphoric acid was then 
 thrown down with acetate of lead. From 
 80 grains of phosphate of lead thus obtained, 
 he inferred 1 8 grains of phosphoric acid to 
 have existed in the ore. 
 
 The residuary part of the fluid contained 
 nothing more of the constituent parts of the 
 mineral, excepting a slight trace of iron. 
 Consequently 100 gr. w ere resolved into 
 
ORE 
 
 ORE 
 
 Oxide of lead, 80. 
 
 Phosphoric acid, 18. 
 
 Muriatic acid, 1.62 
 
 * 
 
 99.62 
 
 8. Analysis of Grey Silver Ore, by 
 Klaproth : — 
 
 (a.) 300 grains of the fragments selected 
 Irom the pounded ore, though not perfectly 
 separable from the quartzose gangue, with 
 which they were firmly concreted, were levi- 
 gated to a subtle powder, and digested with 
 four times their weight of nitric acid. The 
 digestion was renewed with the residuum, in 
 an equal quantity of the same acid ; and the 
 portion which still remained undissolved then 
 assumed a greyish-yellow colour, and weigh- 
 ed 188 grains. 
 
 (6.) By the addition of muriate of soda to 
 the bright green nitric solution, its silver 
 was thrown down ; and this precipitate col- 
 lected and reduced by means of soda, yielded 
 31^ grains of metallic silver. 
 
 (c.) The silver being thus separated, he 
 tried the solution for lead ; but neither the 
 neutral sulphates, nor free sulphuric acid, 
 could discover the least sign of it. 
 
 (d . ) After this he added caustic volatile 
 alkali, so as to supersaturate the acid ; upon 
 which a reddish-brown precipitate, of a loose 
 cohesion, appeared, that by ignition became 
 of a black-brown, and weighed 9^ grains. 
 It dissolved in nitric acid, leaving behind it 
 half a grain of siliceous earth. Prussiate of 
 potash produced from the filtered solution a 
 deep blue precipitate of iron ; and after this 
 was separated, 1^ grains of alumina w r ere ob- 
 tained from it by means of soda. Therefore 
 subtracting the siliceous and argillaceous 
 earths, the portion of iron attractible by the 
 magnet amounted to grains. 
 
 (e.) To the solution, which had been be- 
 fore supersaturated with pure ammonia, and 
 exhibited a sapphire-blue colour, sulphuric 
 acid was now added to excess. A polished 
 piece of iron was then immersed into the 
 fluid, from which it precipitated 69 grains of 
 copper. 
 
 (f.) The above greyish-yellow residuum 
 (a) was now to be examined. It was di- 
 gested with six times its quantity of muriatic 
 acid, in a heat of ebullition. When filtered, 
 the residue which was left on the paper, be- 
 ing first washed with muriatic acid, then 
 with a little alcohol, and lastly dried, was 
 found to weigh 105^ grains. 
 
 (g.) From the solution which was obtain- 
 ed by the last process, and was of a straw- 
 yellow, the greater part of the fluid was 
 drawn off’ by a gentle distillation in a retort. 
 The remaining concentrated solution then 
 deposited some crystalline grains, which were 
 carefully collected, and proved upon inquiry 
 to be muriate of silver, weighing one-fourth 
 of a grain. A large quantity of water being 
 
 next pouied into the solution, a copious pre- 
 cipitate subsided, weighing after desiccation 
 97^ grains. It proved by every test to be 
 oxide of antimony, for which, as was found 
 by comparative experiments, 75 grains of 
 reguline antimony must be allowed. 
 
 (k.) The residue obtained (f) weighing 
 105^ grains, which comprised the sulphured 
 ous part of the ore, was exposed to a low 
 heat, by which treatment the sulphur was 
 consumed, and 80^ grains of silica remained. 
 Hence the quantity of the sulphur was equal 
 to 25\ grains. 
 
 (*•) The siliceous earth was next fused 
 with four times its weight of black flux. The 
 melted mass entirely dissolved in twice its 
 weight of water into liquor of flints ; some 
 minute particles of silver, weighing three- 
 fourths of a grain, excepted. According to 
 this, the proportion of silica amounted to 79^ 
 grains. 
 
 The whole constituents therefore are, 
 
 Ore, exclusive of 
 
 
 
 
 
 
 silica, in 100. 
 
 Silver, 
 
 (b) 31.5 1 
 
 
 
 
 
 (g) 
 
 0.25 
 
 ► 
 
 32.50 
 
 14.77 
 
 
 (0 
 
 0.75, 
 
 
 
 
 Copper, 
 
 W 
 
 
 
 69.00 
 
 31.36 
 
 Antimony, (g) 
 
 
 
 75.00 
 
 34.09 
 
 Iron, 
 
 (<0 
 
 
 
 7.25 
 
 3.30 
 
 Sulphur, 
 
 (*> 
 
 
 
 25.25 
 
 11.50 
 
 Alumina, 
 
 (d) 
 
 
 
 1-50 
 
 0.20 
 
 Silica, 
 
 (d) and (i) 
 
 
 80.00 
 
 95.52 
 
 9. Analysis of Tin ores by Klaproth : — 
 
 1 . Tinstone. 
 
 (a.) 100 grains of tinstone from Alter- 
 non, in Cornwall, previously ground to a 
 subtle powder, were mixed in a silver vessel, 
 with a lixivium containing 600 grains of 
 caustic potash. This mixture was evapo- 
 rated to dryness in a sand heat, and then 
 moderately ignited for half an hour. When 
 the grey -white mass thus obtained, had been 
 softened while yet warm with boiling water, 
 it left on the filter 1 1 grains of an undissolv- 
 ed residue. 
 
 (5.) These 11 grains, again ignited with 
 6 times their weight of caustic potash, and 
 dissolved in boiling water, left now only 1* 
 grains of a fine vellowish-grey powder behind. 
 
 (c. ) The alkaline solution, (a and 6), 
 which was in some degree colourless, was 
 saturated with muriatic acid. A brilliant 
 white tender oxide of tin was thrown down, 
 giving to the mixture a milky appearance. 
 This precipitate, redissolved by an additional 
 quantity of muriatic acid, was precipitated 
 afresh by means of carbonate of soda. hen. 
 lixiviated and dried in a gentle heat, it ac- 
 quired the form of bright yellowish trans- 
 parent lumps, having in their fracture a 
 vitreous lustre. 
 
 (d.) This precipitate being finely powder- 
 ed, soon dissolved entirely in muriatic acid* 
 
ORE 
 
 ORE 
 
 assisted by a gentle heat. Into the colour- 
 less solution, previously diluted with from 2 
 to 3 parts of water, he put a stick of zinc ; 
 and the oxide of tin, thus reduced, gathered 
 around it, in delicate dendritic laminae, of a 
 metallic lustre. These, when collected, wash- 
 ed, dried, and fused under a cover of tallow, 
 in a capsule placed upon charcoal, yielded a 
 button of pure metallic tin, weighing 77 
 grains. 
 
 (e.) The above mentioned residue of 1 \ 
 grains, left by the treatment with caustic 
 potash (6), afforded with muriatic acid a yel- 
 lowish solution ; from which, by means of a 
 little piece of zinc introduced into it, \ grain 
 of tin was still deposited, Ferroprussiate of 
 potash, added to the remainder of the solu- 
 tion, produced a small portion of a light blue 
 precipitate; of which, after deducting the 
 oxide of tin, now combined with it, hardly ^ 
 of a grain remained, to be put to the account 
 of the iron, contained in the tinstone, here 
 examined. 
 
 In these experiments, (excepting only a 
 slight indication of silex, amounting to about 
 | of a grain), no trace appeared, either of 
 tungstic oxide, which some mineralogists have 
 supposed to be one of the constituent parts 
 of tinstone, nor of any other fixed substance. 
 Therefore what is deficient in the sum, to 
 make up the original weight of the mineral 
 analyzed, must be ascribed to the loss of 
 oxygen ; and thus the constituent parts of 
 pure tinstone from Alternon, are to each 
 other in the following proportion : 
 
 Tin, 77.30 
 
 Iron, 0.25 
 
 Silica, 0.75 
 
 Oxygen, 21.50 
 
 100.00 
 
 2. Tin pyrites, from Wheal- Rock, St 
 Agnes in Cornwall, 
 
 (a.) 120 grains of finely triturated tin 
 pyrites w ere treated with an aqua regia, com- 
 posed of 1 ounce muriatic acid, and £ ounce 
 of nitric acid. Within 24 hours, the greatest 
 part of the metallic portion was dissolved in 
 it, without application of heat; while the 
 sulphur rose up and floated on the surface of 
 the menstruum. After the mixture had been 
 digested upon it for some time in a low sand 
 heat, it was diluted with water, and thrown 
 on a filter. It left 43 grains of sulphur on 
 the paper, still, however, mixed with metallic 
 particles. W hen the sulphur had been gen- 
 tly burnt of! on a test, there still remained 
 13 grains; of which 8 were dissolved by n i- 
 tro-muriatic acid. The remaining part was 
 then ignited with a little wax ; upon which 
 the magnet attracted 1 grain of it. What 
 remained was part of the siliceous matrix, 
 and weighed 3 grains. 
 
 (b). The solution of the metallic portion 
 
 (a) was combined with carbonate of potash $ 
 and the dirty-green precipitate, thus obtain- 
 ed, was redissolved in muriatic acid, diluted 
 w ith 3 parts of water. Into this fluid, a cy- 
 linder of pure metallic tin, weighing 217 
 grains, was immersed. The result was, that 
 the portion of copper contained in the solu- 
 tion, deposited itself on the cylinder of tin ; 
 at the same time that the fluid began to lose 
 its green colour, from the bottom upwards, 
 until after tlfe complete precipitation of the 
 copper in the reguline state, it became quite 
 colourless. 
 
 ( c .) The copper thus obtained weighed 44 
 grains. By brisk digestion in nitric acid, it 
 dissolved, forming a blue tincture, and left 
 1 grain of tin behind, in the character of a 
 w hite oxide. Ihus the portion of pure cop- 
 per consisted of 43 grains. 
 
 (d.) The cylinder of tin employed to pre- 
 cipitate the copper, now weighed 1 28 grains ; 
 so that 89 grains of it had entered into the 
 muriatic solution. From this, by means of 
 a cylinder of zinc, he reproduced the whole 
 of the dissolved tin, which was loosely de- 
 posited upon the zinc, in a tender dendritical 
 form. When the tin was all precipitated, he 
 collected and lixiviated carefully, and suffer- 
 ed it to dry. It weighed 130 grains. By 
 mixing it with tallow, he melted it into 
 grains, under a cover of charcoal dust, in a 
 small crucible ; and separated the pow'der of 
 the coal by elutriation. Among the w’ashed 
 grains of tin, some black particles of iron 
 were observed, which were attractible by the 
 magnet, and weighed 1 grain. Deducting 
 this, there remain 129 grains for the weight 
 of the tin. By subtracting again from these 
 last those 89 grains, which proceeded from 
 the cylinder of tin employed for the precipi- 
 tation of the copper (6), there remained 40 
 grains, for the portion of tin contained in the 
 tin pyrites examined. Hence, including the 
 1 grain of tin, which had been separated from 
 the solution of the copper (c), the portion of 
 pure tin contained in this ore amounted to 
 41 grains. The following is a view of the 
 results: — Inl20gr. In 100. 
 
 Sulphur 30 25 
 
 Tin, 41 34 
 
 Copper, 43 56 
 
 Iron, 2 2 
 
 Gangue, S — 
 
 — 97 
 
 119 
 
 The darker varieties are considerably poorer 
 in tin. The reduction of the ores of tin is 
 effected, by roasting the ore after it has been 
 pulverized in stamping mills, and then expos- 
 ing it to heat, in a reverberatory or blast fur- 
 nace, along with W elsh small coal or culm. 
 If much copper be present, it is afterwards 
 fused at a very gentle heat, and what flows 
 off is pretty pure tin. 
 
ORE 
 
 OSM 
 
 Zinc is reduced by distillation of its ore 
 (previously. roasted) in a retort, along with 
 charcoal. * 
 
 A sulphuret of zinc was lately met with in 
 one of the Gwennap mines, incrusting a 
 spongy pyrites intermixed with quartz, and 
 so like wood-tin, as to be supposed a variety 
 of it by the miners. According to Dr Kidd, 
 it consists of 66 oxide of zinc, 33 sulphur, 
 and a very minute portion of iron. The 
 pyrites contains cobalt. 
 
 In the dry way, zinc is reduced by distil- 
 ling its ore after torrefaction, with a mixture 
 of its own weight of charcoal, in an earthen 
 retort well luted, and a strong heat: but by 
 this method scarce half the zinc it contains is 
 obtained. 
 
 The first dressing of calamine for the large 
 works of zinc, consists in picking out all the 
 pieces of lead ore, lime, and ironstone, cauk, 
 and other heterogeneous substances, which 
 are found mixed with it in the mine : it is 
 then roasted in proper furnaces, where it 
 loses about a third or fourth part of its 
 weight. It is picked out again very care- 
 fully, as the heterogeneous particles have be- 
 come more discernible by the action of the 
 fire ; it is then ground to a fine powder, and 
 washed in a gentle rill of water, which car- 
 ries oft' the earthy mixtures of extraneous 
 matters ; so that, by these processes, a ton of 
 the crude calamine of Derbyshire is reduced 
 to 1 2 cwt. only. 
 
 Bergman affirms, that a certain English- 
 man, whose name he does not mention, made, 
 several years ago, a voyage to China, for the 
 purpose of learning the art of smelting zinc, 
 or tutenague ; and that he became instruct- 
 ed in the secret, and returned safely home. 
 
 It is not improbable, but that a fact of this 
 kind may have served to establish the manu- 
 factory of zinc in England about the year 
 1 743, when Mr Champion obtained a patent 
 for the making of it, and built the first work 
 of the kind near BristoL It consists, as 
 Watson relates, of a circular kind of oven, 
 like a glass-house furnace, in which were 
 placed six pots, of about four feet each in 
 height, much resembling large oil jars in 
 shape ; into the bottom of each pot is insert- 
 ed an iron tube, which passes through the 
 floor of the furnace, into a vessel of water. 
 A mixture of the prepared ore is made with 
 charcoal, and the pots are filled with it to 
 the mouth, which are then close stopped with 
 strong covers, and luted with clay. The fire 
 being properly applied, the metallic vapour 
 of the calamine issues, dowmwards, or per 
 descensum, through the iron tubes, there be- 
 ing no other place through which it can 
 escape ; and the air being excluded, it does 
 not take fire, but is condensed in the water 
 into granulated particles; which, being re- 
 melted, are cast into ingots, and sent to Bir- 
 mingham under the name of zinc, or spelter; 
 
 although by this last name of spelter, only a 
 granulated kind of soft brass is understood 
 among the braziers, and others who work in 
 Eondon, used to solder pieces of brass to- 
 gether. 
 
 * Orichalcum. The brass of the ancients; 
 their ass was a species of bronze.* 
 
 * Orpiment. Sulphuret of arsenic. See 
 Ores of Arsenic.* 
 
 * Ortiiite. A mineral so named because 
 it always occurs in straight layers, generally 
 in felspar. It resembles gadolinite, and con. 
 sists of, peroxide cf cerium 19.5, protoxide 
 of iron 12.44, protoxide of manganese 3.44, 
 yttria 3.44, silica 32.0, alumina 14.8, lime 
 7.84, water 5. 36. — Berzelius. It is found 
 in the mine of Finbo, in the vicinity of Fah- 
 lum in Sweden. The mine is situated in a 
 vein of granite which traverses gneiss.* 
 
 * Osmazome. If cold water which has 
 been digested, for a few hours, on slices of 
 raw muscular fibre, with occasional pressure, 
 be evaporated, filtered, and then treated with 
 pure alcohol, a peculiar animal principle 
 will be dissolved, to the exclusion of the salts. 
 By dissipating the alcohol with a gentle heat, 
 the osmazome is obtained. It has a brownish- 
 yellow colour, and the taste and smell cf 
 soup. Its aqueous solution alfords precipi- 
 tates, with infusion of nut-galls, nitrate of 
 mercury, and nitrate and acetate of lead.* 
 
 Osmium. A new metal lately discovered 
 by Mr Tennant among platina, and thus 
 called by him from the pungent and pecu- 
 liar smell of its oxide. For the mode in 
 which he extracted it, see Iridium. 
 
 Its oxide may likewise be obtained in 
 small quantity by distilling with nitre the 
 black pow der left after dissolving platina ; 
 when at a low red-heat an apparently oily 
 fluid sublimes into the neck of the retort, 
 which on cooling concretes into a solid, co- 
 lourless, semi-transparent mass. This being 
 dissolved in water, forms a concentrated so- 
 lution of oxide of osmium. This solution 
 gives a dark stain to ihe skin, that cannot be 
 effaced. Infusion of galls presently pro- 
 duces a purple colour in it, which soon after 
 becomes of a deep vivid blue. This is the 
 best test of the oxide. With pure ammonia 
 it becomes yellowy and slightly so with car- 
 bonate of soda. With lime it forms a bright 
 yellow solution; but it is not affected either 
 by chalk or by pure magnesia. The solu- 
 tion with lime gives a deep red precipitate 
 with galls, which is turned blue by acids. It 
 produces no effect on solution of gold or 
 platina ; but precipitates lead of a yellowish- 
 brown, mercury of a w hite, and muriate of 
 tin of a brown colour. 
 
 Oxide of osmium becomes of a dark colour 
 with alcohol, and after some time separates 
 in the form of black films, leaving the al- 
 cohol w'ithout colour. The same effect is 
 produced by ether, and much more quickly. 
 
OXI 
 
 OXY 
 
 It parts with its oxygen to all the metals 
 except gold and platina. Silver kept in a 
 solution of it some time, acquires a black 
 colour, but does not deprive it entirely of 
 smell. Copper, tin, zinc, and phosphorus, 
 quickly produce a black or grey powder, 
 and deprive the solution of smell, and of the 
 property of turning galls blue. This black 
 powder, which consists of the metallic os- 
 mium, and the oxide of the metal employed 
 to precipitate if, may be dissolved in nitro- 
 muriatic acid, and then becomes blue with 
 infusion of galls. 
 
 i If the pure oxide dissolved in water be 
 shaken with mercury, it soon loses its smell, 
 and the metal forms a perfect amalgam. By 
 squeezing the superfluous mercury through 
 leather, and distilling off the rest, a dark grey 
 or blue powder is left, which is the osmium. 
 
 Exposed to a strong heat in a cavity in a 
 piece of charcoal, it does not melt ; nor is it 
 volatile, if oxidation be carefully prevented. 
 With copper and with gold it forms mallea- 
 ble alloys, which are easily dissolved in ni- 
 tro- muriatic acid, and afford by distillation 
 the oxide of osmium. The pure metal, pre- 
 viously heated, did not appear to be acted 
 upon by acids. Heated in a silver cup with 
 caustic alkali, it combined with it, and gave 
 a yellow solution, similar to that from which 
 it was procured. From this solution acids 
 separate the oxide of osmium. — Phil. Trans . 
 
 * Ossifications. The deposition of calca- 
 reous phosphate or carbonate on the soft solids 
 of animal bodies; as in the pineal gland, 
 lungs, liver, &c.* See Pulm, Concretions. 
 
 * Oxalates. Compounds of the salifiable 
 bases with oxalic acid. See Acid (Oxalic), 
 and the bases.* 
 
 * Oxalic Acid. This acid is described 
 under Acid (Oxalic). It is found in the 
 state of oxalate of lime in the roots of the 
 following plants : — Alkana, apium, bistorta, 
 carlina acaulis, curcuma, dictamnus albus, 
 foeniculum, gentiana rubra, vincetoxicum, 
 lapathum, liquiritia, mandragora, ononis, 
 iris florentina, iris nostras, rheum, saponaria, 
 scilla, sigillum salomonis, tormentilla, Vale- 
 riana, zedoaria, zingiber. And in the fol- 
 lowing barks : — berberis, cassia flstularis, 
 canella alba, cinamomum, cascarilla, cassia 
 caryophyllata, china, culilavan, frangula, 
 fraxinus, quassia, quercus, simaruba, lignum 
 sanctum, ulmus. In the state of binoxylate 
 of potash it exists in the leaves of the oxalis 
 acetosella, oxalis corniculata, different spe- 
 cies of rumex, and geranium acidum. 
 
 The juice of the cicer parietinum is said 
 to be pure oxalic acid. * 
 
 Oxidation. The process of converting 
 metals, or other substances, into oxides, by 
 combining with them a certain portion of 
 oxygen. It differs from acidification in the 
 addition of oxygen not being sufficient to 
 form an acid with the substance oxided. 
 
 Oxides. Substances combined with oxy- 
 gen, without being in the state of an acid. 
 
 Oxygen Gas. This gas was obtained by 
 Dr Priestley in 1774 from red oxide of mer- 
 cury exposed to a burning lens, who observ- 
 ed its distinguishing properties of rendering 
 combustion more vivid and eminently sup- 
 porting life. Scheele obtained it in different 
 modes in 1775; and in the same year La- 
 voisier, who had begun, as he says, to sus- 
 pect the absorption of atmospheric air, or of 
 a portion of it, in the caloination of metals, 
 expelled it from the red oxide of mercury 
 heated in a retort. 
 
 Oxygen gas forms about a fifth of our at- 
 mosphere, and its base is very abundant in 
 nature. Water contains 88.88 per cent of it ; 
 and it exists in most vegetable and animal 
 products, acid9, salts, and oxides. 
 
 This gas may be obtained from nitrate of 
 potash, exposed to a red-lieat in a coated 
 glass or earthen retort, or in a gun-barrel ; 
 from a pound of which about 1200 cubic 
 inches may be obtained ; but this is liable, 
 particularly toward the end of the process, to 
 a mixture of nitrogen. It may be expelled, 
 as already observed, from the red oxide of 
 mercury, or that of lead; and still better 
 from the black oxide of manganese, heated 
 red-hot in a gun-barrel, or exposed to a 
 gentler heat in a retort with half its weight, 
 or somewhat more, of strong sulphuric acid. 
 To obtain it of the greatest purity, however, 
 the chlorate of potash is preferable to any 
 other substance, rejecting the portions that 
 first come over as being debased with the 
 atmospheric air in the retort. Growing ve- 
 getables, exposed to the solar light, give out 
 oxygen gas; so do leaves laid on water in 
 similar situations, the green matter that forms 
 in water, and some other substances. 
 
 Oxygen gas has neither smell nor taste. 
 Its sp. gr. is 1.1111 ; 100 cubic inches weigh 
 33.88 gr. It is a little heavier than atmos- 
 pheric air. Under great pressure water may 
 be made to take up about half its bulk. It 
 is essential to the support of life : an animal 
 will live in it a considerable time longer than 
 in atmospheric air ; but its respiration becomes 
 hurried and laborious before the whole is 
 consumed, and it dies, though a fresh ani- 
 mal of the same kind can still sustain life for 
 a certain time in the residuary air. 
 
 Combustion is powerfully supported by 
 oxygen gas. Any inflammable substance, 
 previously kindled, and introduced into it, 
 burns rapidly and vividly. If an iron or 
 copper wire be introduced into a bottle of 
 oxygen gas, with a bit of lighted touchwood 
 or charcoal at the end, it will burn with a 
 bright light, and throw out a number of 
 sparks. The bottom of the bottle should be 
 covered with sand, that these sparks may not 
 crack it. If the wire coiled up in a spiral 
 like a corkscrew, as it usually is in this ex- 
 
PAI 
 
 PAL 
 
 periment, be moved with a jerk the instant 
 a melted globule is about to fall, so as to 
 throw it against the side of the glass, it will 
 melt its way through in an instant, or, if the 
 jerk be less violent, lodge itself in the sub- 
 stance of the glass. If it be performed in a 
 bell glass, set in a plate filled with water, the 
 globules will frequently fuse the vitreous 
 glazing of the plate, and unite with it so as 
 not to be separable without detaching the 
 glaze, though it has passed through perhaps 
 two inches of water. 
 
 Oxygenation. This word is often used 
 instead of oxidation, and frequently con- 
 founded with it; but it differs in being of 
 more general import, as every union with 
 oxygen, whatever the product may be, is an 
 oxygenation ; but oxidation takes place only 
 when an oxide is formed. 
 
 Oxymel. A compound of honey and 
 vinegar. 
 
 * Oxymuriatic Acid. Chlorine.* 
 
 * Oxyprussic Acid. See Acid (Chloro- 
 
 FRUSSIc).* 
 
 * PAINTS. In the Philosophical Tran- 
 
 -L sactions for 1815, Sir H. Davy has 
 communicated the results of some interest- 
 ing researches, which he had made at Rome, 
 on the colours used by the ancient artists. 
 
 He found the reds to be minium, ochre, 
 and cinnabar. 
 
 The yellows were ochre, orpiment, and 
 massicot. 
 
 The blues were formed from carbonate 
 of copper, or cobalt, vitrified w r ith glass. 
 
 The purples were made of shell- fish, and 
 probably also from madder and cochineal 
 lakes. 
 
 The blacks and browns were lamp-black, 
 ivory-black, and ores of iron and manganese. 
 
 The whites were chalk, white clay, and 
 ceruse. 
 
 The Egyptian azure, the excellence of 
 which is proved by its duration for seventeen 
 hundred years, may be easily and cheaply 
 made. Sir H. Davy found, that 15 parts 
 by weight of carbonate of soda, 20 of pow- 
 dered opaque flints, and 3 of copper filings, 
 strongly heated together for two hours, gave 
 a substance of exactly the same tint, and of 
 nearly the same degree of fusibility, and 
 which when powdered, produced a fine deep 
 sky-blue. 
 
 He conceives, that next to coloured frits, 
 the most permanent pigments are those fur- 
 nished by the peroxides, or persalts, such 
 as ochres, carbonates of copper, patent yel- 
 low (subinuriate of lead), chromate of lead, 
 arsenite of copper, insoluble chloride of cop- 
 per, and sulphate of barytes. 
 
 M. Met ime has inserted a note very in- 
 teresting to painters in the Annales de Chimie 
 et Phys. for June 1820. When carbonate 
 of lead is exposed for some time to vapours 
 of sulphuretted hydrogen, it becomes black, 
 being converted into a sulphuret. This white 
 pigment, employed with oil, and covered with 
 a varnish, which screens it from the air, may 
 be preserved for many hundred years, as the 
 paintings of the 15th century prove. But 
 when the v*rnisli is abraded or decays, the 
 
 whites of ceruse are apt to contract black 
 specks and spots, which ruin fine paintings. 
 Miniatures in water colours are frequently 
 injured in this way. M. Thenard was re- 
 quested to occupy himself with the means of 
 removing these stains, without injuring the 
 rest of the picture. After some trials, which 
 proved that the reagents which would ope- 
 rate on sulphuret of lead, would equally at- 
 tack the texture of the paper, as well as other 
 colours, he recollected, that among the nume- 
 rous phenomena which his discovery of oxy- 
 genated water had presented to him, he ob- 
 served the property it possessed, of convert- 
 ing instantly the black sulphuret of lead into 
 the white sulphate of the same metal. He 
 gave a portion of water, containing about five 
 or six times its volume of oxygen, to an ar- 
 tist who had a fine picture of Raphael spot- 
 ted black. On applying a few touches of 
 his pencil, he perceived the stains vanish as 
 if by enchantment, without affecting the 
 other colours in the slightest degree.* 
 
 Palladium. This is a new metal, first 
 found by Dr Wollaston associated with plat- 
 ina, among the grains of which he supposes 
 its ore to exist, or an alloy of it with iridium 
 and osmium, scarcely distinguishable from 
 the crude platina, though it is harder and 
 heavier. 
 
 If crude platina be dissolved in nitro-mu- 
 riatic acid, and precipitated with a solution 
 of muriate of ammonia in hot water; the 
 precipitate washed, and the water added to 
 the remaining solution, and a piece of clean 
 zinc he immersed in this liquid, till no far- 
 ther action on it takes place ; the precipitate 
 now thrown down will be a black powder, 
 commonly consisting of platina. palladium, 
 iridium, rhodium, copper, and lead. The 
 lead and copper may be separated by dilute 
 nitric acid. The remainder being then di- 
 gested in nitro- muriatic acid, and common 
 salt about half the weight of the precipitate 
 added on the solution, on evaporating this to 
 dryness by a gentle heat, the result will be 
 triple salts of muriate of soda with platina. 
 
PAL 
 
 PAS 
 
 palladium, and rhodium. Alcohol will dis- 
 solve the first and second of these ; and the 
 small portion of platina may be precipitated 
 by sal ammoniac. The solution being dilut- 
 ed, and prussiate of potash added, a precipi- 
 tate will be thrown down, at first of a deep 
 orange, and afterward changing green. This 
 being dried, and heated with a little sulphur 
 before the blow-pipe, fuses into a globule, 
 from which the sulphur may be expelled by 
 exposing it to the extremity of the flame, and 
 the palladium will remain spongy and mal- 
 leable. 
 
 It may likewise be obtained by dissolving 
 an ounce of nitrate of potash in five of mu- 
 riatic acid, and in this mixture digesting the 
 compound precipitate mentioned above. Or 
 more simply by adding to a solution of crude 
 platina, a solution of prussiate of mercury, 
 on which a flocculent precipitate will gra- 
 dually be formed, of a yellowish-white co- 
 lour. This is prussiate of palladium, from 
 which the acid may be expelled by heat. 
 
 Palladium is of a greyish-white colour, 
 scarcely distinguishable from platina, and 
 takes a good polish. It is ductile and very 
 malleable ; and being reduced into thin slips 
 is flexible, but not very elastic. Its fracture 
 is fibrous, and in diverging stride, showing 
 a kind of crystalline arrangement. In hard- 
 ness it is superior to wrought iron. Its sp. 
 grav. is from 10.9 to 11.8. It is a less per- 
 fect conductor of caloric than most metals, 
 and less expansible, though in this it exceeds 
 platina. On exposure to a strong heat its 
 surface tarnishes a little, and becomes blue ; 
 but an increased heat brightens it again. It 
 is reducible per se. Its fusion requires a 
 much higher heat than that of gold; but 
 if touched while hot with a small bit of sul- 
 phur, it runs like zinc. The sulphuret is 
 whiter than the metal itself, and extremely 
 brittle. 
 
 Nitric acid soon acquires a fine red colour 
 from palladium, but the quantity it dissolves 
 is small. Nitrous acid acts on it more quick- 
 ly and powerfully. Sulphuric acid, by boil- 
 ing, acquires a similar colour, dissolving a 
 small portion. Muriatic acid acts much in 
 the same manner. Nitro-muriatic acid dis- 
 solves it rapidly, and assumes a deep red. 
 
 Alkalis and earths throw down a precipi- 
 tate from its solutions generally of a fine 
 orange colour; but it is partly redissolved 
 in an excess of alkali. Some of the neutral 
 salts, particularly those of potash, form with 
 it triple compounds, much more soluble in 
 water than those of platina, but insoluble in 
 alcohol. 
 
 Alkalis act on palladium even in the me- 
 tallic state ; the contact of air, however, pro- 
 motes their action. 
 
 A neutralized solution of palladium is pre- 
 cipitated of a dark orange or brown by re- 
 
 2 Q 
 
 cent muriate of tin : but if it be in such pro- 
 portions as to remain transparent, it is changed 
 to a beautiful emerald-green. Green sulphate 
 of iron precipitates the palladium in a metal- 
 lic state. Sulphuretted hydrogen produces a 
 dark brown precipitate ; prussiate of potash 
 an olive coloured ; and prussiate of mercury 
 a yellowish- white. As the last does not pre- 
 cipitate platina, it is an excellent test of pal- 
 ladium. This precipitate is from a neutral 
 solution in nitric acid, and detonates at about 
 500° of Fahr. in a manner similar to gun- 
 powder. Fluoric, arsenic, phosphoric, oxalic, 
 tartaric, citric, and some other acids, with 
 their salts, precipitate some of the solutions 
 of palladium. 
 
 All the metals except gold, silver, and 
 platina, precipitate it in the metallic state. 
 
 * Paste. A glass made in imitation of 
 the gems. M. Douault-Wieland has lately 
 given the following directions for making 
 them. 
 
 The base of all artificial stones, is a compound 
 of silex, potash, borax, red oxide of lead, and 
 sometimes arsenic* Pure boracic acid, and 
 colourless quartz should be used. Hessian 
 crucibles are better than those of porcelain. 
 The fusion should be continued in a potter’s 
 furnace for 24 hours ; the more tranquil and 
 continued it is, the denser the paste and the 
 greater its beauty. 
 
 Pastes , 
 
 1. 
 
 2. 
 
 5. 
 
 4. 
 
 Rock crystal, 
 
 4056 gr. 
 
 — 
 
 8456 
 
 5600 
 
 Minium, 
 
 6300 
 
 — 
 
 5328 
 
 — 
 
 Potash, 
 
 2154 
 
 1260 
 
 1944 
 
 1260 
 
 Borax, 
 
 276 
 
 360 
 
 216 
 
 360 
 
 Arsenic, 
 
 12 
 
 12 
 
 6 
 
 
 Ceruse of Clichy, 
 
 — — 
 
 8508 
 
 
 8508 
 
 Sand, 
 
 — 
 
 5600 
 
 
 __ 
 
 Topaz. 
 
 
 No. 1. No. 2. 
 
 1008 
 
 43 
 
 1 
 
 3456 
 
 Very white paste, 
 
 Glass of antimony, 
 
 Cassius purple, 
 
 Peroxide of iron (saffron of 
 
 Mars), — 36 
 
 lluby. — Paste 2880, oxide of manganese 
 72. Emerald. — Paste 4608, green oxide of 
 copper 42, oxide of chrome 2. Sapphire . — 
 Paste 4608, oxide of cobalt 68, fused for 80 
 hours. Amethyst. — Paste 4608, oxide of 
 
 manganese 36, oxide of cobalt 24, purple of 
 Cassius 1 . Beryl. — Paste 3456, glass of an- 
 timony 24, oxido of cobalt 1^. Styrian 
 Garnet , or ancient carbuncle. — Paste 512, 
 glass of antimony 2 56, Cassius purple 2, oxide 
 of manganese 2. 
 
 In all these mixtures, the substances should 
 be blended by sifting, fused very carefully, 
 and cooled very slowly, being left on the fire 
 from 24 to 30 hours. 
 
 M. Lan^on gives the following roceipcs : 
 Paste . — Litharge 100, white sand 75, 
 potash ]0. Emerald. — Paste 9216, acetate 
 of coppei 72, peroxide of iron 1.5. Amethyst, 
 
ter 
 
 PET 
 
 —Paste 9216, oxide of manganese from 15 
 to 24, oxide of cobalt 1.* 
 
 * Pearl. A highly prized spherical con- 
 cretion, which is formed within certain shell- 
 fish. It has a bluish-white colour, with con- 
 siderable lustre and iridescence. It consists 
 of alternating concentric layers of membrane 
 and carbonate of lime. To this lamellar 
 structure the iridescence is to be ascribed. 
 Pearls are of course very soluble in acids.* 
 
 * Pargasite. Common Actynolite.* 
 
 * Pearl Ash. An impure potash, obtain- 
 ed by lixiviation, from the ashes of plants.* 
 
 * Pearl Spar. Sec Brown Spar.* 
 
 * Pearlstone. A sub-species of indivi- 
 sible quartz of Jameson and Mohs. 
 
 Colour generally grey. Massive, vesicu- 
 lar, and in coarse concretions, whose surface 
 is shining and very like pearl. In the centre 
 of these concretions, spheres of obsidian 
 are frequently met with. Lustre, shining. 
 Translucent on the edges. Most easily fran- 
 gible. Soft. Sp. gr. 2.24 to 2.34. Before 
 the blow-pipe it swells, and passes into a 
 frothy glass. Its constituents are, silica 
 75.25, alumina 12, oxide of iron 1.6, potash 
 4.5, lime 0.5, water 4.5. — Klaproth. It oc- 
 curs in great beds in clay-porphyry near 
 Tokay in Hungary, and near Sandy Brae 
 in Ireland.* 
 
 * Pearl Sinter, or FiopvIte. A variety 
 of siliceous sinter. Colours white and grey. 
 In imitative shapes. Glistening ; between 
 resinous and pearly. In thin concentric 
 concretions. Translucent. Scratches glass, 
 but less hard than quartz. Brittle. Sp. gr. 
 1.917. It is infusible before the blow-pipe. 
 Its constituents are, silica 94, alumina 2, 
 lime 4. — Santi . It has been found on vol- 
 canic tuff on the V^centine. * 
 
 * Pe astone. A sub-species of limestone.* 
 
 * Pechblende. An ore of uranium.* 
 
 * Perchloric Acid. See Acid (Muri- 
 atic).* 
 
 Pericardium (Liquor of the). The 
 constituents of the liquor pericardii appear 
 to be 
 
 Water, - 92.0 
 
 Albumen, - 5.5 
 
 f The proportion 
 Mucus, - 2.0 j of these substances 
 
 Muriate of soda, 0.5 | is somewhat coll- 
 
 ie jectural. 
 
 100.0 
 
 * Peridot. Chrysolite.* 
 
 Perlate Salt and Acid. See Acid 
 (Phosphoric). 
 
 * Perlated Acid, or Ouretic. Bi- 
 phosphate of soda. * 
 
 Peru (Balsam of). This substance is 
 obtained from the myroxylon peruiferum, 
 which grows in the warm parts ot South 
 America. The tree is full of resin, and the 
 
 balsam is obtained hy boiling the twigs in 
 water. It has the consistency of honey, a 
 brown colour, an agreeable smell, and a hot 
 acrid taste. 
 
 Peruvian Bark. See Cinchona. 
 
 * Petalite. A mineral discovered in the 
 mine of Ufco in Sweden by M. D’Andrada, 
 interesting, from its analysis by M. Arfrcd- 
 son having led to the knowledge of a new 
 alkali. Externally it resembles white quartz, 
 but it has a twofold cleavage, parallel to the 
 sides of a rhomboidal prism ; two of which 
 parallel to each other are splendent, and the 
 other two are dull. Sp. gr. 2.45. On 
 minute inspection, a pinkish hue may be 
 discerned in the white colour. It scratches 
 glass, but may be rased by a knife. It is 
 scarcely fusible by the blow-pipe, acquiring 
 merely a glazed surface, full of minute bub- 
 bles. When reduced to a fine powder, it 
 appears as white as snow. Placed in nitric 
 acid, sp. gr. 1.45, it loses its white colour, 
 and changes to a dingy hue ; the acid at the 
 same time becomes clouded. The same acid, 
 somewhat dilute, dissolves it without elFer- 
 vescence, at a boiling heat. Its constituents, 
 by M. Arfredson, arc, silex 79.212, alumina 
 17.225, lithia 5.761. There is here an ex- 
 cess of 2. 1 98 above die hundred parts, which 
 M. Arfredson says, he does not know how 
 to account for. M. Vauquelin found 7 per 
 cent of lithia, in some pure specimens of 
 petalite which M. Berzelius sent him. Dr 
 Gmelin, as well as M. Arfredson, state the 
 sp. gr. at 2.42* Borax dissolves it with 
 facility. The bead is transparent and co- 
 lourless. Nitre, fused with pure petalite, 
 does not betray the presence of any man- 
 ganese ; whence we may infer that it con- 
 tains none of this metal. By Dr Gmelin’s 
 analysis, petalite is composed of, silica 74.17, 
 alumina 17.41, lithia 5.16, lime 0.32, mois- 
 ture 2.17, and loss 0.77. He could detect 
 no manganese in pure specimens. Those, 
 however, of a pale rose-red colour contain 
 it.* 
 
 Petrifactions. Stony matters deposited 
 either in the way of incrustation, or within 
 the cavities of organized substances, are call- 
 ed petrifactions. Calcareous earth being 
 universally dilfused and capable of solution 
 in water, either alone, or hy the medium of 
 carbonic acid or sulphuric acid, which are 
 likewise very abimdant, is deposited when- 
 ever the water or the acid becomes dissipated. 
 In this way we have incrustations of lime- 
 stone or of selenite in the form ot stalactites 
 or dropstones from the roots ot caverns, and 
 in various other situations. 
 
 The most remarkable observations rela- 
 tive to petrifactions are thus given by Kir- 
 wan : — 
 
 1. That those of shells are found on, or 
 near, the surface of the earth ; those ot fish 
 deeper j and those of wood deepest* Shells 
 
PHO 
 
 PHO 
 
 in specie are found in immense quantities at 
 considerable depths. 
 
 2. That those organic substances that re- 
 sist putrefaction most, are frequently found 
 petrified; such as shells and the harder 
 species of woods : on the contrary, those 
 that are aptest to putrefy are rarely found 
 petrified ; as fish, and the softer parts of ani- 
 mals, &c. 
 
 3. That they are most commonly found 
 in strata of marie, chalk, limestone, or clay, 
 seldom in sandstone, still more rarely in 
 gypsum ; but never in gneiss, granite, ba- 
 saltes, or shorle ; but they sometimes occur 
 among pyrites, and ores of iron, copper, and 
 silver, and almost always consist of that 
 species of earth, stone, or other mineral that 
 surrounds them, sometimes of silex, agate, or 
 carnelian.- 
 
 4. That they are found in climates where 
 their originals could not have existed. 
 
 5. That those found in slate or clay are 
 compressed and flattened. 
 
 * Petroleum. See Naphtha.* 
 
 * Petrosilex. Compact felspar.* 
 
 * Petuntse. Porcelain clay.* 
 
 Pewter, which is commonly called etain 
 
 in France, and generally confounded there 
 with true tin, is a compound metal, the basis 
 of which is tin. The best sort consists of 
 tin alloyed with about a twentieth, or less, of 
 copper or other metallic bodies, as the ex- 
 perience of the workmen has shewn to be 
 the most conducive to the improvement of 
 its hardness and colour, such as lead, zinc, 
 bismuth, and antimony. There are three 
 sorts of pewter, distinguished by the names 
 of plate, trifle, and ley-pewter. The first 
 was formerly much used for plates and dish- 
 es ; of the second are made the pints, quarts, 
 and other measures of beer ; and of the ley- 
 pewter, wine measures and large vessels. 
 
 The best sort of pewter consists of 1 7 
 parts of antimony to 100 parts of tin; but 
 the French add a little copper to this kind 
 of pewter. A very fine silver-looking me- 
 tal is composed of 100 pounds of tin, eight 
 of antimony, one of bismuth, and four of 
 copper. On the contrary, the ley- pewter, 
 by comparing its specific gravity with those 
 of the mixtures of tin and lead, must contain 
 more than a fifth part of its weight of lead. 
 
 * Pharmacolite. Arsenic bloom. Na- 
 tive arseniate of lime. See Ores.* 
 
 * Phosphorescence. See Light.* 
 
 * Phosphorite. A sub-species of apatite. 
 
 1 . Common phosphorite. Colour yellowish- 
 
 white. Massive and in curved lamellar con- 
 cretions. Surface drusy. Dull. Fracture 
 uneven. Opaque. Soft and rather brittle. 
 It melts with difficulty into a white colour- 
 ed glass. When rubbed in an iron mortar, 
 or thrown on red-hot coals, it emits a green 
 coloured phosphoric light. Its constituents 
 are, lime 59, phosphoric acid 34, silica 2, 
 
 fluoric acid 1, oxide of iron 1. — Pelletier. 
 It occurs in crusts in Estremadura in Spain. 
 
 2. Earthy phosphorite. Colour greyish- 
 white. It consists of dull dusty particles. 
 It phosphoresces on glowing coals. Its con- 
 stituents are, lime 47, phosphoric acid 32.25, 
 fluoric acid 2.25, silica 0.5, oxide of iron 
 0.75, water 1, mixture of quartz and loam 
 11 . 5 . — Klaproth. It occurs in a vein at 
 
 Marmarosch in Hungary. See Apatite.* 
 
 * Phosphorus. If phosphoric acid be 
 mixed with l-5th of its weight of powdered 
 charcoal, and the mixture distilled at a mo- 
 derate red- heat, in a coated earthen retort, 
 whose beak is partially immersed in a basin 
 of water, drops of a waxy looking substance 
 will pass over, and, falling into the water, 
 will concrete into the solid, called phospho- 
 rus.-}' It must be purified, by straining it, 
 through a piece of chamois leather, under 
 warm water. It is yellow and semi-transpa- 
 rent. It is as soft as wax, but fully more 
 cohesive and ductile. Its sp. gr. is 1.77. 
 It melts at 90° F. and boils at 550°. 
 
 In the atmosphere, at common tempera- 
 tures, it emits a white smoke, which, in the 
 dark, appears luminous. This smoke is 
 acidulous, and results from the slow oxygena- 
 tion of the phosphorus. In air perfectly dry, 
 however, phosphorus does not smoke, be- 
 cause the acid which is formed is solid, and, 
 closely incasing the combustible, screens it 
 from the atmospherical oxygen. 
 
 When phosphorus is heated in the air to 
 about 148°, it takes fire, and burns with a 
 splendid white light, and a copious dense 
 smoke. If the combustion take place with- 
 in a large glass receiver, the smoke becomes 
 condensed into snowy looking particles, 
 which fall in a successive shower, coating 
 the bottom plate with a spongy white efflor- 
 escence of phosphoric acid. This acid snow 
 soon liquefies by the absorption of aqueous 
 vapour from the air. 
 
 When phosphorus is inflamed in oxygen, 
 the light and heat are incomparably more 
 intense; the former dazzling the eye, and 
 the latter cracking the glass vessel. Solid 
 phosphoric acid results; consisting of 1.5 
 phosphorus -|- 2.0 oxygen. 
 
 When phosphorus is heated in highly rare- 
 fied air, three products are formed from it : 
 one is phosphoric acid ; one is a volatile white 
 powder ; and the third, is a red solid of com- 
 parative fixity, requiring a heat above that 
 of boiling water for its fusion. The volatile 
 substance is soluble in water, imparting acid 
 properties to it. It seems to be phosphorous 
 acid. The red substance is probably an 
 
 f M. Javal finds, that the bi-phosphate of lime ob- 
 tained by digesting 5 parts of calcined bone powder 
 with 2 parts of sulphuric acid, is better adapted to 
 yield phosphorus by ignition with charcoal in a retort 
 than pure phosphoric acid. The latter sublimes in a 
 great measure undecomposed, Ann, tie Chim. et 
 Physique, June 1820. 
 
PHO 
 
 PIIO 
 
 oxide of phosphorus, since for its conversion 
 into phosphoric acid, it requires less oxygen 
 than phosphorus does. See Acids (Piiosfho- 
 iuc, Phosphorous, and IIypophospiiorous.) 
 
 Phosphorus and chlorine combine with great 
 facility, when brought in contact with each 
 other at common temperatures. When chlo- 
 rine is introduced into a retort exhausted 
 of air, and containing phosphorus, tho phos- 
 phorus takes lire, and burns with a pale 
 flame, throwing off' sparks ; while a white 
 substance rises and condenses on the sides of 
 the vessel. 
 
 If the chlorine be in considerable quantity, 
 as much as 12 cubic inches to a grain of 
 phosphorus, the latter will entirely disappear, 
 and nothing but the white powder will be 
 formed, into which about 9 cubic inches of 
 the chlorine will be condensed. No new 
 gaseous matter is produced. 
 
 The powder is a compound of phosphorus 
 and chlorine, first described as a peculiar 
 body by Sir H. Davy in 1810; and various 
 analytical and synthetical experiments, which 
 he made with it, prove that it consists of 
 about 1 phosphorus, and 6.8 chlorine in 
 weight. The equivalent ratio of 1 prime of 
 the first + 2 of the second constituent, gives 
 1.5 to 9, or 1 to 6. It is the bi-chloride of 
 phosphorus. 
 
 Its properties are very peculiar. It is 
 snow-white, extremely volatile, rising in a 
 gaseous form, at a temperature much below 
 that of boiling water. Under pneumatic 
 pressure it may be fused, and then it crys- 
 tallizes in transparent prisms. 
 
 It acts violently on water, decomposing it, 
 whence result phosphoric and muriatic acids ; 
 the former from the combination of the phos- 
 phorus w'ith the oxygen, and the latter from 
 that of the chlorine with the hydrogen of 
 the water. It produces flame when exposed 
 to a lighted taper. If it be transmitted through 
 an ignited glass tube, along with oxygen, it 
 is decomposed, and phosphoric acid and 
 chlorine are obtained. The superior fixity 
 of the acid, above the chloride, seems to 
 give that ascendency of attraction to the oxy- 
 gen here, which the chlorine possesses in 
 most other cases. Dry litmus paper expos- 
 ed to its vapour in a vessel exhausted of air, 
 is reddened. When introduced into a vessel 
 containing ammonia, a combination takes 
 place, accompanied with much heat, and 
 there results a compound, insoluble in water, 
 undecomposable by acid or alkaline solutions, 
 and possessing characters analogous to earths. 
 
 2. The protochloride of phosphorus was 
 first obtained in a pure state, by Sir H. 
 Davy in the year 1809. If phosphorus be 
 sublimed through corrosive sublimate, in 
 powder in a glass tube, a limpid fluid comes 
 over, as clear as water, and having a specific 
 gravity of 1.45. It emits acid fumes when 
 
 exposed to the air, bv decomposing the aque- 
 
 20 
 
 oils vapour. If paper imbued with it, be 
 exposed to the air, it becomes acid without 
 inflammation. It does not redden dry lit- 
 mus paper plunged into it. Its vapour 
 burns in the flame of a candle. When 
 mixed with water, and heated, muriatic acid 
 flies off, and phosphorous acid remains. See 
 Acid (Phosphorous). If it be introduced 
 into a vessel containing chlorine, it is con- 
 verted into the hi -chloride ; and if made to 
 act upon ammonia, phosphorus is produced, 
 and the same earthy-like compound results, 
 as that formed by the bi-chloride and ammo- 
 nia. 
 
 When phosphorus is gently heated in the 
 protocldoride, a part of it dissolves, and the 
 fluid, on exposure to air, gives off acid fumes, 
 from its action on atmospheric moisture, while 
 a thin film of phosphorus is left behind, 
 which usually inflames by the heat gene- 
 rated from the decomposition of the vapour. 
 The first compound of this kind was obtain- 
 ed by MM. Gay Lussac and Thenard, by 
 distilling phosphorus and calomel together, 
 in 1 808 ; and they imagined it to be a pecu- 
 liar combination of phosphorus, oxygen, 
 and muriatic acid. No experiments have 
 yet ascertained the quantity of phosphorus 
 which the protochloride will dissolve. Pro- 
 bably, says Sir H. Davy, a definite combi- 
 nation may be obtained, in which the pro- 
 portion of chlorine will correspond to the 
 proportion of oxygen in the oxide of phos- 
 phorus. The subchloride would consist of 
 3 phosphorus 4.5 chlorine ; or of 2 -}- 3. 
 
 The compounds of iodine and phosphorus 
 have been examined by Sir H. Davy, and 
 M. Gay Lussac. 
 
 Phosphorus unites to iodine with the dis- 
 engagement of heat, but no light. One 
 part of phosphorus and eight of iodine form 
 a compound of a red orange-brown colour, 
 fusible at about 212°, and volatile at a higher 
 temperature. When brought in contact 
 with water, phosphuretted hydrogen gas is 
 disengaged, flocks of phosphorus are preci- 
 pitated, and the water, which is colourless, 
 contains, in solution, phosphorous and hydri- 
 odic acids. 
 
 One part of phosphorus and 16 of iodine, 
 produce a crystalline matter of a greyish- 
 black colour, fusible at 84°. The hydriodic 
 acid produced by bringing it in contact with 
 water, is colourless, and no phosphuretted 
 hydrogen gas is disengaged. 
 
 One part of phosphorus, and 24 of iodine, 
 produce a black substance partially fusible 
 at 115°. Water dissolves it, producing a 
 strong heat, and the solution has a very deep 
 brown colour, which is not removed by keep- 
 ing it, for some time, in a gentle heat. M ith 
 1 phosphorus and 4 iodine, two compounds, 
 very different from each otlrcr, are obtained. 
 One of them has the same colour as that 
 formed of 1 phosphorus 8 iodine, and 
 
PHO 
 
 PIIO 
 
 seems to be the same with it. It melts at 
 217.5°, and when dissolved in water, yields 
 colourless hydriodic acid, phosphuretted hy- 
 drogen, and phosphorus, which last precipi- 
 tates in orange-yellow flocks. The other 
 compound is reddish-brown, does not melt 
 at 212°, nor at a considerably higher tem- 
 perature. Water has no sensible action on 
 it. Potash dissolves it with the disengage- 
 ment of phosphuretted hydrogen gas ; and 
 when aqueous chlorine is poured into the 
 solution, it shews only traces of iodine. 
 When heated in the open air, it takes fire 
 and burns like pliosphorus, emitting white 
 vapours, without any iodine. When these 
 vapours were condensed in a glass jar, by 
 JVI. Gay Lussac, he could perceive no iodine 
 among them. This red substance is always 
 obtained, when the phosphorus is in the pro- 
 portion of 1 to 4 of iodine. M. Gay Lus- 
 sac is inclined to consider it as identical 
 with the red matter, which phosphorus so 
 often furnishes, and which is at present con- 
 sidered as an oxide. In whatever propor- 
 tions the iodide of phosphorus has been 
 made, it exhales, as soon as it is moistened,' 
 acid vapours, owing to the hydriodic acid 
 formed by the decomposition of the water. 
 
 Such is the account of the iodides of phos- 
 phorus given by M. Gay Lussac. The 
 combining ratios by theory are, for the 
 
 Subiodide, 3.0 ) , , r 
 
 i i 1 4- 1 5.5 iodine, or 1 4- 5. 1 6 
 
 phosphorus, } » * • 
 
 Protiodide, 1.5 + 15.5 1 + 10.33 
 
 Deutiodide, 1.5 31.0 i + 20.6(5 
 
 Phosphuretted hydrogen . Of this com- 
 pound there are two varieties ; one consist- 
 ing of a prime of each constituent, and 
 therefore to be called phosphuretted hydro- 
 gen ; another, in which the relation of phos- 
 phorus is one-half less, to he called there- 
 fore subphosphu retted hydrogen. 
 
 1. Phosphuretted hydrogen. Into a small 
 retort tilled with milk of lime, or potash- 
 water, let some fragments of phosphorus be in- 
 troduced, and let the heat of an Argand flame 
 Ire applied to the bottom of the retort, while 
 its beak is immersed in the water of a pneu- 
 matic trough. Bubbles of gas will come 
 over, which explode spontaneously with con- 
 tact of air. It may also be procured by the 
 action of dilute muriatic acid on phosphu- 
 ret of lime. In order to obtain the gas pure, 
 however, wc must receive it over mercury. 
 Its smell is very disagreeable. Its sp. grav. 
 is 0.9022. 100 cubic inches weigh 27.5 gr. 
 
 In oxygen, it inflames with a brilliant white 
 light. In common air, when the gaseous 
 bubble bursts the Him of water, and explodes, 
 there rises up a ring of white smoke, lumi- 
 nous in the dark. Water absorbs about 
 l-40th of its bulk of this gas, and acquires a 
 yellow colour, a bitter taste, and the charac- 
 teristic smell of the gas. When brought in 
 
 contact with chlorine it detonates with a 
 brilliant green light ; but the products have 
 never been particularly examined. 
 
 By transmitting a series of electric explo- 
 sions, through phosphuretted hydrogen, the 
 phosphorus is precipitated, and hydrogen o. 
 the original gaseous volume remains. Ilcnce 
 the composition of the gas may be deduced, 
 from a comparison of its specific gravity 
 with that of hydrogen. 
 
 Phosphuretted hydrogen, 0.9022 
 Hydrogen, 0.0694 
 
 Fhos. = difference of weight, 0.8328 
 Thus we perceive, that this compound 
 consists of 0.8328 phosphorus -j- 0.0694 
 hydrogen ; or 1 2 -}- I ; or 1.5 —J— 0.125 = 
 1.625, which is the weight of the sum ol the 
 primes, commonly called the weight of its 
 atom. The gas may be likewise conve- 
 niently analyzed by nitrous gas, nitrous oxide, 
 or oxygen. 
 
 2. Subphosphurcttcd hydrogen. It was 
 discovered by Sir H. Davy in 1812. When 
 the crystalline hydrate of phosphorous acid 
 is heated in a retort, out of the contact of 
 air, solid phosphoric acid is formed, and a 
 large quantity of subphosphuretted hydrogen 
 is evolved. Its smell is fetid, but not so dis- 
 agreeably so as that of the preceding gas. 
 It does not spontaneously explode like it, 
 with oxygen ; but at a temperature of 500°, 
 a violent detonation takes place. In chlorine 
 it explodes with a white flame. Water ab- 
 sorbs ~ of its volume of this gas. When 
 potassium is heated in it, its volume is 
 doubled, and the resulting gas is pure hydro- 
 gen. When sulphur is sublimed in I vo- 
 lume of it, a sulphuret of phosphorus is 
 formed, and nearly 2 volumes of sulphuret- 
 ted hydrogen are produced. Now as the den- 
 sity of vapour of phosphorus is 0.833, as ap- 
 pears both from the above analysis of phos- 
 phuretted hydrogen, and as also may be infer- 
 red from Sir H. Davy’s equivalent prime of 
 phosphorus, (see Acid, Phosphoric), thepre- 
 sent gaseous compound results evidently from 
 
 2 volumes of hy > 0 . 0694 x 2 = 0 . 1 388 
 
 drogen, ) ^ 
 
 And 1 volume*) 
 
 of vapour of > = 0.8333 
 
 phosphorus, J . 
 
 0.9721 
 
 which occupy only one volume ; whence the 
 specific gravity of this gas is 0.9721 ; and it 
 consists of 2 primes of hydrogen = 0. 25 -j- 
 one of phosphorus = 1.5= 1.75 ; being the 
 same weight with the prime of azote. 
 
 It is probable that phosphuretted hydrogen 
 gas sometimes contains the subphosphuret 
 and common hydrogen mixed with it. 
 
 “ There is not, perhaps,” says Sir H. 
 Davy, “ in the whole series of chemical 
 phenomena, a more beautiful illustration of 
 
PHY 
 
 PIC 
 
 the theory of definite proportions, than that 
 offered in the decomposition of hydrophos- 
 phorous acid into phosphoric acid, and hy- 
 drophosphoric gas. 
 
 “ 1'our proportions of the acid, contain four 
 proportions of phosphorus and four of oxy- 
 gen ; two proportions of water, contain four 
 proportions of hydrogen and two of oxygen, 
 (all by volume). The six proportions of 
 oxygen unite to three proportions of phos- 
 phorus to form three of phosphoric acid, and 
 the four proportions of hydrogen combine with 
 one of phosphorus to form one proportion of 
 hydrophosphoric gas ; and there are no other 
 products.” — Elements , p. 297. The reader 
 will observe, that his hydrophosphoric gas, is 
 our subphosphuretted hydrogen. 
 
 Phosphorus and sulphur are capable of 
 combining. They may be united by melt- 
 ing them together in a tube exhausted of air, 
 or under water. In this last case, they must 
 be used in small quantities; as, at the mo- 
 ment of their action, water is decomposed, 
 sometimes with explosions. They unite in 
 many proportions. The most fusible com- 
 pound is that of one and a half of sulphur to 
 two of phosphorus. This remains liquid at 
 40° Fahrenheit. When solid its colour is 
 yellowish- white. It is more combustible 
 than phosphorus, and distils undecompound- 
 ed at a strong heat. Had it consisted of 2 
 sulphur -j- 3 phosphorus, we should have 
 had a definite compound of 1 prime of the 
 first + 2 of the second constituent. This 
 proportion forms the best composition for 
 phosphoric fire-matches or bottles. A par- 
 ticle of it attached to a brimstone match, 
 inflames when gently rubbed against a sur- 
 face of cork or wood. An oxide made by 
 heating phosphorus in a narrow mouthed 
 phial with an ignited wire, answers the same 
 purpose. The phial must be kept closely 
 corked, otherwise phosphorous acid is spee- 
 dily formed. 
 
 Phosphorus is soluble in oils, and com- 
 municates to them the property of appearing 
 luminous in the dark. Alcohol and ether 
 also dissolve it, but more sparingly. 
 
 When sw allowed in the quantity of a grain, 
 it acts as a poison. Azote dissolves a little 
 of it, and has its volume enlarged by about 
 l-40tb. See Eudiometer.* 
 
 * Phosphorus (of Baldwin). Ignited mu- 
 riate of lime.* 
 
 * Phosphorus (of Canton). Oyster shells 
 calcined with sulphur.* 
 
 * Phosphorus (of Bologna). See Light. 
 Sulphate of barytes.* 
 
 * Phosphuket. A compound of phos- 
 phorus, with a combustible or metallic oxide.* 
 
 Phlogisticated Air. See Nitrogen. 
 
 Phlogisticated Alkali. Ferroprussiate 
 of potash. Sec Acid (Prussic). 
 
 * Phlogiston. See Combustion.* 
 
 * Phvsalite, or Pyrophysalite. Colour 
 
 greenish-white. Massive. In granular con- 
 cretions. Splendent in the cleavage, which 
 is perfect, and as in topaz. Fracture un- 
 even. Translucent on the edges. As hard 
 as topaz. Sp. gr. 3.451. It whitens with 
 the blow-pipe. Its constituents are, alumina 
 57.74, silica 34.36, fluoric acid 7.77. It is 
 found in granite at Finbo, in Sweden. It is 
 a sub-species of prismatic topaz. — Jameson .* 
 
 * Picromel. The characteristic principle 
 of bile. If sulphuric acid, diluted with five 
 parts of w r ater, be mixed with fresh bile, a 
 yellow precipitate will fall. Heat the mixture, 
 then leave it in repose, and decant oft' tho 
 clear part. What remains was formerly call- 
 ed resin of bile, but it is a greenish com- 
 pound of sulphuric acid and picromel. Edul- 
 corate it with water, and digest with carbo- 
 nate of barytes. The picromel now liberat- 
 ed will dissolve in the water. On evaporat- 
 ing 4 this solution, it is obtained in a solid 
 state. Or by dissolving the green sulphate 
 in alcohol, and digesting the solution over 
 carbonate of potash till it cease to redden 
 litmus paper, we obtain the picromel com- 
 bined with alcohol. 
 
 It resembles inspissated bile. Its colour 
 is greenish-yellow ; its taste is intensely bit- 
 ter at first, with a succeeding impression of 
 sweetness. It is not affected by infusion of 
 galls, but the salts of iron and subacetate of 
 lead precipitate it from its aqueous solution. 
 It affords no ammonia by its destructive dis- 
 tillation. Hence, the absence of azote is in- 
 ferred, and the peculiarity of picromel.* 
 
 * Picrotoxia. The bitter and poisonous 
 principle of cocculus indicus , the fruit of the 
 menispermum coccidus . To the filtered de- 
 coction of these berries, add acetate of lead, 
 while any precipitate falls. Filter and eva- 
 porate the liquid cautiously, to the consist- 
 ence of an extract. Dissolve in alcohol of 
 0.817, and evaporate the solution to dryness. 
 By repeating the solutions and evaporations, 
 we at last obtain a substance equally soluble 
 in water and alcohol. The colouring matter 
 may be removed by agitating it with a little 
 w ater. Crystals of pure picrotoxia now fall, 
 which may be washed with a little alcohol. 
 
 The crystals are four-sided prisms, of a 
 white colour, and intensely bitter taste. They 
 are soluble in 25 times their weight of water, 
 and are not precipitable by any known re- 
 agent. Alcohol, sp. gr. 0.810, dissolves one- 
 third of its weight of picrotoxia. Pure sul- 
 phuric ether dissolves 2-5ths of its weight. 
 
 Strong sulphuric acid dissolves it, but not 
 when much diluted. Nitric acid converts it 
 into oxalic acid. It dissolves and neutralizes 
 in acetic acid, and falls when this is saturated 
 with an alkali. It may therefore be regard- 
 ed as a vegeto- alkali itself. Aqueous potash 
 dissolves it, without evolving any smell of 
 ammonia. It acts as an intoxicating poison. 
 
 Sulphate of picrotoxia must be formed by 
 
PIC 
 
 PLA 
 
 dissolving picrotoxia in dilute sulphuric acid, 
 for the strong acid chars and destroys it. 
 The solution crystallizes on cooling. The 
 sulphate of picrotoxia dissolves in 120 times 
 its weight of boiling water. The solution 
 gradually lets fall the salt in fine silky fila- 
 ments disposed in bundles, and possessed of 
 great beauty. When dry, it has a white co- 
 lour, and feels elastic under the teeth, like 
 plumose alum. It is composed of 
 
 Sulphuric acid, 9.99 5 
 
 Picrotoxia, - 90.01 45 
 
 100.00 
 
 Nitrate of picrotoxia. Nitric acid, of the 
 specific gravity 1.J8, diluted with twice its 
 weight of water, dissolves, when assisted by 
 heat, the fourth of its weight of picrotoxia. 
 When this solution is evaporated to one-half, 
 it becomes viscid, and on cooling, is convert- 
 ed into a transparent mass, similar to a solu- 
 tion of gum-arabic. In this state the nitrate 
 of picrotoxia is acid, and exceedingly bitter. 
 If it be still further dried in a temperature 
 not exceeding 140°, it swells up, becomes 
 opaque, and grows at last perfectly white 
 and light, like calcined alum. If we keep it 
 in this state, at a temperature below that of 
 boiling water, adding a little water occa- 
 sionally, the whole excess of acid exhales, 
 and the taste becomes purely bitter. When 
 this salt is washed in pure water, the acid is 
 totally removed, and the picrotoxia is sepa- 
 rated in the state of fine white plates. 
 
 Muriate of picrotoxia . Muriatic acid, of 
 
 the specific gravity 1.145, has little action on 
 picrotoxia. It dissolves it when assisted by 
 heat, but does not become entirely saturated. 
 Five parts of this acid, diluted with three 
 times its weight of water, dissolve about one 
 part of picrotoxia at a strong boiling tempe- 
 rature. The liquor, on cooling, is converted 
 into a greyish crystalline mass, composed of 
 confused crystals. When these crystals are 
 well washed, they are almost destitute of 
 taste, and feel elastic under the teeth. They 
 dissolve in about 400 times their weight of 
 boiling water ; but are almost entirely de- 
 posited on cooling. The solubility is much 
 increased by the presence of an excess of 
 acid. 
 
 Acetate of picrotoxia. Acetic acid dis- 
 solves picrotoxia very well, and may be nearly 
 saturated with it by the assistance of a boil- 
 ing heat. On cooling, the acetate precipi- 
 tates in well-defined prismatic needles. This 
 acetate is soluble in 50 times its weiVht of 
 
 o 
 
 boiling water. On cooling, it forms crystals 
 of great beauty, light, without any acid 
 smell, and much less bitter than picrotoxia 
 itself. It is decomposed by nitric acid, which 
 disengages the acetic acid. Dilute sulphu- 
 ric acid has no marked actiou on it. It is 
 not so poisonous as pure picrotoxia. — Boul- 
 lay. Ann. dc ChimicA 
 
 * Pimelite* A variety of steatite, found 
 at Kosemutz, in Silesia.* 
 
 * Pinchbeck. An alloy of copper, in 
 which the proportion of zinc is greater than 
 in brass.* 
 
 * Pineal Concretions. Matter of a 
 stony consistence is sometimes deposited in 
 the substance cf the pineal gland, formerly 
 reckoned, from its position in the centre of the 
 brain, to be the seat of the soul, the intellectual 
 sanctuary. These concretions were proved 
 by Dr Wollaston to be phosphate of lime.* 
 
 * Pinite. Micarelle of Kirwan. Colour 
 blackish -green. Massive, in lamellar con- 
 cretions, and crystallized in an equiangular 
 six-sided prism ; in the same figure truncat- 
 ed or bevelled, and in a rectangular four- 
 sided prism. Cleavage shining; lustre re- 
 sinous. Fracture uneven. Opaque. Soft. 
 Sectile ; frangible, and not flexible. Feels 
 somewhat greasy. Sp. gr. 2.95. Infusible. 
 Its constituents are, silica 29.5, alumina 
 63.75, oxide of iron 6.75. — Klaproth. It is 
 found in the granite of St Michael’s Mount, 
 Cornwall ; and in porphyry in Glen- Gloe 
 and Blair- Gowrie.* 
 
 * Pistacite. See Epidote.* 
 
 * Pitch. See Bitumen.* 
 
 * Pitch Coal. See Coal.* 
 
 * Pitch Ore. See Ores of uranium.* 
 
 * Pitchstone. A sub-spccies of indivisi- 
 ble quartz. Colour green. Massive. Vitreo- 
 resinous lustre. Feebly transparent on the 
 edges. Fracture conchoidal. Semi-hard in 
 a high degree. Rather easily frangible. Sp. 
 gr. 2.2 to 2.S. It is fusible before the blow- 
 pipe. Its constituents are, silica 73, alu- 
 mina 14.5, lime 1, oxide of iron 1, oxide of 
 manganese 0.1, natron 1.75, water 8.5. — 
 Klaproth. It occurs in veins that traverse 
 granite. It is found in Arran, in Mull, 
 Canna, Skye, and in the Towmland of 
 Newry, where it was first observed by Mr 
 Joy of Dublin.* 
 
 * Pitcoal. See Co A Li* 
 
 * Plants. See Vegetable Kingdom.* 
 
 * Plasma. Colour between crass-green 
 and leek-green. In angular pieces. Glis- 
 tening. Fracture conchoidal. Translucent. 
 Hard. Brittle. Sp. gr. 2.553. Infusible. 
 Its constituents are, silica 96.75, alumina 
 0.25, iron 0.5, loss 2.5. — Klaproth. It oc- 
 curs in beds associated with common calce- 
 dony. It is found also among the ruins of 
 Rome.* 
 
 * Plaster of Paris. Gypsum.* 
 
 Platina is one of the metals for the dis- 
 covery of which we are indebted to our 
 contemporaries. Its ore has recently been 
 found to contain, likewise, four new metals, 
 palladium, iridium, osmium, and rhodium ; 
 which see ; beside iron and chrome. 
 
 The crude platina is to be dissolved in 
 nitro-muriatic acid, precipitated by muriate 
 of ammonia, and exposed to a very violent 
 
PLA 
 
 PLA 
 
 beat. Then the acid and alkali are expelled, 
 and the metal reduced in an agglutinated 
 state, which is rendered more compact by 
 pressure while red-hot. 
 
 Pure or refined platina is by much the 
 heaviest body in nature. Its sp. gr. is 21.5. 
 It is very malleable, though considerably 
 harder than either gold or silver; and it 
 hardens much under the hammer. Its co- 
 lour on the touch-stone is not distinguish- 
 able from that of silver. Pure platina re- 
 quires a very strong heat to melt it ; but 
 when urged by a white heat, its parts will 
 adhere together by hammering. This pro- 
 perty, which is distinguished by the name 
 of welding, is peculiar to platina and iron, 
 which resemble each other likewise in their 
 infusibility. 
 
 Platina is not altered by exposure to air; 
 neither is it acted upon by the most concen- 
 trated simple acids, even when boiling, or 
 distilled from it. 
 
 The aqua regia best adapted to the solu- 
 tion of platina, is composed of one part of 
 the nitric and three of the muriatic acid. 
 The solution does not take place with ra- 
 pidity. A small quantity of nitric oxide is 
 disengaged, the colour of the fluid becoming 
 first yellow, and afterward of a deep reddish- 
 brown, which, upon dilution with water, is 
 found to be an intense yellow. This solu- 
 tion is very corrosive, and tinges animal mat- 
 ters of a blackisli-brown colour ; it affords 
 crystals by evaporation. 
 
 Count Moussin Poushkin has given the 
 following method of preparing malleable 
 platina : 
 
 Precipitate the platina from its solution 
 by muriate of ammonia, and wash the preci- 
 pitate with a little cold water. Reduce it 
 in a convenient crucible to the well-known 
 spongy metallic texture, which wash two 
 or three times with boiling water, to carry 
 off any portion of saline matter that may 
 have escaped the action of the fire. Boil 
 it for about half an hour, in as much water 
 mixed with one-tenth part of muriatic acid 
 as will cover the mass to the depth of about 
 half an inch, in a convenient glass vessel. 
 This will carry off any quantity of iron that 
 might still exist in the metal. Decant the 
 acid water, and edulcorate, or strongly ignite 
 the platina. 
 
 To one part of this metal take two parts 
 of mercury, and amalgamate in a glass or 
 porphyry mortar. This amalgamation takes 
 place very readily. The proper method of 
 conducting: it is to take about two drachms 
 of mercury to three drachms of platina, and 
 amalgamate them together ; and to this amal- 
 gam may he added alternate small quantities 
 of platina and mercury, till the whole of the 
 two metals is combined. Several pounds 
 may be thus amalgamated in a few hours, 
 
 and in the large way a proper mill might 
 shorten the operation. 
 
 As soon as the amalgam of mercury is 
 made, compress it in tubes of wood, by the 
 pressure of an iron screw upon a cylinder 
 of wood adapted to the bore of the tube. 
 This forces the superabundant mercury from 
 the amalgam, and renders it solid. After 
 two or three hours, burn upon the coals, or 
 in a crucible lined with charcoal, the sheath 
 m which the amalgam is contained, and 
 urge the fire to a white-heat ; after which 
 the platina may be taken out in a very solid 
 state, fit to be forged. 
 
 Muriate of tin is so delicate a test of pla- 
 tina, that a single drop of the recent solution 
 of tin in muriatic acid gives a bright red 
 colour to a solution of muriate of platina, 
 scarcely distinguishable from water. 
 
 If the muriatic solution of platina be agi- 
 tated with ether, the ether will become im- 
 pregnated with the metal. This ethereal 
 solution is of a fine pale yellow, does not 
 stain the skin, and is precipitable by ammo- 
 nia. 
 
 If the nitro-muriatic solution of platina 
 be precipitated by lime, and the precipitate 
 digested in sulphuric acid, a sulphate of pla- 
 tina will be formed. A subnitrate may be 
 formed in the same manner. According to 
 M. Chenevix, the insoluble sulphate contains 
 54.5 oxide of platina, and 45.5 acid and 
 water ; the insoluble muriate, 70 of oxide ; 
 and the subnitrate, 89 of oxide ; but the 
 purity of the oxide of platina in these is un- 
 certain. 
 
 Platina does not combine with sulphur 
 directly, but is soluble by the alkaline sul- 
 phurets, and precipitated from its nitro-mu- 
 riatic solution by sulphuretted hydrogen. 
 
 Pelletier united it with phosphorus, by 
 projecting small bits of phosphorus on the 
 metal heated to redness in a crucible ; or 
 exposing to a strong heat four parts each of 
 platina and concrete phosphoric acid with 
 one of charcoal powder. The phosphuret 
 of platina is of a silvery- white, very brittle, 
 and hard enough to strike fire with steel. 
 It is more fusible than the metal itself, and 
 a strong heat expels the phosphorus, whence 
 Pelletier attempted to obtain pure platina 
 in this way. He found, however, that the 
 last portions of phosphorus were expelled 
 with too much difficulty. 
 
 Platina unites with most other metals. 
 Added in the proportion of one-twelfth to 
 gold, it forms a yellowish- white metal, high- 
 ly ductile, and tolerably elastic, so that Mr 
 Hatchett supposed it might be used with 
 advantage for watch-springs, and other pur- 
 poses. Its specific gravity was 19.013. 
 
 Platina renders silver more hard, but its 
 colour more dull. 
 
 Copper is much improved by alloying 
 
rLA 
 
 PLA 
 
 with platina. From l-6th to l-25th, or 
 even less, renders it of a golden colour, 
 harder, susceptible of a finer polish, smooth- 
 grained, and much less liable to rust. 
 
 Alloys of platina with tin and lead are 
 very apt to tarnish. See Iron. 
 
 From its hardness, infusihility, and diffi- 
 culty of being acted upon by most agents, 
 platina is of great value for making various 
 chemical vessels. These have, it is true, the 
 inconvenience of being liable to erosion 
 from the caustic alkalis and some of the 
 neutral salts. 
 
 * Platinum is now hammered in Paris 
 into leaves of extreme thinness. I5y enclos- 
 ing a wire of it in a little tube of silver, and 
 drawing this through a steel plate in the 
 usual way, Dr Wollaston has succeeded in 
 producing platinum wire not exceeding 
 1 -3000th of an inch in diameter. 
 
 For some curious phenomena of its fu- 
 sion, see Blow- pipe. There are two oxides 
 
 of platinum : — 
 
 1. The protoxide may be obtained by 
 pouring a solution of neutral nitrate of 
 mercury into a dilute solution of muriate of 
 platinum. A dark brown or olive-green 
 powder falls, which is a compound of calo- 
 mel and the protoxide of platinum. It 
 must be well washed, and then gently heated 
 so as to dissipate the mercurial salt. The 
 pure black protoxide now remains. 100 
 grains of it, at a red-heat, emit 12^ cubic 
 inches of oxygen, and become metallic pla- 
 tinum. With enamellers’ flux it may be 
 ignited without reduction. This important 
 fact, as well as the discovery of this oxide 
 itself, is due to Mr Cooper. It would thus 
 appear that protoxide of platinum consists of 
 
 Platinum, 100.000 22.625 
 
 Oxygen, 4.423 1.000 
 
 2. The peroxide appears to contain three 
 prime proportions. Berzelius obtained it by 
 treating the muriate of platinum with sul- 
 phuric acid, at a distilling heat, and decom- 
 posing the sulphate by aqueous potash. The 
 precipitated oxide is a yellowish-brown pow- 
 der, easily reducible by a red-heat to the 
 metallic state. 
 
 According to Mr E. Davy, the proto- 
 chloride is soluble in water ; while the bi- 
 chloride is insoluble. If the common nitro- 
 muriatic solution he cautiously dried, and 
 heated to didl redness, washed with water, 
 and again dried, we obtain the bi-chloride, 
 apparently consisting of 
 
 Platinum, 100, or 1 prime 23.73 
 Chlorine, 37.93 2 9.00 
 
 It lias a dull olive-brown or green colour ; 
 a harsh feel ; and is destitute of taste and 
 smell. It is not fusible by heat; nor is it 
 altered by exposure to the atmosphere. At 
 a full red-heat the chlorine flics off, and pla- 
 tinum remains. 
 
 According to Mr E. Davy, there are two 
 pliosphurets and three sulphurets of plati- 
 num. See his excellent memoir in the 
 Phil. Mag. vol. xl. 
 
 The salts of platinum have the following 
 general characters : — 
 
 1. Their solution in water is yellowish- 
 brown. 
 
 2. Potash and ammonia determino the 
 formation of small orange- coloured crystals. 
 
 3. Sulphuretted hydrogen throws down 
 the metal in a black powder. 
 
 Ferroprussiate of potash, and infusion of 
 galls, occasion no precipitate. 
 
 1. The sulphate of platinum may be ob- 
 tained by passing a current of sulphuretted 
 hydrogen gas through the nitro-muriatic so- 
 lution. It should he washed and boiled 
 once or twice with nitric acid, to ensure its 
 entire conversion into sulphate. It has a 
 brownish-black colour, and resembles the 
 carbonaceous crust left when sugar is de- 
 composed by heat. It is brittle, easily pul- 
 verized, and has the lustre nearly of crystal- 
 lized blende. Its taste is acid, metallic, and 
 somewhat caustic. It reddens litmus paper 
 slightly. It is deliquescent, and soluble in 
 water, alcohol, and ether, as w ell as in muri- 
 atic, nitric, and phosphoric acids. At a red- 
 heat it is resolved into metal. It appears 
 from Mr Davy’s analysis to consist of 
 
 Theory. 
 
 Sulphuric acid, 26.3 27.58 
 
 Protoxide of platinum, 73.7 72.42 
 
 This near coincidence is a verification 
 of the analysis. A sulphate of potash and 
 platinum is formed by neutralizing the sul- 
 phate with a solution of potash, and expos- 
 ing the mixture for a little to a boiling heat. 
 A granular substance resembling gunpowder 
 is obtained. It is tasteless, insoluble in wa- 
 ter, and possesses the lustre of blende. A 
 soda- sulphate may be formed by a similar 
 process ; as also an ammonia-sulphate. 
 
 Fulminating platinum has been lately dis- 
 covered by Mr Edmund Davy. Into a so* 
 lution of the sulphate in water, aqueous am- 
 monia is poured, and the precipitate which 
 falls, being washed, is put into a matrass 
 with potash-lev, and boiled for some time. 
 It is then filtered, washed, and dried. A 
 brown powder is obtained, lighter than ful- 
 minating gold, which is the fulminating 
 platinum. It explodes violently when heat- 
 ed to 400° ; but does not detonate by fric- 
 tion or percussion. It is a non-conductor 
 of electricity. With sulphuric acid it forms 
 a deep coloured solution. Chlorine and 
 muriatic acid gas decompose it. According 
 to Mr E. Davy, it consists of 
 
 Nearly 
 
 Peroxide of platinum, 82.5 2 primes 
 
 Ammonia, 9.0 1 
 
 *VV ater, 8.5 
 
 f> 
 
POI 
 
 POI 
 
 An important paper of "Mr Davy’a on 
 platinum has been recently read at the lloyal 
 Society, the details of which are not yet 
 published.* 
 
 * Platinum Ore. See Ores of Pla- 
 tinum.* 
 
 * Pleonaste. Ceylanite.* 
 
 * Plumbago. See Graphite.* 
 
 * Poisons. Substances which, when ap- 
 plied to living bodies, derange the vital 
 functions, and produce death, by an action 
 not mechanical. The study of their nature, 
 mode of operation, and antidotes, has been 
 called toxicology. Poisons have been arrang- 
 ed into six classes : 
 
 I* — Corrosive , or escharotic poisons. 
 
 They are so named because they usually 
 irritate, inflame, and corrode the animal 
 texture with which they come into contact. 
 Their action is in general more violent and 
 formidable than that of the other poisons. 
 The following list from Orfila contains the 
 principal bodies of this class : — 
 
 1 . Mercurial preparations ; corrosive sub- 
 limate, red oxide of mercury ; turbeth mi- 
 neral, or yellow subsulphate of mercury ; 
 pernitrate of mercury ; mercurial vapours. 
 
 2. Arsenical preparations ; such as white 
 oxide of arsenic, and its combinations with 
 the bases, called arsenites ; arsenic acid, 
 and the arseniates ; yellow and red sulphu- 
 ret of arsenic ; black oxide of arsenic, or 
 fly-powder. 
 
 3. Antimonial preparations ; such as tar- 
 tar emetic, or cream-tartrate of antimony ; 
 oxide of antimony ; kermes mineral ; mu- 
 riate of antimony ; and antimonial wine. 
 
 4. Cupreous preparations ; such as verdi- 
 gris ; acetate of copper ; the cupreous sul- 
 phate, nitrate, and muriate ; ammoniacal 
 copper ; oxide of copper ; cupreous soaps, 
 or grease tainted with oxide of copper ; and 
 cupreous wines or vinegars. 
 
 5. Muriate of tin. 
 
 6. Oxide and sulphate of zinc. 
 
 7. Nit rate of silver. 
 
 8. Muriate of gold. 
 
 9. Pearl-white , or the oxide of bismuth, 
 and the subnitrate of this metal. 
 
 10. Concentrated acids ; sulphuric, nitric, 
 phosphoric, muriatic, hydriodic, acetic, Sec. 
 
 1 1 . Corrosive alkalis , pure or subcarbonat- 
 ed potash, soda, and ammonia. 
 
 12. The caustic earths , lime and barytes. 
 
 1 3. Muriate and carbonate of barytes. 
 
 1 4. Glass and enamel powder . 
 
 1 5. Cantharides. 
 
 1 1. — Astringent poisons. 
 
 1. Preparations of lead, such as the ace- 
 tate, carbonate, wines sweetened with lead, 
 water impregnated with its oxide, food 
 cooked in vessels containing lead, syrups 
 clarified with subacetate of lead, plumbean 
 vapours. 
 
 III. — Acrid poisons. 
 
 1. The gases; chlorine, muriatic acid, 
 sulphurous acid, nitrous gas, and nitro-mu- 
 riatic vapours. 
 
 2. Jatropha manihot, the fresh root, and 
 its juice, from which cassava is made. 
 
 3. The Indian ricinus, or Molucca wood. 
 
 4. Scammony. 5. Gamboge. 6 . Seeds 
 of palma Christi. ?. Elaterium. 8. Colo- 
 cynth. 9. White hellebore root. 10. Black 
 hellebore root. 1 1 . Seeds of stavesacre. 
 12. The wood and fruit of the ahov'di of 
 Brazil. 1 3. Rhododendron chrysanthum. 
 14, Bulbs of colchicum, gathered in summer 
 and autumn. 15. The milky juice of the 
 convolvulus arvensis. 16. Asclepias. 17. 
 (Enanthe fistuiosa and crocata. 18. Some 
 species of clematis. 19. Anemone pulsa- 
 tilla. 20. Root of Wolf ’s- bane. 21. Fresh 
 roots of Arum maculatum. 22. Berries 
 and hark of Daphne Mezereum. 23. The 
 plant and emanations of the rhus toxico- 
 dendron. 24. Euphorbia Officinalis. 25. 
 Several species of ranunculus, particularly 
 the aquatilis. 26. Nitre, in a large dose. 
 27. Some muscles and other shell- fish. 
 
 IV. — Narcotic and stupefying poisons. 
 
 1 . The gases ; hydrogen, azote, and oxide 
 of azote. 
 
 2. Poppy and opium. 
 
 3. The roots of the solanum somnife- 
 
 rum ; berries and leaves of the solanum ni- 
 grum ; those of the morel with yellow fruit. 
 
 4. The roots and leaves of the atropa inan- 
 dragora. 5. Datura stramonium. 6. Ilyo- 
 ciamus, or henbane. 7. Lactuca virosa. 8. 
 Paris quadrifolia, or herb Paris. 9. Lauro- 
 cerasus, or bay laurel and prussic acid. 10. 
 Berries of the yew tree. 11. Ervum ervi- 
 lia; the seeds. 12. The seeds of lathyrus 
 cicera. 13. Distilled water of bitter al- 
 
 monds. 14. The effluvia of many of the 
 above plants. 
 
 V. — Narcotico -acrid poisons. 
 
 1. Carbonic acid ; the gas of charcoal 
 stoves and fermenting liquors. 2. The man- 
 ch ineel. 3. Faba Sancti Ignatii. 4. The 
 exhalations and juice of the poison-tree of 
 Macassar, or Upas- A ntiar. 5. Theticunas. 
 6. Certain species of Strychnos. 7. The 
 whole plant, Lauro-cerasus. 8. Belladonna, 
 or deadly ^nightshade. 9. Tobacco. 10. 
 Roots of white bryony. 11. Roots of the 
 Choerophyllum silvestre. 12. Conium ma- 
 culatum, or spotted hemlock. 13. iEthusa 
 cynapium. 14. Cicuta virosa. 15. Ana- 
 gallis arvensis. 16. Mercurialis perennis. 
 17. Digitalis purpurea. 18. The distilled 
 waters and oils of some of the above plants. 
 
 1 9. The odorant principle of some oi them. 
 
 20. Woorara of Guiana. 21. Camphor. 
 22. Coceulus Indicus. 23. Several mush- 
 rooms ; sec Agaricus, and Boletus. -E 
 Secale cornutum. 25. Lolium temulentym. 
 
POR 
 
 POL 
 
 26. Sium latifolium. 27. Coriaria myrti- 
 folia. 
 
 VI. — Septic or putrescent poisons . 
 
 1. Sulphuretted hydrogen. 2. Futrid 
 effluvia of animal bodies. 5 . Contagious 
 effluvia, or fomites and miasmata ; see Mias- 
 mata. 4. Venomous animals ; the viper, 
 rattlesnake, scorpion, mad dog, Sec. 
 
 I regret that the limits of this work pre- 
 clude me from introducing a systematic view 
 of the mode of action of the principal sub- 
 stances in the above catalogue. Under Anti- 
 mony , Arsenic, Copper , Lead, Mercury , Sil- 
 ver, pretty copious details are given of the 
 poisonous effects of their preparations, and 
 of the best methods of counteracting them. 
 
 Antidote for vegetable poisons. M. Dra- 
 piez has ascertained, by numerous experi- 
 ments, that the fruit of the feuillca cord folia , 
 is a powerful antidote against vegetable poi- 
 sons. He poisoned dogs with the rhus toxi- 
 codendron, hemlock, and nux vomica ; and 
 all those which were left to the effects of the 
 poison died, but those to which the above 
 fruit was administered, recovered completely, 
 after a short illness. To see whether the 
 antidote would act in the same way, applied 
 externally to wounds into which vegetable 
 poisons had been introduced, he took two 
 arrows, which had been dipped into the juice 
 of the manchenille, and slightly wounded 
 with them two cats ; to one of these wounds 
 he applied a poultice, composed of the fruit 
 of th ojeuillea cordifolia, while the other was 
 left without any application. The former 
 suffered no inconvenience, except from the 
 pain of the wound, which speedily healed ; 
 while the other, in a short time, fell into 
 convulsions, and died. This fruit loses 
 these valuable virtues, if kept two years after 
 it is gathered. 
 
 Dr Chisholm states, that the juice of the 
 sugar-cane is the best antidote for arsenic. 
 
 Dr Lyman Spalding of New- York, an- 
 nounces in a small pamphlet, that for above 
 these fifty years, the Scutellaria Lateriflora 
 has proved to be an infallible means for the 
 prevention aud cure of the hydrophobia, after 
 the bite of rabid animals. It is better ap- 
 plied as a dry powder, than fresh. Accord- 
 ing to the testimonies of several American 
 physicians, this plant, not yet received as a 
 remedy in any European Materia Mcdica, 
 afforded perfect relief in above a thousand 
 cases, as well in the human species, as in the 
 brute creation, (dogs, swine, and oxen). — 
 Phil. Mag. lvi. p. 151.* 
 
 * Polishing- Slate. See Clay.* 
 
 * Pollen. The powdery matter evolved 
 from the anther cc of flowers. That of the 
 date seems, from the experiments of Four- 
 croy and Vauquelin, to approach in its con- 
 stitution to animal substances; that of the 
 hazel-nut contains tannin, resin, much glu- 
 ten, and a little fibrin ; and that of the tulip 
 
 yielded to Grotthus the following const! 
 tuents in 26 parts : 
 
 Vegetable albumen, - 20.25 
 
 Malate of lime, with trace of I ^ 
 malate of magnesia, ) 
 
 Malic acid, - LOO 
 
 Malate of ammonia, 
 
 Colouring matter, 
 
 Saltpetre ? 
 
 The principle in pollen, intermediate be- 
 tween gluten and albumen, has been named 
 by Dr John, Pollenin. 
 
 It is yellow, without taste and smell ; in- 
 soluble in water, alcohol, ether,, fat, and vo- 
 latile oils, and petroleum. 
 
 It burns %vith flame. On exposure to air, 
 it assumes the smell and taste of cheese, and 
 soon becomes putrid with disengagement of 
 ammonia.* 
 
 * Folychroite. The colouring matter of 
 saffron.* 
 
 * PoMriionx. White oxide of zinc. * 
 
 * Ponderous Spar. See Heavy Spar.* 
 
 * Porcelain Earth. See Clay.* 
 
 Porcelain is the most beautiful and tho 
 
 finest of all earthen wares. 
 
 The art of making porcelain is one of 
 those in which Europe has been excelled by 
 oriental nations. The first porcelain that 
 was seen in Europe was brought from Japan 
 and China. The whiteness, transparency, 
 fineness, neatness, elegance, and even the 
 magnificence of this pottery, which soon be- 
 came the ornament of sumptuous tables, did 
 not fail to excite the admiration and industry 
 of Europeans. 
 
 Father Entrecolles, missionary at China, 
 sent home a summary description of the pro- 
 cess by which the inhabitants of that coun- 
 try make their porcelain, and also a small 
 quantity of the materials which they employ 
 in its composition. He said, that the Chinese 
 composed their porcelain of two ingredients, 
 one of which is a hard stone or rock, called 
 by them petuntse, which they carefully grind 
 to a very fine powder ; and the other, called by 
 them kaolin, is a white earthy substance, 
 which they mix intimately with the ground 
 petuntse. 
 
 Reaumur examined both these matters; 
 and having exposed them separately to a vio- 
 lent fire, he discovered, that the petuntse had 
 fused without addition, and that the kaolin 
 had given no sign of fusibility. He after- 
 ward mixed these matters, and formed cakes 
 of them, which, by baking, were converted 
 into porcelain similar to that of China. See 
 Kaolin, Petuntse, and Pottery. 
 
 Porcelain of Reaumur. Reaumur gave 
 the quality of porcelain to glass; that is, he 
 rendered glass of a milky colour, semi-trans- 
 parent, so hard as to strike fire with steel, 
 infusible, and of a fibrous grain, by means of 
 cementation. The process which he pub- 
 lished is not difficult. Common glass, such 
 
 1.25 
 
 2G.00 
 
POT 
 
 POT 
 
 as that of which wine bottles are made, suc- 
 ceeds best. The glass vessel which is to be 
 converted into porcelain, is to be enclosed in 
 a baked earthen case or seggar. The vessel 
 and case are to be filled with a cement com- 
 posed of equal parts of sand and powdered 
 gypsum or plaster ; and the whole is to be 
 put into a potter’s kiln, and to remain there 
 during the baking of common earthenware; 
 after which the glass vessel will be found 
 transformed into such a matter as has been 
 described. 
 
 * Porphyry is a compound rock, having 
 a basis, in which the other contemporaneous 
 constituent parts are imbedded. The base is 
 sometimes clay-stone, sometimes hornstone, 
 sometimes compact felspar; or pitchstone, 
 pearl stone, and obsidian. The imbedded 
 parts are most commonly felspar and quartz, 
 which are usually crystallized, more or less 
 perfectly, and hence they appear sometimes 
 granular. According to Werner, there are 
 two distinct porphyry formations ; the oldest 
 occurs in gneiss, in beds of great magnitude ; 
 and also in mica-slate and clay-slate. Be- 
 tween Blair in Athole and Dalnacardoch, 
 there is a very fine example of a bed of por- 
 phyry-slate in mica. The second porphyry 
 formation is much more widely extended. 
 It consists principally of clay porphyry, while 
 the former consists chiefly of hornstone por- 
 phyry and felspar porphyry. 
 
 It sometimes contains considerable repo- 
 sitories of ore, in veins. Gold, silver, lead, 
 tin, copper, iron, and manganese occur in it ; 
 but chiefly in the newer porphyry, as hap- 
 pens with the Hungarian mines. It occurs 
 in Arran, and in Perthshire, between Dalna- 
 cardoch and Tumrael-bridge.* 
 
 Portland Stone. A compact sandstone 
 from the Isle of Portland. The cement is 
 calcareous. 
 
 * Potash, commonly called the vegetable 
 alkali, because it is obtained in an impure 
 state by the incineration of vegetables. It is 
 the hydrated dcutoxide of potassium.* 
 
 Table of the saline product of one thousand 
 lbs. of ashes of the following vegetables : — - 
 Saline products. 
 
 Stalks of Turkey ) 198 ^ 
 wheat or mats, j 
 
 Stalks of sun- 
 
 rt 
 
 | 349 
 
 flower, 
 
 Vine- branches, 
 
 162.6 
 
 Elm, 
 
 166 
 
 Box, 
 
 78 
 
 Sallow, 
 
 102 
 
 Oak, 
 
 ] 1 1 
 
 Aspen, 
 
 61 
 
 Beech, 
 
 219 
 
 Fir, 
 
 132 
 
 Fern cut in Au- 
 
 116 \ 
 
 gust, 
 
 Wormwood, 
 
 l 
 
 748 
 
 or 1 25 according to 
 Wildenheim. 
 
 Fumitory, 360 
 
 Heath, 115 \Y ildenheim. 
 
 On these tables Kirwan makes the follow- 
 ing remarks : — 
 
 1. That in general weeds yield more ashes, 
 and their ashes much more salt than woods; 
 and that consequently, as to salts of the ve- 
 getable alkali kind, as potash, pearl ash, ca- 
 shup, Sec. neither America, Trieste, nor the 
 northern countries, have any advantage over 
 Ireland. 
 
 2. That of all weeds fumitory produces 
 most salt, and next to it wormwood. But 
 if we attend only to the quantity of salt in a 
 given weight of ashes, the ashes of worm- 
 wood contain most. Trifolium fibrinum also 
 produces more ashes and salt than fern. 
 
 The process for obtaining pot and pearl- 
 ash is given by Kirwan, as follows : — 
 
 1. The weeds should be cut just before 
 they seed, then spread, well dried, and ga- 
 thered clean. 
 
 2. They should be burned within doors 
 on a grate, and the ashes laid in a chest as 
 fast as they are produced. If any charcoal 
 be visible, it should be picked out, and 
 thrown back into the fire. If the weeds be 
 moist, much coal will be found. A close 
 smothered fire, which has been recommend- 
 ed by some, is very prejudicial. 
 
 5. They should be lixiviated with twelve 
 times their weight of boiling water. A drop 
 of the solution of corrosive sublimate will 
 immediately discover when the water ceases 
 to take lip any more alkali. The earthy 
 matter that remains is said to be a good 
 manure for clayey soils. 
 
 4. The ley thus formed should be evapo- 
 rated to dryness in iron pans. Two or three 
 at least of these should be used, and the ley, 
 as fast as it is concreted, passed from the 
 one to the other. Thus, much time is saved, 
 as weak leys evaporate more quickly than 
 the stronger. The salt thu* procured is of a 
 dark colour, and contains much extractive 
 matter, and being formed in iron pots, is 
 called potash. 
 
 5. This salt should then be carried to a 
 reverberatory furnace, in which the extractive 
 matter is burnt off, and much of the water 
 dissipated : hence it generally loses from 
 ten to fifteen per cent of its weight. Parti- 
 cular care should be taken to prevent its 
 melting, as the extractive matter would not 
 then be perfectly consumed, and the alkali 
 would form such a union with the earthy 
 parts as could not easily be dissolved. Kir- 
 wan adds this caution, because l)r Lewis 
 and Mr Dossie have inadvertently directed 
 the contrary. This salt thus refined is call- 
 ed pearl-ash, and must be the same as the 
 Dantzic pearl-ash. 
 
 To obtain this alkali pure, Berthollet re- 
 commends, to evaporate a solution ot pot- 
 ash, made caustic by boiling with quicklime, 
 
POT 
 
 POT 
 
 till it becomes of a thickish consistence, to 
 add about an equal -weight of alcohol, and 
 let the mixture stand some time in a close 
 vessel. Some solid matter, partly crystal- 
 lized, will collect at the bottom ; above this 
 will be a small quantity of a dark coloured 
 fluid; and on the top another lighter. The 
 latter, separated by decantation, is to be eva- 
 porated quickly in a silver basin in a sand- 
 heat. Glass, or almost any other metal, 
 would be corroded by the potash. Before 
 the evaporation has been carried far, the so- 
 lution is to be removed from the fire, and 
 suffered to stand at rest; when it will again 
 separate into two fluids. The lighter, being 
 poured off', is again to be evaporated with a 
 quick heat; and on standing a day or two 
 in a close vessel, it will deposit transparent 
 crystals of pure potash. If the liquor be 
 evaporated to a pellicle, the potash will con- 
 crete without regular crystallization. In 
 both cases a high-coloured liquor is separated, 
 which is to be poured off; and the potash 
 must be kept carefully secluded from air. 
 
 A perfectly pure solution of potash, will 
 remain transparent, on the addition of lime- 
 water, show no effervescence with dilute sul- 
 phuric acid, and not give any precipitate on 
 blowing air from the lungs through it by 
 means of a tube. 
 
 * Pure potash for experimental purposes, 
 may most easily be obtained by igniting 
 cream of tartar in a crucible, dissolving the 
 residue in water, filtering, boiling with a 
 quantity of quicklime, and after subsidence, 
 decanting the clear liquid, and evaporating 
 in a loosely covered silver capsule, till it flows 
 like oil, and then pouring it out on a clean 
 iron plate. A solid white cake of pure hy- 
 drate of potash is thus obtained, without the 
 agency of alcohol. It must be immediately 
 broken into fragments, and kept in a well- 
 stoppered phial. 
 
 As 100 parts of subcarbonate of potash, 
 are equivalent to about 70 of pure concen- 
 trated oil of vitriol, if into a measure tube, 
 graduated into 100 equal parts, we introduce 
 the 70 grains of acid, and fill up the remain- 
 ing space w ith water, then w r e have an alkali- 
 meter for estimating the value of commer- 
 cial pearl ashes, which, if pure, will require 
 for 100 grains one hundred divisions of the 
 liquid to neutralize them. If they contain 
 only 60 per cent of genuine subcarbonate, 
 then 100 grains will require only 60 divi- 
 sions, and so on. When the alkalimeter 
 indications are required in pure or absolute 
 potash, such as constitutes the basis of nitre, 
 then we must use 102 grains of pure oil of 
 vitriol, along with the requisite bulk of 
 water to fill up the volume of the graduated 
 tube. 
 
 The hydrate of potash, as obtained by the 
 preceding process, is solid, wdiito, and ex- 
 tremely caustic ; in minute quantities, chang- 
 
 ing the purple of violets and cabbage to a 
 green, reddened litmus to purple, and yellow 
 turmeric to a reddish-brown. It rapidly at- 
 tracts humidity from the air, passing into 
 the oil of tartar per deliquium of the old che- 
 mists ; a name, however, also given to the 
 deliquesced subcarbonate. Charcoal applied 
 to the hydrate of potash at a cherry-red-heat, 
 gives birth to carburetted hydrogen, and an 
 alkaline subcarbonate ; but at a heat border- 
 ing on whiteness, carburetted hydrogen, car- 
 bonous oxide, and potassium, are formed. 
 Several metals decompose the hydrate of 
 potash, by the aid of heat ; particularly pot- 
 assium, sodium, and iron. The fused hy- 
 drate of potash consists of 5.95 deutoxide of 
 potassium -J- 1.125 water = 7.075, which 
 number represents the compound prime 
 equivalent. It is used in surgery, as the po- 
 tential cautery for forming eschars ; and it 
 was formerly employed in medicine diluted 
 with broths as a lithontriptic. In chemistry, 
 it is very extensively employed, both in ma- 
 nufactures and as a reagent in analysis. It is 
 the basis of all the common soft soaps. The 
 oxides of the following metals are soluble in 
 aqueous potash : — Lead, tin, nickel, arsenic, 
 cobalt, manganese, zinc, antimony, tellu- 
 rium, tungsten, molybdenum. For the sul- 
 phuret, see Sulphur.* 
 
 * Potassium. If a thin piece of solid hy- 
 drate of potash, be placed between two discs 
 of platinum, connected with the extremities 
 of a voltaic apparatus of 200 double plates, 
 four inch square, it will soon undergo fu- 
 sion ; oxygen will separate at the positive 
 surface, and small metallic globules will ap- 
 pear at the negative surface. These form the 
 marvellous metal potassium, first revealed to 
 the world by Sir H. Davy, early in October 
 1807. 
 
 If iron turnings be heated to whiteness 
 in a curved gun-barrel, and potash be melt- 
 ed and made slowly to come in contact with 
 
 w 
 
 the turnings, air being excluded, potassium 
 will be formed, and will collect in the cool 
 part of the tube. This method of procuring 
 it was discovered by MM. Gay Lussac and 
 Thenard, in 1808. It may likewise be pro- 
 duced, by igniting potash with charcoal, as 
 M. Curaudau shewed the same year. 
 
 Potassium is possessed of very extraordi- 
 nary properties. It is lighter than water ; 
 its sp. gr. being 0.865 to water 1.0. At 
 common temperatures, it is solid, soft, and 
 easily moulded by the fingers. At 150° F. 
 it fuses, and in a heat a little below redness, 
 it rises in vapour. It is perfectly opaque. 
 When newly cut, its colour is splendent 
 wdiite, like that of silver, but it rapidly tar- 
 nishes in the air. To preserve it unchang- 
 ed, we must enclose it in a small phial, with 
 pure naphtha. It conducts electricity like 
 the common metals. When thrown upon 
 water, it acts with great violence, and swims 
 
POT 
 
 POT 
 
 upon the 6urface, burning with a beautiful 
 light of a red colour, mixed with violet. 
 The water becomes a solution of pure pot- 
 ash. When moderately heated in the air, it 
 inflames, burns with a red light, and throws 
 off alkaline fumes. Placed in chlorine, it 
 spontaneously burns with great brilliancy. 
 
 On all fluid bodies which contain water, 
 or much oxygen or chlorine, it readily acts; 
 and in its general powers of chemical com- 
 bination, says its illustrious discoverer, pot- 
 assium may be compared to the alkahest, or 
 universal solvent, imagined by the alche- 
 mists. 
 
 Potassium combines with oxygen, in dif- 
 ferent proportions. When potassium is 
 gently heated in common air or in oxygen, 
 the result of its combustion is an orange- 
 coloured fusible substance. For every grain 
 of the metal consumed, about ly 7 ^ cubic 
 inches of oxygen are condensed. To make 
 the experiment accurately, the metal should 
 be burned in a tray of platina covered with 
 a coating of fused muriate of potash. 
 
 The substance procured by the combus- 
 tion of potassium at a low temperature, was 
 first observed in October 1807, by Sir H. 
 Davy, who supposed it to be the protoxide ; 
 but MM. Gay Lussac and Thenard, in 
 1810, shewed, that it was in reality the deut- 
 oxide or peroxide. When it is thrown into 
 water, oxygen is evolved, and a solution' of 
 the protoxide results, constituting common 
 aqueous potash. When it is fused, and 
 brought in contact with combustible bodies, 
 they burn vividly, by the excess of its oxy- 
 gen. If it be heated in carbonic acid, oxy- 
 gen is disengaged, and common subcarbo- 
 nate of potash is formed. 
 
 When it is heated very strongly upon pla- 
 tina, oxygen gas is expelled from it, and 
 there remains a difficultly fusible substance 
 of a grey colour, vitreous fracture, soluble 
 in water, without effervescence, but with 
 much heat. Aqueous potash is produced. 
 The above ignited solid, is protoxide of pot- 
 assium, which becomes pure potash by com- 
 bination with the equivalent quantity of wa- 
 ter. When we produce potassium with ig- 
 nited iron turnings and potash, much hydro- 
 gen is disengaged from the water of the hy- 
 drate, while the iron becomes oxidized from 
 the residuary oxygen. By heating together 
 pure hydrate of potash and boracic acid, Sir 
 H. Davy obtained from 1 7 to 1 8 of water, 
 from 100 parts of the solid alkali. 
 
 By acting on potassium with a very small 
 quantity of water, or by heating potassium 
 with fused potash, the protoxide may also 
 1)0 obtained. The proportion of oxygen in 
 the protoxide, is determined by the action ot 
 potassium upon water. 8 grains of potas- 
 sium produce from water about 9£ cubic 
 inches of hydrogen ; and for these the me- 
 tal must have fixed 4|- cubic inches of oxy- 
 
 gen. But as 100 cubic inches of oxygen 
 weigh 33.9 gr. 4| will weigh 1.61. Thus, 
 9.61 gr. of the protoxide will contain 8 of 
 metal ; and 100 will contain 83.25 metal -j- i 
 16.75 oxygen. From these data, the prime 
 of potassium comes out 4.969; and that of 
 the protoxide 5.969. Sir H. Davy adopts 
 the number 75 for potassium, corresponding 
 to 50 on the oxygen scale. 
 
 When potassium is heated strongly in 
 a small quantity of common air, the oxygen 
 of which is not sufficient for its conversion 
 into potash, a substance is formed of a grey- 
 ish colour, which, when thrown into water, 
 effervesces without taking fire. It is doubt- 
 ful, whether it be a mixture of the protoxide 
 and potassium, or a combination of potas- 
 sium with a smaller proportion of oxygen than 
 exists in the protoxide. In this case, it 
 would be a suboxide, consisting of 2 primes 
 of potassium = 10 1 of oxygen = 1. 
 
 When thin pieces of potassium are intro- 
 duced into chlorine, the inflammation is very 
 vivid; and when potassium is made to act 
 on chloride of sulphur, there is an explosion. 
 The attraction of chlorine for potassium is 
 much stronger than the attraction of oxygen 
 for the metal. Both of the oxides of potas- 
 sium are immediately decomposed by chlo- 
 rine, w ith the formation of a fixed chloride, 
 and the extrication of oxygen. 
 
 The combination of potassium and chlo- 
 rine, is the substance which has been im- 
 properly called muriate of potash, and which, 
 in common cases, is formed, by causing li- 
 quid muriatic acid to saturate solution of 
 potash, and then evaporating the liquid to 
 dryness and igniting the solid residuum. 
 The hydrogen of the acid here unites to the 
 oxygen of the alkali, forming water, which 
 is exhaled; while the remaining chlorine 
 and potassium combine. It consists of 5 
 potassium 4.5 chlorine. 
 
 Potassium combines with hydrogen, to 
 form potassuretted hydrogen, a spontaneous- 
 ly inflammable gas, which comes over occa- 
 sionally in the production of potassium by 
 the gun-barrel experiment. MM. Gay Lus- 
 sac and Thenard describe also a solid com- 
 pound of the same two ingredients, which 
 they call a hydruret of potassium. It is 
 formed by heating the metal a long while in 
 the gas, at a temperature just under igni- 
 tion. They describe it as a greyish solid, 
 giving out its hydrogen on contact with 
 mercury. 
 
 When potassium and sulphur are heated 
 together, they combine with great energy, 
 with disengagement of heat and light, even 
 in vacuo. The resulting sulphuret of pot- 
 assium, is of a dark grey colour. It acts 
 with great energy on water, producing sul- 
 phuretted hydrogen, and burns brilliantly 
 when heated in the air, becoming sulphate 
 of potash. It consists of 2 sulphur 5 
 
POT 
 
 POT 
 
 potassium, by Sir H. Davy’s experiments, 
 potassium has so strong an attraction for 
 sulphur, that it rapidly separates it from hy- 
 drogen. If the potassium be heated in the 
 sulphuretted gas, it takes fire and burns with 
 great brilliancy ; sulphuret of potassium is 
 formed, and pure hydrogen is set free. 
 
 Potassium and phosphorus enter into 
 union with the evolution ol light ; but the 
 mutual action is feebler than in the preced- 
 ing compound. The phosphuret of potas- 
 sium, in its common form, is a substance of 
 a dark chocolate colour, but when heated 
 with potassium in great excess, it becomes 
 of a deep grey colour, with considerable lus- 
 tre. Hence, it is probable, that phosphorus 
 and potassium are capable of combining in 
 two proportions. T he phosphuret of potas- 
 sium burns with great brilliancy, when ex- 
 posed to air, and when thrown into water 
 produces an explosion, in consequence ot 
 the immediate disengagement of phosphu- 
 retted hydrogen. 
 
 Charcoal which has been strongly heated 
 in contact with potassium, effervesces in wa- 
 ter, rendering it alkaline, though the char- 
 coal may be previously exposed to a tem- 
 perature at which potassium is volatilized. 
 Hence, there is probably a compound of the 
 two formed by a feeble attraction. 
 
 Of all known substances, potassium is 
 that which has the strongest attraction for 
 oxygen; and it produces such a condensa- 
 tion of it, that the oxides of potassium are 
 denser than the metal itself. Potassium 
 has been skilfully used by Sir II. Davy and 
 MM. Gay Lussac and Thenard, for detect- 
 ing the presence of oxygen in bodies. A 
 number of substances, indecomposable by 
 other chemical agents, are readily decompos- 
 ed by this substance . — Elements oJ‘ Chemi- 
 cal Phil, by Sir II. Davy. 
 
 * Potassium, (Iodide of)* See Acid (Hy- 
 
 DRIODIC’).* 
 
 Pottery. The art of making pottery, is 
 intimately connected with chemistry, not only 
 from the great use made of earthen vessels 
 by chemists, but also because all the pro- 
 cesses of this art, and the means of perfecting 
 it, are dependent on chemistry. 
 
 The process of manufacturing stonew r are, 
 according to Dr Watson, is as follows: 
 
 Tobacco-pipe clay from Dorsetshire is 
 beaten much in water. By this process, the 
 finer parts of the clay remain suspended in 
 the water, while the coarser sand and other 
 impurities fall to the bottom. The thick 
 liquid, consisting of water and the finer parts 
 of the clay, is farther purified by passing it 
 through hair and lawn sieves, of different 
 degrees of fineness. After this, the liquid is 
 mixed (in various proportions for various 
 wares) with another liquor, of as nearly as 
 may be the same density, and consisting of 
 flints calcined, ground, and suspended in 
 
 water. The mixture is then dried in a kiln ; 
 and being afterward beaten to a proper tem- 
 per, it becomes fit for being formed at the 
 wheel into dishes, plates, bowls, &c. When 
 this w r are is to be put into the furnace to be 
 baked, the several pieces of it are placed in 
 the cases made of clay, called seggars, which 
 are piled one upon another, in the dome of 
 the furnace. A fire is then lighted ; and 
 when the ware is brought to a proper tem- 
 per, which happens in about forty- eight 
 hours, it is glazed by common salt. The 
 salt is thrown into the furnace, through holes 
 in the upper part of it, by the heat of w hich 
 it is instantly converted into a thick vapour; 
 which, circulating through the furnace, enters 
 the seggar through holes made in its side, 
 (the top being covered to prevent the salt 
 from falling on the ware) ; and attaching 
 itself to the surface of the ware, it forms that 
 vitreous coat upon the surface which is called 
 its glaze. 
 
 The yellow or queen’s- w^are is made of 
 the same materials as the flint-ware ; but the 
 proportion in w T hich the materials are mixed 
 is not the same, nor is the ware glazed in 
 the same way. The flint- ware is generally 
 made of four measures of liquid flint, and of 
 eighteen of liquid clay. The yellow ware 
 has a greater proportion of clay in it. In 
 some manufactories they mix 20, and in 
 others 24 measures of clay, with 4 of flint. 
 These proportions, if estimated by the weight 
 of the materials, w ould probably give for the 
 flint-ware about 3 cwt. of clay to 1 cwt. of 
 flint, and for the yellow w r are somew hat more 
 clay. The proportion, however, for both 
 sorts of w-are depends very much upon the 
 nature of the clay, which is very variable 
 even in the same pit. Hence a previous trial 
 must be made of the quality of the clay, by 
 burning a kiln of the ware. If there be too 
 much flint mixed with the clay, the ware, 
 when exposed to the air after burning, is apt 
 to crack ; and if there be too little, the ware 
 will not receive the proper glaze from the 
 circulation of the salt vapour. 
 
 This glaze, even when it is most perfect, 
 is in appearance less beautiful than the glaze 
 on the yellow w'are. 
 
 The yellow glaze is made by mixing to- 
 gether in water, till it becomes as thick as 
 cream, 1 12 lb. of w hite lead, 24 lb. of ground 
 flint, and 6 lb. of ground flint-glass. Some 
 manufactories leave out the glass, and mix 
 only 80 lb. of white lead with 20 lb. of 
 ground flint ; and others doubtless observe 
 different rules, of which it is very difficult to 
 obtain an account. 
 
 The w'are before it is glazed is baked in 
 the fire. By this means it acquires the pro- 
 perty of strongly imbibing moisture. It is 
 therefore dipped in the liquid glaze, and 
 suddenly taken out : the glaze is imbibed 
 into its pores, and the ware presently be- 
 
PIIE 
 
 PRU 
 
 comes dry. It 13 then exposed a second 
 time to the fire, by which means the glaze it 
 has imbibed is melted, and a thin glassy coat 
 is formed upon its surface. The colour of 
 this coat is more or less yellow, according as 
 a greater or less proportion of lead has been 
 used. The lead is principally instrumental 
 in producing the glaze, as well as in giving 
 it the yellow colour ; for lead, of all the 
 substances hitherto known, has the greatest 
 power of promoting the vitrification of the 
 substances with which it is mixed. The 
 flint serves to give a consistence to the lead 
 during the time of its vitrification, and to 
 hinder it from becoming too fluid, and run- 
 ning down the sides of the ware, and thereby 
 leaving them unglazed. 
 
 The yellowish colour which lead gives 
 when vitrified with flints, may be wholly 
 changed by very small additions of other 
 mineral substances. Thus, to give one in- 
 stance, the beautiful black glaze, which is 
 fixed on one sort of the ware made at Not- 
 tingham, is composed of 21 parts by weight 
 of white lead, of five of pow dered flints, and 
 of 5 of manganese. The queen’s- ware at 
 present is much whiter than formerly. 
 
 The coarse stone ware made at Bristol 
 consists of tobacco-pipe clay and sand, and 
 is glazed by the vapour of salt, like Stafford- 
 shire flint-ware ; but it is far inferior to it in 
 beauty. 
 
 * Potential Cautery. Caustic potash. * 
 
 * Potstone, or Lapis Ollaris. Colour 
 greenish-grey. Massive, and in granular 
 concretions. Glistening. Fracture curved 
 foliated. Translucent on the edges. Streak 
 white. Soft. Sectile. Feels greasy. Some- 
 what tough. Sp. gr. 2.8. Its constituents 
 are, silica 39, magnesia 16, oxide of iron 10, 
 carbonic acid 20, w^ater 10. It occurs in 
 thick beds in primitive slate. It is found 
 abundantly on the shores of the lake Como 
 in Lombardy. It is fashioned into culinary 
 vessels in Greenland. It is a sub-species of 
 the rhomboidal mica of Professor Jameson.* 
 
 * Powder of Algorotii. The white ox- 
 ide of antimony, thrown down from the mu- 
 riate, by water.* 
 
 * Prase. Colour leek-green. Massive, 
 seldom crystallized. Its forms are, the six- 
 sided prism, and the six-sided pyramid. 
 Lustre shining. Fracture conchoidal. .Trans- 
 lucent. Hard. Tough. Sp. gr. 2.67. 
 Its constituents are, silica 98.5, alumina, 
 with magnesia, 0.5, and oxide of iron 1. — 
 Bucholz. It occurs in mineral beds com- 
 posed of magnetic ironstone, galena, &c. 
 
 It is found in the island of Bute, and in 
 Borrodale. * 
 
 * Precipitants. See Metals, and Mi- 
 neral Waters.* 
 
 Precipitate, and Precipitation. When 
 a body dissolved in a fluid is either in whole 
 or in part made to separate and fall down in 
 
 the concrete state, this falling down is called 
 precipitation, and the mutter thus separated 
 is called a precipitate. See Waters (Mine- 
 ral), and Metals. 
 
 * Precipitate, per se. Red oxide of 
 mercury, by heat.* 
 
 * Prehnite. Prismatic prehnite ; of 
 which there are two sub-species, the foliated 
 and the fibrous. 
 
 L Foliated. Colour apple-green. Mas- 
 sive, in distinct concretions, and sometimes 
 crystallized. The primitive form is an 
 oblique four-sided prism of 103° and 77°. 
 The secondary forms are, an oblique four- 
 sided table, and irregular eight-sided table, 
 an irregular six-sided table, and a broad 
 rectangular four-sided prism. Shining. Frac- 
 ture fine grained uneven. Translucent. 
 Hardness from felspar to quartz. Easily 
 frangible. Sp. gr. 2.8 to 3.0. It melts 
 with intumescence into a pale-green or yel- 
 low glass. It does not gelatinize with acids. 
 Its constituents are, silica 43.83, alumina 
 30.33, lime 18.33, oxide of iron 5.66, water 
 1.83. — Klaproth. It occurs in France, in 
 
 the Alps of Savoy, and in the Tyrol. It is 
 said to become electric bv heating. Bcauti- 
 lul varieties are found in the interior of 
 Southern Africa. 
 
 2. Fibrous Prehnite. Colour siskin-green. 
 Massive, in distinct concretions, and crystal- 
 lized in acicular four-sided prisms. Glisten- 
 ing, pearly. Translucent. Easily frangi- 
 ble. Sp. gr. 2.89. It melts into a vesicular 
 enamel. It becomes electric by heating. Its 
 constituents are, silica 42.5, alumina 28.5, 
 lime 20.44, natron and potash 0.75, oxide of 
 iron 3, water 2. — Laugier. It occurs in 
 veins and cavities in trap-rocks near Beith in 
 Ayrshire, Bishoptowm in Renfrewshire, at 
 Hartfield near Paisley, and near Friskv-hall, 
 Old Kilpatrick ; in the trap-rocks round 
 Edinburgh, &c.* 
 
 * Prince’s Metal. A species of copper 
 alloy, in which the proportion of zinc is more 
 considerable than in brass.* 
 
 * Prostate Concretions. See Calculi.* 
 
 * Prussian Alkali. See Acid (Ferro- 
 prussic).* 
 
 * Prussian Blue. See Tron and the above 
 Acid.* 
 
 * Prussic Acid. See Acid (Prussic).* 
 
 * Prussine, or Prussic Gas, the cyanogen 
 of M. Gay Lussac. This last term signifies 
 the producer of blue. But the production of 
 blue is never the result of the direct action of 
 this substance on any other single body; but 
 an indirect and unexplained operation of it in 
 conjunction w ith iron, hydrogen and oxygen. 
 The same reason which leads to the term 
 cyanogen, would warrant us in calling it 
 leucogen, erythrogen, or chlorogen ; for it 
 produces white, red, or green, with other 
 metals, if it produce blue with iron. Al- 
 though, therefore, the highest deference be 
 
PRU 
 
 PRU 
 
 due to the nomenclature of so distinguished a 
 chemist as M. Gay Lussac, yet I apprehend 
 it is better to retain the old word, connected 
 merely with the history of the substance. 
 As cyanogen, like chlorine and iodine, by its 
 action on potassium, produces flame, and like 
 them is acidified by hydrogen, I would res- 
 pectfully propose the name Prussink. Its 
 discovery and investigation do the highest 
 honour to M. Gay Lussac. 
 
 Prussine, or cyanogen, is obtained by de- 
 composing the prusside or cyanide of mer- 
 cury by heat. But as the prusside of mer- 
 cury varies in its composition, we shall be- 
 gin by describing its formation. 
 
 By digesting red oxide of mercury with 
 prussian blue and hot water, we obtain a 
 cyanide perfectly neutral, which crystallizes 
 in long four-sided prisms, truncated ob- 
 liquely. By repeated solutions and crystal- 
 lizations, we may free it from a small portion 
 of adhering iron. But M. Gay Lussac pre- 
 fers boiling it with red oxide of mercury, 
 which completely precipitates the oxide of 
 iron, and lie then saturates the excess of 
 oxide of mercury, with a little prussic acid, 
 or a little muriatic acid. The prusside thus 
 formed, is decomposed by heat, to obtain the 
 radical. For common experiments, we may 
 dispense w r ith these precautions. 
 
 When this cyanide is boiled with red 
 oxide of mercury, it dissolves a considerable 
 quantity of the oxide, becomes alkaline, crys- 
 tallizes no longer in prisms, but in small 
 scales, and its solubility in water appears a 
 little increased. When evaporated to dry- 
 ness, it is very easily charred, which obliges 
 us to employ the heat merely of a water 
 bath. This compound was observed by M. 
 Proust. When decomposed by heat, it gives 
 abundance of prussine, but mixed with car- 
 bonic acid gas. Proust says, that it yields 
 ammonia, oil In considerable abundance, car- 
 bonic acid, azote, and oxide of carbon. He 
 employed a moist prusside. Had it been 
 dry, the discovery of prussine could hardly 
 have escaped him. The prusside of mer- 
 cury, when neutral and quite dry, gives no- 
 thing but prussine ; when moist, it furnishes 
 only carbonic acid, ammonia, and a great 
 deal of prussic acid vapour. When we em- 
 ploy the prusside made with excess of per- 
 oxide, the same products are obtained, but in 
 different proportions, along with azote, and a 
 brown liquid, which Proust took for an oil, 
 though it is not one in reality. Hence to 
 obtain pure prussine, we must employ the neu- 
 tral prusside in a state of perfect dryness. The 
 other mercurial compound is not, however, 
 simply a sub-prusside. It is a compound of 
 oxide of mercury, and the prusside, analo- 
 gous to the brick coloured precipitate ob- 
 tained by adding a little potash to the solu- 
 tion of deutochloride of mercury (corrosive 
 sublimate), which is a triple compound of 
 
 chlorine, oxygen, and mercury, or a binary 
 compound of oxide of mercury, with the 
 chloride of that metal. These compounds 
 might- be called, oxyprusside and oxychloride 
 of mercury. 
 
 When the simple mercurial prusside is 
 exposed to heat in a small glass retort, or 
 tube, shut at one extremity, it soon begins to 
 blacken. It appears to melt like an ani- 
 mal matter, and then the prussine is disen- 
 gaged in abundance. This gas is pure from 
 the beginning of the process to the end, 
 provided always that the heat be not very 
 high ; for if it w r ere sufficiently intense to 
 melt the glass, a little azote would be evolv- 
 ed. Mercury is volatilized with a consider- 
 able quantity of prusside, and. there remains 
 a charry matter of the colour of soot, and as 
 light as lampblack. The prusside of silver 
 gives out likewise prussine when heated ; 
 but the mercurial prusside is preferable to 
 every other. 
 
 Prussine or cyanogen is a permanently 
 elastic fluid. Its smell, which it is impossible 
 to describe, is very strong and penetrating. 
 Its solution in w’ater has a very sharp taste. 
 The gas burns with a bluish flame mixed 
 with purple. Its sp. gr., compared to that 
 of air, is 1.8064. M. Gay Lussac obtained 
 it by weighing at the same temperature, and 
 under the same pressure, a balloon of about 
 c 2~ litres, (152.56 cubic inches), in which 
 the vacuum w r as made to the same degree, 
 and alternately full of air and prussine. 100 
 cubic inches weigh therefore 55.1295 grains, 
 
 Prussine is capable of sustaining a pretty 
 high heat, without being decomposed. Wa- 
 ter, with which M. Gay Lussac agitated it, 
 for some minutes, at the temperature of 
 68°, absorbed about times its volume. 
 Pure alcohol absorbs 26 times its volume. 
 Sulphuric ether and oil of turpentine dissolve 
 at least as much as w'ater. Tincture of lit- 
 mus is reddened by prussine. On heating 
 the solution the gas is disengaged, mixed 
 with a little carbonic acid, and the blue co- 
 lour of the litmus is restored. The carbonic 
 acid proceeds no doubt frotn the decompo- 
 sition of a small quantity of prussine and 
 water. It deprives the red sulphate of man- 
 ganese of its colour, a property w hich prus- 
 sic acid does not possess. This is a proof 
 that its elements have more mobility than 
 those of the acid. In the dry way, it 
 separates the carbonic acid from the carbo- 
 nates. 
 
 Phosphorus, sulphur, and iodine, may be 
 sublimed by the heat of a spirit-lamp in 
 prussine, w ithout occasioning any change on 
 it. Its mixture with hydrogen was not al- 
 tered by the same temperature, or by passin g 
 electrical sparks through it. Copper and 
 gold do not combine with it; but iron, when 
 heated almost to whiteness, decomposes it in 
 part. The metal is covered with a slight 
 
 2 L 
 
PRU 
 
 PRU 
 
 coating of charcoal, and becomes brittle. 
 The un decomposed portion of the gas is 
 mixed with azote, (contains free azote). In 
 one trial the azote constituted 0.44 of the 
 mixture, but in general it was less. Plati- 
 num, which had been placed beside the iron, 
 did not undergo any alteration. Neither 
 its surface nor that of the tube was covered 
 with charcoal like the iron. 
 
 In the cold, potassium acts but slowly on 
 prussine, because a crust is formed on its 
 surface, which presents an obstacle to the 
 mutual action. On applying the spirit- 
 lamp, the potassium becomes speedily in- 
 candescent ; the absorption of the gas be- 
 gins, the in darned disc gradually diminishes, 
 and when it disappears entirely, which takes 
 place in a few seconds, the absorption is 
 likewise at an end. Supposing we employ a 
 quantity of potassium that would disengage 
 50 parts of hydrogen from water, we find 
 that from 48 to 50 parts of gas have disap- 
 peared. On treating the residue with pot- 
 ash, there usually remains 4 or 5 parts of 
 hydrogen, sometimes 10 or 12. M. Gay 
 Lussac made a great number of experiments 
 to discover the origin of this gas. He thinks 
 that, it is derived from the water which the 
 prusside of mercury contains when it has 
 not been sufficiently dried. Prussic acid 
 vapour is then produced, which, when de- 
 composed by the potassium, leaves half its 
 volume of hydrogen. Potassium therefore 
 absorbs a volume of pure prussine, equal to 
 that of the hydrogen, which it would disen- 
 gage from water. 
 
 The compound of prussine and potassium 
 is yellowish. It dissolves in water without 
 effervescence, and the solution is strongly 
 alkaline. Its taste is the same as that of 
 hydrocyanate or simple prussiate of potash, 
 of which it possesses all the properties. 
 
 The gas being very inflammable, M. Gay 
 Lussae exploded it in Volta’s eudiometer, 
 with about times its volume of oxygen. 
 The detonation is very strong ; and the 
 flame is bluish, like that of sulphur burning 
 in oxvgen. 
 
 Supposing that we operate on 100 parts 
 of prussine, we And after the explosion a 
 diminution of volume, which amounts to 
 from four to nine parts. When the resi- 
 duum is treated with potash or barytes, it 
 diminishes from 195 to 200 parts, which are 
 carbonic acid gas. The new residuum, 
 analyzed over water by hydrogen, gives 
 from 94 to 98 parts of azote, and the oxy- 
 gen which it contains, added to that in the 
 carbonic acid, is equal (within four or five 
 per cent) to that which has been employed. 
 
 Neglecting the small differences which 
 prevent these numbers from having simple 
 ratios to each other, and which, like the 
 presence of hydrogen, depend upon the pre- 
 sence of a variable portion of prussic acid 
 
 vapour in the prussine employed, proceeding 
 from the water left in the prusside of mer- 
 cury, we may admit that prussine contains 
 a sufficient quantity of carbon to produce 
 twice its volume of carbonic acid gas ; that 
 is to say, two volumes of the vapour of car- 
 bon, and one volume of azote, condensed 
 into a single volume. If that supposition 
 he exact, the density of the radical derived 
 from it ought to he equal to the density de- 
 rived from experiment ; but supposing the 
 density of air to be 1.00, twice that of the 
 vapour of 
 
 Carbon is 0.8320 (0.83S2) 
 
 Azote, 0. 969 1 (0. 9722) 
 
 1.8014 1.8051 
 
 From the near agreement of these num- 
 bers with the experimental density, we are 
 entitled to conclude that M. Gay Lussac’* 
 analysis is correct. By adding a volume of 
 hydrogen to a volume of prussine, we ob- 
 tain two volumes of prussic acid vapour; 
 just as by adding a volume of hydrogen to 
 a volume of chlorine, we obtain two vo- 
 lumes of muriatic acid gas. The same pro- 
 portions hold with regard to the vapour of 
 iodine, hydrogen, and hydriodic acid. Hence 
 the sp. gr, of these three hydrogen-acids is 
 exactly equal to half the sum of the densi- 
 ties of their respective bases and hydrogen. 
 This fine analogy was first established by 
 M. Gay Lussac. 
 
 It is now obvious that the action of potas- 
 sium on prussine agrees with its action on 
 prussic acid. We have seen that it absorbs 
 50 parts of the first, and likewise that it 
 absorbs 100 parts of the second, from wffiich 
 it separates 50 parts of hydrogen. But 100 
 parts of prussic acid vapour, minus 50 parts 
 of hydrogen, amount exactly to 50 parts 
 prussine. Hence the two results agree per- 
 fectly, and the two compounds obtained 
 ought to be identical, which agrees precisely 
 with experiment. 
 
 The analysis of prussine being of great 
 importance, M. Gay Lussac attempted it 
 likewise by other methods. Having put 
 prusside of mercury into the bottom of a 
 glass tube, he covered it with brown oxide 
 of copper, and then raised the heat to a dull 
 red. On heating gradually the part of the 
 tube containing the prusside, the prussine 
 wasgradually disengaged, and passed through 
 the oxide, which it reduced completely to 
 the metallic state. On washing the gaseous 
 products with aqueous potash, at different 
 parts of the process, he obtained only from 
 0.19 to 0.30 of azote, instead of 0.33, which 
 ought to have remained according to the 
 preceding analysis. Presuming that some 
 nitrous compound had been formed, he re- 
 peated the experiment, covering the oxide 
 with a column of copper filings, which he 
 kept at the same temperature as the oxide. 
 
PRU 
 
 PRTJ 
 
 With this new arrangement, the results were 
 very singular ; for the smallest quantity of 
 azote which he obtained during the whole 
 course of the experiment was 32.7 for 100 
 of gas, and the greatest was 34.4. The 
 mean of all the trials was, — 
 
 Azote, 55.6 or nearly 1 
 
 Carbonic acid, 66.4 2 
 
 A result which shews clearly that prussine 
 contains two volumes of the vapour of car- 
 bon, and one volume of azote. 
 
 In another experiment, iustead of passing 
 the prussine through the oxide of copper, he 
 made a mixture of one part of the prusside 
 of mercury, and 10 parts of the red oxide, 
 and after introducing it into a glass tube, 
 close at one end, he covered it with copper 
 filings, which he raised first to a red-heat. 
 On heating the mixture successively, the 
 decomposition went on with the greatest fa- 
 cility. The proportions of the gaseous mix- 
 ture were less regular than in the preceding 
 experiment. Their mean was,-— 
 
 Azote, 84.6 instead of 33.3 
 
 Carbonic acid, 65.4 66.6 
 
 In another experiment he obtained, — 
 
 Azote, 32.2 
 
 Carbonic acid, 67.8 
 Now the mean of these results gives,— 
 Azote, S3. 4 
 
 Carbonic acid, 66.6 
 
 No sensible quantity of water seemed to 
 be formed during these analyses. This 
 shews farther, that what has been called a 
 prussiate of mercury is really a prusside of 
 that metal. 
 
 When a pure solution of potash is intro- 
 duced into this gas, the absorption is rapid. 
 If the alkali be not too concentrated, and be 
 not quite saturated, it is scarcely tinged of a 
 lemon-yellow colour. But if the prussine 
 be in excess, we obtain a brown solution, 
 apparently carbonaceous. On pouring pot- 
 ash combined with prussine into a saline 
 solution of a black oxide of iron, and adding 
 an acid, we obtain prussian blue. It would 
 appear from this phenomenon that the prus- 
 sine is decomposed the instant that it com- 
 bines with the potash ; but this conclusion 
 is premature ; for when this body is really 
 decomposed by means of an alkaline solu- 
 tion, carbonic acid is always produced, to- 
 gether with prussic acid and ammonia. But 
 on pouring barytes into a solution of prus- 
 sine in potash, no precipitate takes place, 
 which shews that no carbonic acid is present. 
 On adding an excess of quicklime, no trace 
 of ammonia is perceptible. Since, then, no 
 carbonic acid and ammonia have been form- 
 ed, water has not been decomposed, and con- 
 sequently no prussic acid evolved. IIow 
 then comes the solution of prussine in potash 
 to produce prussian blue, with a solution of 
 iron and acid ? The following is M. Gay 
 
 Lussac*s ingenious solution of this diffi- 
 culty : — 
 
 The instant an acid is poured into the 
 solution of prussine in potash, a strong effer- 
 vescence of carbonic acid is produced, and 
 at the same time a strong smell of prussic 
 acid becomes perceptible. Ammonia is 
 likewise formed, which remains combined 
 with the acid employed, and which may be 
 rendered very sensible to the smell by the 
 addition of quicklime. Since therefore we 
 are obliged to add an acid in order to form 
 prussian blue, its formation occasions no 
 farther difficulty. 
 
 Soda, barytes, and strontites, produce the 
 same effect as potash. We must therefore 
 admit that prussine forms particular combi- 
 nations with the alkalis, which are perma- 
 nent till some circumstance determines the 
 formation of new products. These combi- 
 nations are true salts, which may be regard- 
 ed as analogous to those formed by acids. 
 In fact prussine possesses acid characters. 
 It contains two elements, azote and carbon, 
 the first of which is strongly acidifying, ac- 
 cording to M. Gay Lussac. (Is it not as 
 strongly alkalifying, with hydrogen, in am- 
 monia?) Prussine reddens the tincture of 
 litmus, and neutralizes the bases. On the 
 other hand, it acts as a simple body when it 
 combines with hydrogen ; and it is this dou- 
 ble function of a simple and compound body 
 which renders its nomenclature so embar- 
 rassing. 
 
 Be this as it may, the compounds of prus- 
 sine and the alkalis, which may be distin- 
 guished by the term prussides , do not sepa- 
 rate in water, like the alkaline chlorurets, 
 (oxymuriates), which produce chlorates and 
 muriates. But when an acid is added, 
 there is formed, 1st, Carbonic acid, which 
 corresponds to the chloric acid ; 2d, Am- 
 monia and prussic acid, which correspond to 
 the muriatic. 
 
 When the prusside of potash is decom- 
 posed by an acid, there is produced a volume 
 of carbonic acid just equal to that of the 
 prussine employed. What then becomes of 
 the other volume of the vapour of carbon ; 
 for the prussine contains two, with one vo- 
 lume of azote ? 
 
 Since there is produced, at the expense of 
 the oxygen of the water, a volume of carbo- 
 nic acid, which represents 1 volume of oxy- 
 gen, 2 volumes of hydrogen must likewise 
 have been produced. Therefore, neglecting 
 the carbonic acid, there remains 
 
 1 volume vapour of carbon, 
 
 1 azote, 
 
 2 hydrogen ; 
 
 and we must make these three elements 
 
 combine in totality, so as to produce only 
 prussic acid and ammonia. But the one 
 volume of the vapour of carbon, with half a 
 
HU7 
 
 PRU 
 
 volume of azote, and half a volume of hydro- 
 gen, produces exactly 1 volume of prussic 
 acid, while the volume and a half of hydro- 
 gen, and the halt volume of azote remaining, 
 produce 1 volume of ammoniacal gas; for 
 this substance is formed of 3 volumes of hy- 
 drogen and 1 of azote, condensed into 2 vo- 
 lumes. See Ammonia. 
 
 A given volume of prussine, then, com- 
 bined first with an alkali, and then treated 
 with an acid, produces exactly 
 
 1 volume of carbonic acid gas, 
 
 1 prussic acid vapour, 
 
 1 ammoniacal gas. 
 
 It is very remarkable to see an experiment, 
 apparently very complicated, give so simple 
 a result. 
 
 The metallic oxides do not seem capable 
 of producing the same changes on prussine 
 as the alkalis. Having precipitated proto- 
 sulphate of iron by an alkali, so that no free 
 alkali remained, M. Gay Lussac caused the 
 oxide of iron (mixed necessarily with much 
 water) to absorb prussine, and then added mu- 
 riatic acid. But he did not obtain the slightest 
 trace of prussian blue ; though the same 
 oxide, to which he had added a little potash 
 before adding the acid, produced it in abun- 
 dance.'}- 
 
 From this result one is induced to believe 
 that oxide of iron does not combine with 
 prussine ; ai}d so much the more, because wa- 
 ter impregnated with this gas never produces 
 prussian blue with solutions of iron, unless 
 we begin by adding an alkali. (See Prus- 
 sic Acin). The peroxides of manganese 
 and mercury, and the deutoxide of lead, ab- 
 sorb prussine, but very slowly. If we add 
 water, the combination is much more rapid. 
 With- the peroxide of mercury, we obtain a 
 greyish-white compound, somewhat soluble 
 in water. 
 
 Prussine rapidly decomposes the carbon- 
 ates at a dull red-heat, and prussides of the 
 oxides are obtained. When passed through 
 sulphuret of barytes, it combines without 
 disengaging the sulphur, and renders it very 
 fusible, and of a brownish-black colour. 
 When put into water, we obtain a colourless 
 solution, but which gives a deep brown 
 (maroon) colour to muriate of iron. What 
 does not dissolve contains a good deal of 
 sulphate, which is doubtless formed during 
 the preparation of the sulphuret of barytes. 
 
 On dissolving prussine, in the sulphuretted 
 hydrosulphuret of barytes, sulphur is preci- 
 pitated, which is again dissolved when the 
 liquid is saturated with prussine, and we ob- 
 tain a solution having a very deep brown 
 maroon colour. This gas does not decom- 
 pose sulphuret of silver, nor of potash. 
 
 f Does not this experiment justify the adoption of 
 the term prussin since we see that very complicated 
 affinities must be exercised before blue is produced by 
 cyanogen ? 
 
 Prussine and sulphuretted hydrogen com- 
 bine slowly with each other. A yellow 
 substance is obtained in fine needles, which 
 dissolves in water, does not precipitate nitrate 
 of lead, produces no prussian blue, and 
 is composed of 1 volume prussine (cyano- 
 gen), and volume of sulphuretted hydro- 
 gen.J 
 
 Ammoniacal gas and prussine begin to act 
 on each other whenever they come in con- 
 tact ; but some hours are requisite to render 
 the effect complete. We perceive at first a 
 white thick vapour, which soon disappears. 
 The diminution of volume is considerable, 
 and the glass in which the mixture is made, 
 becomes opaque, its inside being covered 
 with a solid brown matter. On mixing 9t> 
 parts of prussine, and 227 ammonia, they 
 combined nearly in the proportion of 1 to 
 1-|. This compound gives a dark orange- 
 brown colour to water, but dissolves only in 
 a very small proportion. The liquid pro- 
 duces no prussian blue with the salts of iron. 
 
 When prussic acid is exposed to the ac- 
 tion of a voltaic battery of 20 pairs of plates, 
 much hydrogen gas is disengaged at the 
 negative pole, while nothing appears at the 
 positive pole. It is because there is evolved 
 at that pole, prussine, w hich remains dissolv- 
 ed in the acid. We may, in this manner, 
 attempt the combination of metals with 
 prussine, placing them at the positive pole. 
 
 It is easy now to determine what takes 
 place, when an animal matter is calcined 
 with potash or its carbonate. A prusside of 
 potash is formed. It has been proved, that 
 by heat potash separates the hydrogen of 
 the prussic or hydrocyanic acid. We can- 
 not then suppose that this acid is formed, 
 while a mixture of potash and animal mat- 
 ters is exposed to a high temperature. But 
 we obtain a prusside of potash, and not of 
 potassium ; for this last, when dissolved in 
 water, gives only prussiate of potash (hydro- 
 cyanate), which is decomposed by the acids, 
 without producing ammonia and carbonic 
 acid ; w hile the prusside of potash (cyanide) 
 dissolves in water, without being altered, 
 and does not gi*e ammonia, carbonic acid, 
 and prussic (hydrocyanic) acid vapour, un- 
 less an acid be added. This is the character 
 which distinguishes a prusside of a metal, 
 from a prusside of a metallic oxide. Se» 
 Acid (Prussic). 
 
 The preceding facts are taken from INI. 
 Gay Lussac’s memoir on hydrocyanic acid, 
 presented to the Institute, September 18. 
 1815, and published in the Annales de Chi- 
 mie, vol. xcv. 
 
 In the Journal de Pharmacie for Novem- 
 ber 1818, M. Vauquelin has published an 
 elaborate dissertation on the same subject, of 
 
 t This is the compound, which Dr Thomson, from 
 atomic considerations, declares to be destitute ot hy- 
 drogen. 
 
PIIU 
 
 PUT 
 
 which I have given some extracts under 
 Acid (Prussic). I shall insert here his 
 very elegant process for obtaining pure hy- 
 drocyanic or prussic acid, from the cyanide 
 or prusside of mercury. 
 
 Considering that mercury has a strong at- 
 traction for sulphur, and that prussine unites 
 easily to hydrogen, when presented in the 
 proper state, he thought that sulphuretted 
 hydrogen might be employed for decompos- 
 ing dry cyanide (prusside) of mercury. lie 
 operated in the following way : — He made 
 a current of sulphuretted hydrogen gas, dis- 
 engaged slowly from a mixture of sulphuret 
 of iron, and very dilute sulphuric acid, pass 
 slowly through a glass tube slightly heated, 
 filled with the mercurial prusside, and com- 
 municating with a receiver, cooled by a mix- 
 ture of salt and snow. 
 
 As soon as the sulphuretted hydrogen 
 came in contact with the mercurial salt, this 
 last substance blackened, and this effect gra- 
 dually extended to the farthest extremity of 
 the apparatus. During this time no trace of 
 sulphuretted hydrogen could he perceived at 
 the mouth of a tube proceeding from the re- 
 ceiver. As soon as the odour of this gas 
 began to he perceived, the process was stop- 
 ped ; and the tube was heated in order to 
 drive over the acid which might still remain 
 in it. The apparatus being unluted, he 
 found in the receiver a colourless fluid, 
 which possessed all the known properties of 
 prussic acid. It amounted to nearly the fifth 
 part of the prusside of mercury employed. 
 
 This process is easier, and furnishes more 
 acid, than M. Gay Lussac’s, by means of 
 muriatic acid. He repeated it several times, 
 and always successfully. It is necessary, 
 merely to take care to stop the process, be- 
 fore the odour of the sulphuretted hydrogen 
 begins to he perceived ; otherwise, the hy- 
 drocyanic acid will be mixed with it. How- 
 ever, we may avoid this inconvenience, by 
 placing a little carbonate of lead at the ex- 
 tremity of the tube. As absolute hydro- 
 cyanic acid is required only for chemical re- 
 searches, and as it cannot he employed in 
 medicine, it may he wortk while, says M. 
 Vauquelin, to bring to the rccoll<&tion of 
 apothecaries, a process of M. Proust, which 
 has, perhaps, escaped their attention. It 
 consists in passing a current of sulphuretted 
 hydrogen gas through a cold saturated solu- 
 tion of prussiate of mercury in water, till 
 the liquid contains an excess of it; to put 
 the mixture into a bottle, in order to agitate 
 it from time to time; and finally, to filter 
 it. 
 
 If this prussic acid, as almost always hap. 
 pens, contains traces of sulphuretted hydro- 
 gen, agitate it with a little carbonate of lead, 
 and filter it again. By this process we may 
 obtain hydrocyanic acid, in a much greater 
 degree of concentration than is necessary for 
 
 medicine. It lias the advantage over the 
 dry prussic acid, of being capable of being 
 preserved a long time, always taking care to 
 keep it as much as possible from the contact 
 of air and heat. Dr Nimmo’s directions for 
 preparing the prusside of mercury ought to 
 he attended to. His experiments, it will he 
 seen, coincide perfectly with the views so 
 admirably developed by M. Gay Lussac. 
 See Acid (Prussic.) 
 
 In the first volume of the Journal of 
 Science and the Arts, Sir PI. Davy has 
 stated some interesting particulars relative to 
 prussine. By heating prusside of mercury 
 in muriatic acid gas, he obtained pure liquid 
 prussic acid, and corrosive sublimate. By 
 heating iodine, sulphur, and phosphorus, in 
 contact with prusside of mercury, com- 
 pounds of these bodies with prussine or cy- 
 anogen may be formed. That of iodine is 
 a very curious body. It is volatile at a very 
 moderate heat, and on cooling, collects in 
 flocculi, adhering together like oxide of zinc 
 formed by combustion. It has a pungent 
 smell, and very acrid taste. * 
 
 * Pulmonary Concretions, consist of 
 carbonate of lime, united to a membranous 
 or animal matter. By Mr Compton’s ana- 
 lysis, Phil. Mag. vol. xiii. 100 parts contain, 
 
 carbonate of lime, 82 
 
 animal matter and water, 18 
 
 Disease proceeding from this cause, (and I 
 believe it to be a frequent prelude and con- 
 comitant of ulcerated lungs), might he pro- 
 bably benefited by the regular inhalation of 
 aqueous vapour mixed with that of acetic 
 acid or vinegar.* 
 
 * Pumice. A mineral of which there are 
 three kind^. — the glassy, common, and por- 
 phyritic. 
 
 1. Glassy pumice . Colour smoke-grey. 
 
 Vesicular. Glistening, pearly. Fracture pro- 
 miscuous fibrous. Translucent. Between 
 hard and semi-hard. Very brittle. Feels 
 rough, sharp, and meagre. Sp. gr. 0.378 
 to 1.44. It occurs in beds in the Lipari 
 Islands. 
 
 2. Common pumice. Colour nearly white. 
 Vesicular. Glimmering, pearly. Fracture 
 fibrous. Translucent on the edges. Semi- 
 hard. Very brittle. Meagre and rough. 
 ‘T* S*** 0.752 to 0.914. It melts into a 
 grey coloured slag. Its constituents are, si- 
 lica. 77.5, alumina 17.5, natron and potash 
 
 3, iron mixed with manganese 1.75., * 
 
 Klaproth. It occurs with the preceding. 
 
 3. Porphyritic pumice . Colour greyish- 
 white. Massive. Minutely jrorous. Glim- 
 mering and pearly. Sp. gr. 1.66*1. It con- 
 tains crystals of felspar, quartz, and mica. 
 It is associated with claystone, obsidian, 
 pearl stone and pitchstone-porphyry. It oc- 
 curs in Hungary, at Tokay, & c .* 
 
 * Putrefaction. The spontaneous de- 
 composition oi. such animal or vegetable 
 
PYR 
 
 PYR 
 
 matters, as exhale a fetid smell, is called 
 putrefaction. r JL lie solid and fluid matters 
 are resolved into gaseous compounds and 
 vapours which escape, and into an earthy 
 residuum. See Adipoceiie and Fermenta- 
 tion, ot which genus , putrefaction is merely 
 a species. As the grand resolvent of organic 
 matter is water, its abstraction by drying, or 
 lixation by cold, by salt, sugar, spices, &c. 
 will counteract the process of putrefaction. 
 The atmospheric air is also active in putre- 
 faction ; hence, its exclusion favours the 
 preservation of food ; on which principle, 
 some patents have been obtained.* 
 
 * Pyreneite. Colour greyish-black. 
 
 Massive, and crystallized in rhomboidal do- 
 decahedrons. Glistening, and metal-like. 
 Fracture uneven. Opaque. Hard. Sp. 
 
 gr. 2.5 ? It melts with intumescence, into a 
 yellowish- green vesicular enamel. Its con- 
 stituents are, silica 43, alumina 16, lime 20, 
 oxide of iron 16, water 4. — Vauquelin. It 
 occurs in primitive limestone, in the Pic of 
 Eres-Lids, near Bareges, in the French Py- 
 renees. * 
 
 * Pyrites. Native compounds of metal 
 with sulphur. See the particular metallic 
 Ores. * 
 
 * Pyrogom. A variety of diopside.* 
 
 * Pyrometer. The most celebrated in- 
 strument for measuring high temperatures, 
 is that invented by the late Mr Wedgwood, 
 founded on the principle, that clay progres- 
 sively contracts in its dimensions, as it is 
 progressively exposed to higher degrees of 
 heat. He formed his white porcelain clay, 
 into small cylindrical pieces, in a mould, 
 which, when they were baked in a dull red- 
 heat, just fitted into the opening of two brass 
 bars, fixed to a brass plate, so as to form a 
 tapering space between them. This space 
 is graduated; and the farther the pyrometric 
 clay gauge can enter, the greater heat does 
 it^indicate. The two converging rules are 
 placed at a distance of 0.5 of an inch at the 
 commencement of the scale, and of 0.3 at the 
 end. 
 
 Mr Wedgwood sought to establish a cor- 
 respondence between the indications of his 
 pyrometer, and those of the mercurial ther- 
 mometer, by employing a heated rod of silver, 
 whose expansions he measured, as their con- 
 necting link. The clay-piece and silver rod 
 were heated in a muffle.* 
 
 When the muffle appeared of a low red- 
 heat, such as was judged to come fully with- 
 in the province of his thermometer, it was 
 drawn forward toward the door of the oven ; 
 and its own door being then nimbly opened 
 by an assistant, Mr Wedgwood pushed the 
 silver piece as far as it would go. But as the 
 division which it went to could not be dis- 
 tinguished in that ignited state, the muffle 
 was lifted out, by means of an iron rod pass- 
 ed through two rings made for that purpose, 
 
 with care to keep it steady, and avoid any 
 shake that might endanger the displacing of 
 the silver piece. 
 
 When the muffle was grown sufficiently 
 cold to be examined, he noted the degree of 
 expansion which the silver piece stood at, 
 and the degree of heat shown by the ther- 
 mometer pieces measured in their own gauge; 
 then returned the whole into the oven as be- 
 fore, and repeated the operation with a strong- 
 er heat, to obtain another point of corres- 
 pondence on the two scales. 
 
 The first was at 2-|° of his thermometer, 
 which coincided with 66° of the intermediate 
 one; and as each of these last had been 
 before found to contain 20° of Fahren- 
 heit’s, the 66 will contain 1320; to which 
 add 50, the degree of his scale to which 
 the (0) of the intermediate thermometer was 
 adjusted, and the sum 1570 will be the 
 degree of Fahrenheit’s corresponding to his 
 
 O 1.0 
 
 *•4 * 
 
 The second point of coincidence was at 
 6^° of his, and 92° of the intermediate; 
 which 92 being, according to the above pro- 
 portion, equivalent to 1840 of Fahrenheit, 
 add 50 as before to this number, and his 
 6£° is found to fall upon the 1890th degree 
 of Fahrenheit. 
 
 It appears hence that an interval of four 
 degrees upon Mr Wedgwood’s thermometer 
 is equivalent to an interval of 520° upon 
 that of Fahrenheit ; and, consequently, one 
 of the former to 150° of the latter; and 
 that the (0) of Mr Wedgwood corresponds 
 to 1077^° of Fahrenheit. 
 
 From these data it is easy to reduce either 
 scale to the other through their whole range ; 
 and from such reduction it w ill appear, that 
 an interval of near 480° remains between 
 them, which the intermediate thermometer 
 serves as a measure for ; that Mr Wedg- 
 wood’s includes an extent of about 32000 of 
 Fahrenheit’s degrees, or about 54 times as 
 much as that between the freezing and boil- 
 ing points of mercury, by which mercurial 
 ones are naturally limited ; that it the scale 
 of Mr Wedgwood’s thermometer be produc- 
 ed downward, in the same manner as Fah- 
 renheit’s has been supposed to be produced 
 upward, for an ideal standard, the freezing 
 point of water would fall nearly on 8° below 
 (0) of Mr Wedgwood’s, and the freezing 
 point of mercury a iittle below 8-§° ; and 
 that, therefore, of the extent of now’ mea- 
 surable heat, there are about 5-10ths ot a 
 degree of his scale from the freezing of mer- 
 cury to the freezing of water ; 8° trom the 
 freezing of water to full ignition ; and 160° 
 above this to the highest degree he has hither- 
 to attained. 
 
 Mr Wedgwood concludes his account with 
 
 n 
 
 the following table of the effects of heat ihi 
 different substances, according to Fahren- 
 heit's thermometer, and his own. 
 
PYR 
 
 PYR 
 
 Fahr. Wedg. 
 
 Extremity of the scale of \ 302770 240° 
 his thermometer - 
 Greatest heat of his small 
 air furnace 
 Cast-iron melts 
 Greatest heat of a com- 
 mon smith’s forge - 
 Welding heat of iron, 
 greatest 
 
 Welding heat of iron, 
 least 
 
 Fine gold melts 
 Fine silver melts 
 Swedish copper melts 
 Brass melts 
 
 Heathy which his enamel 
 colours are burnt on 
 Bed-heat fully visible in 
 day- light 
 
 Red-heat fully visible in 
 the dark 
 
 Mercury boils - €00 
 
 Water boils - - 212 
 
 Vital heat - 97 
 
 Water freezes 32 
 
 Proof spirit freezes - 0 
 
 The point at which mercury') 
 congeals, consequently ^ 
 the limit of mercurial f 
 thermometers, about J 
 
 In a scale of iieat drawn lip in this man- 
 ner, the comparative extents of the different 
 departments of this grand and universal 
 agent are rendered conspicuous at a single 
 glance of the eye. We see at once, for in- 
 stance, how small a portion of it is concern- 
 ed in animal and vegetable life, and in the 
 ordinary operations of nature. From freez- 
 ing to vital heat is barely a five-hundredth 
 part of the scale ; a quantity so inconsider- 
 able, relatively to the whole, that in the higher 
 stages of ignition, ten times as much might 
 be added or taken away, without the least 
 difference being discernible in any of the 
 appearances from which the intensity of fire 
 has hitherto been judged of. Hence, at the 
 same time, we may be convinced of the 
 utility and importance of a physical measure 
 for these higher degrees of heat, and the 
 utter insufficiency of the common means of 
 discriminating and estimating their force. 
 Mr Wedgwood adds, that he has often found 
 differences, astonishing when considered as a 
 part of this scale, in the heats of his own 
 kilns and ovens, without being perceivable 
 by the workmen at the time, or till the ware 
 was taken out of the kiln. 
 
 * Since dry air augments in volume, 3-8ths 
 for 180 degrees, and, since its progressive 
 rate of expansion is probably uniform, by 
 uniform increments of heat, a pyrometer 
 might easily be constructed on this principle. 
 
 Form a bulb and tube of platinum, of exactly 
 the same form as a thermometer, and con- 
 nect with the extremity of the stem, at right 
 angles, a glass tube of uniform calibre, filled 
 with mercury, and terminating below in a 
 recurved bulb, like that of the Italian baio- 
 meter. Graduate the glass tube into a series 
 of spaces equivalent to 3-8ths of the total 
 volume of the capacity of the platina bulb, 
 with 3-4 ths of its stem. The other fourth 
 may be supposed to be little influenced by 
 the source of heat. On plunging the bulb 
 and 2-Sds of the stem into a furnace, the 
 depression of the mercury will indicate the 
 degree of heat. As the movement of the 
 column will be very considerable, it will be 
 scarcely worth while to introduce any cor- 
 rection for the change of the initial volume 
 by barometric variation. Or the instrument 
 might be made, with the recurved bulb seal- 
 
 O 1 
 
 ed, as in Professor Leslie’s differential ther- 
 mometers. The glass tube may be joined 
 by fusion to the platinum tube. Care must 
 be taken to let no mercury enter the plati- 
 num bulb. Should there he a mechanical 
 difficulty in making a bulb of this metal, 
 then a hollow cylinder of inch diameter, 
 with a platinum stem, like that of a tobacco- 
 pipe, screwed into it, will suit equally well.* 
 
 PvRorHORUs. By this name is denoted 
 an artificial product, which takes fire or 
 becomes ignited on exposure to the air. 
 Hence, in the German language, it has ob- 
 tained the name of luft-zunder, or air-tin- 
 der. It is prepared from alum by calcina- 
 tion, with the addition of various inflamma- 
 ble substances. Homberg was the first that 
 obtained it, which he did accidentally in the 
 year 1680, from a mixture of human excre- 
 ment and alum, upon w hich he was operat- 
 ing by fire. 
 
 The preparation is managed in the fol- 
 lowing manner. Three parts of alum are 
 mixed with from two to three parts of honey, 
 flour, or sugar ; and this mixture is dried 
 over the fire in a glazed bowl, or an iron 
 pan, diligently stirring it all the while with 
 an iron spatula. At first this mixture melts, 
 but by degrees it becomes thicker, swells 
 up, and at last runs into small dry lumps. 
 These are triturated to powder, and once 
 more roasted over the fire, till there is not 
 the least moisture remaining in them, and 
 the operator is well assured that it can li- 
 quefy no more : the mass now looks like 
 a blackish powder of charco al. For the 
 
 sake of avoiding the previous above-men- 
 tioned operation, from four to five parts of 
 burned alum may be mixed directly with 
 two of charcoal powder. This powder 
 is poured into a phial or matrass, with a 
 neck about six inches long. The phial, 
 which however must be filled three-quar- 
 ters full only, is then put into a crucible, 
 the bottom of which is covered with sand, 
 
 } 
 
 } 
 
 l 
 
 1 
 
 I 
 
 1 
 
 21877 
 
 160 
 
 17977 
 
 150 
 
 17527 
 
 125 
 
 15427 
 
 95 
 
 12777 
 
 90 
 
 5237 
 
 52 
 
 4717 
 
 28 
 
 4587 
 
 27 
 
 3807 
 
 21 
 
 1857 
 
 6 
 
 1077 
 
 0 
 
QUA 
 
 QUA 
 
 X 
 
 aid so much sand is put round the former, 
 that the upper part of its body also is co-' 
 vered with it to the height of an inch; upon 
 this the crucible, with the phial, is put into the 
 furnace, and surrounded with red-hot coals, 
 'i he fire, being now gradually increased till 
 the phial becomes red-hot, is kept up for the 
 space of about a quarter of an hour, or till 
 a black smoke ceases to issue from the 
 mouth of the phial, and instead of this a 
 sulphureous vapour exhales, which com- 
 monly takes lire. The fire is kept up till 
 the blue sulphureous flame is no longer to 
 be seen ; upon this the calcination must be 
 put an end to, and the phial closed for a 
 short time with a stopper of clay or loam. 
 But as soon as the vessel is become so cool 
 as to be capable of being held in the hand, 
 the phial is taken out of the sand, and the 
 powder contained in it transferred as fast as 
 possible from the phial, into a dry and stout 
 glass made warm, which must be secured 
 with a glass stopper. 
 
 We have made a very good pyrophorus by 
 simply mixing three parts of alum with one 
 of wheat-flour, calcining them in a common 
 phial till the blue flame disappeared; and 
 have kept it in the same phial, well stopped 
 with a good cork when cold. 
 
 If this powder be exposed to the atmo- 
 sphere, the sulnhuret attracts moisture from 
 the air, and generates sufficient heat to kindle 
 the carbonaceous matter mingled with it. 
 
 * Pyrope. A sub-species of dodecahe- 
 dral garnet. Colour dark blood-red, ap- 
 
 pearing yellowish by transmitted light. In 
 grains. Splendent. Fracture conchoidal. 
 Transparent. Refracts double. Scratches 
 quartz more readily than precious garnet 
 Sp. gr. 3.718. Its constituents are,' silica 
 40, alumina 28.5, magnesia 10, lime 3.5, 
 oxide of iron 1G.5, of manganese 0.25, oxide 
 of chrome 2, loss 1.25. — Klaproth . It oc- 
 curs in trap- tuff, at Ely, in Eifeshire ; and 
 in claystone in Cumberland. At Zceblitz, 
 Saxony, it is imbedded in serpentine. It is 
 highly valued as a gem in jewellery.* 
 
 * Pyrophvsaute. See Physalite.* 
 
 * Pyrosmai.ite. Colour liver-brown, in- 
 
 clining to pistachio- green. In lamellar con- 
 cretions, and in regular six-sided prisms, or 
 the same truncated. Shining. Fracture 
 uneven. Translucent. Semi-hard. Streak 
 brownish-white. Brittle. Sp, gr. S.08. It 
 is insoluble in water, but soluble in muriatic 
 acid with a small residuum of silica. It 
 gives out vapours of chlorine before the 
 blow-pipe, and becomes a magnetic oxide of 
 iron. Its constituents are, peroxide of iron 
 21.81, protoxide of manganese 21.14, sub- 
 muriate of iron 14.09, silica 35.85, lime 
 1.21, water and loss 5.9. — Hisinger. It 
 
 occurs in a bed of magnetic ironstone, along 
 with calcareous spar and hornblende, in 
 Bjelke’s mine in .Nordmark, near Philip- 
 stadt in Wermeland. It is a very singular 
 compound.* 
 
 * Pyrotartaric Acid. See Acid (Pyro- 
 tartaric).* 
 
 * Pyroxene. Augite.* 
 
 Q 
 
 Q UART ATI ON is an operation by which 
 _ J the quantity of one thing is made equal 
 toafourth partof thequantityof another thing. 
 Thus, when gold alloyed with silver is to be 
 parted, we are obliged to facilitate the action 
 of the aquafortis by reducing the quantity of 
 the former of these metals to one-fourth part 
 of the whole mass ; which is done by suffi- 
 ciently increasing the quantity of the silver, 
 if it be necessary. This operation is called 
 quartation, and is preparatory to the parting; 
 and even many authors extend this name to 
 the operation of parting. See Assay. 
 
 * Quartz. Professor Jameson divides 
 this mineral genus into two species; rliom- 
 boidal quartz, and indivisible quartz. 
 
 1. Rhomboidal quartz contains 14 sub- 
 species. 1. Amethyst. 2. Rock crystal. 
 
 o. Milk quartz. 4. Common quartz. 5. 
 Prase. 6. Cat’s eye. 7. Fibrous quartz. 
 8. Iron flint. 9. Ilornstone. 10. Flinty 
 slate. 11. Flint. 12. Calcedony. 13. 
 Heliotrope. 14. Jasper. 
 
 2. Indivisible quartz contains nine sub- 
 
 species : 1. Float- stone. 2. Quartz sinter. 
 
 5. Hyalite. 4. Opal. 5. Menilite. 6. 
 Obsidian. 7. Pitchstone. 8. Pearlstone. 
 9. Pumice-stone. We shall treat here of 
 the quartz sub-species. 
 
 1. Rose, or milk quartz. Colour rose-red. 
 and milk-white. Massive. Shining. Frac- 
 ture conchoidal. Translucent. It is pro- 
 bably silica, coloured with manganese. It 
 is found in Bavaria, where it occurs in beds 
 of quartz in granite, near Zwiesel, &c. 
 
 2. Common quartz. Colours white, grey, 
 and many others. Massive, disseminated, 
 imitative, in impressed forms, in supposititious, 
 and. true crystals. The If * ter are, a six-sided 
 prism, acuminated on both extremitie^by six 
 planes ; a simple six-sided pyramid, and a 
 double six-sided pyramid. Splendent to 
 glistening. Fracture coarse splintery, and 
 sometimes slaty. Translucent. It is one ot 
 the most abundant minerals in nature. 
 
 o. Fibrous quartz. Colours greenish and 
 yellowish-white. Massive, and in rolled 
 pieces. In curved fibrous concretions. Glim- 
 
IlAI 
 
 RA1 
 
 nicring and pearly. Fracture curved slaty. 
 Translucent on the edges. Nearly as hard 
 as quartz. Not very difficultly frangible. 
 Sp. gr. 3.123? It occurs on the banks of 
 the Mold are in Bohemia. 
 
 4. Quartz, or siliceous sinter . Of this there 
 are three kinds ; the common, opaline, and 
 pearly. 
 
 § 1 . Common. Colours greyish-white and 
 reddish-white. Massive and imitative. Dull. . 
 Fracture flat conchoidal. Translucent on 
 the edges. Semi-hard. Very brittle. Sp. 
 gr. 1.81. Its constituents are, silica 98, 
 alumina 1.5, iron 0.5. — Klapr . It occurs 
 abundantly round the hot springs in Ice- 
 Jand. 
 
 § 2. Opaline siliceous sinter. Colour yel- 
 
 lowish-white. Massive. Fracture conchoi- 
 dal. Glimmering. Translucent on the edges. 
 Seu\i-hard. Brittle. Adheres to the tongue. 
 It occurs at the hot springs in Iceland. It 
 resembles opal. 
 
 § o. Pearl sinter , or fwrite. Colour milk- 
 white. In imitative shapes. Lustre between 
 resinous and pearly. In thin concentric la- 
 mellar concretions. Fracture fine grained 
 uneven. * Translucent Scratches glass, but 
 not so hard as quartz. Brittle. Sp. gr. 
 1.917. Its constituents are, silica 94, alu- 
 mina 2, lime 4. — Santi. It has been found 
 in volcanic tuff and pumice, in the Vicen- 
 tine. See Rock Crystal.* 
 
 * Quercitron. See Dyeing.* 
 
 * Quicksilver. See Mercury.* 
 
 TO ADI CAL. That which is considered 
 
 ‘i. as constituting the distinguishing part 
 <*f an acid, by its union with the acidifying 
 principle, or oxygen, which is common to all 
 acids. Thus, sulphur is the radical of the 
 sulphuric and sulphurous acids. It is some- 
 times called the base of the acid, but base is 
 a term of more extensive application. 
 
 Radical Vinegar. See Acid (Acetic). 
 
 * Rain. Mr Luke Howard, who may 
 be considered as our most accurate scientific 
 meteorologist, is inclined to think, that rain 
 is in almost every instance (he result of the 
 electrical action of clouds upon each other. 
 This idea is confirmed by observations made 
 in various ways, upon the electrical state of 1 
 .clouds and rain ; and it is very probable that 
 a thunder-storm is only a more sudden and 
 sensible display of those energies, which, ac- 
 cording to the order observable in the crea- 
 tion in other respects, ought to be incessantly 
 and silently operating for more general and 
 beneficial purposes. 
 
 In the formation of the rain-cloud ( nim- 
 bus), two circumstances claim particular at- 
 tention ; the spreading of the superior masses 
 of cloud, in all directions, until they become 
 like the stratus, one uniform sheet ; and the 
 rapid motion, and visible decrease, of the 
 cumulus when brought under the latter. 
 The cirri also, which so frequently stretch 
 from the superior sheet upwards, and resem- 
 ble erected hairs, carry much the appearance 
 of temporary conductors for the electricity 
 extricated by the sudden union of minute 
 particles of vapour, into the vastly larger ones 
 that form the rain. By one experiment of 
 Cavallo’s, with a kite carrying 3G0 feet of 
 conducting string, in an interval between 
 -two showers, and kept up during rain, it 
 seems that the superior clouds possessed a 
 positive electricity before the rain, which on 
 
 the arrival of a large cumulus , gave place to 
 a very strong negative, continuing as long as 
 it was over the kite. We are not, however, 
 warranted from this to conclude the cumulus 
 which brings on rain always negative, as the 
 same effect might ensue from, a positive cu- 
 mulus uniting with a negative stratus. Yet 
 the general negative state of the lower at- 
 mosphere during rain, and the positive indi- 
 cations commonly given by the true stratus, 
 render this the more probable opinion. It is 
 not, however, absolutely, necessary to deter- 
 mine the several states of the clouds which 
 appear during rain, since there is sufficient 
 evidence in favour of the conclusion, that 
 clouds formed in different parts of the atmos- 
 phere, operate on each other, when brought 
 near enough, so as to occasion their partial 
 or entire destruction ; an effect which can 
 be attributed only to their possessing before- 
 hand, or acquiring at the moment, the oppo- 
 site electricities. 
 
 It may be objected, says Mr Howard, that 
 this explanation is better suited to the case 
 of a shower, than to that of continued rain, 
 for which it does not seem sufficient. If it 
 should appear, nevertheless, that the supply 
 of each kind of cloud is by any means kept 
 up in proportion to the consumption, the ob- 
 jection will be answered. Now, it is a well 
 known fact, that evaporation from the sur- 
 face of the earth and waters, often returns 
 and continues during rain, and consequently 
 furnishes the lower clouds, while the upper 
 are recruited from the quantity of vapour 
 brought by the superior current, and con- 
 ‘ tinually subsiding in the form of dew, as is 
 evident both from the turbidness of the at- 
 mosphere in rainy seasons, and the plentiful 
 deposition of dew in the nocturnal intervals 
 of rain. Neither is it pretended that elec- 
 tricity is any further concerned in the pro- 
 
ItAI 
 
 RAN 
 
 duction of rain, than as a secondary agent, 
 which modifies the effect of the two grand 
 predisposing causes, — a falling temperature, 
 and the influx of vapour. 
 
 Mr Dalton, who has paid much attention 
 
 to meteorology, has recently read before the 
 Manchester Society, an elaborate and inte- 
 resting memoir on rain, from which I shall 
 extract a table, and some observations. 
 
 Mean Monthly and Annual Quantities of Rain at various Places , being the Averages for 
 
 many years , by Mr Dalton. 
 
 
 Manchester, 
 S3 years. 
 
 Liverpool, 
 18 years. 
 
 Chatsworth, 
 16 years. 
 
 Lancaster, 
 20 years. 
 
 Kendal, 
 £5 years. 
 
 | Dumfries, 
 16 years. 
 
 Glasgow, 
 17 years. 
 
 1 London, 
 40 years. 
 
 Paris, 
 15 years. 
 
 ~ 03 
 
 U ° 
 
 General ave- 
 rage. 
 
 
 Inch. 
 
 Inch. 
 
 Inch. 
 
 Inch. 
 
 Inch. 
 
 Inch. 
 
 Inch. 
 
 Inch. 
 
 Fr. In. 
 
 Fr. In. 
 
 Inch. 
 
 Jan. 
 
 2.310 
 
 2.177 
 
 2. 1 96 
 
 3.461 
 
 5.299 
 
 3.095 
 
 1.595 
 
 1.464 
 
 1.228 
 
 2.477 
 
 2.530 
 
 Feb. 
 
 2.568 
 
 1.847 
 
 1.652 
 
 2.995 
 
 5. 1 26 
 
 2.837 
 
 1.741 
 
 1.250 
 
 1.232 
 
 1.700 
 
 2.295 
 
 Mar. 
 
 2.098 
 
 1.523 
 
 1.322 
 
 1.753 
 
 5.151 
 
 2.164 
 
 1.184 
 
 1.172 
 
 1.190 
 
 1.927 
 
 1.748 
 
 April. 
 
 2.010 
 
 2.104 
 
 2.078 
 
 2.180 
 
 2.986 
 
 2.017 
 
 0.979 
 
 1.279 
 
 1.185 
 
 2.686 
 
 1.950 
 
 May. 
 
 2.895 
 
 2.573 
 
 2.118 
 
 2.460 
 
 5.480 
 
 2.568 
 
 1.641 
 
 1.636 
 
 1.767 
 
 2.931 
 
 2.407 
 
 June. 
 
 2.502 
 
 2.816 
 
 2.286 
 
 2.512 
 
 2.722 
 
 2.974 
 
 1.54.3 
 
 1.758 
 
 1.697 
 
 2.562 
 
 2.515 
 
 July. 
 
 3. 697 
 
 3.663 
 
 3.006 
 
 4.140 
 
 4.959 
 
 3.256 
 
 2.505 
 
 2.448 
 
 1.800 
 
 1.882 
 
 3.1 15 
 
 Aug. 
 
 S.665 
 
 3.31 1 
 
 2.435 
 
 4.581 
 
 5.039 
 
 3. 1 99 
 
 2.746 
 
 -1.807 
 
 1-900 
 
 2.347 
 
 3.103 
 
 Sept. 
 
 3.281 
 
 3.654 
 
 2.289 
 
 3.751 
 
 4.874 
 
 4.350 
 
 1.617 
 
 1.842 
 
 1.550 
 
 4.140 
 
 3.135 
 
 Oct. 
 
 3. 922 
 
 3.724 
 
 5.079 
 
 4.151 
 
 5.439 
 
 4.143 
 
 2.297 
 
 2.092 
 
 1.780 
 
 4.741 
 
 3.537 
 
 Nov. 
 
 3.360 
 
 3.441 
 
 2.654 
 
 5.775 
 
 4.785 
 
 3.174 
 
 1.904 
 
 2.222 
 
 1.720 
 
 4.187 
 
 3. 1 20 
 
 Dec. 
 
 3.832 
 
 3. 288 
 
 2.569 
 
 5.955 
 
 6.084 
 
 5.142 
 
 1.981 
 
 1.736 
 
 1.600 
 
 2.397 
 
 3.058 
 
 
 36.140 
 
 34. 1 1 8 
 
 27.664 
 
 59.714 
 
 53.944 
 
 56.919 
 
 21.331 
 
 20.686 18.649 
 
 33.977| 
 
 u Observations on the Theory of Rain. 
 
 “ Every one must have noticed an obvious 
 connexion between heat and the vapour in 
 the atmosphere. Heat, promotes evapora- 
 tion, and contributes to retain the vapour 
 when in the atmosphere, and cold precipi- 
 tates or condenses the vapour. But these 
 facts do not explain the phenomenon of rain, 
 which is as frequently attended with an in- 
 crease as with a diminution of the tempera- 
 ture of the atmosphere. 
 
 “ The late Dr Hutton, of Edinburgh, was, 
 I conceive, the first person who published a 
 correct notion of the cause of rain. (See 
 Edin. Trans, vol. i. and ii. and Hutton’s 
 Dissertations, Sec. ) Without deciding whe- 
 ther vapour be simply expanded by heat, and 
 diffused through the atmosphere, or chemi- 
 cally combined with it, he maintained from 
 the phenomena that the quantity of vapour 
 capable of entering into the air increases in 
 a greater ratio than the temperature; and 
 lienee he fairly infers, that whenever two vo- 
 lumes of air of different temperatures are 
 mixed together, each being previously satu- 
 rated with vapour, a precipitation of a por- 
 tion of vapour must ensue, in consequence 
 of the mean temperature not being able to 
 support the mean quantity of vapour. 
 
 “ The cause of rain, therefore, is now, I con- 
 sider, no longer an object of doubt. If two 
 masses of air of unequal temperatures, by 
 the ordinary currents of the winds, are inter- 
 mixed! when saturated with vapour, a preci- 
 
 pitation ensues. If the masses are under 
 saturation, then less precipitation takes place, 
 or none at all, according to the degree. Al- 
 so the warmer the air, the greater is the 
 quantity of vapour precipitated in like cir- 
 cumstances. Hence the reason why rains 
 are heavier in summer than winter, and in 
 warm countries than in cold. 
 
 “ We now inquire into the cause why less 
 rain falls in the first six months of the year 
 than in the last six months. The whole 
 quantity of water in the atmosphere in Janu- 
 ary is usually about three inches, as appears 
 from the dew point, which is then about 32°. 
 Now the force of vapour at that temperature 
 is 0.2 of an inch of mercury, which is equal 
 to 2.8 or three inches of water. The dew 
 point in July is usually about 58° or 59°, 
 corresponding to 0.5 of an inch of mercury, 
 which is equal to seven inches of water ; the 
 difference is four inches of w f ater, which the 
 atmosphere then contains more than in the 
 former month. Hence, supposing the usual 
 intermixture of currents of air in both the 
 intervening periods to be the same, the rain 
 ought to be four inches less in the former 
 period of the year than the average, and four 
 inches more in the latter period, making a 
 difference of eight inches between the two 
 periods, which nearly accords with the pre- 
 ceding: observations.”* 
 
 Rancidity. The change which oils un- 
 dergo by exposure to the air. 
 
 The rancidity of oils is probably an effect 
 
RES 
 
 RET 
 
 analogous to tho oxidation of metals. It 
 essentially depends on the combination of 
 oxygen with the extractive principle, which 
 is naturally united with the oily principle. 
 This inference is proved by attending to the 
 processes used to counteract or prevent the 
 rancidity of oils. 
 
 Reagent. In the experiments of chemi- 
 cal analysis, the component parts of bodies 
 may either be ascertained in quantity as well 
 as quality, by the perfect operations of the 
 laboratory, or their quality alone may be de- 
 tected by the operations of certain bodies 
 called reagents. Thus the infusion of galls 
 is a reagent, which detects iron by a dark 
 purple precipitate ; the prussiate of potash 
 exhibits a blue with the same metal, &c. See 
 Analysis, and Waters (Mineral)* 
 
 * Realgar. Sulphurct of arsenic, a na- 
 tive ore.* 
 
 Receiver. Receivers are chemical ves- 
 sels, which are adapted to the necks or beaks 
 of retorts, alembics, and other distillatory 
 vessels, to collect, receive, and contain the 
 products of distillations. 
 
 * Red Chalk. A kind of clay iron- 
 stone. * 
 
 * Reddle. Red chalk.* 
 
 Reduction, or Revivification, This 
 
 word, in its most extensive sense, is applica- 
 ble to all operations by which any substance 
 is restored to its natural state, or which is 
 considered as such : but custom confines it 
 to operations by which metals are restored to 
 their metallic state, after they have been de- 
 prived of this, either by combustion, as the 
 metallic oxides, or by the union of some he- 
 terogeneous matters which disguise them, as 
 fulminating gold, luna cornea, cinnabar, and 
 other compounds of the same kind. These 
 reductions are also called revivifications. 
 
 Refrigeratory. See Laboratory. 
 
 Regulus. The name regulus was given 
 i>y chemists to metallic matters when se- 
 parated from other substances by fusion. 
 This name was introduced by alchemists, 
 who, expecting always to find gold in the 
 metal collected at the bottom of their cru- 
 cibles after fusion, called this metal, thus 
 collected, regulus, as containing gold, the 
 king of metals. It was afterward applied to 
 the metal extracted from the ores of the semi- 
 metals, which formerly bore the name that is 
 now given to the semi-metals themselves. 
 Thus we had regulus of antimony, regulus 
 of arsenic, and regulus of cobalt. 
 
 Resin. The name resin is used to de- 
 note solid inflammable substances, of veo-eta- 
 ble origin, soluble in alcohol, usually afford- 
 ing much soot by their combustion. They 
 are likewise soluble in oils, but not at all in 
 water ; and are more or less acted upon by 
 the alkalis. 
 
 All the resins appear to be nothing else 
 but volatile oils, rendered concrete by their 
 
 combination with oxygen. The exposure of 
 these to the open air, and the decomposition 
 of acids applied to them, evidently prove this 
 conclusion. 
 
 There are some among the known resins 
 which are very pure, and perfectly soluble 
 in alcohol, such as the balsam of Mecca and 
 of Capivi, turpentines, tacamahaca, elemi : 
 others are less pure, and contain a small 
 portion of extract, which renders them not 
 totally soluble in alcohol ; such are mastic, 
 sandarach, guaiacum, labdanum, and dra- 
 gon’s blood. 
 
 What is most generally knowm by the 
 name of resin simply, or sometimes of yel- 
 low resin, is the residuum left after distill- 
 ing the essential oil, from turpentine. If 
 this be urged by a stronger fire, a thick 
 balsam, of a dark reddish colour, called 
 balsam of turpentine, comes over ; and the 
 residuum, w'hich is rendered blackish, is 
 called black resin, or colophony. 
 
 * Resin, analyzed by MM. Gay Lussac 
 and Thenard, was found to consist of 
 Carbon, 75.944 
 
 Hydrogen, 10.719") w^ater 15.156 
 Oxygen, 13.337 ) hydrogen in excess 8.9.* 
 
 * Respiration. A function of animals, 
 which consists in the alternate inhalation of 
 a portion of air into an organ called the 
 lungs, and its subsequent exhalation. The 
 venous blood, which enters the lungs, from 
 the pulmonary artery, is charged with car- 
 bon, to which it owes its dark purple colour. 
 When the atmospherical oxygen is applied 
 to the interior of the air vesicles of the lungs, 
 it combines with the carbon of the blood, 
 forms carbonic acid, which to the amount of 
 from 4.5 to 8 per cent of the bulk of air in- 
 spired, is immediately exhaled. It does not 
 appear that any oxygen or azote is absorbed 
 by the lungs in respiration ; for the volume 
 of carbonic acid generated, is exactly equal 
 to that of the oxygen which disappears. 
 Now, we know that carbonic acid contains 
 its own volume of oxygen. It is probable 
 that the quantity of carbonic acid, produced 
 on the lungs, varies in different individuals, 
 and in the same individual under different 
 circumstances. The change of the blood, 
 from the purple venous to the bright red ar- 
 terial, seems owing to the discharge of the 
 carbon. An ordinary sized man consumes 
 about 46 thousand cubic inches of oxygen 
 per diem; equivalent to 125 cubic feet of 
 air. He makes about 20 respirations in a 
 minute ; or breathes twice, for every seven 
 pulsations. l)r Prout and Dr Fyfe found, 
 that after swallowing intoxicating liquors, 
 the quantity of carbonic acid formed in res- 
 piration was diminished. The same thing 
 happens under a course of mercury, nitric 
 acid, or vegetable diet.* 
 
 * Retinite. Retin-asphalt. — Hatchett. 
 
 Colour yellowish and reddish-brown. 
 
KUO 
 
 ROC 
 
 Massive, in angular pieces and thick crusts. 
 Surface rough. Glistening, resinous. Frac- 
 ture uneven. Translucent. Soft. Brittle. 
 At first elastic, but becomes rigid by expo- 
 sure to the air. Sp. gr. 1.135. On a hot 
 iron, it melts, smokes and burns, with a fra- 
 grant odour ; soluble in potash, and par- 
 tially in spirit of wine. Its constituents 
 are, resin 55, asphalt 42, earth 3. It is 
 found at Bovey Tracey in Devonshire, ad- 
 hering to brown coal.* 
 
 Retort. Retorts are vessels employed 
 for many distillations, and most frequently 
 for those which require a degree of heat su- 
 perior to that of boiling water. This vessel 
 is a kind of bottle with a long neck, so bent, 
 that it makes with the belly of the retort an 
 angle of about sixty degrees. From this 
 form they have probably been named re- 
 torts. The most capacious part of the retort 
 Ls called its belly. Its upper part is called 
 the arch or roof of the retort, and the bent 
 part is the neck. 
 
 * Reussite. Colour white. As a mealy 
 efflorescence, and crystallized, in flat six- 
 sided prisms and acicular crystals. Shining. 
 Fracture conchoidal. Soft. Its constitu- 
 ents are, sulphate of soda 66.04, sulphate of 
 magnesia 31.35, muriate of magnesia 2. ’ 9, 
 and sulphate of lime 0.42. — lieuss. It is 
 found as an efflorescence on the surface, in 
 the country round Sedlitz and Saidschutz. * 
 
 Reverberatory. See Laboratory. 
 
 Rhodium. A new metal discovered 
 among the grains of crude platina by Dr 
 Wollaston. The mode of obtaining it in the 
 state of a triple salt combined with muriatic 
 acid and soda, has been given under the ar- 
 ticle Palladium. This may be dissolved in 
 water, and the oxide precipitated from it in 
 a black powder by zinc. 
 
 The oxide exposed to heat continues black ; 
 but with borax it acquires a white metallic 
 lustre, though it remains infusible. Sul- 
 phur, or arsenic, however, renders it fusible, 
 and may afterward be expelled by conti- 
 nuing; the heat. The button however is not 
 malleable. Its specific gravity appears to 
 exceed 1 1. 
 
 Rhodium unites easily with every metal 
 that has been tried, except mercury. With 
 gold or silver it forms a very malleable alloy, 
 not oxidated by a high degree of heat, but 
 becoming incrusted with a black oxide when 
 slowly cooled. One-sixth of it docs not per- 
 ceptibly alter the colour of gold, but renders 
 it much less fusible. Neither nitric nor 
 nitro-muriatic acid acts on it in either of 
 these alloys; but if it be fused with three 
 parts of bismuth, lead, or copper, the alloy 
 is entirely soluble in a mixture of nitric acid 
 with two parts of muriatic. 
 
 The oxide was soluble in every acid Dr 
 Wollaston tried. The solution in muriatic 
 acid did not crystallize by evaporation. Its 
 
 residuum formed a rose-coloured solution 
 with alcohol. Muriate of ammonia and of 
 soda, and nitrate of potash, occasioned no 
 precipitate in the muriatic solution, but 
 formed with the oxide triple salts, which 
 were insoluble in alcohol. Its solution in 
 nitric acid likewise did not crystallize, but 
 silver, copper, and other metals precipitated 
 it. 
 
 1 he solution of the triple salt with mu- 
 riate of soda was not precipitated by muriate, 
 carbonate, or hydrosulphuret of ammonia, by 
 carbonate or ferroprussiate of potash, or by 
 carbonate of soda. The caustic alkalis how- 
 ever throw down a yellow oxide, soluble in 
 excess of alkali; and a solution of platina 
 occasions in it a yellow precipitate. 
 
 The title of this product to be considered 
 as a distinct metal has been questioned ; but 
 the experiments of Dr Wollaston have since 
 been confirmed by Descotils. — Philos . Trans. 
 
 * Rhoetizite. Colour white. Massive, 
 and in radiated concretions. Glistening and 
 pearly. Fragments splintery. Feebly trans- 
 lucent on the edges. In other characters, 
 the same as cyanite. It occurs in primitive 
 rocks, with quartz, &c. at Ffitzsci in the 
 Tyrol.* 
 
 * Rhomb Spar. Colour greyish-white. 
 Massive, disseminated, and crystallized in 
 rhomboids, in which the obtuse angle is 
 106° 15'. Splendent, between vitreous and 
 pearly. Cleavage threefold oblique angular. 
 Fracture imperfect conchoidal. Harder than 
 calcareous spar ; sometimes as hard as fluor. 
 Brittle. Sp. gr. 2.8 to 5.2. It effervesces 
 feebly with acids. Its constituents are, car- 
 bonate of lime 56.6, carbonate of magnesia 
 42, with a trace of iron and manganese. — 
 Murray. It occurs imbedded in chlorite 
 slate, limestone, &c. It is found on the 
 banks of Loch Lomond ; near Newton- Stew- 
 art in Galloway; in compact dolomite in 
 the Isle of Man and the North of England. 
 It has been called bitter spar and murical- 
 cite. * 
 
 Rochelle Salt. Tartrate of potash and 
 soda. See Acid (Tartaric). 
 
 * Rock Butter. Colour yellowish-white. 
 Massive and tuberose. Glimmering. Frac- 
 ture straight foliated. Translucent on the 
 edges. Feels rather greasy. Easily fran- 
 gible. It is alum mixed with alumina and 
 
 O 
 
 oxide of iron. It oozes out of rocks that 
 contain alum. It occurs at the Hurlett 
 alum- work, near Paisley.* 
 
 * Rock Cork. See Asbestus.* 
 
 * Rock Crystal. Colour white and 
 brown. In rolled pieces, and crystallized. 
 The primitive form is a rhomboid of 94° 15' 
 and 85° 45'. The secondary forms are, an 
 equiangular six-sided prism, rather acutely 
 acuminated on both extremities by six planes, 
 which are set on the lateral planes; a double 
 six-sided pyramid ; an acute simple six-sided 
 
SAL 
 
 pyramid ; an acute double three-sided pyra- 
 mid. Splendent. Fracture perfect con- 
 choidal. Transparent or translucent. Re- 
 fracts double, feebly. Scratches felspar. 
 Rather easily frangible. Sp. gr. 2.6 to 2.88. 
 When two pieces are rubbed against each 
 other, they become phosphorescent, and ex- 
 hale an electric odour. Its constituents are, 
 silica 99f, and a trace of ferruginous alu- 
 mina. — Bucliolz. Some chemists maintain, 
 that it has one or two per cent of moisture. 
 Crystals of great size and beauty are found 
 in Arran, in drusy cavities in granite ; but 
 the finest are found in the neighbourhood of 
 Cairngorm in Aberdeenshire, where they 
 occur in granite, or in alluvial soil, along 
 with beryl and topaz ; and in the secondary 
 greenstone of Burntisland in Fifeshire. The 
 most magnificent groupes of crystals come 
 from Dauphiny. 
 
 The varieties enclosing crystals of titani- 
 um, the Venus hair-stones of amateurs, and 
 those containing actynolite, or the Thetis 
 hair-stones, are in much repute, and sell at 
 a considerable price. — Jameson .* 
 
 * Rock Salt. Hexahedral rock salt. 
 
 ] . Foliated. Colours white and grey. 
 Massive, disseminated, and crystallized in 
 cubes. Splendent and resinous. Cleavage 
 threefold rectangular. Fracture conchoidak 
 
 * QACLACTATES. See Acid (Sac- 
 
 O lactic).* 
 
 * Safflower. See Carthamus.* 
 
 * Sagenite. Acicular Rutile.* 
 
 * Sahlite. Colours greenish-grey, and 
 green of other shades. Massive, in straight 
 lamellar concretions, and crystallized ; in a 
 broad rectangular four-sided prism, approach- 
 ing the tabular form, or truncated on the 
 lateral edges. Splendent on the principal 
 fracture ; on the cross fracture, dull. Cleav- 
 age fivefold. Fracture uneven. Translu- 
 cent on the edges. Harder than augite. 
 Rather brittle. Sp. gr. 8.22 to 3.47. It 
 melts with great difficulty. Its constituents 
 are, silica 53, magnesia 1 9, alumina 5, lime 
 20, iron and manganese 4. — Vauquelin. It 
 occurs in the Island of Unst in Shetland ; in 
 granular limestone in the Island of Tiree ; 
 and in Glentilt. It is a sub-species of oblique 
 edged augite.* 
 
 Sal Alembroth. A compound muriate 
 of mercury and ammonia. See Alem- 
 broth. 
 
 * Sal Ammoniac (Native) ; of which 
 there are two kinds, the volcanic and con- 
 choidal . 
 
 1. Volcanic . Colour yellowish and grey- 
 ish-white. In efflorescences, imitative shapes, 
 
 SAL 
 
 Fragments cubic. Translucent. As hard 
 as gypsum. Feels rather greasy. Brittle. 
 It has a saline taste. Sp. gr. 2.1 to 2.2. 
 
 2. Fibrous. Colour white. Massive, and 
 in fibrous concretions. Glistening, resinous. 
 Fragments splintery. Translucent. It de- 
 crepitates when heated. The constituents of 
 Cheshire rock salt, in 1000 parts, are, muri- 
 ate of soda 98 3 sulphate of lime 6-J, muri- 
 ate of magnesia O.qqjj muriate of lime 0.y^> 
 insoluble matter 10. — Henry . 
 
 The greatest formation of rock salt is in 
 the muriatiferous clay. The salt is occasion- 
 ally associated with thin layers of anhydrite, 
 stinkstone, limestone, and sandstone. The 
 principal deposite in Great Britain is in 
 Cheshire. The beds alternate with clay and 
 marie, which contains gypsum. It occurs also 
 at Droitwich, in Worcestershire. For other 
 localities, see Professor Jameson’s Miner- 
 alogy, Hi. 6.* 
 
 * Rock Wood. See Asbestos.* 
 
 * Roestone. See Limestone.* 
 
 * Rose Q,uartz. See Quartz.* 
 
 * Rubelite. Red tourmalin.* 
 
 * Ruby. See Sapphire.* 
 
 * Ruby-spinel. See Spinel.* 
 
 * Rust. Red oxide of iron.* 
 
 * Rutile. An ore of titanium.* 
 
 and crystallized ; in an octohedron ; rectan- 
 gular four-sided prism, acuminated with 
 four planes, set on the lateral planes ; a cube 
 truncated on the edges ; a rhomboidal dode- 
 cahedron, and a double eight- sided pyramid, 
 acuminated with four planes. Shining. 
 Cleavage in the direction of the planes of 
 the octohedron. From transparent to opaque. 
 Harder than talc. Ductile and elastic. Sp. 
 gr. 1.5 to 1.6. Taste sharp and urinous. 
 When rubbed with quicklime, it exhales am- 
 monia. Its constituents are, sal ammoniac 
 99.5, muriate of soda 0.5. — Klaproth. It 
 occurs in the vicinity of burning beds of 
 coal, both in Scotland and England. It is 
 met with at Solfaterra, Vesuvius, JEtna, &c. 
 
 2. Conchoidal. It occurs in angular pieces, 
 and consists of, sal ammoniac 97.5, sulphate 
 of ammonia 2.5. — Klaproth A It is said to 
 occur, along with sulphur, in beds of indu- 
 rated clay or clay-slate, in the country of 
 Bucharia. — Jameson. See Acid (Muriatic). 
 
 Sal Ammoniac. Muriate of ammonia. 
 
 Sal Ammoniac (Secret). Sulphate of 
 ammonia, so called by its discoverer Glau- 
 ber. 
 
 Sal Catiiarticus Amarus. Sulphate of 
 magnesia. 
 
 Sal de Duoqus. Sulphate of potash. 
 
SAL 
 
 SAL 
 
 Sal Diureticus. Acetate of potash. 
 
 Sal Gem. Native muriate of soda. 
 
 Sal Glauberi. Sulphate of soda. 
 
 Sal Martis. Green sulphate of iron. 
 
 Sal Mirabile, or Sal Mirabile Glau- 
 beri. Sulphate of soda. 
 
 Sal Mirabile Perlatum, or Sal Per- 
 latum. Phosphate of soda. 
 
 Sat, Polychrest Glaseri. Sulphate of 
 potash. 
 
 Sal Prunella. Nitrate of potash, cast 
 into flat cakes or round balls, after fusion. 
 
 * Salifiable Bases, are the alkalis, and 
 those earths and metallic oxides, which have 
 the power of neutralizing acidity, entirely or 
 in part, and producing salts.* 
 
 Saliva. The fluid secreted in the mouth, 
 which flows in considerable quantity during 
 a repast, is known by the name of saliva. 
 
 Saliva, beside water, which constitutes at 
 least four-fifths of its bulk, contains the fol- 
 lowing ingredients: — 
 
 1. Mucilage, 
 
 2. Albumen, 
 
 3. Muriate of soda, 
 
 4. Phosphate of soda, 
 
 5. Phosphate of lime, 
 
 6. Phosphate of ammonia. 
 
 But it cannot be doubted, that, like all the 
 other animal fluids, it is liable to many 
 changes from disease, &c. Brugnatelli 
 found the saliva of a patient labouring under 
 an obstinate venereal disease impregnated 
 with oxalic acid. 
 
 The concretions which sometimes form in 
 the salivary ducts, &c. and the tartar or 
 bony crust, which so often attaches itself to 
 the teeth, are composed of phosphate of 
 lime. 
 
 Salmiac. A word sometimes used for sal 
 ammoniac. 
 
 * Salt. This term has been usually em- 
 ployed to denote a compound, in definite 
 proportions, of acid matter, with an alkali, 
 earth, or metallic oxide. When the propor- 
 tions of the constituents are so adjusted, that 
 the resulting substance does not affect the 
 colour of infusion of litmus, or red cabbage, 
 it is then called a neutral salt. When the 
 predominance of acid is evinced by the red- 
 dening of these infusions, the salt is said to 
 be acidulous, and the prefix super , or bi , is 
 used to indicate this excess of acid. If, on 
 the contrary, the acid matter appears to be 
 in defect, or short of the quantity necessary 
 for neutralizing the alkalinity of the base, 
 the salt is then said to be with excess of 
 base, and the prefix sub is attached to its 
 name. 
 
 The discoveries of Sir II. Davy have how- 
 ever taught us to modify our opinions con- 
 cerning saline constitution. Many bodies, 
 such as culinary salt, and muriate of lime, to 
 which the appellation of salt cannot be re- 
 fused, have not been prgyed to contain either 
 
 acid or alkaline matter; but must, according! 
 to the strict logic of chemistry, lie regardet 1 
 as compounds of chlorine with metals. 
 
 That great chemist remarks, that very few 1 
 of the substances which have been always- 1 
 considered as neutral salts, really contain, ir I 
 their dry state, the acids and alkalis from I 
 which they were formed. According to hisl 
 views, the muriates and fluates must be ad-| 
 mitted to contain neither acids, nor alkaline I 
 bases. Most of the-prussiates (or prussides)| 
 are shewn by M. Gay Lussac to be in the I 
 same case. Nitric and sulphurio acids can-1 
 not be procured from the nitrates and sul-J 
 phates without the intervention of bodiesJ 
 containing hydrogen ; and if nitrate of am- I 
 monia were to be judged of from the results ] 
 of its decomposition, it must be regarded as ] 
 a compound of water and nitrous oxide. To I 
 this position it might perhaps be objected, 
 that dry sulphate of iron yields sulphuric 
 acid by ignition in a retort, while oxide of 
 iron remains. Only those acids, says he, 
 which are compounds of oxygen and inflam- 
 mable bases, appear to enter into combina- ] 
 tion with the fixed alkalis and alkaline earths I 
 without alteration, and it is impossible to 
 define the nature of the arrangement of the 
 elements in their neutral compounds. The 
 phosphate and carbonate of lime have much 
 less of the characters attributed to neutro- 
 saline bodies than chloride of calcium (mu- 
 riate of lime), and yet this last body is not 
 known to contain either acid or alkaline 
 matter. M. Gay Lussac supposes, that a 
 chloric acid, without water or hydrogen, of 
 one prime proportion of chlorine, and five of 
 oxygen, exists in all the hyperoxvmuriates 
 (chlorates), but he does not support his pro- 
 position by any proof. The hyperoxymuri- 
 ates w r ere shew’n by Sir II. Davy, in 1811, 
 to be composed of one prime of chlorine, one 
 of a basis, and six of oxygen. Now' hydro- 
 gen, in the liquid chloric acid of 31. Gay 
 Lussac, may be considered as acting the 
 part of a base ; and to be exchanged for po- 
 tassium in the salt hypothetically called chlo- 
 rate of potassium. It is an important cir- 
 cumstance in the law of definite proportions, 
 that wdien one metallic or inflammable basis 
 (potassium or hydrogen, for example), com- 
 bines with certain proportions of a com- 
 pound as hexoxygenated chlorine, all the 
 others combine with the same proportions. 
 
 M. Gay Lussac states, that if the chloric 
 acid be not admitted as a pure combination 
 of chlorine and oxygen, neither can the hv- 
 dronitric or hydrosulphuric acids be admit- 
 ted as pure combinations of oxygen. 1 his 
 is perfectly obvious. An acid composed of 
 five proportions of oxygen, and one of nitro- 
 gen, is altogether hypothetical ; and it is 
 a simple statement of facts to say, that liquid 
 nitric acid is a compound ot one prime equi- 
 valent of hydrogen, one of azote, and six of 
 
SAL 
 
 SAL 
 
 oxygen. (Such acid has a sp. gr. considera- 
 bly greater than 1.50). The only difference 
 therefore, between nitre and Iiyperoxymuriate 
 of potash, is, that one contains a prime of 
 azote, and the other a prime of chlorine. — 
 Thus, 
 
 Nitrate oj' potash* 
 1 prime azote, 
 
 6 primes oxygen, 
 
 1 prime potassium. 
 
 Chlorate of potash. 
 1 prime chlorine, 
 
 6 primes oxygen, 
 
 1 prime potassium. 
 
 In each, substitute hydrogen for its kindred 
 combustible, potassium, and you have the li- 
 quid acids. 
 
 The chloriodic acid, the chlorocarbonous, 
 and the binary acids, containing hydrogen, 
 as muriatic and hydriodic, combine with am- 
 monia without decomposition, but they ap- 
 pear to be decomposed in acting upon the 
 fixed alkalis, or alkaline earths ; and yet 
 the solid substances they form, have all the 
 characters which were formerly regarded as 
 peculiar to neutral salts, consisting of acids 
 and alkalis, though they none of them con- 
 tain the acid, and only the two first of the 
 series contain the alkalis from which they 
 are formed. The preceding views of saline 
 constitution, seem to be perfectly clear and 
 satisfactory ; and place in a conspicuous 
 light, the paramount logic of the English 
 chemist. 
 
 The solubility of salts in water, is their 
 most important general habitude. In this 
 menstruum they are usually crystallized ; 
 and by its agency they are purified and se- 
 parated from one another, in the inverse or- 
 der of their solubility. The most extensive 
 series of experiments on the solubility of 
 salts, which has been published, is that of 
 Hussenfratz, contained in the 27th, 28th, 
 and 31st volumes of the Annales de Chimie. 
 Dr Thomson has copied them into the third 
 volume of his System ; and I should also 
 have willingly followed the example, were I 
 not aware from my own researches, that se- 
 veral of Hassenfratz’s results are erroneous. 
 It is four years since I commenced a very 
 extensive train of experiments on this sub- 
 ject, so important to the practical chemist, 
 but unforeseen obstructions have hitherto 
 prevented their completion. Many of Has- 
 senfratz’s determinations, however, are very 
 nearly correct. But his statement of the 
 relation between the density of slaked lime, 
 and the proportion of its combined water, 
 is so absurd, that I wonder that a person 
 of his reputation should have published it, 
 and that Dr Thomson should have embodied 
 it in his System. In one experiment, 10000 
 grains of lime, sp. gr. 1.5949, combined 
 with 1620 of water, give a hydrate of sp. gr. 
 1.4877; and, in another, 10000 grains of 
 lime, sp. gr. 1.3175, combined with 1875 of 
 water, form a hydrate of sp. gr. 0.972. 
 Four parts of lime, sp. gr. 1.4558, combined 
 
 26 
 
 with 1 of water, are stated to yield a hydrate 
 of sp. gr. 1.400; and with 2 of w'ater, of 
 specific gravity 0.8983 ! Now, the last pro- 
 portion forms a mass greatly denser than 
 water, instead of being much lighter than 
 proof spirits. 
 
 “ Mr Kirwan has pointed out,” says Dr 
 Thomson, “ a very ingenious method of esti- 
 mating the saline contents of a mineral water 
 wdiose specific gravity is known ; so that the 
 error does not exceed one or tw'o parts in the 
 hundred. The method is this : — subtract the 
 specific gravity of pure water from the speci- 
 fic gravity of the mineral water examined 
 (both expressed in whole numbers), and 
 multiply the remainder by 1.4. The pro- 
 duct is the saline contents, in a quantity of 
 the water, denoted by the number employed 
 to indicate the specific gravity of distilled 
 water. Thus, let the water be of the speci- 
 fic gravity 1.079, or in w’hole numbers 
 1079. Then the specific gravity of distilled 
 water wfill be 100. And 1079 — 1000 X 
 1.4 = 110.6 = saline contents in 1000 
 parts of the water in question ; and, conse- 
 quently, 11.06 (erroneously printed 110.6), 
 in 100 parts of the same water.” Divested 
 of its superfluous tautology, this rule is ; 
 multiply by 140 the decimal part of the 
 number, representing the sp. gr. of the saline 
 solution, and the product is the dry salt in 
 100 grains. “ This formula,” adds the 
 Doctor, “ will often be of considerable use, 
 as it serves as a kind of standard to w hich 
 w'e may compare our analysis.” System , 
 
 vol. iii. p. 231. 
 
 In the article Caloric of this Dictionarv, 
 the reader will find the following passage : — . 
 “ I did not so far violate the rules of phi- 
 losophy, as to make a general inference from 
 a particular case, a practice, it must be con- 
 fessed, too common with some chemical 
 writers.” The present instance is very in- 
 structive. For Mr Kirwan, the original au- 
 thor of this formula, I entertain the highest 
 esteem. He devoted himself, with distin- 
 guished zeal, candour, and success, to the 
 cultivation of chemistry, and, when he wrote, 
 an empirical rule like the preceding w'as a 
 very pardonable error. But, at the present 
 day, it is ridiculous to hold it forth as a kind 
 of' standard. With solutions of nitre and 
 common salt, it gives tolerable approxima- 
 tions; and hence, I fancy that from these 
 solutions the rule must have been framed. 
 But for solution of sulphate of soda, this 
 kind of standard gives a quantity of dry salt 
 nearly double , and for that of sal ammoniac, 
 less than one-half i he real quantity present. 
 
 M. Gay Lussac has recently published in 
 the Ann. dc Chimie et Fhys. xi. 296, an 
 important memoir on the solubility of salts, 
 from which I shall make a few extracts. 
 
 One is astonished, says this excellent che- 
 
SAL 
 
 SAL 
 
 mist, on perusing the different chemical 
 works, at the inaccuracy of our knowledge 
 respecting the solubility of the salts. They 
 satisfy themselves with the common observa- 
 tion, that the salts are more soluble in hot 
 than in cold water, and with the solubility of 
 a few of them at a temperature usually very 
 uncertain ; yet it is upon this property of 
 salts that their mutual decomposition, their 
 separation, and the different processes for 
 analyzing them depend. As a chemical pro- 
 cess, the solution of the salts deserves pecu- 
 liar attention ; for though the causes to which 
 it is due are the same as those which produce 
 other combinations, yet their effects are not 
 similar. It is to be wished that this interest- 
 ing part of chemistry, after remaining so 
 long in vague generalities, may at last enter 
 the domain of experiment, and that the solu- 
 bility of each body may be determined, net 
 merely for a fixed temperature, but for vari- 
 able temperatures. In the natural sciences, 
 and especially in chemistry, general conclu- 
 sions ought to be the result of a minute 
 knowledge of particular facts, and should not 
 precede that knowledge. It is only after 
 having acquired this knowledge, that we can 
 be sure of the existence of a common type, 
 and that we can venture to state facts in a 
 general manner. 
 
 The determination of the quantity of salt 
 which water can dissolve is not a very diffi- 
 cult process. It consists in saturating the 
 water exactly with the salt whose solubility 
 we wish to know at a determinate tempera- 
 ture, to weigh out a certain quantity of that 
 solution, to evaporate it, and weigh the saline 
 residue. However, the saturation of water 
 may present considerable uncertainty, and 
 before going further it is proper to examine 
 the subject. 
 
 We obtain a perfectly saturated saline so- 
 lution in the two following ways : By heat- 
 ing the water with the salt, and allowing it 
 to cool to the temperature whose solubility is 
 wanted ; or by putting into cold water a 
 great excess of salt, and gradually elevating 
 the temperature. In each case, it is requi- 
 site to keep the final temperature constant 
 for two hours at least, and to stir the saline 
 solution frequently, to be quite sure of its 
 perfect saturation. By direct experiments 
 made with much care, M. Gay Lussac as- 
 certained that these two processes give the 
 very same result, and that of consequence 
 they may be employed indifferently. 
 
 Yet Dr Thomson says, he found that 
 water retains more oxide of arsenic when 
 saturated by cooling, than when put in con- 
 tact with the oxide without any elevation ot 
 temperature ; but the reason I am persuaded 
 was, that he employed too little oxide of 
 arsenic relatively to the water, and that he 
 did not prolong the contact sufficiently. \\ e 
 
 perceive in fact, on a little reflection, that 
 saturation follows in its progress a decreas- 
 ing geometrical progression, and that the 
 time necessary for completing it depends 
 upon the surface of contact of the solvent 
 and the body to be dissolved. 
 
 It happens often that the solution of a 
 salt which does not crystallize, and which, 
 for that reason, we consider as saturated, 
 yields saline molecules to the crystals of the 
 same nature plunged into it ; and it has been 
 concluded from this, that the crystals of a 
 salt impoverish a solution, and make it sink 
 below its true point of saturation. The fact 
 is certain ; it is even very general ; but I 
 am of opinion that ft has been ill explained. 
 
 Saturation in a saline solution of an in- 
 variable temperature, is the point at which 
 the solvent, always in contact with the salt, 
 can neither take up any more, nor let go any 
 more. This point is the only one which 
 should be adopted, because it is determined 
 by chemical forces, and because it remains 
 constant as long as these forces remain con- 
 stant. According to this definition, every 
 saline solution which can let go salt without 
 any change of temperature is of necessity 
 supersaturated. It may be shewn that, in 
 general, supersaturation is not a fixed point, 
 and that the cause which produces it is the 
 same as that which keeps water liquid below 
 the temperature at which it congeals. 
 
 “ I shall now give an account of the ex- 
 periments which I have made on the solu- 
 bility of the salts. 
 
 “ Having saturated water with a salt at & 
 determinate temperature, as I have explained 
 above, I take a matrass capable of holding 
 150 to 200 grammes of water, and whose 
 neck is 15 to 18 centimetres in length. After 
 having weighed it empty, it is filled to about 
 a fourth part with the saline solution, and 
 weighed again. To evaporate the water, the 
 matrass is laid hold of by the neck by a pair 
 of pincers, and it is kept on a red-hot iron at 
 an angle of about 45°, taking care to move 
 it continually, and to give the liquid a rota- 
 tory motion, in order to favour the boiling, 
 and to prevent the violent bubbling up which 
 is very common with some saline solutions, 
 as soon as, in consequence of evaporation, 
 they begin to deposit crystals. When the 
 saline mass is dry, and when no more aqueous 
 vapours are driven off at a heat nearly raised 
 to redness, I blow into the matrass by means 
 of a glass tube fitted to the nozzle ot a pair 
 of bellows, in order to drive out the aqueous 
 vapour which fills it. Die matrass is then 
 allowed to cool, and weighed. I now know 
 the proportion of water to the salt held in so- 
 lution, and this is expressed by representing 
 the quantity of water to be 100. Bach ot 
 the following results is the mean of at least 
 two experiments : — 
 
SAL 
 
 SAL 
 
 Solubility of Chloride of Potassiu m. 
 Temperature Chloride dissolved J)y 
 
 centigrade. 100 water. 
 
 0.00° 29.21 
 
 19.35 34.53 
 
 52.39 43.59 
 
 79.58 50.93 
 
 109.60 59.26 
 
 Solubility of Chloride of' Barium. 
 Temperature centigrade. Salt dissolved in 100 water. 
 
 15.64° 
 
 34.86 
 
 49.31 
 
 43.84 
 
 74.89 
 
 50.94 
 
 105.48 
 
 59.58 
 
 In these experiments, the chloride of ba- 
 rium is supposed to be anhydrous ; but as 
 when it is crystallized it retains two propor- 
 tions of water, 22.65, for one of chloride, 
 131.1, we must of necessity, in order to com- 
 pare its solubility with that of other salts, in- 
 crease each number of solubility by the same 
 number multiplied into the ratio of 22. 65 to 
 131.1, and diminish by as much the quantity 
 of water. On making this correction, the 
 preceding results will be changed into the 
 following : — 
 
 Temperature. Salt dissolved in 100 water. 
 15.64° 45.50 
 
 49.31 55.65 
 
 74.89 65.51 
 
 105.48 77.89 
 
 Solubility of Chloride erf Sodium. 
 
 Temperature. Salt dissolved in 100 water. 
 13.89° 35.81 
 
 16.90 35.88 
 
 59.93 37.14 
 
 3 09.73 40.38 
 
 Solubility of Sulphate of Potash. 
 
 Temperature. Salt dissolved in 100 water. 
 12.72° 10.57 
 
 49.08 16.91 
 
 65.90 19.29 
 
 301.50 26.33 
 
 Solubility of' Sulphate erf Magnesia. 
 
 Temperature. Salt dissolved in 100 water. 
 14.58° 52.7 6 
 
 39.86 45.05 
 
 49.08 49.18 
 
 34.35 56.75 
 
 97.03 72.30 
 
 The sulphate of magnesia is here supposed 
 anhydrous; but as it crystallizes retaining 
 seven portions of water, 79.3, for one pro- 
 portion of salt, 74.6, each number which ex- 
 presses the solubility, must be increased by this 
 number multiplied by the ratio of 79.3 to 
 74.6, and the corresponding quantity of water 
 diminished as much. We shall thus have for 
 the solubility of crystallized sulphate of mag- 
 nesia the following results: — 
 
 2 
 
 Temperature. 
 
 14.58° 103.69 
 
 89.86 ► 178.34 
 
 49.08 212.61 
 
 (74.35 295.13 
 
 97.03 644.44 
 
 These results are no longer proportional 
 to the temperatures; they augment in a much 
 greater ratio. 
 
 Solubility of Sulphate of Soda. 
 
 Salt soluble in 100 water. 
 
 Temperature. 
 
 Anhydrous. 
 
 Crystallized. 
 
 0.00° 
 
 5.02 
 
 1 2. 1 7 
 
 11.67 
 
 10. 12 
 
 26.58 
 
 13.30 
 
 1 1.74 
 
 31.33 
 
 17.91 
 
 16,73 
 
 48.28 
 
 25.05 
 
 28.11 
 
 99.48 
 
 28.76 
 
 37.35 
 
 161.53 
 
 30.75 
 
 43.05 
 
 215.77 
 
 3 h 84 
 
 47.37 
 
 270.22 
 
 32.73 
 
 50.65 
 
 322. 1 2 
 
 33.88 
 
 50.04 
 
 312.11 
 
 40.15 
 
 48.78 
 
 291.44 
 
 45.04 
 
 47.81 
 
 276.91 
 
 50.40 
 
 46.82 
 
 262.35 
 
 59.79 
 
 45.42 
 
 — 
 
 70.61 
 
 44 .55 
 
 — 
 
 84.42 
 
 42.96 
 
 — * 
 
 103.17 
 
 42,65 
 
 — 
 
 W T e see by these results, that the solubility 
 of sulphate of soda follows a very singular 
 law. After having increased rapidly to about 
 the temperature of 33°, where it is at its 
 maximum, it diminishes to 103.17°, and at 
 that point it is nearly the same as at 30.5°. 
 The sulphate of soda presents the second ex- 
 ample of a body whose solubility diminishes 
 as the temperature augments ; for Mr Dal- 
 ton has already observed the same property 
 in lime. 
 
 Temperature. 
 
 Salt dissolved in 100 water. 
 
 0.00° 
 
 5.00 
 
 14.95 
 
 8.18 
 
 17.62 
 
 8.54 
 
 37.87 
 
 13.67 
 
 49.22 
 
 17.07 
 
 52.1 1 
 
 17.97 
 
 73.75 
 
 25.01 
 
 86.21 
 
 29.57 
 
 101.65 
 
 35.18 
 
 Solubility of Nitre. 
 
 Temperature. 
 
 Salt dissolved in 100 watc 
 
 0.00° 
 
 13.32 
 
 5.01 
 
 16.72 
 
 11.67 
 
 22.23 
 
 17.91 
 
 29.31 
 
 24.94 
 
 38.40 
 
 35.15 ■ 
 
 54.82 
 
 45.10 
 
 74.66 
 
 54.72 
 
 97.05 
 
SAL 
 
 SAL 
 
 65.45 125.42 
 
 7 9.72 169.27 
 
 97.66 236.45 
 
 Solubility of Chlorate of Potash. 
 Temperature. 
 
 0.00° 
 
 5.35 
 
 13.32 
 
 5.60 
 
 15.37 
 
 6.03 
 
 24.4.3 
 
 8.44 
 
 35.02 
 
 12.05 
 
 49.08 
 
 18.96 
 
 74.89 
 
 35.40 
 
 104.78 
 
 60.24 
 
 Plate \ III. exhibits a perpendicular sec- 
 tion through the middle of the salt mine of 
 Visachna, on the south-west of the Carpa- 
 thian mountains, 
 
 1. A stratum of vegetable mould. 
 
 2. Stiff yellow clay. 
 
 3. Grey and yellow clay, mixed with spots 
 and veins of sand and ochre. 
 
 4. Greyish-blue clay. 
 
 5. Fine white sand. 
 
 6. Black, fat, bituminous clay, immediate- 
 ly covering the bed of salt. 
 
 7. The body of salt, divided into inclined 
 strata. This has been penetrated to the 
 depth of about two hundred yards. It is 
 traversed by veins (8, 8) of a bituminous 
 clay, of the same nature as that at 6. This 
 clay contains sulphate of lime. 
 
 A. The shaft by which the salt is drawn 
 up. 
 
 C. The shaft through which the work- 
 men pass up and down by means of a ladder 
 placed in it. 
 
 D. A shaft that receives the rain-water, 
 and conducts it to the drain F. 
 
 B. A shaft that receives rain-water, and 
 conducts it into the gallery E. 
 
 E. E, F. Sections of two circular galleries 
 surrounding the shafts A and C, which col- 
 lect the waters that penetrate between the 
 strata of clay, and conduct them to the 
 drain F, through which they are carried 
 off. 
 
 H, II. A conical space hollowed out of 
 the rock salt in working it. 
 
 a, a, a, a. Pieces of timber driven into the 
 bed of salt, and supporting all the wood- 
 work of the shafts. 
 
 b, b, b, b. Sheep-skins, nailed on these 
 pieces of timber, to keep them from wet. 
 
 c, c. Bags in which the salt is drawn 
 
 up. 
 
 d, d, d. Cuts for extracting the salts in 
 oblong squares. 
 
 e, e. Blocks of salt ready to be put into 
 the bags and drawn up. 
 
 When this salt is impure, it must be dis- 
 solved in water, in order to purify it. 
 
 The water of the ocean contains our most 
 ample storo of salt, but not the richest. If 
 we had no means of obtaining the muriate 
 
 of soda from it, but by the heat of fires, salt 
 would be an expensive article of consump- 
 tion. Recourse, therefore, has been had to 
 two methods of attaining this purpose: 1st, 
 by natural evaporation ; 2d, by natural and 
 artificial evaporation combined. 
 
 In the first case, the salt is extracted by 
 means of brine- pits. These are large shal- 
 low pits, the bottom of which is very smooth, 
 and formed of clay. They are made near 
 the sea-shore, and consist of, 
 
 1st, A large reservoir, deeper than the 
 proper brine-pits, and dug between them 
 and the sea. This reservoir communicates 
 with the sea by means of a channel provided 
 with a sluice. On the sea-shore, these re- 
 servoirs may be filled at high water, but the 
 tides are rather inconvenient than advanta- 
 geous to brine-pits. 
 
 2dly, The brine-pits properly so called, 
 which are divided into a number of com- 
 partments by means of little banks. All 
 these compartments have a communication 
 with each other, but so that the water fre- 
 quently has a long circuit to make from one 
 set to another. Sometimes it has four or 
 five hundred yards to flow before it reaches 
 the extremity of this sort of labyrinth. The 
 various divisions have a number of singular 
 names, by which they are technically dis- 
 tinguished, and differing much in different 
 places. 
 
 The brine-pits should be exposed to the 
 north, north-east, or north-west winds. 
 
 Plate IX. exhibits a plan of a set of brine- 
 pits. 
 
 A, A. The great reservoir, into which 
 the water flows through the sluice a. 
 
 B, B, B. The second reservoir. Into this 
 the water enters by a subterranean channel 
 at b, and, circulating through the several 
 divisions in the direction of the shaded line, 
 finds its exit at d. 
 
 c, c, c, c. Narrow banks of earth separat- 
 ing the divisions. 
 
 C, C, C. The third reservoir. The wa- 
 ter, on quitting the second reservoir, enters, 
 through an aperture at d , the long narrow 
 channel d, e,f g, h, whence it flows into C, 
 C, C, as it had before done into B, B, B. 
 
 D, I), D, I). The fourth reservoir, into 
 which the water flows, as shown in tho 
 plate, from the third reservoir ; and from 
 which it is ultimately distributed among 
 the small square basins E, E, E, E, E, E, 
 E, E. 
 
 i, t, i, i. Heaps of salt drawn out of the 
 basins E, E, and left to drain. 
 
 K, K. The salt collected together in 
 larger heaps, and left to drain stiil more. 
 
 The water of the sea is let into these re- 
 servoirs in the month of March. It affords, 
 as is apparent, a vast surface for evaporation. 
 The first reservoir is intended to detain the 
 water till its impurities have subsided, while 
 
SAL 
 
 SAL 
 
 at the same time the evaporation commences 
 in it. From this the other reservoirs are 
 supplied, as their water evaporates. The 
 salt is considered as on the point of crystal- 
 lizing, when the water begins to grow red. 
 Soon after this, a pellicle forms on the sur- 
 face, which breaks, and falls to the bottom. 
 Sometimes the salt is allowed to subside in 
 the first compartment, sometimes it is made 
 to pass on to others, where a larger surface 
 is exposed to the air. In either case the 
 salt is drawn out, and left upon the borders 
 of the pans to drain and dry. In this way 
 it is collected two or three times a-week, to- 
 ward the end of the operation. 
 
 The salt thus obtained, partakes of the 
 colour of the bottom on which it is formed ; 
 according to the nature of which, it is white, 
 red, or grey. The last is frequently called 
 green salt. Sea-salt has the inconvenience 
 of tasting bitter, if used immediately after it 
 is made. This is owing to the muriate of 
 lime and sulphate of soda, with which it is 
 contaminated. By exposure to the air for 
 two or three years it is in part freed from 
 these salts. 
 
 Explanation of Plates X. and XI. 
 
 Fig. 1. Plan of the salt pans. 
 
 No. 1. Small pan. 
 
 No. 2. Graduating pan. 
 
 No. 3. Preparing pan. 
 
 No. 4. Crystallizing pan. 
 
 The arrangement of the plates of iron, 
 which compose these pans, is shown in 
 No. 2. 
 
 a, a. Elevation on which the salt is placed 
 to drain, as it is taken from the crystallizing 
 pans. 
 
 b, b , b . Wooden partitions, which separate 
 the chambers. 
 
 c, c, c. A raised wooden ledge, which 
 surrounds the pans. 
 
 Fig. 2. Section of the evaporating cham- 
 ber, which contains the pans 1 and 2, in the 
 line C, I). 
 
 d } d, d. Heat- tubes, which give heat to 
 the small pan, and contribute to heat the 
 others. 
 
 c, e, e. Fire-place for the pans. 
 
 t, i, i. Pillars of cast iron, over the grat- 
 ings g, g, g, which support the bottoms of 
 the pans. 
 
 h. Wooden chamber, which contains the 
 two pans. 
 
 k. Opening by which the vapours escape. 
 
 Fic. 3. Section of the evaporating cham- 
 her, which contains the pans 3 and 4, in the 
 line A, B. 
 
 a. Elevation on which the salt from the 
 crystallizing pans is placed to drain. 
 
 The other letters indicate the same parts 
 as in the preceding figures. 
 
 Fig. 4. Method in which the plates of 
 iron are joined to form the pans. 
 
 a. The iron plate. 
 
 b . The iron gutter, which receives the 
 edges of the plates, and is strongly fastened 
 with screws. 
 
 i, i. Pillars of cast iron, which support 
 the bottom of the pan. 
 
 Sometimes the water is evaporated to 
 dryness ; but this is rarely done, because for 
 this the water must contain no muriate ot 
 soda. Commonly the mother-water is left, 
 containing chiefly the deliquescent salts, 
 which are muriates of lime and magnesia. 
 These salts, while they increase the bulk of 
 the mother- water, add also to the consump- 
 tion of fuel, and render the salt obtained 
 bitter and deliquescent. 
 
 When saline waters contain but a small 
 quantity of salt, the evaporation of it by fire 
 in its natural state would be too expensive. 
 It must be concentrated therefore by some 
 cheaper mode. 
 
 Now it is well known, that, to promote 
 and accelerate the evaporation of a fluid, it 
 should be made to present a large surface 
 to the air. To effect this, the water is 
 pumped up to the height of nine or ten 
 yards, and made to fall on piles of faggots 
 built up in the shape of a wall. The water, 
 distributed uniformly over these by means 
 of troughs, is minutely divided in its descent, 
 and thus experiences a considerable evapo- 
 ration. The same water is frequently pump- 
 ed up twenty times or more, to bring it to 
 the degree of concentration necessary. This 
 operation is called graduating , and the piles 
 of thorn faggots thus erected are termed 
 graduation houses. 
 
 These piles are covered with a roof, to 
 shelter them from the rain, are made about 
 five yards thick, and are sometimes more 
 than four hundred yards long. They should 
 be so constructed that their sides may face 
 the prevailing winds. 
 
 Plate XII. represents a graduation house 
 at Bex, with the improvements lately made 
 in it by M. Fabre. 
 
 A. Transverse section of the building. 
 
 B. Longitudinal section. 
 
 c, c, c. The faggots of thorns, piled up in 
 two tiers below, and one above. 
 
 a, a. Wooden troughs, to distribute the 
 salt water over these fageots. 
 
 C. C. Plan and perspective view of these 
 troughs. 
 
 b, b, b. Angular notches, through which 
 the water runs out in slender streams, pre- 
 senting a large surface to the air. 
 
 e. Roof, covered with tiles, not laid flat, 
 but raised so as to admit a free circulation 
 of air between them. 
 
 d, d. Reservoir, into which the concen- 
 trated salt water flows, and from which it is 
 
SAL 
 
 SAL 
 
 pumped up to the troughs, to bo distributed 
 afresh over the faucets. 
 
 The state of the air has a considerable in- 
 fluence on the celerity of the concentration. 
 A cool, dry, and moderate wind is favour- 
 able to it ; while dull, damp, and foggy 
 weather sometimes even adds to the quantity 
 of water. 
 
 The principal uses of the muriate of soda 
 have already been mentioned under the ar- 
 ticle muriatic acid. In addition it may be 
 observed, that almost all graminivorous ani- 
 mals are fond of it, and that it appears to 
 be beneficial to them, when mixed with 
 their food. Wood steeped in a solution of 
 it, so as to he thoroughly impregnated with 
 it, is very difficult of combustion : and in 
 Persia it is supposed to prevent timber from 
 the attack of worms, for which purpose it 
 
 is used in that country. Bruce informs us 
 that in -Abyssinia it is used as money ; an< 
 it is very probable, that the pillars of fossi 
 glass, in which the Abyssinians are said b 
 Herodotus to have enclosed the bodies o 
 their relations, were nothing but masses o 
 rock salt, which is very common in that par 
 of Africa. 
 
 Salt was supposed by the ancients to b 
 so detrimental to vegetation, that, when 
 field was condemned to sterility, it was cus- 
 tomary to sow it with salt. Modern agri 
 cult urists, however, consider it as a usefu 
 manure. 
 
 * We are indebted to Dr Henry for aver 
 able and elaborate investigation of the diffe 
 rent varieties of common salt. The following 
 table contains the general statement of hi 
 experiments. 
 
 1000 parts by weight consist of 
 
 Kind of salt. 
 
 Insol. 
 m atter. 
 
 Mur. 
 
 lime. 
 
 Mur. 
 
 magn. 
 
 ^ • 
 
 of 1 
 - g s 
 
 Sulph. 
 
 lime. 
 
 Suiph. 
 magn . 
 
 — js 
 
 ^ Vi 
 
 Total 
 
 muriates. 
 
 Pure 
 muriate 
 of soda. 
 
 3> 
 
 f~St Ube’s, 
 
 9 
 
 trace 
 
 3 
 
 3 
 
 23i 
 
 4i 
 1 2 
 
 28 
 
 40 
 
 960 
 
 £ j 
 
 St Martin’s, 
 
 12 
 
 do. 
 
 Si 
 
 Si 
 
 19 
 
 6 
 
 25 
 
 40i 
 
 959-| 
 
 ' -3 
 
 ^Oleron, 
 
 10 
 
 do. 
 
 2 
 
 2 
 
 19-i 
 
 4i 
 
 ^2 
 
 23j 
 
 354 
 
 964i 
 
 « W ( 
 n. $ 
 
 4 
 
 " Scotch (common), 
 
 4 
 
 — 
 
 28 
 
 28 
 
 15 
 
 l?i 
 1 ' 2 
 
 <zo 1 
 
 G4i 
 
 9354 
 
 &2 C-t- 
 1 • 
 
 } Scotch (Sunday), 
 
 1 
 
 — 
 
 m 
 
 lli 
 
 12 
 
 4i 
 
 164 
 
 29 
 
 971 
 
 g & 
 
 I Lymington (common), 
 
 2 
 
 — 
 
 1 1 
 
 11 
 
 15 
 
 35 
 
 50 
 
 63 
 
 937 
 
 0 0 
 
 1 HJ I 
 
 • J“S V 
 
 _ Ditto (cat), 
 
 1 
 
 — - 
 
 5 
 
 5 
 
 1 
 
 5 
 
 6 
 
 12 
 
 988 
 
 n \ 
 
 ' Crushed rock, 
 
 10 
 
 0 -J— 
 
 1 (j 
 
 0. T 3 7T 
 
 o -4 
 
 64 
 
 
 
 64 
 
 164 
 
 983i 
 
 'P fT) 
 
 | Fishery, 
 
 1 
 
 O.i 
 
 0-4 
 
 i 
 
 114 
 
 — 
 
 H 4 
 
 134 
 
 986i 
 
 c-r ^ 
 
 1 Common, 
 
 1 
 
 o*4 
 
 0.4 
 
 i 
 
 14i 
 
 __ 
 
 144 
 
 164 
 
 9834 
 
 <t> ? 
 
 _ Stoved, 
 
 1 
 
 O.J 
 
 0-4 
 
 i 
 
 154 
 
 • — 
 
 154 
 
 1 7- 
 1 1 2 
 
 982i 
 
 “ In sea salt prepared by rapid evapora- 
 tion, the insoluble portion is a mixture of 
 carbonate of lime with carbonate of magne- 
 sia, and a fine siliceous sand ; and in the salt 
 prepared from Cheshire brine, it is almost 
 entirely carbonate of lime. The insoluble 
 part of the less pure pieces of rock salt is 
 chiefiy a marly earth, with some sulphate of 
 lime. The quantity of this impurity, as it is 
 stated in the table, is considerably below the 
 average, which in my experiments has varied 
 from 10 to 45 parts in 1000.. Some esti- 
 mate of its general proportion, when ascer- 
 tained on a larger scale, may be formed from 
 the fact, that Government, in levying the 
 duties, allow 65 pounds to the bushel of 
 rock salt, instead of 56 pounds, the usual 
 weight of a bushel of salt.” — Henri/. Phil. 
 Trans, for 1810, part 1st. The enormous 
 contamination of the Scotch variety with 
 that septic bitter salt, muriate of magnesia, 
 accords perfectly with my own experiments, 
 and is a reproach to the country. 
 
 That kind of salt then,” says this able 
 
 chemist, “ which possesses most eminentl; 
 the combined properties of hardness, com 
 pactness, and perfection of crystals, will b« 
 best adapted to the purpose of packing fisl 
 and other provisions, because it will remaii 
 permanently between the different layers, o 
 will be very gradually dissolved by the fluid 
 that exude from the provisions; thus fur 
 nishing a slow but constant supply of satin 
 rated brine. On the other hand, for th« 
 purpose of preparing the pickle, or of strik 
 ing the meat, which is done by immcrsioi 
 in a saturated solution of salt, the smalle 
 grained varieties answer equally well ; or 
 on account of their greater solubility, cvei 
 better,” provided they be equally pure. Hi 
 experiments shew, that in compactness o 
 texture the large grained British salt is equa 
 to the foreign bay salt. Their antiseptic 
 qualities are also the same.* 
 
 SaLt ( Am.moniacal, Fixed). Muriate o 
 lime. 
 
 Salt (Ammoniacal, Secret) of Glauber 
 Sulphate of ammonia. 
 
SAN 
 
 SAP 
 
 Salt (Arsenical, Neutral) of Mac- 
 Qur-iu Superarseniate of potash. 
 
 Salt (Bitter, Cathartic). Sulphate of 
 magnesia. 
 
 Salt (Common). Muriate of Soda. See 
 Acid (Muriatic); also end of the article 
 Salt, and Rock Salt. 
 
 Salt (Digestive) of Svlvius. Acetate 
 of potash. 
 
 Salt (Diuretic). Acetate of potash. 
 
 Salt (Epsom). Sulphate of magnesia. 
 
 Salt (Febrifuge) of Sylvius. Muriate 
 of potash. 
 
 Salt (Fusible). Phosphate of ammonia. 
 
 Salt (Fusible) of Urine. Triple phos- 
 phate of soda and ammonia. 
 
 Salt (Glauber’s). Sulphate of soda. 
 
 Salt (Green). In the mines of Wie- 
 liczka the workmen give this name to the 
 upper stratum of native salt, which is ren- 
 dered impure by a mixture of clay. 
 
 Salt (Marine). Muriate of soda. 
 
 Salt (Marine, Argillaceous). Mu- 
 riate of alumina. 
 
 Salt (Microcosmic). Triple phosphate 
 of soda and ammonia. 
 
 Salt (Nitrous Ammoniacal). Nitrate of 
 ammonia. 
 
 Salt of Amber. Succinic acid. 
 
 Salt of Benzoin. Benzoic acid. 
 
 Salt of Canal. Sulphate of magnesia. 
 
 Salt of Colcothar. Sulphate of iron. 
 
 Salt of Egra. Sulphate of magnesia. 
 
 Salt of Lemons (Essential). Superoxa- 
 late of potash. 
 
 Salt of Saturn. Acetate of lead. 
 
 Salt of Sedlitz. Sulphate of magnesia. 
 
 Salt of Seignette. Triple tartrate of 
 potash and soda. 
 
 Salt of Soda. Subcarbonate of soda. 
 
 Salt of Sorrel. Superoxalate of potash. 
 
 Salt of Tartar. Subcarbonate of potash. 
 
 Salt of Vitriol. Purified sulphate of 
 zinc. 
 
 Salt of Wisdom. A compound muriate 
 of mercury and ammonia. See Alembroth. 
 
 Salt (Pkrlate). Phosphate of soda. 
 
 Salt (Polyciirest) of Glaser. Sul- 
 phate of potash. 
 
 Salt (Sedative). Boracic acid. 
 
 Salt (Spirit of). Muriatic acid w'as for- 
 merly called by this name, which it still re- 
 tains in commerce. 
 
 Salt (Sulphureous) of Staiil. Sul- 
 phite of potash. 
 
 Salt (Wonderful). Sulphate of soda. 
 
 Salt (Wonderful Perlate). Phos- 
 phate of soda. 
 
 Saltpetre. Nitrate of potash. 
 
 Sand. Sand is an assemblge of small 
 stones. 
 
 Sand-bath. See Bath. 
 
 Sandaiuc Gum. A resin in yellowish- 
 white tears, possessing a considerable degree 
 of 'transparency. 
 
 Sandive r, or Glass-gat.l. This is a 
 saline matter, which rises as a scum in the 
 pots or crucibles in which glass is made. 
 
 * Sanguification. That process of living 
 animals by which chyle is converted into 
 blood. I had entertained hopes of being 
 able to present some definite facts on this 
 mysterious subject, but have been disappoint- 
 ed. The latest and best essay on sanguifi- 
 cation is that of Dr Prout, in the Annals of 
 Philosophy for April I 819.’"' 
 
 * Sappare. Cy'anite. * 
 
 * Sapphire. A sub-species of rhomboi- 
 dal corundum. It is the Telesie of Ilaiiy, 
 and the perfect corundum of Bonrnon. The 
 oriental ruby and topaz are sapphires. 
 
 Colours blue and red ; it occurs also grey, 
 white, green, and yellow'. It occurs in blunt 
 edged pieces, in roundish pebbles, and crys- 
 tallized. The primitive figure is a slight- 
 ly acute rhomboid, or double three-sided 
 pyramid, in which the alternate angles are 
 86° 4' and 93° 56\ The following are the 
 usual forms: — a very acute, equiangular, 
 six-sided pyramid ; the same truncated on 
 the summit; a perfect six-sided prism; an 
 acute, double, six-sided pyramid ; the same 
 acuminated, or truncated in various ways. 
 Splendent, inclined to adamantine. Clea- 
 vage parallel with the terminal planes of the 
 prism. Fracture eonchoidal. From trans- 
 parent to translucent. Refracts double. 
 After diamond, it is the hardest substance in 
 nature. The blue variety or sapphire, is 
 harder than the ruby. Brittle. Sp. ^gr. 4 
 to 4.2. Its constituents are, 
 
 
 Blue. 
 
 Red. 
 
 Alumina, 
 
 98.5 
 
 90.0 
 
 lame, 
 
 6.5 
 
 7.0 
 
 Oxide of iron, 
 
 1. 
 
 1.2 
 
 loss 1 . 8 
 
 100.0 100.0 
 
 Klaproth. Chenevix . 
 
 Infusible before the blow-pipe. It becomes 
 electrical by rubbing, and retains its electri- 
 city for several hours ; but does not become 
 electrical by heating. It occurs in alluvial 
 soil, in the vicinity of rocks belonging to the 
 secondary or floetz-trap formation, and im- 
 bedded in gneiss. It is found at Fodsedlitz 
 and Treblitz in Bohemia, and Hohenstcin 
 in Saxony ; Expailly in France ; and par- 
 ticularly beautiful in the Capelan mountains, 
 12 days journey from Sirian a city of Pegu. 
 Next to diamond, it is the most valuable of 
 the gems. The white and pale blue varie- 
 ties, by exposure to heat, become snow-white, 
 and when cut exhibit so high a degree of 
 lustre, that they are used in place of diamond. 
 The most highly prized varieties are the 
 crimson and carmine-red; these are the ori- 
 ental ruby of the jeweller; the next is sap- 
 phire, and last, the yellow, or oriental topaz* 
 
SAU 
 
 SCH 
 
 
 The asterias, or star-stone, is a very beautiful 
 variety, iu which the colour is generally of 
 a reddish-violet, and the form a rhomboid, 
 with truncated apices, which exhibit an 
 opalescent lustre. A sapphire of 10 carats 
 weight, is considered to be worth fifty 
 guineas. — Jameson.* 
 
 * Sai\hir,in. Haiiyne.* 
 
 * Sarcolite. A variety of analcime. * 
 
 * Sarde, or Sardoin, a variety of carne- 
 lian, which displays on its surface an agree- 
 able and rich reddish-brown colour, but ap- 
 pears of a deep blood-red, when held be- 
 tween the eye and the light.* 
 
 * Sardonyx. Another variety, composed 
 of layers, of white and red carnelian.* 
 
 * Sassoline. Native boracic acid. It is 
 found on the edges of hot springs near Sasso, 
 in the territory of Florence. It consists of 
 boracic acid 86, ferruginous sulphate of man- 
 ganese II, sulphate of lime 3. — Klaproth .* 
 
 * Satin Spar. Fibrous limestone ; which 
 see.* 
 
 Saturation. Some substances unite in 
 all proportions. Such, for example, are 
 acids in general, and some other salts with 
 water ; and many of the metals with each 
 other. But there are likewise many sub- 
 stances which cannot be dissolved in a fluid, 
 at a settled temperature, in any quantity 
 beyond a certain proportion. Thus water 
 will dissolve only about one-third of its 
 weight of common salt, and, if more be add- 
 ed, it will remain solid. A fluid, which 
 holds in solution as much of any substance 
 as it can dissolve, is said to be saturated 
 with it. But saturation with one substance 
 does not deprive the fluid of its power of 
 acting on and dissolving some other bodies, 
 and in many cases it increases this power. 
 For example, water saturated with salt will 
 dissolve sugar; and water saturated with 
 carbonic acid will dissolve iron, though with- 
 out this addition its action on this metal is 
 scarcely perceptible. 
 
 The word saturation is likewise used in 
 another sense by chemists: the union of 
 two principles produces a body, the pro- 
 perties of which differ from those of its com- 
 ponent parts, but resemble those of the pre- 
 dominating principle. When the principles 
 are in such proportion that neither predo- 
 minates, they are said to be saturated with 
 each other; but if otherwise, the most pre- 
 dominant principle is said to be subsaturated 
 or undersaturated, and the other supersatu- 
 rated or oversaturated. 
 
 * Saussurite. Colours white, grey, and 
 green. Massive, disseminated, and in rolled 
 pieces. Dull. Fracture splintery. Faintly 
 translucent on the edges. Difficultly frangi- 
 ble. Hard, scratching quartz. Meagre to 
 the feel. Sp. gr. 3.2. It melts on the edges 
 and angles. Its constituents are, silica 49, 
 alumina 24, lime 10.5, magnesia 3.75, na- 
 
 tron 5.5, iron 6.5 Klaproth. It occurs 
 
 at the foot of Mount Rosa. Professor Jame- 
 son places it near Andalusite.* 
 
 * Scales of Fish, consist of alternate 
 layers of membrane and phosphate of lime.* 
 
 * Scales of Serpents, are composed of 
 a horny membrane, without the calcareous 
 phosphate.* 
 
 * Sc AMMO NY consists of 
 
 Resin, 
 
 a leppo. 
 60 
 
 Smyrna. 
 
 29 
 
 Gum, 
 
 3 
 
 8 
 
 Extractive, 
 
 2 
 
 5 
 
 Vegetable debris ] 
 and earth, \ 
 
 !• 35 
 
 58 
 
 
 100 
 
 100 
 
 Vogel , and Bouillon Lagrange . * 
 * Scafolite, or Pyramidal Felspar. 
 Professor Jameson divides it into four sub- 
 species ; radiated, foliated, compact red, and 
 elaolite. 
 
 1. Radiated. Colour grey. Massive, in 
 distinct concretions and crystallized. Primi- 
 tive figure a pyramid of 136° 38' and 62° 
 56'. The secondary forms are, a rectangular 
 four-sided prism, acuminated or truncated. 
 Lateral planes deeply longitudinally streak- 
 ed. Resinous, pearly. Cleavage double. 
 Fracture fine grained uneven. Translucent. 
 As hard as apatite. Easily frangible. Sp. 
 gr. 2.5 to 2.8. Green scapolite becomes 
 white before the blow^-pipe, and melts into a 
 white glass. Its constituents are, silica 45, 
 alumina 33, lime 17.6, natron 1.5, potash 
 0.5, iron and manganese 1. — Laugier. It 
 occurs in the neighbourhood of Arendal in 
 Norway, associated w ith magnetic ironstone, 
 felspar, &c. 
 
 2. Foliated scapolite. Colours grey, green, 
 and black. Massive, disseminated, and crys- 
 tallized in low eight-sided prisms, flatly 
 acuminated with four planes. Splendent, 
 vitreous. Fracture small grained uneveu. 
 Translucent. Streak white. Brittle. Hard- 
 ness and sp. gr. as preceding species. It is 
 found in granular granite or whitestone , in 
 the Saxon Erzegebirge. 
 
 5. Compact scapolite. Colour red. Crys- 
 tallized in long, acicular, four-sided prisms, 
 which are often curved. Glistening. Opaque. 
 Hard in a low degree. Easily frangible. 
 It occurs with the others in metalliferous 
 beds at Arendal. 
 
 4. See Elaolite.* 
 
 * ScHAALSTElN. See TABULAR SpAR.* 
 
 * Schaum Earth. See Am rite.* 
 
 * Scheelium. Tungsten.* 
 
 * Schiefer Spar. See Slate Spar.* 
 
 * Schiller Spar. This species contains 
 tw r o sub-species ; bronzite and common schil- 
 ler spar. See Bronzite.* 
 
 Common schiller spar. Colour olive-green. 
 Disseminated, and in granular distinct con- 
 cretions. Splendent and metallic-pearly. 
 
SEL 
 
 SEL 
 
 Cleavage single. Opaque. Softer than 
 bronzite. Streak greenish- grey. Easily 
 frangible. Sp. gr. 2.882? It occurs im- 
 bedded in serpentine in Fetlar and Unst in 
 Shetland, and at Portsoy in Banffshire ; also 
 in Skye, Fifeshire, Calton-hill, near Dum- 
 barton, between Ballantrae and Girvan in 
 Ayrshire, and in Cornwall. 
 
 Labraclore scliiller spar . See Hyfer- 
 
 STENE.* 
 
 * Scillitin. A white transparent, acrid 
 substance, extracted from squills, by Vogel.* 
 
 * Schmelzetein. Dipyre.* 
 
 * Schorl (“Common ). A sub-species of 
 rhomboidal tourmaline. Colour velvet-black. 
 Massive, disseminated, and crystallized, in 
 three, six, and nine-sided prisms. Crystals 
 acicular. Lateral planes, longitudinally 
 streaked. Between shining and glistening. 
 Fracture conchoidal, or uneven. Opaque. 
 Streak grey. As hard as quartz. Easily 
 frangible. Sp. gr. 3. to 3.3. It melts 
 into a blackish slag. Its constituents are, 
 silica 36.75, alumina 54.5, magnesia 0.25, 
 oxide of iron 21, potash 6, and a trace of 
 manganese. — Klaproth. It exhibits the same 
 electric properties as tourmaline. It occurs 
 imbedded in granite, gneiss, &c. in Perth- 
 shire, Banffshire, Cornwall, &c.* 
 
 * Schorl (Blue). A variety of Haiiyne.* 
 
 * Schorl (Red and Titanitic). Rutile.* 
 
 * ScHORLITE, or ScHORLOUS TOPAZ. PpC- 
 nite of Werner. Colour, straw-yellow. 
 Massive, composed of parallel prismatic con- 
 cretions, and crystallized in long six-sided 
 prisms. Glistening, resinous. Fracture, 
 small conchoidal. Translucent on the edges. 
 Nearly as hard as common topaz. Brittle. 
 Sp. gr. 3.53. Infusible. Becomes electric 
 by heating. Its constituents are, alumina 
 51, silica 58.45, fluoric acid 8.84. — Berzelius . 
 It occurs at Altenberg in Saxony, in a rock 
 of quartz and mica, in porphyry.* 
 
 * Selenium. A new elementary body, 
 extracted by M. Berzelius from the pyrites 
 of Fahlun, which, from its chemical proper- 
 ties, he places between sulphur and tellurium, 
 though it has more properties in common 
 with the former than with the latter sub- 
 stance. It was obtained in exceedingly 
 small quantity from a large portion of py- 
 rites. For the mode of extraction I must 
 refer to his long and elaborate papers, trans- 
 lated from the Annales de Chimio et Phy- 
 sique, ix. et seq. into the Annals of Philoso- 
 phy, for June, August, October, and De- 
 cember 1819, and January 1820. 
 
 When selenium, after being fused, be- 
 comes solid, its surface assumes a metallic 
 brilliancy of a very deep brown colour, re- 
 sembling polished haematites. Its fracture is 
 conchoidal, vitreous, of the colour of lead, 
 and perfectly metallic. The powder of sele- 
 nium has a deep red colour, but it sticks to- 
 gether readily when pounded, and then as- 
 
 sumes a grey colour and a smooth surface, 
 as happens to antimony and bismuth. In 
 very thin coats, selenium is transparent, 
 with a ruby-red colour. When heated it 
 softens; and at 212° it is semi-liquid, and 
 melts completely at a temperature a few de- 
 grees higher. During its cooling it retains 
 for a long time a soft and semi-fluid state. 
 Like Spanish wax, it may be kneaded be- 
 tween the fingers, and drawn out into long 
 threads, which have a great deal of elasticity, 
 and in which we easily perceive the transpa- 
 rency, when they are fiat and thin. These 
 threads, viewed by transmitted light, are red ; 
 but, by reflected light, they are grey, and 
 have the metallic lustre. 
 
 When selenium is heated in a retort, i& 
 begins to boil at a temperature below that of 
 a red-heat. It assumes the form of a dark 
 yellow vapour, which, however, is not so in- 
 tense as that of the vapour of sulphur; but 
 it is more intense than chlorine gas. The 
 vapour condenses in the neck of the retort, 
 and forms black drops, which unite into 
 larger drops, as in the distillation of mer- 
 cury. 
 
 If we heat selenium in the air, or in ves- 
 sels so large, that the vapour may be con- 
 densed by the cold air, a red smoke is form- 
 ed, which has no particular smell, and which 
 is condensed in the form of a cinnabar-red 
 powder, yielding a species of flowers, as hap- 
 pens to sulphur in the same circumstances. 
 The characteristic smell of horse-radish is not 
 perceived, till the heat becomes great enough 
 to occasion oxidation. 
 
 Selenium is not a good conductor of heat. 
 We can easily hold it between the fingers, 
 and melt it at the distance of one or two 
 lines from the fingers, without perceiving 
 that it becomes hot. It is also a non-con- 
 ductor of electricity. On the other hand, 
 M. Berzelius was not able to render it elec- 
 tric by friction. It is not hard ; the knife 
 scratches it easily. It is brittle like glass, 
 and is easily reduced to powder. Its sp. gr. 
 is between 4.3 and 4.52. 
 
 The affinity of selenium for oxygen is not 
 very great. If we heat it in the air, without 
 touching it with a burning body, it is usually 
 volatilized, without alteration ; but if it is 
 touched by flame, its edges assume a fine 
 sky-blue colour, and it is volatilized with a 
 strong smell of horse-radish. The odorous 
 substance is a gaseous oxide of selenium, 
 which, however, has not been obtained in an 
 insulated state, but only mixed with atmos- 
 pherical air. If we heat selenium in a close 
 phial filled with common aiiytill the greatest 
 part of it is evaporated, the air of the phial 
 acquires the odour of oxide of selenium in a 
 very high degree. If we wash the air with 
 Pure water, the liquid acquires the odour of 
 the gas ; but as there are always formed traces 
 of selenic acid, this water acquires the pro* 
 
SEL 
 
 pcrty of reddening litmus paper feebly, and 
 of becoming muddy when mixed with sul- 
 phuretted hydrogen gas. Selenic oxide gas 
 is but very little soluble in water, and does 
 not communicate any taste to it. 
 
 If we heat selenium in a large flask filled 
 with oxygen gas, it evaporates without com- 
 bustion, and the gas assumes the odour of 
 selenic oxide, just as would have happened, 
 if the sublimation had taken place in com- 
 mon air ; but if we heat the selenium in a 
 glass ball of an inch diameter, in which it 
 has not room to volatilize and disperse ; and 
 if we allow a current of oxygen gas to pass 
 through this ball, the selenium takes fire, just 
 when it begins to boil, and burns with a fee- 
 ble flame, white towards the base, but green 
 or greenish-blue at the summit, or towards 
 the upper edge. The oxygen gas is absorb- 
 ed, and selenic acid is sublimed into the cold 
 parts of the apparatus. The selenium is 
 completely consumed without any residue. 
 The excess of oxygen gas usually assumes 
 the odour of selenic oxide. Selenic acid is 
 in the form of very long four-sided needles. 
 It seems to be most readily formed by the 
 action of nitro-muriatic acid on selenium. 
 The selenic acid does not melt with heat ; 
 but it diminishes a little in bulk at the hot- 
 test place, and then assumes the gaseous 
 form. It absorbs a little moisture from the 
 air, so that the crystals adhere to each other, 
 but they do not deliquesce. It has a pure 
 acid taste, which leaves a slightly burning 
 sensation on the tongue. It is very soluble 
 in cold water, and dissolves in almost every 
 proportion in boiling water. M. Berzelius 
 infers the composition of selenic acid, from 
 s.everal experiments, to be, 
 
 Selenium, 71.261 100.00 1 prime 4.96 
 
 Oxygen, 28.739 40.33 2 primes 2.00 
 
 If into a solution of selenic acid in mu- 
 riatic acid, we introduce a piece of zinc or of 
 polished iron, the metal immediately assumes 
 the colour of copper, and the selenium is 
 gradually precipitated in the form of red, or 
 brown or blackish flocks, according as the 
 temperature is more or less elevated. When 
 seleniate of potash is heated with muriate of 
 ammonia, selenium is obtained by the de- 
 oxidizing property of the ammonia ; but in 
 this case we always lose a small quantity ot 
 selenium, which .comes over with the water 
 in the form of an acid. If we pour dilute 
 muriatic acid on the compound of selenium 
 and potassium dissolved in water, seleniuret- 
 ted hydrogen gas is evolved. Water impreg- 
 nated with it precipitates all the metallic 
 solutions, even those of iron and zinc, when 
 they arc neutral. Sulphur, phosphorus, the 
 earths, and the metals, combine with sele- 
 nium, forming seleniurets. Selenic acid neu- 
 tralizes the bases. Selenium has been re- 
 cently found in two minerals, one is from 
 
 SER 
 
 Skrickerum, in the parish of Tryserum in 
 Smoland.* 
 
 * Scorza. A variety of epidote.* 
 
 * Sea Froth. Meerschaum* 
 
 Sea Salt. Muriate of soda. See Acid 
 (Muriatic), and Salt. 
 
 Slea Salt (Regenerated). Muriate of 
 potash. 
 
 * Sea Wax, Maltha, a white, solid, tal- 
 lowy looking fusible substance, soluble in 
 alcohol, found on the Baikal Lake in Si- 
 beria.* 
 
 * Sebacic Acid. See Acid (Sebacic). * 
 
 Sebat. A neutral compound of sebacic 
 
 acid with a base. 
 
 Sedative Salt. Boracic acid. 
 
 Sel de Seignftte. The triple tartrate 
 of potash and soda, or Rochelle salt. See 
 Acid (Tartaric). 
 
 * Selenite. Sparry gypsum.* 
 
 * Semiopal. See Opal.* 
 
 * Septaria, or ludi helmontii, are spheroi- 
 dal concretions, that vary from a few inches 
 to a foot in diameter. When broken in a 
 longitudinal direction, we observe the inte- 
 rior of the mass intersected by a number of 
 fissures, by which it is divided into more or 
 less regular prisms, of from S to 6 or more 
 sides, the fissures being sometimes empty, 
 but oftener filled up with another substance, 
 which is generally calcareous spar. The 
 body of the concretion is a ferruginous marie. 
 From these septaria are manufactured that 
 excellent material for building under water, 
 known by the name of Parker’s or Roman 
 cement . — Ja meson. * 
 
 * Serosity. See Blood.* 
 
 * Serpentine ; common, and precious. 
 
 1. Common. Colour green, of various 
 shades. Massive. Dull. Fracture, small 
 and fine splintery. Translucent on the edges. 
 Soft, and scratched by calcareous spar. Sec- 
 tile. Difficultly frangible. Feels somewhat 
 greasy. Sp. gr. 2.4 to 2.6. Some varieties 
 are magnetic. Its constituents are, silica 
 32, magnesia 37.24, alumina 0.5, lime 10.6, 
 iron 0.66, volatile matter and carbonic acid 
 14.16. — Hisinger. John and Rose give 10.5 
 of water in it. It occurs in various moun- 
 tains. It is found in Unst and Fetlar in 
 Shetland ; at Portsoy ; between Ballantrae 
 and Girvan ; in Cornwall; and in the county 
 of Donegal. 
 
 2. Precious 'serpentine. Of this there are 
 two kinds, the splintery and conchoidal. 
 
 a. Splintery. Colour dark leck-grcen. 
 Massive. Feebly glimmering. fracture 
 coarse splintery. Feebly translucent. Soft. 
 Sp. gr. 2.7. It occurs m Corsica, and is cut 
 into snufif-boxes, See. 
 
 b. Conchoidal. Colour leek-green. Mas- 
 sive and disseminated. Glistening, resinous. 
 Fracture flat conchoidal. Iranslucent. Semi- 
 bard. Sp. gr. 2.6. Its constituents aie, 
 
S1E 
 
 SIL 
 
 silica 42.5, magnesia 58.63, lime 0.25, alu- 
 mina 1, oxide of iron 1.5, oxide of manga- 
 nese 0.62, oxide of chrome 0.25, water 15.2. 
 — John . It occurs with foliated granular 
 limestone in beds subordinate to gneiss, mica- 
 slate, &c. It is found at Portsoy, in Banff- 
 shire; in the Shetland Islands, and in the 
 Island of Holyhead. It receives a finer polish 
 than common serpentine.* 
 
 * Serum. See Blood and Milk.* 
 
 * Shale. Slate-clay and bituminous slate- 
 clay .* 
 
 Shells. Marine shells may be divided, 
 as Mr Hatchett observes, into two kinds : 
 Those that have a porcellanous aspect, with 
 an enamelled surface, and when broken are 
 often in a slight degree of a fibrous texture; 
 and those that have generally, if not always, 
 a strong epidermis, under which is the shell, 
 principally or entirely composed of the sub- 
 stance called nacre, or mother-of-pearl. 
 
 The porcellanous shells appear to consist 
 of carbonate of lime, cemented by a very 
 small portion of animal gluten. This ani- 
 mal gluten is more abundant in some, how- 
 ever, as in the patellae. 
 
 The mother-of-pearl shells are composed 
 of the same substances. They differ, how- 
 ever, in their structure, which is lamellar, 
 the gluten forming their membranes, regu- 
 larly alternating with strata of carbonate of 
 lime. In these two the gluten is much more 
 abundant. 
 
 Mr Hatchett made a few experiments on 
 land shells also, which did not exhibit any 
 differences. But the shells of the crusta- 
 ceous animals he found to contain more or 
 less phosphate of lime, though not equal in 
 quantity to the carbonate, and hence ap- 
 proaching to the nature of bone. Linnaeus 
 therefore he observes was right in consider- 
 ing the covering of the echini as crustaceous, 
 for it contains phosphate of lime. In the 
 covering of some of the species of asterias 
 too, a little phosphate of lime occurs; but in 
 that of others there is none. Phil. Trans. 
 
 * Siiistus (Argillaceous). Clay-slate.* 
 
 * Si re rite. Red tourmaline.* 
 
 * Sidero-calcite. Brown spar.* 
 
 * Siderum. Bergman’s name for phos- 
 phurct of iron.* 
 
 ' * Sienite, or Syenite. A compound 
 granular aggregated rock, composed of fel- 
 spar and hornblende, and sometimes quartz 
 and black mica. The hornblende is the 
 characteristic ingredient, and distinguishes it 
 perfectly from granite, with which it is often 
 confounded ; but the felspar, which is almost 
 always red, and seldom inclines to green, 
 forms the most abundant and essential in- 
 gredient of the rock. Some varieties con- 
 tain a very considerable portion of quartz 
 and mica, but little hornblende. This is 
 particularly the case with the Egyptian va- 
 
 rieties, and hence these are often confound- 
 ed with real granite. 
 
 As it has many points of agreement with 
 greenstone, it is necessary to compare them 
 together. In greenstone, the hornblende 
 is usually the predominating ingredient ; in 
 sienite, on the contrary, it is the felspar that 
 predominates. In greenstone, the felspar is 
 almost always green, or greenish ; here, on 
 the contrary, it is as constantly red, or red- 
 dish. Quartz and mica are very rare in 
 greenstone, and in inconsiderable quantity ; 
 whereas they are rather frequent in sienite. 
 Lastly, greenstone commonly contains iron 
 pyrites, which never occurs in sienite. 
 
 It has either a simple granular base, or it 
 is granular porphyritic; and then it is deno- 
 minated porphyritic sienite. When the parts 
 of the granular base are so minute as to be 
 distinguished with difficulty, and it contains 
 imbedded in it large crystals of felspar, the 
 rock is termed sienite-porphyry. It is some- 
 times unstratified, sometimes very distinctly 
 stratified. It sometimes shews a tendency 
 to the columnar structure. It contains no 
 foreign beds. It occurs in unconformable 
 and overlying stratification, over granite, 
 gneiss, mica-slate, and clay-slate, and is 
 pretty continuous, and covers most of the 
 primitive rocks. It is equally metalliferous 
 with porphyry. In the Island of Cyprus, it 
 affords much copper; many of the impor- 
 tant silver and gold mines in Hungary are 
 situated in it. The sienite of the Forest of 
 Thuringia, affords iron. In this country, 
 there is a fine example of sienite, in Gallo- 
 way, where it forms a considerable portion 
 of the hill called Criffle. On the Continent, 
 it occurs in the Electorate of Saxony ; and in 
 Upper Egypt, at the city of Syena, in The- 
 baid, at the cataracts of the Nile, whence it 
 derives its name. The Romans brought it 
 from that place to Rome, for architectural 
 and statuary purposes. — Jameson .* 
 
 * Silica. One of the primitive earths, 
 which in consequence of Sir H. Davy’s re- 
 searches on the metallic bases of the alkalis 
 and earths, has been recently regarded as a 
 compound of a peculiar combustible princi- 
 ple with oxygen. If we ignite powdered 
 quartz with three parts of pure potash in a 
 silver crucible, dissolve the fused compound 
 in water, add to the solution a quantity of 
 acid, equivalent to saturate the alkali, and 
 evaporate to dryness, we shall obtain a fine 
 gritty powder, which being well washed with 
 hot water, and ignited, will leave pure silica. 
 By passing the vapour of potassium over 
 silica in an ignited tube, Sir H. Davy ob- 
 tained a dark-coloured powder, which appa- 
 rently contained silicon, or silicium, the basis 
 ot the earth. Like boron and carbon, it is ca- 
 llable of sustaining a high temperature with- 
 out suffering any change. Aqueous potash 
 
SIL 
 
 SIL 
 
 seems to form with it an olive-coloured so- 
 lution. But as this basis is decomposed by 
 water, it was not possible to wash away the 
 potash by this liquid. Berzelius and Stro- 
 xneyer tried to form an alloy of silicon or 
 silicium with iron, by exposing to the strong- 
 est heat of a blast furnace, a mixture of three 
 parts of iron, 1.5 silica, and 0.66 charcoal. 
 It was in the state of fused globules. These 
 freed from the charcoal, were white and 
 ductile, and their solution in muriatic acid 
 evolved more hydrogen than an equal weight 
 of iron. The sp. gravity of the alloy was 
 from 6.7 to 7.3, while that of the iron used 
 was 7.8285. From Mr Mushet’s experi- 
 ments, however, as well as from the consti- 
 tution of plumbago, we know that carbon 
 will combine with iron in very consider- 
 able proportions, and that in certain quan- 
 tities, it can give it a whitish colour and in- 
 ferior density. Nothing definitive therefore 
 can be inferred from these experiments. See 
 Iron. 
 
 Sir H. Davy found, that more than three 
 parts of potassium were required to decom- 
 pose one part of silica. Hence w r e might 
 infer, that 100 parts of silica contain about 
 60 of oxygen. In this case, the prime equi- 
 valent of silicon, or silicium, would be 1.5, 
 and that of silica 2.5 ; but little confidence 
 can at present be reposed in such deductions. 
 
 “ When iron,” says Sir FI. Davy, “ is 
 negatively electrified, and fused by the vol- 
 taic battery in contact with hydrate of silica, 
 the metalline globule procured contains a mat- 
 ter which aflbrds silex during its solution ; 
 and w’hen potassium is brought in contact 
 with silica ignited to whiteness, a compound 
 is formed, consisting of silica and potassa ; 
 and black particles, not unlike plumbago, 
 are found diffused through the compound. 
 From some experiments I made, 1 am in- 
 
 Froportions. 
 
 80 silica, 
 
 20 barytes, 
 
 75 silica, 
 
 25 barytes, ^ 
 
 66 silica, 
 
 33 barytes, 
 
 50 silica, 
 
 50 barytes, 
 
 20 silica, 
 
 80 barytes, \ 
 
 25 silica, 
 
 75 barytes, 
 
 33 silica, 
 
 66 barytes, 
 
 Wh en the barytes exceeds the silica in the 
 proportion of three to one, the fused mass is 
 soluble in acids, — a circumstance recently 
 applied with great advantage in the analysis 
 of minerals which contain alkaline matter. 
 The habitudes of strontian with silica are 
 
 dined to believe, that these particles are con- 
 ductors of electricity ; they have little action 
 upon w'ater, unless it contain acid, when 
 they slowly dissolve in it with effervescence; 
 they burn when strongly heated, and become 
 converted into a white substance, having the 
 characters of silica ; so that there can be 
 little doubt, both from analysis and synthesis, 
 of the nature of silica.” Elements , p. 365. 
 
 I have already mentioned in treating of 
 earths, that Mr Smithson had ingeniously 
 suggested, that silica might be viewed in 
 many mineral compounds as acting the part 
 of an acid. This however is a vague ana- 
 logy, and cannot justify us in ranking silica 
 with acid bodies. 
 
 When obtained by the process first des- 
 cribed, it is a white powder, whose finest 
 particles have a harsh and gritty feel. Its 
 sp. gr. is 2.66. It is fusible only by the hy- 
 droxygen blow-pipe. The saline menstruum, 
 formed by neutralizing its alkaline solution 
 with an acid, is capable of holding it dis- 
 solved, though silica seems by experiment to 
 be insoluble in water. Yet in the water of 
 the Geyser spring, a portion of silica seems 
 to remain dissolved, though the quantity of 
 alkali present appears inadequate to the 
 effect. Silica exists nearly pure in transpa- 
 rent quartz or rock crystal. It forms also 
 the chief constituent of flints. By leaving a 
 solution of silica in fluoric acid, or in aqueous 
 potash, undisturbed for a long time, crystals 
 of this earth have been obtained. The solu- 
 tion in alkaline lixivia is called liquor s ili- 
 cum. Glass is a compound of a similar na- 
 ture, in wdiich the proportion of silica is 
 much greater. 
 
 Mr Kirvvan made many experiments on 
 the mutual actions of silica and the other 
 earths, at high degrees of heat. The follow- 
 ing are some of his results : 
 
 Effects. 
 
 nearly the same as those with barytes. Lime 
 water added to the liquor silicum , occasions 
 a precipitate which is a compound of the 
 two earths. The following arc Mr Kirwan’s 
 results in the dry way - 
 
 Heat. 
 
 j- 1 50° Wedg. A white brittle mass. 
 
 i 
 5 
 S 
 
 \ 
 
 I 
 
 150 
 
 150 
 
 148 
 
 14S 
 
 150 
 
 150 
 
 A brittle hard mass, semi-transparent at the edges. 
 Melted into a hard somewhat porous porcelain. 
 
 A hard mass, not melted. 
 
 The edges were melted into a pale greenish matter, be- 
 tween a porcelain and enamel. 
 
 Melted into a somewhat porous porcelain mass. 
 
 Melted into a yellowish and partly greenish white 
 porous porcelain. 
 
SIL 
 
 SIL 
 
 Proportions. 
 
 50 lime, 
 
 50 silica, 
 
 80 lime, 
 
 20 silica, 
 
 20 lime, 
 
 80 silica, 
 
 When exposed to the highest possible heat, 
 magnesia and silica, in equal parts, melt in- 
 to a white enamel. 
 
 Silica and alumina unite both in the liquid 
 and dry way. The latter compound consti- 
 tutes porcelain and pottery- ware. 
 
 Equal parts of lime, magnesia, and silica, 
 melt, according to Achard, into a greenish- 
 coloured glass, hard enough to strike fire 
 with steel. When the magnesia exceeds 
 either of the other two ingredients, the 
 mixture is infusible ; when the silica ex- 
 ceeds, the only fusible proportions were, 
 5 silica, 2 lime, 1 magnesia ; and when the 
 lime is in excess, the mixture usually melts 
 in a strong heat. With mixtures of lime, 
 alumina, and silica, a fusible compound is 
 usually obtained when the lime predominates. 
 The only refractory proportions were, 
 
 Lime, 2 3 
 
 Silica, 1 1 
 
 Alumina, 2 2 
 
 Excess of silica gives a glass or poi'celain, 
 but excess of alumina will not furnish a glass. 
 
 When in mixtures of magnesia, silica, and 
 alumina, the first is in excess, no fusion takes 
 place at 150°; when the second exceeds, a 
 porcelain may be formed, and 5 parts of 
 silica, 2 magnesia, and 1 alumina, form a 
 glass. From Achard’s experiments it would 
 appear, that a glass may be produced by ex- 
 posing to a strong heat, equal parts of alu- 
 mina, silica, lime, and magnesia. 
 
 Other proportions gave fusible mixtures, 
 provided the silica was in excess. 
 
 The mineral sommite, or nephelin, con- 
 sists, accoding to Vauquelin, of 4 9 alumina 
 46 silica. If we suppose it to consist of 
 a prime equivalent or atom of each consti- 
 tuent, then that of silica would be 3 ; for 
 49 : 3.2 : : 46 : 5. But if we take Vauque- 
 lin’s analysis of euclase for the same pur- 
 pose, we have the proportion of silica to that 
 of alumina as 55 to 22. Hence, 22 : 3.2 : : 
 55 : 5.09 the prime equivalent of silica, w hich 
 is not reconcileable to the above number, 
 though it agrees with that deducted from 
 Sir II. Davy’s experiments on silicon. I 
 give these examples to shew how unprofit- 
 able such atomical determinations are. See 
 Iron and Acid (Fluosilic).* 
 
 Sit.K. See Bleaching. 
 
 Sil van. Tellurium, so called by Werner. 
 Silver is the whitest of all metals, consi- 
 derably harder than gold, very ductile and 
 
 formed a brittle mass. 
 
 malleable, but less malleable than gold ; for 
 the continuity of its parts begins to break 
 when it is hammered out into leaves of about 
 the hundred and sixty thousandth of an inch 
 thick, which is more than one-third thicker 
 than gold leaf ; in this state it does not trans- 
 mit the light. Its specific gravity is from 
 10.4 to 10.5. It ignites before melting, and 
 requires a strong heat to fuse it. The heat 
 of common furnaces is insufficient to oxidize 
 it; but the heat of the most powerful burn- 
 ing lenses vitrifies a portion of it, and causes 
 it to emit fumes; which, when received on 
 a plate of gold, are found to be silver in the 
 metallic state. It has likewise been partly 
 oxidized by twenty successive exposures to 
 the heat of the porcelain furnace at Sevres. 
 By passing a strong electric shock through 
 a silver wire, it may be converted into a 
 black oxide ; and by a powerful galvanic 
 battery, silver leaf may be made to burn 
 with a beautiful green light. Lavoisier oxi- 
 dized it by the blow-pipe and oxygen gas; 
 and a fine silver wire burns in the kindled 
 united stream of oxygen and hydrogen gases. 
 The air alters it very little, though it is dis- 
 posed to obtain a thin purple or black coat- 
 ing from the sulphurous vapours, which are 
 emitted from animal substances, drains, or 
 putrefying matters. This coating, after a 
 long series of years, has been observed to 
 scale off from images of silver exposed in 
 churches ; and was found, on examination, 
 to consist of silver united w’ith sulphur. 
 
 * There seems to be only 1 oxide of sil- 
 ver, w r hich is formed either by intense igni- 
 tion in an open vessel, when an olive-co- 
 loured glass is obtained ; or by adding a so- 
 lution of caustic barytes to 1 of nitrate of 
 silver, and heating the precipitate to dull 
 redness. Sir FI. Davy found that 100 of 
 silver combine W'ith 7.3 of oxygen in the 
 above oxide; and if we suppose it to consist 
 of a prime equivalent of each constituent, 
 we shall have 15.7 for the prime of silver. 
 Silver leaf burned by a voltaic battery, affords 
 the same olive-coloured oxide. 
 
 Silver combines with chlorine, when the 
 metal is heated in contact with the gas. 
 This chloride is, however, usually prepared 
 by adding muriatic acid or a muriate, to ni- 
 trate of silver. It has been long known by 
 the name of luna-cornea or horn-silver, be- 
 cause though a white pow'der, as it falls down 
 from the nitrate solution, it fuses at a moderate 
 
 Heat. 
 
 j- 150° Wedg. 
 
 } 
 
 } 
 
 156 
 
 156 
 
 Effects. 
 
 Melted into a mass of a white colour, semi-transparent 
 at the edges, and striking fire, though feebly, with steel : 
 it was intermediate between porcelain and enamel. 
 
 A yellowish- white loose powder. 
 
 Not melted : 
 
SIL 
 
 SIL 
 
 heat, and forms a horny looking substance 
 when it tools. It consists of 1 3.7 silver -f- 
 4.5 chlorine. 
 
 The sulphuret of silver is a brittle sub- 
 stance, ot a black colour and metallic lustre. 
 It is formed by heating to redness thin 
 plates of silver stratified with sulphur. It 
 consists of 15.7 silver 2 sulphur. 
 
 Fulminating silver is formed by pouring 
 lime-water into the pure nitrate, and filter- 
 ing, washing the precipitate, and then digest- 
 ing on it liquid ammonia in a little open 
 capsule. In 12 hours, the ammonia must 
 be cautiously decanted from the black pow- 
 der, which is to be dried in minute portions, 
 and with extreme circumspection, on bits of 
 filtering paper or card. If struck, in even 
 its moist state, with a hard body, it explodes ; 
 and if in any quantity, when dry, the ful- 
 mination is tremendous. 'The decanted am- 
 monia, on being gently heated, effervesces, 
 from disengagement of azote, and small 
 crystals appear in it when it cools. These 
 possess a still more formidable power of de- 
 tonation, and can scarcely bear touching, 
 even under the liquid. It seems to be a 
 compound either of oxide of silver and am- 
 monia, or of the oxide and azote. The lat- 
 ter is probably its true constitution, like the 
 explosive iodide and chloride. The sudden 
 extrication of the condensed gas, is the cause 
 of the detonation. 
 
 In the 8th number of the Journal of 
 Science, Mr Farraday has described some 
 experiments which seem to shew that there 
 is a protoxide of silver containing about two- 
 thirds the quantity of oxygen found in the 
 common oxide, by precipitation from the 
 nitrate. Fie procures it by leaving an am- 
 moniacal solution of oxide of silver exposed 
 to the air. A succession of brilliant pellicles 
 is obtained, which are the protoxide. Expe- 
 riments of this nature must be made cautious- 
 ly, least fulminating compounds should acci- 
 dentally be produced.* 
 
 Silver is soluble in the sulphuric acid when 
 concentrated and boiling, and the metal in a 
 state of division. 
 
 The muriatic acid does not act upon it, 
 but the nitric acid, if somewhat diluted, dis- 
 solves it with great rapidity, and with a plen- 
 tiful disengagement of nitrous gas ; which, 
 during its extrication, gives a blue or green 
 colour to the acid, that entirely disappears if 
 the silver made use of be pure ; if it contain 
 copper, the solution remains greenish ; and 
 if the acid contain either sulphuric or muria- 
 tic acid, these combine with a portion of the 
 silver, and form scarcely soluble compounds, 
 which fall to the bottom. If the silver con- 
 tain gold, this metal separates in blackish- 
 coloured flocks. 
 
 The nitric acid dissolves more than halt 
 its weight of silver ; and the solution is very 
 
 caustic, that is to say, it destroys and corrodes 
 animal substances very powerfully. 
 
 The solution of silver, when fully satu- 
 rated, deposits thin crystals as it cools, and 
 also by evaporation. These are called lunar 
 nitre, or nitrate of silver. A gentle heat is 
 sufficient to fuse them, and drive off their 
 water of crystallization. In this situation 
 the nitrate, or rather subnitrate, for the heat 
 drives off part of the acid, is of a black co- 
 lour, may be cast into small sticks in a 
 mould, and then forms the lapis infernal is, 
 or lunar caustic used in surgery. A stronger 
 heat decomposes nitrate of silver, the acid 
 flying off, and the silver remaining pure. It 
 k obvious that, for the purpose of forming 
 the lunar caustic, it is not necessary to suffer 
 the salt to crystallize, but that it may be 
 made by evaporating the solution of silver at 
 once to dryness; and as soon as the salt is 
 fused, and ceases to boil, it may be poured 
 out. The nitric acid driven off from nitrate 
 of silver is decomposed, the products being 
 oxygen and nitrogen. 
 
 The sulphate of silver, which is formed 
 by pouring sulphuric acid into the nitric so- 
 lution of silver, is sparingly soluble in water ; 
 and on this account forms crystals, which 
 are so small, that they compose a white pow- 
 der. The muriatic acid precipitates from 
 nitric acid the saline compound called luna- 
 cornea, or horn- silver ; which has been so 
 distinguished, because, when melted and 
 cooled, it forms a semi-transparent and partly 
 flexible mass, resembling horn. It is sup- 
 posed that a preparation of this kind has 
 given rise to the accounts of malleable glass. 
 This effect takes place with aqua regia, 
 which acts strongly on silver, but precipitates 
 it in the form of muriate, as fast as it is 
 dissolved. 
 
 If any salt with base of alkali, containing 
 the muriatic acid, be added to the nitric so- 
 lution of silver, the same effect takes place 
 by double affinity; the alkaline base unit- 
 ing with the nitric acid, and the silver fall- 
 ing down in combination with the muriatic 
 
 O 
 
 acid. 
 
 Since the muriatic acid throws down only 
 silver, lead, and mercury, ftirid the latter of 
 these two is not present in silver that has 
 passed cupellation, though a small quantity 
 of copper may elude the scorification in that 
 process, the silver which may he revived 
 from its muriate is purer than can readily 
 be Obtained by any other means. When 
 this salt is exposed to a low red-heat, its 
 acid is not expelled ; and a greater heat 
 causes the whole concrete either to rise in 
 fumes, or to pass through the pores of the 
 vessel. To reduce it, therefore, it is neces- 
 sary that it should be triturated with its 
 own weight of fixed alkali, and a little wa- 
 ter, and the whole afterwards exposed to heat 
 
SIL 
 
 in a crucible, the bottom of which is covered 
 with soda ; the mass of muriate of silver being 
 likewise covered with the same substance. 
 In this way the acid will be separated from 
 the silver, which is reduced to its metallic 
 state. 
 
 As the precipitate of muriate of silver is 
 very perceptible, the nitric solution of silver 
 is used as a test of the presence of muriatic 
 a^id in waters ; for a drop of this solution 
 poured into such waters will cause a very 
 evident cloudiness. The solution of silver 
 is also used by assayers to purify the nitric 
 acid from any admixture of muriatic acid. 
 In this state they call it precipitated aqua- 
 fortis. 
 
 M. Chenevix found, that a chlorate of 
 silver may be formed, by passing a current of 
 chlorine through water in which oxide of 
 silver is suspended ; or by digesting phos- 
 phate of silver with hyperoxymuriate of alu- 
 mina. It requires only two parts of hot water 
 for its solution, and this affords on cooling, 
 small white, opaque, rhomboidal crystals. It 
 is likewise somewhat soluble in alcohol. Half 
 a grain, mixed with half as much sulphur, 
 and struck or rubbed, detonates with a loud 
 report and a vivid flash. 
 
 Compounds of silver with other acids are 
 best formed by precipitation from its solu- 
 tion in nitric acid ; either by the acid itself, 
 or by its alkaline salts. Phosphate of silver is 
 a dense white precipitate, insoluble in water, 
 but soluble in an excess of its acid. By heat 
 it fuses into a greenish opaque glass. Car- 
 bonate of silver is a white insoluble powder, 
 which is blackened by light. The fluate and 
 borate are equally soluble. Distilled vinegar 
 readily dissolves the oxide of silver, and the 
 solution affords long white needles, easily 
 crystallized. 
 
 The precipitates of silver, which are formed 
 by the addition of alkalis or earths, are all re- 
 ducible by mere heat, without the addition of 
 any combustible substance. 
 
 A detonating powder has been sold lately 
 at Paris as an object of amusement. It is 
 enclosed between the folds of a card, cut in 
 two lengthwise ; the powder being placed 
 at one end, and the other being notched, 
 that it may be distinguished. If it be taken 
 by the notched end, and the other be held 
 over the flame of a candle, it soon detonates, 
 with a sharp sound, and violent flame. The 
 card is torn, and changed brown; and the 
 part in contact with the composition is cover- 
 ed with'a slight metallic coating, of a greyish- 
 white colour. 
 
 This compound, which M. Descotils calls 
 detonating silver, to distinguish it from the 
 fulminating silver of M. Berthollet, may be 
 made by dissolving silver in pure nitric acid, 
 and pouring into the solution, while it is 
 going on, a sufficient quantity of rectified 
 alcohol : or by adding alcohol to a nitric 
 
 SIL 
 
 solution of silver with considerable excess oi 
 acid. 
 
 In the first case, the nitric acid, into which 
 the silver is put, must be heated gently, till 
 the solution commences, that is, till the first 
 bubbles begin to appear. It is then to be 
 removed from the fire, and a sufficient quan- 
 tity of alcohol to be added immediately, to 
 prevent the evolution of any nitrous vapours. 
 The mixture of the two liquors occasions an 
 extrication of heat; the effervescence quickly 
 recommences, without any nitrous gas being 
 disengaged ; and it gradually increases, emit- 
 ting at the same time a strong smell of nitric 
 ether. In a short time the liquor becomes 
 turbid, and a very heavy, white, crystalline 
 powder falls down, which must be separated, 
 when it ceases to increase, and washed seve- 
 ral times with small quantities of w’ater. 
 
 If a very acid solution of silver previously 
 made be employed, it must be heated gently, 
 and the alcohol then added. The heat ex- 
 cited by the mixture, which is to be made 
 gradually, soon occasions a considerable 
 ebullition, and the powder immediately pre- 
 cipitates. 
 
 It would be superfluous to remind the 
 chemist, that the mixture of alcohol with hot 
 nitric acid is liable to occasion accidents, and 
 that it is consequently prudent to operate on 
 small quantities. 
 
 This powder has the following properties : 
 It is white and crystalline; but the size and 
 lustre of the crystals are variable. Light 
 alters it a little. Heat, a blow, or long con- 
 tinued friction, causes it to inflame with a 
 brisk detonation. Pressure alone, if it be 
 not very powerful, has no effect on it. It 
 likewise detonates by the electric spark. It 
 is slightly soluble in water. It has a very 
 strong metallic taste. 
 
 Concentrated sulphuric acid occasions it 
 to take fire, and is throwm by it to a conside- 
 rable distance. Dilute sulphuric acid ap- 
 pears to decompose it slowly. 
 
 Process for separating silver from copper , by 
 
 Mr Keir. 
 
 Put the pieces of plated metal into an 
 earthen glazed pan ; pour upon them some 
 acid liquor, which may be in the proportion 
 of eight or ten pounds of sulphuric acid to 
 one pound of nitre ; stir them about, that 
 the surfaces may be frequently exposed to 
 fresh liquor, and assist the action by a gentle 
 heat from 1 00° to 200° of Fahrenheit’s scale. 
 When the liquor is nearly saturated, the sil- 
 ver is to be precipitated from it by common 
 salt, which forms a muriate of silver, easily 
 reducible by melting it in a crucible with a 
 sufficient quantity of potash ; and lastly, by 
 refining the melted silver if necessary, with 
 a little nitre thrown upon it. In this man- 
 ner the silver will be obtained sufficiently 
 pure, and the copper will remain unchanged. 
 
SIL 
 
 SIL 
 
 Otherwise, the silver may he precipitated in 
 its metallic state, by adding to the solution 
 ot silver a tew ot the pieces of copper, and 
 a sufficient quantity of water to enable the 
 liquor to act upon the copper. 
 
 Mr Andrew Thomson, of Banchory, has 
 recommended the following method of puri- 
 fying silver, which he observes is equally ap- 
 plicable to gold. The impure silver is to 
 be flatted out to the thinness of a shilling, 
 coiled up spirally, and put into a crucible, 
 the bottom of which is covered with black 
 oxide of manganese. More of this oxide is 
 then to be added, till the silver is completely 
 covered, and all the spaces between the coils 
 filled. A cover is then to be luted on, with 
 a small hole for the escape of the gas ; and 
 after it has been exposed to a heat sufficient 
 to melt silver for about a quarter of an hour, 
 the whole of the alloy will be oxidized. The 
 contents of this crucible are then to be pour- 
 ed into a larger, into which about three times 
 as much powdered green glass has been 
 previously put; a cover luted on as before, 
 to prevent the access of any inflammable 
 matter ; and the crucible exposed to a heat 
 sufficiently strong to melt the glass very 
 fluid. On cooling and breaking the crucible, 
 the silver will be found reduced at the bot- 
 tom, and perfectly pure. 
 
 Sulphur combines very easily with silver, 
 if thin plates, imbedded in it, be exposed to 
 a heat sufficient to melt the sulphur. The 
 sulphuret is of a deep violet colour, approach- 
 ing to black, with a degree of metallic lustre, 
 opaque, brittle and soft. It is more fusible 
 than silver, and this in proportion to the 
 quantity of sulphur combined with it. A 
 strong heat expels part of the sulphur. 
 
 Sulphuretted hydrogen soon tarnishes the 
 surface of polished silver, and forms on it a 
 thin layer of sulphuret. 
 
 The alkaline sulphurets combine with it 
 by heat, and form a compound soluble in 
 water. Acids precipitate sulphuret of silver 
 from this solution. 
 
 Phosphorus, left in a nitric solution of 
 silver, becomes covered with the metal in a 
 dendritic form. By boiling, this becomes 
 first white, then a light black mass, and is 
 ultimately converted into a light brown phos- 
 phuret. The best method of forming a phos- 
 phuret of silver is Pelletier’s, which consists 
 in mixing phosphoric acid and charcoal with 
 the metal, and exposing the mixture to heat. 
 
 Most metallic substances precipitate silver 
 in the metallic state from its solution. The 
 assayers make use of copper to separate the 
 silver from the nitric acid used in the pro- 
 cess of parting. The precipitation of silver 
 by mercury is very slow, and produces a 
 peculiar symmetrical arrangement, called 
 the tree of Diana. In this, as in all preci- 
 pitations, the peculiar form may be affected 
 by a variety of concomitant circumstances; 
 
 for which reason one process usually suc- 
 ceeds better than another. 
 
 Make an amalgam, without heat, of four 
 drachms of leaf silver with two drachms of 
 mercury. Dissolve the amalgam in four 
 ounces, or a sufficient quantity of pure nitric 
 acid of a moderate strength ; dilute this so- 
 lution in about a pound and a half of distill- 
 ed water ; agitate the mixture, and preserve 
 it for use in a glass bottle with a ground 
 stopper. When this preparation is to be 
 used, the quantity of one ounce is put into a 
 phial, and the size of a pea of amalgam of 
 gold, or silver, as soft as butter, is to be add- 
 ed ; after which the vessel must be left at 
 rest. Soon afterwards small filaments ap- 
 pear to issue out of the ball of amalgam, 
 which quickly increase, and shoot out branch- 
 es in the form of shrubs. 
 
 Silver unites with gold by fusion, and 
 forms a pale alloy, as has been already men- 
 tioned in treating of that metal. With pla- 
 tina it forms a hard mixture, rather yellower 
 than silver itself, and of difficult fusion. 
 The turn metals do not unite well. Silver 
 melted with one- tenth part of crude platina, 
 from which the ferruginous particles had 
 been separated by a strong magnet, could 
 not be rendered clear of scabrous parts, 
 though it w r as repeatedly fused, poured out, 
 and laminated between rollers. It was then 
 fused, and suffered to cool in the crucible, 
 but with no better success. After it had 
 been formed, by rolling and hammering, in- 
 to a spoon for blow-pipe experiments, it was 
 exposed to a low red-heat, and became rough, 
 and blistered over its whole surface. The 
 quantities were one hundred grains of silver, 
 and ten grains of platina. Nitre was added 
 during: the fusions. 
 
 Silver very readily combines with mer- 
 cury. A very sensible degree of heat is 
 produced, when silver leaf and mercury are 
 kneaded together in the palm of the hand. 
 With lead it forms a soft mass, less sonorous 
 than pure silver. With copper it becomes 
 harder and more sonorous, at the same time 
 that it remains sufficiently ductile : this 
 
 mixture is used in the British coinage. Til- 
 parts of silver, alloyed with one of copper, 
 form the compound called standard silver. 
 The mixture of silver and iron has been 
 little examined. With tin it forms a com- 
 pound, which, like that of gold with the 
 same metal, has been said to be brittle, how- 
 ever small the proportion ; though there is 
 probably as little foundation for the asser- 
 tion in the one case as in the other. With 
 bismuth, arsenic, zinc, and antimony, it forms 
 brittle compounds. It docs not unite with 
 nickel. The compound of silver and tung- 
 sten, in the proportion of two of the former 
 to one of the latter, was extended under the 
 hammer during a few strokes; but after- 
 wards split in pieces. Sec Iron. 
 
SIL 
 
 SKO 
 
 The uses of silver are well known : it is 
 chiefly applied to the forming of various 
 utensils for domestic use, and as the medium 
 of exchange in money. Its disposition to 
 assume a black colour by tarnishing, and 
 its softness, appear to be the chief objection 
 to its use in the construction of graduated 
 instruments for astronomical and other pur- 
 poses, in which a good white metal would 
 be a desirable acquisition. The nitrate of 
 silver, beside its great use as a caustic, has 
 been employed as a medicine, it is said with 
 good success, in epileptic cases, in the dose 
 of 1 -20th of a grain, gradually increased to 
 1 -8th, three times a-day. Dr Cappe gave it 
 in a dose of l-4th of a grain three times a- 
 day, and afterward four times, in what he 
 supposed to be a case of angina pectoris, in 
 a stout man of sixty, whom he cured. He 
 took it for two or three months. Dr Cappe 
 imagines, that it has the effect of increasing 
 the nervous power, by which muscular ac- 
 tion is excited. 
 
 * The frequent employment in chemical 
 researches of nitrate of silver as a reagent 
 for combined chlorine, occasions the produc- 
 tion of a considerable quantity of the chloride 
 (muriate) of silver, which is usually recon- 
 verted into metal by fusion with potash in 
 a crucible. But, as much of the silver is 
 lost in this way, it is better to expose the 
 following mixture to the requisite heat: 
 
 Chloride of silver, 100 
 
 Dry quicklime, - 19.8 
 
 Powdered charcoal, - 4.2 
 
 An easier method, however, is to put the 
 metallic chloride into a pot of clean iron or 
 zinc, to cover it with a small quantity of 
 water, and to add a little sulphuric or muri- 
 atic acid. The reduction of the chloride of 
 silver by the zinc or iron, is an operation 
 which it is curious to observe, especially with 
 the chloride in mass ( luna-corneci ). It be- 
 
 gins first at the points of contact, and speed- 
 ily extends in the form .of ramifications, over 
 its whole surface, and into its interior. 
 Hence, in less than an hour, considerable 
 pieces of horn-silver are entirely reduced. 
 If the mass operated on, be considerable, 
 the temperature rises, and accelerates the 
 revivification. On the small scale artificial 
 heat may be applied.* — Ann. de Chimie. 
 July 1 820. 
 
 Silvering. There are various methods 
 of giving a covering of silver or silvery 
 aspect to the surfaces of bodies. The appli- 
 cation of silver leaf is made in the same way 
 as that of gold, for which see Gilding. 
 
 Copper may be silvered over by rubbing 
 it with the following powder: Two drachms 
 of tartar, the same quantity of common salt, 
 and half a drachm of alum, are mixed with 
 fifteen or twenty grains of silver precipi- 
 
 tated from nitric acid by copper. The sur- 
 face of the copper becomes white when 
 rubbed with this powder, which may after- 
 ward be brushed of!' and polished with lea- 
 ther. 
 
 The saddlers and harness-makers cover 
 their wares with tin for ordinary uses, but a 
 cheap silvering is used for this purpose as 
 follows : Half an ounce of silver that has 
 been precipitated from aquafortis by the ad- 
 dition of copper, common salt, and muriate 
 of ammonia, of each two ounces, and one 
 drachm of corrosive muriate of mercury, are 
 triturated together, and made into a paste 
 with water ; with this, copper utensils of 
 every kind, that have been previously boiled 
 with tartar and alum, are rubbed, after 
 which they are made red-hot, and then 
 polished. The intention of this process 
 appears to be little more than to apply the 
 silver in a state of minute division to the 
 clean surface of the copper, and afterward 
 to fix it there by fusion ; and accordingly 
 this silvering may be effected by using the 
 argentine precipitate here mentioned, with 
 borax or mercury, and causing it to adhere 
 by fusion. 
 
 The dial-plates of clocks, the scales of ba- 
 rometers, and other similar articles are sil- 
 vered by rubbing upon them a mixture of 
 muriate of silver, sea salt, and tartar, and 
 afterward carefully washing off the saline 
 matter with water. In this operation, the 
 silver is precipitated from the muriatic acid, 
 which unites with part of the coppery sur- 
 face. It is not durable, but may be im- 
 proved by heating the article, and repeating 
 the operation till the covering seems suffi- 
 ciently thick. 
 
 The silvering of pins is effected by boil- 
 ing them with tin filings and tartar. 
 
 Hollow mirrors or globes are silvered by 
 an amalgam consisting of one part by weight 
 of bismuth, half a part of lead, the same 
 quantity of pure tin, and two parts mercury. 
 The solid metals are to be first fused tosre- 
 ther, and the mercury added when the mix- 
 ture is almost cold. A very gentle heat is 
 sufficient to fuse this amalgam. In this state 
 it is poured into a clean glass globe intended 
 to be silvered, by means of a paper funnel 
 which reaches to the bottom. At a certain 
 temperature, it will stick to the glass, which 
 by a proper motion may thus be silvered 
 completely, and the superfluous amalgam 
 poured out. The appearance of these toys 
 is varied by using glass of different colours, 
 such as yellow, blue, or green. 
 
 * Skorodite. Colour leek-green. Mas- 
 sive, but generally crystallized in very short 
 broad rectangular four-sided prisms. Frac- 
 ture uneven. Translucent. As hard as cal- 
 careous spar. Easily frangible. It melts 
 before the blow- pipe, with emission of arso- 
 
SOA 
 
 SOA 
 
 meal vapour, and is converted into a reddish- 
 brown mass, which, when highly heated, so 
 as to drive off all the arsenic, becomes attract- 
 ive by the magnet. It is an arseniate of 
 iron, without copper. It occurs in quartz 
 and hornstone, in primitive rocks, in the 
 Schneeberg mining district in Saxony.* 
 
 * Slate (Adhesive). See Clay.* 
 
 * Slate Clay. See Clay.* 
 
 * Slate Coal. See Coal.* 
 
 * Slate Spar, or Schiefer Spar. A 
 sub-species of limestone.* 
 
 * Slickensides. The specular variety of 
 Golena, so called in Derbyshire. It ex- 
 presses the smoothness of its surface. It 
 occurs lining the walls of very narrow rents. 
 It has a most remarkable property, that when 
 the rock in which it is contained is struck 
 with a hammer, a crackling noise is heard, 
 which is generally followed by an explosion 
 of the rock, in the direction and neighbour- 
 hood of the vein. The cause of this singu- 
 lar effect has not been satisfactorily explain- 
 ed. — Jameson . * 
 
 Smalt. See Zaffre. 
 
 * Smaragdite. Diallage.* 
 
 Smaragdits. See Emerald. 
 
 Soap. Macquer gives us the following 
 process for oil soap : One part of quicklime 
 
 and two parts of good Spanish soda, are 
 boiled together during a short time, with 
 tw r elve times as much water, in an iron cal- 
 dron. This lixivium is to be filtered, and 
 evaporated by heat, till a phial, which is ca- 
 pable of containing an ounce of water, shall 
 contain an ounce and three- eighths of this 
 concentrated lixivium. One part of this 
 lixivium is to be mixed with two parts of oil 
 of olives, or of sweet almonds, in a glass or 
 stoneware vessel. The mixture is to be 
 stirred from time to time with an iron spa- 
 tula, or with a pestle, and it soon becomes 
 thick and white. The combination is gra- 
 dually completed, and in seven or eight days 
 a very white and firm soap is obtained. 
 
 For the coarser sorts of soap, cheaper oils 
 are employed, such as oil of nuts, linseed, 
 hempseed, fish, &c. Either of these kinds 
 of soap, to be good, must neither feel greasy 
 nor unctuous in water, nor exhibit any ves- 
 tige of fat upon the water. It ought farther 
 to dissolve easily in water, and lather well, 
 as likewise be easily soluble in alcohol. It 
 must not become moist in the air, or throw 
 out a saline efflorescence on its external sur- 
 face. 
 
 For making Brown or Yellow Soap. 
 
 Let there be weighed 10 cwt. of tallow, 
 and about 3 cwt. of resin, the resin to be 
 broken into small lumps. In the first place, 
 put into the boiler about 150 or 200 gallons 
 of ley, and set the fire ; then add the tallow 
 and resin. This done, the pan is said to be 
 charged. 
 
 A good fire may be kept up until all is 
 
 thoroughly melted, and the pan brought to 
 boil ; during which time, there ought to be 
 constant stilling with the paddle, to prevent 
 the resin from settling to the bottom. If 
 the goods or materials in the pan appear to 
 swell up, damp the fire, which is done by 
 opening the furnace door, and throwing 
 ashes thereon, (some have proper dampers), 
 when the whole will boil at leisure. As the 
 caustic alkali immediately unites to the tal- 
 low, there is no occasion for long boiling ; 
 about two or three hours will be long 
 enough. The fire may then be drawn, and 
 the pan allowed to stand for four or six 
 hours, when the weak ley may be pumped 
 off, and fresh added for a second boil. It 
 may be necessary to mention, that when the 
 pan is wished to be cranned, or pumped off 
 sooner, a few pails of cold ley must be thrown 
 in, a little after the fire is drawn. 
 
 Set the fire again for the second boil, and 
 when properly a-boil, two or three hours 
 may be sufficient at any one time to continue 
 the boil. The strength of the ley is often 
 gone before this period arrives. A short ex- 
 perience, however, with attention, will per- 
 fectly inform any sagacious person with re- 
 gard to this particular. 
 
 The boilings to be thus continued day- 
 after day, until the soap becomes thick, and 
 of a strong consistence. Take then a little 
 upon the forefinger, and after letting it cool 
 a few seconds, press it with the thumb. If 
 it squeeze into a thin, hard scale, the soap is 
 fit or ready for finishing : if otherwise it ap- 
 pear greasy, and stick to the finger, and of a 
 soft consistence, more ley must be added ; 
 and if this does not harden it, another boil 
 must be given. But, in consequence of the 
 former scaly appearance, give the pan a good 
 hearty boil, and draw the fire. Cool down 
 with two or three pails of ley, and in about 
 two hours thereafter pump off the ley ; which 
 should be done at all times as clean as pos- 
 sible. This done, put in six or eight pails 
 of water to the boiler, (no ley at finishing 
 being used), set a brisk fire, and keep con- 
 stantly stirring with hand-stirrer and paddle 
 alternately, until all is melted, and begins to 
 show an appearance something like thin 
 honey. Take now a little from a boiling 
 part upon the hand-board, and observe, 
 when held up, if any ley runs clearly from 
 it. If it do, more water must be put in, 
 and the boil continued. When, upon the 
 other hand, no ley runs from the soap when 
 held up slanting-ways upon the board, in 
 this case, too much water has already been 
 given. A little strong solution of salt must 
 now be added to open it, technically termed 
 cutting up ; or, instead of salt brine, a little 
 strong common salt and water ; about half a 
 pailful may do. We come now to the most 
 critical part of boiling, that is, the finishing 
 of the soap : and it ought to be particularly 
 
SOA 
 
 SOA 
 
 attended to, that the soap be brought to such 
 a state, as, when held up upon the hand- 
 board, the ley does not run down from the 
 soap, but is seen, as it were, just starting 
 from it. The fire may then be drawn away, 
 and the soap declared finished ; or if palm- 
 oil be wished for making it of a beautiful 
 colour, about 20 lbs. may be put into the 
 boiler, after you discover, as above, the soap 
 to be finished ; and in about half an hour 
 after the oil is put in, the fire may be drawn, 
 and the whole allowed to stand for forty- 
 eight hours, when it may be cast into the 
 frames. 
 
 In about three days, (supposing the frames 
 30 inches deep), the whole will cut up into 
 bars. 
 
 A Charge Jur pure White Soap. 
 
 The boiler being made perfectly clean, 
 put in 10 cwt. of best home melted tallow, 
 (no resin is used in white soap), with 200 
 gallons of ley ; melt down with a moderate 
 lire, as the goods now in hand are some- 
 thing similar to milk, exceeding apt to boil 
 over. 
 
 Close attention, therefore, is absolutely 
 needful upon this first boil; which may be 
 continued about two hours, with a moderate 
 fire, when it may be drawn away, and the 
 pan allowed to settle about two hours, when 
 the ley may be drawn off. The process to 
 be observed in this soap is exactly similar to 
 the last operation. Two or three boils a- day 
 to white soap may be given with great ease ; 
 the ley sooner subsiding in the boiler than 
 with yellow soap, and can be cleaner pump- 
 ed off. 
 
 When sufficient boils have been given, 
 and the soap is arrived at perfection, it will 
 assume an appearance something like a curdy 
 mass. Take then a little upon your fore- 
 finger, (as before directed), and if the same 
 effect seem to attend it, that is, when press- 
 ed with the thumb it squeeze into a thin, 
 hard, clear scale, and part freely from the 
 finger, the soap is ready for finishing. Draw 
 the fire cool down with a few pails of ley, 
 and in a short time thereafter pump clean 
 off*. 
 
 Set the fire, and add to the scap eight or 
 ten pails of water, (the pail I suppose to con- 
 tain about nine or ten English gallons), 
 u hen this is melted, and properly incorpo- 
 rated with the soap, try, as formerly directed, 
 it the ley run from it when held up upon the 
 hand-board. If it do, more water must he 
 put in. If it do not run, or there he no ap- 
 pearance of it, continue boiling for a short 
 while longer, and then add a pail of salt and 
 water pretty strong, mixed together ; about 
 one-third salt, and two-thirds water. This 
 will have the effect of cutting up the pan, or 
 separating the soap and water completely 
 iiom one another. When this is apparent, 
 draw tlie fire; let it stand for half an hour, 
 
 2 
 
 when the water will pump off, bringing 
 therewith most of the remaining alkaline ley 
 of the former boil. 
 
 This I call the first -washing ; and if kelp 
 ley has been used in the operation, the pro- 
 priety of this must be conspicuous, for the 
 water pumped off will be of an exceeding 
 dark bottle-green colour. The finishing of 
 white soap without this precaution, is the 
 sole cause of the blueness, so frequently ob- 
 served in this article when made and brought 
 to market. 
 
 The blue ley being pumped clean off, set 
 again the fire, and put into the boder six or 
 eight pails of water ; and when thoroughly 
 incorporated and boiled some time, try if the 
 water run from the soap. If it do, add wa- 
 ter in small quantities at a time, until it is 
 observed not to run, but, as formerly men- 
 tioned for yellow soap, to appear as just 
 starting from the soap. In this case, after 
 giving a good boil, and swelling the soap up 
 in the pan to near the brim, draw away all 
 the fire, and spread it about to die away. 
 The pan is now finished, and may stand 
 about twelve or fourteen hours ; and if the 
 quantity be large, that is, two, three, or four 
 ton, double this time to stand will be much 
 in favour of the soap, providing always, that 
 it can be kept very close and warm in the 
 boiler. If any blueness still appear, repeat 
 the washing. 
 
 Before casting, I would recommend the 
 frames to have a bottom and linin.'i of coarse 
 cloth, for white soap only. After all is cast 
 into the frames, let it he well stirred, or 
 crutched ; and it is very proper, that it also 
 he covered close up with old sheets, bass 
 matts, Sc. upon the top of the frame and 
 soap, and allowed to cool gradually, and all, 
 together. 
 
 In about three or four days, (supposing, 
 as formerly, the dip 30 inches), the cover- 
 ings and frames may be taken off', and the 
 whole cut up into such size of bars as may 
 best suit the customers. 
 
 To give this white soap the perfume of 
 what is commonly called Windsor scap, a 
 little of the essential oil of caraway seeds, 
 mixed with a small portion of alcohol, may 
 he incorporated with the soap when putting 
 into the frame, stirring it in by little at a time, 
 so as to diffuse it throughout the whole mass. 
 
 For making Ulac/c or Green S<rf't Soap. 
 
 The peculiar method pursued in making 
 this soap, differs considerably from that of 
 making hard soap. The hard has the whole 
 of the ley totally extracted before finishing : 
 soft soap, on the contrary, retains the whole 
 of the ley used in ihe making ; becoming, 
 with the other materials employed, one com- 
 pound body, called soft soap. A few ex- 
 amples will clearly explain the nature and 
 practical means made use of in producing 
 this very useful soap. 
 
 T 
 
SOA 
 
 SOD 
 
 We shall now commence an operation 
 with a charge for what is called 
 
 First Crown Soft Soap, 1 8 Barrels. 
 
 The quantity of ley requisite for comple- 
 tion of this charge will be about 400 gallons ; 
 about one- third of which must be put into 
 the boiler previous to any of the other mate- 
 rials : afterward add, 2 cwt. 2 qrs. of tallow, 
 2 cwt. 2 qrs. of hogs’-lard, and 70 gallons of 
 olive oil. The ley herein to be used is sup- 
 posed to be from Hungarian and English 
 (Essex) ashes. The proportion is one of the 
 English to eight of the Hungarian. The 
 particular mode of proceeding is this : After 
 the ley is put in, add the tallow, and light 
 the fire. When all the tallow is melted, put 
 in the oil, and draw the fire a little after- 
 ward, and allow the pan to stand about two 
 hours. Light again the fire, and add about 
 20 gallons more of the ley. After the pan 
 begius to boil, add now and then a little 
 more ley, for the purpose of preventing the 
 soap from boiling over ; and this adding of 
 ley is to be continued, until the soap is sup- 
 posed to be about half boiled, when it will 
 be time to try whether the soap have got too 
 much or too little ley. 
 
 . This trial is called proving , and is neces- 
 sary to be done several times during the 
 operation, and previous to the finishing. 
 The method of performing it is this : Pro- 
 vide a piece of glazed Dutch delft, and also 
 a clear clean knife ; with the knife take up 
 a piece of the soap from the pan, and if it 
 turn whitish thereon, and fall from it in short 
 pieces upon the delft, it is then to be con- 
 cluded that too much ley has been put in ; 
 to rectify which, a little more oil must be 
 added. On the contrary, if the soap want 
 ley, it will fall from the knife in long ropy 
 pieces ; in consequence of which add some 
 more ley. When, however, it happens to 
 be brought to perfection, neither wanting 
 more ley nor oil, but just in a right state, it 
 will then be observed, when taken upon the 
 knife, to stand the proper colour, not ropy, 
 nor too white, but transparent. The fire 
 may now be drawn, the soap being properly 
 finished, and ought immediately to be cast 
 into the barrels, firkins, &c. 
 
 Remember always, after the second time 
 the tire is lighted, to keep the soap boiling 
 briskly, till the pan is nearly ready, when it 
 ought to boil slow, until finishing, and ready 
 to cast. 
 
 A Charge for Second Crown Soft Soap. 
 
 280 lbs. of tallow, 
 
 140 gallons of ley. 
 
 82 gallons of whale oil. 
 
 Put in 100 gallons of ley, with the tallow, 
 and light the fire. When the tallow is 
 melted, add the oil, and draw the fire. Let 
 all stand for two hours. Again light the 
 fire, and add 20 gallons of ley. With this 
 the boiling is to be continued, until the soap 
 
 is about half finished, when 10 gallons more 
 of ley are to be added. During the remain- 
 der of the boiling, add, at different periods, 
 the other 10 gallons of ley, which will com- 
 pletely finish the soap. See Fat. 
 
 For eau de luce , Wiegleb directs, that in 
 two drachms of the strongest alcohol be dis- 
 solved from six to ten drops of rectified oil 
 of amber, and afterward one scruple of white 
 soap ; to this mixture is then to be poured 
 an ounce of pure ammonia, and the whole 
 well shaken together. 
 
 Soat-stone. See Steatite. 
 
 * Soda. Formerly called the mineral 
 alkali , because under the name of natron it 
 is found native in mineral seams or crusts. 
 The impure commercial substance called 
 barilla is the incinerated salsola soda. Kelp, 
 the incinerated sea-weed, is a still coarser 
 article, containing seldom above 2 or 3 per 
 cent of real soda, while barilla occasionally 
 contains 20. The crystallized carbonate of 
 soda of commerce is procured from the de- 
 composition of sulphate of soda, or muriate 
 of soda. The former is effected by calci- 
 nation with charcoal and chalk in a rever- 
 beratory furnace; the latter is accomplished 
 by the addition of carbonate of potash. To 
 procure pure soda, we must boil a solution 
 of the pure carbonate with half its weight of 
 quicklime, and after subsidence decant the 
 clear ley, and evaporate in a clean iron or 
 silver vessel, till the liquid flow’s quietly like 
 oil. It must then be poured out on a polish- 
 ed iron plate. It concretes into a hard white 
 cake, which is to be immediately broken in 
 
 m 
 
 pieces, and put up, while still hot, in a phial, 
 which must be well corked. If the carbo- 
 nate of soda be somewhat impure, then, 
 after the action of lime, and subsequent con- 
 centration of the ley, alcohol must be di- 
 gested on it, which will dissolve only the 
 caustic pure soda, and leave the heterogene- 
 ous salts. By distilling off the alcohol in a 
 silver alembic, the alkali may then be ob- 
 tained pure. 
 
 This white solid substance is, however, 
 not absolute soda, but a hydrate, consisting 
 of about 100 soda -j- 28 w ater ; or of near- 
 ly 77 -f- 23, in 100. If a piece of this soda 
 be exposed to the nir it softens, and becomes 
 pasty ; but it never deliquesces into an oily 
 looking liquid, as potash does. The soda in 
 fact soon becomes drier, because by absorp- 
 tion of carbonic acid from the air it passes 
 into an efflorescent carbonate. Soda is dis- 
 tinguishable from potash by sulphuric acid, 
 which forms a very soluble salt with the 
 former, and a sparingly soluble one with the 
 latter ; by muriate of platina and tartaric 
 acid, which occasion precipitates with pot- 
 ash salts, but not with those of soda. 
 
 The basis of soda is a peculiar metal, 
 called sodium, discovered by Sir II. Davy 
 in 1807, a few days after he discovered 
 
SOD 
 
 SOD 
 
 potassium. It may be procured in exactly 
 the same manner as potassium, by electrical 
 or chemical decomposition of the pure hy- 
 drate. A rather higher degree of heat, and 
 greater voltaic power, are required to decom- 
 pose soda than potash. Sodium resembles 
 potassium in many of its characters. It is 
 as white as silver, possesses great lustre, and 
 is a good conductor of electricity. It enters 
 into fusion at about 200° Fahr., and rises in 
 vapour at a strong red-heat. Its sp. gr. is, 
 according to MM. Gay Lussacand 'Ihenard, 
 0.972, at the temperature of 5 9° Fahr. In 
 the cold, it exercises scarcely any action on dry 
 air, or oxygen. But when heated strongly 
 in oxygen or chlorine, it burns with great 
 brilliancy. When thrown upon water, it 
 effervesces violently, but does not inflame, 
 swims on the surface, gradually diminishes 
 with great agitation, and renders the water 
 a solution of soda. It acts upon most 
 substances in a manner similar to potas- 
 sium, but with less energy. It tarnishes 
 in the air, but more slowly ; and, like pot- 
 assium, it is best preserved under naph- 
 tha. 
 
 Sodium forms two distinct combinations 
 with oxygen ; one is pure soda, whose hy- 
 drate is above described; the other is the 
 orange oxide of sodium, observed, like the 
 preceding oxide, first by Sir H. Davy in 
 1807, but of which the true nature was 
 pointed out in 1810, by MM. Gay Lussac 
 and Thenard. 
 
 Pure soda may be formed by burning 
 sodium in a quantity of air, containing no 
 more oxygen than is sufficient for its con- 
 version into this alkali ; i. e. the metal must 
 be in excess : a strong degree of heat must 
 be employed. 
 
 Pure soda is of a grey colour, it is a non- 
 conductor of electricity, of a vitreous frac- 
 ture, and requires a strong red-heat for its 
 fusion. When a little water is added to it, 
 there is a violent action between the two 
 bodies; the soda becomes white, crystalline 
 in its appearance, and much more fusible 
 and volatile. It is then the substance com- 
 monly called pure or caustic soda ; but pro- 
 perly styled the hydrate. 
 
 The other oxide or peroxide of sodium 
 may be formed by burning sodium in oxy- 
 gen in excess. It is of a deep orange co- 
 lour, very fusible, and a non-conductor of 
 electricity. When acted on by water, it 
 gives off oxygen, and the water becomes 
 a solution of soda. It deflagrates when 
 strongly heated with combustible bodies. 
 
 The proportions of oxygen in soda, and 
 in the orange peroxide of sodium, are easily 
 learned by the action of sodium on water 
 and on oxygen. * If a given weight of sodi- 
 um, in a little glass tube, be thrown by 
 means of the finger under a graduated in- 
 serted jar, filled with water, the quantity 
 of hydrogen evolved will indicate the quan- 
 
 tity of oxygen combined with the. metal to 
 form soda; and when sodium .is slowly 
 burned in a tray of platina, (lined with dry 
 common salt), in oxygen in great excess, 
 from the quantity of oxygen absorbed the 
 composition of the peroxide may be learned. 
 From Sir H. Davy’s experiments, compared 
 with those of MM. Gay Lussac and The- 
 nard, it appears that the prime equivalent of 
 sodium is 2.95, and that of dry soda, or 
 protoxide of sodium, 3.95 ; while the orange 
 oxide or deutoxide is 4.95. The numbers 
 given by M. Thenard are, for the first, 100 
 metal -j- 33, 995oxygen ; and for the second, 
 100 metal -f- 67.990 oxygen. 
 
 Another oxide is described containing 
 less oxygen than soda; it is therefore a sub- 
 oxide. When sodium is kept for some time 
 in a small quantity of moist air, or when 
 sodium in excess is heated with hydrate of 
 soda, a dark greyish substance is formed, 
 more inflammable than sodium, and which 
 affords hydrogen by its. action upon water. 
 
 Only one combination of sodium and 
 chlorine is known. This is the important 
 substance common salt. It may be formed 
 directly by combustion, or by decomposing 
 any compound of chlorine by sodium. Its 
 properties are well known, and are already 
 described under Acid (Muriatic). It is a 
 non-conductor of electricity, is fusible at a 
 strong red-heat, is volatile at a white-heat, 
 and crystallizes in cubes. Sodium has a 
 much stronger attraction for chlorine than 
 for oxygen ; and soda, or its hydrate, is de- 
 composed by chlorine, oxygen being expelled 
 from the first, and oxygen and water from 
 the second. 
 
 Potassium has a stronger attraction for 
 chlorine than sodium has ; and one mode of 
 procuring sodium easily, is by heating toge- 
 ther to redness, common salt and potassium. 
 This chloride of sodium, improperly called 
 the muriate, consists of 4.5 chlorine -{- 2.95 
 sodium. There is no known action between 
 sodium and hydrogen or azote. 
 
 Sodium combines readily with sulphur 
 and with phosphorus, presenting similar phe- 
 nomena to those presented by potassium. 
 The sulphurets and phosphurets of sodium 
 agree in their general properties with those 
 of potassium, except that they are rather less 
 inflammable. They form, by burning, aci- 
 dulous compounds of sulphuric and phos- 
 phoric acid and soda. 
 
 Potassium and sodium combine with great 
 facility, ami form peculiar compounds, which 
 differ in their properties, according to the 
 proportions of the constituents. By a small 
 quantity of sodium, potassium is rendered 
 fluid at common temperatures, and its sp. gr. 
 is considerably diminished. Eight parts of 
 potassium, and one of sodium, form a com- 
 pound that swims in naphtha, and that is fluid 
 at the common temperature of the air. Three 
 parts of sodium, and one of potassium, make 
 
SOI 
 
 SOI 
 
 a compound fluid at common temperatures. 
 A little potassium destroys the ductility of 
 sodium, and renders it very brittle and soft. 
 Since the prime of potassium is to that of 
 sodium, as 4.95 to 2.95; it will require the 
 former quantity of potassium, to eliminate 
 the latter quantity of sodium from the chlo- 
 ride. The attractions of potassium, for all 
 substances that have been examined, are 
 stronger than those of sodium. 
 
 Soda is the basis of common salt, of plate 
 and crown-glass, aud of all hard soaps. Ele- 
 ments of Chemical Phil* 
 
 * Sodalite. Colour green. Massive 
 and crystallized in rhomboidal dodecahe- 
 drons. Shining. Cleavage double. Frac- 
 ture small conchoidal. Translucent. As 
 hard as felspar. Brittle. Sp. gr. 2.578. 
 It is infusible; becoming only dark grey 
 before the blow-pipe. Its constituents are, 
 silica 58.5 or 36, alumina 27.48 or 52, lime 
 2.7 or 0, oxide of iron 1 or 0.25, soda 25.5 
 or 25, muriatic acid 5 or 6.75; volatile 
 matter 2. 1 0 or 0, loss 1.7 or 0 . — Thomson 
 and Ekeberg . It was discovered in West 
 Greenland by Sir Charles Gieseke, in a bed 
 in mica slate.* 
 
 * Sodium. See Soda.* 
 
 Soil. The soil or earth in which vege- 
 tables grow, varies considerably in its com- 
 position, or in the proportions of the dif- 
 ferent earths of which it consists ; and some 
 plants are found to thrive best in one kind 
 of soil, others in another. Under Analysis 
 the methods of analyzing soils, so as to as- 
 certain their composition, will be found, as 
 given by Sir H. Davy; and we shall here 
 subjoin the rules he has laid down for their 
 improvement, as connected with the princi- 
 ples of which they consist. 
 
 In cases where a barren soil is examined 
 with a view to its improvement, it ought in 
 all cases, if possible, to be compared with an 
 extremely fertile soil in the same neighbour- 
 hood, and in a similar situation : the differ- 
 ence given by their analyses would indicate 
 the methods of cultivation, and thus the plan 
 of improvement would be founded upon ac- 
 curate scientific principles. 
 
 If the fertile soil contained a large quan- 
 tity of sand, in proportion to the barren soil, 
 the process of melioration would depend 
 simply upon a supply of this substance ; 
 and the method would be equally simple 
 witli regard to soils deficient in clay or cal- 
 careous matter. 
 
 In the application of clay, sand, loam, 
 marie, or chalk to lands, there are no parti- 
 cular chemical principles to be observed ; but 
 when quicklime is used, great care must be 
 taken, that it is not obtained from the mag- 
 nesian limestone ; for in this case, as has 
 been shown by Mr Tennant, it is exceed- 
 ingly injurious to land. The magnesian 
 limestone may be distinguished from the 
 
 47 
 
 common limestone by its greater hardness, 
 and by the length of time that it requires for 
 its solution in acids; and it may be analyzed 
 by the process for carbonate of lime and 
 magnesia. 
 
 When the analytical comparison indicates 
 an excess of vegetable matter as the cause 
 of sterility, it may be destroyed by much pul- 
 verization and exposure to air, by paring 
 and burning, or the agency of lately made 
 quicklime. And the defect of animal and 
 vegetable matter must be supplied by ani- 
 mal or vegetable manure. 
 
 The general indications of fertility and 
 barrenness, as found by chemical experi- 
 ments, must necessarily differ in different 
 climates, and under different circumstances. 
 The power of soils to absorb moisture, a 
 principle essential to their productiveness, 
 ought to be much greater in warm and dry 
 countries, than in cold and moist ones ; and 
 the quantity of fine aluminous earth they 
 contain should be larger. Soils likewise 
 that are situate on declivities ought to be 
 more absorbent than those in the same cli- 
 mate on plains or in valleys. 
 
 The productiveness of soils must likewise 
 be influenced by the nature of the sub-soil, or 
 the earthy or stony strata on which they 
 rest ; and this circumstance ought to be par- 
 ticularly attended to, in considering their 
 chemical nature, and the system of improve- 
 ment. Thus a sandy soil may owe its fer- 
 tility to the power of the sub-soil to retain 
 water ; and an absorbent clayey soil may 
 occasionally be prevented from being barren, 
 in a moist climate, by the influence of a sub- 
 stratum of sand or gravel. 
 
 Those soils that are most productive of 
 corn, contain always certain proportions of 
 aluminous or calcareous earth in a finely di- 
 vided state, and a certain quantity of vege- 
 table or animal matter. 
 
 The quantity of calcareous earth is how- 
 ever very various, and in some cases exceed- 
 ingly small. A very fertile corn soil from 
 Ormiston in East Lothian afforded in a hun- 
 dred parts only eleven parts of mild calca- 
 reous earth ; the finely divided clay amount- 
 ed to forty-five parts* It lost nine in decom- 
 posed animal and vegetable matter, and four 
 in water, and exhibited indications of a small 
 quantity of phosphate of lime. 
 
 This soil was of a very fine texture, and 
 contained very few stones or vegetable fibres. 
 It is not unlikely, that its fertility was in 
 some measure connected with the phos- 
 phate; for this substance is found in wheat, 
 oats, and barley, and may be a part of their 
 food. 
 
 A soil from the low lands of Somerset- 
 shire, celebrated for producing excellent crops 
 of wheat and beans without manure, I found 
 to consist of one-ninth of sand, chiefly sili- 
 ceous, and eight- ninths of calcareous marie 
 
SOL 
 
 SOR 
 
 tinged with iron, and containing about five 
 parts in the hundred of vegetable matter. I 
 could not detect in it any phosphate or sul- 
 phate of lime, so that its fertility must have 
 depended principally upon its power of at- 
 tracting principles of vegetable nourishment 
 from water and the atmosphere. 
 
 Mr Tillet, in some experiments made on 
 the composition of soils at Paris, found, that 
 a soil composed of three-eighths of clay, two- 
 eighths of river sand, and three-eighths of 
 the parings of limestone, was very proper 
 for wheat. 
 
 In general, bulbous roots require a soil 
 much more sandy, and less absorbent, than 
 the grasses. A very good potato soil, from 
 Varsel in Cornwall, afforded seven-eighths 
 of siliceous sand ; and its absorbent power 
 was so small, that 100 parts lost only 2 by 
 drying at 400° Fahrenheit. 
 
 Plants and trees, the roots of which are 
 fibrous and hard, and capable of penetrating 
 deep into the earth, will vegetate to advan- 
 tage in almost all common soils that are 
 moderately dry, and do not contain a very 
 great excess of vegetable matter. 
 
 The soil taken from a field at Sheffield- 
 place in Sussex, remarkable for producing 
 flourishing oaks, was found to consist of 6 
 parts of sand, and 1 part of clay and finely 
 divided matter. And 100 parts of the entire 
 soil submitted to analysis, produced water 3, 
 silex 54, alumina 28, carbonate of lime 3, 
 oxide of iron 5, decomposing vegetable mat- 
 ter 4, loss 3. 
 
 From the great difference of the causes 
 that influence the productiveness of lands, it 
 is obvious, that, in the present state of 
 science, no certain system can be devised for 
 their improvement, independent of experi- 
 ment ; but there are few cases, in which the 
 labour of analytical trials will not be amply 
 repaid by the certainty with which they de- 
 note the best methods of melioration ; and 
 this will particularly happen, when the de- 
 fect of composition is found in the propor- 
 tions of the primitive earths. 
 
 In supplying animal or vegetable manure, 
 a temporary food only is provided for plants, 
 which is in all cases exhausted by means of 
 a certain number of crops ; but when a soil 
 is rendered of the best possible constitution 
 and texture with regard to its earthy parts, 
 its fertility may be considered as permanent- 
 ly established. It becomes capable of at- 
 tracting a very large portion of vegetable 
 nourishment from the atmosphere, and of 
 producing its crops with comparatively little 
 labour and expense. 
 
 Solders, and Soldering. Solders consist 
 merely of simple or mixed metals, by which 
 alone metallic bodies can be (irmly united 
 with each other. In this respect it is a gene- 
 ral rule, that the solder should always be 
 easier of fusion than the metal intended to 
 
 be soldered by it; next to this, care must also 
 be taken, that the solder be as far as is pos- 
 sible of the same colour with the metal that 
 is to be soldered. 
 
 For the simple solders, each of the metals 
 may be used according to the nature of that 
 which is to be soldered. For fine steel, cop- 
 per, and brass work, gold and silver may be 
 employed. In the large way, however, iron 
 is soldered with copper, and copper and brass 
 with tin. 
 
 'i he most usual solders are the compound, 
 which are distinguished into two principal 
 classes, viz. hard and soft solders. The hard 
 solders are ductile, will bear hammering, 
 and are commonly prepared of the same 
 metal with that which is to be soldered, 
 with the addition of some other, by which 
 a greater degree of fusibility is obtained, 
 though the addition is not always required 
 to be itself easier of fusion. Under this 
 head comes the hard solder for gold, which 
 is prepared from gold and silver, or gold and 
 copper, or gold, silver, and copper. The 
 hard solder for silver is prepared from equal 
 parts of silver and brass, but made easier of 
 fusion by the admixture of a sixteentli part 
 of zinc. The hard solder for brass is ob- 
 tained from brass mixed with a sixth, or an 
 eighth, or even one-half of zinc, which may 
 also be used for the hard solder of copper. 
 It is sold in the shops in a granulated form, 
 under the name of spelter-solder. 
 
 The soft solders melt easily, but are part- 
 ly brittle, and therefore cannot be hammer- 
 ed. Of this kind are the following mixtures : 
 tin and lead in equal parts ; of still easier 
 fusion is that consisting of bismuth, tin, and 
 lead, equal parts ; l or 2 parts of bismuth 
 of tin and lead each 1 part. 
 
 In the operation of soldering, the surfaces 
 of the metal intended to be joined must be 
 made very clean, and applied to each other. 
 It is usual to secure them by a ligature of 
 iron wire, or other similar contrivance. The 
 solder is laid upon the joint, together with 
 sal ammoniac or borax, or common glass, 
 according to the degree of heat intended. 
 These additions defend the metal from oxi- 
 dation. Glaziers use resin ; and pitch is 
 sometimes employed. 
 
 Tin-foil applied between the joints of fine 
 brass work, first wetted with a strong solu- 
 tion of sal ammoniac, makes an excellent 
 junctuie, caie being taken to avoid too much 
 heat. 
 
 * Solids and Solidity. See Caloric, 
 and Crystallization.* 
 
 Solution. See Salt, Crystallization, 
 and Attraction. 
 
 * SOMMITE. NepIIELINE.* 
 
 Sorbates. Compounds of sorbic, or 
 malic acid, with the salifiable bases. See 
 Acid (Sorbic). * 
 
SPE 
 
 * Sory. The ancient name of sulphate 
 of iron.* 
 
 * Spar (Fluor). See Fluor.* 
 
 * Spar (Ponderous). See Heavy- spar.* 
 
 * Sparry Anhydrite, or Cube-spar, a 
 sub-species of prismatic gypsum. Colour 
 white, passing into blue or red. Massive, 
 in distinct concretions, and crystallized. 
 The primitive figure is an oblique prism, in 
 which the angles are 108° 8' and 79° 56'. 
 The secondary forms are, a rectangular four- 
 sided prism, a broad six-sided prism, an 
 eight-sided prism, and a broad rectangular 
 four-sided prism, acuminated. Splendent, 
 pearly. Cleavage threefold. Fragments 
 cubical. Fracture conchoidal. Transpa- 
 rent. Refracts double. Scratches calca- 
 reous spar, but not fluor. Brittle. Sp. 
 gr. 2.7 to 3.0. It does not exfoliate before 
 the blow-pipe, and melt like gypsum, but 
 becomes glazed over with a white friable 
 enamel. Its constituents are, lime 41.75, 
 sulphuric acid 55, muriate of soda 1. — Klap- 
 roth. It is sometimes met with in the gyp- 
 sum' of Nottinghamshire. It occurs in the 
 salt mines of Halle, &c. * 
 
 * Sparry Iron. Carbonate of iron. 
 Colour pale yellowish-grey. Massive, dis- 
 seminated, and crystallized. The primitive 
 form is a rhomboid of 107°. The following 
 are some of the secondary forms. The 
 primitive, perfect, or truncated ; a still flat- 
 ter rhomboid ; the spherical lenticular form ; 
 the saddle shaped lens, and the equiangular 
 six-sided prism. Glistening or splendent, 
 or pearly. Cleavage threefold. Fracture 
 foliated, or splintery. Translucent on the 
 edges. Streak white or yellowish-brown. 
 Harder than calcareous spar. Easily fran- 
 gible. Sp. gr. 3.6 to S. 9. It blackens and 
 becomes magnetic before the blow-pipe, but 
 does not melt ; it effervesces with muriatic 
 acid. Its constituents are, oxide of iron 
 
 57.5, carbonic acid 36, oxide of manganese 
 
 3.5, lime 1.25. — Klaproth. It occurs in 
 veins in granite, gneiss, &c. associated with 
 ores of lead, cobalt, silver, copper, &c. But 
 the most extensive formations of this mine- 
 ral are in limestone. It is found in small 
 quantities in England, Scotland, and Ire- 
 land ; in Saxony, Bohemia, See. ; and In large 
 quantities in Fichtelgebirge ; and at Schmal- 
 kalden in Hessia. It affords an iron well 
 suited for conversion into steel. — Jameson.* 
 
 * Specific Gravity. The density of the 
 matter of which any body is composed, com- 
 pared to the density of another body, assum- 
 ed as the standard.. This standard is pure 
 distilled water, at the temperature of 60° 
 F. To determine the specific gravity of a 
 solid, we weigh it, first m air, and then in 
 waiter. In the latter case it loses, of its 
 weight, a quantity precisely equal to the 
 weight of its own bulk of water ; and hence, 
 h Y comparing this weight with its total 
 
 weight, wo find its specific gravity. The 
 rule therefore is, divide the total weight, by 
 the loss of weight in water, the quotient is 
 the specific gravity. If it be a liquid or a 
 gas, we weigh it in a glass or other vessel of 
 known capacity ; and dividing that weight, 
 by the weight of the same bulk of water, the 
 quotient is, as before, the specific gravity. 
 See Hydrometer, for another modification 
 of the same rule. 
 
 To calculate the mean specific gravity of 
 a compound from those of its components, is 
 a problem of perpetual recurrence in che- 
 mistry. It rs only by a comparison of the 
 result of that calculation, with the specific 
 gravity of the compound experimentally 
 ascertained, that we can discover whether 
 the combination has been accompanied with 
 expansion or condensation of volume. As 
 several respectable experimental chemists 
 (see Alloy and Ammonia) seem deficient 
 in the knowledge of chemical computation, 
 I shall here insert a short abstract of a paper 
 which I published on this subject in the 7th 
 number of the Journal of Science. 
 
 “ The specific gravity of one body is to that 
 of another, as the weight of the first, divided 
 by its volume, is to the weight of the second, 
 divided by its volume ; and the mean speci- 
 fic gravity of the two, is found, by dividing 
 the sum of the weights by the sum of the 
 volumes. 
 
 Let W, w, he the two weights ; V, v , the 
 two volumes; P, p, the two specific gravities ; 
 and M, the calculated mean specific gravity. 
 Then 
 
 W 4- w 
 
 M = . the formula by which I 
 
 V -|- v 
 
 computed the second column of Table II. 
 
 W w W p 4- ieP 
 
 And V -j- v = = ^ 
 
 ‘ P ‘ p Vp 
 
 Hence 
 
 W -f w _ W _ (W + w)P P__ M 
 
 V — |— v W p -}- icP Pw 
 
 When the difference in density, between 
 
 the two substances is considerable, as it is 
 
 with sulphuric acid and w-ater, the errors 
 
 produced by assuming the arithmetical mean, 
 
 for the true calculated mean, are excessive. 
 
 If we take copper and tin, however, then the 
 
 . , • , 8.89 -f- 7.29 o n q 
 
 arithmetical mean, = = 8.U9, 
 
 differs very little from 8.01, the accurate 
 mean density. 
 
 By a similar error, I suppose, in calculat- 
 ing the mean density of liquid muriatic acid 
 in its different stages of dilution, the cele- 
 brated Kir wan has long misled the chemical 
 world. He asserted, that the mean specific 
 gravity of the components, being also the 
 experimental mean, there is no condensation 
 of volume, as with other acid dilutions. And 
 the illustrious Berthollet has even assigned 
 
SPE 
 
 SPI 
 
 a cause for this suppositious fact I find, on 
 the contrary, that 50 of acid, sp. gr. 1.1920 
 with 50 of water, give out heat, and have 
 their volume diminished in the ratio of 1 00 
 to 99.28. The experimental specific gravity 
 is 1.0954 ; that, by the exact rule, is only 
 1.0875. 
 
 The preceding formula may be presented, 
 under a still more convenient form. P, p 
 being the specific gravities of the two com- 
 
 W w 
 
 ponents, we have P = — and p = — . 
 
 V v 9 
 
 whence V = v = — • 
 
 P> p 
 
 In the condition when W s=s iv = 1, we 
 have then 
 
 V = JL, v = — , and, consequently, 
 P p 
 
 therefore 
 
 1 I 
 
 2A = (P— p)X 
 
 ( P— ;>)* 
 
 P+i> 
 
 (P— P)(P-P) 
 P+P 
 
 This value being constantly negative, 
 proves that the true value of the specific gra- 
 vity of the mixture, represented by 
 
 V v 
 
 is always smaller than the false value, 
 I / W w \ 
 
 T\T + V/- 
 
 Example of the last formula, 
 
 Gold and silver, 14.9 — 
 
 2 
 
 false or arithmetical mean specific gravity. 
 (P— ( 1 9. 3 — 10.5) 2 (8.8) 2 77.44 
 
 P+;> 29.8 29.8 29.8 
 
 = 2.6 = 2 A; and A = 1*3, which being 
 subtracted from the arithmetical mean 14.9, 
 leaves 1 3.6 for the true mean sp. gr. as direct- 
 ly obtained by the formula 
 3 P w + ;AV 
 
 Sulphuric Acid Table, shewing the erroneous results of the 
 common method . See Alloy. 
 
 Acid in 
 100. 
 
 Arithm. 
 
 mean 
 
 density. 
 
 Experi- 
 
 mental 
 
 density. 
 
 Apparent 
 
 volume. 
 
 Acid in 
 100. 
 
 Arithm. 
 
 mean 
 
 density. 
 
 Experi- 
 
 mental 
 
 density. 
 
 Apparent 
 
 volume. 
 
 100 
 
 
 1.8480 
 
 100 
 
 50 
 
 1.4240 
 
 1.3884 
 
 102.6 
 
 90 
 
 1.7632 
 
 1.8115 
 
 97.3 
 
 40 
 
 1.3592 
 
 1.2999 
 
 103.02 
 
 80 
 
 1.6784 
 
 1.7120 
 
 98.0 
 
 30 
 
 1.2544 
 
 1.2184 
 
 102.95 
 
 70 
 
 1.5936 
 
 1.5975 
 
 99.7 
 
 20 
 
 1.1696 
 
 1.1410 
 
 102.50 
 
 60 
 
 1.5088 
 
 1.4860 
 
 101.5 
 
 10 
 
 1.0848 
 
 1.0680 
 
 101.57 
 
 * Specular. Iron Ore. See Ores or 
 Iron.* 
 
 Speculum. Mr Edwards affirms, that dif- 
 ferent kinds of copper require different doses 
 of tin to produce the most perfect whiteness. 
 If the dose of tin be too small, which is the 
 fault most easily remedied, the composition 
 will be yellowish ; if it be too great, the 
 composition will be of a grey-blue colour, 
 and dull appearance. He casts the specu- 
 lum in sand, with the face downwards ; 
 takes it out while red-hot, and places it in 
 hot wood ashes to cool ; without which pre- 
 caution it would break in cooling. 
 
 Mr Little recommends the following pro- 
 portions: — 32 parts of the best bar copper, 
 4 parts of the brass of pin- wire, 16^ of tin, 
 and Ij of arsenic. Silver he rejects, as it 
 has an extraordinary effect of softening the 
 metal ; and he found, that the compound 
 was not susceptible of the highest polish, 
 unless it was extremely brittle. He first 
 melts the brass, and adds to it about an equal 
 
 weight of tin. When this mixture is cold, 
 he puts it into the copper, previously fused 
 with black flux, adds next the remainder of 
 the tin, and lastly the arsenic. This mixture 
 he granulates, by pouring into cold water, as 
 Mr Edwards did, and fuses it a second time 
 for casting. 
 
 * Spermaceti. See Fat.* 
 
 * Sphene. Prismatic titanium ore.* 
 
 * Sphcerulite. Colours brown and grey. 
 In imbedded roundish balls and grains. 
 Glimmering. Fracture even, splintery. 
 Opaque. Scratches quartz with difficulty. 
 Brittle. Sp. gr. 2.4 to 2.5. Nearly in- 
 fusible. It occurs in pearlstone and pitch- 
 stone porphyries, in the vicinity of Glass- 
 hiitte near Schemnitz ; and in the pitchstone 
 of Meissen.* 
 
 * Sphragide. See Lemnian EapvTH.* 
 
 * SriNEL. A sub-species of octohedral 
 corundum. Colour red. Occurs in grains, 
 more frequently crystallized ; in a perfect 
 octohedron, which is the fundamental figure; 
 
 O 9 
 
S PI 
 
 SPI 
 
 in a tetrahedron, perfect or modified ; a thick 
 equiangular six-sided table; a very oblique 
 four-sided table ; a rhomboidal dodecahe- 
 dron ; a rectangular four-sided prism. Splen- 
 dent and vitreous. Cleavage fourfold, f rac- 
 ture flat conchoidal. Translucent to trans- 
 parent. Refracts single. Scratches topaz, 
 but is scratched by sapphire. Brittle. Sp. 
 gr. 3.5 to 3.8. Fusible with borax. Its 
 constituents are, alumina 82.47, magnesia 
 8.78, chromic acid 6.18, loss 2.57. — Vau- 
 (juelin. It is found in the gneiss district of 
 Acker in Sudermannland, in a primitive 
 limestone: in the kingdom of Pegu, and in 
 Ceyion. It is used as a precious Stone. 
 When it weighs four carats (about 1 6 grains), 
 it is considered of equal value with a diamond 
 of half the weight . — Jameson * 
 
 * Spinellane. Colour plum-blue. It 
 occurs crystallized in rhomboids of 117° 23', 
 and 62° 57' : and in six-sided prisms, acu- 
 minated with three planes. It scratches glass. 
 It is found on the shores of the lake of 
 Laach, in a rock composed of glassy felspar, 
 quartz, hornblende, &c. It is said to be a 
 variety of Haiiyne. * 
 
 * SriNTHERE. Colour greenish-grey. In 
 small oblique double four-sided pyramids. 
 It does not scratch glass. It occurs in the 
 department of Isere in France, incrusting 
 calcareous spar crystals. It is believed to be 
 a variety of sphene.* 
 
 Spirit or Mindererus. A solution of 
 acetate of ammonia, made by adding con- 
 crete carbonate of ammonia to distilled vine- 
 gar till saturation takes place. 
 
 Spirit of Nitre. See Acid (Nitric). 
 
 * Spirit, (Pvro- acetic). Some dry ace- 
 tates exposed to heat in a retort yield a 
 quantity of a light volatile spirit, to which 
 the above name is given. When the acetate 
 is easily decomposed by the fire, it affords 
 much acid and little spirit; and on the con- 
 trary it yields much spirit and little acid, 
 when a strong heat is required for its decom- 
 position. The acetates of nickel, copper, 
 Sec. are in the first condition ; those of ba- 
 rytes, potash, soda, strontian, lime, man- 
 ganese, and zinc, are in the second. The 
 following table of M. Chenevix, exhibits the 
 products of the distillation of various ace- 
 tates. 
 
 Table af‘ Pyro- Acetic Spirit. 
 
 
 
 Acetate of 
 
 Acetate of 
 
 Acetate of 
 
 Acetate of 
 
 Peracetate 
 
 Acetate of 
 
 A cetate of 
 
 
 
 Silver. 
 
 Nickel. 
 
 Copper. 
 
 Lead. 
 
 of iron. 
 
 Zinc. 
 
 Manganese. 
 
 Loss by the fire, 
 
 0.36 
 
 0.61 
 
 0.64 
 
 0.37 
 
 0.49 
 
 
 0.555 
 
 g f State of the 
 2 \ base (a). 
 
 A 
 
 metallic. 
 
 metallic. 
 
 metallic. 
 
 metallic. 
 
 bl. oxide. 
 
 wh. oxide. 
 
 hr. oxide. 
 
 tn j 
 
 p-ij ( __ Resid. Carbon. 
 
 0.05 
 
 0.14 
 
 0.055 
 
 0.04 
 
 0.02 
 
 0.05 
 
 0.035 
 
 - ™ 
 *5 ti 
 
 f Sp.gr. 
 
 1.0 656 
 
 1.0398 
 
 1.0556 
 
 0.9407 
 
 1.011 
 
 0.8452 
 
 0.8264 
 
 0*5 ^ Rati oof acid. 
 
 107.303 
 
 44.731 
 
 84.86S 
 
 3.045 
 
 27.286 
 
 2.258 
 
 1 . 285 
 
 *3 o 
 
 ^Pyro. spir. 
 
 0 
 
 almost 0 
 
 0.17 
 
 0.555 
 
 0.24 
 
 0.695 
 
 0.94 
 
 i5 i2 
 
 '”Carb.acid.(6) 
 
 8 
 
 03 
 
 10 
 
 20 
 
 1 3 
 
 16 
 
 20 
 
 O 3 
 
 < 
 
 Carb. hydro. 
 
 12 
 
 60 
 
 34 
 
 8 
 
 34 
 
 28 
 
 32 
 
 ee O 
 
 o & 
 
 Total gas. 
 
 20 
 
 95 
 
 44 
 
 28 
 
 52 
 
 44 
 
 52 
 
 / 
 
 We sec, that of all the acetates, that of 
 silver gives the most concentrated and purest 
 acetic acid, since it contains no pyro-acetie 
 spirit. 
 
 This spirit is limpid and colourless. Its 
 taste is at first acrid and burning, then cool- 
 ing, and in some measure urinous. Its 
 odour approaches that of peppermint mingled 
 with hitter almonds. Its sp. gr. is 0.7864. 
 It burns with a flame interiorly blue, but 
 
 (a) Almost all the metallic residuums are pyropho- 
 ric, or susceptible of inflaming by contact of air, after 
 complete refrigeration ; which M. Chenevix ascribes 
 to the finely divided charcoal mixed with the metallic 
 
 part. . 
 
 (b) The quantities marked here, are expressed in 
 
 volumes. 
 
 white on the outside. It boils at 138.2 F. 
 and dees not congeal at 5° F. With water 
 it combines in every proportion, as well as 
 with alcohol, and most of the essential oils. 
 It dissolves but a little of sulphur and phos- 
 phorus, hut camphor in very large quantity. 
 
 Caustic potash has very little action on 
 the pyro-acetic spirit. Sulphuric and nitric 
 acids decompose it; but muriatic acid forms 
 with this body a compound, which is not 
 acid, and in which wc can demonstrate the 
 presence of the muriatic acid, only by igneous 
 decomposition. Hence we perceive that pyro- 
 acetic spirit is a peculiar substance, which 
 resembles the ethers alcohol, and volatile 
 oils. To obtain it cheaply, wc may employ 
 
STA 
 
 STA 
 
 the acetate of lead of commerce. After 
 having distilled this salt in an earthen retort, 
 and collected the liquid products in a globe, 
 communicating by a tube with a flask sur- 
 rounded with ice, we saturate these products 
 with a solution of potash or soda, and then 
 separate the spirit by means of a second dis- 
 tillation, taking care to use a regulated heat. 
 As it usually carries over with it a little wa- 
 ter, it is proper to rectify it from dry muri- 
 ate of lime. Ann. de Chimie , tom. 69.* 
 
 * SruiiT of Sal Ammoniac. Water of 
 Ammonia.* 
 
 S vi u it (Volatile) of Sal Ammoniac. 
 See Ammonia. 
 
 * Spirit of Salt. See Acid (Muriatic).* 
 
 * Spirit of Wine. Alcohol.* 
 
 * Spodumene. Prismatic triphane spar. — 
 Mohs. Colour between greenish- white and 
 mountain-grey. Massive, disseminated and 
 in large granular concretions. Glistening, 
 pearly. Cleavage, threefold. Fracture fine 
 grained uneven. Translucent. As hard as 
 felspar. Most easily frangible. Sp. gr. 3.0 
 to 3.1. Before the blow- pipe, it first sepa- 
 rates into small gold-yellow coloured folia; 
 and if the heat is continued, they melt into 
 a greenish-white coloured glass. Its consti- 
 tuents are, silica 64.4, alumina 24.4, lime 5, 
 potash 5, oxide of iron 2.2. — Vauquelin. 
 It was first discovered in the Island of Uton 
 in Sudermannland, where it is associated 
 with red felspar and quartz. It has been 
 lately found in the vicinity of Dublin, by Dr 
 Taylor. It contains the new alkali lithia , by 
 some recent analyses.* 
 
 Sponge. A soft, light, very porous, and 
 compressible substance, readily imbibing wa- 
 ter, and distending thereby. It is found ad- 
 hering to rocks, particularly in the Mediter- 
 ranean Sea, about the islands of the Archi- 
 pelago. It was formerly supposed to be a 
 vegetable production, but is now classed 
 among the zoophytes; and analyzed, it yields 
 the same principles with animal substances in 
 general. 
 
 Stalactites. These are found suspended 
 from vaults, being formed by the oozing of 
 water charged with calcareous particles, and 
 gradually evaporating, leaving those particles 
 behind. 
 
 Starch. This is a white, insipid, com- 
 bustible substance, insoluble in cold water, 
 but forming a jelly with boiling water. It 
 exists chiefly in the white and brittle parts 
 of vegetables, particularly in tuberose roots, 
 and the seeds of the gramineous plants. It 
 may be extracted by pounding these parts, 
 and agitating them in cold water; when the 
 parenchyma, or fibrous parts, will first sub- 
 side ; and these being removed, a fine, white 
 powder, diffused through the water, will 
 gradually subside, which is the starch. Or 
 the pounded or grated substance, as the 
 roots of arum, potatoes, acorns, or horse- 
 
 clicsnuts, for instance, may be put into a 
 hair-sieve, and the starch washed through 
 with cold water, leaving the grosser matters 
 behind. Farinaceous seeds may be ground 
 and treated in a similar manner. Oily seeds 
 require to have the oil expressed from them 
 before the farina is extracted. 
 
 If starch be subjected to distillation, it 
 gives out water impregnated with empy- 
 reumatic acetous acid, a little red or brown 
 oil, a great deal of carbonic acid, and car- 
 buretted hydrogen gas. Its coal is bulky, 
 easily burned, and leaves a very small quan- 
 tity of potash and phosphate of lime. If 
 when diffused in water it be exposed to a 
 heat of 60° F., or upward, it will ferment, 
 and turn sour ; but much more so if it be 
 not freed from the gluten, extract, and co- 
 louring matter. Thus, in starch-making 
 the farina ferments and becomes sour, but 
 the starch that does not undergo fermenta- 
 tion is rendered the more pure by this pro- 
 cess. Some water already soured is mixed 
 with the flour and water, which regulates 
 the fermentation, and prevents the mixture 
 from becoming putrid ; and in this state it 
 is left about ten days in summer and fifteen 
 in winter, before the scum is removed, and 
 the water poured off. The starch is then 
 washed out from the bran, and dried, first 
 in the open air, and finally in an oven. 
 
 With boiling water starch forms a nearly 
 transparent mucilage, emitting a peculiar 
 smell, neither disagreeable nor very power- 
 ful. This mucilage may be dried, and will 
 then be semi-transparent, and much resem- 
 bling gum, all the products of which it af- 
 fords. When dissolved it is much more 
 easily digested and nutritious than before it 
 lias undergone this operation. 
 
 Both acids and alkalis combined with wa- 
 ter dissolve it. It separates the oxides of se- 
 veral metals from their solutions, and takes 
 oxygen from many of them. It is found 
 naturally combined with all the immediate 
 principles of vegetables, and may easily be 
 united with most of them by art. 
 
 * Staurolitk. Grenatite, or prismatic 
 garnet. * 
 
 * Staurotide. Grenatite, prismatic gar- 
 net, or staurolite. Colour dark reddish- 
 brown. Only crystallized in forms which 
 may be reduced to a prism of I 29° 30'. The 
 following are secondary forms ; a very oblique 
 four-sided prism, truncated on the acuter 
 
 juiuidi euges, lorming an unequianguiar six- 
 sided prism ; the same acutely bevelled on 
 the extremities; and a twin crystal, formed 
 by two perfect six-sided prisms. Splendent, 
 resino- vitreous. Cleavage, in the smaller 
 diagonal. Fracture, small grained uneven. 
 Opaque, or translucent. Scratches quartz 
 feebly. Brittle. Sp. gr. 3.3 to 3.8. In- 
 fusible. Its constituents are, alumina 44, 
 silica lime 3.84, oxide ol iron 13, oxide 
 
STE 
 
 STE 
 
 of manganese 1, loss 5.16. — Vauquelin. 
 The geognostic relations of this mineral are 
 nearly the same with those of precious gar- 
 net. It occurs in cl ay- si ate near Arc! on aid, 
 between Keith and Huntly, in Aberdeen, 
 shire ; and in a micaceous rock at the Glen- 
 malur lead-mines in the county of Wicklow, 
 Ireland.* 
 
 * Steam. See Caloric, and Vapour.* 
 
 * Stearine. See Fat.* 
 
 * Steatite, or Soapstone. A sub-species 
 of rhomboidal mica. Colour greyish, or 
 greenish- white. Massive, disseminated, imi- 
 tative, and in the following supposititious 
 figures : an equiangular six-sided prism ; an 
 acute double six-sided pyramid ; and a rhom- 
 boid. The first two are on rock crystal, the 
 last on calcareous spar. Dull. Fracture 
 Coarse splintery. Translucent on the edges. 
 Streak shining. Writes but feebly. Soft. 
 Very sectile. Rather difficultly frangible. 
 Does not adhere to the tongue. Feels very 
 greasy. Sp. gr. 2.4 to 2.6. Infusible. Its 
 constituents are, silica 44, magnesia 44, alu- 
 mina 2, iron 7.3, manganese 1.5, chrome 2. 
 Trace of lime and muriatic acid. It occurs 
 frequently in small contemporaneous veins, 
 that traverse serpentine, in all directions ; at 
 Portsoy and Shetland ; in the limestone of 
 Icolmkill ; in the serpentine of Cornwall; 
 and in Anglesey. It is used in the manu- 
 facture of porcelain, and for taking greasy 
 spots out of silk and woollen stuffs. It is 
 also employed in polishing gypsum, serpen- 
 tine, and marble. When pounded and 
 slightly burned, it forms the basis of certain 
 cosmetics. It writes readily on glass. Hum- 
 boldt assures us, that the Otomacks, a savage 
 race on the banks of the Orinoco, live for 
 nearly three months of the year, principally 
 on a kind of potters’ clay ; and many other 
 savages eat great quantities of steatite, which 
 contains absolutely no nourishment.* 
 
 * Steel. A modification of iron, con- 
 cerning which our knowledge is not very 
 precise, notwithstanding the researches of 
 many celebrated chemists. For the follow- 
 ing important facts, I am indebted to the 
 proprietor of the Monkland Manufactory, 
 where bar and cast steel of superior quality 
 are made. 
 
 The chests or troughs, in which the iron 
 bars are stratified, are 9 feet long, and com- 
 posed of an open-grained siliceous freestone, 
 unalterable by the fire. The Dannemora or 
 Oregrounds iron is alone employed, for con- 
 version into steel, at Monkland. The in- 
 crease of weight is from 4 to 1 2 ounces per 
 hundred weight. The average is therefore 
 ] in 224 parts. The first proportion con- 
 stitutes mild, and the second very hard steel. 
 Should the process be pushed much farther, 
 the steel would then melt, and in the act of 
 fusion would take a dose of charcoal, suffi- 
 cient to bring it to the state of No. 1 . cast 
 
 iron, i he charcoal used in stratifying with 
 the bar iron, is bruised so as to pass through 
 a quarter-inch riddle. Whenever the inte- 
 rior of the troughs arrives at 70° Wedgwood, 
 the carbon begins to be absorbed by the iron. 
 There is no further diminution of the weight 
 of the charcoal, than what is due to this 
 combination. What remains is employed at 
 another charge. Great differences are found 
 between the different kinds of bar iron, im- 
 ported at the same time ; which occasion 
 unexpected differences in the resulting steel. 
 The following letter contains important in- 
 formation, from a gentleman possessing great 
 experience in the manufacture of steel. 
 
 “ Monkland Steel- Works., 
 
 “ 9th November 1820. 
 
 “ Sir, — M r William Murray has written 
 me, that you wished I should communicate 
 to you the reason why bar iron should run 
 into the state of soft cast iron, by the opera- 
 tion being carried too far in the blister steel 
 furnace, and how it does not make cast steel, as 
 cast steel is said to be formed by the fusion of 
 the blister steel in the crucible with charcoal. 
 
 “ The usual practice of making cast steel, is 
 to fuse common steel in a crucible, without 
 any charcoal being mixed. The degree of 
 hardness required in the cast steel is regulat- 
 ed by selecting blister steel of the proper de- 
 gree of hardness for what is wanted. 
 
 “ This statement is made with the view* to 
 correct a common mistake, that to make cast 
 steel it is necessary, and that it is the prac- 
 tice, to mix with the steel to be melted a 
 quantity of charcoal. 
 
 “ Pursuing this mistake, it naturally leads 
 to others. Dr Thomson says, when speak- 
 ing on this subject, that cast steel is more 
 fusible than common steel, and for that rea- 
 son it cannot be welded to iron. It mehs 
 before it can be heated high enough ; and 
 that the quantity of carbon is greater than in 
 common steel ; and that this seems to consti- 
 tute the difference between the two sub- 
 stances. 
 
 “ The statement of a simple fact will shew, 
 that this conclusion is erroneous. Suppose 
 a piece of blister steel, pretty hard, yet fit to 
 stand the operation of welding to iron w ith- 
 out any difficulty ; let this steel be made into 
 cast steel in the ordinary wav. It will not 
 then stand the process of welding. It will 
 not melt before reaching the welding heat ; 
 but when brought to that heat, and submit- 
 ted to the blows of the hammer, it wall fall 
 like a piece of sand, and the parts being once 
 separated, they refuse to become again unit- 
 ed. This difficulty of working the steel can- 
 not arise from the steel containing more car- 
 bon, for the fact is, it contains less, part of it 
 being burnt out in the operation of melting 
 it. And if the same steel was to be melted 
 a second time, more of the carbon would be 
 
STI 
 
 ST K 
 
 burnt out, of course the steel would be 
 softer, but at the same time, the difficulty of 
 working it would be increased ; or, in other 
 words, the red-short property it had acquir- 
 ed in the first melting would be doubly in- 
 creased in the second, although a person who 
 has not had the experience would very na- 
 turally conclude, that as the metal kept re- 
 trograding to the state of malleable iron, in 
 the same proportion it would acquire all the 
 properties of the metal in that state. When 
 taking this view of the subject, it would ap- 
 pear that the difference between these two 
 kinds of steel must arise from some other 
 cause than that pointed out by Dr Thom- 
 son. 
 
 “ When the iron has absorbed a quantity of 
 carbon in the blister 'steel furnace, sufficient 
 to constitute steel of a proper degree of hard- 
 ness, and the heat after this is continued to be 
 kept up, the steel will keep absorbing more 
 and more carbon. The fusibility of it will 
 continue to increase, just in the same pro- 
 portion, till at last it becomes so fusible, that 
 even the limited heat of a blister steel furnace 
 brings it down ; and just at the time it is 
 passing to the fluid state, it takes so great a 
 quantity of charcoal, as changes it from the 
 state of steel to that of cast iron. It appears to 
 me, that the charcoal is combined in rich 
 cast iron, in the mechanical state, and not in 
 the chemical, as in steel. 
 
 “ With this you will receive a specimen 
 from the blister steel furnace. The fracture 
 of the bar will shew you steel in the highest 
 state of combination with carbon in which it 
 can exist ; and another part of the same 
 fracture presents the transition from the state 
 of steel to that of cast iron. Should you re- 
 quire it, I will send you a specimen of cast 
 steel in the ingot, and from the same ingot, 
 one in the hammered state. I am,” &c. 
 
 “ John Buttery.”* 
 
 * Steinheilite. Blue quartz of Finland.* 
 
 * Stibium. Antimony.* 
 
 * Stilbite, or Pyramidal Zeolite. See 
 Zeolite. * 
 
 * Stilpnosidfrite. Colour brownish-black. 
 Massive, imitative, and in curved concretions. 
 Splendent, resinous. Fracture conchoidal. 
 Opaque. Streak yellowish-brown. Hard in 
 a low degree. Brittle. Sp. gr. S.77. With 
 borax it gives a dark olive-green glass. Its 
 constituents are, oxide of iron 80.5, silica 
 2.25, water 16, oxide of manganese a trace. 
 — Ullmann. It is said to contain phospho- 
 ric acid. It occurs along with brown iron 
 in Saxony and Bavaria. It is allied to mea- 
 dow iron-ore.* 
 
 * Stones. See Analysis, Earths, Ge- 
 ology, Meteorolite, and Mineralogy.* 
 
 * Stinkstone, or Swinestone. A variety 
 of compact lucullite, a sub-species of lime- 
 stone,* 
 
 * StrahLstein. Actinollte.^ 
 
 Strontia. About 35 years ago a mi- 
 neral was brought to Edinburgh by a dealer 
 in fossils, from a lead-mine at Strontian m 
 Argyllshire, which was generally considered 
 as a carbonate of barytes. It has since been' 
 found near Bristol, in France, in Sicily, and 
 in Pennsylvania. Dr Crawford first observed 
 some differences between its solution in mu- 
 riatic acid, and that obtained from the car- 
 bonate of barytes of Anglezark, and thence 
 supposed it to be a new earth. Dr Hope of 
 Edinburgh had entertained the same opi- 
 nion, and confirmed it by experiments in 
 1791. Kirwan, Klaproth, Pelletier, and Sul- 
 zer did the same. The carbonic acid may 
 be expelled by a heat of 140° of Wedgwood, 
 leaving the strontia behind ; or by dissolv- 
 ing in the nitric acid, and driving this off by' 
 heat. 
 
 Pure strontia is of a greyish-white colour ; 
 a pungent, acrid taste ; and when powdered 
 in a mortar, the dust that rises irritates the 
 lungs and nostrils. Its specific gravity ap- 
 proaches that of barytes. It requires rather 
 more than 160 parts of water at 60° to dis- 
 solve it; but of boiling water much less. 
 On cooling, it crystallizes in thin, transpa- 
 rent, quadraugular plates, generally paral- 
 lelograms, seldom exceeding a quarter of art 
 inch in length, and frequently adhering 
 together. The edges are most frequently 
 bevelled from each side. Sometimes they 
 assume a cubic form. These crystals con- 
 tain about 68 of water; are soluble in 51.4 
 times their weight of water at 60°, and in 
 little more than twice their weight of boil- 
 ing water. They give a blood-red colour to 
 the flame of burning alcohol. The solution 
 of strontia changes vegetable blues to a 
 green. Strontia combines with sulphur 
 either in the wet or dry way, and its sul- 
 phuret is soluble in water. 
 
 In its properties, strontia has a consider- 
 able affinity to barytes. It differs from it 
 chiefly in being infusible, much less soluble, 
 of a different form, weaker in its affinities, 
 and not poisonous. Its saline compounds 
 afford differences more marked . — Edinburgh 
 Trans. 
 
 * The basis of strontia, is strontium, a 
 metal first procured by Sir II. Davy in 
 1 808, precisely in the same manner as ba- 
 rium, to which it is very analogous, but lias 
 less lustre. It appeared fixed, difficultly 
 fusible, and not volatile. It became convert- 
 ed into strontia by exposure to air, and when 
 thrown into water, decomposed it with great 
 violence, producing hydrogen gas, and mak- 
 ing the water a solution of strontia. By 
 igniting the mineral strontianite (see Heavy 
 Sear) intensely with charcoal powder, stron- 
 tia is cheaply procured. Sir II. Davy, from 
 indirect experiments, is disposed to regard it 
 as composed of about 86 strontium + 14 
 
SUB 
 
 SUB 
 
 oxygen, in 100 parts ; and supposing it to 
 be composed ot a prime proportion of each 
 constituent, the equivalent prime of strontium 
 would be 6.143, and of strontia 7.143. 
 Hut from the proportions of the constituents 
 in the carbonate, the prime of strontia ap- 
 pears to be 6.4 or 6.5 ; and hence that of 
 strontium will be 5.5. 
 
 The beautiful red fire which is now so 
 frequently used at the theatres, is composed 
 of the following ingredients : 40 parts dry 
 nitrate of strontian, 13 parts of finely pow- 
 dered sulphur, 5 parts of chlorate of potash 
 (hyperoxymuriate), and 4 parts of sulphuret 
 of antimony. The chlorate of potash and 
 sulphuret of antimony should be powdered 
 separately in a mortar, and then mixed to- 
 gether on paper; after which they may be 
 added to the other ingredients, previously 
 powdered and mixed. No other kind of 
 mixture than rubbing together on paper is 
 required. Sometimes a little realgar is add- 
 ed to the sulphuret of antimony, and fre- 
 quently when the fire burns dim and badly, 
 a very small quantity of very finely powdered 
 charcoal or lampblack will make it perfect. 
 
 For the saline combinations of strontia, 
 see the Acids at the beginning of the Dic- 
 tionary, or Dr Hope’s excellent original dis- 
 sertation on this earth, in the Edin. Phil. 
 Trans, for 1790.* 
 
 * Strontianite. See Heavy Spar.* 
 
 * Strontites. The same as strontia.* 
 
 * Strontium. The metallic base of stron- 
 tia.* 
 
 * Strychnia. This alkaline substance was 
 detected by Pelletier and Caventou in the 
 fruit of the strychnos mix vomica , and strych- 
 ?ios ignatia , about the end of the year 1818. 
 It was obtained from the bean of the strych- 
 nos ignatia by the following process: The 
 bean was rasped down as small as possible. 
 It was then exposed to the action of nitric 
 ether in a Papin’s digester. The residue, 
 thus deprived of a quantity of fatty matter, 
 was digested in alcohol as long as that re- 
 agent was capable of dissolving any tiling. 
 The alcoholic solutions were evaporated to 
 dryness, and the residue redissolved in water. 
 Caustic potash being dropped into the solu- 
 tion, a white crystalline precipitate fell, which 
 was strychnia. It was purified by washing 
 it in cold water, dissolving it in alcohol, and 
 crystallizing it. Strychnia was obtained like- 
 wise from the bean of the strychnos ignatia 
 by boiling the infusion of the bean with 
 magnesia, in the same manner as Ilobiquet 
 had obtained morphia from the infusion of 
 opium. 
 
 The properties of strychnia, when in a 
 state of purity, are as follows : 
 
 It is crystallized in very small four-sided 
 prisms, terminated by four-sided low pyra- 
 mids. It has a white colour, its taste is in- 
 tolerably bitter, leaving a metallic impression 
 in the mouth. It is destitute of smell. It 
 
 is not altered by exposure to the air. It is 
 neither fusible nor volatile, except at tempe- 
 ratures at which it undergoes decomposition. 
 It is charred at the temperature at which oil 
 enters into ebullition (about 580°). When 
 strongly heated, it swells up, blackens, gives 
 out ernpyreumatic oil, a little water and ace- 
 tic acid ; carbonic acid and carburetted hy- 
 drogen gases are disengaged, and a bulky 
 charcoal remains behind. When heated with 
 peroxide of copper, it gives out only carbo- 
 nic acid gas and water. It is very little soluble 
 in cold water, 100,000 parts of that liquid 
 dissolving only 15 parts of strychnia; but 
 it dissolves in 2,500 times its weight of 
 boiling water. A cold solution of strychnia 
 in water may be diluted with 100 times its 
 volume of that liquid without losing its bitter 
 taste. 
 
 When strychnia is introduced into the sto- 
 mach, it acts with prodigious energy. A 
 locked jaw is induced in a very short time, 
 and the animal is speedily destroyed. Half 
 a grain of strychnia blown into the throat of 
 a rabbit proved fatal in five minutes, and 
 brought on locked jaw in two minutes. 
 
 Sulphate of strychnia is a salt which crys- 
 tallizes in transparent cubes, soluble in less 
 than ten times its weight of cold water. Its 
 taste is intensely bitter, and the strychnia is 
 precipitated from it by all the soluble salifi- 
 able bases. It is not altered by exposure to 
 the air. In the temperature of 212° it loses 
 no weight, but becomes opaque. At a higher 
 temperature it melts, and speedily congeals 
 again, with a loss of three per cent of its 
 weight. At a still higher temperature it is 
 decomposed and charred. Its constituents 
 are, 
 
 Sulphuric acid, 9.5 5.00 
 
 Strychnia, 90.5 4 7.63 
 
 100.0 
 
 Muriate of strychnia crystallizes in very 
 small needles, which are grouped together, 
 and before the microscope exhibit the form 
 of quadrangular prisms. When exposed to 
 the air, it becomes opaque. It is more solu- 
 ble in water than the sulphate, has a similar 
 taste, and acts with the same violence upon 
 the animal economy as all the other salts of 
 strychnia. When heated to the temperature 
 at which the base is decomposed, it allows 
 the muriatic acid to escape. 
 
 Phosphate of strychnia crystallizes in four- 
 sided prisms. It can only be obtained neu- 
 tral by double decomposition. 
 
 Nitrate of strychnia can be obtained only 
 by dissolving strychnia in nitric acid, diluted 
 with a great deal of water. I he saturated 
 solution, when cautiously evaporated, yields 
 crystals of neutral nitrate in pearly needles. 
 This salt is much more soluble in hot than 
 in cold water. Its taste is exceedingly hitter, 
 and it acts with more violence upon the ani- 
 mal economy than pure '-trychnia. It seeius 
 
SUB 
 
 SUB 
 
 capable of uniting with an excess of acid. 
 When heated, it becomes yellow, and under- 
 goes decomposition. It is slightly soluble in 
 alcohol, but is insoluble in ether. 
 
 When concentrated nitric acid is poured 
 upon strychnia, it immediately strikes an 
 amaranthine colour, followed by a shade si- 
 milar to that of blood. To this colour suc- 
 ceeds a tint of yellow, which passes after- 
 wards into green. By this action, the 
 strychnia seems to be altered in its proper- 
 ties, and to be converted into a substance 
 still capable of uniting with acids. 
 
 Carbonate of strychnia is obtained in the 
 form of white flocks, little soluble in water, 
 blit soluble in carbonic acid. 
 
 Acetic, oxalic, and tartaric acids, form 
 with strychnia neutral salts, which are very 
 soluble in water, and more or less capable of 
 crystallizing. They crystallize best when 
 they contain an excess of acid. The neu- 
 tral acetate is very soluble, and crystallizes 
 with difficulty. 
 
 Hydrocyanic acid dissolves strychnia, and 
 forms with it a crystallizable salt. 
 
 Strychnia combines neither with sulphur 
 nor carbon. When boiled with iodine, a so- 
 lution takes place, and iodate and hydriodate 
 of strychnia are formed. Chlorine acts upon 
 it precisely in the same way. 
 
 Strychnia, when dissolved in alcohol, has 
 the property of precipitating the greater 
 number of metallic oxides from their acid 
 solutions. It is precipitated by the alkalis 
 and alkaline earths ; but the effect of the 
 earths proper has not been tried. See Ann. 
 de Chim. et de Piiys. x. 142.* 
 
 * Suber. Cork. See Cerin, and Acid 
 (Suberic).* 
 
 Sublimation is a process by which vola- 
 tile substances are raised by heat, and again 
 condensed in the solid form. 
 
 This operation is founded on the same 
 principles as distillation, and its rules are 
 the same, as it is nothing but a dry distilla- 
 tion. Therefore all that lias been said on 
 the article Distillation is applicable here, 
 especially in those cases where sublimation 
 is employed to separate volatile substances 
 from others which are fixed or less volatile. 
 
 Sublimation is also used in other cases : 
 for instance, to combine volatile matters to- 
 gether, as in the operation of the sublimates 
 of mercury ; or to collect some volatile sub- 
 stances, as sulphur, the acid of borax, and all 
 the preparations called llowers. 
 
 The apparatus for sublimation is very 
 simple. A matrass or small alembic is ge- 
 nerally sufficient for the sublimation of small 
 quantities of matter. But the vessels and 
 the method of managing the fire, vary ac- 
 cording to the nature of the matters which 
 are to be sublimed, and according to the 
 form which in to be given to the sublimate. 
 
 'I he beauty of some sublimates consists 
 
 in their being composed of very fine, light 
 parts, such as almost all those called flowers; 
 as flowers of sulphur, of benzoin, and others 
 of this kind. When the matters to be sub- 
 limed are at the same time volatile, a high 
 cucurbit, to which is adapted a capital, arid 
 even several capitals placed one upon ano- 
 ther, are employed. The sublimation is 
 performed in a sand-bath, with only the 
 precise degree of heat requisite to raise the 
 substance wdiich is to be sublimed, and the 
 capitals are to be guarded as much as possi- 
 ble from heat. The height of the cucurbit 
 and of the capitals seems weil contrived to 
 accomplish tins intention. 
 
 When along with the dry matter which 
 is to be collected in these sublimations, a 
 certain quantity of some liquor is raised, as 
 happens in the sublimation of acid of bo- 
 rax, and in the rectification of volatile con- 
 crete alkali, which is a kind of sublimation, 
 a passage and a receiver for these liquors 
 must be provided. This is conveniently 
 done by using the ordinary capital of the 
 alembic, furnished with a beak and a re- 
 ceiver. 
 
 Some sublimates are required to be in 
 masses as solid and compact as their natures 
 allows Of this number are camphor, mu- 
 riate of ammonia, and all the sublimates of 
 mercury. The properest vessels for these 
 sublimations are bottles or matrasses, which 
 are to be sunk more or less deeply in sand, 
 according to the volatility and gravity of 
 the matters that are to be sublimed. In 
 this manner of subliming, the substances 
 having quitted the bottom of the vessel, 
 adhere to its upper part ; and as this part 
 is low and near the fire, they there suffer a 
 degree of heat sufficient to give them a kind 
 of fusion. The art, therefore, of conducting 
 these sublimations consists in applying such 
 a degree of heat, or in so disposing the sand 
 (that is, making it cover more or less the 
 matrass), that the heat in the upper part 
 of the matrass shall be sufficient to mako 
 the sublimate adhere to the glass, and to 
 give it such a degree of fusion as is necessary 
 to render it compact ; but at the same time 
 this heat must not be so great as to force 
 the sublimate through the neck of the ma- 
 trass, and dissipate it. These conditions are 
 not easily to be attained, especially in great 
 works. 
 
 Many substances may be reduced into 
 flowers, and sublimed, which require for 
 this purpose a very great heat, with the ac- 
 cess of free air and even the contact of caals, 
 and therefore cannot be sublimed in dose 
 vessels. Such are most soots or flowers of 
 metals, and even some saline substances. 
 When these sublimates are required, the 
 matters from which they are to be separated 
 must be placed among burning coals in 
 open air; and the flowers are collecfeu in 
 
SUG 
 
 SUG 
 
 the chimney of the furnace in which the 
 operation is performed. The tutty, cala- 
 mine, or pompholix, collected in the upper 
 part of furnaces in which ores are smelted, 
 are sublimates of this kind. 
 
 Subsalt. A salt having an excess of 
 base beyond what is requisite for saturat- 
 ing the acid, as supersalt is one with an ex- 
 cess of the acid. Thus sulphate of potash is 
 the neutral compound of sulphuric acid and 
 potash ; subsulphate of potash, a compound 
 of the same ingredients, in which there is 
 an excess of base ; supersulphate of potash, 
 a compound of the same acid and the same 
 base, in which there is an excess of acid. 
 The term was introduced bv Dr Pearson. 
 
 * Succinates. Compounds of succinic 
 acid with the salifiable bases.* 
 
 * Succinic Acid. See Aem (Succinic).* 
 
 Sugar is a constituent part of vegetables, 
 
 existing in considerable quantities in a num- 
 ber of plants. It is afforded by the maple, 
 the birch, wheat, and Turkey corn. Mar- 
 graaf obtained it from the roots of beet, 
 red beet, skirret, parsnips, and dried grapes. 
 The process of this chemist consisted in di- 
 gesting these roots, rasped, or finely divided, 
 in alcohol. This fluid dissolves the sugar ; 
 and leaves the extractive matter untouched, 
 which falls to the bottom. 
 
 In Canada, the inhabitants extract sucar 
 from the maple. At the commencement 
 of spring, they heap snow in the evening at 
 the foot of the tree, in which they previously 
 make apertures for the passage of the re- 
 turning sap. Two hundred pounds of this 
 juice, afford by evaporation fifteen of a 
 brownish sugar. The quantity prepared 
 annually, amounts to fifteen thousand weight. 
 
 Dr Rush, in the Transactions of the Ame- 
 rican Philosophical Society, vol. iii. has given 
 an account at length, of the sugar maple 
 tree, of which the following is a short ab- 
 stract : — 
 
 The acer saccharmum of Linnaeus, or 
 sugar maple tree, grows in great quantities 
 in the western counties of all the middle 
 States of the American Union. It is as tall 
 as the oak, and from two to three feet in 
 diameter; puts forth a white blossom in the 
 spring, before any appearance of leaves ; its 
 snail branches afford sustenance for cattle, 
 mid its ashes afford a large quantity of ex- 
 cellent potash. Twenty years are required 
 for il to attain its full growth. Tapping 
 dots not injure it; but, on the contrary, it 
 affords more syrup, and of a better quality, 
 the oftener it is tapped. A single tree has 
 not only survived, but flourished, after tap- 
 ping, for forty years. Five or six pounds of 
 sugar are usually afforded by the sap of one 
 tree; though there are instances of the quan- 
 tity exceeding twenty pounds. The sugar 
 is separated from the sap either by freezing, 
 by spontaneous evaporation, or by boiling. 
 
 The latter method is the most used. I)r 
 Rush describes the process; which is simple, 
 and practised without any difficulty by the 
 farmers. 
 
 From frequent trials of this sugar, it does 
 not appear to be in any respect inferior to 
 that of the West Indies. It is prepared at 
 a time of the year when neither insect, nor 
 the pollen of plants, exists to vitiate it, as is 
 the case with common sugar. From calcu- 
 lations grounded on facts, it is ascertained, 
 that America is now capable of producing a 
 surplus of one-eighth more than its own 
 consumption ; that is, on the whole, about 
 135,000,000 pounds ; which, in the country, 
 may be valued at fifteen pounds weight for 
 one dollar. 
 
 The Indians likewise extract sugar from 
 the pith of the bamboo. 
 
 The beet has lately been much cultivated 
 in Germany, for the purpose of extracting 
 sugar from its root. For this the roots are 
 taken up in autumn, washed clean, wiped, 
 sliced lengthwise, strung on threads, and 
 hung up to dry. From these the sugar is 
 extracted by maceration in a small quantity 
 of water ; drawing off* this upon fresh roots, 
 and adding fresh water to the first roots, 
 which is again to be employed the same 
 way, so as to get out all their sugar, and sa- 
 turate the water as much as possible with it. 
 This water is to be strained and boiled down 
 for the sugar. 
 
 Some merely express the juice from the 
 fresh roots, and boil this down ; others boil 
 the roots; but the sugar extracted in either 
 of these ways is not equal in quality to the 
 first. 
 
 Professor Lampadius obtained from 110 
 lbs. of the roots, 4 lbs. of well grained white 
 powder sugar; and the resuluums afforded 
 7 pints of a spirit resembling rum. Achard 
 says, that about a ton of roots produced 
 him a 100 lbs. of raw sugar, which gave 
 55 lbs. of refined sugar, and 25 lbs. of 
 treacle. 
 
 But the sugar which is so universally used, 
 is afforded by tire sugar cane ( arundo sac- 
 charifera ), which is raised in our colonies. 
 When this plant is ripe, it is cut down, and 
 crushed by passing it between iron cylinders 
 placed perpendicularly, and moved by wa- 
 ter or animal strength. The juice which 
 flows out by this strong pressure is received 
 in a shallow trough placed beneath the cy- 
 linder. This juice is called in the French 
 sugar colonies vesou ; and the cane, after 
 having undergone this pressure, is called 
 begasse. The juice is more or less sac- 
 charine, according to the nature of the soil 
 on which the cane has grown, and the wea- 
 ther that has predominated during its 
 growth. It is aqueous when the soil or the 
 weather has been humid ; and in contrary 
 circumstances it is thick and glutinous. 
 
SUG 
 
 SUG 
 
 The juice of the cane is conveyed into 
 boilers, where it is boiled with wood ashes 
 and lime. It is subjected to the same ope- 
 ration in three several boilers, care being 
 taken to remove the scum as it rises. In 
 this state it is called syrup ; and is again 
 boiled with lime and alum till it is sufficient- 
 ly concentrated, when it is poured into a 
 vessel called the cooler. In this vessel it is 
 agitated with wooden stirrers, which break 
 the crust as it forms on the surface. It is 
 afterward poured into casks, to accelerate 
 its cooling; and while it is still warm, it is 
 conveyed into barrels standing upright over 
 a cistern, and pierced through their bottom 
 with several holes stopped with cane. The 
 syrup which is not condensed filters through 
 these canes into the cistern beneath ; and 
 leaves the sugar in the state called coarse 
 sugar , or muscovado. This sugar is yellow 
 and fat, and is purified in the islands in the 
 following manner : The syrup is boiled, and 
 poured into conical earthen vessels, having 
 a small perforation at the apex, which is 
 kept closed. Each cane, reversed on its 
 apex, is supported in another earthen ves- 
 sel. The syrup is stirred together, and then 
 left to crystallize. At the end of fifteen or 
 sixteen hours, the hole in the point of each 
 4X>ne is opened, that the impure syrup may 
 run out. The base of these sugar loaves is 
 then taken out, and white pulverized sugar 
 substituted in its stead ; which being well 
 pressed down, the whole is covered with 
 clay, moistened with water. This water 
 filters through the mass, carrying the syrup 
 with it which was mixed with the sugar, 
 but which by this management flows into 
 a pot substituted in the place of the first. 
 This second fluid is called fine syrup. Care 
 is taken to moisten and keep the clay to a 
 proper degree of softness, as it becomes dry. 
 The sugar loaves are afterward taken out, 
 and dried in a stove for eight or ten days ; 
 after which they are pulverized, packed, and 
 exported to Europe, where they are still 
 farther purified. 
 
 The operation of the French sugar re- 
 finers consists in dissolving the cassonade, 
 or clayed sugar, in lime water. Bullocks’ 
 blood is added, to promote the clarifying ; 
 and, when the liquor begins to boil, the 
 heat is diminished, and the scum carefully 
 taken oil. It is in the next place concen- 
 trated by a brisk heat; and, as it boils up, 
 a small quantity of butter is thrown in, to 
 moderate its agitation. When the boiling 
 is sufficiently effected, the fire is put out ; 
 the liquor is poured into moulds, and agi- 
 tated, to mix the syrup together with the 
 grain sugar already formed. When the 
 whole is cold, the moulds are opened, and 
 the loaves are covered with moistened clay, 
 which is renewed from time to time till the 
 sugar is well cleansed from its syrup. The 
 
 loaves being then taken out of the moulds, 
 are carried to a stove, where they are gra- 
 dually heated to 145° F. They remain in 
 this stove eight days, after which they are 
 wrapped in blue paper for sale. 
 
 The several syrups, treated by the same 
 methods, afford sugars of inferior qualities ; 
 and the last portion, which no longer affords 
 any crystals, is sold by the name of melasses. 
 The Spaniards use this melasses in the pre- 
 paration of sweetmeats. 
 
 A solution of sugar, much less concen- 
 trated than that we have just been speaking 
 of, lets fall by repose crystals, which affect 
 the form of tetrahedral prisms, terminated 
 by dihedral summits, and known by the 
 name of sugarcandy. 
 
 The preceding account of the manufac- 
 ture of sugar in the colonies is chiefly ex- 
 tracted from Chaptal. The following is 
 taken from Edwards’ History of the West 
 Indies, the authority of which is indubita- 
 ble. 
 
 Such planters as are not fortunately fur- 
 nished with the means of grinding their canes 
 by water, are at this season frequently im- 
 peded by the failure or insufficiency of their 
 mills ; for though a sugar mill is a very 
 simple contrivance, yet great force is requi- 
 site to make it vanquish the resistance which 
 it necessarily meets with. It principally con- 
 sists of three upright iron rollers or cylinders, 
 from thirty to forty inches in length, and 
 from twenty to twenty-five inches in dia- 
 meter ; and the middle one, to which the 
 moving power is applied, turns the other two 
 by means of cogs. The canes, which are 
 previously cut short and tied into bundles, are 
 twice compressed between these rollers; for 
 after they have passed through the first and se- 
 cond rollers, they are turned round the middle 
 one by a piece of frame work of a circular 
 form, which is called in Jamaica the dumb- 
 returner, and forced back through the second 
 and third. By this operation they are squeez- 
 ed completely dry, and sometimes even re- 
 duced to powder. The cane-juice is re- 
 ceived in a leaden bed, and thence convey- 
 ed into a vessel called the receiver. The 
 refuse, or macerated rind of the cane, which 
 is called cane-trash, serves for fuel to boil 
 the liquor. 
 
 The juice from the mill usually contains 
 eight parts of pure water, one part of sugar, 
 and one part made up of gross oil and mu- 
 cilage, with a portion of essential oil. The 
 proportions are taken at a medium ; for 
 some juice has been so rich as to make a 
 hogshead or sixteen hundred weight of sugar 
 from thirteen hundred gallons, and some is 
 so watery as to require more than double that 
 quantity. I lie richer the juice is, the less 
 it abounds with redundant oil and gum ; 
 so that very little knowledge of the contents 
 of any other quantity can be obtained by 
 
SUG 
 
 SUG 
 
 the most exact analysis of any one quantity 
 of mice. 
 
 The following matters are likewise usually 
 contained in cane-juice. Some of the green 
 tops, which serve to tie the canes in bundles, 
 are often ground in, and yield a raw acid 
 juice exceedingly disposed to ferment and 
 render the whole liquor sour. Beside these 
 they grind in some pieces of the ligneous 
 part of the cane, some dirt, and lastly, a 
 substance of some importance, which may 
 be called the crust. This substance is a thin 
 black coat of matter that surrounds the cane 
 between the joints, beginning at each joint, 
 and gradually growing thinner the farther 
 from the joint upwards, till the upper part 
 between the joints appears entirely free from 
 it, and resumes its bright yellow colour. It 
 is a line black powder, that mixes with the 
 clammy exudations from the cane; and as 
 the fairness of the sugar is one symptom oi 
 its goodness, a small quantity of this crust 
 must very much prejudice the commodity. 
 
 The sugar is obtained by the following 
 process : — The juice or liquor runs from the 
 receiver to the boiling-house, along a wooden 
 gutter lined with lead. In the boiling-house, 
 it is received into one of the copper pans or 
 caldrons called claritiers. Of these there 
 are generally three ; and their dimensions 
 are determined by the power of supplying 
 them with liquor. There are water mills 
 that will grind with great facility sufficient 
 for thirty hogsheads of sugar in a week. 
 Methods of quick boiling cannot be dispens- 
 ed with on plantations thus fortunately pro- 
 vided ; for otherwise the cane liquor would 
 unavoidably become tainted before it could 
 be exposed to the fire. The purest cane- 
 juice wall not remain twenty minutes in the 
 receiver without fermenting. Hence, clari- 
 fiers are sometimes seen ol one thousand 
 gallons each. But on plantations that, dur- 
 ing crop time, make from fifteen to twenty 
 hogsheads of sugar a-week, three clarifiers 
 of three or four hundred gallons each are 
 sufficient. The liquor, when clarified, may 
 be drawn off at once, with pans of this size, 
 and there is leisure to cleanse the vessels 
 everv time they are used. Bach clarifier is 
 furnished either with a siphon or cock lor 
 drawing oil the liquor. It has a fiat bottom, 
 and is hung to a separate fire, each chimney 
 having an iron slider, which, when shut, 
 causes the fire to be extinguished through 
 want of air.f 
 
 f The clarifiers are generally placed in the middle 
 or at one end of the boiling-house. When they are 
 placed at one end, the boiler called tbe teache is placed 
 at the other, and three boilers are usually ranged be- 
 tween them. The teache commonly holds from / 0 to 
 100 gallons, and the boilers between the claritiers and 
 teache diminish in size from the first to the last, But 
 when the clarifiers are in the middle, there is genc- 
 rallv a set of three boilers on each side, which in effect 
 form a double boiling-house. This arrangement is 
 very necessary on large estates. 
 
 As soon as the stream from the receiver 
 has filled the clarifier with fresh liquor, and 
 the fire is lighted, the temper, w hich is gener- 
 ally Bristol white-lime in powder, is stirred in- 
 to it. This is done, in order to neutralize the 
 superabundant acid, and to get rid of which 
 is the greatest difficulty in sugar making. 
 Alkali, or lime, generally effects this ; and 
 at the same time part of it is said to become 
 the basis of the sugar. Mr Edwards affirms, 
 that it affects both the smell and taste of the 
 sugar. It falls to the bottom of the pans in 
 a black insoluble matter, which scorches the 
 bottom of the vessels, and cannot without 
 difficulty be detached from them. But, in 
 order that less of the lime may be precipitat- 
 ed to the bottom, little more than half a pint 
 of Bristol lime should be allowed to every 
 hundred gallons of liquor, and INI r Bousie*s 
 method of dissolving it in boiling water pre- 
 vious to mixing it w ith the cane-juice should 
 be adopted.' f 
 
 As the force of the fire increases, and the 
 liquor grows hot, a scum is throw n up, which 
 is formed of the gummy matter of the cane, 
 with some of the oil, and such impurities as 
 the mucilage is able to entangle. The heat 
 is now suffered to increase gradually till it 
 nearly rises to the heat of boiling water. 
 The liquor, how r ever, must by no means be 
 suffered to boil. When the scum begins to 
 rise into blisters, which break into white 
 froth, and generally appear in about forty 
 minutes, it is known to be sufficiently heat- 
 ed. Then the damper is applied, and the 
 fire extinguished ; and, if circumstances will 
 admit, the liciuor after this is suffered to re- 
 main a full hour undisturbed. In the next 
 place, it is carefully drawn off, either by a 
 siphon, which draws up the clear fiuid 
 through the scum, or by means of a cock at 
 the bottom. In either case, the scum sinks 
 down without breaking as the liquor flows ; 
 for its tenacity prevents any admixture. r l lie 
 liquor is received into a gutter or channel, 
 which conveys it to the evaporating boiler, 
 commonly called the grand copper ; and if 
 produced at first from good and untainted 
 canes, it w ill then appear almost transparent. 
 
 In the grand or evaporating copper, 
 which should be sufficiently large to re- 
 ceive the net contents of one of the clarifiers, 
 
 f Mi* Bousie, to whom, for his improvements in the 
 art of sugar-boiling, the Assembly of Jamaica gave 
 L. 1000,i n a paper which he distributed among the mem- 
 bers, recommends the use of vegetable alkali, or ashes 
 of wood, such as pimento tree, dumb cane, fern tree, 
 cashew, or logwood, as affording a better temper than 
 quicklime. Afterward, however, he was convinced, 
 that sugar formed on the basis of fixed alkaline sal's 
 never stands the sea, unless some earth is united to 
 the salts. Such earth as approaches nearest to the 
 basis of alum, Mr Id wards thinks, would be most 
 proper ; and it deserves to be inquired, how far a 
 proper mixture of vegetable alkaline salts and lime 
 might prove a better temper than either lime or alka- 
 line salts alone. In some parts of Jamaica, where the 
 cane-liquor was exceedingly rich, Mr Bousie made 
 very good sugar without a particle of temper. 
 
SUG 
 
 the liquor is suffered to boil, and the scum, 
 as it rises, is continually taken off by large 
 scummers, till the liquor becomes finer and 
 somewhat thicker. This operation is conti- 
 nued, till the subject is so reduced in quan- 
 tity, that it may be contained in the next or 
 second copper, into which it is then ladled. 
 The liquor is now almost of the colour of 
 Madeira wine. In the second copper the 
 boiling and scumming are continued ; and 
 if the subject be not so clean as is expected, 
 lime-water is thrown into it. This addition 
 not only serves to give more temper, but 
 likewise to dilute the liquor, which some- 
 times thickens too fast to permit the fecu- 
 lencies to rise in the scum. When the froth 
 in boiling arises in large bubbles, and is not 
 much discoloured, the liquor is said to have 
 a favourable appearance in the second cop- 
 per. When, in consequence of such scum- 
 ming and evaporation, the liquor is again so 
 reduced, that it may be contained in the 
 third copper, it is ladled into it, and so on to 
 the las* copper, which is called the teache. 
 This arrangement supposes four boilers or 
 coppers, besides the three clarifiers. 
 
 In the teache the subject undergoes an- 
 other evaporation, till it is supposed boiled 
 enough to be removed from the fire. This 
 operation is usually called striking, i. e. lad- 
 ling the liquor, which is now exceeding 
 thick, into the cooler. 
 
 The cooler, of which there are generally 
 six, is a shallow' wooden vessel, about eleven 
 inches deep, seven feet in length, and from 
 five to six feet wide. A cooler of this size 
 holds a hogshead of sugar. Here the sugar 
 grains, i. e. as it cools, it runs into a coarse 
 irregular mass of imperfect crystals, separat- 
 ing itself from the melasses. From the 
 cooler it is taken to the curing-house, where 
 the melasses drains from it.f 
 
 But here it may be proper to notice the 
 rule for knowing when the subject is fit to 
 be ladled from the teache to the cooler. 
 Many of the negro boilers, from long ha- 
 bit, guess accurately by the eye alone, 
 judging by the appearance of the grain on 
 the back of the ladle ; but the practice ge- 
 nerally adopted is to judge by what is called 
 the touch, i. e. taking up with the thumb a 
 small portion of the hot liquor from the 
 ladle, and, as the heat diminishes, drawing 
 with the forefinger the liquid into a thread. 
 This thread will suddenly break and shrink 
 from the thumb to the suspended finger, in 
 different lengths, according as the liquor is 
 more or less boiled. A thread of a quarter 
 of an inch long generally determines the 
 
 t It is necessary to observe in this place, that, in 
 order to obtain a large-grained sugar, it must be suf- 
 fered to cool slowly and gradually. If the coolers be 
 too shallow, the grain is injured in a surprising man- 
 ner. 
 
 SUG 
 
 proper boiling height for strong muscovado 
 
 ^gar. t # , . mi- 
 
 The curing-house is a large airy building, 
 
 provided with a capacious melasses cistern, 
 the sides of which are sloped and lined with 
 terras, or boards. A frame of massy joist- 
 work without boarding, is placed over this 
 cistern ; and empty hogsheads without 
 headings are ranged on the joints of this 
 frame. Ei<rht or ten holes are bored in 
 the bottoms of these hogsheads, and through 
 each of the holes the stalk of a plantain leaf 
 is thrust six or eight inches below the joists, 
 and long enough to stand upright above 
 the top of the hogshead. Into these hogs- 
 heads the mass from the cooler is put, which 
 is called potting ; and the melasses drains 
 through the spungy stalk, and drops into 
 the cistern, whence it is occasionally taken 
 for distillation. In the space of three weeks, 
 the sugar becomes tolerably dry and fair. 
 It is then said to be cured, and the process is 
 finished. 
 
 Sugar thus obtained is called muscovado, 
 and is the raw r material whence the British 
 sugar-bakers chiefly make their loaf or re- 
 fined lump. There is another sort, which 
 w'as formerly much used in Great Britain for 
 domestic purposes, and was generally known 
 by the name of Lisbon sugar. In the West 
 Indies it is called clayed sugar ; and the pro- 
 cess of making it is as follow's : — 
 
 A quantity of sugar from the cooler is 
 put into conical pots or pans, w r hich the 
 French call formes , W'ith the points down- 
 ward, having a hole about half an inch in 
 diameter at the bottom, for the melasses to 
 drain through, but which at first is closed 
 with a plug. As soon as the sugar in these 
 pots is cool, and becomes a fixed body, 
 which is know'll by the middle of the top 
 falling in, the plug is taken out, and the pot 
 placed over a large jar, intended to receive 
 the syrup or melasses that drain from it. 
 In this state it is left as long as the melasses 
 continues to drop, when a stratum of clay 
 is spread on the sugar, and moistened with 
 water. This, imperceptibly oozing through 
 the pores of the clay, dilutes the melasses, 
 
 t The vessel called the teache probably derived its 
 name from this practice of trying by the touch (tactio). 
 Some years ago, John Proculus Baker, Esq. barrister 
 at law, recommended to the public a method more 
 scientific and certain, in a treatise which he published 
 in 1775, entitled, An Essay on the Art of making Mus- 
 covado Sugar. It is as follows : “ Provide a small thin 
 pane of clear crown glass, set in a frame, which I 
 w'ould call a tryer ; on this drop two or three drops of 
 the subject, one on the other, and carry your tryer out 
 of the boiliug-housc into the air. Observe your sub- 
 ject, and more particularly whether it grain freely and 
 whether a small edge of melasses separate at the bot- 
 tom. I am well satisfied, that a little experience will 
 enable you to judge what appearance the whole skin 
 will put on when cold, by this specimen, which is also 
 cold. I Ins method is used by chemists, to try evapo- 
 rated solutions of all other salts : it may seem there 
 fore somewhat strange, it has not been' long adopted 
 in the hoihng-liouse.” 
 
SUG 
 
 SUG 
 
 in consequence of which more of it comes 
 away than from sugar cured in the hogs- 
 head, and the sugar of course becomes so 
 much whiter and purer. According to 
 Sloane, the process was first discovered in 
 Brasil, by accident: “ A hen,” says he, 
 
 “ having her feet dirty, going over a pot of 
 sugar, it was found under her feet to be 
 whiter than elsewhere.” The reason as- 
 signed why this process is not universally 
 adopted in the British sugar islands is this, 
 that the water which dilutes and carries 
 away the melasses, dissolves and carries with 
 it so much of the sugar, that the difference 
 in quality does not pay for the difference in 
 quantity. It is probable, however, that the 
 French planters are of a different opinion ; 
 for upwards of four hundred of the planta- 
 tions of St Domingo have the necessary ap- 
 paratus for claying, and actually carry on 
 the system. 
 
 Sugar is very soluble in water, and is a 
 good medium for uniting that fluid with oily 
 matters. It is much used for domestic pur- 
 poses, and appears on the whole to be a va- 
 luable and wholesome article of food, the 
 uses of which are most probably restricted 
 by its high price. This price may in a cer- 
 tain degree arise from the nature of the 
 article, and its original cost ; but is no doubt 
 in a «reat measure owing to the inhuman 
 and wasteful culture by slaves, and the absurd 
 principles of European colonization, duties, 
 drawbacks, and bounties, which have the 
 effect to create unnatural monopolies, and to 
 prevent commerce from finding its level. 
 This is eminently the case with regard to our 
 West- India islands, and their produce. 
 
 It appears that sugar has the property of 
 rendering some of the earths soluble in wa- 
 ter. This property was accidentally disco- 
 vered by Mr William Ramsay of Glasgow. 
 
 Being employed in making experiments 
 on sugar, and happening to put some quick- 
 lime into a cold solution of it, he noticed, 
 that it had acquired an uncommon caustic 
 taste. 
 
 Hence he concluded, that sugar possesses 
 the property of dissolving a certain propor- 
 tion of lime ; and in order to ascertain its 
 capacity in this respect, experiments were 
 made upon this earth, together with strontites, 
 magnesia, and barytes. 
 
 Sugar, dissolved in water at the tempera- 
 ture of 50°, is capable of dissolving one-half 
 of its weight of lime. 
 
 The solution of lime in sugar is of a beau- 
 tiful white-wine colour, and has the smell of 
 fresh slaked quicklime. 
 
 It is precipitated from the solution, by the 
 carbonic, citric, tartaric, sulphuric, and 
 oxalic acids ; and it is decomposed, by dou- 
 ble affinity, by caustic and carbonated potash 
 and soda, the citrate, tartrate, and oxalate of 
 potash, Sec, 
 
 An equal weight of strontia, with the 
 sugar employed, is capable of being dissolv- 
 ed at the temperature of 212°, and of being 
 retained in solution by the sugar at 50° of 
 Fahrenheit On exposing the crystals, which 
 had fallen down during the cooling of the 
 liquid, to the air of the atmosphere, they 
 attracted carbonic acid, and effloresced. 
 
 The solution of strontia in su^ar is of a 
 fine white-wine colour, and,‘like that of lime, 
 has a peculiar caustic smell. This earth is 
 precipitated by caustic and carbonated pot- 
 ash and soda; also by the carbonic, citric, 
 tartaric, sulphuric, and oxalic acids; and it 
 is decomposed, by compound affinity, by the 
 carbonates of potash and soda ; also by the 
 citrate, tartrate, and oxalate of potash. 
 
 The solution of magnesia in syrup, like 
 those of lime and strontia, was of a pure 
 white colour, and had no sensible variation 
 in smell or taste from the common solution 
 of sugar, farther than that the sweet seemed 
 much improved, and was softer and more 
 agreeable to the palate, as if it were entirely 
 freed from the earthy taste, which unrefined 
 sugar frequently has. On its remaining at 
 rest for some months in a bottle well corked, 
 the magnesia appears to be entirely separat- 
 ed. 
 
 Very little alumina is dissolved by a solu- 
 tion of sugar, when fresh precipitated earth 
 is presented to it, either in the cold or hot 
 state. 
 
 The union of sugar with the alkalis, has 
 been long known ; but this is rendered more 
 strikingly evident, by carbonated potash or 
 soda, for instance, decomposing the solutions 
 of lime and strontia in sugar, by double 
 affinity. 
 
 In making solutions of unrefined sugar 
 for culinary purposes, a grey-coloured sub- 
 stance is found frequently precipitated. It 
 is probable, that this proceeds from a super- 
 abundance of lime, which has been used in 
 clarifying the juice of the sugar-cane at the 
 plantations abroad. Sugar with this imper- 
 fection is known among the refiners of this 
 article by the name of weak. And it is justly 
 termed so, the precipitated matter being no- 
 thing but lime which has attracted carbonic 
 acid from the sugar, (of which there is a 
 great probability), or from the air of the 
 atmosphere. A bottle in which I had kept 
 a solution of lime in sugar for at least four 
 years, closely corked, was entirely incrusted 
 with a yellowish-coloured matter, which on 
 examination was found to be entirely carbo- 
 nate of lime. 
 
 * In the ordinary refining of raw sugars, 
 from twenty to thirty-five percent of melasses 
 are separated, of which a considerable part, 
 probably two-thirds, are formed by the high 
 lieat used in the concentration of the syrup. 
 Various plans have been contrived to dimi- 
 nish this production of melasses. One ot 
 
SUG 
 
 SUG 
 
 these consisted in surrounding the sugar 
 boiler with oil or steam at a high tempera- 
 ture, instead of exposing it to a naked fire. 
 In a second, the boiler is covered at top, and 
 by means of an air-pump the atmospheric 
 pressure is removed, so as to favour ebulli- 
 tion, and rapid evaporation, at moderate heats. 
 
 The celebrated chemist, Mr Howard, took 
 out a patent for this plan, which is undoubt- 
 edly the most scientific and productive of 
 any ; but requires superior skill and very 
 minute attention in the manufacturer. No 
 blood is used for clarification. This is ac- 
 complished by a system of most ingenious 
 canvas filters, aided by the intermixture 
 with the syrup, of a small quantity of pasty 
 gypsum and alumina, made by saturating a 
 solution of alum with quicklime. In the 
 final purification, the base of the inverted 
 sugar cone, is covered with a stratum of very 
 pure saturated syrup, instead of moist pipe- 
 clay. 
 
 The third method is founded on the pro- 
 perty which animal charcoal (bone-black) 
 possesses, of destroying vegetable colouring 
 matter. Perhaps the combination of the 
 last two modes promises the best results. 
 
 A fourth process for refining sugar is that 
 of Mr Daniel Wilson, for which a patent 
 was granted. The specification is in the 
 34th vol. of the Repertory, p. 134. 
 
 The pan is to be charged with strong lime- 
 water, the sugar added, and the fire set in 
 the usual manner. For every hundred weight 
 of sugar used, a solution is to be made of 
 four ounces of sulphate of zinc, in as small a 
 quantity of water as will dissolve it. When 
 the sugar in the pan is melted, the solution 
 of sulphate of zinc is added, and the whole 
 well stirred. The oxide of zinc combines 
 with the extractive matter, tannin and gallic 
 acid, and renders them insoluble, while the 
 sulphuric acid, in combination with the lime, 
 becomes also insoluble. When raw sugar 
 contains much acid, and a strong grain is 
 required, take one ounce of lime in powder 
 for every four ounces of sulphate of zinc, 
 and as much water as will form a milk of 
 lime, which is added to the solution of su- 
 gar in the pan, about five minutes after the 
 solution of sulphate of zinc has been added. 
 This purification of sugar by separating im- 
 purities chemically combined with it, is em- 
 ployed with much advantage in conjunction 
 with the patent filtering apparatus invented 
 by Mr John Sutherland. The solution of 
 sugar brought to the boiling point is run 
 through the filter, and afterwards boiled to a 
 proof. Mr Wilson boils the syrup in a pan, 
 having a coil of tinned copper or pure tin 
 tubes placed along its bottom and sides, 
 through which a constant stream of strongly 
 heated oil, or other fatty matter, is made to 
 pass. The oxide of zinc precipitated pre- 
 viously by adding a solution of the salt to 
 
 lime-water, is also recommended, as well as 
 the oxide of tin. 
 
 MrKirchoff, an ingenious Russian chemist, 
 accidentally discovered, that starch is con- 
 vertible into sugar, by being boiled for some 
 time with a very dilute sulphuric acid. 
 Saussure showed, that 100 parts of starch 
 yield ] 10 of sugar. Fie concluded, that this 
 sugar is merely a compound of water and 
 starch. According to his analysis, starch 
 consists of 
 
 Oxygen, 55.87 
 Carbon, 37.29 
 Hydrogen, 6.84 
 
 100.00 
 
 Sugar of grapes, according to the 9ame 
 chemist, is composed of 
 
 Oxygen, 56.51 
 Carbon, 36.7 1 
 Hydrogen, 6.78 
 
 100.00 
 
 Common sugar has been analyzed by many 
 eminent chemists. The following is a ge- 
 neral view of the results : 
 
 G. Lussac and 
 
 Berzelius. 
 
 Prout. 
 
 Thenard. 
 
 Mean of o. 
 
 
 Oxygen, 50.63 
 
 49.856 
 
 53,33 
 
 Carbon, 42.47 
 
 43.265 
 
 39.99 
 
 Hydrogen, 6.90 
 
 6.879 
 
 6.66 
 
 100.00 
 
 100.000 
 
 100.00 
 
 For a view of the proportions of the con- 
 stituents referred to equivalent primes or 
 volumes, see Fermentation', column 4. I 
 am happy to observe, that Dr Trout’s experi- 
 mental results agree with M. Gay Lussac’s 
 theory, of sugar being a compound of 40 
 parts of carbon -|- 60 of water, or its ele- 
 ments. By Berzelius’ analysis, starch con- 
 sists of Oxygen, 49.5 
 
 Carbon, 43.5 
 Hydrogen, 7.0 
 
 100.0 
 
 The abstraction of a little hydrogen and 
 carbon, would convert it into sugar. But 
 no carbonic acid or other gas, is extricated 
 during the conversion, according to Vogel’s 
 experiments. I find that potatoes digested 
 with dilute sulphuric acid, yield sugar cheaply 
 and abundantly. The acid is afterwards re- 
 moved by chalk ; and the strained liquor left 
 to repose, after due evaporation, affords crys- 
 tals of sugar. From starch sugar, good beer 
 lias been made. I would recommend pota- 
 toes for this purpose. They are washed, 
 grated down, and treated with the dilute acid 
 for a day or two at a temperature of 212°. 
 
 M. Braconnot lias recently extended our 
 views concerning the artificial production of 
 sugar and gum. Sulphuric acid (sp. gr. 
 1.827) mixed with well dried elm dust, be- 
 came very hot, and on being diluted with 
 
SUL 
 
 SUL 
 
 water, and neutralized with chalk, afforded 
 a liquor, which became gummy on evapora- 
 tion. Shreds of linen triturated in a glass 
 mortar, with sulphuric acid, yield a similar 
 gum. Nitric acid has a similar power. If 
 the gummy matter from linen be boiled for 
 some time with dilute sulphuric acid, we ob- 
 tain a crystal lizable sugar, and an acid, which 
 M. Braconnot calls the vegeto-sulphuric acid. 
 The conversion of wood also into sugar, will 
 no doubt appear remarkable ; and when per- 
 sons not familiarized with chemical specula- 
 tions are told, that a pound weight of rags 
 can be converted into more than a pound 
 weight of sugar, they may regard the state- 
 ment as a piece of pleasantry, though no- 
 thing, says M. Braconnot, can be more real. 
 
 Silk is also convertible into gum by sul- 
 phuric acid. Twelve grammes of glue, re- 
 duced to powder, were digested with a double 
 weight of concentrated sulphuric acid with- 
 out artificial heat. In twenty hours the liquid 
 was not more coloured than if mere water 
 had been employed. A decilitre of water was 
 then added, and the whole was boiled for 5 
 hours, with renewal of the water, from time 
 to time, as it wasted. It was next diluted, 
 saturated with chalk, filtered and evaporated 
 to a syrupy consistence, and left in repose 
 for a month. In this period a number of 
 granular crystals had separated, which ad- 
 hered pretty strongly to the bottom of the 
 vessel, and had a very decided saccharine 
 taste. This sugar crystallizes much more 
 easily than cane sugar. The crystals are 
 
 gritty under the teeth, like sugar-candy; 
 and in the form of flattened prisms or tabu- 
 lar groupes. Its taste is nearly as saccha- 
 rine as grape sugar; its solubility in water, 
 scarcely exceeds that of sugar of milk. Boil- 
 ing alcohol, even when diluted, has no action 
 on this sugar. By distillation it yields am- 
 monia, indicating the presence of azote. This 
 sugar combines intimately with nitric acid, 
 without sensibly decomposing it, even with 
 the assistance of heat, and there results a 
 peculiar crystallized acid, to which the name 
 nitro-saccharine has been given. Annales 
 dc Chimie , xii. or Tilloch's Magazine , vol. 55, 
 and 56. 
 
 The varieties of sugar are ; cane sugar, 
 maple sugar, liquid sugar of fruits, sugar of 
 figs, sugar of grapes, starch sugar, the mush- 
 room sugar of Braconnot, manna, sugar of 
 gelatin, sugar of honey, and sugar of diabetes. 
 “ The relation,” says l)r Prout, “ which 
 exists between urea and sugar, seems to ex- 
 plain in a satisfactory manner the phenomena 
 of diabetes, which may be considered as a 
 depraved secretion of sugar. The weight of 
 the atom of sugar, is just half that of the 
 weight of the atom of urea; the absolute 
 quantity of hydrogen in a given weight of 
 both is equal ; while the absolute quantities 
 of carbon and oxygen in a given weight of 
 sugar, are precisely twice those of urea.” 
 
 The constituents of these two bodies and 
 lithic acid, are thus expressed by that inge- 
 nious philosopher. 
 
 Elements. 
 
 
 Urea. 
 
 
 Sugar 
 
 • 
 
 Lithic i 
 
 \cin. 
 
 No. 
 
 Per 
 
 Atom. 
 
 Per 
 
 Cent. 
 
 No. 
 
 Per 
 
 Atom. 
 
 Per 
 
 Cent. 
 
 No. 
 
 Per 
 
 Atom. 
 
 Per 
 
 Cent. 
 
 Hydrogen, 
 
 2 
 
 2.5 
 
 6.66 
 
 1 
 
 1.25 
 
 6.66 
 
 1 
 
 1.25 
 
 2.85 
 
 Carbon, 
 
 1 
 
 7.5 
 
 1 9.99 
 
 1 
 
 7.50 
 
 39.99 
 
 2 
 
 15.00 
 
 34.28 
 
 Oxygen, 
 
 1 
 
 10.0 
 
 26. 66 
 
 1 
 
 10.00 
 
 53.33 
 
 1 
 
 10.00 
 
 22.85 
 
 Azote, 
 
 1 
 
 17.5 
 
 46.66 
 
 
 
 
 1 
 
 17.50 
 
 40.00 
 
 
 5 
 
 57.5 
 
 100.00 
 
 5 
 
 18.75 
 
 100.00 
 
 5 
 
 43.75 
 
 loo.ool 
 
 The above compounds, appear to be form- 
 ed by the union of more simple compounds, 
 as sugar, of carbon and water ; urea, of car- 
 buretted hydrogen and nitrous oxide ; lithic 
 acid, of cyanogen and water, &c. whence it is 
 inferred, that their artificial formation falls 
 within the limits of chemical operations.* 
 
 * Sugar of Lead. Acetate of lead. See 
 Lead. * 
 
 * Sulphates. Definite compounds of sul- 
 phuric acid with the salifiable bases. See 
 Acid (Sulphuric), and the respective bases.* 
 
 * Sulphites. Definite compounds of sul- 
 phurous acid with the bases.* 
 
 * Sulphur. Of native or prismatic sul- 
 
 47 
 
 phur, there are two species, the common and 
 volcanic ; the former is of two kinds com- 
 pact and earthy sulphur. 
 
 § 1. Compact common sulphur. Colour 
 sulphur-yellow, and yellow of other shades. 
 Massive, disseminated, and crystallized. Its 
 primitive figure is a pyramid of 107° 19'; 
 and 84° 24'; basis = 102° 41'. The se- 
 condary figures are, the primitive variously 
 truncated, or acuminated, and delicate acicu- 
 lar crystals. Shining or glimmering. ( lea- 
 vage prismatic and axifrangible. Fracture 
 uneven. Translucent. Refracts double. 
 Harder than talc. Brittle. M hen rubbed, 
 it exhales a faint sulphureous smell, and be- 
 
SUL 
 
 SUL 
 
 comes resino-electric. Sp.gr. 1.9 to 2.1. 
 It occurs in considerable abundance in pri- 
 mitive mountains, in a state of combination 
 with metals, forming the different genera of 
 pyrites, glance and blende. In secondary 
 mountains it is more abundant in the pure 
 uncombined state. It is found in the island 
 of Iceland, associated with gypsum ; or in 
 crusts investing alluvial substances. Very 
 superb specimens of crystallized sulphur are 
 found at Conil near Cape Trafalgar. It oc- 
 curs abundantly in Sicily, at Urbino in the 
 Papal States, in Arragon in Spain, and 
 Lauenstein in Hanover. 
 
 § 2. Earthy common sulphur. Colour 
 pale straw-yellow. Massive and dissemi- 
 nated. Dull. Fracture fine earthy. Opaque. 
 Does not soil. Soft to friable. It occurs in 
 drusy cavities in flint, and along with the 
 compact varieties in gypsum, and other 
 rocks. 
 
 2. Volcanic sulphur. Colour pale sulphur- 
 yellow. Massive, imitative, and crystallized 
 in pyramids. Glistening, inclining to ada- 
 mantine. Fracture uneven. Slightly trans- 
 lucent. It occurs abundantly at Solfatera in 
 the neighbourhood of Vesuvius, and in Ice- 
 land. — Jameson. * 
 
 * Sulphur. A simple inflammable body, 
 of great importance in chemistry and the 
 arts. To the properties above mentioned, 
 we shall here add, that its fusing point is 
 about 220° F., before which temperature, it 
 begins to evaporate. At 560°, it takes fire 
 in the open air, and burns with a pale blue 
 flame. When kept melted in an open ves- 
 sel for some time, about 500° F., it becomes 
 thick and viscid ; and if it be then poured 
 into a basin of water, it appears of a red co- 
 lour, and ductile like wax. In this state, it 
 is used for taking impressions of seals or 
 medals. Its sp. gr. is said to be increased 
 from 1.99 to 2.325. This change is not 
 owing to oxidation, for it takes place in close 
 vessels. 
 
 When a roll of sulphur is suddenly seized 
 in a warm hand, it crackles, and sometimes 
 falls in pieces. This is owing to the unequal 
 action of heat, on a body which conducts 
 that power slowly, and which has little cohe- 
 sion. If a mass of sulphur be melted in a 
 crucible and after the surface begins to con- 
 crete, if the liquid matter below be allowed 
 to run out, fine acicular crystals of sulphur 
 will be obtained. 
 
 Sulphur is insoluble in water ; but in small 
 quantity in alcohol and ether, and more 
 largely in oil. 
 
 Sulphur combines with oxygen in four defi- 
 nite proportions, constituting an interest mi- 
 series of acids. See Acid (Sulp huric). 
 
 from these combinations it is inferred, 
 that the prime equivalent of sulphur is 2 ; 
 and the density of its vapour is 1.111 = that 
 of oxygen gas. 
 
 Sulphur combines readily with chlorine. 
 This compound was first made by Dr 1 horn- 
 son, who passed chlorine gas through flowers 
 of sulphur. It may be made more expedi- 
 tiously by heating sulphur in a retort con- 
 taining chlorine. The sulphur and chlorine 
 unite, and form a fluid substance, which is 
 volatile, below 200° F., and distils into the 
 cold part of the retort. This substance, 
 seen by reflected light, appears of a red co- 
 lour, but is yellowish-green when seen by 
 transmitted light. It smokes when exposed 
 to air, and has an odour somewhat resem- 
 bling that of sea- weed, but much stronger; 
 it affects the eyes like the smoke of peat. 
 Its taste is acid, hot, and bitter. Its sp. gr. 
 is 1.7. 
 
 It does not redden perfectly dry paper 
 tinged with litmus ; when it is agitated in 
 contact with water, the w r ater becomes cloudy 
 from the appearance of sulphur, and strong- 
 ly acid, and it is found to contain oil of vi- 
 triol. 
 
 According to Sir II. Davy’s experiments, 
 10 grains of pure sulphur absorb nearly 30 
 cubic inches of chlorine, so that the com- 
 pound contains about 2. sulphur to 4.5 chlo- 
 rine, or a prime equivalent of each. 
 
 The compound formed in the manner 
 above described, cannot be made to unite to 
 more chlorine ; but it can dissolve a consi- 
 derable portion of sulphur by heat, and be- 
 comes of a tawny- yellow colour. 
 
 Iodide of sulphur is easily formed by mix- 
 ing the two ingredients in a glass tube, and 
 exposing them to such a heat as melts the 
 sulphur. It is grevish-black, and has a ra- 
 diated structure like that of sulphuret of an- 
 timony. When distilled with water, iodine 
 is disengaged. 
 
 Sulphur and hydrogen combine. Their 
 union may be effected, by causing sulphur 
 to sublime in dry hydrogen in a retort. 
 There is no change of volume ; but only a 
 part of the hydrogen can be united with the 
 sulphur in this mode of operating. 
 
 The usual way of preparing sulphuretted 
 hydrogen, is to pour a dilute sulphuric or 
 muriatic acid, on the black sulphuret of iron 
 or antimony in a retort. For accurate ex- 
 periments it should be collected over mer- 
 cury. It takes fire when a lighted taper is 
 brought in contact with it, and burns with a 
 pale blue flame, depositing sulphur. Its 
 smell is extremely fetid, resembling that of 
 rotten eggs. Its taste is sour. It reddens 
 vegetable blues. It is absorbable by water, 
 which takes up more than an equal volume 
 of the gas. Its sp. gr. according to MM. 
 Gay Lussac and Thenard, is to that of air, 
 as 1.1912 to 1.0. From Sir II. Davy’s ex- 
 periments, it would appear to be a little less, 
 but he is inclined to adopt the results of the 
 French chemists, rather than his own, as 
 their gas was weighed in larger quantity, and 
 
SUL 
 
 SUL 
 
 dried. Notwithstanding this preference of 
 other experiments to his own, we must pre- 
 fer a number nearer to Sir H. Davy’s than 
 M. Gay Lussac’s. Its true sp. gr. is 1.1805. 
 K)0 cubic inches weigh 36.006 ; and it con- 
 sists ol 1 volume vapour of sulphur = 
 1.1 1 1 1 -j- i volume of hydrogen = 0.0694 
 = 1. 1 80 5 ; or a prime equivalent of each = 
 2.125. If platina wires be ignited in it, by 
 the voltaic apparatus, it is rapidly decom- 
 posed. Sulphur is deposited, and an equal 
 volume of hydrogen remains. The same 
 change is effected more slowly by the electric 
 sparks. 
 
 Of all the gases, sulphuretted hydrogen is 
 perhaps the most deleterious to animal life. 
 A greenfinch, plunged into air, which con- 
 tains only of its volume, perishes in- 
 
 stantly. A dog of middle size, is destroy- 
 ed in air that contains ; and a horse 
 would fall a victim to an atmosphere con* 
 
 tuning ^ jo* . 
 
 Dr Chaussicr proves, that to kill an ani- 
 mal, it is sufficient to make the sulphuretted 
 hydrogen gas act on the surface of its body, 
 when it is absorbed by the inhalants. He 
 took a bladder having a stop-cock at one 
 end, and at the other an opening, into 
 which he introduced the body of a rabbit, 
 leaving its bead outside, and securing the 
 bladder air-tight round the neck by adhesive 
 plaster. He then sucked the air out of the 
 bladder, and replaced it by sulphuretted hy- 
 drogen gas. A young animal in these cir- 
 cumstances, usually perishes in 15 or 20 
 minutes. Old rabbits resist the poison much 
 longer. 
 
 When potassium or sodium is heated, 
 merely to fusion, in contact with sulphuret- 
 ted hydrogen, it becomes luminous, and 
 burns with extrication of hydrogen, while a 
 metallic sulphuret remains, combined with 
 sulphuretted hydrogen, or a sulphuretted hy- 
 drosulphuret. 
 
 Sulphuretted hydrogen combines with an 
 equal volume of ammonia ; and unites to 
 alkalis and oxides, so that it has all the cha- 
 racters of an acid. These compounds are 
 called hydrosulphurets . 
 
 All the hydrosulphurets, soluble in water, 
 have an acrid and hitter taste, and when in 
 the liquid state, the odour of rotten eggs. 
 All those which are insoluble, are, on the 
 contrary, insipid and without smell. There 
 are only two coloured hydrosulphurets, that 
 of iron, which is black, and of antimony, 
 which is chesnut-brown. 
 
 All the hydrosulphurets are decomposed 
 by the action of fire. That of magnesia is 
 transformed into sulphuretted hydrogen and 
 oxide of magnesium ; those of potash and 
 soda, into sulphuretted hydrogen, hydrogen, 
 and sulphuretted alkalis; those of manga- 
 nese, zinc, iron, tin, and antimony, into wa- 
 ter and metallic sulphurets. 
 
 ^ hen we put in contact with the air, at 
 the ordinary temperature, an aqueous solu- 
 tion of a hydrosulphuret, there results, in 
 the space of some days, 1st, water, and a 
 sulphuretted hydrosulphuret, which is yel- 
 low and soluble ; 2d, water, and a colourless 
 hydrosulphite, which, if its base be potash, 
 soda, or ammonia, remains in solution in the 
 water ; but which falls down in acicular 
 crystals, if its base be barytes, strontia, or 
 lime. 
 
 The acids in general combine with the 
 base of the hydrosulphurets, and disengage 
 sulphuretted hydrogen with a lively effer- 
 vescence, wdthout any deposition of sulphur, 
 unless the acid be in excess, and he capable, 
 like the nitric and nitrous acid, of yielding a 
 portion of its oxygen to the hydrogen of the 
 sulphuretted hydrogen. 
 
 The hydrosulphurets of potash, soda, am- 
 monia, lime, and magnesia, are prepared di- 
 rectly, by transmitting an excess of sulphu- 
 retted hydrogen gas, through these bases, dis- 
 solved or diff used in water. 
 
 The composition of the hydrosulphurets is 
 such, that the hydrogen of the sulphuretted 
 hydrogen, is to the oxygen of the oxide in 
 the same ratio as in water. Hence, when 
 w hen we calcine the hydrosulphurets of iron, 
 tin, &c. we convert them into water and sul- 
 phurets. 
 
 Hydrosulphuret of potash crystallizes in 
 four-sided prisms, terminated by four-sided 
 pyramids. Its taste is acrid and bitter. Ex- 
 posed to the air, it attracts humidity, absorbs 
 oxygen, passes to the state of a sulphuretted 
 hydrosulphuret, and finally, to that of a hy- 
 drosulphite. It is extremely soluble in wa- 
 ter. Its solution on this liquid occasions a 
 perceptible refrigeration. Subjected to heat, 
 it evolves much sulphuretted hydrogen, and 
 the hydrosulphuret passes to the state of a 
 sub- hy drosulph uret. 
 
 Hydrosulphuret of soda crystallizes with 
 more difficulty than the preceding. 
 
 Hydrosulphuret of ammonia is obtained 
 by the direct union of the tw o gaseous con- 
 stituents in a glass balloon, at a low' tempe- 
 rature. As soon as the gases mingle, trans- 
 parent white or yellowish crystals are formed. 
 When a mere solution of this hydrosulphuret 
 is wished for medicine or analysis, we pass a 
 current of sulphuretted hydrogen through 
 aqueous ammonia till saturation. 
 
 The pure hydrosulphuret is white, trans- 
 parent, and crystallized in needles or fine 
 plates. It is very volatile. Hence, at ordi- 
 nary temperatures, it gradually sublimes into 
 the upper part of the phials in which we pre- 
 serve it. We may also by the same means 
 separate it from the yellow sulphuretted hy- 
 drosulphuret, with which it is occasionally 
 mixed. \\ lien exposed to the air, it absorbs 
 oxygen, passes to the state of a sulphuretted 
 hydrosulphuret, and becomes yellow. When 
 
SUL 
 
 SUM 
 
 it contains an excess of ammonia, it dissolves 
 speedily in water, with the production of a 
 very considerable cold. 
 
 Sub-hydrosulphuret of barytes is prepared 
 by dissolving, in five or six parts of boiling 
 water, the sulphuret of the earth obtained by 
 igniting the sulphate with charcoal. The 
 solution being filtered while hot, will deposit, 
 on cooling, a multitude of crystals, which 
 must be drained, and speedily dried by pres- 
 sure between the folds of blotting paper. 
 
 It crystallizes in white scaly plates. It is 
 much more soluble in hot than in cold wa- 
 ter. Its solution is colourless, and capable 
 of absorbing, at the ordinary temperature, a 
 very, large quantity of sulphuretted hydro- 
 gen. 
 
 Sub-hydrosulphuret of strontites crystallizes 
 in the same manner as the preceding. The 
 crystals obtained in the same way, must be 
 dissolved in water ; and the solution being 
 exposed to a stream of sulphuretted hydro- 
 gen, and then concentrated by evaporation 
 in a retort, will afford, on cooling, crystals of 
 pure sub-hydrosulphuret. 
 
 Hydrosulphurets of lime and magnesia 
 have been obtained only in aqueous solutions. 
 The metallic hydrosulphurets of any practi- 
 cal importance are treated of under their 
 respective metals. 
 
 When we expose sulphur to the action of 
 a solution of a hydrosulphurct, saturated with 
 sulphuretted hydrogen, so much more sul- 
 phuretted hydrogen is evolved, as the tem- 
 perature is more elevated. But when the 
 solution of hydrosulphuret, instead of being 
 saturated, has a sufficient excess of alkali, it 
 evolves no perceptible quantity of sulphu- 
 retted hydrogen, even at a boiling heat ; al- 
 though it dissolves as much sulphur as in its 
 state of saturation. It hence follows, 1st, 
 That sulphuretted hydrogen, sulphur, and 
 the alkalis, have the property of forming 
 very variable triple combinations ; ‘2d, That 
 all these combinations contain less sulphu- 
 retted hydrogen than the hydrosulphurets ; 
 and, 3d, That the quantity of sulphuretted 
 hydrogen is inversely as the sulphur they 
 contain, and reciprocally. These com- 
 pounds have been called, in general, sul- 
 phuretted hydrosulphurets ; but the name of 
 hydrogenated sulphurets is more particularly 
 given to those combinations which are satu- 
 rated with sulphur at a high temperature, be- 
 cause, by treating them with acids, we preci- 
 pitate a peculiar compound of sulphur and 
 hydrogen, of which we shall now treat. 
 
 This compound of hydrogen and sulphur, 
 the proportions of the elements of which 
 have not yet been accurately ascertained, is 
 also called hydruret of sulphur. It is formed 
 by putting flowers of sulphur in contact with 
 nascent sulphuretted hydrogen. With t his 
 view, we take an aqueous solution of the 
 hydrogenated sulphuret of potash, and pour 
 
 it gradually into liquid muriatic acid, which 
 seizes the potash, and forms a soluble salt, 
 whilst the sulphur and sulphuretted hydro- 
 gen unite, fall down together, collecting by 
 degrees at the bottom of the vessel, as a 
 dense oil does in water. To preserve this 
 hydruret of sulphur, we must rill with it a 
 phial having a ground stopper, cork it, and 
 keep it inverted in a cool place. W e may 
 consider this substance either as a combina- 
 tion of sulphur and hydrogen, or of sulphur 
 and sulphuretted hydrogen ; but its proper- 
 ties, and the mode of obtaining it, render 
 the latter the more probable opinion. 1 be 
 proportion of the constituents is not known. 
 
 The most interesting of the hydrogenated 
 sulphurets, is that of ammonia. It was dis- 
 covered by the Hon. Robert Boyle, and 
 called his fuming liquor. To prepare it, we 
 take one part of muriate of ammonia and 
 of pulverized quicklime, and ball a part ol 
 flowers of sulphur. After mixing them inti- 
 mately, we introduce the mixture into an 
 earthen or glass retort, taking care that none 
 of it remains in the neck. A dry cooled re- 
 ceiver is connected to the retort by means of 
 a long adopter-tube. The heat must be 
 urged slowly almost to redness. A yellow- 
 ish liquor condenses in the receiver, which is 
 to be put into a phial with its own weight of 
 flowers of sulphur, and agitated with it -seven 
 or eight minutes. The greater part of the 
 sulphur is dissolved, the colour of the mix- 
 ture deepens remarkably, and becomes thick, 
 constituting the hydrogenated sulphuret. 
 
 The distilled liquor diffuses, for a long 
 time, dense vapour in a jar full of oxygen or 
 common air; but scarcely any in azote or 
 hydrogen ; and the dryness or humidity of 
 the gases makes no difference in the effects. 
 It is probably owing to the oxygen convert- 
 ing the liquor into a hydrogenated sulphu- 
 ret, or perhaps to the state of sulphite, that 
 the vapours appear. 
 
 Hydrogenated sulphurets are frequently 
 called hydroguretted sulphurets. 
 
 Sulphur combines with carbon, forming 
 an interesting compound, to which the name 
 of sulphuret of carbon is sometimes given. 
 
 I have described it under the title Carburet 
 of Sulthur. For the combinations of sul- 
 phur and phosphorus, see the latter article. * 
 
 * Sulphuretted Chyazic Acid. Sec 
 Acid ( Sulpiiuro- Prussic). * 
 
 * Sulphuric Acid. See Acid (Sulphu- 
 ric).'* 
 
 * Sulphurous Acid. See Acid (Sul- 
 phurous).* 
 
 Sumach. Common sumach (rhus coria- 
 ria) is a shrub that grows naturally in Syria, 
 Palestine, Spain, and Portugal. In the two 
 last, it is cultivated with great care. Its 
 shoots are cut down every year quite to the 
 root ; and, after being dried, they are reduc- 
 ed to powder by a mill, and thus prepared 
 
SWE 
 
 SWE 
 
 for the purposes of dyeing and tanning. 
 The sumach cultivated in the neighbour- 
 hood of Montpellier, is called redoul , or 
 roudou. 
 
 Mr Hatchett found, that an ounce con- 
 tains about 78 or 79 grains of tannin. 
 
 Sumach acts on a solution of silver just as 
 galls do ; it reduces the silver to its metallic 
 state, and the reduction is favoured by the 
 action of light. 
 
 Of all astringents, sumach bears the great- 
 est resemblance to galls. The precipitate, 
 however, produced in solutions of iron by 
 an infusion of it, is less in quantity than 
 what is obtained by an equal weight of galls ; 
 so that in most cases it may be substituted 
 for galls, the price of which is considerable, 
 provided we proportionally increase its quan- 
 tity. 
 
 Sumach alone gives a fawn colour, inclin- 
 ing to green ; but cotton stuffs, which have 
 been impregnated with printer’s mordant, 
 that is, acetate of alumina, take a pretty 
 good and very durable yellow. An incon- 
 venience is experienced in employing su- 
 mach in this way, which arises from the 
 fixed nature of its colour ; the ground of 
 the stuff does not lose its colour by exposure 
 on the grass, so that it becomes necessary to 
 impregnate all the stuff with different mor- 
 dants, to vary the colours, without leaving 
 any part of it white. 
 
 Supersalt. A compound of an acid and 
 base, in which the acid is in excess. See 
 JSubsalt. 
 
 * Supersalts. Salts with excess of acid.* 
 
 * Surturbrand. Fibrous brown coal, or 
 bituminous wood, so called in Iceland, where 
 it occurs in great quantities. * 
 
 * Swamp Ore. Indurated bog iron ore.* 
 
 Sweat. When the temperature of the 
 
 body is much increased, either by being ex- 
 posed to a hot atmosphere, or by violent 
 exercise, the perspired vapour not only in- 
 creases in quantity, but even appears in a 
 liquid form. This is known by the name of 
 sweat. 
 
 Beside water, it cannot be doubted, that 
 carbon is also emitted from the skin ; but in 
 what state, the experiments hitherto made 
 do not enable us to decide. Mr Cruick- 
 shanks found, that the air of the glass vessel 
 in which his hand and foot had been confin- 
 ed for an hour, contained carbonic acid gas; 
 for a candle burned dimly in it, and it ren- 
 dered lime-water turbid. And Mr Jurine 
 found, that air which had remained for some 
 time in contact with the skin, consisted al- 
 most entirely of carbonic acid gas. The 
 same conclusion may be drawn from the ex- 
 periments of Ingenhousz and Milly. Trous- 
 set has lately observed, that air was separat- 
 ed copiously from a patient of his, while 
 bathing. 
 
 Beside water and carbon, or carbonic acid 
 gas, the skin emits also a particular odorous 
 
 substance. I hat every animal has a pecu- 
 liar smell, is well known : the dog can dis- 
 cover his master, and even trace him to a 
 distance, by the scent. A dog, chained up 
 several hours after his master had set out on 
 a journey of some hundred miles, followed 
 his footsteps by the smell. But it is need- 
 less to multiply instances of this fact ; they 
 are too well known to every one. Now this 
 smell must be owing to some peculiar mat- 
 ter, which is constantly emitted ; and this 
 matter must differ somewhat either in quan- 
 tity or some other property, as we see, that 
 the dog easily distinguishes the individual 
 by means of it. Mr Cruickshanks has made 
 it probable, that this matter is an oily sub- 
 stance ; or at least, that there is an oily sub- 
 stance emitted bv the skin. He wore re- 
 peatedly, night and day for a month, the 
 same under-waistcoat of fleecy hosiery, dur- 
 ing the hottest part of the summer. At the 
 end of this time he always found an oily 
 substance accumulated in considerable masses 
 on the nap of the inner surface of the waist- 
 coat, in the form of black tears. When rub- 
 bed on paper, it rendered it transparent, and 
 hardened on it like grease. It burned with 
 a white flame, and left behind it a charry re- 
 siduum. 
 
 Berthollet has observed the perspiration 
 acid ; and he has concluded, that the acid 
 which is present is the phosphoric ; but this 
 has not been proved. Fourcroy and Vau- 
 quelin have ascertained, that the scurf which 
 collects upon the skins of horses, consists 
 chiefly of phosphate of lime, and urea is even 
 sometimes mixed with it. 
 
 According to Thenard, however, who has 
 lately endeavoured more particularly to as- 
 certain this point, the acid contained in sweat 
 is the acetous ; which, he likewise observes, 
 is the only free acid contained in urine and 
 in milk, this acid existing in both of them 
 when quite fresh. 1 1 is account of his exa- 
 mination of it is as follows : 
 
 The sweat is more or less copious in dif- 
 ferent individuals ; and its quantity is per- 
 ceptibly in the inverse ratio of that of the 
 urine. All other circumstances being simi- 
 lar, much more is produced during diges- 
 tion, than during repose. The maximum of 
 its production appears to be twenty-six grains 
 and two-thirds in a minute, the minimum 
 nine grains, troy weight. It is much infe- 
 rior, however, to the pulmonary transpira- 
 tion ; and there is likewise a great difference 
 between their nature and manner ot forma- 
 tion. The one is a product ot a particular 
 secretion, similar in some sort to that ot the 
 urine ; the other, composed ot a great deal 
 of water and carbonic acid, is the product of 
 a combustion gradually effected by the atmos- 
 pheric air. 
 
 The sweat, in a healthy state, very sensi- 
 bly reddens litmus paper or intusion. In 
 certain diseases, and particularly in putrid 
 
TAL 
 
 TAN 
 
 fevers, it is alkaline ; yet its taste is always 
 rather saline, and more similar to that of 
 salt, than acid. Though colourless, it stains 
 linen. Its smell is peculiar, and insupport- 
 able when it is concentrated, which is the 
 case in particular during distillation. But 
 before he speaks of the trials to which he sub- 
 jected it, and of which he had occasion for 
 a great quantity, he describes the method he 
 adopted for procuring it, which was similar 
 to that of Mr Cruickshanks. 
 
 Human sweat, according to M. Thenard, 
 is formed of a great deal of water ; free 
 acetous acid ; muriate of soda ; an atom of 
 phosphate of lime, and oxide of iron ; and 
 an inappreciable quantity of animal matter, 
 which approaches much nearer to gelatine 
 than to any other substance. 
 
 * Swinestone. A variety of compact lu- 
 cullite, a sub-species of limestone.* 
 
 * HH ABULAR SPAR, or Table Scar. 
 
 JL The schaalstein of Werner, and 
 prismatic augite of Jameson. 
 
 Colour greyish-white. Massive, and in 
 angular-granular concretions. Shining pearly. 
 Cleavage double. Fracture splintery. Trans- 
 lucent. Harder than fluor spar, but not so 
 hard as apatite. Brittle. Sp. gr. 3.2 to 
 8.5. Its constituents are, silica 50, lime 
 45, water 5. — Klaproth. It occurs in pri- 
 mitive rocks, at Orawicza in the Bannat of 
 Temeswar, where it is associated with brown 
 garnets.* 
 
 * Tacamahac. A resin, having the aroma 
 of musk, and soluble in alcohol.* 
 
 * Talc. Of this mineral, Professor Ja- 
 meson’s sixth sub-species of rhomboidal mica, 
 there are two kinds; common talc, and in- 
 durated talc. 
 
 1 Common talc. Colour greenish- white. 
 Massive, disseminated, in plates, imitative, 
 and sometimes crystallized in small six-sided 
 tables, which are druses. Splendent, pearly, 
 semi-metallic. Cleavage single, with curved 
 folia. Translucent. Flexible, but not elas- 
 tic. Yields to the nail. Perfectly sectile. 
 Feels very greasy. Sp. gr. 2.77. It whitens, 
 and at length affords a small globule of ena- 
 mel, before the blow-pipe. Its constituents 
 are, silica 62, magnesia 27, alumina 1.5, 
 oxide of iron 3.5, water 6. — Vauquelin. 
 Klaproth found 2.75 of potash in 100 parts. 
 It occurs in beds in mica-slate and clay- 
 slate. It is found in Aberdeenshire, Banff- 
 shire, and Perthshire. The finest specimens 
 come from Saltzburg, the Tyrol, and St 
 Gothard. It is an ingredient in rouge for 
 the toilette, along with carmine and benzoin. 
 This cosmetic communicules a remarkable 
 
 Sylvanite. Native tellurium. 
 
 Sylvius (Salt of), or I*ebrifuge (Salt 
 of). Muriate of potash. 
 
 Synovia. Within the capsular ligament 
 of the different joints of the body, there is 
 contained a peculiar liquid, intended evi- 
 dently to lubricate the parts, and to facilitate 
 their motion. This liquid is known among 
 anatomists by the name of synovia . 
 
 From the analysis of M. Margueron, it 
 appears, that synovia is composed of the fol- 
 lowing ingredients : 
 
 11.86 fibrous matter 
 4.52 albumen 
 1.75 muriate of soda 
 .71 soda 
 
 .70 phosphate of lime 
 80.46 water 
 
 100.00 
 
 
 degree of softness to the skin, and is not in- 
 jurious. The flesh polish is given to gypsum 
 figures, by rubbing them with talc. 
 
 2. Indurated talc , or talc-slate . Colour 
 greenish-grey. Massive. Fragments tabu- 
 lar. Translucent on the edges. Soft. Streak 
 w r hite. Rather sectile. Easily frangible. 
 Not flexible. Feels greasy. Sp. gr. 2.7 to 
 2.8. It occurs in primitive mountains, w'here 
 it forms beds in clay-slate and serpentine. 
 It is found in Perthshire, Banffshire, the 
 Shetland Islands, and abundantly on the 
 Continent. It is employed for drawing 
 lines by carpenters, tailors, hat-makers, and 
 glaziers. — Jameson .* 
 
 * Talcite. Nacrite of Jameson, and 
 
 earthy talc of Werner. Colour greenish- 
 white. It consists of scaly parts. Glim- 
 mering, pearly. Friable. Feels very greasy. 
 Soils. It melts easily before the blow r -pipe. 
 Its constituents are, alumina 81.75, magne- 
 sia 0.75, lime 4, potash 0.5, w^ater 13.5. — 
 John . This is a very rare mineral, oc- 
 
 curring in veins, with sparry ironstone 
 and galena, in the mining district of Frey- 
 berg.* 
 
 * Tallow. Sec Fat.* 
 
 * Tamarinds. The pulp consists, ac- 
 cording to Vauquelin, of bitartrate of pot- 
 ash 500, gum 432, sugar 1 152, jelly 576, 
 citric acid 864, tartaric acid 144, malic acid 
 40, feculent matter 2880, water 3364 ; in 
 9752 parts.* 
 
 Tannin. This, which is one of the im- 
 mediate principles of vegetables, w\as first 
 distinguished by Seguin from the gallic acid, 
 with which it had been confounded under 
 the name of the astringent principle . He 
 gave it the name of tannin, from its use in 
 
TAN 
 
 TAN 
 
 the tanning of leather ; which it effects by 
 its characteristic property, that of forming 
 with gelatin a tough insoluble matter. 
 
 It may be obtained from vegetables by 
 macerating them in cold M ater ; and preci- 
 pitated from this solution, which contains 
 likeM'ise gallic acid and extractive matter, 
 by hyperoxygenized muriate of tin. From 
 this precipitate, immediately diffused in a 
 large quantity of water, the oxide of tin may 
 be separated by sulphuretted hydrogen gas, 
 leaving the tannin in solution. 
 
 Professor Proust has' since recommended 
 another method, the precipitation of a decoc- 
 tion ot galls by powdered carbonate of pot- 
 ash, washing well the greenish-grey flakes 
 that fall down, with cold Mater, and drying 
 
 # ' r O 
 
 them in a stove. The precipitate grows 
 brown in the air, becomes brittle and shin- 
 ing like a resin, and yet remains soluble in 
 hot water. The tannin in this state, he says, 
 is very pure. 
 
 Sir II. Davy, after making several ex- 
 periments on different methods of ascertain- 
 ing the quantity of tannin in astringent in- 
 fusions, prefers for this purpose, the com- 
 mon process of precipitating the tannin by 
 gelatin ; but he remarks, that the tannin 
 of different vegetables requires different pro- 
 portions of gelatin for its saturation ; and 
 that the quantity of precipitate obtained is 
 influenced by the degree in which the solu- 
 tions are concentrated. 
 
 M. Chenevix observed, that coffee berries 
 acquired by roasting the property of precipi- 
 tating gelatin ; and Mr Hatchett has made 
 a number of experiments, which shoM r , that 
 an artificial tannin, or substance having its 
 chief property, may be formed, by treating 
 with nitric acid matters containing charcoal. 
 It is remarkable that this tannin, when pre- 
 pared from vegetable substances, as dry 
 charcoal of wood, yields, on combustion, pro- 
 ducts analogous to those of animal matters. 
 From his experiments it would seem, that 
 tannin is, in reality, carbonaceous matter 
 combined witli oxygen ; and the difference 
 in the proportion of oxygen may occasion 
 the differences in the tannin procured from 
 different substances, that from catechu ap- 
 pearing to contain most. 
 
 Bouillon Lagrange asserts, that tannin 
 by absorbing oxygen is converted into gallic 
 acid. 
 
 It is not an unfrequent practice, to admi- 
 nister medicines containing tannin in cases 
 of debility, and at the same time to prescribe 
 gelatinous food as nutritious. But this is 
 evidently improper, as the tannin, from its 
 chemical properties, must render the gela- 
 tin indigestible. For the chief use of tan- 
 nin, see the following article. 
 
 * According to Berzelius, tannin consists 
 of hydrogen 4.186 -}- carbon 51.160 -f- 
 oxygen 44.654. And the tannate ot lead 
 
 is composed of, 
 
 tannin, 100 26.923 
 
 oxide of lead, 52 14 . 
 
 But there is much uncertainty concerning 
 the definite neutrality of this compound.* 
 
 Tanning. The several kinds of leather 
 are prepared from the skins of animals ma- 
 cerated for a long time with lime and water, 
 to promote the separation of the hair and 
 wool, and of the fat and fleshy parts, in 
 which recourse is also had to the assistance 
 of mechanical pressure, scraping, and the 
 like. The skin, when thus deprived of its 
 more putrescible part, and brought consi- 
 derably toward the state of mere fibre, is 
 tanned by maceration with certain astrin- 
 gent substances, particularly the bark of the 
 oak-tree. 
 
 The hide consists almost M'holly of gela- 
 tin, and all that is necessary is, to divest it 
 of the hair, epidermis, and any flesh or fat 
 adhering to it. This is commonly done, 
 after they have been soaked in water some 
 time, and handled or trodden to cleanse 
 them from filth, by immersing them in 
 milk of lime. Some, instead of lime, use 
 an acescent infusion of barley or rye-meal, 
 or spent tan ; and others recommend M ater 
 acidulated udth sulphuric acid. Similar 
 acidulous Maters are aftemard employed 
 for raising or sM'elling the hide, M’hen this is 
 necessary. 
 
 The skins thus prepared, are finally to 
 undergo what is properly called the tanning. 
 This is usually done by throwing into a pit, 
 or cistern made in the ground, a quantity of 
 ground oak-bark, that has already been used, 
 and on this the skins and fresh bark in alter- 
 nate layers, covering the whole with half a 
 foot of tan, and treading it well down. The 
 tanning may be accelerated by adding a little 
 water. 
 
 As it is a long time before the hide is 
 thoroughly tanned in this mode, at least 
 many months, during which the bark is re- 
 newed three or four times ; M. Seguin 
 steeps the skins in a strong infusion of tan, 
 and assists its action by heat. Chaptal ob- 
 serves, hoM-ever, that this requires an exten- 
 sive apparatus, for preparing the liquor, and 
 the skins : the leather imbibes so much wa- 
 ter, that it remains spongy a long time, and 
 wrinkles in drying ; and it is extremely dif- 
 ficult so to arrange the hides in a copper, as 
 to keep them apart from each other, and free 
 of the sides of the vessel. 
 
 The following account of M. Seguin s 
 practice, was transmitted to England in the 
 year 1796: — 
 
 To tan a skin is to take away its putres- 
 cent quality, preserving however, a certain 
 degree of pliability. This is effected by in- 
 corporating M'ith the skin particles of a sub- 
 stance, which destroys their tendency to pu- 
 trefaction. 
 
TAN 
 
 TAN 
 
 The operations relating to tanning are 
 therefore of two kinds: — the lirst is merely 
 depriving the skin of those parts, which 
 would oppose its preservation, or which ad- 
 here to it but little, such as hair and flesh; 
 the other consists in incorporating with it a 
 substance, which shall prevent its putrefy- 
 ing. 
 
 The operations of the first kind are tech- 
 nically termed, unhairing and fleshing; the 
 operations of the second kind belong to tan- 
 ning, properly so called. 
 
 Fleshing is an operation merely mechani- 
 cal : unhairing is a mechanical operation if 
 performed by shaving; or a chemical opera- 
 tion, if effected by dissolution or decomposi- 
 tion of the substance, which connects the 
 hah* with the skin. 
 
 According to the ancient method, the dis- 
 solution of this substance was effected by 
 means of lime; the decomposition either by 
 the vinous fermentation of barley, by the 
 acetous fermentation of oak-bark, or by the 
 putrid fermentation produced by piling the 
 hides one upon another. 
 
 Unhairing by means of lime would often 
 take twelve or fifteen months ; this operation 
 with barley, or the acetous part of tan, 
 could not be performed in less than two 
 months. 
 
 The slowness of these operations, which 
 the experiments of Seguin have shown may 
 be finished in a few days, and in a more ad- 
 vantageous manner, by means of the same 
 substances, proves, that the nature of those 
 operations was not understood by those who 
 performed them. Those of tanning, proper- 
 ly so called, were as little known, as the de- 
 tails we are about giving will prove, which 
 w© compare with the least improved routine 
 now in practice. 
 
 Whatever the method of unhairing was, 
 the mode of tanning was always the same, 
 for skins unhaired with lime, or those pre- 
 pared with barley or tan. 
 
 This mode of operating would take 
 eighteen months or two years, often three 
 years, when it was wished to tan the hides 
 thoroughly. 
 
 Among the substances for tanning, gall- 
 nut, sumach, and the bark of oak, to which 
 may be added catechu, appear the most pro- 
 per, at least, in the present state of our 
 knowledge. In the middle departments of 
 France, oak-bark is preferred, because it is 
 the cheapest and most abundant substance. 
 To use it, it is first ground to powder ; then, 
 according to the old mode, it is put into 
 large holes dug in the ground, which are fill- 
 ed by alternate layers of ground bark and 
 unhaired hides. 
 
 As the principle which effects the tan- 
 ning cannot act in the interior of the skin, 
 unless carried in by some liquid in which it 
 is first dissolved, tanning is not produced 
 
 by the immediate action of the powdered 
 bark upon the skin, but only by the action 
 of the dissolution of the tanning principle 
 originally contained in the bark. The tan 
 therefore has the tanning property only 
 when wetted so much as not to absorb all 
 the water thrown on it. But as tanners put 
 in their vats only a small portion of w ater 
 compared to what would be necessary to 
 deprive the bark of all the tanning principle 
 which it contains, the bark put into the vats 
 preserves, when taken out, a portion of its 
 tanning principle. 
 
 This waste is not the only disadvantage 
 of the old modes of proceeding ; they are, be- 
 sides, liable never to produce in the skins a 
 complete saturation with the tanning prin- 
 ciple. For, as the property of attraction is 
 common to all bodies, according to the dif- 
 ferent degree of saturation, the water con- 
 taining in solution a certain quantity of the 
 tanning principle, will not part, to a fixed 
 weight of skins, with as much as the same 
 quantity of water will, in which a greater 
 quantity of the principle is dissolved. 
 
 As the water, which, in the old manner 
 of proceeding, is in the vats, can contain but 
 a small portion of the tanning principle, ow- 
 ing to the nature of the operation, it can give 
 but a small portion of it to the skin, and 
 even this it parts with by slow degrees. 
 Hence, the slowness in the tanning of skins 
 according to the old method, which required 
 two whole years, and sometimes three, be- 
 fore a skin was well tanned to the centre. 
 Hence also, the imperfection of skins tanned 
 by that method; an imperfection resulting 
 from the non-saturation of the tanning prin- 
 ciple, even when it had penetrated the cen- 
 tre. 
 
 The important desideratum was, therefore, 
 to get together, within a small compass, the 
 tanning principle, to increase its action, and 
 produce in the hide a complete saturation in 
 a much shorter time than that necessary for 
 the incomplete tanning produced in vats. 
 But, first of all, it was necessary to analyze 
 the skin, analyze the leather, and analyze the 
 oak-bark. The principles of these three 
 substances were to be insulated, and their 
 action upon one another determined, the in- 
 fluence of their combination upon that ac- 
 tion known, and the circumstances most 
 productive of its greatest action found out. 
 
 Seguin, by following this method, has de- 
 termined : — 
 
 1. That the skin deprived of flesh and 
 hair is a substance, which can easily, by a 
 proper process, be entirely converted into an 
 animal jelly (glue). 
 
 2 . That a solution of this last mentioned 
 substance, mixed with a solution of tan, 
 forms immediately an imputresciblc and in- 
 dissoluble compound. 
 
 *-'• I fiat the solution of tan is composed 
 
TAN 
 
 TAR 
 
 of two very distinct substances; one of 
 which precipitates the solution of glue, and 
 which is the true tanning substance ; the 
 other, which precipitates sulphate of iron, 
 without precipitating the solution of glue, 
 and which produces only the necessary dis- 
 oxygenation of the skin, and of the substance 
 which connects the hair to the skin. 
 
 4. That the operation of tanning is not 
 a simple combination of the skin with the 
 principle which precipitates the glue, but 
 a combination of that principle with the 
 skin disoxygenized by the substance, which 
 in the dissolution of tan is found to preci- 
 pitate the sulphate of iron ; so that every 
 substance proper for tanning should possess 
 the properties of precipitating the solution 
 of glue, and of precipitating the sulphate of 
 iron. 
 
 5. That the operation of tanning consists 
 in swelling the skins by means of an acidu- 
 lous principle; to disoxygenize, by means 
 of the principle which in the solution of 
 bark precipitates the solution of sulphate of 
 iron, that substance which connects the hair 
 to the skin, and thus produce an easy un- 
 hairing; to disoxygenize the skin by means 
 of the same principle, and to bring it by 
 this disoxvgenation to the middle state be- 
 tween glue and skin ; and then to combine 
 with it, after this disoxygenation, and while 
 it is in this middle state, that particular sub- 
 stance in oak-bark, as well as in many other 
 vegetables, which is found to precipitate the 
 solution of glue, and which is not, as has 
 been hitherto conceived, an astringent sub- 
 stance. 
 
 Agreeably to these discoveries, there only 
 remains, in order to tan speedily and com- 
 pletely, to condense the tanning principle 
 so as to accelerate its action. Seguin, to 
 effect this, follows a very simple process. 
 He pours water upon the powdered tan, 
 contained in an apparatus nearly similar to 
 that made use of in saltpetre works. This 
 water, bv going through the tan, takes from 
 it a portion of its tanning principle, and by 
 successive filtrations dissolves every time an 
 additional quantity of it, till at last the bark 
 rather tends to deprive it of some than to 
 give up more. Seguin succeeds in bringing 
 these solutions to such a degree of strength, 
 that, he says, he can, by taking proper mea- 
 sure, tan calf-skin in 24 hours, and the 
 strongest ox-hides in seven or eight days. 
 These solutions containing a great quantity 
 of the tanning principle, impart to the skin 
 as much of it as it can absorb, so that it can 
 then easily attain a complete saturation of 
 the principle, and produce leather of a quality 
 much superior to that of most countries fa- 
 mous for their leather. 
 
 On the above I have only to remark, that 
 every new art or considerable improvement 
 must unavoidably be attended with many 
 
 difficulties in the establishment of a manu- 
 factory in the large way. From private in- 
 quiry I find, that this also has its difficulties, 
 which have hitherto prevented its being car- 
 ried into full effect in this country. Of 
 what nature these may be I am not decided- 
 ly informed, and mention them in this place 
 only to prevent manufacturers from engag- 
 ing in an undertaking of this kind, without 
 cautious inquiry. 
 
 M. Desmond has recommended, to sa- 
 turate water with tannin, by affusion on suc- 
 cessive portions of oak-bark, or whatever 
 may be used ; and when the bark will give 
 out no more tannin, to extract what gallic 
 acid still remains in it, by pouring on fresh 
 water. To the latter, or acidulous liquor, 
 he adds one-thousandth part by measure of 
 sulphuric acid ; and in this steeps the hide, 
 till the hair will come oil* easily by scraping. 
 When raising is necessary, he steeps the hide 
 ten or twelve hours in water acidulated with 
 a five-hundredth part by measure of sul- 
 phuric acid ; after which they are to be 
 washed repeatedly, and scraped with the 
 round knife. Lastly, the hides are to be 
 steeped some hours in a weak solution of 
 tannin, then a few days in a stronger, and 
 this must be renewed as the tannin is ex- 
 hausted, till the leather is fully tanned. 
 
 For the softer skins, as calves, goats, &c. 
 he does not use the acid mixture, but milk 
 of lime. 
 
 Of substances used for tanning Sir H. Davy 
 observes, that 1 lb. of catechu is nearly equal 
 to of galls, 5 of sumach, 7-§ of the bark 
 of the Leicester willow, 8^ of oak-bark, 1 1 
 of the bark of the Spanish chesnut, 18 of 
 elm-bark, and 21 of common willow- bark, 
 with respect to the tannin contained in them. 
 Fie observes too, that leather slowly tanned 
 in weak infusions of barks appears to be 
 better in quality, being both softer and 
 stronger than when tanned by strong infu- 
 sions ; and he ascribes this to the extractive 
 matter they imbibe. T his principle, there- 
 fore, affects the quality of the material em- 
 ployed in tanning ; and galls, which contain 
 a great deal of tannin, make a hard leather, 
 and liable to crack, from their deficiency of 
 extractive matter. — Ann. de Chim. — Philos. 
 Trans. — Philos. Mag. — ChaptaVs Chem. 
 
 * Tantalum Ore. See Ore of Tan- 
 talum. * 
 
 * Tantalum. The metal already treat- 
 ed off under the name Columbium.* 
 
 Tarras, or Terras. A volcanic earth 
 used as a cement. It does not differ much 
 in its principles from pouzzolana ; but it is 
 much more compact, hard, porous, and 
 spongy. It is generally of a whitish-yellow 
 colour, and contains more heterogeneous 
 particles, as spar, quartz, schoerl, &c. and 
 something more of a calcareous earth. It 
 effervesces with acids, is magnetic, and lusi- 
 
TAR 
 
 TEL 
 
 ble per se. When pulverized, it serves as 
 a cement, like pouzzolana. It is found in 
 Germany and Sweden. See Lime. 
 
 * Tartar. See Acid (Tartaric).* 
 
 Tartar is deposited on the sides of casks 
 during the fermentation of wine : it forms 
 a lining more or less thick, which is scraped 
 off. This is called crude tartar, and is sold in 
 Languedoc from 10 to 15 livres the quintal. 
 
 All wines do not afford the same quantity 
 of tartar. Neumann remarked, that the 
 LIungarian wines left only a thin stratum ; 
 that the wines of France afforded more ; and 
 that the Ii-henish wines afforded the purest 
 and the greatest quantity. 
 
 Tartar is distinguished from its colour 
 into red and white : the first is afforded by 
 red wine. 
 
 4 
 
 Tartar is purified from an abundant ex- 
 tractive principle, by processes which are 
 executed at Montpellier and at Venice. 
 
 The following is the process used at 
 Montpellier: — The tartar is dissolved in 
 water, and suffered to crystallize by cooling. 
 The crystals are then boiled in another ves- 
 sel, with the addition of five or six pounds 
 of the white argillaceous earth of Murviel to 
 each quintal of the salt. After this boiling 
 with the earth, a very white salt is obtained 
 by evaporation, which is known by the name 
 of cream of tartar, or the acidulous tartrate 
 of potash. 
 
 M. Desmaretz has informed us, that the 
 process used at Venice consists, 
 
 1. In drying the tartar in iron boilers. 
 
 2. Pounding it, and dissolving it in hot 
 w r ater, which, by cooling, affords purer crys- 
 tals. 
 
 5. Redissolving these crystals in water, 
 and clarifying the solution by whites of eggs 
 and ashes. 
 
 The process of Montpellier is preferable 
 to that of Venice. The addition of the ashes 
 introduces a foreign salt, w'hicli alters the 
 purity of the product. See Acid (Tartar- 
 ic). 
 
 Tartar (Chalybeated). This is pre- 
 pared by boiling three parts of the super- 
 tartrate of potash and two of iron tilings in 
 forty-six parts of water, till the tartar appears 
 to be dissolved. The liquor is then filtered, 
 and crystals are deposited on cooling, more 
 of which are obtained by continuing the eva- 
 poration. 
 
 Tartar (Cream of). The popular name 
 of the purified supertartrate of potash. 
 
 Tartar (Crude). The supertartrate of 
 potash in its natural state, before it has been 
 purified. 
 
 Tartar (Emetic). The tartrate of potash 
 and antimony. See Antimony. 
 
 Tartar of the teeth. The popular 
 name for the concretion that so frequently 
 incrusts the teeth, and which consists ap- 
 parently of phosphate of lime. 
 
 Tartar (Regenerated). Acetate of pot- 
 ash. 
 
 Tartar (Salt of). The subcarbonate 
 of potash. 
 
 Tartar (Secret Foliated Earth of). 
 Acetate of potash. 
 
 Tartar (Soluble). Neutral tartrate of 
 potash. 
 
 Tartar ( Vitriolated). Sulphate of pot- 
 ash. 
 
 Tartarine. The name given by Kirwan 
 to the vegetable alkali, or potash. 
 
 Tartarous Acid. See Acid (Tartaric). 
 
 Tartrate. A neutral compound of the 
 tartaric acid with a base. 
 
 Tears. That peculiar fluid which is em- 
 ployed in lubricating the eye, and which is 
 emitted in considerable quantities when we 
 express grief by weeping, is known by the 
 name of tears. For an accurate analysis of 
 this fluid we are indebted to Messrs Four- 
 croy and Vauquelin. 
 
 The liquid called tears is transparent and 
 colourless like water ; it has scarcely any 
 smell, but its taste is always perceptibly 
 salt. Its specific gravity is somewhat great- 
 er than that of distilled w r ater. It gives to 
 paper stained with the juice of the petals 
 of mallow-s or violets a permanently green 
 colour, and therefore contains a fixed alkali. 
 It unites with wrater, whether cold or hot, in 
 all proportions. Alkalis unite with it rea- 
 dily, and render it more fluid. The mineral 
 acids produce no apparent change upon it. 
 Exposed to the air, this liquid gradually 
 evaporates, and becomes thicker. When 
 nearly reduced to a state of dryness, a num- 
 ber of cubic crystals form in the midst of a 
 kind of mucilage. These crystals possess 
 the properties of muriate of soda ; but they 
 tinge vegetable blues green, and therefore 
 contain an excess of soda. The mucilaginous 
 matter acquires a yellowish colour as it dries. 
 
 Tears are composed of the following in- 
 gredients : — 
 
 1. Water, 
 
 2. Mucus, 
 
 3. Muriate of soda, 
 
 4. Seda, 
 
 5. Phosphate of lime, 
 
 6. Phosphate of soda. 
 
 The saline parts amount only to about 
 0.01 of the whole, or probably not so much. 
 
 Teeth. The basis of the substance that 
 forms the teeth, like that of other bones, 
 (see Bone), appears to be phosphate of lime. 
 The enamel, however, according to Mr 
 Hatchett, differs from other bony substances 
 in being destitute of cartilage : for raspings 
 of enamel, when macerated in diluted acicfs, 
 he found were wholly dissolved ; while rasp- 
 ings of bone, treated in the same manner, 
 always left a cartilaginous substance uu« 
 touched. See Bone. 
 
 * Telesia. Sapphire.* 
 
TEL 
 
 TEM 
 
 Tellurium. Mueller first suspected the 
 existence of a new metal in the aurum para- 
 doxicum, or problematicum, which has the 
 appearance of an ore of gold, though very 
 little can be extracted from it. Klaproth 
 afterward established its existence, not only 
 in this but in some other Transylvanian ores, 
 and named it tellurium. 
 
 Pure tellurium is of a tin-white colour, 
 verging to lead-grey, with a high metallic 
 lustre ; of a foliated fracture ; and very 
 brittle, so as to be easily pulverized. Its 
 sp.gr. is 6.115. It melts before ignition, 
 requiring a little higher heat than lead, and 
 less than antimony ; and, according to Gme- 
 lin, is as volatile as arsenic. When cooled 
 without agitation, its surface has a crystal- 
 lized appearance. Before the blow-pipe on 
 charcoal it burns with a vivid blue light, 
 greenish on the edges ; and is dissipated 
 in greyish- white vapours, of a pungent 
 smell, which condense into a white oxide. 
 This oxide heated on charcoal is reduced 
 with a kind of explosion, and soon again 
 volatilized. Ileated in a glass retort it fuses 
 into a straw-coloured striated mass. It ap- 
 pears to contain about 16 per cent of oxygen. 
 
 Tellurium is oxidized and dissolved by 
 the principal acids. To sulphuric acid it 
 gives a deep purple colour. Water sepa- 
 rates it in black fiocculi, and heat throws 
 it down in a white precipitate. 
 
 With nitric acid it forms a colourless so- 
 lution, which remains so when diluted, and 
 affords slender dendritic crystals by evapo- 
 ration. 
 
 The muriatic acid, with a small portion 
 of nitric, forms a transparent solution, from 
 which water throws down a white submu- 
 riate. This may be redissolved almost 
 wholly by repeated affusions of water. Al- 
 cohol likewise precipitates it. 
 
 Sulphuric acid, diluted with two or three 
 parts of water, to which a little nitric acid 
 lias been added, dissolves a large portion of 
 the metal, and the solution is not decom- 
 posed by water. 
 
 The alkalis throw down from its solutions 
 a white precipitate, which is soluble in all 
 the acids, and by an excess of the alkalis or 
 their carbonates. They are not precipitated 
 by prussiate of potash. Tincture of galls 
 gives a yellow flocculent precipitate with 
 them. Tellurium is precipitated from them 
 in a metallic state by zinc, iron, tin, and 
 antimony. 
 
 Tellurium fused with an equal weight of 
 sulphur, in a gentle heat, forms a lead-co- 
 loured striated sulphuret. Alkaline sul- 
 phurets precipitate it from its solutions of a 
 brown or black colour. In this precipitate 
 either the metal or its oxide is combined 
 with sulphur. Each of these sulphurets 
 burns with a pale blue flame, and white 
 smoke. Ileated in a retort, part of the sul- 
 
 phur is sublimed, carrying up a little of the 
 metal with it. It does not easily amalga- 
 mate with quicksilver. 
 
 * Telluretted Hydrogen. Tellurium 
 and hydrogen combine to form a gas, called 
 telluretted hydrogen. To make this com- 
 pound, hydrate of potash, and oxide of tel- 
 lurium, are ignited with charcoal, and the 
 mixture acted on by dilute sulphuric acid, 
 in a retort connected with a mercurial pneu- 
 matic apparatus. An elastic fluid is gene- 
 rated, consisting of hydrogen holding tellu- 
 rium in solution. It is possessed of very 
 singular properties. It is soluble in water, 
 and forms a claret-coloured solution. It 
 combines with the alkalis. It burns with a 
 bluish flame, depositing oxide of tellurium. 
 Its smell is very strong and peculiar, not 
 unlike that of sulphuretted hydrogen. This 
 elastic fluid was discovered by Sir II. Davy 
 in 1809. When tellurium is made the elec- 
 trical negative surface in water in the voltaic 
 circuit, a brown powder is formed, which 
 appears to be a solid combination of hydro- 
 gen and tellurium. It was first observed 
 by Mr Ritter in 1808. The composition 
 of the gas and the solid hydruret has not 
 been ascertained. The prime equivalent of 
 tellurium, according to Sir Ii. Davy, is 4.93, 
 reduced to the oxygen radix. Berzelius 
 makes the oxide of tellurium a compound 
 of metal 100 oxygen 24.8. If we call 
 the oxygen 25, then the atom or prime 
 would be 4. In this case, telluretted hy- 
 drogen, if analogous in its constitution to 
 sulphuretted hydrogen, would have a sp. gr. 
 of 2.2916, (not 2.3074, as Dr Thomson 
 deduces it from the very same data).* 
 
 * Temperature. A definite term of 
 sensible heat, as measured by the thermo- 
 meter. Thus we say ,a high temperature, 
 and a low temperature, to denote a manifest 
 intensity of heat or cold; the temperature 
 of boiling water, or 212° Fahr. ; and a 
 range of temperature, to designate the inter- 
 mediate points of heat between two distant 
 terms of thermometric indication. Accord- 
 ing to M. Biot, temperatures are the diffe- 
 rent energies of caloric, in different circum- 
 stances. 
 
 The general doctrines of caloric have 
 been already fully treated of under the arti- 
 cles Caloric, Combustion, Congelation , Cli- 
 mate, and Pyrometer. 
 
 The changes induced on matter, at diffe- 
 rent temperatures, relate either to its mag- 
 nitude, form, or composition. The first two 
 of these effects are considered under Expan- 
 sion, Concreting Temperatures, and Pyrome- 
 ter ; the third under Combustion , and the 
 Individual Chemical Bodies. 1 shall here 
 introduce some facts concerning the tempera- 
 ture of living bodies, and that of our north- 
 ern climates, as modified by the constitution 
 of water. 
 
TEM 
 
 THE 
 
 The power which man possesses of resist- 
 ing the impression of external cold is well 
 known, and fully exemplified in high latitudes. 
 That of sustaining high heats has been made 
 the subject of experiment. On the Conti- 
 nent, the girls who are sent into ovens often 
 endure for a short period a heat of 300° F. 
 and upwards. If the skin be covered with 
 varnish, which obstructs the perspiration, 
 such heats, however, become intolerable. 
 Or Fordyce staid for a considerable time, 
 and without great inconvenience, in a room 
 heated by stoves to 260° of Fahrenheit’s 
 scale. The lock of the door, his watch and 
 keys, lying on the table, could not be touch- 
 ed without burning his hand. An egg be- 
 came hard ; and though his pulse beat 159 
 times per minute, yet a thermometer held in 
 his mouth was only 2° or 3° hotter than 
 ordinary. He perspired most profusely. — 
 Phil. Trans, vol. 64, and 65. 
 
 It has been shewn under Caloric , that fresh 
 water possesses a maximum density about 
 39^° F. When its temperature deviates 
 from this point, either upwards or down- 
 wards, its density diminishes, or its volume 
 enlarges. Hence, when the intensely cold 
 air from the circumpolar regions, presses 
 southwards, after the autumnal equinox, it 
 progressively abstracts the heat from the 
 great natural basins of water or lakes, till the 
 temperature of the whole aqueous mass sinks 
 to 39^°. At this term, the refrigerating in- 
 fluence of the atmosphere incumbent on the 
 water, becomes nearly null. For, as the 
 superficial stratum, by farther cooling, be- 
 comes specifically lighter, it remains on the 
 surface, and soon becomes a cake of ice, 
 which being an imperfect conductor of heat, 
 scieens the subjacent liquid water from the 
 cold air. Had water resembled mercury, 
 oils, and other liquids, in continuing to con- 
 tract in volume, by cooling, till its congela- 
 tion commenced, then the incumbent cold 
 aii would have robbed the mass of water in 
 a lake, of its caloric of fluidity, by unceasing 
 precipitation of the cold particles to the bot- 
 tom, till the whole sunk to 32°. Then the 
 water at the bottom, as well as that above, 
 would have begun to solidify, and in the 
 course of a severe winter in these latitudes, 
 a deep lake would have become throughout a 
 body of ice, never again to be liquefied. We 
 can easily see, that such frozen masses would 
 have acted as centres of baleful refrigeration 
 to the surrounding country ; and that under 
 such a disposition of things, Great Britain 
 must have been another Lapland. Nothing 
 illustrates more strikingly the beneficent 
 economy of Providence, than this peculiarity 
 in the constitution of water, or anomaly, as it 
 has been rather preposterously termed. What, 
 seems void of law to short-sighted man, is 
 often, as in the present case, the finest sym- 
 metry, and truest order.* 
 
 a<5 
 
 * Tenacity. See Cohesion.* 
 
 * Tennantite. Colour, from lead-grey 
 to iron-black. Massive, but usually crystal- 
 lized, in rhomboidal dodecahedrons, cubes, or 
 octohedrons. Splendent, and tin-white; oc- 
 casionally dull. Cleavage dodecahedral. 
 Streak reddish-grey. Rather harder than 
 grey copper. Brittle. Sp. gr. 4.375. It 
 yields a blue flame, followed by arsenical 
 vapours ; and leaves a magnetical scoria. 
 Its constituents are, copper 45.32, sulphur 
 28.74, arsenic 11.84, iron 9.26, silica 5. — 
 Richard Phillips. It occurs in Cornwall in 
 copper veins that intersect granite, and clay- 
 slate, associated with common copper pyrites. 
 It is a variety of grey copper.* 
 
 * Terra Ponderosa. See Heavy Spar 
 and Barytes.* 
 
 Terra Japonica. Catechu. 
 
 Terra Lemnia. A red bolar earth for- 
 merly esteemed in'medicine. See Lemnian 
 Earth. 
 
 Terra Sienna. A brown bole, or ochre, 
 with an orange cast, brought from Sienna in 
 Italy, and used in painting, botli raw and 
 burnt. W hen burnt it becomes of a darker 
 brown. It resists the fire a long time with- 
 out fusing. It adheres to the tongue very 
 forcibly. 
 
 Terre Verte. This is used as a pig- 
 ment, and contains iron in some unknown 
 state, mixed with clay, and sometimes with 
 chalk and pyrites. 
 
 * Thallite. Epidote or Pistacite.* 
 
 * Thermometer. An instrument for 
 measuring heat, founded on the principle, 
 that the expansions of matter are proportional 
 to the augmentations of temperature. With 
 regard to aeriform bodies, this principle is 
 probably well founded ; and, hence, our 
 common thermometers may he rendered just, 
 by reducing their indications to those of an 
 air thermometer. Solids, and still more 
 liquids, expand unequally, bv equal incre- 
 ments of heat, or intervals of temperature. 
 With regard to water, alcohol, and oils, tin's 
 inequality is so considerable as to occasion 
 their rejection, for purposes of exact thermo- 
 
 approaches more to metals than ordinary 
 liquids, in its rate of expansion, and hcncc, 
 as well as from its remaining liquid, through 
 a long range of temperature, it is justly pre- 
 ferred to the above substances for thermo- 
 metric purposes. A common thermometer, 
 therefore, is merely a vessel in which very 
 minute expansions of mercury may be render- 
 ed perceptible; and, by certain rules of gra- 
 duation, be compared with expansions made 
 on the same liquid, by other observers The 
 first condition is fulfilled, by connecting a 
 narrow glass tube with a bulb of consider- 
 able capacity, filled with quicksilver. As 
 tins fluid metal expands l-63d by being heat- 
 ed in glass vessels, from the melting point of 
 
tiie 
 
 THE 
 
 ice to the boiling point of water, if 1 0 inches 
 of the tube have a capacity equal to l-63d 
 of that of the bulb, it is evident that, should 
 the liquid stand at the beginning of the tube, 
 at 32°, it will rise up and occupy 10 inches 
 of it, at 212°. Hence, if the tube be uni- 
 form in its calibre, and the above space be 
 divided into equal parts, by an attached scale, 
 then we shall have a centigrade or Fahren- 
 heit’s thermometer, according as the divisions 
 are 100 or 180 in number. Such are the 
 general principles of thermometric construc- 
 tion. But to make an exact instrument, 
 more minute investigation is required. 
 
 The tubes drawn at glass-houses for mak- 
 ing thermometers, are all more or less irre- 
 gular in the bore, and for the most part coni- 
 cal. Hence, if equal apparent expansions of 
 the included mercury, be taken to represent 
 equal thermometric intervals, these equal ex- 
 pansions will occupy unequal spaces in an 
 irregular tube. The attached scale should 
 therefore correspond exactly to these tubular 
 inequalities ; or if the scale be uniform in its 
 divisions, we must be certain that the tube is 
 absolutely uniform in its calibre. I may 
 join the authority of Mr Troughton’s opi- 
 nion to my own, for affirming, that a tube of 
 a truly equable bore is seldom or never to be 
 met with. Hence we should never construct 
 our thermometers on that supposition. 
 
 The first step in the formation of this instru- 
 ment, therefore, is to graduate the tube into 
 spaces of equal capacity. A small caoutchouc 
 bag with a stop-cock and nozzle capable of 
 admitting the end of the glass tube, when it 
 is wrapped round with a few folds of tissue 
 paper, must be provided ; as also pure mer- 
 cury, and a sensible balance. Having ex- 
 pelled a little air from the bag, we dip the 
 end of the attached glass tube into the mer- 
 cury, and by the elastic expansion of the 
 caoutchouc, we cause a small portion of the 
 liquid to rise into the bore. We then shut 
 the stop-cock, place the tube in a horizontal 
 direction, and remove it from the bag. The 
 column of mercury should not exceed half 
 an inch in length. By gently inclining the 
 tube, and tapping it with our finger, we 
 bring the mercury to about a couple of 
 inches from the end where we mean to make 
 the bulb, and, with a file or diamond, mark 
 there the initial line of the scale. The slip 
 of ivory, brass, or paper, destined to receive 
 the graduations, being laid on a table, we 
 apply the tube to it, so that the bottom of 
 the column of mercury coincides with its 
 lower edge. With a fine point, we then 
 mark on the scale the other extremity of the 
 mercurial column. Inclining the tube gen- 
 tly, and tapping it, we cause the liquid to 
 flow along till its lower end is placed where 
 the upper previously stood. We apply the 
 tube to the scale, taking care to make its 
 initial line correspond to the edge as be- 
 
 fore. A new point for measuring equal ca- 
 pacity is now obtained. W e thus proceed 
 till the requisite length be graduated; and 
 we then weigh the mercury with minute pre- 
 cision. 
 
 The bulb is next formed at the enameller’s 
 blow'-pipe in the usual way. One of a cy- 
 lindrical or conical shape, is preferable to a 
 sphere, both for strength and sensibility. 
 We now ascertain, and note down its weight. 
 A tubular coil of paper is to be tied to the 
 mouth of the tube, rising in a funnel-form 
 an inch or two above it. Into this we pour 
 recently boiled mercury ; and applying the 
 gentle heat of a lamp to the bulb, we expel 
 a portion of the air. On allowing the bulb 
 to cool, a portion of the mercury will des- 
 cend into it, corresponding to the quantity of 
 air previously expelled. The bulb is now to 
 be heated over the lamp till the included 
 mercury boil briskly for some time. On re- 
 moving it, the quicksilver will descend from 
 the paper funnel, and completely fill the bulb 
 and stem. Should any vesicle of air appear, 
 the process of heating or boiling must be re- 
 peated, with the precaution of keeping a co- 
 lumn of superincumbent mercury in the pa- 
 per funnel. When the temperature of the 
 bulb has sunk to nearly that of boib’ng wa- 
 ter, it may be immersed in melting ice. The 
 funnel and its mercury are then to be re- 
 moved, and the bulb is to be plunged into 
 boiling water. About l-65d of the includ- 
 ed mercury will now be expelled. On cool- 
 ing the instrument again in melting ice, the 
 zero point of the centigrade scale, corres- 
 ponding to 32° of Fahrenheit, will be indi- 
 cated, by the top of the mercurial column. 
 This point must be noted with a scratch on 
 the glass, or else by a mark on the prepared 
 scale. We then weigh the whole. 
 
 We have now sufficient data for complet- 
 ing the graduation of the instrument from 
 one fixed point; and in hot climates, and 
 other situations, where ice, for example, can- 
 not be conveniently procured, this facility of 
 forming an exact thermometer is important. 
 We know the weight of the whole included 
 mercury, and that of each gradus of the 
 stem. And as from 32° to 212° F. or from 
 0° to 100° cent, corresponds to a mercurial 
 expansion in glass of l-63d, we can easily 
 compute how many of our graduating spaces 
 are contained in the range of temperature, 
 between freezing and boiling water. Thus, 
 supposing the mercurial contents to be STS 
 grains, l-63d of that quantity, or 6 grains, 
 correspond to 180 of Fahrenheit’s degrees. 
 Now% if the initial measuring column w ere 
 0.6 of a grain, then 10 of these spaces would 
 comprehend the range between freezing and 
 boiling water. Hence, if we know the boil- 
 ing point, we can set off the freezing point ; 
 or, from the temperature of the living body. 
 98° F., we can set off both the freezing and 
 
THE 
 
 THE 
 
 boiling points of water. In the present case, 
 we must divide each space on our prepared 
 scale, into 18 equal parts, which would con- 
 stitute degrees of Fahrenheit ; or into 10 equal 
 parts, which would constitute centigrade de- 
 grees ; or into 8, which would form Reau- 
 mur’s degrees. I have graduated thermo- 
 meters in this way, and have found them to 
 be very correct. When we have ice and 
 boiling water at our command, however, we 
 may dispense with the weighing processes. 
 By plunging the instrument into melting 
 ice, and then into boiling water, we find 
 how many of our initial spaces on the stem, 
 correspond to that interval of temperature, 
 and we subdivide them accordingly. If the 
 tube be very unequable, we must accommo- 
 date even our subdivisions to its irregulari- 
 ties, for which purpose the eye is a sufficient 
 guide. 
 
 Thermometers are used for two different 
 purposes, each of which requires peculiar 
 adaptation. Those employed in meteorology, 
 or for indicating atmospherical temperature, 
 are wholly plunged in the fluid, and hence 
 the stem as well as bulb are equally affected 
 by the calorific energy. But when the che- 
 mist wishes to ascertain the temperature of 
 corrosive liquids, or bland liquids highly 
 heated, he can immerse merely the bulb, and 
 the naked part of the stem under the scale. 
 The portion of the tube corresponding to the 
 scale, is not influenced by the heat, as in the 
 former case ; and hence, l-65d part of the 
 mercury, which at 52° F. w T as acted on, lias 
 at 212° escaped from its influence. (MM. 
 Dulong and Petit make it 1 -64.8th between 
 32° and 212°; see Caloric). Hence I 
 conceive, that a meteorological and a chemi- 
 cal thermometer ought to be graduated under 
 the peculiar conditions in which they are 
 afterwards to be used. The former should 
 have its stem surrounded with the steam of 
 boiling water, while its bulb is immersed an 
 inch or two beneath the surface of that liquid, 
 the barometer having at the time an altitude 
 of 30 inches. 
 
 For ascertaining the boiling point on a 
 thermometer stem, I adapt to the mouth 
 of a tea-kettle a cylinder of tin-plate, the 
 top of which contains a perforated cork. 
 Through this, the glass tube can be slid 
 to any convenient point ; while the tin cy- 
 linder may also be raised or lowered, till 
 the bulb rest an inch beneath the water. 
 The nozzle of the kettle is shut with a cork ; 
 and at the top of the cylinder, a side-hole 
 for escape of the steam is left. If the baro- 
 meter differs from 30, by one inch, then the 
 boiling point of water will differ by 1.92° 
 F. Or 1° F. by Mr Wollaston, corresponds 
 to a difference of 0.589 of barometric pres- 
 sure. When the barometer, for example, 
 stands at 29 inches, water boils at 210,08 
 F. j and when it stands at 31 inches, the 
 
 boiling temperature is 213.92. Particular 
 attention must be paid to this source of va- 
 riation. 
 
 A thermometer for chemical experiments 
 should have its boiling point determined, by 
 immersion only of the bulb and the naked 
 portion of its stem below the scale, in boil- 
 ing water. It is surely needless to say, that 
 the water ought to be pure, since the pre- 
 sence of saline matter affects its boiling tem- 
 perature ; and it ought to be contained in a 
 metallic vessel. 
 
 Before sealing up the end of the tube, we 
 should draw it into a capillary point, and 
 heat the bulb till the mercury occupy the 
 whole of the stem. A touch of the blow- 
 pipe flame on the capillary glass will in- 
 stantly close it, and exclude the air from re- 
 entering when the bulb becomes cool. If 
 this has been skilfully executed, the column 
 of mercury will move rapidly from one end 
 of the tube to the other, when it is inverted 
 with a jerk. An ivory scale is the hand- 
 somest, but the most expensive. Those 
 used in Paris consist of a narrow slip of pa- 
 per, enclosed in a glass tube, which is attach- 
 ed in a parallel direction to the thermometer 
 stem. It is soldered to it above, by the 
 lamp, and hooked to it below, by a ring of 
 glass. Such instruments are very conve- 
 nient for corrosive liquids ; and I find them 
 not difficult to construct. 
 
 In treating of the measure of temperature 
 under Caloric, I have endeavoured to shew, 
 that were the whole body of the thermome- 
 ter, stem and bulb, immersed in boiling mer- 
 cury, it would indicate 35° more than it 
 does on the supposition of the bulb alone 
 being subjected to the calorific influence, as 
 takes place in common experiments. But 
 MM. Dulong and Petit state, that it ought 
 to indicate 680° in the former case, while 
 Mr Crichton shews that it actually indicates 
 656° in the latter, giving a difference of only 
 24° instead of 35°. This discordance be- 
 tween fact and theory, is only apparent ; for 
 we must recollect, that mercury being ail 
 excellent conductor of heat, will communi- 
 cate a portion of that expansive energy from 
 the immersed bulb, to the mercury in the 
 stem, which will be retained, in consequence 
 of glass being a very imperfect conductor of 
 heat. Hence we may infer, that but for 
 this communication of heat to the stem, a 
 thermometer, whose bulb alone is plunged in 
 boiling mercury, would stand at 645° F. or 
 17° below' the true boiling temperature by an 
 air thermometer, according to MM. Dulong 
 and Petit. If we take the mean apparent 
 expansion of mercury in glass, for 180°, be- 
 tween 32° and 662°, as given by these che- 
 mists, at l-64th ; then the above reduction 
 would become 34.4° instead of 35°, an in- 
 considerable difference. 
 
 In consequence of this double con.pcnsa- 
 o \ 1 
 
 4m* < V 
 
THE 
 
 THO 
 
 tion, a good mercurial thermometer, as con- 
 structed by Crichton, becomes an almost ex- 
 act measure of temperature, or of the rela- 
 tive apparent energies of caloric. 
 
 At the end of the Dictionary a table of 
 reduction is given for the three thermometric 
 scales, at present used in Europe ; that of 
 Reaumur, Celsius, or the centigrade, and 
 Fahrenheit. The process of reduction is 
 however a very simple case of arithmetic. 
 To convert the centigrade interval, into the 
 Fahrenheit, we multiply by 1.8 or by 6 and 
 0.3, marking off the last figure of the product 
 as a decimal. Thus an interval of 1 7° cen- 
 tigrade = 1 7° X 6 X 0.3 = one of 30. 6° 
 Fahrenheit. But as the former scale marks 
 the melting of ice 0°, and the latter 32°, we 
 must add 32° to 30.6° to have the Fahren- 
 heit number — 62.6°. 
 
 Another form of the same rule of conver- 
 sion is, from double the centigrade interval, 
 subtract one-fifth, the remainder is the Fah- 
 renheit interval. Thus from the double of 
 17 ° x= 54°, subtract = 3.4, the remain- 
 der 30.6 is the corresponding interval on 
 Fahrenheit’s scale. To convert the Fahren- 
 heit intervals into the centigrade, divide by 
 6 and by 0.3, and mark off the decimal 
 
 05 0 
 
 point, thus : 95° F. = -1 = 52.77° C. 
 
 1 6 X 0.3 
 
 When we wish to reduce a Fahrenheit 
 number, to a centigrade, we must begin by 
 deducting the 32° which the former is in 
 advance, over the latter, at the melting of 
 ice, or zero of the French scale. Thus to 
 convert 95° F. to the centigrade scale ; 95° 
 
 — 32°= 63°; 
 
 63° 
 
 6 X 0. 3 
 
 = 35 ° C. 
 
 All versed in arithmetical reduction, know 
 how advantageous it is to confine it if possi- 
 ble to one rule, and not to blend two or 
 more. Hence the ordinary rule of multi- 
 plying by 9, and dividing by 5, to bring the 
 Fahrenheit to the centigrade intervals, seems 
 less convenient than the preceding. With 
 regard to the Reaumur scale, however, which 
 is now of rare occurrence, we may employ 
 the usual proportion of 9 to 4, or to the dou- 
 ble add one-fourth : 
 
 F. = 9-4ths R. and 
 R. = 4-9ths F. 
 
 These are the relations of the intervals. 
 
 We must, however, attend to the initial 
 32° of Fahrenheit. 
 
 c o = F° — 32Q 
 
 6 X 0.5 
 
 F° == (C° X 6 X 0.3) + S2° 
 
 RO== 4 ( F - 52 °) 
 
 9 
 
 F° = -& R + 32° 
 R° 
 
 C°= — 
 
 0.8 
 
 R° = 0.8 X C°. 
 
 In the 15th volume of the Phil. Maga- 
 zine, Mr Crichton of Glasgow has describ- 
 ed a self-registering thermometer of his in- 
 vention, consisting of two oblong slips of 
 steel and zinc, firmly fixed together by their 
 faces ; so that the greater expansion or 
 contraction of the zinc, over those of the 
 steel, by the same variations of temperature, 
 causes a flexure of the compound bar. As 
 this is secured to a board at one end, the 
 whole flexure is exercised at the other, on 
 the short arm of a lever index, the free ex- 
 tremity of which moves along a graduated 
 arc. The instrument is originally adjusted 
 on a good mercurial thermometer ; and the 
 movements of the arm are registered by tw'o 
 fine wires, which are pushed before it, and 
 left at the maximum deviation to the right 
 or left of the last observed position or tem- 
 perature. The principle is obviously, that 
 of Arnold’s compensation balance for chro- 
 nometers. 
 
 An exquisite instrument on the same 
 principle has been invented by M. Breguet, 
 member of the academy of sciences, and 
 board of longitude of France. It consists of 
 a narrow metallic slip, about of an inch 
 thick, composed of silver and platina, sol- 
 dered together ; and it is coiled in a cylin- 
 drical form. The top of this spiral tube is 
 suspended by a brass arm, and the bottom 
 carries, in a horizontal position, a very deli- 
 cate golden needle, which traverses as an in- 
 dex, on a graduated circular plate. A steel 
 stud, rises in the centre of the tube, to pre- 
 vent its oscillations from the central posi- 
 tion. If the silver be on the outside of the 
 spiral, then the influence of increased tem- 
 perature will increase the curvature, and 
 move the appended needle in the direction 
 of the coil ; while the action of cold w ill re- 
 lax the coil, and move the needle in the op- 
 posite direction. M. Breguet was so good 
 as present me with tw o instruments ; both 
 of which are perfect thermometers, but one is 
 the most sensible which I ever saw. For some 
 details concerning it, see Caloric. Dr \\ ol- 
 laston shewed me in 1 809 a slip of copper 
 coated with platinum, which exhibited by its 
 curvature, over flame, or the vapour of wa- 
 ter, the expansing influence of heat, in a 
 striking manner. For other facts concern- 
 ing the measurement of heat, see Caloric.* 
 * Thorina. An earth discovered in 
 1816 by M. Berzelius. He found it in 
 small quantities in the gadolinite of Korar- 
 vet, and tw o new minerals which he calls the 
 deutofluate of cerium, and the double fluate 
 of cerium and yttria. It resembles zirco- 
 nia. 
 
 To obtain it from those minerals that con- 
 tain protoxide of cerium and yttria, we must 
 first separate the oxide of iron by succinate 
 of ammonia. The new' earth, indeed, may, 
 when alone, be precipitated by the sucei- 
 
THO 
 
 nates ; but in the analytical experiments in 
 which he has obtained it, it precipitated in 
 so small a quantity along with iron, that he 
 could not separate it from that oxide. The 
 deutoxide of cerium is then precipitated by 
 the sulphate of potash ; after which the 
 yttria and the new earth are precipitated to- 
 gether by caustic ammonia. Dissolve them 
 in muriatic acid. Evaporate the solution to 
 dryness, and pour boiling water on the resi- 
 due, which will dissolve the greatest part of 
 the yttria ; but the undissolved residue still 
 contains a portion of It. Dissolve it in mu- 
 riatic or nitric acid, and evaporate it till 
 it becomes as exactly neutral as possible. 
 Then pour water upon it, and boil it for 
 an instant. The new earth is precipitated, 
 and the liquid contains disengaged acid. 
 By saturating this liquid, and boiling it a 
 second time, we obtain a new precipitate of 
 the new earth. 
 
 This earth, when separated by the filter, 
 has the appearance of a gelatinous, semi- 
 transparent mass. When washed and dried, 
 it becomes white, absorbs carbonic acid, and 
 dissolves with effervescence in acids. Though 
 calcined, it retains its white colour ; and 
 when the heat to which it has been exposed 
 ■was only moderate, it dissolves readily in 
 muriatic acid ; but if the heat has been vio- 
 lent, it will not dissolve till it be digested in 
 strong muriatic acid. This solution has a 
 yellowish colour ; but it becomes colourless 
 when diluted with water, as is the case with 
 glucina, yttria, and alumina. If it be mixed 
 with yttria, it dissolves more readily after 
 having been exposed to heat. The neutral 
 solutions of this earth have a purely astrin- 
 gent taste, which is neither sweet, nor saline, 
 nor bitter, nor metallic. In this property it 
 differs from all other species of earths, ex- 
 cept zirconia. 
 
 When dissolved in sulphuric acid with a 
 slight excess of acid, and subjected to evapo- 
 ration, it yields transparent crystals, which 
 are not altered by exposure to the air, and 
 which have a strong styptic taste. 
 
 This earth dissolves very easily in nitric 
 acid ; but, after being heated to redness, it 
 does not dissolve in it except by long boil- 
 ing. The solution does not crystallize, but 
 forms a mucilaginous mass, which becomes 
 more liquid by exposure to the air, and 
 which, when evaporated by a moderate heat, 
 leaves a white, opaque mass, similar to ena- 
 mel, in a great measure insoluble in water. 
 
 It dissolves in muriatic acid, in the same 
 manner as in nitric acid. The solution does 
 not crystallize. When evaporated by a mo- 
 derate heat, it is converted into a syrupy 
 mass, which docs not deliquesce in the air, 
 but dries, becomes white like enamel, and 
 afterwards dissolves only in very small quan- 
 tity in water, leaving a subsait undissolved ; 
 so that by spontaneous evaporation it lets the 
 
 TIN 
 
 portion of muriatic acid escape to which it 
 owed its solubility. 
 
 This earth combines with avidity with car- 
 bonic acid. The precipitates produced by 
 caustic ammonia, or by boiling the neutral 
 solutions of the earth in acids, absorb car- 
 bonic acid from the air in drying. The al- 
 kaline carbonates precipitate the earth com- 
 bined with the whole of their carbonic acid. 
 
 The ferruginous prussiate of potash pour- 
 ed into a solution of this earth, throws down 
 a white precipitate, which is completely re- 
 dissolved by muriatic acid. 
 
 Caustic potash and ammonia have no ac- 
 tion on this earth newly precipitated, not 
 even at a boiling temperature. 
 
 The solution of carbonate of potash, or 
 carbonate of ammonia, dissolves a small 
 quantity of it, which precipitates again when 
 the liquid is supersaturated with an acid, 
 and then neutralized by caustic ammonia ; 
 but this earth is much less soluble in the 
 alkaline carbonates than any of the earths 
 formerly known that dissolve in them. 
 
 Thorina differs from the other earths by 
 the following properties : From alumina, by 
 its insolubility in hydrate of potash ; from 
 glucina, by the same property ; from yttria, 
 by its purely astringent taste, without any 
 sweetness, and by the property which its so- 
 lutions possess of being precipitated by boil- 
 ing when they do not contain too great an 
 excess of acid. It differs from zirconia by 
 the following properties: 1. After being 
 heated to redness, it is still capable of being 
 dissolved in acids. 2. Sulphate of potash 
 does not precipitate it from its solutions 
 while it precipitates zirconia from solutions 
 containing even a considerable excess of acid. 
 3. It is precipitated by oxalate of ammonia, 
 which is not the case with zirconia. 4. Sul- 
 phate of thorina crystallizes readily, while 
 sulphate of zirconia, supposing it free from 
 alkali, forms, when dried, a gelatinous, 
 transparent mass, without any trace of crys- 
 tallization.* 
 
 * Thorinum. The supposed metallic 
 basis of the preceding earth, not hitherto ex- 
 tracted.* 
 
 * Thulite. A hard peach-blossom co- 
 loured mineral found at Sonland, in Telle- 
 mark in Norway.* 
 
 * Tiiumerstone. Axinite.* 
 
 * Tile Ore. A sub-specics of octohedral 
 red copper ore.* 
 
 Tin is a metal of a yellowish- white co- 
 lour, considerably harder than lead, scarcely 
 at all sonorous, very malleable, though not 
 very tenacious. Under the hammer it is ex- 
 tended into leaves, called tin-foil, which are 
 about one-thousandth of an inch thick, and 
 might easily be beaten to less than half that 
 thickness, if the purposes of trade required 
 it. The process for making tin-foil consists 
 simply in hammering out a number of plates 
 
TIN 
 
 TIN 
 
 of this metal, laid together upon a smooth 
 block or plate of iron. The smallest sheets 
 are the thinnest. Its specific gravity is 7.29. 
 It melts at about the 442° of Fahrenheit’s 
 thermometer, and by a continuance of the heat 
 it is slowly converted into a white powder 
 by oxidation. Like lead, it is brittle when 
 heated almost to fusion, and exhibits a grain- 
 ed or fibrous texture, if broken by the blow 
 of a hammer ; it may also be granulated by 
 agitation at the time of its transition from 
 the fluid to the solid state. The oxide of tin 
 resists fusion more strongly than that of any 
 other metal ; from which property it is use- 
 ful, to form an opaque white enamel when 
 mixed with pure glass in fusion. The 
 brightness of its surface, when scraped, soon 
 goes oil’ by exposure to the air ; but it is not 
 subject to rust or corrosion by exposure to 
 the weather. 
 
 * To obtain pure tin, the metal should 
 be boiled in nitric acid, and the oxide which 
 falls down reduced by heat in contact with 
 charcoal, in a covered crucible. 
 
 There are two definite combinations of tin 
 and oxygen. The first or protoxide is grey ; 
 the second or peroxide is white. The first 
 is formed by heating tin in the air, or by dis- 
 solving tin in muriatic acid, and adding wa- 
 ter of potash to the solution whilst recent, 
 and before it has been exposed to air. The 
 precipitate, after being heated to whiteness 
 to expel the water of the hydrate is the pure 
 protoxide. It is convertible into the per- 
 oxide by being boiled with dilute nitric acid, 
 dried and ignited. According to Sir LI. 
 Davy the protoxide contains IS. 5 per cent of 
 oxygen. Supposing it to consist of a prime 
 equivalent of each constituent, that of tin 
 would be 7.333. From the analyses of Ber- 
 zelius and Gay Lussac, the peroxide is com- 
 posed of 100 metal -}- 27-2 oxygen ; and if 
 we regard it as containing 2 primes of the 
 latter principle to 1 of metal, the prime of 
 this will be 7.555. The mean may be taken 
 at 7.35. 
 
 There are also two chlorides of tin. When 
 tin is burned in chlorine, a very volatile 
 clear liquor is formed, a non-conductor of 
 electricity, and which, when mixed with a 
 little water, becomes a solid crystalline sub- 
 stance, a true muriate of tin, containing the 
 peroxide of the metal. This, which has 
 been called the liquor of Libavius, may be 
 also procured, by heating together tin-filings 
 and corrosive sublimate, or an amalgam of 
 tin and corrosive sublimate. It consists, ac- 
 cording to the analysis of Dr John Davy, 
 of 2 primes of chlorine = 9 -j- 1 of tin 
 — 7.35. The other compound of tin and 
 chlorine, is a grey semi-transparent crystal- 
 line solid. It may be procured by heating 
 together an amalgam of tin and calomel. It 
 dissolves in water, and forms a solution, 
 which rapidly absorbs oxygen from the air, 
 
 2(5 
 
 with deposition of peroxide of tin. It con- 
 sists of chlorine, 4.5 
 tin, 7 .55 
 
 There are two sulphurets of tin. One 
 may be made by fusing tin and sulphur to- 
 gether. It is of a bluish colour, and lamel- 
 lated texture. It consists of 7.35 tin -j- 2 
 sulphur. The other sulphuret, or the bi- 
 sulphuret, is made by heating together the 
 peroxide of tin and sulphur. It is of a 
 beautiful gold colour, and appears in fine 
 flakes. It was formerly called aurum musi- 
 vum. According to Dr John Davy, it con- 
 sists of 1 prime tin = 7.35 
 2 sulphur = 4.00 
 
 For another mode of making it, see Aurum 
 Musivum. 
 
 The salts of tin are characterized by the 
 following general properties : 
 
 1. Ferroprussiate of potash gives a white 
 precipitate. 
 
 2. Hydrosulphuret of potash, a brown- 
 black with the protoxide ; and a golden- 
 yellow with the peroxide. 
 
 3. Galls do not affect the solutions of 
 these salts. 
 
 4. Corrosive sublimate occasions a black 
 precipitate with the protoxide salts ; a white 
 with the peroxide. 
 
 5. A plate of lead frequently throws down 
 metallic tin or its oxide, from the saline so- 
 lutions. 
 
 6. Muriate of gold gives, with the pro- 
 toxide solutions, the purple precipitate of 
 cassius. 
 
 7. Muriate of platinum occasions an 
 orange precipitate with the protoxide salts.* 
 
 Concentrated sulphuric acid, assisted by 
 heat, dissolves half its weight of tin, at the 
 same time that sulphureous gas escapes in 
 great plenty. By the addition of water, an 
 oxide of tin is precipitated. Sulphuric acid, 
 slightly diluted, likewise acts upon this me- 
 tal ; but if much water he present, the solu- 
 tion does not take place. In the sulphuric 
 solution of tin, there is an actual formation 
 or extrication of sulphur, which renders the 
 fluid of a brown colour while it continues 
 heated, but subsides by cooling. The tin is 
 likewise precipitated in the form of a w4iite 
 oxide, by a continuance of the heat, or by 
 Iona: standing without heat. This solution 
 affords needle-formed crystals by cooling. 
 
 Nitric acid and tin combine together very 
 rapidly, without the assistance of heat. Most 
 of the metal falls down in the form of a 
 white oxide, extremely difficult of reduction ; 
 and the small portion of tin, which remains 
 suspended, does not afford crystals, but falls 
 down, for the most part, upon the application 
 of heat to inspissate the fluid. '1 he strong 
 action of the nitric acid upon tin, produces a 
 singular phenomenon, which is happily ac- 
 counted for by the modern discoveries in 
 chemistry. M. de Morveau has observed, 
 
TIN 
 
 TIN 
 
 that, in a solution of tin by the nitric acid, 
 no elastic fluid is disengaged, but ammonia 
 is formed. This alkali must have been pro- 
 duced by the nitrogen of that part of the 
 nitric acid which was employed in affording 
 oxygen to oxidize the tin. 
 
 The muriatic acid dissolves tin very rea- 
 dily, at the same time that it becomes of a 
 darker colour, and ceases to emit fumes. A 
 slight effervescence takes place with the dis- 
 engagement of a fetid inflammable gas. Mu- 
 riatic acid suspends half its weight of tin, 
 and does not let it fall by repose. It affords 
 permanent crystals by evaporation. If the 
 tin contain arsenic, it remains undissolved 
 at the bottom of the fluid. Recent muriate 
 of tin is a very delicate test of mercury. 
 M. Chenevix says, if a single drop of a satu- 
 rated solution of neutralized nitrate, or mu- 
 riate of mercury, be put into 500 grains of 
 water, a few drops of solution of muriate of 
 tin will render it a little turbid, and of a 
 smoke-grey. lie adds, that the effect is 
 perceptible, if ten times as much water be 
 added. 
 
 Aqua regia, consisting of two parts nitric 
 and one muriatic acid, combines with tin 
 with effervescence, and the development of 
 much heat. In order to obtain a permanent 
 solution of tin in this acid, it is necessary to 
 add the metal by small portions at a time ; 
 so that the one portion may be entirely dis- 
 solved before the next piece is added. Aqua 
 regia, in this manner, dissolves half its 
 weight of tin. The solution is of a reddish- 
 brown, and in many instances assumes the 
 form of a concrete gelatinous substance. 
 The addition of water sometimes produces 
 the concrete form in this solution, which is 
 then of an opal colour, on account of the 
 oxide of tin diffused through its substance. 
 
 The uncertainty attending these experi- 
 ments with the solution of tin in aqua regia, 
 seems to depend upon the want of a suffi- 
 cient degree of accuracy in ascertaining the 
 specific gravities of the two acids which are 
 mixed, the quantities of each, and of the tin, 
 together with that of the water added. It is 
 probable, that the spontaneous assumption 
 of the concrete state, depends upon water 
 imbibed from the atmosphere. The solu- 
 tion of tin in aqua regia, is used by dyers to 
 heighten the colours of cochineal, gum-lac, 
 and some other red tinctures, from crimson 
 to a bright scarlet, in the dyeing of woollens. 
 
 The acetic acid scarcely acts upon tin. 
 The operation of other acids upon this metal 
 has been little inquired into. Phosphate, 
 fluate, and borate, of tin, have been formed 
 by precipitating the muriate with the respec- 
 tive neutral salts. 
 
 If the crystals of the saline combination 
 «of copper with the nitric acid be grossly 
 powdered, moistened, and rolled up in tin- 
 foil, the salt deliquesces, nitrous fumes are 
 
 emitted, the mass becomes hot, and sudden- 
 ly takes fire. In this experiment, the rapid 
 transition of the nitric acid to the tin, is sup- 
 posed to produce or develope heat enough 
 to set fire to the nitric salts; but by what 
 particular changes of capacity, has not been 
 shown. 
 
 If small pieces of phosphorus be thrown 
 on tin in fusion, it will take up from 15 to 
 20 per cent, and form a silvery white phos- 
 phuret of a foliated texture, and soft enough 
 to be cut with a knife, though but little mal- 
 leable. This phosphuret may be formed 
 likewise by fusing tin filings with concrete 
 phosphoric acid. 
 
 Tin unites with bismuth by fusion, and 
 becomes harder and more brittle in propor- 
 tion to the quantity of that metal added. 
 With nickel it forms a white brilliant mass. 
 It cannot easily be united in the direct way 
 with arsenic, on account of the volatility of 
 this metal; but by heating it with the com- 
 bination of the arsenical acid and potash, 
 the salt is partly decomposed ; and the tin 
 combining with the acid, becomes converted 
 into a brilliant brittle compound, of a plait- 
 ed texture. It has been said, that all tin 
 contains arsenic ; and that the crackling 
 noise which is heard upon bending pieces of 
 tin, is produced by this impurity ; but, from, 
 the experiment of Bayen, this appears not 
 to be the fact. Cobalt unites with tin by 
 fusion ; and forms a grained mixture of a 
 colour slightly inclining to violet. Zinc 
 unites very well with tin, increasing its hard- 
 ness, and diminishing its ductility, in pro- 
 portion as the quantity of zinc is greater. 
 
 This is one of the principal additions 
 used in making pewter, which consists for 
 the most part of tin. The best pewter does 
 not contain above one-twentieth part of ad- 
 mixture, which consists of zinc, copper, bis- 
 muth, or such other metallic substances, as 
 experience has shown to be most conducive 
 to the improvement of its hardness and co- 
 lour. The inferior sorts of pewter, more 
 especially those used abroad, contain much 
 lead, have a bluish colour, and are soft. 
 The tin usually met with in commerce in 
 this country, has no admixture to impair its 
 purity, except such as may accidentally elude 
 the workmen at the mines. But the tin met 
 with in foreign countries, is so much debas- 
 ed by the dealers in that article, especially 
 the Dutch, that pewter and tin are consider- 
 ed abroad as the same substance. 
 
 Antimony forms a very brittle hard mix- 
 ture with tin ; the specific gravity of which 
 is less than w'ould have been deduced by 
 computation from the specific gravities and 
 quantities of each, separately taken. Tung- 
 sten fused with twice its weight of tin, af- 
 fords a brown spongy mass, which is some- 
 what ductile. 
 
 The uses of tin are very numerous, and 
 
TIT 
 
 TOL 
 
 so well known, that they scarcely need be 
 pointed out. Several of them have been al- 
 ready mentioned. r I he tinning of iron and 
 copper, the silvering of looking-glasses, and 
 the fabrication of a great variety of vessels 
 and utensils for domestic and other uses, 
 are among the advantages derived from this 
 metal. 
 
 Tincal. Crude borax, as it is imported 
 from the East Indies in yellow greasy crys- 
 tals, is called tincal. 
 
 Ting lass. Bismuth. 
 
 * Tinning. See Iron.* 
 
 Titanites. This name has been given 
 to certain ores of titanium, containing that 
 metal in the state of oxide. See the follow- 
 ing article. 
 
 Titanium. About twenty years ago, the 
 Bev. Mr Gregor discovered in a kind of fer- 
 ruginous sand, found in the vale of Mena- 
 chan, in Cornwall, what he supposed to be 
 the oxide of a new metal, but was unable to 
 reduce. 
 
 Klaproth, afterward analyzing what was 
 called the red schorl of Hungary, found it 
 to be the pure oxide of a new metal, which 
 he named titanium, and the same with the 
 menachanite of Mr Gregor. Since that 
 oxide of titanium has been discovered in se- 
 veral fossils. 
 
 We do not know that titanium has been 
 completely reduced, except by Lampadius, 
 who effected it by means of charcoal only. 
 The oxide he employed was obtained from 
 the decomposition of gallate of titanium by 
 fixed alkali. The metal was of a dark cop- 
 per colour, with much metallic brilliancy, 
 brittle, and in small scales considerably elas- 
 tic. It tarnishes in the air, and is easily 
 oxidized by heat. It then acquires a bluish 
 aspect. It detonates with nitre, and is highly 
 infusible. All the dense acids act upon it 
 with considerable energy. According to Vau- 
 quelin, it is volatilized by intense heat. 
 
 The native red oxide is insoluble in the 
 sulphuric, nitric, muriatic, and nitro-mu- 
 riatic acids : but if it be fused with six 
 parts of carbonate of potash, the oxide is 
 dissolved with effervescence. The sulphu- 
 ric solution when evaporated becomes gela- 
 tinous; the nitric affords rhomboidal crys- 
 tals by spontaneous evaporation, but is ren- 
 dered turbid by ebullition ; the muriatic be- 
 comes gelatinous, or flocculcnt, by heat, and 
 transparent crystals form in it when cooled ; 
 but if it be boiled, oxygenized muriatic acid 
 gas is evolved, and a white oxide thrown 
 down. Phosphoric and arsenic acids take it 
 from the others, and form with it a white 
 precipitate. These precipitates are soluble 
 in muriatic acid, but in no other. 
 
 The solutions of titanium give white pre- 
 cipitates with the alkalis, or their carbonates ; 
 tincture of galls gives a brownish-red, and 
 prussiate of potash a brownish -yellow. If 
 
 the prussiate produce a green precipitate, 
 this, according to Lowitz, is owing to the 
 presence of iron. Zinc immersed in the so- 
 lutions, changes their colour from yellow to 
 violet, and ultimately to an indigo; tin pro- 
 duces in them a pale red tint, which deepens 
 to a bright purple red. Hydrosulphuret of 
 potash throws down a brownish- red precipi- 
 tate, but they are not decomposed by sul- 
 phuretted hydrogen. 
 
 By exposing phosphate of titanium, mix- 
 ed with charcoal and borax, to a violent 
 heat, in a double crucible luted, M. Chene- 
 vix obtained a pale white phosphuret, with 
 some lustre, brittle, of a granular texture, 
 and not very fusible. 
 
 The oxides of iron and titanium, exposed 
 to heat with a little oil and charcoal, pro- 
 duce an alloy of a grey colour, intermixed 
 with brilliant metallic particles of a golden 
 yellow. 
 
 Oxide of titanium was used to give a 
 brown or yellow' colour in painting on por- 
 celain, before its nature was known 5 but it 
 was found difficult to obtain from it an uni- 
 form tint, probably from its not being in a 
 state of purity. 
 
 * Tobacco. The expressed juice of the 
 leaves, according to Vauquelin, contain the 
 following substances: — 
 
 A considerable quantity of vegetable al- 
 bumen or gluten ; supermalate of lime 5 
 acetic acid. 
 
 A notable quantity of nitrate and muriate 
 of potash. A red matter soluble in alcohol 
 and water, which swells considerably when 
 heated. 
 
 Muriate of ammonia. 
 
 Nicotin. 
 
 Green fecula composed chiefly of gluten, 
 green resin, and woody fibre.* 
 
 Tolu (Balsam of). This substance is 
 obtained from the toluifera balsamum, a 
 tree which grows in South America. The 
 balsam flow’s from incisions made in the 
 bark. It comes to Europe in small gourd 
 shells. It is of a reddish-brown colour and 
 considerable consistence ; and when exposed 
 to the air, it becomes solid and brittle. Its 
 smell is fragrant, and continues so, even 
 after the balsam has become thick by age. 
 When distilled with water, it yields very 
 little volatile oil, but impregnates the water 
 strongly with its taste and smell. A quan- 
 tity of benzoic acid sublimes, if the distilla- 
 tion be continued. 
 
 Mr Hatchett found it soluble in the al- 
 kalis, like the rest of the balsams. When 
 he dissolved it in the smallest possible quan- 
 tity of lixivium of potash, it completely lost 
 its own odour, and assumed a fragrant smell, 
 somewhat resembling that of the clove pink. 
 “ This smell,” Mr Hatchett observes, “ is 
 not fugitive, for it is still retained by a solu- 
 tion, which was prepared in June, and has 
 
TOU 
 
 TOP 
 
 # 
 
 remained in an open glass during four 
 months.” 
 
 When digested in sulphuric acid, a con- 
 siderable quantity of pure benzoic acid su- 
 blimes. When the solution of it in this 
 acid is evaporated to dryness, and the resi- 
 duum treated with alcohol, a portion of 
 artificial tannin is obtained ; the residual 
 charcoal amounts to 0.54 of the original 
 balsam. 
 
 Mr Hatchett found, that it dissolved in 
 nitric acid, with nearly the same phenomena 
 as the resins; but it assumed the smell of 
 bitter almonds, which led him to suspect the 
 formation of prussic acid. During the solu- 
 tion in nitric acid, a portion of benzoic acid 
 sublimes. By repeated digestions, it is con- 
 verted into artificial tannin. 
 
 It is totally soluble in alcohol, from which 
 water separates the whole of it, except the 
 benzoic acid. 
 
 Tombac. A white alloy of copper with 
 arsenic, commonly brittle, though if the 
 quantity of arsenic be small, it is both duc- 
 tile and malleable in a certain degree. It is 
 sometimes called white copper. 
 
 * Topaz. According to Professor Jame- 
 son, this mineral species contains three sub- 
 species, common topaz, schorl ite, and physa- 
 lite. 
 
 Common topaz . Colour wine-yellow. In 
 granular concretions, disseminated and crys- 
 tallized. Its primitive form is an oblique 
 prism of 124° 22'. The following are se- 
 condary forms. An oblique four-sided prism, 
 acuminated by four planes ; the same, with 
 the acute lateral edges bevelled ; the same, 
 with a double acumination ; and several 
 other modifications, for which consult Jame- 
 son’s Min. vol. i. p. 75. The lateral planes 
 are longitudinally streaked. Splendent and 
 vitreous. Cleavage perfect and perpendicu- 
 lar to the axis of the prism. Fracture, small 
 conchoidal. Transparent. Refracts double. 
 Harder th..n quartz, or emerald; but softer 
 than corundum. Easily frangible. Sp. gr„ 
 3.4 to 5.6. 
 
 Saxon topaz in a gentle beat becomes 
 white, but a strong heat deprives it of lustre 
 and transparency. The Brazilian, on the 
 contrary, by exposure to a high temperature, 
 burns rose- red, and in a still higher, violet- 
 blue. Before the blow-pipe, it is infusible. 
 The topaz of Brazil, Siberia, Mucla in Asia- 
 Minor, and Saxony, when heated, exhibit at 
 one extremity positive, and at the other, ne- 
 gative electricity. It also becomes electrical 
 by friction ; and retains its electricity very 
 long. Its constituents are, 
 
 
 Braz. Top. 
 
 Sax. T. 
 
 Sax. T. 
 
 Alumina, 
 
 58.38 
 
 57.45 
 
 59 
 
 Silica, 
 
 54.01 
 
 34.24 
 
 35 
 
 Fluoric acid, 
 
 7.79 
 
 7.75 
 
 5 
 
 
 100.18 
 
 99.44 
 
 99 
 
 
 JJcrzclius. 
 
 Klapr. 
 
 Klapr. 
 
 Topaz forms an essential constituent of a 
 particular mountain-rock, which is an aggre- 
 gate of topaz, quartz, and schorl, and is 
 named topaz-rock. Topaz occurs in drusy 
 cavities in granite. It has been also disco- 
 vered in nests, in transition clay-slate ; and 
 it is found in rolled pieces in alluvial soil. 
 It occurs in large crystals, and rolled masses, 
 in an alluvial soil, in the granite and gneiss 
 districts of Mar and Cairngorm, in the up- 
 per parts of Aberdeenshire; and in veins, along 
 with tin-stone, in clay-slate at St Anne’s, 
 Cornwall. On the continent, it appears 
 most abundantly in topaz-rock at Schnecken- 
 stein. — Jameson. * 
 
 * Topazolite. A variety of precious gar- 
 net, found at Mussa in Piedmont. * 
 
 * Tortoise-shell. It approaches to nail or 
 coagulated albumen in its composition. 500 
 parts, after incineration, leave three of earthy 
 matter, consisting of phosphate of lime, and 
 soda, with a little iron.* 
 
 * Touchstone. Lydian stone, a variety 
 of flinty- slate.* 
 
 * Tourmaline. Rhomboidal tourmalino 
 is divided into two sub-species, schorl , and 
 tourmaline. 
 
 Tourmaline. Colours green and brown. 
 In prismatic concretions, rolled pieces, but 
 generally crystallized. Primitive form, a 
 rhomboid of 133° 26'. It occurs in an 
 equiangular three-sided prism, flatly acumi- 
 nated on the extremities with three planes.. 
 The lateral edges are frequently bevelled, 
 and thus a nine-sided prism is formed : 
 when the edges of the bevelment are trun- 
 cated, a twelve-sided prism is formed ; and 
 when the bevelling planes increase so much, 
 that the original faces of the prism disappear, 
 an equiangular six-sided prism is formed. 
 Sometimes the prism is nearly awanting, 
 when a double three-sided pyramid is formed. 
 The lateral planes are generally cylindrical 
 convex, and deeply longitudinally streaked. 
 Crystals imbedded. Splendent, vitreous. 
 
 Cleavage threefold. Fracture conchoidal. 
 
 Opaque to transparent. Refracts double. 
 When viewed perpendicular to the axis of 
 the crystal, it is more or less transparent, but 
 in the direction of the axis, even when the 
 length of the prism is less than the thickness, 
 it is opaque. As hard as quartz. Easily 
 frangible. Sp. gr. 3.0 to 3.2. By friction 
 it yields vitreous electricity ; by beating, 
 vitreous at one end, and resinous at the other. 
 The brown and hyacinth-red varieties, have 
 these properties in the greatest degree. The 
 ancients called it lyncurium. Before the 
 blow-pipe, it melts into a greyish-white 
 vesicular enamel. Its constituents are, silica 
 42, alumina 40, soda 10, oxide of manga- 
 nese with a little iron 7, loss 1. — Yauquelin . 
 It occurs in gneiss, mica-slate, talc-slate, 
 
 The red occurs in Siberia, Ava, and Cey- 
 lon. — Jameson. '* 
 
Til A 
 
 TRE 
 
 Iracacanth (Gum). This substance, 
 which is vulgarly called gum-dragon, ex- 
 udes from a prickly bush, the astragalus tra - 
 gacantha , Lin. which grows wild in the war- 
 mer climates, and endures the cold of our 
 own, but does not here yield any gum. This 
 commodity is brought chiefly from Turkey, 
 in irregular lumps, or long vermicular pieces 
 bent into a variety of shapes; the best sort is 
 white, semi-transparent, dry, yet somewhat 
 soft, to the touch. 
 
 Gum-tragacanth differs from all the other 
 known gums, in giving a thick consistence 
 to a much larger quantity of water; and in 
 being much more difficultly soluble, or ra- 
 ther dissolving only imperfectly. Put into 
 water it slowly imbibes a great quantity of 
 the liquid, swells into a large volume, and 
 forms a soft but not fluid mucilage ; if more 
 water be added, a fluid solution may be ob- 
 tained by agitation : but the liquor looks 
 turbid and wheyish, and on standing, the 
 mucilage subsides, the limpid water on the 
 surface retaining little of the gum. Nor 
 does the admixture of the preceding more 
 soluble gums promote its union with the 
 water, or render its dissolution more dura- 
 ble : when gum-tragacanth, and gum-arabic 
 are dissolved together in water, the traga- 
 canth seems to separate from the mixture 
 more speedily than when dissolved by it- 
 self. 
 
 Tragacanth is usually preferred to the 
 other gums for making up troches, and 
 other like purposes, and is supposed like- 
 wise to be the most effectual as a medicine ; 
 but on account of its imperfect solubility, is 
 unfit for liquid forms., It is commonly given 
 in powder with the addition of other mate- 
 rials of similar intention ; thus to one part 
 of gum-tragacanth, are added one of gum- 
 arabic, one of starch, and six of sugar. See 
 Cerasin. 
 
 * Trap Fop.mations in geology. 
 
 Primitive trap. The name trap is deriv- 
 ed from the Swedish word trappa , a stair. 
 Werner understands by trap, rocks princi- 
 pally characterized by the presence of horn- 
 blende, and black iron clay. Hence all rocks 
 occurring in the primitive class, having horn- 
 blende as a characteristic, or predominating 
 ingredient, belong to the primitive trap for- 
 mation. The following table from Professor 
 Jameson exhibits the rocks of this forma- 
 tion. 
 
 1. Gommon hornblende rock. 
 
 a. Granular hornblende rock. 
 
 b. II ornblende slate. 
 
 2. Hornblende mixed with felspar. 
 
 a. Greenstone. 
 
 «. Common greenstone. 
 
 (j. Porphyritic greenstone. 
 y . Greenstone porphyry. 
 
 Green porphyry. 
 
 b. Greenstone slate. 
 
 3. Hornblende mixed with mica. 
 
 Transition trap. It contains greenstone 
 and amygdaloid. 
 
 The newest floetz-trap contains several 
 rocks which are peculiar to it, and others 
 that occur in other floetz formations. The 
 peculiar or characteristic rocks are, basalt , 
 waclce, grey stone, porphyry-slate, and trap- 
 tuff. These, and also greenstone, are often 
 called whinstone by mineralogists.* 
 
 * Trap-tuff. It is composed of masses 
 of basalt, amygdaloid, hornblende rock, sand- 
 stone, and even pieces of wood (as in the 
 island of Canna) cemented together by a 
 rather loose spongy clayey basis, which has 
 been formed from decomposed basalt or 
 wacke rock. The masses vary much in size, 
 from that of a pea, to several hundred weight. 
 It occurs in beds, which are from a few inches 
 to several fathoms thick. A considerable 
 portion of Arthur’s-seat, near Edinburgh, is 
 composed of this rock : there it rest* on in- 
 clined strata which belong to the oldest coal 
 formation. It occurs also in Mull, and many 
 other places in Scotland.* 
 
 * Tremolite. This sub-species of straight- 
 edged augite is divided into three kinds ; the 
 asbestous, common, and glassy. 
 
 1. Asbestous tremolite. Colour greyish- 
 white. Massive, and in fibrous concre- 
 tions. Shining, pearly. Fragments splintery. 
 Translucent on the edges. Rather easily 
 frangible. Soft. Rather sectile. When 
 struck gently, or rubbed in the dark, it emits 
 a pale reddish light; when pounded and 
 thrown on coals, a greenish light. Before 
 the blow- pipe, it melts into a white opaque 
 mass. It occurs most frequently in granular 
 foliated limestone, or in dolomite. It is 
 found in the former in Glentilt and Glen- 
 elg ; in the latter, in Aberdeenshire and 
 Icolmkill; and in basalt in the Castle-rock 
 of Edinburgh. 
 
 2. Common tremolite. Colour white. 
 Massive, in distinct prismatic concretions, 
 and crystallized in a very oblique four-sided 
 prism, truncated or bevelled on the lateral 
 edges ; in an extremely oblique four-sided 
 prism, perfect or variously modified by bevel- 
 ment or truncation. The lateral planes are 
 longitudinally streaked. Vitreous or pearly. 
 Cleavage double oblique angular, of 124^ 
 50' and 55° 50'. Fracture uneven or con- 
 choidal. Translucent. As hard as horn- 
 blende. Rather brittle. Sp. gr. 2.9 to 3.2. 
 It melts with much difficulty and ebullition 
 into an opaque glass. Its constituents arc, 
 silica 50, magnesia 25, lime 18, carbonic 
 acid and water 5. — Laugier. It occurs with 
 the preceding. 
 
 5. Glassy tremolite. Colour greyish, 
 greenish, yellowish, and red dish- white. Mas- 
 sive, in distinct concretions, and frequently 
 crystallized in long acicular crystals. Shin- 
 ing, between vitreous and pearly. lr.ms- 
 
TUN 
 
 TUN 
 
 lucent. As hard as hornblende. Very 
 brittle. Sp. gr. 2.865. It is phosphures- 
 cent in a low degree. Infusible. Its con- 
 stituents are, silica 55.5, lime 26.5, mag- 
 nesia 16.5, water and carbonic acid 25. — 
 Lciugier, It occurs with the preceding. — 
 Jameson .* 
 
 * Triphane. See Spodumene. * 
 
 * Tripoli. Colour yellowish-grey. Mas- 
 
 sive. Fracture fine or coarse earthy. Opaque. 
 Soft. Rather easily frangible. Meagre. 
 Does not adhere to the tongue. Sp. gr. 
 2.2. Infusible. Its constituents are, silica 
 81, alumina 1.5, oxide of iron 8, sulphuric 
 acid 5.45, water 4.55. — Bucholz. Of the 
 
 rottenstone, silica 4, alumina 86, carbon 10. 
 — Phillips. It occurs in beds in coal-fields, 
 with secondary limestone, and under basalt. 
 It is found at Bakewell, in Derbyshire, 
 where it is called rottenstone. It is used for 
 polishing stones, metals, and glasses. The 
 tripoli of Corfu is reckoned the most valu- 
 able. * 
 
 * Trona. The name given in Africa to 
 the native carbonate of soda, found at Sukena, 
 near Fezzan.* 
 
 Tube of Safety. A tube open at both 
 ends, inserted into a receiver, the upper end 
 communicating with the external air, and the 
 lower being immersed in water. Its inten- 
 tion is to prevent injury from too sudden 
 condensation or rarefaction taking place dur- 
 ing an operation. For, if a vacuum be pro- 
 duced within the vessels, the external air will 
 enter through the tube : and if air be gene- 
 rated, the water will yield to the pressure, 
 being forced up the tube. Thus, too, the 
 height of the water in the tube indicates the 
 degree of pressure from the confined gas or 
 gases. See PI. VII. fig. 3. h. It is now 
 more frequently used in a curved form, ib. 
 fig. l.$ and is commonly called a welter’s 
 tube. 
 
 * Tu faceous Limestone, or Calc Tuff. 
 See Limestone.* 
 
 Tumite. See Thummerstone. 
 
 * Tungsten. See Ores of Tungsten.* 
 
 Iungstenum. This name, signifying 
 
 heavy stone, was given by the Swedes to a 
 mineral, which Scheele found to contain a 
 peculiar metal, as he supposed, in the state of 
 an acid, united with lime. The same metal- 
 lic substance was afterward found by the 
 Don d’Elhuyarts united with iron and man- 
 ganese in wolfram. 
 
 From the first of these the oxide may be 
 obtained by digesting its powder in thrice 
 its weight of nitric acid ; washing the yel- 
 low powder that remains, and digesting it 
 in ammonia, by which a portion of it is dis- 
 solved. These alternate digestions are to 
 be repeated, and the tungstic oxide precipi- 
 tated from the ammoniacal solutions by nitric 
 acid. The precipitate is to be washed with 
 water, and exposed to a moderate heat, to 
 
 expel any ammonia that may adhere to it. 
 Or the mixture may be evaporated to a dry 
 mass, which is to be calcined under a muffle, 
 to dissipate the nitrate of ammonia. From 
 wolfram it may be obtained by the same pro- 
 cess, after the iron and manganese have been 
 dissolved by muriatic acid. 
 
 The Spanish chemists reduced the oxide 
 of tungsten to the metallic state, by’exposing 
 it moistened with oil, in a crucible lined with 
 charcoal, to an intense heat. After two 
 hours a piece of metal weighing 40 grains, 
 but slightly agglutinated, was found at the 
 bottom of the crucible. Some have attempt- 
 ed its reduction in vain, but Guyton, Ru- 
 precht, and Messrs Aikin and Allen, have 
 been more successful. The latter gentle- 
 men produced it from the ammoniuret. 
 From 240 grains of this substance, in acicu- 
 lar crystals, exposed for two hours to a pow- 
 erful wind furnace, in a crucible lined with 
 charcoal, they obtained a slightly cohering 
 mass of roundish grains, about the size of a 
 pin’s head, with a very brilliant metallic 
 lustre, and weighing in the whole 161 grains. 
 
 Tungsten is said to be of a greyish- white 
 or iron colour, with considerable brilliancy, 
 very hard, and brittle. Its specific gravity 
 Don d’Elhuyarts found to be 17.6; Messrs 
 Aikin and Allen, above 17.22. 
 
 * There are two oxides of tungstenum, 
 the brown, and the yellow or tungstic acid. 
 
 The brown oxide is formed by transmit- 
 ting hydrogen gas over tungstic acid, in an 
 ignited glass tube. It has a flea-brown co- 
 lour, and when heated in the air, it takes 
 fire and burns like tinder, passing into tung- 
 stic acid ; which see. 
 
 The brown oxide consists of 
 Tungstenum, 100 
 Oxygen, 16.6 — Berzel. 
 
 Hence, if we regard it as composed of 2 
 
 primes oxygen + i metal, its composition 
 will be 
 
 Tungstenum, 12.05 100. 
 
 Oxygen, 2.00 16.6 
 
 Hence the acid prime Ought probably to be, 
 12.05 “| - 5. = 15.05 or 15 ; and that of the 
 metal 12. 
 
 But from Berzelius's experiments, tung- 
 state of lime seems to consist of 
 
 Tungstic acid, 100. 14.72 
 
 Lime, 24.12 3.55 
 
 The difference indeed is not great. 
 
 Sir II. Davy found that tungstenum burns 
 with a deep red light, when heated in chlorine, 
 and forms an orange-coloured volatile sub- 
 stance, which affords the yellow oxide of 
 tungstenum, and muriatic acid, when decom- 
 posed by water.* 
 
 Scheele supposed the white powffler ob- 
 tained by digesting the ore in an acid, add- 
 ing ammonia to the residuum, and neutral- 
 izing it by nitric acid, to be pure acid of 
 tungsten. In fact it has a sour taste, red- 
 
TUli 
 
 TUT 
 
 dens litmus, forms neutral crystallizable salts 
 with alkalis, and is soluble in 20 parts of 
 boiling water. It appears however to be a 
 triple salt, composed of nitric acid, ammonia, 
 and oxide of tungsten ; from which the 
 oxide may be obtained in a yellow powder 
 by boiling with a pure concentrated acid. 
 In this state it contains about 20 per cent of 
 oxygen ; part of which may be expelled by 
 a red-heat, when it assumes a green colour. 
 
 Tungsten is insoluble in the acids; and 
 its oxide is nearly the same. It appears to 
 be capable of uniting with most other me- 
 tals, but not with sulphur. Guyton found, 
 that the oxide gives great permanence to ve- 
 getable colours. — Scheeles Essays. — Brong- 
 niart's Min. — Nich. Journ. — Phil. Mag . — 
 Murray s Chemistry. 
 
 Tumgsten of Bastnas, or False Tung- 
 sten. See Cerium. 
 
 * Turbeth Mineral. Yellow sub-deu- 
 tosulphate of mercury.* 
 
 Turnsole. Heliotropium. See Ar- 
 chil. 
 
 Turkey Stone. Cos Turcica. See 
 Whetslate. 
 
 Turmeric ( terra merita), curcuma longa, 
 is a root brought to us from the East Indies. 
 Berthollet had an opportunity of examining 
 some turmeric that came from Tobago, 
 which was superior to that which is met 
 with in commerce, both in the size of the 
 roots and the abundance of the colouring 
 particles. This substance is very rich in 
 colour, and there is no other which gives a 
 yellow colour of such brightness; but it 
 possesses no durability, nor can mordants 
 give it a sufficient degree. Common salt 
 and sal ammoniac, are those which fix the 
 colour best, but they render it deeper and 
 make it incline to brown : some recommend 
 a small quantity of muriatic acid. The root 
 must be reduced to powder to be fit for use. 
 It is sometimes employed to give the yellows 
 made with weld a gold cast, and to give an 
 orange tinge to scarlet ; but the shade the 
 turmeric imparts, soon disappears in the 
 air. 
 
 Mr Guckliche gives two processes for fix- 
 ing the colour of turmeric on silk. The 
 first consists in aluming in the cold for 
 twelve hours, a pound of silk in a solution 
 of two ounces of alum, and dyeing it hot, 
 but without boiling, in a bath composed of 
 two ounces of turmeric and a quart (mea- 
 sure) of aceto-citric acid, mixed with three 
 quarts of water. The second process con- 
 sists in extracting the colouring particles 
 from the turmeric by aceto-citric acid, in 
 the way described for Brazil wood, and in 
 dyeing the silk alumed as already mentioned 
 in this liquor, either cold or only moderately 
 warm. The colour is rendered more dura- 
 ble by this than by the former process. 
 The first parcel immersed acquires a gold 
 
 yellow ; the colour of the second and third 
 parcels is lighter, but of the same kind ; 
 that of the fourth is a straw colour. Mr 
 Guchlicho employs the same process to ex- 
 tract fine and durable colours from fustic, 
 broom, and French berries; he prepares 
 the wool by a slight aluming, to which he 
 adds a little muriatic acid. He seems to 
 content himself in these cases with vinegar 
 or some other vegetable acid, instead of his 
 aceto-citric acid, for the extraction of the co- 
 lour; he directs that a very small quantity 
 of solution of tin should be put into ti*e dye- 
 bath. 
 
 Turpentine is a resinous juice extracted 
 from several trees. Sixteen ounces of Ve- 
 nice turpentine, being distilled with water, 
 yielded four ounces and three drachms of 
 essential oil ; and the same quantity, distilled 
 without water, yielded with the heat of a 
 water-bath, two ounces only. When turpen- 
 tine is distilled or boiled with water till it 
 becomes solid, it appears yellowish ; when 
 the process is farther continued, it acquires 
 a reddish-brown colour. On distilling six- 
 teen ounces in a retort with an open fire, in- 
 creased by degrees, Neumann obtained, first, 
 four ounces of a limpid colourless oil ; then 
 two ounces and a drachm of a dark brown- 
 ish-red empyreumatic oil, of the consistence 
 of a balsam, and commonly distinguished by 
 that name. 
 
 The essential oil, commonly called spirit 
 of turpentine, cannot without singular diffi- 
 culty be dissolved in alcohol, though turpen- 
 tine itself is easily soluble in that spirit. 
 One part of the oil may be dissolved in se- 
 ven parts of alcohol ; but on standing a 
 while, the greatest part of the oil separates 
 and falls to the bottom. 
 
 * Turquois, Mineral, or Calaite. Co- 
 lours smalt-blue and apple-green. Massive, 
 disseminated, and imitative. Dull. Frac- 
 ture conchoidal or uneven. Opaque. Hard- 
 er than felspar, but softer than quartz. 
 Streak white. Sp. gr. 2.8 6 to 3.0. Its 
 constituents are, alumina 73, oxide of cop- 
 per 4.5, water 18, oxide of iron 4. — John. 
 It occurs in veins in clay-ironstone, and 
 in small pieces in alluvial clay. It has 
 been found only in the neighbourhood of 
 Nichabour, in the Khorassan, in Persia. It 
 is very highly prized as an ornamental stone 
 in Persia, and the neighbouring countries. 
 Malchite yields a green streak, but that ot 
 calaite is white. Bone turquois is phosphato 
 of lime, coloured with oxide of copper. * 
 
 Tutenag. This name is given in India 
 to the metal zinc. It is sometimes applied 
 to denote a white metallic compound, brought 
 from China, called also Chinese copper , the 
 art of making which is not known in Eu- 
 rope. It is very tough, strong, malleable, 
 may be easily cast, hammered, and polished ; 
 and the better kinds of it, when well manu- 
 
ULM 
 
 URA 
 
 factured, are very white, and not more dis- 
 posed to tarnish than silver is. Three in- 
 gredients of this compound may be dis- 
 covered by analysis ; namely, copper, zinc, 
 and iron. 
 
 Some of the Chinese white copper is said 
 to be merely copper and arsenic. 
 
 Type Metal. The basis of type metal 
 for printers is lead, and the principal article 
 used in communicating hardness is anti- 
 mony, to which copper and brass in various 
 proportions are added. The properties of 
 a good type metal are, that it should run 
 freely into the mould, and possess hardness 
 without being excessively brittle. The 
 smaller letters are made of a harder com- 
 position than those of a larger size. It does 
 not appear that our type founders are in 
 possession of a good composition for this 
 purpose. The principal defect of their 
 
 composition appears to be, that the metals 
 do not uniformly unite. In a piece of cast- 
 ing performed at one of our principal foun- 
 deries, the thickness of which was two 
 inches, I found one side hard and brittle 
 when scraped, and the other 9ide, consist- 
 ing of nearly half the piece, was soft like 
 lead. The transition from soft to hard was 
 sudden, not gradual. If a parcel of letter 
 of the same size and casting be examined, 
 some of them are brittle and hard, and re- 
 sist the knife, but others may be bent and 
 cut into shavings. It may easily be ima- 
 gined, that the duration and neatness of 
 these types must considerably vary. I have 
 been informed, but do not know the fact 
 from trial, that the types cast in Scotland 
 are harder and more uniform in their quali- 
 ties. 
 
 U 
 
 U LM IN. Dr Thomson has given this 
 temporary name to a very singular 
 substance lately examined by Klaproth. It 
 differs essentially from every other known 
 body, and must therefore constitute a new 
 and peculiar vegetable principle. It exuded 
 spontaneously from the trunk of a species of 
 elm, which Klaproth conjectures to be the 
 ulrnus nigra, and was sent to him from Pa- 
 lermo in 1 802. 
 
 1. In its external characters it resembles 
 gum. It was solid, hard, of a black colour, 
 and had considerable lustre. Its powder 
 was brown. It dissolved readily in the 
 mouth, and was insipid. 
 
 2. It dissolved speedily in a small quan- 
 tity of water. The solution was transpa- 
 rent, of a blackish-brown colour, and, even 
 when very much concentrated by evapora- 
 tion, was not in the least mucilaginous or 
 ropy ; nor did it, answer as a paste. In this 
 respect ulmin differs essentially from gum. 
 
 3. It was completely insoluble both in al- 
 cohol and ether. When alcohol was poured 
 into the aqueous solution, the greater part 
 of the ulmin precipitated in light brown 
 flakes. The remainder was obtained by 
 evaporation, and was not sensibly soluble in 
 alcohol. The alcohol by this treatment ac- 
 quired a sharpish taste. 
 
 4. When a few drops of nitric acid were 
 added to the aqueous solution, it became 
 gelatinous, lost its blackish-brown colour, 
 and a light brown substance precipitated. 
 The whole solution was slowly evaporated 
 to dryness, and the reddish-brOwn powder, 
 which remained, was treated with alcohol. 
 The alcohol assumed a golden-yellow co- 
 
 lour; and when evaporated, left a light- 
 brown, bitter, and sharp resinous substance. 
 
 5. Oxymuriatic acid produced precisely 
 the same effects as nitric. Thus it appears 
 that ulmin, by the addition of a little oxy- 
 gen, is converted into a resinous substance. 
 In this new state it is insoluble in water. 
 This property is very singular. Hitherto 
 the volatile oils were the only substances 
 known to assume the form of resins. That 
 a substance soluble in water should assume 
 the resinous form with such facility, is very 
 remarkable. 
 
 6. Ulmin when burnt emitted little smoke 
 or flame, and left a spongy but firm char- 
 coal, which, when burnt in the open air, 
 left only a little carbonate of potash behind. 
 
 Such are the properties of this curious 
 substance, as far as they have been exa- 
 mined by Klaproth. 
 
 Ultramarine. See Azure-stone. 
 
 * Umber. See Ores of Iron.* 
 
 Uranglimmer. An ore of uranium, 
 formerly called green mica, and by Werner 
 chalcolite. See the following article. 
 
 Uranite, or Uranium. A new metallic 
 substance, discovered by the celebrated 
 Klaproth in the mineral called Pechblende . 
 In this it is in the state of sulphuret. But 
 it likewise occurs as an oxide in the green 
 mica, or uranglimmer, and in the uranochre. 
 
 By treating the ores of the metal with 
 the nitric or nitro-muriatic acid, the oxide 
 will be dissolved ; and may be precipitated 
 by the addition of a caustic alkali. It is in- 
 soluble in water, and of a yellow colour ; 
 but a strong heat renders it of a brownish- 
 grey. 
 
URA 
 
 URE 
 
 To obtain it pure, the ore should be 
 treated with nitric acid, the solution evapo- 
 rated to dryness, and the residuum heated, 
 so as to render any iron it may contain in- 
 soluble. This being treated with distilled 
 water, ammonia is to be poured into the so- 
 lution, and digested with it for some time, 
 which will precipitate the uranium and re- 
 tain the copper. The precipitate, well 
 washed with ammonia, is to be dissolved in 
 nitric acid, and crystallized. The green 
 crystals, dried on blotting paper, are to be 
 dissolved in water, and recrystallized, so as 
 to get rid of the lime. Lastly, the nitrate, 
 being exposed to a red-heat, will be con- 
 verted into the yellow oxide of uranium. 
 
 It is very difficult of reduction. Fifty 
 grains, after being ignited, were formed into 
 a ball with wax, and exposed, in a well 
 closed charcoal crucible, to the most vehe- 
 ment heat of a porcelain furnace, the inten- 
 sity of which gave 170° on Wedgwood’s 
 pyrometer, d'hus a metallic button was ob- 
 tained, weighing 28 grains, of a dark grey 
 colour, hard, firmly cohering, fine grained, 
 of very minute pores, and externally, glit- 
 tering. On filing it, or rubbing it with ano- 
 ther iiard body, the metallic lustre has an 
 iron-grey colour ; but in less perfect assays 
 it verges to a brown. Its specific gravity 
 was 8.1. Bucholz, however, obtained it as 
 high as 9.0. 
 
 * There is probably but two oxides of 
 uranium ; the protoxide, which is greyish- 
 black ; and the peroxide, which is yellow. 
 
 When uranium is heated to redness in an 
 open vessel, it glows like a live coal, and 
 passes into the protoxide, which, from the 
 experiments of Schoiibert, consists of 
 Uranium, 100 15.7 
 
 Oxygen, 6.573 1.0 
 
 The precipitate thrown down by potash 
 from the nitrate solution is called the yellow 
 oxide. It consists of 
 
 Uranium, 100 51.4 = 2 primes 
 
 Oxygen, 9.559 5.0 = 3* 
 
 The oxide is soluble in dilute sulphuric 
 acid gently heated, and affords lemon co- 
 loured prismatic crystals. Its solution in 
 muriatic acid, in which it is but imperfectly 
 soluble, affords yellowish-green rbomboidal 
 tablets. Phosphoric acid dissolves it, but 
 after some time the phosphate falls down in 
 a flocculent form, and of a pale yellow co- 
 lour. 
 
 It combines with verifiable substances, 
 and gives them a brown or green-colour. 
 On porcelain, with the usual llux, it pro- 
 duces an orange. 
 
 Uranochre. An ore of uranium, con- 
 taining this metal in the oxidized state. 
 ♦See the preceding article. 
 
 * Urates. Compounds of unc or lithic 
 acid, with the salifiable bases. See Acid 
 (Lithic). * 
 
 * L rea. 1 lie best process for preparing 
 urea is to evaporate urine to the 'consistence 
 of syrup, taking care to regulate the heat 
 towards the end of the evaporation ; to add 
 very gradually to the syrup its volume of 
 nitric acid (24° Baume) of 1.20 ; to stir the 
 mixture, and immerse it in a bath of iced 
 water, to harden the crystals of the acidu- 
 lous nitrate of urea which precipitate ; to 
 wash these crystals with ice-cold water, to 
 drain them, and press them between the 
 folds of blotting paper. When we have 
 thus separated the adhering heterogeneous 
 matters, we redissolve the crystals in water, 
 and add to them a sufficient quantity of car- 
 bonate of potash, to neutralize the nitric 
 acid. We must then evaporate the new 
 liquor, at a gentle heat, almost to dryness ; 
 and treat the residuum with very pure alco- 
 hol, which dissolves only the urea. On con- 
 centrating the alcoholic solution, the urea 
 crystallizes. 
 
 The preceding is M. Thenard's process, 
 which Dr Prout has improved. lie sepa- 
 rates the nitrate of potash by crystallization, 
 makes the liquid urea into a paste with ani- 
 mal charcoal, digests this with cold water, 
 filters, concentrates, then dissolves the new 
 colourless urea in alcohol, and lastly crys- 
 tallizes. The process prescribed by Dr 
 Thomson, in the fifth edition of his System, 
 does not answer. 
 
 Urea crystallizes in four-sided prisms, 
 which are transparent and colourless, with a 
 slight pearly lustre. It has a peculiar, but 
 not urinous odour ; it does not affect litmus 
 or turmeric papers ; it undergoes no change 
 from the atmosphere, except a slight deli- 
 quescence in very damp weather. In a 
 strong heat it melts, and is partly decom- 
 posed and partly sublimed without change. 
 The sp. gr. of the crystals is about 1.35. 
 It is very soluble in water. Alcohol, at the 
 temperature of the atmosphere, dissolves about 
 20 per cent; and when boiling, considerably 
 more than its own weight, from which the 
 urea separates, on cooling, in its crystalline 
 form. The fixed alkalis and alkaline earths 
 decompose it. It unites with most of the 
 metallic oxides ; and forms crystalline com- 
 pounds with the nitric and oxalic acids.* 
 
 If cautiously introduced into a retort with 
 a wide short neck, it fuses with a gentle 
 heat : a white fume rises, which is benzoic 
 acid, and condenses on the sides of the re- 
 ceiver : crystallized carbonate of ammonia 
 succeeds, and continues to the end : neither 
 water nor oil rises, but the sublimate is 
 turned brown : the air expelled from the 
 apparatus is impregnated with a smell of 
 garlic and stinking fish : when the heat is 
 very intense, the smell is insupportable. 
 The matter in the retort is then dry, black- 
 ish, and covered with a raised white crust, 
 which rises at length in a heavy vapour, and 
 
URE 
 
 URI 
 
 attaches itself to the lower part of the retort. 
 This is muriate of ammonia. 
 
 If water be poured on the residuum, it 
 emits a smell of prussic acid. Burned on an 
 open fire it exhales the same smell, gives 
 out ammonia, and leaves one-hundredth of 
 its weight of acrid white ashes, which turn 
 syrup of violets green, and contain a small 
 quantity of carbonate of soda. 
 
 The aqueous solution, distilled by a gen- 
 tle fire, and carried to ebullition, affords 
 very clear water loaded with ammonia. By 
 adding more water, as the liquor became 
 inspissated, Fourcroy and Vauquelin ob- 
 tained nearly two-thirds of the weight of 
 the urea in carbonate of ammonia, and the 
 residuum was not then exhausted of it. The 
 latter portions, however, were more and 
 more coloured. 
 
 This decomposition of an animal sub- 
 stance at the low heat of boiling water is 
 very remarkable, particularly with respect 
 to the carbonic acid. Indeed it appears 
 that a very slight change of equilibrium is 
 sufficient to cause its constituent principles 
 to pass into the state of ammonia, and car- 
 bonic, prussic, and acetous acids. 
 
 * Urea has been recently analyzed by Dr 
 
 Prout, and M. 
 
 Berard 
 
 . The following are 
 
 its constituents 
 
 : — 
 
 
 
 Per cent. 
 
 Per cent. 
 
 Per atom. 
 
 Hydrogen, 
 
 10.80 
 
 6.66 
 
 2 — 2.5 
 
 Carbon, 
 
 19.40 
 
 19.99 
 
 1 = 7.5 
 
 Oxygen, 
 
 26.40 
 
 26.66 
 
 1 = 10.0 
 
 Azote, 
 
 43.40 
 
 46.66 
 
 1 = 17.5 
 
 100.00 
 
 100.00 
 
 37.5 
 
 See Sugar for some reitiarks on the rela- 
 tion between it and urea. Uric, or lithic 
 acid, is a substance quite distinct from urea 
 in its composition. This fact, according to 
 Dr Prout, explains, why an excess of urea 
 generally accompanies the phosphoric dia- 
 thesis, and not the lithic. Fie has several 
 times seen urea as abundant in the urine of 
 a person where the phosphoric diathesis pre- 
 vailed, as to crystallize spontaneously on the 
 addition of nitric acid, without being con- 
 centrated by evaporation. 
 
 As urea and uric acid, says Dr Berard, 
 are the most azotized of all animal substan- 
 ces, the secretion of urine appears to have for 
 its object, the separation of the excess of 
 azote from the blood, as respiration separates 
 from it the excess of carbon.* 
 
 Urea has a singular effect on the crystal- 
 lization of some salts. If muriate of soda be 
 dissolved in a solution of urea, it will crys- 
 tallize by evaporation, not in cubes, but in 
 octaedra; muriate of ammonia, on the con- 
 trary, treated in the same way, instead of 
 crystallizing in octaedra, will assume the 
 cubic form. The same effect is produced, 
 if fresh urine be employed. 
 
 UrJc Acid. See Acid (Lithic). 
 
 Urine. This cxcrementitious fluid, in 
 its natural state, is transparent, of a yellow 
 colour, a peculiar smell and saline taste. Its 
 production as to quantity, and in some 
 measure quality, depends on the seasons and 
 the peculiar constitution of the individual, 
 and is likewise modified by disease. It is 
 observed, that perspiration carries off' more 
 or less of the fluid, which would else have 
 passed off by urine ; so that the profusion 
 of the former is attended with a diminution 
 of the latter. 
 
 From the alkaline smell of urine kept for 
 a certain time, and other circumstances, it 
 was formerly supposed to be an alkaline 
 fluid ; but by its reddening paper stained 
 blue with litmus or the juice of radishes, 
 it appears to contain an excess of acid. 
 
 The numerous researches made concern- 
 ing urine have given the following as its 
 component parts: 1, water, 2, urea, 3, phos- 
 phoric acid, 4, 5, 6, 7, phosphates of lime, 
 magnesia, soda, and ammonia, 8, 9, 10, 11, 
 lithic, rosacic, benzoic, and carbonic acid, 12, 
 carbonate of lime, 13, 14, muriates of soda 
 and ammonia, 15, gelatin, 16, albumen, 17, 
 resin, 18, sulphur. 
 
 Muriate of potash may sometimes be de- 
 tected in urine, by cautiously dropping into 
 it some tartaric acid ; as may sulphate of 
 soda, or of lime, by a solution of muriate of 
 barytes, which will throw down sulphate of 
 barytes together with its phosphate ; and 
 these may be separated by a sufficient quan- 
 tity of muriatic acid, which will take up the 
 latter. 
 
 Urine soon undergoes spontaneous chan- 
 ges, which are more or less speedy and 
 extensive, according to its state, as well as 
 the temperature of the air. Its smell, when 
 fresh made* and healthy, is somewhat fra- 
 grant; but this presently goes off', and is 
 succeeded by a peculiar odour termed uri- 
 nous. As it begins to be decomposed, its 
 smell is not very unlike that of sour milk ; 
 but this soon changes to a fetid, alkaline 
 odour. It must be observed, however, that 
 turpentine, asparagus, and many other vege- 
 table substances, taken as medicine, or used 
 as food, have a very powerful effect on the 
 smell of the urine. Its tendency to putre- 
 faction depends almost wholly on the quan- 
 tity of gelatin and albumen it contains; in 
 many cases, where these are abundant, it 
 comes on very quickly indeed. 
 
 * According to Berzelius, healthy human 
 urine is composed of, water 95.3, urea 30.10, 
 sulphate of potash 3.71, sulphate of soda 
 3.16, phosphate of soda 2.94, muriate of 
 soda 4.45, phosphate of ammonia 1.65, mu- 
 riate of ammonia 1.50, free acetic acid, with 
 lactate of ammonia, animal matter soluble in 
 alcohol, urea adhering to the preceding, al- 
 together 17.14, earthy phosphates with a 
 
VAP 
 
 VAR 
 
 trace of fluate of lime 1.0, uric acid 1, mucus 
 of the bladder 0.32, silica 0.03, in 1000.0. 
 The phosphate of ammonia and soda, obtain- 
 ed from urine, by removing by alcohol the 
 urea from its crystallized salts, was called 
 fusible salt of urine , or microcosmic salt ; 
 and was much employed in experiments with 
 the blow-pipe. 1 * 
 
 The changes produced in urine by disease 
 are considerable, and of importance to be 
 known. It is of a red colour, small in quan- 
 tity, and peculiarly acrid, in inflammatory 
 diseases; but deposits no sediment on stand- 
 ing. Corrosive muriate of mercury throws 
 down from it a copious precipitate. Toward 
 the termination of such diseases, it becomes 
 more abundant, and deposits a copious pink- 
 coloured sediment, consisting of rosacic acid, 
 with a little phosphate of lime and uric acid. 
 
 In jaundice it contains a deep yellow co- 
 louring matter, capable of staining linen. 
 Muriatic acid renders it green, and this in- 
 dicates the presence of bile. Sometimes, too, 
 according to Fourcroy and Vauquelin, it 
 contains a substance analogous to the yellow 
 acid, which they formed by the action of 
 nitric acid on muscular fibre. 
 
 In hysterical affections it is copious, lim- 
 pid, and colourless, containing much salt, 
 but scarcely any urea or gelatin. 
 
 In dropsy the urine is generally loaded 
 with albumen, so as to become milky, or 
 even coagulate by heat, or on the addition 
 of acids. In dropsy from diseased liver, 
 however, no albumen is present ; but the 
 urine is scanty, high coloured, and deposits 
 the pink- coloured sediment. 
 
 In dyspepsy, or indigestion, the urine 
 abounds in gelatin, and putrefies rapidly. 
 
 In rickets, the urine contains a great deal 
 of a calcareous salt, which has been suppos- 
 ed to be phosphate of lime, but according to 
 Bonhomme it is the oxalate. 
 
 Some instances are mentioned, in which 
 females have voided urine of a milky appear- 
 ance, and containing a certain portion of the 
 caseous part of milk. 
 
 But among the most remarkable altera- 
 tions of urine is that in the diabetes, when 
 the urine is sometimes so loaded with sugar, 
 as to be capable of being fermented into a 
 vinous liquor. Upwards of one-twelfth of 
 its weight of sugar was extracted from some 
 diabetic urine by Cruickshank, which was at 
 the rate of twenty-nine ounces troy a-day 
 from one patient. In this disease, how- 
 ever, the urine, though always in very large 
 quantity, is sometimes not sweet, but in- 
 sipid. 
 
 The urine of some animals, examined by 
 Fourcroy, Vauquelin, and Rouelle, jun. ap- 
 pears to differ from that of man in wanting 
 the phosphoric and lithic acids, and contain- 
 ing the benzoic. That of the horse, accord- 
 ing to the former two, consists of benzoate of 
 soda .024, carbonate of lime .01 1, carbonate 
 of soda .009, muriate of potash .009, urea 
 .007, water and mucilage .940. Giese, 
 however, observes, that the proportion of 
 benzoate of soda varies greatly, so that some- 
 times scarcely any can be found. Notwith- 
 standing the assertions of these chemists, 
 that the urine of the horse contains no phos- 
 phoric acid, Giobert affirms that phosphorus 
 may be made from it. 
 
 That of the cow, according to Rouelle, 
 contains carbonate, sulphate, and muriate of 
 potash, benzoic acid, and urea : that of the 
 camel differed from it in affording no ben- 
 zoic acid : that of the rabbit, according to 
 Vauquelin, contains the carbonates of lime, 
 magnesia, and potash, sulphates of potash and 
 lime, muriate of potash, urea, gelatin, and 
 sulphur. All these appear to contain some 
 free alkali, as they turn syrup of violets green. 
 In the urine of domestic fowls, Fourcroy and 
 Vauquelin found lithic acid. 
 
 Urine has been employed for making 
 phosphorus, volatile alkali, and sal ammo- 
 niac ; moulds to the produce of nitre-beds ; 
 and it is very useful in a putrid state for 
 scouring woollens. 
 
 * Urinary Calculi. See Calculi (Uri- 
 nary).* 
 
 * T 7 A POUR. The general principles of 
 V the formation of vapour have been 
 explained under the article Caloric, changes 
 of state. Some observations have been add- 
 
 ed under Evaporation and Gas. 
 
 Fig. 15. plate XIV. represents one form- 
 of the apparatus, which I employed for de- 
 termining the elastic force of vapours at dif- 
 ferent temperatures. L, 1, are the initial 
 levels of the mercurial columns in the two 
 legs of the syphon barometer. /, is the fine 
 wire of platina, to which the quicksilver was 
 
 made a tangent, at every measurement, by 
 pouring mercury into the open leg, till its 
 vertical pressure equipoised the elastic force 
 of the vapour above l. The column added 
 over L, measured directly that elastic force. 
 Sec the Tables in the Appendix.’' 
 
 * Varec. The French name for kelp, or 
 incinerated sea-weed.* 
 
 Varnish. Lac varnishes or lacquers con- 
 sist of different resins in a state ot solution, 
 of which the most common are mastich, 
 sandarach, lac, benzoin, copal, amber, and 
 
VAR 
 
 VAR 
 
 asphaltum. The menstrua are either expres- 
 sed or essential oils, as also alcohol. For a 
 lac varnish of the first kind, the common 
 painter’s varnish is to be united by gently 
 boiling it with some more mastich or colo- 
 phony, and then diluted again with a little 
 more oil of turpentine. The latter addition 
 promotes both the glossy appearance and 
 drying of the varnish. 
 
 Of this sort is the amber-varnish. To 
 make this varnish, half a pound of amber is 
 kept over a gentle fire in a covered iron pot, 
 in the lid of which there is a small hole, till 
 it is observed to become soft, and to be melt- 
 ed together into one mass. As soon as this 
 is perceived, the vessel is taken from off the 
 fire, and suffered to cool a little ; when a 
 pound of good painter’s varuish is added to 
 it, and the whole suffered to boil up again 
 over the fire, keeping it continually stirring. 
 After this, it is again removed from the fire ; 
 and when it isbecome somewhat cool, a pound 
 of oil of turpentine is to be gradually mixed 
 with it. Should the varnish, when it is cool, 
 happen to be yet too thick, it may be attenu- 
 ated with more oil of turpentine. This var- 
 nish has always a dark-brown colour, because 
 the amber is previously half burned in this 
 operation ; but if it be required of a blight 
 colour, amber powder must be dissolved in 
 transparent painter’s varnish, in Papin’s ma- 
 chine, by a gentle fire. 
 
 As an instance of the second sort of lac- 
 varnishes with ethereal oils alone, may be 
 adduced the varnish made with oil of tur- 
 pentine. For making this, mastich alone is 
 dissolved in oil of turpentine by a very gen- 
 tle digesting heat, in close glass vessels. This 
 is the varnish used for the modern trans- 
 parencies employed as window-blinds, fire- 
 screens, and for other purposes. These are 
 commonly prints, coloured on both sides, 
 and afterwards coated with this varnish on 
 those parts that are intended to be transpa- 
 rent. Sometimes fine thin calico, or Irish 
 linen, is used for this purpose ; but it re- 
 quires to be primed with a solution of isin- 
 glass, before the colour is laid on. 
 
 Copal may be dissolved in genuine Cliio 
 turpentine, according to Mr Sheldrake, by 
 adding it in powder to the turpentine pre- 
 viously melted, and stirring till the whole is 
 fused. Oil of turpentine may then be add- 
 ed, to dilute it sufficiently. Or the copal in 
 powder may be put into a long-necked ma- 
 trass with twelve parts of oil of turpentine, 
 and digested several days on a sand-heat, 
 frequently shaking it. This may be diluted 
 with one-fourth or one-fifth of alcohol. Me- 
 tallic vessels or instruments, covered with 
 two or three coats of this, and dried in an 
 oven each time, may be washed with boiling 
 water, or even exposed to a still greater heat, 
 without injury to the varnish. 
 
 A varnish of the consistence of thin tur- 
 
 pentine is obtained for aerostatic machines, 
 by the digestion of one part of elastic gum, 
 or caoutchouc, cut into small pieces, in 
 thirty-two parts of rectified oil of turpentine. 
 Previously to its being used, however, it 
 must be passed through a linen cloth, in 
 order that the undissolved parts may be left 
 behind. 
 
 The third sort of lac-varnishes consists in 
 the spirit-varnish. The most solid resins 
 yield the most durable varnishes; but a 
 varnish must never be expected to be harder 
 than the resin naturally is of which it is 
 made. Hence, it is the height of absurdity 
 to suppose, that there are any incombustible 
 varnishes, since there is no such thing as an 
 incombustible resin. But the most solid 
 resins by themselves produce brittle varnishes; 
 therefore, something of a softer substance 
 must always be mixed with them, whereby 
 this brittleness is diminished. For this pur- 
 pose gum-elemi, turpentine, or balsam of 
 copaiva are employed in proper proportions. 
 For the solution of these bodies the strongest 
 alcohol ought to be used, which may very 
 properly indeed be distilled over alkali, but 
 must not have stood upon alkali. The ut- 
 most simplicity in composition with respect 
 to the number of the ingredients in a for- 
 mula is the result of the greatest skill in the 
 art ; hence it is no wonder, that the greatest 
 part of the formulas and recipes that we 
 meet with, are composed without any prin- 
 ciple at all. 
 
 In conformity to these rules, a fine co- 
 lourless varnish may he obtained, by dissolv- 
 ing eight ounces of gum-sandarach and two 
 ounces of Venice turpentine in thirty-two 
 ounces of alcohol by a gentle heat. Five 
 ounces of shell-lac and one of turpentine, dis- 
 solved in thirty- two ounces of alcohol by a 
 very gentle heat, give a harder varnish, but 
 of a reddish cast. To these the solution of 
 copal is undoubtedly preferable in many re- 
 spects. This is effected by triturating an 
 ounce of powder of gum-copal, which has 
 been well dried by a gentle heat, with a 
 drachm of camphor, and, while these are 
 mixing together, adding by degrees four 
 ounces of the strongest alcohol, without any 
 digestion. 
 
 Between this and the gold-varnish there 
 is only this difference, that some substances 
 that communicate a yellow tinge are to he 
 added to the latter. The most ancient de- 
 scription of two sorts of it, one of which 
 w r as prepared with oil, and the other with 
 alcohol, is to be found in Alexius Pedemon- 
 tanus De i Secreti, Lucca, of which the first 
 edition was published in the year 1557. But 
 it is better prepared, and more durable, 
 when made after the following prescription : 
 — Take two ounces of shell-lac, of arnatto 
 and turmeric of each one ounce, and thirty 
 grains of fine dragon’s-blood, and make an 
 
VEG 
 
 VEG 
 
 extract with twenty ounces of alcohol in a 
 gentle heat. 
 
 Oil-varnishes are commonly mixed imme- 
 diately with the colours, but lac or lacquer- 
 varnishes are laid on by themselves upon a 
 burnished coloured ground ; when they are 
 intended to be laid upon naked wood, a 
 ground should be first given them of strong 
 size, either alone or with some earthy colour, 
 mixed up with it by levigation. The gold 
 lacquer is simply rubbed over brass, tin, or 
 silver, to give them a gold colour. 
 
 Before a resin is dissolved in a fixed oil, 
 it is necessary to render the oil drying. For 
 this purpose the oil is boiled with metallic 
 oxides, in which operation the mucilage of 
 the oil combines with the metal, while the 
 oil itself unites with the oxygen of the oxide. 
 To accelerate the drying of this varnish, it 
 is necessary to add oil of turpentine. 
 
 The essential varnishes consist of a solu- 
 tion of resin in oil of turpentine. The var- 
 nish being applied, the essential oil Hies off, 
 and leaves the resin. This is used only for 
 paintings. 
 
 When resins are dissolved in alcohol, the 
 varnish dries very speedily, and is subject 
 to crack ; but this fault is corrected by add- 
 ing a small quantity of turpentine to the 
 mixture, which renders it brighter, and less 
 brittle when dry. 
 
 The coloured resins or gums, such as 
 gamboge, dragon’s-blood, &c. are used to 
 colour varnishes. 
 
 To give lustre to the varnish after it is 
 laid on, it is rubbed with pounded pumice- 
 stone aud water ; which being dried with a 
 cloth, the w'ork is afterward rubbed with 
 an oiled rag and tripoli. The surface is last 
 of all cleaned with soft linen cloths, cleared 
 of all greasiness with powder of starch, and 
 rubbed bright with the palm of the hand. 
 
 Vegetable Kingdom. In the mineral 
 kingdom, little of chemical operation takes 
 place, wherein the peculiar locality or dis- 
 position of the principles which act upon 
 each other, appears to have any considerable 
 effect. The principles, for the most part 
 simple, act upon each other by virtue of 
 their respective attractions : if heat be de- 
 veloped, it is for the most part speedily con- 
 ducted away; if elastic products be extri- 
 cated, they in general make their escape ; — 
 in a word, we seldom perceive in the opera- 
 tions in the mineral kingdom any arrange- 
 ment, which at all resembles the artificial 
 dispositions of the chemist. 
 
 But in the animal and vegetable king- 
 doms it is far otherwise. In the former of 
 these, bodies are regularly changed by me- 
 chanical division, by digestion, and the ap- 
 plication of peculiar solvents, in a tempera- 
 ture exceeding that of the atmosphere, and 
 the w'hole of the effects are assisted, modi- 
 fied, and kept up by an apparatus for ad- 
 
 
 mitting the air of the atmosphere. The 
 subjects of the vegetable kingdom possess 
 undoubtedly a structure less elaborate. They 
 exhibit much less of those energies, which 
 are said to be spontaneous. The form of 
 their vessels is much simpler, and, as far as 
 we can perceive, their action is obedient to 
 the changes of the atmosphere in quality 
 and moisture, the mechanical action of w inds, 
 the temperature of the weather, and the 
 influence of light. In these organized beings, 
 the chemist discovers principles of a more 
 compounded nature, than any which can be 
 obtained from the mineral kingdom. These 
 do not previously exist in the earth, and 
 must therefore be results of vegetable life. 
 
 The most obvious difference between ve- 
 getables and animals is, that the latter are 
 in general capable of conveying themselves 
 from place to place ; whereas vegetables* 
 being fixed in the same place, absorb, by 
 means of their roots and leaves, such sup- 
 port as is wdthin their reach. This appears 
 on the whole to consist of air and water. 
 The greatest part of the support of animals 
 are the products already elaborated in the 
 vegetable kingdom. The products of these 
 two kingdoms in the hands of the chemist 
 are remarkably different, though perhaps 
 not exclusively so. One of the most di- 
 stinctive characters seems to be the presence 
 of nitrogen or azotic gas, which may be ex- 
 tricated from animal substances by the ap- 
 plication of nitric acid, and enters into the 
 composition of the ammonia afforded by dc* 
 structive distillation. It was long supposed, 
 that ammonia was exclusively the product 
 of the animal kingdom, but it is now’ well 
 known, that certain plants likewise afford it. 
 
 When it is considered, that by far the 
 greater part of every organized substance 
 is capable of assuming the elastic form, and 
 being volatilized by heat ; that the products 
 are during life brought into combination by 
 slow and long-continued processes, and are 
 kept separate from each other in the vessels 
 of the plant or animal ; that these combina- 
 tions are liable to be altered by the destruc- 
 tion of those vessels, as well as by every not- 
 able change of temperature — it will not ap- 
 pear surprising, that the chemical analysis of 
 plants should be in an imperfect state. 
 
 See 
 
 Analysis. 
 
 In the structure of vegetables we observe 
 the external covering or bark, the ligneous 
 or woody matter, the vessels or tubes, and 
 certain glandular or knotty parts, 1 he com- 
 parative anatomy, and immediate uses of 
 these parts, form an object of interesting 
 research, but less immediately within the 
 province of a chemical work. 
 
 The nutrition or support of plants ap- 
 pears to require water, earth, light, and air. 
 There are various experiments, which ha\e 
 been instituted to show’, that water is the 
 
VEG 
 
 VEG 
 
 only aliment, which the root draws from 
 the earth. Van Helmont planted a willow, 
 weighing fifty pounds, in a certain quantity 
 of earth covered with sheet-lead ; he water- 
 ed it for five years with distilled water ; and 
 at the end of that time the tree weighed one 
 hundred and sixty-nine pounds three ounces, 
 and the earth in which it had vegetated was 
 found to have suffered a loss of no more 
 than three ounces. Boyle repeated the same 
 experiment upon a plant, which at the end 
 of two years weighed fourteen pounds more, 
 without the earth in which it had vegetated 
 having lost any perceptible portion of its 
 weight. 
 
 Messrs Duhamel and Bonnet supported 
 plants with moss, and fed them with mere 
 water : they observed, that the vegetation 
 was of the most vigorous kind ; and the na- 
 turalist of Geneva observes, that the flowers 
 were more odoriferous, and the fruit of a 
 higher flavour. Care was taken to change 
 the supports before they could suffer any 
 alteration. Mr Tillet has likewise raised 
 plants, more especially of the gramineous 
 kind, in a similar manner, with this differ- 
 ence only, that his supports were pounded 
 glass, or quartz in powder. Hales has ob- 
 served, that a plant, which weighed three 
 pounds, gained three ounces after a heavy 
 dew. Do we not every day observe hya- 
 cinths and other bulbous plants, as well as 
 gramineous plants, raised in saucers or bot- 
 tles containing mere water? And Braconnot 
 has lately found mustard-seed to germinate, 
 grow, and produce plants, that came to ma- 
 turity, flowered, and ripened their seed, in 
 litharge, flowers of sulphur, and very small 
 unglazed shot. The last appeared least fa- 
 vourable to the growth of the plants, ap- 
 parently because their roots could not pe- 
 netrate between it so easily. 
 
 All plants do not demand the same quan- 
 tity of water ; and nature has varied the 
 organs of the several individuals conforma- 
 bly to the necessity of their being supplied 
 with this food. Plants which transpire little, 
 such as the mosses and the lichens, have no 
 need of a considerable quantity of this fluid ; 
 and accordingly they are fixed upon dry 
 rocks, and have scarcely any roots ; but 
 plants which require a larger quantity, have 
 roots which extend to a great distance, and 
 absorb humidity throughout their whole sur- 
 face. 
 
 The leaves of plants have likewise the 
 property of absorbing water, and of extract- 
 ing from the atmosphere the same principle 
 which the root draws from the earth. But 
 plants which live in the water, and as it were 
 swim in the element which serves them for 
 food, have no need of roots ; they receive the 
 fluid at all their pores; and we accordingly 
 find, that the fucus, the ulva, &c. have no 
 roots whatever. 
 
 o 
 
 The dung, which is mixed with earths, 
 and decomposed, not only affords the ali- 
 mentary principles we have spoken of, but 
 likewise favours the growth of the plant by 
 that constant and steady heat, which its ul- 
 terior decomposition produces. Thus it is 
 that Fabroni affirms his having observed 
 the development of leaves and flowers in 
 that part of a tree only, which was in the 
 vicinity of a heap of dung. 
 
 From the preceding circumstances it ap- 
 pears, that the influence of the earth in ve- 
 getation is almost totally confined to the 
 conveyance of water, and probably the elas- 
 tic products from putrefying substances to 
 the plant. 
 
 Vegetables cannot live without air. From 
 the experiments of Priestley, Ingenhousz, 
 and Sennebier, it is ascertained, that plants 
 absorb the azotic part of the atmosphere ; 
 and this principle appears to be the cause of 
 the fertility which arises from the use of 
 putrefying matters in the form of manure. 
 The carbonic acid is likewise absorbed by 
 vegetables, w r hen its quantity is small. If 
 in large quantity, it is fatal to them. 
 
 Chaptal has observed, that carbonic acid 
 predominates in the fungus, and other sub- 
 terraneous plants. But by causing these 
 vegetables, together with the body upon 
 which they were fixed, to pass, by imper- 
 ceptible gradations, from an almost absolute 
 darkness, into the light, the acid very nearly 
 disappeared ; the vegetable fibres being pro- 
 portionally increased, at the same time that 
 the resin and colouring principles were de- 
 veloped, wdiich he ascribes to the oxygen of 
 the same acid. Sennebier has observed, that 
 the plants wdiich he watered with water im- 
 pregnated with carbonic acid, transpired an 
 extraordinary quantity of oxygen, which like- 
 wise indicates a decomposition of the acid. 
 
 Light is almost absolutely necessary to 
 plants. In the dark they grow r pale, lan- 
 guish, and die. The tendency of plants to- 
 ward the light is remarkably seen in such 
 vegetation as is effected in a chamber or 
 place where the light is admitted on one 
 side ; for the plant never fails to grow in 
 that direction. Whether the matter of light 
 be condensed into the substance of plants, 
 or whether it act merely as a stimulus or 
 agent, without which the other requisite che- 
 mical processes cannot be effected, is uncer- 
 tain. 
 
 It is ascertained, that the processes in 
 plants serve, like those in animals, to pro- 
 duce a more equable temperature, which is 
 for the most part above that of the atmos- 
 phere. Dr Hunter, quoted by Chaptal, ob- 
 served by keeping a thermometer plunged in 
 a hole made in a sound tree, that it con- 
 stantly indicated a temperature several de- 
 grees above that of the atmosphere, when 
 it was below the fifty-sixth division of Fall* 
 V 
 
VEG 
 
 VEG 
 
 renheit ; whereas the vegetable heat, in hot- 
 ter weather, was always several degrees be- 
 low that of the atmosphere. The same phi- 
 losopher has likewise observed, that the sap 
 which, out of the tree, would freeze at 32°, 
 did not freeze in the tree unless the cold 
 were augmented 15° more. 
 
 1 he vegetable heat may increase or di- 
 minish by several causes, of the nature of 
 disease ; and it may even become percepti- 
 ble to the touch in very cold weather, ac- 
 cording to Buflfon. 
 
 The principles of which vegetables are 
 composed, if w r e pursue their analysis as 
 far as our means have hitherto allowed, are 
 chiefly carbon, hydrogen, and oxygen. Ni- 
 trogen is a constituent principle of several, 
 but for the most part in small quantity. 
 Potash, soda, lime, magnesia, silex, alu- 
 mina, sulphur, phosphorus, iron, manganese, 
 and muriatic acid, have likewise been rec- 
 koned in the number ; but some of these oc- 
 cur only occasionally, and chiefly in very 
 small quantities; and are scarcely more en- 
 titled to be considered as belonging to them 
 than gold, or some other substances, that 
 have been occasionally procured from their 
 decomposition. 
 
 The follow ing are the principal products 
 of vegetation : — 
 
 1. Sugar. Crystallizes. Soluble in water 
 and alcohol. Taste sweet. Soluble in nitric 
 acid, and yields oxalic acid. 
 
 2. Sarcocol. Does not crystallize. Solu- 
 ble in water and alcohol. Taste bitter sw eet. 
 Soluble in nitric acid, and yields oxalic acid. 
 
 3. Asparagin . Crystallizes. Taste cool- 
 ing and nauseous. Soluble in hot water. 
 Insoluble in alcohol. Soluble in nitric acid, 
 and converted into bitter principle and arti- 
 ficial tannin. 
 
 4. Gum . Does not crystallize. Taste in- 
 sipid. Soluble in water, and forms muci- 
 lage. Insoluble in alcohol. Precipitated by 
 silicated potash. Soluble in nitric acid, and 
 forms mucous and oxalic acids. 
 
 5. Ulmin. Does not crystallize. Taste 
 insipid. Soluble in water, and does not 
 form mucilage. Precipitated by nitric and 
 oxymuriatic acids in the state of resin. In- 
 soluble in alcohol. 
 
 6. Inulin. A white powder. Insoluble in 
 cold water. Soluble in boiling water ; but 
 precipitates unaltered after the solution 
 cools. Insoluble in alcohol. Soluble in 
 nitric acid, and yields oxalic acid. 
 
 7. Starch. A white powder. Taste in- 
 sipid. Insoluble in cold water. Soluble in 
 hot w'ater; opaque and glutinous. Precipi- 
 tated by an infusion of nutgalls ; precipitate 
 redissolved by a heat of 120°. Insoluble in 
 alcohol. Soluble in dilute nitric acid, and 
 precipitated by alcohol. With nitric acid 
 yields oxalic acid and a waxy matter. 
 
 8. Indigo. A blue powder. Taste insi- 
 
 pid, Insoluble in water, alcohol, ether. So- 
 luble in sulphuric acid. Soluble in nitric 
 acid, and converted into bitter principle 
 and artificial tannin. 
 
 9. Gluten. Forms a ductile elastic mass 
 with w'ater. Partially soluble in water ; pre- 
 cipitated by infusion of nutgalls and oxy- 
 genized muriatic acid. Soluble in acetic 
 acid and muriatic acid. Insoluble in alco- 
 hol. By fermentation becomes viscid and 
 adhesive, and then assumes the properties 
 of cheese. Soluble in nitric acid, and yields 
 oxalic acid. 
 
 10. Albumen. Soluble in cold water. Co- 
 agulated by heat, and becomes insoluble. 
 Insoluble in alcohol. Precipitated by infu- 
 sion of nutgalls. Soluble in nitric acid. 
 Soon putrefies. 
 
 11. Fibrin. Tasteless. Insoluble in water 
 and alcohol. Soluble in diluted alkalis, and 
 in nitric acid. Soon putrefies. 
 
 12. Gelatin. Insipid. Soluble in water. 
 Does not coagulate when heated. Precipi- 
 tated by infusion of galls. 
 
 13. Bitter principle. Colour yellow or 
 brown. Taste bitter. Equally soluble in 
 water and alcohol. Soluble in nitric acid. 
 Precipitated by nitrate of silver. 
 
 1 4. Extractive. Soluble In water and al- 
 cohol. Insoluble in ether. Precipitated by 
 oxygenized muriatic acid, muriate of tin, and 
 muriate of alumina ; but not by gelatin. 
 Dyes fawn colour. 
 
 15. Tannin. Taste astringent. Soluble 
 in water and in alcohol of 0.810. Precipi- 
 tated by gelatin, muriate of alumina, and 
 muriate of tin. 
 
 16. Fixed oils. No smell. Insoluble in 
 w^ater and alcohol. Forms soaps with al- 
 kalis. Coagulated by earthy and metallic 
 salts. 
 
 17. Wax. Insoluble in w'ater. Soluble 
 in alcohol, ether, and oils. Forms soap with 
 alkalis. Fusible. 
 
 18. Volatile oil. Strong smell. Insoluble 
 in water. Soluble in alcohol. Liquid. Vo- 
 latile. Oily. By nitric acid inflamed, and 
 converted into resinous substances. 
 
 19. Camphor. Strong odour. Crystal- 
 lizes. Very little soluble in w'ater. Soluble 
 in alcohol, oils, acids. Insoluble in alkalis. 
 Burns with a clear flame, and volatilizes be- 
 fore melting. 
 
 20. Birdlime. Viscid. Taste insipid. In- 
 soluble in w r ater. Partially soluble in al- 
 cohol. Very soluble in ether. Solution 
 green. 
 
 21. Resins. Solid. Melt when heated. 
 Insoluble in water. Soluble in alcohol, 
 ether, and alkalis. Soluble in acetic acid. 
 By nitric acid converted into artificial tan- 
 nin. 
 
 22. Guaiacum. Possesses the characters 
 of resins ; but dissolves in nitric acid, and 
 yields oxalic acid and no tannin. 
 
VEG 
 
 VER 
 
 23. Balsams . Possess the characters of 
 the resins, but have a strong smell ; when 
 heated, benzoic acid sublimes. It sublimes 
 also when they are dissolved in sulphuric 
 acid. By nitric acid converted into artifi- 
 cial tannin. 
 
 24. Caoutchouc . Very elastic. Insoluble 
 in water and alcohol. When steeped in 
 ether reduced to a pulp, which adheres to 
 every thing. Fusible, and remains liquid. 
 Very combustible. 
 
 25. Gum resins. Form milky solutions 
 with wafer, transparent with alcohol. So- 
 luble in alkalis. With nitric acid converted 
 into tannin. Strong smell. Brittle, opaque, 
 infusible. 
 
 26. Cotton. Composed of fibres. Taste- 
 less. Very combustible. Insoluble in wa- 
 ter, alcohol, and ether. Soluble in alkalis. 
 Yields oxalic acid to nitric acid. 
 
 27. Suber . Burns bright, and swells. Con- 
 verted by nitric acid into suberic acid and 
 wax. Partially soluble in water and alcohol. 
 
 28. Wood. Composed of fibres. Taste- 
 less. Insoluble in water and alcohol. So- 
 luble in weak alkaline lixivium. Precipi- 
 tated by acids. Leaves much charcoal when 
 distilled in a red-heat. Soluble in nitric 
 acid, and yields oxalic acid. 
 
 * To the preceding we may add, emetin, 
 fungin, hematin, nicotin, pollenin, the new 
 vegetable alkalis, aconita, atropia, brucia, 
 cicuta, datura, delphia, byosciama, morphia, 
 picrotoxia, strychnia, veratria ; and the va- 
 rious vegetable acids, enumerated under the 
 general article Acid.* 
 
 Vegetation (Saline). M. Chaptal has 
 given us a good memoir on this subject, in 
 the Journal de Physique, for October ] 788, 
 entitled Observations on the Influence of the 
 Air and Light upon the Vegetation of Salts. 
 
 In the operations in the large way, of his 
 manufactory of medical and chemical pro- 
 ducts, he often observed that salts, particu- 
 larly the metallic, vegetated on the side most 
 exposed to the light, and the frequency of 
 the effect induced him to make some direct 
 experiments on the subject. For this pur- 
 pose he took several capsules of glass, and 
 covered the half of each, as well above as 
 below, with black silk. At the same time, 
 he prepared solutions of almost all the earth}', 
 alkaline, or metallic compound salts in c}is- 
 tilled water, at the temperature of the atmos- 
 phere. These capsules were placed on ta- 
 bles in a well closed chamber, which had no 
 chimney, and of which the doors and win- 
 dows were carefully stopped up, in order 
 that the evaporation might not be hastened 
 by any agitation of the air. Reflected light, 
 by which I understand the light from the 
 clouds, was admitted through a small aper- 
 ture in one of the window-shutters. By this 
 management, as well as the disposition of 
 the capsules, onc-half of each of their respec- 
 
 tive cavities received light from the apciture, 
 and the other was almost perfectly in dar - 
 ness. The solutions were then caiefu y 
 poured into the capsules by means of a fun- 
 nel resting on the middle of the bottom, so 
 that the border of the fluid was neat and uni- 
 form, without any irregularity or drop of the 
 fluid falling on the bare surface of the glass. 
 
 Upwards of two hundred experiments 
 were made, with variations of the principal 
 trials, so as to leave no doubt with regard to 
 the constancy of the results. The most re- 
 markable fact is, that the vegetation took 
 place on those surfaces only which w r ere illu- 
 minated. This phenomenon w'as so striking 
 in most of the solutions, that in the space of 
 a few r days, and frequently even within one 
 single day, the salt was elevated several lines 
 above the liquor upon the enlightened sur- 
 face, while there did not appear the smallest 
 crust or edge on the dark part. Nothing 
 could be more interesting, than to observe 
 this vegetation, projecting frequently more 
 than an inch, and marking the line of dis- 
 tinction between the illuminated and dark 
 parts of the vessel. The sulphates of iron, 
 of zinc, and other metals, more especially 
 presented this appearance. It was generally 
 observed, that the vegetation was strongest 
 toward the most enlightened part. 
 
 This phenomenon may be rendered still 
 more interesting, by directing the vegetation 
 at pleasure toward the different parts of the 
 vessel. For this purpose, nothing more is 
 required than to cover the several parts in 
 succession. For the vegetation always takes 
 place in the enlightened parts, and quickly 
 ceases in that which is covered. 
 
 When the same solution has stood for se- 
 veral days, the insensible evaporation gra- 
 dually depresses its surface, and a crust or 
 edge of salt is left in the obscure part. But 
 the salt never rises, or at least very imper- 
 fectly, above the liquor, and cannot be com- 
 pared with the true vegetation. 
 
 When salts are suffered to vegetate in this 
 manner, the spontaneous evaporation of the 
 fluid affords very few crystals. All the saline 
 matter extends itselfon the sides of the vessel. 
 
 Veins. The ores of metals are frequently 
 found to fill certain clefts in mountains. 
 These masses, when they run out in length, 
 are called veins. Inconsiderable veins, which 
 diverge from the principal, are called slips ; 
 and such masses of ore as are of consider- 
 able magnitude, but no great length, are 
 called bellies, or stock- works. 
 
 * Veratria. A new vegetable alkali, 
 discovered lately by MM. Pelletier and Ca- 
 ventou, in the veratrum sabatilla, or eeva- 
 dilla, the veratrum album, or white helle- 
 bore, and the colchicum autumnale or mea- 
 dow saffron. 
 
 The seeds of cevadilla, after being freed 
 from an unctuous and acid matter by ether. 
 
VER 
 
 VQL 
 
 were digested in boiling alcohol. As this 
 infusion cooled, a little wax was deposited ; 
 and the liquid being evaporated to an extract, 
 redissolved in water, and again concentrated 
 by evaporation, parted with its colouring 
 matter. Acetate of lead was now poured 
 into the solution, and an abundant yellow 
 precipitate fell, leaving the fluid nearly co- 
 lourless. The excess of lead was thrown 
 down by sulphuretted hydrogen, and the fil- 
 tered liquor being concentrated by evapora- 
 tion, was treated with magnesia, and again 
 filtered. The precipitate, boiled in alcohol, 
 gave a solution, which, on evaporation, left a 
 pulverulent matter, extremely bitter, and 
 with decidedly alkaline characters. It was 
 at first yellow, but by solution in alcohol, 
 and precipitation by water, was obtained in 
 a fine white powder. 
 
 The precipitate by the acetate of lead, 
 gave, on examination, gallic acid; and hence 
 it is concluded, that the new alkali existed in 
 the seed as a gall ate. 
 
 Yeratria was found in the other plants 
 above mentioned. It is white, pulverulent, 
 has no odour, but excites violent sneezing. 
 It is very acrid, but not bitter. It produc- 
 ed violent vomiting in very small doses, and, 
 according to some experiments, a few grains 
 may cause death. It is very little soluble in 
 cold water. Boiling water dissolves about 
 
 foVltF P ar b ar *d becomes acrid to the taste. 
 It is very soluble in alcohol, and rather less 
 soluble in ether. It fuses at 122° F., and 
 then appears like wax. On cooling, it be- 
 comes an amber- coloured translucent mass. 
 Heated more highly, it swells, decomposes, 
 and burns. Decomposed by oxide of cop- 
 per, it gave no trace of azote. It acts on 
 test papers like an alkali, and forms salts un- 
 cry stall izable by evaporation. The salts ap- 
 pear like a gum. The supersulphate only 
 seems to present crystals. Strong solutions 
 of these salts are partially decomposed by 
 water. Veratria falls down, and the solu- 
 tion becomes acid. The bisulphate appears 
 to consist of, 
 
 Veratria, 95.725 100 
 
 Sulphuric acid, 6.227 6.6441 
 
 The muriate is composed of, 
 
 Veratria, 95.8606 100 
 
 Muriatic acid, 4.1394 4.3181 
 
 Iodine and chlorine produce with veratria, 
 an iodate, hydriodate, chloride, and mu- 
 riate. 
 
 Verdigris. A crude acetate of copper. 
 
 Verditer, is a blue pigment, obtained by 
 adding chalk or whiting to the solution of 
 copper in aquafortis. Dr Merret says, that 
 
 is prepared in the following manner : 
 A quantity of whiting is put into a tub, 
 and upon this the solution of the copper 
 is poured. The mixture is to be stirred 
 
 every day for some hours together, till the 
 
 26 
 
 liquor loses its colour. Tho liquor is then 
 to be poured off, and more solution of cop- 
 per is to be added. This is to be repeated 
 till the whiting has acquired the proper co- 
 lour. 'I hen it is to be spread on large 
 pieces of chalk, and dried in the sun. 
 
 It appears from M. Pelletier’s analysis, 
 that 100 grains of the very best verditer con- 
 tain, of carbonic acid 30, of water Sj, of 
 pure lime 7, of oxygen 9j, and of pure cop- 
 per 50. The author remarks, that the ver- 
 diters of inferior quality contain more chalk 
 and less copper. 
 
 Verjuice. A kind of harsh, austere vi- 
 negar, made of the expressed juice of the 
 wild apple, or crab. The French give this 
 name to unripe grapes, and to the sour li- 
 quor obtained from them. 
 
 Vermilion. The red sulphuret of mer- 
 cury, or cinnabar. 
 
 Vessels (Chemical). See Apparatus. 
 
 * Yesuvian. Idocrase of Haiiy ; a sub- 
 species of pyramidal garnet. Colours green 
 and brown. Massive, disseminated, and 
 crystallized. Primitive form, a pyramid of 
 129° 30' and 74° 12'. The following se- 
 condary forms occur ; a rectangular four- 
 sided prism, variously acuminated, bevelled 
 or truncated. The lateral planes of the 
 prism are longitudinally streaked. Glisten- 
 ing vitreo-resinous. Cleavage imperfect, but 
 in the direction of the diagonals. Fracture 
 small grained uneven. Translucent. Re- 
 fracts double. Scratches felspar. Brittle. 
 Sp. gr. 3.3 to 3.4. It becomes electrical by 
 friction. Before the blow-pipe it melts with- 
 out addition into a yellowish, and faintly 
 translucent glass. Its constituents are, silica 
 
 35. 5, lime 33, alumina 22.25, oxide of iron 
 
 7.5, oxide of manganese 0.25, loss 1 . 5 . — 
 Klaproth . It occurs in considerable abun- 
 dance, in unaltered ejected rocks, in the vi- 
 cinity of Vesuvius. The rare blue variety 
 is found at Souland, in Tellemark, in Nor- 
 way, At Naples it is cut into ring- stones.*' 
 
 Vinegar. See Fermentation (Acetous); 
 and also Acid (Acetic), where the mode of 
 making it is given. 
 
 * Vinegar from Wood. M. Stolze, apo- 
 thecary at Halle, has discovered a method of 
 purifying vinegar from wood, by treating it 
 with sulphuric acid, manganese, and com- 
 mon salt, and afterwards distilling it over.* 
 
 Vinegar of Saturn. Solution of acetate 
 of lead. 
 
 Vinegar (Radical). Acetic acid. 
 
 Vital Air. See Oxygen. 
 
 Vitrification. See Glass; also Silica. 
 
 * Vitriol, blue, green , red, white. See 
 Ores of Copper, Iron, Cobalt, Zinc.* 
 
 Vitriolic Acid. See Acid (Sulphu- 
 ric). 
 
 Volatile Alkali. See Ammonia. 
 
 Volatility. The property of bodies by 
 which they are disposed to assume the va- 
 
VOL 
 
 VOL 
 
 porous or elastic state, and quit the vessels in 
 which they are placed. 
 
 Volcanoes. The combustion of those 
 enormous masses of bitumen, which are de- 
 posited in the bowels of the earth, produces 
 volcanoes. They owe their origin more 
 especially to the strata of pyritous coal. The 
 decomposition or action of water upon the 
 pyrites determines the heat, and the produc- 
 tion of a great quantity of hydrogen, which 
 exerts itself against the surrounding ob- 
 stacles, and at length breaks them. This 
 effect appears to be the chief cause of earth- 
 quakes ; but when the concourse of air faci- 
 litates the combustion of the bitumen and 
 the hydrogen, the flame is seen to issue out 
 of the chimneys or vents which are made ; 
 and this occasions the fire of volcanoes. 
 
 There are many volcanoes still in an ac- 
 tive state on our globe, independent of those 
 of Italy, which are the most known. The 
 Abbe Chappe has described three burning 
 in Siberia. Anderson and Von Troil have 
 described those of Iceland ; Asia and Africa 
 contain several ; and we find the remains of 
 these fires or volcanic products in all parts of 
 the globe. 
 
 Naturalists inform us, that all the south- 
 ern islands have been volcanized ; and they 
 are seen daily to be formed by the action of 
 these subterraneous fires. The black colour 
 of the stones, their spongy texture, the other 
 products of fire, and the identity of these 
 substances with those of the volcanoes at 
 present burning, are all in favour of the opi- 
 nion that their origin was the same. 
 
 When the decomposition of the pyrites is 
 advanced, and the vapours and elastic fluids 
 can no longer be contained in the bowels of 
 the earth, the ground is shaken, and exhibits 
 the phenomenon of earthquakes. Mephitic 
 vapours are multiplied on the surface of the 
 ground, and dreadful hollow noises are heard. 
 In Iceland, the rivers and springs are swal- 
 lowed up; a thick smoke, mixed with 
 sparks and lightning, is then disengaged 
 from the crater ; and naturalists have ob- 
 served, when the smoke of Vesuvius takes 
 the form of a pine, the eruption is near at 
 hand. 
 
 lo these preludes, which shew the inter- 
 nal agitation to be great, and that obstacles 
 oppose the issue of the volcanic matters, suc- 
 ceeds an eruption of stones and other pro- 
 ducts, which the lava drives before it ; and, 
 lastly, appears a river of lava, which flows 
 out, and spreads itself down the side of the 
 mountain. At this period the calm is restor- 
 ed in the bowels of the earth, and the erup- 
 tion continues without earthquakes. The 
 violent efforts of the included matter some- 
 times cause the sides of the mountain to 
 open ; and this is the cause which has suc- 
 cessively formed the smaller mountains that 
 surround volcanoes. Montenuevo, which is 
 
 a hundred and eighty feet high, and three 
 thousand in breadth, was formed in a 
 night. 
 
 This crisis is sometimes succeeded by an 
 eruption of ashes, which darken the air. 
 These ashes are the last result of the altera- 
 tion of the coals ; and the matter which is 
 first thrown out is that which the heat has 
 half vitrified. In the year 1767, the ashes 
 of Vesuvius were carried twenty leagues out 
 to sea, and the streets of Naples were cover- 
 ed with them. The report of Dion, con- 
 cerning the eruption of Vesuvius in the 
 reign of Titus, wherein the ashes were car- 
 ried into Africa, Egypt, and Syria, seems to 
 be fabulous. M. de Saussure observes, that 
 the soil of Rome is of this character, and 
 that the famous catacombs are all made in 
 the volcanic ashes. 
 
 It must be admitted, however, that the 
 force with which all these products are 
 thrown is astonishing. In the year 1769, 
 a stone, twelve feet high and four in cir- 
 cumference, was thrown to the distance of 
 a quarter of a mile from the crater : and 
 in the year 1771 Sir William Hamilton ob- 
 served stones of an enormous size, which 
 employed eleven seconds in falling. This in- 
 dicates an elevation of near two thousand feet. 
 
 The eruption of volcanoes is frequently 
 aqueous : the water, which is confined, and 
 favours the decomposition of the pyrites, is 
 sometimes strongly thrown out. Sea salt is 
 found among the ejected matter, and like- 
 wise sal ammoniac. In the year 1630, a 
 torrent of boiling water, mixed with lava, 
 destroyed Portici and Torre del Greco. Sir 
 W. Hamilton saw boiling water ejected. 
 The springs of boiling w'ater in Iceland, and 
 all the hot springs which abound at the sur- 
 face of the globe, owe their heat only to the 
 decomposition of pyrites. 
 
 Some eruptions are of a muddy substance ; 
 and these form the tuffa, and the pouzzolano. 
 The eruption which buried Herculaneum is 
 of this kind. Sir W. Hamilton found an 
 antique head, the impression of which w as 
 w r ell enough preserved to answer the purpose 
 of a mould. Herculaneum at the least 
 depth is seventy feet under the surface of the 
 ground, and in many places one hundred 
 and twenty. 
 
 The pouzzolano is of various colours. It 
 is usually reddish, sometimes grey, white, or 
 green : it frequently consists of pumice-stone 
 in powder ; but sometimes it is formed of 
 oxided clay. One hundred parts of red 
 pouzzolano afforded Bergman, silex 55, alu- 
 mina 20, lime 5, iron 20. 
 
 When the lava is once thrown out of the 
 crater, it rolls in large rivdrs down the side 
 of the mountain to a certain distance, which 
 forms the currents of lava, the volcanic 
 causeways, &c; The surface of the lava 
 cools, and forms a solid crust, under which 
 
VOL 
 
 VUL 
 
 the liquid lava flows. After the eruption, 
 this crust sometimes remains, and forms hol- 
 low galleries, which Messrs Hamilton and 
 Ferber have visited ; it is in these hollow 
 places that the sal ammoniac, the muriate of 
 soda, and other substances sublime. A 
 lava may be turned out of its course by op- 
 posing banks or dykes against it: this was 
 done in 1669 to save Catania; and Sir 
 William Hamilton proposed it to the king 
 of Naples to preserve Portici. 
 
 The currents of lava sometimes remain 
 several years in cooling. Sir William Ha- 
 milton observed, in 1769, that the lava which 
 flowed m 1766 was still smoking in some 
 places. 
 
 Lava is sometimes swelled up and porous. 
 The lightest is called pumice-stone. 
 
 The substances thrown out by volcanoes 
 are not altered by fire. They eject native 
 substances, such as quartz, crystals of ame- 
 thyst, agate, gypsum, amianthus, felspar, 
 mica, shells, schorl, &c. 
 
 The fire of volcanoes is seldom strong: 
 enough to vitrify the matters it throws out. 
 We know only of the yellowish capillary 
 and flexible glass thrown out by the vol- 
 canoes of the island of Bourbon, on the 
 14th of May 1766, (M. Commerson), and 
 the lapis gallinaceus ejected by Hecla. Mr 
 Egolfrigouson, who is employed by the 
 observatory at Copenhagen, has settled in 
 Iceland, where he uses a mirror of a tele- 
 scope, which he has made out of the black 
 agate of Iceland. 
 
 The slow operation of time decomposes 
 lavas, and their remains are very proper for 
 vegetation. The fertile island of Sicily has 
 been every- where volcanized. Chaptal ob- 
 served several ancient volcanoes at present 
 cultivated ; and the line which separates the 
 other earths from the volcanic earth, consti- 
 tutes the limit of vegetation. The ground 
 over the ruins of Pompeia is highly culti- 
 vated. Sir William Hamilton considers 
 subterranean fires as the great vehicle used 
 by nature to extract virgin earth out of the 
 bowels of the globe, and repair the exhaust- 
 ed surface. 
 
 The decomposition of lava is very slow. 
 Strata of vegetable earth, and pure lava, are 
 occasionally found applied one over the 
 other ; which denote eruptions made at dis- 
 tances of time very remote from each other, 
 since in some instances it appears to have 
 required nearly two thousand years before 
 lava was fit to receive the plough. In this 
 respect, however, lavas differ very widely, so 
 that our reasoning from them must at best 
 be very vague. An argument has been 
 drawn from this phenomenon to prove the 
 antiquity of the globe : but the silence of the 
 most ancient authors concerning the volca- 
 noes of the kingdom of France, of which we 
 find such frequent traces, indicates that these 
 
 volcanoes have been extinguished from time 
 immemorial ; a circumstance winch carries 
 their existence to a very distant period. Be- 
 side this, several thousand years of connected 
 observations have not afforded any remarka- 
 ble change in Vesuvius or /Etna ; neverthe- 
 less these enormous mountains are all vol- 
 canized, and consequently formed of 6trata 
 applied one upon the other. The prodigy 
 becomes much more striking, when we ob- 
 serve, that all the surrounding country, to 
 very great distances, has been thrown out of 
 the bowels of the earth. 
 
 The height of Vesuvius above the level of 
 the sea is three thousand six hundred and 
 fifty- nine feet ; its circumference thirty-four 
 thousand four hundred and forty-four. The 
 height of /Etna is ten thousand and thirty- 
 six feet ; and its circumference one hundred 
 and eighty thousand. 
 
 The various volcanic products are appli- 
 cable to several uses. 
 
 1. The pouzzolano is of admirable use for 
 building in the water : when mixed with 
 lime it speedily fixes itself ; and water does 
 not soften it, for it becomes continually 
 harder and harder. Chaptal has proved 
 that oxided ochres afford the same advantage 
 for this purpose ; they are made into balls, 
 and baked in a potter’s furnace in the usual 
 manner. The experiments made at Sette, 
 by the commissary of the province, prove, 
 that they may be substituted with the great- 
 est advantage instead of the pouzzolano of 
 Italy. 
 
 2. Lava is likewise susceptible of vitrifi- 
 cation ; and in this state it may be blown 
 into opaque bcttles of the greatest lightness, 
 which Chaptal says he has done at Erepian 
 and at Alais. The very hard lava, mixed 
 in equal parts with wood-ashes and soda, 
 produced, he says, an excellent green glass. 
 The bottles made of it were only half the 
 weight of common bottles, and much strong- 
 er, as was proved by Chaptal’s experiments, 
 and those which M. Joly de Fleury ordered 
 to be made under his administration. 
 
 3. Pumice-stone likewise has its uses ; it 
 is more especially used to polish most bodies 
 which are somewhat hard. It is employed 
 in the mass or in powder, according to the 
 intended purpose. Sometimes, after levi- 
 tation, it is mixed with water to render it 
 softer. 
 
 * Volcanite. Augite. * 
 
 * Vulpenite. Colour greyish- white. 
 Massive. Splendent. Fracture foliated. 
 Fragments rhomboidal. In distinct granu- 
 lar concretions. Translucent on the edges. 
 Soft. Brittle. Sp. gr. 2.878. It melts 
 easily before the blow-pipe into a "bite 
 opaque enamel. Its constituents are, sul- 
 phate of lime 92, silica 8. It occurs along 
 with granular foliated limestone at \ ulpiuo, 
 in Italv. * 
 
WAT 
 
 WAT 
 
 W 
 
 * ^TTACKE. A mineral substance in- 
 
 it v termediate between clay and basalt. 
 It is sometimes simple j but when it inclines 
 to basalt, it contains hornblende and mica. 
 It is sometimes spotted, and these spots are 
 unformed crystals of hornblende, resembling 
 the unformed crystals of felspar in certain 
 varieties of porphyry. It never contains 
 augite or olivine. When it approaches to 
 an amygdaloid, it is vesicular. Its colour is 
 greenish-grey. Massive and vesicular. Dull. 
 Opaque. Streak shining. Soft. Easily 
 frangible. Sp. gr. 2 .55 to 2.9. Fuses like 
 basalt. It seldom contains petrifactions. It 
 occurs sometimes in beds and veins, and 
 these veins contain very small portions of 
 ores of different kinds, as bismuth, silver- 
 glance, and magnetic ironstone. * 
 
 W add. This name is given to plumba- 
 go, or black-lead. 
 
 Wadd Black. An ore of manganese 
 found in Derbyshire. It is remarkable for 
 the property of taking fire when mixed with 
 linseed oil. 
 
 Wash. The technical term for the fer- 
 mented liquor, of whatever kind, from which 
 spirit is intended to be distilled. See Al- 
 cohol and Distillation. 
 
 # 
 
 Water. It is scarcely necessary to give 
 any definition or description of this univer- 
 sally known fluid. It is a very transparent 
 fluid, possessing a moderate degree of acti- 
 vity with regard to organized substances, 
 ■which renders it friendly to animal and 
 vegetable life, for both which it is indeed 
 indispensably necessary. Hence it acts but 
 slightly on the organs of sense, and is 
 therefore said to have neither taste nor 
 smell. It appears to possess considerable 
 elasticity, and yields in a perceptible degree 
 to the pressure of air in the condensing 
 machine, as Canton proved, by including 
 it in an open glass vessel with a narrow 
 neck. 
 
 The solubility or insolubility of bodies in 
 this fluid composes a large part of the science 
 of chemistry. See Salt. 
 
 * The habitudes of water with heat have 
 been detailed under Caloric and Tempera- 
 ture. * 
 
 Water is not ody the common measure 
 of specific gravities, but the tables of these 
 may be usefully employed in the admea- 
 surement of irregular solids; for one cubic 
 foot is very nearly equal to 1000 ounces 
 avoirdupois. The numbers of the table 
 denoting the specific gravities, do there- 
 fore denote likewise the number of ounces 
 avoirdupois in a cubic foot of each sub- 
 stance. 
 
 Native water is seldom, if ever, found 
 perfectly pure. The waters that flow within 
 or upon the surface of the earth, contain 
 various earthy, saline, metallic, vegetable, or 
 animal particles, according to the substances 
 over or through which they pass. Rain and 
 snow waters are much purer than these, al- 
 though they also contain whatever floats in 
 the air, or has been exhaled along with the 
 watery vapours. 
 
 The purity of water may be known by 
 the following marks or properties of pure 
 water : — 
 
 1. Pure water is lighter than water that 
 is not pure. 
 
 2. Pure water is more fluid than water 
 that is not pure. 
 
 3. It has no colour, smell, or taste. 
 
 4. It wets more easily than the waters 
 containing metallic and earthy salts, call- 
 ed hard waters, and feels softer when touch- 
 ed. 
 
 5. Soap, or a solution of soap in alcohol, 
 mixes easily and perfectly with it. 
 
 6. It is not rendered turbid by adding to 
 it a solution of gold in aqua regia, or a so- 
 lution of silver, or of lead, or of mercury, in 
 nitric acid, or a solution of acetate of lead 
 in water. 
 
 For the habitudes of water with saline 
 matter, see Salt, and the different sub- 
 stances. 
 
 Water was, till modern times, considered 
 as an elementary or simple substance. 
 
 Previous to the month of October 1776, 
 the celebrated Macquer, assisted by M. Si- 
 gaud de la Fond, made an experiment by 
 burning hydrogen gas in a bottle, without 
 explosion, and holding a white china saucer 
 over the flame. His intention appears to 
 have been that of ascertaining whether any 
 fuliginous smoke was produced, and he ob- 
 serves, that the saucer remained perfectly 
 clean and white, but was moistened with 
 perceptible drops of a clear fluid, resembling 
 water; and which, in fact, appeared to him 
 and his assistant, to be nothing but pure wa- 
 ter. 
 
 He does not say whether any test was ap- 
 plied to ascertain this purity, neither does he 
 make any remark on the fact.f 
 
 In the month of September 1777, Messrs 
 Bucquet and Lavoisier, not being acquaint, 
 ed with the fact, which is incidentally and 
 concisely mentioned by Macquer, made an 
 experiment to discover what is produced by 
 the combustion of hydrogen. They fired 
 
 * Dictionnaire de Chymie, 2d edition, Paris, 1778 
 Art. U*s Inllammable, vol.ii. p. 514, 515. 
 
WAT 
 
 WAT 
 
 fire or six pints of hydrogen in an open and 
 wide-mouthed bottle, and instantly poured 
 two ounces of lime-water through the flame, 
 agitating the bottle during the time the com- 
 bustion lasted. The result of this experi- 
 ment showed, that carbonic acid was not 
 prodiiced.f 
 
 Before the month of April 1781, Mr 
 John Warltire, encouraged by Dr Priest- 
 ley, fired a mixture of common air and hy- 
 drogen gas in a close copper vessel, and 
 found its weight diminished. Dr Priestley, 
 likewise, before the same period, fired a like 
 mixture of hydrogen and oxygen gas in a 
 closed glass vessel, Mr Warltire being pre- 
 sent. 1 he inside of the vessel, though clean 
 and dry before, became dewy, and was lined 
 with a sooty substance. | These experi- 
 ments were afterwards repeated by Mr Ca- 
 vendish and Dr Priestley; and it was found, 
 that the diminution of weight did not take 
 place, neither was the sooty matter perceiv- 
 ed. || These circumstances, therefore, must 
 have arisen from some imperfection in the 
 apparatus or materials with which the former 
 experiments were made. 
 
 It was in the summer of the year 1781, 
 that Mr Henry Cavendish was busied in 
 examining what becomes of the air lost by 
 combustion, and made those valuable expe- 
 riments, which were read before the Royal 
 Society on the 15th of January 1784.§ He 
 burned 500,000 grain measures of hydrogen 
 gas, with about times the quantity of 
 common air, and by causing the burned air 
 to pass through a glass tube eight feet in 
 length, 135 grains of pure water were con- 
 densed. lie also exploded a mixture of 
 19,500 grain measures of oxygen gas, and 
 37,000 of hydrogen, in a close vessel. The 
 condensed liquor was found to contain a 
 €mall portion of nitric acid, when the mix- 
 ture of the air was such, that the burned air 
 still contained a considerable proportion of 
 oxygen. In this case it may be presumed, 
 that some of the oxygen combines with a 
 portion of nitrogen present. 
 
 In the mean time, M. Lavoisier continu- 
 ed his researches, and during the winter of 
 1781-1782, together with M. Gingembre, 
 be filled a bottle of six pints with hydrogen, 
 which being fired, and two ounces of lime- 
 water poured in, w as instantly stopped with 
 a cork, through which a flexible tube com- 
 municating with a vessel of oxygen was pass- 
 
 + Acad. Par. 1781, p. 470. 
 
 t Priestley, v. 305. 
 
 || Phil. Trans, lxxiv. 126. Dr Priestley supposed the 
 sooty matter to be part of the mercury used in filling 
 the vessel, Phil. Trans, lxxiv. 332. 
 
 \ Mr I^avoisier relates, that Dr Blagden, Sec. It. S. 
 (who was present at the performing of the capital ex- 
 periment of burning hydrogen and oxygen gas in a 
 closed vessel on the 24th June 1783), informed him, 
 that Mr Cavendish had already done the same thing, 
 and obtained water. See the Memoirs of the Royal 
 Academy at Paris for 1781, p. 472; also Phil. Trans, 
 vol. lxxiv. p. 134. 
 
 ed. The inflammation ceased, except at the 
 orifice of the tube, through which the oxy- 
 gen was pressed, where a beautiful flame ap- 
 peared. The combustion continued a con- 
 siderable time, during which the lime-water 
 was agitated in the bottle. Neither this, nor 
 the same experiment repeated w ith pure w a- 
 ter, and with a w-eak solution of alkali in- 
 stead of lime-water, afforded the information 
 sought after, for these substances were not 
 at all altered. 
 
 The inference of Mr Warltire, respecting 
 the moisture on the inside of the glass, in 
 which Dr Priestley first fired hydrogen and 
 common air, was, that these airs, by com- 
 bustion, deposited the moisture they con- 
 tained. Mr Watt, however, inferred from 
 these experiments, that water is a compound 
 of the burned airs, which have given out 
 their latent heat by combustion, and com- 
 municated his sentiments to Dr Priestley in 
 a letter dated April 26. 1783.f 
 
 It does not appear, J that the composition 
 of water was known or admitted in France, 
 till the summer of 1783, when M. Lavoi- 
 sier and M. de la Place, on the 24th of 
 June, repeated the experiment of burning 
 hydrogen and oxygen in a glass vessel over 
 mercury, in a still greater quantity than had 
 been burned by Mr Cavendish. The re- 
 sult was nearly five gros of pure water. § 
 M. Monge made a similar experiment at 
 Paris, nearly at the same time, or perhaps 
 before. 
 
 This assiduous and accurate philosopher 
 then proceeded, in conjunction with M. 
 Meusnier, to pass the steam of water through 
 a red-hot iron tube, and found that the iron 
 was oxidized, and hydrogen disengaged ; 
 and the steam of water being passed over 
 a variety of other combustible or oxidable 
 substances, produced similar results, the wa- 
 ter disappearing, and hydrogen being disen- 
 gaged. These capital experiments were ac- 
 counted for by M. Lavoisier, by supposing 
 the water to be decomposed into its compo- 
 nent parts, oxygen and hydrogen, the former 
 of which unites with the ignited substance, 
 while the latter is disengaged. 
 
 The grand experiment of the composition 
 of w'ater by Fourcroy, Vauqurlin, and Se- 
 guin, was begun on Wednesday, May 13. 
 1790, and w'as finished on Friday, the 22d 
 of the same month. The combustion was 
 kept up 185 hours with little interruption, 
 during which time the machine was not 
 quitted for a moment. The experimenters 
 alternately refreshed themselves when fa- 
 tigued, by lying for a few hours on ma- 
 trasses in the laboratory. 
 
 f Phil. Trans, vol. lxxiv. p. 330. ... 
 
 % Compare Phil. Trans, vol. lxxiv. p. lou, with^the 
 Memoirs of the Royal Academy at Paris tor 1/81, 
 pages 472 and 474. 
 
 The ounce poids de marc being A , .... grains tro>, 
 this quantity will be 225 English grains. 
 
WAT 
 
 WAT 
 
 To obtain the hydrogen, 1 . Zinc was 
 melted and rubbed into a powder in a very 
 hot mortar. 2. This metal was dissolved in 
 concentrated sulphuric acid diluted with 
 seven parts of water. The air procured 
 was made to pass through caustic alkali. To 
 obtain the oxygen, two pounds and a half 
 of crystallized hyperoxymuriate of potash 
 were distilled, and the air was transferred 
 through caustic alkali. 
 
 The volume of hydrogen employed was 
 25963.568 cubic inches, and the weight was 
 1039.358 grains. 
 
 The volume of oxygen was 12570.942, 
 and the weight was 6209.869 grains. 
 
 The total weight of both elastic fluids was 
 7249.227. 
 
 The weight of water obtained was 7244 
 grains, or 12 ounces 4 gros 45 grains. 
 
 The weight of water which should have 
 been Obtained was 12 ounces 4 gros 49.227 
 grains. 
 
 The deficit was 4.227 grains. 
 
 The quantity of azotic air before the ex- 
 periment was 415.256 cubic inches, and at 
 the close of it 467. The excess after the 
 experiment was consequently 51.744 cubic 
 inches. This augmentation is to be attribut- 
 ed, the academicians think, to the small 
 quantity of atmospheric air in the cylinders 
 of the gasometers, at the time the other airs 
 were introduced. These additional 51 cu- 
 bic inches could not arise from the hydro- 
 gen, for experiment showed, that it contain- 
 ed no azotic air. Some addition of this last 
 fluid, the experimenters think, cannot be 
 avoided, on account of the construction of 
 the machine. 
 
 The water being examined, was found to 
 be as pure as distilled water. Its specific 
 gravity to distilled water was as 18671 : 
 18670. 
 
 * The decomposition of water is most ele- 
 gantly effected by Electricity ; which see. 
 
 The composition of water is best de- 
 monstrated by exploding 2 volumes of hy- 
 drogen and l of oxygen, in the eudiometer. 
 They disappear totally, and pure water re- 
 sults. A cubic inch of this liquid at 60°, 
 weighs 252.52 grains, consisting of 
 28.06 grains hydrogen, and 
 224.46 oxygen. 
 
 The bulk of the former ) . . . , 
 
 > 1325 cubic inches. 
 
 gas is $ 
 
 That of the latter is 662 
 
 1987 
 
 Hence there is a condensation of nearly 
 two thousand volumes into one ; and one 
 volume of water contains 662 volumes of 
 oxygen. The prime equivalent of water is 
 1.125 ; composed of a prime of oxygen = 
 
 1 .0 — |— a prime of hydrogen = 0. 1 25 ; or 9 
 parts by weight of water, consist of 8 oxy- 
 gen 1 hydrogen.* 
 
 Water of Crystallization. Many 
 salts require a certain proportion of water to 
 enable them to retain the crystalline form, 
 and this is called their water of crystalliza- 
 tion. Some retain this so feebly, that it flies 
 off on exposure to the air, and they fall to 
 powder. These are the efflorescent salts. 
 Others have so great an affinity for water, 
 that their crystals attract more from the air, 
 in which they dissolve. These are the deli- 
 quescent. 
 
 Waters (Mineral). The examination 
 of mineral waters with a view to ascertain 
 their ingredients, and thence their medical 
 qualities and the means of compounding 
 them artificially, is an object of considerable 
 importance to society. It is likewise a sub- 
 ject which deserves to be attended to, be- 
 cause it affords no mean opportunity for the 
 agreeable practice of chemical skill. But 
 this investigation is more especially of im- 
 portance to the daily purposes of life, and 
 the success of manufactures. It cannot but 
 be an interesting object, to ascertain the 
 component parts and qualities of the waters 
 daily consumed by the inhabitants of large 
 towns and vicinities. A very minute por- 
 tion of unwholesome matter, daily taken, 
 may constitute the principal cause of the 
 differences in salubrity, which are observa- 
 ble in different places. And with regard to 
 manufactures, it is well known to the brew- 
 er, the paper-maker, the bleacher, and a va- 
 riety of other artists, of how much conse- 
 quence it is to them, that this fluid should 
 either be pure, or at least not contaminated 
 with such principles as tend to injure the 
 qualities of the articles they make. This 
 analysis has accordingly employed the atten- 
 tion of the first chemists. Bergmann has 
 written an express treatise on the subject, 
 which may be found in the first volume of 
 the English translation of his Essays. Kir- 
 wan published a valuable volume on the 
 analysis of waters. 
 
 The topography of the place where these 
 waters rise is the first thing to be considered. 
 By examining the ooze formed by them, 
 and the earth or stones through which they 
 are strained and filtered, some judgment 
 may be formed of their contents. In filter- 
 ing through the earth, and meandering on 
 its surface, they take with them particles of 
 various kinds, which their extreme attenua- 
 tion renders capable of being suspended in 
 the fluid that serves for their vehicle. Hence 
 we shall sometimes find in these, water, sili- 
 ceous, calcareous, or argillaceous earth ; and 
 at other times, though less frequently, sul- 
 phur, magnesian earth, or, from the decom- 
 position of carbonated iron, ochre. 
 
 The following are the ingredients that 
 may occur in mineral waters : 
 
 1. Air is contained in by far the greater 
 number of mineral waters ; its proportion 
 
WAT 
 
 does not exceed l-28th of the bulk of the 
 water. 
 
 2. Oxygen gas was first detected in waters 
 by Scheele. Its quantity is usually inconsi- 
 derable ; and it is incompatible with the 
 presence of sulphuretted hydrogen gas or 
 iron. 
 
 3. Hydrogen gas was first detected in 
 Buxton water by Dr Pearson. Afterward 
 it was discovered in Ilarrowgate waters by 
 Dr Garnet, and in those of Lemington 
 Priors by Mr Lambe. 
 
 4. Sulphuretted hydrogen gas constitutes 
 the most conspicuous ingredient in those 
 waters, which are distinguished by the name 
 of hepatic or sulphureous. 
 
 The only acids hitherto found in waters, 
 except in combination with a base, are the 
 carbonic, sulphuric, and boracic. 
 
 5. Carbonic acid was first discovered in 
 Pyrmont water by Dr Brownrigg. It is the 
 most common ingredient in mineral waters, 
 100 cubic inches of the water generally 
 containing from 6 to 40 cubic inches of this 
 acid gas. According to YVestrumb, 100 
 cubic inches of Pyrmont water contain 187 
 cubic inches of it, or almost double its own 
 bulk. 
 
 6. Sulphurous acid has been observed in 
 several of the hot mineral waters in Italv, 
 which are in the neighbourhood of volca- 
 noes. 
 
 7. The boracic acid has also been observ- 
 ed in some lakes in Italy. 
 
 The only alkali whch has been observed 
 in mineral waters, uncombined, is soda; 
 and the only earthy bodies are silex and 
 lime. 
 
 8. Dr Black detected soda in the hot mi- 
 neral waters of Geysser and Rykum in Ice- 
 land ; but in most other cases the soda is 
 combined with carbonic acid. 
 
 9. Silex was first discovered in waters by 
 Bergtnann. It was afterward detected in 
 those of Geysser and Rykum by Dr Black, 
 and in those of Karlsbad by Klaproth. II as- 
 senfratz observed it in the waters of Pougues, 
 as Breze did in those of Pu. It has been 
 found also in many other mineral waters. 
 
 10. Lime is said to have been found un- 
 combined in some mineral waters ; but this 
 has not been proved in a satisfactory man- 
 ner. 
 
 The only salts hitherto found in mineral 
 waters are the following sulphates, nitrates, 
 muriates, carbonates, and borates; and of 
 these the carbonates and muriates occur by 
 far most commonly, and the borates and ni- 
 trates most rarely. 
 
 1 1 . Sulphate of soda is not uncommon, 
 especially in those mineral waters which are 
 distinguished by the epithet saline. 
 
 12. Sulphate of ammonia is found in mi- 
 neral waters near volcanoes. 
 
 1 3. Sulphate of lime is exceedingly com- 
 
 WAT 
 
 mon in water. Its presence seems to have 
 been first detected by Dr Lister in 1682. 
 
 14. Sulphate of magnesia is almost con- 
 stantly an ingredient in those mineral waters 
 which have purgative properties. It was 
 detected in Epsom waters in 1610, and in 
 1696 Dr Grew published a treatise on it. 
 
 15. Alum is sometimes found in mineral 
 waters, but it is exceedingly rare. 
 
 16. Sulphate of iron occurs sometimes in 
 volcanic mineral waters, and has even been 
 observed in other places. 
 
 1 7. Sulphate of copper is only found in 
 the waters which issue from copper mines. 
 
 1 8. Nitre has been found in some springs 
 in Hungary, but it is exceedingly uncom- 
 mon.. 
 
 19. Nitrate of lime was first detected in 
 water by Dr Plome, of Edinburgh, in 1756. 
 It is said to occur in some springs in the 
 sandy deserts of Arabia. 
 
 20. Nitrate of magnesia is said to have 
 been found in some springs. 
 
 21. Muriate of potash is uncommon ; but 
 it has lately been discovered in the mineral 
 springs of Uhleaborg in Sweden, by Julin. 
 
 22. Muriate of soda is so extremely com- 
 mon in mineral waters, that hardly a single 
 spring has been analyzed without detecting 
 some of it. 
 
 25. Muriate of ammonia is uncommon, 
 but it has been found in some mineral 
 springs in Italy and in Siberia. 
 
 24. Muriate of barytes is still more un- 
 common, but its presence in mineral waters 
 has been announced by Bergmann. 
 
 25 and 26. Muriates of lime and majr- 
 nesia are common ingredients. 
 
 27. Muriate of alumina has been observed 
 by Dr Withering, but it is very uncommon. 
 
 28. Muriate of manganese was mentioned 
 by Bergmann as sometimes occurring in mi- 
 neral waters. It has lately been detected by 
 Lambe in the waters of Lemington Priors, 
 but in an extremely limited proportion. 
 
 29. The presence of carbonate of potash 
 in mineral waters has been mentioned by se- 
 veral chemists ; if it do occur, it must be in 
 a very small proportion. 
 
 30. Carbonate of soda is, perhaps, one of 
 the most common ingredients of these liquids, 
 if we except common salt and carbonate of 
 lime. 
 
 31. Carbonate of ammonia has been dis- 
 covered in waters, but it is uncommon. 
 
 32. Carbonate of lime is found in almost 
 all waters, and is usually held in solution by 
 an excess of acid. It appears from the dif- 
 ferent experiments of chemists, as stated by 
 Mr Kirwan, and especially from those ot 
 Berthollet, that water saturated with car- 
 bonic acid is capable of holding in solution 
 0.002 of carbonate of lime. Now water sa- 
 turated with carbonic acid, at the tempera- 
 ture of 50°, contains very nearly 0.002 ol its 
 
WAT 
 
 WAT 
 
 weight of carbonic acid. Hence it follows, 
 that carbonic acid, when present in such 
 quantity as to saturate waters, is capable of 
 holding its own weight of carbonate of lime 
 in solution. Thus we see 1000 parts by 
 weight of water, when it contains two parts 
 of carbonic acid, is capable of dissolving 
 two parts of carbonate of lime. When the 
 proportion of water is increased, it is capa- 
 ble of holding the carbonate of lime in solu- 
 tion, even when the proportion of carbonic 
 acid united with it is diminished. Thus 
 24000 parts of water are capable of holding 
 two parts of carbonate of lime in solution, 
 even when they contain only one part of 
 carbonic acid. The greater the proportion 
 of water, the smaller proportion of ^car- 
 bonic acid is necessary to keep the lime in 
 solution ; and when the water is increased 
 to a certain proportion, no sensible excess 
 of carbonic acid is necessary. It ought to 
 be remarked also, that water, however small 
 a quantity of carbonic acid it contains, is 
 capable of holding earbonate of lime in solu- 
 tion, provided the weight of the carbonic 
 acid present exceed that of the lime. These 
 observations apply equally to the other 
 earthy carbonates held in solution by mine- 
 ral waters. 
 
 55. Carbonate of magnesia is also very 
 common in mineral waters, and is almost 
 always accompanied by carbonate of lime. 
 
 34. Carbonate of alumina is said to have 
 been found in waters, but its presence has 
 not been properly ascertained. 
 
 35. Carbonate of iron is by no means un- 
 common, indeed it forms the most remark- 
 able ingredient in those waters, which are 
 distinguished by the epithet of chalybeate. 
 
 56. Borax exists in some lakes in Persia 
 and Thibet, but the nature of these waters 
 has not been ascertained. 
 
 57 and 38. The hydrosulphurets of lime 
 and of soda have been frequently detected 
 in those waters which are called sulphurous, 
 or hepatic. 
 
 Mr Westrumb says, that all sulphurous 
 waters contain more or less hydrosulphuret 
 of lime. 
 
 To detect this he boiled the mineral water, 
 excluding the contact of atmospheric air, to 
 expel the sulphuretted hydrogen gas and car- 
 bonic acid. Into the water thus boiled he 
 poured sulphuric acid, when more sulphuret- 
 ted hydrogen gas was evolved, and sulphate of 
 lime was thrown down ; finning nitric acid, 
 which separated from it sulphur ; and oxalic 
 acid, which expelled sulphuretted hydrogen, 
 and formed oxalate of lime. The water eva- 
 porated in open vessels let fall sulphate of 
 lime, and gave out sulphuretted hydrogen 
 gas. 
 
 To ascertain the quantity of sulphuretted 
 hydrogen gas and carbonic acid, Mr West- 
 rumb proceeded as follows : lie introduced 
 
 the sulphurous water into a matrass, till it 
 was filled to a certain point, which he mark- 
 ed ; fitted to it a curved tube, which ter- 
 minated in a long cylinder; filled this cylin- 
 der with lime-water for the one experiment, 
 and with acetate of lead, with excess of acid, 
 for the other ; luted the apparatus ; and 
 boiled the water till no more gas was ex- 
 pelled. When the lime-water is used, car- 
 bonate of lime is precipitated in the propor- 
 tion of 20 grains to every 10 cubic inches 
 of carbonic acid gas; when the solution of 
 acetate of lead, hydrosulphuret of lead, is 
 thrown down in the proportion of 19 grains 
 to 10 cubic inches of sulphuretted hydrogen 
 gas. 
 
 Beside these substances, certain vegetable 
 and animal matters have been occasionally 
 observed in mineral waters. But in most 
 cases these are rather to be considered in 
 the light of accidental mixtures, than of real 
 component parts of the waters in w hich they 
 occur. 
 
 From this synoptical view of the different 
 ingredients contained in mineral waters, it 
 is evident, that these substances occur in tw r o 
 different distinct states, viz. 1. As being sus- 
 pended in them ; and 2. As being dissolved 
 in them chiefly in the form of a salt. 
 
 The investigation of mineral waters con- 
 sists, 1. In the examination of them by the 
 senses : 2. In the examination of them by 
 reagents : 3. In the analysis properly so 
 called. 
 
 The examination by the senses consists in 
 observing the effect of the water as to ap- 
 pearance, smell, and taste. 
 
 The appearance of the water, the instant 
 in which it is pumped out of the well, as 
 well as after it lias stood for some time, af- 
 fords several indications, from which we are 
 enabled to form a judgment concerning its 
 contents. If the water be turbid at the 
 well, the substances are suspended only, and 
 not dissolved ; but if the w ater be clear and 
 transparent at the well, and some time in- 
 tervenes before it becomes turbid, the con- 
 tents are dissolved by means of carbonic 
 acid. 
 
 The presence of this gas is likewise indi- 
 cated by small bubbles, that rise from the 
 bottom of the w'ell, and burst in the air 
 while they are making their escape, though 
 the water at the same time perhaps has not 
 an acid taste. This is the case, according 
 to Count Razoumowski, with respect to the 
 tepid spring in Vallais, and the cold vitriol- 
 ated chalybeate springs at Astracan. But 
 the most evident proof of a spring contain- 
 ing carbonic acid is the generation of bub- 
 bles on the water being shaken, and their 
 bursting with more or less noise, while the 
 air is making its escape. 
 
 The sediment deposited by the water in 
 the well is likewise to be examined ; if it be 
 
WAT 
 
 WAT 
 
 yellow, it indicates the presence of iron ; if 
 black, that of iron combined with sulphur ; 
 but chalybeate waters being seldom sulphu- 
 retted, the latter occurs very rarely. As to 
 the colour ot the water itself, there are few 
 instances where this can give any indication 
 of its contents, as there are not many sub- 
 stances that colour it. 
 
 The odour of the water serves chiefly to 
 discover the presence of sulphuretted hydro- 
 gen in it: such waters as contain this sub- 
 stance have a peculiar fetid smell, somewhat 
 resembling rotten eggs. 
 
 The taste of a spring, provided it be per- 
 fectly ascertained by repeated trials, may 
 afford some useful indications with respect 
 to the contents. It may be made very sen- 
 sible by tasting water, in which the various 
 salts that are usually found in such waters 
 are dissolved in various proportions. There 
 is no certain dependence, however, to be 
 placed on this mode of investigation ; for in 
 many springs, the taste of sulphate of soda 
 is disguised by that of the sea salt united 
 with it. The water too is not only to be 
 tasted at the spring, but after it has stood 
 for some time. This precaution must be 
 particularly observed with respect to such 
 waters as are impregnated with carbonic 
 acid; for the other substances contained in 
 them make no impression on the tongue, 
 till the carbonic acid has made its escape; 
 and it is for the same reason, that these wa- 
 ters must be evaporated in part, and then 
 tasted again. 
 
 Though the specific gravity of any water 
 contributes but very little towards determin- 
 ing its contents, still it may not be entirely 
 useless to know the specific weight of the 
 water, the situation of the spring, and the 
 kind of sediment deposited by it. 
 
 The examination of the w'ater by means 
 of reagents shows what they contain, but 
 not how much of each principle. In many 
 instances this is as much as the inquiry de- 
 mands ; and it is always of use to direct the 
 proceedings in the proper analysis. 
 
 It is absolutely necessary to make the ex- 
 periment with water just taken up from the 
 spring, and afterward with such as has been 
 exposed for some hours to the open air; 
 and sometimes a third essay is to be made 
 with a portion of the w'ater that has been 
 boiled and afterward filtered. If the water 
 contain hut few saline particles, it must be 
 evaporated ; as even the most sensible re- 
 agents do not in the least affect it, it the 
 salts, the presence of which is to be disco- 
 vered by them, are diluted with too great 
 a quantity of water. Now, it may happen, 
 that a water shall be impregnated with a 
 considerable number of saline particles ot 
 different kinds, though some of them may 
 be present in too small a quantity ; for w hich 
 reason the water must be examined a second 
 
 time, after having been boiled down to three- 
 fourths. 
 
 i lie substances of which the presence is 
 discoverable by reagents, are: 
 
 1. Carbonic acid. When this is not com- 
 bined with any base, or not with sufficient 
 to neutralize it, the addition of lime-water 
 "'ill thrown down a precipitate soluble with 
 effervescence in muriatic acid. The in- 
 fusion of litmus is reddened by it; but the 
 red colour gradually disappears, and may 
 be again restored by the addition of more 
 of the mineral water. When boiled it loses 
 the property of reddening the infusion of 
 litmus. According to Pfaff, the most sen- 
 sible test of this acid is acetate of lead. 
 
 2>The mineral acids, when present un- 
 combined in w r aler, give the infusion of lit- 
 mus a permanent red, even though the wa- 
 ter has been boiled, Bergmann has shown, 
 that paper stained with litmus is reddened 
 
 when dipped into water containing Vr of 
 sulphuric acid. 
 
 3. Water containing sulphuretted hydro- 
 gen gas is distinguished by the following 
 properties : It exhales the peculiar odour of 
 sulphuretted hydrogen gas. It reddens the 
 infusion of litmus fugaciously. It blackens 
 paper dipped into a solution of lead, and 
 precipitates the nitrate of silver black or 
 brown. 
 
 4. Alkalis, and alkaline and earthy car- 
 bonates, are distinguished by the following 
 tests : The infusion of turmeric, or paper 
 stained with turmeric, is rendered brown 
 by alkalis; or reddish-brown, if the quantity 
 be minute. This change is produced when 
 
 the soda in water amounts only to ^2 17 
 part. Paper stained with brazil wood, or 
 the infusion of brazil w r ood, is rendered blue; 
 but this change is produced also by the al- 
 kaline and earthy carbonates. Bergmann 
 
 ascertained, that water containing part 
 
 of carbonate of soda, renders paper stained 
 with brazil wood blue. Litmus paper red- 
 dened by vinegar is restored to its original 
 blue colour. This change is produced by 
 the alkaline and earthy carbouates also. 
 When these changes are fugacious, we may 
 conclude, that the alkali is ammonia. 
 
 5. Fixed alkalis exist in water that occa- 
 sions a precipitate with muriate of magnesia 
 after being boiled. Volatile alkali may be 
 distinguished by the smell ; or it may be 
 obtained in the receiver by distilling a por- 
 tion of the water gently, and then it may be 
 distinguished by the above tests. 
 
 6 . Earthy and metallic carbonates are pre- 
 cipitated by boiling the water containing 
 them ; except carbonate of magnesia, which 
 is precipitated but imperfectly. 
 
 7. Iron is discovered by the following 
 tests: — The addition of tincture of galls 
 gives water, containing iron, a purple or 
 
WAT 
 
 WAT 
 
 black colour. This test indicates the pre- 
 sence of a very minute portion of iron. If 
 the tincture have no effect upon the water, 
 after boiling, though it colours it before, the 
 iron is in the state of a carbonate. The fol- 
 lowing observations of Westrumb on the 
 colour which iron gives to galls, as modified 
 by other bodies, deserve attention. A vio- 
 let indicates an alkaline carbonate, or earthy 
 salt. Dark purple indicates other alkaline 
 salts. Purplish-red indicates sulphuretted 
 hydrogen gas. Whitish, and then black, in- 
 dicates sulphate of lime. Mr Phillips has 
 lately ascertained, that, while the iron is 
 little oxided, the presence of lime rather 
 facilitates the application of this test; but 
 the lime prevents the test from acting, pro- 
 vided the iron be considerably oxidized. 
 The prussian alkali occasions a blue preci- 
 pitate in water containing iron. If an al- 
 kali be present, the blue precipitate does not 
 appear unless the alkali is saturated with an 
 acid. 
 
 8. Sulphuric acid exists in waters that 
 form a precipitate with the following solu- 
 tions : — muriate, nitrate, or acetate of bary- 
 tes, strontian, or lime, or nitrate or acetate of 
 lead. Of these the most powerful by far is 
 muriate of barytes, which is capable of de- 
 tecting the presence of sulphuric acid un- 
 combined, when it does not exceed the mil- 
 lionth part of the water. Acetate of lead is 
 next in point of power. The muriates are 
 more powerful than the nitrates. The cal- 
 careous salts are least powerful. All these 
 tests are capable of indicating a much small- 
 er proportion of uncombined sulphuric acid, 
 than when it is combined with a base. To 
 render muriate of barytes a certain test of 
 sulphuric acid, the following precautions 
 must be observed -The muriate must be 
 diluted ; the alkalis or alkaline carbonates, 
 if the water contain any, must be previously 
 saturated with muriatic acid ; the precipitate 
 must be insoluble in muriatic acid ; if boracic 
 acid be suspected, muriate of strontian must 
 be tried, which is not precipitated by boracic 
 acid. The hydro-sulphurets precipitate bary- 
 tic solutions, but their presence is easily dis- 
 covered by the smell. 
 
 9. Muriatic acid is detected by nitrate of 
 silver, which occasions a white precipitate, 
 or a cloud, in water containing an exceed- 
 ingly minute portion of this acid. To ren- 
 der this test certain, the following precau- 
 tions are necessary: — The alkalis or car- 
 bonates must be previously saturated with 
 nitric acid. Sulphuric acid, if any be pre- 
 sent, must be previously removed by means 
 of nitrate of barytes. The precipitate must 
 be insoluble in nitric acid. Pfaff says, that 
 the mild nitrate of mercury is the most sen- 
 sible test of muriatic acid ; and that the pre- 
 cipitate is not soluble in an excess of any 
 acid. 
 
 10. Boracic acid is detected by means ot 
 acetate of lead, with w'hich it forms a preci- 
 pitate insoluble in acetic acid. But to ren- 
 der this test certain, the alkalis and earths 
 must be previously saturated with acetic acid, 
 and the sulphuric and muriatic acids remov- 
 ed by means of acetate of strontian and ace- 
 tate of silver. 
 
 11. Barytes is detected by the insoluble 
 white precipitate, which it forms with dilut- 
 ed sulphuric acid. 
 
 12. Lime is detected by means of oxalic 
 acid, which occasions a white precipitate in 
 water containing a very minute proportion 
 of this earth. To render this test decisive, 
 the following precautions are necessary: — 
 The mineral acids, if any be present, must 
 be previously saturated with an alkali. Bary- 
 tes, if any be present, must be previously re- 
 moved by means of sulphuric acid. Oxalic 
 acid precipitates magnesia but very slowly ? 
 whereas it precipitates lime instantly. 
 
 13. Magnesia and alumina. The pre- 
 sence of these earths is ascertained by the* 
 following tests : — Pure ammonia precipi- 
 tates them both, and no other earth, provid- 
 ed the carbonic acid have been previously 
 separated by a fixed alkali and boiling. 
 Lime-water precipitates only these two 
 earths, provided the carbonic acid be pre- 
 viously removed, and the sulphuric acid also* 
 by means of nitrate of barytes. 
 
 The alumina may be separated from the 
 magnesia, after both have been precipitated 
 together, either by boiling the precipitate in 
 caustic potash, which dissolves the alumina 
 and leaves the magnesia ; or the precipitate 
 may be dissolved in muriatic acid, precipi- 
 tated by an alkaline carbonate, dried in the 
 temperature of 100°, and then exposed to 
 the action of diluted muriatic acid, which 
 dissolves the magnesia without touching the 
 alumina. 
 
 14. Silex may be ascertained by evapo- 
 rating a portion of water to dryness, and 
 redissolving the precipitate in muriatic acid. 
 The silex remains behind undissolved. 
 
 By these means w r e may detect the pre- 
 sence of the different substances commonly 
 found in waters ; but as they are generally- 
 combined so as to form salts, it is necessary 
 we should know what these combinations 
 are. This is a more difficult task, which 
 Mr Kirwan teaches us to accomplish by the 
 following methods : — 
 
 I. To ascertain the presence of the dif- 
 ferent sulphates. 
 
 The sulphates wdiich occur in water are 
 seven ; but one of these, namely, sulphate of 
 copper , is so uncommon, that it may be ex- 
 cluded altogether. The same remark ap- 
 plies to sulphate of ammonia. It is almost 
 unnecessary to observe, that no sulphate need 
 be looked for, unless both its acid and base 
 have been previously detected in the water. 
 
WAT 
 
 WAT 
 
 Sulphate of soda may be detected by the 
 following method : — Free the water to be ex- 
 amined ot all earthy sulphates, by evaporat- 
 ing it to one-half, and adding lime-water as 
 long as any precipitate appears. By these 
 means the earths will all be precipitated 
 except lime, and the only remaining earthy 
 sulphate will be sulphate of lime, which will 
 be separated by evaporating the liquid till 
 it becomes concentrated, and then dropping 
 into it a little alcohol, and, after filtration, 
 adding a little oxalic acid. 
 
 With the water thus purified, mix solu- 
 tion of lime. If a precipitate appear, either 
 immediately or on the addition of a little 
 alcohol, it is a proof, that sulphate of potash 
 or of soda is present. Which of the two 
 may be determined, by mixing some of the 
 purified water with acetate of barytes. Sul- 
 phate of barytes precipitates. Filter and 
 evaporate to dryness. Digest the residuum 
 in alcohol. It will dissolve the alkaline 
 acetate. Evaporate to dryness, and the dry 
 salt will deliquesce if it be acetate of potash, 
 but effloresce if it be acetate of soda. 
 
 Sulphate of lime may be detected by eva- 
 porating the water suspected to contain it 
 to a few ounces. A precipitate appears, 
 which, if it be sulphate of lime, is soluble in 
 500 parts of water ; and the solution affords 
 a precipitate with the muriate of barytes, 
 oxalic acid, carbonate of magnesia, and al- 
 cohol. 
 
 Alum may be detected by mixing carbo- 
 nate of lime with the water suspected to con- 
 tain it. If a precipitate appear, it indicates 
 the presence of alum, or at least of sulphate 
 of alumina ; provided the water contains no 
 muriate of barytes or metallic sulphates. 
 The first of these salts is incompatible with 
 alum. The second may be removed by the 
 alkaline prussiates. When a precipitate is 
 produced in water by muriate of lime, car- 
 bonate of lime, and muriate of magnesia, we 
 may conclude, that it contains alum or sul- 
 phate of alumina. 
 
 Sulphate of magnesia may be detected by 
 means of hydrosulphuret of strontian, which 
 occasions an immediate precipitate with this 
 salt, and with no other ; provided the water 
 be previously deprived of alum, if any be 
 present, by means of carbonate of lime, and 
 provided also that it contains no uncombin- 
 ed acid. 
 
 Sulphate of iron is precipitated from water 
 by alcohol, and then it may be easily recog- 
 nized by its properties. 
 
 2. To ascertain the presence of the dif- 
 ferent muriates. 
 
 The muriates found in waters amount to 
 eight, or to nine if muriate of iron be includ- 
 ed. The most common by far is muriate of 
 soda. 
 
 Muriate of soda and of potash may be de- 
 tected by the following method: — Separate 
 
 the sulphuric acid by alcohol and nitrate of 
 barytes. Decompose the earthy nitrates and 
 muriates by adding sulphuric acid. Expel 
 the excess of muriatic and nitric acids by 
 heat. Separate the sulphates thus formed by 
 alcohol and barytes water. The water thus 
 purified can contain nothing but alkaline 
 nitrates and muriate*. If it form a precipi- 
 tate with acetate of silver, we may conclude, 
 that it contains muriate of soda or of potash. 
 To ascertain which, evaporate the liquid 
 thus precipitated to dryness. Dissolve the 
 acetate in alcohol, and again evaporate to 
 dryness. The salt will deliquesce, if it be 
 acetate of potash ; but effloresce, if it be 
 acetate of soda. 
 
 Muriate of barytes may be detected by 
 sulphuric acid, as it is the only barytic salt 
 hitherto found in water. 
 
 Muriate of lime may be detected by the 
 following method : — Free the water from 
 sulphate of lime and other sulphates, by eva- 
 porating it to a few ounces, mixing it with 
 alcohol, and adding last of all nitrate of ba- 
 rytes, as long as any precipitate appears. 
 Filter the water ; evaporate to dryness ; 
 treat the dry mass with alcohol ; evaporate 
 the alcohol to dryness ; and dissolve the re- 
 siduum in water. If this solution give a 
 precipitate with acetate of silver and oxalic 
 acid, it may contain muriate of lime. It 
 must contain it in that case, if, after being 
 treated with carbonate of lime, it give no 
 precipitate with ammonia. If the liquid in 
 the receiver give a precipitate with nitrate of 
 silver, muriate of lime existed in the water. 
 
 Muriate of magnesia may be detected by 
 separating all the sulphuric acid by means 
 of nitrate of barytes. Filter, evaporate to 
 dryness, and treat the dry mass with alco- 
 hol. Evaporate the alcoholic solution to 
 dryness, and dissolve the residuum in water. 
 The muriate of magnesia, if the water con- 
 tained any, will be found in this solution. 
 Let us suppose, that, by the tests formerly 
 described, the presence of muriatic acid and 
 of magnesia, in this solution, has been ascer- 
 tained. In that case, if carbonate of lime 
 afford no precipitate, and if sulphuric acid 
 and evaporation, together with the addition 
 of a little alcbhol, occasion no precipitate, 
 the solution contains only muriate of mag- 
 nesia. If these tests give precipitates, we 
 must separate the lime which is present by 
 sulphuric acid and alcohol, and distil oft' the 
 acid with which it was combined. Then 
 the magnesia is to be separated by the oxalic 
 acid and alcohol, and the acid with which it 
 was united is to be distilled oft. It the li- 
 quid in the retort give a precipitate with ni- 
 trate of silver, the water contains muriate of 
 magnesia. 
 
 Muriate of alumina may be discovered by 
 saturating the water, if it contain an excess 
 of alkali, with nitric acid, and by separating 
 
WAT 
 
 WAT 
 
 the sulphuric acid by means of nitrate of ba- 
 rytes. If the liquid, thus purified, give a 
 precipitate with carbonate of lime, it con- 
 tains muriate of alumina. The muriate of 
 iron or of manganese, if any be present, is 
 also decomposed, and the iron precipitated 
 by this salt. The precipitate may be dis- 
 solved in muriatic acid, and the alumina, 
 iron, and manganese, if they be present, 
 may be separated by the rules laid down 
 below. 
 
 3. To ascertain the presence of the dif- 
 ferent nitrates. The nitrates but seldom 
 occur in waters; but when they do, they 
 may be detected by the following results : — 
 
 Alkaline nitrates may be detected by free- 
 ing the water examined from sulphuric acid 
 by means of acetate of barytes, and from 
 muriatic acid by acetate of silver. Evapo- 
 rate the filtered liquid, and treat the dry 
 mass with alcohol ; what the alcohol leaves 
 can consist only of the alkaline nitrates and 
 acetate of lime. Dissolve it in water. If 
 carbonate of magnesia occasion a precipi- 
 tate, lime is present. Separate the lime by 
 means of carbonate of magnesia. Filter and 
 evaporate to dryness, and treat the dried 
 mass with alcohol. The alcohol now leaves 
 only the alkaline nitrates, which may be 
 easily recognized, and distinguished by their 
 respective properties. 
 
 Nitrate of lime. To detect this salt, con- 
 centrate the water, and mix it with alcohol 
 to separate the sulphates. Filter, and distil 
 off the alcohol ; then separate the muriatic 
 acid by acetate of silver. Filter, evaporate 
 to dryness, and dissolve the residuum in al- 
 cohol. Evaporate to dryness, and dissolve 
 the dry mass in water. If this last solution 
 indicate the presence of lime by the usual 
 tests, the water contained nitrate of lime. 
 
 To detect nitrate of magnesia, the water 
 is to be freed from sulphates and muriates 
 exactly as described in the last paragraph. 
 The liquid thus purified is to be evaporated 
 to dryness, and the residuum treated with 
 alcohol. The alcoholic solution is to be eva- 
 porated to dryness, and the dry mass dis- 
 solved in water. To this solution potash 
 is to be added, as long as any precipitate 
 appears. The solution, filtered, and again 
 evaporated to dryness, is to be treated with 
 alcohol. If it leave a residuum consisting 
 of nitre (the only residuum which it can 
 leave) the water contained nitrate of mag- 
 nesia. 
 
 Such are the methods by which the pre- 
 sence of the different saline contents of wa- 
 ters may be ascertained. The labour of 
 analysis may be considerably shortened, by 
 observing that the following salts are incom- 
 patible with each other, and cannot exist to- 
 gether in water, except in very minute pro- 
 portion : — 
 
 Salts. 
 
 Fixed alkaline 
 sulphates 
 
 Alum 
 
 fi 
 
 Incompatible with 
 
 ^Nitrates of lime and mag- 
 \ nesia, 
 
 f Muriates of lime and mag- 
 nesia. 
 f Alkalis, 
 
 Sulphate of lime Carbonate of magnesia, 
 
 ^ Muriate of barytes. 
 Alkalis, 
 
 Muriate of barytes, 
 Nitrate, muriate, carbo- 
 nate of lime, 
 
 Carbonate of magnesia. * 
 f~ Alkalis, 
 
 Muriate of barytes, 
 Nitrate and muriate of 
 lime. 
 f Alkalis, 
 
 Sulphate of iron Muriate of barytes, 
 
 (^Earthy carbonates, 
 f Sulphates, 
 
 Alkaline carbonates, 
 Earthy carbonates. 
 TSulphates, except of lime. 
 Muriate of lime Alkaline carbonates, 
 
 C Earthy carbonates. 
 Muriate of mag- ^ Alkaline carbonates, 
 nesia \ Alkaline sulphates. 
 
 f Alkaline carbonates, 
 
 \ Carbonate of magnesia 
 f and alumina, 
 ^Sulphates, except of lime. 
 
 Sulphate of 
 magnesia 
 
 { 
 
 i 
 
 i 
 
 Muriate of 
 barytes 
 
 Nitrate of lime 
 
 Beside the substances above described, 
 there is sometimes found in water a quan- 
 tity of bitumen combined with alkali, and 
 in the state of soap. In such waters acids 
 occasion a coagulation ; and the coagulum 
 collected on a filter discovers its bituminous 
 nature by its combustibility. 
 
 Water also sometimes contains extractive 
 matter ; the presence of which may be de- 
 tected by means of nitrate of silver. The 
 water suspected to contain it must be freed 
 from sulphuric and nitric acid by means of 
 nitrate of lead : after this, if it give a brown 
 precipitate with nitrate of silver, we may 
 conclude that extractive matter is present. 
 
 But it is not sufficient to know that a 
 mineral water contains certain ingredients ; 
 it is necessary to ascertain the proportions of 
 these, and thus we arrive at their complete 
 analysis. 
 
 1. The different aerial fluids ought to be 
 first separated and estimated. For this pur- 
 pose, a retort should be filled two-thirds 
 with the water, and connected with a jar 
 full of mercury, standing over a mercurial 
 trough. Let the water be made to boil for 
 a quarter of an hour. The aerial fluids 
 will pass over into the jar. When the ap- 
 paratus is cool, the quantity of air expelled 
 from the water may be determined either 
 by bringing the. mercury within and with- 
 
 47 
 
WAT 
 
 WAT 
 
 out the jar to a level ; or if this cannot be 
 done, by reducing the air to the proper den- 
 sity by calculation. The air of the retort 
 ought to be carefully subtracted, and the 
 jar should be divided into cubic inches and 
 tenths. 
 
 The only gaseous bodies contained in 
 water are, common air, oxygen gas, nitrogen 
 gas, carbonic acid, sulphuretted hydrogen 
 gas, and sulphurous acid. The last two 
 never exist in water together. The pre- 
 sence of either of them must be ascertained 
 previously by the application of the proper 
 tests. If sulphuretted hydrogen gas be pre- 
 sent, it will be mixed with the air contained 
 in the glass jar, and must be separated be- 
 fore this air be examined. For this purpose 
 the jar must be removed into a tub of warm 
 water, and nitric acid introduced, which will 
 absorb the sulphuretted hydrogen. The re- 
 siduum is then to be again put into a mer- 
 curial jar and examined. 
 
 If the water contain sulphurous acid, this 
 previous step is not necessary. Introduce 
 into the air a solution of pure potash, and 
 agitate the whole gently. The carbonic 
 acid and sulphurous acid gas will be ab- 
 sorbed, and leave the other gases. The 
 bulk of this residuum, subtracted from the 
 bulk of the whole, will give the bulk of 
 the carbonic acid and sulphurous acid ab- 
 sorbed. 
 
 Evaporate the potash slowly, almost to 
 dryness, and leave it exposed to the atmos- 
 phere. Sulphate of potash will be formed, 
 which may be separated by dissolving the 
 carbonate of potash by means of diluted mu- 
 riatic acid, and filtering the solution. 100 
 grains of sulphate of potash indicate <56.4 
 grains of sulphurous acid, or 53.66 cubic 
 inches of that acid in the state of gas. The 
 bulk of sulphurous acid gas ascertained by 
 this method, subtracted from the bulk of the 
 gas absorbed by the potash, gives the bulk 
 of the carbonic acid gas. Now 100 cubic 
 inches of carbonic acid, at the temperature 
 of 60° and barometer 80 inches, weigh 
 46.6 grains. Hence it is easy to ascertain 
 its weight. 
 
 The gas remaining may be examined by 
 the common eudiometrical processes. 
 
 When a water contains sulphuretted hy- 
 drogen gas, the bulk of this gas is to be 
 ascertained in the following manner: Fill 
 three-fourths of a jar with the water to be 
 examined, and invert it in a water trough, 
 and introduce a little nitrous gas. This 
 gas, mixing with the air in the upper part 
 of the jar, will form nitrous acid, which will 
 render the water turbid, by decomposing 
 the sulphuretted hydrogen and precipitating 
 sulphur. Continue to add nitrous gas at 
 intervals as long as red fumes appear, then 
 turn up the jar and blow put the air. II 
 
 the hepatic smell continue, repeat this pro- 
 cess. The sulphur precipitated indicates 
 the proportion of hepatic gas in the water; 
 one grain of sulphur indicating the presence 
 of nearly 3 cubic inches of this gas. 
 
 .2. After having estimated the gaseous 
 bodies, the next step is to ascertain the pro- 
 portion of the earthy carbonates. For this 
 purpose it is necessary to deprive the water 
 of its sulphuretted hydrogen, if it contain 
 any. I his may be done, either by exposing 
 it to the air for a considerable time, or treat- 
 ing it with litharge. A sufficient quantity 
 of the water, thus purified if necessary, is to 
 be boiled for a quarter of an hour, and filter- 
 ed when cool. The earthy carbonates re- 
 main on the filter. 
 
 The precipitate thus obtained may be car- 
 bonate ot lime, of magnesia, of iron, of alu- 
 mina, or even sulphate of lime. Let us sup- 
 pose all of these substances to be present 
 together. Treat the mixture with diluted 
 muriatic acid, which will dissolve the whole 
 except the alumina and sulphate of lime. 
 Dry this residuum in a red-heat, and note 
 the weight. Then boil it in carbonate of 
 soda, saturate the soda with muriatic acid, 
 and boil the mixture for half an hour. Car- 
 bonate of lime and alumina precipitate. Dry 
 this precipitate, and treat it with acetic acid. 
 The lime w ill be dissolved, and the alumina 
 will remain. Dry it and weigh it. Its w eight 
 subtracted from the original weight, gives the 
 proportion of sulphate of lime. 
 
 The muriatic solution contains lime, mag- 
 nesia, and iron. Add ammonia as long as 
 a reddish precipitate appears. The iron and 
 part of the magnesia are thus separated. 
 Dry the precipitate, and expose it to the 
 air for some time in a heat of 200° ; then 
 treat it with acetic acid to dissolve the mag- 
 nesia; which solution is to be added to the 
 muriatic solution. The iron is to be redis- 
 solved in muriatic acid, precipitated by an 
 alkaline carbonate, dried and weighed. 
 
 Add sulphuric acid to the muriatic solu- 
 tion as long as any precipitate appears ; then 
 heat the solution and concentrate. Heat 
 the sulphate of lime thus obtained to redness, 
 and weigh it. 100 grains of it are equiva- 
 lent to 74.7 of carbonate of lime dried. Pre- 
 cipitate the magnesia by means of carbonate 
 of soda. Dry it and weigh it. But as part 
 remains in solution, evaporate to dryness, 
 and wash the residuum with a sufficient 
 quantity of distilled water, to dissolve the 
 muriate of soda and sulphate of lime, if any 
 be still present. What remains behind is 
 carbonate of magnesia. Weigh it, and add 
 its weight to the former. The sulphate of 
 lime, if any, must also be separated and 
 weighed. 
 
 3. We have next to ascertain the propor- 
 tion of mineral acids or alkalis, if any be 
 
WAT 
 
 WAT 
 
 present uncombined. The acids which may 
 be present, omitting the gaseous, are the sul- 
 phuric, muriatic, and boracic. 
 
 The proportion of sulphuric acid is easily 
 determined. Saturate it with barytes water, 
 and ignite the precipitate. 100 grains of 
 sulphate of barytes thus formed indicate 34.0 
 of real sulphuric acid. 
 
 Saturate the muriatic acid with barytes 
 water, and then precipitate the barytes by 
 sulphuric acid. 100 parts of the ignited pre- 
 cipitate are equivalent to 23.73 grains of real 
 muriatic acid. 
 
 Precipitate the boracic acid by means of 
 acetate of lead. Decompose the borate ot 
 lead by boiling it in sulphuric acid. Eva- 
 porate to dryness. Dissolve the boracic acid 
 in alcohol, and evaporate the solution ; the 
 acid left behind may be weighed. 
 
 To estimate the proportion of alkaline 
 carbonate present in a water containing it, 
 saturate it with sulphuric acid, and note 
 the weight of real acid necessary. Now r 100 
 grains of real sulphuric acid saturate 120.0 
 potash, and 80.0 soda. 
 
 4. The alkaline sulphates may be estimated 
 by precipitating their acid by means of ni- 
 trate of barytes, having previously freed the 
 water from all other sulphates; for 14.75 
 grains of ignited sulphate of barytes indicate 
 9.0 grains of dried sulphate of soda ; w hile 
 14.75 sulphate of barytes indicate 1 1 of dry 
 sulphate of potash. 
 
 Sulphate of lime is easily estimated by eva- 
 porating the liquid containing it to a few 
 ounces (having previously saturated the 
 earthy carbonates with nitric acid), and pre- 
 cipitating the sulphate of lime by means of 
 weak alcohol. It may then he dried and 
 weighed. 
 
 The quantity of alum may be estimated 
 by precipitating the alumina by carbonate 
 of lime or of magnesia (if no lime be pre- 
 sent in the liquid). Eleven grains of the 
 alumina, heated to incandescence, indicate 
 100 of crystallized alum, or 55 of dried salt. 
 
 Sulphate of magnesia may be estimated, 
 provided no other sulphate be present, by 
 precipitating the acid by means of a barytic 
 salt, as 14.75 parts of ignited sulphate of ba- 
 rytes indicate 7.46 of sulphate of magnesia. 
 If sulphate of lime, and no other sulphate, 
 accompany it, this may be decomposed, and 
 the lime precipitated by carbonate of mag- 
 nesia. The weight of the lime thus obtain- 
 ed, enables us to ascertain the quantity of 
 sulphate of lime contained in the water. 
 The whole of the sulphuric acid is then to 
 he precipitated by barytes. This gives the 
 quantity of sulphuric acid ; and subtracting 
 the portion which belongs to the sulphate of 
 lime, there remains that which was combined 
 with the magnesia, from which the sulphate 
 of magnesia may be easily estimated. 
 
 If sulphate of soda be present, no earthy 
 
 o 
 
 nitrate or muriate can exist. Therefore, if 
 no other earthy sulphate be present, the 
 magnesia may be precipitated by soda, dried 
 and weighed; 2.46 grains of which indicate 
 7.46 grains of dried sulphate of magnesia. 
 The same process succeeds when sulphate of 
 lime accompanies these two sulphates ; only 
 in this case the precipitate, which consists 
 both of lime and magnesia, is to be dissolved 
 in sulphuric acid, evaporated to dryness, and 
 treated with twice its weight of cold water, 
 which dissolves the sulphate of magnesia, 
 and leaves the other salt. Let the sulphate 
 of magnesia be evaporated to dryness, ex- 
 posed to a heat of 400°, and weighed. The 
 same process succeeds, if alum be present 
 instead of sulphate of lime. The precipitate 
 in this case, previously dried, is to be treated 
 with acetic acid, which dissolves the magne- 
 sia, and leaves the alumina. The magnesia 
 may be again precipitated, dried, and weight 
 ed. If sulphate of iron be present, it may 
 be separated by exposing the water to the 
 air for some days, and mixing with it a por- 
 tion of alumina. Both the oxide of iron, 
 and the sulphate of alumina, thus formed, 
 precipitate in the state of an insoluble pow der. 
 The sulphate of magnesia may then be esti- 
 mated by the rules above given. 
 
 Sulphate of iron may be estimated by pre- 
 cipitating the iron by means of prussic alka- 
 li, having previously determined the weight 
 of the precipitate produced by the prussiate 
 in a solution of a given weight of sulphate 
 of iron in water. If muriate of iron be also 
 present, which is a very rare case, it may be 
 separated by evaporating the water to dry- 
 ness, and treating the residuum with alco- 
 hol, which dissolves the muriate, and leaves 
 the sulphate. 
 
 5. If muriate of potash or of soda, with- 
 out any other salt, exist in water, we have 
 only to decompose them by nitrate of silver, 
 and dry the precipitate; for 18.2 of mu- 
 riate of silver indicate 9.5 of muriate of pot- 
 ash ; and 18.2 of muriate of silver indicate 
 7.5 of common salt. 
 
 The same process is to be followed, if the 
 alkaline carbonates be present; only these 
 carbonates must be previously saturated with 
 sulphuric acid ; and we must precipitate 
 the muriatic acid by means of sulphate of 
 silver Instead of nitrate. The presence of 
 sulphate of soda does not injure the success 
 of this process. 
 
 If muriate of ammonia accompany either 
 of the fixed alkaline sulphates, without the 
 presence of any other salt, decompose the 
 sal ammoniac by barytes water, expel the 
 ammonia by boiling, precipitate the barytes 
 by diluted sulphuric acid, and saturate the 
 muriatic acid with soda. The sulphate of 
 barytes thus precipitated, indicates the quan- 
 tity of muriate of ammonia, 14.75 grains of 
 
 sulphate indicating 67.0 grains of this salt. 
 
 Z 
 
WAT 
 
 WAT 
 
 I f any sulphates be present in the solution, 
 they ought to be previously separated. 
 
 Tt common salt be accompanied by mu* 
 i:ate of lime, muriate of magnesia, muriate 
 of alumina, or muriate of iron, or by all 
 these together, without any other salt, the 
 earths may be precipitated by barytes water, 
 and redissolved in muriatic acid. They are 
 then to be separated from each other by the 
 rules formerly laid down, and their weight, 
 being determined, indicates the quantity of 
 every particular earthy muriate contained in 
 the water. For 50 grains of lime indicate 
 100 of dried muriate of lime ; SO grains of 
 magnesia indicate 100 of the muriate of that 
 earth; and 21.8 grains of alumina indicate 
 100 of the muriate of alumina. The barytes 
 is to be separated from the solution by sul- 
 phuric acid, and the muriatic acid expelled 
 by heat, or saturated with soda ; the com- 
 mon salt may then be ascertained by evapo- 
 ration, subtracting in the last case the pro- 
 portion of common salt indicated by the 
 known quantity of muriatic acid, from which 
 the earths had been separated. 
 
 When sulphates and min iates exist toge- 
 ther, they ought to be separated either by 
 precipitating the sulphates by means of alco- 
 hol, or by evaporating the whole to dryness, 
 and dissolving the earthy muriates in alco- 
 hol. The salts thus separated may be esti- 
 mated by the rules already laid down. 
 
 When alkaline and earthy muriates and 
 sulphate of lime occur together, the last is to 
 be decomposed by means of muriate of ba- 
 rytes. The precipitate ascertains the weight 
 of sulphate of lime contained in the water. 
 The estimation is then to be conducted as 
 when nothing but muriates are present, only 
 from the muriate of lime that proportion of 
 muriate must be deducted, which is known 
 to have been formed by the addition of the 
 muriate ot* barytes. 
 
 When muriates of soda, magnesia, and 
 alumina, are present together with sulphates 
 of lime and magnesia, the water to be exa- 
 mined ought to be divided into two equal 
 portions. To the one portion add carbonate 
 of magnesia, tiil the whole of the lime and 
 alumina is precipitated. Ascertain the quan- 
 tity of lime, which gives the proportion of 
 sulphate of lime. Precipitate the sulphuric 
 acid by muriate of barytes. This gives the 
 quantity contained in the sulphate of mag- 
 nesia and sulphate of lime ; subtracting this 
 last portion, we have the quantity of sulphate 
 of magnesia. 
 
 From the second portion of water, preci- 
 pitate all the magnesia and alumina by 
 means of lime-water. The weight of these 
 earths enables us to ascertain the weight of 
 muriate of magnesia and of alumina con- 
 tained in the water, subtracting that part of 
 the magnesia which existed in the state of 
 sulphate, as indicated by the examination ot 
 
 the first portion of water. After tins esti- 
 mation, precipitate the sulphuric acid by ba- 
 rytes water, and the lime bv carbonic acid* 
 The liquid, evaporated to dryness, leaves the 
 common salt. 
 
 6’. It now only remains to explain the 
 method of ascertaining the proportion of the 
 nitrates which may exist in waters. 
 
 W hen nitre accompanies sulphates and 
 muriates without any other nitrates, the sul- 
 phates are to be decomposed by acetate of 
 barytes, and the muriates by acetate of silver; 
 ihe w r ater, after filtration, is to be evaporat- 
 ed to dryness, and the residuum treated with 
 alcohol, which dissolves the acetates, anil 
 leaves the nitre, the quantity of which may 
 be easily calculated. If an alkali be pre- 
 sent, it ought to be previously saturated with 
 sulphuric or muriatic acid. 
 
 It nitre, common salt, nitrate of lime, and 
 muriate of lime or magnesia, be present to- 
 gether, the water ought to be evaporated to 
 dryness, and the dry mass treated with alco- 
 hol, which takes up the earthy salts. From 
 the residuum, redissolved in water, the nitre 
 may be separated, and calculated as in the 
 last case. The alcoholic solution is to be 
 evaporated to dryness, and the residuum re- 
 dissolved in water. Let us suppose it to 
 contain muriate of magnesia, nitrate of lime, 
 and muriate of lime. Precipitate the mu- 
 riatic acid b) r nitrate of silver, which gives 
 the proportion of muriate of magnesia and 
 ot lime. Separate the magnesia by means 
 of carbonate of lime, and note its quantity. 
 This gives the quantity of muriate of mag- 
 nesia ; and subtracting the muriatic acid 
 contained in that salt from the whole acid 
 indicated by the precipitate of silver, we 
 have the proportion of muriate of lime. 
 Lastly, saturate the lime added to precipitate 
 the magnesia with nitric acid. Then preci- 
 pitate the whole of the lime by sulphuric 
 acid ; and subtracting from the whole of the 
 sulphate thus formed, that portion formed 
 by the carbonate of lime added, and by the 
 lime contained in the muriate, the residuum 
 gives us the lime contained in the original 
 nitrate; and 55 grains of lime form 1 00 of 
 dry nitrate of lime. 
 
 * In the year 1807, Dr Marcet ad- 
 vanced some new ideas on the art of analyz- 
 ing mineral waters, in an admirable paper 
 on the water of the Dead Sea, inserted in 
 the Phil. Transactions. “It is satisfactory 
 to observe,” says this excellent chemist, 
 
 “ that Dr Murray adopted, several years 
 afterwards, a mode of proceeding precisely 
 similar, and indeed that he proposed, in a 
 subsequent paper, a general formula for the 
 analysis of mineral waters, in which this 
 method is pointed out, as likely to lead to 
 the most accurate results. And this coin- 
 cidence is the more remarkable, as it would 
 appear from Dr Murray not mentioning uiy 
 
WAT 
 
 WAT 
 
 labours, that they had not at that timo come 
 to his knowledge.” Phil. Trans. 181 9. partii. 
 
 The following table exhibits the composi- 
 tions of the principal mineral waters as well 
 as that of the sea. The reader will find in 
 the Phil. Trans, for 1819, a very valuable 
 dissertation on sea-water, by Dr Marcet, of 
 which a good abstract is given in the 2d vo- 
 lume of the Edin. Phil. Journal. This 
 philosopher shews, that in Baffin’s-Bay, the 
 Mediterranean Sea, and the Tropical Seas, 
 
 the temperature of the sea diminishes with 
 the depth, according to the observations of 
 Phipps, Ross, Parry, Sabine, Saussure, 
 Ellis, and Peron ; but that in the Arctic 
 or Greenland Seas, the temperature of the 
 sea increases with the depth. This singular 
 result was first obtained by Mr Scoresby, in 
 a series of well conducted experiments, and 
 has been confirmed by the later observations 
 of Lieutenants Franklin and Beechy, and 
 Mr Fisher.* 
 
(1) Bergmann. (2) Klaproth. (3) Babington. (4) Marcet. (5) Fourcroy. (6) Fothergill. (7) John. 
 
 (8) Phillips. (9) Pearson. (10) Schmesser. (11) Carrick. (14) Garnet. (15) Dr Philip. (16) Dr Murray. 
 
 (17) Dr Marcet, (18) Klaproth. (19) M. Gay Lussac. (20) Yauquelin. f Dr Wollaston. 
 
 Dead Sea (17) sp.gr. 1.211 
 Do. (18) sp.gr. 1.245 
 
 Do. (19) sp.gr. 1.2283 
 
 Sea water, Forth (16) 
 
 Calcareous, 
 
 nearly pure. 
 
 — * 
 
 Chaly- 
 
 beate. 
 
 0 2 . c 
 ’H.0'3 E. 
 
 §5: 
 
 ^ CO 
 
 • 
 
 • 
 
 • 
 
 1 
 
 1 
 
 • 
 
 1 
 
 Saline. 
 
 A 
 
 Sulphu- 1 
 rous. 
 
 5 S o » 
 e E.f aq 
 
 — • fe O. O 
 
 (0 1 ” i 
 
 ^ tr j, w 
 cip^^r 
 
 © ^ 
 
 , ° ' w 
 
 s 
 
 . • * 
 
 • 
 
 Acidulous. 
 
 Names of the Springs. 
 
 
 'Bath (8) 
 
 Buxton (9) - - 
 
 Bristol (11) ... 
 
 Matlock - 
 
 .Malvern (15) 
 
 'Sedlitz - 
 
 Cheltenham (6) 
 
 Plombieres (20) 
 
 Dunblane (16) 6p.gr. 1.00475 
 .Pitcaithly (16) 
 
 'Seltzer (1) 
 Pyrmont (1) 
 Spa (1) - 
 
 Carlsbad (2) 
 _Kilburn (10) 
 
 100 
 
 7291 
 
 Cl Ci Cl Cl t-* 
 00 oo 00 00 Cl 
 C3 Oo CO CO o 
 © O O O CO 
 O C C C O 
 
 to Ci o 
 
 to 00 Co 
 
 0(0 c 
 
 •— » 
 
 MOtl 
 - 1 *~1 4- C» OO 
 
 to tc o. £, c: 
 to tc o ♦* o 
 
 -1-003(0 
 
 103643 
 
 103643 
 
 6940 
 
 92160 
 
 i— * 
 
 cs to_ 
 cecicccccr 
 to Co to to to 
 4- to CO C) 4* 
 oocaot 
 
 Grains 
 
 of 
 
 water. 
 
 
 
 ►-i 
 
 
 
 *r* 
 
 CO 
 
 bl 
 
 Oxy- 
 
 gen. 
 
 Cubic inches of gases. 
 
 
 OS 
 
 o to 
 bo if* 
 
 10.6 
 
 18.0 
 
 Ca 
 
 >-» coo 
 
 bs o 
 
 8.0 
 
 1.0 
 
 18.5 
 
 00 Cl *-*►- 
 
 4* O p tO C5 
 b b be b» b 
 
 s 
 
 Carbo- 
 nic acid. 
 
 
 
 
 3.0 
 
 © o o o 
 
 Oi 
 
 36.0 
 
 Sulph. 
 
 hydro- 
 
 gen. 
 
 
 2.0 
 
 >f* 
 
 b 
 
 12.0 
 
 4*<! 
 
 oo 
 
 
 Azote. 
 
 
 5.33 
 
 »— * 
 CO 
 
 bl 
 
 $ 
 
 
 CO 
 
 GC J-* pi 
 
 Ci bo to 
 
 Ci tc 
 
 <3 $ 
 
 r* a 
 
 S 
 
 • 
 
 Carbonates of 
 
 
 (-1 1-1 
 
 J-* COCm 
 
 b> Ci Ci oi 
 
 16.5 
 
 pco ps 
 Ci bn if* -a 
 
 tc 1— 1 IT- 
 
 »-* ch ce 
 
 if. to Ci 
 
 Ci 
 
 io KD h-4 4^ 0C 
 k b CC to t; 
 CJi 
 
 50 e 
 3 
 
 tp 
 
 
 0.92 
 
 
 31.0 
 
 12.5 
 
 5.5 
 
 5.89 
 
 1.35 
 
 ►-» 4* to CX 
 
 to bo bo bo 
 
 Cl Ci tc 
 
 Magne- 
 
 sia. 
 
 gr. 
 
 
 0.004 
 
 0.625 
 
 1.0 
 
 32.5 
 
 5.0 
 
 0.17 
 
 
 coco 
 • • • • 
 
 Co — 
 
 4|i-4!- C O 
 
 Iron. 
 
 gr. 
 
 to 
 
 Ci 
 
 o> 
 
 3.0 
 
 11.2 
 
 2.896 
 
 
 •f* 
 
 O OS »-■ GC 
 • • • • 
 to -c oo 
 
 
 I— i C5 
 00 05 
 
 to -I 
 Cl 
 
 _ CO 
 
 39 O 
 
 " g* 
 
 Sulphates of 
 
 fe 
 
 4- 
 
 18.0 
 
 2.5 
 
 11.7 
 
 trace 
 
 Co 
 
 to — 
 Oi jo 
 
 Cl 
 
 41.1 
 
 40. 
 
 33.3 
 
 8.38 
 
 13.0 
 
 n c 
 
 .■> s 
 
 o 
 
 • 
 
 
 
 
 1444 
 
 0.5 
 
 5.8 
 
 5.44 
 
 91.0 
 
 Magne- 
 
 sia. 
 
 gr. 
 
 
 
 11.2 
 
 
 
 
 ?? IT 
 
 r« © 
 
 M 
 
 07 
 
 ZC ^ ^ o 
 U Sc oo b\ 
 
 Cl 
 
 i— i if. •— ' 03 
 
 ci o in o> 
 
 Ci 
 
 O) >-* 
 
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 ca to Ci 
 
 i— tc 
 
 tC — tc Cl 
 
 -j ' b b 
 
 05 
 
 to O CO Cl 
 
 if. to or. Ct 
 
 — . 
 
 CO *-* 
 
 C5 tC C — GO 
 © Ci to Cl 
 i— > 4* 
 
 09 O 
 
 -1 C, 
 
 * P 
 
 Muriates of 
 
 — 
 
 Ci 4*. O CO 
 
 i-i o o> bo 
 
 
 28.5 
 
 20.8 
 
 £0.2 
 
 3.0 
 
 0.6 
 
 r 
 
 ^ 3 
 
 • o 
 
 os i-* t o >— 
 ci ci 4* o 
 
 ci bo to *-> 
 1— » 
 
 7.25 
 
 cs tc 
 
 CO 
 
 tc p 
 
 C Cl 
 
 00 to 
 
 o i- 
 
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 bo 
 
 <5 I? 
 
 . ja op 
 
 tracef 
 
 
 
 
 
 
 1 Pot- 
 ash. 
 
 gr. 
 
 
 0.4 
 
 ►— * 
 
 
 
 to 
 
 to 
 
 Cl 
 
 Silica. 
 
 gr. 
 
 
 
 »— * 
 Cl 
 
 W-* 
 
 
 
 
 Alu- 
 
 mina. 
 
 gr. 
 
 
 
 
 
 
 6.0 
 
 b £■* 
 • 2? 
 
 
 O 
 
 o cwi oo ►-* 
 a. 4- k, 4* 
 o- o o o o 
 
 cold 
 
 cold 
 
 cold 
 
 o o a n o 
 o c c 6 c 
 
 O* O- O- 0* c. 
 
 cold 
 
 cold 
 
 143o 
 
 cold 
 
 n — n o o 
 
 C C5 c c c 
 ►r* Ci “ ST S* 
 o. C CC CC ©• 
 
 Tem- 
 
 pera- 
 
 ture. 
 
 TABLE of the Composition of the most celebrated Mineral Jl T aters. 
 
WAT 
 
 WAX 
 
 * Water (Oxygenized), or deutoxide of 
 hydrogen. This interesting compound has 
 been lately formed by M. Thenard, and an 
 account of it published in the tenth volume 
 of the Annales de Chimie et Physique. 
 The deutoxide of barium being dissolved in 
 water, and sulphuric acid added, the prot- 
 oxide of barium or barytes falls down, 
 leaving the oxygen combined with the water. 
 It contains, at 52° F. when saturated, twice 
 the quantity of oxygen of common water ; 
 that is to say, a cubic inch absorbs 66 2 cu- 
 bic inches = 224.4 6 gr., forming 476.98 
 grains, and acquires a specific gravity of 
 1.453. Hence 1.0 in volume, becomes ap- 
 parently 1.8; containing 1324 volumes of 
 oxygen ; and 1 therefore contains very nearly 
 1000 volumes. 
 
 In consequence of this great density, 
 when it is poured into common water, we 
 see it fall down through that liquid like a 
 sort of syrup, though it is very soluble in it. 
 It attacks the epidermis almost instantly, and 
 produces a prickling pain, the duration of 
 which varies, according to the quantity, of 
 the liquid applied to the skin. If this quan- 
 tity be too great, or if the liquid be renewed, 
 the skin itself is attacked and destroyed. 
 When applied to the tongue, it whitens it 
 also, thickens the saliva, and produces in the 
 organs of taste a sensation difficult to express, 
 but one which approaches to that of tartar eme- 
 tic. Its action on oxide of silver is exceedingly 
 violent. Every drop of the liquid let fall on 
 the dry oxide, produces a real explosion ; 
 and so much heat is evolved, that if the ex- 
 periment be made in a dark place, there is a 
 very sensible disengagement of light. Be- 
 sides the oxide of silver, there are several 
 other oxides, which act with violence on 
 oxygenated water ; for example the peroxide 
 of manganese, that of cobalt, the oxides of 
 lead, platinum, gold, iridium, rhodium, 
 palladium. Several metals in a state of 
 extreme division, occasion the same phe- 
 nomenon ; such as silver, platinum, gold, 
 osmium, iridium, rhodium, palladium. In 
 all the preceding cases it is always the oxy- 
 gen united to the water, which is disengaged 
 and sometimes likewise that of the oxide; but 
 in others, a portion of the oxygen unites with 
 the metal itself. This is the case when arsenic, 
 molybdenum, tungsten, or selenium is em- 
 ployed. These metals are often acidified 
 with the production of light. 
 
 The acids render the oxygenated water 
 more stable. Gold in a state of extreme 
 division acts with great force on pure oxy- 
 genated w'ater ; yet it has no action on that 
 liquid, if it be mixed with a little sulphuric 
 acid. 
 
 M. Thenard took pure oxygenated water, 
 and diluted it, so that it contained only 8 
 times its volume of oxygen. lie passed 22 
 measures of it into a tube filled with mer- 
 
 cury. He then introduced a little fibrin, 
 quite white, and recently extracted from 
 blood. The oxygen began instantly to be 
 disengaged from the water ; the mercury in 
 the tube sunk ; at the end of six minutes 
 the w'ater was completely disoxygenated ; for 
 it no longer effervesced with oxide of silver. 
 Having then measured the gas disengaged, 
 he found it, 176 measures = 8 X 22, that 
 is to say, as much as the liquid contained. 
 This eras contained neither carbonic acid nor 
 
 O 
 
 azote. It w r as pure oxygen. The same 
 fibrin placed in contact with new portions of 
 oxygenated water, acted in the same man- 
 ner. 
 
 Urea, albumen, liquid or solid, and gela- 
 tin, do not disengage oxygen from water, 
 even very much oxygenated. But the tissue 
 of the lungs cut into thin slices, and well 
 washed ; that of the kidneys and the spleen, 
 drive the oxygen out of the water, with as 
 much facility, at least, as fibrin does. The 
 skin and the veins possess the same property, 
 but in a weaker degree. These results are 
 equally interesting and mysterious. For a 
 valuable application of oxygenated w'uter, 
 see Paints,* 
 
 * Wavellite. Colour greyish-white. Imi- 
 tative and crystallized, in very oblique four- 
 sided prisms, flatly bevelled on the extremi- 
 ties, or truncated on the obtuse lateral edges. 
 Shining, pearly. Fragments w'edge-shaped. 
 Translucent. As hard as fluor spar. Brit- 
 tle. Sp. gr. 2.3 to 2.8. Its constituents 
 are, alumina 70, lime 1.4, water 26.2.— 
 Davy. It is said to contain also a small 
 quantity of fluoric acid. It occurs in veins 
 along with fluor spar, quartz, tinstone, and 
 copper pyrites in granite, at St Austle in 
 Cornwall. At Barnstaple in Devonshire, 
 where it was first found by Dr Wavell, it 
 traverses slate-clay, in the form of small 
 contemporaneous veins. It has been found 
 in rocks of slate-clay, near Loch Humphrey, 
 Dumbartonshire.® 
 
 Wax is an oily concrete matter gathered 
 by bees from plants. Proust says, that the 
 bloom on fruit is real wax ; and that it is 
 w r ax spread over leaves, which prevents 
 them from being wetted, as on the cabbage- 
 leaf. He likewise finds it in the fecula of 
 some vegetables, particularly in that of the 
 small house- leek, in which it abounds. Hu- 
 ber, however, asserts, from his observations, 
 that the wax in bee-liives is an artificial 
 production, made by the bees from honey ; 
 that they cannot procure it, unless they 
 have honey or sugar for the purpose ; and 
 that raw' sugar affords more than honey. 
 
 It was long considered as a resin, from 
 some properties common to it with resins. 
 Like them, it furnishes an oil and an acid 
 by distillation, and is soluble in all oils; but 
 in several respects it differs sensibly from 
 resins. Like these, wax has not a strong 
 
WAX 
 
 WEL 
 
 aromatic taste and smell, but a very weak 
 smell, and when pure, no taste. With the 
 heat of boiling water no principles are dis- 
 tilled from it ; whereas, with that heat, 
 some essential oil, or at least a spiritus rec- 
 tor, is obtained from every resin. Farther, 
 wax is less soluble in alcohol. If wax be 
 distilled with a heat greater that that of boil- 
 ing water, it may be decomposed, but not 
 so easily as resins can. By this distillation 
 a small quantity of water is first separated 
 from the wax, and then some very volatile 
 and very penetrating acid, accompanied with 
 a small quantity of a very fluid and very 
 odoriferous oil. As the distillation ad- 
 vances, the acid becomes more and more 
 strong, and the oil more and more thick, till 
 its consistence is such, that it becomes solid 
 in the receiver, and is then called butter of 
 wax. When the distillation is finished, no- 
 thing remains but a small quantity of coal, 
 which is almost incombustible. 
 
 Wax cannot be kindled, unless it is pre- 
 viously heated and reduced into vapours; 
 in which respect it resembles fat oils. The 
 oil of butter of wax may by repeated distil- 
 lations be attenuated and rendered more and 
 more fluid, because some portion of acid is 
 thereby separated from these substances; 
 which effect is similar to what happens in 
 the distillation of other oils and oily con- 
 cretes : but this remarkable effect attends 
 the repeated distill„don of oil and butter of 
 wax, that they become more and more so- 
 luble in alcohol ; and that they never ac- 
 quire greater consistence by evaporation of 
 their more fluid parts. Boerhaave kept but- 
 ter of wax in a glass vessel open, or care- 
 lessly closed, during twenty years, without 
 acquiring a more solid consistence. It may 
 be remarked, that wax, its butter, and its 
 oil, differ entirely from essential oils and 
 resins in all the above mentioned properties, 
 and that in all these they perfectly resemble 
 sweet oils. Hence Macquer concludes, that 
 wax resembles resins only in being an oil 
 rendered concrete by an acid ; but that it 
 differs essentially from these in the kind of 
 the oil, which in resins is of the nature of 
 essential oils, while in wax and in other ana- 
 logous oily concretions (as butter of milk, 
 butter of cocoa, fat of animals, spermaceti, 
 and myrtle- wax) it is of the nature of mild, 
 unctuous oils, that are not aromatic, and not 
 volatile, and are obtained from vegetables by 
 expression. 
 
 It seems probable, that the acidifying 
 principle, or oxygen, and not an actual acid, 
 may lie the leading cause of the solidity, or 
 low fusibility of wax. Wax is very useful, 
 especially as a better material than any other 
 for candles. 
 
 Wax may be deprived of its natural yel- 
 low disagreeable colour, and be perfectly 
 whitened by exposure to the united action 
 
 of air and water, by which method the 
 colour of many substances may be destroy- 
 ed. 
 
 The art of bleaching wax consists in in- 
 creasing its surface; for which purpose it 
 must be melted with a degree of heat not 
 sufficient to alter its quality, in a caldron so 
 disposed, that the melted wax may flow 
 gradually through a pipe at the bottom of 
 the caldron into a large tub filled with wa- 
 ter, in which is fitted a large wooden cylin- 
 der, tli at turns continually round its axis, 
 and upon which the melted wax falls. As 
 the surface of this cylinder is always moist- 
 ened with cold water, the wax falling upon 
 it does not adhere to it, but quickly becomes 
 solid and flat, and acquires the form of rib- 
 bands. The continual rotation of the cylin- 
 der carries off' these ribbands as fast as they 
 are formed, and distributes them through 
 the tub. When all the wax that is to be 
 whitened is thus formed, it is put upon 
 large frames covered with linen cloth, which 
 are supported about a foot and a half above 
 the ground, in a situation exposed to the 
 air, the dew, and the sun. The thickness of 
 the several ribbands, thus placed upon the 
 frames, ought not to exceed an inch and a 
 half, and they ought to be moved from time 
 to time, that they may all be equally ex- 
 posed to the action of the air. If the wea- 
 ther be favourable, the colour will be chang- 
 ed in the space of some days. It is then to 
 be re-melted and formed into ribbands, and 
 exposed to the action of the air as before. 
 These operations are to be repeated till the 
 wax is rendered perfectly white, and then 
 it is to be melted into cakes, or formed into 
 candles. 
 
 * Wax is composed, according to MM. 
 Gay Lussac and Thenard, of 
 Oxygen, 5.544 
 
 Hydrogen, 12.672 
 Carbon, 81.784 
 
 100.000 
 
 See Cerin.* 
 
 Wax is employed for many purposes in 
 several arts. It is also used in medicine as a 
 softening, emollient, and relaxing remedy : 
 but it is only used externally, mixed with 
 other substances. 
 
 Weld, or Woald (reseda luteola, Linn.), 
 is a plant cultivated in Kent, Herefordshire, 
 and many other parts of this kingdom. The 
 whole of the plant is used for dyeing yellow ; 
 though some assert, that the seeds only afford 
 the colouring matter. 
 
 Two sorts of weld are distinguished : the 
 bastard, or wild, which grows naturally in 
 the fields ; and the cultivated, the stalks ot 
 which are smaller, and not so high. kor 
 dyeing, the latter is preferred, it abounding 
 more in colouring matter. 1 he more slen- 
 der the stalk, the more it is valued. 
 
■WEL 
 
 WIN 
 
 When the weld is ripe, it is pulled, dried, 
 and made into bundles, in which state it is 
 used. 
 
 The yellow communicated to wool by weld 
 has little permanency, if the wool be not pre- 
 viously prepared by some mordant. For this 
 purpose alum and tartar are used, by means 
 of which this plant gives a very pure yellow, 
 which has the advantage of being perma- 
 n ent. 
 
 For the boiling, which is conducted in the 
 common way, Hellot directs four ounces of 
 alum to every pound of wool, and only one 
 ounce of tartar : many dyers, however, use 
 half as much tartar as alum. Tartar renders 
 the colour paler, but more lively. 
 
 For the welding, that is, for the dyeing 
 with weld, the plant is boiled in a fresh bath, 
 enclosing it in a bag of thin linen, and keep- 
 ing it from rising to the top by means of a 
 heavy wooden cross. Some dyers boil it till 
 it sinks to the bottom of the copper, and then 
 let a cross down upon it: others, when it is 
 boiled, take it out with a rake and throw it 
 -away. 
 
 Flellot directs live or six pounds of weld 
 for every pound of cloth ; but dyers seldom 
 use so much, contenting themselves with 
 three or four pounds, or even much less. 
 
 To dye silk plain yellow, in general no 
 <other ingredient than weld is used. The 
 silk ought to be scoured in the proportion of 
 twenty pounds of soap to the hundred, and 
 afterward alumed and refreshed, that is, 
 washed after the aluming. 
 
 A bath is prepared with two pounds of 
 weld for each pound of silk, which after a 
 quarter of an hour’s boiling is to be passed 
 through a sieve or cloth into a vat : when it 
 is of such a temperature as the hand can 
 bear, the silk is put in, and turned till the 
 colour is become uniform : during this ope- 
 ration the weld is boiled a second time in 
 fresh water ; about* half of the first bath is 
 taken out, and its place supplied by a fresh 
 decoction. This fresh bath may be used a 
 little hotter than the former ; too great a de- 
 gree of heat, however, must be avoided, that 
 no part of the colour already fixed may be dis- 
 solved ; it is to be turned as before, and in the 
 mean time a quantity of the ashes of wine- 
 lees is to be dissolved in a part of the second 
 decoction ; the silk is to be taken out of the 
 bath, that more or less of this solution may 
 be put in, according to the shade required. 
 After it has been turned a few times, a hank 
 is wrung witli the pin, that it may be seen 
 whether the colour be sufficiently full, and 
 have the proper gold cast : if it should not, a 
 little more of the alkaline solution is added, 
 the eflcct of which is to give the colour a 
 gold cast, and to render it deeper. In this 
 way the process is to be continued, until tiie 
 silk has attained the desired shade; the al- 
 
 kaline solution may also be added along with 
 the second decoction of the weld, always tak- 
 ing care, that the bath is not too hot. 
 
 If we wish to produce yellows with more 
 of a gold or jonquille colour, a quantity ot 
 anotta proportioned to the shade required 
 must be added to the bath along with the 
 alkali. 
 
 A water-colour, called weld-yellow, is 
 much used by paper-hanging manufacturers. 
 This is the colouring matter of weld preci- 
 pitated with an earthy base. The following 
 is given in the Philosophical Magazine as a 
 method of preparing it very fine: — Into a 
 copper vessel put four pounds of fine washed 
 whiting and as much soft water, and boil 
 them together, stirring them with a deal 
 stick, till the whole forms a smooth mixture: 
 then add gradually twelve ounces of powder- 
 ed alum, still stirring, till the effervescence 
 ceases, and the whole is well mixed. Into 
 another copper put any quantity of weld, 
 with the roots uppermost, pour in soft, water 
 enough to cover every part containing seed; 
 let it boil, but not more than a quarter of an 
 hour ; take out the weld, and set it to drain ; 
 and pass the whole of the liquor through 
 flannel. To the hot mixture of earth and 
 water add as much of this decoction as will 
 produce a good colour, keep it on the fire 
 till it "boils, and then pour out into a deal or 
 earthen vessel. The next day the liquor 
 may be decanted, and the colour dried on 
 .chalk. 
 
 Welter’s Tube. See Laboratory. 
 
 * Wernerite. Foliated Sea polite. * 
 
 * Wheat Flour. See Gluten and Zi- 
 
 2V10ME. * 
 
 Wheat. See Bread, Gluten, Starch. 
 
 * Whet-slate. Colour greenish-grey. 
 Massive. Feebly glimmering. Fracture 
 slaty in the large ; splintery in the small. 
 Fragments tabular. Translucent on the 
 edges. Streak greyish -white. Soft in a low 
 degree. Feels rather greasy. Sp.gr. 2 . 722 . 
 It occurs in beds in primitive and transition 
 clay-slate. It is found at Seifersdorf near 
 Freyberg. Very fine varieties are brought 
 from Turkey, called Ilonestones. It is used 
 for sharpening steel instruments.* 
 
 Whey. The fluid part of milk which re- 
 mains after the curd has been separated. See 
 Milk. It contains a saccharine matter, some 
 butter, and a small portion of cheese. 
 
 * Whisky. Dilute Alcohol , which see, 
 and Distillation. * 
 
 White Copper. See Tutenag. 
 
 White, Spanish, and White Lead. See 
 Ceruse. 
 
 Whiting. Chalk cleared of its grosser 
 impurities, then ground in a mill, and made 
 up into small loaves, is sold under the name 
 of Whiting. 
 
 Wine. Chemists give the name of wine 
 
WIN 
 
 WIN 
 
 in general to all liquors that havo become 
 spirituous by fermentation. Thus cider, beer, 
 hydromel or mead, and other similar liquors, 
 are wines. 
 
 llie principles and theory of the fermen- 
 tation which produces these liquors are essen- 
 tially the same. The more general princi- 
 ples we have explained under the article 
 Fermentation. 
 
 All those nutritive, vegetable, and animal 
 matters, which contain sugar ready formed, 
 are susceptible of the spirituous fermentation. 
 Thus wine may be made of all the juices of 
 plants, the sap of trees, the infusions and de- 
 coctions of farinaceous vegetables, the milk 
 of frugivorous animals ; and lastly, it may be 
 made of all ripe succulent fruits ; but all 
 these substances are not equally proper to be 
 changed into a good and generous wine. 
 
 As the production of alcohol is the result 
 of the spirituous fermentation, that wine may 
 be considered as essentially the best, which 
 contains most alcohol. But of all substan- 
 ces susceptible of the spirituous fermentation, 
 none is capable of being converted into so 
 good wine, as the juice of the grapes of 
 France, or of other countries that are nearly 
 in the same latitude, or in the same tempe- 
 rature. The grapes of hotter countries, and 
 even those of the southern provinces of 
 France, do indeed furnish wines, that have 
 a more agreeable, that is, more of a saccha- 
 rine taste ; but these wines, though they are 
 sufficiently strong, are not so spirituous as 
 those of the provinces near the middle of 
 France : at least, from these latter wines the 
 best vinegar and brandy are made. As an 
 example, therefore, of spirituous fermenta- 
 tion in general, we shall describe the method 
 of making wine from the juice of the grapes 
 of France. 
 
 This juice, when newly expressed, and be- 
 fore it has begun to ferment, is called must, 
 and in common language sweet wine. It is 
 turbid, has an agreeable and very saccharine 
 taste. It is very laxative ; and when drunk 
 too freely, or by persons disposed to diar- 
 rhoeas, it is apt to occasion these disorders. 
 Its consistence is somewhat less fluid than 
 that of water, and it becomes almost of a 
 pitchy thickness when dried. 
 
 When the must is pressed from the grapes, 
 and put into a proper vessel and place, with 
 a temperature between fifty-five and sixty de- 
 grees, very sensible effects are produced in 
 it, in a shorter or longer time according to 
 the nature of the liquor, and the exposure of 
 the place. It then swells, and is so rarefied, 
 that it frequently overflows the vessel con- 
 taining it, if this be nearly full. An intes- 
 tine motion is excited among its parts, ac- 
 companied with a small hissing noise and 
 evident ebullition. The bubbles rise to t^e 
 surface, and at the same time is disengaged 
 a quantity of carbonic acid of such purity, 
 
 and so subtle and dangerous, that it is capa- 
 ble of killing instantly men and animals ex- 
 posed to it in a place where the air is not re- 
 newed. The skins, stones, and other grosser 
 matters of the grapes are buoyed up by the 
 particles of disengaged air that adhere to 
 their surface, are variously agitated, and are 
 raised in form of a scum or soft and spongy 
 crust, that covers the whole liquor. During 
 the fermentation this crust is frequently rais- 
 ed, and broken by the air disengaged from 
 the liquor which forces its way through it ; 
 afterward the crust subsides, and becomes 
 entire as before. 
 
 These effects continue while the fermenta- 
 tion is brisk, and at last gradually cease: 
 then the crust, being no longer supported, 
 falls in pieces to the bottom of the liquor. 
 At this time, if we would have a strong and 
 generous wine, all sensible fermentation must 
 be stopped. This is done by putting the 
 wine into close vessels, and carrying these 
 into a cellar or other cool place. 
 
 After this first operation, an interval of 
 repose takes place, as is indicated by the 
 cessation of the sensible effects of the spiritu- 
 ous fermentation ; and thus enables us to 
 preserve a liquor no less agreeable in its 
 taste, than useful for its reviving and nutri- 
 tive qualities when drunk moderately. 
 
 If we examine the wine produced by this 
 first fermentation, we shall find, that it dif- 
 fers entirely and essentially from the juice 
 of grapes before fermentation. Its sweet 
 and saccharine taste is changed into one that 
 is very different, though still agreeable, and 
 somewhat spirituous and piquant. It has 
 not the laxative quality of must, but affects 
 the head, and occasions, as is well known, 
 drunkenness. Lastly, if it be distilled, it 
 yields, instead of the insipid water obtained 
 from must by distillation with the heat of 
 boiling water, a volatile, spirituous, and in- 
 flammable liquor called spirit of wine, or al- 
 cohol. This spirit is consequently a new 
 being, produced by the kind of fermentation 
 called the vinous or spirituous. See Al- 
 cohol. 
 
 When any liquor undergoes the spirituous 
 fermentation, all its parts seem not to ferment 
 at the same time, otherwise the fermentation 
 would probably be very quickly completed, 
 and the appearances would he much more 
 striking : hence, in a liquor much disposed 
 to fermentation, this motion is more quick 
 and simultaneous than in another liquor less 
 disposed. Experience has shown, that a wine 
 the fermentation of which is very slow and 
 tedious, is never good or very spirituous ; and 
 therefore, when the weather is too cold, the 
 fermentation is usually accelerated by beat- 
 ing the place in which the wine is made. A 
 proposal has been made bv a person very 
 intelligent in economical affairs, to apply a 
 greater than the usual heat to accelerate the 
 
WIN 
 
 WIN 
 
 fermentation of the wine, in those years in 
 which grapes have not been sufficiently ripen- 
 ed, and when the juice is not sufficiently 
 disposed to fermentation. 
 
 A tOo hasty and violent fermentation is 
 perhaps also hurtful, from the dissipation 
 and loss of some of the spirit; but of this 
 we are not certain. However, we may dis- 
 tinguish in the ordinary method of making 
 wdnes of grapes, two periods in the fermen- 
 tation, the first of which lasts during the ap- 
 pearance of the sensible effects above men- 
 tioned, in which the greatest number of fer- 
 mentable particles ferment. After this first 
 effort of fermentation, these effects sensibly 
 diminish, and ought to be stopped, for rea- 
 sons hereafter to be mentioned. Ihe fer- 
 mentative motion of the liquors then ceases. 
 The heterogeneous parts, that were suspended 
 in the wines by this motion, and render it 
 muddy, are separated, and form a sediment 
 called the lees ; after which the wine be- 
 comes clear ; but though the operation is 
 then considered as finished, and the fermen- 
 tation apparently ceases, it does not really 
 cease ; and it ought to be continued in some 
 degree, if we would have good wine. 
 
 In this new wine a part of the liquor pro- 
 bably remains, that has not fermented, and 
 which afterward ferments, but so very slowly, 
 that none of the sensible effects produced in 
 the first fermentation are here perceived. 
 The fermentation therefore still continues 
 in the wine, during a longer or shorter time, 
 although in an imperceptible manner ; and 
 this is the second period of the spirituous 
 fermentation, which may be called the im- 
 perceptible fermentation. We may easily 
 perceive, that the effect of this imperceptible 
 fermentation is the gradual increase of the 
 quantity of alcohol. It has also another 
 effect no less advantageous, namely, the se- 
 paration of the acid salt called tartar from, 
 the wine. This matter is therefore a second 
 sediment, that is formed in the wine, and 
 adheres to the sides of the containing vessels. 
 As the taste of tartar is harsh and disagree- 
 able, it is evident, that the wine, which by 
 means of the insensible fermentation has ac- 
 quired more alcohol, and has disengaged it- 
 self of the greater part of its tartar, ought to 
 be much better and more agreeable ; and for 
 this reason chiefly old wine is universally 
 preferable to new wine. 
 
 But insensible fermentation can only ripen 
 and meliorate the wine, if the sensible fer- 
 mentation have regularly proceeded, and 
 been stopped in due time. We know cer- 
 tainly, that if a sufficient time have not been 
 allowed for the first period of the fermenta- 
 tion, the un fermented matter that remains, 
 being in too large a quantity, will then fer- 
 ment in the bottles, or close vessels in which 
 the wine is put, and will occasion effects so 
 much more sensible, as the first fermentation 
 
 shall have been sooner interrupted: hence 
 these wines are always turbid, emit bubbles, 
 and sometimes break the bottles, from the 
 large quantity of air disengaged during the 
 fermentation. 
 
 We have an instance of these effects in 
 the wine of Champagne, and in others of the 
 same kind. The sensible fermentation of 
 these wines is interrupted, or rather suppress- 
 ed, that they may have this sparkling quality. 
 It is well known, that these wines make the 
 corks fiy out of the bottles ; that they sparkle 
 and froth when they are poured into glasses; 
 and lastly, that they have a taste much more 
 lively and more piquant than wines that do 
 not sparkle : but this sparkling quality, and 
 all the effects depending on it, are only 
 caused by a considerable quantity of carbonic 
 acid gas, which is disengaged during the 
 confined fermentation, that the wine has 
 undergone in close vessels. This air not 
 having an opportunity of escaping, and of 
 being dissipated as fast as it is disengaged, 
 and being interposed betwixt all the parts of 
 the wine, combines in some measure with 
 them, and adheres in the same manner as it 
 does to certain mineral waters, in which it 
 produces nearly the same effects. When 
 this air is entirely disengaged from these 
 wines, they no longer sparkle, they lose their 
 piquancy of taste, become mild, and even 
 almost insipid. 
 
 Such are the qualities that wine acquires 
 in time, when its first fermentation has not 
 continued sufficiently long. These qualities 
 are given purposely to certain kinds of wine, 
 to indulge taste or caprice ; but such wines 
 are supposed to be unfit for daily use. Wines 
 for daily use ought to have undergone so 
 completely the sensible fermentation, that 
 the succeeding fermentation shall be insen- 
 sible, or at least exceedingly little perceived. 
 Wine, in which the first fermentation has 
 been too far advanced, is liable to w^orse in- 
 conveniences than that in which the first 
 fermentation has been too quickly suppress- 
 ed ; for every fermentable liquor is from its 
 nature in a continual intestine motion, more 
 or less strong according to circumstances, 
 from the first instant of the spirituous fer- 
 mentation till it is completely purified: 
 hence from the time of the completion of 
 the spirituous fermentation, or even before, 
 the w'ine begins to undergo the acid or 
 acetous fermentation. This acid fermenta- 
 tion is very slow and insensible, when the 
 wine is included in very close vessels, and in 
 a cool place ; but it gradually advances, so 
 that in a certain time the wine, instead of 
 being improved, becomes at last sour. This 
 evil cannot be remedied ; because the fer- 
 mentation may advance, but cannot be re- 
 verted. 
 
 Wine- merchants, therefore, when their 
 wines become sour, can only conceal or ab- 
 
WIN 
 
 WIN 
 
 sorb this acidity by certain substances, as by 
 alkalis and absorbent earths. But these 
 substances give to wine a dark greenish co- 
 lour, and a taste which, though not acid, is 
 somewhat disagreeable. Besides, calcareous 
 earths accelerate considerably the total de- 
 struction and putrefaction of the wine. Ox- 
 ides of lead, having the property of forming 
 with the acid of vinegar a salt of an agree- 
 able saccharine taste, which does not alter 
 the colour of the wine, and which besides 
 has the advantage of stopping fermentation 
 and putrefaction, might be very well employ- 
 ed to remedy the acidity of wine, if lead and 
 all its preparations were not pernicious to 
 health, as they occasion most terrible colics, 
 and even death, when taken internally. We 
 cannot believe that any wine-merchant, 
 knowing the evil consequences of lead, 
 should, for the sake of gain, employ it for 
 the purpose mentioned ; but if there be any 
 such persons, they must be considered as the 
 poisoners and murderers of the public. At 
 Alicant, where very sweet wines are made, it 
 is the practice, to mix a little lime with the 
 grapes before they are pressed. This, how- 
 ever, can only neutralize the acid already ex- 
 isting in the grape. 
 
 If wine contain litharge, or any other 
 oxide of lead, it may be discovered by eva- 
 porating some pints of it to dryness, and 
 melting the residuum in a crucible, at the 
 bottom of which a small button of lead may 
 be found after the fusion : but an easier and 
 more expeditious proof is by pouring into 
 the wine some liquid sulphuret. If the pre- 
 cipitate occasioned by this addition of the 
 sulphuret be white, or only coloured by the 
 wine, we may know, that no lead is con- 
 tained in it: but if the precipitate be dark 
 coloured, brown, or blackish, we may con- 
 clude, that it contains lead or iron. 
 
 The only substances that cannot absorb or 
 destroy, but cover and render supportable 
 the sharpness of wine, without any incon- 
 venience, are sugar, honey, and other sac- 
 charine alimentary matters ; but they can 
 succeed only when the wine is very little 
 acid, and when an exceeding small quantity 
 only of these substances is sufficient to pro- 
 duce the desired effect; otherwise the wine 
 would have a sweetish, tart, and not agree- 
 able taste. 
 
 From what is here said concerning the 
 acescency of wine, we may conclude, that 
 when this accident happens, it cannot by 
 any good method be remedied, and that no- 
 thing remains to be done with sour wine but 
 to sell it to vinegar-makers, as all honest 
 wine-merchants do. 
 
 * As the must of the grape contains a 
 notable proportion of tartar, which our cur- 
 rant and gooseberry juices do not, I have 
 been accustomed, for many years, to recom- 
 
 mend in my lectures, the addition of a small 
 portion of that salt to our must , to make it 
 ferment into a more genuine wine. Dr 
 M k Cul!och has lately prescribed the same 
 addition in his popular treatise on the art of 
 making wine. 
 
 The following is Mr Brande’s valuable 
 table ol the quantity ol spirit in different 
 kinds of wine 
 
 1. Lissa, . . . . 
 
 Ditto . . 
 
 Proportion of 
 spirit per cent 
 by measure. 
 
 . . . . 26.47 
 
 . . . . 24.35 
 
 Average, 25.4 1 
 
 2. Raisin wine, 26.40 
 
 Ditto 25. 77 
 
 Ditto 23,20 
 
 Average, 25,12 
 
 3. Marsala, „ 26. 3 
 
 Ditto 25. 5 
 
 Average, 25. 9 
 
 4. Madeira, 24.42 
 
 Ditto 23.93 
 
 Ditto (Sircial) 21.40 
 
 Ditto . 19.24 
 
 Average, 22.27 
 
 5. Currant wine, ...... 20.55 
 
 6. Sherry, 1 D.81 
 
 Ditto ] 9.83 
 
 Ditto 18.79 
 
 Ditto 1 8.25 
 
 Average, 19.17 
 
 7. Tenerifle, 19.79 
 
 8. Colares, 19.75 
 
 9. Lachryma Christi, . . . . . ] 9.70 
 
 10. Constantia, white, .... 1 9.75 
 
 11. Ditto red, 18.92 
 
 12. Lisbon, 18.94 
 
 IS. Malaga, (1666) 18.94 
 
 14. Bucellas, 18.49 
 
 15. Red Madeira, 22.30 
 
 Ditto 18.40 
 
 Average, 20.35 
 
 16. Cape Muschat, 18.25 
 
 17. Cape Madeira, 22.94 
 
 Ditto 20.50 
 
 Ditto . . . * . . 18.11 
 
 Average, 20.51 
 
 18. Grape wine, 18.11 
 
 1 9. Calcavella, 1 9.20 
 
 Ditto 18.10 
 
 Average, 18.65 
 
 20. Vidonia, 19.25 
 
 21. Alba Flora, 17.26 
 
 22. Malaga, 17.26 
 
 23. White Hermitage, .... 17.43 
 
 24. Rousillon, 1 9.00 
 
 Ditto 1 7.26 
 
 Average, 18.18 
 
 25. Claret, 1 7.1 1 
 
 Ditto 16.32 
 
 Ditto ) 4.08 
 
 Ditto * • . 12.91 
 
 Average, 15.10 
 
WOA 
 
 WOD 
 
 Proportion of 
 spirit percent 
 by measure. 
 
 26. Malmsey Madeira, • . . . 16.40 
 
 27. Lunel, 15.52 
 
 28. Sheraaz, 15.52 
 
 29. Syracuse, . . . . ♦ . . 15.28 
 
 30. Sauterne, 14.22 
 
 31. Burgundy, . ..... 16.60 
 
 Ditto . . 15.22 
 
 Ditto 14.53 
 
 Ditto 11.95 
 
 Average, 14.57 
 
 32. Hock, 14.37 
 
 Ditto ■' 13.00 
 
 Ditto (old in cask) .... 8.88 
 
 i Average, 12.08 
 
 S3. Nice, 14.65 
 
 34. Barsac, 13.86 
 
 35. Tent, 13.30 
 
 36. Champagne, (still) .... 13.80 
 
 Ditto (sparkling) . . . 1 2.80 
 
 Ditto (red) .... 12.56 
 
 Ditto (ditto) .... 11.30 
 
 Average, 12.61 
 
 37. Red Hermitage, 12.32 
 
 38. Yin de Grave, 15.94 
 
 Ditto ] 2.80 
 
 Average, 13.57 
 
 39. Frontignac, 12.79 
 
 40. Cote Rotie, 12.32 
 
 41. Gooseberry wine, 11.84 
 
 42. Orange wine, — average of six sam- 
 
 ples made by a London manu- 
 
 facturer, 11 .26 
 
 43. Tokay, 9.88 
 
 44. Elder wine, 9.87 
 
 45. Cyder, highest average, . . . 9.87 
 
 Ditto lowest ditto .... 5.21 
 
 46. Perry, average of four samples, 7.26 
 
 47. Mead, 7.52 
 
 48. Ale (Burton) 8.88 
 
 Ditto (Edinburgh) .... 6.20 
 
 Ditto (Dorchester) .... 5.56 
 
 Average, 6.87 
 
 49. Brown stout, 6.80 
 
 50. London Porter (average) . . 4.20 
 
 51. Ditto small beer, (ditto) . . 1.28 
 
 52. Brandy, 53.39 
 
 53. Rum, 53.68 
 
 54. Gin, 51.60 
 
 55. Scotch Whisky, 54.32 
 
 56. Irish ditto 53.90 
 
 * With f. rite. Carbonate of barytes. 
 
 "See Heavy- Spar.* 
 
 Wo ad, Isatis, Glastum, is a plant which 
 grows wild in some parts of France, and on 
 the coasts of the Baltic Sea ; the wild woad, 
 and that which is cultivated for the use of 
 the dyers, appear to be the same species of 
 plant. 
 
 The preparation of woad for dyeing, as 
 practised in France, is minutely described 
 by Astruc, in his Memoirs for a Natural 
 History of Languedoc. — The plant puts 
 
 forth at first five or six upright leaves about 
 a foot long and six inches broad ; when 
 these hang downwards, and turn yellow, 
 they are fit for gathering ; five crops are 
 gathered in one year. The leaves are car- 
 ried directly to a mill, much resembling the 
 oil or tan-mills, and ground into a smooth 
 paste, if this ^process were deferred for 
 some time, they would putrefy, and send 
 forth an insupportable stench. The paste is 
 laid in heaps pressed close and smooth, and 
 the blackish crust, which forms on the out- 
 side, reunited if it happen to crack : if this 
 were neglected, little worms would be pro- 
 duced in the cracks, and the woad would 
 lose part of its strength. After lying for 
 fifteen days, the heaps are opened, the crust 
 rubbed and mixed with the inside, and the 
 matter formed into oval balls, which are 
 pressed close and solid in wooden moulds. 
 These are dried upon hurdles : in the sun 
 they turn black on the outside, in a close 
 place yellowish, especially if the weather be 
 rainy. The dealers in this commodity pre- 
 fer the first, though it is said the workmen 
 find no considerable difference between the 
 two. The good balls are distinguished by 
 their being weighty, of a pretty agreeable 
 smell, and, when rubbed, of a violet colour 
 within. 
 
 For the use of the dyer these balls require 
 a farther preparation ; they are beaten with 
 wooden mallets, on a brick or stone floor, 
 into a gross powder, which is heaped up in 
 the middle of the room to the height of four 
 feet, a space being left for passing round the 
 sides. The powder moistened with water 
 ferments, grows hot, and throws out a thick 
 fetid fume. It is shovelled backward and 
 forward, and moistened every day for twelve 
 days ; afrer which it is stirred less frequent- 
 ly, without watering, and at length made 
 into a heap for the dyer. 
 
 The powder thus prepared gives only 
 brownish tinctures of different shades to 
 water, to alcohol, to ammonia, and to fixed 
 alkaline lixivia ; rubbed on paper, it com- 
 municates a green stain. On diluting the 
 powder with boiling water, and, after stand- 
 ing for some hours in a close vessel, adding 
 about one-twentieth its weight of lime newly 
 slaked, digesting in a gentle warmth, and 
 stirring the whole together every three or 
 four hours, a new fermentation begins ; a 
 blue froth rises to the surface, and the liquor, 
 though it appears itself of a reddish colour, 
 dyes woollen of a green ; which, like the 
 green from indigo, changes in the air to a 
 blue. This is one of the nicest processes in 
 the art of dyeing, and does not well succeed 
 in the way of a small experiment. 
 
 * Wodanium. A new metal recently 
 discovered by Lampadius in the mineral 
 called Woodan pyrites. This metal has a 
 bronze-yellow colour, similar to that of co- 
 
YTT 
 
 YTT 
 
 bait glance ; and its sp. gr. is 1 1.470. It is 
 malleable ; its fracture is hackly ; it has the 
 hardness of fluor spar ; and is strongly at- 
 tracted by the magnet. 
 
 It is not tarnished by exposure to the atmos- 
 phere at the common temperature ; but when 
 heated it is converted into a black oxide. 
 
 I he solution of this metal in acids is co- 
 lourless ; or at least has only a slight wine- 
 yellow tinge. Its hydrated carbonate is also 
 white. The hydrate, precipitated by caustic 
 ammonia, is indigo-blue. 
 
 Neither the alkaline phosphates nor arse- 
 niates, occasion any precipitate, when drop- 
 ped into a saturated solution of this metal 
 in an acid ; nor is any precipitate produced 
 by the infusion of galls. A plate of zinc 
 throws down a black metallic powder from 
 the solution of this metal in muriatic acid. 
 Prussiate of potash throws down a pearl- 
 grey precipitate. 
 
 Nitric acid dissolves with facility both the 
 metal and its oxide, and the solution yields 
 colourless needle-form crystals, which readily 
 dissolve in water. — Gilbert's Annalen (ler 
 Physik> September 1818.* 
 
 * Woodan Py kites. See Ores of Wo- 
 
 DANIUM. * 
 
 * Wood (Opal). See Opal.* 
 
 Wood (Rock). The ligniform asbestus. 
 
 * W ood- stone. A sub-species of horn- 
 stone. * 
 
 * Wood-tin. See Ores of Tin. 
 
 Wootz. The metal extracted from some 
 
 kind of iron ore in the East Indies, appa- 
 rently of good quality. It contains more 
 carbon than steel, and less than cast-iron, 
 but from want of skill in the management is 
 far from homogeneous. — Phil. Trans. 
 
 * Wort. See Beer, Distillation, and 
 Fermentation.* 
 
 * Wolfram. See Ores of Tungsten.* 
 
 Y 
 
 •'W'ANOLITE. Axinite.* 
 
 X * Yeast. See Fermentation, and 
 Bread.* 
 
 * Yellow Earth. Colour ochre-yellow. 
 Massive. Dull. Fracture slaty or earthy. 
 Streak somewhat shining. Opaque. Soils 
 slightly. Soft. Easily frangible. Adheres 
 to the tongue. Feels rather greasy. Sp. 
 gr. 2.24. Before the blow-pipe it is con- 
 verted into a black and shining enamel. 
 Its constituents are, silica 92, alumina 2, 
 lime 5, iron 3 . — Merat Guillot. It is found 
 at Wehraw in Upper Lusatia, where it is 
 associated with clay and clay- ironstone. 
 When burnt, it is sold by the Dutch as a 
 pigment, under the name of English red. 
 It was used as a yellow paint by the an- 
 cients. * 
 
 * Yenite. Lievrite. * 
 
 Yttria. This is a new earth, discovered 
 in 1794 by Prof. Gadolin in a stone from 
 Ytterby in Sweden. See Gadolinite. 
 
 It may be obtained most readily by fusing 
 the gadolinite with two parts of caustic 
 potash, washing the mass with boiling water, 
 and filtering the liquor, which is of a fine 
 green. This liquor is to be evaporated, till 
 no more oxide of manganese falls down from 
 it in a black powder ; after which the liquid 
 is to be saturated with nitric acid. At the 
 same time digest the sediment, that was not 
 dissolved, in very dilute nitric acid, which 
 will dissolve the earth with much heat, leav- 
 ing the silex, and the highly oxided iron, 
 undissolvcd. Mix the two liquors, evapo- 
 rate them to dryness, redissolve, and filter, 
 which will separate any silex or oxide of iron 
 that may have been left. A few drops of a 
 
 solution of carbonate of potash will separato 
 any lime that may be present, and a cau- 
 tious addition of hydrosulphuret of potash 
 will throw down the oxide of manganese 
 that may have been left ; but if too much 
 be employed, it will throw down the yttria 
 likewise. Lastly, the yttria is to be preci- 
 pitated by pure ammonia, well washed, and 
 dried. 
 
 Yttria is perfectly white, when not con- 
 taminated with oxide of manganese, from 
 which it is not easily freed. Its specific gra- 
 vity is 4.842. It has neither taste nor smell. 
 It is infusible alone ; but with borax melts 
 into a transparent glass, or opaque white if 
 the borax were in excess. It is insoluble 
 in water, and in caustic fixed alkalis ; but it 
 dissolves in carbonate of ammonia, though 
 it requires five or six times as much as glu- 
 cine. It is soluble in most of the acids. 
 The oxalic acid, or oxalate of ammonia, 
 forms precipitates in its solutions perfectly 
 resembling the muriate of silver. Prussiate 
 of potash, crystallized and redissolved in 
 w r ater, throws it dow n in white grains ; phos- 
 phate of soda, in white gelatinous fiakes ; in- 
 fusion of galls, in brown flocks. 
 
 Some chemists are inclined to consider 
 yttria rather as a metallic than as an earthy 
 substance ; their reasons are its specific gra- 
 vity, its forming coloured salts, and its pro- 
 perty of oxygenizing muriatic acid after it 
 has undergone a long calcination. — Crcll's 
 Chan. An. — Scherer s Joum. — Annales dc 
 Chimie. 
 
 * When yttria is treated with potassium 
 in the same manner as the other earths, 
 similar results are obtained ; the potassium 
 
ZEO 
 
 ZEO 
 
 becomes potash, and the earth gains appear- 
 ances of metallization, so that it is scarcely 
 to be doubted, says Sir H. Davy, that yttria 
 consists of inflammable matter, metallic in 
 its nature, combined with oxygen. Ac- 
 cording to Klaproth, 55 parts of yttria com- 
 bine with 1 8 parts of carbonic acid ; conse- 
 quently, if it be supposed that the carbonate 
 of yttria consists of one prime proportion of 
 earth and one of acid, its prime equivalent 
 will be 8.403 ; and that of its metallic basis 
 probably 7.4. The salts of yttria have the 
 following general characters: — 
 
 1. Many of them are insoluble in water. 
 
 2. Precipitates are occasioned in those 
 which dissolve, by phosphate of soda, car- 
 bonate of soda, oxalate of ammonia, tartrate 
 of potash, and ferroprussiate of potash. 
 
 S. If we except the sweet-tasted soluble 
 sulphate of yttria, the other salts of this 
 earth resemble those with base of lime in 
 their solubility.* 
 
 * Yttro-Tantalite. An ore of Tan- 
 talum.* 
 
 * Yttro- Cerite. Colours reddish and 
 greyish-white, and violet-blue. Massive, and 
 in crusts. Cleavage indistinct. Opaque. 
 Yields to the knife. Scratches fluor. Sp. 
 gr. 5.447. Its constituents are, oxide of 
 cerium 13.15, yttria 14.6, lime 47.77, fluoric 
 acid 24.45. — Berzelius. It has hitherto 
 been found only at Finbo, near Fahlun in 
 Sweden, imbedded in quartz, or incrusting 
 pyrophysalite.* 
 
 Z AFFRE, or SAFFRE, is the residuum 
 of cobalt, after the sulphur, arsenic, 
 and other volatile matters of this mineral 
 have been expelled by calcination. 
 
 The zaffre that is commonly sold, and 
 which comes from Saxony, is a mixture of 
 oxide of cobalt with some vitrifiable earth. 
 It is of a grey colour, as all the oxides of 
 cobalt are before vitrification. 
 
 * Zeolite. The name of a very exten- 
 sive mineral genus, containing the following 
 species : — 1. Dodecahedral zeolite or leu- 
 cite ; 2. hexahedral zeolite or analcime ; 5. 
 rhomboidal zeolite, chabasite, or chabasie; 
 4. pyramidal zeolite, or cross stone ; 5. di- 
 plomatic zeolite, or laumonite; 6. prisma- 
 tic zeolite, or mesotype, divided into three 
 sub-species, — fibrous zeolite, natrolite, and 
 mealy zeolite ; 7. prismatoidal zeolite, or stil- 
 bite, comprehending foliated zeolite, and ra- 
 diated zeolite ; 8. axifrangible zeolite, or apo- 
 phyllite. The following belong to this place : 
 6. Prismatic zeolite or mesotype. 
 
 § 1. Fibrous zeolite , of which there are 
 two kinds ; the acicular or needle zeolite, 
 and common fibrous zeolite. 
 
 a. Acicular or needle zeolite, the meso- 
 type of Haiiy. Colours greyish, yellowish 
 or reddish- white. Massive, in distinct con- 
 cretions, and crystallized. Primitive form, 
 a prism of 91° 25'. The following are se- 
 condary figures: — An acicular rectangular 
 four-sided prism, very flatly acuminated with 
 four planes, set on the lateral planes; some- 
 times two of the acuminating planes disap- 
 pear, when there is formed an acute bevel- 
 rnent, or the prism is sometimes truncated 
 on the edges. Lateral planes longitudi- 
 nally streaked. Shining, inclining to pearly. 
 Cleavage twofold. Fracture small grained 
 uneven. Fragments splintery. Translucent. 
 
 Refracts double. As hard as apatite. Brit- 
 tle. Sp. gr. 2.0 to 2.3. It intumesces be- 
 fore the blow-pipe, and forms a jelly with 
 acids. It becomes elastic by heating, and 
 retains this property some time after it has 
 cooled. The free extremity of the crystal 
 with the acumination, shews positive, the at- 
 tached end, negative electricity. Its consti- 
 tuents are, silica 50.24, alumina 29.3, lime 
 9.46, water 10. — Vauquelin. It occurs in 
 
 secondary trap rocks, as in basalt, green- 
 stone, and amygdaloid. It is found near 
 the village of Old Kilpatrick, Dumbarton- 
 shire; in Ayrshire and Perthshire, always 
 in trap rocks ; in Iceland and the Faroe 
 Islands. 
 
 b. Common Jibr ous zeolite. Colour white. 
 Massive, in distinct concretions, and in ca- 
 pillary crystals. Glimmering, pearly. Frag- 
 ments splintery. Faintly translucent. Hard- 
 ness as before. Rather brittle. Sp. gr. 
 2.16 to 2.2. Chemical characters and si- 
 tuations as above. Its constituents are, si- 
 lica 49, alumina 27, soda, 17, water 9.5. — 
 Smithson. 
 
 § 2. Mealy zeolite. Colour white, of various 
 shades. Massive, imitative, in a crust, or in 
 delicate fibrous concretions. Feebly glim- 
 mering. Fracture coarse earthy. Opaque. 
 The mass is soft, but the minute parts as 
 hard as the preceding. Sectile. Most easily 
 frangible. Does not adhere to the tongue. 
 Feels meagre. Sometimes so light as nearly 
 to float on water. It intumesces, and gela- 
 tinizes as the preceding. Its constituents 
 are, silica 60, alumina 15.6, lime 8, oxide 
 of iron 1.8, loss, by exposure to heat, 11.6. 
 — Hisinger. It occurs like the others. It 
 is found near Tantallon-castle, in East Lo- 
 thian, and in the islands of Skye, Mull, aiul 
 Canna. 
 
ZIM 
 
 ZIN 
 
 7. Prismatoidal zeolite , or stilbite. Of 
 this there are two sub-species ; the foliated 
 and radiated. 
 
 § 1. Foliated zeolite , the stilbite of Haiiy. 
 Colour white, of various shades. Massive, 
 disseminated, imitative, in distinct Granular 
 concretions, and crystallized. Primitive 
 form, a prism of 99° 22'. Secondary forms 
 are, a low oblique four-sided prism, variously 
 truncated ; a low equiangular six-sided prism ; 
 and an eight-sided prism, from truncation of 
 all the edges of the four-sided prism. La- 
 teral planes transversely streaked. Shining, 
 pearly. Cleavage single. Fracture con- 
 choidal. Translucent. Refracts single. As 
 hard as calcareous spar. Brittle. Sp. gr. 
 2. to 2.2. It intumesces and phosphoresces 
 before the blow-pipe, but does not form a 
 jelly with acids. Its constituents are, silica 
 52.6, alumina 17.5, lime 9, water 18.5. — 
 Vauquelin. It occurs principally in secon- 
 dory amygdaloid, either in drusy cavities, or 
 in contemporaneous veins. It is also met 
 with in primitive and transition mountains. 
 Very beautiful specimens of the red foliated 
 and radiated zeolites are found at Carbeth in 
 Stirlingshire, and at Loch Humphrey in 
 Dumbartonshire ; also in the secondary trap 
 rocks of the Hebrides, as of Skye, Canna, 
 and Mull ; and in the north of Ireland. 
 
 § 2. Radiated zeolite. Stilbite of Haiiy. 
 Colours yellowish-white and greyish-white. 
 Massive, in angular pieces, in prismatic and 
 granular concretions, and crystallized in a 
 rectangular four-sided prism, variously mo- 
 dified by acuminations. Shining, pearly. 
 Translucent. Hardness and chemical cha- 
 racters as above. Brittle. Sp. gr. 2.14. 
 Its constituents are, silica 40.98, alumina 
 39.09, lime 10.95, water 16.5. — Meyer. Its 
 situations are as the preceding. — Jameson .* 
 
 * Zero. The commencement of a scale 
 marked O. Thus w*e say the zero of Fah- 
 renheit, which is 32° below the melting 
 point of ice ; the zero of the centigrade scale, 
 which coincides with the freezing of water. 
 The absolute zero, is the imaginary point in 
 the scale of temperature, when the whole 
 heat is exhausted ; the term of absolute cold, 
 or privation of caloric. See Caloric.* 
 
 * Zimome. The gluten of wheat, treat- 
 ed by alcohol, is reduced to the third part 
 of its bulk. This diminution is owing, 
 not merely to the loss of gliadine, but 
 likewise to that of water. The residue is 
 zimome, which may be obtained pure by 
 boiling it repeatedly in alcohol, or by di- 
 gesting it in repeated portions of that li- 
 quid cold, till it no longer gives out any 
 gliadine. See Gliadine. 
 
 Zimome thus purified has the form of 
 small globules, or constitutes a shapeless 
 mass, which is hard, tough, destitute of co- 
 hesion, and of an ash-white colour. When 
 
 washed in water, it recovers part of its vis- 
 cosity, and becomes quickly brown, when 
 left iu contact of the air. It is specifically 
 heavier than water. Its mode of ferment- 
 ing is no longer that of gluten ; for when it 
 putrefies, it exhales a fetid urinous odour. 
 It dissolves completely in vinegar, and in 
 the mineral acids at a boiling temperature. 
 AV ith caustic potash, it combines and forms 
 a kind of soap. When put into lime-water, 
 or into the solutions of the alkaline carbo- 
 nates, it becomes harder, and assumes a new 
 appearance without dissolving. When thrown 
 upon red-hot coals, it exhales an odour si- 
 milar to that of burning hair or hoofs, and 
 burns with flame. 
 
 Zimome is to be found in several parts of 
 vegetables. It produces various kinds of 
 fermentation, according to the nature of the 
 substance with which it comes in contact. * 
 
 Zinc is a metal of a bluish-white colour, 
 somewhat brighter than lead ; of considera- 
 ble hardness, and so malleable as not to be 
 broken with the hammer, though it cannot 
 be much extended in this way. It is very 
 easily extended by the rollers of the flatting 
 mill. Its sp. gr. is from 6.9 to 7.2. In a 
 temperature between 210° and 300° of F., 
 it has so much ductility that it can be drawn 
 into wire, as well as laminated, for which a 
 patent has been obtained by Messrs Hobson 
 and Sylvester of Sheffield. The zinc thus 
 annealed and wrought retains the malleabi- 
 lity it had acquired. 
 
 When broken by bending, its texture ap- 
 pears as if composed of cubical grains. On 
 account of its imperfect malleability, it is 
 difficult to reduce it into small parts by filing 
 or hammering ; but it may be granulated, 
 like the malleable metals, by pouring if, 
 when fused, into cold water; or, if it be 
 heated nearly to melting, it is then suffi- 
 ciently brittle to be pulverized. 
 
 It melts long before ignition, at about the 
 700th degree of Fahrenheit’s thermometer ; 
 and, soon ^fter it becomes red-hot, it burns 
 with a dazzling white flame, of a bluish or 
 yellowish tinge, and is oxidized with such 
 rapidity, that it flies up in the form of white 
 flowers, called the flowers of zinc, or philoso- 
 phical wool. These are generated so plen- 
 tifully, that the access of air is soon inter- 
 cepted ; and the combustion ceases, unless 
 the matter be stirred, and a considerable 
 heat kept up. The white oxide of zinc is 
 not volatile, but is driven up merely by the 
 force of the combustion. When it is again 
 urged by a strong heat, it becomes convert- 
 ed into a clear yellow glass. If zinc be 
 heated in closed vessels, it rises without de- 
 composition. 
 
 * The oxide of zinc, according to the ex- 
 periments of MM. Gay Lussac and Berze- 
 lius, consists of 100 metal -f- 2.44 oxygen; 
 
ZIN 
 
 ZIN 
 
 whence the prime equivalent appears to be 
 4.1. Sir H. Davy makes it 4.4 from his 
 own and his brother’s experiments. 
 
 When zinc is burned in chlorine, a solid 
 substance is formed of a whitish-grey colour, 
 and semi-transparent. This is the only 
 chloride of zinc, as there is only one oxide 
 of the metal. It may likewise be made by 
 heating together zinc filings and corrosive 
 sublimate. It is as soft as wax, fuses at a 
 temperature a little above 212°, and rises in 
 the gaseous form at a heat much below 
 ignition. Its taste is intensely acrid, and it 
 corrodes the skin. It acts upon water, and 
 dissolves in it, producing much heat ; and 
 its solution, decomposed by an alkali, affords 
 the white hydrated oxide of zinc. This 
 chloride has been called butter °f zinc , and 
 muriate of zinc. From the experiments of 
 Dr John Davy, it consists of nearly equal 
 weights of zinc and chlorine. The equiva- 
 lent proportions appear to be,— 
 
 Zinc 4.1 chlorine 4.5 
 Or Zinc 4.4 + 4.5. 
 
 Blende is the native sulphuret of zinc. 
 The two bodies are difficult to combine arti- 
 ficially. The salts of zinc possess the fol- 
 lowing general characters : — 
 
 1. They generally yield colourless solu- 
 tions with water. 
 
 2. Ferroprussiate of potash, hydrosulphu- 
 ret of potash, hydriodate of potash, sulphu- 
 retted hydrogen, and alkalis, occasion white 
 precipitates. 
 
 3. Infusion of galls produces no precipi- 
 tate. * 
 
 The diluted sulphuric acid dissolves zinc ; 
 at the same time that the temperature of the 
 solvent is increased, and much hydrogen 
 escapes, an undissolved residue is left, which 
 has been supposed to consist of plumbago. 
 Proust, however, says, that it is a mixture 
 of arsenic, lead, and copper. As the com- 
 bination of the sulphuric acid and the oxide 
 proceeds, the temperature diminishes, and 
 the sulphate of zinc, which is more soluble 
 in hot than cold water, begins to separate, 
 and disturb the transparency of the fluid. 
 If more water be added, the salt may be 
 obtained in fine prismatic four-sided crys- 
 tals. The white vitriol, or copperas, usually 
 sold, is crystallized hastily, in the same man- 
 ner as loaf-sugar, which on this account it 
 resembles in appearance ; it is slightly efflo- 
 rescent. The white oxide of zinc is soluble 
 in the sulphuric acid, and forms the same 
 salt as is afforded by zinc itself. 
 
 The hydrogen gas, that is extricated from 
 water by the action of sulphuric acid, carries 
 up with it a portion of zinc, which is appa- 
 rently dissolved in it ; but this is deposited 
 spontaneously, at least in part, if not wholly, 
 by standing. It burns with a brighter flame 
 than common hydrogen. 
 
 Sulphate of zinc is prepared in the large 
 way from some varieties of the native sul- 
 phuret. The ore is roasted, wetted with 
 water, and exposed to the air. The sulphur 
 attracts oxygen, and is converted into sul- 
 phuric acid; and the metal, being at the 
 same time oxidized, combines with the acid. 
 After some time the sulphate is extracted 
 by solution in water ; and the solution be- 
 ing evaporated to dryness, the mass is run 
 into moulds. Thus the white vitriol of the 
 shops, generally contains a small portion of 
 iron, and sometimes of lead. 
 
 Sulphurous acid dissolves zinc, and sul- 
 phuretted hydrogen is evolved. The solu- 
 tion, by exposure to the air, deposits needly 
 crystals, which, according to Fourcroy and 
 Vauquelin, are sulphuretted sulphite of zinc. 
 By dissolving oxide of zinc in sulphurous 
 acid, the pure sulphite is obtained. This is 
 soluble, and crystallizable. 
 
 Diluted nitric acid combines rapidly with 
 zinc, and produces much heat, at the same 
 time that a large quantity of nitrous air flies 
 off. The solution is very caustic, and affords 
 crystals by evaporation and cooling, which 
 slightly detonate upon hot coals, and leave 
 oxide of zinc behind. This salt is deliques- 
 cent. 
 
 Muriatic acid acts very strongly upon 
 zinc, and disengages much hydrogen ; the 
 solution, when evaporated, does not afford 
 crystals, but becomes gelatinous. By a 
 strong heat it is partly decomposed, a por- 
 tion of the acid being expelled, and part of 
 the muriate sublimes and condenses in a 
 congeries of prisms. 
 
 Phosphoric acid dissolves zinc. The phos- 
 phate does not crystallize, but becomes gela- 
 tinous, and may be fused by a strong heat. 
 The concrete phosphoric acid heated with 
 zinc filings is decomposed. 
 
 Fluoric acid likewise dissolves zinc. 
 
 The boracic acid digested with zinc be- 
 comes milky ; and if a solution of borax be 
 added to a solution of muriate or nitrate of 
 zinc, an insoluble borate of zinc is thrown 
 down. 
 
 A solution of carbonic acid in water dis- 
 solves a small quantity of zinc, and more 
 readily its oxide. If the solution be exposed 
 to the air, a thin iridescent pellicle forms on 
 its surface. 
 
 The acetic acid readily dissolves zinc, and 
 yields by evaporation crystals of acetate of 
 zinc, forming rhomboidal or hexagonal plates. 
 These are not altered by exposure to the air, 
 are soluble in water, and bum with a blue 
 flame. 
 
 The succinic acid dissolves zinc with ef- 
 fervescence, and the solution yields long, 
 slender, foliated crystals. 
 
 Zinc is readily dissolved in benzoic acid, 
 and the solution yields needle-shaped cry- 
 stals, which are soluble both in water and in 
 
ZIN 
 
 ZIN 
 
 alcohol. Heat decomposes them by volati- 
 lizing their acid. 
 
 lhe oxalic acid attacks zinc with a violent 
 effervescence, and a white powder soon sub- 
 sides, which is oxalate of zinc. If oxalic acid 
 be dropped into a solution of sulphate, nitrate, 
 or muriate ot zinc, the same salt is precipi- 
 tated ; it being scarcely soluble in water uti- 
 less an excess of acid be present. It con- 
 tains seventy- five per cent of metal. 
 
 The tartaric acid likewise dissolves zinc 
 with effervescence, and forms a salt difficult 
 of solution in water. 
 
 The citric acid attacks zinc with efferves- 
 cence, and small brilliant crystals of citrate 
 of zinc are gradually deposited, which are in- 
 soluble in water. Their taste is styptic and 
 metallic, and they are composed of equal 
 parts of the acid and of oxide of zinc. 
 
 The malic acid dissolves zinc, and affords 
 beautiful crystals by evaporation. 
 
 Lactic acid acts upon zinc with efferves- 
 cence, and produces a crystallizable salt. 
 
 The metallic acids likewise combine with 
 zinc. If arsenic acid be poured on it, an 
 effervescence takes place, arsenical hydrogen 
 gas is emitted, and a black powder falls 
 down, which is arsenic in the metallic state, 
 the zinc having deprived a portion of the 
 arsenic, as well as the water, of its oxygen. 
 If one part of zinc filings and two parts of 
 dry arsenie acid be distilled in a retort, a 
 violent detonation takes place when the re- 
 tort becomes red, occasioned by the sudden 
 absorption of the oxygen of the acid by the 
 zinc. The arseniate of zinc may be precipi- 
 tated by pouring arsenic acid into the solu- 
 tion of acetate of zinc, or by mixing a solu- 
 tion of an alkaline arseniate with that of 
 sulphate of zinc. It is a white powder, in- 
 soluble in water. 
 
 By a similar process zinc may be com- 
 bined with the molybdic acid, and with the 
 oxide of tungsten, the tungstic acid of some, 
 with both of which it forms a white insolu- 
 ble compound ; and with the chromic acid, 
 the result of which compound is equally in- 
 soluble, but of an orange- red colour. 
 
 Zinc likewise forms some triple salts. 
 Thus, if the white oxide of zinc be boiled in 
 a solution of muriate of ammonia, a consi- 
 derable portion is dissolved ; and though 
 part of the oxide is again deposited as the 
 solution cools, some of it remains combined 
 with the acid and alkali in the solution, 
 and is not precipitable either by pure alkalis, 
 or their carbonates. This triple salt does 
 not crystallize. 
 
 If the acidulous tartrate of potash be boil- 
 ed in water with zinc filings, a triple com- 
 pound will be formed, which is very soluble 
 in water, but not easily crystallized. This, 
 like the preceding, cannot be precipitated 
 from its solution either by pure or carbo- 
 nated alkalis. 
 
 A triple sulphate of zinc and iron may be 
 formed by mixing together the sulphates of 
 lion and of zinc dissolved in water, or by 
 dissolving iron and zinc in dilute sulphuric 
 acid. This salt crystallizes in rhomboids, 
 which nearly resemble the sulphate of zinc 
 in figure, but are of a pale green colour. 
 In taste, and in degree of solubility, it dif- 
 fers little from the sulphate of zinc. It con- 
 tains a much larger proportion of zinc than 
 of iron. 
 
 A triple sulphate of zinc and cobalt, as 
 first noticed by Link, may be obtained by 
 digesting zaffre in a solution of sulphate of 
 zinc. On evaporation, large quadrilateral 
 prisms are obtained, which effloresce on ex- 
 posure to the air. 
 
 Zinc is precipitated from acids by the 
 soluble earths and the alkalis : the latter 
 redissolve the precipitate, if they be added 
 in excess. 
 
 Zinc decomposes, or alters, the neutral 
 sulphates in the dry way. When fused with 
 sulphate of potash, it converts that salt into 
 a sulphuret : the zinc at the same time being 
 oxidized, and partly dissolved in the sulphu- 
 ret. When pulverized zinc is added to fused 
 nitre, or projected together with that salt 
 into a red-hot crucible, a very violent de- 
 tonation takes place ; insomuch that it is 
 necessary for the operator to be careful in 
 using only small quantities, lest the burning 
 matter should be thrown about. The zinc 
 is oxidized, and part of the oxide combines 
 with the alkali, with which it forms a com- 
 pound soluble in water. 
 
 Zinc decomposes common salt, and also 
 sal ammoniac, by combining'with the muriatic 
 acid. The filings of zinc likewise decom- 
 pose alum, when boiled in a solution of that 
 salt, probably by combining wfith its excess 
 of acid. 
 
 Zinc may be combined with phosphorus, 
 by projecting small pieces of phosphorus on 
 the zinc melted in a crucible, the zinc being 
 covered with a little resin, to prevent its 
 oxidation. Phosphuret of zinc is white, 
 with a shade of bluish-grey, has a metallic 
 lustre, and is a little malleable. When zinc 
 and phosphorus are exposed to heat in a 
 retort, a red sublimate rises, and likewise a 
 bluish sublimate, in needly crystals, with a 
 metallic lustre. If zinc and phosphoric 
 acid be heated together, with or without a 
 little charcoal, needly crystals are sublimed, 
 of a silvery-white colour. All these, ac- 
 cording to Pelletier, are phosphuretted ox- 
 ides of zinc. 
 
 Most of the metallic combinations of zinc 
 have been already treated ot. It forms a 
 brittle compound w ith antimony ; and its 
 effects on manganese, tungsten, and molyb- 
 dena, have not yet been ascertained. 
 
 Zirconia w'as first discovered in the jar- 
 gon of Ceylon by Klaproth, in 1739, and it 
 
21 R 
 
 ZOO 
 
 has since been found in the jacinth. To 
 obtain it, the stone should be calcined and 
 thrown into cold water, to render it friable, 
 and then powdered in an agate mortar. Mix 
 the powder with nine parts of pure potash, 
 and project the mixture by spoonfuls into a 
 red-hot crucible, taking care that each por- 
 tion is fused before another is added. Keep 
 the whole in fusion, with an increased heat, 
 for an hour and half. When cold, break 
 the crucible, separate its contents, powder, 
 and boil in water, to dissolve the alkali. 
 Wash the insoluble part ; dissolve in muria- 
 tic acid ; heat the solution, that the silex 
 may fall down ; and precipitate the zircon 
 by caustic fixed alkali. Or the zircon may 
 be precipitated by carbonate of soda, and the 
 carbonic acid expelled by heat. 
 
 * New Process for preparing pure Zireonia. 
 
 Powder the zircons very fine, mix them 
 with two parts of pure potash, and heat them 
 red-hot in a silver crucible, for an hour. 
 Treat the substance obtained with dis- 
 tilled water, pour it on a filter, and wash 
 the insoluble part well ; it will be a com- 
 pound of zireonia, silex, potash, and oxide 
 of iron. Dissolve it in muriatic acid, and 
 evaporate to dryness, to separate the silex. 
 Redissolve the muriates of zireonia and 
 iron in water; and to separate the zireonia 
 which adheres to the silex, wash it with 
 weak muriatic acid, and add this to the so- 
 lution. Filter the fluid, and precipitate the 
 zireonia and iron by pure ammonia ; wash 
 the precipitates well, and then treat the hy- 
 drates with oxalic acid, boiling them well 
 together, that the acid may act on the iron, 
 retaining it in solution, whilst an insoluble 
 oxalate of zireonia is formed. It is then to 
 be filtered, and the oxalate washed, until no 
 iron can be detected in the water that passes. 
 The earthy . oxalate is, when dry, of an opa- 
 line colour. After being well washed, it is 
 to be decomposed by heat in a platinum 
 crucible. 
 
 Thus obtained, the zireonia is perfectly 
 pure, but is not affected by acids. It must 
 be reacted on by potash as before, and then 
 washed until the alkali is removed. After- 
 wards dissolve it in muriatic acid, and preci- 
 pitate by ammonia. The hydrate thrown 
 down, when well washed, is perfectly pure, 
 and easily soluble in acids. — MM. Dubois 
 and Silveira , Ann. de Ckimie , et. de Phys. 
 xiv. p. 110.* 
 
 Zircon is a fine white powder, without 
 taste or smell, but somewhat harsh to the 
 touch. It is insoluble in water ; yet if slow- 
 ly dried, it coalesces into a semi-transparent 
 yellowish mass, like gum-arabic, which re- 
 tains one-third its weight of water. It 
 unites with all the acids. It is insoluble in 
 pure alkalis; but the alkaline carbonates 
 dissolve it. Heated with the blow-pipe it 
 
 does not melt, but emits a yellowish phos- 
 phoric light. Heated in a crucible of char" 
 coal, bedded in charcoal powder, placed in 
 a stone crucible, and exposed to a good 
 forge fire for some hours, it undergoes a 
 pasty fusion, which unites its particles into 
 a grey opaque mass, not truly vitreous, but 
 more resembling porcelain. In this state it 
 is sufficiently hard to strike fire with steel, 
 and scratch glass ; and is of the specific gra- 
 vity of 4.3. 
 
 * There is the same evidence for believ- 
 ing that zireonia is a compound of a metal 
 and oxygen, as that afforded by the action 
 of potassium on the other earths. The al- 
 kaline metal, when brought into contact with 
 zireonia ignited to whiteness, is, for the most 
 part, converted into potash, and dark par- 
 ticles, which, when examined by a magnify- 
 ing glass, appear metallic in some parts, of 
 a chocolate-brown in others, are found dif- 
 fused, through the potash and the decom- 
 pounded earth. 
 
 According to Sir H. Davy, 4.66 is the 
 prime equivalent of zirconium on the oxygen 
 scale, and 5.66 that of zireonia. * 
 
 * Zoisitje. A sub-speeies of prismatoidal 
 augite, which is divided into two kinds, the 
 common and friable. 
 
 § 1. Common xoisite . Colour yellowish- 
 grey. Massive, in granular and prismatic 
 concretions, and crystallized in very oblique 
 four-sided prisms, in which the obtuse late- 
 ral edges are often rounded, so that the 
 crystals have a reed-like form. Shining, or 
 glistening and resino- pearly. Cleavage, 
 double. Fracture small grained uneven. 
 Feebly translucent. As hard as epidote. 
 Very easily frangible. Sp. gr. 3.3. It is 
 affected by the blow-pipe, as epidote. Its 
 constituents are, silica 43, alumina 29, lime 
 21, oxide of iron 3. — Klaproth. At the 
 Saualp in Carinthia, it is found imbedded in 
 a bed of quartz, along with cyanite, garnet, 
 and augite ; or it takes the place of felspar 
 in a granular rock, composed of quartz and 
 mica. It is found in Glen Elg in Inver- 
 nesshire, and in Shetland. 
 
 § 2. Friable zoisite. Colour reddish- 
 white, which is spotted with pale peach-blos- 
 som red. Massive, and in very fine loosely 
 aggregated granular concretions. Feebly 
 glimmering. Fracture intermediate between 
 earthy and splintery. Translucent on the 
 edges. Semi-hard. Brittle. Sp. gr. 3.3. 
 Its constituents are, silica 44, alumina 32, 
 lime 20, oxide of iron 2.5. — Klaproth. It 
 occurs imbedded in green talc, at ltadelgra- 
 ben in Carinthia.* 
 
 Zoophytes. Scarcely any chemical ex- 
 periments have been published on these in- 
 teresting subjects, if we except the admirable 
 dissertation by Mr Hatchett, in the Philoso- 
 phical Transactions for 1 800. From this 
 
 3 A 
 
zoo 
 
 ZUN 
 
 dissertation, and from a few experiments of 
 Merat-Guillot, we learn, that the hard zoo- 
 phytes are composed chiefly of three ingre- 
 dients: 1. An animal substance of the na- 
 ture of coagulated albumen, varying in con- 
 sistency ; sometimes being gelatinous and 
 almost liquid, at others of the consistency of 
 cartilage. 2. Carbonate of lime. 3 . Phos- 
 phate of lime. 
 
 In some zoophytes, the animal matter is 
 very scanty, and phosphate of lime wanting 
 altogether ; in others the animal matter is 
 abundant, and the earthy salt pure carbo- 
 , oate of lime ; while in others the animal 
 matter is abundant, and the hardening salt 
 a mixture of carbonate of lime and phos- 
 phate of lime ; and there is a fourth class al- 
 most destitute of earthy salts altogether. 
 Thus, there are four classes of zoophytes; 
 the first resemble porcellaneous shells ; the 
 second resemble mother-of-pearl shells ; the 
 third resemble crusts ; and the fourth 
 horn . 
 
 1. When the madrepora virginea is im- 
 mersed in diluted nitric acid, it effervesces 
 strongly, and is soon dissolved. A few ge- 
 latinous particles float in the solution, which 
 is otherwise transparent and colourless. Am- 
 monia precipitates nothing ; but its carbonate 
 throws down abundance of carbonate of 
 lime. It is composed, then, of carbonate 
 of lime and a little animal matter. The 
 following zoophytes yield nearly the same 
 results : - — 
 
 Madrepora muricata, 
 
 — labyrinthicaj 
 
 Millepora cerulea, 
 
 alcicornis, 
 
 Tubipora musica. 
 
 2. When the madrepora ramea is plunged 
 into weak nitric acid, an effervescence is 
 equally produced; but after all the soluble 
 part is taken up, there remains a membrane 
 which retains completely the original shape 
 of the madrepore. The substance taken up 
 is pure lime. Hence, this madrepore is com- 
 posed of carbonate of lime, and a membra- 
 naceous substance, which, as in mother-ol- 
 pearl shells, retains the figure of the madre- 
 pore. The following zoophytes yield nearly 
 the same results: — 
 
 Madrepora fascicularis, 
 
 Millepora cellulosa, 
 
 fascialis, 
 
 — truncata, 
 
 Iris hippuris. 
 
 The following substances, analyzed by 
 Merat-Guillot, belong to this class from 
 their composition, though it is difficult to 
 say what are the species of zoophytes which 
 were analyzed. By red coral , he probably 
 meant the gorgonia nobilis, though that sub- 
 stance is known, from Hatchett’s analysis, 
 to contain also some phosphate : — 
 
 Animal matter, 
 
 White 
 
 licit 
 
 Articulated 
 
 coral. 
 
 coral. 
 
 coralline. 
 
 , 50 
 
 53.5 
 
 49 
 
 50 
 
 4G.5 
 
 51 
 
 100 
 
 100.0 
 
 lOOf 
 
 S. W hen the madrepora polymorpha is 
 steeped in weak nitric acid, its shape con- 
 tinues unchanged ; there remaining a tough 
 membranaceous substance of a white colour 
 and opaque, filled with a transparent jelly. 
 The acid solution yields a slight precipitate 
 of phosphate of lime, when treated with 
 ammonia, and carbonate of ammonia throws 
 down a copious precipitate of carbonate of 
 lime. It is composed, therefore, of animal 
 substance, partly in the state of jelly, partly 
 in that of membrane, and hardened by car- 
 bonate of lime, together with a little phos- 
 phate of lime. 
 
 Flusirajbliacea, treated in the same man- 
 ner left a finely reticulated membrane, which 
 possessed the properties of coagulated albu- 
 men. The solution contained a little phos- 
 phate of lime, and yielded abundance of car- 
 bonate of lime when treated with the alka- 
 line carbonates. The corallina opuntia , 
 treated in the same manner, yielded the 
 same constituents ; with this difference, that 
 no phosphate of lime could be detected in 
 the fresh coralline, but the solution of burnt 
 coralline yielded traces of it. The iris och- 
 racca exhibits the same phenomena, and is 
 formed of the same constituents. When 
 dissolved in weak nitric acid, its colouring 
 matter falls in the state of a fine red pow- 
 der, neither soluble in nitric nor muriatic 
 acid, nor changed by them ; whereas the 
 tingeing matter of the tubipora musica is de- 
 stroyed by these acids. The branches of 
 this iris are divided by a series of knots. 
 These knots are cartilaginous bodies con- 
 nected together by a membraneous coat. 
 Within this coat there is a conical cavity 
 filled with the earthy or coralline matter; 
 so that, in the recent state, the branches of 
 the iris are capable of considerable motion, 
 the knots answering the purpose of joints. 
 
 See Coral. 
 
 Mr Hatchett analyzed many species of 
 sponges, but found them all similar in their 
 composition. The spongia cancellata , ocu- 
 lata, irifundibuliformis, palmata , and offici- 
 nalis, may be mentioned as specimens. They 
 consist of gelatine, which they gradually 
 give out to water, and a thin brittle mem- 
 branous substance, which possesses the pro- 
 perties of coagulated albumen. 
 
 * Zumates. Combinations of the zumic 
 acid with the salifiable bases.* 
 
 * Zumic Acid. See Acid (Zumic).* 
 
 Zundererz. Tinder ore. An ore of 
 
 silver. 
 
 f Merat-Guillot, Ann. de Chim. xxxxw 7L 
 
APPENDIX, 
 
 * 
 
 * Containing several Tables referred to in the body of the Work. Many important 
 Tables usually placed at the end of Chemical Treatises are inserted under the particular ar- 
 ticles to which they belong. Thus the Tables of the Mineral Acids will be found under 
 Acid (Muriatic), (Nitric), and (Sulphuric). For others, see Acid in general, Alcohol, 
 Attraction, Caloric, Climate, Coal-gas, Combustion, Equivalents, Electricity, Gas, 
 Hydrometer, Light, Metal, Rain, Salt, Water (Mineral), Wine, &c. &c. 
 
 I.— -Dr Wollaston s Numerical Table of Chemical Equivalents. 
 
 Dr Wollaston’s numbers represent the weights of the atoms of bodies, oxygen being 
 
 
 
 called ten. 
 
 
 
 1. 
 
 Hydrogen - 
 
 1.32 
 
 
 Black oxide ( 1 25.5 mercury) 
 
 261.00 
 
 2. 
 
 Oxygen - 
 
 10.00 
 
 30. 
 
 Lead - — — 
 
 129.50 
 
 3. 
 
 Water - 
 
 11.32 
 
 
 Litharge (10 oxygen) 
 
 139.50 
 
 4. 
 
 Carbon ... 
 
 7.54 
 
 81. 
 
 Silver ... 
 
 1 35.00 
 
 5. 
 
 Carbonic acid (20 oxygen) 
 
 27.54 
 
 
 Oxide (10 oxygen) 
 
 145.00 
 
 6. 
 
 Sulphur - 
 
 20.00 
 
 32. 
 
 Sub-carbonate of ammonia 
 
 49.00 
 
 7. 
 
 Sulphuric acid (30 oxygen) 
 
 50.00 
 
 
 Bi-carbonate (27.5 carbonic acid) 76.50 
 
 8. 
 
 Phosphorus 
 
 17.40 
 
 33. 
 
 Sub- carbonate of soda 
 
 66.6 0 
 
 9. 
 
 Phosphoric acid (20 oxygen) 
 
 37.40 
 
 
 Bi-carbonate (27.5 C. A. -f 
 
 
 10. 
 
 Azote or Nitrogen 
 
 17.54 
 
 
 11.3 water) 
 
 105.50 
 
 11. 
 
 Nitric acid (50 oxygen) 
 
 67.54 
 
 34. 
 
 Sub- carbonate of potash 
 
 86.00 
 
 12. 
 
 Muriatic acid, dry 
 
 34.10 
 
 
 Bi-carbonate (27.5 C. A. -f 
 
 
 13. 
 
 Oxymuriatic acid (10 oxygen) 
 
 44.10 
 
 
 11.3 water) 
 
 125.50 
 
 14. 
 
 Chlorine 44.10 + 1.32 hydro- 
 
 
 35. 
 
 Carbonate of lime 
 
 63.00 
 
 
 gen = muriatic acid gas 
 
 45.42 
 
 36. 
 
 barytes *» 
 
 124.50 
 
 15. 
 
 Oxalic acid 
 
 47.0 
 
 37. 
 
 lead 
 
 167.00 
 
 16. 
 
 Ammonia 
 
 21.5 
 
 38. 
 
 Sulphuric acid dry 
 
 50.00 
 
 17. 
 
 Soda - 
 
 39.1 
 
 39. 
 
 Do. sp. gr. 1.850 (50 -f 11.3 
 
 
 18. 
 
 Sodium (above — 10 oxygen) 
 
 29.1 
 
 
 water) 
 
 61.30 
 
 19. 
 
 Potash 
 
 59.1 
 
 40. 
 
 Sulphate of soda (10 water = 
 
 
 20. 
 
 Potassium (above — 10 oxygen) 
 
 49.1 
 
 
 113.2) 
 
 202.30 
 
 21. 
 
 Magnesia 
 
 24.6 
 
 41. 
 
 Sulphate of potash 
 
 109.10 
 
 22. 
 
 Lime - 
 
 35.46 
 
 42. 
 
 Sulphate of magnesia dry 
 
 74.60 
 
 23. 
 
 Calcium (above — 10 oxygen) 
 
 25.46 
 
 
 Do. crystallized (7 water = 
 
 
 24. 
 
 Strontites 
 
 69.00 
 
 
 79.3) 
 
 153.90 
 
 25. 
 
 Barytes - 
 
 97.00 
 
 43. 
 
 Sulphate of lime dry 
 
 85.50 
 
 26. 
 
 Iron - 
 
 84.50 
 
 
 Crystallized (2 water = 22.64) 108.10 
 
 
 Black oxide (10 oxygen) 
 
 44.50 
 
 44. 
 
 Sulphate of strontites 
 
 1 1 9.00 
 
 
 Red oxide (15 oxygen) 
 
 49.50 
 
 45. 
 
 barytes 
 
 147.00 
 
 27. 
 
 Copper - 
 
 40.00 
 
 46. 
 
 — copper (1 acid + 1 
 
 
 
 Black oxide (10 oxygen) 
 
 50.00 
 
 
 oxide -p 5 water) 
 
 156.60 
 
 28. 
 
 Zinc - - 
 
 41.00 
 
 47. 
 
 iron (7 water) 
 
 1 73.80 
 
 
 Oxide (10 oxygen) 
 
 51.00 
 
 48. 
 
 zinc (do.) 
 
 1 80.20 
 
 29. 
 
 Mercury 
 
 125.50 
 
 49. 
 
 lead 
 
 1 89.50 
 
 
 Red oxide (10 oxygen) 
 
 135.50 
 
 50. 
 
 Nitric acid dry 
 
 67.54 
 

 Nitric acid, sp. gr. 1.50 (2 water 
 
 
 59. 
 
 Muriate of lime 
 
 169.60 
 
 
 = 22.64) 
 
 90.20 
 
 60. 
 
 barytes 
 
 131.00 
 
 51. 
 
 Nitrate of soda 
 
 106.60 
 
 61. 
 
 — lead 
 
 1 73.60 
 
 52. 
 
 potash 
 
 126.60 
 
 62. 
 
 silver 
 
 179.10 
 
 53. 
 
 lime 
 
 108.00 
 
 63. 
 
 mercury 
 
 170.10 
 
 54. 
 
 barytes 
 
 164.50 
 
 64. 
 
 Sub-muriate of do. (1 acid -f 1 
 
 
 55. 
 
 lead 
 
 207.00 
 
 
 oxygen -f 2 mercury) 
 
 296.10 
 
 56'. 
 
 Muriate of ammonia 
 
 66.90 
 
 65. 
 
 Phosphate of lead 
 
 176.90 
 
 57. 
 
 soda 
 
 73.20 
 
 66. 
 
 Oxalate of lead 
 
 186.50 
 
 58. 
 
 potash 
 
 93.20 
 
 67. 
 
 Bin-oxalate of potash 
 
 153.00 
 
 
 Oxymuriate of do. (GOoxygen) 
 
 153.20 
 
 
 
 
 * TABLES exhibiting a collective View of all the Erigorific Mixtures contained in 
 
 Mr Walker s Publication , 1808. 
 
 II* — TABLE, consisting of Frigorifc Mixtures, having the Power of generating , or creating 
 Cold , without the aid of Ice, sufficient for all useful and Philosophical purposes, in any 
 part of the World at any Season . 
 
 Frigorific Mixtures without Ice. 
 
 MIXTURES. 
 
 Thermometer sinks. 
 
 Deg. of cold 
 produced. 
 
 Muriate of ammonia - 5 parts 
 
 Nitrate of potash - - 5 
 
 Water - - - 16 
 
 From -f- 50° to -f- 10 ° 
 
 40° 
 
 Muriate of ammonia - 5 parts 
 
 Nitrate of potash 5 
 
 Sulphate of soda 8 
 
 Water - - - 16 
 
 From + 50° to 4 - 4° 
 
 46 
 
 Nitrate of ammonia - 1 part 
 
 Water - 1 
 
 From 4 - 50° to 4 - 4° 
 
 46 
 
 Nitrate of ammonia - 1 part 
 
 Carbonate of soda - - 1 
 
 Water - - 1 
 
 From 4 - 50° to — 7° 
 
 57 
 
 Sulphate of soda - - 3 parts 
 
 Diluted nitric acid 2 
 
 From 4 - 50° to — 3° 
 
 53 
 
 Sulphate of soda 6 parts 
 
 Muriate of ammonia ... 4 
 
 Nitrate of potash 2 
 
 Diluted nitric acid 4 
 
 From 4 - 50° to — 10° 
 
 60 
 
 Sulphate of soda 6 parts 
 
 Nitrate of ammonia 5 
 
 Diluted nitric acid - - 4 
 
 From 4 - 50° to — 14° 
 
 64 
 
 Phosphate of soda - - 9 parts 
 
 Diluted nitric acid - - 4 
 
 From 4 - 50° to — 12 ° 
 
 62 
 
 Phosphate of soda - - 9 parts 
 
 Nitrate of ammonia 6 
 
 Diluted nitric acid - 4 
 
 From 4 - 50° to — 21° 
 
 71 
 
 Sulphate of soda - 8 parts 
 
 Muriatic acid - - 5 
 
 From 4 - 50° to 0 ° 
 
 50 
 
 Sulphate of soda 5 parts 
 
 Diluted sulphuric acid - 4 
 
 From 4 - 50° to 4 - 3° 
 
 47 
 
 N. If the materials are mixed at a warmer temperature, than that expressed in the 
 
 Table, the effect will be proportionably greater ; thus, if the most powerful of these mix- 
 tures be made, when the air is + 8 5°, it will sink the thermometer to + 2°. 
 
 47 
 
Ill TABLE consisting of Frigorific Mixtures, composed of Ice, with chemical Salts and Acids* 
 
 Frigorific Mixtures with Ice. 
 
 MIXTURES. Thermometer sinks. ^r^uced? 
 
 Snow, or pounded ice - 2 parts 
 
 Muriate of soda - 1 
 
 From any temperature 
 
 o 
 
 to 
 
 l 
 
 o 
 
 4^ 
 
 * 
 
 Snow, or pounded ice - 5 parts 
 
 Muriate of soda - - 2 
 
 Muriate of ammonia - 1 
 
 o 
 
 CN 
 
 r-* 
 
 1 
 
 o 
 
 * 
 
 Snow, or pounded ice - 24 parts 
 
 Muriate of soda - - 10 
 
 Muriate of ammonia - 5 
 
 Nitrate of potash 5 
 
 to — 1 8° 
 
 * 
 
 Snow, or pounded ice - 12 parts 
 
 Muriate of soda - -5 
 
 Nitrate of ammonia - 5 
 
 to — 25° 
 
 * 
 
 Snow - 3 parts 
 
 Diluted sulphuric acid - 2 
 
 From -f 32° to — 23° 
 
 55 
 
 Snow 8 parts 
 
 Muriatic acid - 5 
 
 From + 32° to — 27° 
 
 59 
 
 Snow ^ 7 parts 
 
 Diluted nitric acid - 4 
 
 From + 32° to — 30° 
 
 62 
 
 Snow - 4 parts 
 
 Muriate of lime - - 5 
 
 From + 32 0 to — 40° 
 
 72 
 
 Snow - 2 parts 
 
 Cryst. muriate of lime - 3 
 
 From + 32° to — 50° 
 
 82 
 
 Snow 3 parts 
 
 Potash - 4 
 
 From + 32° to — 51° 
 
 83 
 
 N. B. — The reason for the omissions in the last column of this Table, is, the thermometer sinking In these 
 mixtures to the degree mentioned in the preceding column, and never lower, whatever maybe the tempe- 
 rature of the materials at mixing. 
 
 IV .— -TABLE consisting of Frigorific Mixtures selected from the foregoing Tables , and 
 combined so as to increase or extend Cold to the extremest Degrees . 
 
 Combinations of Frigorific Mixtures. 
 
 MIXTURES. 
 
 Thermometer sinks. 
 
 Deg. of cold 
 produced. 
 
 Phosphate of soda - - 5 parts 
 
 Nitrate of ammonia - S 
 
 Diluted nitric acid - 4 
 
 From 0° to — 34^ 
 
 S4 
 
 Phosphate of soda - - 3 parts 
 
 Nitrate of ammonia - 2 
 
 Diluted mixed acids - 4 
 
 From — 34° to — 50° 
 
 16 
 
 Snow - 3 parts 
 
 Diluted nitric acid - 2 
 
 From 0° to — 46° 
 
 46 
 
 Snow - 8 parts 
 
 Diluted sulphuric acid - 3 
 
 Diluted nitric acid 3 
 
 From — 10° to — 56° 
 
 46 
 
 Snow - 1 part 
 
 Diluted sulphuric acid - 1 
 
 From — 20° to — 60° 
 
 40 
 
 Snow - - 3 parts 
 
 Muriate of lime 4 
 
 From + 20 to — 48° 
 
 68 
 
 Snow - 3 parts 
 
 Muriate of lime 4 
 
 From 4- 10° to — 54° 
 
 64 
 
 Snow - - - 2 parts 
 
 Muriate of lime - 3 
 
 From — 1 5° to — 68° 
 
 53 
 
 Snow 1 part 
 
 Cryst. muriate of lime - 2 
 
 From 0° to — 66° 
 
 66 
 
 Snow ... 1 part 
 
 Cryst. muriate of lime - 3 
 
 From — 40° to — 73° 
 
 33 
 
 Snow 8 parts 
 
 Diluted sulphuric acid - 10 
 
 From — 68° to — 91° 
 
 23 
 
 N. B.— The materials in the first column are to be cooled, previously to mixing, to the temperature re 
 quired, by mixtures taken from either of the preceding tables.* 
 
^ • — TABLE of Capacities <f different Substances for Caloric . 
 
 in this Table, the authorities are marked by the initials of the respective authors’ names. 
 C. Crawford: K. Kirvvan: Ir. Irvine: G. Gadolin : L. Lavoisier: W. Wilcke : M. 
 Meyer. 
 
 Gases. 
 
 1. Hydrogen gas - 21.4000 
 
 C. 
 
 4. Aqueous vapour 
 
 1 .5500 
 
 c. 
 
 2. 
 
 Oxygen gas 
 
 4.7490 
 
 — 
 
 5. Carbonic acid gas 
 
 1.6454 
 
 — 
 
 S. 
 
 Atmospheric air 
 
 1.7900 
 
 — 
 
 6. Nitrogen gas 
 
 .7936 
 
 — 
 
 
 
 
 Liquids. 
 
 
 
 
 7. 
 
 Solution of carbonate of 
 
 
 
 33. 
 
 Solution of sulphate of 
 
 
 
 
 ammonia, 
 
 1.8510 
 
 K. 
 
 
 iron in 2.5 of water 
 
 .7340 
 
 K. 
 
 8. 
 
 Solution of brown sugar 
 
 1.0860 
 
 — 
 
 34. 
 
 Solution of sulphate of 
 
 
 
 9. 
 
 Alcohol (15.44) 
 
 1.0860 
 
 
 
 soda in 2.9 of water - 
 
 .7280 
 
 — 
 
 10, 
 
 Arterial blood 
 
 1.0300 
 
 C. 
 
 35. 
 
 Olive oil 
 
 .7100 
 
 — 
 
 11. 
 
 Water 
 
 1 .0000 
 
 
 36. 
 
 Water of ammonia, sp. gr. 
 
 
 
 12. 
 
 Cows’ milk 
 
 .9999 
 
 C. 
 
 
 0.997 
 
 .7080 
 
 K. 
 
 13. 
 
 Sulphuret of ammonia 
 
 ;9940 
 
 K. 
 
 37. 
 
 Muriatic acid, sp. gr. 1 . 1 22 
 
 .6800 
 
 — 
 
 14. 
 
 Solution of muriate of so- 
 
 
 
 38. 
 
 Sulphuric acid, 4 parts 
 
 
 
 
 da, ] in 10 of vrater - 
 
 .9360 
 
 G. 
 
 
 with 5 of water 
 
 .6631 
 
 L. 
 
 15. 
 
 Alcohol (9.44) 
 
 .9300 
 
 Ir. 
 
 39. 
 
 Nitric acid, sp.gr. 1.29895 
 
 .6613 
 
 — 
 
 16. 
 
 Sulphuric acid, diluted 
 
 
 
 40. 
 
 Solution of alum in 4.45 
 
 
 
 
 with 10 of water 
 
 .9250 
 
 G. 
 
 
 of water 
 
 .6490 
 
 M. 
 
 17. 
 
 Solution of muriate of so- 
 
 
 
 41. 
 
 Mixture of nitric acid with 
 
 
 
 
 da, in 6.4 of water - 
 
 .9050 
 
 G. 
 
 
 lime, 9y to 1 
 
 .6189 
 
 L. 
 
 18. 
 
 Venous blood 
 
 .8928 
 
 C. 
 
 42. 
 
 Sulphuric acid, with an 
 
 
 
 19. 
 
 Sulphuric acid, with 5 
 
 
 
 
 equal weight of water 
 
 .6050 
 
 G. 
 
 
 parts of water 
 
 .8760 
 
 G. 
 
 43. 
 
 Sulphuric acid, 4 parts 
 
 
 
 20. 
 
 Solution of muriate of so- 
 
 
 
 
 with 3 of water 
 
 .6031 
 
 L. 
 
 
 da, in 5 of water 
 
 .8680 
 
 G. 
 
 44. 
 
 Alcohol (9. 15) 
 
 .6021 
 
 c. 
 
 21. 
 
 Nitric acid (39) 
 
 .8440 
 
 K. 
 
 45. 
 
 Nitrous acid, sp. gr. 1.354 
 
 .5760 
 
 K. 
 
 22. 
 
 Solution of sulphate of 
 
 
 
 46. 
 
 Linseed oil 
 
 .5280 
 
 — 
 
 
 magnesia, in 2 of water 
 
 .8440 
 
 — 
 
 47. 
 
 Spermaceti oil (5S) 
 
 .5000 
 
 C. 
 
 23. 
 
 Solution of muriate of so- 
 
 
 
 48. 
 
 Sulphuric acid, with \ of 
 
 
 
 
 da in 8 of water 
 
 .8320 
 
 — 
 
 
 water - 
 
 .5000 
 
 G. 
 
 24. Solution of muriate of so- 
 
 da in S. 33 of water 
 
 25. Solution of nitrate of pot- 
 
 ash in 8 of water 
 
 26. Solution of muriate of so- 
 
 da in 2.8 of water 
 
 27. Solution of muriate of 
 
 ammonia in 1.5 of water 
 
 28. Solution of muriate of so- 
 
 da saturated, or in 2.69 
 of water 
 
 29. Solution of supertartrate of 
 
 potash in 237.3 of water 
 
 30. Solution of carbonate of 
 
 potash 
 
 31. Colourless sulphuric acid 
 
 (51.55,56,57) 
 
 32. Sulphuric acid, with 2 
 
 parts of water 
 
 63. Ice - 
 
 64. - 
 
 65. Ox hide with the hair 
 
 66. Sheep’s lungs - 
 
 67. Beef of an ox 
 
 .8200 
 
 .8167 
 
 .8020 
 
 .7980 
 
 G. 
 
 L. 
 
 G. 
 
 K. 
 
 49. 
 
 50. 
 
 51. 
 
 52. 
 
 53. 
 
 54. 
 
 55. 
 
 .4720 K. 
 
 Oil of turpentine (52) 
 
 Sulphuric acid, with % of 
 water - 
 
 Sulphuric acid (31.55,56,57) 
 
 Oil of turpentine (49) - 
 
 Spermaceti oil (47) 
 
 Red wine vinegar 
 Sulphuric acid, concen- 
 trated and colourless (31). 3390 
 56. Sulphuric acid, sp. gr. 
 
 .4420 
 
 .4290 
 
 .4000 
 
 .3990 
 
 .3870 
 
 G. 
 
 C. 
 
 Ir. 
 
 K. 
 
 G. 
 
 .7930 
 
 G. 
 
 1.87058 
 
 .3345 
 
 L. 
 
 
 
 57. Sulphuric acid (31.51 ) - 
 
 .3330 
 
 Ir. 
 
 .7650 
 
 K. 
 
 58. Spermaceti melted 
 
 .3200 
 
 — 
 
 
 
 59. Quicksilver, sp. gr. 13.30 
 
 .0330 
 
 K. 
 
 .7590 
 
 MM 
 
 60. Quicksilver 
 
 .0290 
 
 I,. 
 
 
 
 61. 
 
 .0290 
 
 W. 
 
 .7580 
 
 — 
 
 62. 
 
 .0280 
 
 Ir. 
 
 .7490 
 
 G. 
 
 
 
 
 
 Solids. 
 
 
 
 .9000 
 
 K. 
 
 68. Scotch fir wood 
 
 .6500 
 
 I\I. 
 
 .8000 
 
 Ir. 
 
 69. Lime tree Avood 
 
 .2600 
 
 — 
 
 .7870 
 
 C. 
 
 70. Spruce fir wood 
 
 .6000 
 
 — 
 
 .7690 
 
 — 
 
 71. Pitch pine wood 
 
 .5800 
 
 — 
 
 .7400 
 
 — 
 
 72. Apple tree wood 
 
 .5700 
 
 
73. 
 
 Alder wood 
 
 .5300 
 
 — 
 
 74. 
 
 Sessile-leaved oak 
 
 .5100 
 
 — 
 
 75. 
 
 Ash wood - 
 
 .5100 
 
 — 
 
 76. 
 
 Pear tree wood 
 
 .5000 
 
 — 
 
 77. 
 
 Rice - 
 
 .5060 
 
 c. 
 
 78. 
 
 Horse-beans 
 
 .5020 
 
 — 
 
 79. 
 
 Dust of the pine tree 
 
 .5000 
 
 — 
 
 80. 
 
 Pease - - - 
 
 .4920 
 
 — 
 
 81. 
 
 Beech - - - 
 
 .4900 
 
 M. 
 
 82. 
 
 Hornbean wood 
 
 .4800 
 
 — 
 
 83. 
 
 Birch wood 
 
 .4800 
 
 — 
 
 84. 
 
 Wheat - 
 
 .4770 
 
 C. 
 
 85. 
 
 Elm 
 
 .4700 
 
 M. 
 
 86. 
 
 White wax 
 
 .4500 
 
 G. 
 
 87. 
 
 Pedunculated oak wood 
 
 .4500 
 
 M. 
 
 88. 
 
 Prune tree 
 
 .4400 
 
 — 
 
 89. Ebony wood 
 
 90. Quicklime, with water, in 
 
 .4300 
 
 “ 
 
 the proportion of 16 to 9 .4391 L. 
 
 91. Barley - - .4210 C. 
 
 92. Oats - - - .4160 — 
 
 93. Charcoal of birch wood (99) .3950 G. 
 
 94. Carbonate of magnesia .3790 — 
 
 95. Prussian blue - - .3300 — 
 
 96. Quicklime saturated with 
 
 
 water and dried 
 
 .2800 
 
 G. 
 
 97. 
 
 Pit coal - 
 
 .2777 
 
 C. 
 
 98. 
 
 Artificial gypsum 
 
 .2640 
 
 G. 
 
 99. 
 
 Charcoal (93) - * 
 
 .2631 
 
 C. 
 
 100. 
 
 Chalk (108) 
 
 .2564 
 
 — 
 
 101. 
 
 Rust of iron 
 
 .2500 
 
 — 
 
 102. 
 
 White clay 
 
 .2410 
 
 G. 
 
 103. 
 
 White oxide of antimony 
 washed 
 
 .2272 
 
 C. 
 
 204. 
 
 Oxide of copper 
 
 .2272 
 
 — 
 
 105. 
 
 Quicklime (107) 
 
 .2239 
 
 — 
 
 106. 
 
 Muriate of soda in crystals 
 
 .2260 
 
 G. 
 
 107. 
 
 Quicklime (105) 
 
 .2168 
 
 L. 
 
 108. 
 
 Chalk (100) 
 
 .2070 
 
 G. 
 
 109. 
 
 Crown glass - • - 
 
 .2000 
 
 lr. 
 
 210. 
 
 Agate, sp. gr. 2.648 
 
 .1950 
 
 W. 
 
 111. 
 
 Earthen ware 
 
 .1950 
 
 K. 
 
 112. 
 
 Crystal glass without lead 
 
 .1929 
 
 L. 
 
 113. 
 
 Cinders - 
 
 .1923 
 
 C. 
 
 114. Sulphur » 
 
 .1890 
 
 Ir. 
 
 115. 
 
 Ashes of cinders 
 
 .1855 
 
 C. 
 
 116. 
 
 White glass, sp. gr. 2.586 
 
 .1870 
 
 W. 
 
 117. 
 
 White clay burnt 
 
 .1850 
 
 G. 
 
 118. 
 
 Black lead 
 
 .1830 
 
 , 
 
 119. 
 
 Sulphur - 
 
 .1830 
 
 K. 
 
 120. 
 
 Oxide of antimony, nearly 
 free of air 
 
 .1666 
 
 C. 
 
 121. 
 
 Rust of iron, ditto ditto 
 
 .1*666 
 
 — - 
 
 122. 
 
 Ashes of elm wood 
 
 .1402 
 
 — 
 
 123. 
 
 Iron (125.127,128.132) 
 
 .1450 
 
 Ir. 
 
 124. 
 
 Oxide of zinc, nearly freed 
 from air 
 
 .1369 
 
 C. 
 
 125. 
 
 White cast iron 
 
 .1320 
 
 G. 
 
 126. 
 
 White oxide of arsenic - 
 
 .1260 
 
 — ■ 
 
 127. 
 
 Iron (123.152) - 
 
 .1269 
 
 C. 
 
 128. 
 
 Iron, sp. gr. 7876 
 
 .1260 
 
 w. 
 
 129. 
 
 Cast iron abounding in 
 plumbago 
 
 .1240 
 
 G. 
 
 130. 
 
 Hardened steel 
 
 .1230 
 
 — 
 
 131. 
 
 Steel softened by fire - 
 
 .1200 
 
 — 
 
 132. 
 
 Soft bar iron, sp. gr. 7.724 .1 1 90 
 
 — 
 
 153. 
 
 Brass, sp. gr. 8.356 (135) 
 
 .1160 
 
 W. 
 
 134. 
 
 Copper, sp. gr. 8.785 (136) .1140 
 
 w. 
 
 135. 
 
 Brass (133) 
 
 .1123 
 
 c. 
 
 136. 
 
 Copper (133) 
 
 .1111 
 
 — 
 
 137. 
 
 Sheet iron 
 
 .1099 
 
 L. 
 
 138. 
 
 Zinc, sp. gr. 7.154 (143) 
 
 .1020 
 
 W. 
 
 139. 
 
 V r hite oxide of tin, nearly 
 free of air 
 
 .990 
 
 C. 
 
 140. 
 
 Cast pure copper, heated 
 between charcoal, and 
 cooled slowly, sp. grav. 
 7.907 
 
 .990 
 
 G. 
 
 141. Hammered copper, sp. gr. 
 
 9150 - - - .970 G. 
 
 142. Oxide of tin - - .960 K. 
 
 143. Zinc (198) - - .943 C. 
 
 144. Ashes of charcoal - - .909 — 
 
 145. Sublimated arsenic - .840 Go 
 
 146. Silver, sp. gr. 10.001 - .820 W. 
 
 147. Tin (152) - - .704 C. 
 
 148. Yellow oxide of lead - .680 — 
 
 149. White lead - - .670 G. 
 
 150. Antimony - .645 
 
 151. Antimony, sp. gr. 6.107 .630 W. 
 
 152. Tin, sp. gr. 7.380 (147) .600 — . 
 
 153. Red oxide of lead - .590 G. 
 
 154. Gold, sp. gr. 1 9.04 - .500 W. 
 
 155. Vitrified oxide of lead * .590 G„ 
 
 156. Bismuth, sp. gr. 9.861 - .430 W. 
 
 157. Lead, sp. gr. 11.45 - .420 
 
 158. - .352 C. 
 
 * The above capacities of the gases, are all erroneous ; and those of the other bcdies are 
 probably more or less incorrect. See Caloric. * 
 
^ !•“— Correspondence of the Thermometers of' Fahrenheit and Reaumur , and that of Celsius, 
 or the Centigrade 'Thermometer if the modern French Chemists. 
 
 Falir . 
 
 Reaum . 
 
 Celgi . 
 
 Fahr . ] 
 
 ieaum . 
 
 Cel * i . 
 
 Fahr . 
 
 Reaum . 
 
 Celsi . 
 
 Fahr . 
 
 Reaum . 
 
 Celii . 
 
 212 
 
 80 
 
 100 
 
 148 
 
 51.5 
 
 64.4 
 
 85 
 
 23.5 
 
 29.4 
 
 22 
 
 4.4 
 
 5.5 
 
 211 
 
 79.5 
 
 99.4 
 
 147 
 
 51.1 
 
 63.8 
 
 84 
 
 23.1 
 
 28.8 
 
 21 
 
 4.8 
 
 6.1 
 
 210 
 
 79.1 
 
 98.8 
 
 146 
 
 50.6 
 
 63.3 
 
 83 
 
 22.6 
 
 28.3 
 
 20 
 
 5.3 
 
 6.6 
 
 209 
 
 78.6 
 
 98.3 
 
 145 
 
 50.2 
 
 62.7 
 
 82 
 
 22.2 
 
 27.7 
 
 19 
 
 5.7 
 
 7.2 
 
 208 
 
 78.2 
 
 97.7 
 
 144 
 
 49.7 
 
 62.2 
 
 81 
 
 21.7 
 
 27.2 
 
 18 
 
 6.2 
 
 7.7 
 
 207 
 
 77.7 
 
 97.2 
 
 145 
 
 49.3 
 
 61.6 
 
 80 
 
 21.3 
 
 26.6 
 
 17 
 
 6.6 
 
 8.3 
 
 206 
 
 77.5 
 
 96.6 
 
 142 
 
 48.8 
 
 61.1 
 
 79 
 
 20.8 
 
 26.1 
 
 16 
 
 7.1 
 
 8.8 
 
 205 
 
 76.8 
 
 96.1 
 
 141 
 
 48.4 
 
 60.5 
 
 78 
 
 20.4 
 
 25.5 
 
 15 
 
 7.5 
 
 9.4 
 
 204 
 
 76.4 
 
 95.5 
 
 140 
 
 48 
 
 60 
 
 77 
 
 20 
 
 25 
 
 14 
 
 8 
 
 10 
 
 205 
 
 76 
 
 95 
 
 139 
 
 47.5 
 
 59.4 
 
 76 
 
 19.5 
 
 24.4 
 
 13 
 
 8.4 
 
 10.5 
 
 202 
 
 75.5 
 
 94.4 
 
 158 
 
 41.1 
 
 58.8 
 
 75 
 
 19.1 
 
 23.8 
 
 12 
 
 8.8 
 
 11.1 
 
 201 
 
 75.1 
 
 93.8 
 
 137 
 
 46.6 
 
 58.5 
 
 74 
 
 18.6 
 
 23.3 
 
 11 
 
 9.3 
 
 11.6 
 
 200 
 
 74.6 
 
 95.5 
 
 136 
 
 46.2 
 
 57.7 
 
 73 
 
 18.2 
 
 22/7 
 
 10 
 
 9.7 
 
 12.2 
 
 199 
 
 74.2 
 
 92.7 
 
 135 
 
 45.7 
 
 57.2 
 
 72 
 
 17.7 
 
 22. 2 
 
 9 
 
 10.2 
 
 12.7 
 
 198 
 
 73.7 
 
 92.2 
 
 134 
 
 45.3 
 
 5 6.6 
 
 71 
 
 17.3 
 
 21.6 
 
 8 
 
 10.6 
 
 13.3 
 
 197 
 
 73.3 
 
 91.6 
 
 133 
 
 44.8 
 
 56.1 
 
 70 
 
 16.8 
 
 21.1 
 
 7 
 
 11.1 
 
 13.8 
 
 196 
 
 72.8 
 
 91.1 
 
 132 
 
 44.4 
 
 55.5 
 
 69 
 
 16.4 
 
 20.5 
 
 6 
 
 1 1.5 
 
 14.4 
 
 195 
 
 72.4 
 
 90.5 
 
 131 
 
 44 
 
 55 
 
 68 
 
 16 
 
 20 
 
 5 
 
 12 
 
 15 
 
 194 
 
 72 
 
 90 
 
 ISO 
 
 43.5 
 
 54.4 
 
 67 
 
 15.5 
 
 19.4 
 
 4 
 
 12.4 
 
 15.5 
 
 193 
 
 71.5 
 
 89.4 
 
 129 
 
 43.1 
 
 53.8 
 
 66 
 
 15.1 
 
 18.8 
 
 3 
 
 12.8 
 
 16.1 
 
 192 
 
 71.1 
 
 88.8 
 
 128 
 
 42.6 
 
 55.3 
 
 65 
 
 14.6 
 
 18.3 
 
 2 
 
 13.3 
 
 16.6 
 
 191 
 
 70.6 
 
 88.3 
 
 127 
 
 42.2 
 
 52.7 
 
 64 
 
 14.2 
 
 17.7 
 
 1 
 
 13.7 
 
 17.2 
 
 190 
 
 70.2 
 
 87.7 
 
 126 
 
 41.7 
 
 52.2 
 
 63 
 
 13.7 
 
 17.2 
 
 0 
 
 14.2 
 
 17.7 
 
 189 
 
 69.7 
 
 87.2 
 
 125 
 
 41.3 
 
 51.6 
 
 62 
 
 13.3 
 
 16.6 
 
 1 
 
 14.6 
 
 18.3 
 
 188 
 
 69.3 
 
 S 6.6 
 
 124 
 
 40.8 
 
 51.1 
 
 61 
 
 12.8 
 
 16.1 
 
 2 
 
 15.1 
 
 18.8 
 
 187 
 
 68.8 
 
 86.1 
 
 123 
 
 40.4 
 
 50.5 
 
 60 
 
 12.4 
 
 15.5 
 
 3 
 
 15.5 
 
 19.4 
 
 186 
 
 68.4 
 
 85.5 
 
 122 
 
 40 
 
 50 
 
 59 
 
 12 
 
 15 
 
 4 
 
 16 
 
 20 
 
 185 
 
 68 
 
 85 
 
 121 
 
 39.5 
 
 49.4 
 
 58 
 
 11.5 
 
 14.4 
 
 5 
 
 16.4 
 
 20.5 
 
 184 
 
 67.5 
 
 84.4 
 
 120 
 
 39.1 
 
 48.8 
 
 57 
 
 11.1 
 
 13.8 
 
 6 
 
 16.8 
 
 21.1 
 
 183 
 
 67.1 
 
 85.8 
 
 119 
 
 38.6 
 
 48.3 
 
 56 
 
 10.6 
 
 13.3 
 
 7 
 
 17.3 
 
 21.6 
 
 182 
 
 66.6 
 
 83.5 
 
 118 
 
 38.2 
 
 47.7 
 
 55 
 
 10.2 
 
 12.7 
 
 8 
 
 17.7 
 
 22.2 
 
 181 
 
 66.2 
 
 82.7 
 
 117 
 
 37.7 
 
 47.2 
 
 54 
 
 9.7 
 
 12.2 
 
 9 
 
 18.2 
 
 22.7 
 
 180 
 
 65.7 
 
 82.2 
 
 116 
 
 37.3 
 
 46.6 
 
 53 
 
 9.3 
 
 11.6 
 
 10 
 
 18.6 
 
 23.3 
 
 179 
 
 65.3 
 
 81.6 
 
 115 
 
 36.8 
 
 46.1 
 
 52 
 
 8.8 
 
 11.1 
 
 11 
 
 19.1 
 
 25.8 
 
 178 
 
 64.8 
 
 81.1 
 
 114 
 
 86.4 
 
 45.5 
 
 51 
 
 8.4 
 
 10.5 
 
 12 
 
 19.5 
 
 24.4 
 
 177 
 
 64.4 
 
 80.5 
 
 1 13 
 
 36 
 
 45 
 
 50 
 
 8 
 
 10 
 
 13 
 
 20 
 
 25 
 
 176 
 
 64 
 
 80 
 
 112 
 
 35.5 
 
 44.4 
 
 49 
 
 7.5 
 
 9.4 
 
 14 
 
 20.4 
 
 25.5 
 
 175 
 
 63.5 
 
 79.4 
 
 111 
 
 35.1 
 
 45.8 
 
 48 
 
 7.1 
 
 8.8 
 
 15 
 
 20.8 
 
 26.1 
 
 174 
 
 65.1 
 
 78.8 
 
 110 
 
 34.6 
 
 43.3 
 
 47 
 
 6.6 
 
 8.3 
 
 16 
 
 21.3 
 
 26.6 
 
 173 
 
 62.6 
 
 78.3 
 
 109 
 
 34.2 
 
 42.7 
 
 46 
 
 6.2 
 
 7.7 
 
 17 
 
 21.7 
 
 27.2 
 
 172 
 
 62.2 
 
 77.7 
 
 108 
 
 33.7 
 
 42.2 
 
 45 
 
 5.7 
 
 7.2 
 
 18 
 
 22.2 
 
 27.7 
 
 171 
 
 61.7 
 
 77.2 
 
 107 
 
 33.3 
 
 41.6 
 
 44 
 
 5.3 
 
 6.6 
 
 19 
 
 22.6 
 
 28.3 
 
 170 
 
 61.3 
 
 76.6 
 
 106 
 
 32.8 
 
 41.1 
 
 43 
 
 4.8 
 
 6.1 
 
 20 
 
 23.1 
 
 28.8 
 
 169 
 
 60.8 
 
 76.1 
 
 105 
 
 32.4 
 
 40.5 
 
 42 
 
 4.4 
 
 5.5 
 
 21 
 
 23.5 
 
 29.4 
 
 168 
 
 60.4 
 
 75.5 
 
 104 
 
 52 
 
 40 
 
 41 
 
 4 
 
 5 
 
 22 
 
 24 
 
 30 
 
 167 
 
 60 
 
 75 
 
 103 
 
 31.5 
 
 39.4 
 
 40 
 
 3.5 
 
 4.4 
 
 23 
 
 24.4 
 
 30.5 
 
 166 
 
 59.5 
 
 74.4 
 
 102 
 
 31.1 
 
 38.8 
 
 39 
 
 8.1 
 
 3.8 
 
 24 
 
 24.8 
 
 31.1 
 
 165 
 
 59.1 
 
 73.8 
 
 101 
 
 30.6 
 
 38.3 
 
 38 
 
 2.6 
 
 3.3 
 
 25 
 
 25.3 
 
 51.6 
 
 164 
 
 58.6 
 
 73.3 
 
 100 
 
 30.2 
 
 37.7 
 
 37 
 
 2.2 
 
 2.7 
 
 26 
 
 25.7 
 
 32.2 
 
 163 
 
 58.2 
 
 72.7 
 
 99 
 
 29.7 
 
 37.2 
 
 36 
 
 1.7 
 
 2.2 
 
 27 
 
 26.2 
 
 32.7 
 
 162 
 
 57.7 
 
 72.2 
 
 98 
 
 29.3 
 
 36.6 
 
 35 
 
 1.3 
 
 1.6 
 
 28 
 
 26.6 
 
 33. S 
 
 161 
 
 57.5 
 
 71.6 
 
 97 
 
 28.8 
 
 36.1 
 
 34 
 
 0.8 
 
 1.1 
 
 29 
 
 27.1 
 
 33.8 
 
 160 
 
 56.8 
 
 71.1 
 
 96 
 
 28.4 
 
 35.5 
 
 33 
 
 0.4 
 
 0.5 
 
 30 
 
 27.5 
 
 34.4 
 
 159 
 
 56.4 
 
 70.3 
 
 95 
 
 28.0 
 
 35 
 
 32 
 
 0 
 
 0 
 
 31 
 
 28 
 
 35 
 
 158 
 
 56 
 
 70 
 
 94 
 
 27.5 
 
 34.4 
 
 31 
 
 0.4 
 
 0.5 
 
 32 
 
 28.4 
 
 35.5 
 
 157 
 
 55.5 
 
 69.4 
 
 93 
 
 27.1 
 
 '33.8 
 
 30 
 
 0.8 
 
 1. 1 
 
 33 
 
 2 S .8 
 
 36.1 
 
 156 
 
 55.1 
 
 68.8 
 
 92 
 
 26.6 
 
 33.3 
 
 29 
 
 1.3 
 
 1.6 
 
 34 
 
 29.3 
 
 36.6 
 
 155 
 
 54.6 
 
 68.3 
 
 91 
 
 26.2 
 
 32.7 
 
 28 
 
 1.7 
 
 2.2 
 
 35 
 
 29.7 
 
 37.2 
 
 154 
 
 54.2 
 
 67.7 
 
 90 
 
 25.7 
 
 32.2 
 
 27 
 
 2.2 
 
 2.7 
 
 36 
 
 30.2 
 
 37 . 7 
 
 155 
 
 53.7 
 
 67.2 
 
 89 
 
 25.3 
 
 31.6 
 
 26 
 
 2.6 
 
 3.3 
 
 37 
 
 30.6 
 
 38.3 
 
 152 
 
 53.5 
 
 66.6 
 
 88 
 
 24.8 
 
 31.1 
 
 25 
 
 3.1 
 
 3.8 
 
 00 
 
 00 
 
 31.1 
 
 SS .8 
 
 151 
 
 52.8 
 
 66. 1 
 
 87 
 
 24.4 
 
 30.5 
 
 24 
 
 3.5 
 
 4.4 
 
 39 
 
 31.5 
 
 39.4 
 
 150 
 
 119 
 
 52.4 
 | 52 
 
 65.5 
 
 6.5 
 
 86 
 
 24 
 
 30 
 
 23 
 
 4 
 
 5 
 
 40 
 
 32 
 
 40 
 
* TABLE VII. — Of the Elastic Force of the Vapour of IVater in inches of Mercury , 
 
 by Dr Ure. 
 
 Temp. 
 
 Force. 
 
 Temp. 
 
 Force. 
 
 Temp. 
 
 Force. 
 
 Temp. 
 
 Force. 
 
 Temp. 
 
 Force. 
 
 Temp. 
 
 Force. 
 
 24° 
 
 0.170 
 
 115° 
 
 2.820 
 
 195° 
 
 21.1 ooj 
 
 242° 
 
 53.600 
 
 270° 
 
 86.300 
 
 2 95.6° 
 
 130.400 
 
 32 
 
 0.200 
 
 120 
 
 3.300 
 
 200 
 
 23.600j 
 
 245 
 
 56.340 
 
 271.2 
 
 88.000 
 
 295 
 
 129.000 
 
 40 
 
 0.250 
 
 125 
 
 3.830 
 
 205 
 
 25.900 
 
 245.8 
 
 57.100 
 
 273.7 
 
 91.200 
 
 297.1 
 
 133.900 
 
 50 
 
 0.560 
 
 130 
 
 4.366 
 
 210 
 
 28.880 
 
 248.5 
 
 60.400 
 
 275 
 
 93.480 
 
 298.8 
 
 137.400 
 
 55 
 
 0.41 6 
 
 135 
 
 5.070 
 
 212 
 
 30.000 
 
 250 
 
 61.900 
 
 275.7 
 
 94. 600 
 
 300 
 
 139.700 
 
 60 
 
 0.516 
 
 140 
 
 5.770 
 
 216.6 
 
 33.400 
 
 251.6 
 
 63.500 
 
 277.9 
 
 97.800 
 
 300.6 
 
 140. 900 
 
 65 
 
 0.630 
 
 145 
 
 6.600 
 
 220 
 
 35.540 
 
 254.5 
 
 66.700 
 
 279.5 
 
 101.600 
 
 302 
 
 144.300 
 
 70 
 
 0.72 6 
 
 150 
 
 7.530 
 
 221.6 
 
 36.700 
 
 255 
 
 67.250 
 
 280 
 
 101.900 
 
 303.8 
 
 147.700 
 
 75 
 
 0.860 
 
 155 
 
 8.500 
 
 225 
 
 39.110 
 
 257.5 
 
 69.800 
 
 281.8 
 
 104.400 
 
 305 
 
 150.560 
 
 80 
 
 1.010 
 
 160 
 
 9.600 
 
 226.3 
 
 40.1 00| 
 
 260 
 
 72.300 
 
 283.8 
 
 107.700 
 
 306.8 
 
 154.400 
 
 85 
 
 1.170 
 
 165 
 
 10.800 
 
 230 
 
 43.100 
 
 260.4 
 
 72.800 
 
 285.2 
 
 1 1 2. 200 
 
 308 
 
 157.700 
 
 90 
 
 1.360 
 
 170 
 
 1 2.050 
 
 230.5 
 
 43.500 
 
 262.8 
 
 75.900 
 
 287.2 
 
 1 1 4. 800 
 
 310 
 
 161.300 
 
 95 
 
 1.640 
 
 175 
 
 13.550 
 
 234.5 
 
 46.800 
 
 264.9 
 
 77.900 
 
 289 
 
 1 1 8. 200 
 
 311.4 
 
 164.800 
 
 100 
 
 1.860 
 
 180 
 
 15.160 
 
 235 
 
 47.220 
 
 265 
 
 78.040 
 
 290 
 
 120.150 
 
 312 
 
 167.000 
 
 105 
 
 2.100 
 
 185 
 
 16,900 
 
 238.5 
 
 50.300 
 
 267 
 
 81.900 
 
 292.5 
 
 123.100 
 
 Another experim. 
 
 110 
 
 2.456 
 
 190 
 
 19.000 
 
 240 
 
 51.700j 
 
 269 
 
 84.900 
 
 294 
 
 126.700 
 
 312° j 
 
 165.5 
 
 TABLE VIII. — Of the Elastic Forces of the Vapours of Alcohol , Ether , Oil of Turpentine, 
 
 and Petroleum , or Naphtha, by Dr Ure. 
 
 Ether. 
 
 Alcoh. sp. gr. 0.813. 
 
 Alcoh. sp. gr. 0.813. 
 
 Petroleum. 
 
 Temp. 
 
 Force of 
 Vapour. 
 
 Temp. 
 
 Force of 
 Vapour. 
 
 Temp. 
 
 Force of 
 Vapour. 
 
 Temp. 
 
 Force of 
 Vapour. 
 
 34° 
 
 6.20 
 
 32° 
 
 0.40 
 
 193.3° 
 
 46.60 
 
 316° 
 
 30.00 
 
 44 
 
 8.10 
 
 40 
 
 0.56 
 
 196.3 
 
 50.10 
 
 320 
 
 31.70 
 
 54 
 
 10.50 
 
 45 
 
 0.70 
 
 200 
 
 53.00 
 
 325 
 
 34.00 
 
 64 
 
 13.00 
 
 50 
 
 0.86 
 
 206 
 
 60.10 
 
 330 
 
 36.40 
 
 74 
 
 16.10 
 
 55 
 
 1.00 
 
 210 
 
 65.00 
 
 335 
 
 38.90 
 
 84 
 
 20,00 
 
 60 
 
 1.23 
 
 214 
 
 69.30 
 
 340 
 
 41.60 
 
 94 
 
 24,70 
 
 65 
 
 1.49 
 
 216 
 
 72.20 
 
 345 
 
 44.10 
 
 104 
 
 30.00 
 
 70 
 
 1.76 
 
 220 
 
 78.50 
 
 350 
 
 46.86 
 
 
 
 75 
 
 2.10 
 
 22 5 
 
 87.50 
 
 855 
 
 50.20 
 
 2d. 
 
 Ether. 
 
 80 
 
 2.45 
 
 230 
 
 94.10 
 
 360 
 
 53.50 
 
 
 
 85 
 
 2.93 
 
 232 
 
 97.10 
 
 365 
 
 56.90 
 
 105° 
 
 30.00 
 
 90 
 
 3.40 
 
 2 36 
 
 103.60 
 
 370 
 
 60. 70 
 
 110 
 
 32.54 
 
 95 
 
 3.90 
 
 238 
 
 106.90 
 
 372 
 
 61.90 
 
 115 
 
 35.90 
 
 100 
 
 4.50 
 
 240 
 
 111.24 
 
 375 
 
 64.00 
 
 120 
 
 39.47 
 
 105 
 
 5.20 
 
 244 
 
 118.20 
 
 
 
 125 
 
 43.24 
 
 110 
 
 6.00 
 
 247 
 
 122.10 
 
 
 
 130 
 
 47.14 
 
 115 
 
 7.10 
 
 248 
 
 126.10 
 
 Oil of Turpen, 
 
 135 
 
 51.90 
 
 120 
 
 8.10 
 
 249.7 
 
 131.40 
 
 
 
 140 
 
 56.90 
 
 125 
 
 9.25 
 
 250 
 
 1 32.30 
 
 
 
 145 
 
 62.10 
 
 130 
 
 10.60 
 
 252 
 
 138.60 
 
 Temp. 
 
 rorce oi 
 Vapour. 
 
 150 
 
 67.60 
 
 135 
 
 12.15 
 
 254.3 
 
 143.70 
 
 304° 
 
 30.00 
 
 155 
 
 73.60 
 
 140 
 
 1 3.90 
 
 258.6 
 
 151.60 
 
 307.6 
 
 32.60 
 
 160 
 
 80.30 
 
 145 
 
 15.95 
 
 260 
 
 155.20 
 
 310 
 
 33.50 
 
 165 
 
 86.40 
 
 150 
 
 18.00 
 
 262 
 
 161.40 
 
 315 
 
 35. 20 
 
 170 
 
 92.80 
 
 155 
 
 20.30 
 
 264 
 
 166.10 
 
 320 
 
 37.06 
 
 175 
 
 99.10 
 
 160 
 
 22.60 
 
 
 
 322 
 
 37.80 
 
 180 
 
 108.30 
 
 165 
 
 25.40 
 
 
 
 326 
 
 40.20 
 
 185 
 
 116.10 
 
 170 
 
 28.30 
 
 
 
 330 
 
 42.10 
 
 190 
 
 124.80 
 
 173 
 
 30.00 
 
 
 
 336 
 
 45.00 
 
 195 
 
 133.70 
 
 178.3 
 
 33.50 
 
 
 
 540 
 
 47. SO 
 
 200 
 
 142.80 
 
 180 
 
 34.73 
 
 
 
 343 
 
 49.40 
 
 205 
 
 151.30 
 
 182.3 
 
 36.40 
 
 
 
 347 
 
 51.70 
 
 210 
 
 166.00 
 
 1 85.3 
 
 S9.90 
 
 
 
 350 
 
 53.80 
 
 
 
 190 
 
 43.20 
 
 
 
 554 
 
 56.60 
 
 
 
 
 
 
 
 557 
 
 58.70 
 
 
 
 
 
 
 
 360 
 
 60.80 
 
 
 
 
 
 
 
 362 
 
 62.40 
 
" TABLE IX ”“ ‘New French Weights and Measures (calculated by Dr Duncan, jun.) 
 
 1. Measures of Length : the Metre being at 32°, and the Foot at 62°. 
 
 Millimetre 
 
 Centimetre 
 
 Decimetre 
 
 Metre* 
 
 Decametre 
 
 Ilecatometre 
 
 Kilometre 
 
 Myriometre 
 
 English inches. 
 «= .03937 
 
 =* .39371 
 
 = S.93710 
 
 = 39.37100 
 
 = 393.71000 
 
 = 3937.10000 
 
 = 39371.00000 
 
 = 393710.00000 
 
 Mil. 
 
 Fur. 
 
 Yds. 
 
 Feet. In. 
 
 0 
 
 0 
 
 10 
 
 2 
 
 9.7 
 
 0 
 
 0 
 
 109 
 
 1 
 
 1 
 
 0 
 
 4 
 
 213 
 
 1 
 
 10.2 
 
 6 
 
 1 
 
 156 
 
 0 
 
 6 
 
 Millilitre 
 
 Centilitre 
 
 Decilitre 
 
 Litre 
 
 Decalitre 
 
 Ilecatolitre 
 
 Kilolitre 
 
 Myriolitre 
 
 2 . — Measures of Capacity. 
 
 Cubic inches. 
 — .06103 
 
 = .61028 
 = 6.10280 
 = 61.02800 
 = 610.28000 
 = 6102.80000 
 = 61028.00000 
 = 610280.00000 
 
 English. 
 
 Tons. Hhds. Wine. G. Tints. 
 = 00 O. 2.11 S3 
 
 = 0 0 2. 5.1352 
 
 = 0 0 26.419 
 
 = 1 0 12.19 
 
 = 10 1 58.9 
 
 3 Measures of Weight. 
 
 English Grains. 
 
 .0154 
 
 Milligramme = 
 Centigramme = 
 Decigramme *= 
 Gramme = 
 Decagramme =» 
 Hecatogramme = 
 Kilogramme = 
 Myriogramme = 
 
 .1544 
 1.5444 
 15.4440 
 154.4402 == 
 
 1544.4023 = 
 
 15444.0234 = 
 
 154440.2344 = 
 
 Avoirdupois. 
 Toun. Oun. Dram. 
 0 O 5.65 
 0 3 8.5 
 
 2 3 5 
 
 22 1 2 
 
 * TABLE X . — Correspondence of English Weights and Measures ivith those used in 
 
 France before the Revolution. 
 
 § 1 . — Weights. 
 
 The Paris pound, poids de marc of Charlemagne, contains 9216 Paris grains; it is divid- 
 ed into 16 ounces, each ounce into 8 gros, and each gros into 72 grains. It is equal to 
 7561 English troy grains. 
 
 The English troy pound of 12 ounces contains 5760 English troy grains, and is equal to 
 7021 Paris grains. 
 
 The English avoirdupois pound of 16 ounces contains 7000 English troy grains, and is 
 equal to 8532.5 Paris grains. 
 
 To reduce Paris grains to English troy grains, divide by 
 To reduce English troy grains to Paris grains, multiply by 
 To reduce Paris ounces to English troy, divide by ^ 1 01 57S4 
 
 To reduce English troy ounces to Paris, multiply by S ‘ ‘ 
 
 | 1.2189 
 
 § 2 . — Long and Cubical Measures. 
 
 To reduce Paris running feet, or inches, into English, multiply by 
 English running feet, or inches, into Paris, divide liy 
 To reduce Paris cubic feet, or inches, to English, multiply by 
 English cubic feet, or inches, to Paris, divide by - 
 
 1.065977 
 
 1.211278 
 
 * Recently determined by Captain Rater to be 39.37079 inches. (Phil. Trans. 1818, p. 109 
 
* TABLE XI.— Correspondence between English and other Foreign Weights and Measures. 
 
 I . — English Weights and Measures. 
 
 Found. Ounces. 
 1 = 12 = 
 
 1 = 
 
 Troy Weight. 
 
 Drms. 
 
 . Scruples. 
 
 Grains. 
 
 Grammes. 
 
 : 96 
 
 = 288 = 
 
 5760 = 
 
 372.96 
 
 : 8 
 
 = 24 = 
 
 480 = 
 
 31.08 
 
 1 
 
 3= 3 = 
 
 60 = 
 
 3.885 
 
 
 1 = 
 
 20 =±= 
 
 1.295 
 
 
 
 1 = 
 
 0.06475 
 
 Avoirdupois Weight. 
 
 Found. Ounces. Drms. Grains. Grammes. 
 
 1 = 16 = 256 = 7000. = 453.25 
 
 1 1 6 = 437 .5 = 28.328 
 
 1 = 27.34375 = 1.7705 
 
 Measures. 
 
 Gal. Tints. Ounces. Drms. Cubic. Inch. Litres. 
 
 1 — 8 — 128 — 1024 — 231. == 3.78515 
 
 1 = 16 = 128 = 28.875 = 0.47398 
 
 1 — 8 = 1.8047 = 0.02957 
 
 1 = 0.2256 = 0.00396 
 
 N. B. The English ale-gallon contains 282 cubical inches. 
 
 The wine gallon contains 58176 Troy grains; and the wine pint 7272 Troy grains. 
 
 II. — German . 
 
 71 lbs. or grs. English troy . = 74 lbs. or grs. German apothecaries’ weight. 
 
 1 oz. Nuremberg, medic, weight = 7 dr. 2 sc. 9 gr. English. 
 
 1 mark Cologne .... = 7 oz. 2 dwt. 4 gr. English troy. 
 
 III. — Dutch « 
 
 1 lbs. Dutch = 1 lb. 3 oz. 16 dwt. 7 gr. English troy. 
 
 787-J lbs. Dutch — 1038 lbs. English troy. 
 
 IV . — Swedish Weights and Measures, used by Bergman and Scheele. 
 
 The Swedish pound, which is divided like the English apothecary or troy pound, weighs 
 •6556 grs. troy. 
 
 The kanne of pure water, according to Bergman, weighs 42250 Swedish grains, and oc- 
 cupies 100 Swedish cubical inches. Hence the kanne of pure water weighs 48088.719444 
 English troy grains, or is equal to 189.9413 English cubic inches ; and the Swedish longi- 
 tudinal inch is equal to 1.238455 English longitudinal inches. 
 
 By Everard’s experiment, and the proportions of the English and French foot, as esta- 
 blished by the Royal Society and French Academy of Sciences, the following numbers 
 are ascertained : 
 
 Paris grains in a Paris cube foot of water at 55° F. = 64551 1 
 
 English grains in a Paris cube foot of water . . = 529922 
 
 Paris grains in an English cube foot of water . = 533247 
 
 English grains in an English cube foot of water = 437489.4 
 English grains in an English cube inch of water =z 253. 1 75 
 
 As a cubic foot of water weighs very nearly 1000 ounces avoirdupois, the specific gra- 
 vities of bodies, express the ounces in a cubic foot of them, the density of water being 
 called 1000. 
 
TABLE XII. Of the Solubility of some Solid) in Hater. 
 
 names of salts. 
 
 Acids. 
 
 Arsenic 
 
 Benzoic 
 
 Boracic 
 
 Camphoric 
 
 Citric 
 
 Gallic 
 
 Mucic 
 
 Molybdenic 
 
 Oxalic 
 
 Suberic 
 
 Succinic 
 
 Tartaric 
 
 Solubility in 100 Tarts Water. 
 
 At 60 ° 
 
 At 212° 
 
 150 . 
 
 0.208 
 
 1.04 
 1 33 . 
 
 8.3 
 
 0.84 
 
 4.17 
 
 2 . 
 
 8.3 
 
 200 . 
 66 . 
 1.2 5 
 
 50 . 
 
 0.69 
 
 4 . 
 
 Very soluble 
 
 0.1 
 
 100 . 
 
 50 . 
 
 50 . 
 
 Salifiable Bases. 
 
 
 
 Barytes 
 
 5 . 
 
 50 . 
 
 Unlimited 
 
 crystallized 
 Lime - 
 
 57 . 
 
 0.2 
 
 Potash - _ 
 
 Soda - 
 
 Very soluble 
 do. 
 
 
 Strontites ... 
 
 0.6 
 
 
 crystallized 
 
 1.9 
 
 50 . 
 
 Salts. 
 
 
 
 Acetate of ammonia 
 
 Very soluble 
 
 
 barytes 
 
 do. 
 
 
 lime 
 
 do. 
 
 
 1 magnesia 
 
 do. 
 
 
 potash 
 
 100 . 
 
 
 soda ... 
 
 Very soluble 
 
 
 strontites 
 
 40 . 
 
 Carbonate of ammonia 
 
 4 - 30 . 
 
 100 . 
 
 I barytes 
 
 Insoluble 
 
 
 lime 
 
 do. 
 
 
 magnesia 
 
 Q 
 
 
 potash 
 
 25 . 
 
 83 . 
 
 soda 
 
 50 . 
 
 4 - 100 . 
 
 strontites 
 
 Insoluble 
 
 
 jCamphorate of ammonia 
 
 1 . 
 
 33 . 
 
 barytes 
 
 0.16 
 
 
 lime 
 
 0.5 
 
 
 potash 
 
 33 . 
 
 4 - 53 . 
 
 Citrate of soda 
 
 60 . 
 
 
 lime 
 
 Insoluble 
 
 
 Chlorate of barytes 
 
 25 . 
 
 4 - 25 . 
 
 mercury 
 
 25 . 
 
 
 potash 
 
 6 . 
 
 40 . 
 
 soda 
 
 35. 
 
 4 - 55 . 
 
 Muriate of ammonia 
 
 33. 
 
 100 . 
 
 barytes 
 
 20 . 
 
 4 - 20 . 
 
 lead 
 
 4.5 
 
 
 lime 
 
 200 . 
 
 
 magnesia 
 
 100 . 
 
 
 mercury 
 
 5 . 
 
 50 . 
 
 potash 
 
 53. 
 
 
 silver 
 
 
 
4 
 
 NAMES OF SALTS. 
 
 Muriate of soda 
 
 strontites 
 Nitrate of ammonia 
 barytes 
 lime 
 
 magnesia 
 potash 
 soda 
 
 strontites 
 Oxalate of strontites 
 
 Phosphate of ammonia 
 barytes 
 lime 
 
 magnesia 
 Phosphate of potash 
 soda 
 
 strontites 
 Phosphite of ammonia 
 barytes 
 potash 
 Sulphate of ammonia 
 barytes 
 copper 
 iron 
 lead 
 lime 
 
 magnesia 
 
 potash 
 
 soda 
 
 strontites 
 Sulphite of ammonia 
 lime 
 
 magnesia 
 
 potash 
 
 soda 
 
 Saccholactate of potash 
 soda 
 
 Sub-borate of soda (borax) 
 
 Super- sulphate of alumina and pol 
 
 potash 
 
 Super-oxalate of potash 
 tartrate of potash 
 Tartrate of potash 
 
 and soda 
 
 antimony and potash 
 
 Solubility in 100 Parts Water. 
 
 At 60° 
 
 At 212° 
 
 .35.42 
 
 36.16 
 
 150. 
 
 Unlimited 
 
 50. 
 
 200. 
 
 8. 
 
 25. 
 
 400. 
 
 
 100. 
 
 + 100. 
 
 14.25 
 
 100. 
 
 33. 
 
 f 100. 
 
 100. 
 
 200. 
 
 °*tV 
 
 
 25. 
 
 + 25. 
 
 0. 
 
 0. 
 
 0. 
 
 0. 
 
 6.6 
 
 
 Very soluble 
 
 
 25. 
 
 50. 
 
 0. 
 
 0. 
 
 50. 
 
 + 50. 
 
 0-i 
 
 
 33. 
 
 + 33. 
 
 50. 
 
 100. 
 
 0.002 
 
 
 25. 
 
 50. 
 
 50. 
 
 + 100. 
 
 °'T2 
 
 . 
 
 0.2 
 
 0.22 
 
 100. 
 
 133. 
 
 6.25 
 
 20. 
 
 37. 
 
 125. 
 
 0. 
 
 0.02 
 
 100. 
 
 
 0.125 
 
 
 5. 
 
 
 100. 
 
 
 25. 
 
 100. 
 
 
 12. 
 
 
 20. 
 
 8.4 
 
 16.8 
 
 ) 5. 
 
 133. 
 
 50. 
 
 + 100. 
 
 
 10. 
 
 i.i 
 
 3 i 
 
 25. 
 
 ' 
 
 20. 
 
 
 6.6 
 
 S3. 
 
 See Salt. 
 
 \ 
 
 THE END. 
 
 Printed by Walker and Greig, 
 Edinburgh. 
 
 I 
 

 
ADDITIONS AND CORRECTIONS. 
 
 
 Acid (Aksenious). Column 4th, read 
 et soluble in an excess of the arsenious solu- 
 tion.” 
 
 Acid (Chlorocyanic or Chlorofrussic). 
 Column 2d, line 25d, dele “ aqueous.” Co- 
 lumn 3d, line 17th, read “ water, or receiv- 
 ed over mercury.” 
 
 Alcohol. M. Gay Lussac having shewn 
 that this liquid is a compound of olefiant gas 
 and water, potassium ought to disengage from 
 it, hydrogen and olefiant gas. In the abso- 
 lute alcohol of Richter there is no water, 
 independent of that which is essential to its 
 constitution. See Fermentation. 
 
 Atropia. A new vegetable alkali, ex- 
 tracted by Dr Brandes from the Atropa bel- 
 ladonna, or deadly nightshade. It is white, 
 brilliant, crystallizes in long needles, is taste- 
 less, and little soluble in water or alcohol. 
 It resists a moderate heat. With acids, it 
 forms regular salts, and is capable of neu- 
 tralizing a considerable proportion of acid. 
 Sulphate of atropia is composed of, 
 
 Sulphuric acid, 36.5 2 5.00 
 
 Atropia, 38.93 5 . 33 
 
 Water, 24.55 
 
 100.00 
 
 Bleaching. In the process given under 
 inverted commas, near the end of the article, 
 the writer omitted to state the proportion of 
 water, which is 360 gallons; and in describ- 
 ing the use of lime as a detergent, the addi- * 
 tion of soap is a mistake ; as I observed im- 
 mediately after it was printed. Soap and 
 lime are incompatible detergents. 
 
 Calcium. Column 3d, line 3d, read 
 “ sulphur and lime in water.” Column 
 4th, line 10th, read “ bleaching power.” 
 
 Calculus. Column 3d, line 1st, read 
 “ examine calculi.” 
 
 Caloric. Line 8th, read “ modify.” 
 Column 2d, line 19th, read “ it is extruded.” 
 Column 7th, line 31st, read “ mercurial and 
 air thermometer.” Column 20th from the 
 end, line 34th, read “give birth to a liquid.” 
 
 Coal-gas. 1st table, column 8th, read 
 “ Consume oxygen.” 2d last column, line 
 17th from bottom, read “ and the best as five 
 
 to six. If we therefore multiply this ratio, 
 into the double product of gas, obtained in 
 the Glasgow gas- work,” Sec. A linehasbeers 
 accidentally transposed here by the printer. 
 
 Combustion. Colume 2d, line 25th from 
 bottom, read “ either combination or decom- 
 position.” Column 3d, line 5th, read “ its 
 volume becomes.” Column 17th, line 8th 
 from bottom, read “ oxygen and hydrogen.” 
 
 Congelation. Column 2d, line 23d, for 
 “ to,” read “ till.” 
 
 Distillation. Column 2d, line 16th, 
 for “ is,” read are.” 
 
 Egeran. A sub-species of pyramidal gar- 
 net. Colour, reddish-brown. Massive, some- 
 times crystallized in rectangular four- sided 
 prisms, with cylindrical convex lateral planes. 
 The prisms are long, and deeply longitudin- 
 ally streaked. Shining, vitreous. Cleavage, 
 twofold. Fracture, uneven. Feebly trans- 
 lucent on the edges. Scratches felspar. 
 Brittle. Sp. gr. 3.294. It melts into a 
 black scoria. It occurs in a bed of felspar 
 and hornblende, at Haslau, near Eger in 
 Bohemia. 
 
 Ether (Muriatic). According to MM. 
 Colin and Robiquet, ( Annales de Cliimie et 
 de Physique, i. p. 348.) one volume of mu- 
 riatic ether passed through a porcelain tube 
 at a dull red-heat, is resolved into a mixture 
 of one volume olefiant gas, and one volume 
 muriatic acid gas. By adding the density 
 of olefiant gas = 0.9722 to that of 
 muriatic acid gas = 1.2840 
 
 We have the sum = 2.3562, which is 
 nearly the sp. gr. of the vapbur by experi- 
 ment = 2.2190. 
 
 Gas. Column 5th, line 13th, read “ spe- 
 cific gravity.” Column 20th, line 1 1th, read 
 “ s — r.” Column 23d, line 7th, read “ = 
 0.327.” Column 24th, last line but one, read 
 “ its bulk as at.” 
 
 Grenatite, or prismatic garnet. See 
 Staurotide. 
 
 Helvine. A sub-species of dodecahedral 
 garnet. Colour, wax-yellow. Dissemin- 
 ated, in small granular concretions, and 
 crystallized in small tetrahedrons. Glim- 
 
ORE 
 
 THE 
 
 mering, or shining. Fracture, small grain- 
 ed uneven. Crystals, strongly translucent. 
 Softer than quartz, but harder than felspar. 
 Brittle. Sp. gr. 3.2 to 3.S. It melts easily 
 into a blackish-brown glass. It occurs along 
 with slate-spar, brown blende, and fluor 
 spar, in beds subordinate to gneiss, near 
 Scliwartzenberg in Saxony. 
 
 Hyosciama. A new vegetable alkali, 
 extracted by Dr Brandes from the hyoscia- 
 mus nigra, or henbane. It crystallizes in 
 long prisms, and when neutralized by sul- 
 phuric acid, or nitric acid, forms characteris- 
 tic salts. — The examination of the alkaline 
 constituents of narcotic plants demands great 
 circumspection, because in them the whole 
 poisonous properties of the plant are concen- 
 trated. The vapour is particularly prejudi- 
 cial to the eyes. The smallest morsel put 
 upon the tongue, is very dangerous. 
 
 Ore of Silver, (omitted). Antimonial 
 
 silver. Colour, between silver-white and 
 tin-white. Massive, disseminated, in dis- 
 tinct concretions, and crystallized ; in a rec- 
 tangular four-sided prism, in a unequiangu- 
 lar six-sided prism, and a double six-sided 
 pyramid, truncated on the apices. Surface 
 of the prisms, longitudinally streaked. Splen- 
 dent, metallic. Cleavage, octohedral. Hard- 
 ness, between calc and fluor spar. Sp. gr. 
 9.4 to 10. The antimony is volatilized be- 
 fore the blow-pipe, and silver remains on the 
 charcoal. Its constituents are, silver 78, an- 
 timony 22. — Vauquelin. It occurs in veins 
 in granite, and greywacke. In the first, at 
 Altwoifach in Suabia ; in clay-slate in the 
 Hartz. 
 
 Salt. Column 2d, line 1 8th from bottom, 
 read “ chlorate of potash.” 
 
 Thermometer. The plan of graduation 
 is not borrowed from M. Gay Lussac ; though 
 it resembles his in some respects. 
 

I 
 

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 T.thh 1. 
 
 or t/h ( llfirilftlTS/i’ be made use cl' m 
 
 Chemistry,, 
 
 ByUcM 
 
 !" J/afUtuhiU tuul. Uht . 
 
 1 * fru > 5 
 H S ! $ * 
 
 hil-si 
 
 tcIM 
 
 ■sS H t* 
 4 5 
 
 s 
 
 1 
 
 Lip hi 
 Caloric 
 
 — 
 
 Ofaqai 
 
 •irt* 
 
 / 
 
 
 
 \ 
 
 Nitreoen 
 
 
 
 
 1 •? •< > 5 f ■ S- 
 
 
 such new uiu/ 
 
 *!|VS{ 
 
 
 > simple Substances 
 its tuny be 
 
 Ctrl's- 
 
 V"x 
 
 > /is covered . 
 
 M-a/i/ «vuiJ*v.l .is) 
 
 Tbtask 
 
 simple Substances. | 
 
 Soda 
 
 
 V 
 
 Jiarvtcs 
 
 | 
 
 V 
 
 Lime 
 
 / 
 
 S ^ 
 
 ,v 
 
 /Jaanesut 
 
 1 
 
 V 
 
 . Uuminc 
 
 
 V 
 
 Si/c.r 
 
 •c. 
 
 'll 
 
 3 
 
 c 
 
 Ifidrooon 
 
 larbcn 
 
 s t !< H 
 
 
 
 1 
 
 
 Sulphur 
 
 jj|K 
 
 
 IVtosphcrus 
 
 
 Z 
 
 (7niniefcr* ti< c.epress 
 silt'll in n' ci'tiibiistib/c 
 y substances as ivi/l 
 
 
 
 be disci'yered . 
 
 
 
 
 
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 1 Vatina 
 
 
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 (rold 
 
 r. 
 
 © 
 
 Silver 
 
 - 
 
 © 
 
 Mercury 
 
 
 
 
 
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 Hn 
 
 r' \ 
 
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 r.’f/'.r 
 
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 Lead 
 
 
 © 
 
 Iron 
 
 
 © 
 
 Zink 
 
 
 © 
 
 A h i m tilth sc 
 
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 ED 
 
 CD 
 
 ed 
 
 m 
 
 m 
 
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 m 
 
 ED 
 
 ED 
 
 ED 
 
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 lUsmnth 
 
 xlntimony Stibium 
 
 / O hi lit 
 
 i . irxettic 
 I Moh bt/m 
 Tuner sten 
 
 A lunatic \ 
 
 Poraeic 
 Fluoric 
 i Succinic 
 Acetic 
 I 7'attun us 
 l\n ’tartan ‘us 
 
 M 
 
 ED 
 
 ED 
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 ED 
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 o 
 
 v o 
 
 4< o 
 
 0 
 
 lit <$> 
 
 S r 
 
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 A 
 
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 C 
 
 c 
 
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 Fartbs 
 
 /bnibtistibh ■ 
 
 / Substances 
 
 A fan Hie 
 
 iflhstu/icc.f 
 
 7 <t>mfh utihl . i, u/itYoNc 
 
 ^ Bi/.ft'S 
 
 □ 
 
 /V f Foh - li'uli/Yii/’/i 
 
 \ compound Substance. 
 
 Olpper 
 
 Acini. 
 
 iv// 
 
 iir/' 
 
 - 1 / tncfancrc 
 
 Nfckc/ 
 
 Bismuth 
 
 An/irnony 
 
 jArsr ii/e 
 
 Udybdcna 
 
 TaMr J 7 . 
 
 Cow jlminii om oi' Colon r | !**“*" 
 
 n il// S/t/t/de dubs , /ir//i'i\r />/\ 'din'itut 
 
 t/ir St'/id^At] i/i(/ y <irit/ Ae/tibr/ti Stutos. 
 
 f ladtc 
 
 
 
 Si did 
 
 Liquid 
 
 At tir on tt 
 
 
 
 
 
 
 
 ( Jtrie 
 
 
 i Ni/n-acn 
 
 A 
 
 V 
 
 ( 
 
 Malic 
 
 u 
 
 5» 
 
 Li rash 
 
 A 
 
 l/\ 
 
 A 
 
 Benzoic 
 
 / 5 
 / v 
 
 1 St 'tin .. 
 
 A 
 
 A 
 
 A 
 
 7V/> /ionic 
 
 
 Barytes 
 
 V 
 
 V 
 
 
 Pyromudc 
 tarn p/u •. ric 
 
 
 Liftu 
 
 V 
 
 V 
 
 V 
 
 Lactic 
 
 
 I mesia 
 
 V 
 
 V 
 
 
 Sai>'/ii'lac/ie 
 
 
 . thinum 
 
 V 
 
 V 
 
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 h -rune 
 
 
 Silar. 
 
 V 
 
 V 
 
 V 
 
 Ibussic 
 S chil tic 
 
 
 Hidroaen - 
 
 3 
 
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 Bom hie 
 
 
 Idrbf n 
 
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 C 
 
 Litfiie y 
 
 
 Su/phur 
 
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 F.ther 
 
 Phosphorus 
 
 rs 
 
 
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 Alcohol 
 
 Gi Id 
 
 o 
 
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 G 
 
 Fired AH 
 
 Pkdina 
 
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 © 
 
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 Silver 
 
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 Abnurv 
 
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 I7n 
 
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 Mums 
 
 
 
 
 
 Muriatic Jituhral 
 
 Tlcritcic Jbttliciil 
 
 Fluoric Rat/im/ 
 
 Succinic Radical 
 A* toils Radical 
 
 Torturous /bn lira/ 
 
 l\rotnrtnr> tts Radm/ 
 
 ilm He Radical 
 
 Gallic / ith/ica! 
 
 f'itric Riu/ictil 
 
 Malic Radical 
 Rm zoic Radical 
 .I\ n dii *nit • Radical . 
 
 / amphoric Radical 
 Lactic Radfai / 
 
 \ Saecho lactic Radical 
 
 I Formic Radical 
 
 /busstc Radical 
 
 \S, />aeic Radical 
 /iambic Riittica / 
 
 Solid 
 
 Lii/uiif 
 
 Aeriform ! 
 
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 bo 
 
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 ED 
 
 bD 
 
 pi 
 
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 Solid 
 
 Liquid 
 
 l| Litbic Riit/ical 
 
 CD 
 
 bD 
 
 j Other, 
 
 0 
 
 
 Wet hoi 
 
 0 
 
 o 
 
 p 
 
 Tahir M. 
 
 77 tr known (bmbin/itiond of * 
 
 O x i g* e id and ( ' a I o v i e 
 
 u’t/ft di/l'crcrit . fuhstancr.t . 
 
 Nitrous /ills 
 
 /Vitro us Acid / fas ... 
 
 Nitrons Arid 
 
 Nitric Arid 
 
 / 'aiacnized Nitric - fad 
 
 Water. 
 
 Vapour or' Water 
 
 Parbonic Aral Gas 
 
 Sulphurous ( hide tins .. 
 Sulphurous At 'id Has .... 
 Sulphurous Arid 
 
 Liquid Sulphuric Acid 
 
 Concrete Sulphuric Acid 
 
 Concrete Phosphorous Add ~ 
 
 In quid Ihospharous And 
 
 J.nfuid Phosphoric And 
 
 Liquid Mu riii tic Acid - 
 
 A fanatic Acid fras 
 
 tlviacmscd /lunatic Act * / tins 
 Idt/uid 1 Xripenized lln riti tic Acid 
 / bncn'tc Clriqcnizi'd Muriatic Ant! 
 tbnerete Ronieir And 
 
 Fluoric Add, this 
 
 /.',</ 
 
 Lurnid tartnrous Acid 
 
 Conert'fr furtarous .fad 
 Liquid IVrotnrturous And 
 
 [pg[jFpl3I3 i SP i !li][ir?'7? f 
 
Plat, JV. ft 'tt/ituu > /. 
 
 1 
 
 (Intirwation oA Ttibh'IlI. 
 
 i' 
 
 Liquid Acetous And 
 
 EK 
 
 icetous Aeui Gas 
 
 F> 
 
 liquid SSd 
 
 tZL 
 
 Concrete (XraJic Add 
 
 on 
 
 liquid Gallic Acid 
 
 CELj 
 
 liquid iitru ■ JM 
 
 m 
 
 Limdd Iftft Acid 
 
 ED-i 
 
 foncn’tc 3 <- azoic And 
 
 EZL 
 
 liuuiil lyroluliuMS - i -u/ 
 
 tZh 
 
 liquid lAromucons - hud 
 
 
 Concrete Cataphoric And . 
 
 EZL 
 
 Liqtiiil Lactic Add 
 
 tn 
 
 Concrete . 'V /< > iu >hictic ii'UI " 
 
 En 
 
 Liquid Jfortnic idd 
 
 \E 1 
 
 1 £ Geu 
 
 llL 
 
 liquid. Jtbadt !.i.t 
 
 ZZ] 
 
 Hi ft ud Print hie tdrl 
 
 ITT] 
 
 Oxide of Tunpsten 
 
 er 
 
 Tuna /tic Arid. 
 
 Q. 
 
 t trite of Meh hdena J 
 
 ®"S 
 
 i it. r. t. 1 / /| / lir id i 
 
 11 
 
 ride t If mi 
 
 0 " j 
 
 Ccncrei* Arsenic Arid 
 
 Q. 
 
 Oxide of Cohalt 
 
 0 " 
 
 t hide of . Inti at • >ny ... 
 
 0 "! 
 
 < .1 id. . Bismuth 
 
 0 " 
 
 (bade of WAcel 
 
 ©■ 
 
 / » /./. m Lfatu/anest 
 
 
 Unde of Zink 
 
 0 * 
 
 t Znufi at Iran 
 
 dfi 
 
 > it /./. of I end 
 
 0 " 
 
 (hide ol' Copper 
 
 €T 
 
 - St i / I,,, 
 
 0 ^ 
 
 /hide of Mercury 
 
 0 " 
 
 t • uk . / w/i . / 
 
 07 
 
 Ori.tr , « ' 6 ,. 1,1 
 
 a 
 
 Oddi of //. /////,/ 
 
 (57 
 
 Table f\\ 
 
 lln/ltlfU *lks' oT / J/Y * S / / / >X f ( I / / < 
 (alone fhrms // thin / iti some 
 or these ( / *////>/ \tiltt »//.»*. 
 
 _ Inunoniaeal frV/s 
 tom reb * - ■itnrm >nia 
 (hrburettr v/ Ni/ropm tuts. 
 S/dp Iiuret ted JVttrcarn this .... 
 Gtrburetied TUdropen Gas 
 . tulphun u< ft fli/tri pen (rax 
 Phosphorated Ihdropen Gas 
 
 Sulphuret of Totash 
 
 Sulphuret of Soda 
 
 Sulphuret 01 s Barytes. 
 
 Sulphuret of Lu no. 
 
 Sulp/uiret • *f Alus/une 
 Stdp/utrot of Go/d 
 
 
 U/ov t'f (it'Id .If 1 topprf... 
 
 A/ualpa/u of Go/d 
 
 of Silver... 
 
 Alloy of Tut V Copper 
 
 />/ * 7 / 7 / X % load 
 
 of Iron .<• .1 Ian, ranee. 
 
 of Iron .<• tV/ehel ....... 
 
 t ar/ moot of Iron 
 
 'arhonat of Ahk/nexia 
 IrtK 
 
 ^C_ ( Iri/mtria/ if Soda 
 
 ®C 
 
 /torn/ of Soda 
 
 . hunt uti.i 
 
 Lime .... 
 
 t ’a/nphorat of A > rash 
 Jtnmonia 
 
 Table V. 
 
 IN v 1 j l rn 1 S m 1 1 3 cow/ test'd 
 <>/’ Three SnWVmt’rs,, 
 
 / ft/e/if • is /n •/ inj>n 'st/, bt v ymse they an 
 it II st/f y v si 1 1 < > In • /// thi • si d/d stab ‘. 77 b \ bn 
 
 
 ® i 
 
 Sulphur. / of Mercury ! 
 
 
 Sulphuret of Tin — 
 
 
 Sulphuret of topper j 
 
 i 
 
 Sulf/huret of Lcrtd - 
 
 
 Sulphur t / of Ir, /> 
 
 
 Sulphur ct of 2 udc 
 
 
 Sulphuret o f Nickel 
 
 
 Sulphuret rtf J list nut h 
 
 « 1 
 
 Sul/ >huref of 'Antimony 
 
 
 Sulphuret ill' Cobalt 
 
 
 Sui/>/wret of Arsenic 
 
 
 Sulphuret of Mbfybdena, 
 
 & 
 
 IVtosphuret 0 /' Lear/ 
 
 % 
 
 
 ©) 
 
 Alloy of P/atina X’ Gobi 
 
 xj 
 
 @0 
 
 4 /' Pht/inn < Sth t r 
 
 ;©© 
 
 of Gold X' Silver....- 
 
 ie® 
 
 vul 
 
 Vd 
 
 VEL 
 
 . hut. 
 
 ©EL 
 
 Ztviutof Sod/L 
 inure rtf a 
 
 . It mt 
 
 Horn In at 0 / I'otash 
 
 . im mom a 
 
 II Gal hit of fbtask 
 Mala/ of Potash 
 Mud a! of Potash 
 Soda 
 
 Altrat of fbfa.th 
 
 Sulpha t of Ammonia - 
 
 with rtr/vw of has* 
 
 . i Sulphat of Part tes 
 
 Sulpha/ of hmr - 
 
 it id// Ions S/dp. hid of A/nminr ( 
 . S' alpha/ of ^ Hu /nine .... - 
 
 AH ~1 
 
 j H j I Xi/rif of Potash 
 
 \/ l 1 v ~j I Oj* Xihft I / ! ' t . I h 
 
 AEL Attdu/ous ( Km fat of phfash 
 I ^ ^] ( p\ ! / 'hospital of Potash 
 
 VEIL I hospital of Soda 
 AEL I Phosphat of Ammonia 
 
 ,jn I hospital of Lime 
 
 X/ l r | j Phosphat of Iron 
 
 
 Al 1 1 I Phosphit of Soda 
 
 ,©EL J lYussiat of Iron 
 
 VEL I J Xrotartri/ it/' Potash 
 
 /Sjl /1 /Yromueir 0 / ' Soda 
 
 Pyroliordt of Ammonia — 
 
 Sarrholat of Potash, 
 
 Sehat of Soda 
 
 | C\)/ Snip hat of Ahttnine 
 
 v> - ■ ~~ I with r'S'i fs.r 1 v ‘ hast’ 
 
 AS— Sulpha 1 of SLipnesut 
 
 AFH . tn/phat of . filv* r ©LL 
 
 ! l/dphat of Men'u rv ) 
 
 n! f that of Tin ®U_ 
 
 A^_ Sn/phat of topper. 
 
 • Sulpha t of J.rad 
 
 V©- St dp /hit of Inn 
 
 , Sn/phat of Zink 
 
 . ! 
 
 /^ ry | Sulpha I of Manaanese 
 I' 1 | St t!f> hat of At ek-’l 
 
 f. - 
 
 Sul/ that of Anfuuonv ®s-L 
 
 Sn/phat of (obit If - — J 
 
 Sulpha/ ofArsenie ! 
 
 AEL . tn/phat 1 rf Air 'hhdena — ®U_ 
 
 AEL 
 
 Su Ip hit of Pettish 
 
 Snlpluit of Potash 
 
 . Iridu/ous Sulpha/ of Potash 
 
 Sulpha/ of Potash 
 
 ut/h esters* of base. 
 
 Sn/phat 0 / Soda 
 
 Acidulous Sulpha/ of Soda 
 
 Sulpha/ of Soda 
 
 with excess of hose. 
 
 Suf/dutt of Ammonia 
 
 Adthdous Snlphttr of hntnenin 
 
 Al s-A Sulpha/ of Tunpsten - -j ©U. 
 
 f\.j I Suceinat of Potash 
 
 A. I . fr, rental of Potash 
 
 X" Aeidulous Arseniat of li 'tosh 
 
 &L± 
 
 irsi’ttiat of Pobts/i 
 
 Ht/h AIVYV/ of h<tse 
 
 n-ui|k 
 

CHE 511 1 C AX. APPAMA T U S 
 
 i'km v 
 
 t'ouppi' , 
 

 
 

 
 CHEMICAL 
 
 
 ArP AM AT V S 
 
 T/atr V/. 
 
 I'UJ.l 
 

 
 
SALT 
 
 M INI 
 
 1 
 
 l 
 
 A . 
 
 //,//✓• \W. 
 
 C(M»|1««|* fVul|1 
 
 i.loinU< 
 

 BMINE PIT S. 
 
 
 

SAJLT W OIKS. 
 
 /•/„/, -.X. 
 
 jfcvaporaftntf Jh/ts . 
 
SALT WORKS. 
 
 l'kite JO. 
 
 Bavarian Mrt/iruZ of evaporafnujf . ^/// Itn/rrs. 
 
 lutf. /. 
 
J'/afc XI L 
 
 W O ]R K -S 
 
 loJoijt 
 
 Coopoj* fVotp, 
 
Fig. 3. 
 
 r LATE MU- v 
 
 Fig. 6. 
 
 S 
 
 
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 * 
 
 v * 
 
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 X * 
 
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 r 
 
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 p 
 
 
 
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 * 
 
 
 
 
 
 
 
 
 57-S 
 
 I \ 1 X \ 
 
 
 
 
 GETTY CENTER LIBRARY 
 
 
 
 
 
 

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