CORNELL UNIVERSITY LIBRARY GIFT OF George Butler Cornell University Library arV19017 ' Elements of chemistry in which the recen 3 1924 031 287 695 olin.anx Cornell University Library The original of this book is in the Cornell University Library. There are no known copyright restrictions in the United States on the use of the text. http://www.archive.org/details/cu31924031287695 ELEMENTS C ,H E 1 rS T R Y , w wb;ch the BSCENT DISCOTEEIES IN THE' SCIENCE AEE INCLUDED, ITS DOCTEINES FAMILIARLY EXPLAINED ILLUSTRA.TED BT NUMEROUS ENQRAVINOS, AND DESIGNED FOR TEIE USE OF SCHOOLS AND ACADEMIES. BT J. L. COMSTOCK, M. D., HEM. CON. u; 9. ; HON. MBM. R.I. M. B. ; AUTUOB OV NOTES TO CONT. ON CHBMISTRT ; AUTHOR OF oaAM. OF cHsnnsrav ; bleh. mih:kiajlogy ; btatitrai^ hibtort of ^uaiuiufxds AND BIRDS ; NATURAL FHILOSOPmr, STC. REVISED STEREOTYPE EDITION. : NEW YORK: PUBLISHED BT PR4TT, WOODFORD & CO. 1853. Entered, according to Act of Congress, in the year of our Lord one thousand eight hundred and fifty-three, By PRATT, WOODFORD & CO., In the Clerk's OfHce of the District Court of Connecticut. STEUBOTYPED BY PRINTED BY RICHARD II. HOBBS, CASE, TIFPInY, AND CO., HAHTFOKD, CONN. HARTFORD, CONN. ADVERTISEMENT FOR THB THIED STEREOTTPE KDIHOlf. The circulation of this work requiring new stereotype plates, (for the third time,) the author has again, with much labor, revised the whole, and added such new matter, and new illustrations, as the rapid advance of chemical science appeared to demand. Nearly all the old figures -which remain have been, ,re-engraved, arid a large number of new ones added, so as to make the illustrations and embellishments, it is^ believed,i; equal tothos^of any work of the kind in markefa The cuts have either beep, drawn by. the author, or selected from foreign works, and chiefly from Fownes, Graham, Camp- bell, llfttscherlich, or Muller. The ctanges in the text required much labor and attention, in order tQ make the terms cor-* respond, with the present chemical nomenclature.' In many; instances, where the new terms were such as not to be readily comprehended, the old terms are allowed to remain, with the new ones as synonyms. This was thought to be the most convenient plan for the pupils, since this edition may now be employed in classes with the former one. The new matter will be found chiefly in the elementary parts of the worklj- where many changes have been made, and many new illustrations added. Haxtfosd, Conn., April, 1853. PREFACE. It is Lafdly necessary' for the author of the following-volume to make any excuses for its publication, since, notwithstanding the nmltipKeity of books on the same subject, there seems to be none which are exactly adapted to the object for which this is principally designed. The Conversations on Chemistry, and the works of Parke and Joyce, besides the interlocutory form in which they are written, are objectionable, in not containing the recent discoveries and improvements in ihe science ; and the volume of Dr. Turner, though free from these objections, is too large for the use of schools and academies. In this volume, it has been the intention of the author not only to avoid these objections, but, at the same time, to explain the elements and doctrines of the science in sufficient detail," to give a competent knowledge of its several parts, and in such language as can be understood by those who will but read the book attentively, and pursue the subject in course. It appears to the writer, that in teaching- Chemistry to youth, its elementary parts have not been sufficiently insisted on at the beginning. Of all the sciences, this is the most ^^/^ ^.■s<«.-^,^A^<^ /'""7 complete, in respect to its language, tlie order of its aiTang ment, the succession of its subjects, and consequently, in the facility with which it may be learned. But from tllese per- fections, arises the absolute necessity of becoming well ac- quainted with its first principles, before the student can derive and retain any useful knowledge from its study. The nomen- clature of chemistry, the laws of affinity, and %e doctrine of proportions, are far more necessary to a proper knowledge of this science, than is a knowledge of mathematics to the study of astronomy. The cause of an eclipse, or the reason -why the complicated motions of the earth should produce a change of seasons, can be fully understood without the use of mathema- -tics. But without a knowledge of affinity, and proportions, the decomposition of a salt, or the formation of a definite com- pound, are absolutely incomprehensible phenomena ; nor can they be explained without a previous acquaintance with the peculiar language of chemistry. It is from a conviction of the importance of first principles in learning this science, that the author has devoted so much attention to the imponderable agents, attraction, affinity, §nd galvanism, and to the explanation of definite proportions and chemical equivalents, The doctrine of definite proportions, being now universally adopted, forms one of the fundamental principles of chemical science. And whether the theory of atoms, which accounts for the facts on which this doctrine is founded, be true, or false, the doctrine itself will ever maintain its integrity, its elements being nothing more than the expression of facts which experiment and analysis have developed. The subject of proportions, independently of its- relation, to theory or prac- tice of Chemistry, is highly cmious, and of uncommon in- terest, both to the naturalist and the moral philosopher. To PBBFACB. the first it shows, that the laws of nature are equally- inherent and efficient, in dead and in animated matter, and that the effects of" these laws are as peculiar and distinctive in the formation of chemical compounds, as they are in the produc- tion and habitudes of the different races of animals. To the moralist, this subject teaches, that nothing has been formed by the forttdtous concurrence of atoms, but that even the " stocks and stones" bear the impress of creative agency and design — that the air he breathes, and the water he drinks, are formed of invariable proportions of certain elements, and that these compounds are so precisely adapted to his nature and wants, that the least change in the proportion of their constituents would inevitably effect his destruction. Besides the charms which this subject presents to the re- flecting student, the composition of coihpound bodies, in recent books of chemistry, is expressed in equivalent numbfers, and therefore can not be understood without a knowledge of the doctrine of proportions. The author, therefore, before the description of each element and^oompound, has affixed to its name, at the head of the sections, its combining number, or atomic weight. By this arrangement, the pupil, at a single glance, becomes acquainted, not only with the scientific, and common names, bnt also with the cpmposition and propor- tions of all the compounds described. In respect to the authorities which have been consulted in the composition of this work, the principal are, Dr. Thomson, Dr, Henry, Sir H. Davy, Mr. Gray, Dr. Ure, Mr. Accum, Mr. Faraday, the Library of Useful Knowledge, the Journal of the Eoyal Institution, Silliman's Journal, and Dr. Turner. Of the work of the latter author, free use, has been made, his arrangement of subjects, with some variations, having been adopted, and his exposition of the doctrine of proportions care- fully consulted. The work now offered, is not, however, to be considered as a servile compilation ; the former experience of the author as a lecturer, and his habit, for many- years, of analyzing various substances, having given him opportunities, not only of verifying the deductions of others, but occasionally of making new experiments for himself. Hartford, Conn, CHEMISTRY. C'HAPTEE I. EXPLANATIONS. 1.' Chbmistey is that science whicli investigates the-xoinpo- sition and properties of bodies, and by which we are enabled to explain the, causes of the natura,I changes which take place in material substances. Natural Science has bee^n divided into two great branches, the one comprehending all- those natural- changes which are ac- companied by serisible nlotions ; the other including all those natural changes accompanied by insensible motions. The first science is called Natural Philosophy ; including also the Phi- losophy of Mechanics, and the laws of motion. The second is known under the name of Chemistry, or Chemical Philosophy. As a science. Chemistry is of the highest importance to man- kind, since, by its investigations, the practical arts are con- stantly improving. 2. All chemical knowledge is founded on analysis and syn- iAesiSj^that is, the decomposition of bodies, or the separation of compounds into their simple elements, and the recomposition of simple bodies into compounds. * When water is passed through a red hot iron tube, in the form of steam, it is decomposed; its oxygen uniting with the iron, while its^iydrogen passes away, in a state of freedom, or may be collected and retained. This is called analysis ; and- the bodies so separated from each other, if they can not again be decomposed, are called elements. Thus hydrogen and oxy- gen are the elements of water. When oxygen, which may be obtained pure, as will be seen in anpther place, is burned with What is CliemistryT How is science divided'! What is the foundation of all chemical knowledge ( What is analysis 1 10 EXPLASATIOSS. hydrogeli, a quantity of water -will be formed. This is called synthesis, or the reeotnposition of water from its elements. Thus, all knowledge of this science is obtained by experiment. As a science, chemistry is intimately connected with a great variety of natural phenomena. All satisfactory explanation of the causes of rain, hail, dew, wind, earthquakes, and volcanoes, have been given by the aid of chemical knowledge. The phe- nomena of respira'tidn, the decay and growth of plants, and the functions of the several parts of animals, are also explained in a satisfactory manner, only by the aid of chemistry. 3. As an art, chemistry is connected,, more or less intitnately with nearly every branch of human industry, and particularly with agriculture and manufactures. In its application to agri- culture, chemistry furnishes the most direct and certain means of ascertaining what a barren soil wants to make it a fruitful one, and also what ingredient any soil requires to best adajit it to any given kind of produce. Many of our most common and useful articles are manufactured entirely by chemical processes. The making of soap, glass, bleaching salts, the several kinds of acids, and almost every kind of medicine, depend wholly on the manipulations of chemistry. The art of the potter, iron- smith, tanner, sugar-maker, distiller, brewey, vintner, paper- maker, and painter, are also connected in various degrees with cbemistry. 4. Number of chemical elements. — We have ah-eady seen that an element is a body\ir substance which has not been de- composed. Formerly, the nutnber of such bodies known to chemists were quite small, but the advance of science and the skill of practical chemists have shown, that many articles once considered elements were really compounds ; having, many of them, by new methods of manipulation, and new re-agents, been resolved into several elementary bodies. Within the last ten years the number of known ielements have been increased from about fifty to upward of sixty. [See Table of Elementary Substances^ Natural objects may be separated into two grtat divisions or •classes, viz. : Imponderable agents and Ponderable bodies. VVhat'iB synlheBisl What are among the natural phenomena which chemistr* explains 1 W^hat are among the most important arts which derive advantaifp f?om chemiBtry 1 What is said of the number .of elementsl How are nalnrarobjrc" PART I, CHAPTER II. IMPONDERABLE AGENTS. ■5. The imponderable agents are Light, Caloric, or Heat, Eiectrieity, and Galvanisiti. These are called the imponderable agents, because they possess no appreciable weight. The in- vestigation of many of the properties of these agents, and par- ticularly those of light and- attraction, belong to the several de- partments of natura;! philosophy, bilt they each possess proper- tifes also, which are strictly chemical, and it is these properties only, which it is proposed here to examine. 6. Heat is the sensation which one feels when he touches a body hotter than the hand ; and this sensation is caused by the passage of caloric from the hot body to the hand. Thus caloric is the cause of the sensation which we call heat, and heat is the effect of the passage of caloric, into the hand. , Caloric, then, is the matter or principle of heat, while heat is the sensation pro- duced by the transfer of this principle to the living system, from some body hotter than itself. Caloric is impohderable ; that is, there is no appreciable dif- ference in the weight of a body, whether it is hot or cold. This principle seems to be present in all bodies, nor is there any known process by which it can be separated from any sub- stance. For, since heat constantly passes from the hotter to the colder body, until every thing in the same vicinity becomes of an equal temperature, so if we take a substance at a tempera- ture however low, and carry it to a place wiere the tempera- ture is still*' lower, this substance will give out heat until its temperature becomes the same with that of the surrounding air. For instance, if a pieee of ice at 32 degrees of temperature, What are fhe imponderable agents 1 Why are these agents called imponderable ? When one touches a body hotter than his hand, why does he feel the sensation of heat ? What is Caloric 7 What is heati How is it proved that caloric is impon- derable % How is it shown that caloric is present in all bodies ? What illustratious ehow that ice will emit cklorici 12 CALORIC. could be transported to any place, as in Siberia, where the tem- perature is 60 degrees below 32, then this piece of ice will con- tinue to emit caloric until its temperature becomes only equal to that of the surrounding atmosphiSre, and it would therefore give out 60 degrees of heat. It will be quite obvious to any one, that if a piece of iron, or any other substance, be carried from the open air on a summer's day, where the heat is 92, to an ice house, where the heat is only 32, that the iron will con- tinue to part with its heat until it becomes of the same tem- perature with the ice, and therefore that it will, in a short time, lose 60 degrees of heat, as indicated by the thermometer. 1. Heat and cold are, therefore, merely relative terms, and so far as our sensations are concerned, depend on circumstances. Thus we call a body cold when its temperature is lower than our own, and it has, at the same time,- the power of conducting heat rapidly. That the sensation of cold, which we experience when touching another body with the hand, depends greatly on the conducting power of the body touched, is easily proved by the following experiment. A piece of woolen cloth, or fur,, and a vessel of quicksilver, being pjagpd in the same room, will both indicate the same temperature when the bulb of a ther- mometer is wrapped in the one, or plunged into the other. And yet, if the experiment be made in the warmest day of sum- mer, the mercury will feel cold to the hand, while no such sen- sation will be produced on touching the cloth or fur. Now both articles touched being of the same temperature, it is certain that the different sensations must depend on the poweT of the mer- cury to absorb, or conduct away, the heat of. the hand more rapidly than the fur or cloth. ' 8. On the contrary, we say a body is warm, or hot, when it imparts heat to the hand, more or less rapidly. But this sen- sation, to a certain degree,-also depends on circumstances, and is connected with the relative temperature of the hand, and the conducting power of the substance touched. Thus, if one hand be placed in water at 32 degrees, and the other in water at 130 degr^s, and then both hands be plunged into water at 90 degrees, one hand will feel cold, and the other warm, though \he temperature to which both are exposed is the feame. This principle is illustrated by the different sensations which men How are heat and cold relative termsT How is It shown that the sensation of cold often depends on the conducting power of the body 1 When do we sav a hodVic warm or hot ! How.is it shown that the sensations of heat and cold denind on cii cumstances 1 What illustrations are given of this principle 1 I'^u uu cir- CALORIC. 13 and animals experience, when transported from a cold or hot climate to one which is temperate. A Russian would consider the coldest New , England ^winter a pleasant and comfortable season, while an inhabitant of Sumatra, or Borneo, would trem- ble with the cold of our September. A white bear from Green- land, or a dog from Kamtschatka,. would constantly suffer from the heat, while an elephant, or a naked dog from Africa, would require protection from the cold. 9. BeuiLiBRioM OF Caloric. — One of the most obvious properties 6f caloric is, its tendency to an equilibrium, that is, its disposition to pass from the hotter body, to that which is colder. Thus, if several bodies of different temperatures be placed in the same room, the warmer body will continue to im- part its heat to those which are colder until they all indicate the same temperature by the thermometer. This distribution is so equal and general, that two thermometers, graduated exactly alike, and placed under the same circumstances in the open air, will indicate the same degrees of heat though placed miles apart. Thus, caloric has the power of pervading all sub- stances, and of equalizing th^ temperatures. 10. Fbbe Caloric— ^CalSlj exists in two different states, viz. : in a state of eombination, and in a state ai freedom. It has already, been stated, that aU bodies are supposed to contain caloric, but that all bodies do not contain sensible heat, or are not warm to the touch, requires no proof. 06mmon occur- rences, however, as we have already seen, are sufficient to show, that, to a certain extent, the sensation of heat depends on cir- cumstances, and that it is only necessary that the body touched should be of a higher temperature than the hand; for us to per- ceive the sensation of warmth. But it by no means proves, that because the thing touched does not feel warm, that it con- tains no calorie. It follows, therefore, that when the body touched conveys the sensation of heat, that calorie passes from the body to the hand, and this is called free, or uncombined calprio; but that when no sensation follows, the heat is com- bined, or latent, in the body touched, and therefore is not im- parted to the hand. ">• 11. Combined ok latent Caloric. — This is also sometimes What ia one of the most obvious properties of caloric 1 What is meant by equilib- rium ? Ho"w is it shown that caloric tends tc* an equilibrium 7 What conclusion is drawn from the fact that caloric is equally distributed t What are the two states in which caloric exists ? Is it a proof that a body contains no heat because it does not feel warm 1 If every body contains heat, why does it not always feel warm 1 What is free heat J . What is latent heat 7 14 OALoaic. called caloric of fiwidity, because, in the conversion of solids into fluids, a quantity of heat is absorbed which is not in- dicated by the thermometer, and which, therefore, becomes latent in the fluid. The experiments of Dr. Black, in relation to this subject, are highly curious and interesting. These experiments prove, that if a pound of water, at 32 degrees, be mixed with a pound of water at lT2 degrees, the temperature of the mixture will be intermediate between them, and therefore 102 degrees. But if a pound of ice at 32 degrees be mixed with a pound of water at 172 degrees, the ice will soon be dissolved, and then, on ap- plying the thermometer to the water thus formed, it will be found at the same temperature that the ice was before the ad- dition of the warm water, and therefore at 32 degrees, instead of 102 degrees, as before. In this experiment, therefore, the pound of hot water lost 140 degrees of- caloric, which is em- ployed in melting the ice, and which is not appreciable by the thermometer, but remains latent in the water. It follows, then, that a quantity of caloric becomes insensible during the melt- ing of ice, which, were it free, ajymcombined, would raise the temperature of the same weigh-^M water 140 degrees; for, the ice being at 32 degrees, and the water at 172 degrees, at the beginning of the experiment, and the whole being at 32 de- grees at the eiid, the water loses 140 degrees, being the excess of 172 degrees aboVe 32. 12. It is well knbwn, that if a piece of ice be exposed to the rays of the hottest sun in the summer, or if it is placed in a vessel over a fire, the temperature of the ice, or of the water flowing from it, will not be raised above 32 degrees, until the ice is all melted, when the thermometer : placed in the vessel will instantly begin to rise. Those wliol^ave melted snow, or ice, for cuUnary or other purposes, are well aware how much more time and fuel it takes to obtain a vessel of boiling water from ice, than it does from the liquid itself. But this" fact is readily accounted for by Dr. Black's experiment, since we have seen above, that 140degrees of heat are fii-st empl'dyed merely in converting the ice into water, and that this caloric does not i-aise the water one degree above the freezing point, or 32 de- grees, until all the ice is melted. \ 13. TJjis principle is of vast consequence to the world and How many degrees of heat become latent during the conversion of ice into watcp 1 now IS this shown By experiment ! What common fact shows that the temneraturs ofwater cannot be raised as long as it contains ice 7 *^ ■» ure OALOEIC. 15 particularly , to tlie inhabitanfe of cold climates, where the ground is covered with snow and ice, a part or the whole of the year. In some northern climates, and particularly in Russia, the transition from the cold of winter to the heat of summer takes place within a few days, the ground being covered Several feet deep with the accumulated snow of the winter. Now, were it not for the fact above explained, and did the snow and iee follow the same law, in respect to temperature, thajt we ob- serve in some other bodies, this whole mass would be turned into water nearly as soon as the temperature of the atmosphere became above 32 -degrees, and consequently the whole country would be inundated and destroyed by the flood. But in consequence of the quantity of caloric employed in the liquefaction of the snow, the melting is gradual, and no such accident ensues. 'This- is a striking instance of the wisdom and mercy of Providence toward man, though to most of the world it is unseen and unknown. -We have mentioned the melting of ice, as being the most familiar example-, in most paits of our country, of the conversion of a solid into a fluid. But the principle holds with respect to the conversion of other soM's info liquids, though the quantity of caloric required for this purpose varies with the substance. From the experiments of Dr. Irvine, it appears that the fol- lowing named substances vary in this respect very widely, and also very unexpectedly. Equal weights of, each substance are supposed to be employed in the experiments : the degrees in- dicate the extent to which each would have been heated by. the caloric' of fluidity proper to it. Spermaceti, 145 degrees; lead, 162 degrees; bees;wax,l'75 degrees; zinc, 493 degrees; tin, 500 degrees ; bismuth, 550 degrees. * 14. Nature of, heat. — Of the nature of this universal and most important agent, there have been suggested two opinions, viz. : 1st. That it is material, or composed of particles of matter, thoun^h so oiearly imponderable ^' not to be weighed by any means in our power. 2d. That it consists in nothing more than a quantity of matter pervading all space, a:nd that its efiects are produced by undulations. We can not here examine these theories, but only mention them that the student may What circumstanoeB afe mentioned under which the great quantity of caloric absorbed by melting ice, ip a blessing to mankind 1 When the temperature of the atmosphere is above the freezing point, why does not the snow and ice instantly re- turn to waterl In melting, do other solids besides ice absorb a quantity of caloric not appreciable by the Ihermometerl- What two opinions about the natare of heati 16 CALORIC. understand more clearly some of the phenomena of heat which we shall mention. 15. Different kinds of heat. — Some facts which we wit- ness every day are curious illustrations of what might be con- sidered as different species, or sorts of heat. Thus, the window glass which admits the. light and heat of the sun into our rooms, are not at all heated thereby ; the heat seeming to pass through their solid substance without diflBculty, leaving none of its particles behind. But if the same glass be transferred to the front of a fire of the same temperature as the rays of the sun, the glass soon becomes so hot as to burn the hand. Such being the difference between natural and artificial heat in their effects, the one passing freely through transparent bodies which almost entirely intercept the other. 16. Heat by friction and compression. — If two dry sub- stances, whether hard or soft, be rubbed together, h^at is the consequence. Savages, even, kindle a fire by rubbing two dry sticks together ; and every one knows that the hand becomes warm by rubbing it on the sleeve of a garment. When air is suddenly compressed, it emits so much heat as to ignite various substances, of which an illustration is given by Fig. 16. In this case it is supposed that the caloric is forced out of the air by increasing its density, and thus diminishing its capacity for caloric, and on the same principle that friction converts latent, into free heat, by pressing the air along the surface rubbed. But Sir H. Davy succeeded in melting two pieces of ice, by rubbing them together in the vacuum of an air-pump, while the temperature where this curious experiment was made was below 32 degrees, showing clearly that at least an ice-melting heat was developed by the«friction. It is difficult to reconcile the results of this experiment with the theory that the product of heat by friction and compression is owing to th^ diminution of capacity to retain caloric. ^17. Pictet found that two pieces of brass rubbed together produced less heat than one piece of brass and another of wood, and that the heat was highest when two pieces of wood were used. The same philosopher found that solids only produced heat by friction, and that no change of teiiiperature was pro- duced when a sohd acted mechanically on a liquid, or liquids, on each other, or when air or gas was forced ever so strongly on a solid, or hquid. What are the effects of natural aud artificial heat od gla&sT What is Eaid ahout heat by friction and compression 1 STE4M. 17 18. When water, or other liquids, are converted into steam, a large quantity of caloric is absorbed, which is not indicated by the thermometer, and which, therefore, becomes latent in the steam. , , If a thermometer be placed in an open vessel of water, over a fire, there will be indicated a gradual increase of heat until the water boils,, after which no increase of the fire will raise the temperature of the water another degree ; nor does the steam, arising from a vessel of water which boils violently, indicate a greater degree of heat: than the water itself, or of the steam arising from another vessel which boils moderately. The steam conveys away all the heat above 212 degrees of Fahrenheit's thermonreter, which is the teinperature of boiling water under the ordinary pressure of the atmosphere. The quantity of caloric , which combines with the water to form steam, is nearly 1000 degrees greater than that of the same weight of boiling water. ■ In other terms, the caloric of fluidity in steam surpasses that of an equal weight of boiling water by nearly 100.0 degrees. Consequently, there is nearly 1000 degrees of heat in steam which is not indicated by the thermometer, and is therefore latent. 19. By the apparatus. Fig. 1, the latent heat in steam BECOMES APPARENT. The Small glass retort, a, is kept boiling by means of a spirit lamp* From the retort, the tube b, bent at right angles, dips into cold water contained in the jar c, and by which the steam is con- densed. Now, the heat ab- sorbed from the fire, through the water, to form the steam, is given out to the cold water as fast as the steam is condensed. Th^ cold water must, therefore, have its temjieratuye gradually raised until it reaches 212 de'_ grees the boiling point, after which no more steam will be con- why can not water, in an open vessel, be heated iigher-than 212 degrees ! . How- many degrees of heat does steam contain, which is not indicated l^y- the ther- mometer f ' ' ' 2* FIG. 1. Laten\ Heat of .Steam. 18 riG. 2. densed, the water boiling in the jar, as well as in die retort. When this occurs the process must cease. Now, assuming that the jar c contained eleven cubic inches of water at 32 degrees, at the beginning of the. experiment, and thirteen inches at the close, at 212 degrees, then the water int^e jar would have increased two cubic inches, having gained this from the condensation of the steam from the retort. The latent heat, therefore, contained in two cubic inches of water m the form of steam, has raised the eleveji cubic inches in the jar from 32 degrees to 212 degrees. We may therefore, says Mliller, (from whom this experiment is taken,) express the result of our experiment in the following manner. The amount of heat necessary to convert a definite q^uantity of water from 212 de- grees into steam at 212 degrees, suffices to. raise the tempera- ture of a mass of water five and a half times greater, from 32 degrees to 212 degrees. 20. Stbam-engine. — ^The me- ■ chanical details of the steam-en- gine must be looked for in other books, our object here being merely such a description as to- enable the pupil to comprehend its principles. This complicated machine con- sists essentially of a cylinder of metal, a, Fig. 2, in which works a solid piston also of metal, the rod of which passes air-tight through the stuffing-box 6, at the top of the cylinder. The piston is connected with the .machinery to be put in motion, as^the pad- dle-wheels of a steamboat, either directly, or by the intervention of an oscillating beani. A pipe communica,tes with the interior of the cyUnder, leading to a large vessel c, surrounded with cold water, and called The con- denser. Into this a jet of cold ' steam-engine. Describe the experimenc of Mttller.to show the amount of latent heat in steam Describe the principle of the steam-engine. STEAM. 19 water can at pleasure be throvvu by. the. pipe d. By means of a sliding valve, shown at e, a steam communication is made be- tween the boiler and cylinder by the pipe g, and. also between the cylinder and condenser by the tube h. 21. This is called the low-pressure, or condensing engine, and acts thus : the steam being admitted at g, passes by the opening of a valve to the under surface of the piston, while by the opening of another valve, a^jet of cold water condenses the' steam above the piston, which therefor^ is made to rise, with the force of the steam on one side, with only a vacuum on the other. At the proper instant the first valve is closed, and an- other opened by the machinery, by which the steam is admitted above the. piston, wliile the steam is condensed below it, and the motion is reversed, and thus the action is continued constantly ; the up and down, motion of the piston, hy proper jnachinery, giving rotary motion to those parts of the engine by which the paddle-wheels, and consequently the boat is put in motion. An air-pump, not shovm, is an essential partof the machinery, and by which the air and condensed waterjs Removed from the cylinder. 22. High-pressure engine. — This is called high-pressure, . because the piston acts in both directions against the force of the atmosphere, there being no condenser by which a vacuum is formed, as in the low-pressure engines. The force of the steam employed must therefore be equal to the resistance of the atmosphere, greater than in the low-pressure.- In this the steam escapes into the atmosphere instead of being condensed, and hence the air=pump is omitted. Owing to the absence of these portions of the machinery, the condenser and air-pump, high -pressure, are much more simple and compact than low-pressure engines, and hence are always employed for the locomotives of railroa;ds. 23. CAtfSE OF EBULLITION. — Wc havc Stated that the tem- perature of boiling water, and of steam, is 212 degrees, under the ordinaiy pressure of the atmosphere. The cause of ebulli- tion, or boiling, is th^ fotoation of vapor, or steam, at the bot- tom ,of the vessel, ii^^^^^l'*®"''® °^ ^'^ application of heat there. The steam 13|Lp| lighter than the water, or other fluid from which it is made, constantly ascends in bubbles, and escapes from the surface into the open air. The process of What is the difference between the low and high.-pressure engines t Describe the apparatus to ascertain the quantity of caloric in steam. yVhat is the cause of ebullition or boilhigT" 22 STEAM. amounting to nearly 520 feet, makes a difference of one' degree in the boiling point of water. A traveler, therefore, wJio as- cends a high mountain, may ascertain nearly his elevatiou by the temperature at which he finds his tea-kettle to boil, llius, Saussure found that at a certain station on Mount Blanc, water boUed when heated to 187 degrees. This being 25 degrees less than its boiling poin,t at the level of the sea, flawing 520 feet for every degree, would give an elevation ot 13,000 feet. This method can not, however, be very accurate, since the weight of the atmosphere at the same place varies at different times about three inches of the barometric guage. [See JHfoftural Philosophy, article Barometer^ 26. Evaporation. — During the process of ebullition, there is a rapid formation of vapor, attended by more or less commo- tion in the liquid. Evaporation, also consists in the formation of vapor without heat, but the process is so slow as not to oo- c-asion any visible commotion in the fluid. Evaporation takes place, even during the coldest seasons, while ebullition requires various degrees of heat, or at least the removal of atmospheric pressure. To prove that evaporation takes place at ordinary tempera- tures, nothing more is necessary than to expose a quantity of water to the open air in a shallow vessel, when the fluid will be found gradually to diminish, and finally to disappear entirely, ITiere is, however, a great difference in the rapidiW with whim different fluids evaporate, and in general it is found that those whose boiling points are lowest disappear most rapidly. Thus, ether and alcohol evaporate much inpre rapidly than water. The chief circumstances which influence evaporation are, ejc- tent of surface, and the state of the atmosphere in respect to temperature, moisture, and dryness. As evaporation takes place only from the surfaces of fluids, it is obvious that its rapidity must, under equal circumstances, be in proportion to this extent of surface. Thus, a given quantity of water will evaporate four times as soon from a vessel two feet square, as it will from a vessel of one foot square. In respect to temperature, it hardly need to be remarked, that fluids evaporate more rapidly in warm than in cold situations, Fow may a traveler, who ascends a high mountain, ascertain nearly his elevatior^ by the boiling of a Jea-keKte ! What Is evaporation 1 How is it shown that evanori lion talres place without the aid or heat 1 What relation does there stem to he he tween UU.1.US «i o. _ic.ii,r. Lio 1 w imi is evaporation i jiow is It shown that evapori Ires place without the aid of heat 1 What relation does there stem to he be tne boiling point ol aflaid and its evaporation! What are the chief circum s which influence evaporation ? tVf cell LUC LIUIillI^ puiliv Ul a UUIU null 1 glances which influence evaporation ? STEAM. 23 and that the process is hastened in proportion to the degree of heat employed. Fluids evaporate much more rapidly in a dry, than in a damp ■ atmosphere. Even when the season is cold, if the air be dry, this process goes on rapidly, while it is comparatively slow during the warmest seasons, if the air is already saturated with moisture. As evaporation consists in the formation of vapor, and the subsequent j-emoval of successive portions of the ' evaporating fluid by the air which comes into contact with its surface, it is obvious that the process must be more rapid in a current of air, than it is in a place whei'e the air is still. And hence, we find by experience, that evaporation is more rapid in: the open air than in the house, and that, under equal circumstances, is- more speedily effected during a strong wind. 27. Steam absorbs Caloric. — We have already explained, that one of the peculiar circumstances attending the formation of ste^m, is the large quantity of caloric which it absorbs and carries away. 'Now it appears, by experiment, that the" con- version of fluids into vapor always requires large quantities of caloric, which becomes latent in the vapor, however slowly the process is carried on, and hence, under ordinary circumstances, evaporation, by conveying off the heat, has the effect of gener- ' ating cold. To make this fact sensible, by experimentj we have only to pour a little. ether on the hritid, when a strong sensation of cold will be felt during its eva;poration. When our clothes are wet by a shower of rain, we feel cold for the same reason, but the sensation is less strong, because the evaporation of water is not so'rapid as that of ether. It has been explained that water boils at a lower temperature, in proportion as the pressure of the atmosphere is removed. For the same reason,' evaporation under equal circnimstances, is most rapid when the weight of the atmosphere is removed, as under the exhausted receiver of the air-pump. The cooling effects produced by the evaporation of water in the open air are not strikiiigly apparent, because the process is comparatively slow, and, therefore, the quantity of caloric car- ried away from a body in any given time, is but little more than it receives from surrounding objects. But when water is placed Is evaporation most rapid in hot or cold weather? In what does evaporation con- BiBt 7 Why is evaporat4GU more rapid in the open air than in the house 1 What is " said concerninit the latent heat of vapor 1 How is cold produced by evaporation f Does the pressure of the atmosphere influence this process? Why does not the evaporation of water from the surface of the earth produce intense cold ? 24 STEAM. in a vacuum, its evaporation is vei-y rapid, and did not the vapor from it fill the vacuum, and thus prevent further evaporation, the heat would be carried away so rapidly as soon to turn the water to ice. FIG. i. Crt/ophoTua. 28. Cetophorus. — This curious effect is produced by means of an instrument invented by Dr. WoUaston, and called the Cryophorus, or Frost-bearer, Fig. 4. It consists, of two glass balls, as free from air as possible, and joined together by a glass tube. One of the balls contains a portion of distilled water, while the other parts of the instrument, which appear empty, are full of aqueous vapor, which prevents the further evapora- tion of the water, by the pressure the vapor exerts on it. ■ But when- the empty ball is plunged into a freezing mixture, all the vapor within it is condensed ; aind then the evaporation beeotnes so rapid from the water in the other ball, as to freeze it in a few minutes. To make this experiment succeed, the tube should be a yard long, the balls holding about a quart each. The same effect on water will ie produced by the evaporation of ether under the exhausted receiver of an air-pump. 29. Tp FRBEZE WATER BY EVAPORATION. ^"='- ^■ This experiment may be conveniently made by placing a little water in a glass cup, and covering it with ether, after which suspend the cup within the receiver of the air-pump, as shown at Fig. 5. On exhausting the receiver, the ether will boil, in consequence of its rapid evaporation, and in a few minutes the water will be frozen. Evaporation takes place constantly, from the surfaces of our bodies, and it is owing 1» this circumstance that men are enabled to un- dergo exercise during the heat of summer. _ In general, the more violent the exercise, Evaporation. How may the evaporation of water be made so rapid as to turn it<..lf i„t„ -..i What is the instromem Fig. 4, caliedl How may w&er be fro^^V^I,'' '^'° '«' tion of ether 1 From what provision of nature are we enabled to use violpnt . '^ ■ in warm weather? '"»cui exerci; CONDUCTORS OF CALORIC. 25 the greater is the quantity of perepii-ation, arising from the sur- face, and consequently the greater the quantity of heat carried away. In this manner nature regulates the heat of the system, and during health sustains the equilihrium of animal tempera- ture. Whenever this exhalation from the skin is suppressed, which only results from disease, the temperature of the system rises, and fever succeeds. In some cases of this kind, the heat of th& human body exceeds that 6f the standard of health by seven or «ight degrees. The natural temperature of the human body in health, is about 98 degi'ees, and whenever the heat of summer is equal to that of the body, it beconies exceedingly oppressive. The least exertion then brings on copious perspiration, which, in- deed, prevents the immediate consequence of a higher animal temperature, but which is generally succeeded by languor and debility. 30. Animaes resists heat and cold. — It is a wonderful fact, that the living animal has the power of resisting Ijoth heat and cold, and of maintaining its own temperature, whatever may be the temperature of the air or water in which it is im- mersed. Sir Joseph Banks, and Sir Charles Blagden, found by experiment that they could eindure for a sh,ort time the heat erf a room, the temperature of which was 264 degrees, that is, 52 degrees hotter tha,n boiling water. These gentlemen found that their bands could not bear the heal)' of their watch-chains, or metallic buttons, but that their chests felt cold, and that the temperature of their bodies was not elevated above 98 degrees. In -this room, eggs placed in a tin frame, were roasted in twenty minutes, and beefeteak was well cooked in about the same time. CONDITCTOKS OF CALOKIO. 31. Some bodies have the power of conducting ca,loric much more rapidly than others. Thas, one can hardly hold a brass pin for a moment, in the flame of a lamp, without burning his fingers, while a piece of glass of the same size, may have one of its ends melted, without warming the other. Bodies which are most dense are generally the best con- ductors. Thus the metals conduct better than stones ; stones How does nerspiration relieve ub from the effects of excessive heat ? What is the effect of suppressed perspiration on the temperature of our system') What is said of the power of animals to resist heat a^ well as cold t What sti-ilting illustration is riven of the power of men to resist heat7 What bodies are generaUy the best ppn- 'Sudors of heat 1 Are the most dense bodies always the best conductors of heat ■! Missing Page Missing Page Missing Page Missing Page 30 UXPAXSION BY HEAT. FIG. 8. Expansion by Meat. its comparative expansion is. shown by the multiplied motidn of the index, e, along the, graduated scale. In comparing different substances by means of this instru- ment, it will be necessary that all the rods should be of the same size and length, and that the heat of the lamps should be applied the same length of time. From experiments made with this instrument, it appears that, in most instances, there is a relation between the expansitJli of the metals; and their fusibility, and in, general, that those which are most easily fusiUe,. expand most with equal increments of heat. Thus, lead, tin, and zinc, expand much rnore, by the same degrees of heat, than copper, silver, and iron, and the former are much more easily fusible than the latter. 41. -Daniel's pteombtbe. — The pyrometer, or fire-measurer, is an instrument which, by means of the expansion of some solid body, is made to indicate such high degrees of hedt as are not within the range of the ther- mometer. That ' invented by Prof. Daniel, is the most simple and accurate. It consists of a black lead tube containing a bar cf iron, which is fixed at the lower end, and is surmounted by Pyrometer. What bodies expand least, and what most, bf heat 1 What is said of the enual csiiansion of air and the gases by heat ) How il the expansion of a piece of mela o^SSn'L^'liSai'J rr^^ ""'-^^ "^^'"^ of expanslog which .oui^rjlS,^. EXPANSION By HKAT. ' 31 a plug of clay, or unglazed earthenware. The expansion of the iron by the beat, moves the clay, which .acting on an index, shows the temperature. This is, shown by Fig. 9, where a is the iron bar, longerthan the blacklead tube, b, the plug of clay to be placed- on its end, in the-tube. The clay is secured by a piece of platina foil, so as to remain fixed in its place when the iron cools. The clay is ^hown at c, placed in the tube, and act- ing on thearm or hand d by means of a, short lever, and show- ing by the index the' degrees of heat, or the amount of expan- sion which the iron bar suffers. , The expansion of the met^s by heat, is often turned to advantage by certain mechanics and artizansin their business. In constructing large cisterns for brewers, or other manufac- turers, the iron hoops are made too small for the circumference of the vessel. They are then heated, and in this state driven on the vessel, and as they contract in cooling, the vessel is thus bound together more firmly than could be done by any other means. Carriage-makers, by heating the iron band, or tire, which surrounds the wheels of carriages, and putting it in its place while hot, bind these parts together with the greatest pos- sible firmness, ^ 42. Force of conteaotion. — The great force with which metals contract on coaling, was strikingly illustrated some years since in Paris. The two sides of a large building in that city, having been pressed out, by the weight of its contents and the roof, M. Molard proposed to remedy the eVil, by'making several holes in the two walls, opposite to each other, through which strong iron bars should be introduced, so as to cross tlie inside of the building, from one wall to the other. On the projecting ends of the bars, on the outside of the building, were screwed strong plates of iron. The bars were then heated, by which their ends were made to project further beyond the walls, thus permitting the plates to b^ advanced, until they again touched the walls, which might be an inch, or inore. The bars then, on cooling, contracted, and drew the walls as much nearer each other as the bars expanded in heating. There were two sets of these bars, so that, while one set was contracting and [draw- ing the wall to its place, the other set was heating, and prepar- ing to retain what was thus gained. In this manner, a force What relation is there between the expansion of metals and their fusibilities t What is the use of the pyrometer t Explain the construction of Daniel's pyrometer. In what mechanical arts is the expansion of the metals, bj-heat, turned to advantage 1 In what manner were the walls of a building in Paris drawn toward each other by means of heat 1 32 EXPANSION BY UKAT. FIG. 10. was exerted, which the power of man could scarcely have ap- plied by any other means, and :by which the walls of an immense building were made to resume their perpendicular position. 43. Expansion op liquids by heat, may be strikingly shown by means of a hollow glass ball, with a long small tube at- tached to it. ■ When the ball, and a part of the neck, are filled with a liquid, and heat applied to the ball, the liquid expands, and continues to rise up the tube with considerable rapidity, until the liquid boils, when it will be thrown out with great force by the steam. The different expansibihties of different fluids by the same increase of heat may be shown by two such vessel? as that just described. On the tube of each, fix a mark at the same - height, and fill one up to the mark with alco- hol, and the other with water. Then plunge the bulbs of both into the same vessel of boil- ing hot water, thus making the heat applied to each exactly equal. Both the fluids will ex- pand, and rise up the tubes, but the alcohol will be found to rise about twice as high as the water. 44. Expansion of the gases. — ^It has al- ready been remarked that the ratio of expan- sion in all aeriform fluids, is equal, with equal increments of heat. If, therefore, the ratio of expansion for one gas, as for instance, oxygen, be known, then the ratio for all the other gases, as well as that for the common air, which we breathe, will be in- dicated. From the experiments of sereral^hilosophers, it is proved, that this rate of expansion is equal to the -ji-oth part of the volume whieh the gas occupied, for eVery degree of Fahrenheit's scale, at 82 degrees and upward. This calculation is made from the experiments of Gay Lussac, who found that 100 parts, or volumes of air, at 32 degrees, expanded to 1375 parts, when heated to 212 degrees. The increase of bulk for 180 degrees. In what manner is the expansion of a flufd most strikingly sliown ? IIow are the different expansibilities of different iluids. shown 1 Explain Fig. 10. " How mnch more (ixpansible Is alcobol.than water! What is the ratio of expansion in aeriform bodies 1 What is the difference in the Bulk of 100 parts of air at the freezing and boiling palhts of waterl RADIATION OF HEAT. 33 that is, from the freezing, to the boiling point, is therefore 3 '7^, which, by calculation, will be found nearly -rsrth part for each degree. The exj^ansion of air by heat may readily be shown by blow- ing up a bladder, and securing the mouth by a string, so that none can escape, and then holding it towai-d the fire. As the air becomes rarefied by the heat, the bladder will become more and more tense, until it bursts with an explosive report. A more elegant experiment is, - to take a glass tube, terminated by a bulb, and put in so much water as to about half fill the tube, and then, having im- mersed it in a vessel of water,' as' repre- sented in Fig. 11, apply the heat of a lamp to the bulb. As the heat rarefies the air -in the bulb, the water will be forced down the tube, but will slowly rise again to its former place, by the pressure of the atmosphere on the fluid,, when the heat is removed, and the air in the ball al- lowed to contract. ri(?. 11. RADIATION OP HEAT. 45. When we approach a Mated body we become sensible that it emits caloric without touching it, and if a thermometer be carried near, this will indicate an increase of temperature. The caloric thus flowing from a heated body, is called radiant calorie, because it radiates, Or is'thrown off in all directions, like the *ays of light from a radiant point. If the hand be held under the heated body, a sensation of warmth will still be per- ceived, which proves that this effect is produced without the intervention of a str^m of heated air, which is felt only above the hot body, and never below it. Neither is this effect pro- duced by the gradual conduction of the caloric by the air, for the heat from a hot ball may be felt in the open air, at a dis- tance from it, and in the direction contrary to that of the wind. It is found also, that caloric radiates equally well through all the gases, and better through a vacuum than any medium ; and hence we may infer that no medium at all is necessary for the passage of radiant caloric. What simple experiments show tlie expansion of air by heati Explain Fig. U. VVliat is meant by radiant heat 7 How is it proVed that radiant iieat is not coddacted by. the a:r ! 34 KADIAMOil OF HEAT. FIG. 12. When radiant caloric falls upon a splid or liquid, its rays are either reflected from it, and thus receive a new direction, or they lose their radiant form entirely by absorption into the body. Thus, a substance highly polished will throw the heat back toward the radiating body, and remain cold itself; while ainother substance, with a rough surface, will become warm at the same distanee, because it absorbs, but does not reflect the heat. 46. Aescribe Fig. 14, and explain how tbe different Burfaces affect the thermometer. What practical uses may be made on the principles established by Mr. Leslie's ex- periment 1 Why does a bright coffee-pot keep, its contents warm longer than one that is tarnished 1 What is said of the passage of tile sun's heat through glass t What effect does a plate of glass have on the passage of culinary heat 1 Does glass entirely intercept the rays of artificial heat ? 4 38 ' TRANSMISSION *0F UBAT. lutely impermeable to artificial radiant heat, for it has been found that the intense ignition of charcoal by voltaic action, produces an effect on the air thermometer when passed through a glass lens, and also that thin plates of the same substance will transmit indications of the heat of a powerful gas-burner. 53. Transmission of heat by different substances. — On this subject, M. Melloni, a French chemist, has made a series of curious and important experiments. These: were made by means of the thermo^muHiplier, an instniment much more sensible to small degrees of heat than the air thermome- ter. This instrument is constnioted on the principle oi^ thermo- electricity, of which the following is a description : first inform- ing the student, that when two bars of different metals are con- nected together at each end, if one of the joints is heated more than the other, a current of electricity is immediately producj?d. 54. Thermo-electrical piles. — Now if a magnetic needle be exposed to the influence of the above described electrical current, it will be moved, or deflected out of its true position, even though only a single pair of bars be employed ; and by using a series of such bars, and heating their alternate ends, the intensity of the electrical influence may be increased to any de- sirable-extent. Such an instrument is called a thermo-electric pile. That used by M. Melloni in his experiments consisted of fifty-five bars of antimony, and as many of bismuth, laid side by side, with their alternate ends sol- *'*'• ^■ dered together. Fig. 15 repre- sents this thermometer ; a, the metallic bars ; b, a lamp heating one end of the pile, by which the electricity is developed, and the magnetic needle, c, is moved. The lamp being removed, and the end of the pile blackened, in order to _, promote the absorption of the rays Thermopile. of heat, the substances, whose powers of transmission were to be examine4, having been cut into thin plates, were placed before the end of the pile. A screen, having an aperture equal to the face of the pile, was placed between the source of heat, and the plate to be tried What is meant by tbermo-electricity 1 What effect does the thermo-electrical cur- rent have on the Inagnetic needle i How is tb« thermoelectric pile constructed i In what manner is the pile employed ? SPECIFIC CALORIC. 39 while a second screen intercepted the rays of heat until the in- stant of trial. 55. By such means, M. Melloni obtained very curious, and often very unexpected results ; and, among othera, that bodies which transmit light most freely, often almost entirely intercept the rays ot heat,, while other transparent bodies are as perme- able to heat as to- light. 56. Bodies which allow the ready passage of heat, are called trcmscalfint, or diathermcmous, while those which intercept its rays are called intranscalent, or adiathermanous. Among all substances, rock salt 4s most highly transcalent, admitting the rays of heat to pass through it with very little interruption ; while alum and glass, though fully as pervious to light as the salt,, almost entirely intercept the calorific rays. On the con^ trary, some substances, though nearly opaque, with respect to light, admit the passage of heat with. considerable facility, such as brown rock crystal, which, was found nearly as transcalent as the most colorless specimens of the same material. 57. Bodies absolutely opaque, as wood, metals, and black marble, intercepted the rays of heat completely, although it was found that the faculty of transmission was possessed to a certain degree hj nearly opaque substances, as thick plates of brown quartz, black mica, ^d black glass. SPECIFIC OALOKIC. 58. Equal weights of the same substance, at the same tem- perature, contain equal quantities of caloric ; but equal weights of different substances, at the same temperature, contain un- equal quantities of caloric. The quantity "peculiar to each body, or substance, is called specific caloric. „ "When one body of the same weight is found to contain more caloric than another, that containing the most is said to possess the greatest capacity for caloric. — , , 59. When equal quantities of the same fluid, at different temperatures, are mingled together, the resulting temperature is a medium between these temperatures. Thus, if a quart of water at 100 degrees, be mixed with another quart of water at What singular results were obtained by means of tfiis pile T What are transcalent bodies 1 What are intranscalent bodies'! What difference is ^there between the transcalence qf rock salt and alum 1 What is said of glass as a transcalent body 1 What substances are mentioned, which tratismit heat without light 1 Do substances entirely opaque transmit heatl Wbat is meant by;specific caloric 7 What is meant by capacity for caloric? Suppose erfual quantities of the Same fluid, at different temperatures, are mixed, what will be the resulting temperature! 40 SPECIFIC CALOniC. 40 degrees, the temperature of the mixture will he YO degrees. The same result will occur when any other liquid is mixed in equal ..proportions, hut at different temperatures, as oil, alcohol, or mercury. But when equal quantities of (different fluids are mingled together at different temperatures, the resulting temperature is not a medium; but is either above or below it. 60. Capacities op qutcksilvbr and water. — We should expect, without 'experiment, that quicksilver would possess a greater capacity for caloric than the sarne bulk of water, and, therefore, that when equal quantities of these two fluids, at dif- ferent temperatures, are mixed, the resulting temperaitttre would be above the arithmeticar mean. But in this we are disap- pointed ; for if we mix a quart of water at 40 degrees, with a quart of quicksilver at 100 degrees, the temperature of the mixture will not be 70 degrees, as in the experiment with"' the water alone, but only 60 degrees. This proves that a quart of quicksilver, although it weighs about fourteen times as much as a quart of water, still contains less caloric, and, therefore, that water has a greater capacity for caloric than quicksilver ; for, in the first experiment, a quart of water at ipO degrees, raised the temperature of another quart at 40 degrees, to 70 degrees ; but here, a quart of quicksilver at 100 degrees, raises the heat of the same bulk of water to only 60 degrees. The quicksilver, then, loses 40 degrees, which nevertheless raises the temperature of the water only 20 degrees. 61. The relative capacities of water and quicksilver for heat, may be shown by mixing equal Weights of the two fluids at different temperatures, and then ascertaining how much the resulting temperature differs from the arithmetical mean. Mix a pound of water at 100 degrees with the same weight of mercury at 40 degrees, and the heat of the mixture will be 98 degrees ; that is, 28 degrees above the arithmetical mean, because when equal weights of water were mixed at these tem- peratures, the resulting temperature was only 10 degrees ; but here it is 98. The water, then, has lost only 2 degrees, while the same weight of mercury has gained 58 degrees, for the temperature of the mercury before the mixture was only 40 degrees, while that of the water was 100 degrees. The capacity When fluids of diflferent kinds are mixed under the same circumatatices, will the resulting temperature be a medium? Which fluid has the greatest capacity for caloric, water or quicksHverl How is this shown 1 If a pound of mercury at 40 degrees be mixed with a pound of water at tOO degrees, what will be the resulting temperature i SPECIFIC CALOBIC. 41 of water for heat, is therefore to the capacity of mercury for the same, in the proportion of 58 to 2, or as 29 to 1. 62. It appears from a great variety of experiments made by different pHlosophers on this curious subject, that whatever may be the cause of the different capacities of bodies for heat, the effect is greatly influenced by the state of density in which -such bodies exist, and that in general their capacities increase, in a ratio to the decrease of their specific gravities. In . the above experiment, the capacity of water i^ to mercury as 29 to 1,. while their specific gravities are as 1 to 14. 63. Capacity of the gases. — ^Various methods have been employed by philosophers to ascei-tain the capacities of the several gases for heat. 64. To determine and compare the relative capacities of these bodies in this respect, Gay Lussac, contrived, an apparatus, by means of which, a hot current of one gas met a cold current of another gas, in the center of a small reservoir, containing a thermometer. . A thermometer was also placed in the current of each gas before they met. Thus, by knowing their tempera- tures before their mixture, and afterward, it was easy to infer their respective capacities for, caloric. 65. Bernard, in order to determine the specific caloric of elastic fluids, caused them to pass through a pipe inclosed in a largerpipe, the latter being constantly filled with steam. In this manner he was enabled to -know precisely the temperature of the gas under ejtperiment, and also to raise the temperature of each to the same degree. Having thus determined its tem- perature, the gas was then made to pass into a spiral tube im- mersed in cold water, and the specific caloric of each gas was inferred by the quantity of heat it imparted to the water. By these and similar experiments, it has been ascertained that the aeriform fluids differ greatly in the quantities of their specific caloric, — thus, the capacity of hydrogen for caloric is more than twelve times greater than the capacity of an equal bulk of atmospheric air, though the air weighs about thirteen times as much as the hydrogen. It Is also ascertained that out of nine gases on which experiments were made, none except hydrogen has a capacity for heat equal to that of water, but that they all What are the proportionate capacities of mercury and water for heat-? In general, do the capacities of bodies for heat increase, or decrease, frith their densities'? By what method did Gay Lussac determine the capacities of the gases for caloric 7 By wliat method did Bernard determine the capacities of the g&ses for catoriG ? What gas has the greatest capacity forlieat?.In general, what class of bodies have (he greatest, and what the least capacity for heat ^ 4* 42 SPECirlO CALORIC. have greater capacities than any of the metals. Hydrogen, the lightest of all bodies, has the greatest capacity for heat, while the metals, the most ponderous of all bodies, have the least. 66. The same substance by having its bulk enlarged, and consequently its density decreased, acquires an increased ca- pacity for caloric. Thus water, when thrown on the bulb of a thermometer, sinks the mercury, because, in assuming the form of vapor, its capacity for caloric is increased, and it consequently absorbs and carries away the heat from the mercury. Some philosophers have accounted, in part, for the intense cold in the upper regions of the atmosphere, on the suppo.sition of the increased capacity of the air for heat as tJie pressure of the in- cumbent atmosphere is removed. 67. Ignition by pressure. — On the contrary,, we ^k'- i"- know, that by increasing the density of air, its capacity for caloric is diminished, and that under certain circum- stances sufficient heat may be set free in this manner to produce ignition. This effect may be produced by the little instrument represented by Fig. 16. It consists of a metallic tube, ten or twelve inches long, the bore of which is less than half an inch in diameter. To this is fitted a rod and piston, moving air-tight; the lower end of the piston being excavated to receive a little tinder. When the piston is suddenly forced down, nearly to the bottom of the tube, the condensation of the air it contains, evolves so much heat, as to set fire to the tinder in the end of the piston, and in this way a fire may conveniently be ^'re kindled.. ''""■ 68. Table of specific caloric. — By the following table it will be seen that there are extraordinary differences in the capacities of different substances for contaming heat. These results were obtained by the most accurate modes of experi- ment, by the French philosopher Regnault. Water, . . . 1000 Ice, ... . 513 Oil of turpentine, 416 Specific heat in equal weights. Wood charcoal, 241 Sulphur, . . . 203 Glass, .... 198 . If a body has its bulk enlarged, is its capacity for beat increased or diminisbed thereby t How has the intense cold of the upper regions been accounted for on this principle 1 VAPORIZATION. 43 Bulistanees. Diamond, Iron,. . Nickel, Cobalt, Zinc, , . Copper, Arsenic, Silver, ." Specific he&t in eqtiiii weights. . 147 . 113.79 . 108.63_ . 106.96 95.55 95.15 . 81.40 . 57.01 Tin, . . Iodine, . AiHtimoDy, Gold,' . Platinum, Mercury, Lead, . Bismuth, Specific heat in e^uai weights. . 56.23 . 54.12 . 50.77 . 32.44 . 32.43 . 33.32 . 31.40 . 30.84 Gbsebvation. — In chemistry, nothing must be left to con- jecture, all must be tried by experiment, and the result is often what was least expected. In the present case, without experi- mentj who could have imagined that the .capacity for heat is greater in water and ice than in platinum, gold, and silver ; and yet we find that water has more than twenty times the capacity of the most dense metals. VAPORIZATION. 69. By vaporization or evaporation is meant the conversion of a liquid, or solid into an aeriform body. This, with respect to most solids is performed by heat more or less intense, accord- ing to the nature of the substance, and it is even supposed that with suflScient degrees of heat, all substances would become elastic fluids. But many substances, as water and alcohol, and even some solids, as camphor and ice, evaporate by mere exposure to the air. In general, however, when a solid is con- verted into vapor by heat, the process is called sublimation, thus sulphur* and mercuiy, and some^other solids are purified by sublimation, or dry distillation. We have already spoken of evaporation, chiefly as induced by ebullition, but the subject has several other hearings which it will be well to illustrate and explain. 70. Maximum density. — At a certain degree of heat there exists for the vapor of difierent substances a state of density which it can not pass without losing its gaseous condition, and becoming a liquid. This point is called its state of maximum density. When a Volatile liquid is introduced in sufficient quan- tity into a vacuum, this condition is already reached, and then How is it proved that .the air tlas less capacity for heat when condensed than otherwise ? What is the difference between evaporation and sublimation ? What is meant by the maximum density of a gas ? 44 THERMOMETEE. evaporation ceases; and any attempt to increase the density of this vapor by compressing it in a smaller space, wiU be attended by its liquefaction. Thus, if a little ether, be intro- duced into a barometer tube, and the tube be slowly sunk into a deep cistern of mercury, it wiU be found that the height of the mercury in the glass will remain unaltered, ^lntll the upper extremity of the barometer approaches the surface of the metal in the reservoir. It will be observed . also, that as the tube sinks, the little stratum of liquid ether increases in thick- ness, but no increase of elastic force occurs in the vapor above it, and, consequently, no increase of density ; for tension and density in elastic bodies, are always directly proportionate to each other. 71. The point of maximum density of a vapor is dependent upon the temperature ; it increases rapidly as the temperature rises. Thus, taking the specific density of atmospheric air at 212 degrees to be 1000, then that of aqueous vapor in its greatest state of compression at different temperatures will be as follows : — Temperatare. Specific gravity. Weight of 100 cubic inches 32 degrees. . . 5.590 . . . ;136 grains. 50 " . 10.293 . . . .247 " 60 . 14.108 . . . .338 " 100 " . 46.600 . . . 1.113 " 150 " 170.293 . . . 4.076 " 212 " 625.000 . . 14.962 " Thus pressure, by increasing the density, may cause an elastic fluid to assume the liquid form ; and the same effect, in many instances, is produced by cold, inasmuch as loss of heat de- presses the point of maximunt density. {See lAquefctction of the Cfases.) THEKUOMETER. 72. The thermometer is an instrument founded on the prin- ciple that the expansion of matter is proportional to the aug- mentation of temperature, and is designed to measure the varia- tions of heat and cold. The first attempt to measure such variatrons on this principle was made by Sanctorius, an Italian physician, in the seventeenth Od what pri'nciple is the thermometer constructed 7 -^ho first constructed ther- mometers 7 What fluid was first employed to indicate the variations of tem- perature 1 THERMOMETER. 45 century. He employed a glass tube, blown into a ball at one extremity, and open at the other. After expelling a sntall part of th^ air by heating the ball, the open end was plunged into a vessel of colored fluid, and as the air in the ball cooled, the fluid ascended up tjie tube. Any variation of temperature by expanding, or contracting the air in the ball, woJild then cause "the liquid in the tube to lise or fall ; thus formiug an imperfect air thermometer. T3. A better construction for aii air thermometer is ^^^- ''• represejited at Kg. 17. It consists of a thin glass bottle, containing a small quantity of a colored" liquid, and stopped closely by a cork. Through the cork is passed a broken therniomet^r tube, open at both ends. This tube descends nearly to the bottom of the bottle, and dips into the fluid. There is, therefore, a quan- tity of air above the fluid which can not escape, and when this expands by the application of heat, the fluid is forced up the tube. /Ihus the height of the fluid will indicate th& expansion of the air, and conse- quently, the degree of heat to which the instrument is exposed. There are, however, two objections to the employ- ment of air for this purpose. Its expansions and con- tractions are so great, even by small changes of tem- perature, that a tube several feet in length would be required to measure them ; and as air suffers condensation by pressure, the variation of the barometer would affect its height, at the same temperature. ' 74. Differential thermometer. — For the above reasons, the air tHermometer, for common purposes, is both inconvenient and inaccurate, and therefore haS' long since been laid aside. There is, however, a modification of this instrument, invented by Mr. Leslie, and called the differential thermometer, which for certain purposes is a very elegant and useful instrument. A drawing of this instrument is represented by Fig., 18, and it is' designed, as its name imports, to show the difference of temperature between two places at short "distances from each other. It consists of a glass tube termiiaated at each end by a bulb, and bent as s^hown in the figure. The tube is partly filled with some colored fluid, as sulphuric acid, tinged with carmine. Describe the construction af an air thermometer. What are the objections to the airihermometer t How is the differential thermometer constructed, and for what purposes IS it useful. 46 THERMOMETER. Thermometer. or alcohol, colored by cochineal, the bulbs and fig. 18. other parts of the tube being filled with air. It -will be obvioiis, from the consti-uction of this instrument, that it can not indicate the tem- perature of the atmosphere, since an equal ex- pansion of the air in both bulbs would press equally on the fluid in both legs of the tube, and consequently it would rise in tfeither. But if one bulb is exposed to a higher temperature than the other, then the expansion of the air in this, will be greater than in the other, and con- sequently the fluid will rise toward the bulb where the air is least expanded., 15. Use. — The use of this thermometer, then, consists in showing the difference of tem- perature to which the bulbs are exposed, as in experiments on the radiation of heat, already .described. The scale affixed to one of the legs, shows the rise in degrees, and is divided into 100 parts. The legs are six inches long, and the bulbs an inch or a little more in diameter. The stand may be of glass or wood. Some of these instruments are so delicate as to be affected by the approach of the hand. Air, being inapplicable to the construction of thermometers for the purpose of -measuring the absolute temperature of places or things, for the reasons aheady noticed, solid bodies are equally so from a contrary defect ; their expansion by heat being so small as not to be appreciated without the adaptation of complicated machinery.' A perfect substance for this pur- nose would be a fluid, which would expand uniformly with equal increments of heat, and which would neither freeze nor boil at any temperature to which it might be exposed. Mer- cury approaches nearer to these conditions than any other sub- stance, and therefore this is the fluid now almost universally employed. 76. CONSTEUCTION 01' THE THERMOMETER. The blowing of the best thermometer tubes requires m\ich experience and skill in the workmen, and is perform'fed only by particular artists. This is the most diflicult part of its construction. The mercury is introduced by heating the bulb, and thus rarefying the air Why will not the differential tliermometer indicate the temperature of the atmos- phere! Wliy are not solid bodies proper for the construction of thermometers 7 THBRMOMETEE. 47 •within it, and then dipping the open end of the tube into a vessel of the .fluid. As the air contracts within by cooling, the pressure of the external atmosphere forces the mercury to enter the tube to supply its place. When the bulb is nearly filled in this way, the mercury is boiled to expel the air. Having filled about one-third of the tube, the open end is s&iled hermetically, that is, by melting the glass. This is done while the mercury in the bulb is heated nearly to its boiling point, so as to exclude all the air. , Having sealed the lend of the tube, the next step in the con- struction- of the thermometer, is its graduation. This is done by ascertaining two fixed and invariable points on the tube, which are the same in every ther- fig. 19. mometer, and then by making a scale of equal divisions between these two points. These are tiie freezing and boiling points.. • The freezing point is found by imtiiersing the bulb of the thermometer in melting snow or ice, for it (jiaS been ascertSned, that the temperature of water flowing from melting snow or ice, is every where the same, whatever may be the heat of the atmosphere where the experiment is made. The boiling point is slightly affected by the pressure of the'atonosphei-e; but thether- floometer will be sufiiciently accurate for all or- dinary purposes, when this point is ascertained by immereing the bulb in pure boiling water, open to. the air, and on the level of the sea, during pleasant weather. {See Barometer, in Natural Philosophy.) The freezing and boihng points are marked with a diamond or file, on the tube ;* and on the scale to be afterward affixed, the freezing point IS marked 32, and the boiling point, 212. The interval between these two points is then accur- ately diwded in 180 equal parts. This is the division of Fahrenheit's scale, the thermometer generally employed in this country, and is the only, scale referred to in this work. Thermameur. What -would^e a perfect substance for the eonstructidn of thermotiieters 1 What is the mo^ perfect fluid in our possession for. this purpose % How are thermometer tubes filledf How is the freezing'point of the thermometer ascertained? How is llie boiliuff point ascertained ? 48 thekmometeh. FIG. 20. The commencement of this .scale is 32 degrees _ below the freezing pomt, and is called zero, being marked with the cipher 0, to signify the total absence of heat. This degree ■ of cold, it is supposed, Fahrenheit obtained by mixing snow and common salt, and it was probably the greatest degi'fie of cold known in his time, though at the present day certain mixtures produce much greater, and at a future period, the progress of science may show the means of abstracting hfeat, so as to solidify even the air we breathe. The absolute zero must therefore be considered an imaginary point. Besides the zero and the freezing and boiling points, marked on Fahrenheit's scale. Fig. 19, there are also noted the temperature of the blood, and the heat of summer, and soinetimes other points, as fever heat, -ater) to the negative wire. ' , 143. Transfer of' elements. — Biit thenlost surprising eflfects of the power of this principle is exhibited when the com- pound is placed in cups connected with the two sides of the Describe the method of decomposing water by galvanism, and of retaining the two gases in a separate state. In performing this experiment, why is l^e tube on the negative side first tilled with gas ? In decomposing thp salts, what %w is Observed In respect to the potes at which-tJieir elements are extricated 1 84 CHEMICAL ErrECTS OF GALVANIS^I. battery, and the two constituents of tte compound are trans- ferred from one cup to the other. If the solutjji of any saline compound, such as Glauber's salt, be made in water, and placed in two cups, one connected with the positive, and the other with the negative side of the battery, then, by making a communication between the cups, by means of some moistened asbestos, or cotton, and setting the battery in action, the two constituents of the salt will be transferred from one cTip to the other. 144. Fig. 40 will show the situation of the cups, Fig: 40. the asbestos, and the gal- vanic poles of this experi- ment. Both cups contain a solution of Glauber's salt. This salt is composed of sulphuric acid, soda, and water. The cup, p, is con- nected to the positive side Galvanie Cups. of the "battery, by a wire, passing into the fluid; and the cup, n, with the negative side, in the same manner. The cups are connected by the moistened asbestos passing from the fluid of one to that of the other. When this arrangement is completed, and the battery has been some time in action, it will be found that the water in the posi- tive cup will Jiave an acid taste, while that in the negative cup will have an alkaline taste ; and if the action be continued a sufficient time, all the acid contained in the salt will be found in one cup, and all the soda in the other. 145. Nor does it appear to make any difierence in the result, at what part of the fluid circuit the salt to be decomposed is placed. FIG. II. Galvanic Cups, Explain Fig. 40, and describe how Ihe elements of tlie .-alt are transferred from one cup to the otlier. In which cup is the acid, aiid in which is ihe alltali found 1 CHEMICAL EFFECTS OF GALVANISM. 85 This is provedTby placing three cups in a line, and connecting theiii tog^her by moistened asbestos, as shown by Fig. 41. If the Glauber's salt, or any other saline compound be put into the middle cup, and water into the otherSj and the two galvanic poles be connected with the other cups, p being the positive, and n the negative side, then all the acid will be transferred to the positive, and all the- alkah to the negative cup, while the water in the middle eup wjll remain nearly in a state of purity. If the two outer cups be filled with an infusion of red cabbage instead of simple water, the operator can see the progress of iis experiment, since the contents of one cup will be turned red by the acid, and the contents of the other green by the alkah. 146. ScsPKNDS THE LAW OF AFFINITY. — A phenomenon of a still more extraordinary kind occurred to Sir H. Davy, during his experiments on this subject. - For it was proved that the galvanic action was-capable of suspending the laws of affinity, so that an acid might be conveyed through an alkaline sub- stance, or an alkah through an acid, without any combination taking place between them, or either might be passed through a cup of infusion of cabbage, without changing its color. The three cups being arranged as in the last experiment, and con- nected together by films of moistened cotton, or asbestos, there was put into the negative cup, n, a solution of sulphate of spda, and into the other two cups, an infusion of red cabbage in water ; this infusion being one of the most delicate tests of the presence of an acid or an alkah. After these cups, so arranged, had been for a short time placed in the galvanic circuit, the in- fusion in the positive cup became red, and afterward strongly acid, while that in the middle cup continued of the same color as at first. Thus, as the salt Was decomposed, its acid passed through the_ middle cup without mixing in the lea.st with the water it cqntained, otherwise its color would have been changed. On reveraing the connections with the poles of the battery, the alkali of the salt was transferred to the opposite cup, the solu- tion of which it tinged green, without in the least affecting the color of that in the middle cup. On placing an alkaline solution in the middle cup, the acid Descrfbe Fig. 41, and show- into "which cup the gait is placed, and into which its different elements are transferred by tlie galvanic action. What is the advantage of filling the two outside cups with infusion of red cabbage T What extraordinary phenomenon is observed in respect to the suspension of the laws of affinity by gal- vanic action ? Describe the experiment by which it was found that an acid or an alliati was made to pass through a cup of infusion of cabbage without changing its color. What are theother proofs showing that galvanic action suspends the action of affinity 1 How does Sir,n. Davy account for these phenomena J 8 86 DECOMPOSING EFKECIS OF GALVANISM. was transferred through it without combination ; and when an acid was placed in that cup, an alkali passed through.it in like . PECOMPOSINQ KFPECTB OP GALVANISM. 147. Bird's battkry and decomposing OELL.-^It was form- trly supposed that a large quantity of electiieity, or intense electrical action, was required to effect the decomposition of elementary compounds ; but it appears that a slight current of the fluid long continued, is' sufficient to produce the same effects, in this respect, as a large quantity from a more extensive surface, and hence more costly apparatus. -The following description of Fig. 42, will make this dis- fig. 42. ' ' tinctly understood. A glass tube, a, one and a half inches in diameter, and four inches" long, having the lower end closed with a plug of plaster of Paris, is fixed by means of cork wedges, within the glass cylinder b, which is eight inches deep and two inches in diam- eter. A sheet of copper, c, six inches long and three inches wide, is coiled so as to go into the tube'witli the plaster bottom. To this the conducting copper wire d is soldered. A piece of sheet zinc, s, of the same size as the copper, is loosely coiled and placed into an outer cylinder, to this is soldered the con- ducting wire e. The counterpart of this, being the decomposing apparatus, the two being connected by the conducting wires, consists al?o of two glass tubes, or of a tube and cylinder, h, i ; the bottom of the smaller one is stopped with plaister, or clay, and may be an inch in diameter, and three or four inches long ; this con- tains a strip of platina foil, which is connected "with the zinc plate in the other vessel by the wire e. This being the negative electrode of the battery, into this cell is placed the naetallic solution for experiment. This conductor passing through a corkj stops the tube as the cut shows. The outer vessel con- tains a slip of amalgamated zinc, for the positive pole, or elec- Bird's Battery. Give an account of Bird'S'decompoeJng battery 1 DECOMPOSING EB'FEOTS OF GALVA-NISM. 87 trode, which is soldered to the wire of the copper plate of the otheP vessel, or battery. ' . 148. Action. — Having thus prepared the apparatus, fill the large cylinder of the battery with a weak solution of common salt, and the smaller one, containing the copper coil, with a saturated solution of sulphate of copper, the two fluids being prevented from mixing by the plaster bottom of the latter. Into the other cylinder, containing the zinc, at the end of the wire d, pour weak brine, and' into the tube containing the pla- tinum, place such metallic solutions as you wish to see reduced to the metallic state on the platinum. This apparatus, Dr. Bird states, will continue to afford a continuous current of gal- vinism for several weeks, and by it many, or most of the me- tallic salts may be reduced to their perfect metallic states. {See lard's Natural Philosophy^^ 149. Theory of gaivanism.— -To account for the phenomena of galvanism, Sir Humphrey Davy supposed that the elements of compound bodies were in different and opposite states of electrieity, but that during their chemical union, an equilibrium existed in these electrical states. This theory we have already mentioned, in accounting for the decomposition of water by common electricity. But Sir H. Davy believed it to extend in general to all chemical compounds. To explain how the ele- ments of bodies may be in this state, he supposed that each element is naturally possessed with a portion of electricity, whether it is in a state of combination or not ; and that the elements, in this respect, naturally divide themselves into two classes, one of which is endowed with positive, and the other with negative electricity. In proof of this, it is found as an ex- perimental fact, that oxygen, chlorine,- iodine, [see the latter article,) and acids in general, are naturally negative, while hy- di'ogen, the metals, and the metallic oxides, and the alkalies, are naturally positive. Thus it appears that bodies having the strongest attraction, or diemical affinity for each other, are naturally in opposite states of electricity, and that the sup- porters of combustion, oxygen, chlorine, and iodine, are all negatively electrified. .From such considerations, Sir H. Davy not only accounts for the chemical agency of the galvanic fluid, but also for that force called affinity, or chemical attraction, which impels bodies of In what state of electricity are oxygen, chlorine, iodine, and the acids generally 1 In what state are hydrogen and the metals ? Are bodies having the strongest chem. ical affinity for each other, in the same, or in opposite, states of electricity? 88 DECOMPOSING EFFECTS OF GALVANISM. different kinds to unite and form compounds. Thus, oxygen being naturally negative, and hydrogen naturally positive, they unite with a force or energy proportional to Ihe difference of their electrical states. 150. The decomposing force of the galvanic battery may readily be accounted for on the same principle ; for if water 1» presented to any substance of a higher state of positive elec- tricity than its hydrogen, then a 'decomposition would ensue, because the oxygen would leave *the hydrogen, and attach itself to that substance for which it had the strongest attraction. The voltaic battery produces this effect, by offering to the two con- stituents of water stronger opposite electrical energies than these two substances have for each other. Thus, supposing the elec- trical force of hydrogen for oxygen to be equal to three, and that of oxygen to hydrogen to be equal to three, then they would, combine with a force equal to six. But if we suppose the galvanic, battery to offer to the oxygen a positive electrical energy equal to four, and at the same time to the hydrogen a negative energy equal to four, then it is obvious that their com- bining force would be overcome, and that the oxygen would fly to the positive, and the hydrogen to the negative poles of the battery, and thus that this "compound would be reduced to its original elements ; and we find that this is exactly what hap- pens as a fact, when the water is exposed to the galvanic cirde. 151. Positive and negative elements. — Among the ulti- mate elements which chemistry has developed, there is, at present, known to be twenty-two which are characterized by their electro-negative, and thirty-two by their electro-positive state, in relation to each other.- ELEOTRO-POBITITE. Gold, Tin, , Yttrium, Platinum, Lead, Glucinum, Iridium, Cadmium, Aluminum, Osmium, Zinc, Magnesium, Palladium, Nickel, Calcium, Silver, Iron, Barium, Rhodium, Cobalt, Strontium, Merenry, Manganese, Lithium, Copper, Lantanium, Sodium, Uranium, Cerium, Potassium. Bismuth, Zirconium, How is the decomposiDg foree of galvanism accounted for J DECOiLPOSi:s vanadium, and uranium, are of very rare occurrence, while others, as aluminum, iron, and calcium, are veiy abundant in nature, though combined with other sub- stances. It wiU be observed that by far the greatest number of them comes under the denomination of metals, though sev^ eral of these, as potassium, calcium, and sodium, can not be ob- tained in a separate state, without the most refined and powerfiil chemical aid. Among them all, the most common and abun- dant in nature are oxygen, hydrogen, carbon, and nitrogen, as it wiU be remembered, that of these elements are composed, water, air, vegetable, and animal substances. 21,1. Classification of the metals. — ^The metals have been the subjects of various classifications by different wiiters. When we come to treat of them separately, we shall give a more practical division. In the following table they are ar- ranged according to their affinity for oxygen : Potassiam, Sodium, Lithium, Calcium, Barium, Strontium, Magnesium. Iron, Zinc, Tin, CaCbninm, Cobjdt, Nickel. Copper, Lead, Antimony, Rhodinm, Bismuth, Osmium, Uranium, Iridium. Titanium, Cerium, VI. Tellurium. Glucinum, IV. Zirconium, Arsenic, Molybdenum, Chromium, Vanadium, Yttrium, Thorinum, Aluminum, Silicium. Tungsten, vn. Columbinm. Erbium, V. Terbium, Mercury, Didymium, Silver, Niobium, Gold, Ruthenium, FlatiDum, Pelopium, Palladium, Conarium. Note.— The last group, -riJ., are chiefly new metals, the places of which, in the above arrangement, are unknown ; we have, therefore, thrown them together, and shall hereafter give such an account of each as the most recent publications contain. What are the nunes of the new metals 1 124 CHEMICAL EQUIVALENTS. WOLLABTON's 8CALK OF CHEMICAL KaUIVALENTB. 212. Dr. Ure says, that this scale of chemical equivalents has contributed more to facilitate the general study and practice of ckemistry than any other invention of man. It consists of a piece of mahogany board two or three inches wide, and of a length proportionate to the, extent of the scale it contains, or of the size of the type in which it is printed. Eunning through the middle of the board there is a sliding rule containing ^e proportionate numbere of a]l the most common chemical com- pounds, and on each side of the rule.afe printed the names of the compounds corresponding with these numbers. The divi- sions of this scale are laid out logometrically, after the manner of the common Gunter's scale, and consequently the ratios be- tween the numbers are found by the juxtaposition of the several lines on the sliding and fixed parts with the greatest accuracy. I The arrangement of this instrument is such, that the weight of any ingredient in a compound, or its definite proportion, and also the equivalents of the acids and alkalies, may be at once seen by merely moving the sliding part. 213. On this scale, inst-ead of taking hydrogen for unity. Dr. WoUaston has taken oxygen, which he calls 10 ; but if we slide down the middle rule so that 10 on it stands opposite to 10 hydrogen on the^ left hand,. then every thing on the, scale will be in accordance with Sir H. Davy's system of proportions, taking hydrogen for unity, and also in accordance with the theory of definite gaseous combination by volume. The principle on which this instrument works may be learned in a few minutes ; and after a little practice, it becomes one of the most efficient and beautiful of labor-saving machines, to both the practical and theoretical chemist. Nothing but actual practice with the instrument will convey to the mindof the learner a knowledge of its practical useful- ness ; we will however give an example, by which the principle of its construction may perhaps be comprehended. 214. We have already stated, that on this scale oxygen is the unit from which all the other proportions are calculated, and that this element is marked 10. When, therefore, 10 on the sliding rule iS against this number, the weights of the other Describe the construction of Wollaston's scale of chemical eqaivalents' What Fr'Jfpm fv^SF-T' ^°""?'™ "alj ""«?. ^"d What is its number on the scale ofchem- t?oisTunded ^ evidence is the truth of the doctrine of definite propor. THEOBY or ATOMS. 125 bodies are in due proportion to this number. Thus, carbonic acid being 27.54, and lime 35.46, carbonate of lime being the sum of these numbers, is placed at 62. Then, if the slid- ing rule Ife drawn upward, so that the number 100, on it, cor- responds with carbonate of lime, the other number will coire- spond with carbonic acid and lime, and will show the propor- tions in which these ingredients unite to form 100 parts of carbonate of lime. Thus, the number 56 corresponds with lime, while 44 corresponds with carbonic acid, these two num- bers making 100. THEORY OF ATOMS. 215. To BE DECIDED BY EXPERIMENT ONLT. — That chemical bodies unite in definite proportions, by weight, and also by volume, and that where one body unites with another in more than one proportion, the second is a multiple of the first, are facts resting on the evideoce of experiment alone. These facts in themselves so wonderful, and in their relation to science so important, excited the inquiry and speculations of many philoso- phic minds, as to their cause. Among these inquirers, Mr. Dalton, of Manchester, seems to iave been the most successful, having proposed a theory which accounts, with few, if any ex- ceptions, for all the phenomena observed, and which, therefore, explains satisfactorily the reasons why bodies combine in such proportions. As the basis of this theory, Mr. Dalton assumes that the union of bodies in their smallest proportions, always takes place between the atoms of which they are composed ; that is, one atom of one body combines with one atom of the other body. Thus, water is formed by the combination of one atom or particle of oxygen combined with one particle or atom of hydrogen. This theory supposes also that the ultimate atoms of matter are indivisible; that they are always of the same shape and size in the same body, and that their weights are difierent in the difierent bodies. Thus, the weight of an atom of oxygen is 8 times that of an atom of hydrogen,, these being the proportions in which these gases form water. But when bodies unite in several proportions, then it is 2 or 3 atoms of one, to one atom of the other. -Thus sulphurous acid Wliat is said of Mr. Daftoc's theory of atoms? What does Mr. Dalton assume as llie basis of his theory of atoms? Onthis theory what is water Composed of ? What does this theory suppose, in respect to the divisibility, shape, and weight, of the atoms of bodies I Why is an atom of oxygen supposed to be eight times as heavy as one of hydrogeu ? Why is an atom of sulphur supposed to be twice as heavy as one of oxygen ? 11* 126 THEORY OF ATOMS. is composed of 2 atoms of oxygen united to 1 atom of sul- phur, and sulphuric acid is composed of 1 atom of sulphur and 3 atoms of oxygen, these being the relative weights of their elements. But as it is found tjiat the lowest proportion m which sulphur unites with any other body, it is in the propor- tion of 16 by weight, hydrogen being 1, so it is assumed that a "particle of sulphur is sixteen times as heavy as one of hydrogen, and twice as heavy as one of oxygen. And as in sulphurous acid the weight of oxygen is found to be exactly double that in water, it is reasonable to suppose that sulphurous acid consists of 1 atom of sulphur united to 2 atoms of oxy- gen, and for the same reason, since sulphuric acid contains three times the weight of oxygen that water does, that this acid is composed of 1 atom of sulphur and 3 atoms of oxygen. 216. Why bodies unite in definite proportions. — All this, whether true or false, explains in the most satisfactory man- ner, why bodies combine with each other in definite propor- tions, and why these proportions are expressed by the numbers attached to each. Thus, hydrogen is unity, or the prime equiv- alent, and is expressed by 1, because by weight this gas is found to form water by uniting with 8 parts_ of oxygen. Oxygen is expressed by 8, because its proportion in water weighs eight times as much as the hydrogen. The number for sulphur is 16, because this is the smallest proportion in which it unites with any- substance, and the number for the oxygen in sulphurous acid is 16, becaiise in this acid the sulphur and oxygen are of equal weights, and therefore ju^t twice the ■weight of the oxygen in water ; and the number for the oxygen in sulphuric acid is 24, because its weight is three times that in water. Now^ by supposing that one atom of oxygen is eight times as heavy as one of hydrogen, and that an atom of sulphur is twice as heavy as one of oxygen, or sixteen times as heavy as one of hydrogen, the whole mystery of the law of definite pro- portions is reduced to simple arithmetical calculation, for the proportional numbers are in fact nothing more than the rela- tive weights of the atoms of which the several bodies are composed. Why is It supposed that sulphurous acid contains one atom of sulpliur united to two atoms pf oxygen 1 That sulphuric acid is coin})OSed of one atom of sulphrirjind three atoms of oxygen 1 Why is the equivalent number of oxygen eight 7 Why is that for i-ulphur sixteen 1 Why is the number for oxygen in suljihuric acid twenty- four 7 What is said of the proportionate numbers iu relation to the weights of ,th« atoms of bodies 7 CHEMICAI, APPARATUS. 127 217. Atomic theory not proved. — In respect to the truth or falsity of this theory, it is obviously without the bounds .of demonstration, for we never can ascertain whether the propor- tions on which it is founded are the smallest in which, bodies combine, nor whether, if so, they combine atom to atom, as is .supposed. But whether it be true or false, it does not in the least affect the truth of the law of definite proportions, which, as already stated, is founded on experiment alone, and is, there- fore, purely an expression of facts. The atomic theory, how- ever, must always be considered an elegant and probable hypo- thesis ; and, while it displays uncommon ingenuity, and great chemical research, has the advantage of agreeing, in general, perfectly with the facts obtained by analysis. CHAPTER X CHMICAI APPAEATUS. 218. Before proceeding to treat of ponder- able bodies, and "the description of particular agents, it is proposed to describe some of the most common and necessary utensils, used in the manipulations of chemistry. 219. A CRUCIBLE, Fig. 47, is a deep conical cup, of a triangular shape at the top, and round at the bottom. Crucibles are made of this shape for the convenience of pouring out their fluid contents at either angle. , They are made of clay and sand baked hard, and will withstand very high degrees of heat without melting, but are liable to crack when suddenly cooled. They are chiefly manufactured at Hesse, in, Germany, and hence are called Hessian crucibles. 220. A MELTING POT, Fig. 48. These pots ai-e made of various sizes and materials. . Those used in large glass-houses are made of clay, and are of a large size. Chemists employ those made of silver or platina, as well as of black FIG. 47. Crucible. FIG. 48. Ujdting Pot. What is said in respect to tlie troth of this theory ? Whether it is true or false, does it in the least affect the truth of the doctriDe or definite and multiple propor- tions 7 What is a crucible, and for what purpose is it used ? 128 CHEMICAL APPAKATUS. lead, but of small dimensions. Metallic crucibles are used for particular purposes, when the sub- stance to be experimented on would destroy the common crucible, in consequence of its corrosive quality. . 221. A MATRASS, Fig. 49, is a glass vessel, in the shape of an-eggy with a long neck. It is employed in .effecting the solution of such sub- stances as "require -heat, and- long-continued di- gestion, for that purpose. When used, they are commonly placed in a sand bath, that is, in sand moderately heated. FIQ. 49. Matraes FIG. 60. Retort and Receiver. , 222. A RETORT AND RECEIVER, Fig. 50. Ketorts, 6, are egg. shaped vessels, with the neck turned on one side. These ves- sels are of various capacities, from a gill to a barrel, or more. They are made of glass, metal, or earthen-ware, but most com- monly of glass. No vessel is so much used in experimental chemistry as the retort. In tlie process of distillation, in col- lecting the gases, in concentrating the acids, and in a great variety of other operations, this vessel is universally employed. The receiver, «, is a necessary appendage to the retort, and is destined to receive whatever comes over from it, during the process of distillation. For common purposes, these vessels are made of glass, but in the manufacture of various articles they are made of clay or metal.' 223. A TUBULATED RETORT, Fig. 51. It differs from the plain retort, figured above, in having a tubulure, or opening, as seen in the figure, to which is fitted a glass ground stopper. This opening saves the trouble of detaching the retort from the of what arc crucibles made? How do melting pots differ from crucibles? Of what substances are melting pots made J Of what are matrasses made ^ For what purpose are these vessels used t What is a retort 1 How lar^e are retorts ? Of what are retorts madel What are the uses of rf torts ? What is a receiver, and what is its.usel Of what are receivers made ? How does a tubulated, differ from a plain retort ? CHEMICAL APPARATUS. 129 receiver when any addi- tions are to be made to its conteats, after they are connected, as in fig, 50. It is also necessary fcr the introduction of a safety tube^ a part of this appa- ratus absolutely necessary in some processes, and >yhich will be described in another plate. 224. An ALEMBIC, ^g. 52, is used for the distillation or sublimation of solid, volatile substances. It consists of two parts, the head, a, which is ground on, so as to be perfectly tight, and the body, 6, which is set into a sand bath, when in use. The product of sublimation rises into the head, where it is condensed, and then runs down the spout iiito a receiver. 225. Evaporating dish. Fig. 53. Every chemical apparatus must have among its utensils shallow dishes for evap- orating fluids.. The best are made of Wedgewood's ware, and come packed in nests containing several sizes each. The heat is applied by means of heated sand or ashes, and these vessels are used to evapo- rate solutions of salts, in order to obtain crystals, and for various other purposes. 226. A Florence i-eask, Fig. 54, fur- nished with a tube, to be used instead of a retort Students will save considerable ex- pense by employing these flasks in the room of retorte. The cork is pierced with a burning iron, and through the aperture is passed a tube of glass or lead, bent as in the figure. In ol)taining oxygen, by means of oxide of manganese and sulphuric acid, and for ipany other purposes, this arrange- Tubulated Retort. FIG. 52. FIG. 53. EvapoTaling D.'uh. Florence Flask. What is the use of toe tuhulnre, or openiDg, in this retort 1 What is an alembic 1 What is the use of the alembic I Of how many parts does the alembic consist 1 130 CHEMICAL APPABATUS. FIG. S5. ~A The Common Bloie-ptpe. ment will serve instead of the best retort, wl^ile, if broken, the expense is only a few cents. 2^7/ The COMMON blow- pipe, Fig. 55, is a little in- , strument by means of which the BQOst violent heat of a , furnace may be produced! It is a pipe of "brass, about the third of an inch in diameter at the largest end, and thence tapering, gradually, to a point, and bent, as in the figure. To use it, place the curved end in the flame of a lamp, or candle, and apply the lips to the other end, then blow gently and steadily, giving the jet of flame a horizontal direction. To keep up a constant stream of air for a length of time, the in- spiration must be made by the nostrils, while the_ cheeks are used as bellows. The art of doing this is soon learned.by prac- tice.- The small fragments of ore, or other substance, on which the flame is thrown, must be laid on a piece of charcoal, which is held by small forceps. When a very intense heat is required, and the fragment is so light as to be blown aWay by the air, it may be confined by making a small cavity in the charcoal support, into which the substance is put, and another piece of charcoal is placed partly over this. 228. Gahn's blow-pipe. Fig. 56, is' a much more convenient form than • the common one above described. In the common form, the flame is sometimes nearly extinguished, and the process stopped, by the condensed moisture from the breath. In Gahn's instrument this is prevented by the chamber a, which retains the condensed moisture, and which may be taken off from the main pipe for its removal. The tip of the small pipe through which the air passes to the flame, fits to a socket, so that those of different .sized orifices can be used. 229. Dropping tube. Fig. 57, is a small glass tube, blown into a ball in the middle, and ending FIG. 56. Gahn's Blnw-pipe. Forwhat purposes are evaporatiiVg dishes employed 1 What does Fig. 54 repre- sent? .What are the advantages of using Fiorence nasks insread of .retorts 1 What is the cno^lnon blow-pipe 1 What is .the use of thisioetrument ? Describe ttie mode of -using It. How does Gahn's blow-pipe differ from the common one ? What are the peculiar advantages of this blow-pipe 1 CHEMICAL APPARATUS. 131 Dropping Tube. FIG. 58. with a fine orifice at the lower end. It ^•*- ^■ is filled by dipping the small end into the fluid, and exhausting the air by sucking at the upper end with the mouth. The thumb is then placed on the upper end, which keeps the liquU from running out. On raising the thumb, the .contents will descend in drops, but is instantly restrained on replarang it. This little instrument is highly useful for various purposes, and particularly when it is required, to introduce one fluid under another, as water under alcohol, or sulphuric acid underwater. 230. Ammokia appabatus. — Fig. 58 is designed to collect and retain, for the purpose of temporary examination, such gases as are lighter than the atmosphere, and at the same time are absorbable by water. These gases, for more fliorough examination, require the aid of a mercurial bath, but most of their proper- ties may be examined by the apparatus repre- serited-by the figure. The fbsk, a, is to contain the materials for ex- tricating the gas, and into the mouth of this there is inserted a tube a foot or more long. The tall bell glass, b, or a large tube closed at the upper end, is inverted over this tube, as seen in the figure. As an example of the use of this apparatus, suppose we desire to make some experiments on ammonia, a gas which is rapidly absorbed by water and specifically lighter than atmospheric Ammonia air. The materials for separating this gas are Apparatus, muriate of aimmmia, called also sal ammoniac, and slaked quicklime. These being separately reduced to powder, equal parts are then mixed, and introduced into the flask -a, and the tube put into its place. -On apphcation of a gentle heat, the gas will be set free in consequence of the com- bination which takes place between the Ume and the muriatic acid of the muriate of ammonia. The ammonia is thus set at liberty, and being lighter than the air, ascends and gradually Describe the construction of Gahn's blow-pipe. What is the shape of the dropping tube 1 What is the use of this instrument 1 Descrih* the manner of using the drop- nine tube. For what purposes is the dropping lube useful 1 What is the use of the konaratus represegteJ in Fig. 58 ? Describe Fig. 68. and explain an example of its use How may ammonia be obtained and eiamuied by means of this apparatus^ What is represented by Fig. 59 1 Why can not the gas be poured from one vessel to another, and be retamed in an open vessel like w^ter 1 ^^g^gt^gL 132 CHEMICAL APPARATUS. displaces the air from the vessel 6, and talses its place. This experiment aibrds an instance of the chemical action of two solids on each other. 231. Gas apparatus. — ^Fig. 59 is designed as a simple illustration of a gas apparatus. The method of making fexperi-' ments with the permanently elastic fluids, such as common air, and tlje gases, and of transferring them from ^^- ^■ one vessel to another, though suflSoiently sim- ple, requires some direc- tions for the new begin- ner. The gases are none of them sufficiently dense to be retained in vessels open to the air for any considerable time ; and Gm Ajiparatus. some of them being lighter than the atmosphere, instantly ascend, and are lost, when the vessels containing them are opened. All the gases, therefore, when open to the air, mix with it more or less rapidly, according to their densities, and thus escape us entirely, beiag diffused in the atmosphere. Hence, to retain a gas in a state of purity, it must be. kept from contact with the atmosphere, and he,nce, also, the necessity of first filUng the vessel with a fluid instead of air, before the gas is introduced, and of trans- ferring it under a fluid from one vessel to another. The figure represents a wooden vessel, or tub, a, with a shelf, jfc, fixed a few inches from, the brim. "When the apparatus is to be used, the tub is to be filled with water, so as to rise a few inches above the shelf. Now, when a glass jar, or any other vessel, open only at one end, is filled with water,, by being plunged into the fluid, it will retain its contents when raised above the fluid, provided its mouth be kept under it; for the water is sustained in the vessel by the pressure of the atmosphere, on the same principle that the mercury is sustained in the barometer tube. {See Barometer in Natural Philoso- phy.) The vessels 6, g,f, represent jars filled with water, and inverted on the shelf, their necks passing through an aperture Explain Ihe reason why a Vessel filled with Water may bfr raised above the fluid, provided its month be kept under it. When a tumbler is fdrceil into the water with its mouth downward, why does not the fluid rise in it 1 Vfhen air is introduced under a vessel, inverted and filled With water, wliy does it rise to Ihe highest part ol the vessel 1 CHEMICAL APPARATUS. 133 FIG. 60. in it, so as to preserve their upright positions. The vessels e, c, and i, are retorts, with their necks inserted into the mouths of the inverted jars. 232. Now, when common air, or any gas, is introduced into the mouth of a vessel se inverted, tie air will rise to the upper part of the vessel, and will displace the water, and occupy its place. If a tumbler, or cup, in the state which. we usually call empty, but which is really full of air, be plunge'd into water with its inouth downward, very little water will enter it, because the admission of the fluid is opposed by the included air ; but if the mouth of the vessel be turned upward, it immediately fills with water, while the air is displaced, and rises to the surface of the fluid in one or more bubbles. Suppose this is done under the mouth of a jar filled with water, tiie air will ascend as before, but instead of escaping, it will be detained in the upper part of tlie jar. In this manner, therefore, air may be trans- ferred from one vessel into another,, by an inverted pouring, and the first portions, instead of occupying the bottom of the vessels, like water, ascend to the top, t^e air, instead of running from a higher to a lower vessel, rising •from the lower to the higher one. This is owing to the pressure of the water on the air, or to the lightness of air when compared with water. For the same reason, lead being %hter than quicksilver, . if a bullet of the former be sunk in a vessel of the latter, it will rise to the surface. On this principle balloons ascend ; the hydrogen with which they are charged being thirteen times lighter than the atmosphere, the former is forced upward by the pressure of the latter. 233. A LAMP FURNACE. Fig. 60 is one qf the most indispensable articles in a chemical apparatus. It consists of a rod of brass, or iron, about half an inch in diame- Lamp Fumaee. How does I he rise of a balloon illnstrate this principle J Describe the lamp fiir- nace, Fig- 60. What are the uses of the rings on the ends of the arms 1 134 sPKOiFio GRAvrrr. ter, and three or four feet long, screwed to a foot of the same metal, or to a heavy piece of wood. On this- rod, slide three or four metallic sockets, into which are screwed straight arms terminated with brass or iron rings of different diameters. The screws cut on the ends of the arms where they enter the sockets are all of the same size, so that -the rings may be dianged from one socket to another, as convenience requires.. These rings ate for the support of retorts, receivers, evaporating dishes, &c., as represented in the figure, and may be moved up, or down, or turned aside, and then fixed in their places, by means of thumb screws passing through the sockets and acting on the rod. The^ lamp by which the heat is given for distillation, or other purposes is alsq fixed with a thumb screw, so that the heat can be regulated by moving it up or down. 234. A BELL GLASS, Fig. 61, is employed in making experiments on air, or the gases. It is a glass vessel, of the shape represented in the figure, and of various sizes, from the capacity of a pint to that of several gallons. The" knob at the upper part, is the handle by which it is moved. \ It is used for the temporary confine- ment of elastic fluids, on which experiments are to be made. Large tumblers are good substitutes for bell glasses. FIG. 61. CHAPTER- XL SPECW GiMl*^" 235. The specific gravity of a body is its relative weight when compared with the same bulk of another body. For solids and-Hquids, water is the substance to which the weights of other bodies are compared ; and for elastic fluids, the atmosphere is the standard of comparison. When a body weighs twice as much as the same bulk of water, it is said to have the specific gravity of 2 ; and if it weighs three, four, or five times as much as the same bulk of water, it has the specific gravity of 3, 4, or 5. Water, there- fore, is the unit, or standaM of comparison, and has in this respect the specific gravity of 1. What are the uses of the thumb screws with which the sockets and lamp are fur- nished I What docs Fig. 61 represent % What is the use of the bell glass receiver I - SPECIFIC GRAVITY. 135 When a body is weighed in water, its weigMjrill be dimin- ished by exactly the weight of a quantity of water equal to its own bulk, aod thus the difference between its weight in air and in water being known, its specific gravity is readily found. Taking the specific gravities of bodies is a work of consider- able delicacy, and requires some practice before it can be done in a manner to be depended upon. The experimenter should always have his pencil and paper in hand, in order to set down the relative weights as they are taken. 236. Scales for spe- cific GRAVITY.; — In this FI<5. 62. edition we have added scales for the purpose of taking the specific densi- ties of solids, being in some respects, a more simple method than by the balance, and besides requiring no other instru- ment than is in general use for other purposes. How TO TAKE THE DENSITY. — First weigh the body in the usual manner, and note down the number of grains ; iiien with a fine thread, suspend it ft-om thff bottom of the scale-dish, as shown by Fig. 62, in the vessel of water, a. As it will weigh less in water, add weights until the scale beam becomes horizontal ; then note down the num- ber of grains so added, and thej» will show the difference between the weight of the body in air and in- Water. RuLE.^^ — JJivide the weight in air, by the loss in water, and tJw quotient will be the specific density. Illustrations and examples will be seen under the next article, where it will be observed that, although the means employed are quite different, the results are exactly the same. ^237. Portable balance. — Another mode of taking the specific gravity of a solid, is by means of Nicholson's Portable What is the specific gravity of a body 1 With what substances are solids and liquids compared to find.Lheir specific cavities 1 What is the standard of compari- son for elastic iluids'? Suppose a body weighs twice as much as the same bulk of water, what is its specific gravity 1 What does Fig, 63 represent 7 Describe this balance. What preparation is'necessat7 before the balance is used 1 What are the balance weigllts ?■ After the balance weigirtHS known, how will yon proceed to find the Fpecific gravity of a body ? , 8 8c{desfor Specific Gravity. 136 SPECIFIC GRAVITY. Fig. 63. Balance, represeBted by Fig. 63. The body is a hollow cylinder of tinned iron, terminated at each end by a cone. From the vertex of the upper coi>e rises the small stem, a, of copper or brass, bearing a small tin cup. This cup slips qn,-and maybe removed when the instrument is not in use. From the point of the lower cone is suspended the tin cup, e, at the bottom of which is attached a conei of lead so heavy as to sink the whole instrument in water nearly to the base of the upper cone. Before this balance is used, it is placed in a vessel of water, and the upper cup loaded with weights until it sinks so far that a mark on the stem at a, coincides exactly with the surface of the water. The weights, , so added, are called the balance weights, and their : ' amount may be marked on the cup as a given quantity for future use ; suppose this is 900 grains. por(o«te 238. The specific gravity of a solid may then be Balance. taken as follows : Firet pla«e it in the upper cup, and add weights until the mark on the stem coincides vrith the water ;' suppose this to be 400 grains-; subtract this from the balance weight, and we have 500 grains for its weight in air. Then remove the subject of experiment to the lower cup, and the stem will rise above the mark, because it weighs less in water than in air ; weights must, therefore, be placed in the upper cup until the mark again coincides with the surface of the water ; suppose this, to be 100 grains, which will be exactly the tyeight of th^ water displaced by the mineral, or other solid. The specific gravity is now found by a very simple rule, already given. • In the present instance, we have 500 grains for the weight iu air, and 100 for the loss in water ; therefore, 100 : : 500=:5, the specific gravity. TABLE op SPECIFIC WEIGHTS OF VARIOUS SOLIDS. (FROU MULLBK's PHTSJCa.) Platinu m, coined, . 22.100 Gold, coined, . . 19.325 u rolle4, . . 22.069 " fiised, . . . 19,258 (1 ^ed, . . 20.859 Copper, malleable, . 8.878 t( wire, . . 19.267 fused, . . 7.788 . Aftpr finding the weight of a body in ait, and its weight in water, what is the rule for finding its specific gravity 7 What are the most simple means of finding the Bpecificgravity of aliqiiidl ■ SPECIFIC GRAVITY. la's Copper, wire, . . . 8.780 Iodine, . . . . . 4.948 Cadmium, . . . 8.694 Sulphate barytes, . 4.426 Molybdenum, . . 8.611 Selenium, . . . 4.320 Brass, .... 8,395 Flint glass, French, . 3.200 Arsenic, . . . 8.308 " " English, , 3.373 Nickel, .... 8.279 Marble, , . . . 2.837 Uranium, . . . 8.100 Emerald, . . 2.775 Steel, .... 7.816 Rock Crystal, . . 2.683 Cobalt, .... 7.812 Porcelain, . . 2.493 Iron, wrought, . 7.788 " 2.145 " cast, . . . 7.208 Sulphur, native, . 2.033 Tin, . . . . . 7.291 Ivory, . . . . 1.917 Antimony, . . . 6.712 Alabaster, . . . 1;847 Tellurium, . . . 6.115 Anthracite, . 1.800 Ch)-omium, . , 5.900 Phosphorus, . . 1.770 FI6. 64. 239. Specific gravity of UQuros.- — ^The most simple method of taking the specific gravity of liquids, is by means of a graduated bottle holding 1000 grains of water, which is taken as the unit, or standard, for other liquids. Take a small bottle with a -long narrow neck, as represented by Pig, 64, and having weighed it accurately, introduce into it exactly 1000 grains of pure water, and mark the level of the water with a file on the neck of the bottle. The bottle thus pre- pased will serve to ascertain the specific gravity of any fluid, for since water is the standard by which the comparative weights of all other fluids are known, the same bulk of any other fluid, weighed at the same tem- perature, will be its specific gravity. Thus, suppose that when the bottle is filled with sulphuric add up to the mark at which the water weighed 1000 grains, it should be found to weigh 1800 grains; then the specific gravity of the acid would be 1800, water being- 1000.- If filled to the same mark with alcohol, it might weigh 800 gi-ains. The specific gravity of alcohol would there- fore be-^S 00, water being 1000. But as it is understood that How does a bottle, filled with 1000 grains of water, become the standard for other liquids'? Suppose a given bulk of water weighs 1000 grains, and the same balk of another fluid 1600 grains, what would be the specific gravity oTFthe latter J 12* Density of Fbiida. 138 SPECIFIC GK^VITT. water is tte standard of comparison, the specific gravities of bodies are expressed merely by the numbers signifying ^ their relation to this standard. Thus, the specific gravity of lead is 11, that is, it is 11 times as heavy as water, bulfc for bulk; while the specific gravity of ether is 750, that is, a given bulk of ether wiU weigh 750 grains,, ounces, or pounds, while the same bulk of water weighs 1000 grains, ounces, or pounds. {See Specific Chavity 4n Na,twral Philosophy.) DENBITI OP BOME LiaUIDS AT 32 DEGREES FAHRENHEIT. Distilled water, . . 1.000 Sulphuric acid, . 1.848 Mercury, . . . . 13.598 " diluted, . 1.21S Milk, .... 1.030 Sea water, . . . 1.026 Oil, linseed, . . . 0.953 (( 1.060 " poppy. • • , 0.929 Alcohol, absolute. 0.793 " olive, . . . . 0.915 Sulphuret of carbon, 1.272 " turpentine, . . '0.872 Sulphuric ether, . 0.716 240. Specific gravitt of gases. — To deterruine accurately the specific gravity of the gases, is an operation of great deli- cacy, and requires not only very nice apparatus, but much experience. The method by which it is done is, however, easily explained, and will be readily understood. We have already said that atmospheiic air is the standard of comparison for the gases. In the first place, therefore, it is necessary to ascertain the weight of a given volume of air. This is done by weighing, very accurately, a light glass vessel furnished with a good stop-cock, when full of air, or in its ordi- nary state. Then, having withdrawn the air by means of an air-pump, and closed the stop-cock, the vessel is again weighed, and the difference vsdll show the weight of air which the vessel contained. On making this experiment, it is found that 100 cubic inches of air weigh 30.5 grains, and by tlie same method, the weight of a given portion of any elastic fluid may be ascer- tained. In all these experiments, it is underetood that the thermometer stands at 60 degrees, and the barometer at 30 degrees. Suppose, then, that the glass globe, a, Fig. 65, is of sufficient capacity to contain 100 cubic inches of air weighing 30.5 grains, and it is found, on filling it with oxygen, that the same quan- How is the specific gravity of a gas ascertained 1 What is the weight of 100 cvbic incties of common air? Suppose it is found that lOO^cubic inches of oxygen gas weighs 34 grains, how is its specific gravity found t DESSny 0¥ THE GASES. 139 tity of this gas weighs 34 grains. Then to find pio. 65. the specific gravity of the latter gas we say, "as the weight of the air is to that op the oxygen, so is unity, or the specific gravity of the atmosphere to the specific gravity of oxygen^ Thus, 30.5 : 34 :: 1=1.1147, gives 1.1147 for the specific gravity of oxygen ^as. But since it is inconvenient in practice to ex- periment on just 100 cubic inches of gas, the graduated vessel, "6, has been jnvented, to show at once what quantity of gas in cubic inches is weighed in the globe, a. , The globe being first exhausted of air, and its stop-cock closed, is the,n connected with the re- ceiver, 6, contMuing the gas, and both cocks being opened, the gas passes from the receiver to the ^bbe. The receiver being open at the bottom, and set over water, or mercury, the rise of the fluid will show the quantity of gas which passes into the globe, and on weighing the globe, both before and after connecting it with the re- Graduateei jar. ceiyer, the difierence wiU show the weight of the air thus transferred. DENEITT OF SOME OF THE OABES. Atmospheric Mr, Oapbonic acid, . Carbonic oxide. Hydrogen,^ . . Nitrogen, . . Sulphurous gas, 1.000 1.527 0.972 0.069 0.972 2.222 Chlorine, .... 2.500 Ammonia, .... 0.590 Cyanogen, .... 1,805 Nitrous oxide, . . . 1.527 Oxygen, 1.111 Sulphureted hydrogen, 1.180 Note. — ^It will be observed in the above table, that instead of making the weight of 100 cubic inches of atmospheric air the standard of compari- son, air.is taken at 1,000, (in the same manner as water is for solids,) and with this as a unit, the other elastic fluids are compared. This is, no doubt, for common purposes, the easiest and best way. Explain Fig. 65, aud siiow the design of each vessel, Bfid the maimer of using them. 140 NOMENCtATUKE. CHAPTER XII. NOMENCLATUHE. 241. The nomenclature of Chemistry, now universally em- ployed, was invented by the French chemists about l'i'84. Before jthat period, the names of chemical substances were en- tirely arbitrary, that is, each substance had an independent name, the signification of which had nothing to do with its composition, or often gave an erroneous idea concerning it. Thus, solution of muriate of lime was , called liquid shell, and afterward oil of lime. Liquid ammonia was called'iojie spirit, and sulphuric acid was called oil of. vitriol. It is true, at that time, the substances known to chemists were few in number, when compared with the immense list of the present day. But even then, their number was such as to make it difficult for the memory to retain them, and at the same time to remember their origin or composition, when this was known. At present, were the substances mentioned in any chemical book, merely desig- nated by arbitrary names, or names inexpressive of their com- position, the student; would necessarily spend more time in learning and remembering them, than is now reqoiired to obtain a knowledge of the whole science of Chemistry. The general diffiision of chemical knowledge, therefore, is in a great measure owing to the present nomenclature — its perfect simplicity, its copiousness of meaning, and the ease with which it is learned and retained. 242. Each term designates the coMPOsiTiON.^Each term in this nomenclature designates the composition of the com- pound substance to which it is applied; and as the simple sub- stances are comparatively few, the composition of most chemical substances are known only by these names. 243. -Names op the acids derived from their bases. — The names of the acids are derived from those of their bases, that is, from the names of the substances to which oxygen unites in such proportions as to form acids. Thus,' sulphur is When was cliriniCal. nomenclature invented, and by whom ? Before this inven- tion, how were phemical substances designated ? What is said concerninflf improper names before this invention 7 At present, were the substances icnown to chemists designated only by arbitrary names, wliat would be the consequence to the learnerl What effect iias this nomenclature had on the diffusion of chemical knowledge? By this nomenclature what do the names of the substances designate J From what are the names of the acids derived 7 NOMENCLATURE. 141 the base of sulphuric acid, and carbon is the base of carbonic acid. Some of these bases unite with several proportions of oxygen, and form acids of diflferent degrees of strength. These proportions are designated by the different .terminations of the name of the acid, the smaller proportion being signified by ous, and the larger by ic. Thus, sulphurozts and sulphuric, and nitrons and nitric acids, mean that these acids contain single and double proportions of oxygen. The salts, that is, the com- pounds which the acids form with alkaUes, earths, and metallic oxides, also indicate by their names the substances they con- tain. Thus, the salts ending in He, consist of a base, united to an acid, ending in ous ; and a salt, ending in ate, contains an acid ending in ic. Sulphiie and phosphite of potash are formed of potash and sulphurott* and phoSphoroas acids, while sulphate and phosphate of potash denote compounds of sulphunc a,nd phosphoric acids,, united to the same base. The names of all the salts, of which there are nearly 2,000, denote their compo- sition in the same manner, and thus we know the ingredients of their compositions by merely. seeing their names. The ter- mination 'uret, denotes the union of simple non-metallic bodies with a metal, a metallic oxide, or with each other. Thus, sulph«r«< and carbwre/, or sulphide and carbide of iron, indicate a combination between sulphur, or carbon, with iron. As oxy- gen combines with several of the metals, in different proportions, but" not always sufficient in quantity to form adds, the com- pounds so formed, though derived from the same metal, differ from each other. These compounds are called oxides, and are distinguished from each other by the Greek derivatives, prot, deut, trit, and per. Protoxide signifies the first degree of oxidation; deutoxiie, the second; iriioxide, the third; and peroxide, the highest. If it is a compound of one atom of acid and one of alkali, the generic name is employed, as carbonate of potash. But if two or more atoms of the acid be combined with the same base, a numeral is prefixed to indicate its compo- sition in this respect. Thus, when the acid is in two propor- tions, or there are two atoms of acid to one of potash, it is What is the base of sulphuric -acid 1 What is the base of carbonic acid 1 By what termination in the word is a wealt acid designated 1 By what termination is the strong acid indicated! What are the compounds called which the acids form with different bases 1 If an acid ends in ous, what is the termination of the salt of which it composes a parH If the acid ends in ic, how does the salt endl How will you know the composition of a salt by merely hearing its namel What does the termination uret denotel What is the composition of a carburet of sulphurl What are oxides 1 By what terms are the different oxides denoted 1 What is a deutoxide t What is a /riVoxide 1 What is aperoxide t 142 TABLE OF NAMES AND 'fllElE COMPOUNDS. called 5i-carbonate of potash. The three Salts of oxalic acid and potash are called the oxalate, fiiwoxalate, and g'Madwxalate of potash ; the first consisting of one atom of each, the second of two atoms of acid to one of potash, and the third of four atoms of acid to one of potash. 244. When oxygen unites in more than two proportions with any base, the prefix hypo is'used to denote a less degree (tf oxy- genation than is indicated by ous. Thus, Ay/jpsulphuroul- acid contains less oxygen than sulphurous, and hyposulphuric less than sulphuric. Oxy denotes a dose of oxygen more than is indiaated by ic ; thus, oxycUonc acid is stronger than chloric acid. ■ Ter denotes 3 equivalents as terchloride. The terms sub, under, and super, above, are used with re- spect to the salts. When the components neutralize each other, it is a neutral salt; if the acid prevails, it is a super-ssiK; if the alkali, it is a «M6-saIt ; but these terms are now obsolete; Ses- gui, one and a half, is used' when 'elements combine in the pro- portions of one and a half tci one, or as three to two. 245. Examples. — The following examples will show how the numeral prefixes are used : Triphosphuret of copper 1 eq. phosphorus +3 eq. copper. Dinoxide' of copper 1 eq. oxygen +2 eq. copper. Subsesquiphosphuret cop. 1 eq. phosphorus 4-lTt-eq. copper. Protoxide of copper 1 eq. oxygen -f- 1 eq. copper. Susquioxide of copper l-J eq. oxygen -f- 1 eq. copper. Binoxide manganese 'B eq. oxygen + 1 eq. manga. Teriodide of nitrogen 3 eq. iodine + 1 eq. nitrog, Quadrachloride nitrogen 4 eq. chlorine + 1 eq. nitrog. TABLE OF NAMES AND THEIK COMPOUNDS. The following table shows at a view the names of the com- pounds, which some of the principal elements form, when com- bined with other substances. Names. Compoundi. Phosphorus fonns phosphides. Carbon " carbides. Nitrogen " nitrides. Hydrogen " hydrides. Cyanogen " cyanides. What is said of supers^aXta and aubtiaJtst Nunefl. Compounib. Oxygen brms oxides. Chlorine (( chlorides. Bromine <»/' bromides. Iodine (1 iodides. Fluorine t< fluorides. Sulphur (( sulphides. CHEMICAL STMBOLB. 143 It will be observed that the former names of the sulphides, phosphides, and carbides, were sulphurefs, phosphurets, and carburets. CHEMICAL STHBOLS. 246. The impracticability, in many ca^es, of contriving con- venient names, expressive of the constitution of chemical com- pounds, especially of minerals, suggested the employment of symbols, as an abbreviated mode of denoting the composition of bodies. It was thought, the names of elementary sul^tances, instead of being written at full length, might often be more conveniently indicated by the fct letter of their names ; and that the comlgnation of elements with each other might be ex- pressed by placing together, in some way agreed on, the letters which represent them. The advantage of such a symbolic lan- guage was felt so strongly by Berzelius, that he, some years ago, contrived a set of symbols, consisting of the initials of the Latin names of the elements, which he has since used exten- sively in has writings ; and other eminent chemists, as well as mineralogists, believing symbols to be useful, adopted those which Berzelius had proposed. The consequence is, that symbolic ex- pressions, called chemical formula, are now so much resorted to^ and so identified with the language of chemistry, that essays of great value are, in a measure, sealed books to those who can not read symbols. It is, therefore, important, that those who are to make chemistry an object of science, or business, should not be unacquainted with these signs. The following table in- cludes the symbols of all elementsfry bodies, according to Gra- ham's last edition. TABLE OF CHEMICAL ETHBOLB. (Those in italics are rare, or newly discovered.) Nvoes of the elemenu. I'. Aluminum, . . . 2. Antimony, (Stilbium,) 3. Aridinm, 4. Arsenio, ^. 5. Barium, 6. Bismuth, 7. Boron, . 8. Bromine, 9. Cadmium, Names of the elements. Symbols 10. Calcium, Ca. 11. Carbon, ...... C. 12. Cerium, .- . . . . Ce. 13. Chlorine, CL 14. Chromium, .... Cr. 15. Cobalt, Co. 16. Copper, (Cuprum,) . . Cu. 17. Didymium, . . . . D. 18. Donarium, Do. What are carbonate and Wcarbonate of potash? Wha^ is a ponderable bodyl What is a simple body 1 What is the difference between a simple and an elementary body 1 When do chemists call a body simple 1 What ore the uses of chemical eym- bols t Who invented these symboUs 1 144 CHEMICAL SYMBOLS. Natnea of the elements. 19. Erbium, . . 20. Flilorine, . . SI. Glucinum, . . 22. Gold, (Ava-um,) 23. Hydrogen, . . 24. nmerium, . . 25. Iodine, . . . 26. IritJium, . . . 27. Iron, (Feri-um,) 28. Latlninium, 29. Lead, (Plumbum,) 30. Lithium, 31. IMagnesium, 33. Manganese, Symbols. . E. . F. . G. . Au. . H, . U. . I. . Ir. . Fe. . La. . PL , Li. . Mg. . Mn. Names of the elements.. Symbol!. p. PI. K. E. Ru. 43. Pliosphorus, . . , 44. Platinum, . . . 45. Potassium, (Kalium,) 46. Rhodium, . . . 47. Ruthenium, . . , 48. Selenium, . . . , . . Se. 49. Silicon, ....... Si. 50. Silver, (Argentum,) . . Ag. 51. Soda, (Natron,) . . .' Na. 52. Strontium, ..... Sr. 53. Sulphur, ..... S. 54. Tantalum, (Columbium,) Ta. 55. Tellurium, . . . . Te. 56. Terbium,. Tb. 57. Thorium, ..... Th. 58. Tin, (Sfannum,) . . . Sn. 59. Titanium, . . . . . Ti. 60. Tungsten, (Wolfram,) . W. 61. Uranium, ..... TJ. 62. Vanadium, .... V. 63. Yttrium, T. 64. Zino, Zn. 65. Zirconium, Zr. 33. Mercury, (Hydrargyrum,) Hg. 34. Molybdenum, .... Mo. 35. Nicliel Ni." 36. Niobium, . . . . . No. 37. Norium, Nr. 38. Nitrogen, N. 39. Osraiunj, ..... O. 40. Oxygen, ..... O. 41. Palladium, Pd. 42. Pelopium, Pe. Note. — ^In some cases, the symbols represent the Latin, instead, of the common names of the equivalents, as Natron, meaning soda. In such cases the terms are placed in brackets. 247. About sYMBOLS.^Sir Thomas Brande has invented, and employs, symbols differing in several respects from those of Berzelius above given ; so that those who consult his works, and those of some othef writers, will have to learn a new series of characters, to signify the same elements. Those of Berzelius are, however, employed by most authors who have adopted the symbolic system of chemical writing, both in this country and Europe. To those students, however, who intend only to ob- tain a general knowledge of chemistry, by going once or twice through a manual, these signs can not be considered of primary importance. When -formulae; of considerable length and com- plexity are indicated by these signs, the student will, at first, find himself at a loss to comprehend them, and will, every mo- ment, have to consult the table to understand what he sees. We have, therefore, in kindness to the student, thought best not to adopt them fully ; at the same time, giving such ex- planations as the subject seems to require, so that those who desire it can becoilie masters of the whole matter. 248. EXPEANATION OV CHEMICAL SYMBOLS. Thcse sigDS CHEMICAL SYMBOLS. 145 ' are intended to represent the chemical equivalents of the ele- ments. Thus, the letters H. I. and Ba. stand for one equivalent of hydrogen, iodine, and barium ; and 2 H, 3 H, and 4 H, for 2, 3, and 4 equivalents of hydrogen. The formulae for cem- pound bodies are indicated by the elements they contain, and the mode in which they are united. This may be done in sev- eral ways, but the most common method is, to connect together the symbols by the same signs as are used in algebra. Thus, the formula K+0, Ca+0, Ba+0, Mn+0, Fe+O, 2 Fe-|- 3 G, 3 H+N, 2 H+2 C+2 O, N-t-5 O, S+3 O, and H+Cl., denote single equrvalents of potassa, lime, baryta, protoxide of manganese, protoxide of iron, sesquioxide of iron, ammonia, olefiant gas, carbonic acid, nitiic acid, sulphuric acid, and hy- drochloric acid. The formula K+N+6 O, indicates the ele- ments which are contained in an eqviivalent of nitrate of potassa: in order to express, further, that the potassium is combined with only one equivalent of oxygen, the remaining oxygen with the nitrogen, and the potassa with the nitric acid, the symbols are placed thus: {K-f-0)-)-(N-t^5 O,) the brackets containing the symbols of those elements which are supposed to be united. A number placed on the outside of a bracket multiplies the compound within it: thus (K+0)-t-{S-|-3 O) is sulphate of potassa, and (K-|-0)-|-2 (S-f-3 O) is the bisulphate of potassa. All the elements contained in a compound are thus visibly rep- resented, and the chemist is able readily to trace all the modes of combination, and to select that which is most in harmony with the facts and principles of his science. He may, and often does, thereby detect relations which might otherwise have escaped his notice. The above is taken from the last edition of "Graham's Chemistry," and if teachers and students in this country adopt this method, the doctrine of chemical sjrmbols wUl become generally understood and appreciated. Independently, how- ever, of the vexation of learning such a number of signs, we can not perceive the utility of employing them for common pur- poses, though already learned. Thus bisulphate of potash, as seen above, is thus expre^ed, (K+0) + (2 S+3 O.) Now, who does not see that the words themselves can be more quickly written than these signs made? and, when printed, close atten- tion and much practice is required in order to avoid errors in reading them. 249. Isomorphism. — This term comes from the Greek, sig- nifying like form, and is applied to such substances as assume 13 146 CHEMICAL STMBOLS. the same crystalline forms, though composed of different ele- ments, and having the same number of equivalents. Also, the quality of a substance by which it is capable of re- placing another in a compound, wiliiout any alteration of the previous crystalline form of the compound. This new branch of chemical science is particularly illustrated by the arsenic and phosphoric acids. Thus, the neutral phosphate and biphos- phate of soda, have exactly the same crystalline forms as the arseniate, and biarseniate of soda. Each arsoniate has a corre- sponding phosphate, possessed of the same form, possessing the same number of equivalents of acid, alkali, and water of crystal- lization, and differing, in fact, in nothing, except that one series contains arsenic, and the other an equivalent quantity of phos- phorus. * ^ These examples are sufficient to show the meaning and scope of isomorphisnii. Many other cases of the same kind are to be found described by chemical authors. 250. Isomerism. — Thi& term is a Greek compound, and sig- nifies equal parts, and in chemical science is applied to certain compounds, which, though- they have the same elementary equivalents, possess entirely different properties. Such bodies have in general been found, by the progress of discovery,' to agree in the relative proportion of their constituents only, and to differ in the aggi-egate number of the atoms com- posing them, or in the mode of arrangement. of these atoms ; and although new cases -of isomerism are constantly arising, others are removed as they come to admit of explanation. In the abstract. Isomerism is an improbable phenomenon, since a difference in the properties of a compound, without a difference in their composition, would seem to be an effect without a cause. In some of these cases, however, although the relative propor- tions of the compound are identical; the number of atoms of each are different. These are shown by Oil of lemons, . 10 eq. carbon-. " " . . 8 eq. hydrogen. Oil of turpentine, 20 eq. carbon. " " . . 16 eq. hydrogen. Here we see that although the relative proportions of each are thesame, the number of combining atoms differ, and hence the entire difference in the nature of these two bodies. What is the meaning of Isomorphism J What examples are given J What is the meaning of Isomerism % How is this term applied to chemical componnds 1 PART II. CHAPTER XIII. PONDERABLE BODIES. 251. Explanations. — K ponderable body is one which has appreciable weight. A simple body is one which has not been decomposed. These are also called elements, or elementary bodies. It is possible that all the substances now called elementary, may still he in reality compounds, for our knowledge on this subject is entirely negative, that is, all bodies which the art of chemistry has been unable to separate into parts, or to decom- pose, are called simple, in order to distinguish them from known compounds. Before the refinements of chemical analy^s were known, it was believed that nature afforded only four elements, viz., fire, air, earth, and water. Analysis has, however, shown, that fire, or heat, is the result of chemical union ; that air is a compound of nitrogen and oxygen ; that there are many earths, and that water is composed of hydrogen and oxygen. 252. Number of elements. — The number of simple, or ele- mentary substances, as arranged under the head of chemical symbols, now amount to sixty-five. Of these, much the largest proportion are metals, or metalUc bodies, seven or eight of which have been discovered within a few years. Not long since, potash, soda, and many other substances, which the refinements of chemistry have shown to be com- pounds, were supposed to have been elements ; and it is not improbable that some now rated as simple bodies, will prove to be compounds. 253. Transferring the gases. — Before proceeding to de- scribe the properties of the gases, it might be tiiought necessary to detail more particularly than has been done, the modes of confining and transferring them from one vessel to another But it is thought that such directions are better understood by How many elements were formerly supposed to ezist 7 What is said cODCerDing fire, air, earth, and water 1 How many elemeuts are now supposed to exist, and what are they? What ^s said of the probability that some bodies now arranged as elemenls will be found to be compounds 1 148 POSDEPvABLE BODIES. the. student, and mucli more readily followed when given in con- . nection with the particular subjecte or cases to which they im- mediately apply. The method, for instance, of transferring the nitrous oxide from the retort to the gasometer, g,nd from the gasometer to the gas bag, will be best understood if given in connection with an account of the properties of the gas, or im- mediately after it. The- same, it is thought, may be said of confining and transferring the other gases. As several different methods are required, depending on the nature of the gas, its absorption by water, its specific gravity, and other properties, these different modes can be best explained and understood in immediate connection with the description of the peculiar pro- perties of each gas. 254. Definite proportions. — As the doctrine of definite proportions is not only highly interesting as a subject of philos- ophy, but is also intimately connected with chemistry, both as a science and a practical art, we shall attach to' the name of each substance at the head of sections, its equivalent number, so that the reader may at once observe its combining propor- tion. And it is earnestly recommended to the pupil, that he should not only regard this subject as one of great importance in a scientific relation, but also, when viewed in a different light, as one that tends -directly to impress the mind with the most serious conviction that nothing in nature has been left to chance, but that the Altoighty Creator has left a Avitness of Himself, even in the proportions and arrangement of the atoms of matter. Nothing, perhaps, even tl^e sublimest works of na- ture, are more calculated to elicit the wonder and astonishment of a reflecting mind, than the fact that substances combine with each other in exact and definite quantities,-and that these quan- tities or proportions, are the same in relation to the same sub- stance throughout the world, and have heen. so ever since the creation. This discovery may be considered as a new proof, directed expressly to the present age, that the most minute _^ works of what we call nature, do indeed bear the most indubit- able marks of divine agency and design. 255. But while the discovery itself is an evidence of the pro- found philosophy of the present age, the development of its principles, by the constant accession of new ideas, is calculated What is said of the doctrine of definite proportions, in relation to pliilosoplly and cliemistry? In what othpr respects is this subject recommended-to liie particular attention of the pupils What is said of divine agency and desi^i in the minute worlis of nature 1 After all human acquirements, how much do we know of the laws and operations of nature ? INOKGANIC CHEMISTRY. 149 rather to humble the pride of human knowledge, by as constant a conviction, that after all our acquirements, we kuow compara- tively nothing of the laws and opei-ations of nature. The very fact, that the' laws of proportions, now comparatively just knowu to man, have existed ever since the creation of matter, and have been in perpetual exercise all over the universe, without a suv picion of their existence, is of itself a sufficient proof of the almost entire ignorance of man even of the phenomena of na- ture, and a still stronger proof of his ignorance of her laws. And if facts, in themselves so simple, yet so wonderful, and when once known, so obvious, have escaped the observation of man for thousands of years, is it not probable that phenomena are constantly going on before our eyes, which, could we under- stand them, would astonish us still more, and at the same time afford a still stronger conviction of our ignorance, and want of penetration ? These considerations, while they are calculated to humble the pride of human intellect, by showing how little we know of the laws which govern even the ordinary operations of nature, ought, by the conviction of ignorance, to prove an -incentive to constant observation on natural phenomena, that, if possible, we might arrive at the knowledge of their true causes. CHAPTER XIV. ffiOKGABIC CHESUSTKT.-NOIf-METAIIIC SUBSTANCES. OXYGEN. Equivalent, 8. Symbol, O. 256. The name oxygen is derived from two Greek words, and signifies the former or generator of acids, because it enters into the composition of most acid substances, and was for- merly considered the universal and only acidifying principle iii nature. It was discovered by Dr. Priestley, in 1774, and named by him dephlogisticated air. Its specific gravity is 1.11, air being 1. It is a non-conductor of electricity, hke common air. Its What is proved by the fact, that the law of definite proportions, though existing ever since the creation of matter, have, until lately, remained unknown 1 What is saiJ of the probability that wonderfijl phenomena are constantly going on before our eyes 7 What does the term oxygen signity 1 Who discovered this gas 1 What is the speciSc gravity of oxygen gas t 13" 150 OXYGEN. electrical state is always negative, and when suddenly and for- cibly compressed, as in the fire-pump, already described, it emits light and heat. Oxygen may be obtained from many substances. The per- oxides of lead, or manganese, and the nitrate and chlorate of potash, all yield it in abimdance, when merely exposed to a dull red heat. 257. From manganese; — A convenient substance for this purpose is black, or peroxide of manganese, in the state of fine powder. This, when heated in an iron bottle, or gun-barrel, will yield upward of 120 cubic inches of the gas to. an ounce of the oxide. For small experiments, a gun-barrel may be used ; but where considerable quantities are wanted, a wrought-iron bottle, with a neck 18 inches long, is the best instrument. FIG. 66. Oxygen from Manganese, 258. Into such a bottle introduce three or fourpoiinds of the black manganese, in powder, and having placed it in a fiirnace, as shown by Fig. 66, on making the fire, oxygen gas will, in a few minutes, come over in abundance. The neck of the bottle, a, is connected with the glass, or lead tjibe, 6, leading to the gasometer. This vessel is formed of two cylinders, c and d, -placed one above the other, with tubes communicating between them, through which the water passes to fill the lower cylinder, on being poured into the upper one. Two of these tubes reach to the bottom of the lower cylinder, and the other two are stopped with thumb screws. What are the substances from which it can be obtained? What Is the cheapest and most convenient mode ufobtainiiig it t How many cubic inches of this gas will an ounce' bf the blaclt oxide of manganese yield 1 What are the methods described of extricating this gas from manganese? , Describe the method of obtaining oxygen gas by means of an apparatus. Fig. 66. OXYGEN. 151 259. Before the escape of the gas from the retort, the gas- ometei^must, of course, be filled with water. This is done By pouring it into the upper cylinder, the stop-cock, e, being open, for the exit ef the air. NoW, on stopping the communication between the two cylinders, and turning the stop-cock, e, it will be seen that the gas now to be admitted, can not escape by the long tubes from the upper cylinder, since th^r mouths are under Uie water, nor by the others, since they are closed by stop-cocks. The first portions of the gas are impure, and may be let off at e, until the wick of a candle just blown out, takes fire on being held in the current. In these gasometers, there is a glass tube on the outside, to show the quantity of water or gas it contains. The tube by which the gas is admitted, must be curved down from such a height as to prevent the water in the gasometer from flowing back into the retort. As the gas is let in, the water is allowed to escape by a stop-cock, through which the tube passes to admit the gas, this being closed when the gas- ometer is full. The upper cylinder being open, water is poured into this, to increase the pressure on the gas in the lower one. By fixing a tube at e, and opening the stop-cock, and pouring water into the upper cylinder, the gas may be transferred to any place where it is wanted. By fixing a jet-tube and stop- cock to the gas holder, and directing a jet of oxygen through the flame of an alcohol lamp, nearly all the effects of the com- pound blow-pipe may be obtained. 260. Theory. — With respect to the theory of the above process, it is necessary to state, that there are three oxides of manganese, each, of coui-se, containing different proportions of oxygen. These oxides are thus constituted, the combining pro- portion of manganese being 28, and that of oxygen 8. Protoxide manganese, 28, added to oxygen, 8=36. Deutoxide, ... 28, " " 12=:40. Peroxide, .... 28, "j» « 16=44. When the peroxide is exposed to a red heat, it parts with half a proportion of oxygen, that is, 4 parts, the number for oxj'gen being 8, and is therefore reduced to a deutoxide, whose number, it will be observed, is 40. The number for the peroxide being 44, and the loss by a red heat being 4, we obtain 4 In what manner may the effects of the compound blow-pipe bis obtained by this gas, and a spirit lamp 1 How many oxides of man^nese are there, and vhat are the proportions of oxygen in each 1 What proportion of oxygen does the peroxide part withat ared heat? 152 ^ OXYGEN. grains of oxygen for every 44 grains of the oxide, which in hulk is nearly 12 cubic inches, making about 128 cubic inches for each ounce of the oxide. When oxygen is obtained by means of sulphuric acid, thfe theoretical expression is different. In this case the peroxide loses a whole proportion of oxygen, and is thus converted into a protoxide, which then combines with the acid, forming a sul- phate of manganese, which remains in the retort. By tlii& pro- ii'eas, therefore, the peroxide yields 8 grains of oxygen to every 44 grains employed ; but in practice it is found that the &st method is the best and cheapest. 261. It will be observed, that the weight of oxygen for the deutoxide, expressed above, is only 1 2, being a proportion and a half, instead of two proportions of that element. The oxides of lead and iron afford examples of precisely the same kind. These facts were at first supposed to afford exceptions to the law of definite proportions, or rather to the atomic "theory, by which the cause of definite quantities is explained. But it will be remembered, as already stated, that the smallest proportions in which bodies have been found to combine, by weight, are those by which they are represented in numbers. Now the s;nallest proportion in which oxygen has hitherto been known to combine, is in water, this proportion being as 8 to 1. The number, therefore, for oxygen is 8. 262. From red oxide of mercury. — Theingenjous student who has a strong desire to witness the effects of oxygen on various substances of which he bad so often read, may obtain enough for his purpose from several compounds, most of which are easily obtained. In addition to the oxides of lead and man- ganese, and the chlorate of potash, already named, oxygen is readily obtained from the red oxide of mercury, or red precipi- tate. In this compound the affinity which holds the mercury and oxygen together is ^o feeble, that simple exposure to the heat of a lamp suffices to feffect decomposition. The apparatus for this purpose is shown by Fig. 67, where a is a tube of glass, stopped with a cork, through which passes the end of the glass tube, 6, bent as in the figure, so as to open under the receiver, c, which is filled with water, and stands on the shelf of a pneumatic trough. The precipitate being placed To what oxide i^ the peroxide.' reduced by parting witli a portion of its oxygen! What does deutoxide mean 1 Explain the chemical chaiiires which talce place when tlie oxygen is obtained by means of sdlphuric acid. Whftt is said conceriiing^lhe welsht of oxygen for the deutoxide of'manganebe? Descr.be the means of obtaining oxygen from red precipitate and clxloride of potash. 153 in tke tube, for whiot a retort of larger size may be substituted, the heat of the spirit lamp, d, soon extricates the oxygen, which will be seen to rise through the water. By having several such receivei-s filled with water, the student may fill and' remove, one after the other, or by upward pouring transfer the gas to other vessels, only taking cai'e to keep their mouths under the water FIG. 67. Oxygen fTom Red Precipitate. of the cistern during the process. Instead of the red predpitate, the chlorate of potash may be used, which yields very pure oxy- gen. If the chlorate is mixed with one-half its weight of oxide of manganese, it will require less heat than when used alone. Oxygen gas is an invisible transparent fluid, Uke common air, and. has- neither taste nor smell. It is sparingly absorbed by water, 100 cubic inches of which, take up three or four cubic inches of the gas. 263. Universal affinity of oxYGEN.-^Oxygen has the most universal afiBnity of any known- substance, tbere being not one of the simple substances with which it "may not be made to combine. It unites with all the metdls, forming a very exten- sive class of compounds, known under the name of oxides. What is said of the taste and emell of oxygen 1 In what proportion in this gas ab- sorbed by water 1 What is said concerning the extensive affinity of oxygen J 154 0X1- GEN. With some of them itioombmes in, such proportions as to form adds. Such is the case with arsenic, molybdena, and others. With the simple combustibles, sulphur,, carbon, PHOSPHORUS. 209 is combined with auimal substances, in considerable quantities, and is occasionally found in minerals. 349. How OBTAINED. — It IS obtained from bones by the follow- ing process : In the first place, the bones are calcined, or bumed in an open fire, and then pulverized, and digested for two or three days with half their weight of sulphuric acid, to which water is occasionally added. This solution is then mixed with twice its bulk of hot water, and the liquid separated by straining through a cloth. By this process, the J)ones, which are com- posed of phosphoric acid and lime, are decomposed, and two new salts, viz., the sulphate of lime, and the biphosphate of lime, are formed. The sulphate of hme is insoluble in water, and therefore the filtrated solution contains only the biphos- phate, which is soluble. Thus, the bones, which are a phos- phate of lime, mixed vrith animal matter, are first deprived of this matter by burning, and then converted, in part, into the biphosphate by the sidphuric acid. We have, then, in this stage of the process, a solution of the biphosphate, or acidulous phosphate of lime in water. This solution is then evaporated to the thipkness of syrup, mixed with one-fourth of its weight of charcoal in powder, and distilled with a strong heat, in an earthen retort. The charcoal combines with the oxygen of the biphosphate, which, being thus decomposed, the phosphorus distills over, and is obtained in a vessel of water, into which the mouth of the retort is placed. The apparatus for this pur- pose is represented by fig. 92, and will be understood by mere inspection. The retort a is of stone, or clay, so as to bear a considerable degree of heat. The tube 6, is of cop- per, and passing air-tight through the cork, dips only a few hnes into the water in the ■ bottle. This is a necessary precaution, since, if by any accident, ihe retort should be suddenly cooled, only a small quantity of water, and not enough to reach the hot re- tort, could be absorbed, other- FI6. 92. Making tf Phosphorus. By what process is phosphorus obtained 1 Describe the different chemical chaoEes which takes place in the process of its preparation. 18* 210 PHOSPHORUS. wise, sad accidents might occur, since only a few drops of water, converted into steam, would burst the retort, and throw its contents in all directions. The small tube c, open at both ends, is for the purpose of allowing the gasses, which come over during the process to escape. The heat, in the furnace, is to be gradually increased, when the phosphorus, which comes over in a liquid form, will be condensed in th^ water, and in the neck of the retort. Large quantities of this article are manu- factured and employed in making friction matches, and for other purposes. It is a brilliant experiment, since, during the pro- cess, sulphureted hydrogen escapes, which takes fire as it reaches the air. It also requires much care and experience, otherwise it is not without danger. 350. Propeetiks. — Phosphorus, thus obtained, is of a yel- lowish, or flesh color, but may be made colorless and transpa- rent by redistillation. This substance is exceedingly inflammable, so that at com- mon temperatures, it is necessary to preserve it under water, in well stopped bottles. It may be set on fire by slight fiiction, or even by the heat of the hand. It is insoluble in *ater, but is soluble in ether, or oils, to which it comjnunicates the pro- perty of shining in the dark. ' ' Put a piece of phosphorus into a vial half filled with olive oil, then keeping the thumb on the mouth of the vial, warm the bottom, shaking it now and then, until the phosphorus is melted. This forms liquid phosphorus, and a vial thus pre- pared may be occasionally useful to show the hour of the night by a watch. All that is necessary for this purpose is to hold the vial in the hand for a few minutes, until it becomes warm, then. take out the cork, and the union of the oxygen of the air with the phosphorus will evolve sufficient light to see the hour. That the hght is owing to the combination of oxygen with the phosphorus, or to its slow combustion, in the above instance, is proved by the fact, that phosphorus may be melted and sub- limed in pure nitrogen, without the least appearance of light. Its combustion in oxygen gas is exceedingly vivid, and afibrds a striking and splendid experiment for a public lecture room. When taken into the stomach, phosphorus proves a virulent and deadly poison ; though in minute doses, it has been used as a medicine, when dissolved in ether. What is said of the inflammability of phosphorus 1 In what manner must it be preserved from the air t How is liquid phosphorus prepared % For \ybat purpose may a vial of this mixture be useful t How is it proved that the luminous appear- ance of phosphorus is owing to the absorption of oxygen? What is said of the pois- onous quality of this gas when talcen into the stomach ) PUOSFUOliUS ACID. 211 PHOSPHORUS AND OXYGEN. PHOSPUOmO ACID. Equivalent, 72. Symbol, PO5. 1 eq. Phosphorus, 32+5 eq. Oxygen, 40. 351. Phosphorus, as above stated, unites with oxygen with great rapidity, and affords an instance of intense chemical action, attended with the most brilliant phenomena. During this combustion, copious white vapors are produced, which fall to the bottom of the vessel in which the experiment is made, like flakes of snow. This white vapor is the dry, or anhydrous phosphoric acid. K exposed to the air, it soon attracts moist- ure in sufficient quantity to dissolve it, and thus becomes liquid phosphoric acid. This acid may also be formed by the action of nitric acid on phosphorus. The union is made by dropping pieces of phos- . phorus into the strong acid. The phosphorus absorbs one pro- portion of oxygen from the acid, thus converting this acid into the deutoxide of nitrogen, or nitrous gas, which escapes in immense volumes during the process. The phosphorus is thus converted into phosphoric acid, which is obtained in the solid form by evaporating the solution to dryness. Phosphoric acid unites vrith water in aU proportions, and produces a small degree of heat during the solution. Its taste is intensely sour, but it is not corrosive. When heated in con- tact with charcoal, the latter absorbs its oxygen, and the phos- phoric acid is converted into phosphorus. This acid combines with various bases, and forms a class of compounds called phosphates. Its composition is 1 proportion of phosphorus, 16 2 " " oxygen, 16 Consequently its equivalent' is 32 PHOSPHORUS ACID. Equivalent, 56. Symbol, PO3. 1 eq. Phosphorus, 32+3 eq. Oxygen, 24. 352. This acid is obtained by exposing pieces of phospho- rus to the open air, in consequence of which it spontaneously absorbs oxygen, and, undergoes a slow combustion. What is said of the union ofphoephorus and oxysen 1 In what form does the dry phosplioric acirf appear 1 Why does this acid become liquid on eiposufe to the air t 212 BORON. K two or three sticks of phosphorus bo thus exposed in a glass funnel, set into the molith of an empty bottle, the acid will be formed, and by attracting moisture from the air, will be dissolved, and pass down into the bottle, where at first may bo found a quantity of liquid phosphorous acid. This acid com- bines with different bases, and forms salts, which are called phosphites. Phosphorus acid, when exposed for some time to the air, absorbs another proportion of oxygen, and is then con- verted into phosphoric acid. Indeed, the acid formed by this method is probably always mixed with the phosphoric" acid. There are several other compounds of phosphorus and oxy- gen, but these are the most important. The phosphates' will be described in their proper place. - Equivalent, 11. Syrohol, B. 356. There is a solid substance, resembling alum in appear- ance, which is used in medicine and the arts, under the name of borax. From borax there is extracted an acid, called the horacic acid. When boracic acid is heated in contact with the metal called potassiuln, the metal, having a strong affinity for oxygen, deprives the acid of that principle, and thus its base, called boron, is set free. This, so far as is known, is an ele- ment. Boron is insoluble in water, alcohol, or oil. It may be exposed to the strongest heat in a close vessel, without change, but when heated to about 600 degrees in the bpeti air, it takes fire, burns vividly, and by the absorption of oxygen, is again converted into boracic acid. 358. Boracic acid. — This is the only known compound of boron and oxygen. It is a natural product, occasionally found in springs, and also in several salts, of which borax, or the borate of soda, is the principal. The acid may be obtained from the, borate of soda, by dis- solving that substance in hot water, and then adding sulphuric acid until the solution becomes sour. Sulphuric acid combines with the sod^, forming sulphate of soda, or Glauber's salt, while the boracic acid thus set free, is formed, when the water cools, By what other method may this acid be formed t When phosphorus is thrown into nitric acid, wliat are the chemical clianges which ensue? In what manner does charcoal convert jihosphoric acid into phosphoruB? What is the composition, and what the combining number -of this acid? How is phosphoraus acid obtained 7 What are the salts called which this acid forms with the different bases 1 How is bnron obtninedT Is boron a compound, or an elementary bodyl What are the properties "of boron 1 Whzt is boracic acid 1 How may boracic ^cidbe obtained 1 What is the common name for borate of soda ? OXMURIATIC ACID. 213 in small crystals. It is not readily soluble in water, but alco- hol dissolves it freely, which being set on fire, burns with a beautiful green flame. This green flame is a good test of the presence of, boracic acid in any composition. This acid is composed of Boron, 1 equivalent, 11 Oxygen, 6 " 48 The combining pro. of this acid is therefore 69 CHLORINE. Equivalent, 36. Symbol, O. OZUnRIAXIC ACID. 355. This highly. important and useful gas is obtained by the action of muriatic acid on black, or peroxide of manganese. The most convenient mode of preparing it is by mixing strong muriatio acid, contained in a letort, with half its w;eight of the black oxide of manganese in Bne powder, and then applying a gentle heat. The gas may he' received in glass bottles filled with water, and inverted in the pneumatic cistern, in the usual way. The water should be warmed, to prevent absorption. 356. Mr. Fownes' method. — The following are Mr. Fownes' directions for the preparation of chlorine. Fig. 93, a large glass flask, a, containing a quantity of common salt, is fitted with a cork and safety tube, b, with a bent tube, c, the latter passing through a short tube into a wide necked bottle, con- taining a little water, into which the open tube dips. A second bent tube, d, passes by another hole in the cork, into the bottle, e, but only just through the cork. This tube passes into another bottle containing distilled water. The tubes are of glass, and the joints through the cork made tight by bees-wax. Action. — Having thus prepared the apparatus, pour through the funnel, b, sulphuric acid, about equal in weight to the salt, when the gas will be developed, which at first will be absorbed by the water in the bottle e, but when this is satm-ated, it will pass in the other bottle by the tube, d,m a, pure state. When the action ceases, an additional quantity of gas may be obtained by the application of heat, by means of charcoal placed iu the furnace under the flask. As much heat is ^giv»n out by the What is the best test for the preseuce of boracic acid 1 What are the elements of boracic acid, and what is its combining number ( How is chlorine obtained t What are the two processes, described, of obtaining it 7 Wilat is said of the color and suf- focating effects of this gas? 214 OXMUBIATIC AClD. condensation ef tlie gas, the condensing bottle may be sur- rounded with cold water, being placed in a vessel for this purpose. 857. Observation. — It will be observed that this method differs materially from that first described, in which the articles FIG. 93. \^ SSanuJactwn of Chlorine. employed are muriatic acid and oxide of manganese. The result, however, is exactly the same, the chlorine being in the first case the product of the mutual action of the manganese and muriatic acid, and in the second, by thei action of the sulphuric acid on the muriate of soda,^ or common salt. 358. Properties. — This gas is of a yellowish green color, the name, chlorine, in Greels;, signifying green. It has an astringent taste, and is so exceedingly suffocating, that a bubble or two let loose m a room, will excite coughing and a sense of strangulation. Cold water, recently boiled, wiU absorb twice its volume of chloVine, which it gives out again on being heated. OXMUMATIC Acm. 215 The specific gravity of this gas is 2.5, so that it is more than twice as heavy as atmospheric air. 100 cubic inches weigh 76.25 grains, while the same quantity of common air weighs only 30.5 grains. Chlorine, in solution with water, was formerly called oxy- muriatic acid, from the opinion that it was composed of mu- riatic acid and oxygen. But, according to the logic of chemis- try, it is now universally considered a simple body, having never been decomposed, though repeatedly submitted to the most active decomposing agents tnown to chemists. Sir H. Davy submitted it to the most powerful effects of galvanism, and to charcoal heated to whiteness, without decomposition, and without separating the least trace of oxygen from it. Hence, according to the present state of knowledge, it is an elementary body. Chlorine is a supporter of combustion. When a lighted taper is plunged into this gas, it bums with a small red flame, emitting a large quantity of smoke. Phosphorus takes fire in it spontaneously, and so do several of the metals. Fill a deep bottle, or large tube, with this gas, and set it up- right, with lie mouth covered by a plate of glass. Have some antimony prepared, by "being pounded in a mortar ; then slide off the cover and pour in the metal. It will take fire before it Teaches the bottom, and afford a beautiful shower of white flame. This affords an elegant and striking experiment. The metals, tin, zinc, copper, arsenic, and even gold, when in the state of powder, or thin leaves, will be inflamed in the same manner. Chlorine has a very strong attraction for hydrogen, but it is through the mysterious influence of light that the com- bination between the two substances seems spontaneously to be effected. Thus, when a mixture of these two gases is kept in the dark, no combination ensues, but if exposed to the direct light of the sun, they combine suddenly, and with a violent detonation. This sometimes happens wiliout the sun's light. This gas, though formerly called an acid, does not appear ,to possess any acid properties. It is not sowr to the taste, nor What is its specific gravity 1 Wbat was the former name of this gas 7 Does this gas cootain any oxygen 1 What is said of the experiments of Sir H. Davy on chlo- rine ? Is this an elementary, or a compound body 1 Is chlorine a supporter of com- bustion t What substances take fire in this ga-s spontaneously 1 In what manner may a shower of flame be made by this gas and a metall What is said of the union between this gas and hydrogen 1 Does chlorine contain any of the properties of an acid) 210 MURIATIC ACID. does it redden vegetable blue colors, properties nearly universal in tbe acids. But tie most important property of chlorine, is its bleaching power, all vegetable and animal colors being discharged by ite action. For this purpose, it is combined with quicklime, form- ing chloride of lime, or bleaching powder, an article very exten- sively employed at the present time, and which will be de- scribed, and its properties examined, in its proper place. . Another very important property of chlM-ine is its disinfect- ing power, any infectious or disagreeable odor being almost in- stantly destroyed by it. For this^ purpose, the chloride of lime is also chiefly employed. The compounds' of chlorine which are not acid, are called cAfon^es, or chlorurets. When chlorine, united to oxygen, combines with a base, and forms a salt, it is called a chlorate. These were formerly called hypetoxyiimfi- ates. They possess no bleaching properties. CHLORINE AND HYDROGEN. HYDROCHLORIC ACID. Equivalent, 37. Symbol, CI. H. 1 eq. Chlorine, 36-1-1 eq. Hydrpgen 1. MDRIATIC ACID. 359. We have just seen that chlorine has a strong affinity for hydrogen, but that no union takes place between them, without the influence of light. When the light is entirely excluded, a mixture of these gases remains without change. When the mixture is made in a glass vessel, and exposed to the light of day in the shade, the gases, if of equal volumes, slowly combine, and form muriatic acid gas. But when the mixture is exposed to the direct rays of the sufi, the union is sudden, and attended by an explosion. This combination does not change the volume of the original mixture, but the properties of the two gases are greatly changed. If the vessel in whiclT the experiment has been made is un- stopped under T^ater, the fluid will in a few moments entirely absorb its contents, alnd fill the vessel in its place, while the two What is the most important property of clilorine ? What does chlorine form, when combined with quicklime 1 What other important and useful property has thisgasl What are the compounds of chlorine, which are not acid, called ? When a mixture of hydrogen and chlorine is kept in the dark, what change takes place? When placed in the shade, what is the effect t When the mixture is placed in the sun, what effect is produced ? What are the changes productd on these gases by this combina- tion 1 What is the name of the new gas 1 MURIATIC ACID. 217 gases, before combination, were absorbed by water only in small proportions. The peculiar odor of chlorine, and its prompt bleaching propert}'^, are also destroyed, and other change of properties will become apparent on further examination. The compound formed by the union of chlorine and hydro- gen is called hydrochloric add. This gas is composed by weight of 1 equivalent of chlorine, 36 1 " " hydrogen, 1 Combining weight of hydrochloric aqjd gas, 37 360. The production of muriatic acid l^the combination of its elements, is designed to prove its constitution, and combin- ing proportions. This acid is, however, much more readily pre- pared by the action of sulphuric acid on common salt. If the salt be pulverized and nwxed with an equal weight of the acid, and then the heat of a lamp appUed, muriatic acid gas will be disengaged. , But it must not be received over water, which will absorb several himdred times its own bulk of this gas. Muriatic acid gas is a transparent, elastic fluid, of a very pun- gent smell, and intensely acid taste. Its attraction for water is so great, that when it escapes in the open air, even,in the dry- est season, it instantly forms a white cJoud, in consequence of combining with the moisture of the atmosphere. , Water, at the temperature of 40 degrees, absorbs 480 times its bulk of this gas, and the solution is known under the name of muriatic acid, or smrU of sea salt, and is largely employed for chemical and manumcturing purposes. This acid is prepared, in the large way, by extricating the gas from sea salt, by sulphuric acid, as above described, and then passing a current of it into water, as long as any is ab- sorbed. It forms, with the different bases, a class of salts, called muriates, or hydrochlorates. When this gas, in a pure state, is submit^ to the pressure of 40 atmospheres, that is, 600 pounds to the square inch, it is condensed into a liquid. what is Gaid of the absorption by water of cblorin^ and hydrogen, and also of muriatic acid ;;as ? What is the composition of muriatic acid gas. and what is ita combining number? How is this gas most readily and conTeniently prepared? Why does muriatic acid gas form a white cloud in the open air ? Bow many times its own built of this gas will water absorb? Under what name is this solation of gas in water Icnown? How is the muriaticacid of commerce prepare^? 19 218 CHLORIDE OF SPLPHUR. CHLORINE AND OXYGEN. \ 361. There are four compounds of oHorine and oxygen, formed by the union of as many diflferent propoi-tions of the oxygen to the same proportion of chlorine. These compounds are known only to chemists, and with' the exception, perhaps, of chloric acid, possess no value in the arts. They are all formed by the action of an acid on the chlorate of potash, or the chlorate of barytes. The chief interest which these sub- stances possess, in a chemical relation, is their strict conformity to the laws of definite and multiple proportions. Their names and constituents ai&as follows : Pi-<*oxide orchlorine, 36 chlorine4- 8 oxygen. iPeroxide of chlorine, 36 " +32 " Chloric acid, . . 36 " +40 " Perchloric acid, . 36 " +56 " Thus, the first is composed of 1 proportion of ohloi'ine com- bined to 1 of oxygen. The second, 1 of chlorine and 4 of oxy- gen. The third, 1 of chlorine and 5 of oxygen. The fourth, 1 of chlorine and 7 of oxygen. The equivalent numbers, therefore, for the first, is 36 + 8 = 44 ; the second, 36+32=68; for the thu-d, 86+40=76; and for the fourth, 36 + 56=92. CHLORINE AND SULTHUR. CHLORIDE. OF BULPHUBl, . Equivalent, 52. SymbqL S. CI. ^ 1 eq. Sulphur, 16+1 e(^'i»lorine,"3&. ^^^ ' . The combination of chlorme with sulphur forms a curious compound, called chloride, or cMoruret of sulphur. The method of forming this combination is as follows : 362. Prepabation. — The materials for making chlorine, it- will be remembered, are black oxide of manganese, and muriatic acid. These being. placed in the flask, a, Kg. 94, and the heat of a lamp applied, the chloi-ine will rise, and pass down the tube into the globe, b, where any water it contains is condensed. Rising from 6, the gas passes through the tube, c, containing Under what pressure is this gas condensed into a liquid t How many compounds nf chlorine and oxygen are known 1 Do the compounds of ctlloriue al|^ oxygen pos- sess any value iu the arts'! In what relation are the compounds oi chlorme and oxygen intere&tingi » CHLORIDE OF SULPHUR. 219 cHoride of calcium, by the absorption of wMck it will be de- prived of all moisture, so that it will arrive at e, which contains the sulphur, in a perfectly dry state. The globe, e, must be gently heated by means of a spirit lamp, so as to melt the sulphur. FIG. 91. Preparaium qf^ Chloride of Sulphur. ♦■■V By these means, the sulphur and chloiine are made to com- bine and pass in the gaseous state into the globe,/, which being kept cold by means of a stream of water from the cistern, h, the compound is condensed into the liquid form. The quan- tity of water is regulated by means of the stop-cock, i, affixed to the tube, k, and falls from the globe into the dish, o. The superflnous gas passes off into the open air, by the waste pipe, I. By this method small quantities *>f the chloruret of sulphur may be formed. , • 363. -PKOjEpTiBS.-^ghlonfr^ of sulfur is a yellowish red fluid, of a peculiar andaisagreeable odOr, whose boiling point is 346 degrees. ""It sinks iiygatOT, by which, in a short time, it is decomposed; and resolvS^rinfe hydrochloric and sulphuric acids, aB«l sulphur. The'cfiwrine combines with the hydrogen of the water, while the oxygejl of the water combinas with one fourth part-of the sulphur thus set free to form sulphuric acid. The remaining three parts of the ^ulphur aie^parafed in the solid fonii. #•''*' Chloruret of sulphur is compose the composi- tion of nitrate of ammonia? How is the chloride of nitrog:enprel)aredV What chem- ical changes talce place in Ihe formation of chloride of nitrogen 1 Whar cautions are given with respect to experimpnting on this compound t IODINE. 221 tard seed at a time, and even in this quantity, with great cau- tion. Both its discoverer, and Sir H. Davy, notwithstanding their experience and caution, as chemical experimenters, were seriously injured by its violence. At the temperature of about 200 degrees it explodes, and at common temperatures, when thrown on some combustibles. When a small globule is thrown into olive oil, or spirit of turpentine, ^ explodes with such vjplence as to shatter any vessel of glass in pieces. The violence of its detonation is owing to the great volume of the products which are formed at the instant. The com- pound consists wholly of the two gases, chlorine and nitrogen, condensed, and combined with each otji^r. When, therefore, the explosion takes place, these two elements assume their gase- ous forms, &US, in an instant, occupying a vast space, frhen compared to their former state. Chloride of nitrogen consists of 1 equivalent of nitrogen, 14 4 " " chlorine, 14*4 Making its number, 158 Equivalent, 126. Symbol, I. 366. The next simple substance we shall examine, is iodine. Its name signifies in Greek, " violet colored," because, when in the state of vapor, it is of a most beautiful violet color. Iodine was discovered at Paris by a manufacturer of nitre, in 1812. This substance; is obtained fi-omthe lye made of the ashes of marine vegetables, or from the substance called Jeelp, ov barilla, which is an impure alkali, made during the manu- facture of soda. 367. Preparation. — Dissolve^ the soluble part of kelp, or the ashes of sea-weeds in water ; concentrate the solution by evaporation, when crystals of carbonate of soda wiU appear, which must be separated. Then pour the remaining hquor into a clean vessel, and mix with it an excess of sulphuric acid. Boil this liquid for some time, and then strain it through a cloth. Put this liquid into a small flask, and mix with it as At what temperature does this compound explode 1 What combustible substances cause if to explode at common temperatures "^ Explain the cause of its violent ex- plosion* What are the combiuin^ numbers for it£ constituents, and also for the com- pound ? What does the name iodine signify, and from what Gircumstances bos it StriTed its name 1 By what process is iodine prepared 1 10* 222 UYDBIODIC ACID. much black oxide of manganese, by weight, as there was sul- phuric acid ; then attach to the mouth of the flask a glass tube, closed at the upper *end, and apply the heat of a lamp to the flask. The iodine will be sublimed, and will attach itself to the tube in small brilliant scales resembling black lead. Iodine thus obtained is a friable ^olid, with a brilliant metallic luster, and bluish gray color. Its taste is hot and acrid, and it is spariagly soluble in water. It corrodes the cork of the vial in which it is kept, and escapes — ^is a strong poison when taken in large doses ; but in soliition with alcohol, which dissolves it freely, has been considerably used as a medicine. When heated in a jetort to about 250 degrees, it evaporates, and fills the vessel with an exceedingly rich violet colored gas. As the retort cools, it again condenses in fine brilliant points resembling frost on the glass. If exposed to the open air, it slowly evaporates, and if handled, it leaves a brown stain on the fingers. \ Iodine resembles chlorine in smell, and in some of its proper- ties, particularly in destroying vegetable colors. Like oxygen and chlorine, it is a non-conductor of electricity, and is a nega- tive electric. So far as is known, it is a simple body. It has a strong attraction for the pure metals, and the simple non- metallic substances, such as sulphur and phosphorus. These compounds are called iodides. The best test for iodine, in its free state, is starch, with which it fonns an insoluble compound in water, of a deep blue color. This test is so delicate as to indicate the most minute portion of starch in solution. Iodine combines with hydrogen, oxygen, and chlorine, form- ing hydriodic acid, iodic acid, and chloriodic acid. Among these, the hydriodic acid, only, is of any importance or use. IODINE AND HYDROGEN. HYDRIODIC ACID. —^ Equivaleiit, 127. Symbol, IH. 1 eq, lodiDe, 126 + 1 eq. Hydrogen, 1. 368. When iodine is heated in a porcelain tube with, hydro- gen gas, the two substances combine and form a compound in What is the appearance of iodine ? What are its sensible properties 1 What are its uses? What is the etfect when it is heated in aretort7 Wnen exposed to the open air, what is the consequence? In what respects does iodine resemble chlorine? what is its electrical state? Is iodine asimpUj or a compound body? For what sub- BtaDce has iodine a strong attraction 1 What is the atomic weight of iodine 1 HYDRIODIC ACID. 223 the form of a gas, wtich has acid, properties, and wfiich. is rapidly absorbed by water. TMs is the hydriodio acid. This gas is without color, is very sour to the taste, reddens the blue colors of vegetables, and has an odor similar to muri- atic acid gas. It combines with alkalies, forming salts, called hydriodates. The discovery of iodine was one of the means of subverting the former doctrine, that oxygen was the universal acidifying principle, the above instance showing that compounds, having all the properties o^ aeids, are formed by the combination of hydrogen with iodine. Several other instances of similar natm'e have been discovered, as,in the case of muriatic acid. These instances appear, however, to be only exceptions to a universal principle, oxygen being «till the acknowledged agent by which most acids are formed. 369. Hydriodatb of potash. — This is given a place here, instead of among the salts, because it is the only salt of the kind to be described, and because, in manufactm-ing this com- pound, the method of obtaining the hydiiodic acid is different from .that stated above. It is the only hy'diiodate of any use or importance, and does not exist as a salt in a separate state, but only in solution. In preparing hydriodate of potash for medicinal use, the pre- liminary labor of forming the acid may be dispensed with, and the salt in solution may be formed by a very simple process, as follows : Add to a hot solution of pure caustic potash in w^ater, as much iodine as it is capable of dissolving. This will form a solution of a reddish brown .color, consisting of the iodate and hydriodate of potash, together with an excess of free iodine. Through this solution, a cm-rent of sulphureted hydrogen gas is ti'ansmitted, until the free iodine and iodic acid are con- verted into hydriodic acid, changes which may be known to be accomplished by the appearance of the liquid, which will gradually lose its brown color, and become colorless and trans- parent. The solution is then heated to expel the. remaining sulphureted hydrogen, and after being ^tered, is pure hydrio- What is the most delicate test for iodine 1 How may hydriodic acid be formed % Wbal are its sensible properties t What arc the salts called which this acid forms with alkalies 7 How does this acid demonstrate tlrjt oxygen is not the nnlTersal acidifying principle i Are there any other instances in which an acid is formed with- out oxygen 1 What is said relative to these exceptions to a general principle 1 How is the hydriodate of potash formed t What does the reddish brown solution consist of? Howls it known when asufficient quantity of sulpboreted hydrogen has beea passed through the solution of iodine ? 221 BEOMiNia. date of potash, in aqueous solution. This solution is consider- |ibly employed, as a medicine, in scrofula, and other glandular 7a bromine. Equivalent, 78. Symbol, Br. 370. The name bromine is from the Greet, and signifies a " strong, or rank odor." Bromine, after undergoing various and multiplied tortures, by means of the most powerful- decomposing agents, is arranged as an elementary body, having endured &e, galvanism,~^ &e., without loss of integrity. It was discovered by Balard, of Montpelier, in 1 826, and lite iodine, exists in the ashes of marine vegetables, and also in sea water. In the water of the Dead Sea it is found ii\, large quantities. The process of extricating it is too intricate to be detailed in this work, nor would it ever be undertaken by pupils in chem- istry, for which this book is designed. , Bromine is a fluid of a hyacinth red color, when viewed by transmitted light; but of a blackish red, when seen in the ordinary manner, or • by reflected light. Its odor resembles that of chlorine, but is much more disagreeable. Like iodine, it corrodes wood or cork, and stains the fingers of a yellowish hue. Its specific gravity is 3. It is a strong poison.- It is volatile at common temperatures, and emits red vapors similar to those of nitrous acid. ^ A hghted taper is soon extinguished by it, but before going out it burns with a flame which is green at the base and red at the top. Bromine does not turn blue vegetable colors f6d, but like chlorine, destroys them. From these properties it will be observed, that this substance has many characters in common with iodine and chlorine. Bromine combines with oxygen, hydrogen, and chlorine, but these compounds are little known, and of no interest except to professed chemists. Whatis theuse of thehyjriodate of potash? What does the name bromine sig- nify? Is it an element, or a compound ? In what substance does it exist 7 What is the appearance of bromine 7 In what respects is it similar to iodine ? In what re- spect does it resemble chlorine in properties? What is the equivalent number ol bromine 1 FLfOBIxfe' ' 225 FLnORINE. Equivalent, 19. Symbol, F. S"?!. It is a singular circumstance in chemistry, that the base of th% fluoric acid has never been detached from the acid itself notwithstanding every eflFort has been made on the part of the chemists to effect a separation. It will be remembered, that all the other acids consist of a base united to an acidifying prin- ciple, and that the two elements have been examined in separate states. Thus, sulphuric acid consists of sulphiu- and oxygen ; carbonic acid, of carbon and oxygen, &c. v The base of this acid, however, has been named fluorine ; but whether this is united to oxygen, as the acidifying principle, or whether such a base exists or not, is unknown. Fluoric acid must, therefore, at present, be examined as a simple body, or in connection with substances to which it unites. This acid exists in nature in considerable quantities, being found combined with lime, forming the salt called fluate of lime, but more commonly known under the name of Derbyshire spar. This latter substance is found crystallized, and of various colore intermixed, forming, when polished, one of the most beautiful productions of the mineral kingdom. It is in common use, for vases, candlesticks, snuflF-boxes, &c. 372. Process tor fluoric acid. — ^To obtain fluoric acid, a quantity of fluate of lime is powdered, and submitted to the action of twice its weight of strong sulphuric acid, in a retort of lead. On the appUcation of a gentle heat to the retort, the acid distills over, and must be reefiived in a leaden vessel. The retort «uid receiver, Fig. 95, made of sheet lead, ^''- ^ and soldered together on tjie edges, and the juncture be- tween them, stopped with a lute -of clay, will answer very well. The white fluor must Pracesa fir Fluoric Add. be selected for this purpose, as being most pure. It is first put into the retort, the acid poured in, and then connected with the receiver, which must be suiTOunded with a mixture of common salt and snow, or powdered ice, to keep it cold. Has the base of fluoric acid never been detached from the acid itself? Is the same true of any of the other acids'? What isthebase of fluoric acid called 1 Is it known that any such base exists ? What natural substance contains flaoric acid 1 Jlow is fluoric acid cb'ained from Huate of lime ? 226 FLUOKIKB. Fluoric acid, at the temperature of 32 degi-ees, or the freezing point, is a colorless liquid, and will retain its liquid state, if preserved in well stopped vessels, wlien the temperature is 60 degrees. But if exposed to the air when the temperature is above 32 degrees, it flies off in dense white fumes, whi(ii con- sist of the acid, and the moisture of the air with which it combines. No substance with which we are acquainted has so strong an affinity for water as fluoric acid. . Its liquid state appears to be owing to the water which is distilled over from th*) sulphuric, acid during the process of obtaining it, and no process yet de- vised has succeeded in freeing it entirely from moisture. When a single drop is let fall into watei-, a hissing noise is produced, like that occasioned by the plunging of a red hot iron into the same fluid, such is the heat produced by its combination with water. In experimenting with this fluid, the utmost caution is neces- sary ; for no substance so instantly and effectually disorganizes the flesh, and produces such deep and obstinate ulcers, as this. The least particle would inevitably destroy an eye, or create an obstinate ulcer on any other part. 373. Process of etching on glass. — Fluoric acid has the singular property of corroding glass, and may be used for this purpose in the floiid state, as above described, or in the gaseous form, the latter of which is commonly the most convenient. Any design may be etched on glass, by the following simple method : First, cover the glass with a coat of bees-wax, or engravers' varnish. If wax is used, it must be spread ov* the surface as thin as possible. This is done by neatiug the glass over a lamp, and at the same time. rubbing it with wax. A thin and even coat may thus be obtained. Next draw the design bj^ cutting the wax with a sharp pointed instrument, quite down to the glass, so that every lino may leave its surface naked ; otherwise the design will be spoiled, since the acid will not act through the thinnest film of the wax. A large needle answers for a graver for this purpose. Having made the design, the etching is done by placing What Is the appearance of fluoric acid at the temperature of 32 degrees? What ie Its appearance when exposed to the open air. at a temperature ab(7Ve 32 iegreeel What is said of the affinity of this siugularacid for water 7 What is said of the action of this acid on the flesh? What is said of the action of fluoric acid on glass? Describe the method of making designs on glass. FLUOSILISIC ACID. 227 the glass in a horizontal position, and pouring on the liquid acid. But a simpler method is by the temporary extrication of the gas from the fluor spar, for the occasion. For this purpose, take a lead or tin cup, large enough to include the figures on the glass, the lower the better, and having placed on its bottom a table spoouM of powdered spar, pour on it a quantity of strong sulphuric acid sufficient to form a paste. Then place the glass on the cup, as a cover, with the etching downward, and set the cup in a dish of hot water, or apply to it the gentle heat of a lamp, taking care not to melt the wax. In twenty or thirty minutes, the etching will be finished, and the wax may be removed with a little spiiit of turpentine. In this manner, figures of any kind may be permanently and beautifully done on glass. Since the above was written, the composition and affinities of fluoric acid have been more minutely examined, and ihore appropriate names affixed to its compounds. Flitm-ine is the hypothetical base of the hydrofluoric acid. . The latter is the present naine of fluoric acid. Its composi- tion is 1 eq. Fluorine, 18+1 eq. Hydrogen, 1 = 19. 374. Fldoboric acid. — A gas made by heating to redness a mixture of dry boracio acid, and powdered fluor spar. It is colorless, pungent, and produces a dense white cloud, when it escapes into a moist atmosphere. It is probably composed of 1 eq. Boron, 11 + 6 eq. Fluorine, 108 = 119. 375. FurosiLisic acid.-— A gas obtained from a mixture of fluor spar and silex by the aid of sulphuric acid. The fluoric acid produced in the usual way is a fluosilisic, since fluor spar nearly always contains more or less silex. Its composition is 1 eq. Fluorine, 19+1 eq. Silicium, 8=27. After the desiffD is formed, in what manner is tlie etching done 1 What is hydro- fluoric acid ? What is the fluoboric acid 7 What is fluosilisic acid J 228 LIGHT CARBURETED HYDROGEN. CHAPTER XVI. COMINATIONS OF SIMPLE NON-METALLIC COMBUSTIBLES WITH EACH OTHER. CARBON AND HYDROGEN. BICARBIDE OF HYDROGEN. Equivalent, 8. Symbol, CHg. 1 eq. Carbon, 6 + 2 eq. Hydrogen, 2. LIGHT CARBURETED HYDROGEN. 376. This gas has also been called hydro-carburet, and light inflammable air. . . It exists in every stagnant pool of water, especially dunng the warm season, being generated by the decomposition ot vegetable products. 3 7 7. How OBTAINED. " ^'^- ^^- — To obtain it from such places, fill a glass jar with watet, and invert it in a stagnant pool or ditch ; then stir the mud under it with a stick, and the gas will rise and dis- place the water in the jar. To preserve it for examination, slide a dish under the mouth of the jar while in the water, and then carefully raise, and caiTy the whole to the place of experiment, or make use of a bottle and funnel, as shown by Fig. 96 GaafTOm Stagmiitt Water. Sl8. Properties. — The gas so obtained is found to contain a proportion of carbonic acid gas, which may be removed by passing it through lime water. What are the names under which carbureted hydrogen has been known 1 In what place has this gas been formed by the operation of nature ? How may it be ob- tained from stagnant pools of water 1 What gas is commonly found mixed with this 1 What is the atomic composition of carbureted hydrogeu I LIGHT OARBUBETED HYDROGEN. 229 This gas is composed by weigM of 1 equivalent of carbon, 6 2 " " hydrogen, 2 8 3t9. It is immediately destructive to animal life, and wiU not support combustion. It is highly inflammable, and burns with a yellowish blue flame, but owing to the carbon it con- tains, it gives considerably more light than pure hydrogen. Mixed with atmospheric air, Uke hydrogen, it^tonates power- fully when inflamed. When burned -wiih oxygen, the product of the combustion is water and carbonic acid. There appears to be several varieties of light carbureted hy- drogen, or perhaps the difierence may depend on a mixture of the light and heavy kinds. If a volume of steam be sent through a red hot gun-barrel filled with charcoal, the gas ob- tained differs little in its illuminating powers from that obtained from stagnant pools. Nor is there any material difference be- tween these and that evolved by the burning of common wood, such as maple or beech, in .a. gun-barrel. • But if pine wood containing turpentine, be heated in the same manner, the gas obtained has much greater iUumiihating powers, the brilliancy of the flame being nearly equal to that of oil gas. Now, as by analysis there appears to be only two kinds, or varieties, of car- bm-eted hydrogen ; in the first of which there is but one pro- portion, and in the second two proportions of carbon, it is most probable that these different powers of illumination depend on a mixture of the two gases. , 380. This gas sometimes exists in large quantities in coal mines, and is known by the miners under the name of fife- damp. The most shocking accidents have often occuiTed in consequence of the explosion of this gas in the mines, when mixAi with atmospheric air. In some mines, this gas flows from the coal beds in vast quantities, being obviously the pro- duct of the decomposition of water by the coal. But in what manner the water is decomposed, is unexplained. Did the process consist in the formation of sulphuric acid, in conse- quence of the oxygenation of the sulphur, and the subse- quent action of this acid on the iron of the sulphuret of iron. How does it effect animal life and combustion ? When burned, why does this gas give a stronger light than pure hydrogen t What is said concerning the several varieties of carbureted hydrogen J Under wljat name is this pas known, when it oc- cur:^ in coal mines 1 In what manner iis this gas formed in coal beds t ■ 20 230 LIGHT OARBUKETED HVDROGEN. there would be formed sulphureted, instead of carbureted hydrogen. There are no facts, it is believed, which warrant the supposi- tion, that in ordinary cases, the decomposition is consequent upon the heat, or ignition of the coal. Possibly in such vast bodies of coal as are found to exist in some mines, the water is slowly decomposed, by gradually imparting its oxygen to the carbon, without the aid of heat. 381. Explosive compound. — We have already stated, that when carbureted hydrogen is mixed with atmospheric air, and inflamed, a violl^it explosion is the consequence. In the coal mines of England, the mixture of atmospheric air and the gas in question, otien produces such an explosive compound. It appears that the miners have no certain means of ascertaining the presence of this gas, probably because, being much lighter than the atmospheric air, it at first rises to the roof of the mine, and then gradually descends toward the floor. As the rtliners work entirely by the light of lamps, one of which is sufficient to set fire to the explosive compound existing throughout the whole cavern, it is obvious, that as soon as the hydrogen has mixed with the air' near the floor of the mine, in the explgdiog proportions, it must inevita^y take fire. ' It can readily be imagined, particularly by those who have witnessed the detona- tion of a pint or two of this compound, that a quantity cover- ing many acres of surface, and extending upward in some places, at least, several hundred feet, mUst produce the most awful consequences. 382. Explosion in Felling collibet. — Such explosions have often taken place in the coal mines in'diflerent parts of England. That which happened in a mine called Felling col- liery, in Northumberland, on the 25th of May, 1812, was at- tended with the loss of 92 lives, and spread poverty, and wretch- edness throughout the whole district. Most of these men had wives and children, who depended entirely on their daily labor for support, and who, in addition to the loss of their hushainds and fathers, by so sudden and awful a death, were in a moment deprived of th.e means of subsistence. This mine had been wrought a century or more, and only a single accident from fire-damp had before happened, and this What are the remarks on this subject 1 What is the consequence, when this gas is mixed with atmospheric air and inflamed 1 In what situations is it said that ex- ptosive compounds are thus formed 1 What is the reason that the miners are not aware of the existence of this compound until the whole takes fire? What number of lives were destroyed by such an explosion at Felling colliery, in 1812 7 LIGHT CARBURETED HrDBOGEX. 231 ■was SO trifling, as only to slightly bum two or three workmen. Twenty-five acres of coal had been excavated in this mine, and the number of men employed under ground, at the time of the ac! said of the influence of gas Ughts on the motals of London 1 How iB oil eas manufactured 1 Describe the furnace and retorts. How is the oil admjited into the retorts 1 In large works, what is the size of the gasometer 7 238 ' GAS LiGfns. 395. Portable gas. — As the burners are stationary, in the ordinary mode of lighting with gas, there exists an inconven- ience in its employment for the purpose of common household illumination, where the lights are often necessarily carried 'to different parts of a room, or from one room to another. There is also another inconvetdenoe, which arises from the expense of laying conductors through streets where the houses are scat- tered, and consequently, where but a small quantity of the gaa is wanted. To remedy these defects in the ordinary method of lighting with gas, it has been proposed to condense the gas in strong copper, or brass lamps, at the gas works, ajjd then transport them, thus filled, to the houses, to supply the place of common lamps. This is distinguished by Ishe came portable gas, and has been extensively employed in London and its vicinity, but is now out of use. 396. Illuminating power of gas. — The illuminating power of the oil gas is much greater than that of coal gaa. According to <3ie experiments of Mr. Accum, two cubic feet of coal gas willbm-n one hour, and give a quantity of light equal to three tallow candles, eight of which weigh a pound. But according to the experiments of Mr. Dewey, formerly superin- tendent of the gas works of New York, one cubic foot of oil gas will give light for one hour equal to 8 candles, 6 to the pound. This agrees very nearly with the result of Mr. Ricardo's experi- ments, who found that a given quantity of oil gas was equal in illuminating power to four times the same quantity of coal gas. One "gallon of clean whale oil will make 100 cubic feet of gas, which, according to the above statement, will bum 100 hours, and give as niuch light as 8 mould candles, 6 weighing a pound. Such an immense difference between the cost of gas, and other lights, would seem to indicate the propi%ty of establishing gas works in every village. But the expenses of erecting and tend- ing small establishments of this kind, are such as not to yield any considerable profit to the owners. How is the gas conveyed into the gasometer? How is the gas cooxeyed .from the^ gasometers to the gas burners ? What inconvenience is experienced in-the, use of ordinary gas lights? How has it been proposed to remedy this defect? Uilderwhat name is this condensed gas known 7 which gas has the greatest illuminating power, .that from the coal, or that from oil ? What is said to be the comparative di^renfee between the illuminating power of coal and oil gas? What quantity of gas is it said one gallon of oil will malie, and how long will this gas burn 1 The cost of oil gas being much less than other lights, why are they not universally used 1 % SULPHIDE OF HYDROGEN. 289 HYDROGEN AND SULPHUR. SntrHIDE OP HYDROGEN. Equivalent, 17. Symbol, SH. 1 eq. Sulphur, 16 + 1 eq. Hydrogen, 1. 397. This gas may be procured by placing in a retort some sulphuret of antimony, or iron, and pouring on it sulphuric or muriatic acid. The sulphui-ets of these metals may be prepared by heating either of them, in filings or powder, with sulphur ; or the natural sulphurets may be employed. The chemical changes, concerned in the formation of this gas, are as follows : The oxygen of the water which the acid contains unites with the metal of the sulphuret, which metal is then dissolved by the acid. Thus, the hydrogen of the water, and the sulphur of the sulphuret, are both set at liberty, and having an affinity for each other, they combine, and escape in the form of sul- phurated hydrogen. 398. Properties. — Sulphureted hydifegen is a transparent, elastic gas, which, both to the taste and smell, is exceedingly unpleasant and nauseous, its odor being similar to that of putre- fying eggs. Under a pressure of 17 atmospheres, that is, under a weight equ^ to 255 pounds to the square inch, this gas is condensed into a colorless liquid, but again assumes its gaseous form, when the pressure is removed. This gas is instantly fatal to animal life, when pure, and even when diluted with 1500 times its bulk of air, has been found so poisonous as to destroy a bird in a few seconds. Like hy- drogen, it instantly extinguishes flame, but is itself inflammable, and brn-ns with a pale blue flame. The products of its com- bustion are water and'sulphuric acid. The composition of this gas being hydrogen and sidphur, the water formed during its combustion is the product of the union between the hydrogen and the oxygen of the atmosphere, during the act of combus- tion, while the sulphuric acid is formed by the union of the oxygen of combustion with the sulphur. Sulphureted hydi'ogen tarnishes silver, and even gold, and blackens paint ma^e with preparations of lead. This gas is How may sulphureted hydrogeu be procured ? What chemical changes takeplace by which this gas is evolved 7 What are the sensible properties of this gas 1 Under what pressure may this gas be condensed into a liquid ? Does it remain liquid when the pressure is removed ? What is said of the poisonous effects of this gas ? What are the effects of plunging a burning candle into this g;as? When this gas is burned, what are the products of combustion 1 Whence come the water and sulphuric acid ■? What is its effects on the metals ? 240 PHOSPHIDE OF HYDKOGEN, often generated during the decomposition of animal products,- in sink drains and ditches, and hence the paint of white lead, about such places, often becomes black in consequence. Eggs contain a small quantity of sulphur, which, on boiling, is con- verted into sulphureted hydrogen, and hence a silver spoon is instantly tarnished by coming iu contact with a boijed egg. The composition of sulphureted hydrogen by weight, is as follows : 100 cubic inches of this gaS weigh 36 grains. This is composed of sulphur, . . 33.39 " » " " hydrogen, . 2.11 " 36.00 HYDROGEN AND PHOSPHORUS. PHOSPHIDE OF HYDKOGEN. Equivalent, 35. Symbol, PHj. 1 eq. Phosphorus, 32+1 eq. Hydrogen, 3. 399. This compound consists of hydrogen, in which is dis- solved a small quantity of phosphorus. It may be formed in several ways. One of the most simple is the following : Into five parts of water put 15 or 20 grains of phosphorus, cut into small pieces. It must be cut under water to prevent its taking fire. Then add one part of granulated zinc, and poUr in three parts of sulphuric acid. The gas will instantly rise through the water in small bub- bles, and will take fire spontaneously on coming in contact with the air. Each bubble, as it takes fire, will form a horizontal ring of white smoke, which will gradually enlarge as it rises, until lost in the air. The cause of this curious appearance is owing to the formation of a small quantity of phosphoric acid by the combustion of the phosphorus, and which, having a litrong affinity for moisture, attracts it from the atmosphere, and thus foiTQs a little ring of dew, which is visible to the eye. Phosphureted hydrogen may also be obtained by placing some pieces of phosphuret of lime in water, when the gas will be extricated, and will rise through the w^ter as above described. {See Phosphuret of Lime.) What is the composition of 100 cubic inches of this gas by weightl How is phos- phureted hydrogen formed 7 What singular property does this gas possess 1 How is the ring of white smoke accounted for, which rises after the combustion'of a bubble of this gas? CYANOGEN. 241 This gas detonates with great violence when mixed with oxygen, and forms a dangerous explosive compound with atmospheric air; consequently, much caution is required in mating experiments with it. When a bubble of phosphureted hydrogen is allowed to mix with oxygen, a flash of the most vivid light is spontaneously produced, which, in a darkened room, resembles lightning. The safest method of performing this beautiftil experiment, is to let up into a small strong- bell glass, or a thick glass tube, a few ounces of oxygen gas. Then, having collected a little of the phosphureted hydrogen in a small vial, hold the bell glass in the left hand, with its mouth under water, and with the right hand manage the vial, so as to let only a single bubble at a time escape into the oxygen. The detonation of each bubble ' will produce a considerable reaction on the beU glass, which will be felt by the hand. But if the experiment be performed as described, there will be no danger of an explosion. The gas above described is called per-pkosphureted hydro- gen, dei^oting, as abeady explained, the highest degree with which one body unites with another. It is so caEed to distin- guish it from the proto-phosphureted hydrogen, which contains only half the quantity of phosphorus, and is a much less inter- esting compound. Per-phosphureted hydrogen consists of 1 equivalent of phosphorus, 32 3 " « hydrogen, 3 35 NITROGEN AND CARBON. BICARBIDE OF NITROGEN. Eqnivalent, 26. Symbol, Cj N. 2 eq. Carbon, 12-|-1 eq. Nitrogen, 14. CYANOGEN. 400. By boiling together red oxide of mercury and Prussian bltte in powder, with a suflScient quantity of water, there may be obtained a compound which shoots iiio crystals, and which was formerly called prussiate qf mercury, but is now known by the name of cyanuret of mercury. With what substances does phosphureted hydrogen afford dangerous detonating compounds ? What directions are given for admitting bubbles of this gas into oxy. gen f What is the equivalent composition of per.phosphureted hydrogen t How may cyanuret of mercurv be ibrmed I 21 242 PRCSsic ACID. Wheji this salt is heated in a retort, it turns black, the cy- anogen passes over in the form oLa gas, and the mercury is revived, or assumes its metallic forrnl This gas has a pungent, disagreeaKfe odor, bums with a pur- plish blue flame, extinguishes burning tfeidies, and is reduced to a liquid under the pressure of about t%ee and a half atm'os- pheres. This gas must be collected over Viercury. 100 cubic inches of this gas weigh 65 ffl-aips, and is found to be composed of 2 equivalents of carbon, 12 1 " " nitrogen, 14 26 its combining number. Cyanogen, though a compound gas, has the singulajr property of combining with other substances, in a manner perfectly sim- ilar to the simple gases, such as oxygen and hydrogen. The term cyanogen comes fron^ two Greek words, signifying to form blue, because it is an ingredient in Prussian blue. HYDROCYANIC ACID. Equivalent, 27. Symbol, HCy. 1 eq. Cyanogen, 26+1 eq. Hydrogen, 1. PKUSBIC ACID. 401. Cyanogen is obtained by simply heating cyanuret, or prussiate of mercury, as above described. Hydrocyanic, or pnis- sic acid, is composed of cyanogen and hydrogen. It may be obtained by heating in a retort a quantity of prussiate of mer- cury with two-thirds of its weight of muriatic acid. During this process there, takes place an interehange of elements. The cyanogen of the cyanuret of mercury unites with the hydrogen, forming hydrocyanic acid, while a muriate of the peroxide of mercury remains in the retort. But a more common method of making prussic aoid is the following : 402. Process for prussic acid. — Mix together, in a con- venient vessel, four ounces of finely powdered Prussian blue, two How is cyanogen procured 1 What are the properties of this gasi What is the equivalent composition of this gas, and what is its combining number 1 Whence comes the name of this gas ? How may hydrocyanic, or prussic acid, be formed by -meana of prussiate nf mercury and muriatic acid t What are the interchanges of elements whiph take place 'during this process 1 What is the more common method described (or making prussic aciri ? PRUSSIC ACID. 243 FIC. 98. and a half ounces of red oxide of mercury, and twelve ounces of water. Boil the mixture for half an hour, now and then stir- ring it. The blue color will disappear, and the solution will becoma yellowish green. Filter the solution, and wash the residuum by pouring on boiling water, in quantities suflScient to make up the loss by evaporation, and let this also pass throna-h the filter. ^ Put this solution, which is a prussiate of mercury, into a re- tort in caremlly the complicated interchange ol chemical principles that tak.ee place by this proces.*:. What is the appearance of the acid thus obtained ? Prussie Acid. 244 piiussic ACID. prives the prussiate of mercury of its oxygen, the prussic acid reraains free in the solution of the sulphate of iron, and being volatile, readily passes over into the receiver, by a gentle heat. The hydrocyanic acid thus obtained, is a perfectly colorless, limpid fluid, and can not be distinguished by th^ eye from dis- tilled water. It has a strong odor, )*esembUng that of peach blossoms, and when much diluted has the taste of bitter almonds. ... 403. A MOST DEADLY POISON. — Prussic acid is the most active and powerful of al] kiiown poisons. A single drop placed on the tongue of a dog causes Ms death in a few seconds ; and a servant girl who swallowed a small glass of it, diluted with alco- hol, fell down instantly, as though struct with apoplexy, and died in two minutes. A professor at Vienna, ha\'ing prepared some of this acid in its most concentrated state, by way of ex- periment, diffused some of it on his naked arm, and was killed thereby in a short time. These instances not only show the terrific and mysterious effect which this substance has on the animal economy, but they also show what extreme caution is necessary in preparing and using it. When much diluted, it has, however, been considera- bly employed as a medicine, in cases of consumption, and often with good effect. ,. 404. Observations. — Although the investigations of chem- istry have developed this substance, than which, even hghtning itself is scarcely more prompt, or sure, in destruction, still the wisdom of Omniscience has connected circumstances with its production and nature, which, in a great measure, will always prevent its employment for criminal purposes. The process by which it is made, requires more chemical skill than generally falls to the lot of unprincipled and vicious persons ; and when obtained, its active properties are so evanescent, as never to re- main more than a week or two, withput peculiar treatment, and sometimes it becomes nearly inert in a few days. The odor, also, which is distinguished in animals destroyed by it, is often the sure means of detection, The commencement of itS' decomposition is marked by the reddish brown color of the liquid, and, in a short time after, it becomes black, and deposits a thick carbonaceous substance, at Whjit is tbe smell of this acid 7 What cases are mentioned of its poisonous effects'; For what purposes is this acid employed when much diluted? What cir- cumslances are connected with the production and nature of this acid, which it is said will prevent its employment for wicktd purposes! PR0SSIC ACID. 245 the same time it loses its peculiar smell, and emits that of am- monia. In this state, the prussic acid' has none of its former properties, but becomes entirely inert and worthless. This substance possesses the sensible qualities of an acid only in a very slight degree, being hai-dly sour to the taste^and pro- ducing but very little change in the blue colors of vegetables. It however performs the office of an acid in combining with alkaline bases, forming salts, called prussiates, or hydrocyanates. 405. Composition of. — The following is an example, by which the composition of a substance may be found, when one of its elements can be made to combine with a third body, in a known proportion. By a previous experiment it was ascertained how much cyanogen would combine with a given proportion of potassium, the basis of potash. Then, Gay Lussac exposed to the action of 100 measures of piTissic acid, heated so as to be in a state of vapor, a quantity of potassium precisely sufficient to absorb 50 measures of cyanogen. By this process, cyanuret of potassium was formed, and exactly 50 measures of the vapor of prussic acid was absorbed, leaving 50 measures of pure hydro- gen remaining in the vessel in which the experiment was made. From this experiment, it appears that prussic acid is com- posed of equal volumes of cyanogen and hydrogen, and there- fore that they combine in the ratio of their specific gravities, that is, the weight of the vapor of prussic acid must be the combined weights of cyanogen and hydrogen, of an equal bulk. 406. .Atomic weights of. — Now the specific gravity of hy- drogen is known to be 0.0694, and cyanogen gas, 1.8044, air being 1000. Cyanogen, therefore, is 26 times as heavy, bulk for bulk, as hydrogen, and since they combine in equal propor- tions, by volume, to form prussic acid, it follows that this acid consists of an atom of hydrogen united to an atom of cyanogen, and, therefore, that an atom of cyanogen gas is 26 times as heavy as an atom of hydrogen. Thus, the atomic weight of cyauogep is 26, that of hydrogen being 1, and the specific How does the acid appear wbile decomposing? Does this substance possess the sensible qualities of an acid ? In what respect does it perform the office of an acid ? How did Gay Lussac know that exactly 50 measures of cyanogen were absorbed by the potassium ? [Cyano^ren combines with metalsin the same manner that oxygen does. See Cyanogen.] What was the quantity of hydrogen which remained after this absorption? From this experiment, what appears to be (he composition of grussic.acrd, by volume ; and therefore, the vapor of prussic acid consists of (be com- ined weight of what? How does it appear that cyanogen is 26 times as heavy as hydrogen? [Multiply 0.0694 by 26.] 21* 246 SULPHIDE OF CARBON. gravity of the vapor of prussic acid being the medium between them, is 0.9369, because 0.0694, the specific gravity of hydro- gen, added to 1 .8044, the specific gravity of cyanogen, makes 1.8738, the medium or half of which is 0.9369, the specific gravity of the vapor of prussic acid. The composition of prussic acid may therefore be stated thus : - By volume. By weight. Cyanogen, 50 1.8044 26, one atom. Hydrogen, 50 0.0694 1, one atom. 100 acid vapor. 27 atomic weight. Thus the' atomic weight, or equivalent number for cyanogen is 26, and that for prussic acid is 27. The above will serve as a practical example of the method of finding the atomic weight of a constituent, under similar circumstances. CARBON AND STTLPHHR. eUIiPHIDE OF CARBON. Equivalent, 38. Symbol, CSa. 1 eq. Carbon, 6+2 eq. Sulphur, 32. 407. Preparation OF.^This singular and interesting com- pound, as the name indicates, is composed of sulphur and car- bon. These substances unite only in one proportion ; by merely heating them together, no combination takes place, the sulphur burns away, or passes off in vapor, and the charcoal- re- mains unchanged ; but by bringing the vapor of sulphur into contact with charcoal at a red heat, the combination takes place immediately. For this purpose a porcelain tube is sometimes employed, but one of cast-iron, or a gim-barrel, coated with clay on the inside, is better. For this purpose, the clay is formed into a thin paste, with water, and poured into the tube, this being at the same time rolled so that the clay will cover every part. After one coat is applied, and dried by heating^the tube, the same process is repeated, until the surface is well covered. How does it appear that an atom of cyanogen is 26 times as heavy as one of hydro- gen 1 [Because they combine in equal volumes, hut cyanofren weighs 26 times the most.] What then is the weight of an atom of cyanogen, that of hydrogen being 1 1 Wliat is the specific gravity of the vapor of pruppic acid, it being the medium be- tween those of cyanogen and hydrogen 1 From these data, wliat is the composition of prussic acid, by volume and weight 1 What is the equivalent number for prussic acid! SULPHIDE OF CARBON. 247 and the iron is thus protected from the action of the sulphur. If the tube is not well prepared, the experiment will fail entirely, since the action of the sulphur in a few moments would destroy the iron. The tube, well covered, is filled with burning charcoal, and laid in the furnace, Fig. 99, until it attains a white heat. The end, h, of the tube is closed with a piece of clay, and at a there FIG. 99. Preparation of Sulphide of Carbon^ ) is an aperture for the admission of the sulphur ; this is also fur- nished with a stopper of clay. A long glass tube, o, is attached to the iron pipe at c, and passes into the capacious flask, _/j through an aperture in the side. In the absence of such a flask, a double necked bottle wiU do. A waste pipe, m, arises from the flask, and leads into the open air through a window, so as to avoid the fumes of the sulphur. At the bottom of the flask some water is placed, to receive the product of the experi- ment. The flask and glass tube should be kept cold during the whole process. For this purpose, the tube should be sur- rounded by a cloth kept wet with water from the cistern, e, and the flask surrounded with ice. When the apparatus is ready, and the iron tube is at a white heat, the stopper a is to be removed, and pieces of sulphur dropped in, and the stopper instantly returned to its place. The sulphur instantly melts, and in passing through the hot tube, which is a little inclined, is converted- into vapor, and at the same time unites with the charcoal, to form the compound in question. The sulphuret of carbon, being conden|ed by the cold tube, flows along into the flask, and sinks in the water it contains. 408. Another method.— A more simple method of pro- ducing the sulphuret of carbon, where it is designed to make it in quantities, is the following : 248 BCTLPHlDE OF' CARBON. A cast-iron cylinder is produced, having a cover through which pass the tubes, J, c, Fig. 100. The cylinder is to be coated with clay in the manner above described for the iron tube,, and then "filled with charcoal, the tube, h, being in, its FIG. loa Sulphide of Carbon, place as shown by the figure. The cylinder, is then to be placed in a furnace, and heated to redness, and .then the sul- phur introduced through the tube, 6, the aperture of which must be immediately, closed. The melted sulphur, passing down the tube to the bottom of the cylinder, is -there converted into vapor, and passing through the ignited charcoal combines with it, and rises by the iron tube, c, into the glass tube, e, along which it is condensed. The tube, d, leads from a cistern of water, which is allowed in small quantities to run in a trough containing the glass tube, arid from which it is conducted by the string, h, to the dish, x. The sulphuret as it is formed, passes down the tube,/, into the vessel, n, this being half filled with pounded ice. The waste pipe, m, conducts away any superfluous gas which is generated during the process. Whenever all is prepared, as above described, the jntroduc- tion of small quantities of sulphur by the tube, i, will insure the production of the compound in question, so long as any char- coal remains in the cylinder. It is apt, however, to contain some impurities, and must be distiUed with chloride of calcium. 409. PROPERTiES.-«-Pnre sulphuret of carbon is transparent and colorless, and insoluble in water. It has a strong, disagree- able smell, peculiar to itself, and is soluble in alcohol, arid ether. Its specific gravity is 1.272, and it boils at 127 degrees, evapor- ating very rapidly during the process. Its freezing point is 60 METALS. - 249 degrees below zero. In the open air, it is exceedingly volatile, and the cold it thus produces is intense. Under the exhausted receiver of the air-pump, the evaporation of course is still more rapid. In this situation, a thermometer bulb, covered with fine lint, and moistened with this fluid, carried off the heat so rapidly by evaporation, that the mercuiy was frozen in the tube, and md on substituting an alcohol instrument, the fluid sunk down to 80. degrees below zero. Sulphuret of carbon is soluble in fixe* and volatile oils,^ and it dissolves camphor, phosphorus, and sulphur. When the two latter substances are dissolved in it separately, the evaporation of the fluid causes crystals of them, of remarkable. regularily and beauty, to be deposited. CHAPTER XVII. Nemea of metals. Gold, . . , Silver, . . , Iron, . . . Copper, . . Meronry, . . Lead, . . . Tin,. . . . Antimony, Bismuth, . 2SnG, . . Arsenic, . Cobalt, . . Platimim, . Nickel, "t" themetais; TABI^ OF THE DISCOVERT OF THE HETAIS. Aathon of the ducovet/. Ti itj-i Tungsten, Tellurium, Molybdenum, Uranium, . Titanimn, . Chromium, Columbinm, Palladium, . Khodimn, . Iridium, Osmium, . Cerium, ■ Known to the ancients. Described by Basil Valaitine, 1490 Described by Agricola, 1530 First noted by Paracelsus, 16th century. I Brandt, the chemist, 1733 Wood, assay-master, Jamaica, 1741 Cronsted, 1751 Gahn and Scheele, 1774 Dr. Elhnyart, 1781 Mnller, 1782 Heihn, 1782 . Klaproth, 1789 Gregor, 1791 Vauguelin, 1797 . Hatchett, . ■ 1802 \ WoHaston, 1803 . Deseotils and Tennant, 1803 Smithson Tennant, 1803 Hissinger and Beraelius, . ... 1804 250 NRiael of metala. Potassium, . Sodium, Barium, Strontium, . Calcium, . Cadmium, . Lithium, . Zirconium, Aluminum, Gluoinura, . Yttrium, . Thoriign, . Magnesium, Vanadium, Lanthanium, Didymium, Erbium, . Terbium, . Rutherium, Pelopium, . Niobium, . Donarium, OF THE DISCOVERY OF TIIK METALS. CONCLnUED. Authors of the ducoTery. Dates. Sir Humphrey Davyf 1807 Stromyer, . Ariwedson, . Berzelius, . 1818 1818 >1824 WoWer, 1828 Berzelius, BuBsy, . Sefstrom, Mosander, 1829 1829 1830 1839 V Mosander, 1840 ( Klaus, H. Bose, . Bergman, 1844 1846 1848 GENERAL PROPERTIES OF THE METALS, 410. The metals form the most numerous class of undecom- posed, or elementary bodies. They possess a peculiar luster, called the metallic, which continues in the streak, or when they are reduced to small fragments. They are all conductors of electricity and caloric. They are^ fusible, at di^rent tempera- tures, and in fusion retain their luster and opacity. They are, in general, good reflectors of light, and with the exception of gold, which, in the thinnest leaves transmits a green light, they are perfectly opaque. JMany of fhe metals may be extended under the hammer, and are hence called malleable, or under the rolling press, and are called laminahle, or may be drawn into wire, and are called duc- tile. Others can neither be drawn into wire, nor hammered into plates, but may be ground to powder in a mortar ; these are called brittle metals. The metals are capable of combining with each other, in any Have any of the metals been decomposed 1 What is the peculiar luster of the metals called 1 What imponderable agents do all the merals conduct ? Are all the melalB opaque'! What are malleable, laminable, and diiclile metals? What are brittle metals 1 What is an alloy 7 What is said ofihe specific sravit? of the metalil What are the properties in respect lo which the mitals differ ? METALS. 251 proportion, wh«n melted together, and siioh compounds are called alloys. With a few exceptions, the metals have the greatest spedfio gravity of all bodies. Potassium and sodium swim on water, but -with these exceptions, the lightest among them, cerium, is about Si- times the weight of water ; platinum is more than 20 times heavier than the same bulk of water. The metals differ in r&spect to brilliancy, color, density, hard- ness, elasticity; ductility, tenacity, conductility for caloric and electricity, fusibility, expansibility by heat, stability, odor, and taste. 411. Metals positive electrics. — When combined- with oxygen, chlorine, iodine, or sulphur, and the resulting* com- pounds submitted to the action of galvanism, the metals with- out exception are revived, and appear at the negative side of the battery, hence aU the metals are positive electrics. The malleable metals, such as gold, silver, and iron, in what- ever manner their surfaces are increased, if this is done rapidly, grow hot, and crumble imder the hammer, or press, and finally refuse to be extended any further. It then becomes necessary, if their surfaces are to be further extended, to anneal them, which is done by exposure to a red heat, when they become soft and malleable as before. It is probable that this change is produced by a quantity of caloric which the metal retains in its latent state, and by which its particles are prevented from form- ing so compact a mass as before. When the metal is again drawn under the hammer, or press, it grows hot, and at the • same time is increased in density and specific gravity, the caloric before absorbed being given out, and the metal is again ren- dered brittle-by the process. 412. All the metals become fluid by heat. — ^All the metals are converted into a fluid state by suflBcient degrees of heat. In this respect there is a vast difference in the different metals. Mercury is a fluid at all common temperatures, and does not assume the solid form unless exposed to a temperature nearly 40 degrees below the freezing point, while platina and columbium continue solid under the highest heat of a smith's foi^e, and only become fluid under the heat of a compound blow-pipe, or the action of the most powerful galvanic battery. What is the electrical state of the metals 1 When the surfaces of the malleable metals are suddelily increased, what effect is thereby produced on their temperature % When is it necessary to anneal a metal "i How is the' process of annealing supposed to affect the metal, so as to restore its malleabilityl By what means may all tha metals be rendered fluid ? What is said of the di^rent temperatures at which tha metals become fluid 7 252 METALS. TABLE OP THE FUSIBILITY OF THE METALS Mercury, . . . Potassium, . . Sodium, . . . Tin FUSIBLE BELOW Pahr. . 39 deaf. . 136 " . 190 " , 442 " A RED BEAT. Lead, ... Tellurium, . . Zinc, . . . Antimony, . - Cadmium, Palir. . 594 deg. . 620 " . 113 " . 800 " AlW, . . • • > Bismuth, . . . . 497 " . 442 " INFUSIBLE BELOW A RED HEAT. Silver, .... Copper, . . . God, .... 2283 deg. 1996 " 2016 " Iron, (cast,) Cobalt, . . . . 3479 deg. . 2800 " REftUIRE THE HEAT OP A FOEOB. Iron, (malleable,) Manganese, Nickel, Palladium. Molybdenum Uranium, Tungsten, Chromium, Titanium, Osmium, Iridium, Khodium, Platinum, Columbium 413. Metals become oxides. — With several exceptions, these bodies suffer a singular change on exposure to air and moisture, or on exposure to air and heat. They lose their tenacity, brilliancy, and other qualities peculiar to the metals,^ soil the fingers, and crumble to powder, but at the same time increase in weight. This change is termed oxidation, and in this state they are termed metallic oxides. This increase In weight and loss of metallic splendor, does not happen when the metal is placed in a vacuum, or when it is protected from the air by varnish or other means, but is found to be the consequence of the union between the metal and the oxygen of the air, or water, or both. Thus, iron, when exposed to air and moisture, spontaneously absorbs oxygen, and is con- verted into a brown friable matter called rust. This is an oxide of iron. The increase of weight is caused l?y the solid oxygen which thus combines with the metal. The metals, with the exception of platina, gold, and silver, are said to suffer a pe- culiar change, when exposed to heat, or to air and moisture 1 To what is this chanjT* owinjj, and what are the resulting compounds called 1 What causes iron and other metals to rust, wliea exposed to the air ? METALS. 253 414. The mbtals combustibles. — The metals, in the languagB of chemistry, are termed combustibles, because they are capable of combining with oxygen, and thus passing through the pro- cess of oxidation, or combustion. In ordinary combustion there is an extrication of heat and light, and under favorable circum- stances, several of the metals exhibit these phenomena. Ziuc burns with a brilliant flame when heated, and exposed to , the open air ; and iron, when heated in oxygen gas, emits the most vivid scintillations, attended with intense heat. Gold and pla- tina, the metals which have the least afiBnity for oxygen, are still capable of uniting with it so rapidly, as to produce scintilla- tions when heated with the flame of the compound blow-pipe. In all cases the metals combine with oxygen most rapdly when exposed to the highest degrees of heat. Hence, at common temperatures, their oxidation proceeds so slowly as not to emit sensible light or heat ; and some of them, such as gold, silver, and platina, do not combine with it at all at such temperatures. Some of the metals combine with oxygen in only one propoT- tion, while others combine with it in three or four proportions. Thus, there is only a single oxide of zinc, but there are three or four oxides of iron. 415. Rkduction of the metals. — After the metals are con- verted into oxides, they may again be reduced, that is, brought back to their metallic states, by depriving them of their oxygen. This may be done by several methods, depending on the nature of the metal, or the force by which it retains the oxygen. The reduction of many of the metals from their ores, is nothing more than depriving them of their oxygen. For this purpose, a common method is to heat the oxide with some combustible which has a stronger afiSnity for the oxygen than the metal has. Thus, the oxide parts with its oxygen, and assumes the metallic form, while the combustible absorbs that which the oxide before contained, and is itself consumed, or converted into an oxide. As an example,, carbon, when heated, has a stronger affinity for oxygen than iron, and therefore, when carbon and oxide of iron are strongly heated together, the iron Why are the metals termed combastibles in tbe language of chemistiy 1 Under -what circamstances do several of the metals exhibit the ordinary pheDomena of com- bustioD ? Under what circumstances do all the metals combine must rapidiy with oxygen ? What metals do not combine at all with oxl^n at common temperatares ? Do the metals all combine with the same proportion of oxygen 1 After a metal has been converted into an oxide, how may it again be reduced, or brought again to its metallic state 1 By what method can the melals be deprived of their oxygen 3 What is one of the most common methods of reducing iron from its^res 1 When iroa is reduced by heating its oxide with charcoal, what becomes of the oxygen 1 22 254 METALS. is reduced while the charcoal is converted into an oxide, or an acid, and passes away into the air, or in common language, is burned up. This is the method of reducing iron from its ores. In some instances, heat alone di'ives away the oxygen and reduces the metal ; but in such cases the metal has only a weak affinity for oxygen. The oxides of gold, mercury, and platina, are thus reduced. Metals having stronger affinities for oxygen, resist such methods of reduction, and require the more powerful agency of galvanism. When metallic oxides are exposed to this influence, the reduced metal is found at the negative side of the battery, while the oxygen rises through the water at the positive side. 416. The metals not soluble in their metallic state. — None of the metals are soluble in an acid, in their metallic states, but when first combined with oxygen they are readily dissolved. Gold will not dissolve in muriatic acid ajone, be" cause this acid does not pai-t with its oxygen with such facihty as to form an oxide of the metil. But if. a quantity of nitric acid be added to the muriatic, the gold instantly begins to enter into solution, and a chloride of the metal is formed. If a piece of zinc be thrown into sulphuric acid, it will remain undissolved, but if three or four parte of water be poured in, the metal is attacked with great violence, and soon dissolved. In this case the water furnishes the oxygen, by which the zinc is oxydized, and it is then dissolved by the acid. By this method hydrogen is obtained ; the miBtal decomposing the water by absorbing its oxygen, while the hydrogen is set at liberty. The, metals combine with phosph«rus, sulphur, and car- bon, forming compounds called phosphurets, sulphurets, and carburets, or phosphides, sulpMdes, and carbides. 41 V. Combination with suLPHUR.^Of all the inflammable bases, sulphur appears to possess the strongest affinity for the metals, and ite combination with some of them is attended with remarkable phenomena. This affinity is shown by the following interesting experiment : Introduce into a Florence flask, three parte of iron, or copper filings, and one part flowers of sulphur. In what instances does heat alone reduce the tnerallic ojcidesl When metallic oxides are reduced by means of galvanism, at which pole of the battery Is the oxygen extricated 1 Are any of the metals soluble in the acids, while in their metallic states 1 Why is it necessary tqiarid nitric acid to the muriatic acid before it will dis- solve gold 1 Why does not zinc dissolve in strong sulphuric acid 1 Why is hydro- gen evolved when the zinc is dissolved in diluted sulpjiuric acid 7 When a metal combines with phosphorus, what is the resulting compound called? What is the composition of asulphuret? What is the composftion-of a carburet ? What com- bustible bndy'appears to posses the strongest atnnity for the metals ? What experi- ment is stated, illustrating the affinity between iron and sulphur 1 METALS. 265 well mixed together. Then stop the flask with a cork, and place it over a lamp, so as to heat it slowly, and as soon as any red- ness appears, remove the flask from the fire. The chemical action thus begun, will be continued by the heat evolved by the combination between the sulphur and the metal, and the whole mass in succession will become red hot, which, in the dark, will produce a very beautiful appearance. . We have stated, in a former part of this work, that when bodies pass from a rarer to a denser state, caloric is evolved. The heat and light, in this experiment, seems to be the con- sequence of this general law of condensation, for the sulphuret, formed by the union of the two bodies, occupies much less space than the metal and sulphur did before. Many of the metallic sulphurets are very abundant in nature, forming the ores of the metals. Several metals are extracted entirely from such ores. The most abundant sulphurets are those of lead,, antimony, copper, iron, and zinc. The phosphurets are seldom found as natural products, but may be formed, by bringing phosphurets into contact with the metal, at a high temperature. Carbon unites with iron in several proportions. Unrefined iron, steel, and black lead, are all carburets of iron, the latter containing 95 per cent, of carbon. 418. Metallic salts. — When the oxide of a metal is dis- solved in an acid, there is a compound formed, which differs en- tirely from either of these two substances, and when the liquor is evaporated there remains a crystalline solid, called a metallic salt. These salts difier materialljtfrom each other, according to the kind of acid and metal of which they are composed. Some of them, such as the sulphate of iron and acetate of lead, are of great importance to the arts. The oxides of the metals readily unite, by fusion, with glass, and it is by such means that this substance is mad§ to resemble gems and precious stones. The stained glass, so celebrated among the ancients, and used in the windows of churches, was prepared in this manner. This art was said to -have been lost, but stained glass is still made in many parts of Europe, and in this country. (See Glass.) 419. Allots of the METALS.!?--^C6mpounds, made by fiising Whence does the heat arise in this experiment ? What are the most abundant sulphurets in nature? Are the phosphurets otlen found native? What carburets are mentioned ? What is a metallic salt ? What particular salts are mentioned, as being of^reat importance to the arts? Wh-lt is said of the union between the metaU lit oxides and glass 1 Whril are alloys 1 266 two or more metals together, are called alloys. In these cases there is a chemical union between the metals-; and hence such compounds differ greatly from th« metals of which they are composed. In general, the specific gravity of the alloy is greater than the medium specific gravity of the two metals, and of consequence, the bulk' of the alloy is less than that of the two metals taken separately. As an example, if two bullets of copper and two of iinj of equal bulk, be melted together^ they will form little more than three bullets of the same size. This diminution of bulk is accounted for, by supposing that the par- ticles of the two metals enter into a closer union with each other, when combined, than those of either did in a separate state. The alloys of the metals are also more easily fusible than the metals of which they are composed ; that is, the melting point of an alloy is below the medium temperature at which the metals composing it are fusible. 420. FusiBLB ALLOT. — An alloy, made of 8 parts bismuth, 5 lead, and 3 tin, is a curious instance of. this fact. In a separ- ate state, the melting point of lead is 594 degrees, bismuth, 497 degrees, and tin, 442 degrees, and yet, when these are fused together, the compound melts at 212 degrees. Amusing toys, in the form of tea-spoons, have been made of this alloy. Such spoons, in the hand of those who know nothing of theii* compo- sition, have excited great astonishment, by coming out of a cup of hot tea, with their bowls melted oflf. The number of metals, and the variety of properties which they possess, render it necessary to throw them into classes and orders, that a knowledge of these properties may be more easily obtained. SPECIFIC GRAVITY OF THE METALS. AT 60 DEOKEEE FAHRENHEIT. Platinum, . . . 20.98 Uranium, . . . 9.00 Gold, .... . . . 19.26 Copper, .... 8.89 Tungsten, . . . 17.60 Cadmium, . . . 8.60 Mercury, .... 13.57 Cobalt, ..... 8.54 Palladium, . . . 11.30 Arsenic, .... 5.88 Lead, 11.35 Nickel, .... 8.28 Silver, .... 10.47 Iron, 7.79 Bismuth, . . . 9.82 Molybdenum, . , 7.40 In what reBpect do alloys differ from he metals of which they are composed 1 How is the increased specific gravity of ttie alloys accounted for ? Wtiat is said of ^he fusibility of alloys ? What curious illustration of the fusibility of an alloy ma4e of bismuth) lead, and tiOj is given % CLASSIFICATION OF TltE METALS. 257 ■Kn, 7.29 Zinc, 6.86 Manganese, .... 6.85 Antimony,.* .... 6.70 t CHAPTER XVIII. CLASSIFICATION OF THE BETALS. Tellurium, 6.11 Titanium, ..... 5.30 Sodium, 972 Potassium, 865 V^ 421. The following arrangement is that originally proposed by Thenard, and adopted by Henry and othei-s. "We have already stated, that some of the metals are reduced from the state of oxides by^heat alone, such metals having only a slight affinity for oxygfen. ' Others, it was also stated, have so strong an attraction for oxygen, that they can riot be reduced by this method, but require the presence of a combustible, or some other mean^, for their reduction. The arrangement into classes is founded on this distinctive difiFerence. The orders of the second class are founded on the powers of the metals to de- compose water. Metals, the oxides of which are reducible to the metallic state, by heat alone. These are Mercury, Platinum, Osmium, Silver, Palladium, and _ Gold, Ehodium, Iridium. Metals, the oxides of which are riot reducible to the metallic state by the action of heat alone. Order 1. — Metals which decompose water at common tem- peratures. These are Potassium, Lithium, Strontium, Sodium, Barium, Calcium. what is the distinctive difference between tiie metals, on which is founded the ar- rangement into ciasFes ? What are the peculiar properties on which the. order^ of the second class are founded ? Uow are the classes and orders defined, and what are the names of the metals belonging: to each? How^any metals belong to the first class, and how many to the second ? What is the definition of class first? 22* 258 MBRCURT. Order 2, — Metals which are analogous to Order 1. -They are the metallic bases of the earths. These are Magnesium, Yttrium, Zireonjum, Glucinum, Aluminum, Silicium. Order 3. — Metals which decompose water at a red heat. These are Manganese, Iron, Ifickel, Zinc, Tin, Cadmium. Cobalt, Order 4. — Metals which do not decompose water at any tem- perature. These are Arsenic, Uranium, Titanium, Molybdenum, Columbium, Bismuth, Chromium, Vanadium, > Copper, Tungsten, Lanthanium, Tellurium, Antimony, Cerium, Didymium, Lead, Terbium, Pelopium, Erbium, Rutherium, Donarium. Niobium, The seven last metals in Order 4 are new, and have not, many of them, been so examined as to decide whether they belong to that order or not. They are, however, left there until we ob- tain more light on the subject. It will be seen by the catalogue of elements, that only a part of their combining numbers are known. Of the first class, there are 8 metals ; of the second, there are 41, making 49 in all. Metals, the oxides of which are decomposed hy the action of heat alone. MERCURY, (hTDHARQYRUM.) Equivalent, 100. Symbol, Hg. 422. Mercury, or quicksilver, is found native, or in its pure state, only in small quantities, the mercury of commerce being chiefly extracted from cinnabar, which is a sulphuret of the From what substance is the mercury of commerce extracted ^ What is the com- position of cinnabar, and whut its cbemical name 7 Wtiat isthe method of obtaining the mercury from its sulphuret ? ff MERCURV. 259 metal. The metal is extracted from this ore, by heating it in iron retorts, mixed with iron filings, or lime. By this process, the sulphur combines with the lime, or iron, forming a sulphuret of lime, or iron, while the mercury is volatilized, and is distilled into a receiver, whei'e it condenses in its pure form. ''- This metal is distinguished from all others by preserving its fluidity at common temperatures. Its specific gravity is 13.5. At the temperature of 660 degrees it boils, rises in vapor, and may be distilled from one vessel into another. At 40 degrees below zero it becomes solid, and is then malleable, and may be hammered into thin plates. , i "When pure, this metal is not readily oxidized in the open air at common temperatures, but when mixed with other metals, such as tin, or zinc, there is commonly a film of oxide on its surface ; hence, this is an indication that the mercury is impure. When mercury is triturated with an equal quantity of sulphur, there is formed a black powder, called ethigps mineral. ; y 423. CoMbiNATiON.— Mercury readily combines with gold, silver, tin, bismuth, and zinc ; but not so readily with copper, arsenic, and antimony, and with platina and iron scarcely at all. The resulting compounds between mercmy and the other metals are called amalgams. J <- Mercury has such an affinity for gold and tin as to dissolve tliese metals in small pieces, at common temperatures. In the mines of South Amenea, a great proportion of the gold was formerly procured by ajnidgamation. Sand, containing particles of gold, was agitated in a close vessel with mercury, and the two metals thus brought in contact, united and formed an amal- gam. This was then distilled in an iron vessel," by which the mercury was driven away, while the gold remained. -17 At the present time, lie gold-beaters make use of the same means to obtain the small particles of the metal contained in the sweepings of their shops. The sweepings being placed in a close vessel, and»agitated with mercury, an amalgam is formed. The gold is then separated by pressing the amalgam in a buck- skin bag, which forces the mercury through the pores of the leather, while the gold is retained. ^ n What striking distinction is tliWe DMweenViereary and other metals'! What is the specific gravity of mercurjj? At what temperalure does mercury Jioil, and at what temperature does it freepe? Wlien solid, what properly common to man^ oriier metals does it possess 1 What are the obvious indications of impurity in this metal i What is ethiops mineral % When mercury combines with other metals, what is the compound called? How is gold obtained by mercury? How do gold- beaters obtain the small particles of gold from among the sweepings of their shops I 260 MERCUKT. Mercury is -applied to many other uses in the arts, and is a constituent in several iinportknt. medicines. 424. Silvering looking-glasses. — The silvering on the backs of looking-glasses is an amalgam of tin, and is put on in the following manner : A sheet of tin foil is laid perfectly smooth on a slab of marble, and on the tin foil, mercury is poured, until it is about the eighth of an inch thick ; the attraction of the metals for each' other, keeping the mercury from running offi When'^the -mercury is spread equally over the surface, the glass plate is run or shd on. This is so managed by partly immersing the end of the plate in the edge of the mercury, and pushing it forward, as to entirely exclude the air from between the metal and the glass. Weights are then laid on the plate to press piit ,the mercury, which does not amalgafiadte, with the tin. In about 24 or 36 hours the amalgam adheres to the plate in the manner we see it on looking-glasses. The glass, therefore, merely serves to keep the amalgam in its place, and being trans- parent, to transmit the image which is reflected from the surface of the metal. Could the mercury be kept from oxidation, and be retained in its place without the glass plate, such mirrors would be much more perfect, since the glass prevents some of the rays of light from passing to and from the metal. 425. Permeability of metals to MERODRY.-^It .has long been known that several metals, as tin, lead, and zinc, when dipped in mercury, would absorb a portion erf that metal, and that the latter would rise in the former above its own level, f)er- haps, on the same principle, that water rises in bibulous sub- stances, by what is called capillar^ attraction. Prof, Henry, of the Smithsonian Institute, after various ex- periments on this curi»us subject, discovered the interesting fact that a bar of lead bent into the form of a syphon, would act as a real syphon on the mercury. Thus, when such a bar is placed with its shorter division in a Vessel of that metal, the mercury will rise over the side of the vessel, and drop from the end of the longer division, thus exhibiting the syphon experi- ment, with a solid bar of metal for the tube, and mercury for thejiquid. In respect to the facility of transmission, it was observed that the mercury rose much more rapidly in cast, than in hammered lead, probably because the hammering closed the pores, thus ', .Wh^t is- the composition, called .the silvering, on tile backs of looking-glasses 7 Describe tfie process of silvering a plate of glass. In forming a looidng-glass, what is the use nf the glass plate 1 RED PRECIPITATE. 261 rendering it less permeable than the cast lead. Mercury also penetrates tin, and exhibits with it the syjphpn action more readily than with lead. Several other metals also exhibit the same phenomena, with various degrees of rapidity. The curious reader will find much more on this singular dis- covery by consulting Prof. Horsford's paper, read before the association at Albany. MERCURY AND OXYGEN. PEROXIDE OF MERCURY. Equivalent, 116. Symbol, HgOa 1 eq. Mercury, 100+2 eq. Oxygen, 16. RED PRECIPITATE. 426, This xsompound is commonly formed by dissolving mer- cury in nitric scid, and then exposing the nitrate to such a de- gree of heat as to expel all the acid. It is in the form of small, shining crystalline scales, of a red color. When exposed to a red heat, this oxide is reduced, and converted into oxygen, and metallic mercury, a circumstance on which its arrangement in the present class depends. When long exposed to the action of light, the same effect is produced. Red precipitate is em- ployed in medicine chiefly as an escharotic. It will be observed at the head of this section, that the per- oxide of mercury is composed of 100 parts of the metal, com- bined with 1 6 parts or two equivalents of oxygen. The protoxide of this metal consists of 100 mercury, and 8 oxygen, these coin- pounds conforming precisely to the doctrine of definite and mul- tiple proportions, as formerly explained.. The reason why so large a number as 100 is taken for the equivalent of mercury, and some other metals, will be understood when it is recollected that the data from which all the proportional numbers are es- timated, is the proportions of hydrogen and oxygen forming water. The proportion of oxygen in this compound being 8, tmS this number for oxj^en being fixed, that for mercury is 100, because it is found by experiment, that these are the small- est proportions in which these two bodies combine. What is the composition of peroxide of mercury? By what simple process is it obtained 1 How may this oxide be decomposed 7 What is the use of red precipi- tate 1 Explain the reason why the combining number for mercury is 200. What is said of the combination between mercury and the gas chlorine, at common tempera- tures3 What common name has the protochloride-of mercury ? How does the pro- tochlortde differ from the bichloride of mercury 1 ^Vhat is the common name for the bichloride of mercury ? 262 CALOMEL. MERCURY AND CHLORINE. SUBCHLORIDE OF MERCURY. , Equivalent, 236. Symbol, HgaCl. 2 eq. Mercury, 200+1 eq. Chlorine, 36. CALOMEL. 427. When chlorine, a gas formerly described, is brought into contact with mercury, at common temperatures, a combination takes place between them, amounting to one proportion of each, forming a protochloride of the metal. This, however, is not the common method of preparing calomel; the two constituents being more conveniently combined in their propef proportions, by mixing the bichloride of this metal with an additional quan- tity of mercury. The bichloride 'of mercury contains, as its name signifies, two proportions, of chlorine and one of the metal. This compound is known under the name of corrosive sublimate. It contains mercury 200, and chlorine 72 parts by weight. When this salt is triturated with> mercury, the metal absorbs a part of the chlorine, and the whole is converted into a proto- chloride, or calomel; The proportions are 172 parts, or 1 equiva- lent of the corrosive sublimate, and 100 parts, or 1 equivalent of the mercury. This process aflfords a beautiful illustration of the truth of the doctrine of definite proportions ; for when these equivalents are mixed in a mortar, and then sublimed by" heat, 36 parts, or 1 proportion of the chlorine' is transferred from the bichloride to the metallic mercury, thus converting the whole into 272 parts of protochloride of mercury, or calomel. This process also shows, in a striking manner, the effects of different proportions of the same principles, on the qualities of bodies. Corrosive sublimate is one of the most active and viru- lent of all metallic poisons, and in doses of only a few grains, occasions the most agonizing symptonas, which commonly end in death. But calomel is a mild and safe medicine, which may be taken in doses of 60, or even 100 grains, without injury. And yet the only chemical difierence between these, two sub- stances is, that the calomel is a compound of 1 atom of chlorine combined with 1 of mercury, while corrosive sublimate consists of 2 atoms of the first and 1 of the metal. Wh^t is tbe common mpde nf making calomell What proportions of corroBive sublimate and mercury combipe and form calomell Wliat two principles are etrilviugly illustrated by this combination "i SILVER. 263 MERCURY AND SULPHUR. SDLFHIDE OF HERCUKT. Equivalent, 116. Symbol, HgS. 1 eq. Mercury, 100+1 eq. Sulphur, 16. CINNABAR. 428. Cinnabar is prepared by fusing mercury and sulphur together, and afterward subliming the compound. When this compound is reduced to a fine powder, it forms the well known pigment vermillion. Cinnabar occurs in nature, in lai^e quan- tities, and is the substance, as already stated, from which mer- cury is chiefly obtained. SILVER, (aRGENTUH.) Eqnivalenl^ltOS. Symbol, Ag. 429. Silver is found native in small quantities. It also occurs mixed with several other metals, as copper, antimony, arsenic, and sometimes with gold, but is, chiefly found in combination with sulphur, forming a sulphuret of silver. This metal, when pure, admits of a luster only inferior to that of polished steel. Its specific gravity is 11, being- about half that of platina. In malleability and ductility it excels all the other metals except gold and platina. Silver is fused by the heat of a common furnace, and by a long continued and high degree of heat it may be volatilized, or turned into vapor. By slow cooling, this metal may be ob- tained in T^ular crystals. It is not oxidated by exposui'e to the combing action of heat and moisture, but is readily tar- nished by sulphureous vapor. Sulphuric acid dissolves this metal, when assisted by heat, but its proper solvent is nitric acid, with which it readily combines, and when the solution is evaporated, forms nitrate of silver, a substance known under the name of lunar caustic. Silver is precipitated from its solutions, by sevei-al of the other metals, in its metallic form. Tliis happens when any o'ther metal, having a stronger afiSnity for oxygen than silver, is placed in a solution of this metal. What is the composition of sutphuret of mercury J What is the more common name for this compound? What is vermilion? In what state does silver occur? What are the substance with which it is chietly found combined ? What is its specific gravity ? What is said of its malleability and ductility J How may silver be obtained io crystals ? What vapor readily tarnishes silver ? What is the proper solvent of this metal ? What is the salt formed when silver is dissolved in nitric acid? How is lunar caustic formed? How m.iy silver be precipitated in its metallic foi-m ? 264 SILVER. If a quantity of nitrate of silver, or lunar caustic, be dissolved in water, and a slip of clean polished copper be dipped into it, the copper will be covered with a coat of silver. 430. Diana's silver tree.— Diana's silver tree is made by precipitating silver from its solution, by' means of mercury. -This interesting experiment may be performed in the following manner : Mix together six parts of a solution of nitrate of sil- ver, and four parts of a solution of nitrate of mercury, botb com- pletely saturated. Add a small quantity of rain-water, and put the mixture into a glass decanter, containing six parts of amal- gam, made of seven parts of mercury, by weight, and six parts of silver leaf. In the course of some hours there will appear small shining scales of metallic .silver on the amalgam, which will increase, and shoot out in the fprin of a silver tree, producing a very beautiful appearance. 431. SiLVEHiNo POWDER. — Silvering powder may be pre- pared in the following manner : Precipitate silver from its solu- tion in nitric acid, by dropping into it some plates of clean cop- per. Take 20 grains of this powder, and- mix with it two drams of cream of tartar, the same quantity of common salt, and half a dram of alum. These articles must be finely pul- verized, and intimately mixed in a mortar. If a little of this powder be moistened, and rubbed on a clean surface of brass or copper, the silver will be precipitatedj and the surface of the metal will be covered with it. In this way the silvering of can- dlesticks, or other articles, where it is worn off, may be replaced. The addition of the other articles to the precipitated silver, pro- bably serves no other purpose than to keep the surface of the brass perfectly clean,' and free from oxide, as the powder is nibbed on. 482. Silvering ivory. — Silver may also be precipitated on ivory, and then revived by the action of solar light. Into a dilute solution of nitrate of silver, immerse a slip of polished ivory, and let it remain until it acquires a yellow color, then place it in a tumbler of pure water, and expose it to the direct rays of the sun for a few hours, or until it turns black. If now it be gently rubbed, the surface will be changed into a bright metalhc one, and the slip of ivory will, in appearance, be trans- mitted into one of silver. This change is caused by the deoxi- What ia the process for forming Diana's silver tree 7 How may silvering powder be prepared 1 What is the us6 oftlie silvering powder 7 Of what use are the other ingredients Tn this powder besides the precipitAfed siiverl What is the process for silvering ivory 1 How do yoi) account for the return of the silver to its metallic state by being placed in the sun 1 GOLD. 205 dizing power of the solar rays, in consequence of which the oxy- gen is separated from the silver, and the metal reduced to its former state. A very useful solvent of silver is made by dissolving one part of niter with about eight parts of strong sulphuric acid. This , solvent, when heated to about the temperature of boiling water, will dissolve silver, without acting on gold, copper, lead, or iron, and hence may be conveniently used to extract the silver from old plated goods, &c. The combining number for silver is 108, it having been found that the oxide of this metal contains 108 silver, and 8 oxygen. The sulphuret of silver is "composed of 108 of the metal, and 16 sulphur. /* GOLD, (AnRHH.) Equivalent, 98. Symbol, An. 433. This well known precious metal is found only in the metallic state, either alone, or mixed with other metals ; conse- quently, there is no such thing as an ore of gold. Gold is sometimes found disseminated in rocks, but always in its metallic state, and never mineralized by sulphur, oxygen, or any other sutetance. Its specific gravity is 19. It is the most malleable of all the metals, and in ductility is only excelled by platina. 434. Malleabilitt of gold. — ^The extent to which a given portion of this metal may be spread, and still continue a per- fectly unbroken surface, is truly astonishing. A single grain of the best wrought gold leaf is found to cover fifty-six square inches, and it would take nearly 282,000 such leavra to make an inch in thickness. This, however, is not the utmost limit to which its tenuity may be extended, for the wire used by lace- makers is drawn from an ingot of silver, gilded with this leaf, and from the diameter of the ingot, compared with that of the wire, it has been found that the covering of gold on the latter is only a twelfth part of the thickness of gold leaf. Supposing the leaf; when first placed on the silver, to have been the 30 thou- sandth part of an inch in^ickness, the covering on the wire would require 360,000 tiills its own thickness to make an What istlie composition of a solvent for silver, which does not act npon other metals 1 What is the equivalent number for silver 1 In what state is gold always found 1 Are there any ores of gold? What is the specific gravity of gold 1 What illustrations are given of the malleabUity of gold 1 What is said of.the thickness ol this metal on the wire used by lace-makers 1 23 266 ooLD. inch ; and still this covering is so entire that, even with a micro- scope, the silver is not to be seen. Gold is the only metal which can be made so thin as to trans- mit the rays of light ; and the rays so transmitted, instead of being of the same color with the metal, are green. This -metal, when pure, is not oxidated, or otherwise altered, by being kept in fusion, in the highest heat of a furnace, for any I ,agth of time. Sulphuric, nitric, or muriatic acid, do not, alone, produce' the least action on gold ; but when two parts of nitric and one of muriatic acid are mixed, forming aqua regia, the mixture dissolves this metal with facility! Put some nitric acid into another, and throw a little gold leaf into each. Not: the least effect on either will be produced; but if the contents of one vessel be poured into the other, immediate action will ensue, and the metal will soon be dissolved^. , • The solution of gold is decomposed by many substances which have a stronger attraction for oxygen than this metal has, and by absorbing the oxygen, restores the gold to its metallic state. 435. HrDROGEN precipitates gold. — ^If a piece of ribbon, or other substance, be moistened with some dilute solution of gold, and exposed to the action of a current of hydrogen, the gold will be revived, and the ribbon, or other substance, will be covered with a film of gold. By means of a camel hair pencil, the solution may be applied to the ribbon in regular figures, and as the appearance of the ribbon is not changed by the applica- tion, until the hydrogen is thrown upon it, a striking experiment may be made in this way. The hydrogen must be applied while the ribbon is moist, and may be blown on, through a tube attached to a bladder containing it. 436. Sulphuric ether precipitates gold. ^ — Sulphuric ether precipitates gold, but instantly dissolves the precipitate, forming an ethereal solution of the metal. This solution is sometimes employed to gild lancets, scissors, and other instru- ments, in order to preserve them from rust. This is readily done by the following method. Into a given quantity, say an ounce, of the nitro-mnriatic solution of gold, pour twice as much sulphuric ether ; shake the vessel, and let it stand two or three 'minutes, and then pour into anollfcr vessel about one-third of What is said of the light Been through gold leaf? How is gold affected by contitiued fusion at the highest degrees of heat 1 What acids dissolve gold 1 How may the solu- tions of gold be decomposed ? lu what manner may figures of gold be m'ade on rib. bon I What are the directions for making an ethereal solution of gold % PLATINUM. 267 the mixture. The acid does not mix with the ether, but settles to tlie bottom of the vessel, leaving the ether in possession of the gold on its surface ; the portion decanted into the other vessel, therefore, is an ethereal solution of gold. Any perfectly clean and polished steel instrument will be covered with a coat of gold, if dipped for a moment into this solution. When taken from the ether, it should be instantly plunged into pure water, to wash off any particles of acid which may be retained in the solution. The instrument may afterward be burnished, when it will have all the appearance of the best Riding. In this case the gold appears to be in its metallic state, and to be retained on the surface of the steel by the attraction of co- hesion, while the ether evaporates. PLATDiUM. Equivalent, 96. Symbol, Pt. 437. Platinum is a white metal, resembling silver in color, but a little darker. It is the heaviest of all known bodies, hav- ing a specific gravity of 22. This metal comes chiefly from several parts of South America, where it is found in small grains, or scales, exceedingly heavy, and nearly the color of wrought-iron. In this state it is alloyed by several other metals, and requires to be purified before it is malleable. It was first discovered in 1741, but has not been applied to any considerable use until within the last fifty years. This metal has lately been discovered in considerable quantities in Russia, and is employed for the purposes of coin, for which it is well adapted. . Platina, like iron, may be welded, and like gold, suffers no change from the combined agencies of air and moisture, or by long continued heat. For many purposes, therefore, it is the most valuable of all the metals. This metal is so diflicult of fusion, as to undergo the greatest heat of a smith's forge without the least change ; none of the acids act on it, except the nitro-muriatic, the solvent of gold. 438. How PURIFIED. — Platinum is purified and'obtained in a malleable state by dissolving the grains in 8 times their weight of aqua regia, assisted by heat The acid only dissolves the In what manner may steel instmments besilded with an ethereal solution of gold) What is the color of platinum 1 What is its specific jravity 1 Is there any known body of greater specific gravity than platina 1 In what countries is platina found ? When was this metal discovered 1 In what respect does platina posses the property of iron' In what respect is this metal like gold ? What is said of the action of heat, and of the acids, on platinum 1 How is this metal purified and rendered malleabla 1 268 " PLATINUM. platinum, leaving the iridium and osmium, the metals with which it is alloyed, in the form of a precipitate at the bottom of the vessel. The acid solution is then evaporated, and the metal precipitated by muriate of ammonia. The precipitate thus obtained, is heated in a crucible, lined with a mixture of clay and charcoal, to the utmost degree that can be attained in a blast furnace, when the ammonia and acid are driven off, and the fusftd metal falls to the bottom of the crucible. It is after- ward several times heated, and hammered, when it becomes both ductile and malleable. In small quantities, this metal may be fused by the compound blow-pipe. 439. Allots. — Platinum combines with many of the other metals by fusion, and forms alloys which possess various proper- ties, some of which are useful. Copper, when alloyed witb from one-sixth to one twenty-fifth part of platina, becomes of a golden color, is much less readily oxidated than before, and receives a fine polish. With iron, platina is said to form a cohipound highly es- teemed by the Spaniards, for the purpose of making gun-barrels, which are stronger, and less apt to rust, than iron alone. 440. Uses. — From its infusibility, and the difficulty with which it is oxidated, this metal is highly useful in the arts, and particularly for making various chemical and' philosophical instruments. ■ Retorts of platina are now employed instead of lead, for the distillation of sulphuric acid. Being acted on neither by heat, nor any single acid, such vessels will probably last even &* cen- turies without repair. Their expense would, however, often be an objection to their use. In Mr. Tennant's •great works for the manufacture of bleaching salt, at Glasgow, jt is said there are nine platina retorts, which cost about 2,500 dollars each. 441. Aphlogistio lamp. — Platina is the slowest, or most imperfect conductor of heat among the metals, and from this quality, together with that of sustaining a high degree of beat without oxidation, it may be employed to construct the aphlo^ ffistic, or Jlameless lamp. This curious lamp retains a coil of platina wire constantly at a while heat, without either flame or smoke. It may be constructed in the following manner : The platina wire to be used for this purpose is about the thickness of card, or brass wire. No. 26. If larger, the Does platinum form alloys with the other metals by fusion? PLATINUM. 269 Aphloffistic Lamp. heat is carried oflF too fast, and the ignition ceases ; and if much fiuer, it does not retain sufficient heat to keep up the evaporation of^iie alcohol, by the combustion of which the heat of the wire is main- tained. Such a piece of wire, six or eight inches long, a piece of glass tube, and a low vial, are the chief materials for the construction of this lamp. The coil, a. Fig. 101, is made by winding the wire round a .piece of wood cut of the proper size and shape. ' The size is determined by that of the aperture of the tube, allowing for the diameter of the wire. Its shape is a little conical, or tapering upward. In winding the coil, it is best that the turns of the wire should come in contact, and afterward be gently extended, so as to come as nearly as possible to each other without touching. Tbe diameter of the coil may be one- fourth, or one-sixth of an inch, and its length half an inch, con- taining twenty or thirty turns of the wire. 6 is a glass tube three or four inches long, containing the cotton wick by which the alcohol is carried up to the wire. The wick passes about half way through .the coil, c is the body of the lamp which contains the alcohol. It is a low vial, or glass inkstand, capable of holding two or three ounces. The glass tube passes through a cork, and dips into the fluid, d is a small tube throi^h which the alcohol is poured. This must be stopped to prevent evaporation.' When the lamp is thus prepared and filled with alcohol, the fluid is set on fire by holding the platina wire in the flame ^f a candle, and after a few minutes, or when the -coil becomes red hot, the flame is blown out, and if every thing is properly ad- justed, the wire will remain red hot as long as the vial contains alcohol. What alloys of platina are meotioned as being useftil 1 For what Dsefal parposes lias tile pure metal been employed ? Is platina a good or bad conductor of lieat? What is the apblogistic or Hame'less lamp ? Explain Fig 101, and describe the con* Gtructiou of Ihe tlamelcss lamp. With what fluid is the lamp filled 7 •23* 270 PALLAj3l|M. 442. ■ Explanation.-^ — The following appears to be the causes of the permanent ignition of the wire. Alcohol, when in a state of vapor, combines with oxygen with facility. The temperature of the wire is raised by the flame of the candle to about 1000 degrees, the point at which alcohol combines with oxygpn, or is combustible. When this is once effected, the caloric extricated by the combustion of the alcohol is sufficient to keep the coil at a red heat, which again is the temperature at which alcohol is combustible, so that one portion of alcohol, by the absorption of oxygen, and the consequent evolution of heat, prepares the wire to effect the combustion of another portion, and as the alcohol rises in a constant stream of vapor, so the ignition is constant. Before the invention of friction matches, this lamp was highly cowrenient, for by touching a match to the coil, and then to the wick of a candle, a h'ght was inimediately obtained. Platinum combines with oxygen in two proportions, forming the Protoxide, 1 eq. plat. 96 4:1 eq. oxy. 8. Peroxide, 1 " « 96+2 " "16. PALLADIUM AND BHODIUM. 443. These two metals were discovered by Dr. Wollaston, in 1803, in the ore of platinum. When this ore is digested in nitro-hydrochlorio acid, the platinum, together with the palla- dium, rhodium, iron, copper, and lead, is dissolved ; while'a black powder is left, consisting of osmium -and iridium, mixed in general with a considerable quantity of titanite of iron and insoluble matter. PALLADIUM. Equivalent, 54. Symbol, Pd. 444. This is one of the rare metals, and is obtained in its pure state with difficulty. It resembles platina in color and luster. It is malleable and ductile, and is much harder than platinum. Its specific gravity is about 11.8. Its fusibility is intermediate between gold and platinum, and when intensely heated by the oxy-hydrogen blow-pipe, is dissipated in sparks. How is it lighted 1 Explain the principles which caiase the permanent ijrnition of the platina wire. What is the use of the aphloffisticlamp ? What is the equivalent number for platinum 7 What are the names of the oxides of this metal, and what the proportionsof their elements? Where were the metals palladium, rhod'um, iri- dium, and osmium, first discovered 1 What is the combining number for palladium 7 Osmium' AND iridium. 271 It is oxidized and dissolved by nitric acid, but its proper solvent is nitro-hydrochloric acid. Its protoxide forms beautiful red salts, from which metallic palladiuni is precipitated by the sul- phate of proxide of iron. Its compounds are not numerous, though it combines with oxygen in two proportions, forming a protoxide and a bhioxide ; with chlorine, forming the proto^ chloride and the bichloride, and with sulphur, -forming the protosulphuret. ^ RUODIDM. Equivalent, 52. Symbol, R. 445. On imraei-sing a plate of clean iron into the solution from which palladium and most of the platinum have been pre- cipitated, the rhodium, with small quantities of lead, copper, and platinum, is thrown down in the metallic state. The rho- dium is afterward separated by means of several processes not necessary to detail. . It is procured in the form of a black pow- der, which being fused by- the strongest heat of a wind furnace, produces the metal in question. Its color is white, with a me- tallic luster, and a specific gravity of about 11. It is extremely hard, scratehing hardened steel, and is not attacked by any of the acids in its pure state. Chemists are acquainted with two oxides of rhodium, and several salts, which are either red or yellow. It is only soluble in acids when alloyed with other metals. Use. — It is employed for the points of metallic pens, for which, owing to its extreme hardness and insolubility in acids, it is ad- mirafbly adapted. The gold pens of the present day owe their lasting property to this metal. OSMIUM AND IRIDIUM. 446. These metals owe their discovery to Mr. Tennant, in 1803. The black powder, mentioned at the beginning of this article, as containing these metals, is the source whence they were obtained. The manipulations resulting in obtaining them in the pure state, are long and difficult. Wliat is the specific ffravity of rhodium ? What is the color, and what are the pro- perties of rhodium ? From what circumstance is the name of this metal derived t What is the equivalent number of rhodium? How are iridium and osmium ob. tained 1 What is the specific gravity of iridium 1 What is said of its fusibility, and solution in acids I 2V2 IRIDIUM. Equivalent, 100. Symbol, Os. 44V. This metal appears at first in the form of a porous mass, which acquires metallic luster by_ friction. It takes fire "when heated in the open air, and is readily dissolved by nitric acid. In its, densest state its specific gravity is 10.^ It combines with oxygen and the acids, forming many compounds, which our limits do not allow us to describe. OsMic ACID. — This is the product of the oxidation of osmium by acids, or by combustion. It is in the form of elongated, transparent crystals, having an exceedingly acrid vapor, exciting cough, producing tears, and a copious flow of saliva. Its odor is disagreeable and pungent, somewhat like that, of chlorine, and this property suggested its name from a Greek word signifying odor. Neither the metal, nor its compounds, have been applied to any use. IRIDIUM. Equivalent, 99. Symlwl, Ir. 448. This is a very brittle metal, and, without care, will fall into powder in attempting to burnish it. When polished, it resembles platinum in color and luster. Of all known metals it is the most infusible. Berzelius never succeeded in melting it, but Mr. Children, with his immense galvanic batteryrfused it into a brilliant metallic globule of a white color, having a specific gravity of nearly 19, being, in respect to this property, next to platinum. Iridium combines with oxygen and chloric acid, forming oxides and chlorides. CLASS II. 449. Metals, the oxides of which are not reducible to the me- tallic state hy heat alone. Order 1. — Metals which decompose water at common tem- peratures. These are Potassium, Lithium, Strontium, Sodium, Barium, ■ Calcium. what are the pro])ertiefi of osmium 7 How is osmium obtained in its ^ure state! What is the denniticn of Class I1 1 What is the iJelinition of Order 1st, of this class 7 What arc the names of the metals belonging to this order 1 POTASSIUM. 273 These metals attract oxygen with the most intense degi-ee of force. They absorb it from the atmosphere, and even decom- pose water, by combining with its oxygen, at common tempera- tures. Such is the force by which they hold this principle, that their oxides had resisted all attempts to decompose them, until the discovery of galvanism placed in the hands of men a more powerful decomposing agent than was before known. By means of the most intense electrical repulsion, the alkalies, before considered as simple bodies, were shown to be the oxides of metals. After the secret of their composition was known, chemists devised other and less expensive means of eflfecting their decompositions, so that at the present time, sodium and potassium, at first the most expensive of all substances, are within the means of any one. poTAseiuM, (kauum.) Equivalent, 40. Symbol, K. 450. Decomposition of potash. — If a small piece of pure potash, slightly moistened, be put between two plates of pla- tinum connected with the poles of a galvanic battery of 200 double plates, the alkali will soon be fiised and decomposed. Oxygen will separate at the positive poles, and small metallic globules, like quicksilver, wiU appear at the negative pole. In this manner. Sir H. Davy first determined the composition of potash, and separated its elements. Potash, therefore, is a compound consisting of a metal called potassium, united to oxygen. By this process the metal- can be obtained only in minute quantities ; but chemists, now understanding that to obtain potassium in any quantity, only required that the oxygen should be separated from the potash, soon found more ready means of performing the experiment. 451. Decomposition by charcoal. — ^Inthe former editions of this 'work, Thenard's process for the making of potassium was given, illustrated by a diagram. In this process, the de- composition was eflTected by means of a heated gun-barrel, con- taining iron turnings, the oxygen of the potash bding absorbed by the iron at a high heat. It has since been discovered that the decomposition can be performed more readily by charcoal What is said ofthe intense degree of force with whicli these metals attract oxygen? By what decomposing agent were the alkalies shown to be the oxides of metalsl What is the process by which Six H. Davy decomposed potash 1 274 poTASti. than by iron, and hence, at present, this forms the bases of the process for potassium, now always followed. The process, how- ever, requires more apparatus, and more chemical experience than usually pertains to the students of this humble treatise, and we have, therefore, omitted the description and apparatus for this purpose in this edition, referring the inquirer for a com- plete account of the process, with explanatory diagrams, to the last edition of Graham's Chemistry, Part L, page 370. There he will find an extended account of the most recent methods of obtaining this most interesting and curious metal. 452. Potassium is solid at ordinary temperatures, but be- comes fluid at 150 degrees, and then appears like mercury. It is perfectly opaque, and a good conductor of electricity and caloric. At the temperature of 50 degrees, it is soft like wax, and yields to the pressure of the fingers. In this state it resem- bles an amalgam of mercury and tin. Its specific gravity is 0.865, water being 1.000. The most prominent chemical property of this metal is its ex- treme avidity for oxygen. When exposed to the air it oxidizes rapidly, and when thrown on water it decomposes that fluid, by absorbing its oxygen with such rapidity as to set itself on fire, and burns with a white flame, and great evolution of heat, while swimming on its surface. POTASSIUM AND OXYGEN. PROTOXIDE OF POTASSIUM. PKOTOXJDK OJf POTAHHlUm. Equivalent, 48. Symbol, KO 1 eq. Potassium, 40+1 eq. Oxyi eq. Oxygen, 8. 453. Potassium combines with oxygen in two proportions, forming the protoxide and peroxide of potassium. The first, which is common potash, is formed whenever potassium is put into water, or exposed to dry air, or oxygen gas. The proportion of oxygen which this metal absorbs, to con- vert it into potash, is readily ascertained by the volume of hy- drogen liberated when it acts on water. For, when potassium What is the principle on which the decomposition of the potash is eifected by means of iron turnings and iieatl What is the appearance 01 potassium ? Is it a conductor of caloric and electricity t At what temperature does it become fluid, and at what temperature is it solid 1 " What is the speci He gravity of this metal ] What phenomena are produced when potassium is thrown on water 1 In how many pro- portions does potassium combine with oxysen 1 What common substance is formed when potassium is exposed to the air i When potassium is plunged under water, bow is it a^rtftin^ what quantity of oxygeu it alxorbs 1 POTASH. 2^5 is plunged at once under that fluid, it is oxidized without the evolution of light or heat, and it is found that each grain of the metal so placed, separates 106 cubic inches of hydrogen gas. Now, by Mowing previously what are the relative volumes and weight of hydrogen and oxygen composing water, it is easy to calculate the exact quantity of oxygen absorbed by the above data. . , Thus,. Sir H. Davy found that 40 grains of this metal decom- poses precisely »0 grains of water. Now, as 9 grains of water IS cpmposed of 1 grain of hydrogen, and 8 oxygen, so 40 parts of potassium combines with 8 parts of oxygen, to form oxide of potassium, or potash. Potash js therefore composed of Potassium, 1 eq. 40 ^Oxygen, 1 eq. 8=48. 48 combining number for potash. When potassium is allowed to absorb oxygen in the open air, or when plunged under water, it combines with only one propor- tion of oxygen, as above stated. But when this metal burns in the open air, or in oxygen gas, it is converted into an orange colored substance, which is the peroxide of potassium. This is composed of Potassium, 1 eq. 40+3 eq. Oxygen, 24=64. 454 The potash of commerce is obtained from the lye of wood ashes, boiled down in pots, and hence the name potash. It is chiefly used in the manufacture of soap and glass. For the former purpose, the lye itself is often employed, and is better than the solid potash, dissolved in water, since the potash soon absorbs carbonic acid, and then its quality for soap-making is in a great measure destroyed. From this circumstance it is, that soap-makers mix with their lye a quantity of newly burned quicklime, which renders the solution of potash caus- tic, by absorbing from it the carbonic acid, with which it has combined. Soft soap only can be made from potash, while hard soap is made from soda. Common green glass is made by fusing sand and wood ashes Suppose 40 grains of potassium decompose 9 grains of water, how does it appear in what proportion potassium and oxygen combine ? What is the equivalent jium? ber for potash ? When potassium is burned )□ the open air, or in oxygen gas. what proportion of oxygen does it absorb % What is the oxide called which is so formed ? How is the potash of commerce procured ? In what manufactures is the article chiefly employed? What is the use of quicklime in soap-makingl How do the soaps made from pg^asii and soda differ*) \Vhat are the piattriUs for making green g'aesi 276 SODA. together, by means of an intense heat, produced by the combus- tion of dried wood, in a blast furnace. Flint glass, which is per- fectly white and transparent, is made by fusing together a quan- tity of potash and white sand, or ground quartz^ to which are added a proportion of lead, and a Uttle manganese. Salt of tartar, salt of wormwood, pearl-ash, and carbonate of potash, are only different names for the same article, some of which are more pure than others. BODIDM, (nATBON.) Equivalent, 24. Symbol, Na. 455. By the same process which showed potasfc to be a compound body, soda was also found to be of the same nature. Although first procured by means of galvanism, it may be ob- tained by precisely the same method as that described for the production of potassium, only placing soda in the gun-barrel, instead of potash. Sodium has a strong metallic luster, similar to that of silver. It is a little less fusible than potassium, not becoming perfectly fluid until it has acquired the temperature of nearly 200 degrees. Tts specific gravity is somewhat greater. than that of potassium, being 0.9Y2. When thrown on water it produces a violent effervescence, but does not inflame like potassium. Xhe water is decomposed by its action, hydrogen escapes, and there re- mains a solution of soda in the water. Like potassium, it must be preserved in a vial, covered by naphtha — a substance which cont^ns no oxygen. SODIUM AND OXYGEN. PROTOXIDE OF CODIUM. Equivalent, 32. Symbol, NaO. 1 eq. Soda, 24 -fl eq. Oxygen, 8. eODA. 456. When the metallic base of soda is burned in dry atmos- pheric air, protoxide of sodium, or soda, is formed. The same • What are the mal erials for making flint glassi What other names are applied to potash 1 What is the process of decomposing soda, and obtaining the metal sodiuiml Wiiat is the appearance of sodium ? In what respects does this metal differ from potassium 1' What is the effect when sodium is thrown upon water 1 How is the metal preserved 1 What compound is formed when sodium is burned In atmos- pheric air, 'or thrown into water % What is the oOmpoBillon of protoxide of sodiUin, or soda ? COMMON SALT. 277 compound is formed when sodium is thrown into water, and the composition may therefore be determined in the manner already described for potassium. From such an experiment it has been found that soda is composed of Sodium, 1 equivalent, 24 Oxygen, 1 " 8 32 equivalent of soda. The peroxide of soda is composed of the same equivalent of sodium, with two equivalents of oxygen. Sodium, 24, oxygen, 16 — 40. i S^9da is readily distinguished from other alkalies by the fol- lowing characters. With muriatic acid it forms the common table salt, with the taste of which every one is familiar. With sulphuric acid it_forms Glauber's salt, or sulphate of soda. All the salts of soda are soluble in water, and are not precipitated hy any other substances. SODIUM AND CHLORINE. CHLORIDE OF SODIUM. Equivalent, 60. Symbol, NaCI. 1 eq. Sodium, 24+1 eq. Chlorine, 36. COMMON SALT. 457. When sodium is exposed to chlorine, or is heated in muriatic acid gas, the salt is formed, well known under the name of muriate of soda, or common salt. This is an abundant product of nature, and exists ready formed in Spain, England, Poland, and other countries, in large quantities. In these countries it is dug out of the earth, and is known by the name of rock salt. Sea water and certain springs also contain this salt in solution. When common salt is dissolved in water, and the solution is evaporated rapidly, it crystallizes in the form of hollow four- sided pyramids ; but if allowed to evaporate spontaneously, it occurs in regular cubes. Thus, the crystals show in what man- ner the salt has been manufactured. In England, vast quanti- What is the equivalent number for sodal How is soda distinguished from the other ailtalies 1 What is chloride of sodium ? What the sources of cnmmoD salt 7 Wlien a solution of common salt is evaporated rapidly, what is the form of its crys- tals? When evaporated slowly, in what form are the crystals t Where are the salt mines of England J What impurities exist in the Cheshire rook salt J 24 278 COMMON SALT. ties of salt are annually raised from the mines, chiefly of Ches- hire, and purified for sale. The impurities consist chiefly of clay and oxide of iron, besides which, it contains various pro- portions of sulphate of magnesia, or Epsom salt, sulphate of lime, and muriate of lime. It is purified by being dissolved in sea-water, and subsequently evaporated. Formerly, all the English salt was evaporated by artificial heat, the brine being bulled until it was ready to shoot into crystals. Its crystals were, therefore, always in the form of hollow pyramids. But it Lr.s been supposed, by victualers and others, that this salt is far less efficacious, as a preserver of animal food, than that prepared by^ the spontaneous evaporation of sea-water in hot climates. Hence, salt from the West Indies, which is crystallized in s'oM cubes, has been preferred for curing provisions for- long voyag-es, or for summer use. In this country, although immense quan- tities of common salt are manufactured, by the evaporation of water from salt springs and from the sea, and a'sufficient supply for our consumption might be made, yet we annually import large quantities from the West Indies, there having been, until lately, an opinion that no other kind of salt would preserve animal substances through the hot season. 458. Dr. Henry, for the purpose of ascertaining the difference between English salt, crystallized by heat, and that from the West Indies, crystallized by spontaneous evaporation, analyzed many specimens of each. The result showed the presence of sulphate of magnesia and sulphate of Ume in both, but the dif- ference in the quantity of muriate of soda, in several specimens of each kind, was so trifling, as to make no possible difference in respect to their preserving qualities. It is presumed, therefore, that the prejudices in favor of foreign salt ought to be discarded as imaginary, and that equal weights of fine 'Or coarse salt, whether made by artificial, or spontaneous evaporation, are equally eiBcacious for all purposes. Common salt contains no water of crystallization, but decrepi- tates remarkably when heated, owing to the conversion of the water into steam, which is mechanically confined within its crystals. Its solubility is not, like most other salts, increased by How is this salt purified ? Why were the crystals of this salt always in the form of hollow pyramids J What salt was formerly supposed best for the preservation of animal substances 7 What is said of the real difference between salt made by rapid or slow evaporation ? Does common salt contain any water of crystallization T Why does common salt decrepitate, or lly in pieces, when thrown upon afire? Is the solubility of this salt, increased by heat ? What quantity of water does it require for 279 heati and it requires two and a half times its weight of water for solution, whether hot or cold, j Equivalent, 6.43. Symbol, Ij. 4S9.. Lithia is an alkaline substance, discovered by Mr. Arf- wedson, a Swedish chemist, in 1818. It exists in the minerals called spodumene, and lepidolite, and also in some varieties of mica. This alkali is distinguished from potash and soda, by its power of neutralizing larger quantities of the different acids, and by its action on platinum, when melted on that metal. In respect to its metallic base, called lithium, Sir H. Davy succeeded, by means of galvanism, in obtaining a white metal from lithia, similar in. appearance' to sodium, but it was oxidized so rapidly, and reconverted into the alkali, that it could not be collected. Lithium combines with several acids, forming salts of various kinds, as the carbonate of lithia, sulphate of lithia, &c. It also unites vrith sulphur, formiiig the sulphide of lithium. Lithia has been procured only in very small quantities, and has never been apphed to any useful purpose. Equivalent, 69. Symbol, Ba. 460. There is a substance called sulphate of barytes, which is found abundantly in nature. By the decomposition of this sub- stance, an alkaline earth is obtained, called baryta, or barytes. When barytes, in the form of paste mixed with water, is ex- posed, in contact with mercury, to the action of a powerful gal- vanic battery, its decomposition is effected, and tlie metal barium, its base, amalgamates with the mercury. The amal- gam being exposed to heat, the mercury is driven o^ and pure barium remains. The metal thus obtained, is of a dark gray color, with a lus- ter inferior to cast-iron. It fiises at a heat below redness, and at a red heat is converted into vapor, which acts violently npon What is lithia? la what miuerals isthis alkali fonnd? How is lithia distingnished from potash and sods? What is known concerning the metallic base ofthi^ alkali 1 What are the equivalent numbers of lithium and lithia? How is baryta obtained? By what process is barium separated from baryta? What is the color of bar'Um? At what temperature is barium fiisible ! What is the specific gravity of barium 1 280 BAEYTES. glass. The specific gravity of barium is four or five times that of water. When exposed to the air it falls into a white pow- der, which is found to be an oxide of barium, or barytes. When heated in oxygen, it burns with a deep red light, and when thrown into the water, the fluid is decomposed, hydrogen being extricated. BARIUM AND OXYGEN. PKOTOZIDE OF BAEIUM. Equivalent, 77. Symbol, BaO. 1 eq. Barium, 69+1 eq. Oxygen, 8. BARYTES. 461. When the metal barium is exposed to the air it falls into a powder, which was formerly called pure barytes, or baryta, but which Sir H. Davy has proved by the above-stated experi- ment,' to consist of a metal and oxygen. This substance is, therefore, called oxide of barium. Oxide of barium may also be obtained by a different process from that above described, viz., by exposing the carbonate of baryta to an intense heat, mixed with charcoal. The carbonate of barytes is found native in small quantities, but may be obtained from the sulphate of barytes by a simple process. Mix sulphate of barytes in fine powder, with, three times its weight of carbonate of potash, (pearl-ash,) and a proper quantity of water. Let the mixture boil for an hour, now and then breaking the lumps into which it is apt to run, with a pestle. By this means the two salts will decompose eachj)ther, and there will be formed carbonate of barytes, and sulphate of potash. The carbonate may now be exposed to a high heat, or it may be dissolved in_ nitric acid, and thus decomposed, which is effected by a moderate heat, when protoxide of barium, or barytes, will be obtained. This substance is of a white color, has a sharp caustic taste; changes vegetable blue colors, to green ; neutralizes acids, vrith which it forms salts, and is a strong poison. When water is thrown on it; it falls into fine powder, like quicklime, but with a greater evolution of heat. When barium is exposed to, the air, what compound is formed 7 When thrown .nto water, what etFects are produced ? By what process may barium be obtained without the agency of galvanism '( How may carbonate of barytes be extracted from the sulphate ? What are the properties of barytes, or protoxide of barium ? What is the composition of barytes? In what quantity of water is barytes soluble ^ Why is barytes a test for carbonic acid 1 STRONTIUM. 281 Barytes is composed of 1 equivalent of barium, .... 69 1 " " oxygen, .... 8 The equivalent combining number for baryte^ 77 Barytes is soluble in about twenty parts of water, at common temperatures, and this solution forms a delicate test for the presence of carbonic acid. The carbonate of barytes being inso- luble in water, a white cloud is instantly formed by the union. Equivalent, 44. Symbol, Sr. 462. The sulphate and carbonate of strontian, or strontia, are native salts. They consist of pure strontian, combined with sulphuric and carbonic acids. From the sulph'ate, the car- bonate may be procured by precisely the same means as already described for barytes, and the pure oxide may also be obtainedj and the metal strontium separated from it, by the same process as that described for barytes. Strontia resembles baryta in most respects. It slakes in water, causing an intense heat, and possesses distinct alkaline properties.- The metal strontium is similar to barium in appearance, and when exposed to the air quickly attracts oxygen, and is con- verted into strontia. _ Perhaps the principal diflference between these two substances, which has been detected, is their different combining proportions with oxygen, and the inertness of the oxide of strontium on animals. ^ The protoxide of strontium consists of Strontium, 1 equivalent, 44 Oxygen, 1 " 8 52 The oxides of barium, as already stated, are strong poisons, but those of strontium are inert. How is the carbonate of strontian produced from the sulphate? How is the pore earth strontia obt^ed trom the carbonate 1 By what process is the metal strontiom separated from stronlial What is the appearance of this metall What is tile com- position of strontia, or the protoxide of stroDiium 1 What is the combining number of strontia? Wtiat is the difference between strontia and baryta? 24* 282 Equivalent, 20. Symbol, Ca, 463. When carbonate of lime, or white marble, is exposed to a red heat, the carbonic acid is expelled, and there remains a white caustic«ubstance, well known under the name of quick- lime. "WJien this substance is exposed to the action of galvan- ism, in the same manner as already described for the decompo- sition of barytes, calcium, the metallic base of lime, is separated. This metal is of a whiter color than barium, and ha.s a luster like silver. When exposed to the air, it absorbs oxygen, and is converted into quicklime; and when thrown into water, the fluid is decomposed, its oxygen being absorbed, while hydrogen is given oflF, and a solution of lime remains. 464. Artificial marble. — To Mrs. Marshall, of Edinburgh", we are indebted for the following singular, and perhaps important suggestions and experiments, as detailed in Chambers' Journal. In about 1840, Mrs. Marshall was struck with the singular ideaj that the animal and vegetable remains so universally found in certain atrajta of the earth, might, by a chemical or electric in- fluence exerted upon the disintegrated particles of these rocks, have been the cause of their aggregation. The result of numer- ous experiments undertaken by herself, has, she states, satisfac- torily demonstrated, that if the constituents of any mineral body of which Hme forms a part, be mixed in their true propor- tions, (tlie lime used being free from carbon in any form,) and these mixed with animal and vegetable remains, under circum- stances of due moisture and heat, aggregation of their particles will take place, at periods varying with the substances under ex- periment, from a few minutes to hours, weeks, and months. These artificial aggregations, allowing for shortness of time and amount of superincumbent pressure in the natural phenomena, come so undeniably near, in appearance and qualities to the products of nature, as to throw a totally new and interesting light on some of her hitherto most mysterious operations. Mrs. Marshall's experiments show, that if a mass, in imitation of a native mineral aggregate, be prepared, and one portion left at rest, while another portion is agitated or disturbed, the first will harden in a few hours or days, into a substance not to be distinguished by the eye from the natural stone, and capable of ^yhat.iB quicklime'? How may quicklime be decomposed, and calcium, Its merallic base, be separated 7 What is the appearance of calcium 1 How is calcium converted into quicklime? What eifect is produced when calcium is thrown into water J Give an account orMrs. Marshall's method of making artificial marble. QUICKLIME. 283 resisting water and weather, while the other portion will take as many weeks to harden, and will, then present a mass which will fall in pieces by exposure to either. These experiments are, to all appearance, worthy of general consideratjon and further tiial, for if durable stone can be made from the useless chips and refuse of marble quarries, the result may be of vast benefit to the world. . CALCIUM AND OXYGEN. OXIDE OF CALCIDH. Eqnivaleut, 98. Symbol, CaO. 1 eq. Galdum, 20+1 eq. Oxygen, 8. m the air. When heated, it attracts oxygen both fi-om air and water, with great rapidity. When the steam of water is passed over iron, at a red heat, the water is decomposed, its oxygen combining with the metal, while the hydrogen is set at Uberty. When heated to redness, in oxygen gas, it burns with intense biilliancy. Iron is exceed- What is the scientific name for black oxide of manganese 1 When peroxide of manganese is heated to .redness, what chemical change does it underage ? Of what numberf , . ^ . said of the affioUy of iron for oxygen ? Under what circumstances does iron decom.' pose water 1 In what dots t..is decomposition consist 1 298 mos. ingly ductile, and may be drawn into wire not exceeding tlie thousandth part of an inch in diameter ; but it can not, like gold and silver, be hammered into thin leaves, and therefore is not highly malleable. The ores of this metal are very numerous, and some of them highly beautiful and interesting. They are chiefly sulphurets and oxides, but the oxides are the ohly ores from which the metal is obtained. Iron'has, in a few instances, been found in its native state, mixed with lead and copper, or with some earthy substance. It has also been found in large masses, alloyed wilii five or six other metals, and called wifiieoric iron, from an o^nion that these masses fell from the clouds. Native iron is soft and mal- leable as it occurs, and does not differ from that which has been reduced from its ores and purified. Cast-iron contains variable proportions of carbon and oxygen, and in this state it is hard and- brittle. These impurities are detached by the process of refipiiig, and then the iron becomes soft and malleable. 491. SiBEL.-^Steel is made by heating pure iron with car- bon, or charcoal, by which it is rendered exceedingly' hard and brittle. This change is produced in consequence of the absorp- tion of a pttrtion of carbon by the iron. Steel, therefore, is composed of iron and ckrbon, and its scientific name is carburet of iron. 492. Coating iron with other metals. — Messrs. Gressel and Eedwood, of London, have recently patented the following methods of coating iron with zinc, and other metals. The zinc is melted in an open vessel, and on its surface is placed a layer of chloride of zinc, or a mix,ture of equal parts of chloride of zinc and chloride of potassium, in the proportion of eight of the former and two of the latter. When the chloride on the sur- fape is in a state of fusion, the sheets of iron to be coated are placed in the melted zinc, and allowed to remain there for a short time, or until a coating of sufficient thickness adheres to it, when it is withdrawn. If any part of the surface is imper- fectly covered, this is sprinkled with the sal ammonia, and the sheet of iron again immersed in the zinc bath. 493. To COAT IRON WITH SILVER. — The iron must first be What is said of the ductility and malleability of iron 7 la w^at state does iron oc cur as a natural product ? What is the ore from which iron ie extracted 1 What is meteoric iron "J What are the impurities contained in cast'ironi How is steel made ) What is the composition of steel ! BUST OF lEON. 299 covered, or amalgamated with mercury, by the following pro- cess: 12 parts, by weight, of mercury, 1 of zinc, 2 of sulphate of iron, 2 of muriatic acid, and 12 ^f water, are mixed together and heated in an open vessel to about 2.00 degrees Fahrenheit. Into this the iron is immersed, and while warm, the mercury is rubbed on the surface until it adheres by amalgamation. The silver, haying been melted ih a -crucible, the amalgamated iron being 'dipped therein, a coating of the 'silver yrill be deposited on its sutfacev , IRON AND OXYGEN. OXIDE OF mON. * RUST OP IRON. 494. Iron combines with oxygen in two proportions, forming the blue and red oxides of tMs metal., 495. Protoxide of iron. — The black, or protoxide of this metal, is formed by passing dry hydrogen over the red oxide, at a terdperature a little below redness. This oxide is composed of 1 equivalent of iron, 28, and 1 equivalent of oxygen, 8. Its combining number, therefore, is 36. Symbol, FeO. 496. The black oxide of iroJt, which occurs in the form of scales, when iron is heated, and hammered in the open air, is not a definite compound, but a mixture of the black ©xide, and metallic iron. 497. Peroxide of iron. — This is the red oxide, and is known to mineralogists as a native compound, under the name of RED HEMATITE. The samc article is Isjipwn to button-makers, and other artists, under the name oi blood atone, and is em- ployed to polish their work. The peroxide may be prepared by art, by dissolving iron in nitric acid, then precipitating it with ammonia, and heating the precipitate to a little below red- ness, to drive off the acid. Its color and. other properties are like those of the native red oxide. Tlie peroxide of iron is com- posed of iron, 28, and oxygen, 12. 498. The b'bown oxide of iron is composed of precisely the same proportions of the metal and oxygen as the red oxide, but in addition to these ingredients, it contains one proportion, or 9 parts of water. What is the scientific name of steel 1 What is the method of coating iron with zinc ■! How may iron be coated with silver 1 In how ipany proportions does oxygea conibinewlth iron? What are the names of these oxides'! What Js the composition of the protoxide? What is the composition of the peroxide of iron 1 How does the brown differ from the red ctido of iron 7 300 RUST OF IRON. The other oxides of iron are eithei- mixtures of the red and blue oxides, or one or both of theSe oxides containing various impurities. The great number of oxides of this metal, described in books of mineralogy, and differing from each other in color, hardness, and form, arise from such mixtures. Thus, the mag- netic oxide of iron, or native magnet, is composed of peroxide of iron, 71, and protoxide 29 toTihe 100. The brown oxides of iron all contain water, and are, therefore, callei hydrates. The ochres are of this kind. Iron combines with carbon, sulphur, iodine, phosphortis, and the different acids. Its compounds are, therefore, exceedingly various, in respect to form, color, and properties. We shall, however, examine only two or three of these compounds here, the salts being reserved for another place. 499. Cakburbt of iron. — Steel, we have already said, is a carburet of iron. This important metal is manufactured from the iron, by exposing the latter to a long continued red heat, in contact with charcoal.' For this purpose, the purest malleable iron, in bars, is employed, and is found to gain in weight, one pound in 150, by the process. Steel, therefore, consists of iron combined with a ISOth part of its "weight of carbon, which it absorbs from the fire. When iron is perfectly inclosed, and heated with a fragment of diamond, it is converted into steel, in the same manner as when heated with charcoal. This ex- periment Shows the identity of carbon and diamond, the only difference being the color and crystalline form of the latter. It also provgs that the hardness of steel is owing to the particles of diamond which it contains. The native carburet of iron, commonly known under the name of black lead, or plumbago, contains 95 parts of carbon and 5 of iron. This substance is infusible at the highest heat of a furnace, and hence is employed in making crucibles and melting-pots. It is also used in making black lead pencils. 500. Sulphide of iron. — This compound occurs as a natural product, and is known to mineralogists and others un- der the name of iron pyrites. It is a yellow brittle substance, often crystallized in the form of cubes,' or octahedrons, with their surfaces highly polished. These specimens are generally What is the compositiou of the native magnet 1 What substances are mentioned with which iron combines? In what proportion is the weight of iron increased by being converted into steel t What is said of converting iron into steel by means of the diamond ? What does this e^fnerimcnt prove 1 What is the composition and the proper name of black lead 1 what am the iiBes of black lead 1 Is eulpburet ol tron a natural, or artificial compound 1 301 taken for gold, by those who are.ignorant of such matters, and the places where they are found are sometiines kept a profound secret, for years, for fear the owner of the soil should claim a part of the wealth. Every mineraiogist, on pronouncing such specimens of no value, has occasionally witnessed the fallen countenance of the applicant, whose hopes and expectations he had thus blasted. Sulphide of iron may also be formed by touching a bar of iron, at a glowing red heat, with a roll of brimstone. The compound will fall down in drops. The natural and artificial snlphurets are composed of precisely the same definite proportions, viz., iron, 28, and sulphur, 16. E^mvalent, 32. Symbol, Zn. 501. Zinc, when pure, is of a, bluish white color, and of a striated fracture, presenting the result of a confused crystalliza- tion> When rubbed with -the fingers it imparts to them a peculiar metallic taste and smell. When cold, this metal is not maDeable, but when heated to between 200 and 300 de- grees, it becomes both malleable and ductile. If its tempera^ ture be raised to 400 degrees, it becomes so brittle as to be readily reduced to powder, in a mortar. Zinc melts at 680 degi«es, and if this temperature be in- creased, it bums with a bluish flame in the open air. When melted with copper it forms the alloy, weU known under the name of brass. . 502. Calamine.^ — Zinc never occurs in the native, or pure state, but is always found combined either with sulphur, car- bonic acid, or oxygen. The sulphuret of this metal, called zinc blende, and the carbonate, called calamine^ are the ores from which zinc is obtained. The sulphuret being roasted, that is, submitted to a low red heat in the open air, to drive off the sul- phur, and oxydize the metal, is then melted with charcoal, by which the oxygen is absorbed, and the metal reduced. The calamine is first roasted to drive off the carbonic acid, and is then distilled in iron retorts, by which means the pure metal is obtained. This latter process is said to have been learned of What is the appearance of the native sulphoret of iron t What precious metal is this compound sometimes taken for 1 How may sulphuret of iron be formed arti- ficially 7 What is Ihe composition of sulphuret of iron 7 What is the color of pure zinc 7 Under what circumstances is'zinc malleahle? In what temperature does zinc meltl What is the composition -of brafs? Is zinc ever found in the native state 1 What are the names of the ores of zinc, and of what are they composed ? How is zinc reduced from it£ sulphuret ? How is calamine reduced i 28 S02 FLOWERS 6f ZINO. the Chinese, and that a man was sent from Europe to China on purpose to obtain the secret. Pure zinc, when exposed to a white heat in a close vessel, will in the same manner sublime, and again condense, unchanged, 503. Malleable BRAss.^It is well known that brass, as it is usually made,' is very brittle, whether hot or cold. This de- pends, it appears, on the proportions of the zinc and copper, of which it is composed ; since it is stated in the London Chemist, that iC-has recently been discovered in Germany, that by melt- ing together 33 parts of copper and 25 parts of zinc, or 60 parts of copper- and 40 partsof zinc, alloys are formed which possess a high degree of malleability. , ZINC AND OXYGEN. OXIDE OF ZINC. Equivalent, 40. Symbol, ZnO. 1 eq. Zinc, 32 + 1 eq. Oxygen, 8. FLOWERS OF ZINC. 504. When zinc is exposed to a red heat in the open air, it burns with a white flame, and at the same time an oxide of the metal is formed, which, rising by the heat, falls around the place of combustion in the form of white flakes. This substance was formerly called flowers of zinc, and &oraei\m^ philosophical wool. It is an oxide of the metal, and the only one known. When this oxide is collected, and again submitted to the fire, it does not rise, as before, but melts into a clear glass. When the vapor of water is brought into contact with me- tallic zinc at a red heat, the water is decomposed, the zinc com- , bining with its oxygen, and forming an pxide, in the same man- ner as is done in the open air. Bot£ these oxides are composed by weight of 1 equivalent of zinc, ... 32 1 " " oxygen, . . 8 Combining number for oxide of zinc, 40 How may malleable brass be made? How is the oxide of zinc formed? What was this oxide formerly called? How may zinc be made to decompose water? What is the composition -of oxide of zlQC, and what is its combining number? TIN. 303 \J OADMIDM. Equivalent, 56. Symbol, Cd. .; 505. Cadminm is ' one of the new metals, Laving been dis- covered in certain ores of zinc, in 1817. This metal in color and luster resembles tin, but is harder and more tenacious. It is both ductile and malleable to a considerable degree. Its specific gravity is nearly 8.5. It fuses at a temperature some- thing less than 500 degrees, and at a little higher heat it rises in vapor, and condenses in globules like mercury. When cadmium, is heated ia the open air, lite many other metals, it absorbs oxygen, and is converted into an oxide. It is readily dissolved by the nitric acid. When heated in con- tact with the vapor of water, the fluid is decomposed, and an oxide of the metal is fonae^d- Cadmium combines, so &r as is known, with only one pro- portion of oxygen, This oxide is composed, of Cadmimn, 1 equivalent, 56 Oxygen, 1 " 8 64 Cadmium, hte the other metals, forms salts by combination with the acids. But these compounds are little known, and of no value. TIM, (STANNUM.) Equivjilent, 58. Symbol, Sn. 506. Tin must be examined in tjie state of grain, or block tin ; what is commonly called tin, being sheets of iron, merely covered with this metal. Tin is procured from its native oxides, by heat and charcoal, on the same principle that has already been described for u-on and several other metals. The ores of tin are only two, viz., an oxide and a sulphutet. This metal is not readily oxidized by exposure to the atmosphere, though the brilliancy of its surface is soon tarnished. It is highly malleable, but not equally duc- tile, its tenacity not being sufficient to allow its being drawn into fine wire. Its specific gravity is 8. When heated to What is cadmium 3 VlTiat other metals doescadmiiun resemble? Is this a brittle or a malleable metall What is the specific gravity of cadmium 1 What is the com- position of oxide of cadmium T Of what metal is the sheet tin chiefly composed 1 How is tin procured from its olide 1 What are the only ores of tin 3 Is tin readily oxidized by exposure to the air or not 3 What is^said of the malleabilily and diictility of tin 3 304 TIN AND OXTGKN. whiteness, it takes jfire in the open air,' and burns with a white flame, being at the same time converted into an oxide ; at a red heat it decomposes water. Tin is a highly useftd metal, being employed for many valua- ble purposes in the arts and conveniences of- life^ Thin sheets of iron, being dipped into melted tin, receive a coat of the iiietal, and are thus prevented from rusting. This is called sheet tin, and is the article of which the common tin ware is made. Tin foil, that is, tin rolled into thin sheets, is used for many purposes. Electrical jars are coated with it, and the backs of looking-glasses are formed of an amalgam of tin foil and mercury. Block .tin forms a part of Britannia ware, of princes' metal, of pewter, speculam metal, &c. TIN AND OXYGEN. 507. Tin combines with oxygen in two proportions : The first, or the protoxide, is formed when the metal is kept for some time in fusion in the open air. At this temperature it absorbs oxygen from the atmosphere, and is converted into a gray powder. This powder is the protoxide, and is composed of 1 equivalent of tin, 58 1 " ;" pxygen, 8 66 This oxide is soluble in acids and in ammonia. The second, or peroxide of tin, is prepared by dissolving the metal in nitric acid, slightly diluted with tyater. It is a powder of a yellow color, and is composed of 1 equivalent of tin, 58 2 " " oxygen, 16 74 This oxide, when melted with -glass, forms white enamel. Tin combines with sulphur, chlorine, and the acids, forming a variety of compounds, some of which are occasionally used iu the arts. What is the specific gravity of tin 1 Into what is this metal converted wlTen burned in the open air t How is sheet tin made 7 What are the principal uses of tin? In how many prtfportions does tin combine with oxygen ? How is the protoxide of tin formed ? What is the composition of the protoxide of tin 7 How is the peroxide of this metal prepared 1 What is the quanttty of oxygen contained in the peroxide ol tinl ARSENIC. 305 OBDEK IV. 508. Metals which do not decompose water at any tempera- ture. These are, Arsenic, Uranium, Copper, Molybdenum, Columbium, Tellurium, Chromium, Cerium, Lead, Tungsten, Titanium, and Antimony, Bismuth, Yanadium. The last order includes all such metals as attract oxygen with sufScient force, when heated to redness, to decompose water. The present division absorb and retain oxygen at high temperatures, but none of them attract that principle, even at the highest temperatures, with sufficient force to decompose water. Equivalent, 75. Symbol, As. 509. There are no mines worked merely for the purpose of bbtaining arsenic, the arsenious acid, the only form in which it is used, being procured by the process of roasting the ores of cobalt. The ores of the latter metal, being heated in furnaces with long chimneys, the acid rises and attaches itself to the sides of the chimney, in layers, or cakes. After a considerable quantity has been accxmiulated in this manner, it is scraped off, and purified by a second sublimation, when it forms the well known poison called white arsenic, or oxide of arsenic. From the white oxide the metallic arsenic is procured, by heating this with a combustible. In legal investigations, where there is a su^icion of poison- ing with arsenic, it sometimes happens that Justice wiU depend on the decision of the chemist, whether arsenic might not have been the cause of death. In such cases, very minute portions of arsenic may be detected by means of a combustible and a glass tube, in the following manner : Let the matter suspected to contain the poison, be well dried at a low heat ; then mix it with five or six times its weight of powdered charcoal, and put the mixture into a thin glass tube, closed at one end. If now heat be gradually apphed to the tube until it becomes red, the what is the definition of Order 4th ? What are the names of the metals arranged under the 4th order '! Are any mines worked merely to obtain arsenic 1 How is the oxide of arsenic procured 7 How may arsenic be reduced from its oxide to the me- tallic state ? What is the appearance of pure arsenic 1 26* 306 SULPHUBETS OF ARSENIC. metal, if arsenic be present, will rise and coat its inside, show ing a brilliant metallic luster, similar to that of steel. If it is found that, on- heating a small piece of this metal, it rises in white vapor and gives the smell of garlic, it is arsenic beyond doubt. The structure of metallic arsenic is crystalline, and its specific gravity about .8. When heated to about 360 degrees, it sub- limes, without fusion, its melting point being far above that at which it becomes volatile. E the metal is heated in the -open air, it is converted into the arsenious acid, and again becomes poisonous as before ; „but, while in the metallic form, arsenic has no action on the system, and, therefore, is not a poison. ARSENIC AND OXYGEN. ABSENIOUS ACID. Eqiiivalenfr, 91. , Symbol, AsOa. 1 eq. Arsenic, 75+2 eq. Oxygen, 16. WHITE AKEENIC. OXIDE OP ARBENIO. 510. We have stated above, that when metallic arsenic is heated in the open air, it is converted into a white substance called oxide of arsenic. This is the arsenious acid of chemists. It differs from the oxides of metals in possessing acid proper- ties.. It is slightly soluble in water, reddens vegetable blue colors, and combines with alkalies, forming salts called arseni- ates. The arsenite of potash, usua,lly called Fowler's solution of arsenic, has been long employed in medicine, as a remedy for eruptive, and other diseases. ARSENIC AND SULPHUR. SULPHURETS OF ARBENIO. 511. Sulphur combines with arsenic in two proportions, forming compounds which are known by the names of orpiment, and realger. These compounds are, both of' them, natural pro- ducts, and may also be formed by art. Realger is of a red, or scarlet color, with a shioing semi-metallic luster, aiid is com- What is the specific gravity of arsenic 7 Is metallic arsenic a poison 1 How is arsenious acid formed ? WliaC is the common name of this acid ? What is the form of arsenious acid "i What are the salts called which arsenious acid forms with the salifiahle bases 1 What use is made of arsenite of potash 1 In how many propor- tions does sulphur combine with arsenic ? What is realger 1 Wljat is its composi* tion 1 How does orpiment differ from realger 1 aHROSlH,'M. 307 posed of 75 parts of metallic arsenic, aud 16 parts, or one pro- portion, of sulphur. Orpim^nt has a rich yellow color, and a foliated structure. Its luster is ?hining, and somewhat metallic, and it is readily separated into layers, like mica. This is composed of 75 parts, or one atom of metallic arsenic, and 24 parts, or one atom and a half of sulphur. Orpiment is employed as a paint under the name of King\ Yellovj. CHROMIDH. EqtuTjaent, 28. Symbol, O. 512. The metal chromium has been detected only in the two native compoimds, chroniate of lead, and chromate of iron. In these two salts, ihe metal chrome exists in combination with so much oxygen as to constitute an acid, which is united to the oxides of lead and iron, forming the compounds above named. Arsenic, as shown above, forms an acid with oxygen in the same manner, and we shall see presently that several other metals, when combined with oxygen, pCTform the office of acids. Chromium has been prociued only in very small quantities, by exposing its acid mixed with charcoal, to the highest tem- perature of a smith's forge. It is a brittle metal, of a grayish white color, and very infusible. Its specific gravity is 6. Chromium combines with oxygen in three proportions, form- ing the following compounds : V Chrome. Oxygeo. Protoxide, composed of 28 and 8. Deutoxide, " " 28 " 16. Chromic acid, " " 28 " 24. The oxides of chrome are of no importance in the arts, but the chromic acid forms colored salts with the oxides of the metals, which are extensively employed in painting and coloring. The chromic acid may be obtained in a separate state, by boiling the native chromate of lead in powder, with twice its weight of carbonate of potash, and afterward saturating the what use is made of orpitnent ? What is chromium ? lo what native compound is chromium found ? lu what state does chromium exist in these compounds ? How has chromium been prepared ? What is the color and what are the propor- ties of chromium ? In how many proportions does chromium combine with oxy- gen? What are the names of these compounds? Of what use is the chromic acid Y How may pure chromic i.cid be obia'ned 7 308 MOLYBDENUM. alkali with dilute sulphiirie acid. -The sulphate, of potash thus formed, will subside, leaving the chromic acid in solution, which, on evaporation, will yield crystals of chromic acid. These crystals are of a ruby red color, and when dissolved in water, possess all the properties of an acid. ' 513. The useful compounds formed by combining chromic acid with salifiable, bases, are prepared from ohromate of potash in solution. The latter salt is made by heating to redness the native chromate of iron with jin equal weight of nitrate of pot- ash. By this process, the chromate, which was in the state of an oxide, is converted into chrpmic acid, by the oxygen of the ■ nitrate, the acid at the same time combining with the potash of the niter. The ignited mass is then dissolved in water, neu- tralized by nitric acid, and the solution concentrated by evapor- ation, when the chromate of potash shoots into crystals, of a yellow color. The chromate of lead, a Taeautiful paint, at present largely employed under the name of chrome yellow, is made by mixing acetate, or sugar of lead, dissolved in a large quantity of water, with solution of chromate of potash. A double decomposition of these two salts is thus effected, and acetate of "potash and chromate of lead are formed. The acetate remains in solution, while the chromate being insoluble in water, falls down in the form of an orange colored, or yellow powder. This powder being separated from the liquid, and dried, forms the beautiful pigment in question. MOLyHDENCM. Equivalent, 48. Symbol, Mo. 514. The native sulphuret of molybdenum is a ponderous mineral, which occurs in masses, or is disseminated in other minerals. Its structure is foliated, and its luster like that of lead recently cut. "When this compound is reduced to fine powder, and' digested in nitro-muriatic acid, the sulphur and metal are both acidified by the oxygen imparted to them by the nitro-muriatic acid. On heating the solution, the sulphuric acid thus formed is expelled, while Qie molybdic acid remains in the form of a heavy white powder. From this powder the What is the color and form of this acid 7 How is the chromate of potash prepared ? How is the chromate of lead made from the chromate of potash 1 What is the color and use of chromate of lead 1 How is the native sulphuret of molybdenum de- scribed? By what process is molybdicacid procured? How is the metal obtained from this acid 1 COHTMBIUM. 309 metallic molybdenum may be obtained by exposing it, mixed with charcoal, to the strongest heat of a smith's forge. This metal has never been obtained, except in very small quantities, and in the form of brilliant white globules, contained in a blackish mass. When heated in the open air, it is soon converted into molyhdic acid. Molybdic acid is in the form of a white powder, -which has a sharp metallio taste, reddens vegetable blues, and forms salts with the alkalies, called molybdates. This acid is composed of 1 proportion of molybdenum, 48, and 3 proportions of oxygen, 24. TUNGSTEN, (wOLFRAM.) Equivatent, 95. Symbol, W. 515. The tungstate of iron, is a brownish black mineral, which is found both massive and crystallized. Its specific gravity is upward of 7, and when broken it presents a foliated structure, and a luster somewhat metallic. This mineral, by the miners, is called wolfram, and is com- posed of tuttgstic acid and oxide of u'on,.with a portion of the oxide of manganese. From this mineral the tungstic acid may be procured, by the action of muriatic acid, in the form of a yellow powder. ' When tungstic acid is mixed with charcoal, and exposed to an intense heat, the metal is deprived of its oxygen by the charcoal, and appears in its pure form. Tungsten has a specific gravity of 17.4, being next to platina, gold, and iridium, the most dense body known. It is nearly equal to steel in hardness, and is one of the most infusible of the metals. When heated in the open air, it is reconverted into tungstic acid. This acid is composed of 95 parts of tungsten and 24 parts of oxygen, consequently 95 is the atomic weight of this metal, and 119 the equivalent number for timgstic acid. No nse has been made of this metal, or any of its compounds. COLUMBIOH, (tANTALDM.) Equivalent, 93. Symbd, Ta. 516. This metal was discovered by Mr. Hatchett, of London, in a black mineral, which was sent to the British Museum,»by What is the appearance of molybdenum ? What are the salts called which molyb- dic acid forms with the salifiable bases 1 What is the appearance of tungstate of iron 7 How is tangstic acid procured 1 310 ANTIMONY AND OXYGEN. Governor Winthrop, of Connecticut. The mineral came from New London, and is said to have been forad near the residence of the governor. Oolumbium, like tungsten, exists in its natural state, com- bined with so much oxygen as to perform the part of an acid, and is found united to the oxides of iron, or manganese. This metal is of an iron gray color, and considerable metallic luster. Its specific gravity is 5.5. Columbia acid is composed of colui^bium, 92, and oxygen, 8. Its equivalent number, therefore, is 100. AMTIMOUy, (STILBIHM.) Equivalent, 129. Symbol, Sb. 5 IT. The only ore from which the antimony of commerce is obtained, is the sulphuret. From this native compound the pure metal is separated, by heating" it witt half its weight of iron filings in a covered vessel. By this process the' sulphur unites with the iron, while the fused antimony is drawn off at the bottom of the vessel. Antimony is a brittle metal, of a bluish white color, and con- siderable luster. Its structure is lamellated, or it consists of layers, which are the result of an imperfect crystallization. It is fused at about 800 degrees, and when slowly cooled, may be crystallized in octohedrons. By exposure to'the air it tarnishes, though not so readily as several other metals. Its specific gravi1;y is about 7. ANTIMONY AND OXYGEN. 518. Oxygen combines with antimony in three proportions, forming the protoxide, coinposed of antimony, 129, and oxy- gen, 8 ; the deutoxide, consisting of antimony, 129, and oxy- gen, 12; and the peroxide, composed of antimony, 129, and oxygen, 16! - The deutoxide combines with alkalies, and forms salts ; it is therefore called antimonious acid, and the salts so formed are antimonites. What is the process for prdcuringr tungsten from tungstic acid 1 ' What' is tlie specific gravity of tungsten % What are the properties of tungsten 7 What is the coifiposition of tungstic acid t Whence came the mineral in which columbium was first discovered 7 In what state does columbium exist combined with iron 7 What is the/specific "ravity of columbium T What is the ore from which antimony is ob- tained ? In what manner is this metal obtained from its ore 1 What is the color and what the specific gravity of antimony 7 Tn libw many proportions does oxygen com- bine with antimony 7 What are the oxides called ? CRANIUM. 311 _ The peroxidB ako performs the office of an acid, and com- bines with alkalies, foiining salts, called antimoniates, the acid itself being the antimonic. Eormerly; there were at least forty different preparations of antimony, known and used in medicine. At present this num- ber is reduced to three or four, and of these only one is in general use, yiz., the tartrate of antimony and potoCssa, or tartar emetic. ANTIMONY AND SULPHUR. 519. The native sulphuret of antimony, as stated above, is the only ore from which the metal is extracted. This is gener- ally found in compact masses, though it sometimes occurs in long crystals, interlacing each other. It is of a leaden gray color, with a metallic luster. The same compound may be formed byfiising antimony and sulphur together, or by transmitting sulphureted hydrogen through a solution of tartsir emetic. Sulphuret of antimony is composed of Antimony, 1 equivalent, 129. Sulphur, 1 " 16. Equivalent, 60. Symbol, TI. 520. This metal was first detected in a mineral found in Saxony, which, from its black color," was called pitchblende. This ore, now called Mack oxide of uranium, contains uranium in the state of an oxide, mixed with the oxides of iron and lead. The metal is reduced from its oxide to the metallic state, with great difficulty, even in the laboratory of the chemist. According to Klaproth, who discovered it, uranium is of a dark gray color, with a metallic luster, and granular texture. It is soluble in nitric acid,frise5 only at the highest temperatujj^ and affords a deep orange color to enamel. Its specific gravity is about 8. Chemists are acquainted with two oxides of this metal. The protoxide is composed of uranium, 60, and oxygen, 8. The combining number of the protoxide is therefore 68. What is the composition of salphnret of antimony? What is the ore of uranium called? What is the appearaqpe of uranium 1 What is its specific gravity? How many oxides of this metal are known ? What is said of the native protoxide of this metal? What use is made of this oxide? 312 LASTHANIUM. The peroxide consists of 1 proportion of uranium, 60, and 2 proportions of oxygen, 16 ; so that the equivalent number for the peroxide is 76. The jprotoxide occurs as a natural product, of a dark emerald gi-een color, and shining luster. It is often found attached to other minerals, in the form of scales, or in bundles of crystals, variously grouped, or interlacing each other, affording one of the most beautiful products of the mineral kingdom. This oxide is also formed by art, and is employed to give a black color to porcelain, the change from green to black being pro- duced by the heat of the porcelain furnace. Equivalent, 46. Symbol, Ce. 621. The chemists have proved that a metal called cerium exists in a reddish brown mineral found in Sweden, and called cerite, or siliceous oxide of cerium / and also in a mineral found in West Greenland, and called Allanite. The properties of this metal are little known, it having never been obtained, except in minute quantities, not larger than a pin's head. It has, however, been ascertained, that cerium combines with oxygen in two proportions, and that its combining or equivalent number is 46. These oxides are composed of cerium, 46, and oxygen, 8, forming the protoxide, whose equivalent, therefore, is 54. The deutoxide contains the same quantity of metal, with one and a half proportions of oxygen. Its equivalent is, there- fore, 58. LANTHANIOM. Equivalent, 48. Symbol, La. 522. Lanthanium was discovered by Mosander, in 1839, mixed vrith cerium, in an ore found in Sweden. Its hame is from the Gree^and signifies to lurk, or elude, in allusion to its remain- ing tHmown so long, its oxide having been confounded with that of cerium. One of its oxides is of a brick-red color, and its basic powers are said, to be very energetic. Very little is yet known of its properties. , Mosander has quite recently announced the discovery of Wh'at is said of the existence of the metal cerium ? When and by whom was lan- thanium discovered 1 What is known of this metal? What is said of the oxide of cerium 1 From what ore is the metal cobalt obtainecT? What is /.aifree 1 What ifl smalt? What is the use of the oxide of cobalt? COBAKT. 313 another new metal found in the ores of cerium, which he called Didymium. Of it we know nothing. Eqiiivalent, 30. Symbol, Co. 523. The ore from which this metal is extracted, is called arseniacal cohalt. It is found in primitive rocks, both dissem- inated and in veins, associated -with nickel, silver, bismuth, ar- senic, and copper. 524. Zaffree. — ^Whenthis ore of cobalt is' heated in contact with the air, the arsenic is expelled in the form of arsenious aeid, and the sulphur, which it also contains, is converted into sulphurous acid gas, and escapes. By this process, the ore commonly loses more than half its weight, and there remains •in the furnace an impui-e oxide of cobalt, called zaffree. When zafii-ee is heated with sand and potash, there is formed a glass of a beautiful blue color, which, when pulverized, is ex- tensively known and used under the name of siimU. The blue color of porcelain and earthenware, is produced entirely by this oxide of cobalt. Paper and linen, sdso, receive their bluish tinge from this oxide. From the oxide of cobalt, or zafiree, the metal may be ob- tained by heating that substance in contact with some carbona- ceous matter. If it is intended to obtain the metal in its pure state, the zaffree must first be purified from the iron, or other metals, which it may contain. . 525. Metallic cobalt. — Cobalt is a brittle metal, of a reddish brown color, and slightly metaUic luster. It is fused with diffi- culty. Its specific gravity is 8.5. It is attracted by the mag- net, and is capable of being permanently magnetic. Muriatic or sulphuric acid acts but slightly on this metal, but it is readily soluble in nitric acid. Cobalt does not attract oxygen by exposure to the air, but by a long continued and strong heat, it is converted into an oxide of a deep blue or nearly black color. The atomic weight of cobalt has been lately determined. 526. Sympathetic ink. — This metal is the base of that curious liquid called sympathetic ink, and which may be pre- pared in the following maimer : How may metallic cobalt be obtained from the oxide ? What is the appearance of . cobalt ? What is the specific gravity of cobalt 'i What is said of the magnetic prop- erty of cobalt 1 What acid is the proper solvent of cobalt T What is the method of prepariug sympathetic iuk 7 •27 314 SICKEL. Dissolv'^ one part of cobalt, or zaffree, in four parts of nitric aciS, and assist the solution by heat. To this solution add one part muriate of soda, and four times as much water as there ■was acid. - . .* Characters wiitten on paper, with this' ink, are ille^ble when the paper is cold, but become plain, and of a beautiful green color, when the paper is warmed. This expeiiment is rendered still more pleasant by drawing the trunk and branches of a tree, in the ordinaiy manner, and then ti-acing the leaves with the solution of cobalt. In winter such a tree will appear without leaves, except when warmed, but in the summer, particularly if placed in the sun, it will be covered with beautiful green foliage. Screens, painted with this solution, will show their green when in use, but will immediately begin to fade when carried away from the fire. Equivalent, 28. Symbol, Ni. 527. Nickel is generally found minei-alized by the acids of arsenic. The Saxon ores, among which this metal is found, are mixtures of lead, copper, iron, cobalt, and arsenic, combined with sulphur and oxygen. In nearly every instance, where meteoric iron, or other meteoric products have been analyzed, they have been found to contain this metal. Nickel, with zinc and copper, melted together, form German- silver, of which large quantities are manufactured. Nickel has a strong metallic luster, and is nearly the color of tin and silver. It is both ductile and malleable, and like iron and cobalt, is attracted by the magnet, and may be made per- manently magnetic. Its specific gravity, after being hammered, is 9. It is exceedingly infusible, and suffers no change at com- mon temperatures, when exposed to the air; but is slowly oxidized at a red heat. The muriatic and sulphuric acids do not act on nickel, but it is readily oxidized and dissolved in nitric acid. Nickel combines .with two proportions of oxygen. The pro- toxide is composed of nickel, 28, and oxygen, 8. The peroxide of nickel, 28, and oxygen, 16^44. What are the peculiar properties of this inki With what is nickel combined in the natural statel What is said of the existence of nickel in meteoric products? Is tftiB metal of any use in the arts 1 What is the appearance bf nickel 1 What is said pf Its magnetic prcipBrtyl What is its specific Eravity ? In what acid does nickel diBSOlyel ' ■ ■ • . . r TLOWERS OF BISMUTH. 315 Equivalent, 72. Symbol, Bi. 528. Bismuth occurs native, and in combination with sul- phur, oxygen, and arsenic. That which is employed in the arts and in commerce, is derived chiefly from the native metal. Bismuth has a reddish white color, a brilliant luster, and a foliated structure. It fiises at 476 degrees, being, with the ex- ception of tin, the most fusible of the solid metals. When slowly cooled, this metal may be obtained in octohedral crys- tals. Its specific gravity is 10. Bismuth enters into lie composition of printing type ; and its oxides are employed as paints, and in medicine. BISMUTH AND OXYGEN. OXIDE OF BISMnTH. Equivalent, 80. Symbol, BiO. 1 eq. Bismuth, 72-1-1 eq. Oxygen, 8. FLOWERS OF BIBUUTH. 529. Bismuth combines with oxygen in only one proportion, forming a yellowish white oxide, "fiiis may readUy be formed by submitting the metal to a strong heat in the open air. It takes fii-e and bums with a blue flame, while the oxide Ms down in the form of powder. Bismuth is not readily soluble in the muriatic or dblphuric acids, but the nitric acid dissolves it with facility, forming nitrate of bismuth. "When nitrate of bismuth, either in crystals or in solution, is thrown into water, a copious precipitate subsides, in the form of a beautiftdly white powder. This is the subnitrate of bis- muth, and was formerly known under the name of magistery of bismuth. This is employed as a cosmetic powder for whiten- ing the complexion, but it is a dangerous substance for such a purpose, since, if it happens to be exposed to sulphureted hy- drogen, it turns black, thus exposing, the wearer to mortification and detection. What are the states in which bismuth is found ? What is the colof of bismuth ? What are the uses of bismuth 1 In how many proportions does this metal combine with oxygen 7 How may tliis oxide be formed ? What use is made of the subnitrate ofb.smulh? Whatissaid of the eztstcnce^ftitaniuml What is said of the native oxide of titanium 7 316 corPEK. TITANIUM. Eqiuvalent, 24. Symbol, Ti. 530. Titanium has hardly been seen in its pure metallic state, but the analysis of its oxides proves that such a metal exists. The ores of this metal are considerably numerous, and are widely disseminated. The native oxides of titanium sometimes occur in long striated, acicular crystals, of a reddish brown color, and shining metatlic luster. Such crystals are sometimes contained in transparent pieces of quartz, forming specimens of singular beauty. The artificial oxides of this metal are white, and are obtained by difficult processes. They hold their oxygen with such tenacity that all attempts to reduce them, by means of heat and a combustible, in the usual manner, have failed. The equivalent numbers of these acids have not been deter- mined with certainty. EquivaJent, 66. Symbol, Te. 531. This is an exceedingly rare metal, being hitherto found only in the gold mines of Transylvania, and at Huntington, in Connecticut. It occurs in the metallic state, associated with gold and silver, lead, iron, and sulphur. The color of tellurium is between those of zinc and lead ; texture laminated, like that of antimony, which it also resembles in some of its properties. It melts at about 600 degrees ; has a specific gravity of 6.11 ; is brittle, and easily reduced to powder. When heated before the blow-pipe, it tates fire, burns rapidly with a blue flame, and is dissipated in gray fumes, which are an oxide of "the metal. This oxide, which is the only one tellurium forms, is com- posed of 66 parts of this metal and 8 parts of oxygen ; so that 66 is the atomic weight of tellurium, and 74 the equivalent of its oxide. COPPER, (CUPBDM.) Eqnivalent,'^2. Symbol, Cu. 532. Giopper is found native, also combined with sulphur, with oxygen, with carbonic acid, arsenic acid, sulphuric acid, VBherie have the ores of tellurium been found 1 In what state; does tellurium occur 1 What IB the color of tellurium 1 What is the composition of the oxides of tellurium * What are the substances with which copper is found combined 1 RED OXIDE OF COPPER. 317 muriatic acid, and with several of the metals. Its ores are very numerous, and some of tliem highly beautiful and interesting. The uses of this metal are numerous, and well known. In the metallic state, it forms a part of brass, of pinchbeck, of Dutch gold, and many other alloys. Wl en dissolved in various acids, it forms compounds which are employed for a great variety of useful purposes. The green pigment, verditer, is a nitrate of copper, precipi- tated by carbonate of lime. Verdigris is an acetate of copper. Mineral green is a sulphate of copper, precipitated by caustic potash. Copper receives a considerable luster by polishing, but soon tarnishes when exposed to the open air. Its specific gravity is 8.78, and is increased by hammering. It is malleable and duo- tile, and its tenacity is inferior only to iron. It hardens when heated and suddenly cooled. At a red heat, with access to air, it absorbs oxygen, and is converted into the peroxide, which appeai-s in the form of black scales. Nitric acid acts on this metal with vehemence, and it is dis- solved slowly in the muriatic and sulphuric acids. The vege- table acids, as vinegar, also dissolve copper when exposed to me air, but not otherwise, the oxygen of the atmosphere assisting in the oxidation of the metal. COfPER AND OXYGEN. PROTOXIDE OF COFPER. Equivalent, 40. Symbol, CuO. 1 eq. Copper, 324-1 eq. Oxygen, 8. RED OXIDE OF COPPER, SSS.ffhe red, or protoxide of copper, is found native in the form of regular octohedral crystals, variously truncated, and forming specimens of great beauty. It may also be prepared artificially, by mixing 64 parts of copper filings with 80 parts of the peroxide iu powder, and heating the mixture to redness in a close vessel. By this process, the copper filings attract one proportion of oxygen from the peroxide, which contains twice the quantity of oxygen contained in the protoxide. Thus What are the principal uses of copper % What is the specific gravity of copper 1 How may copper be conTerled into a peroxide ? What acids dissolve this melal 7 In what fbrm does the protoxide of copper occur ? How may the protoxide of cop- per be prepared l)y art? Explain huw the process for forming the protoxide of cop- per illustrates the Taw of definite proportions. 27* 318 LEAD. the quantity of oxygen is equalized, and the whole is convertsd into the protoxide. This experiment aflFords a very simple illustration of the law of definite .proportions. Eighty parts of the peroxide of copper contains 32 parts of the inetal, and 16 of oxygen. When this quantity is heated with 32 parts of copper, 1 proportion, or 8 parts of oxygen, leaves the peroxide, and unites with the cop- per, thus making, in the whole, 112 parts of the protoxide, the copper gaining 8, and the peroxide losing 8, the numbei- for each becomes 40, the equivalent for the protoxide. - FEROXIDE OP COPPER, Ec[uivalent, 48. Symbol, CuOa. 1 eq. Copper, 32+2 eq. Oxygen, 16. 534. This oxide is said to be found in the native state. • By art, it may be formed by keeping thin pieces of copper at a red heat exposed to the air, or by heating the nitrate of copper- to redness. This oxide is dark brown, or nearly black. When heated alone, it undergoes no change, but ii heated in a close vessel, with charooalj or other combustible, it parts with the whole of its oxygen, and is reduced to the metallic state. It combines with most of the acids, and produces salts of a green or blue • color. Copper combines with sulphur, and forms a sulphuret of the metal. This compound occurs native, and may be formed by heating a mixture of copper filings and sulphur. LEAD, (plumbum.) Equivalent, 104. Symbol, PI. 535. In a few instances lead has been found in tne native state; but it most commonly occurs combined with sulphur, forming the sulphuret, of a bluish gray color, and strong me- tallic luster. This compound is known under the name of galena, and is the ore from which the lead of commerce is ex- clusively obtained. The color and common properties of lead are well known. Its specific gravity is 11. In tenacity, it is inferior to all the ■ ~ ' ' - r ■ — How may the peroxide of copper be formed 1 How may the peroxide of copper be reduced to itit melaUic state ? What is the composition of tiie sulphuret" of cop- per ? In what state iS:lead cliiefly found ? What is the common name for sulphuret ofleadi What is the specific gravity of lead 1 LEAD ASD OXYGBS. 319 ductile metals. It fuses at about 600 degrees, and when slowly cooled, may be obtained in octohedral crystals. When newly cut, it has a brilliant metallic luster, but is soon tarnished by exposure to the aii-.- Lead is not oxidized by moisture without the contact of air, and hence it may be kept under pure water, for any length of time, without change. But if water be placed iu an open ves- sel of lead, the metal is slowly oxidized, and a white crust is formed, at the points of contact between the lead, water, and air, which is a carbonate of the protoxide of lead. Hence, as the salts of this metal are poisonous, leaden vessels open to the air, should never be employed to contain water for culinary purposes. The sulphuric and muriatic acid& act slowly upon this metal. Conce^ntrated sulphuric acid produces so little action on it, that the" acid is made in chambers lined with lead- Nitric acid is the proper solvent of this metal. The solutipii, when evapor- ated, -deposits whitish opaque crystals of mtrate of lead. LEAD AND OXYGEN. 536. There are three oxides of lead, which are thus con- stituted : L«ad. Oxygen. Protoxide, 104+ 8=112. ■Deutoxide, 104+12 = 116. Peroxide, 104+16=120. 537. Protoxide of lead. — ^This oxide is procured in purity, when a solution of the metal in nitric acid is precipitated by potash, and the precipitate dried. It is of a yellow color ; is insoluble in water, and fuses at a red heat The same oxide is formed by heating lead in the open air, and is known in com- merce by the name of massicot. When massicot is partiaHy fused, in contact with the air, it becomes of a reddish color, and is known by the name of litharge. This appears to be a mix- tiu-e of the protoxide and deutoxide of lead. Litharge is mixed with oil usedin painting, in order to make it dry more rapidly. It is probable that this effect is produced by the oxygen, which the litJtarge imparts to the oil. what is said of the oxidatiou of lead when kept under water X Under what cir- cumstances does water become poisonous when kept in leaden vessels? What is said of the action of different acids on lead % How many oxides of lead are there, and what is the composition of each 1 What is massicoti How is litharge prepared? What istheuseof litharge 1 320 LK^D AND OXVGKN. The well known pigment called white lead, is a carbonate Oi the protoxide. This substance is prepared by placing rolls of thin sheet lead in pots containing vinegar. The vinegar im- parts its oxygen to the metal gradually, and probably prepanjs it for the absorption of carbotilc acid froin the atmosphere. C[r possibly the lead may be dissolved by the acetic acid, and this acetate in its forming state decomposed by the carbonic acid of the atmosphere, in the same manner that the chloride of lime is (jecomposed, and changed into a carbonate by exposni-e to the air. White lead was formerly considered a peculiar oxide, but analysis shows that it is a compound of the yellow oxide, and carbonic acid. 638. Dehtoxide of lead.— This is the red lead of com- merce, and is extensively used as a pigment, and in the manu- facture of flint glass. It is formed by heating litharge in a fur- nace so constructed that a current of air constantly passes over its surface. In 'this manner, the litharge, ■ which is chiefly a protoxide, is converted into a deutoxide, by absorbing another proportion of oxygen from the air. When red lead is heated to redness, it gives oflf pure oxygen, and is reconverted into the deutoxide. 539. Peroxide of LEAD.^This is formed by the action of nitric acid on red lead. The red lead, or deutoxide, is decom- posed by the acid, and resolved in the protoxide which it dis- solves, and converts into the peroxide, which being insoluble, falls down in the form of a puce colored powder. This oxide is insoluble in any of the acids. When heated it gives oflF large quantities of oxygen gas, and is resolved into the protoxide. 540. Su-LPHUBET OF LEAD. — This compound occurs very abundantly as a natural product, and may be fornied by fusing a mixture of lead and sulphur. The lead of commerce, as above stated, is obtained exclu- sively from this ore, which is generally known under the name c{ galena. The metallic lead is easily obtained from the sul- phuret. The ore being placed in tlie furnace, is gradually heated with small wood, or faggots, to drive off the sulphur. Afterwards, charcoal and lime are thrown in, and the heat is increased. As some portions of the lead become oxidated by exposure to the air and heat, the dharcoal reduces these portions What is the composition of white lead ? How is white lead prepared t What i& the deutoxide of lead 1 How is red lead prepared, and what ig its use 7 Wliat pro- nortioll of oxygen does the deutoxide contain 1 How is the peroxide of lead formed 1 What are the properties of the peroxide of lead I IJow is lead reduced from the sulphuret 1 NEW METALS. 321 by the absorption of their oxygen, and at the same time in- creases the heat. The Erne combines with the sulphuric acid, which is formed by the union of the sulphur of the metal, the oxygen of the air, and the water of the wood, and forms a sxd- phate of lime. Meantime, the metallic lead, tiius reduced, runs down into the lower part of the furnace, where it is drawn off into proper vessels. All the salts of lead act as poisons, with the exception of the sulphate,, which Orfila has proved^ not deleterious. The same autiior has shown that the acetate, or sugar of lead, is decom- posed in the stomach by sulphate of magnesia, or Epsom salt, and that the inert sulphate is thus formed. Hence, Eipsom salt, or Glauber's salt, which is a sulphate of soda, becomes an anti- dote to the poisonous effects of sugar of lead, when taken soon after it. VANADIUU. Eqiiivaleiit, 68. Symbol, V. 541. This new metal was discovered by Professor Sefetrom in 1830, mixed with some iron ore from Jaberg, in Sweden. Its name is from vanadis, a Scandinavian deity. In its properties, vanadium appears to be between chromium and uranium. It forms with oxygen, two oxides and one acid, called the vandaie add, and combines with several other simple non-metallic elements. The metal, which can only be obtained by a complicated process, has a strong metaUic luster, like silver, and is so brittie that it can hardly be touched without falling into powder. By combination with the proper substances, it forms chlorides, sulphurets, and phosphurete. Of its uses, nothing more seems to be known, than that it maies an excel- lent writing ink, in the form of vanadiate of ammonia, mixed with iniusion of nut galls. NEW METALS. 542. "Within the last few years, at least seven new metals, or metallic oxides,- have been discovered in various parts of the world. None of them have thus far proved of any use to the arts, or luxuries of life. We have, however, taken pains to ob- tain some account of each, which is here inserted. What are the uses of charcoal and lime in the redaction of lead % What compound of lead is said not to be poisonoos? What antidote is mentioned to the poisonous effects of sugar of lead ? How does Epsom salt act to neutralize the poisonous effects of the salts of lead "i When was vanaflium discovered ? From whence is its name derived 1 What is the appearance of this metal 1 WTiat are its uses 1 322 NEW METALS. EimiUM AND TERBIUM. 543. These two metals were discovered by Mosander, while testing the ores of yttria. Information concerning^ them are quite limited. They do not appear to have been reduced to the metallic state, but exist only in the form_ of bases, with several acids, forming metallic salts, and also in the form of oxides. Equivalent unlmovm. Symbol, E. 644; The oxide of erbium becomes of a deep brown color, when heated in the air, this color being lost when lieated in hydrogen. The nitrate and sulphate of this metal are colorless. fERBIDBt. Equivalent,' 64. Symbol, Tb. 545. The oxide of this metal is colorless, but its salts are of a pale red. The nitrate does not deliquesce, but dries into a crystalline mass ; the sulphate dries into a white powder. Equivalent untmown. Symbol, D. 546. This metal, or rather its oxide, was discovered by Mo- sander, in an oxide of lanthanium. Very little is known of its properties, and nothing interesting. Equivalent unlcnown. Symbol, No. 54^. This metal was detected by M. Eose, in an ore of columbium, foupd in Bavaria. It forms acids with oxygen, some of which have quite distinct properties ; but little is known of these compoimds. Equivalent unknown. Symbol, Pe. 548. This is another metal lately announced by Eose, and which he found in an ore of columbium. Like the last, it has thus far developed nothing interesting or useful. SALTS. 323 RUTHEniOM. Equivalent, 52. Symbol, Ru. 549. In,, preparing platinum from its ores, there remains a black powder, from whiqh, as already noticed, several metals have been derived. From this residue is also obtained ruthe- num. It occurs in small porous masses, with a metallic luster winch oxidates on exposure to the air. It is infusible, even by the compound blow-pipe, and is insoluble in nitro-muriatic acid. It has been examined with much care, but no useful result has followed. DONARIUH. Equivalent unknown. Symbol, Do. 550. This metal was found by Bergmann, while testing cei^ tain ores found in Norway. It exists in the form of an oxide, and is reduced to the metallic state withmuch difficulty, and then exists in the form of a heavy powder, with metaUio luster. It has not been of any use. CHAPTER XX. SALTa Note.— The symbols for the elements, with their ])inaiy combination, have been given, but those for the saline com- pounds are omitted, as useless for those for whom this book is' intended. If, however, the pupil is desirous of giving such symbols, he has only to look back and ascertain those of the elements, and combine them for the compounds. As an exam- ple, we give the symbols for alum. Al. 203-|-3SO 3-f-K O, SO 3-1-24 Aq.=262. 551. The compound resulting- from the union of any acid with an alkaU, an earth, or a metallic oxide, in definite propor- tions, is called a salt. The substance which combines with the acid to form the salt, is called the base. Thus, lime is the base of carbonate of Mme. Any substance capable of combining with an acid to form a What ia a salt ? What is the base of a salt ? What is a salifiable base ? What is an acid ? Are all acids sonr to the taare 7 Do all acids contain ox7gen ? Do the allcalies contain ojcygen 1 324 SALTS. s^t, is called a salifiable hase^ The salifiable bases, therefore, are the alkalies, the earths, and metallic oxides. Any compound, -which is capable of imiting in definite pro- portions -frith a salifiable base, or whicb in solution is sour to the taste, or reddens vegetable blues, is an acid. Fi'om this definition, it will be observed that acids are not necessarily sour to the taste. This, in many instances, arises from their insolubility, for an insoluble acid neither tastes sour, norvchafi^es the color of vegetable blues. Other acids, which, though soluble, do not taste sour, and have little, if any action on colors, still have the property of neutralizing alkalies, and combining with salifiable bases in definite proportions ; such is the prussic acid. , It was formerly supposed tbat all tbe acids contained oxygen, as the acidifying principle, but we have already had occasion to remark, that there are several known exceptions to this truth. Since the discovery of the compound nature of the alka- lies, and the simple nature of chlorine, it is foimd that some compounds, in which oxygen exists as an element, are alkalies, and that others, containing no oxygen, are acids. Thus, the metal potassium, conibined with oxygen, fca-ms the alkaji po- tassa, and 6hlorine, united to hydrogen, forms muriatic acid. 552. Alkalies. — The alkalies are supposed to possess char- acters exactly opposite to those of the acids. Their tastes are pungent ; they neutralize the acids, and change vegetable blue colors to green. There are, however, many compounds, capable of foi-ming salts, and of neutralizing acids, which do not possess the latter characters. Thus magnesia, though a powerful neu- tralizing substance, excites no t3ste,~and produces little change on vegetable colors. This want of action obviously depends on its insolubility in water. Thus, a salifiable base does not necessarily contain sensible alkaline properties, but js any substance which foi-ms a definite oompourid with acids, or which being soluble, has the alkaline taste, and changes vegetable blues to gi-een. All the "metallic oxides are salifiable bases. 553. Oxides combine. — In speaking of the solution of a metal in an acid, it must always be understood, that it is the Give an instance where oxygen, combined with a metal, forms an alkali. Give an instance in wiiich chlorine and another simple substance umted, forman acid. Why IS magnesia tasteless 1 Are the metallic oxides salifiable bases 1 What change do the metals undergo before they .are soluble in the acids? In 'what manner do the meta)s become oxides helbro they are dissolved 1 When zinc is thrown into diluted sulphuric acid, why docs hydrogen e64.:ape 1 SALTS. 325 oxide ot the metal which is soluble, for no metal combines with an acid in its metallic state. The action of the acid is first to oxidate the metal ; which it does, either by imparting to it a portion of its own oxygen, or by assisting it to obtain this prin- ciple from the water with which the acid is mixed. When uopper- dissolves in nitric acid, the metal is first pxidated at the expense of one proportion of the bxygen which the acid con- tains, and hence the fumes of nitrous -gas which escape. But when zinc dissolves in dilute sulphuric acid, the metal is oxidated by the decomposition of the water, and then dissolved by the acid, and hence the escape of hydrogen during this process. 554. Number of salts. — It is said that at least 2000 salts are known, but this is a small number when compared with those which might be formed ; for supposing each acid to be capable of forming a different compound with each salifiable base, and each base a distinet compound with ^ every knewn acid, the salts would be nuniberless. It may be supposed, fi-om the variety of properties possessed by the acids, and the salifiable bases, with which they are known to combine, that the resulting compounds must' present a grea||Variety of different qualities, colors, and shapes, and in this we are not disappointed. Some of the salts are corrosive poisons, others are perfectly inactive on the animal system; some are used as medicines, others as paints, bthers in coloring, &c. It is obvious that in this epitome of the science, only a limited number of these compounds can be described. These we shall arrange in groups, or classes, each group consisting of the same acid, united to different salifiable bases. 555. Crystallization. — Most of the salts are capable of being crystallized, that is, of forming dry solid figures of deter- minate , shapes. During the act of crystallization, many of them combine chemically with a definite portion of water, which, therefore, is called the water of crystallisatign. Some salts contain more than half theiif weight of water ; this is the case with sulphate of soda, or Grlauber's salt, which consists of 72 parts of the dry sulphate, and 90 parts of water. Other salts, as muriate of soda, or common salt, contain no water of crystallization. But these salts sometimes contain particles of water included mechanically within their substance. What number of snlts are said to be known T On what principles are the salts thrown into groups ? What is the water of eryetallization 1 Do all the salts contain water of crystallization ^ Why does common salt decrepitate when heated ? 326 SALTS. and hence when heated they decrepitate, or fly in pieces, in consequence of the conversion of this water into steam. From this cause, common salt decrepitates violently when thrown on the fire. Salts containing a large quantity of the water of crystalliza- tion, when heated, undergo the aqueous fusion ; that is, they dissolve in the water they contain. Anhydrous salts, or such as are n^t chemically united with water, when heated undergo the igneous fusion. A salt is said to effloresce, when its water of crystallization evaporates, and it falls into a dry powder. • 556. Solution in water. — Most of the salts are soluble in water ; and with a few exceptions, the solvent power of this fluid is in proportion to its temperature. One of these excep- tions is common salt, which is equally soluble in hot or cold water. Some of the salts require SOO or 600 times their own weight of water for solution. This is the case with carbonate of lime, and sulphate of lime. In a few instances, as in the sulphate of baryta, the salts are entirely insoluble in water. On the contrary,^some of these compounds have such an afiinity for water, as to enter into solution with that which they at- tract from the atmosphere. In these instances the fialt^s said to deliquesce. Muriate of lime is an example. It can not be kept in the solid state, unless closely excluded from the atmosphere. 557. Definite proportions. — All the salts are composed of definite proportions of their ingredients, and these ingredients are compounded of definite proportions of elementary bodies. Thus, sulphate, of potash is composed of 40 pai-ts of sulphuric acid, and 48 parts of potash. The acid is composed of 16 parts, or 1 atom of sulphur, and 24 parts, or 3 atoms of oxy- gen. Potash is composed of 40 parts, or 1 atom of potassium, and 8 parts, or 1 atom of oxygen. 558. Definite numbers. — Thus the salts are formed by the union of compound substances, and their equivalent numbers are the sums of the atomic weights of these substances. Thus,' the equivalent number for the sulphate of potash is 88, being composed of the equivalents for sulphuric acid, 40, and the equivalent for potash, 48. How these latter numbers are ob- What is meant by aqueous fiision 7 What is meant by igneous fusion 7 When ia a salt said to effloresce ? What salt is equally soluble in cold or hot water 7 WhaX salts require a large portion of water forsolution? When isasaltsaid todeliiiuesce? What is said of the definite proportions of the ingredients and elements of the salts 1 What is the composition of sulphate of potash % How is the equivalent number for sulphate of potash obtained 7 SULPHATES. 32,7 tained has just been explained ; and indeed the whole of the above, so far as regards definite propoi-tions, is only a recapitu- lation of what has already been stated more in detail, in its ^proper place ; but is repeated here, because the doctrme of pro- portions applies especially to the composition of the class of compounds which we are now afiout to describe. Some salts combine with each other and form compounds, which wer« formerly known imder the name of triple salts. But as, in these instances, only two bases combine with one acid, or two acids with one base, this kind of union is more properly indicated by the term double than triple ; and this change being proposed by Berzelius, is now employed by recent writers. In describing the salts, we shall follow the method already observed in respect to other compounds, and place the equiva- lent numbers at the head of each description. CHAPTER XXI. SULPHATES. 559. The sulphates, when heated to redness with charcoal, are decomposed and changed into sulphurets. The oxygen, both of the oxide and the acid of which the salt is composed, unites with the carbon, forming carbonic acid, while the sul- phur and metal combine to fonn the new compound, the sul- phuret, or sulphide. The sulphates in solution, are readily detected by muriate of baryta ; the muriate being decomposed by the sulphuric acid, an insoluble sulphate of baryta is formed, which falls to the bottom of the vessel in the form of a white powder. Several sulphates exist in nature, the most abundant of which are those of lime and baryta. The sulphate of lime is very abundant in some countries, and is employed as a manure, and in the arts, under the name of gypsum, or plaster of Paris. What is meant by a double salt ? How are the sulphates changed into sulphurets 1 In what manner does the charcoal and heat change sulphates to sulphured? t How does muriate of barytea show the presence of sulphuric acid 1 328 aiiAUSEB'S Salt. SULPHATE or POTASSA, 88. leq, S. Acid, 40+1 eq. PotassaJ 48. VITllIOLATED TARTAR. 560. This salt is prepared by decomposing the. carbonate of potash with sulphuric acid. Its crystals are -iu the form of six- sided prisms, terminating in six-sided pyramids. Its taste is saline' and bitter. This salt suffers no change on exposure to the air. Its crystals contain no water of crystallization, and when thrown on the fire, decrepitate for the reason formerly explained. These crystals are. soluble in 16 times their weight of water at 60 degrees. The composition and equivalent number of this salt are seen above. SULPHATE OF SODA, 72. 1 eq. S. Acid, 40+1 eq. Soda, 32. Glauber's salt. 561. Sulphate of soda sometimes occurs as a native com- pound, and may be readily formed by saturating common car- bonate of soda by dilute sulphuric acid. That sold by apothe- caries is chiefly prepared from the contents of the retort after the distillation of muriatic acid. This acid is obtained by distilling a mixture of common salt and sulphuric acid. The latter acid, combining with the soda of the muriate, the muriatic acid is evolved and sulphate of soda formed. This being purified, forms the Grls^uber's salt of commerce. Sulphate of soda crystallizes in fom* and six-sided prisms. These crystals when exposed to the air, part with their water of crystallization, or e^oTMce, leaving the salt in the state of a dry powder. By this process the salt loses about half its weight. According to the analysis of Berzelius, this salt contains 12 parts of the neutral sulphate, and 90 parts, or ten atoms of water. The combining proportions, or equivalents, of the salts, refer only to the acids and bases which they contain, and not to their How IS sulphate of potaeli formed 1 What is the composition and equivalent num- ber of this salt! What is the composition of sulphate of soda? What Is the com- mon name of this salt 1 How is (jlauber'3 salt prepared 1 What proportion ol water does sulphate of soda contain 1 What is said of the definite nuantilv of the water of crystallization? ' PLASTER OF PARIS. 329 water of oiystallization. It is found, however, that the water of crystallization is always combined in definite proportions, as well as the other ingredients. The combining number for water, as already explained, is 9, and in the present instance the doctrine of mvdtiple proportions, by- a whole number, is found to be precisely true, there being 10 atoms, or proportions, of water in this salt. BULPHATE OP BARYTA, 118. 1 eq. S. Acid, 40+1 eq. Baryta, 18. HEATT SFAB. 562. The native sulphate of baryta is widely disseminated, though not often found in verj' large quantities at any one lo- cality. It occurs both massive and in anhydrous crystals, which are generally flattened, or tabular. This substance is known under the name of heavy spar, having a specific gravity of nearly 4-J, being the most ponderous of earthy minerals. It is formed artificially by mixing the earth baryta with sul- phuric acid. The native sulphate is ground and fraudulently mixed with oxide of lead, as a paint. This substance is sometimes employed to form the solar phos- phori, a compound which shines in the dark, after having been exposed to the light of the sun. It is prepared by first igniting the native sulphate, after which it is powdered and sifted. It is then mixed with mucil- age of gum arable, and formed into cylinders about the fourth of an inch in thickness. These being dried in the sun, are ex- posed to the heat of a wind furnace supplied with charcoal, for about one hour, and the fire sufiiered to bum out. The cylin- ders will be found among the ashes, jetaining their original shapes, and must be preserved in a well stopped vial. When this substance is exposed for a while to the sun, and then carried into the dark, it will emit so much light as to show the hour by a wateh dial. , ,, SULPHATE OF LIME, 68. 1 eq. S. Acid, 40 + 1 eq. Lime, 28. GYPSUM. PLASTER OF PARIS. 563. This salt occurs abundantly as a natural production. It is composed of 68 parts of the pure sulphate, and 18 parts What is the composition and equivalent number of sulphate of baryta ? 28* 330 EPSOM SALT. or two proportions of water. This salt is found crystallized in broad foliated plates, and also in compact masses. It is ground, and spread on certain kinds of land as a manure. In this state it is called ground plaster. The compact variety is called alabaster, and is cut, or turned into various ornamental articles, such as candlesticks, vases, and boxes. Some of these speci- mens are perfectly white, and being translucent, are among the most beautiful productions of the mineral kingdom. Other varieties of this mineral are colored with metallic oxides, and present the appearance of clouds, stripes, or spots of red, blue, or brown, interspersed, or alternating with each other. Sulphate of lime is largely employed in forming the orna- mental, or stucco work, for churches and houses. For this pui-pose it is first heated nearly to redness, or as the workmen term it, boiled, va. order to expel the water of crystallization, and then ground in a mill. In this state it is a fine white powder, which being mixed with water and cast into moulds of various- figures, form the ornamental work seen on the walls of churches and rooms. It also foi-ms the moulds for stereotype plates. , After being mixed with the water, it must be immediately poured into the mould, for however thin the paste may be, it grows hard, or as the workmen call it, sets, in a few minutes, and no addition of water will make it thin as before. This is owing to the chemical combination which takes place between the anhydrous sulphate and the water, and by which the latter is made solid. Sulphate of lime is soluble in about 500 parts of cold water, and as it exists abundantly in the earth, it is more frequently found dissolved in the water of wells and springs, than perhaps any other salt. When it exists in considerable quantity, it gives that quality to the water called hardness. Such water decomposes soap, by neutralizing its alkali, and therefore is not fit for washing. BULFBATE OF MAGNEBIA, €0. 1 eq. S. Acid, 40-|-l eq. Magnesia, 20. EFSOM SALT. 564. Epsom salt is sometimes obtained by evaporating the water of springs which contain it in solution, and sometimes it What is the common name of this salt 1 Is sulphate of baryta a native, or an arti- ficial salt? How is solar phosphor! prepared from sulphate of baryta 1 What curious property kas the solar phosphorus ? What is (he composition of sulphate of lime 1 What quantity of water does this salt contain % ALUM, 331 is made artificially, by first dissolving magnesian limestone in vinegar, which takes up the lime and leaves the magnesia. "Ehe magnesia is then piirifled by calcination, and after- ward dissolved in dilute sulphuric acid, and crystallized by evaporation. .. This salt appears in minute quadrangular shining crystals. These sufier little change when exposed to-the air, undergo the watery fusion when heated, and are soluble in three-fourths of their own weight of boiling water. Its use, as a medicine, is well known. Sulphate of magnesia is composed of 60 parts of the dry siil- phate, aoid 63 parte, or Y atoms, of. water. SULPHATE OF ALUMINA AND POTASSA, 262. 3 eq. Sulph. Alumina, 174-|-1 eq. Sulph. Potassa, 88. ALUM. 66fi. AJum is a substance so well known, that its external appearance -requires no description. Its taste is at once astrin- gent and sweetish. It is soluble in about ite own weight of boiling water. It crystallizes in octohedions, or eight-sided figures, and, by peculiar management, these crystals may be obtained of gi-eat size and beauty. It is a dou"ble salt. Sometimes aJum is found ready formed in earth or friable rocks, and is extracted by collecting such eai:th into proper vessels, and pouring on water, which, passing through, dissolves the salt, and holds it in solution. The water being then evap- orated, the alum shoote into crystals. When the mineral which furnfehes this salt is aluminous clay, mixed with sulphur and iron, which is more often the case, another method is taken. The mineral being exposed to heat, or merely to the action of the air, the sulphur attracted oxygen, and is converted into svdphuric acid, which then com- bines with the alumina, and forms a sulphate. If no putash be present in the earth, this is added, and the whole is treated by lixiviation, (that is, pouring on water until the salt is dissolved,) and the liquor afterward evaporated to obtain the alum. What is the common name for salphate of lime 1 What are the uses of sulphate of lime 1 What is the compact variety of this salt called ? How is gypsum prepared to fbrm stucco work? What chemical change is produced when the anhydrous sulphate is mixed with water? What is meant by anhydrous? What effect does sulphate of lime have on the water of wells? What is the composition of sulphate ofmasnesra? What is.the common name of sulphate of magnesia? What is the use or this salt? How is sulphate of magnesia prepared? What isthe commou name of sulphate of alumina and potash? What is the composition of alum? What is the process by which alum is obtained ? 332 GBEEN VITEIOL. Alum is used in medicine and in the arts. Its composition is stated at the head of this section. Alum is thfe base of a curious composition, called Homberg's pyrophorus, which ignites on exposure to the air. It is prepared in the following manner : Reduce an ounce or two of alum to powder, and mix it with an equal weight of brown sugar. Put the mixture into an earthen dish, and keep it stirring over the fire until aU the moisfure is expelled. Then, havihg pulverized it finely, intro- duce the powder into a common vial, coated with a mixture of clay and sand. To the mouth of the vial, lute a small glass tube, or the stem of a tobacco-pipe, in order to allow the. mois- ture and gases to escape. The vial, thus prepared, is set in a crucible, surrounded with saiid, and the whole placed in a coal fire, and gradually heated to redness. At first, steam will issue from the tube, but afterward a gas, which, being set on fire, burns with a blue flame. After the flame goes out, keep up the heat for about fifteen minutes, and then remove the crucible from the fire, and imme- diately stop the orifice of the tube with a piece of wet clay. When the vial is cool, pour its contents hastily into other vials, which are perfectly dry, and then cork them so as entirely to exclude the air. This compound resembles powdered charcoal in appearance ; but if a few grains be poured out, and exposed to the air, it soon glows with a red heat, and will set paper or wood on fire. If poured from the vial, at the distance of a few feet from the ground, it forms a shower of fire. When introduced into oxy- gen gas it spontaneously explodes, giving out intense heat and light, and aflbrding a very brilliant experiment. Small vials of ttis pyrophorus may be preserved for years, and may be made highly convenient, especially for itinerant smokerSi and tp those who are traveling through a wilderness^ The ignition of this substance is caused by its strong attrac- tion for the oxygen of the atmosphere. SULPHATE OP IKON. 1 eq. Sulph. Acid, 40-i-l eq. Oxide Iron, 36. COPPERAS. GREEN VITRIOL. 566. This well known salt is the sulphate of the protoxide of iron, and may readily be formed by the action of dilute sul- What is the use of alum I How is Homberg's pyrophorus prepared? WHITE VITRIOL. 333 phuric acid on metallic iron. The green vitriol of commerce is, however, manufactured directly from the sulphuret of iion, which nature furnishes in abundance. For this purpose, the ore, being raised from the earth, is exposed to the air, and oc- casionally sprinkled with water. By a natural process, the sul- phur absorbs oxygen firom the atmosphere, and is converted into sulphuric acid,.wiich is retained by the water. The acid thus formed, combines with the iron, forming a sulphate of the metal, which appears, on the decomposition of the ore, in a greenish crust. The mass is then lixiviated, or washed by pour- ing water through it, by which the salt is dissolved, and after- ward obtained in crystals by evaporating the water. Sulphate of iron is of a greenish color, has an astringent me- tallic taste, and is soluble in three-fourths of its weight of boil- ing water. According to the analysis of Berzelius, it contains 76 parts, or 1 equivalent of the sulphate, and 63 parts, or 7 atoms of water. Large quantities of this salt are employed in the arts, chiefly for coloring black, and making ink. SULPHATE OF ZINC, 82. , 1 eq. S. Acid, 404-1 eq. Ox. Zinc, 42. WHITE VITRIOL. 567. When diluted sulphuric acid is poured on zinc, for the purpose of obtaining hydrogen, the residue, if allowed to stand, forms small white crystals. This is the sulphate of zinc. For the purpose of commerce it is made by roasting the native sul- phuret of this metal, and then throwing it into water. The sulphate is formed 'by the decomposition of the, sulphuret, on the same principle as above described for the mamrfacture of green vitriol, and being dissolved by the water, is obtained by evaporation. Sulphate of zinc has a strongly styptic taste, is soluble in about two and a half parts of cold water, and reddens vegetable blue colors, though strictly a neutral salt. This salt consists of 82 parts of the sulphate, and 7 atoms, or 63 parts of water. It is employed in medicine, as a tonic and emetic. What sin^lar and curious property does this compound possess? For what use- ful purpose may tliis pyrophorus be employed ? What is (ho composition of sul- phate of iron ? What is the common name of sulphate' of iPon? How is green vitriol manufactured on a lai-ge scale 1 Explain the chemical changes by which the sulphuret of iron is converted into copperas. What are the usdflbf sulphate of iron ? 334 SAETPETEB, OK NITER. CHAPTER XXII. . NITRATES. 568. The nitrates, when thrown on burning charcoalj defla- grate, or produce a vivid combustion of the charcoal. , This is in consequence of the oxygen gas which they yield when heated, which unites with the combustible as it is expelled. All the nitrates, without exception, are decomposed at high temperatures, and by heat alone. Some of thein, as the- niti'ate of potash, or niter, yield oxygen gas in a state of considerable purity when heated, and hence are employed for the purpose of obtaining oxygen. As aU the nitrates deflagrate when thrown on burning char- coal, this simple test is sufficient to distinguish them from other salts. Another test of these salts, is iheir power of dissolving gold leaf, when mixed with muriatic acid. The only native nitrates are those of potash, lime, soda, and magnesia NITRATE OP POTASH, 102. 2 eq. N. Acid, 54-1-1 eq. Potash, 48. SALTPETER, OR NITER. 569. This salt may be prepared by saturating the common carbonate ©f potash with diluted nitric acid, and evaporating the solution until crystals are formed. That used in commerce, and for the manufacture of gunpow- der, is prepared by throwing into heaps, under cover, the re- mains of decayed vegetable and animal matter, found about old buildings. Heaps of such ^arth, when exposed to the air under sheds, gradually generate nitric acid, in consequence of the com- bination of the nitrogen, which is always contained in animal remains, with the oxygen of the atmosphe«e. The earth from such situations also contains lime, magnesia, and commonly considerable proportions of potash, from the ashes of burned wood. Thus there appears to be formed in these niter beds, Uf what is sulphate of zinc composed? What is the common name of sulphate of zinc "! How is t_lie sulphate of stinc-of commerce prepared 1 What proportion ol water does this salt contain ? What are the uses of white vitriol? W'hy do the ni- trates deflaftrate when thrown on burning charcoal 1 What gas do the nitrates yield^ when heater] 1 How may the nitrates be readily distinguished from all other saltsl What nitrates ar^fcit_iid in thp native state 1 What is the composition of nitrate oi p^jtash? What is the common name of nitrate of potash? SALTPETEE, OB NITER. 335 the nitates of lime, potash, and magnesia. After the earth has remained in this situation for several months being now and then sprinkled with water, it is Uxidated, and to the solution of these salts there is added a quantity of potash, which decom- poses the nitrates of lime and magnesia, thus leaving the nitrate of potash in solution. The niter is then crystallized by evap- orating the water, and afterward further purified for use. In the East Indies, this salt is formed spontaneously in the soil, and is found in small crystals on its surface. It is there- fore obtained with great facility, nothing more being necessary than to lixiviate the earth and purify the niter. Nitrate of potassa is a colorless salt, of a cool saUne taste, which crystallizes in six-sided prisms. It contains no wafer of crystallization, but its crystals always contain more or less water mechanically retained in them. When heated, it under- goes the igneous fusion, and at a red heat is decomposed, first giving out oxygen, and afterward both oxygen and nitro- gen, and if the heat be continued, tliere will remain only pure potassa. In chemistry, this salt ia employed in the manufecture of nitric and sulphuric acids, and for the purpose of obtaining oxy- gen gas. In the arts, it is chiefly used in the manufacture of gunpowder and fire-works. 570. Gunpowder is composed by weight, of six parts niter, one part sulphur, and one of charcoal. These ingredients being fii-st finely powdered separately, are then mixed into the form of a paste, with water, and beaten together with a wooden pestle, until they become very intimately incorporated. This paste is then granulated, by passing it through sieves, and care- fully dried in the sun, forming the grains of gunpowder. 571. Fulminating powder is made by mixing in a mortar three parts of niter finely powdered, two parts of carbonate of potash, and one part of sulphur. The whole being thoroughly mixed by grinding, forms the powder in question. When a quantity of this mixture is placed on a shovel, and heated gradually, until the sulphur begins to inflame, it ex- plodes,, giving a loud and stunning report, and leaving the ears hardly in a state to hear any thing more for hours, or if the quantity be considerable, even for days. Not more than ] 5 or what is the process of preparing the Diter of commerce? Id what country is niter formed spontaneously? When niter is heated, -what gases are expelled, and what sub- stance remains in the tire ? What are the uses of niter ? What is the composition ofgunpowdcr? How Ib fulminating powder prepared ? How is Jhis powder used 7 336 LUkAR CAUSTIC. 20 grains of this powder should be exploded at once, unless in . the open air. 5l2. Nitrate of ammonia. — The mode of preparing this salt was described under the article nitrous oxide. This salt is composed of one proportion of nitric acid, 54, and one propor- tion of ammonia, 17 = 71. It also contains one proportion of waters 9. Nitrate of bilter, 164. 1 eq. Nitric Acid, 54+leq. Silver, 110. LUNAR CAUSTIC. 57^. When silver is thrown into nitric acid; the metal is dissolved, with a copious disengagement of red fumes, which consist of the deutoxide of nitrogen, formerly described. The solution, if allowed to evaporate, will form large regular crystals, in the shape of flat rhombs. These, if the metal is iin- alloyed, are pure nitrate of silver. They contain no water of crystallization. They undergo the igneous fusion at a veiy moderate heat, and in this state, being cast into small cylin- drical moulds, form the substance so well known, and so univer- sally employed in surgery, and ibr other purposes, under the name of luriar caustic. A solution of this salt in water,_being applied to animal or vegetable substances, stains them, after exposure to light, of a permanent black color. The skin or hair may be made black in this manlier, and there is no doubt but persons have colored their faces and hands with this substance, as preparatory to the commission of the worst of crimes. No washing, or any other means, will whiten the skin, once stained with this solution, until the scarf-skin itself wears off, or is removed, which re- quires several weeks. The solution itself is perfectly trans- parent, and in appearance can not be distinguished from pure water. 674. Ikdeliblb ink is a solution of nitrate of silver in water, and is well known as the only substance in use, with which cotton and linen may be marked in a permanent manner. Nitrate "of silver, in soluticfti, is decomposed by a variety of substances, having a stronger attraction for oxygen than the sil- When silver is thrown into nitric acid, what gas escapes? What is the composi- tion of nitrate of silver'J Wliat is the common name of nitrate of silver ? What is lunar caustic? What effect does a solution of nitrate of silver have on the skin, or hair 1 What is indelible ink 1 What substances are mentioned which deoompoBe nitrate of silver 7 CHLORATES. 33Y ver has. By the action of such substances, the silver is revived, and appears in its metallic form. Thus, a stick of phosphorus placed in this solution, is soon covered with metallic silver ; and if the solution be heated to the temperature of boiling water, with a little charcoal in it, the metal will be reduced, and may be obtained in the form of crystals. The composition of the nitrate of silver is seen at the head of this section. There are many other nitrates, but none of them are of suffi- cient use, or interest, to require a description in this book. CHAPTER XXIII. CHLORATE. 575. The chlorates resemble the nitrates in many of their characters. These salts were formerly called oxymuriates. Most of them are decomposed at a red heat, with the evolu- tion of pure oxygen gas, and are converted into metallic chlorides. The pupil may find some difficulty in pointing out the dis- tinction between the chlorates and chlorides. -The chlorates are composed of chlorine united to oxygen, forming chloric acid, which acid, being combined with tibe metallic oxides, foi-m chlorates. The chlorides are composed of uncombined chlorine, either united to the metals themselves, or their oxides. Thus, chloride of lime is composed of lime, or oxide of calcium, and chlorine. But chloride of (^dnm is composed of the two sim- ple bodies, chlorine and the metal calcium, consequently con- tains no oxygen. "When the chlorates are decomposed by heat, as above stated, and converted into chlorides, the change is produced by the ex- pulsion of the oxygen which the compound contained, and the subsequent union between the chlorine and the base of the alkali, or the metal itself, Thus, when chlorate of potassa is heated, its oxygen escapes, while the chlorine remains, and com- bines with the base of the alkali, foriping phloride of potassium. What were the chlorates formerly called 1 What is Baid pf the decomposition of the chlorates by heatl What is the difference between the chlorates and the chlo- aftes 1 What are the chemical changes by which the chlorates are converted mto iPchloridesI 29 338 CHLOKATES. In producing tke chlorates, it is not necessaiy tbat the chlone acid should first be formed, and then combined with the salifia- ble base, since the same result is produced by merely passing the chlorine through a solution of the alkali. This will be ex- plained under the chlorate of potassa. - The chlorates are all of them artificial compounds, none of them having Ibeen discovered in the native state. Most of them yield their oxygen to combustibles with such facility as to pro- duce explosion. Thus, when chlorate of potash is rubbed in a mortar with phosphorus, ' or struck in contact with sulphur, violent detonations are produced. SYe. Gun cotton.^ — This is a recently invented explosive corppound, which it was supposed by some would, for many uses, take the place of gunpowder. But the energy of its action, and the uncertainty with which it explodes, are such as to render it a dangerous agent,, especially in the hands of the inexperienced. It is therefore, at present, employed rather as a curiosity than as an article of general utility. 577. MANUFACTURE.^Gun cotton is made by a veiy simple process, though manufactuTers differ somewhat in the propor- tions of their materials. The following is said to be one of the best : Mix together equal proportions of nitric acid and of strong sulphuric acid, say an ounce and a half of each, and into this immerse one hundred grains of clean cotton fiber, for five minutes. Then remove the cotton, and wash it in cold water until every trace of the acid is removed. Having dried it in the sun, or by means of a gentle heat, not to exceed 120 de- grees, the manufacture is finished.- Gun cotton thus prepared, has the appearance of the com- mon article, tinged a little yellow ; ihoiigh, on trial, it will be found to have lost much of its strength. It is a dangerous agent in young hands, and must always be iised with caution, sometimes exploding whennot expected, and with only the heat of boiling water. Its combustion is as in- stantaneous as the best gunpowder, and is attended by an im- mense volume of flame, leaving not a trace in the form of carbon, or ashes, behind. When confined, it explodes with, terrible energy, and may therefore ultimately become a cheap and efficient agent in the In producing tbe chlorates, is the chloric acid first formed, or is it only necessary to pass the chlorine through the alkaline solution ? Do any of the chlorates occur in nature! What is said of the facility with which the chlorates yield their oxygen to combustibles 1 How is gun cotton made? What is the appearance of this Bf- ticle ? What is said of its dangerous properties ? OXTMURIATE OF POTASH. 339 art of mining. Its power of propelling balls is said to>e about eight times greater than the same weight of gunpowder. 578. Detonating sugar. — Prof. Sobrero, of Turin, has dis- covered that detonating sugar may be prepared thus : Pour on powdered loaf sugar a mixture of two parts, by volume, of sul- phuric, and, one of nitric acid. The sugar is at once converted into a viscid mass. On adding about 20 times as much water as there was acid, the mass is converted into a white substance, which is diffusible in the acid mixture, is insoluble in water, but is quite soluble in alcohol and sulphuric ether. In a moder- ate heat it melts and is decomposed, without detonation ; but if suddenly heated to redness, it explodes like gunpowder. By a blow with a hammer it explodes, but feebly. It has not been applied to any useful purpose. CHLORATE OF POTASH. 1 eq. Chloric Acid, 76-1-1 eq. Potash, 48. OZTMORIATE OF POTASH. 579. The chlorate of potash is formed by passing chlorine gas through a solution of the pure csftistic alkaU in water. The pure potash is Teadily prepared in the following manner : Mate a solution of the carbonate of potash in its own weight of hot water, in an iron vessel, and add to this as much quicklime by weight, as there was potash, and let' the mixture boil for about ten minuteis. Then strain the solution through a linen cloth, and it will be fit for use. The hme absorbs the carbonic acid from the potash, forming with it an insoluble compound, thus leaving the alkali in its pure, or caustic state. The caustic potash being placed- in a proper v^sel, the chlorine is passed into, if as long as any of the gas is absorbed. 580. Apparatus for chlorate of potash. — The appar- atus for this purpose is represented at Fig. 102. The solution is contained in the three-necked bottle. The chlorine may be evolved by first introducing into the retort two ounces of finely powdered black oxide of manganese, and after eveiy thing is arranged, as in the figure, pouring on this, through the safety tube, four ounces of muriatic acid, and then applying a gentle heat. When the solution is saturated, the gas will pass ofi" by the bent tube into the open air. What is said to be its force, compared with gunpowder ? What is the composi- tioi) of chlorate of potash i Uow is caustic potash prepared T 340 OXrMURIATE OF POTASH. FIG. 102. Chlorate of Potaah. To obtpn the salt, the solution is evaporated -with a gentle heat, and' on cooling, small shining crystals of chlorate of pot- ash will be deposited. The first product only must be reserved for use, as the solution will afterward form crystals of muriate, instead of chlorate of potash. In the production of this salt, by the above process, the chloric acid is formed by the decomposition of the water, the oxygen of which unites with one portion of the chlorine to form the acid, while the hydrogen thus disengaged, unites with another portion of the chlo- rine, forming muriatic acid. Hence the solution as above intimated, contains both muriate and chlorate of potash. When chlorate of potash is heated, it gives off oxygen gas nearly pure, and chloride of potassium remains. 581. DfiTONATBS with'sulphur. — If two grains of this salt are mixed with one grain of sulphur, and the mixture is struck, or pressed suddenly, a loud detonation is produced. When struck in contact with -powdered charcoal, a similar effect re- sults. If a grain of the -chlorate and half a grain of phosphorus be rubbed together in a mortar, very violent detonations will be the effect. In making this- experiment, the hand should be covered with a glove, and the face protected by a mask, or averted, as the inflamed phos|jhorus is sometimes projected sev- eral feet by the explosion. If a httle of this salt be mixed with twice its weight of white sugar, and on the mixture a few drops of strong sulphuric acid be poured, a sudden and vehement inflammation will be produced. These phenomena are owing to the facility with which the chlorate of potash pai-ts with its oxygen to combustible substances. 582. Friction matches. — This salt forms the base of the matches, by which a Ijght is instantly obtained. The chlorate What is the use of the lime in preparipg caustic potash 1 Explain tbo process bT which chlorate of potash is formed. HoW is the chforic acid foniied by thieprocepsl Whence comes the muriate of potash which the solution contains? Mention some of the experimentswhich may be marie with this salt and a combustible 7 How are the red matches prepared from this salt t PH0SPHAT3 OF SODA. ~ 341 being finely pulverized by itself, is then mixed with twice its weight of jvhite sugar, moistened so as to prevent explosion, and afterward made into a paste with mucilage of gum arabic. A little of this paste is fixed on the ends of brimstone matches, •so that when it is inflamed, first the sulphur and then the wood is set on fire. These matches require only to be rubbed on a rough body, when they instantly buret into flame. Attempts are said to have been made in France, on a large scale, to substitute the chlorate of potash for niter in the manu- facture , of gunpowder. But it was found that the workmen could not mix the ingredients, under any circunastanoes, without the greatest danger, and that in many instances explosions took place after the powder was prepared ; the attempt was there- fore abandoned. Attempts have also been made to use mix- tures of this salt for percussion priming, but it was found that the chlorine acted so readily on the iron, as soon to injure the gun, and it was therefore laid aside, for the fulminating mer- cury, which is now generally used for this purpose. CHAPTER XXIY. PHOSPHATES. 583. The phosphates of the metals are converted into phos- phurets by heat and charcoal. Some of the alkaline and earthy phosphurets undergo a partial decomposition by the same means, while others are not changed. A number of phos- phates are found in the native statfl, such as tliose of iron, lime, copper, and lead. FHOSFHATE OF BODA, 64. 1 eq. Acid, 32-t-l eq. Soda, 32. 584. This salt is prepared on a large scale in chemical manu- factories, by neutralizing, with carbonate of soda, the super- phosphate of lime, procured by the action of sulphuric acid on burned bones. The phosphate of lime, which the solution con- tains, is separated by filtration, and the liquid containing the what Is said of the attempts made to substittile the chlorate of potash for niters in the preparation of gunpowder 1 W^hat are the phosphates which occur in the native state 1 What is the composition of phosphate of soda? How is the phosphate of soda prepared on a tar^e scale 1 What is the use of phosphate of soda? 29* 342 BOEAX. phosphaW of soda is then evaporated until crystals of the salt are deposited. The phosphate of soda is composed of one proportion of the acid, 32 ; one proportion of soda, 32 ; and twelve proportions of water, 108. It is employed in medicine, and in chemistry, as a reagent. BORATES. 585. The borates are few in number, and being, most of them, of no use, are little known. They are distinguished by imparting a green color to the flame of alcohol, when dissolved in it. Any borate, being first digested in sulphuric acid, then evapora:ted to dryness, and the lesidue boiled in alcohol, pro- duces this effect. Hence, this is the test for these salts. BIBORATE OF SODA, 80. 2 eq. B. Acid, 48+1 eq. Soda, 32. BOKAZ. 686. This is the only borate of any consequence, either in chemistry, or the arts. It occurs' native in certain lakes in Pereia and Thibet, which are said to be supphed-from springs. The edges and shallow parts of these lakes are covered with a crust of borax, which being removed, another deposition is formed. It is imported into Europe and America in its rough or impure state, undei- the name of Tincal, and which being purified, forms the refined borax of commerce. ' This salt is capable of being crystallized, in six-sided prisms, though more conimonly seen in amorphous pieces. It is soluble in six times its weight of boiling water. When exposed to heat, it enters into the watery fusion, and at the same time swells to several times its former bulk. When the water of crystallization is expelled, it passes silently into the ig- neous fusion, and forms a" vitreous transparent globule, called fflass of borax. Borax is used as a flux, by braziers and mineralogists, and is employed in medicine, in cases of sore mouth. Besides the constituents of this salt placed at the head Of this section, borax contains 8 atoms, or 72 parts of water of crystallization. How are the bprates dlstingaiBhed 1 What is the composition of the biboraf'e of Eodal What is the common name of this salt ? Where is borax found 1 What is glass of borax 1 What are the Uses of borax 7 CAKB0NATE8. 348 FLUATES. * SS?. The nature of the filiates, owing^ to the uncertainty which exists concerning the base of the fluoric acid, are little known. These salts may, however, be readily identified by first reducing them to powder, aiid pouring on sulphuric acid, when, with the aid of a gentle heat, fluoric acid will be disengaged, and may be recognized by its property of corroding glass. Several fluates are found in the native state, and it is from these only, or rather ^rom one of them, the fluate of hme, that the fluoric acid is obtained. The topas is a compound of fluoiic acid, alumine, and silex. Its chemical name is fiuosilicate of alumina. FLUATE OF LIME, 38. 1 eq. F. Acid, 10+1 eq. Lime, 28. DERBTGHIRE BPAR. 588. This salt is found in its native state, in many parts of the world. It is often seen as an aiticle of luxury, cut into the form of vases, candlesticks, or boxes, under the name of Derby- shire spar. Its colors are purple, green, red, blue, and white, often mixed in the same specimen, and forming one of the most beautiful of mineral substances. This substance crystallizes in a great variety of forms, the cube being the most common. Some varieties of this salt phosphoresce, when thrown upon hot iron, emitting light of various colors, as green, red, blue, &c. When fluate of lime is exposed to the united action of sul- phuric acid and heat, it is decomposed, the fluoric acid being liberated in the form of gas, while a sulphate of lime is formed. By this method the fluoric acid is obtained. CARBONATES. 589. Some of the carbonates exist in great abundance in the native state. The carbonate of lime forms entire mountains. .These salts may generally be distinguished from all othere by their efiervescence, when exposed to the action of the stronger acids. This is owing to the.escape of carbonic acid during the decomposition of the salt. Thus, when sulphuric acid is poured What proportion of water does borax contain ? How may the fluates be tnownl From what natui-al substance is the fluoric acid obtained 1 What is the chemical name of topaz? What is the composition, and what the combining number, of fluate of lime 1 What is the common njime of fluate of lime ? How is fluoric acid ob- tained? What carbonate forms entire mountains? 344 PEABLASH. on carbonate of lime, the lime and acid combine, while the car- bonic acid, being thus liberated, escapes through the solution, and occasions the eflfervescence. The carbonates, with the exception of those of potash, soda, and ammonia, are vfery sparingly soluble in water. The car- bonate of lime is entirely insoluble in pure water, but is sUghtly soluble in water containing carbonic acid. • Many carbonates of the metals, as well as of the earths, are found native. The carbonates of hme, of soda, barytes, stron- tian, magnesia, manganese, of iron, copper, and lead, are all native salts. CARBONATE OF POTASH, 70. 1 eq. C. Acid, 22+1 eq. Potash, 48. POTASH. PEARLABH. 690. The well known substance pearlask, is the potash of commerce deprived of its impurities, and saturated with carbonic acid. The potash of commerce is obtained by lixiviating the ashes of land plants, or common wood, and evaporating the so- lution to dryness. In this state it is of a dark reddish color, and wheh recently prepared, is exceedingly caustic to the taste and touch. By age its caustic property is gradually lost, in consequence of the absorption of carbonic acid from the at- iDosphere. Potash is chiefly employed in making soft soap and glass. The Ucarbonate of potash is prepared by transmitting a cur- rent of carbonic acid gas through a solution of the carbonate. This salt contains 44 parts, of carbonic acid and 48 parts of" potash, making its equivalent 92. It also contains 9 parts, or one proportion of water of crystallization. This is far milder, both to the touch and taste, than the carbonate. At a red heat it parts with one proportion of its acid, and is reduced to a carbonate. This salt is in common use under the name of sal ceratis. It ' is employed for culinary purposes ; in many of the arts, and in medicine. The bicarbonate of potash may be obtained in regular pris- matic crystals by evaporating its solution gradually. How may the carbonates be distinguisbed from all other salts? What occasions the eflfervescence when carbonate of lime is acted on by a strong acid I What car- bonates are found native? What is the composition of carbonate of potash ? What is the common name of carbonate of potash 1 How is potash obtained 1 What are the uses of potash 1 How is the bicarbonate of potash prepared 1 What is the com- mon name of bicarbonate of potash? 345 CARBONATE OF BODA, 54. 1 eq. C. Acid, 22+1 eq. Soda, 32. EODA. 591. The carbonate of soda is prepared by burning plants which grow in the sea, and lixiviating their ashes. The im- pure soda of commerce is known under the name of barilla, and is obtained by burning certain sea plants expressly for the pur- pose. An inferior kind is called kelp, and is prepared with less care and frpmafliflFerent plants. The carbonate of soda of commerce is prepared by dissolving barilla in water, filtering the solution, and then evaporating the water. If the evaporation is conducted slowly, the salt shoots into regular crystals. By continued gentle heat these crystals part with their water, and are rendered anhydrous without loss of carbonic acid. This salt dissolves in about its own weight of hot water. Carbonate of soda is composed of one proportion of the acid, 22 ; one proportion of soda, 32, and 10 proportions, or 90 parts of water. Hard soap is prepared entirely from soda. Bicarbonate of soda is made by transmitting earbonic acid through a solution of the carbonate in water. It may also be prep^ed by placing ves- sels containing the carbonate in the vats of a distUlery, or brew- ery, where the process of fermentation is carried on. By either process the carbonate is made to absorb an additional proportion of the acid, and is thus converted into the bicarbonate. This salt contains two proportions of the acid, 44 ; one pro- portion of soda, 32, and 9 parts of water. The bicarbonate is in general use as a medicine, and forms the alkaline portion of soda powders. It also forms the basis of that agreeable beverage, soda-water. MURIATES. 592. The muriates may be distinguished by the emission of muriatic acid ftimes when tested with strong sulphuric acid. And -also when in solution, by forming a white insoluble chlo- ride, wben tested with nitrate of silver. The muriates, when in a dry state, "are chlorides. How IS the carbonate of soda prepared 7 What is the name of the impure soda of commerce? Wbat,is kelp ] What is the composition of carbonaCeof soda? What Jkind of soap is made from soda? By what process is bicarbonate of soda made) llow docs the bicarbonate of soda differ from the carlronate of eodal 346 SAL AMMONIAC. MURIATE OF AWMOinA, 54. 1 eq. M. Acid, 37+1 eq. Ammonia, lY. \ BAL AMMONIAC. 593. Sal ammoniac was formerly imported from the East, and particularly from Egypt; but has for many years been manufactured in large quantities, in several parts of Europe. Several processes are used at the different manufactories. The following is the method employed at a principal manufactory in Paris : " Two kilns are constructed of brick, in which are placed proper vessels for containing the materials employed. Into one of these vessels is placed a quantity of common salt, on which is poured sulphuric acid, and into the other are'thrown animal matters, such as horns, bones, parings of hides, &c. On the application of heat there is extricated from one vessel, muriatic acid gas, and from the other, ammonia. These gases are conducted by flues into a chamber hned with lead, wliere they combine, and form solid muriate of ammonia, which incrnste the roof and sides of the room, and enters into solution with a stratum of water on the floor. Muriate of ammonia, as seen above, is composed of muriatic acid and ammonia. Both these constituents exist in the state of a gas, but when combined they form the solid compound in question. The elements of ammonia, (fiitrogeB and hydrogen,) exist in all animal substances, and thfe muriatic acid is a constituent of common salt. In the above process the ammonia is extricated by the heat, while the muriatic acid is evolved by the decom- position of the common salt. This method of preparing sal ammoniac may be illustrated in the following manner, and affords a very instructive and satisfac- tory experiment. Provide two flasks, each furnished with a tube, as represented at Fig. 103. Into one of these put a handful of common salt, and a little sulphuric acid, and into the other What are the uses of bicarbonate of soda? ^ What JB the composition of muriate of ammonia? What is the common name of muriate of ammonia ? What is the pro- cess for making muriate of ammonia 1 FIG. 103. C^ Sal Ammonia. HTDKOSULPHURETS. 34^ put equal parts of powdered quicklime and sal ammoniac ground together. Then invert over the ends of the tubes a-tall bell glass, or a tubulated receiver, as seen in the figure, and ap- ply a gentle heat to the bottom of each flask. The two gases will be disengaged, and combining, will form a white cloud within the receiver, which will gradually condense and cover its sutface with soUd sal ammoniac. If one of the gases be intro- duced into the receiver without the other, it will remain trans- pai-ent and unseen until it meets the other, when a dense white cloud will instantly be formed. In this experiment the ammonia is set free, in consequence of the decomposition of the muriate, by the quickUme, which combines with its muriatic acid. The article used in smelling bottles, and called volatile salts, hartshorn, &c., is a carbonate of ammonia. HUKIATE OF BARTTES, 115. 2 eq. Muriatic JlcH, 37-f-l eq. Barytes, 18. 594. This salt is_ formed by saturating muriatic acid with carbonate of barytes. For this purpose, either the native or artificial carbonate may be employed. Muriate of barytes crystallizes in four-sided tables, and con- tains nine parts, or one proportion of water. It is soluble in about two and a half times its weight of water ; and is much employed as a reagent in chemistry. HTDROSULPHURETS. 595. Sulphureted hydrogen is formed by the action of mu- riatic acid on sulpfeuret of antimony, or some other metaUic sulphuret. This gas is capable of forming salts with the alkalies, or alka- line earths, when passed into their aqueous solutions. It thus performs the office of an acid, and the compounds so formed are called hydrtsulphurets. . The hydrosulphurets are all of them easily decomposed, with the disengagement <5f sulphureted hydrogen ; the fetid odor of which seldom leaves the experimenter in any doubt concerning the character of the compound. How may the process of making the muriate of ammonia be illnstrated by the ap- paratus represented at Fig. 103. What is the composition, and what the combining proportion, of muriate ofbarytes ? How is the muriate of barytes prepared 7 What ar«iJI)£ hydrosulphurets? How are Ihe hydrosulpliurets formxl 1 348 HYDRACIDS. FIG. 104. BydrosulpkuTet of Potash. HYDROSULPHURET OF POTABH. "596. The best method of making this salt, or of impregnating water wth any other gas, is by means of the apparatus repre- sented by Fig. 104. The solution of pure potash in water, is placed in the lower vessel, while the materials for extricating the sulphureted hy- drogen are contained in the retort. The influx of the sul- phureted hydrogen into the lower vessel, drives the fluid into the upper one, the junc- ture between the two being made close by grinding. Thus, the fluid pressing on the gas, the absorption of the latter is greatly facilitated. In this manner soda water may be made,' the tube in the upper vessel being convenient for the introduction of an additional quantity of soda, when required, or for a similar purpose when experimenting on other substances. These vessels being made of glass, the change in the height of the fluid, and consequently its degree of pressure on the gas, are made obvious. This salt forms large transparent crystals, in the shape of six-sided prisms. Its taste is bitter, and it is soluble in water and alcohol. COMBINATIONS OF HYDROGEN.,, 597. There are several combinations of hydrogen with various substances, and several names expressive of such com- pounds, some of which are new, and which, therefore, we will explain at this place. HyDRACIDS. 698. The hyrdracidg are combinations of hydrogen with cer- tain-bases, which opinpound performs the part of an acid in the forma;tion of salts. These acids and their salts are therefore remarkable for the absence of oxygen, and the presence of hy- Exi)Iain Fig. \6i, and flescribe in what manner the water presBes on a gas generated in the retort, and force it into the upper vessel. What are the hydracidel HTDKACIDS. 349 drogen. It was formerly supposed that oxygen was the univer- sally acidifying principle, and hence its name, as already ex- plained. But further investigations have shown that salts are formed without the presence of oxygen, hydrogen in one sense, being the substitute for oxygen. These compounds, therefore, are called salts of the hydradds, in order to distinguish them from the salts of the oxyacids, which contain oxygen, as the acidifying principle. The substances with which hydrogen unites to form acids, are chlorine, iodine, bromine, fluorine, selenium, sulphur, and cyanogen. These acids, according to the nomenclature formerly explained, form severally, hydrochloric, hydriodic, hydrohromic, hydrofluoric, hydroselenic, hydrosulphuric, and hydrocyanic acids. The hydrocyanic is the prussic acid, the hydrochloric, the muriatic, and the hydrosulphuric, sulphureted hydrogen ; to the others, there are no old, or common names. The salts which these acids form with alkaline or metallic bases, are hydrochlorates, hydriodates, hydrobrom^.tes, hydro- fluorates, hydroseleniates, hydrosulphates, and hydrocyanates. These names qf course indicate the constituents of the several compounds to which they apply. ' Some of these salts are highly important and universally known, while others are worthy of notice only as chemical compounds. We shaftiere refer only to the former. The hydrochlorate of ammonia is the muriate of ammonia, more commonly known under the name of sal ammoniac. Hydrochlorate of soda is the muriate of soda, or common salt. The hydrocyanates, or prussiates, have already been ex- plained. The hydroferrocyanates are salts which were formerly called triple prussiates. They are combinations of hydrogen, iron, and cyanogen, as the name indicates. The term hypo is prefixed to a number of acids and salts, to denote the first degree of oxygenation. Hypo means sub, or under, and is employed in cases where bodies are capable of combining with more than two proporticftis of oxygen. The nomenclature of the acids of sulphur forms an example. These acids are four in number, depending on different degrees of oxygenation, and are termed 1, AyposulphuroMS acid ; 2, sulphur- OiM acid; 3, Ayposulphuric acid; 4, sulphuric acid. When these several acids are combined with salifiable bases, the names of the salts thus formed are hyposulphites, sulphites, hy- posulphates, and sulphates. 30 PART III. CHAPTER XXV. OEGAOTC CHEMISTRT. 599. Organic cHemistry compreheiids the chemical history of all those diflferent substances or elements, which form yeget- ahle and animal bodies. ' In many respects this department of chemistry dififers very materially from tliat of the mineral kingdom. The analysis of inorganic bodies show, that each substance which dififers mate- * riaUy from another substance, contains some principle peculiar to iteelf, or that the difference arises from the multiplied pro- portion of some one constituent, while the other remains the same. Numerous instances of both these case?will be found, on referring to th6 composition of various substances, and to such compounds as are formed by the union of different, but definite proportions of the same- ele^nts. Thus, sulphur, united with oxygen, and carbon united to the same element, form two compounds differing from each other in every respect, with the exception that tbey both combine with salifiable bases and form salts. And mercury, with one proportion of chlorine, forms a compound, which may be taken in large doses, and is in general use, as a medicine, while with another proportion of the same element, it becomes one of the most corrosive poisons known. On the contrary, the elements of organized bodies are com- paratively few in number, and although the diflferent products, of which there is a great variety, must be composed of different proportions of these few elemente, yet the resulting compounds of the same elements seldom present qualities differing widely from each other, like those of the mineral kingdom. There is another wide difference between organic and inor- ganic chemistry. The latter presents us only with compounds What dofis the third part of this volume treat of 7 What does organic chemistry comprehend t In what respect does organic chemistry differ from mineral chemis- tryl WJiat is said of the number of elements in organized bodies 3 What is the dif- ference in the mode in which inorganic and organic substances are formed 1 ORGANIC CHEMISTBT. 351 fonned in consequence of afiBnity, or the attraction of the heter- ogeneous particles of matter for each other. But organic sub- stances are foiToed by the action of peculiar organs, each organ being endowed with the power of producing different results from similar elements. Thus, the several organs of the same tree produce wood, bark, flowers, fruit, gum, honey, &c., from the same elements ; while the organs of secretion, and growth, in animals, produce bone, marrow, flesh, bile, fet, hair, nails, &c., fi-om the same food. In general the chemist finds little difficulty in decomposing and afterward imitating the products of the mineral kingdom, by again Joining the same elements to each other. But although he can decompose the products of organic ac- tion, aiid find the proportions of their elements, .he never has been able to recompose or imitate these compounds. Thus, sugar and gum are found to be composed of hydrogen, oxygen, and carbon, and the exact proportions of these elements which they contain, are known ; but no chemist has yet found the means of combining these elements, so as again to form sugar and gum. Organic substances differ also from inorganic, in their ten- dency to decomposition. Thus, all animal and vegetable bodies, without exception, when exposed to the agencies of air and moisture, undergo spontaneous changes, their elements entering into new combinations, and forming new compounds to the en- tire destruction of the old ones. The compounds of the min- eral kingdom, on the contrary, are generally permanent, many of them having probably not suffered the least change since their creation. The changes which result from the decomposition of animal and vegetable substances, are often exceedingly complicated, and particularly when this is produced by heat, and in a close vessel. A compound, consisting of carbon, hydrogen, and oxy- gen, when thus treated, will produce water, carbonic acid, car^ bonic oxide, and carbureted khydrOgen, and if the substance contains nitrogen, in addition to these, there will also be formed ammonia,' and cyanogen. What substances do the different organs of a tree form, from the same elements t What are the different substances mention^, which the several organs of an animal 'produce from the same food 1 What is san of the power of the chemists to imitate inorganic and organic substances? What is the difference between inorganic and organic bodies with respect to the tendency to decomposition 7 What is said with re- spect to the complicated changes which organic bodies undergo, by decomposition 1 3S2 VEGETABLE CHEMIStKY. CHAPTER XXVI. VEGETABLE CHEMISTET. 600. Before proceeding to descsribe particular substances, of tbe means by wMcli the coniposition of vegetable produictsi are ascertained, and, to show the elements of which they are com- posed, we shall give a short account of the process of vegeta- tion, and point out the chemical changes which take place dur- ing the growth of plants. We have already stated, that the elements of which veget- ables are . composed are few in number, and that the, great variety, which we observe in plants, and their diflferent parts, must therefore arise from the different proportions in which these few elements unite. The constituents of vegetables are carbon, hydrogen, amdi oxy- gen, to which is occasionally added small proportions of nitro- gen. The nitrogen, however, occurs only in such plants as emit the' animal odor during their decomposition, as cabbage, and some of "the mushrooms. Notwithstanding the great variety which we observe in the texture, color, ta^te, smell, hardness, and other properties of different plants, as well as their several parts, sudi ,as flowers, seeds, and fruits, it is certain that their composition differ only in respect to different proportions of these elements. , 601. Essential organs Of plants. — The essential organs of plants, are the root, the stern, the leaves, the flowers, and the seeds. The root serves to attach the plant to the soil, and is one of its organs of nutriment. The stem, which is usually erect, serves to elevate the leaves, the flower, and the fruit, from the ground, by which they are exposed to air and light.. The leaves are the respiratory organs of the plant, and the flower performs the important oflBce of .giving rise a,nd nourishment, to tfee seeds, by which the plant is reproduQed. When a seed is exposed in a situation which favors its growth, it soon undergoes a change. It swells, grows soft. What are the elements, or constitueats of which all vegetables are composed? How is the great variety under whicli ^etables appear accounted for, when their elenients are so few in number 7 What are the essential organs of plants 7 What purpose do each of these organs serve 1 When a seed is placed in circumstances favorable to its growth, what changes does it undergo 1 VJiQEXABLE CHEMISTRY. 353 bursts its membrane, or shell, and at the same time, from being insipid and farinaceous, it becomes sweet and mucilaginous, thus becoming fit nourishment for the new plant. The stem and leaves are soon after elevated above the earth, in search of air, warmth, and light, while the rtjot sinks into the ground in search of moisture and nourishment. The seed, however various in form, consists essentially of the cotyledon, the plumulet, and the radicle. The cotyledon, con- tains the matter necessary for the early nourishment of the young plant. Sometimes this is single, sometimes double, and sometimes it is divided into lobes. The plumula is enveloped within the cotyledon, and is the part which produces the stem and leaves. The radicle shoots downward, and becomes the root. ' The gai-den bean, having been *''='• i^^- a few days in the ground, shows all these parts in perfection, and is represented by Fig. 105. The cotyledons form the bulk of the seed, and are marked a, a. The , plumula, b, and the radicle, c, "/'■ are represented as beginning to shoot, while d, d, mark the membrane by which the whole aarden Bean. ... has been inclosed. , 602. Germination of seeds. — The circumstances necessary for healthy germination are, a temperature above the freezing , point, and Iselow 100 degrees ; moisture in a certain proportion, depending on the kind of seed ; and a proper access of air. The joint operation of these several agents seem absolutely requisite ; for seeds exposed to the action of air and moisture, at a temperature below 32 degrees, will not grow, though they may not be absolutely destroyed by the frost. Nor will see^ vegetate without the contact of some air, though both heat and moisture be present. This is shown by burying seeds deep in the ground, where they are known to lie in a torpid state for years, and in some instances, it is supposed, even for centuries. Thus, when alluvial soils are exposed to the sun, though taken from many feet below the surface, they afford grass from titie What is said of the stem and roots t Of what does a seed essentially consist 1 What is the cotyledon 1 What is the plumula 1 What is the radicle) What are the circumstances necessary to healthy germination 1 ^ Will seeds grow, when ex- posed to air and moisture, under 32 degrees } Uow is it shown that seeds will not vegetatL without air % 30* 354 VEGETABLE CHEMISTRY. seeds they already contain, and which had before remained tor- pid an imknown length of time, for want of the gecminating power of oxygen. This curious fact is confirmed by the experiment of Mr. Ray, who found that seeds exposed to heat and moisture, but con- fined in the exhausted receiver of an air-pump, showed no signs of germination. 603. Germination requires orrGEN. — Other experiments have proved that seeds will not grow under any circumstances, without the presence of oxygen. Healthy seeds, supplied with abundance of heat and moisture, but confined to an atmosphere of nitrogen, carbonic acid, or hydrogen, showed no signs of germination. It appears, howevef, that only a very small quantity of oxy- gen, is required for this purpose, for Mr. Bay found diat when the receiver of his aar-pump was not completely exhausted, the seeds would sprout. In this respect several experimenters have been deceived, and in consequence of not producing a complete vacuum, have concluded that air was not necessary for the process of germination. . It being thus certain that seeds will not germinate without the aid of oxygen, it hardly need to be Stated that the future growth of the plant must require the presence of liie same principle. The immediate sources fi-om which plants draw their nour- ishment, has been a matter of doubt and controversy. It is certain, however, that they will not grow without the presepce of heat, air, and moisture. It also seems necessary for their vigorous growth, that theu- roots should be placed in the earth, but whether this is requisite for their nourishment, or whether the ground serves merely to give them support, was a question long in dispute. 604. Van Helmont's willow.: — ^Van Helmont planted a willow, which weighed five pounds, in a pot containing 200 pounds of earth. This he watered for the space of five years, and, at the end of that time, the tree was found to weigh 169-^ pounds, while the earth in which it had stood, being dried as at first, was found to have lost only two ounces. Here, then, was an increase of 164 pounds weight, and yet the food of the What was Mr. Ray's experiments on the growth of seeds 1 What gas is ahsolutely necessary to the growth of seeds t What are the agents necessary for the vigorous growth of a plant 1 What was the ejcperiments of Van Helmont, and what was it supposed to decide t VEGETABLE CHEMISTRY. 365 plant had been water only. This experiment was supposed to settle all controversy, and to decide that the sole food of plants was water. But Mr. Boyle afterwards showed, that the water with which the tree was moistened, contained earii, from which the willow derives at least a part of the nourishment. After a great variety of curious, and many elaborate experi- ments on this sulgect, it has been ascertained, that plants will germinate in pure water, and that the young plant, for a time, will gi-ow with no other aliment; but that it finally grows sickly, and does not come to maturity and produce seed, with- out other nourishment. A proof that plants do not thrive on water alone, is drawn from the well known fact, that soils become sterile by a long succession of crops, but are again made productive by the addition of new ingredients. JTor does it appear that the simple earths, or clay, without some additional ingredients, are sufficient to support die growth of vegetables. On majdng an experiment, by planting seeds in pure silica, almnina, or inagnesia, moistened with pure water, and exposed to proper degrees of heat, it was found that, al- though germination was effected, the young plants did not grow, imtil supplied with water, which contained vegetable or animal remains in solution. It is for this reason, that earth, taken from a depth below the surface, never forms a productive soil. The soils best adapted to the growth of plante, always contain a proportion of vegetable mould, that is, the remains of decayed vegetables. This mould contains a quantity of matter which is soluble in water, and it is probable that the fertility of a. soil depends, in a degree, on the quantity of soluble matter it oonteins, and that in this manner the ahment of plants is prepared for absorption by the roots. The sdp, which is prepared from the fluid absorbed by the roots, is constantly ascending up the vessels of the plant during its growth, until it arrives at the leaves. Here it undergoes a considerable change, the watery pa,rts being thrown- off by the persjnration of the leaves, while that which remains is convei-ted into a peculiar juice, called the true sap, which, like the blood How did Mr. Boyle show that the willow did not live on water alone t Wliat has been ascertained with respect to the growth of plants in pure water? . What common fact, concerning soils, show that plants w!U not thrive on water alone 7 What, is said of the growth of vegetables in the pure earths? Why does not the earth, taken from a considerable depth below the surface, form a productive soiU -On what doea the fertility of a soil appear to depend 1 366 VEGETABLE CHEMISTRT. of animals, is afterward employed in forming the various sub- stances found in plants. The leaves of plants are not only their perspiratory organs, but they also serve the purpose of respiration, that is, thfff alternately absorb carbonic acid and emit oxygen at their surfaces. Plants constantly throw off moisture fi-om their surfaces, by perspiration, but the quantity is much larger during the day than during -the night. Dr. Hales found that a cabbage trans- mitted, daily, a quantity of water nearly equal to half its weight. The office of transpiration is performed entirely by the under side of the leaf, and may be almost entirely stopped by spreading varnish on that surface. 605. Plants absorb carbonic acid. — The fact that plants absorb carbonic acid was first observed by Dr. Priestley. Having suffered a sprig of mint to vegetate for ten days in a quantity of this gas, which would instantly extinguish a candle, he found, at the end of that time, that the candle was not ex- tinguished by it as before, but that the flame continued for a while. Subsequent experiments have shown, that pure carbonic acid stops the growth of plants, but that a small quantity is absolutely necessary to healthful vegetation. In Dr. Priestley's experiment, the sprig of mint could not have qualified the air in which it was confined, for the support of combustion, merely by the absorption of the carbonic acid. It must be inferred, therefore, from this experiment, that the plant not only absorbed carbonic acid,- but that it gave out oxy- gen, or that it converted the carbonic acid into oxygen gas, and this inference has been confirmed by other experiments. . Plants, while growing in the light, absorb carbonic acid from the atmosphere, which they decompose; the oxygen, of which this acid is in part composed, being emitted, while the carbon is retained by the plant. 606. Plants emit oxygen. — ^If a growing plant, as a sprig of mint, be exposed to the sun, in a glass vessel filled with water, it constantly emits from its leaves small bubbles of air, which on examination are found to be oxygen gas. Now What changes does the sap undergo in the leaves T What is the true sap, and what its use ? What otSce do the leaves perform besides that of perspiration 7 What proportion of water did Dr. Hates find a cabbage to transmit 7 What part of the leaf thiriiws off moisture 1 What was Dr, Priestley's experiment with a sprig of mint and carbonic acid 1 In Dr. Priestley's experiment, what change did the mint produce on the carbonic acid 1 When a plant Is exposed to the sun in a vessel of water, whence comes the carbonic acid which it decomposes? What two facts prove that plants emit oxygen in consequence of the decomposition ofcarbonlcacid ? VEGETABLE CHEMISTRY. 35^ water, under ordinary circumstances, always contains a quan- tity of atmospheric air, and the xitmosphere always contains a proportion of carbonic acid, and hence it may be inferred, that the water furnishes the air which the plant decomposes in this experiment ; that this is the case, is proved directly by making the experiment with water, deprived of its air by tiie air-pump, or by boiling", when not a particle of oxygen is obtained. That -it is the carbonic acid which the plant decomposes, and . from which the oxygen is derived, is proved by two &cts. The first is, that vegetables are foimd not to emit oxygen, unless carbonic acid be present. The other is, that if the plant be confined in a mixture of carbonic acid and oxygen, the quanti- ties of which are known, the proportion of" oxygen will be in- creased, while that of the acid will be diminished. From these facts we arrive at the wonderful conclusion, that plants absorb carbonic acid fi-om the atmosphere, and that they retain the carbon for their own nourishment, but return the oxygen to purify the air. And from all that is known, it is most probable that a great proportion, if not all the carbon which wood contains, is derived from tiie atmosphere in this manner. 607. Plants absorb oxygen. — On the contrary, during the night, or when the light of the sun is withdi-awn, plants absorb oxygen, and form with it carbonic acid, a part of which they emit, and a part is retained. It appeal's from experiment, that vegetables not only cease to thrive, but that they actually die, if deprived of this nightly in- spiration of oxygen. Thus, if a plant be confined during the day in a portion of carbonic acid, it decomposes a part of this gas, which is replaced by the emission of an equal volume of oxygen. But at night a part of this oxygen is absorbed and convei-ted into carbonic acid, which is again enfitted. Thus, ultimately, the plant decomposes all the carbonic acid, because it emits more oxygen dming the day than it absorbs during the night. But if the oxygen which is formed during the day is withdrawn at evening, that is, if the plant has a new supply of pure carbonic acid eveiy day, it soon droops, and dies for the want of its oxygen. 608. The leaves of plants absorb water. — The leaves of plants absorb water, as well as carbonic acid and oxygen. When plants decompose carbonic acid, what becomes of the carbon ? From wlmt source is it piobable that plants derive most of their carbon 1 When do plants ab- sorb oxygen-from the atmosphere ? « 358 VEGETABLE CHEMISTRY. The great effect whioli the dew of nigM, or sprinMing with water, has on a drooping flower, is a proof that the leaves im- bibe moisture. Experiments also prove, that detached leaves often live for weeks, when swimming on the water, and that a plant which is" dying for want of moisture at the root, will revive and grow, when a branch "with its leaves is placed in a vessef of water." It is most probable, therefore, that during dry seasons, and when there is a defect of moisture at the root, that the plant is in part sustained by the absorption of water from the air, and particularly from the dew as it fells at night. 609. Plants incline toward the light. — In addition to heat, moisture, oxygen,- and carbonic acid, healthy vegetation requires a certain quantity of light. It is well known that plants which grow in the dark are always nearly colorless, and that they appear weak and unhealthy. The disposition of plants to enjoy the light is expressed by their inclination toward it, when it is stronger in one direction than in another. Thus, bean, or potato vines growing in a dark cellar, will al- ways run toward the light, and if possible will creep out into the open air. And flowers, growing in pots placed near a win^ dow, will always lean toward the light, so that to keep them in a vertical position, the~ pots must often be turned. In thick forests, the trees grcfw tail for the same reasoii; they stretch upward to enjoy the light and heat of the sun. Plants which grow in the dark contain more water, and less carbon, than those which grow in the sun. A plant which grew in the dark, on analysis of one of its branches, was found to contain only one ninetieth part of carbon; but on allowing the same plant to stand for 'thirty days in the ^un, it was found to contain one twenty-fourth part of carbon. This is readily accounted for, by the fact, that plants grow- ing in the dark, emit no oxygen, but give out carbonic acid, and hence the defect of carbonaceous matter which they con- tain. This also accounts for the circumstance, that when a healthy .plant is placed in the dark, it not only ceases to form carbon, but actually loses a part of that which it before con- tained, by the constant emission of carbonic acid. How is it shown that plants droop and die, when deprived of oxygen ? How is it shown that the teaVes ol plants absorb water 1 What aj;ent does healthy vegetation require in addition to heat, oxygen, water, and carbonic acid ? How do plants show their disposition to enjoy the liglit ! Why do the trees in thick forests grow tall 1 What IS the difrerence iii composition between plants growing in the dark, and in Ihe light t How is the small quantity of carbon contained in ulaats growing in the dark accounted for? AQKICTTLTCRAL CHEUISTRT. 359 CHAPTER XXVII. AGSICULTtmAI CHEMISTRY. 610. Observation. — The analysis of soils, in order to de- tect what is considered injurious to any particular crop, and to remedy the defect by adding such ingredients as are wanting for general or peculiar cultivation, has of late years become so common, that the present state of science, in tbis respect, calls for at least" a chapter on this subject, to the exclusion of less important matter. We, therefore, abridge the following from Liebig's Agricultural Chemistry, the most recent and important work on this subject. 611. Chemical elements or a soil. — ^The fertility of a soil is much influenced by its physical properties, such as its porosity, color, attraction for moisture, or state of disintegra- tion. But independently of these conditions, the fertility de- pends upon the chemical constituents of which the soil is composed. Experiment has shown that the alkalies, earths, and phos- phates, which constitute the ashes of plants, are indispensable for their vigorous growth. '612. Salts and acids. — ^Plants require certain salts for their gi'owth, the acids of which salts often exist in the soil, or are generated from nutriment derived from the atmosphere. If such materials do not exist within reach of the plants, their growth will be feeble, and the whole vegetation nearly or quite ' These salts do not, however, occur simultaneously in all plants ; thus, in saline plants, soda is the only alkali found ; in wheat and rye, lime and potash are constituents ; and in other plants, magnesia and potash exist. 613. Acids. — The acids vary m a similar manner. Thus one species may contain phosphoric acid, in the form of phos- phate of lime ; another, phosphate of magnesia ; a third, an al- kali combined with silicic acid ; and a fourth, an alkali in com- bination with a vegetable acid. 614. Wheat. — ^The most important and extensively cul- tivated crop in this country is wheat. This is best cultivated in a soil containing a good proportion of silicate of potash. That is, a soU consisting of sand, formed of quartz, feldspar, and mica, portions of which disintegrate by the action of the 360 AGRIOULTUBAL CHKMISTET. weatliey, together with a mixture of decomposed vegetation. On such a soil, large fields of wheat may be produced every year for an indefinite time. As a manure for such soils, when required, it is said that wood ashes are among the best, since they contain both phosphate of lime and silicate of potash. The silicate of potash, formed of silicic acid and potash, is a salt found in small quantities in plants, and also in many soils, in both of which it is detected by chemical analysis. The phosphate of lime is found in animal remains, especially in bones, of which they are chiefly composed. 615. Sulphur in plants. — Most culinary vegetables con- tain sulphur in greater or less proportions. What are called by botanists cruciferoiLS plants, as cabbage, mustard, and tur- nip, contain notable quantities of this element. Hence, as plants are found to thrive best on the materials of which they are at least, in part, composed, so it is a matter of experience, that all cruciform -Kfigetables thrive best in soils containing sul- phur, Gypsum, (which is sulphate of lime,) shavings of wood, refuse wool, or old woolen clothes, torn in pieces and decayed, each form excellent manure for all plants of the cruciferous family, as they all contain sulphur. 616. Potash and tobacco. — A most striking proof of the influence of potash upon vegetation, has been furnished by the investigations oiih^''^ Administration" on the subject of tobacco, in Paris. For many years, accurate chemical tests of the ashes of various sorts of tobacco, have been executed by order of the a,bove-named authority, and it has been found as the result, that the value of the tobacco stands in a certain relation to the quan- tity of potash contained in the ashes. By this means, the soils on which the several kinds of tobacco grew, could be distin- guished ; and it was further ascertained that certain kinds of American tobacco had their value increased, or diminished, in proportion to the potash they contained. Hence it would ap- pear that wood ashes, as a manure, gives value to the tobacco crop. 617. Indian corn. — ^There are certain plants, says Liebig, which contain either no potash; or a mere trace of it. Such are the poppy and Indian corn, {Zea mays.) For such plants, the potash in the soil is of no use. 618. Analysis of different soils. — ^Liebig has given the analysis of a great variety of soils, in different parts of the world, chiefly, however, in the several departments of Germany, and in Hungary and Bohemia. In North America, he has AGRICULTURAL CHEMISTBT. 361 &vored us ■with only two examples, hoth in Ohio, and of course in fertile regions, but in what parts he does not define. Th^ are as follows : NORTH AMERICA. 619. Surface soil of alluvial land in Ohio, remarkable for its fertility. 100 parts consisted of Silica and.silicious sand, 79.538 Alumina, 7.306 Iron, peroxide and protoxide o^ .... 6.824 Preside of manganese, 1.320 Lime, 0.619* Magnesia, 1.024 Potash, with silica, 0.200 Soda, • ■ • *'-°2* Phosphoric acid, lime, and oxide of iron, ' . 1.776 Sulphuric acid and lime, ....... 0.122 Chlorine, . ■ 0.036 Humus, soluble in alkalies, 1.950 Nitrogenous organic matter, 0.236 Wax and resinous matter, 0.025 100.000 Surface and subsoil in the vicinity of the Ohio river. This soil was also distinguished for its great fertility. The surfece soil is marked A and the subsoil B. A. B. Silica, with silicious sand, fine, . 87.143 94.261 Alumina, 5.666 1.376 Peroxide and protoxide of iron, . 2.220 2:336 Peroxide of manganese, . . . 0.360 1.200 lime, 0.564 0.243 Magnesia, . 0.312 0.310 Potash, with silica, 0.120 0.240 Soda, 0.125 Phosphoric acid, 0.060 a trace. Sulphuric acid, 0.027 0.034 Chlorine, 0.036 a trace. Humus, soluble in alkalies, . . 1.034 Humus, 1-072 Carbonate of lime, 0.080 Nitrogenous, organic matter, . 1-011 100.000 100.000 51 362 AGRICULTURAL CHEMISTRY. 620. Humus. — This substance, mentioned in the above analy- sis, Liebig defines to consist of woody fiber in a state of decay. It is, therefore, carbon and water. The property of woody fiber is, by uniting with the oxygen of the atmosphere, to convert it into an equal portion of car- bonic acid gas. This gas, it is well known, is the most im- portant food for young pl&nts, and hence it is, that vegetation is so r^id and vigorous among old decaying wood. The leaves of plants absorb this acid from the atrnosphere, and by the aid of light, heat, and moisture, they convert it into their own substance, the carbon becoming solid, while the oxy- gen remains to purify the air. Huiius does not nouiish plants by being absorbed into their substance, but by furnishing" carbonic acid, as above stated, which is hot only taken up by their leaves, but by their roots also. 621. How CHARCOAL OPERATES. — Charcoal is not subject to decomposition by time,' heat, and moisture, but remains for ages under all such influences combined, without the least change. Pieces of this substance have been found in the cata- combs of Egypt, where they had remained unchanged for thousands of years. It therefore does not furnish, by decompo- sition, any nutriment to plants, and yet there is no doubt -but charcoal is a good stimulant to vegetation. This is explained on the principle of its great absorbing powers for the gases, and particidarly carbonic acid, which gas, as above stated, is con- verted into wood by growing plants. 622. Experiment. — If charcoal, in a vessel containing the roots of a plant, be placed where it can not absorb carbonic acid, it will droop and expire, in the same manner and time that it would if placed in a vacuum. This is a proof that plants gi-owing in charcoal, are supported entirely by its ab- sorbing powers. 623. No MATURITY IN CHARCOAL. — Although plants will grow in charcoal, yet they never attain maturity, and ripen their seeds, without some additional nutriment, such as water containing some salt, as potash, or the liquid manure, from de- caying vegetables. What IB said of salts and acids for the growth of plants 1 What soil is best for wlieati What plants contain sulplirl What is the best manure for tobacco I What IS said of potash as a manure fo» Indian corn 1 What is humus J How does charcoal onerate to sunnnrt. vpufitnfinn 1 - ■ " -— ..».j»^ w> £.u.HU.. US .. UJ.LUU1 C l\tX II charcoal operate to support vegetation t ANALYSIS OF VEGETABLES. 363 CHAPTER XXVIII. Alf ALTSIS OP YEGETABLES. 624. We know, as already stated at page 352, that lihe chief elements of vegetables are carbon, oxygen, and hydrogen ; but that we may take the simplest case to illustrate the means of detecting these elements, we will suppose the subject of analy- sis consist only of carbon and hydrogen. In this case it is ob- vious that their entire combustion in oxygen gas, would afford nothing but carbonic acid and water. Now let us see how we shall come at the proportions of these. The quantity of car- bonic acid being determined, either .by weight or measure, the proportion of carbon could be inferred; and this ascertained and compared with the original weight of the substance to be analyzed, would give the proportion of hydrogen. Thus, sup- pose that 7 grains of the sutetance under analy^, yielded by combustion in oxygen, 22 grains of carbonic acid, then we should know that the quantity of cai-bon present was 6 grains, or 1 proportion of carbon united to 2 propoilions of oxygen, 16 grains =22 grains of carbonic acid. The 1 grain of hydrogen of course combined with oxygen to form water, and as these unite in the proportions of 1 and 8, there would result 9 grains of water. Suppose, in another instance, the weight of the compound to be anaJyzed was 15 grains, and that it was composed of hydro- gen, oxygen, and carbon, as a piece of wood ; and that on suj>- jecting it to heat with oxide of copper, we obtained 22 grains of carbonic acid, and 9 grains of water, then the result would be by inference, that the wood contained carbon, 6, hydrogen, 1, and oxygen, 8 ==15, because, there being 9 grains of water, we infer by the law of definite proportions, hydrogen, 1, oxy- gen, 8=9, and there being 22 grains of carbonic acid, this, by the same law, is composed of carbon, 6, and oxygen, 16=22. Now, since there was only 15 grains of the wood, we infer that 1 proportion of the oxygen was derived from the wood, and 1 proportion from the oxide of copper. The substance to be analyzed must first be reduced to pow- der, if capable, if not into small pieces, and mixed witii about 100 times its weight of oxide of copper, then the mixture is to be dried in the vacuum of an air-pump, wherein is also a small 364 ANALYSIS OF VEGETABLES. vessel of sulphuric acid. The substance for analysis is first heated to about 212 degrees, or higher if it will bear it, and in this state set under the receiver, before containing the acid, and^hen the air exhausted. The acid by its affinity to water, abstracts, all the moisture still retained by the substance in the dish. The mixture to ^^- ^°^- be analyzed being thus 'prepared, it is introduced into the tube of green glass, a, Fig. 106, which is open at Analysis of regetailes. the large end, and drawn out into a fine point at the other, to which is attached the small glass globe, c, communicating with the pipe, d, which contains chloiide of calcium. From the tube, d, there passes a crooked tube, leading under the bell-glass, /, which stands in the mercury bath, g. The orifice of the "tube, a, being closed by a piece of clay or otherwise, the tube is heated very gradually by burning charcoal, the screen, b, according to the directions of Prof. Mitscherlich, being necessary "for the purpose of pre- venting the heat from spreading too rapidly, lest the glass should become fused." By means of the heat, the carbon and hydrogen of the sub- stance to be analyzed, unite with the oxygen given out by the oxide of copper, so tliat a complete combustion goes on within the tube, and water and carbonic acid are composed. The water collects in the globe, c, and if any vapor passes, it is ab- sorbed by the chloride of potash in the tube, d. That part of the apparatus being carefully weighed both before and after the process, the excess of weight must be due to the water. The carbonic acid passes along and escapes into the bell-glass, -_/5 within which is the small glass globe, e, filled with moist caus- tic potash, into which the carbonic acid is, directed, where it is ■instantly absorbed by the potash, and thus the additional weight of the globe and' its contents will indicate the amount of car- bonic acid generated during the process. Both the water and acid formed during the analysis, can be detei-mined in the man- ner already pointed out, through the aid of definite proportion. If any nitrogen is evolved during the process, this will be re- tained under the bell-glass, and its quantity estimated. It will not be absorbed by the potash which takes up the carbonic KECAPITULATION. 365 acid. Or, perhaps, wliere the elements are complicated, one experiment had better be made for the nitrogen alone. REOAPlTnLATldtt. 1. Vegetable substances are chiefly composed of ca/rbon, hydrogen, and oxygen,' but sometimes contain portions of nitrogen. 2. During the process of germination, the farinaceous sub- stance of the seed becomes sweet, and affords nourishment to the young plant. 3. Healthy germination does not proceed without the com- bined presence of heat, water, and oxygen. 4. Seeds will not germinate in a vacuum, or in any gas which does not contain oxygen, though heat and moisture be present. 5. Plants receive nourishment from the air, as well as from the earth. 6. Plants nourished by pure water, and having access to the air, grow for a time, but do not produce seeds. 7. The nourishment which plants receive by the roots, is probably in a state of solution in water. 8. The sap undergoes a change in the leaves, where it parts with a portion of water, and is thus fitted to form the various ■ substances found in vegetables. 9. In the day time, plants absorb carboiiic acid, retain the carbon, and emit the oxygen. 10. In the night theiy absorb oxygen, and give out carbonic acid. 11. Plants do not live unless they are permitted to absorb oxygen during the night ; nor will they live unless they absorb a portion of carbonic acid during the day. 1 2. Vegetation will continue for some time in either carbonic acid, or oxygen gas ; because when confined in carbonic acid, plants emit a quantity of oxygen during the day, which they absorb at night ; and when confined in oxygen, they give out a quantity of carbonic acid at night, which l^ain serves them durirfg the day. 13. Healthy vegetation absolutdy requires the agency of light. 14. Plants which grow in the dark are white. They show The student should be able to answer all the questions involved in this recapitulation. 31* 366 VINEGAR. their propensity to enjoy the light, by leaning, or creeping to- ward it. 15. Plants growing in the dark, do not absorb, and decom- pose, but emit carbonic acid, and hence they contain a deficiency of carbon. V.YV-'.x.itvlt i^tA-J.^ CIAPTER XXIX. TEGETABLE ACIDS. 625. The vegetable acids are generally less liable to sponta- neous Secomposition than other vegetable products. They form salts when combined with the salifiable bases. Most of them are decomposed by hot nitric acid, being converted into carbonic acid and water. All of them suficr decomposition when exposed to a red heat. These acids are numerous, but a» large proportion of them are of little consequence, and there- fore we shall describe only the most useful. ACETIC ACID, 50. 4 eq. Carbon, 24. 3 eq. Oxygen, 24. 2 eq. Hydrogen, 2. VINEGAR. 626. The acetic acid, or vinegar, exists ready formed, in the sap of some plants, either in a free state, or combined with Ume, or potash. It may be formed artificially either by the acetous fermentation, or by the destructive distillation of wood. In the first case, it is made by exposing wine, cider, beer, or any other Uquid capable of passing through the acetic fermen- tation, to the action of the air. This last condition is absolutely requisite, for no liquid will form vinegar if prevented from the access of air, that is, from the presence of oxygen. The liquid must also be exposed to certain degrees of temperatm-e, for the acetic fermentation does not proceed when the thermometer is at 32 degrees, sM but very slowly when it is near this point. In this process, little or no gas is evolved, but on the contrary the oxygen of the atmosphere is absorbed, so that the liquid undergoes a slow oxidation. what is said of the tendency of vegetable acids to decomiiosition'? How may the vegetable acids be deconii)osea 7 What is the composition of acetic acid! What is the common name of acetic acid ? Is vinegar ever found ready formed in plantsi How may this acid be formed by art 1 What liquids form this acid by fermentatioa i VERDIGRIS. 367 The vinegar obtained by the distillation of wood is called pyroUgneoiis acid, that is, the acid of bumed wood. When first made, it is, very impure, and of a dark color, holding in solution carbon, soot, tai-, creosote volatile oil, which gives it a strong smell of smoke. It is purified by a second distillation, and is largely employed for manufacturing purposes, and par- ticularly in the preparation of white lead. The acetic acid is distinguished fi'om aJl other acids by its peculiar flavor, odor, and volatility. Its salts are called acetates. These salts are all of them decomposed at a red heat, or by the action of sulphuric acid. ACETATE OF LEAD, 162. 1 eq. A. Acid, 50+1 eq. Oxide Lead, 112. SnCAR OF LEAD. 627. This salt is prepared by dissolving either litharge, or white lead, in distilled vinegar. The solution is sweet to the tgste, and hence its common name. It occurs in small shining crystals, which contain 27 parts, or 3 atoms of water. .This salt is partially decomposed when abandoned to the action of the atmosphere. It parts with its water of crystallization, and absorbs carbonic acid from the atmosphereJ;hus being changed into a carbonate, or into white lead. We have stated in another place, that in the manufacture of white lead, the same change is effected ; the lead being first dissolved by the acetic acid, and afterward changed, into a carbonate by the action of the atmosphere. The acetate of lead is largely employed in the process of coloring, and as a sedative and astringent in surgery. ACETATE OF COPPER, 130. 1 eq. Acetic Acid, 50+1 eq. Oxide of Copper, 80. VERDIGRIS. 628. Thik salt may be prepared by exposing metallic copper to the vapor of vinegar. The process appears to consist in the what conditions are necessary to the production of vinegar by fermentation 7 Wiiat gas is absorbed from ttie air by the forming vinegar 1 What is the vinegar from distilied water called 1 How is the acetic acid distinguished from ail other acids ? What is the composition of acetate of lead 1 What is the common name for acetate of lead? How i& this salt prepared? lo what manner is this salt decom- posed when exposed to the air. ana what new salt is formed % What are the uses of acetate of lead 7 What is the composition of acetate of copper? What is the com- mon name of this salt ? By wliat chemical process is this salt formed? How is ver- digris made in the large way ? 36S ACID UY SORKEL. absorption of oxygen from the atmosphere by the metal, aftej ■which it is dissolved in the acetic acid. Verdigris is manufactured largely in the south of France, by placing plates of copper between the refuse of grapes after the juice is preyed out, foir the making of wine. The fluids which the grapes still contain, pass through the acetic fermentation, by exposure to the atmosphere, and after several weeks, the plates acquire a coat of the acetate, which being scraped off, they are again exposed to the same process. The acetate is afterward pui'ified by solution, and crystallization. OXALIC ACID, 36. 2 cq. Carbon, 12 + 3 eq. Oxygen, 24. ACID OF SOKKEL. 629. The oxalic acid exists ready formed in several plants, and particularly in the oxalis acetosella, or wood sorrel, and also in common sorrel. It is readily prepared artificially^ by digest- ing white sugar 'in five or six times its weight of nitric acid, and evaporating the solution to the consistence of syrup. On cooling, crystals of oxalic acid will be deposited ; but they should be purified by solution in water, and again crystallized by evaporation. Oxalic acid crystallizes in slender, flat prisms, which have an exceedingly sour taste, and which in solution combine with the salifiable bases, and form a class of salts called oxalates. These crystals contain half their weight of water of crystallization. This acid is easily distinguished from all others, by the form of its crystals, and by its solution, giving, with lime water, a white precipitate, which is not dissolved by adding in excess the same acid." Oxalic acid is one of the most prompt and fatal poisons known, when taken in large doses. Fatal acci- dents have many times happened, in consequence of mistaking this acid for Epsom salts. This acid is employed by calico printers, for the pui-pose of discharging certain colors. It is also used in families, for taking out spots of iron mould, and other stains. The oxalates are none of them of much importance. The oxalates of potash, like the acid itself, is sold under the name of essential salt of lemons, for removing stains from linen. What IS the oxalic acid composed of 1 In what plants iijthis acid ready formed 1 How IS this acid formed by art 1 What are the salts called, which Ihe salifiable ba-^es form with oxalic acidl How is this acid distinsuished from others! What is sairt ofits poisonous effects 1 What are the uses of oxalic acid 1 TARTAR EMETIC. 369 TARTARIC ACID, 66 4 eq. Carbon, 24-1-5 eq. Oxygen, 40 -|- 2 eq. Hydrogen, 2. tARTARIC ACIP. 630. Cream of tartar is the ■pnri&ad lees, or deposits of wino casks. From cream of tartar the tartaric acid is produced, by mixing the former with chalk in fine powder, and throwing the mixture into boiling water, by which the cream of tartar, which is a tartrate of potash, is decomposed, and a tai-trate of lime is formed. The tartrate of lime is then washed, and decomposed by. dilute sulphuric acid, which, combining with the lime, sets the tartaric acid at liberty, where it remains in solution. This solution being evaporated, the tartaric acid is obtained in white crystals. This acid is employed by calico printers, to discharge false prints, and by tallow chandleTs, to whiten their goods. It is also jised, when dissolved in a large quantity of water, as a cooling beverage in the hot season. When mixed with car- bonate "of soda in solution, it forms the effervescing draught called soda powder, of which large quantities are prepared and sold during the summer season. , The effervescMice, the only property which makes this drink agreeable, is occasioned by the union of the tartaric acid with the soda, in consequence of which the carbonic acid is liberated, and in escaping through the water, causes the eflfervescence. This acid is remarkable for its power of combining with two bases at the same time, and forming double salts. The' most important of these salts is well known under the name of tartar emetic. TARTRATE OF ANTIMONY AND POTASH, 354. 2 eq. Tartaric Acid, 132+2 eq. Protoxide of Antimony, ISff. 1 eq. Potash, 48+2 eq. Water, 18, TARTAR EMETIC. 631. This compound, so singular from the number of con- stituents it contains, is made by boiling the oxide of antimony called crocus metallorum, with tartrate of potash, or cream of tartar. What is the tartaric acid'composed of? What is the substance from which tartaric acid is obtained 1 By what process is this acid obtained 1 What are the uses of tar- tiiric acid 1 What occasions the effervescence of soda powders? What is the chem- ical name of tartar emetic T What is the composition of tartar emetic 1 How is tar- tar emetic prepart d J 370 SALT OF LEMOXS. This salt crystallizes in transparent prisms, which afterward grow white and opaque by exposure to the air. It is soluble in about fifteen parts of cold, and three parts of hot water. When dissolved in water, the ^solution gradually undergoes spontaneous decomposition, and becomes inert as a medicine. This may be prevented by the addition of about one-third part alcohol to the aqueous solution. This salt is also decomposed by many reagents, as by all the stronger acids, and several of the alkalies and alkaline earths, and even by vegetable sub- stances. Infusion of nutgalls causes with it a whitish precipi- tate, which is considered a compound of tannin and oxide of antimbny. This compound is inert, and hence the decoction of chincona bark, as it contains tannin, has been given as an antidote to an over dose of tartar emetic. CITRIC ACID, 58. 4 eq. Carbon, 24-f-4 eq. Oxygen, 32-(-2 eq. Hydrogen, 2. SALT OF LEMONS. 632. This acid is obtained from the juice of lemons, by the same process as that described for tartaric acid. Finely pow- dered chalk is added to the juice, as long as ^ny effervescence ensues. The citrate of lime thus fom^ied, is insoluble in water, and sinks to the bottom of the vessel. This being washed, is digested in dilute sulphuric acid, by which an insoluble sul- phate of lime is formed, while the citric acid, being thus set at hberty, remains in the solution, and on evaporation is obtained in crystals. These crystals are large, transparent, and beautiful. They undergo no change by exposure to the air, are exceedingly sour to the taste, but when dissolved in a large proportion of water, make an agreeable drink, in consequence of retaining the flavor of the lemon. This acid forms salts with the salifiable bases, but none of them are of importance. There is a variety of other vegetable acids, most of which are of no importance in any respect. Some of them have been analyzed, while the composition of others are unknown. We may, however, conclude, by analogy, that they are aU composed of oxygen, carbon, and hydrogen, in different proportions. Wliat is said pf the decomposition of aqueous solution of tartar emetic ? How may tiiis decomposition be prevented! Explain tlie principle on which chincona, or FeruTiaiL baric, has been given as an antidote to tartar emetic. GUMS. 371 GHAPIER XXX. INGKEDIENTS OF PLANTS. 633. The ingredients of plants are distinct substances, formed by their secreting organs, and separable from each other with- out destructive distillation. They are separated by certain sol- vents, which have the power of dissolving some, but not others. Thus, water dissolves the gum but not the resin, while alcohol takes up the resin and leaves the gum; The solvents einployed for these purposes are hot and cold water, ether,^cohol, and some of the acids. The following are lite principal ingredients, or what are called the proximate principles of plants, viz. : Gum, Tannin, Resins, Sugar, Coloring matter, Narcotine, Starch, Wax, Bitumen, Gluten, Fix«d oil. Vegetable alkalies. Exti'active, ^ Volatile oil, Vegetable acids. Lignum, Camphor, « We shall examine the propea^es of only the most important of these principles. 634. Gum-arabic may be taken as an example of pure gum. It dissolves in water, with which it forms a viscid solution, or mudlage, from which it may be obtained in its original state, by spontaneous evaporation. It is insoluble in alcohol, or ether, the former precipitating it from the watery solution in the form of white flakes. Gimi is decomposed by sulphuric, and nitric acids. By -the former, it is resolved into water, acetous acid, and charcoal ; the latter produces with it oxalic and malic acid. When gum is submitted to destructive distillation, it affords water, carbonic acid, carbureted hydrogen, empyreumatic oil, and acetic acid. Wbat is citric acid composed o* I What is the common name otthis acid t How , is citric acid obtained? Wtlat ip tlie use of citric acid 2 What are the Ingredients of p^tsl How are the ingredie.its of plants separated from each' other? Wllat are ttiTprincipal ingredients, or proximate gxinciples of plants? In what liquid is gum soluble. Into what substances is gum resolved by sulphuric acid ? What are tba products of gum, when submitted to destructive distillation ? 372 635. Sugar is chiefly obtained from tlie sugar-cane, a plant which grows in hot climates, and which yield it in a larger pro- portion than any other substance^ It is also procured from the sugai>maple, by boiling down the sap which flows from incisions made in the tree ; and from several roots, particularly the beet, from which large quantities are made in France. In the manufacture of sugar from the cane, the first process consists in obtaining the juice, which is done by grinding and pressure. This is then evaporated by a gentle heat, during which a quantity of lime is added, partly for the purpose of neutralizing any free acid, and "partly for the purpose of separ- ating extractive matter, which unites with the lime, and forms a scum on the surface of the liquid. The evaporation is con- tinued until it acquires the consistency of syrup, when it is transferred into wooden coolers, where a portion concretes into a crystalline mass, and in this state idtvas what is called musco- vado or raw sugar. It is then placed in vessels with apertures in the bottom, where the more fluid parts drain oflF, and form the well known sweet syrup, molasses. 636. Refined sugar. — ^Raw sugar is refined by the follow- ing process : The sugar being dissolved in water, is mixed with the whitdB of eggs, or the serum of blood, and boiled. The al- bumen or serum is thus coagulated by the heat, and -rising to the surface, brings with it such impurities as the sugar con- tained*, which are removed by a skimmer. When the syrup is judged to be sufficiently clear, it is placed in smaller pans, and further concentrated by boiling, and then transferred into Cool- ers, where it is agitated with wooden oara, until it appears thick and granulated. It now becomes white, and the crystals being broken by the agitation, facilitates the draining oflf of the colored matter which remains. It is next placed in conical cups of earthenware, of the well known form called sugar-loaf. These having apertures at the bottom, a portion of molasses drains off, leaving the sugar much whiter than before. Lastly, a quantity of pipe clay is mixed with water to the consistency of cream, and poured on the loaves to the thickness of an inch. The water from this slowly What are the principal vegetables from which sugar is obtained 7 What is the process by which sugar is extracted from sugarcaiel Why is lime added to the juice of the cane when boiling 1 What is muscovado sujar J How is molasai'S ob- tainertl How ia raw sugar refined 7 What is the use of the albumen and seruniused in this process 1 How is the suj-it (luriflod and whitened after it is placed inbie conical cups ? ILUTKN. 373 -percolates through the (^ ^ . b, and washes all remains of the coloring matter from the i .-^ iir. The loaves are then dried by heat, and put in papers for sale. Refined sugar undergoes no change when exposed to the air, the dampness of ray sugar being caused- by impurities. Sugar is decomposed by the sulphuric and nitric acids. By analysis it is resolved into the usual constituents of vegetables, oxygen, carbon, and hydrogen.. 637. Starch is an abundant principle in the vegetable king- dom, being one of the chief ingredients in most sorts of gi-ain, and in many roots and seeds. The process for obtaining starch consists in diffusing the powdered grain or rasped root in pure cold water, by which the water is rendered white and turbid. After some hours, the grosser parts, which in wheat consists chiefly of gluten, are separated by straining, and the water which passes through, being placed in shallow vessels, deposits the starch, on standing. It is afterward washed and dried with a gentle heat. If stardi be boiled for a considerable time in water contain- ing about a twelfth of its weight of sulphuric acid, it is con- verted into sugar. By careful analysis, it has been found that the only difference between the composition of starch and sugar, is, that the_staroh contains less hydrogen and oxygen, in ' proportion to the 'carbon, than sugar. How the acid acts to convert the starch, into sugar, has not been satisfactorily ex- plained. During the germination of geeds, a similar change is effected, the starch being in part converted into sugar. The principal varieties of starch, are arrow-root, potato starch, sago, tepioca, cassava, salop, and the starch of wheat. 638. Gluten may be obtained from wheat flour, by forming it into a paste, with cold water, and continuing to wash the paste under the stream of the same fluid, as long as any thing is carried away. The starch beil5g thus removed, a tough elastic substance, of a gray color, will remain, which is gluten. What is said of tlie abundance of starch in the vegetable kingdom 1 What is the process for obtaining starch ? How may starch be converted into sugar l What is- the.difference between the composition of starch and sugar 1 What are the principal varieties of starch 1 How may gluten be obtained? What is the appearance of gluten ? What are some of the properties of gluten-? Wiiy is wheat flour said to te more nourishtDg than tiiat of other grain ? 32 314, COLORING MATTER. This substance has no'taste^ and is insoluble in water, aloo- hol, or ether, but is soluble in alkalies and acids. If left to un- dergo the putrefactive fel-mentation, it emits an offensive odor, similar to animal substances, and- from this circumstance it is apparent that it contains nitrogen, which indeed is proved by- its yielding ammonia at a red heat. Of air substances, wheat contains the greatest proportion of gluten, and it is owing to this circumstance, that wheat flour IS more nourishing than that of other grain, gluten beings the most nutritive of all vegetable substances. It is also owing to the presence of this substance in the flour, that the dough is tenacious, and the bread spongy, or light, the carbonic acid formed during the fermentation of the dough, being detained by the gluten, in consequence of which the whole mass is dis- tended with bubbles of air. Wheat contains from 18 to 24 per cent, of gluten, the re- mainder being principally starch. EXTRACTIVE MATTER. 639. Most vegetables, when infiised for a time in hot water, impart to it a brOwn color. When such solutions are evapo- rated, there remains a solid substance, of a bifownish, or some- times of a yellowish color, which is extractive matter. Extracts are prepared by apothecaries, as a means of concen- ti'ating the virtues of plants for medicinal puiyoses. These ex- tracts not only contain the proper extractive matter, but several foreign substances also, such as resin, coloring matter, oil, &o. COLORING MATTER. 640. The coloring matter of vegetables is chiefly red, Uue, green, yellow, or mixtures of these colors. Nearly all vegetable colors are discharged by the continued aotjon of light, and without exception, they are all destroyed Tjy tts action of chlorine. , . Acids and alkalies either destroy^ or change the tints of vegetable colors. < The extraction of the coloriiig principles, and the transfer of them' to different substances, constitutes the art of dyeing, an In what manner does the gluten in the dough produce the sponginess of the bread % What is extractive matter 1 What are the principal tints of the coloring matter of vegretables 1 What elFect does light have on the coloring principle" of vegetables 1 What are the effects of chlorine on these colors 1 What constitutes the art of dye- ing ? How are colors divided 1 What are substantive colors ? TANNIN. 375 art which, in the succession of ages, has been carried to a high degree of perfection. This art has been practiced from the remotest antiquity; for the history of man informs us, that from the Mng on the throne, to the savage in the wilderness, all have ever been fond of decorating themselves in a variety of colors. Colors have been divided into substantive and adjective. Substantive colors are such as do not require the intervention of any other substance to fix them pennanently, their attraction for the cloth being sufficient for this purpose. Adjective colors require the intervention of some substance, which has an affinity both for the coloring matter, and the stuff to be dyed. This intervening substance is called a mordant. The mordant generally consists of a metallic salt dissolved in water, with which the cloth is impregnated, after which it is passed through the solution cif coloring matter. The mordants most commonly employed are, muriate of tin, sulphate of iron, acetate of iron, and sulphate ofalumine. Different mordants are used for different colors, and different kinds of cloth. Thus, Mack is made with sulphate of iron, nut- galls, and logwood. Yellow, with alum, fustic, and safiron; red, of cochineal, madder, red wipod, or archil, with muriate of tin, or sulphate of alumine for a mordant. Blue is made with indigo, &c. TANNIN. 641. Tannin is the substance, by the absorption of which the skins of animals are converted into leather. Jhis substance is contained abundantiy in nutgalls, in the bark of many trees, particularly the oak, hemlock, and birch, and in most vegetable substances which are astringent to the taste. Tannin may be obtained from any of these substances, by first bruising the article, and tiien digesting it in a small quan- tity of cold water, and afterward evaporating the water. This substance is of a yellowish brown color, extremely astringent to the taste, and soluble in water and diluted alcohol. Tannin is distinguished by its affording an insoluble precipi- tate with isinglass, or any other animal jelly. It is on this principle that the art of tanning leather is founded. The hides are laid in vats, and between them there is thrown a layer of What are adjective colors 1 What are mordaDts in coloring ? What are (he prin cipal substances used as mordants'? What is tannin! What are the principal snh- Btanccs which contain tannin 1 How may tannin be obtained ? How is tannin dra- tingnished 1 On what principle is the tanning of leather founded 1 376 VEGETABLE OILS. of oat, or other bark, which contains tannin, in coarse powder. The tannin of the bark is first dissolved by the water, and after- ward combines with the leather, by which it is rendered hard, and nearly impervious to water. CHAPTER XXXI. VEGETABLE OILS. 642. The vegetable oils are of two kinds, Fixed and Volatile. 643. Fixed oils. — These are found only in the seeds of plants, and chiefly in such as have two cotyledons, such as almonds, linseed, walnuts, and rape-seed. The oil of olives, however, is extracted from the pulp which surrounds the kernel. The fixed oils are obtained by crushing or bruising the seed, and subsequent pressure. Itey are viscid, nearly insipid,~ and inodorous, and generally cong^l at a temperature considerably higher than 32 degrees. The fixed oils, with a few exceptions, undergo little other change, by exposure to the air, man that of growing more viscid, and acquiring a degree of rancidity. The latter change is owing to the absorption of oxygen, for rancid Oils redden Vegetable blues, showing that they contain a quantity of free afcid. The absorption of oxygen, by some of the fixed oils, and par- ticularly by those of Jinseed and rape-seed, is sometimes so abundant and" rapid, as to set fire to light porous substances on which they are spread. These are called cases of spontaneous combustion, and in many instances, where these oils have been suflfered, either by accident or otherwise, to come in contact with cotton Wool or cotton cloth, destructive fires have been the consequence. The alkalies combine with the fixed oils, and foi-m soap. The composition of all these oils is, carbon, hydrogen, and oxygen. What are the two kinds of vegetable oils? In what part of plants are the fixed oils found 1 How are the fixed oils obtained 1 What changes do these oils undergo by exposure to the air ? What causes oils to become rauci^ 1 In what manner do these oils flometimes produce spontaneous combustion ? VJEGJETABLE OILS. 377 644. Volatile oils. — Plants and flowers owe their odor and flavor to volatile or essential oils. These oils are obtained by distilling the plants which contain them with water. The water prevents the pi ants 'from being burned. Both pass into the receiver from the stilly where the oil is found either at the bottom, or oa the surface; as its density is greater or less than that of water. Some fruits, however,' yield essential oil by pres- sure ; such are the orange, the lemon, and the bergamot, which contain it in vesicles in the rind of the finit. The odor of the essential oils is aromatic, and their taste pene- trating. They consist of the odoriferous principle, by which plants are distinguished from each other in a concentrated state. These oils are soluble in alcohol, and very sparingly so in water. When dissolved in the former, they constitute esserKes, a great variety of whicb are manufactured, particularly in Paris, and sold as perfiimes in most parts of the world. All tile volatile oils, when pure, pass away by evaporation. Hence, a good test of the purity of these oils is to let a drop fall on paper, and if any oily spot is left, after warming the paper, the essential oil has been adulterated by some fixed oil. The essential oils burn with a clear, white light, and the only products -of their combustion is water and carbonic acid. Hence, these oils are composed solely of carbon and hydrogen, the water and carbonic acid being formed by the absorption of oxygen to support the combustion. On exposure to the atmosphere, they absorb oxygen, and in consequence become thick, and turn of a yellowish color. They are at length converted into solids resembling resins. Some of them during this process deposit crystals, when exposed to the agency of light. VoiatUe oils do not unite readily with metallic oxides, and even with alkalies, no combination is readily effected. .They dissolve sulphur in large quantities, forming the well known article called balsam of sulphur. The following list contains the principal essential oils, with their colors and specific gravities- annexed. Turpentine. Lemons, Anise, . Juniper, Cbamoniile, Caraway, Colcr. Specific giaritj. CkilorlesB 0.870 Pale yellow, 0.850 " « 0.985 Greenish yellow, . . . 0.91 1 Deep bine, 0.940 Pale yellow, ..... 0.940 32' 378 BCKNINO FLUIDS. Oil^ of * Color. Specific gravity. Lavender, Yellow, 0.870 Peppermint, .... Greenish yellow, . . . 0.920 Rosemary, Colorless, ...... 0.895 Camphor, White, 0.988 . Mint, Greenish, 0.975 Cipnamon, .... Yellow, ...... 1.035 Cloves, Pale yellow, 1.061 Sassafras, Red, or yellow, .... 1.094 Mustard, .- '. . . . Yellow, ' 1.038 Bitter Almonds, . . . Colorless, , 1.043 In tlie above table, water, as formerly explained, is estimated at 1000. Most of these oils, it will be seen, are lighter than water, while a few, "as oil of cloves, are heavier than that fluid. It is hardly necessary jto describe the properties of these oils separately, as they are all in many respects qiijte similar. ' The odors of many of them are well known, and their tastes familiar to most persons who indulge in the use of candy. There are, however, a few of them which differ greatly from the rest of the class, and particularly in the power of refracting light. BURNINQ FLUIDS. 645. The numerous accidents which have occurred in conse- quence of ignorance, or carelessness in the . use of what are tnown imder the name of "burning fluids" make it proper that some notice should be taken of these compounds in this epitome of chemistry. There is some variety in the proportions of these compounds, but they all consist, essentially, of oil of turpentine and alcohol. Alcohol is composed chiefly of hydrogen, and when pure, burns with a pale bluish light, so entirely unfit for illumination, that a flame of the ordinary size of that of a lamp, will not show the hour "by a watch at the distance of six iilches. It burns with- out smoke, and hence is used as a spirit lamp. The oil of tur- pentine, (when pure, it is called camphene,) on the contrary, is composed chiefly of carbon, and bums with a white light, well fitted for illumination, but does not readily consume its own smoke, and hence deposits lamp black. The alcohol, therefore, requires the turpentine to give' it the power of illumination, and the turpentine requires the alcohol to make it bum freely, and without smoke. When the two are mixed the compound burns freely, without smoke, and with a most agreeable white light, well fitted for illumination. B0RNISG FLUIDS. 379 This compound, as a hand light, has several advantages over oil ; it burns with very simple apparatus, merely a tube and cotton wick ; it requires no snuffing, and never smokes ; and, perhaps, a stiU greater advantage is, that when spilled it does not soil the carpet, or dress ; and, lastly, its light is much more briUiant than that produced by oil. But, on the contrary, while oil is always safe, the hundreds of accidents, and the num- ber of agonizing deaths every year, caused by the burning fluid, are sufficient to show that ite general use must always be at- tended with more or less hazard. 646. Explosive effects. — Common hydrogen, or the car- bureted hydrogen, caHed Jtre-damp, or that used for gas-lights, will burn silently, or without explosion, when pure, but when either is mixed with oxygen, or atmospheric air, and fired, a violent detonation is the consequence. The same happens with respect to the vapor of burning fluid, which consists of hydro- gen, or carbureted hydrogen; it never explodes unless mixed with oxygen, of which, however, the atmosphere contains a sufficient quantity for this purpose. When, therefore, the burn- ing fluid in a lamp is nearly or quite exhausted, the space is filled with gaseous vapor, or fire-damj), which is instantly mixed with a portion of oxygen from the atmosphere, when the cover is removed : and now, the vessel is filled with an explosive mix- ture, which, if a blaze be brought near, wUl, of course, produce the efiects of gunpowder, with more or less force, depending on the quantity, or perfection of the mixture. The trutii of these principles is illustrated by the frequent practice of attempting to replenish the lamp while it is burning. The cover is removed, the fluid poured in, which drives out the inflammable gas, and this, being lighter than the atmosphere, reaches the flame,4and the whole instantly detonates, breaking th#lamp, if of glass, and if of rnetal, throwing the fluid, which it sets on fire, in every direction. But there is no need of supposing an explosive mixture, in order to produce the sad consequences which so often result from accidentally fiiiiig the burning fluid. If the mouth of the vessel is small, and the gas is set on fire within it, all the bad eftects of an explosion will follow from the expansion df the contents by the heat, the vessel being broken, and the fluid set on fire and thrown in all directions. 647. Remedies. — ^To avoid the horrid results of these explo- sions, of which almost every weekly paper contains more or less cases, it is only required that persons having the charge of 380 RESINS. burning fluid, or camphene lights, should observe the following rules: 1. Fill the lamps in the morning. 2. If a lamp requires to be filled in the evening, produce another light, and setting it at least two feet distant, put the caps on that to be filled, then remove the cover, and pom- in the fluid. 3. See that there is no air-hole through the cover, by which the vapor within the lamp can gain admission to the flame. 4. See that the wicks fill the tubes so that the flame can not descend, in case the vapor by cold or otherwise^ should be condensed. 5. Employ metallic lamps, furnished with wire gauze, on the principle of Daty's safety-lamp. 6. Understand that the wire gauze is no protector, if the glass lamp is broken while it is burning. 7. Never trust children, or careless persons, with the .use of the burning fluid at any rate. 8. If you sell burning fluid, never draw it in the night, either for your customers or yourself. 648. Eemark. — It is pretended that some compounds of this sort are not explosive, certain venders, or inventors, assuring the public, on their reputation for honesty, that their Amds can not be inadeto explode, and hence are perfectly safe. Now so far as this is true, the public ought certainly to thank such inven- tors, but it is believed that he who will make his own experi- ments on this subject, will find little or no difierence in the ex- plosive disposition, of these compounds. If they will bum, their vapors wUl explode when mixed with air. RESINS. 649. The resins are peculiar substances which exude irom certain trees, or plants, or are contained iti their juices. They commonly contain a portion of the essential oil of the plant. They are solid at common temperatures, and, when rubbed, show signs of electrical excitement. Their colors are yellow, reddish, and white, and most of them are translucent, or transparent. The resins are soluble in alcohol, ether, and the essential oils, but are precipitated by water, in which they are entirely in- soluble. They are dissolved, and at the same time decomposed, * What are the resins 1 la what liquid are the resins soluble 1 FERMENTATION. 381 by the sulphuric add, with evolution of sulphuric acid gas, and the deposition of charcoal. The principal resins are, common resin, gum copal, lac, mas- tic, elemi, and dragon's blood. Common resin, called rosin, is ■what remains after the distillation of spirit of turpentine. The turpentine itself is obtained by makiDg incisions in the fir tree, from which it exudes. This consists of resin, and the oil of tur- pentine, which are separated by distillation. The usei of many of the resins' are well known. Sealing- wax is made of lac, turpentine, and common resin. Copal and elemi, "when dissolved in spirit of turpentine, or alcohol, form varnishes. CHAPTEK XXXII. PERMENTAHON. 650. Fermentation consists in a spontaneous exercise of chemical aflolnity, in a vegetable substance, or solution, in con- sequence of which its properties are materially or totally changed. There are several Mnds of fermentation, the names of which indicate the pruducts formed. These are, the saccharine, the vinous, the acetic, and the putrefactive. The product of the first is sugar ; that of the second, wine ; that of the third, vinegar ; while the fourth results in the total decomposition of all vegetable matter, and the destruction of every usefiil product. 651. Saccharine fermentation. — The germination of seeds, and the malting of barley, are instances of the saccharine fermentation, the farinaceous being converted into saccharine matter, or sugar. 652. Vinous fermentation. — ^This, by the generality of mankind, is considered the most important of all fermentations, since, from the days of Noah and Alexajider, to the present time, its product has been employed, either to heighten tiie pleasures, or as an antidote to the cares of this poor life. Why are the resins precipitated by water? What arc the names of the principal resiDs? In -what manner IS common resin, or rosin, obtained ? What are the uses of some of the principal resins 1 What is fermentation 1 What are the different kinds of fermentation 1 What is the product of the saccharine fermentation 1 Wliat is the product of the vinous ? 382 FERMENTATION. Wine, as well as other intoxicating liquors, are produced only by tbe vinous fermentation ; a process by which alcohol is formed. There are four conditions necessary to the success of this process. These are, the presence of water, sugar, and yeast, in mixture, and a temperature between 60 and 70 de- grees. Or, instead of yeast and sugar, saccharine matter, and starch, or the sweet juices of fruits. These conditions, being united, there succeeds a brisk intestine motion, attended with the escape of carbonic acid gas in abundance, and 9t the same time the transparency of the fluid is diminished by the. rising of opaque filaments, the whole being attended with an elevation of temperature. "When these phenomena cease, the liquor is found to have lost its sweet, mucilaginous taste, and to have ac- quired some degree of acidity', with a brisk, penetrating flavor, and, the power of producing intoxication. ■ 653. Chemical Changes in fermentation. — In respect to the chemical changes which take place during this process, it is found that after the fermentation, the sugar has entirely dis- appeared, and that it is replaced by a quantity of alcohol, none of which existed in the liquid before the process. Hence, sugar is converted into alcohol by the vinous fermentation. But the weight of the alcohol is never et[ual to the weight of sugar em- ployed, by nearly one-half. This loss is accounted for by the escape of the carbon and oxygen of the sugar, in the form of carbonic' acid. Wheii the process is conducted in such a rnan- ner that the quantity of carbonic acid can be retained and weighed, it is found to correspond precisely with the loss of the alcohol ; that is, the combined weight of the acid and alcohol are equal to that of the sugar. This may be made apparent thus : Sugar and alcohol are composed of Sugar. Alcohol. 3 eq. of carbon, 18 2 eq. carbon, 12 3 " " hydrogen, 3 3" hydroge^i, 3 , 3 " " oxygen, 2i 1 " oxygen, 8 45 23 This shows a loss of one proportion of carbon and two pro- portions of oxygen from the sugar, the alcohol containing only two parts of carbon and one of oxygen, while the sugar con- What is the prortact of the acetic 1 What are the results of the putrefactive fer- mentation 1 What changes do seeds and barley undergo by germination and malt- ing? What are the four condirions necessary to induce the vinous fermentation? What gaa escapes during this fermentation 1 ALCOHOL. 383 tained three of carbon and three of oxygen, the proportion of hydrogen being the same in both. The difference between the number for sugar and that for alcohol is, therefore, 22. Now, we have seen, that carbonic acid is composed of one proportion, or atom, of carbon, 6, and two proportions, or atoms, of oxygen, 16, and these two numbers make the precise quantity of car- bon and oxygen lost by the sugar, and which is not contained in the alcohol. Therefore, 45 parts of sugar produce, by fer- mentation, 23 parts of alcohol, which is found in the fermented liquor, and 22 parts of carbonic acid gas, which escape. This investigation, while it affords a beautiful illustration of the doctrine of definite proportions, demonstrates that notibing is lost by a new arrangement, or interchange of elements. It is believed,, that the vinous fermentation never takes place without the presence of sugar, the elements of this ingredient, as shown above, fiirnishing by decomposition those of the alco- hol. In. cases where substances which contain no sugar are known to produce alcohol without the addition of this ingre- dient, the process is explained by the supposition that the starch which these substances contain, is converted into sugar by the saccharine fermentation. It is well known that potatoes, which contain little or no sugar, yield a large quantity of alcohol by fermentation. But potatoes contain a large proportion of starch, which entirely disappears during the process, being first con- verted into sugar, and then into alcohol. 654. When a liquor which has passed , through the vinous fermentation is distilled, there rises from it a fluid, having much more highly intoxicating powers than the fermented liquor from which it is obtained. This liquorTias a sharp, penetrating taste, and retains the flavor and odor of the fermented liquor from which it is distilled. The fluid so obtained is alcohol mixed with water, and containing a portion of the essential oil peculiar to the vegetable which formed the fermentative solu- tion, and which gives it a flavor. Thusj brandy, rum, and whiskey, have each a flavor of their own, wliich arises from this circumstance. These are called spirituous liqiiors. What becomes of the sugar during the vinous fermentation 1 Is the weight of alco- hol formed, equal to the weight of sugar employed 1 What .becomes.of the deficiency 1 What is the composition of sugar 7 What is the composition of alcohoH How does it appear that the loss from the sugar escapes in the form ofjjwrbonic acid ? Does the vinous fermentation ever take place without the presence ofsugarl 384 WINE. When a spirituous liquor is distilled, the alcohol is obtained in a state of much greater purity, the oil which it contained and most of the water being left in the retort, or stiU. In this state it is colorless, highly inflammable, produces cold by evap- oration, and occasions a considerable augmentation of tempera- ture by admixture with water. Common alcohol contains a portion of water, and has a spe- cific gravity of froni 850 to 875, water being 1000. It may be further purified, or fi-eed from water, by adding to it warm car- bonate of potash, or muriate of lime, which combines with the water, and sinks to the bottom of the vessel, after which the alcohol may be poured off, Very pure alcohol may also be procured, by putting, it into a bladder, which being suspended in a warm place, th« water will slowly pass through the coats, while the pure alcohol is retained. The strongest alcohol which canbe procured feyeither of these methods, has a specific gravity of 800, or 796, at the temperature ol 60 degrees. Pure alcohol has never been frozen, though exposed to the lowest temperature which art has ever produced. It is a pow- erful solvent, being capable of dissolving camphor, resins, soap, volatile oUs, sugar, bafaaan, Atropa belladonna. Bi-uela, Stiyclmos nux vomica. Cinchonia, Cineliona.]ancifoIia. Codeia, Opium. Conia, . Caninm maoulatmn. CoryOalia, Corydalis tuberosa. Cynapia ^thusa cynapium. DatDra, Datm-a stramonium. Delphia, Delphinium staphisagria. Bigitalia, . . . Digitalis purpurea. Bmetia, Cephaelis ipecacuanlia. Hyoficyamia, Hyosoyamus niger. Meeoniaj- ......... Opium. Morphia, Opium. Nareotina, Opium. Niootinaj . ^ Nicotiana tohacum. Fi habitants. That fish, frogs, and other animals of this kind, can not sustain life without oxygen gas, is proved by the fact^ that they die in a short time, if the water in which they are placed is covered with a film of oil, so that no-oxygen is admitted. Frogs, though capable of suspending their respu'ation for a long time, die in less than an hour, if the small quantity of water in which they are confined is covered with oil. Aquatic insects and worms exhibit the same phenomena when treated in the same manner. In these cases, experiment has shown that oxy- gen is converted into carbonic aa tube of the capacity of one cubic inch, divided into 100 equal parts, and accurately fitted, by grinding, to lie neck of 408 AjJALTSis ,oi; MIXED gases. the bottle. -The tube, full of gas, is fixed into the bottle pre- viously filled -with lime water, and its contents ai'e brisMy agitated. The stopper is tben withdrawn under water, when a ■portion of liquid rushes into the tube, supplying the place of the gas which has disappeared; and the process. is afterward repeated, as long as any absorption ensues. 695. The eudionaeter of Dr. Hope was originally designed for ansdyzing air or other similar .mixtures, &e bottle being filled with a solution of the hydro-sulphuret of .potassa, or lime, or some hquid capable of absorbing oxygen. To the employmem of this apparatus it has been objected, that the absorption is rendered -slow by the partial vacuum which is continually taking place within it, an inconvenience particu- larly felt toward the close of the process, in conseqixence of the eudiometric liquor being diluted by the admission of watei'. To remedy this defect, Dr. Henry has substituted a bottle of elastic gum for that of glass, by which contrivance no vacuum can occur. From the improved method of analyzing air, how- ever, this instrument is now rarely employed in eudiometiy ; but it may be used with advantage for absorbing carbonic acid pf similar gases, and is particularly useful for the purpose of demonstration. 696. Mode qf analyzing mixtures or HrniiOGBN and OTHEH inflammable GASES.— When hydrogen is mixed with nitrogen, air, or other similar gaseous mixtures, its, quantity is easily ascertained by causing it to combine with -oxygen, either by means of platinum sponge, or the electric spark. If, instead of hydrogen, any other combustible substance, such as car- bonic oxide, light carbureted hydrogen, or olefiant gas, is mixed with nitrogen, 4Jie analysis is easily effeeted by adding a sufficient quantity of oxygen, and detonating the mixture by electricity. The diminution in volume indicates the quantity of hydrogen contained in the gas, and from the .carbonic acid, which may then be removed by an alkaU, the quantity of car- bon is inferred. When olefiant gas is mixed with other inflammable gases, its quantity is easily determined by an elegant and simple process proposed by Dr. Henry. It consists in mixing 100. jcneasures, or any convenient quantity of the gaseous mixture, with an equal volume of chlorine, m a vessel covered with a piece of cloth, or paper, so as to protect it from light ; and after an in- terval 0^ about ten minutes, the excess of chlorine is remaved by lime water, or potassa. The loss experienced by the gas to ANAtTBIS OF MINERALS. 409 be analyzed, indicates the exact quantity of defiant gas wMoh it had ss is owing to the escape of carbonic acid, the quality of this gas may be determined by a compara- tive analysis. Into a small flask, containing mmiatic aeid, diluted with two or three parts of water, a known quantity of marble is gradually added, the flask being inclined to one %ide in order to prevent the fluid from being flung out of the vessel during the efiervescence. The diminution in weight experienced by the flask and its contents, indicates the quantity of carbonic acid which has been, expelled. ShouH the carbonate suflFer a greater loss in the Aire than when decomposed by an acid, it- will most probably be found to contain water. This may be ascertained by heating a piece of it to redness, in a glass tube, the sides of which will be bedewed with moisture, if water is present. Its quantity may be determined by causing the watery vapor to pass through a weighed tube filled with fragments of the chloride of calcium, (muriate of lime,) lay which the moistufe is absorbed. 699. Separation of lime and magnesia. — Tlie more common kinds of carbonate of lims frequently contain traces of siKcious and aluminous earths, in consequence of whioh,''they are not completely dissolved in dilute muriatic acid. A very frequent source of impurity is the carbonate of magnesia, which is often present in such quantity that it forms a pecu- liar compound called magnesian limestone. The analysis of this substance, so far as respects carbonic acid, is the same as that of marble. The separation of the two earths niay be conveniently efiected in the following manner : The solution of the mineral in muriatic acid is evaporated to perfect dry- ness, in a flat dish, or caipsule of porcelain, and after rcdis- solving the residuum, in a moderate quantity of distilled water, a solution of the oxalate of ammonia is added as long as a precipitate ensues. The oxalate of lime is then allowed to subside, collected on a filter, converted into quicklime by a white heat, and weighed ; or the oxalate may be decomposed by a red heat, the carbonate resolved into the sulphate of lime by sulphuric acid, and the excess of acid expelled by a temperatm-e of ignition! To the filtered liquid ^Bntaining the magnesia, an excess of cdrbonate of ammonia, and then phos- phate of soda is added, when the magnesia, in the form of the ammoniaco-phosphate, is precipitated. Of this precipi- tate, heated to redness, 100 parts correspond to 40' of pure magnesia. {Murray.) 700. Earthy sulphates.— ITie most abundant of the earthy ANALYSIS OF MIKEEALS. 411 sulpliates, is that of lime. The analysis of this compound is easily effected. By boiling it for fifteen or twenty minutes with a solution of twice its weight of the carbonate of soda, double decomposition ensues; and the carbonate of lime, after being collected on a filter and washed with hot water, is either heated to low redness, to expel the water, and weighed, or at once reduced to quicklime by, a white heat. Of -the dry car- bonate, fifty parts correspond to twenty-eight of lime. The al- kaline solution is acidulated with muriatic acid, and the sul- phuric acid thrown down by the muriate of baryta. From the sulphate of this earth, collected and dried at a red heat, the quantity of acid may easily be estimated. The method of analyzing the sulphates of strontia and baryta is somewhat different. As these salts are difficult of decomposition in the moist way, the following process is adopted : The sulphate, in fine powder, is mixed with three times its weight of the carbonate of soda, and the mixture is heated to redness in a platina crucible, for the space of half an hour. The ignited mass is then digested in hot water, and th* insoluble earthy carbonate collected on a filter. The other parts of the process are the same as the foregoing. 701. Mode of analyzing compounds of silica, alumina, AND iron. — Minerals, thus, constituted, are decomposed by an alkaline carbonate, potash, or soda, at a red heat, in the same manner as the sulphate of baryta. The mixture is afterward digested in dilate muriatic acid, by which means all the in- gredients of the mineral, if the decomposition is complete, are dissolved. The solution is next evaporated to dryness, the heat being carefully regulated toward the close of the pro- cess, in order to prevent any of the chloride of iron, the vola- tility of which is considerable, ffom being dissipated in vapor. By this operation, the sOica, though previously held in solution by the acid, is entirely deprived of its solubility ; so that on digesting the dry mass in water, acidulated with muriatic acid, the alumina and iron are taken up, and the silica is left in a state of purity. The siliceous earth, after subsiding, is col- lected on a filter, carefully edulcorated, heated to redness, and weighed. _ ; To the clear liquid amt^ing iron and' alumina, a con- siderable excess of a solution of pure potassa is added;, so as not only to throw down these oxides, but to dissolve the alumina. The peroxide of iron is then collected on a filter, edulcoratetl carefully until the washings cease to have an alka- 412 AXALTSIS OF MINERALS. line reaction, and is well dried on a sand bath. Of tbU hydrated peroxide, forty-nine parts contain forty of the anhy- droa* peroxide of iron. But the most accurate mode of deter- mining its quantify is by expelling the water by a red heat. This operation, however, should be done with care ; since any adhering particles of paper, or other combustible matter, would bring the iron into the state of black oxide, a change which Ls known to have occurred by the iron being attracted by a magnet. To procure the alumina, the liquid in which it is dissolved is boiled with sal-ammoniac, when the muriatic acid unites with the potassa, the volatile alkali is dissipated in vapor, and the alununa subsides. As soon as the solution is thus rendered neutral, the hydrous alumina is collected on a filter, /iried by exposure to a white heat, and quickly weighed after removal from the fire. 702. Sepabatiok of bson and manganese. — A compound of these metals, or their T)xide, may be dissolved in muriatic acid. If the iron is in a large proportion, compared with the manganese, the following process may be adopted with advan- tage : To the cold solution, considerably diluted with water, and acidulated with muriatic add, carbonate of soda is gradu- ally added, and the liquid is briskly stirred with a glass rod, during the effervescence, in order that it may become highly charged with carbonic acid. By neutraliang the solution in this manner, it at length attains a point at which the per- oxide of iron is entirely deposited, leaving the liquid colorless ; while the manganese, by aid of the free carbonic acid, is kept in solution. The iron, after subsiding, is collected on a filter, and its quantity determined in the usual manner. The filtered liquid is then boiled with an excess of the carbonate of soda ; and the precipitated carbonate of manganese is collected, heated to low redness in an open crucible, by which it is con- verted into the brown oxide, and weighed. This method is one of some delicacy ; but in skillful hands, it affords a very accurate result. It may also be employed for separating iron from magnesia and lime as well as from manganic. 103. Br SUCCINATE OF ammonia. — But if the proportion of iron is small, compared with that of manganese, the best mode of separating it is by the succinate of ammonia or soda, prepared by neutralizing a solution of succine acid with either of those alkalies. That this process should succeed, it is neces- sary that the iron be wholly in the state of peroxide, that the ANALYSIS OF MINERALS. 413 solution be exactly neutral, whicli may easily be insured by the cautious use of ammonia, and that the reddish-brown colored succinate of irgn be washed with cold wat«r. Of this succinate, weir dried at a temperature of 212 degrees F., 90 parts corre- spond to 40 of the peroxide. From the filtered liquid, the manganese may be precipitated at a boiling temperature by carbonate of soda, and its quantity determined in the way above mentioned. The benzoate may be substituted for the succinate of ammonia in the preceding process. It may be stated- as a general rule, that whenever it is in- tended to precipitate iron hy means of the alkalies, the succin- ates, or benzoates, it is essential that this metal be in the maxi- mum of oxidation. It is easily brought into this state by digestion with a little nitiic acid. 704. Separation of manganese from lime and maone- siA.-r^If the quantity of the former be proportionally small, it is precipitated as a sulphuret by the hydrosulphuret of am- monia or pot'assa.- This sulphuret is then dissolved in muriatic acid, and the manganese thrown down as usual by means of an alkaK. But if the manganese be the chief ingredient, the best method is to precipitate it at once, together with the two earths, by a fixed alkaline carbonate, at a boiling temperature. The precipitate, after being exposed to a low red heat and weighed, is put into cold water, acidulated with a drop or two of nitric acid, when the lime and magnesia will be slowly dissolved with effervescence. Should a trace of the manganese be like- wise taken up, it may easily be thrown down by the hydrosul- phuret of ammonia. 705. Mode of analtzing an earthy mineral contain- ing SILICA, IRON, alumina, MANGANESE, LIME, AND MAGNESIA. — ^The mineral, reduced to a fine powder, is i^ited with three or four times its weight of the carbonate of potassa or soda, the mass is taken up in dilute muriatic acid, and the silica separated in the way already described. To the solution, thus freed from silica and duly acidulated, carbonate of soda is gradually added, so as to charge the liquid with carbonic acid, as in the analysis of iron and* manganese. In this manner the iron and alumina are alone precipitated, substances. which may be separated from each other by means of pure potassa. The manganese, lim6, and magnesia, may be determined by the processes already described. 706. Analysis of minerals containing a fixed alkali. — When the object is to determine the quantity of a fixed 35* 414 AKALYSI3 OF MINEUALS. alkali, such as potassa or soda, it is necessary to abstain, from the emplojfinent of these reagents in the analysis itself;, and the banner will do well to devote his attention to the alkaline ingrecuents oiialy. On this supposition, he will proceed in the following manner : The minersu is reduced to a very fine pow- der, mixed intimately with six times its weight of the artificial carbonate of baryta, and exposed for an hour to a white heat. The ignited mass is dissolved in dilute muriatic~acad, and the solution evaporated to perfect dryness. The soluble parts are taken up in hot water ; an excess of the carbonate of ammonia is added; and the insoluble matters, consisting of silica, car- bonate of baryta, and all the constituents of the mineral, ex- cepting the fixed alkali, are collected on a filter. The dear solution is evaporated to dryness in a porcelain capsule, -and the dry mass is heated to recbiess in a crucible of platinum, in order to expel the salts of ammonia. The residue is the chlo- ride of potassium or sodium. In tius analysis, it generally happens that traces of manga- nese, and sometimes of iron, escape precipitation in the first part of the process ; and, in that case, th^ should be thrown down by the hydrosulphnret of ammonia. If neither lime nor mag- nesia is present, the alumina, iron, and manganese, may be separated by pure ammonia, and the baryta subsequently re- moved by die carbonate of that alkali. By this method the carbonate of baryta is recovered in a pure slate, and may be reserved for another analysis. The b^yta may also be thrown down, as a snlphate, by salphiuic acid, in which case, the soda or pota^a is piocnied in combination with that acid. The analysis is attended with considerable inconvenience, when magnesia happens to be present, because this earth is not completely prerapitated, rather by ammonia or its carbonate; and, therrfore, some <^^ -7-11^ '-:?■ -; /k- Page. Blende, ; 301 Blood, 396 circulation of, 398 Blow-pipe, common, 130 Gahn'a,, 130 compound, ...... 1 67 use of, 168 Blue, Prussian, ,..■., , . 242 Bodies, elementary, 122 number of, ..... 122 ponderable, 147 Imponderable, 11 Boiling of liquids, 21 Borates, 342 Borate of soda, 342 Borax...... 342 Boron, 212 Brass............... ...... 302 maUeable, , 302 Bromihe, 224 Bunsen's battery, 79 Burning fluid, 378 Cadmium, 303 Calamine,. 301 Calcium, "282 ■ ' oxideof,. 282 Calomel, 262 Caloric, 11 conductors of, 25, 26 combined, r. 13 equilibrium of, 12 expansion of, 29 free, 13 latent in steam, 14 specific, ■ 39, 42 reflection of, 34 sources of , 57 offlaidity, 14 capacity for, 40 Caloric, transmission o^ 37 Canton's pbosphtirus, ....... 61 Caoutchouc, 391 Camphene, . . . . 378 Cai-bon,.. 194 and oxygen, 198 sulphide of, 246 Carbonic acid, 198 absorption of, 201 poison, 198 oxide,.... 203 properties of, ..... . 199 preparation, 199 Carbonates, 343 of soda, 345 of potash, 344 ' of lead, 320 of lime, 283 Catalysis, 103 Calico printing, 374 Carbo-sulphurio acid, 246 darbm-eted hydrogen, ....... 228 , , ' ■ light,... 228 heavy, . . 235 Caustic, lunar, 336 Carburet of hydrogen, 235 Cerium, 312 Cistern, pneumatic, ... . , 167 Charcoal, manufacture of, 196 Chemical afiinity, 95 force of, 107 combinations, 104 apparatus, 128 equivalents, ;. 118 s^ale of, . 1^4 symbols, ........... 143 Chemistry, defined, 9 animal, 394 inorganic, ...... 149 organic, 350 Chlorates, 216, 337 424 Page. Chlorate of potash, 339 Chlorides, 333 Chloride of nitrogen, 220 calcium, 283 sodium, 277 lime, 289 sulphur, 218 Chlorine, 213 _ how prepared,. . 214, 285 supports combustion, 215 metals burn in it, . . . 215 oxides of, , . 219 and oxygen, ....... 220 and sulphur, ...... 220 and nitrogen, 220 and hydrogen, 216 Chloruret of sulphur, 218 Chloroform, 404 Chromium, 307 Chromate of lead, 307 iron, 307 Chrome yellow, 308 Cinchonia, 392 Cinnabar, 263 Classification of metals, ...... 123 Citric acid,. 370 Coal gas, 236 CobMt, 313 analyisis of,.... 313 oxides of, 313 arsenical, 313 Codeia, .'. ,. 391 Cohesion, 100 attraction of, 44 Cold, artificial, 53 Coloring matter, 374 of the blood, 396 art of, 374 Columbram 309 Colors, primary, 59 Combination, 104 F«ie. Combination by volume, - 1 15 Common salt, 277 Compound blow-pipe, 167 Combining numbers,. 122 Combined calorio, 13 Combustion, 57 what, 154 changes by, 156 in oxygen, , 155 of charcoal, 91 of hydrogen, 166 loss of weight by,. 57 of iron or steel, . . 155 spontaneous, .... 367 of zinc, 155 Conductors of caloric, ... 25, 26 Concave mirrors, 34 Consumption of oxygen, 182 Copper, 316 acetate of, 367 protoxide of,. 317 peroxide of, 318 sulphate of, 206, 332 sulphide of, 318 sulphuret of, 318 Copperas, .., 332 Corrosive sublimate, 262 Cotyledon, , . . 353 Cream of tartar, 369 Cryophorus, 24 Crucible, 127 Crassamentum, , 396 Crystallization,. 325 water of, 325 Cups, galvanic, 77, 84 Cyanogen 242 Cyanuret of mercury, 242 D. Decompo»tion, double, ...... 99 Detonating sugar, 339 INDEX. 425 P«ee. Dentoxide of hydrogen, ..... 172 lead, 319 Definite proportions, 148, 326 nnmbers, 326 Decrepitation, 326 Decomposition by hydrogen, . . 1 64 Derbyshire spar, 343 Density of air, 43,' 139 fluids...... .. 137 Didyminm, 322 Donarnim, ....;. 323 Double salts, 325 Destructive distillafaon, 364 Diamond, burning of, 195 Differential thermometer, 45 Dropping tube, 131 Diana's silver tree, 264 Dutch gold, 317 Dyeing, art of, 374 E. Earths, 290 metallic bases of, .... 292 properties of, 290 Ebullition, cause of, 19 Efflorescence, 324 ISasticity in affinity, ; 102 Elective affinity, 95 double, 97 Electricalpile, 75 Electricity, 64 conductors of, ... . 68 theory of, 67 magneto, .' 71 chemical, effects of, 69 Electro-chemical theory, 87 Electro-magnetism, 91 Elements, 122 electrical, 88 their number, 122 transfer of, . . . ^ . . . 82 35* Page. Einetia, 393 Emetic, tartar,. 369 Engine, 18 Epsom salt, 330 Equivalents, chemical, 118 how found, 120 Equivalent numbers, 122 table of, 122 scale of,.. 124 Erbium, 322 E^ential organs of plants, 352 oils 377 table of, 377 Ether, 383 evaporation of, 24 Etching on glass, 226 Endiometry, 188 Extractive matter, 374 Expansion by heat, 29 of solids, 29 of liquids, 32 of gases, ...;...;. 32 Evaporation, 22 freezing by, 24 Evaporating dish, 129 F. Fermentation, 381 chemical changes in, 382 — saccharine, 381 vinous, 381 Felling colliery........ 230 Fibrm,« 394 Fire-damp, 230 Fixed air -. 198 oils, 376 Florence flask, 129 Fricti 234 phosphate of, '. . 309 phosphuret of, 289 , carbonate of, . . ! 283 and chlorine, T. 284 sulphate of, ...;.. 329 Lime water, . . . ''. 330 Liijuids exjiand by heat, . , ^ . . 32 Litharge, .- 319 Lithium, ^ • • .- . 279 Looking-glasses, silvering, ... 260 Lunar caustic, ...'...,., 336 M. Magdeburg hemispheres, ... . 180 Magnetism, electro,. ........ 91 Magnet, temporary, 93 Magnesia, .". . . 295 Matrass, v 128 Marble, ai-tifieial, -. . . 282 Manganese, -. 150, 295 oxide of, 150,296" Matter, ooloriilft,. \ ■ . 374 extractive, ......... 374 Meconia, 391 Meltingpot, 127 Mereury, 258 penetrates othermetals, 260 peroxide of,. . . . . ." 261 sulphnret of,. . . , . . . .'. 263 subchloride of, 262 Metallic compounds, . ; 255 alloys, ; 255 oxides, 252 salts......... 255 Metals, ..; 123,249 arrangement of, 123 Page. Metals, classification of, ..... . 257 combustible, 253 combine with sulphur, 252 discpvery of, 249 become oxides, ...... 252 new, 321 general properties of, . 250 how reduced, ... 253 positi\ie electrics, . . . ..^51 q)eoific gravity of, . . . 256 Meteoric iron, 298 Mineral waters, analysis of, . . 415 Mirrors, concave, 34 Molybdio acid,. . — ;■. i 309 Molybdenum, . .^. 308 Mordant, .;.... 374 Morphia, »; ... ...".;... 391 Multiple proportions, ........ 115 Muriates, .T . .... ...... 217 Mui-iatic acid, 216 Musical tones, .162 Muriate of ammonia, .,....., 346 barytes,.'.. ...... 347 N. Narootine, 392 New metals, '. 321 Nickel, 314 Nicholson's balance, . . . < 136 Nitrates, 334 Nitrate" of ammonia, 185 potash, 334 silver, , 336 Nitric acid, : ; 190 anhydrous, 191 oxide, ......... ". 187 Niobium, 322 Niter,.. ......^... 334 Nitro-muriatio acid, ,'. 266 Nitrous acid, 187 oxide, * . . 185 429 P*ge. Nitrous oxide, effects of, 186 gas........... 197 Nitn^en, 172 how obtained, 173 catbnretof,... 241 cUoride of, i 220 binoxide of, 187 peroxide of, 189 and hydrogen, 192 jf^ and oxygen^. ...... 190 protoxide of, 185 Nomenclature, 140 O. Gil of turpentine, .• 377 OUgaa, .;. 234 Oil lof vitriol, 206 Oils, vegetable, ........' 376 fixed, 376 volatile,., 376 Olefiant gas, 235 Oleaginous substances, 395 Opium, 391 Oi^anic chemistry, 350 Organs of plants, 352 Orpiment, ." 307 Osmium, ...i. 271 Oxide, carbonic,, 203 Oxalates, 368 Oxides, metallic,. . . . 252, 324 Oxide of calcium,. , 283 Oxidation, 252 Oxygen gas, 149 emitted by plants, 63 consumption ot, .. 182 how obtained, .... 150 combustion in, . . , 155 affinity of, 153 source of, 183 Oxymuriatic acid, 213 P. Palladium 270 Peariash, ^6 Pelopium, „....,. 322 3,.... ...211,341 of soda, 341 Photometer, ............ 60, Ifrl Phosphorus,. . . . ". 208 preparation of, . . . 209 and oxygen,. .... 211 Homberg's, 61 Phosphites, 212 PiiosphorescCnoe, 61 Phospiiide of hydrogen, 240 PileofYolta, , 75 Pinchbeck,. 317 Plants, growth of, 354 food of, 356 < incline toward the sun, 358 in^edients of, 371 organs o^ 352 Plaster of Paris, 329 Platinum, 267 aUoysof, 268 action on hydrogen, . 1 62 malleable, 267 peroxide oJ, 270 protoxide of, 270 sponge,. 163 uses of, .,. .. 268 Pneumatic cistern,. 132 Plumbago, 300 Ponderable bodies, 147 Portable gas, 236 Potassa, 273 Potassium 273 protoxide of, 274 and oxygen^ 274 oxide of, 2t5 Potash, chlorate of, 339 carbonate of,.,. .... . 344 430 Page. Potash, hydriodate of, 222 sulphate of, '. 328 Pot, melting, 127 Fropoitioiis, definite, .... Ill, 148 indefinite, 109 by Toliune, ..... 115 imiltiple, 115 how found, 115 Prussian blue, 242 Prussio acid, .............. 242 deadly poison, . . . 244 Pyrites, '. .'. ^00 Pyrometer, 30 Q. Quicklime, 283 Quicksilver, 258 Quinia, 392 sulphate of, .' . 393 R. Realger, 306 Ked oxide of copper, 317 lead, 320 precipitate, 261 Kefiectors, 34 Resins, 380 Respiration, 397 Receiver, 128 Retort,'. 128 Rhodium, 371 Rust of iron, 299 Rutheriura, 323 S. Saccharine fermentation, .... 381 Salts of the hydraoids, 348 Safety-lamp, 232 Sal-aramonrae, , 346 Salifiable bases, 324 Salt, common, 277 p«e«. Salt of sorrel, 368 lemons,... 370 Salts, remarks on, 324 crystallization of, 325 nomenclature of, 324 number of, 325 Sap of plants, 355 Scale of equivalents, 124 for gravity, 135 Seeds, germifiation of, #<352 Serum, 396 Silica, ; 293 Siljcium, 293 Silver, 263 nitrate of,.,...... 263,336 solvent of, 263 , German,..., 314 -Silvering powder, j.., ... ... 264 ' ivoryj ......>.,.. . 264 looking-glasses, .... 260 Simple bodies, what, 123 number of, 122 Smalt; ..; 3l5 Soap, 345 Soda, 276 carbonate of, ......... . 345 muriate of, 277 phosphate of, ......... 341 borate of, 342 sulphate of, 328 Sodium, ... ; 276 prot03dde of, 276 chloride of, 1.... 277 Solar spectrum,,. 59, phosphor!, . ; 61 Solids expand by heat, 29 Solution of salts, ...,'... 326 Soils, elements of, y. S69 Sources of caloric, 57 Spar, Derbyshire, 343 heavy 329 INDEX. 431 ttge. Specific gravity, 134 how taken,. . . 135 of solids,.;.., 135 ofliqnids, 137 of gases, 139 table of,.. 136j 256 Spirituous liquors, : . . 383 Starch, 373 Steam', ; 17 . latent heat of,. .... . 14,. 17 engine, 18 Steel, combustion of, ....... . 155 Strontian, . . . 281 protoxide of, 281 Strychnia, 393 Sugar, 372 howma4e^ 372 beet,; .' 372 maple, .• 372 of lead,... 367 refined,., 372 Sulphates, 327 of copper, 206 of alumina, 330 of baryta, 329 ofKme,.... 329 of magnesia, 331 of iron, 332 ofpotjsh, 328 ofsoda, 328 of zinc, 333 Sulphur, 204 and hydrogen 206 and oxygen, ....... 304 oiilonu'etof,.. 218 chloride of, 218 Sulphuric ether,. 389 Sulphurous acid, 204 Sulphuric acid, 206 Sulphide of carbon, 248 Snlphureted hydrogen, 239 Synthesis, chemical 10, 167 Symbols, chemical, 143 table of, . . 143 Syphon, solid, 260 Table of equiv^ents, 122 metals, 123 elements, 88 essential oils, 377 specific caloric, 42 temperatures, ..,,,. 55 specific weights,' .... 136 Tannin, 375 Tantalum, i . 309 Tannic acid, 375 Tartar emetic, 369 cream of, 369 Tartaric acid 369 Tellm-ium, . , 316 Temperature, animal, 401 Temporal^ magnet, 93 Terbium, 322 Theory of atoms, 125 galvanism, 87 Thermometer, 44 air, 45 roistering, ... 48 construction of, . 46 difierential, ... 45 Fahrenheit's, . . 47 . Six's, 48 Thenno-electrical pile, 3S •En, 303 uses of, 304 oxides o^ 304 Titanium, 316 Tones, musical, 162 Transmission of heat, 37 Trough, galvanic, 78 Triple sails, 327 432 INDEX. en, 309 Tungstio aoid, ......... 309 Turpentime, oil of, 377 U. Uranium, 311 V. Vanadium, . ; 321 Vanadiates, 312 Vapori2ation, . ., 43 Van,Helmant's willow, 354 Vegetation, . . . ". 353 source of oxygen,. 183 Vegetable acids, 366 alkaloids, ,. 390 oils, 376 alkalies, 324 ctemistry, 352 yegelables, analysis of, , 363 ultimate principles of, 364 Verdigris, 317, 367 Veratria, , .- 393 . Verditer, 317 Vermilion, 263 Vinegar, . , 366 Vital action, 57 Vitriol, blue, 206 green, ..;'... 332 white, 333 oil of, ;.. 206 Volumes, theory of, 115 Volta's pile, , .;. 75 VolatUe oils, 376, 377 W. Water, 168 .analysis of, 176 analysis of mineral, ... 415 al^sorbed t^y plants, . . . 358 absorbs gases, 171 contains air, 171 deeompositfon bf^, . . 83, 170 properties of, 169 oxygenized, 172 expands by freezing, . . 1 70 boiling of, 21,28 synthesis of, 10, 167 weight of,... i.. 170 Wells, caution about, 157 White arsenic, 305 White vitriol, 333 T. Tttrja, 293 Z. Zinc, . . , 301 flowers of, 302 oxide of, 302 sulphate of, 333 ZsrfTree, '. 313 Zirconia, 293 Zero, 45