CORNELL UNIVERSITY LIBRARY CHEMISTRY RS 421.H7ri883'™"'''''-'''™^^ ^liniHMiiiiijiii?''®'""'^' ^"^'ysis as applied 3 1924 004 111 476 Cornell University Library The original of tiiis book is in tine Cornell University Library. There are no known copyright restrictions in the United States on the use of the text. http://www.archive.org/details/cu31924004111476 MANUAL CHEMICAL ANALYSIS AS APPLIED TO THE EXAMINATION OF MEDICINAIi CHEMICALS. A GUIDE FOR THE DETERMINATION OF THEIR IDENTITY AND QUALITY, AND FOR THE DETECTION OF IMPURITIES AND ADULTERATIONS. KOK THE USE OF PHARMACISTS, PHYSICIANS, DRUGGISTS, MANUFACTURING CHEMISTS, AND PHARMACEUTICAL AND MEDICAL STUDENTS. THIRD EDITION, T H O K O U G II I, Y K E V I S E D AND GREATLY ENLARGED. BY FREDERICK HOFFMAN"!^, A.M., Ph.D., PUIJLTC ANALYST TO THE STATE OP NEW YORK, ETC., FREDERICK By POWER, Ph.D., PROFESSOR OF ANALYTICAL CHEMISTRY IN THE PHILADELPHIA COLLEGE OF PHARMACY. PHILADELPHIA: ' HEE'RY C. LEA'S SON & CO. 1883. RNELL \ V UNIVERSITY I \ ^ Entered according to Act of Congress, in the year 1883, by HENRY C. LEA'S SON & CO., in tlie Office of tlie Librarian of Congress. All rights reserved. COLLIS S, PRINTER. PREFACE TO THE THIRD EDITION. The third edition of this work has been thoroughly revised and to a large extent re-written, in order to make it comply with the present compass of chemical knowledge, as also with the recently issued new editions of the Pharmacopceias of the United States of America and of the German Empire. The general and original plan and character of the work have been retained; the first part has been much enlarged, so as to afford an explicit and comprehensive guide and work of reference to both student and expert. All the articles of the second part have been carefully revised and greatly enlarged, many new ones added, as also the most approved methods for the sepa- ration, identification, and, in most cases, for the quantitative estimation of the chemical poisons likely to be met with in foren- sic research. As in former editions, the aim has been to render each article complete in text and illustrations, so as to avoid, as far as possible, references to other articles. The German, French, and Spanish names have been added, as also a large number of new illustra- tions of apparatus and forms of crystals. The senior author desires to express his obligations and thanks to his friend and associate Dr. Frederick B. Power, to whose ef&bient and able assistance all credit for the superiority of the present edition is due. New York, February, 1883. PREFACE TO THE FIRST AND SECOND EDITIONS. Although the preparation of most medicinal chemicals has passed away from the laboratory of the pharmacist, and is suc- cessfully conducted on a commercial scale in manufacturing estab- lishments, yet the responsibility for the identity and quality of medicines, and of the substances used in their preparation, rests properly and legally with those who prepare, compound, and dis- pense them. It is therefore the duty of the pharmacist and the dispensing practitioner of medicine, as also, to a considerable extent, of the druggist and the manufacturing chemist, to examine the medicinal chemicals of commerce as to their identity, quality, and purity. In the exercise of this duty, they have frequent occasion to resort for information to references now widely scat- tered through chemical, pharmaceutical, and medical manuals and journals; since our literature, although of vast and increasing extent, and crystallizing more and more into distinct branches, is still wanting in a special guide for ready reference in the applica- tion of chemical analysis to such examinations. In the present volume I have endeavored to supply this want, in a manner and to an extent which, it is hoped, will confine the work within the precise limits of requirement, without detracting from its general scope and its practical usefulness. Since chemical tests and examinations bear upon and involve the methods of systematic chemical analysis, and as these cannot be described in each particular instance, I have deemed it expe- dient to preface the volume with a few notes on operations and reagents, and on a few important general tests, and to present a VI PREFACE TO THE FIRST AND SECOND EDITIONS. brief outline of a simple course of qualitative analysis for the sys- tematic and progressive recognition of such substances as are met with in the medicinal chemicals. A brief guide has also been added for the volumetric estimation of those compounds to which this mode of examination is especially applicable. Upon these preliminaries is based the subsequent description of the physical and chemical properties and relations of the medici- nal chemicals and their preparations, and of the methods era- ployed for establishing their identity, and for ascertaining their quality and purity. It has been compiled with special reference to the recent editions of the Pharmacopoeias of the United States, of Great Britain, and of Germany, and has been brought within the briefest possible compass, with the view to furnish a concise and trustworthy guide, combining easy execution, simple appa- ratus, and economy of time, with the greatest attainable accuracy. In preparing this compendium, I have consulted, and at times made free use of, a number of standard works, and periodicals of the kindred literature. I have, however, felt compelled, not with- out hesitation, to omit the introduction of references, which would have required much space, and would have greatly increased the size of the volume, without afibrding a corresponding advantage. Though well aware of the shortcomings and imperfections of the work, I nevertheless venture to hope that it will meet with kind consideration, and will prove both serviceable and stimulat- ing in a province not yet duly appreciated or deservedly culti- vated. This hope is the stronger, as the work appears at a time when the rapid advance of both sciences and arts, the drift of public sentiment, and the consequently 'increasing obligations of the pharmaceutist and the physician, all tend toward higher quali- fications, and necessitate also, among other attainments, a more extended exercise of knowledge and skill in chemical and micro- scopical investigation. New Yokk, February, 1873. CONTEI^TS. PART FIRST. Opeeations .... Reagents ..... Keagisnts and Test Solutions CouiiSE or Qualitative Analysis Preliminary Examination Solution Examination for Bases Examination for Acids Table of the Deportment of the Compounds of the Principal Metals with some of the General Reagents VoLUMETEic Analysis . ' Analysis by Neutralization Estimation of Alkalies Estimation of Acids Analysis by Oxidation and Reduction Estimation of Sugars Analysis by Precipitation Alkaloids 17 2G 29 43 44 48 49 61 69 70 80 80 86 88 96 98 102 PART SECOND. MEDICIXAL CHEMICALS AND THEIR PEEPAEATIONS. Acetura . ..... Acidum Aceticum ..... " Arseniosum . . . . Detection of Arsenic in P'orensic Investigation Detection of Arsenic in Coloring-matters, Paper, and Fabrics 134 Benzoicum Boricum Carbolicum Chromicum Citricum Gallicum Hydriodicum 117 122 126 132 135 137 139 142 144 147 148 via CONTENTS. Acidum Hydrobromicum ' ' Hydrochloricum ' ' Hydrocyanicum Detection of Hydrocyanic Acid in Forensic Investiga ' ' Hypophosphoi'osum " Lacticum . " Nitricum " Oleicum " Oxalicum . ' ' Phosphoricum " Salicylicum ' ' Siiccinicum ' ' Sulphuricum " Sulphurosum " Tannicum . " Tartaricum ' ' Valerianicum Acouitina . jEther ^Ether Aceticus Alcohol Alcohol Amyliciim Aloinum Alumen Detection of Alum in Flour and Bread Aluminii Hydras " Sulphas Ammonii Benzoas ' ' Bromidum " Carbonas " Chloridum lodidum . " Nitras " Phosphas " Sulphas . ' ■ Valerianas Amyl Nitris Antimonii et Potassii Tartras " Oxidum " Sulphidum " " Aurantiacum Antimonium Sulphuratum . Apomorpliinffi Hydrochloras Aqua Ammoniae " Amygdala; Amara; . '■ Chlori " Destillata CONTENTS. IX Argenti Cyanidnm . ' ' lodidum ' ' Nitras ' ' Oxidum Ai-senii Bromidum . " lodidum Atropina Atropinse Sulphas Auri et Sodii Chloriduni Barii Chloridum Benzinum . Bismuthi Citras " et Ammonii Citras ' • Subcarbonas ' ' Subnitras ' ' Valerianas Bromum Brucina Cadmii lodidum " Sulphas Caff'eina Calcil Bromidum " Carbonas pra2cipitatus " Chloridum " Hypophosphis " lodidum " Phosphas prsecipitatus Calx Chlorata " Sulphurata Camphora monobromata Cantharidinum Carbonei Bisulphidum Cerii Oxalas Chinoidinum Chloral Chloralum Butylioum Chloroformum Chrysarobinum Cinchonidina Oinchonidina; Sulphas Cinchonina CinchoninsE Sulphas Codeina Colchicina . Coniina Creasotum . Cupri Acetas PAGE 256 257 258 2C1 262 263 263 265 266 268 269 270 272 273 276 277 279 ^82 284 285 286 287 289 290 292 293 294 296 299 300 300 301 303 304 305 308 308 312 313 314 315 317 318 320 322 324 326 X CONTKNTS. PAGE Cupri Oxidum ..... . 329 " Sulphas .... . 330 Cuprum Ammoniatum .... . 332 Curarina ...... . 333 Digitalinum ..... . 334 Elaterinum ..... . 337 Emetina ...... . 338 Ferri Arsenias . 339 ' Carbonas Saccharatus . 340 ' Chloridum . . . . . 341 ' Citras ..... . 343 ' et Ammonii Chloridum . 344 ' '• " Citras . . 345 ' •' " Sulphas . . 346 ' " " Tartras .... . 346 ' " Potassii Tartras . . 347 ' " Quininae Citras .... . 348 ' " Stryohninse Citras . 349^ ' Ferrocyanidum .... . 350 ' Hypophosphis .... . 352 ' lodidum . ... . 352 ' Lactiis .... . 353 ' Oxalas ..... . 355 ' Oxidum Hydratum . . 356 ' Phosphas .... ...... -'-^^ ' Pyrophosphas . . . .- . 359 ' " et Sodii Citras . 359 ' Subcarbonas ...... . 360 ' Sulphas ..... . 361 ' Valerianas ..... . 363 Ferrum ....... . 364 Glycerinum ..... . 370 Detection and estimation of gljcerin in beverages . 372 Hydrargyri Chloridum corrosivum . . 373 " " mite . 375 " Cyanidum ... . 378 " lodidum rubrum . 379 " " viride . 381 " Oxidum flavum . 382 " " rubrum . 382 " Subnitras .... . 385 " Subsulphas flavus . 386 " Sulphidum rubrum . 386 Hydrargyrum ...... . 388 " ammoniatum - 390 Hyoscyaminae Sulphas .... . 392 lod oformum ..... . 392 CONTENTS. XI PA(Jf lodum . .... . 393 Liquor Ammonii Auetatis . . . 397 " Antimonii Chloridi . . . 397 " Calcis . . . 399 Ferri Acetatis . . . 399 '■ " Chloridi . . 401 ■' Citi-atis . 4(12 " et Quinina? C'itratis . . 403 '• " Niti-atis . 404 '■ " Sulphatis . 40.5 " Hydrai-gyri Xitratis 4(i6 " Plrnnbi Subacetatis 40 7 " Potassse . . 408 " Potassii Arsenitis 41(i Sodse . 412 " " Chlorata> 414 Lithii Benzoas 41."i " Bromidum . . 41G " Carbonas . .417 " Citras . 419 " Salicylas . 42(i Magnesia . . 421 Magnesii Carbonas . 4 22 " Sulphas . . . 423 " Sulphis . 42U Manganj Oxidum nigrum 42ii Sulphas . . 429 Morphina . 430 Morphinse Acetas . 432 Morphinse HydrochIora.« 433 " Sulphas ... ... 434 Morphiometa-ic Assa}" of Opium . 43o " ■■ Tincture of Opium 439 Nieotina ... . . . 439 Oleum Amygdalae aethoreum . 44 n " Sinapis asthereum ... . 443 Phosphorus . . ... 445 " Detection of phosphorus in forensic- investigation . 44b' Physostigminae Salicyla^ . . 449 Picrotoxinum . . . 449 Pilocarpinae Hydrochlora* . . 451 Piperina .... 451 Plumbi Acetas . . . 452 " Carbonas . . 453 " lodidum . . . . 455 " Xitras . . 45G " Oxidum . . . 457 xu CONTENTS. Plumbi Oxidum rubrum Potassa Sulphurata . Potassii Acetas " Bicarbonas " Bichromas . ' ' Bitartras " Bromidum Carbonas Crudus " " Depuratus " " Purus ' ' Chloras Citras Cyanidum . " et Sodii Tartras ' ' Ferrocyanidum ' ' Hydras " " .crudus ' ' Hypophosphis " lodidum ' ' Nitras ' ' Permanganas " Sulphas " Sulphis ' ' Tartras Quinidina . Quinidinas Sulphas . Quinina " estimation of the alkaloids in Cinchona bark Quininse Hydrobromas " Bisulphas . ' ' Hydrochloras ' ' Sulphas " Tannas " Valerian as . Resorcinum . Salicinum . Santoninum Sodii Acetas ' ' Arsenias ' ' Benzoas " Bicarbonas ' ' Bisulphis " Boras . " Bromidum ' ' Carbonas " Chloras " Chloridum CONTENTS. xiii PAaE Sodii Hydras ...... . 550 " Hypophosphis ..... . 552 " Hyposulphis . .... . 554 " lodidum .... . 556 " Nitras ... . . . 560 " Phosphas ... . . . 561 " Pyrophosphas . . . . . .564 " Salieylas ...... . 565 " Santoninas . .... . 566 " Sulphas ..... . 56T " Sulphis ... . . . 569 " Sulphocarbolas . . . . . 570 Spiritus jEtheris nitrosi .... . 571 Strychnina . . . . . 574 Strychnina; Nitras . 576 " Sulphas . 578 Sulphur Prascipitatum . 578 " Sublimatum . 581 Sulphuris lodidum .... ■ 58.*! Thymol ... . 583 Veratrina ... . 584 Zinci Aoetas .... 586 " Bromidum .... . 587 " Carbonas Precipitatus . 588 " Chloridum . . . . . 589 " lodidum . 590 " Oxidum . 591 " Phosphidum . 593 " Sulphas . . . 594 " Sulphocarbolas . 597 " Valerianas ...... . 598 Table of Elementary Bodies, with their Symbols and Atomic Weights . 603 Table of Thermometric Equivalents, according to the Centigrade and Fahrenheit Scales ....... 604 Table for converting Metric Measures of Capacity into United States Fluid Measures . . .... 606 Table for converting United States Fluid Measures into Metric Measures of Capacity ...... . 607 Table for converting Metric Weights into Troy Weights . . . 608 Table for converting Troy Weights into Me,tric Weights . . . 609 Index . 611 PART I. OPERATIONS AND REAGENTS, INCLUDING AN OUTLINE OF A SYSTEMATIC COURSE OF QUALITATIVE CHEMICAL ANALYSIS, VOLUMETRIC ESTIMATION, AND A METHOD FOR THE SEPARATION AND RECOaNITION OP THE PRINCIPAL ALKALOIDS AND ALLIED PRINCIPLES. OPERATIONS AI^D REAGENTS. OPERATIONS. The operations involved in the application of simple tests and chemical examinations must be supposed to be familiar to the pharmacist, the druggist, the pharmaceutical or chemical manu- facturer, and the physician. For the student and the less experi- enced operator, however, the following preliminary explanations and descriptions relating to the more important simple operations are considered to be of sufficient practical value to merit a brief notice. Solutions. — With regard to the nature of the product, two kinds of solution are distinguished, simple and chemical. In a "simple solution" the dissolved body retains all of its original properties, with the exception of its physical form, and may be obtained again in its former state on the removal of the solvent by evapo- ration : for instance, solution of ferrous sulphate in water. It is "saturated" when the solvent ceases to take up any more of the dissolved body ; but as the coefScient of solubility of most substances is increased by heat, the expression of saturation will therefore always relate to the temperature at which the solution has been formed. A "chemical solution" is one in which the dis- solved body no longer retains its original qualities, but, .through the action of the solvent, has become converted into a new sub- stance, possessing various!}'' modified chemical and physical prop- erties: for instance, solution of ferrous carbonate in dilute sulphuric acid. Solutions for testing are best prepared in test-tubes, or in small flasks or beaker-glasses. Increase of the surfaces of contact by comminution, agitation, and increase of temperature, as is well known, aid and accelerate the process of solution, as well as of chemical reaction ; and one or both of these auxiliaries may be employed, unless the nature of, the substance or the effect of heat upon it is such as to exclude their application. The common solvent, water, has to be used distilled, and this fact is to be understood throughout this work ; neither rain-water nor spring-water, however pure it may appear to he^ can be used 2 18 MANUAL OF CHEMICAL ANALYSIS. indiscriminately as a solvent or for edulcoration in chemical in- vestigations. To effect the solution of substances insoluble in water, for the purpose of chemical examination, or where the aid of an acid is required, only such acids as are found by the operator himself to be chemically pure should be employed. Precipitation. — The formation of an insoluble body from a solu- tion can be effected either by a change or modification of the solvent, or by the production of one or more new bodies, insoluble in the solvent. An instance of the first case is an aqueous solution of barium chloride, which will be precipitated by the addition of concentrated hydrochloric acid, or a solution of calcium sulphate, which will be precipitated by alcohol ; in both these instances the solvent power of the liquid is lessened, and solution may be re- established by the addition of a sufiicient quantity of water. In- stances of the second case of precipitation are a solution of'Calciura hydrate precipitated by sodium carbonate, and a solution of mag- nesium sulphate precipitated by barium hydrate. Precipitation is resorted to as the most important mode of de- tecting and discriminating bodies by their physical and chemical properties, and of effecting their separation. According to the nature or appearance of the precipitates, they are variously dis- tinguished; thus '' flocculent," when forming flock-like masses; " crystalline," if, when magnified, the small particles are seen to be composed of minute but distinctly formed crystals; "gelatinous," if jelly-like ; or " curdy," if separating in the form of a curd, etc. The terms "turbidity" and "cloudiness" designate the formation of a precipitate so insignificant in quantity, or so finely divided, or so light in weight, that the suspended particles only impair the transparency of the fluid, and require a certain amount of time to subside in the form of a precipitate. If the transparency of a colorless or nearly colorless liquid becomes so slightly impaired upon the addition of a reagent as not to become distinctly turbid, but displays a reflection of pearly light, and thus presents an opal-like appearance, the minute degree of precipitation thus produced is designated as " opalescence." Filtration and Decantation. — The separation of the supernatant liquid from a precipitate is effected either by filtration and subse- quent washing of the precipitate upon the filter by means of a wash-bottle (Figs. 1 and 2), or, where the precipitate speedily and completely subsides, by decantation. As a rule, funnels and filters must be small, and proportionate to the amount of the pre- cipitate and the liquid requiring filtration. Filters employed in analytical operations should be as free as possible from inorganic substances, especially such as become dis- solved by the action of acids, as calcium salts, ferric oxide, etc., and for the collection of precipitates should be smooth, so placed in the funnel as to fit closely on all sides, and out so as not to OPERATIONS. 19 project over the rim ; it is also advisable always to moisten the filter upon the funnel with distilled water, by means of the wash-bottle, previous to the collection of the precipitate, or to filtration. Fig. 1. Fig. 3. Decantation is effected either by pouring off the supernatant clear part of the fluid by simply inclining the vessel, and allowing Fig. 3. the fluid to flow down a glass rod (Fig. 3), or by drawing it off' by means of a small glass siphon or a pipette (Figs. 4 and 5). WasMng Precipitates. — In either mode of separation the precipi- tate, in most instances, must be thoroughly freed from the ad- dering liquid by washing with water, either on the filter or by decantation. As a rule, the washing of precipitates is most thoroughly and quickly effected by means of hot water ; for this purpose nothing more is required than the ordinary wash-bottle, 20 MA>UAL OF CHEMICAL ANALYSIS. Fig. 4. Fig. 5. which, however, for convenience in holding, is provided either with a wooden handle, attached by means of a strong wire to the flask (Fig. 2), or the neck of the flask may be covered with a thick circular strip of corlc, or tightly bound with twine. In order to ascertain whether a precipitate has been sufficiently or thoroughly washed, a few drops of the liquid, as it escapes from the funnel, may~be collected from time to time on platinum foil, and subsequently slowly evaporated, whereby the presence of soluble, non-volatile bodies will be indicated by a visible resi- due. In some cases, and particularly where the bodies to be removed by washing are of a volatile nature, the completion of the operation may be most quickly determined by the application of chemical tests; thus, if the liquid in which the precipitate has been produced contains a sulphate or chloride, the complete removal of these salts will be indicated by testing a few drops of the filtered liquid with barium chloride or argentic nitrate, whilst if the liquid contain free acid, or a volatile alkali, such as ammonia, their complete displacement may be determined by means of litmus. Removing Precipitates from the Filter When a small quantity of a moist precipitate has to be taken from the filter for further examination, this is best done by carefully dipping the end of a thin glass rod into it, and subsequently detaching the adherent part of the precipitate upon a watch-glass, the interior of a small test-tube, or the microscopic glass slide. If a precipitate is to be removed from the filter as completely as possible, this may be accomplished either by puncturing the point of the filter by means of a glass rod, and subsequently washing the precipitate with a fine stream of water or other liquid from a wash-bottle into a receptacle beneath, or the funnel may be held in a horizontal position, so that its rim projects inside the edge of OPBRAXrONS. 21 a porcelain dish or beaker, wlien by directing a fine stream of water against the sides of the filter by means of a wash-bottle, the pre- cipitate may be removed without breaking the filter. If, however, it is not desirable to add a liquid to the precipi- tate, the filter with its contents is first allowed to drain thoroughly in the funnel, and is then opened and placed upon a glass plate or upon several layers of bibulous paper, when the moisture will have soon become sufficiently absorbed to permit the ready removal of the precipitate with a glass rod or a spatula. When it is desired to dissolve a precipitate on the filter, the solvent should, when admissible, be first heated, and gradually poured upon the precipitate, and the filtrate, which will contain the pre- cipitate in solution, collected in a test-tube or beaker ; if the pre- cipitate does not thus become completely dissolved, the filtrate is again heated, and returned to the filter uutil complete solution is effected, which may be finally aided, if necessary, by the addition of a fresh portion of the solvent. If the precipitate should be considerable in amount, the larger portion may be first removed by means of a spatula, and transferred to a porcelain dish or beaker, and the residue upon the filter subsequently dissolved by the aid of the proper solvent. Drying Precipitates. — When a precipitate is required in a dry condition, it is first allowed to drain as completely as possible on the filter, and the funnel and filter are then placed in a hollow tin cone or cylinder (Fig. 6), which is supported on a piece of wire Fig. 6. Fig. 7. gauze over a moderate gas flame, being careful to so regulate the heat as not to char the filter. The operation may also be acconi- plished still more quickly by opening the filter and spreading it with its contents upon a porcelain plate or watch-glass, which is placed upon a piece of wire gauze over a low flame, the proper precautions being observed to prevent excessive heat. In either 22 MANUAL OF CHEMICAL ANALYSIS. case, the precipitate may be first partially dried by opening the filter, and placing it with its contents upon several folds of bibu- lous paper. In the more exact requirements of analysis, the precipitate or other substance requiring desiccation may be placed under a bell- jar containing concentrated sulphuric acid or fragments of fused calcium chloride (Fig. 7), or in an air-bath or drying oven, pro- vided with a thermometer, and the temperature of which is Fig. 8. a uniform be varied regulated by a gas flame (Fig. 8). By this means temperature may be readily maintained, which may in accordance with special requirements. _ Weighing Precipitates, — Before ascertaining the weight of a pre- cipitate, it is usually required to be first completely drfed at a defi- nite temperature. This is accomplished by means of the above illustrated air-bath. The precipitate, after partial drying upon the filter in the funnel, is placed upon a watch-glass, which, too-ether with another glass of the same size and a small brass clam^ has been previously accurately weighed. During the process of 'dry- ing the glasses are placed one within the Fig. 9. other, _ so that the moisture from the precipitate contained on the uppermost glass may readily escape. When. the precipitate has become sufaciently dry, it is removed from the air-bath, the lower watch-glass placed upon the upper, and the whole secured by means of the brass OPERATIONS. 23 clamp (Fig. 9), in order that on cooling no moisture shall be ab- sorbed by exposure to the air. The glasses, with the inclosed precipitate, as indicated in the figure, are brought upon the iDalance, and the weight finally determined. In order to ascertain that no further loss takes place upon drying, the glasses are again opened, placed in the air-bath as before, and the operation re- peated until two successive weighings prove the weight to remain constant. Ignition. — The process of ignition refers to the subjection of solids to a more or less elevated temperature, and is employed for various purposes, but has, usually, for its object, the separa- tion of a volatile from a less volatile or non- volatile body, when the latter alone is required ; it is also frequently employed for ascertaining the effect of strong heat upon a substance. In the latter case the substance is heated in a bent glass tube (Fig. 10), whereby the nature of the evolved gases or sublimate produced may be observed, whereas, if it be required simply to ascertain or confirm the volatile or non-volatile nature of a substance, it is heated on platinum foil, in the non-luminous flame. For the ignition of precipitates, however, the substance is placed in a porcelain or platinum' crucible of convenient size (Fig. 11), sup- FiG. 10. Fig. 11. ported on a wire triangle, and heated in the non-luminous gas flame, or, if a higher temperature be required, by means of the blowpipe or gas blast-lamp. Determination of the Melting and Boiling Point — The melting and boiling point of bodies under normal atmospheric pressure ' The use of platinum vessels should be avoided for heating substances which develop chlorine, the alkaline hydrates, nitrates, and cyanides, metallic sul- phides, readily reducible metallic oxides, salts of the heavy metals with organic acids, or phosphates in the presence of organic compounds. 24 MANUAL OF CHEMICAL ANALYSIS. Fig. 12. being contant and unchangeable, the determination of these factors is an operation which is frequently resorted to for the purpose of establishing the iden- tity of a substance, and for affording confirmatory evidence of its purity. The melting point is determined by bringing a very small portion of the substance into the lower part of a capillary glass-tube (Fig. 12), and attaching the latter by means of a small rubber band to a thermometer, so that the substance will be on the same level and in the most direct possible contact with the thermometer bulb (Fig. 13). The ther- mometer, thus arranged, is then suspended, and the bulb and the capillary portion of the tube allowed to Fig. 13. Fig. 14. dip below the surface of water or sulphuric acid, contained in a beaker ; the liquid employed being adapted to the melting point OPERATIONS. 25 of the substance. The liquid is then very gradually heated hv ri'dXleXlrre^tet ""''''''' "'^ ^^ ^^^^^^^ ^^^-^ The boihng point is determined by bringing the liquid into a vessel adapted for fractional distillation (Fig. 15) or Sto -in ordi nary glass flask provided with a doubly perforated cork (Mg I ej; Fm. 15. Fig. 16. I 1- ] / so Fie. in one orifice of which the thermometer is inserted, while the other IS provided with a bent glass tube, which may be connected with a condenser. The thermometer should not be allowed to become immersed in the liquid, but should simply proiec far into the interior of the flask ^ ^ r j as to be surrounded by the vapor of the boiling liquid. On the appli- cation of heat, the boiling point will be indicated by the height of the mercurial column when the liquid is in a state of active ebulli- tion. Bending of Glass Tubing Glass tubing may be regularly and uni- formly bent in any desired shape 2(J MANUAL OF CHEMICAL ANALYSIS. by the use of the upper edge of the commoa fish-tail gas-flame; the flarn'e of the Bunseu gas-lamp cannot be well employed, producing unsatisfactory curves. The tube is held in a horizontal position in the. flame at the point requiring to be bent, so that it becomes entirely enveloped by the illuminating portion ; it soon becomes covered with a deposit of soot, and, when sufficiently heated, bends itself by the weight of the unsupported end (Fig. 17). The bend, if properly made, will form a symmetrical curve, without diminish- ing the calibre of the tube at any point, and will be free from sharp angles. Glass tubing or rods when employed in analytical or chemical operations should have no sharp or protruding edges, but should be made smooth and round by holding the ends for a few seconds in the non-luminous gas-flame. EEAGENTS. The methods of chemical analysis and investigation consist in bringing the substances under examination into contact with other bodies of known properties, and observing the resulting phenomena. These phenomena consist in alterations, either in state of aggregation, form, or color, resulting from some chemical change. All bodies which are employed for this purpose are called reagents, and the ensuing phenomena reactions. It is obvious, therefore, that a sufficient knowledge of theo- retical chemistry in its details, and especially a familiarity with the deportment, properties, and relations of the common com- pounds and reagents, are indispensable to the pursuit of chemical tests and examinations. Upon such knowledge depend the con- ception and comprehension of the conditions necessary for the formation of new compounds, and for the manifestation of the various reactions, as well as the correct inference from the obser- vations and results of all investigations ; and without it they will remain unavailing and uncertain. No special and definite rules can be assigned for the applica- tion of reagents in each instance, with respect to their proportion and quantity. These must depend upon the quantity and nature of the substance under examination and its solution, as well as upon the nature of the reagent, the strength of its solution, and the processes taking place in each particular reaction. Knowl- edge and reflection, as well as a ready comprehension of the object and aim of each test, of its issues, and of the possible inci- dents, and a correct inference from all phenomena, must decide at large, as well as in detail, not only what reagents should be employed, but also the amount and the conditions in each par- ticular instance. The general method for ascertaining the sufficient or slightly REAGENTS. 27 excessive amount of a reagent, as has to be done before proceeding in the systematic course of analysis, is to add a few drops more of the reagent to the clear liquid obtained either by allowing the precipitate to subside, or by filtering off a small quantity of it ; if any further precipitate is formed, the filtered portion must be re- turned, more of the reagent added, and the clear liquid again examined with a few additional drops of the reagent, until no further precipitate is produced. With some reagents, as, for in- stance, with hydrogen sulphide or ammonia water, this method of procedure is rendered unnecessary, an excess being indicated by their characteristic odor. A common error, and an obstacle to the less skilled, is the use of an undue excess of reagents.' There are reagents which in many cases admit a free application without disadvantage to the correctness of the result — as, for instance, hydrogen sulphide, solution of calcium hydrate, etc. ; but the majority of reagents need to be applied in common tests only by a few drops of their solutions — as, for instance, bario, ferric, cupric, and argentic solu- tions, etc. On the other hand, there are not unfrequentlj' errors arising from an insufficient amount in the application of reagents, especially with dilute solutions, or in those cases in which the complete elimination of a substance by precipitation is required for the subsequent examination for other bodies : for instance, hydrogen sulphide, applied in a limited quantity, produces a white precipitate with solutions of mercuric salts ; applied in excess, it gives a black precipitate. There are other instances where an excess of the solution under consideration, as well as of the reagent, may redissolve, and consequently destroy, the pre- cipitate whereon the reaction is based. In operations of chemical analysis it must always be borne in mind and well understood that, in the processes and phenomena taking place between the reagents and the substances act.'d upon, as in all chemical changes and reactions, certain laws and definite limits exist between cause and efi'ect, and that the ability of cor- rectly applying knowledge, judgment, and skill, and of drawing the right inference from necessary as well as from casual reactions and phenomena, must rule and guide the methods and operations of the investigator, and carry them beyond mere conjecture and empiricism. It is beyond the scope of this work to describe the mode of preparing the reagents, their use and application, and their deport- ment with the common compounds, or to dwell upon the general rules of systematic methods, accuracy, order, neatness, and clean- liness to be observed in the execution of analytical work. For such information reference must be had to the text-books of applied and analytical chemistry. From a practical point of view, only the usual strength of the solution of the reagents, as best suited for the common tests and examinations, and the mode of 28 MANUAL OF CHEMICAL ANALYSIS. preparing a few of the rarer or special reagents, or of such as are not included among the medicinal chemicals considered in this volume, have been stated. As regards the strength of the solutions of reagents, unless otherwise stated, the test solutions described upon the following pages are invariably understood to be used wherever the name of the reagent only is stated. It hardly needs to be mentioned that all reagents must consist purely of their essential constituents, and must contain no admix- ture of any other substance ; it must, therefore, be an invariable rule to test the purity of the reagents before they are employed. The reagents and their solutions must be preserved according to their nature ; of those whose solutions are liable to alteration or decomposition only small quantities must be kept, and always in tightly closed glass-stoppered bottles. EEAGENTS AND TEST SOLUTIONS. 29 REAGENTS AND TEST SOLUTIONS. Fig 18 Acetic Acid Spec. grav. 1.048. Acetic Acid, Diluted.- — Obtained by mixing 1 part of acetic acid with 4 parts of water. Hydrochloric Acid Spec. grav. 1.16 ; containing 32.2 per cent. of absolute acid. Hydrochloric Acid, Diluted Spec. grav. 1.049; containing about 10 per cent, of absolute acid. Obtained by mixing 6 parts of hydrochloric acid with 13 parts of water. Hydrosulphuric Acid. See Hydrogen Sulphide. Nitric Acid. — Spec. grav. 1.42 ; con- taining 69.4 per cent, of absolute acid. When concentrated acids are applied in small tests only by the drop, as, for instance, in testing alkaloids, etc., they are taken from the bottle by dipping a glass rod into the acid and allowing the drop or drops to fall upon the substance to be acted upon, or better by means of a kind of pipette consisting of a thin, strong glass tube, adjusted at one end to a small caoutchouc bulb, and con- tracted at the other extremity to a capil- lary end. The fluid is drawn into the tube, and delivered again by gentle pressure of the bulb (Fig. 18). Nitric Acid, Diluted. — Spec. grav. 1.059; containing 10 per cent, of absolute acid. Obtained by mixing 1 part of nitric acid with 6 parts of water. Nitro-hydrochloric Acid (Aqua Eegia). — 4 parts by weight of nitric acid, spec. grav. 1.42, are gradually added to 15 parts by weight of hydrochloric acid, spec. grav. 1.160, in a capacious, open glass vessel, and, when effervescence has ceased, the product is transferred to glass-stoppered bottles, which should be not more than half filled, and preserved in a cool place. Oxalic Acid,' — Solution of 1 part of crystallized oxalic acid in 10 parts of water. Picric Acid. — Saturated aqueous solution of picric acid. 30 MANUAL OF CHEMICAL ANALYSIS. Sulphuric Acid, Concentrated. — Spec. grav. 1.84; containing 97 per cent, of absolute acid. Sulphuric Acid, Strong. — Spec. grav. 1.64; containing 72.75 per cent, of absolute acid. Obtained by carefully mixing, in a flask or beaker, 3 parts of concentrated acid with. 1 part of water (Fig. 19). Fig. 19. In diluting concentrated sulphuric acid with water, the acid should invariably and gradually be added to the water, and in vessels which are either placed in cold water or which are not liable to crack from the heat evolved. Sulphuric Acid, Diluted.— Spec. grav. 1.068; containing about 10 per cent, of absolute acid. Obtained by mixing 1 part of con- centrated acid with 9 parts of water. Sulphurous Acid.— Spec. grav. 1.046. An aqueous solution of sulphurou.s acid gas, saturated at 15° C. (59° F.), containing 36 times its volume, or about 9.5 per cent, by weight of the gas. Tannic Acid — Solution of 1 part of tannic acid in a mixture consisting of 18 parts of water and 2 parts of alcohol. Tartaric Acid — Solution of 1 part of crystallized tartaric acid in 5 parts of water. Albumen. — The white of one egg is triturated Avith 100 cubic centimeters of water, and is then filtered through cotton previously moistened with water. Alcohol. — Spec. grav. 0.820 ; containing 91 per cent, by weight or 94 per cent, by volume of absolute alcohol. Alcohol, Absolute.— Spec. grav. 0.795. Alcohol, Amylic — Spec. grav. 0.816 to 0.818. Aluminium. — Metallic aluminium in the form of wire or ribbon. Ammonia Water (Aqua Ammonia). — Spec. grav. 0.959. An aqueous solution of ammonia, containing 10 per cent, by weight of the gas. EEAGENTS AND TEST SOLUTIONS. 31 Ammonia Water, Stronger (Aqua Ammonise Fortior, U. S. P.). — Spec. grav. 0.900. A nearly saturated aqueous solution of ammonia, containing 28 per cent, by weight of the gas. Ammonium Carbonate. — Solution of 1 part of unefBoresced am- monium carbonate in a mixture of 4 parts of water and 1 part of ammonia water. Ammonium Chloride. — Solution of 1 part of crystallized ammo- nium chloride in 10 parts of water. Ammonium Molybdate. Ammonium Molybdate in Nitric Acid. — Solution of 1 part of ammonium molybdate in 10 parts of water, to which 10 parts of nitric acid, spec. grav. 1.2, are subsequently added. Ammonium OKalate. — Solution of 1 part of crystallized ammo- nium oxalate in 20 parts of water. Ammonium Phosphate. — Solution of 1 part of ammonium phos- phate in 15 parts of water. Ammonium Sulphide. — A solution of ammonium sulphide in water; it is obtained by saturating, at 15° C. (59° F.) or a lower temperature, 3 parts of Aqua Ammonias Fortior, U. S. P., with hydrogen sulphide gas, and by subsequent addition of 2 parts of ammonia water. It isbest preserved in small vials, tightly corked, and in a cool place. This solution, being concentrated, has to be employed, in tbe common tests, only in small quantities, mostly by drops. When hydrogen sulphide is at hand, ammonium sulphide may, in many of its applications, be produced by saturating the liquid under examination with the gas, and by the subsequent addition of ammonia water; or, in ammoniated solutions, if dilution does not interfere with the reaction, by the addition of an aqueous solu- tion of hydrogen sulphide. Aniline Sulphate. — Solution of 5 drops of aniline in 25 cubic centimeters of diluted sulphuric acid. Argentic Nitrate. — Solution of 1 part of crystallized argentic nitrate in 20 parts of w^ter. Argentic Nitrate, Ammoniated. — Solution prepared by adding ammonia water, spec. grav. 0.959, in drops, to test-solution of argentic nitrate, until the precipitate at first formed is very nearly all redissolved, and filtering. Argentic Sulphate. — Solution of 1 part of argentic sulphate in 250 parts of water. Auric Chloride. — Solution of 1 part of auric chloride in 20 parts of water. Barium Chloride. — Solution of 1 part of crystallized barium chloride in 10 parts of water. Barium Hydrate (Baryta-water). — Saturated aqueous .solution of barium hydrate, containing about 5 per cent, of the hydrate. Barium Nitrate. — Solution of 1 part of crystallized barium nitrate in 20 parts of water. 32 MANUAL OF CHEMICAL ANALYSIS. Benzin (Petroleum Benzin or Petroleum Ether).— Spec. grav. from 0.670 to 0.675, and boiling at 50 to 60° C. (122 to 140° F,). Benzol. — Spec. grav. 0.885. Borax. Bromine Water. — A saturated solution of bromine in water. Calcium Chloride. — Solution of 1 part of pure crystallized cal- cium chloride in 10 parts of water. Calcium Hydrate (Lime-water). — Saturated aqueous solution of calcium hydrate. Calcium Sulphate. — Saturated aqueous solution of calcium sul- phate, containing about 0.2 per cent, of the salt. Carbon BisulpMde. — Spec. grav. 1.272. Chlorine Water. — A saturated aqueous solution of chlorine, con- taining about 0.4 per cent, by weight of the gas. For analytical iise, this solution is best preserved in small vials, tightly corked and sealed, in a cool place, and protected from the light. Chloroform, — Spec. grav. 1.480. Cobaltous Nitrate. — Solution of 1 part of cobaltous nitrate in 10 parts of water. Copper. — Metallic copper in slender wire, or thin foil cut into strips. Cupric Sulphate, — Solution of 1 part of crystallized cupric sul- phate in 10 parts of water. Cupric Sulphate, Ammoniated. — Solution prepared by adding ammonia water, spec. grav. 0.959, in drops, to test-solution of cupric sulphate, until the precipitate at iirst formed is very nearly all re- dissolved, and filtering. Cupric Tartrate, Alkaline Solution of, (Fehling's Solution). — 17.32 grams (267.3 grains) of pure crystallized cupric sulphate are dissolved in 100 cubic centimeters (about 8 fluidounces) of water ; and 85 grams (2 ounces and 457 grains) of pure crystallized potas- sium and sodium tartrate are dissolved in 800 cubic centimeters (about 10 fluidounces) of a 10 per cent, solution of sodium hydrate. The cupric solution is then gradually added to the alkaline solu- tion, and, having been well mixed, so much water is added as to make the whole measure 500 cubic centimeters (16 fluidounces). The solution should be free from yellowish -brown sediment, and should deposit none upon boiling. Ether.— Spec. grav. 0.750. Ferric Chloride.— Solution of 1 part of ferric chloride in 10 ■parts water. Ferric Dinitrosulphide. — Obtained by adding, drop by drop, a solution of ferric chloride or sulphate, with constant stirring, to a mixture consisting of equal parts of strong solutions of potassium nitrate and ammonium sulphide, heating the liquid to boiling for a few minutes, and filtering while hot from the sulphur. The deep-colored liquid deposits, on cooling,- black, needle-shaped rhombic prisms of ferric dinitrosulphide; these are dissolved 1 part in 10 parts of water, to give the required solution. REAGENTS AND TEST SOLUTIONS. 33 Ferrous Sulphate. — Solution of 1 part of ferrous sulphate, ob- tained by precipitation with alcohol, in 10 parts of water. Ferrous sulphate is best obtained by pouring an aqueous solu- tion of freshly prepared crystallized ferrous sulphate, saturated at the boiling-point, into strong alcohol, collecting the precipitate upon a filter, washing with a little alcohol, drying by pressing between filtering-paper, and by immediately filling the humid salt iuto small warm vials, which are corked and sealed while warm. The absence of ferric sulphate may be ascertained by testing the solution with potassium ferrocyanide ; no blue turbidity, or only a very slight one, should occur. Gelatin. — Solution obtained by digesting 1 part of isinglass (ichthyocolla) with 50 parts of water, on a water-bath, for half an hour, and subsequently filtering through cotton, moistened with water. Gold. — Metallic gold in the form of leaf. Hydrogen, Nascent, is a very delicate means of detecting arsenic. The test depends upon the production of hydrogen arsenide (ar- seniuretted hydrogen), whenever arsenic is present in any soluble form, in which hydrogen is being evolved by the action of dilute sulphuric or hydrochloric acid upon zinc or magnesium. From the hydrogen arsenide the arsenic can be separated in a charac- teristic and unmistakable form, either as metal, or by leading the gas into a solution of an easily reducible metallic salt, as, for instance, argentic nitrate, in which case the silver is precipitated and a solution of arsenious acid is obtained. AsH, + 8H,0 + 6AgN03= H3ASO3 + 6HN0, + 3Ag,. Marsh's Test. — Of the different methods for the application of this test, the one long and commonly known as Marsh's test is pre-eminently adapted for the recognition, as also for the quanti- tative estimation of small amounts of arsenic. A complete and simple form of apparatus for the application of Marsh's test is represented in Fig. 20. It consists of a gas generating flask or Woulff's bottle (A), of about 300 to 400 cubic centimeters (10 to 14 ounces) capacity, provided by means of a peforated cork or rubber stopper with a funnel tube {b), and a drying tube (a), loosely stopped at each end with a small plug of cotton, and par- tially filled with dry calcium chloride in small fragments, followed by a layer of small pieces of dry potassium hydrate ; the latter serving to retain any acid which may accidentally be carried over with the gas, as also any trace of hydrogen sulphide. The end of this tube is connected with a reduction tube (d), of hard German glass, narrowly drawn out in one or more places, and at the end into a capillary point, and bent up so as to form a vertical jet, as shown in Fig. 20. The test consists in introducing into the flask (A) pure granu- lated zinc or magnesium, and adding gradually,' by means of the funnel tube, a cold mixture of one part of sulphuric acid and 3 34 MANUAL OF CHEMICAL ANALYSIS. three parts of water, when the hydrogen is more or less quickly evolved. When perfectly pure zinc is employed, the development Fig. 30. of gas takes place very slowly, and may be hastened by the addi- tion of a few drops of test solution of platinic chloride. Fig. 21. It is of primary importance in each case where the test is ap- plied to first ascertain the absolute purity of the zinc or magne- sium and acid employed. REAGENTS AND TEST SOLUTIONS. 3o After the evolution of gas has continued long enough to expel the atmospheric air,' the reduction tube (d) is heated to redness in the part indicated in the figure for about ten minutes, the escaping gas is lighted, and a piece of white porcelain is held in the flame. If no dark deposit takes place, either in the tube or on the porcelain, the reagents may be considered pure, and the liquid to be tested rnay then be added through the funnel tube (b), first in small amounts, and the operation continued in the manner described. If arsenic-spots or mirrors are obtained in the tube, a number of them may be produced by heating the tube in at least two places, at distances of about three inches, or if an approximately quantitative estimation of the arsenic is desired, all the arsenic may be obtained by the employment of a larger reduction tube and several flames (Fig. 21). The obtained arsenic mirrors may be examined for identification, or quantitatively determined by subsequently removing the tube and determining the increase in weight. In cases where it is desirable to estimate the entire amount of arsenic, and guard against possible loss, instead of allowing the developed gas to burn, it is preferable to conduct it into a solu- tion of argentic nitrate, in which case any arsenic which may have escaped reduction in the glass tube will be recovered, and contained in the solution as arsenious acid, together with the ex- cess of the undecomposed silver salt. As is well known,certaincompoundsof antimony, when brought into Marsh's apparatus, give rise to the formation of hydrogen antimonide (antimoniuretted hydrogen), analogous in composition to hydrogen arsenide, which, when subjected to the same process of reduction as above described, produces black spots of metallic antimony. These spots are so different in their physical appear- ance and properties as to be readily distinguished by the experi- enced operator, and, when subjected to chemical tests, display so marked a difference that their discrimination from those of arsenic is readily effected. To enumerate in detail all the special tests for each of these two metals would lead beyond the scope of this work ; the prin- cipal distinctive characters, however, will be briefly described. The mirror of arsenic, as obtained in the reduction-tube, when gently heated during the simultaneous development of a current of hydrogen, can easily be driven from one place to another, and, if the gas be allowed to escape at the exit tube, the develop- ment of the arsenical or garlic-like odor can at the same time be observed ; whilst antimony, on account of the much higher temperature required for its volatilization, cannot be so readily 1 This may be determined by holding an inverted dry test-tube over the point of exit of the gas for a few seconds, and tlien bringing the mouth of the test- tube in contact with the flame ; if the air be entirely expelled from the appa- ratus, the gas burns quietly, if not, a slight explosion ensues. 36 MANUAL OF CHEMICAL ANALYSIS. removed from the place in whicli it "was deposited, and the escaping gas is quite odorless. The spots of arsenic, obtained by holding the' cold surface of a piece of white porcelain in the flame during the development of the hydrogen arsenide, have a bright metallic lustre, whilst the. spots of antimony have a dull velvety black appearance. When touched with a solution of sodium hypochlorite or chlorinated lime, the arsenic spots become immediately dissolved, whereas the spots of antimony remain unaffected ; by this means arsenic can be detected, even when accompanied by antimony. The spots of arsenic, when touched with a drop of a solution of ammonium sulphide, and gently warmed, become completely dis- solved, and, on being allowed to dry, display the bright yellow color of arsenious sulphide ; antimony under the same circum- stances gives an orange-red coloration of antimonious sulphide. The yellow arsenious sulphide remains unaffected upon the addi- tion of a drop of hydrochloric acid, whilst antimonious sulphide is readily dissolved ; and inversely a solution of ammonium carbonate dissolves the arsenious sulphide, but does not act upon the anti- monious sulphide. These few points of distinction in relation to this important and characteristic test are sufBcient in the majority of cases to render possible a prompt determination, as to the pre- sence or absence of one or both of these metals, and to effect their discrimination. Precautions to he observed in the Application of MarsKs Test for Arsenic. — Although this test is so delicate as to render possible the detection of exceedingly small amounts of arsenic, certain precautions are necessary, which, if not observed, may prove a source of serious error, and lead to incorrect inferences. The sulphuric acid employed for generating the hydrogen gas should be free from the lower oxy-acids of sulphur and selenium, of the proper dilution, and cold ; for if concentrated and warm, sulphurous-acid gas will be produced, which, combining with the nascent hydrogen, forms hydrogen sulphide, and a precipitation of arsenic as insoluble sulphide would result. Nitric acid and nitrates, free chlorine and other similar oxidiz- ing agents must be rigidly excluded in the application of the test, as preventing the formation of the gaseous hydrogen arsenide. Hydrochloric acid can also not be substituted to advantage for the sulphuric acid for the generation of the hydrogen, for although it does not interfere with the formation of hydrogerf arsenide, yet on account of its greater volatility, and tendency to the produc tion of the so called zinc spots, the presence of arsenic might be erroneously inferred. Another test which may be employed for the detection of small amounts of arsenic, and which commends itself for con- venience of application, is that known as : Fleitmann's Test. — This consists in the generation of hydro- gen by the action of a strong solution of potassium or sodium REAGENTS AND TEST SOLUTIONS. 37 Pig. 32. r 1 ) 1 hydrate on metallic zinc or aluminium, by the aid of heat. The operation may be performed quickly in a long test-tube, taking care that the tube is only filled to about one- tenth of its capacity. As soon as the gas is generated, the solution to be tested is cautiously added to the alkaline liquid, and a cap of white filter- ing paper, moistened with a drop of solution of ar- gentic nitrate, placed over the tube (Fig. 22). If arsenic is present, a purplisli-black spot, due to the reduction of the argentic nitrate to metallic silver, will be produced upon the moist paper cover. This reaction is of particular importance and value, for while antimony combines with hydrogen evolved from dilute acids and zinc, it does not combine with hydro- gen evolved by the action of an alkali on the same metal. Hydrogen Sulphide (Hydrosulphuric Acid, or Sul- phuretted Hydrogen). — Obtained by the action of di- luted sulphuric or hydrochloric acids upon ferrous sul- phide. Atnong the several convenient forms of ap- paratus for the continuous preparation of the gas and to keep it ready for use, the one represented in Fig. 23 is frequently employed. It consists of three glass bulbs, the two lower ones being a single piece, and the "^"^ upper one, prolonged by a tube reaching to the bottom of the lower, being ground air-tight into the neck of the second. Through the tubulure of the middle bulb the ferrous sulphide is introduced, and the tubulure then closed by a cork containing a wide glass tube provided with a stop- cook, or with a rubber tube, closed by a Mohr's wire clamp (see p. 7-±). The acid is poured in through the safety-tube, runs into the bottom globe, and rises to overflow the ferrous sulphide in the middle one. When the air has been allowed to escape through the delivery-tube, and this is closed, the pressure of the accumulating hydrogen sul- phide forces the liquid from the second bulb down into the lower, and thence into the upper bulb, thus stopping the action, and pre- serving a volume of the gas ready for use. Another form of apparatus, which is recommended for sim- FiG. 83. 38 MANUAL OF CHEMICAL ANALYSIS. plioity of construction and the facility with which it may be cleansed or supplied with fresh material, is represented in Fig. 24:. A glass cylinder, about 40 centimeters (nearly 16 inches) high, and 12 centimeters (4| inches) wide, is partially filled with diluted sulphuric acid. It is closed with a cork or rubber stopper having a lateral notch, and carrying a rather long tube, drawn out at its lower end to a small point. This tube is filled with coarse frag- ments of ferrous sulphide, and is closed with a tightly fitting cork or rubber stopper, through which the delivery-tube (provided with a stop-cock) passes. When the apparatus is not in use, the inner cylinder is drawn upwards, until its point merely is immersed in the liquid. When the gas is required, the tube is depressed to the position shown in the figure, and the stop cock opened. The acid then enters from below, and generates a more or less rapid current of the gas, which may be regulated by means of the stop-cock. When the latter is closed, the pres- sure of gas inside the inner tube forces the liquid back into the glass cylinder. When the above described forms of appa- ratus are not at hand, hydrogen sulphide may be generated, in small tests, from a little flask or test-tube (Fig. 25), taking care that none of the contents of the flask pass through the de- livery-tube into the liquid under examination. Fig. 25. Pig. 24. Hydrogen Sulphide Water A solution of hydrogen sulphide (hy- drosulpharic acid, or sulphuretted hydrogen) in water, saturated at 15" G. (59° F.), or at a lower temperature, containing about four times its volume of the gas. The gas is obtained, as above described, by the action of diluted sulphuric acid upon ferrous sulphide, and is washed by water, contained in a small flask or cylinder (Fig. 2(5), before passing it into water for absorption. In order to preserve the hydrogen sulphide in this form, it is advisable to fill the freshly-prepared saturated solution immedi- ately into small vials, and to place them, tightly corked, in an inverted position, in a cool place. When, in the, course of a test, a solution has to be acted upon REAGENTS AND TEST SOLUTIONS. 39 for some time by hydrogen sulphide, a test-tube or flask may be employed, of such size as nearly to be filled by the liquid. It may then be tightly stoppered, allowing sufficient escape of air before corking, if it has to be warmed. Fig. 26. Indigo Solution (Solution of Indigo in Sulphuric Acid). — 1 part of finely powdered indigo is gradually added to 6 parts of fuming sulphuric acid; the mixture, after having been well stirred, is then allowed to repose in a covered vessel for about two days, when it is poured into 20 times its volume of water, the solution well mixed, filtered, and preserved for use in a glass-stoppered bottle. Iodine Water. — A saturated solution of iodine in water. lodinized Potassium Iodide. — Solution of 1 part of iodine and 3 parts of potassium iodide in 60 parts of water. Magnesium. — Metallic magnesium in the form of wire or ribbon. Magnesium Mixture (Ammoniated Magnesium Sulphate). — A solution of 11 parts of crystallized magnesium chloride or sul- phate and 14 parts of ammonium chloride in 70 parts of stronger ammonia water and 130 parts of water. (Magnesium chloride is to be preferred to the sulphate in the preparation of the solution, as having less tendency in its application to produce basic salts.) Magnesium Sulphate,— Solution of 1 part of crystallized mag- nesium sulphate in 10 parts of water. Mercuric Chloride. — Solution of 1 part of crystallized mercuric chloride in 20 parts of water. Mercuric Oxychloride (Bohlir/s Reagent). — To a dilute solution of mercuric chloride in water (1 : 30) a dilute solution of potas- sium carbonate (1 : 50) is added, drop by drop, with constant agitation, until a perfectly neatral solution is obtained. Phosphorous Salt (Sodium-ammonium-hydrogen Phosphate). 40 MANUAL OF CHEMICAL ANALYSIS. Platinic CUoride. — Solution of 1 part of platinic chloride in 20 parts of water. Plumbic Acetate. — Solution of 1 part of crystallized plumbic acetate in 10 parts of water. Plumbic Nitrate. — -Solution of 1 part of crystallized plumbic nitrate in 10 parts of water. Potassium Acetate. — Solution of 1 part of potassium acetate in 5 parts of water. Potassium Antimoniate. — -A cold, saturated, aqueous solution of potassium antimoniate. Potassium Bicarbonate. — Solution of 1 part of potassium bicar- bonate in 10 parts of water. Potassium Bichromate Solution of 1 part of potassium bichro- mate in 10 parts of water. Potassium Carbonate Solution of 1 part of pure potassium carbonate in 3 parts of water. Potassium Cluromate, Neutral. — Solution of 1 part of potassium chromate in 10 parts of water. Potassium Cyanide. Potassium Ferricyanide. — Solution of 1 part of potassium ferri- cyanide in 10 parts of water. To be prepared as required. Potassium Ferrocyanide. — Solution of 1 part of potassium ferro- cyanide in 10 parts of water. Potassium Hydrate (Liquor Potassas, U. S. P.). — Containing 5 per cent, of potassium hydrate. Potassium Iodide. — Solution of 1 part of potassium iodide in 20 parts of water. Commercial potassium iodide occasionally contains traces of potassium iodate, and this should be eliminated by dissolving the salt in boiling alcohol, to saturation, filtering the hot solution, and, when cool, collecting and drying the separated salt. Potassium Mercuric Iodide. — A solution of 1.35 grams of mer- curic chloride and 4.98 grams of potassium iodide in 100 cubic centimeters of water. Potassium Mercuric Iodide with Potassium Hydrate (Nesshr's Test). — 10 grams of potassium iodide are dissolved in 10 grams of hot water, and a hot solution of 6 grams of mercuric chloride added until the precipitate of mercuric iodide ceases to be dis- solved. The mixture is then filtered, the filtrate mixed with a concentrated solution of 30 grams of potassium hydrate, and diluted to the measure of 200 cubic centimeters. To this solu- tion 5 cubic centimeters of the above-prepared mercuric chloride solution are subsequently added, and the liquid, after having been allowed to become perfectly clear by standing, preserved in well stoppered bottles. Potassium Nitrate. Potassium Nitrite, Potassium Permanganate. — Solution of 1 part of potassium per- manganate in 1000 parts of water. REAGENTS AND TEST SOLUTIONS. 41 Potassium Sulphate.— Solution of 1 part of potassium sulphate iu 15 parts of water. Potassium Sulphocyanide Solution of 1 part of potassium sul- ptiocyanide in 20 parts of water. Soda-Lime, — Quicklime is slaked with a solution of sodium hydrate, of such a strength that about 2 parts of quicklime are mixed with 1 of sodium hydrate; the product, after drying, is heated to bright redness, subsequently finely powdered, and pre- served in tightly stoppered bottles. Sodium Acetate.' — -Solution of 1 part of crystallized sodiam acetate. in 5 parts of water. Sodium Bicarbonate. — Saturated aqueous solution of sodium bicarbonate. Sodium Bitartrate. — Saturated aqueous solution of sodium bitartrate. Sodium Carbonate. — Dehydrated by exsiccation. Sodium Carbonate. — Solution of 1 part of crystallized sodium carbonate in 10 parts of water. Sodium Hydrate (Liquor Sod^, U. S. P.). — Containing 5 per cent, of sodium hydrate. Sodium Hyposulphite. — Solution of 1 part of crystallized sodium hyposulphite in 10 parts of water. Sodium Molybdate, Sodium Phosphate. — Solution of 1 part of crystallized sodium phosphate in 10 parts of water. Stannous Chloride. — Saturated solution of real and pure tinfoil in concentrated hydrochloric acid, with subsequent addition of a little concentrated hydrochloric acid. Starch Mucilage (Gelatinized Starch). — 1 part of finely powdered starch is triturated with a little water, the mixture diluted with about 100 parts of water, and subsequently heated to the boiling- point; after cooling, and having been allowed to subside, the clear liquid is decanted. The reagent should be freshly prepared, when required. Zinc. — Metallic zinc, in slender sticks, or small fragments, or in thin disks, prepared by melting and pouring in a thin stream into water. PREPARATION OP TEST PAPERS, ETC. Neutral Litmus Solution is prepared by digesting 1 part of com- mercial litmus with alcohol, with the aid of a gentle heat, for about fifteen minutes; the alcoholic liquid, which contains oljjec- tionable coloring matters, is decanted, and the litmus subsequently extracted with about 10 parts of water, by digestion on the water- bath, and filtered. The filtrate thus obtained is divided into two equal parts ; to one of them, by means of a glass rod, very dilute sulphuric acid is added, with constant stirring, until the liquid turns faintly red ; 42 MANUAL OF CHEMICAL ANALYSIS. the red liquid is then added to the reserved blue portion, and the whole well mixed. If it is desirable to preserve the solution for any length of time, about 5 per cent, of alcohol should be added, or it must be kept in bottles provided with a perforated stopper, through which a bent glass tube may be inserted, or loosely stopped with cotton, in order to admit access of air, and exclude dust; if these precau- tions be neglected, the solution soon becomes mouldy or dis- colored, and unfit for use. Blue Litmus-Paper is prepared by drawing unsized white paper (Swedish filtering-paper) through the above neutral liquid. Red Litmus-Paper is prepared by drawing unsized white paper (Swedish filtering-paper) through the acidulated reddened part of the litmus solution, as obtained and described above, in the prepa- ration of neutral litmus solution. The paper thus prepared is dried in warm air by suspension over a thread, and for ready use is cut into strips about one-third of an inch wide and four inches long, and preserved inclosed in paraffin-paper, or in tightly corked bottles, protected from the light. In reactions of neutralization, where carbonic aid gas is evolved, this substance acts on litmus, and may impair the cor- rectness of the test ; in such operations it is therefore better, if admissible, to operate on warm solutions, in order quickW to expel the carbonic acid gas ; if heat be incompatible, turmeric- paper may be used instead of litmus-paper. Turmeric Solution Obtained by digestion of 1 part of powdered turmeric in a mixture of 4 parts of alcohol and 3 parts of water. After one or two days, the liquid is filtered oft' and preserved. Turmeric-Paper is prepared from this tincture by steeping in it white unsized paper (Swedish filtering-paper). The paper need not be preserved from the action of the atmosphere, since it remains unchanged by carbonic acid. Alkanet-Paper is prepared like litmus-paper, by saturating un- sized paper with a solution of the alkanet-red. This is obtained by extracting dry alkanet root with ether; the filtered solution is ready for use. The blue paper may be obtained from the red one by dipping it into an aqueous solution of sodium carbonate (1:500). A neu- tral paper, answering for the alkaline as well as the acid test, may be prepared by dividing the ethereal solution of alkanet-red into two equal parts ; to one is added, drop by drop, an aqueous solu- tion of sodium carbonate, until the red is just changed to a dis- tinct blue tint ; then both liquids are mixed and used for the preparation of the paper. Plumbic Acetate-Paper serves for the detection of hydrogen sul- phide, and is prepared by dipping white unsized paper (Swedish filtering-paper) into a solution of plumbic acetate, and, when dry, cutting into strips of a convenient size, which may be preserved inclosed in paraffin-paper. A SYSTEMATIC COURSE OP QUALITATIVE CHEMICAL ANALYSIS. Chemical tests and examinations must be founded upon a thorough knowledge of the nature and relations of the reagents, and of their deportment with the common compounds, and also upon a certain fixed order and methodical system in their appli- cation. These attainments, and the necessary skill, experience, and judgment, are requisite for every one who enters upon testing and investigation with a chance or claim of accuracy or certainty. It is advisable in analytical work to enter the result of each test as soon as satisfactorily completed into a note-book, whereby th.e brief symbolic notation may be used to advantage ; the analysis is thus recorded, step by step, as it progresses until com- pleted. It may also be stated here that a reasonable economy with the substance under examination, especially if only of a small quan- tity, and with its solutions is necessar}', so as to leave enough of the former for unseen contingencies and for confirmatory tests, as well as to repeat or verify any and all results of the examina- tion. All tests and reactions are, therefore, performed on as small a scale as is reasonable and appropriate in the particular case ; and all operations should proceed accordingly, and with constant observance of the principles and processes whereon they depend. The following brief outline of a simple progressive course ot qualitative chemical analysis depends, first, upon the successive elimination of groups of elementary compounds which possess certain common chemical properties, and, finally, upon the recog- nition of each member of such groups ; it may therefore serve as a guide whenever, in the course of investigation, recourse is to be had to such a systematic method of analysis. When the object of the examination is only to establish the presence or absence of some particular substance, the character- istic reagent may be employed at once, provided there be no other substance present which would interfere with, or exclude, the direct application of the test; but, if a qualitative analysis is required, the substance, if a solid body, may be subjected first to 44 MANUAL OF CHEMICAL ANALYSIS. a preliminary examinatiou in the dry way, by which means approximate information as to its composition may be obtained ; after this, it is dissolved and examined. The course of qualitative analysis, therefore, consists of three parts :— I. Preliminary examination in the dry way. II. Solution, or conversion into the liquid form. III. Analysis of the solution. I. PRELIMINARY EXAMINATION. This consists in an accurate observation, often by the aid of a lens or a microscope, of the physical properties of the substance, its form, color, hardness, gravity, and odor, and of its deportment at a high temperature, either alone, or in contact with some chemical compound which produces decomposition. Fig. 27. 1. The substance is heated in a dry narrow tube open AT BOTH ENDS (Fig. 27). (a) The substance remains unaltered; indicating absence of organic matter, of salts containing water of crystallization, and of volatile com- pounds. (5) Non-volatile organic substances car- bonize and blacken, evolving empyreu- matic, inflammable gases. (c) The substance fuses, expelling aqueous vapors, which condense in the cooler parts of the tube ; indicating salts with water of crystallization (these will generally re- solidify after the expulsion of the water), or decomposable hydrates, which often give off their water without fusing. The acid or alkaline reaction of the condensed vapors should be determined by means of litmus-paper. (o?) A change of color takes place ; zinc oxide assumes a yellow color while hot, which disappears again on cooling; mer- curic oxide shows a transitory brown coloration, followed by the sublimation of metallic mercury ; mercuric iodide sublimes with a yellow color ; chromates, and the oxides of lead and bismuth are colored brown. , (e) G-ases or fumes are evolved ; iodine or bromine vapors would indicate their respective compounds, and may be recognized by the violet or brownish-red color and characteristic odor of the vapor ; sulphur dioxide is often produced by the decomposition of sulphates; nitric peroxide arises from the decomposition of many nitrates, and is recognized by its brownish color and suftb- QUALITATIVE CHEMICAL ANALYSIS. 45 eating odor ; cyanogen is recognized by its odor, and would indi- cate such cyanogen compounds as are decomposable by beat (mercuric cyanide); ammonia vapors may arise either from the decomposition of ammonium salts, cyanogen compounds, or from nitrogenous organic compounds ; in the latter case carbonization takes place, and either cyanogen or empyreumatic fumes escape with the ammonia. (/) Sublimates are formed by volatile substances, such as sul- phur, ammonium salts, compounds of mercury, arsenic, and anti- mony, and some organic acids (benzoic, succinic, oxalic, salicylic, etc.). Sulphur sublimes in reddish-brown drops, which, upon cooling, assume a yellow or yellowish -brown color; metallic mercury forms globules, which are sometimes only distinguish- able by the aid of a lens; mercuric chloride melts before volatil- izing, and mercurous chloride sublimes without previously melt- ing ; when touched with a solution of potassium hydrate the sublimate assumes a yellow color with mercuric, a black one with mercurous salt ; metallic arsenic forms the well-known mirror, arsenious acid small octahedral crystals, and the sulphides of arsenic a reddish-yellow, or, when cold, yellow sublimate ; anti- monious oxide melts first to a yellow liquid, and then sublimes in bright, shining needles. 2. The substance is mixed with soda-lime, and heated in A DRY GLASS TUBE (Fig. 28). The development of ammonia vapors will indicate ammonium salts, or nitrogenous compounds. Fig. 38. 46 MANUAL OF CHEMICAL ANALYSIS. 3. The substance is mixed with deied sodium caebonate, and heated on chaecoal in the seducing flame of THE BLOWPIPE (Fig. 29). (a) Fusion and absorption into tlie coal indicate alkalies, or their salts. (b) An infusible white residue, either at once or after previous fusion in the water of crystallization, indicates compounds of calcium, barium, strontium. Fig. 29. magnesium, aluminium, zinc, or tin. (c) A reduction to the me- tallic state takes place, with- out formation of a periph- eric incrustation upon the charcoal. Compounds of tin, silver, and copper, give malleable shining scales. Compounds of iron, man- ganese, cobalt, and nickel, are reduced to a gray in- fusible powder; all visible upon cutting the fuse from the coal, and triturating and levigating it in an agate mortar (Fig. 30). KiG. 30. (d) Reduction with incrustation : Antimony compounds give a brittle metallic globule and a white incrustation ; bismuth, a brittle globule and a brown-yellow incrustation ; lead, a mallea- ble globule and a yellow incrustation ; zinc and cadmium are not reduced, but give, the former, a white incrustation, not volatile in the oxidizing flame, the latter, a brown-red incrustation. (e) Arsenic compounds evolve the smell of garlic. (/) Borax and alum intumesce, and lose their water of crystal- lization. {g) All sulphur compounds give an alkaline sulphide, which, when moistened upon a clean silver plate, produces a black stain, and with acids develops hydrogen sulphide. QUALITATIVK CHEMICAL ANALYSIS. 47 (h) If deflagration takes place, nitrates, chlorates, iodates, or bromates are indicated. 4. The substance, contained on the looped end of a mounted platinum wire (fig. 31), is heated in the upper reducing portion of the non-luminous gas FLAME. («) A violet color imparted to the flame indicates potassium salts. As this reaction may be perfectly concealed by the pre- sence of sodium salts, the flame should be observed through blue glass.* Fig. 31. (5) A yellow color imparted to the flame indicates sodium salts. (c) The substance is moistened with hydrochloric acid, and the color of the flame observed ; a purplish-red color indicates stron- tium, a carmine-red, lithium, and a yellowish-red color, calcium salts ; a green coloration indicates either copper or barium salts, more evident with the former than with the latter. (d) The substance is first heated to deprive it of moisture, then moistened with a drop of strong sulphuric acid, and the color of the flame observed ; a green coloration may indicate phosphoric or boric acid, which, however, particularly when sodium com- pounds are present, is only of transient duration. (e) A blue coloration imparted to the flame may indicate ar- senic, antimony, or lead compounds. 5. A SMALL AMOUNT OF POWDERED BORAX IS MELTED ON THE LOOPED END OF A PLATINUM WIRE, BROUGHT IN CONTACT WITH A TRACE OF THE SUBSTANCE TO BE TESTED, AND HEATED : (a) In the outer blowpipe flame, or in the lower oxidizing por- tion of the non-luminous gas flame. A blue glass or bead indicates cobalt. An amethyst- red colored glass indicates manganese. A green glass indicates chromium or copper (the copper bead becomes blue on cooling, the chromium bead yellowish-green). A brown-red glass indicates nickel or iron (the iron bead, when cold, is often of a yellowish color). A vellow glass indicates uranium or lead. 1 The blue glass, wLich is tinted with cobalt monoxide, possesses tlie pro- pertj' of absorbing tlie yellow rnj's of light, and permits only the blue and violet rays of the spectrum to pass through it. 48 MANUAL OF CHEMICAL ANALYSIS. A colorless glass indicates molybdic acid, tin, antimony, and bismuth, as also the alkaline earths ; the latter, however, be- coming opaque on cooling. (b) In the inner blowpipe flame, or in the lower reducing por- tion of the non-luminous gas-flame. A blue glass indicates cobalt. A yellow or brownish-red glass indicates copper or molybde- num. A green glass indicates chromium, iron, or uranium. A gray glass indicates nickel, bismuth, silver, or antimony. A colorless glass indicates manganese, as also the alkaline earths ; the latter showing the same behavior in both the re- ducing and the oxidizing flames. The operation of reduction is usually more easily accomplished by the use of phosphorous salt, instead of borax ; the former pro- ducing in the oxidizing flame with the oxides of manganese, cobalt, chromium, copper, iron, nickel, antimonj'', and molybde- num, and in the reducing flame with the oxides of cobalt, iron, uranium, chromium, copper, bismuth, and silver, the same results as with borax ; the oxides of bismuth and silver, however, yield a yellow colored glass. With either phosphorous salt or borax, and heated in the oxidizing or reducing portion of the flame, silica and silicates produce a skeleton in the bead. II. SOLUTION OF SOLID BODIES. « After having ascertained, by the preliminary examination, to what class of bodies the substance under consideration belongs, it has then to be brought into the liquid form — in other words, to be dissolved. The usual solvents which are employed are water, hydrochloric, nitric, and nitro-hydrochloric acids. The finely pow- dered substance is first boiled with from 12 to 20 times its weight of distilled water, in order to ascertain its complete or partial solubility, or its insolubility therein. If it be not completely dis- solved, the portion insoluble in water is collected upon a filter, and is then treated successively with dilute and concentrated hydro- chloric acid ; by this process carbonates evolve carbonic-acid gas, with effervescence ; peroxides, chromates, and chlorates, evolve chlorine ; cyanides give hydrocyanic acid ; many sulphides, hy- drogen sulphide ; sulphites and hyposulphites, sulphurous acid. If hydrochloric acid does not completely dissolve the substance, it generally effects the separation of one or more of its constitu- ents ; for this reason the solution should be separated from the residue and examined apart. The residue may consist of com- pounds undecomposable by hydrochloric acid, which existed in the original substance ; or of insoluble compounds formed by the decomposition of the original substance by hydrochloric acid. Thus sulphur is separated from polysulphides, and pulverulent or gelatinous silica from silicates ; or, if lead, silver, or mercurous QUALITATIVE CHEMICAL ANALYSIS. 49 salts be present, insoluble chlorides of these metals will be formed. In this latter case, argentic chloride may be distinguished by its solubility in ammonia water, and mercurous chloride by its con- version by ammonia into the gray colored dimercurous ammo- nium chloride, or its reduction by potassium or sodium hydrate to black mercurous oxide ; while plumbic chloride is characterized by its solubility in hot water, from which it separates in a crys- talline form on cooling. If the substance is not completely soluble in hydrochloric acid, the insoluble residue is treated successively with nitric and nitro- hydrochloric acids, which either act as mere solvents or exert an oxidizing action. When a finely powdered substance is not dissolved by succes- sive treatment with either of these solvents, it must be rendered soluble by other means, in order that its constituents may be de- termined. This is generally accomplished by fusion with 3 to 4. parts by weight of alkaline carbonates, in the case of the sulphates of barium, strontium, calcium, and lead, and also of silica and sili- cates, or by fusion with acid potassium sulphate in the case of alumina or aluminates. In the process of fusion with alkaline carbonates, as above described, in cases where arsenic or an easily reducible metal (antimony, tin, lead, bismuth, etc.) is present, the application of platinum crucibles should be avoided (see note on page 23). III. QUALITATIVE ANALYSIS OP SOLUTIONS. I. Examination for Bases. In the systematic course of examination for metals, now gen- erally employed, use is made of the analogy in physical and chemical properties, and especially in the solubilities of certain classes of compounds; the reagents which give rise to the forma- tion of these compounds are : hydrochloric acid, hydrogen sul- phide, ammonium sulphide, ammonium carbonate, and ammonium phosphate. Their application depends upon the different solubility and insolubility of metallic chlorides and sulphides, and of the carbonates or phosphates of the alkaline-earthy and alkali metals. By means of these general reagents, the metallic compounds are divided into several groups, and are successively eliminated from their solutions, wherebj' the detection of each individual member of such groups is considerably facilitated. Group I. Metals whose chlorides are insohihle, or nearly so, in'ivater and dilute acids : MeTcu'rous salts, white; ["""^Pletely precipitated. Lead, white, incompletely precipitated. 4 60 MANUAL OF CnExMICAL ANALYSIS. Group II. Metals whose sulphides are insoluble, or nearly so, in water and dilute acids : They are all precipitated from their acid solutions by hydrogen sulphide. They are divided into two subdivisions according to their deportment with ammonium sulpbide. A. Metals whose sulphides are sulpho-acids, forming witb sul- pho-bases, soluble sulpho-salts : Antimony, orange. Molybdenum, black-brown. Arsenic, yellow. Gold, black-brown. Stannous salts, brown. Platinum, black- brown. Stannic salts, yellow. B. Metals whose sulphides do not possess acid properties, not combining with, and therefore insoluble in, alkaline sulphides : Lead, black. Copper, black. Mercuric salts,' black. Cadmium, yellow. Bismuth, black-brown. Palladium, black. Group III. Metals whose sulphides form, soluble sulpho-salts, which conse- quently are not precipitated by hydrogen sulphide from neutral or acid, but partially from alkaline solutions ; which, however, are completely precipitated by ammonium sulphide from neutral as well as from alkaline solutions. These are, again, subdivided into two groups : A. Metals which are precipitated as sulphides : Zinc, white. Nickel, black. Iron, black. Uranium, black-brown. Manganese, flesh-colored. Thallium, black. Cobalt, black. Indium, yellow. B. Metals which are precipitated as hydrates : Aluminium, colorless andtrans- Chromium, grayish-green. parent. Cerium, white. The oxalates, phosphates, and borates of barium, calcium, stron- tium, and magnesium, being soluble in dilute acids and insoluble in water, are similarly precipitated by ammonium sulphide. Group IV. Metals whose sulphides and hydrates are soluble in water ; and which, therefore, are not precipitated by hydrogen sulphide nor by ammonium sulphide. These are subdivided according to their deportment with ammonium carbonate in the presence of ammo- nium chloride. A. Metals whose normal carbonates are insoluble in water or in solution of ammonium chloride: Barium, Calcium, Strontium. ' Mercuric sulphide is slightly soluble in potassium sulphide, and cupric sul- phide in ammonium sulphide. QUALITATIVE CHEMICAL ANALYSIS. 51 B. Metals whose carbonates are soluble in water or in solution of ammonium chloride: Magnesium, Potassium, Sodium, Lithium, Ammonium. "When entering upon the examination of a solution, the results of the preliminary examination should be taken into due consid- eration, as they often will indicate the number and kind of bases present. If thea a precipitate is caused by one of the general reagents, the solution should be examined for every member of that particular group. It is also evident that when the presence of one or several bases has been ascertained, the systematic and successive course of examination, as described hereafter, should be pursued, so as to exclude beyond doubt the presence of any not-detected metal. The precipitation by each general reagent must be complete. To insure this, they must be employed in the order above stated, and must be added gradually, allowing the precipitate to subside between each addition, until no further precipitate is produced. In the case of hydrogen sulphide, the precipitation is complete when the solution, after agitation, still smells strongly of the gas. Gentle heat generally facilitates the separation of precipitates. Bach group, when precipitated, must be thoroughly freed, by washing with water, from all members of the subsequent groups, which may be contained in the solution. After the precipitation of each group, it is advisable to ascertain the presence or absence of any members of the succeeding groups, by evaporating on platinum-foil a few drops of the filtrate; if, after ignition, there is no distinctly visible residue, non-volatile substances need not be looked for further. It is obvious that, if complete precipita- tion and thorough washing be neglected, metals belonging to one group are liable to be found among those of another group ; and, consequently, as the analysis proceeds, reactions will be obtained which will be a source of perplexity and errors. Hereupon the following course of analysis may be pursued, involving the systematic investigation of the several groups : Group I, A portion of the solution is acidulated with hydrochloric acid. An ensuing precipitate, which may be marked No. 1, would indi- cate lead, silver, or mercurous chlorides. In this case the pre- cipitate is collected on a filter, washed and subsequently boiled with water, and the solution filtered while hot. Lead chloride is soluble in hot water, and can be precipitated from its solution as yellow lead chromate on the addition of po- tassium chromate. Silver and mercurous chlorides are insoluble in water ; the former, however, is readily soluble in ammonia SS MANUAL OF CHEMICAL ANALYSIS. ■water, from which solution it is again precipitated on the addition of an excess of nitric acid, whilst mercurous chloride in contact with ammonia is colored black. Group II. The liquid, acidulated with hydrochloric acid, or, if a precip- itate was produced by the latter, the filtrate therefrom, is satu- rated with hydrogen sulphide. If no precipi^tate ensues, the reagents indicated in the next following group may at once be employed ; if, however, a precipitate has been formed, indicating bases of group II , this is collected on a filter, well washed with water, and the filtrate and washings, which may be marked Filtrate Wo. 2, reserved for further examination. The precipi- tate, which may be marked No. 2, is then examined as follows: If it is of a light yellowish-white color, it may consist simply of sulphur, which may be recognized by its volatility when heated in a small glass tube, or by the formation of an alkaline sulphide when heated with a little exsiccated sodium carbonate on char- coal, before the blow-pipe. The precipitation of sulphur results from the presence of ferric salts, chromic acid, or chromates ; in the first case, the ferric is reduced to ferrous salt, and in the latter, the chromic acid to chromic oxide, which imparts a green color to the solution. When considerable free nitric acid is present in a solution, sulphur may also be precipitated by the decomposition of hydrogen sulphide. A yellow precipitate is produced when arsenious or arsenic acid, stannic acid, or cadmium salts are present in the solution. If arsenic is present in the form of arsenic acid, the solution must be heated before or during the time of saturation with the gas, and subsequently allowed to stand for a few hours in a closed flask or test-tube, in order to insure its complete precipitation. An oronc/e-colored precipitate is produced when antimony is present. A brown precipitate is produced by stannous salts, and the salts of bismuth and molybdenum. A black or blackish-brown precipitate is produced by mercuric salts, lead, copper, gold, platinum, and palladium, as also by silver and mercurous salts, in case the two latter were previously not completely precipitated by hydrochloric acid. It is evident that when several metals precipitable by hydrogen sulphide are present, the color of the precipitate will be unavail- able as a criterion for the recognition of any one substance. The metallic sulphides precipitated by hydrogen sulphide are distinguished by their deportment with ammonium sulphide, being soluble or insoluble therein, and may thus be resolved into two classes. The precipitate JSTo. 2, collected upon a filter and well washed QUALtTATIVE CHEMICAL ANALYSIS. 53 with water, is digested with ammonium sulphide, by the aid of a gentle heat, and filtered. The solution may be marked A, and any insoluble residue upon the filter, B. The obtained solution A contains those metals whose sulphides are sulpho-acids, combining with alkaline sulphides or sulphy- drates to form soluble sulpho-salts. These are: arsenic, antimony, tin, molybdenum, gold, and platinum. In order to effect their separation, several methods may be employed, only one of which, however, need be here described. The solution A is acidulated with dilute sulphuric acid, and the resulting precipitate (if not consisting only of sulphur) very slightly warmed with a concentrated solution of ammonium car- bonate. Arsenic is thereby dissolved, and, upon supersaturating the solution with hydrochloric acid, and warming, is reprecipi- tated as arsenious sulphide, and may then be reduced to the metallic state by heating in a small glass tube with a mixture of potassium cyanide and exsiccated sodium carbonate (Fig. 32), or Fig. 32. it may be dissolved by gently heating with hydrochloric acid and a little potassium chlorate, when upon the subsequent addition of test magnesium mixture, a white crystalline precipitate of ammo- nio-magnesium arseniate will be obtained. Traces of arsenic may be more readily detected, after the above treatment, by examining the solution in Marsh's apparatus (Fig. 33), as described on pages 83 to 36. The portion undissolved by ammonium carbonate is dissolved in hydrochloric acid, with the addition of a small amount of potas- sium chlorate, and gently heating, and the solution thus obtained tested as follows : A few drops are brought upon platinum-foil, 5J: MANUAL OF CHEMICAL ANALYSIS. together witb a fragment of metallic zinc, when, if antimony is present, a deep black spot will be produced upon the foil, or the solution when brought into Marsh's apparatus, will develop hy- drogen antimonide, which may be recognized by the method de- FiG. 33. scribed on page 35. Another portion of the solution is warmed with metallic zinc, when tin will be precipitated as a black me- tallic powder, soluble in warm hydrochloric acid, and producing upon the subsequent addition of solution of mercuric chloride a white or gray-colored precipitate. Molybdenum may be best detected by the tests of the preliminary examination, as described on page 48. Gold may be recognized by the brown precipitate of finely divided metal on the addition of ferrous sulphate to the original slightly acid solutition. Platinum is detected by the addition of a little ammonium chloride to the original, slightly acid solution, evaporating nearly to dryness, and treating with strong alcohol ; a yellow, crystalline precipitate, consisting of the double chloride of platinum and ammonium, and reducible by heating to black metallic platinum, will thus be formed. The portion of the hydrogen sulphide precipitate B, insoluble in ammonium sulphide, contains those metals whose sulphides do not possess acid properties, not combining with, and therefore insoluble in, alkaline sulphides or sulphydrates. These are: lead, bismuth, copper, cadmium, and mercuric salts, also mercurous salts and silver, in case nitric instead of hydrochloric acid was employed for acidulating the original solution, before precipi- QUALITATIVE CHEMICAL ANALYSIS. 55 tatiug with hydrogen sulphide. The precipitate B is washed, subsequently treated upon the filter with concentrated nitric acid, and the filtrate examined as follows : (1) Portion soluble in nitric acid. Lead, which can be present in but small amount if the original solution was acidulated with hydrochloric acid, as described under group I. page 51, may be detected by neutralizing the solution with ammonia water, evaporating to a small volume, and acidu- lating with sulphuric acid ; a white precipitate will thus be pro- duced, which is soluble in basic ammonium tartrate, and may be again precipitated from this solution on the addition of potassium chromate. The latter precipitate, when mixed with exsiccated sodium carbonate, and heated upon charcoal, yields a soft me- tallic bead. Silver can oiily be present when hydrochloric acid was not employed for acidulating the original solution, as directed under group I. page 51. It may be detected in the filtrate from the just-mentioned lead sulphate precipitate by the addition of hydro- chloric acid, when a white curdy precipitate, sol able in ammonia water, will be produced. Bismuth may be detected in the filtrate from the preceding silver precipitate by tiie addition of ammonia water, when a white precipitate, insoluble in an excess of the reagent, will be formed. The solution of the precipitate in a small amount of hydrochloric acid, becomes turbid on the addition of much water. Copper is recognized when the filtrate from the preceding bis- muth solution possesses a blue color, and, after acidulating with hj'drochloric acid, by a reddish-brown precipitate on the addition of solution of potassium ferrocyanide. Cadmium may be recognized, when the solution of the preceding test remains colorless upon the addition of ammonia water, by a yellow precipitate upon saturation with hydrogen sulphide. If, however, both copper and cadmium are present in the solution, then the ammouiacal liquid from the above-mentioned bismuth precipitate is supersaturated with hydrochloric acid, the solution concentrated by evaporation, and ammonium carbonate in excess added, when cadmium will be separated as a white precipitate, whilst copper, remaining dissolved, imparts a blue color to the liquid. The separation may also be effected by adding potas- sium cyanide to the ammoniacal liquid from the bismuth pre- cipitate until the solution appears colorless; upon subsequent saturation with hydrogen sulphide cadmium will be precipitated as yellow cadmium sulphide, while copper remains in solution. Palladium may be .detected in the original solution of the sub- stance under examination by the formation of a black precipitate on the addition of solution of potassium iodide. (2) The portion of precipitate B insoluble in nitric acid may consist of sulphur, which is recognized by its yellowish or gray • 56 MANUAL OF CHEMICAL ANALYSIS. ish-yellow color,* as also by its complete volatilization when heated in a small glass tube, or the formation of an alkaline sul- phide, when heated with exsiccated sodium carbonate on charcoal, before the blow-pipe. Lead sulphate forms a heavy, white pre- cipitate, and results from the action of the nitric acid on the lead sulphide. In this case lead will usually be found aud recognized also in that portion of the precipitate B which is soluble in nitric acid, page 55. Mercury, in the form of mercuric salt, is recognized as a black, flocculent precipitate, which, when mixed with sodium carbonate, and heated in a glass tube, yields a sublimate of metallic mercury. Lead sulphate may be separated from mercuric sulphide by digest- ing with a solution of basic ammonium tartrate, in which lead sulphate is soluble, and may be subsequently recognized by a black precipitate with hydrogen sulphide, or a yellow one with potas- sium chromate. The washed mercuric sulphide may be dissolved in nitro-hydrochloric acid, the excess of acid removed by evapora- tion, and the solution tested, either with stannous chloride, which will produce a white precipitate, or by immersing a piece of bright copper foil in the liquid, when a coating of metallic mercury will be deposited. Group III. Filtrate No. 2, page 52, is supersaturated with ammonia water, and ammonium sulphide added, in an amount sufficient to effect complete precipitation, if any reaction is produced. If no precipi- tate is formed by the addition of these reagents, the solution may be further examined as directed under group IV., page 59. If, however, a precipitate is produced, it is collected on a lilter, well washed with water, and the filtrate, which may be marked Wo. 3, reserved for the examination of the bases of group IV. This pre- cipitate, marked No. 3, may contain iron, nickel, cobalt, manga- nese, zinc, uranium, chromium, and aluminium, as also calcium, barium, and strontium oxalates and phosphates and magnesium phosphate. A bi'own color of the filtrate from precipitate No. 3 would indicate the presence of nickel. A hlaclc precipitate will indicate iron, cobalt, nickel, uranium, or one or all of these combined with other members of the group. A greenish precipitate will indicate chromium. A ^es/i-cofo?^ precipitate will indicate manganese. A white precipitate is dependent in its character as to whether the original substance was soluble in water, or whether in order to effect its solution the aid of an acid was required. In the former case, it may consist of zinc or aluminium, either alone, or combined with manganese and chromium ; in the latter case it 1 The sulplnir frequently incloses particles of mercuric sulphide, which im- parts to it a brown color. QUALITATIVE CHEMICAL ANALYSIS. 57 may also contain magnesium, barium, calcium, or strontium, in combination with phosphoric or oxalic acids. Precipitate No. 3 (page 56) is examined as follows : (a) It is first digested wnth cold, dilute hydrochloric acid. This dissolves all the oxides and sulphides of the group, with the exception of the sulphides of cobalt and nickel, which, if present, are separately examined as directed under (c). The acid solution or filtrate thus obtained is first heated, in order to remove the hydrogen sulphide, filtered, and solution of sodium hydrate, in con- siderable excess, added. If a precipitate is formed, it is examined as directed under (b), whilst the alkaline solution or filtrate is examined as follows: It is first boiled for some time, when chro- minm will be precipitated ; its identity may be confirmed by fusing it, on platinum-foil, with an equal weight of exsiccated sodium carbonate and potassium nitrate, dissolving the fused mass in water, and, after acidulating with acetic acid, testing with plumbic acetate, when a yellow precipitate will be produced. A portion of the filtrate from the first chromium precipitate is then satu- rated with hydrogen sulphide, when an ensuing white precipitate will indicate zinc; this may be confirmed by moistening part of the precipitate, on the looped end of a platinum-wire, with a drop of solution of cobaltous nitrate, and heating in the non-luminous flame, when a green color will be imparted to the bead. If the hydrogen sulphide has produced no precipitate in the alkaline solution, then another portion of the latter is supersaturated with hydrochloric acid, and subsequently made slightly alkaline with ammonia water, when an ensuing transparent, flocculent precipi- tate will indicate aluminium; this may be confirmed by moisten- ing the precipitate, on the looped end of a platinum- wire, with a drop of solution of cobaltous nitrate, and heating in the non-lumi- nous flame, when a blue color will be imparted to the bead. (b) The precipitate, undissolved by solution of sodium hydrate, as directed under (a), may contain the oxides or hydrates of iron, manganese, and uranium, the phosphates and oxalates of the alka- line earths, calcium fluoride, and possibly traces of zinc. It is redissolved in dilute hydrochloric acid, ammonium chloride added, and subsequently ammonia water in slight excess. By this means the above-mentioned metals are again precipitated, with the excep- tion of manganese and zinc, which remain dissolved, and are separated as follows : From the ammoniacal solution the manga- nese and zinc are again precipitated by ammonium sulphide ; a portion of this precipitate is heated, on platinum -foil, with a mix- ture of potassium nitrate and exsiccated sodium carbonate, when a green color of the fused mass will indicate manganese ; the remaining portion of the precipitate is dissolved in hydrochloric acid, sodium acetate in excess added, and the solution subse- quently saturated with hydrogen sulphide, when an ensuing white precipitate will indicate zinc. 58 MANUAL OF CHEMICAL ANALYSIS. The precipitate, as above obtained by the addition of ammonium chloride and ammonia water, is digested with a concentrated solu- tion of ammonium carbonate, when uranium and cerium will be dissolved. Uranium is recognized by a brown precipitate on supersaturating the solution with hydrochloric acid, and the subsequent addition of potassium ferrocyanide. Cerium is recognized by the formation of a difficultly soluble double salt with potassium sulphate. The precipitate which remains undissolved by the above treatment with concentrated solution of ammonium carbonate, is dissolved in dilute hydro- chloric acid, and the solution tested, in separate portions, as follows : Iron is recognized by a blue precipitate on the addition of solu- tion of potassium ferrocyanide. Barium or strontium by a white precipitate on the addition of solution of calcium sulphate. Calcium by a white precipitate on the addition of sodium ace- tate, in slight excess, and solution of ammonium oxalate. Magnesium,— Sodium acetate, in slight excess, is added to the solution, and subsequently ferric chloride until a red coloration is produced. The liquid is then heated to boiling, filtered, and the filtrate completely precipitated by ammonium carbonate. The filtrate from the latter precipitate is finally tested with ammonium phosphate, when an ensuing white, crystalline precipitate will indicate magnesium. Phosphoric Acid is recognized by an ensuing white precipitate of ferric phosphate, when to the cold solution sodium acetate, in slight excess, and subsequently a few drops of solution of ferric chloride are added; or, if on the addition of solution of ammo- nium molybdate in nitric acid, and gently heating, a yellow, crys- talline precipitate is produced. Oxalic Acid, as calcium oxalate, is recognized, when on the addi- tion of sodium acetate, in slight excess, a white precipitate is formed, which is insoluble in acetic acid, and by ignition is con- verted into calcium carbonate. Fluorine, which may be present as calcium fluoride, must be tested for with the original substance, and may be recognized by the etching produced upon a glass plate, which is partially cov- ered with wax, and placed over a lead or platinum capsule in which a little of the substance is heated with concentrated sul- phuric acid. (c) The portion of the ammonium sulphide precipitate, insoluble in cold dilute hydrochloric acid, may consist, as stated under (a), of the sulphides of cobalt and nickel, or- simply of sulphur. If the latter alone is present, it may be recognized by its color, as also by its complete volatilization when heated on platinum-foil. The sulphides of cobalt and nickel are black, and may be sepa- QUALITATIVE CHEMICAL ANALYSIS. 59 rated by the following method : The precipitate is dissolved in nitro-hydrochloric acid, the solution evaporated, and the residue taken up with water containing a little acetic acid. To this solu- tion potassium nitrite in considerable quantity is added, and allowed to stand for several hours, when cobalt will be completely separated as a yellow, pulverulent double salt, whilst nickel re- mains in solution, and may be precipitated therefrom on the addition of sodium hydrate, as light green colored nickel hydrate. The metals thallium and indium, which also belong to this group, are of such rare occurrence that when their presence may be reasonably suspected they must be tested for by means of the spectroscope. Group IV. Filtrate No. 3, page 56, is supersaturated with hydrochloric acid, and heated until the odor of hydrogen sulphide has entirely disappeared; when cold, it is filtered, slightly supersaturated with ammonia water, and ammonium carbonate in slight excess added. If no precipitate is formed on the addition of these reagents, the solution may be further examined as directed under group V. If, however, a precipitate is obtained, it is collected and washed on a filter, and the filtrate therefrom, which may be marked Wo, 4, reserved for the examination of bases of group Y. The precipi- tate, marked Wo. 4, which may contain barium, calcium, or stron- tium,, is examined as follows : It is dissolved in dilute hydrochloric acid, and to a portion of the solution a saturated solution of cal- cium sulphate is added. If a precipitate is formed at once, it will indicate the presence of barium ; but if the precipitate is only formed after standing for some time, strontium is indicated, whilst if no turbidity is produced, only calcium can be present. In the latter case ammonia water, in slight excess, and ammonium oxalate are added to another portion of the dilute hydrochloric acid solu- tion, when, if calcium is present, a white precipitate of calcium oxalate will be produced. If calcium has thus been found to be present, the dilute hydrochloricacidsolutionfirstobtained is exactly neutralized with ammonia water, and solution of neutral potassium chromate added, when barium will be precipitated as yellow barium chromate. To the filtrate from the last-named precipitate dilute sulphuric acid is added, and allowed to stand for some time, when strontium will be precipitated as white strontium sulphate. The filtrate from the latter, on the addition of ammonia water, in slight excess, and afterward of ammonium oxalate, will yield a white precipitate of calcium oxalate. Group V. Filtrate No. 4, page 59, may still contain magnesium, sodium, potassium, lithium, and ammonium. 60 MANUAL OF CHEMICAL ANALYSIS. Magnesium is recognized by an ensuing white crystalline pre- cipitate of ammonio- magnesium phosphate on the addition of solution of ammonium phosphate. The methods employed for testing the filtrate for potassium, sodium, and lithium are subject to some variation in their appli- cation, and depend upon the previously determined presence or absence of magnesium. If the solution contains no magnesium, it may be evaporated to dryness, the residue ignited to expel ammonium salts, and the final residue dissolved in a small amount of water. It is then examined on platinum-wire in the non- luminous flame, to which sodium imparts a yellow, potassium a violet, and litMum a carmine-red color ; the detection of potassium in the presence of sodium being effected by observing the flame, through blue cobalt glass. For the verification of potassium the remainder of the solution may be tested with a few drops of pla- tinic chloride; a yellow crystalline precipitate of potassio-platinic chloride will be formed, if potassium be present. For the special detection of lithium, the dry mixture of the chlorides is digested with a mixture of about equal parts of alco- hol and ether, filtered, and the filtrate allowed to evaporate spon- taneously ; the residue from the alcohol-ether solution will contain all the lithium, which may be recognized when examined on platinum-wire in the non-luminous flame. If, however, magnesium has been found to be present, it has to be first removed before potassium, sodium, and lithium can be tested for. The solution is accordingly evaporated to dryness, ignited to expel ammonium salts, and the residue taken up with water. To the filtered liquid, solution of barium hydrate is added until alkaline to test-paper, again filtered, and the excess of barium in the filtrate removed by solution of ammonium carbonate to which a little ammonia water has been added. The filtrate from the latter precipitate is evaporated to dryness, gently ignited, and the residue tested for potassium, sodium, and lithium as above described. In case lithium is absent, the filtrate from the above- mentioned ammonio-magnesium phosphate precipitate may be directly employed for the ordinary flame tests for potassium and sodium. Ammonium is always sought for in a separate portion of the original substance or solution, by heating with a concentrated solution of potassium or sodium hydrate ; any ammonium com- pound evolves the characteristic odor of ammonia gas, which changes moistened red litmus-paper to blue, and produces white fumes when a glass rod, moistened with acetic acid, is held over the orifice of the test-tube. Minute traces of ammonia may be detected by conducting the vapors into a test-tube containing a small quantity of distilled water ; if ammonia be present a brown precipitate will then be QUALITATIVE CHEMICAL ANALYSIS. 61 produced on the addition of a few drops of solution of potassio- mercuric iodide with potassium hydrate (Nessler's reagent). II. Examination for Acids. The examination for the bases is followed by that for the acids and for chlorine, iodine, and bromine. The preliminary examination, as well as the nature of the substance and the bases found therein, will give information, in most cases, as to what acids cannot be contained in the substance, and what acids may be present therein, or should especially be looked for. Thus the acids of arsenic, chromic and carbonic acids, and hydrogen sulphide, have already been indicated. With soluble substances containing earthy and metallic bases, the presence of carbonic, phosphoric, boric, and oxalic acids, is excluded ; soluble substances, containing silver, lead, and mercurous compounds, exclude chlorine ; soluble sub- stances, containing lead, barium, strontium, and mercurous salts, exclude sulphuric acid. In the examination for acids, a neutral solution is frequently required, and generally ammonia water is used for neutralization ; but, as most of the heavy metals, as well as some alkaline earthy salts, are precipitated when their solutions are neutralized by ammonia water, it is often necessary to remove from the solution all metals, exce|)t those of the alkalies, before proceeding to search for acids. When this is not necessary, it is frequently requisite, according to the nature of the substance and its chemical rela- tions, to substitute, instead of hydrochloric acid and its salts, nitric acid and the corresponding nitrates. The general reagents employed in the examination for acids are barium chloride or nitrate, calcium chloride, magnesium sulphate or chloride, ferric chloride, argentic nitrate, and indigo solution. By these reagents the more commonly occurring acids may be divided, analogously to the bases, into certain groups, but, unlike the latter, the perfect separation of the individual acids embraced in the different groups cannot thus be effected. I. Acids which are precipitated hy barium chloride or nitrate. (a) From acidulated solutions: sulphuric acid as a white pre- cipitate, insoluble in nitric or hydrochloric acids. ih) From neutral solutions (the precipitate being soluble in acids) : sulphurous, phosphorous, phosphoric, carbonic, silicic, boric, arsenious, and arsenic acids, as white precipitates, and chromic acid as a yellow one, all soluble, in hydrochloric acid. Of the organic acids, oxalic and tartaric also produce white precipitates, but only from more concentrated solutions, and likewise soluble in hydrochloric acid. 62 MANUAL OF CHEMICAL ANALYSIS. II. Acids which are precipitated hy calcium chloride. (a) From neutral solutions only: phosphoric, arsenic, and ioric acids as white precipitates, which are readily soluble in ammo- nium chloride; carbonic and sulphurous acids, as white precipitates, but the latter one only in concentrated solutions ; tartaric acid, as a white precipitate, soluble in ammonium chloride or potassium hydrate, which alkaline solution becomes turbid on heating ; citric acid gives a white precipitate, upon the subsequent addition of lime water or ammonia water in excess, and heating; ferrocyan- ides produce gradually a yellowish precipitate. All of the above precipitates are readily soluble in acetic acid, with the exception of that of ferrocyanides, which is difficultly soluble. (b) From neutral or acetic acid solutions : oxalic acid, as a white precipitate, insoluble in ammonium chloride; this precipitate is also formed with a saturated solution of calcium sulphate ; sul- phuric acid gives a white precipitate, except in very dilute solu- tions, when it is only produced on the subsequent addition of alco- hol ; hydrofluoric acid produces a white gelatinous precipitate, which has the property of etching a glass plate, placed over a lead or platinum capsule, in which the precipitate is gently heated with concentrated sulphuric acid. III. Acids which are precipitated ly magnesium sulphate or chloride in the presence of ammonium chloride and ammonia water. Phosphoric acid, as a white crystalline precipitate, which is slowly formed in very dilute solutions, and soluble in all acids ; arsenic acid yields a precipitate which is precisely analogous in its char- acter to that of phosphoric acid, but froni its acid solution, on warming, hydrogen sulphide precipitates yellow arsenic sulphide ; tartaric acid gradually yields a white precipitate in concentrated solutions, which becomes black on drying, and subsequent incin- eration upon platinum-foil. IV. Acids which are detected ly ferric chloride. (a) Those which are precipitated. (From neutral or acetic-acid solutions.) Ferrocyanides yield a blue precipitate, which is also produced in the presence of free hydrochloric acid ; phosphoric acid, a yel- lowish-white one, insoluble in acetic, but soluble in hydrochloric acid ; arsenic acid gives a precipitate which is analogous in its properties to phosphoric acid, but is also precipitated from its warm acidulated solution by hydrogen sulphide; tannic acid, a bluish-black precipitate, and the original solution is precipitated by gelatin. QUALITATIVE CHEMICAL ANALYSIS. 63 (From neutral solutions only.) Boric acid yields a yellowish precipitate ; benzoic and succinic acids, light brown ones; the latter is also precipitated by a mix- ture of ammonia water, barium -chloride, and alcohol. (J) Those uhich produce a coloration, hut no precipitate. (In the presence of free hydrochloric acid.) Ferricyanides produce a brownish coloration, and with ferrous salts a blue precipitate ; sulphocyaiiides, an intense blood-red coloration, which disappears on the addition of mercuric chloride. (In neutral solutions only.) Acetic acid, a reddish-brown coloration, and, on boiling, a red- dish-brown precipitate, whilst the solution becomes decolorized ; formic acid gives also a reddish-brown coloration, but the original solution reduces silver and mercury from a solution of their salts ; sulphurous acid, a reddish-brown coloration, which disappears on boiling the solution, without a precipitate being produced ; meco- nic acid, a blood-red coloration, remaining unchanged on the addition of solution of auric chloride ; gallic acid, a black colora- tion, but the original solution is not precipitated by gelatin ; salicylic acid produces a deep violet coloration. V. Acids which are precipitated hy argentic nitrate. (a) Only from neutral solutions (the precipitate being soluble in dilute nitric acid) : phosphoric acid (ortho) produces a yellow pre- cipitate, and is also precipitable by magnesium rmxtMre; pyrophos- phoric acid, a white precipitate ; metaphosphoric acid, likewise a white one, but the free acfd also coagulates albumen, which distinguishes it from the preceding ; phosphorus and hypophosphorus acids give white precipitates, which soon change to black ; carbonic acid, a white precipitate ; arsenic acid, a reddish-brown one, and is also precipitable by magnesium mixture, and from a warm acidulated solution by hydrogen sulphide ; arsenious acid, a yellow precipi- tate, and is also precipitable from an acid solution by hydrogen sulphide ; chromic acid, a brownish-red one, and the original yellow or red compound is changed by sulphurous acid to green ; boric acid gives a white precipitate, ahd, after the addition of sul- phuric acid to the compound, the alcohol flame is colored green; sulphurous acid, a white precipitate, becoming blackened on heat- ing ; hyposulphxirous acid, a white precipitate, soon changing to black, and soluble in an excess of a solution of the ensuing hypo- sulphite; oxalic acid, a white precipitate, insoluble in acetic acid; tartaric acid, a white precipitate, becoming black on heating ; citric acid, a white precipitate, changing to black by the action of 64 MANUAL OF CHEMICAL ANALYSIS. light ; formic acid, a white precipitate, becoming black on heat- ing; salicylic acid, a white precipitate; gallic and pyroyallic acids produce a separation of metallic silver; acetates and ienzoates, in concentrated solutions, produce white crystalline precipitates, soluble in hot water. {b) Also from acid solutions (the precipitate being insoluble in dilute nitric acid): hydrochloric acid produces a white curdy pre- cipitate, soluble in ammonia water and sodium hyposulphite ; hydrobromic acid, a white precipitate, and the original solution imparts a reddish-yellow color to carbon bisulphide, when agitated therewith after the addition of a little chlorine water; hydriodic acid, a yellowish precipitate, insoluble in ammonia water, and the original compound imparts a violet color to carbon bisulphide, or a blue color to mucilage of starch, when agitated therewith after the addition of a little chlorine water ; hydrocyanic acid, a white pre- cipitate, soluble in ammonia water and sodium hyposulphite, and the original compound, on the addition of a solution of potassium hydrate, a ferrous and ferric salt, and of hydrochloric acid in slight excess, produces a precipitate of Prussian blue; sulpho- cyanides, a white precipitate,. difficultly soluble in ammonia water, and the original solution produces with ferric chloride a blood- red coloration ; sulphides, a black precipitate, insoluble in ammo- nia water, which is also produced in solutions of lead and copper salts ; iodic acid, a white precipitate, soluble in ammonia water, from which solution sulphurous acid precipitates argentic iodide ; ferrocyanides, a white precipitate, insoluble in ammonia water, and the original compound gives with ferric salts a precipitate of Prussian blue ; ferricyanides, a reddish-brown precipitate, and the original solution gives with ferrous salts a deep blue precipitate. VI. Acids which decolorize indigo seliition. Free chlorine and bromine, and their oxygen acids, when free ; free nitric acid, if not too dilute, and alkaline sulphides. On the addition of sulphuric or hydrochloric acids, and heating, indigo solution is also decolorized by all chlorates, bromates, iddates, and nitrates, and, on the addition of hydrochloric acid and heating, besides all the foregoing acids, also by chromates, permanganates, and all peroxides. By the application of these group reagents the identity of many acids can often be determined; but, should this not be the case, the investigation may be further continued according to the fol- lowing method : The preliminary examination of the substance will have shown whether it be soluble in water, either alone or by the aid of an acid, or whether, in order to effect its solution, the process of fusion with an alkaline carbonate must be resorted to. According to this deportment of the substance towards sol- QUALITATIVE CHEMICAL ANALYSIS. 65 vents, the three following divisions may be made, which are also of service in defining the nature of the acid, and render its iden- tification possible. Many of the known acids, and particularly of the organic acids, being of rare occurrence, only those will be taken into consideration which are more commonly met with in analysis, or which are of practical importance. A. The substance is wholly or partially soluble in water. If a portion of the substance, when heated on platinum-foil, becomes blackened, or emits combustible vapors, organic acids should be sought for. Chromic, arsenic, and arsenious acids will already have been found in the examination for bases, groups 11. and ill. Carbonates and SulpMdes will be recognized by the de- velopment of gas bubbles when dilute hydrochloric acid is added to a portion of the liquid ; the former produces a white precipitate when the gas is led into lime-water, and the latter may be recog- nized by the odor, as also by the .blackening of a strip of paper, previously moistened with a solution of lead acetate, and placed in contact with the gas. Tannic, gallic, benzoic, succinic, and acetic acids, and ferrocyanides, may be detected by the addition of a little neutral ferric chloride to the solution, and discriminated from each other as indicated on pages 62 and 63. (a) A portion of the original solution is acidulated with hydro- chloric acid ; if this produces a precipitate, it is separated by filtration, and the filtrate is made sligttly alkaline with ammonia- water; iu case this should produce a precipitate, it is again fil- tered, and the filtrate finally tested ^^ith barium chloride. A precipitate with barium chloride will iSjJicate, in the absence of organic acids, either sulphuric, boric, phjpphoric, or silicic acids ; the precipitate with sulphuric acid is insoluble in nitric or hydro- chloric acids ; boric acid in the free state, or mixed with con- centrated sulphuric acid when in the fqrm of a salt, imparts a green color to the alcohol flame; phosphoric acid, in neutral solu- tions, gives with argentic nitrate a yellow precipitate, soluble in nitric acid or ammonia-water, and with magnesium mixture, a white crj^stalliue precipitate of ammonio-magnesium phosphate; very small amounts of phosphoric acid are detected by heating with a solution of amrnonium molybdate in dilute nitric acid, when a yellow crystalline precipitate will be instantly produced ; silicic acid and its salts, with the exception of those of the alkalies, are insoluble in water, and may be detected by evaporating a portion of the solution to dryness, and taking up the residue with water containing a little hydrochloric acid, when the silica will remain behind as an insoluble powder. If organic acids are pre- sent in the original solution, the precipitate produced by barium chloride may also indicate oxalic, tartaric, and citric acids, and these, in neutral solutions, likewise produce white precipitates 5 66 MANUAL OF CHEMICAL ANALYSIS. with argentic nitrate, which are soluble in ammonia-water and in nitric acid. They may be distinguished as follows: oxalic acid, x^pon the addition of lime-water in excess, yields at once a pre- cipitate, insoluble in acetic acid ; tartaric acid yields a precipitate, soluble in acetic acid ; citric acid affords no precipitate until the liquid is boiled, and the precipitate is soluble in acetic acid. Beside the acids already mentioned as producing precipitates with a neu- tral solution of barium chloride («), page 65, may be added chromic, carbonic, arsenious, and arsenic acids ; but, as previously stated, these acids would also be found in the examination for bases, and may thus be readily identitied. (b) A portion of the original solution is acidulated with nitric acid, and solution of argentic nitrate added, when a precipitate, insoluble in dilute nitric acid, will indicate hydrochloric, hydriodio, hydrobromio, and hydrocyanic acids, as also ferrocyanides, ferri- cyanides, sulphocyanides, and sulphides, all of which may be dis- tinguished from each other by the reactions given on page 64, V. (b). (c) A portion of the original solution is tinted faintly blue with indigo solution, and a little concentrated sulphuric acid added and heated. Ensuing decolorization will indicate nitric, chloric, or h3^0chlorous acids, as also free chlorine. Nitric acid may be readily detected by adding to the solution to be tested, contained in a test-tube, concentrated sulphuric acid, cooling the mixture, and then carefully pouring upon the surface of the liquid a solu- tion of ferrous sulphate, so as to form two distinct layers (Fig. 34) • a brown or violet coloration of the liquid, or a brownish colored zone at the point of contact of the two liquids will then be pro- duced ; chloric acid, besides being indicated, together with nitrates, QUALITATIVE CHEMICAL ANALYSIS. 67 in the preliminary examination, page 47, is also recognized in its salts by strongly heating, when it is reduced to chloride, and may then be tested by argentic nitrate. Of the more commonly occurring acids, only acetic, sulphurous, and hydrofluoric acids still remain ; these have already been men- tioned, and may be recognized by the distinctive tests of the preceding group reagents, as described on pages 61, 62, and 63. B. The substance is insoluble in water, hut -soluhle in acids. A portion of it is heated on platinum-foil, to ascertain the pre- sence or absence of organic acids. (a) The powdered substance is treated with nitric acid, and heated ; carbonic acid may be recognized by effervescence, and by the formation of a white precipitate when the evolved gas is led into lime-water; violet or brown vapors will indicate iodine and bromine, which may be recognized by a purple or yellowish color- ation of chloroform or carbon bisulphide, when shaken with a small part of the dilute nitric acid solution. (i) To a portion of the nitric acid solution, solution of argentic nitrate is added, when a white precipitate, insoluble in nitric acid but soluble in ammonia-water, will indicate hydrochloric acid. (c) A portion of the substance is boiled with a solution of potas- sium carbonate, and filtered ; a few drops of a solution of a ferrous and ferric salt are then added, and subsequently hydrochloric acid in slight excess, when a blue precipitate will indicate hydro- cyanic acid. (d) A portion of the substance is dissolved in hydrochloric acid, and solution of barium chloride added; a white precipitate, in- soluble in water, or in an excess of hydrochloric or nitric acids, will indicate sulphuric acid. (e) Boric, silicic, and hydrofluoric acids may be recognized in the preliminary examination, and by previous mentioned tests (pages 61, 62, and 65) ; phosphoric and oxalic acids, if in combination with alkaline earths, would have been found in the examination for bases, page 58; if combined with metallic oxides, they should be tested for in the liquid from which the bases precipitable by hydrogen sulphide and ammonium sulphide have been previously removed. (/) A portion of the substance is dissolved in hydrochloric acid, ammonia- water in slight excess added, and, in case a pre- cipitate is produced, filtered therefrom. Solution of calcium chloride is then added to the filtrate, when a precipitate, soluble in acetic acid or potassium hydrate, will indicate tartaric acid ; if the precipitate is formed only after boiling the solution, then citric acid is present ; if the precipitate produced in the cold solu- tion is insoluble in acetic acid, and also produced in the ammo- niacal solution by the addition of solution of calcium oxalate, then oxalic acid is present. 68 MANUAL OF CHEMICAL ANALYSIS. 0. The substance I's insohihle, or only partially soluble in acids. The substance, or portion of the substance, insoluble in acids, may be best brought into a condition suitable for further exami- nation by mixing it intimately with four parts of dry sodium carbonate, and fusing at a red heat. The fused mass, when cold, is boiled with water, and the solution filtered from the insoluble residue. To the solution nitric acid is added in slight excess; sulphides will be recognized by the odor of the developed gas, and by imparting a black stain to paper moistened with lead acetate. If a precipitate is produced by the addition of nitric acid, it may consist of silicic acid, and is collected upon a filter for further examination; in the latter case the solution may also contain some silica, and a portion of it is evaporated to dryness with strong hydrochloric acid, and the residue taken up with water acidulated with a little hydrochloric acid, when silica will remain behind as an insoluble powder. To a portion of the origi- nal solution, acidulated with nitric acid, solution of argentic nitrate is added, when a white precipitate, insoluble in excess of nitric acid, and soluble in ammonia-water, will indicate hydro- chloric acid ; the formation of a white precipitate on the addi- tion of barium chloride to the acidulated liquid will indicate sul- phuric acid. Boric and hydrofluoric acids may be recognized by previously indicated tests, pages 61 and 62 ; phosphoric acid is recognized on the addition of ammonium molybdate to the nitric acid solution, and gently heating, by the production of a yellow crystalline precipitate, insoluble in nitric acid, and soluble in ammonia-water; or by the yellow precipitate produced in the carefully neutralized solution on the addition of argentic nitrate, as also hj a white crystalline precipitate on the addition of magne- sium mixture. It should, however, be remembered that arsenic acid produces with ammonium molybdate, and magnesium sul- phate in ammoniacal solution, precipitates precisely analogous to those of phosphoric acid ; the arsenic acid may be readily recognized by its reaction with argentic nitrate, or by saturating the warm solution with hydrogen sulphide, when arsenious sulphide and sulphur will be precipitated. If the solution, as above obtained, by boiling the fused mass with water, shall have been found to contain nothing more than the excess of the applied sodium carbonate, then the entire fused mass maj' be treated with dilute nitric acid, and the solution thus obtained examined for the above-mentioned acids, in the manner already indicated. This outline of a systematic course of analysis, although neces- sarily open to modification in some of its details, such as may frequently be indicated by the results of the preliminary exami- nation, and of that for bases, will, it is believed, for those possess- QUALITATIVE CHEMICAL ANALYSIS. 69 ing ordinary cliemical knowledge, be found a reliable and trust- worthy guide, whenever recourse has to be taken to such a method in the examination and identification of medicinal chemicals, and the more commonly occurring chemicals used in medicine, and in the arts and trades. TABLE OF THE DEPORTMENT OF THE COMPOUNDS OF THE PRINCIPAL METALS WITH SOME OF THE GENERAL REAGENTS. Precipitable by Hydrogen Sulphide From Acid Solutions : As Sb Sn Mo Au Pt Pd Bi Ag Cu Pb Od. From Alkaline Solution!! : as Sulphides : as Hydrates : Fe Mn Co Ni Al Cr Ce. Zn Ur Tl In. Sulphides soluble in Nitric Acid : Nitro-TiydrocMorie Acid : Ammonium Sulphide : Pb Bi Cu Ag Cd Fe Hg Co Ni. As Sb Sn Mo Au Pt. Mn Zn Ur Tl In. Hydroehlorie Acid : Pb Ag Hg,0. Precipitable by Sulphuric Acid : Pb Hg Sb Sn Ba Ca Sr. Ammonia- Water : (soluble in excess) Zn Cu Cd Ni Co (insoluble in excess) Pb Bi Hg Fe Sn Sb Mn AlCr. Ammonium Carbonate: (in the presence of ammonium chloride) Ba Sr Ca. Bi Hg,0 Sn Sb. Potassium Hydrate : (insoluble in excess) Cu Cd Ni Co Bi Hg Fe Mn (soluble in excess) Pb Sn Sb Zn Al Cr (re-precipitated by boiling) ZnCr. VOLUMETRIC ANALYSIS. Fig. 35. The quantitative estimation of a number of medicinal chemi- cals and their preparations has been much simplified in practice by the volumetric method of chemical examination, which is based upon the fact that chemical substances combine in definite and equivalent proportions, and consists in noting the volume of a test-solution of known strength, required to produce by chemical reaction a certain visible effect when added to a known quantity of the substance under examination. On obtaining this effect, the quantity of the reagent being ascertained, and that of the substance being already known, an accurate estimate may readily be made by equation and simple calcula- tion. By the aid of this simple and rapid mode of examination, the proportion of the constituents of many chemical com- pounds and their preparations may be at once quantitatively estimated. In the fol- lowing part of this volume, in treating of all those chemicals and preparations in which a quantitative determination of the principal constituents is required, and to which the volumetric mode of examina- tion is best suited, either alone or as a confirmatory test, reference has frequently been made to these pages in explanation of the processes involved ; and in connec- tion with which, for many substances, is also stated the quantity of the volumetric test solution requisite to produce, with a definite weight of the substance under ex- amination, in direct relation or correspond- ing to its molecular weight, the exact re- action indicative of its officinal strength. In treating of the vari- ous chemicals in the following pages of this volume, where special volumetric methods of analysis are indicated for their examina- tion, or when for those methods here given a more detailed descrip- VOLUMETRIC ANALYSIS. 71 tion of the process may be considered necessary or desirabla, the method of procedure will in all cases be fully explained. The apparatus required for volumetric analysis consists, besides the common utensils, as beakers, funnels, porcelain-capsules, cru- cibles, stirring-rods, balances, etc., of one or several liter-flasks for the preparation of the test-solutions (Fig. 35) ; these, when filled to a mark on the neck, have mostly a capacity of 1000 cubic centimeters (1 liter) of distilled water at the temperature of 15° C. (59° F.) ; some cylindrical graduated liter-jars (Figs. 36 and 37), Fig. 36. Fig. 37. divided into 100 or 1000 centimeter-parts, and used for the pre- paration of test-solutions as well as for the admixture of parts of a liter ; and one or several graduated tubes for the delivery and measurement of the test-sohitions ; pipettes and burettes. The pipettes (Figs. 38, 39, and 40) are provided either with a 72 MANUAL OF CHEMICAL ANALYSIS. single mark upon the narrow neck, or are graduated into a num- ber of cubic centimeters, or parts thereof, and have a capacity varying from 1 to 50, 100, or more cubic centimeters. Fig. 38. Fig. 39. , Fig. 40. 10 CC r iC.C. In using pipettes, they are filled by placing the mouth directly on the upper end of the tube, or preferably by connecting a small piece of rubber tubing, and then by suction drawing the liquid into the tube until it rises slightly above the mark on the neck ; it is then closed above by the forefinger of the right hand (Fig. 40), or by compression of the rubber tubing, and the liquid allowed to flow out until its surface exactly coincides with the mark on the neck of the tube ; by a more or less gentle displace- ment of the finger, the whole or a portion of the contents of the pipette may then be delivered. VOLUMETRIC ANALYSIS. 73 Burettes are preferable for delivery and measurement, and are now quite universally employed; they hold to a certain mark 100 or less cubic centimeters, and are divided by graduation into a corresponding number of equal parts. There are three kinds of burettes inuse, which differ mainly in their construction for deliv- ery : Mohr's burette. Gay Lussac's burette, and Geissler's burette. Of these, Mohr's burette (Figs. 41 and 42), on account of its cheapness, simplicity, and convenience, is now in general use for Fig. 41. Pig. 43. Mohr's burette. Mohr's burette. the more common purposes, but its application is excluded in the employment of such solutions as would be affected by contact with rubber tubing, as in the case of potassium permanganate, silver, or iodine solutions. It consists of a graduated glass tube, 74 MANUAL OF CHEMICAL ANALYSIS. of about 12 millimeters (half an incli) iuternal diameter, and 50 centimeters (twenty inclies) in length ; to its contracted lower extremity is fitted a small piece of rubber tubing, into the lower end of which a small piece of glass tubing, about 25 millimeters (one inch) in length, and drawn out at the lower orifice to quite a fine point, is tightly inserted. A strong wire clamp (Fig. 43) Fig. 43. Fig. 44. closes the rubber tube, so that the fluid can only pass through, either in a stream, or drop by drop, when the knobs of the clamp are pressed. Since the correctness of the test depends upon the accurate reading of the height of the test-solution in the burette, a small hollow glass float, known as Erd- mann's float, is sometimes employed for this purpose (Fig. 44); it is of such a diameter that it can move freely in the tube without undue friction, and of such a weight that it sinks to more than half its length in the test liquid. A line is scratched around the centre of the float, serving to mark the coinciding line on the burette, and not the actual height of the liquid contained therein, which does not require consideration. The application of the float for determining the exact volume of test liquid employed is subject to certain restrictions; the burette must be accurately calibrated, for, if in' the least ununi- form in caliber, the reading in the narrow and wider portions of the tube will not agree with the direct reading by means of the marks on the burette. As usLially constructed, the mercury contained in the lower end in order to give it the proper weight is also liable to oxidation, which then disturbs the transparency of the interior of the bulb, and renders the line on the opposite side either invisible or indistinct ; also in the case of highly colored solutions, as potassium permanganate, iodine, etc., the fine line on the float is seen with difficulty, or not at all. For these reasons the float is not very generally employed, and the readings may usually be attained with sufficient accuracy, and with but slight error, by observing, in the case of colorless liquids, simply the mark on the burette coinciding with the lower line of the concave meniscus of the liquid when held towards the light ; with colored VOLUMETRIC ANALYSIS. 75 liquids the lower line produced by the concave surface of the liquid is not so distinctly seen, and in this case it is therefore better to observe the mark on the burette coinciding with the Upper line of the concave surface when held from the light, or against a dark object, by which means readings proportionately accurate may readily be obtained. Other forms of Mohr's burette are provided with a glass stop- cock (Figs. 45 and 46), so as to be suitable for all liquids, includ- FiG. 45. Fig. 46. Fig. 47. Mohr's burette, with glass stop-cock. Mohr's burette, with glass stop-cock. Gay Lussac's burette. ing those which are affected by organic matter ; they are, however, more expensive than the one above described, and in the hands 76 MANUAL OF CHEMICAL ANALYSIS. of the inexperienced are less convenient, as also not permitting an equally ready control over the flow of liquid. Gay Lussac's burette is represented in Fig. 47. This is one of the oldest forms of burette, and is still in quite frequent use, as being composed entirely of glass it may be used for estimations with any of the volumetric test-solutions, and is thus not open to the objections of the simple form of Mohr's burette. The burette- is graduated from a point somewhat below the point of delivery downward, and has usually a capacity of 50 cubic centimeters to the lowest point of graduation, subdivided into tenths of a cubic centimeter. In using the burette it is most conveniently held in the left hand, and so inclined as to allow the test-liquid to fall drop by drop into the solution of the substance to be esti- mated, contained in a beaker or other vessel, meanwhile stirring the liquid with a glass rod held in the right hand. When the liquid does not flow readily from the exit tube, it may be facili- tated by producing a slight pressure with the mcuth by means of a piece of glass tubing inserted in the cork of the burette, or preferably by means of a small piece of rubber tubing attached to the glass tube ; in no case should the liquid come in contact with the cork. In observing the height of the liquid in the burette it should be held near the top by means of the thumb and forefinger of the right hand, when it assumes a perfectly vertical position, and any expansion of the liquid caused by the heat of the hand is also thereby avoided; the same rules in relation to the concavity of the upper surface of the liquid being observed, as have been pre- viouslj'- described. Geissler's burette is represented in Fig. 48. It is a modifica- tion of Gay Lussac's burette, but difi'ers from the latter by having the small tube inclosed within the larger one, thereby tending to render the burette less fragile ; this is, however, one of the less convenient forms, and being also difficult of accurate con- struction, is not in general use. Burettes are conveniently kept for ready use on a revolving stative (Fig. 49), and should be properly labelled in accordance with the test-solution contained therein, in order to avoid error. To prevent the evaporation of the test-solution and exclude dust, the burette may be closed at the top by means of a marble, as shown in the figure, but as these are liable to fall from their position and produce breakage of other apparatus beneath, an in- verted short test-tube placed over the top of the burette is much to be preferred ; alkaline solutions, when kept for any length of time in the burette, should be protected from the absorption of carbonic acid gas by means of a tube filled with fragments of fused potas- sium hydrate, and inserted in the cork of the burette, as shown in the figure. The tests are made by first filling the burette with the test-solu VOLUMETRIC ANALYSIS. 77 tion to exactly such a height that the mark on the float is coin- cident with the on the scale of the tube, or, if the float is not Fig. 48. Fig. 49. ill Geissler's burette. employed, the mark on the burette coinciding with the surface of the liquid contained therein should be accurately observed. The solution or mixture to be tested is placed in a beaker under the 78 MANUAL OF CHKiMICAL ANALYSIS. burette (Fig. 50), and then so nrnch of the test-solution is gradu- ally and carefully delivered into the beaker, with gentle stirring Ftg. 50. with a glass rod, as to accomplish the reaction indicative of the completion of the operation. Volumetric determinations are principally based, either upon neutralization^ in which the quantity of a base or an acid is deter- mined by noting the volume of the test-solution of acid or alkali which is necessary to convert it into a neutral salt ; the point of neutralization being usually indicated by means of litmus solu- tion,* which assumes with free acids a red, and with free alkalies * Plienolphtaleitn lias recently been recommended as an indicator in alliali- metry ; the neutral iind acid solutions of this substance being colorless, but assuming in the presence of the slightest excess of alkali an intense carmine-red color. The color developed by alkalies is destroyed by all acids, including carbonic; hence, like litmus, it is unfitted for use in the titration of carbonates in the cold. The solution is prepared for use by dissolving one part of plienol- phtale'in in 100 parts of a mixture of 35 parts of alcohol and 75 parts of water ; four or five drops of this solution being sufficient for 50 to 100 cubic centi- meters of the solution to be titrated. Cochineal solution is occasionally used in preference to litmus, particularly with solutions of the alkaline earths, such as calcium and barium hydrates, and possesses the additional advantage that it is much less modified in color by the presence of carbonic acid. The solution is prepared by digesting 3 grams of powdered cochineal in a mixture of 40 cubic centimeters of alcohol and 160 cubic centimeteis of water. Its color is yellowish-red, whicli is changed to violet by alkalies, mineral acids restoring the original color ; but it is not so sensibly VOLUMETRIC ANALYSIS. 79 a blue coloration; or, upon oxidation and reduction^ in which the quantity of the substance to be determined is found by noting the volume of the test-solution of the oxidizing or reducing agent to which it is equivalent, or which is required to produce a certain reaction ; the changes indicating the final completion of the pro- cess varying in their nature according to circumstances or the process employed; the principal oxidizing agents being potassium permanganate, potassium bichromate, and iodine, and the reducing agents, ferrous and stannous salts, and sodium hyposulphite (thio- sulphate) ; or, upon precipitation, in which case the quantity of the substance to be determined is derived from that of the re- agent required to cause its complete precipitation, or, the reagent is added until a precipitate begins to make its appearance, when a certain stage in the process is thereby indicated, from which the calculation may be made. The quantities of the substances to be assayed volumetrioally are submitted to examination by weight, which are sometimes for convenience in calculation made coincident with their mole- cular weights, and are expressed in grams ;* those of the test- solutions by measure in cubic centimeters.f In the preparation of solutions for volumetric estimations those designated as normal are, as a general rule, such as contain, for univalent substances, the molecular weight expressed in grams in one liter, and for bivalent substances, or salts containing two atoms of a univalent base, one-half of the molecular weight ex- pressed in grams in each liter ; solutions of trivalent s"ubstances containing one-third of the molecular weight, etc. Decinormal and centinormal solutions are, therefore, one-tenth of this strength, and are frequently for convenience briefly designated as — and -L J -^ ^ 10 100 solutions. Solutions are, however, sometimes made of such a strength as to be only empirically normal, and are so prepared that a certain volume of the liquid (100 cubic centimeters) stands in direct relation to, or will exactly neutralize, a known quantity (one gram) of some one definite substance in a pure state, by which means the number of cubic centimeters of the test-solution employed for the same amount by weight of the substance to be estimated, will indicate at once the percentage strength of the substance under examination. Such solutions, although some- times conveniently employed in the analysis of technical products, affected by the -weaker organic acids as litmus, and for these the Fig. 51. latter is, therefore, to be preferred. * One grnm is equal to 15.434 grains of Troy weight. f A cubic centimeter (Fig. 51) is the volume occupied by one gram of distilled water at its point of greatest density, 4° C. ; metric measurements, however, are uniformly taken at 15° C. (59° F.). 80 MANUAL OF CHEMICAL ANALYSTS. are limited in their application to the estimation of one single substance, requiring for each acid and alkali a special liquid, whereas with virtually normal solutions but one acid is required for all- bases, and one alkali for all acids. Solutions are sometimes designated as normal which bear no definite relation to the molecular weight of the substance con- tained therein, or to its neutralizing power, but, as in the processes of oxidation and reduction, refer to a particular reaction involved in the process to which the solution is applied ; thus a normal solution of potassium permanganate (K^MujOj) is made to contain one-tenth of the molecular weight expressed in grams in a liter, with reference when used as an oxidizing agent to the amount of available oxygen : 2K,Mn,0, + 6H,S0, = 2K,S0, + 4MnS0, + 6H,0 + 50,. A normal solution of stannous chloride, although tin is a quadri- valent metal, will thus likewise, when used as a reducing agent, contain one-half, and not the fourth of its molecular weight ex- pressed in grams in a liter, as is shown by the expression of its reaction with ferric chloride : Fefil^ + Sn'Ol^ = 2FeCl2 + SnCl,. ANALYSIS BY NEUTRALIZATION. ESTIMATION OP ALKALIES (ALKALIMETRY). The operations of analysis by neutralization are based upon the fundamental and simple principle, that the proportions in which chemical substances unite with each other in forming new com- pounds are definite and invariable, and that these proportions are represented by the molecular weights. In the formation of solu- tions, therefore, for volumetric estimations by neutralization, a simple equation, and the molecular weights deducted therefrom, will at once indicate the amount of solid substance necessary for the production of a normal solution, which then bears a direct and simple relation to all other substances with which it may be employed for neutralization, and which is expressed by the mole- cular weight of the substance, or a corresponding fraction deducted therefrom. The standard test-solutions employed for the estimation of alkalies are either oxalic or sulphuric acids; the oxalic acid solu- tion is the more commonly employed, and is generally preferred on account of the convenience of preparation, but as the amount of water of crystallization which the acid contains (two molecules) has to be considered in the preparation of the solution, it is neces- sary that it should be neither moist, nor that it should have lost a part of the water of crystallization by exposure — conditions which would materially influence the correctness of the strength of the solution, and consequently the results of all the estimations obtained VOLUMETRIC ANALTSIS. 81 therewith. Its action upon litmus is moreover not quite as deci- sive or as distinct as that of sulphuric acid, for which reason, and that above mentioned, sulphuric acid is considered in careful re- search to furnish more accurate results. For the preparation of a standard sulphuric acid, 49 grams (corresponding to one-half the molecular weight) of concentrated sulphuric acid are diluted with water to the measure of one liter. This affords a solution which is approximately normal, and the exact strength of which is afterwards determined. A burette being filled with the acid solution, a certain number of cubic cen- timeters are allowed to flow into a beaker, a few drops of litmus solution added, and from another burette containing a solution of potassium or sodium hydrate of empirical or unknown strength, but which should be stronger than the acid solution, a sufficient amount is added until the indications of the point of neutraliza- tion are obtained, or until the last drop of the alkaline solution which is added produces a decided blue coloration. From the number of cubic centimeters of the alkaline solution required, as determined by two or three experiments with concordant results, a simple calculation will show to what extent the alkaline solu- tion has to be diluted in order that equal volumes of the acid and alkali shall precisely neutral- ize each other, and which must Fig. 52. again be confirmed by experi- ment after the dilution of the alkaline solution. This having been attained, two or three portions of pure, freshly ig- nited sodium carbonate, of about two grams each (readily obtainable by the ignition of portions of pure sodium bicar- bonate, of about three grams each, in an open porcelain crucible, and preserved after ignition by filling, while still warm, into tightly corked test- tubes), are accurately weighed. The several portions, dissolved separately, in small amounts of water, in a percelain cap- sule or beaker, and a few drops of litmus solution added, are then titrated with the acid solution (Fig. 52) ; the liquid being heated from time to time to insure the complete removal of the disengaged carbonic acid gas, until a slight excess of acid has been added, which is evidenced 6 82 MANUAL OF CHEMICAL ANALYSIS. by the appearance of a bright cherry-red coloration. The excess of acid employed may be then inversely titrated with the alkaline solution until the blue coloration is produced, when the amount reqiiired of the latter, deducted from the number of cubic centi- meters of acid employed, will give the number of cubic centimeters of acid which were required for the exact neutralization of the amount of carbonate taken. The number of cubic centimeters of acid which would be required if the latter were exactly normal, may be found by dividing the amount of sodium carbonate taken by the decimal 0.053 (the amount of sodium carbonate equivalent to one cubic centimeter of strictly normal sulphuric acid). This number, which will usually be found to be somewhat greater or less than the number of cubic centimeters employed, will, when divided by the latter, give a number slightly greater or less than one, showing that the acid is a little weaker or stronger than normal, aod, designated as the correction factor or coefficient, must be used to multiply the number of cubic centimeters of acid or alkali used in each estimation, in order to convert it into its equivalent of normal strength. The exact strength of the acid and alkali and their correction factor having thus been accurately deter- mined, the methods of their application remain the same as will be described for the standard solution of oxalic acid. Standard Solution of Oxalic Acid. H,C,0, -f 2H,0; 126. 63 Grams in 1 Liter. Sixty-three grams of pure crystallized oxalic acid are dissolved in water; the solution is filtered into a liter-flask, and the filter washed with water until the exact volume of 1 liter at about 15-^ C. (59° F.), is obtained. One hundred cubic centimeters of this solution contain one- twentieth of the molecular weight, in grams, of oxalic acid, and are, therefore, capable of neutralizing one-twentieth of the molec- ular weight in grams of bivalent bases, or salts containing two atoms of univalent metals, or one-tenth of the molecular weight in grams of salts containing one atorji of univalent bases. This test solution is applied for the estimation of the alkaline hydrates, carbonates, acetates, tartrates, citrates, and borates : 100 cubic centimeters of the solution will exactly neutralize, or other- wise decompose, if pure, or of officinal strength : 5.23 grams of Ammonii Carbonas. NHiHCOj+NHiNHjCOj. 17.00 " Aqua Ammonite, U. S. P., spec. gray. 0.959. 6.07 " Aqua AmmoniiE fm-tior, U. S. P., spec. grav. 0.900. 54.68 " Liquor Plumbi Subacelatis, U. S. P., spec. grav. 1.228. 113.00 . " Liquor Potassse, U. S. P., spec. grav. 1.036. 80.00 " Liquor Sodse, U. S. P., spec. grav. 1.059. 9.80 " Potassii Acetas, KC^HsOj.* * Alter ignition. VOLUMETRIC ANALYSIS. 83 Fio. 53. 10.01 grams of Potassii Bicarbonas. KHCO,. 18.80 " Potassii Bitartras, KHC4H^6„.* 8.30 " Potassii Carbonas, depuratus. 6.91 " Potassii Carbonas, purus, K.,CO|. 10.80 " Potassii Citras, K^CsH^Oj-f- HjO,* or 10.30 grams of anhy- drous salt. 14.10 " Potassii et SodiiTartras, KNaO,H,Os-f4H,0.* .■i.ei " Potassii Hydras, KHO. 3.14 " Potassii Permanganas, KjMn^Og. 11.76 " Potassii Tartras, SKjC^H, Ob, H^O.* 13.60 " Sodii Acetas, NaC.,B;,0.,+ 3H.,0.* 8.40 " Sodii Bicarbonas, NaHCOa. 8.93 " Sodii Bicarbonas Venalis 19.10 " Sodii Boras, Na.,BiO,+ 10H.iO. 14.30 " Sodii Carbonas.'NajCOa+lOHjO, or 5.3 grams of anhydrous salt. 4.00 " Sodii Hydras, NaHO. 17.00 " Spiritus Ammonise, TJ. 31 P., spec. grav. 0.810. The operation is conducted by weighing the above quantity of the substance, or the preparation to be estimated, placing it in a beaker, and, when required, diluting or dissolving it by the addi- tion of a sufficient quantity of water. The tartrates, citrates, and acetates have first to be completely converted into carbonates by ignition in a platinum or porcelain crucible (Fig. 53), care being taken that no loss of substance is occa- sioned by the increase of volume on first heating; to avoid this, the crucible should be suificiently large, and at first very gently heated, after which the heat may be increased until inflammable vapors cease to be evolved, and perfect reduction is eft'ected. As this operation is usually accompanied by the separation of consid- erable carbon, the fused mass should be extracted with hot water, filtered into a capsule or beaker, and the filter, together with the insoluble residue, well washed with water. When the solution is ready for the test, a few drops of litmus solution are added, so as to impart a distinct bluish tint ; the capsule or beaker is then placed under the burette containing the test-solution (Fig. 54), and, with constant gentle stirring with a small glass rod, the test-solution is delivered into the beaker, first in a stream, and, when approaching the point of neutraliziation, drop by drop, until the blue liquid assumes a cherry-red hue. In the estimation of carbonates it is preferable, as stated on page 81, to add an excess of the standard acid solu- tion above that required for the neutralization of the alkali, the * After ignition. Si MANUAL OF CHEMICAL ANALYSIS. Pig. 54. solution being heated to expel completely the liberated carbonic acid gas, which, by its action upon litmus, imparts a violet or wine-red coloration to the liquid, as distinguished from the light cherry-red coloration which is produced by the acid test-solution. The excess of acid employed may then be inversely titrated or neu- tralized by a corresponding standard alkali solution, the preparation of which has already been mentioned (page 81), and will be fur- ther described under the estimation of acids ; the difference between the amounts of the two solutions employed, both being equal in volumetric strength, will give the exact amount of acid solution re- quired for the neutralization of the alkali or alkaline car- bonate. This method of pro- cedure has the additional ad- vantage that the change of color of the litmus solution from red to blue is much more prominent than from blue to red, thus insuring a more ac- curate determination of the exact point of neutralization. These operations require care and skill in every point, so as to avoid the slightest loss of either of the liquids, and a consequent error in the final result. When neutralization is in- dicated by the light, cherry- red coloration in the one case, or, in the above described method of inverse titration, by the appearance of the blue colora- tion in the other, the process is completed, and the volume of the acid test-solution employed is observed. The number of cubic centimeters employed, less than 100, indicates at once the per- centage of impurities, or of deficiency of strength in the substance estimated. On the other hand, each cubic centimeter of the test-solution of oxalic acid employed corresponds to one milligram molecule of alkaline hydrate, one-half milligram molecule of alkaline carbon- ate, or the proportionate amount of other salts, i.e.: 1 cubic centimeter corresponds to 0.017 gram Ammonia gas, NHj. 1 " " " " 0.05333 " Ammonium Carbonate, NH^HCO».NH,NH.,CO.,. 1 " " " " 0.18935 " Lead Acetate, crystallized, Pb(C,,H30,)j-f3B,0. VOLUMETRIC ANALYSIS. 85 1 cubic centimeter corresponds to 0.13675 gram Lead Subacetate, as PbjOCCjHjO;,).,, " •' " 0.0980 •• - ■ - " " ■ " 0.1000 " 0.1880 " 0.0690 " " 0.1020 " " 0.0560 " " 0.0314 " " 0.1410 " " 0.1175 " " 0,1360 " " 0.0840 " " 0.1910 ■' " 0.1430 " " 0.0530 " " 0.0400 " Potassium Acetate, KC,H.,Oj.* Potassium Bicarbonate, KHCOj. Potassium Bitartrate, KHC^H^Oe.* Potassium Carbonate, anhy- drous, K.^COj. Potassium Citrate, anhydrous, . K,C«HA.* Potassium Hydrate, KOH. Potassium Permanganate, K,Mn.A. Potassium Sodium Tartrate, KNaCh this deviation is influenced in character as well as in extent by the solvent em- ployed and the concentration of the solution, thus restricting the practical application of this' property for their estimation to cer- tain conditions and limits. With many reagents the alkaloids afford special reactions in common, depending upon their precipitation from their solutions in a form which, although presenting no sharply discriminating- individual characters, very frequently serves to determine the presence of a body of this class, or for its obtainment in a form better adapted for its purification, estimation, or further chemical examination. Thus the alkaline hydrates and carbonates precipi- tate the alkaloids from the aqueous solution of their salts ; the precipitates, how^ever, in some cases being readily re-dissolved by an excess of the precipitant. To these may be added the follow- ing list of the more important and commonly employed reagents, which, in most cases, produce in aqueous solutions of the alka- loids, or their salts, precipitates possessing general, definite characters. Tannic acid produces white or yellowish tannates of the alka- loids, many of which are soluble in hydrochloric acid, and in some instances, as in the case of morphine, are readily re-dissolved by a slight excess of the precipitant. In this connection the fact should, however, be borne in mind that tannic acid also precipitates many non-alkaloidal or neutral bodies, and particularly the large class of so-called bitter prin- ciples. Iodine in potassium iodide solution (Wagner), page -39, produces yellowish, brown, or reddish-brown precipitates, which are insolu- ble in water, alcohol, and dilute acids. Potassio-mercuric iodide (Planta and Delffs), page 40, produces white or yellowish-white precipitates, in which the alkaloid takes the place of the potassium of the reagent, and which are either amorphous or crystalline, insoluble in acids, but soluble in alcohol. Potassio-cadmic iodide^ (Marme, Dragendorff') produces, in solu- ' Cadminm iodide is dissolved in a lint, concentrated, aqueous solution of potassium iodide, and this solution is mixed with as much concentrated sola- lOi MANUAL OF CHEMICAL ANALYSIS. tions slightly acidulated with sulphuric acid, white, amorphous precipitates, which, after some time, become yellowish and crys- talline, and are readily soluble in alcohol or an excess of the reao;ent. Potassio-hismidhic iodide^ (Dragendorft') produces, in solutions slightly acidulated with sulphuric acid, orange-red, amorphous precipitates. Phospho-molyldic acid^ (De Vrij, Sonuenschein). — This reagent, applied in the form of an acid solution of the sodium salt, pro- duces yellow or brownish-yellow, amorphous, flocoulent precipi- tates, which are insoluble in alcohol and dilute mineral acids, but are dissolved b}'- the concentrated mineral acids, and by several of the organic acids. Mercuric chloride^ page 39, produces white, crystalline precipi- tates, which are soluble in hydrochloric acid. Platinic clilorid-e, page 39, and mtric chloride, page 31, form with most of the alkaloids double salts, analogous in composition to those of the inorganic alkalies, which are usually of a bright yellow color, either crystalline, or gradually becoming so upon standing, or amorphous and flocculent, and generally sparingly soluble in water, but soluble in warm hydrochloric acid. Picric acid (Hager) precipitates most of the alkaloids, even from very dilute solutions, in a yellow, crystalline, or amorphous form ; the precipitates are insoluble in an excess of the precipitant, or in dilute sulphuric acid, but are soluble in hydrochloric acid. In addition to the large class of alkaloids derived from the vege- table kingdom, science has been enriched, and at the same time the labors of the chemical expert rendered more arduous, by the comparatively recent discovery and development of a class of bodies produced by the putrefaction of animal substances, which closely resemble some of the vegetable alkaloids in their physical and chemical properties, and which have been designated as ptom.aines (cadaver poisons). From the time of their discovery by Salmi and Gauthier, in 1873, much valuable knowledge has been contributed respecting their physiological action and chemical behavior, by the labors lion of pntasshini iodide as will be sufficient to retain the cadmium iodide iu solution when cold. 1 Prepared from bismuth iodide as potassio-cadmic iodide is prepared from cadmium iodide. 2 An aqueous solution of ammonium molybdate, acidulated with nitric acid, is added to an aqueous solution of sodium phosphate, acidulated with nitric acid ; the resulting precipitate, after standing for some time, is filtered off, well washed with water, and dissolved in a solution of sodium carbonate. The solu- tion is then evaporated to dryness, and the residue gently ignited until ammo- nia ceases to be given otf. The cooled product is "finally dissolved in water, and so much nitric acid added as may be required to dissolve the precipitate which is first formed. ALKALOIDS. 105 and observations of a number of investigators, but whicb is not yet sufficiently complete to admit of their classification. The ptomaines appear to exist in several distinct forms, although Hager has designated the alkaloidal product of the decomposition of animal matter as septicin, with reference to one special body, which, in explanation of the difference in physical, chemical, and physiological properties, he believes to be capable of assuming different modifications, or of undergoing further decomposition with the production of other bodies of an alkaloidal nature, accord- ing to the extent of putrefaction. The ptomaines are mostly volatile, and in this form appear to bea-r some resemblance to coniine, possessing in addition to the general characters of alkaloids a narcotic odor, as also being pre- cipitated by chlorine-water, but, unlike coniine, not becoming turbid on gently warming ; while others present a more permanent charac- ter, with some analogies to atropine, hyoscyamine, veratrine, etc. They all possess strongly reducing properties, and when added to a solution of potassium ferricyanide convert the latter into ferrocyanide, which, on the addition of ferric chloride, yields a precipitate of Prussian blue. These bodies, although in some instances inert, have been found to possess, in the majority of cases, powerful toxic properties ; their distinction from the vege- table alkaloids may, therefore, be destined to become an im- portant factor in the problems of toxicological chemistry and forensic research. The isolation and identification of the alkaloids and allied prin- ciples, and especially those of a toxic character, is a subject of such importance, and of necessity so extended in its details, that it is properly confined to the departments of toxicological chem- istry. With this consideration it is the aim to present here simply a brief outline of the generally adopted process of separation, together with the more important and characteristic tests for their recognition. Although the physical and chemical properties of the alka- loids, as has been indicated, present a marked variation among themselves, yet they are nevertheless capable of being divided into certain groups with respect to their behavior towards sol- vents, which, although by no means so sharply defined as in the case of the inorganic bases, still suffices for their separation in a form sufficiently pure for their identification, or for i'urther expe- riment. For the separation of the alkaloids and allied principles from other extraneous, organic, coloring, or extractive matters, the method of Stas, as modified by Otto, will here be briefly de- scribed. This method, which consists in treating the acid and alkaline solutions successively with ether, and finally with amylic alcohol, recommends itself by its simplicity, and is often adopted in preference to the more complicated method of Dragendorfi", 106 MANUAL OF CHEMICAL ANALYSIS. which consists in the successive treatment of both the acid and the alkaline solution with benzin, benzol, chloroform, and amylic alcohol, or to the other variously modified processes. The organic material to be examined, if not already in a fluid condition, should first be mixed with, or dissolved in, water, and then tested with litmus-paper, in order to ascertain its possible acid or alkaline character. If it be perfectly neutral, it should be slightly acidulated with tartaric acid, or, if acid, it is first to be neutralized with sodium hydrate, and then, as in the case of an originally neutral reaction, slightly acidulated with tartaric acid ; if, however, it possess an alkaline reaction, in which case the vola- tile alkaloids coniine and nicotine would be indicated by t>heir odor, tartaric acid is likewise added until a perceptibly acid reac- tion is obtained. If the substance in its acidulated solution, as above obtained, forms a perfectly clear liquid, it may be treated at once with ether, but in the case of articles of food, the contents of a stomach, vomited matter, etc., the direct treatment with ether is precluded, in consequence of the presence of fatty matter or other impurities, which would likewise become dissolved, and dis- guise the characteristic reaction of the subsequently applied tests. The substance in this case, after the previously described treat- ment, should first be evaporated upon the water-bath to a semi- solid consistence, then transferred to a flask, about twice its weight of strong alcohol added, and digested upon the water-bath for about half an hour. The clear liquid is then poured off, and the residue digested twice or thrice successively in the same manner with alcohol. The entire amount of mixed alcoholic liquid is then filtered into a capsule, and evaporated upon the water-bath to the consistence of a soft extract ; this is again treated with strong alcohol, and the alcoholic solution filtered and evaporated as before. This latter residue is now treated with a small amount of cold water, and the slightly acid solution thus obtained filtered into a flask or other suitable glass vessel, and successively shaken with two or three times its volume of pure ether. The ethereal solu- tions, which have been separated as completely as possible from the aqueous liquid by means of a glass separating funnel, are then allowed to evaporate spontaneously. I. From the acid solution are hereby absorbed by ether: Colchicine. DiGlTALIX. PiCROTOXIX. Caxthaeidin. (Also traces of atropine and veratrine, which, however, if present, will be subsequently extracted much more completely from the alkaline .solution.) ALKALOIDS. 107 The residue left by the evaporation of the ether from the acid solution, as previously described, is to be dissolved in a small amount of hot water, the solution filtered, and further examined for the above-named substances. In order to avoid repetition, tjie description of all the more important alkaloids, together with the allied neutral principles and glucosides, will be reserved for the second part of this vol- ume, where their physical properties and chemical character- istics will be fully detailed, and to which in searching for the above-named substances, reference should always be made. For this reason, but a limited number ot the more important indi- vidual reactions of these bodies will here be stated, when, if such be found to correspond with any one of the substances mentioned, and in order to exclude any possibility of error, its identity should be invariably confirmed by the other known tests. Colchicive, if present, will be indicated by the yellow color of the solution ; it is, moreover, precipitated by tannic acid and iodine solution, but by potassio-mercuric iodide only after being previously acidulated with a mineral acid. Chlorine-water pro- duces a yellow precipitate, soluble in ammonia-water with an orange-yellow color. Concentrated nitric acid colors its solution violet, changing to red ; if the nitric acid solution be diluted and made alkaline with sodium hydrate, an orange-red color is pro- duced. Digitalin, not properly an alkaloid but closely related by its properties, is precipitated by tannin only from a concentrated solution. When it is dissolved, in a capsule, with concentrated sulphuric acid, and a trace of bromine water is brought into the liquid, a violet-red color is produced. If a trace of digitalin, together with a little purified ox-gall, be dissolved in a little water, in a capsule, a small amount of concentrated sulphuric acid added, and warmed at from 60 to 80° C. (140 to 176° F.), the solution gradually assumes a fine red color. Picrotoxin is not precipitated by tannin, nor by the other alka- loidal reagents. It may be readily obtained in a crj'stalline form from its solution in hot water or in alcohol. Its aqueous solution possesses an intensely bitter taste, and, when made alkaline with a few drops of sodium hydrate solution, reduces an alkaline solu- tion of cupric oxide on heating. Gantharidin does not afford the general reactions of alkaloids, and may be obtained in a crystalline form from its solution in ether or hot alcohol. It is very sparingly soluble in water, and, for want of characteristic chemical tests, may be extracted from the ethereal residue by fatty oils, and recognized by its vesicating properties. 108 MANUAL OF CHEMICAL ANALYSIS. The original acidulated, aqueous liquid, which has been sub- jected to the above treatment with ether, is subsequently gently warmed in order to expel the small amount of ether which re- mains dissolved therein, and solution of sodium hydrate in slight excess then added until, upon testing with litmus or turmeric- paper, a distinct alkaline reaction is obtained ; the alkaloids are thus liberated from their combination, and are precipitated, or, as in the case of morphine, become re-dissolved by the excess of al- kali. The alkaline liquid is then agitated twice or thrice succes- sively with pure ether, allowing an interval of about half an hour to elapse before the separation of each portion of ether from the aqueous liquid, and finallyHhe mixed ethereal liquids are allowed to evaporate spontaneously. II. From the alkaline solution are hereby absorbed hy ether : (fls) Liquid and Volatile. (6) Solid and Permanent. Nicotine. Strychnine, CoNiiNE. Brucine. Veratrine. Atropine, Aconitine, Delphinine, Narcotine, Thebaine, Codeine, Papaverine, Hyoscyamine, Phi^sostigmine, Emetine. (Also, possibly, traces of colchicine and diyitalin, which are diffi- cult to abstract perfectly from the acid solution by means of ether.) Before proceeding to apply the individual tests for the identifi- cation of the alkaloids, it is preferable first to test the residue which may be left by the evaporation of the ether, in order pri- marily to establish or confirm the presence or absence of such a body This may be conveniently accomplished without loss of material, by placing a very small portion of the residue upon a watch-glass, together with a few drops of water, and then, by means of a glass rod, adding a trace of hydrochloric acid, in order to form a solution of the salt. A few drops of this solution may then be tested upon a glass or porcelain plate, with some of the general alkaloidal reagents, e. g., potassio-mercuric iodide, iodine solution, tannic acid, platinic chloride, etc., adding a drop of the reagent by means of a glass rod, and, for better observing the formation of such precipitates with the reagents as are of a light color, the glass plate should be placed upon a piece of dark ALKALOTDS. 109 paper or other suitable object. With the attainment of a negative result by the use of these reagents no further examination need be made of the substance in question for an alkaloid, and much time and labor will, therefore, be saved. If, however, the above general tests have revealed the presence of an alkaloid, small portions may then be taken for applying the most characteristic individual tests, commencing the search by testing for the more commonly occurring alkaloids of the list, and finally, in case of an affirmative reaction, confirming the result by the application of as many of the other well-Icnown tests for the sub- stance as may seem necessary to establish its identity, or as the usually limited supply of the substance may admit. Nicotine, in case of the obtainment of a liquid residue by the evaporation- of the ether, will be indicated by its strong narcotic odor. It is not precipitated by chlorine-Avater, and its aqueous solution does not become turbid on warming. When mixed with hydrochloric acid, and cautiously warmed, a reddish-brown mixture ensues, which, by further evaporation and cooling, gives upon the addition of nitric acid a violet color, gradually changing to orange. Coniine will be indicated by the strong, peculiar, and unpleasant odor of the obtained liquid residue. It is precipitated by chlorine- water, and its aqueous solution becomes turbid on gently warm- ing. Dry hydrochloric acid gas produces first a purplish-red, and finally an indigo-blue color. Strychnine dissolves in concentrated sulphuric acid, forming a colorless solution, which, upon the addition of a trace of potassium bichromate, assumes a bluish-violet color, changing to cherry-red, and rapidly fading. (Curarine produces a reaction somewhat similar to strychnine, but it is not absorbed by ether, either from an acid or an alkaline solution, and is further distinguished by other tests, which will be described under group III.) Brucine produces with concentrated nitric acid an intense blood- red color, which soon changes to yellowish-red, and, upon gently warming, becomes yellow. If to this solution water then be added, it assumes, upon the addition of stannous chloride or ammonium sulphide (preferably freshly prepared), a beautiful violet color. Veratrine dissolves in concentrated sulphuric acid with a yellow color, which, upon warming, changes to blood-red. It dissolves in concentrated hydrochloric acid, forming a colorless solution, which, upon warming, assumes a fine, permanent, dark-red hue. Atropine, when heated with concentrated sulphuric acid and potassium bichromate or ammonium molybdate, develops the odor of bitter almond oil. When applied to the eye, it powerfully dilates the pupil. Aconitine produces with concentrated phosphoric acid, upon warming, or slowly with concentrated sulphuric acid at ordinary 110 MANUAL OF CHEMICAL ANALYSIS. temperatures, a violet color. {Delphinine produces a similar reaction with phosphoric acid, but gives also the digitalin reaction with sulphuric acid and bromine-water.) Narcotine dissolves without color in concentrated sulphuric acid, but the solution soon becomes yellow, and, upon the addition of a trace of nitric acid, blood-red. Concentrated sulphuric acid, which contains a trace of sodium molybdate, produces a green color, but if the solution of molybdate be applied more concentrated, the green soon changes to a fine cherry-red. A freshly prepared solu- tion of narcotine in dilate sulphuric acid (1 part of concentrated acid to 5 parts of water), when evaporated very gradually in a small porcelain capsule, produces a successive change of colors, becoming first orange-red, then on the edges bluish-violet, and finally, at the temperature at which the sulphuric acid begins to volatilize, intensely reddish-violet. Chlorine-water colors solu- tions of salts of narcotine greenish-yellow, which, upon the addi- tion of a very little ammonia-water, changes to a transient cherry- red color. Thebaine assumes with concentrated sulphuric acid a fine, deep blood-red color, which gradually changes to yellowish-red ; with ammonium molybdate in concentrated sulphuric acid the same coloration is produced. Its solution in chlorine-water assumes upon the addition of ammonia-water an intense reddish-brown hue. Codeine assumes with concentrated sulphuric acid which con- tains a trace of ferric oxide in solution, gradually at ordinary temperatures, or immediately upon warming, a beautiful indigo- blue color. When dissolved in concentrated sulphuric acid, one or two drops of a concentrated cane-sugar solution added, and gently warmed, a fine purplish-red color is produced. Papaverine dissolves in cold concentrated sulphuric acid with a slight yellowish color, which, upon warming, changes to violet. The solution in chlorine-water is colored deep reddish-brown upon the addition of ammonia-water, after some time becoming almost blackish-brown. "With concentrated sulphuric acid, containing a little ammonium molybdate in solution, it assumes a green color, which, upon warming, rapidly changes to blue, and finally becomes of a fine cherry-red. Hyoscyarnine, for want of any specially characteristic chemical reactions, may be best recognized by the physiological property, which it shares with atropine, of producing dilation of the pupil when applied to the eye. It is distinguished from atropine in being precipitated from its solutions by platinic chlpride, if not applied in excess, whereas atropine is precipitated by this reagent only from relatively very concentrated solutions. Physostiymine is characterized by its physiological property of producing contraction of the pupil when applied to the eye. Its aqueous solution assumes a reddish color upon the addition of ALKALOIDS. Ill a small amount of a solution of chlorinated lime, whicli, upon the further addition of the latter, becomes discharged. Emetine is particularly characterized by its strongly emetic properties, which may be confirmed by experiments upon small animals, by the subcutaneous injection of its aqueous solution. Its nitrate is a very sparingly soluble salt. An aqueous solution of emetine assumes with a few drops of a freshly prepared, satu- rated solution of chlorinated lime, and the subsequent addition of one or two drops of hydrochloric or acetic acid, an orange or lemon-yellow color. Concentrated sulphuric acid dissolves emetine with the production of a green color, which soon changes to yellow. It should be observed that veratrine also possesses violent emetic properties, but this alkaloid is so characterized by other special tests that it cannot be mistaken for emetine. III. Alkaloids remaining dissolved in the alkaline solution: Morphine, Narceine, cuearine. The alkaline liquid remaining after the extraction by ether for the obtainment of the alkaloids of group II. should first be gently warmed in order to expel the small amount of dissolved ether, then acidulated with hydrochloric acid, and subsequently made slightly alkaline with ammonia-water. The ammonical liquid is then treated at least twice successively with warm amylic alcohol, separating the latter liquid carefully from the aqueous solution, and allowing it to evaporate, either spontaneously, or by means of a gentle heat. The amylic alcohol will have thus abstracted the entire amount of morphine, and the larger portion of the narceine from the solution, whilst the remainder of the narceine and the entire amount of curarine still remain dissolved in the ammoniacal liquid. The residue left by the evaporation of the amylic alcohol should first be tested by the general reagents in order to ascertain the presence of an alkaloid, when, in case of an affirmative result, the special tests may be subsequently applied. Morphine reduces iodine from a solution of iodic acid, which dissolves in carbon bisulphide or chloroform with a violet color. A neutral solution of morphine or its salts assumes with a small amount of a dilute neutral solution of ferric chloride a deep blue color. When dissolved in concentrated sulphuric acid, the solu- tion gently warmed, allowed to cool, and then a trace of dilute nitric acid added, a deep blood-red color is produced. . Narceine assumes upon the addition of iodine-water an intense blue color. Its solution in concentrated sulphuric acid is of a grayish-brown color, which, upon warming, changes to bloodred. A solution of narceice in chlorine-water assumes also upon the 112 MANUAL OF CHEMICAL ANALYSIS. addition of ammonia-water a blood-red color. (Narceine may be readily separated from morpbine by its much greater solubility in hot water.) For the separation of the remainder of the narceine (in case its presence should have been determined by the previous extraction with amylic alcohol), as also of the curarine, the alkaline liquid should be evaporated in a porcelain capsule upon the water-bath to dryness, the residue then reduced to powder, transferred to a flask, and digested for some hours with strong alcohol, with the aid of a gentle heat and frequent agitation. The liquid is then saturated with dry carbonic acid ga.s, in order to convert the free alkali into carbonate, afterwards brought upon a filter, the inso- luble residue well washed with strong alcohol, and the alcoholic liquid finally evaporated. If this residue is found to be still too impure for the application of the tests, it should be treated with warm water, the aqueous solution filtered, and evaporated upon the water-bath, this residue again taken up with alcohol by the aid of a gentle heat, the solution filtered, and evaporated as before. In the alcoholic residue the narceine may be recognized by the previously-described tests, whilst the curarine may be readily abstracted therefrom by means of cold water, in which it is freely soluble. Curarine, as previously stated, page 109, produces with sulphuric acid and potassium bichromate a reaction somewhat similar to strychnine, but the coloration is more of a bluish tint, and much more permanent. It dissolves in concentrated sulphuric acid with a pale violet color, which gradually changes to a dirty red, and, after some hours, assumes a rose-red color. With potassium, bichro- mate it forms a quite sparingly soluble salt, analogous to the strychnine chromate, differing, however, from the latter by its amorphous character. It is of particular importance in testing for alkaloids, especially when contained in complex organic mixtures, to obtain them in the purest possible state, as slight impurities may, according to their nature, either altogether conceal, or materially influence the characteristic reactions upon which the recognition of the sub- stance depends. In order to effect the purification of the alkaloids when con- taminated with adhering coloring matter, etc., as also for the separation of the individual alkaloids from each other, recourse must be had to the distinctions in their physical and chemical properties, such as behavior towards the simple solvents, or the production of sparingly soluble simple salts, etc., from which the pure alkaloid, if desired, can again be obtained. It should also be made a rule in the application of the tests to employ the smallest possible quantity of substance, as the reac- ALKALOIDS. 113 Fig. 57. tions from their delicacy are usually quite as well obtained as with larger quantities, even should the amount of material at disposition be considerable, which, however, in forensic research is rarely, if ever, the case; and the amount of the reagent added should always be proportionate to the amount of the substance to be tested. For the observance of such reactions as depend upon the production or change of color, a small porcelain plate or capsule will be found the most serviceable, applying the reagent, when required in but small quantity, by means of a glass rod or small pipette (Fig. 57). In the preceding briefly described course for the systematic separation of the alkaloids, it will be evident that only the more commonly occurring bodies of this class, and such as possess toxic properties, have been considered, whilst such as are non-poisonous in their character, as, e. ^., caffeine, the cinchona alkaloids, etc., have been in- tentionally omitted, as not properly in- cluded within the province of forensic chemistry. Should the presence of such a body, however, be presumed or sus- pected in the substance under examina- tion, a consideration of its deportment towards ether or other sol- vents, in acid or alkaline solution, will at once indicate the method to be adopted for its isolation, after the accomplishment of which, the proper tests for its identification may be applied. For the separation of the alkaloids when associated with other organic or inorganic poisons, such as hydrocyanic acid, phosphorus, arsenic, metallic salts, etc., which may likewise be the object of search, special methods of manipulation and precautions are re- quired to be observed, in order that none of the substances shall undergo decomposition, or escape detection in the process of ex- traction, or that the correctness of the result may be thereby impaired. Investigations of this character, therefore, should only be en- trusted to the experienced expert, possessing special knowledge of the properties and deportment of the bodies in question, which from their importance are too extended in their scope to admit of a more detailed consideration in this place, although the charac- teristic and most reliable tests for the recognition of the above mentioned, and the more commonly occurring organic and in- organic poisons, will receive further attention in their appropriate places in the second part of this volume, and the methods indi- cated whereby their isolation may be effected. 8 PART II. THE MEDICINAL CHEMICALS THEIR PREPARATIONS, PHYSICAL AND CHEMICAL CHARACTERISTICS, WITH DIKECTIOSS FOE THE EXAMINATION OF THEIR QUALITY AND PURITY, AND FOR THEIR QUANTITATIVE ESTIMATION. THE MEDICINAL CHEMICALS AND THEIR PEEPAEATIONS. ACETUM. Vinegar. Ger. Essig ; Fr. Vinaigre ; Sp. Vinagre. ViNEGAE, as obtained by the acetic fermentation of dilute alcoholic liquids, presents considerable variation in its physical characters, such as color, odor, taste, etc., imparting properties which in most instances are unobjectionable, and are frequently desired in its employment for domestic purposes, while they do not always render it inadmissible for pharmaceutical applications. It must, however, form a perfectly transparent liquid, possessing a true acetic odor, free from empyreuma, and should contain no metallic impurities or acrid vegetable substance, as also no free inorganic or other foreign acids, with which it is not unfrequently adulterated for the purpose of increasing its strength. Vinegar contains, on an average, from 4.5 to 6 per cent, of true acetic acid. The British Pharmacopoeia requires a spec. grav. of 1.017 to 1.019, corresponding to 4.6 per cent, of absolute acetic acid. The Pharmacopoeia Germanica requires that 10 cubic cen- timeters of vinegar neutralize 10 cubic centimeters of normal solution of potassium hydrate, corresponding to 6 per cent, of absolute acetic acid. Examination : Free mineral acids are readily detected by adding to 20 cubic centimeters of the vinegar, about 4 or 5 cubic centimeters of strong ammonia-water, and evaporating in a shallow glass capsule on the water-bath. If the vinegar is pure, a slight yellow or brownish residue will remain, whereas in the presence of free mineral acids, or with tartaric and citric acids, a crystalline mass is obtained. As the ammonium salts are readily volatilized on heating, and the tartrate and citrate become thereby carbonized, the presence of fixed impurities may at the same time be determined. 118 MANUAL OF CHEMICAL ANALYSIS. The presence of mineral acids may be also readily detected as follows : A solution of ferric acetate is diluted with water to such an extent as to appear slightly yellowish, and a small amount of ammonium or potassium sulphocyanide dissolved therein, when no red coloration will be produced, even upon the addition of acetic acid ; the smallest trace of free sulphuric, nitric, or hydro- chloric acids, however, produces an intense red coloration, which may be rendered still more evident by shaking the liquid with ether, when the latter will absorb the red ferric sulphocyanide. Another method consists in mixing a freshly prepared solution of pure ferrous sulphate, free from oxide, with a solution of gallic acid in cold water, which has been previously well boiled ; to the colorless liquid thus obtained a little sodium acetate is added, and subsequently a small portion of the vinegar to be tested. The violet coloration produced by sodium acetate is destroyed by the presence of mere traces of free mineral acid, but is not affected by acetic acid. Sulphuric and Hydrochloric. Acids. — A crude mode of detecting the presence of sulphuric acid in vinegar consists in tiie addition of a little cane-sugar to a small portion of it, and evaporating the solution, at a gentle heat, in a porcelain capsule, to the consistence of a thick syrup; this will become almost black if free sulphuric acid be present. Since the water and the materials used for the preparation of vinegar generally contain traces of sulphates and chlorides, most vinegar yields a slight turbidity With barium and argentic nitrates. An undue proportion of sulphuric or hydrochloric acid may, how- ever, be readily detected by adding to 20 grams of the vinegar 0.5 cubic centimeter of soJution of barium nitrate arid 1 cubic centimeter of decinormal solution of argentic nitrate, and filter- ing; the filtrate should afibrd no turbidity upon the subsequent addition of either barium or argentic nitrates. The presence of sulphuric acid may also be detected, or verified, by adding to a portion of vinegar, contained in a test-tube, a satu- rated solution of calcium chloride, and subsequently heating to boiling; if, upon cooling, a cloudiness or a precipitate of calcium sulphate is produced, the presence of free sulphuric acid will be verified. Oxalic acid would also yield a white precipitate, but may be distinguished by affording a precipitate with a solution of calcium sulphate. •The presence of hydrochloric acid, in the free state, will be detected or verified by submitting a portion of the vinegar to distillation (Fig. 58), changing the receiver when about one-fourth of the liquid has distilled over, and reserving this portion for examination for aldehyde, and afterward continuing the distilla- tion until nearly the entire amount of liquid has passed over; the second portion of the distillate is then acidulated with nitric acid, and tested with argentic nitrate, when a white, curdy precipitate, ACIDA. 119 insoluble in nitric acid, but soluble in ammonia-water, will prove the presence of hydrochloric acid. Fig. 58. Fig. 59. Aldehyde, if present, will be indicated in the first or reserved portion of the distillate by its peculiar and unpleasant odor, and may be recognized by its property of reducing metallic silver from a solution of the nitrate; by the formation of a crystalline compound when shaken with an alka- line bisulphite; and by a yellow or brown coloration, or formation of resinous bodies, when mixed with a strong solution of a caustic alkali, and gently heated. Sulphurous acid and sulphites may be detected by adding a portion of the vinegar to a few fragments of zinc and a little dilute sulphuric acid, contained in a test-tube, and placing over the orifice of the tube a small cap of white, bibulous paper, moistened with a drop of solution of plumbic acetate (Fig. 59); if sul- phurous acid be present, hydrogen sulphide will be evolved, and cause the production of a black stain upon the paper. Nitric acid may be detected by adding a drop of indigo solution to a small portion of the vinegar, con- tained in a test-tube, and heating, when decoloration of the liquid will indicate free nitric acid ; if, upon heating, the original tint of the liquid remains perma- nent, a few drops of concentrated sulphuric acid should be added, and the liquid again heated, when decolora- tion of the liquid after this addition will indicate the presence of nitrates. The test may also be made by mixing carefully, in a test-tube, 2 volumes of the vine- 120 MANUAL OF CHEMICAL ANALYSIS. gar with 1 volume of concentrated sulphuric acid, and subse- quently adding 1 volume of a concentrated solution of ferrous sulphate, so as to form two layers (Fig. 60) ; a brown or violet Fig. 60. colored zone at the line of contact of the two liquids will reveal the presence of nitric acid or nitrates. Metallic impurities are detected by saturating the vinegar with hydrogen sulphide, and allowing the liquid to stand for a few hours in a closed vessel ; if a white turbidity is produced, it will indicate zinc or sulphurous acid, the latter giving rise to the depo- sition of sulphur, whereas a brown or black precipitate may indi- cate tin, lead, or copper. The precipitate may be examined for the latter metals by collecting it on a filter, washing with a little water, and digesting with ammonium sulphide ; sulphide oitin will become thereby dissolved, and, afte]' filtration, may be precipitated from its solution on the addition of an excess of hydrochloric acid as yellow stannic sulphide. The portion of the precipitate insoluble in ammonium sulphide is dissolved in a little nitric acid, and a few drops of dilute sulphuric acid added, when an ensuing white precipitate will indicate lead; after the removal of the latter, if present, by filtration, ammonia-water is added, in slight excess, when a blue coloration of the liquid will reveal the presence of copper. Other metallic impurities than those here mentioned, which may accidentally be present, may be sought for or deter- mined according to the systematic method of analysis, as described on pages 51 to 61. Acrid vegetable substances may be recognized by their odor and taste, either in the residue obtained by the direct evaporation of ACIDA. 121 a portion of the vinegar, or by previously neutralizing the latter with magnesium or sodium carbonate, filtering, and subsequently evaporating the filtrate, at a gentle heat, to about one-third of its volume. Fixed impurities may be detected by evaporating a portion of the vinegar to dryness, and igniting the residue at a gentle heat- sodium salts may then be recognized by their property of impart- ing a bright yellow color to the non-luminous flame, and cal- cium salts by dissolving the residue in a little water, acidulated with acetic acid, and testing with ammonium oxalate, when a white precipitate will be produced. This examination for fixed impurities may also serve for the detection of free mineral acids, which, if present, would render the ignited residue neutral in its action upon litmus, whilst with pure vinegar it will always be found to possess an alkaline reaction. Estimation : About 10 grams of the vinegar, accurately weighed in a flask or beaker, are diluted with about 50 cubic centimeters of water, a few drops of litmus solution added, and a normal solution of potassium or sodium hydrate, page 87, allowed to flow into the liquid from a burette, until a slight excess above that required for the perfect neutralization of the liquid has been employed, and the liquid assumes a distinct bluish tint; the excess of alkali is then inversely titrated with normal nitric acid until a permanent red coloration is produced. From the dift'erence between the number of cubic centimeters of alkali and acid employed, the number of cubic centimeters of normal alkali required for the perfect neutralization of the liquid is given, and from this the acetic strength of the vinegar may be calculated ; one cubic centi- meter of normal alkali corresponding to 0.06 gram of absolute acetic acid. As vinegar is frequently more or less colored, the transition of color of the litmus from blue to red is not always clearly percep- tible, and in this case it is better to omit the litmus entirely, titrating the excess of alkali first added by means of normal nitric acid as before, until a drop of the liquid, removed by means of a glass rod, after repeated testing, no longer produces a brown zone upon turmeric paper, which thus proves the perfect neutralization of the free alkali. Should free sulphuric or hydrochloric acid be present in the vinegar, these must be separately estimated by precipitating small portions of the vinegar with barium chloride or argentic nitrate; from the amount of barium sulphate or argentic chloride thus ob- tained, the equivalent amount of free sulphuric or hydrochloric acid may be determined, and the result of the calculation of the acetic estimation correspondingly corrected. 122 MANUAL OF CHEMICAL ANALYSIS. ACIDUM ACETICUM. Acetic Acid. Ger. Essigsaure ; Fr. Acide acetique ; Sp. Acido acelico. C,Hp, = CH3-CO-OH ; 60. Acetic acid, when free from water, forms at or below 15° C. (59° F.) large, colorless, transparent, tabular crystals of the rhom- bic system (Glacial Acetic Acid), which melt at 17° C. (62.6° F.). to a colorless, limpid liquid, of a pungent odor, and strongly acid reaction. The acid containing mucli water does not crystallize even at 0° C. (82° F.). The specific gravity of the pure liquid acid is 1.056 to 1.058, at 15° C. (59° F.); it bo'ils at 118° C. (244.4° F.), emitting \erj pungent and acid, inflammable vapors, which burn with a blue flame. Acetic acid is miscible in all proportions with water, alcohol, and ether, and dissolves albumen, fibrin, camphor, and many resins, gum-resins, and essential oils ; diluted with water, it forms the commercial and medicinal acetic acids, which maintain the cha- racter of acetic acid as long as the admixture of water does not exceed 18 to 19 per cent., beyond which dilution the acid loses more or less the character of a strong acid, and its solvent prop- erties for the above mentioned substances. In addition to the glacial acid (Acidum Aceticum Glaciale), two strengths of acetic acid are officinal: Acidum Aceticum of the spec. grav. of 1.048 (1.044 British Pharmac, 1.064 Pharm. German.), and Acidum Aceticum Dilutum of the spec. grav. of 1.0083 (1.006 British Pharmac, 1.041 Pharmac. German.). The strong acid of 1.048 spec. grav. contains 36 per cent, of absolute acetic acid, or 30.6 per cent, of acetic anhydride, and 6 grams of it require for neutralization 86 cubic centimeters of volumetric solution of potassium or sodium hydrate, or 100 parts are neutral- ized by 60 parts of crystallized potassium bicai'bonate ; the diluted acid of 1.0083 spec. grav. contains 6 per cent, of absolute acetic acid, corresponding to 5.10 per cent, of acetic anhydride, and 24 grams of it require for neutralization 24 cubic centimeters of volumetric solution of potassium or sodium hydrate, or 100 parts are neutralized by 10 parts of crystallized potassium bicarbonate. Acetic acid is recognized in its soluble salts, or in the free state, after previous neutralization with an alkali, by the production of a deep-red color on the addition of a few drops of solution of ferric chloride ; this coloration is discharged on strongly acidu- lating the solution with sulphuric acid, or by boiling, in the latter case the iron being completely precipitated as a basic salt. The acid may also be recognized, when not too dilute, by the odor of acetic ether, when heated with a mixture of equal parts of alcohol and concentrated sulphuric acid. ACIDA. 123 Examination : Glacial acetic acid may be tested for water by mixing 10 parts of it with 1 part of fresh or unaltered lemon oil, when a perfectly clear solution should be formed. A much better method, how- ever, for the determination of the presence of small quantities of water consists in mixing equal parts of the acid and carbon bisul- phide in a small dry test-tube, which is inclosed in the hand; when maintained at this temperature for a few moments, a per- fectly clear mixture should result, whilst the smallest amount of water will produce a cloudiness in the liquid. The other tests of purity are the same as those applied for the examination of the diluted acids, as follows: Empyrtiumatic substances will be rendered evident by their odor, and, when present in but small amount, may be also recog- nized by neutralizing a little of the acid with solution of potas- sium hydrate, and subsequently tingeing the solution faintly with potassium permanganate ; the color should Fig. 61. not be sensibly changed by standing five minutes at the ordinary temperature. Organic impurities may be recognized by an ensuing dark coloration, when the acid is mixed with an equal f volume of concentrated quently heated to boiling. volume of concentrated sulphuric acid, and subse- i Sulphuric and hydrochloric acids may be detected by an ensuing white precipitate, when- the diluted acid is y tested, in separate portions, with barium nitrate or chloride, and with argentic nitrate. Sulphurous- acid is indicated by a greenish colora- tion, when a little of the acid is heated with a few drops of solution of potassium bichromate; it may also be recognized by adding a portion of the acid to a few fragments of zinc and a little dilute sulphuric acid, contained in a test-tube, and placing over the orifice j. of the tube a small cap of white, bibulous paper, moist- i ened with a drop of solution of plumbic acetate (Fig. f 61); if sulphurous acid be present, hydrogen sulphide ." will be evolved, and cause the production of a black 1 r stain upon the paper. r* Nitric acid may be detected by the decoloration of jj" Jl the liquid, when the acid is tinged slightly blue with "^^"^ indigo solution, and heated; or by mixing the acid with an equal volume of concentrated sulphuric acid, and subse- quently carefully adding to the cooled mixture a concentrated solution of ferrous sulphate, so as to form two layers (Fig. 62); a brown or reddish-brown zone at the line of contact of the two liquids will reveal the presence of nitric acid. Metallic impurities are recognized by a turbidity or precipitate upon saturating the acid with hydrogen sulphide, or upon subse- 124 MANUAL OF CHEMICAL ANALYSIS, quent siipersaturation with ammonia- water. If a brown or black precipitate is produced by hydrogen sulphide, it may indicate Fig. 63. tin, lead, or copper, and may be further examined by collecting it on a filter, washing with a little water, and digesting with am- monium sulphide ; sulphide of tin will become thereby dissolved, and, after filtration, may be reprecipitated from its solution by the addition of an excess of hydrochloric acid as yellow stannte sulphide. The portion of the precipitate insoluble in ammonium sulphide is dissolved in a little nitric acid, and a few drops of dilute sulphuric acid added, when an enSuing white precipitate will indicate lead; after the removal of the latter, if present, by filtration, ammonia-water is added in slight excess, when a blue coloration of the liquid will reveal the presence of copper. If the acid, after saturation with hydrogen sulphide, and filtering, yields a black precipitate upon subsequent aupersaturation with am- nionia-water, the presence of iron is indicated. ■ Pure acetic acid should leave no residue upon evaporation ; a b^"ownish-colored residue would indicate foreign organic matters, and, upon subsequent ignition, a permanent white residue will indicate salts of the inorganic bases, sodium, calcium, etc. If the residue, when heated on a platinum wire, imparts a bright-yellow color to the non-luminous flame, sodium salts will be indicated, and, when subsequently dissolved in water, the solution acidulated with a few drops of acetic acid, and tested with ammonium oxa- late, an ensuing white precipitate will indicate calcium salts. Estimation : In consequence of the existing anomaly between the specific gravity of acetic acid and its strength, the hydrometer does not ACIDA. 125 always give a correct indication of the latter ; the specific gravity being increased to a certain extent upon the dilution of the acid, ill consequence of contraction, as will be seen by reference to the subjoined table. Thus an acid containing from 77 to 80 per cent, of absolute acetic acid has the highest specific gravity, 1.0748 at 15° C. (59° F.), above which strength it again decreases similarly as upon dilution, so that the anhydrous acid and an acid containing 43 per cent, of absolute acid have the same specific gravity at 15° 0. (59° F.), viz., 1.055. It will be seen, however, that a specific gravity below 1.0552 can only apply to an acid containing less than 43 per cent, of absolute acetic acid. The strength of acetic acid may be determined by observing the exact quantity of crystallized potassium bicarbonate required to saturate a known weight of the acid, and by subsequent equa- tion, see page 122 ; or by the following process of volumetric analysis : Five grams of the acid, accurately weighed in a flask or beaker, are diluted with about 10 times its volume of water, a few drops of litmus solution added, and a normal solution of potassium or sodium hydrate (page 87) allowed to flow into the liquid from a burette until, with constant stirring, the liquid assumes a distinct bluish tint. From the number of cubic centimeters of alkali solution required for the exact neutralization of the liquid, the percentage strength of the acid may be readily calculated : 1 cubic centimeter of normal alkali corresponding to 0.06 gram of absolute acetic acid. Instead of the employment of a normal solution of potassium or sodium hydrate, as above described, very accurate results may also be obtained by the addition of so much of a measured volume of baryta-water of known strength to a weighed quantity of acid, as to be slightly in excess of that required for its exact neutraliza- tion, and subsequently determining the excess employed by means of a normal acid ; the point of exact neutralization being deter- mined by means of turmeric paper, which, by the delicacy of its reaction with baryta-water, will indicate the slightest excess of the latter by the production of a brown coloration. From the amount of baryta-water, of previously ascertained strength, re- quired to neutralize a definite amount of acid, the percentage strength of the acid may be readily calculated: 1 part of barium hydrate, Ba(0H)2, corresponding to 0.7017 part of absolute acetic acid, C^H^O, ^2" 126 MANUAL OF CHEMICAL ANALYSIS. Table of the quantity hy weight of absolute Acetic Acid contained in 100 parts hy weight of aqueous Acetic Acid of different specific gravities (^Oudetnans). Temperature at 15° C. (59° F.). Speciac Percent, of Specific Per cent, of Specific Percent, of Specific Per cent, of gravity. acetic acid. gravity. acetic acid. gravity. acetic acid. gravity. acetic acid. 1.0007 1 1.0363 26 1.0623 51 1.0747 76 1.0033 3 1.0375 27 1.0631 52 1.0748 77 1.0037 3 1.0388 38 1.0638 53 1.0748 78 1.0053 4 1.0400 39 1.0646 54 1.0748 79 1.0067 5 1.0412 30 1.0653 55 1.0748 80 1.0P83 6 1.0434 31 1.0660 56 1.0747 81 1.0098 7 1.0436 32 1.0666 57 1.0746 83 1.0113 8 1.0447 33 1.0673 58 1.0744 83 1.0137 9 1.0459 34 1.0679 .59 1.0743 84 1.0143 10 1.0470 35 1.0685 60 1.0739 85 1.0157 11 1.0481 36 1.0691 61 1.0736 86 1.0171 12 1.0493 37 1.0697 62 1.0731 87 1.0185 13 1.0.502 38 1.0703 63 1.0736 88 1.0200 14 1.0513 39 1.0707 64 1.0730 89 1.0314 15 1.0.583 40 1.0712 65 1.0713 90 1.0388 16 1 0533 41 1.0717 66 1.0705 91 1.0342 17 1.0543 42 1.0721 67 1 0696 93 1.0356 18 1.0552 43 1.0735 68 1.0686 93 1.0370 19 1.0568 44 1.0729 69 1.0674 94 1.0384 30 1.0571 45 1.0783 70 1.0660 95 1.0298 31 1.0580 46 1.0737 71 1.0644 96 1.0311 33 1.0589 47 1.0740 73 1.0635 97 1.0334 33 1.0598 48 1.0742 73 1.0604 98 1.0337 34 1.0607 49 1.0744 74 1.0580 99 1.0350 25 1.0615 50 1.0746 75 1.0553 100 ACIDUM ARSENIOSUM. ACIDUM ARSENICOSUM. ARSENICUM ALBUM. Arsenious Acid. White Arsenic. Arsenious Oxide. Ger. Arsenige Siinre ; Fr. Acide arsenieux ; Sp. Acido arsenioso. As,0.;* 197.8. A heavy, wliite solid, occurring either in transparent or semi- transparent masses, which usually have a striated appearance, or as a white, crystalline powder. In the crystalline condition it is dimorphous, presenting either the form of octahedra or tetrahedra of the regular system' (Fig. 63), which are obtained by the con- densation of its vapor under ordinary circumstances, or by crys- * According to the determinations of tlie vapor density of arsenious oxide, its molecular composition is more correctly expressed by the formula AsjO^. ACIDA. 127 tallization from its solution in water or hydrochloric acid : or the form of rhombic prisms, which are occasionally deposited in the roasting furnaces, and are also obtained when hot saturated solu- tions of arsenious acid, in solution of potassium hydrate or arsenic acid, are allowed to evaporate slowly. When freshly prepared by sublimation it forms heavy, trans- parent, glassy cakes, with a smooth conchoidal fracture, and has a spec. grav. of 3.738; this becomes gradually opaque and porcelain- liise by passing into the crystallir^e state, -which change proceeds from the surface toward the interior; at the same time its specific gravity is slightly diminished (3.689), and its solubility in water increased. In cou- Fig. 63. sequence of- the simultaneous occurrence of the amorphous and the crystalline modi- fications, and the difference in their solu- bility, the statements of the solubility of arsenious acid in water are slightly at variance. The crystalline modification is soluble in about 9 parts of water at 15° C. (59° F.), while the amorphous variety re- quires 25 parts of water for solution; but saturated solutions with cold water are very slowly formed. It is slowly but completely soluble in 15 parts of boiling water, but very sparingly soluble in alcohol ; the amorphous variety requiring 94 parts, and the crystalline variety 400 parts of absolute alcohol for solution. It is insoluble in ether, but freely soluble in the alkaline hydrates and in warm diluted acids, especially in hydrochloric and tartaric acids, from which latter solutions it is deposited, on cooling, in small transparent octa- hedral crystals. It is also soluble in warm concentrated glycerin, from which solution it gradually separates by absorption of water, or at once upon the addition of water. The aqueous solution of arsenious acid has a feeble acid reac- tion on litmus; it yields a white precipitate with lime-water, which is soluble in ammonium chloride; and, after acidulating with hydroclilorie acid, a yellow precipitate with hydrogen sulphide, which is soluble in ammonia-water or in ammonium sulphide, but insoluble in hydrochloric acid. Argentic nitrate and cuprio sul- phate produce only a turbidity in an aqueous solution of arsenious acid; upon exact neutralization with ammonia- water, however, a yellow precipitate is formed with the former reagent, and a bril- liant green one with the latter, both precipitates being soluble in an excess of ammonia- water or of acid. Arsenious acid, when heated in an open tube, volatilizes at about 218° C. (424.4° F.) without fusion, forming a colorless, in- odorous vapor, which condenses, on cooling, in small, transparent, and brilliant, octahedral crystals. When heated in contact with 128 MANUAL OF CHEMICAL ANALYSIS. reducing agents, such as a mixture of equal parts of fused sodium carbonate and potassium cyanide, or with carbou, the acid is re- duced to metallic arsenic, which, when the reduction is performed in a glass tube, sublimes and is deposited in the form of a bright metallic incrustation, emitting at the same time a peculiar and characteristic odor somewhat similar to garlic. For the reduction of arsenious acid by means of the previouslj'- mentioned mixture of sodium carbonate and potassium cyanide, the form of tube shown in Fig. 64 is the most suitable. Fig. 64. The arsenious acid is first brought into the bulb of the tube, and the powdered and perfectly dry mixture of equal parts of sodium carbonate and potassium cyanide then added in such an amount that the bulb of the tube shall be filled to not more than half its capacity. The upper portion of the tube should be made perfectly clean by means of a narrow strip of bibulous paper or a small camel's-hair brush, and the bulb at first gently heated, in order to expel all traces of moisture, which may also be removed by means of bibulous paper, after which the contents of the tube are heated to fusion, when the reduced arsenic will form a bright metallic mirror in the narrow part of the tube. ACIDA. 129 This method of reduction is also applicable to the arseniates and to the yellow arseuious sulphide. The reduction of arsenious acid by carbon is best effected in a small tube, drawn out at one end to a narrow point, as shown in Fig. 65. Fig. 65. The small particles of arsenious acid are placed in the point of the tube, and above them a splinter of previously ignited wood- charcoal, as shown in the figure. The portion of the tube con- taining the charcoal is first heated to redness, maintaining the tube in a nearly horizontal position, after which the tube is grad- ually inclined, and finally brought into a nearly vertical position, so that the point of the tube becomes also heated. The vapor of the arsenious acid in passing over the red-hot carbon is reduced to the metallic state, and deposited above the carbon in the form of a bright metallic mirror. After cooling, the carbon may be removed from the tube, and the metallic arsenic heated for itself, when, if the amount be quite small, it will be oxidized for the most part in the act of volatilization to arsenious oxide, forming a white sublimate of small, shining, octahedral crystals in the upper part of the tube, and readily distinguishable hy the aid of a lens. A solution of arsenious acid in contact with nascent hydrogen, as developed by the action of dilute sulphuric acid on metallic zinc or magnesium, gives rise to the formation of hydrogen arse- nide, which, when ignited, burns with a bluish-white flame, and emits, when considerable arsenic is present, dense white clouds of arsenious oxide ; when a piece of cold white porcelain is held in the flame, shining brown or black spots of metallic arsenic are deposited (Marsh's test). For further details relating to the appli- cation of this test, see pages 33 to 36. When a solution of arsenious acid is mixed with an excess of concentrated hydrochloric acid, and a piece of bright copper-foil or wire immersed in the liquid, and boiled, a dark gray metallic film, consisting of a compound of copper and arsenic, CUjAs^, is deposited upon the copper. If the copper-foil or wire be now removed from the liquid, well washed with water, carefully dried, and then strongly heated in a perfectly dry test-tube, the arsenic will become volatilized, and at the same time oxidized to arsenious acid, forming a sublimate of small, brilliant, octahedral crystals in the upper part' of the tube (Reinsch's test). When the same test is made as the preceding, with the employ- 9 130 MANUAL OF CHEMICAL ANALYSIS. ment of pure tin-foil, or stannous chloride, instead of copper, the tin becomes likewise coated with arsenic, and at the same time a more or less voluminous brown deposit is formed (JBettendorfs test). To insure success, concentrated hydrochloric acid, and a very small quantity of the arsenical solution must be employed, as the presence of much water prevents the reaction. Examination of Powdered WMte Arsenic : When a small portion of the powder is heated in a glass tube, it should be completely volatilized, and form a colorless subli- mate, which will prove its freedom from admixture with metallic arsenic or arsenious sulphide ; and when dissolved in warm con- centrated sulphuric acid, it should form a perfectly colorless solu- tion, which will prove the absence of organic substances. Earthy admixtures are recognized by a non-volatile residue when a little of the white arsenic is strongly heated on platinum- foil, or by an insoluble residue when heated with a solution of potassium hydrate or hydrochloric acid. When a residue is ob- tained by either of these tests, it is collected on a filter, washed with a little water, and, after drying, mixed and fused in a por- celain crucible with four times its weight of a mixture of equal parts of exsiccated sodium and potassium carbonates; the obtained fused mass is triturated and boiled with a sufficient quantity of water, and the filtered solution, after acidulation with nitric acid, tested with barium nitrate for sulphates (calcium and barium sul- phates). The residue on the filter is washed with water, and treated with warm diluted hydrochloric acid, and the filtrate sub- sequently tested with sodium sulphate for barium, and, in another portion, neutralized with ammonia-water, with ammonium oxalate for calcium. Ammonium salts will be recognized by the development of the odor of ammonia, when a small portion of the arsenious acid is heated, in a test-tube, with an excess of a strong solution of potas- sium hydrate, and by the formation of white fumes when a glass rod, moistened with acetic acid, is subsequently held over the orifice of the tube. Chlorides may be detected by treating a portion of the arsenious acid with concentrated nitric acid until complete solution is effected, and red nitrous fumes cease to be evolved, and subse- quently adding to the acid solution, slightly diluted with water, a few drops of solution of argentic nitrate, when a white precipi- tate, soluble in ammonia- water, will prove the presence of chlo- rides. Estimation : I. One gram of arsenious acid, As^Oj, when dissolved in warm diluted hydrochloric acid, yields, upon complete precipitation with hydrogen sulphide, a precipitate of arsenious sulphide, As^S,, which, when collected upon a tared filter, washed, and dried, should weigh 1.24 grams. ACIDA. 131 II. One gram of arsenious acid, AsjOj, is dissolved, by the aid of heat, in dilute hydrochloric acid, and potassium chlorate, in small portions, from time to time added, finally continuing the heat until all free chlorine is expelled; the arsenious acid is thus converted into arsenic acid, which, after dilution with water, may ■ be precipitated by test magnesium mixture, as crystalline, ammo- nio-magnesium arseniate, NH^MgAsO^ + 6HjO. The precipitate, after standing for twenty-four hours, is collected upon a tared filter, .which has been previously dried at 105° 0. (221° ]?.), washed with a mixture of three parts of water and one part of ammonia-water, and dried first at 100° 0. (212° F.), and finally at 105° C. (221° F.), until of constant weight. Its composition is then represented by the formula NH^MgAsO^ + JH^O, and 100 parts correspond to 39.47 parts of metallic arsenic, or 52.11 parts of arsenious acid, As fi^ III. The estimation of arsenious acid may also be very accu- rately and quickly accomplished volumetrically by the following process : 0.1 gram of the acid is accurately weighed, and dissolved in 20 cubic centimeters of boiling water, with the addition of about one gram of pure sodium bicarbonate. To the solution, when cold, a little mucilage of starch is added, and a standard decinormal solution of iodine, page 98, allowed to flow into the liquid from a burette until, after well stirring, a permanent blue coloration is produced. The amount of pure iodine equivalent to the number of cubic centimeters employed may then be calcu- lated, and therefrom its equivalent in pure arsenic trioxide ; 508 parts of iodine being equivalent to 198 parts of arsenious oxide, as shown by the equation : 21, + As,03 + 5HjO = 4HI -f 2H3ASO,, 508 198 or as follows : 2]Sra,HAsO, + 21, -f 2Na,C03 = 2Na,HAsO, + 4NaI + 2C02- 508 198 The calculation ma,j also be made with the consideration that one cubic centimeter of the volumetric solution of iodine, if exactly decinormal, corresponds to 0.00495 gram of pure arsenious oxide, As^O,. The United States Pharmacopceia directs that if 0.247 gram of arsenious acid be dissolved, with 0.5 gram of sodium bicarbonate, in boiling water, the solution should decolorize not less than 48.5 cubic centitoeters of the volumetric solution of iodine (corespond- ing to at least 97 per cent, of pure arsenious acid). 132 MANUAL OF CHEMICAL ANALYSIS. Separation and Detection of Arsenic in Forensic Investigations. — Arsenious acid, from the fact of being one of the more commonly employed and readily obtainable poisons, is sometimes the cause of accidental or intentional poisoning, and therefore becomes not unfreqiiently the object of search in forensic investigations. In consequence of the sparing solubility of arsenious acid in aqueous liquids, it may frequently, in cases of poisoning, be found adher- ing to the coatings of the stomach or intestines, or in the vomited matters. In all cases, however, it should be carefully searched for among the folds and in the inflamed portions of the stomach and intestines, when, if thus found, and after purification by washing with a small amount of cold water, it may be at once identified by subjecting it to the several tests already mentioned. Should the direct isolation of the arsenious acid in substance prove unsuccessful, other methods for ascertaining its presence must be then resorted to. The organic matters, as finely divided as pos- sible, are brought into a flask or retort provided with a condenser and well cooled receiver, fused common salt or pure rock salt, and a quantity of pure sulphuric acid not sufficient to decompose the entire amount of the salt, are then added, and the mixture subjected to distillation (Fig. 66). In the presence of arsenic, the Fig. 66. very volatile and poisonous arsenic trichloride, AsClj, is formed, which, in the presence of water, is decomposed into arsenious and hydrochloric acids : 2ASOI3 + 3H,0 = As^O, + 6HC1. The dis- tillate thus obtained, which contains the arsenic in quite a pure state, may be at once precipitated by hydrogen sulphide, or em- ployed in part for the application of the previously described tests. The above method for the separation of the arsenic is only ACIDA. 133 applicable, however, when present in the form of arsenious acid or its salts ; and in order to ascertain the presence of arsenical compounds ift general, which may possibly be accompanied also by other poisonous metallic compounds, the following method may be resorted to. The substance under examination, in the finest possible state of division, is first deprived as completely as possible of organic matter, an operation which is most effectually and conveniently accomplished by first placing it in a large porcelain dish, and diluting it with sxifficient water to form a thin paste. Concen- trated hydrochloric acid, equal in amount to the volume of sub- stance, and a few grams of potassium chlorate are then added, and the mixture heated upon the water-bath ; the addition of potas- sium chlorate being from time to time renewed, and the evapo- rated water or expended acid being also renewed, if necessary, until finally the mixture assumes the form of a thin, homogeneous, yel- lowish liquid. A small additional quantity of potassium chlorate may now be added, and the mixture again heated until the odor of chlorine entirely disappears. The solution, which should still possess a strong acid reaction, is then filtered into a small flask, and, after heating to about 60-80° 0. (140-176° ¥.), saturated with hydrogen sulphide, the flask loosely stoppered, and allowed to stand in a warm place for about twenty-four hours. If the odor of the gas should have disappeared after standing, the solu- tion must be again warmed, and subsequently again saturated with hydrogen sulphide, until complete precipitation is finally effected. The precipitate thus obtained is collected on a filter, washed with water previously saturated with hydrogen sulphide, and, in con- sideration of the possible presence of the sulphides of other metals than arsenic, digested with ammonium sulphide. The solution thus obtained is brought upon a filter, and the filtrate, together with the washings, evaporated in a porcelain capsule, by the aid of a gentle heat, to dryness. The residue is then treated with concentrated nitric acid, and the obtained .solution evaporated at a gentle heat until the residue no longer shows a dark coloration, but in a moist condition appears of a yellowish hue. A small quantity of pure sodium hydrate, sufficient to neutralize the free acid, is then added, the mixture evaporated to dryness, subse- quently mixed with the proper quantity of a mixture of one part of fused sodium carbonate and two parts of sodium nitrate, and brought into a small porcelain crucible, and. with a gradually increased temperature, heated to fusion. The fused mass, which will contain the arsenic in the form of soluble sodium arseaiate, is treated with water, the soluble portion filtered off", and the re- sidue washed with water containing a little alcohol, when any antimony present will remain behind as insoluble sodium antimo- niate. To the arsenical solution a small quantity of sodium bicar- bonate is added, or preferably carbonic acid gas is passed into the 134 MANUAL OF CHEMICAL ANALYSIS. solution, in order to separate any traces of tin which, may have become dissolved, and the solution filtered. The solution is now strongly acidulated with dilute sulphuric acid, and carefully evap- orated, at a gentle heat in a porcelain capsule, until vapors of sulphuric acid begin to appear, in order to effect the removal of the nitric and nitrous acids. The residue in the capsule, which will form a colorless, strongly acid liquid, is to be diluted with water, and is then adapted for the application of the several tests. If a quantitative estimation of the arsenic is desired, it maybe either precipitated from the warm solution directly, or, after previous re- duction by means of sulphurous acid, as arsenic trisulphide, and weighed as such ; or precipitated in the form of the crystalline ammonio-magnesium arseniate by the addition of test magnesium mixture. 100 parts of arsenic trisulphide, As^Sj, when dried at 100° C. (212° F.), correspond to 80.49 parts of arsenious oxide, ASjO^, or 61 parts of metallic arsenic; and 100 parts of ammonio- magnesium arseniate, NH^MgAsO^-f IH^O, dried at 105° 0. (221° F.), correspond to 52.11 parts of arsenious oxide, As^Oj, or 39.47 parts of metallic arsenic. Detection of Arsenic in Coloring-matters, Wall-paper, Fabrics, etc. — The employment of arsenic in the preparation of some of - the aniline colors, and the application of Scheele's Green (cupric arsenite) or Schweinfurth Green (cupric arsenite and acetate) in painting, paper staining, etc., often renders the examination of various materials and products for arsenic necessary or desirable. The following method, which is simple and accurate, will admit of general application : The material to be examined is finely divided, and, when pos- sible, the coloring-matter separated from the material (wood, paper, cotton, wool, silk, etc.) to which it is attached. It is then brought into a porcelain capsule, concentrated hydrochloric acid and a little potassium chlorate added, and gradually heated upon the water-bath. The organic substances will thereby become com- pletely destroyed and dissolved, or, after the complete oxidation of the coloring-matter, may be mechanically removed from the capsule. A little potassium chlorate is occasionally added to the solution, which is further heated on the water-bath, and finally evaporated to dryness, to effect the complete removal of the free chlorine. The residue is then .dissolved in water with the addi- tion of a little dilute sulphuric acid, and finally examined in Marsh's apparatus, as described on pages 33 to 86. Another method consists in digesting the material to be ex- amined, or the coloring-matter removed therefrom, with hydro- chloric acid, spec. grav. 1.12, for about one hour, subsequently warming gently, and finally heating a portion of the liquid thus obtained, in a test-tube, with a concentrated solution of stannous chloride, or a piece of pure tin -foil ; if arsenic be present a brown coloration, or a brownish-black precipitate, will be produced. As ACIDA. 135 a confarmative test the precipitate may be collected on a small filter, washed with a little dilute hydrochloric acid, subsequently dissolved in nitric acid, and the filtered solution evaporated at a gentle heat, in a porcelain capsule, to dryness. The residue, dis- solved in a little water, is then adapted for further examination by the application of Marsh's test. If the article under examination is suspected to contain Schwein- furth or Scheele's Green, a small portion may be digested with ammonia-water, which will thereby assume a deep blue color. A portion of the ammoniacal solution, after acidulation with dilute sulphuric acid, may then be tested in Marsh's apparatus for arsenic, and anpther portion, acidulated with hydrochloric acid, tested with potassium ferrocyanide, when a reddish-brown coloration will reveal the presence of copper. ACIDUM BENZOICUM. ACIDUM BENZOICUM SUBLIMATUM. FLOHES BENZOES. Benzoic Acid. Phenyl-formic Acid. Benzol-carbonic Acid. Ger. Benzoesaiire ; Fr. Acide benzoique ,; Sp. Acido benzoico. C,H,0, = C,H,-CO-OH ; 122. Colorless, soft, feathery needles, or laminee, of a silky lustre, inodorous when cold and pure, but developing a faint odor when gently warmed. The agreeable aromatic odor of the officinal benzoic acid is due to tracer of essential oil. When derived from solutions, benzoic acid forms colorless, pearly needles or laminae of six-sided prisms. When warmed, the acid begins to volatilize below 100° C. (212° F.), and melts at 121 C. (249.8° F.), forming a colorless liquid, which, on cooling, solidifies to a mass of radi- ating crystals ; at 145° C. (293° F.) it volatilizes freely, and at 249-250° C. (480.2-482° F.) boils, without decomposition,' emitting acrid and irritating, inflamable vapors. When heated with water, it is also volatilized to a certain extent with the aqueous vapor ; and when heated with an excess of freshly slaked lime, benzol is evolved. Benzoic acid is soluble in 500 parts of water at 15° C. (59° F.), and in 15 parts of boiling water, the solutions possessing an acid reaction ; it is also soluble in 3 parts of cold, and 1 part of boiling, alcohol, in 3 parts of ether, 7 parts of chloroform, and freely solu- ble in carbon bisulphide, warm petroleum benzin, glycerin, and many volatile and fatty oils, as also in solutions of the alkaline hydrates. Concentrated sulphuric acid dissolves benzoic acid readily, without decomposition, and without coloration, if pure, the officinal acid producing a slight brownish coloration ; on the addition of water it is precipitated unchanged. A concentrated aqueous solution of benzoic acid, when carefully neutralized by 136 MANUAL OF CHEMICAL ANALYSIS. ammonia-water, produces, on the addition of a solution of ferric chloride or sulphate, a reddish-yellow or flesh -colored precipi- tate of basic ferric benzoate, which dissolves on the addition of a small quantity of warm hydrochloric acid, and, upon cooling, benzoic acid is again separated, re-dissolving on the addition of alcohol or ether. Pure benzoic acid does not melt under water, but certain im- purities, even when present in but small amount, impart to it this property, at the same time rendering it more freely soluble in water, and causing the formation of smaller crystals. These obser- vations formerly led to the incorrect acceptance of the existence of different modifications of the acid, as derived from different sources; a supposition which is not in harmony with the present views of the constitution of benzol derivatives, according to which, but one mono 'Substitution product of benzol is capable of existence, whilst the error of the conclusion may be also demon- strated by the purification of such an acid, either by distillation with aqueous vapor, treatment with potassium permanganate, or other means, when a product possessing all the physical and chemical properties of the pure acid will be obtained. Examination : Hippuric acid, as is well known, is resolved by the action of hydrochloric acid, and other agents, into benzoic acid and glyco- coll, and much benzoic acid is obtained from this source. CH— CO-OH I -f H„0 = CH„(]SrH,)00-OH + O^H.-CO-OH JSTH— CO-C.H, Hippmic acid. Glycocoll. Benzoic acid. Such acid, although chemically identical with the acid obtained from benzoin or other sources, is usually accompanied by an un- pleasant, persistent odor, which renders it objectionable for phar- maceutical or medicinal purposes unless further purified, or the characteristic and agreeable odor of the officinal acid subsequently imparted to it by mixing with a portion of benzoin, and subjecting it to sublimation. Hippuric acid may be distinguished from, or recognized in, ben- zoic acid, by heating, in a test-tube, a small portion of the acid with about twice its weight of dry potassium hydrate, and a little water ; if hippuric acid is present, it will be indicated by the odor of ammonia, as also by the formation of white vapors, when a glass rod, moistened with acetic acid, is held over the orifice of the tube. It may also be recognized by forming a very dark colored or black solution when warmed with concentrated sulphuric acid ; and when heated for itself in a glass tube an odor resembling that of bitter almond oil is produced, accompanied by the final pro- duction of a black, carbonaceous, or resinous like residue. Chloro-lemoic acid may be recognized by mixing a small por- tion of the acid with a little recently ignited and moistened cupric ACIDA. 137 oxide, and introducing the mixture, contained on the looped end of a platinum-wire, in the non-luminous flame; a green or bluish-green color imparted to the flame would indicate a con- tamination with chlorinated compounds. Cinnamic add may be detected by the development of the odor of bitter-almond oil, when a small portion of the acid is gentlv heated in a test-tube, with an equal quantity of potassium bi- chromate and sulphuric acid, and allowed to cool ; or when gently heated with about an equal quantity of potassium permanganate and a little water. Salicylic acid may be detected by the production of a violet coloration upon the addition of a drop of a solution of ferric chlo- ride to the aqueous solution of the acid. Boric acid may be recognized by the green coloration of the flame of burning alcohol, previously saturated with the acid. Oxalic acid may be readily detected by its much greater solu- bility in cold water, and, when subsequently neutralized by ammonia-water, a white precipitate of calcium oxalate will be pro- duced on the addition of a solution of calcium sulphate. Mineral substances, not readily volatilizable or soluble in alco- hol, may at once be detected by a residue left on volatilization, as well as upon solution of the acid in alcohol. If any fixed residue is left, it may be dissolved in warm water acidulated with nitric acid, and tested with barium nitrate for sulphates, and with ar- gentic nitrate for chlorides, and, after neutralization with ammonia- water, with the latter reagent for phosphates. ACIDUM BORICTJM. Boric Acid. Ortho-borio Acid. Boracic Acid. Ger. Borsaure ; Fr. Acide boracique ; Sp. Acido borioo. H,B03 = B(0H),,; 62. Colorless, translucent, shining, six-sided laminee (Fig. 67) belong- ing to the tri-clinic system, permanent in the air, and somewhat unctuous to the touch. Its specific gravity is 1.4347 at 15° 0. (59° F.). Fig. 67. Boric acid is soluble in 25 parts of cold, and in 3 parts of boiling water. The solu- ^,^^f^ tion has but little taste; it feebly affects blue _ - <^ litmus-paper, but imparts to turmeric-paper a reddish-brown tint, which becomes more distinct after drying.* The acid is also soluble in 15 parts of cold, "^ and in 5 parts of boiling, alcohol, and the • * A similai- coloration is produced by alkalies with turmeric paper, but the color disappears on the addition of hydrochloric acid, whilst that produced by boric acid remains unaltered. 138 MANUAL OF CHEMICAL ANALYSIS. solution burns, when ignited, with a flame tinged with green. The same green tint may be observed when the acid is dissolved in warm concentrated glycerin, the latter heated to boiling, and the vapors then ignited, or when a small portion of the acid, con- tained on the looped end of a platinum-wire, is brought into the fusion zone of a non-luminous flame. The salts of copper and thallium, as also some organic compounds, impart a green colora- tion to the flame, but these are usually readily distinguished by other physical or chemical characters. When boric acid is heated to 100° C. (212° F.), it parts with 1 molecule of water of constitution (not crystallization), and is con- verted into meta-horic acid, BO(OH) ; if heated for some time at 140° 0. (284° F.), ptjro-honc acid, B.O/OH)^ is formed, which may be considered as produced from 4 molecules of the ordinary or ortho-boric acid, by the abstraction of 5 molecules of water, 4B(0H),— 5H20 = B,6/OH),. This acid, which is dibasic, forms very stable salts, of which the ordinary borax may be taken as a representative. If boric acid be heated to redness?, a further de- composition takes place, by which from 2 molecules of the acid 'd molecules of water are abstracted (corresponding to a loss of 43.55 per cent, in weight), and boron trioxide, B^Oj, is obtained. 2B(OH)3-3H,0=BA. This forms a glassy, transparent, and very hygroscopic solid, which readily unites with water to form boric acid. It possesses the property of dissolving most metallic oxides at a red heat, which frequently impart characteristic colors to the mass, and thus render it, or the more commonly employed borax, a valuable agent in blow-pipe analysis. Examination : A small portion of the cry.=!tals of boric acid is added to five times its weight of water in a test-tube, and heated ; a clear and complete solution must take place, and, when part of the hot solu- tion is dropped into alcohol, no turbidity or precipitate must ensue; otherwise the presence of admixtures insoluble or less soluble in water or alcohol is indicated. It should dissolve in warm concentrated sulphuric acid without disengagement of gas bubbles, and without coloration, and, when cold, the solution should afford no coloration upon the addition of a saturated solution of ferrous sulphate, which would prove the absence of nitrates. Metallic impurities may be recognized in the aqueous solution of the acid by an ensuing dark coloration or a precipitate when saturated with hydrogen sulphide, or upon the subsequent addition of ammonium sulphide. Calcium and Sodium Salts. — The former may be detected in the aqueoug solution of the acid by an ensuing white precipitate when tested with ammonium oxalate, and the latter by heating a frag- ACIDA. 139 ment of the acid, contained on the looped end of a platinum-wire, in the noa-luminous flame; a persistent yellow color imparted to the flame would indicate the presence of sodium salts or borax. Chlorides and sulphates are detected in the aqueous solution, acidulated with nitric acid, by white precipitates, when tested with argentic nitrate and barium nitrate respectively. Estimation : The estimation of free boric acid may be accomplished by adding an accurately weighed quantity of pure, fused sodium carbonate (about 2 parts of carbonate to 1 part of acid), evapo- rating to dryness, after the addition of the carbonate, if the acid should be in the form of solution, finally heating the residue to the point of fusion, and, when cold, determining its weight. The amount of carbonic acid contained in the fused mass is now deter- mined, as described on page 86, and, from the difference in the amount of carbonic acid contained in the weighed quantity of carbonate taken, and that determined after fusion with the acid, the amount of carbonic acid expelled by the boric acid is ascer- tained, from which the equivalent amount of boric acid may readily be calculated. ACIDUM CARBOLICUM. Carbolic Acid, or Phenic Acid. Phenol. Phenylic Alcohol. Hydroxyl-benMl. Ger. Carbolsaure ; Fr. Acide carbolique ; Sp. Acido carb61ico. C,H„0 = CeH,-OH; 94. Long, colorless, prismatic needles, or crystalline masses, possess- ing a peculiar distinctive odor, and a sharp, burning taste, and having the specific gravity of 1.065 at 18° C. (64.4° F.). When perfectly pure, as obtained by re-crystallization from warm petro- leum benzin or other solvents, it undergoes no change, melts at 44° 0. (111.2° F.) to an oily, colorless liquid, and boils at 187° 0. (368.6° F.); but, when slightly impure, or through the influence of certain agencies, as, for instance, ammonia-gas, it assumes a more or less pinkish tint, absorbs moisture on exposure to the air, and gradually deliquesces. The commercial acid usually contains a small quantity of cresol, and probably also other homologous phenols, which, however, do not materially modify its essential properties or value ; but the melting-point and factor of solubility of the pure acid in water become thereby slightly decreased. Carbolic acid is soluble in 20 parts of water at 15° 0. (59° F.) ; with about one-tenth of its weight of water it forms a crystalliza- ble hydrate (08H5-OH)j+H.jO, which remains liquid at temper.a- tures above 16'' C. (60.8° F.), and which is rendered turbid by the further addition of water until 20 parts have been added, when a 140 MANUAL OF CHEMICAL ANALYSIS. clear and complete solution is formed. It is freely soluble in alcohol, ether, chloroform, carbon bisulphide, glycerin, acetic acid, solutions of the alkaline hydrates, and the volatile and fatty oils. Its aqueous solution has no action upon test-paper, coagulates albumen and collodion (distinction from creasote), and assumes a permanent violet-blue color upon the addition of a few drops of a dilute neutral solution of ferric chloride ; with bromine, in the form of vapor or in aqueous solution, it yields a flocculent, white precipitate of the very sparingly soluble tribrom-phenol, OsHjBrj-OH, which, by re-crystallization from alcohol, may be obtained in the form of long, fine, colorless needles. Carbolic acid is miscible with concentrated sulphuric acid, with slight evolution of heat, and forms therewith two isomeric sul- phonic acids of the composition CaH^(S03H)0H ; these are distin- guished and may be separated from each other by the difiereuce in solubility of their salts (sulpho-carbolates, sulpho-phenates), which usually crystallize with great facility. By the action of an excess of concentrated nitric acid, carbolic acid yields bright yellow, shining, prismatic crystals or laminie of trinitro-phenol (picric acid), C'H,(N0J30H. The presence of very small amounts of carbolic acid may be recognized or detected by the following characteristic reactions and tests : When an aqueous solution of carbolic acid, to which a small quantity of ammonia-water has been added, is brought in contact with the vapor of bromirre, a bright blue coloration is produced. This reaction is so delicate, that if the ammoniacal solution of the acid, contained in a test-tube or small porcelain capsule, be thrown out, a suflScient quantity will still adhere to the sides of the vessel to produce in contact with the vapor of bromine the characteristic blue color. An aqueous sokition of carbolic acid assumes, upon the addition of a little mercurous nitrate and a trace of nitric acid, and heating, an intense red color, with the separation of metallic mercury. If to one or two cubic centimeters of pure concentrated sul- phuric acid, contained in a test-tube, an equal volume of an aqueous solution of carbohc acid (1 : 500) is carefully added, and a small crystal of potassium nitrate subsequently allowed to fall into the liquid, a violet coloration will be produced, which is changed to orange-red upon the addition of water. Examination : The quality of carbolic acid is sufficiently recognized by the above characteristics, by its odor, and by its appearance ; in order to detect admixtures, the liquified acid may be tested by mixing it with twice its volume of solution of potassium hydrate, and warming the mixture by immersing the test-tube in boiling water ; a oomplete solution should be formed, which, when cold, should remain limpid, and not separate any oily liquid upon dilution with thz'ee times its bulk of water. ACIDA. 141 Creasote and cresylic acid, or cresol, may be likewise detected by adding to the liquefied acid, containing 5 per cent, of water, an equal volume of glycerin ; a perfectly clear mixture should be formed, which should not be rendered turbid by the subsequent addition of 3 volumes of water, otherwise an undue amount of the above-mentioned impurities will be indicated. Estimation : The estimation of pure carbolic acid in an impure product may be accomplished by dissolving a few grams of it in a porcelain capsule, by the aid of heat, in a solution of potassium or sodium hydrate, evaporating the solution to dryness, heating to a tem- perature not exceeding 170° C. (338° F.), and dissolving the residue in about ten times its weight of water. To the filtered solution, sufficient dilute hydrochloric or sulphuric acid is added to liberate the combined carbolic acid, which may then be sepa- rated by means of a pipette, washed with a saturated solution of common salt, and finally deprived of water by means of fragments of calcium chloride, after which it may be introduced into a dry glass vessel, and weighed ; or, after purification, the aqueous solution of the carbolic acid may be precipitated by bromine- water, in the form of the sparingly soluble tribrom-phenol, CGH^Bra-OH, the precipitate then collected upon a filter, washed with a very small amount of water, and dried at a temperature not exceeding 90° C. (194° F.). One hundred parts of this com- pound correspond to 28.40 parts of pure carbolic acid. The estimation of carbolic acid may also be effected with con- siderable accuracy volumetrically, by a process which likewise depends upon the formation of the sparingly soluble tribrom-phenol. Bromine-water (the strength of Fig. 68. which has been previously determined separately by adding an excess of potassium iodide to a measured portion, and estimating the liberated iodine by means- of a standard solution of sodium hyposulphite, page 94) is added, in slight excess, to a known amount of an aqueous solution of the carbolic acid ; the number of cubic centimeters of bromine-water re- quired are then noted, and, after the separation of the tribrom-phenol by filtration, an excess of potas- sium iodide is added to the filtrate, and the liber- ated iodine, which bears a direct proportion to the excess of bromine employed, estimated with standard solution of sodium hyposulphite, as described on page 94. The first reaction is expressed by the equation : C.Hj-OH + 6Br = OgH.Bra.OH + 3HBr. 94 4"80 As 480 parts of bromine thus correspond to 94 142 MANUAL OF CHEMICAL ANALYSIS. parts of carbolic acid, the amount of pure carbolic acid contained in a weighed quantity of the acid, or in a measured quantity of its aqueous solution, may readily be calculated. The amount of water contained in solutions of carbolic acid may be determined by agitating it, in a graduated cylinder (Fig. 68), with an equal volume of chloroform, and allowing the mixture to repose until it separates into two layers; the upper layer will consist of the water originally present in the solution. ACIDUM CHROMICUM. Ohromie Acid. Oliromic Anhydride. Gliromium Trioxide. Ger. Chromsaure ; Fr. Acide chromique ; Sp. Acido cr6mico. CrOj; 100.4, Long, scarlet, rhombic prisms, of considerable lustre, or masses of loose, bright red, acicular crystals; very deliquescent, and therefore frequently presenting a moist appearance. Its specific gravity is 2.819 at 20° C. (68° F.). At 193° C. (379.4° F.) it melts to a dark red liquid, which, on cooling, solidifies to a red- dish-black, crystalline mass, having a metallic appearance ; at temperatures above 250° C. (482° F.) it is decomposed into chro- mium sesquioxide, CrjO,, and oxygen : 2Cr03 = Cr203 4- O3. Chromic acid dissolves readily and without decomposition in water, cold diluted alcohol, and in pure ether ; it also dissolves in glacial acetic acid, and in concentrated sulphuric acid, but not in the latter when containing from 16 to 17 per cent, of water. Its solution in water, in which the presence of true chromic acid, HjCrO^, is assumed, is, when concentrated, of a yellowish-brown color, but, on further dilution, it assumes a pure yellow color, and possesses an acid reaction and an acid and astringent taste. Chromic acid is a powerful oxidizing agent, decomposing most organic substances, and becoming readih' reduced to chromic oxide. This reduction is effected by hydrogen sulphide, sulphur- ous and arsenious acids, as also by various organic substances, such as oxalic acid, sugar, paper, etc., particularly on warming, for which reason its solution cannot be filtered through paper. If strong alcohol be poured upon the acid, the alcohol becomes ignited, and, when dissolved in glycerin, the mixture explodes violently upon agitation. With hydrogen peroxide, chromic acid forms an intense] v blue compound, of not yet ascertained composition, which is very unstable ; it is soluble in water, and may be extracted there- from by agitation with ether. A somewhat similar and much more permanent blue coloration is produced when an alcoholic ACIDA. 143 tincture of guaiacura. wood is added to a dilute aqueous solution of chromic acid, and is best observed by allowing the liquids to form two layers, when the coloration will appear at the point of contact. By means of this easily applied reaction exceedingly small amounts of chromic acid may be recognized, although it should be remembered that other oxidizing agents show a similar behavior. An aqueous solution of chromic acid, after the addition of a few drops of hydrochloric acid and a few drops of alcohol, assumes, upon heating, a bright green color, with the evolution of etherial vapors. A similar green coloration is immediately produced by concentrated hydrochloric acid, or by the action of the reducing agents previously mentioned, such as sulphurous acid, hydrogen sulphide, ferrous salts, etc. Examination : Sulphuric acid may be detected by boiling a dilated solution of the acid, to which a few drops of hydrochloric acid and a little alcohol have been added, until the liquid appears green. It is then tested with barium chloride, when an ensuing white precipi- tate will indicate the presence of sulphuric acid. Traces of sul- phuric acid, from the difficulty of effecting its complete removal, will usually be fjund, and the following test may serve to estab- lish its limit for pharmaceutical application. One gram of chro- mic acid is dissolved in 100 cubic centimeters of cold water, and the solution mixed with 10 cubic centimeters of hydrochloric acid ; the further addition of 1 cubic centimeter of test-solution of barium chloride should cause not more than a white turbidity. Potassium bichromate or sulphate, which should not be present in any considerable amount, may be detected by igniting a por- tion of the acid in a platinum crucible, and extracting the re- sidual chromic oxide with boiling water. A portion of the neu- tral solution is then tested with barium chloride, when a yellow precipitate, insoluble in acetic, but soluble in hydrochloric, acid, will prove the presence of chromate; another portion, previously acidulated with hydrochloric acid, will, with the same reagent, yield a white precipitate, if sulphate be present. 14.t MANUAL OF CHEMICAL ANALYSIS. ACIDUM CITRICTJM. Citric Acid. Ger. Citronensaure ; Pr. Acide citrique ; Sp. Acido citvico. C,H,0, + H,0 = CH,-GO-OH I/OH I \CO-OH CH„-00-OH + H,0: 210. Fig. 69. Colorless, rhombic prisms, with dihedral summits (Fig. 69), containing one molecule (8.6 per cent.) of water of crystallization, and having the specific gravity 1.617. They are permanent in the air, but slightly efSoresCent in a dry and warm atmosphere, and becoming moist in a damp one, and possess an agreeable, purely acid taste, and an acid reaction. The acid melts at 100° 0. (212° F.) in its water of crystallization, and, when de- prived of water, at 153 to 154° C. (307.4 to 309.2° F.). Exposed to a strong heat, the acid first fuses, and afterwards becomes decomposed, with the separation of carbon, and the evolution of carbon monoxide, carbon dioxide, acetone, and empyreumatic acid vapors, finally becoming wholly dissi- pated. It dissolves in concentrated sul- phuric acid on gently warming, at first without coloration, and with the rapid evo- lution of carbon monoxide and carbon dioxide gases, but afterwards becomes blackened, with the development of sulphurous acid vapors". Citric acid is soluble in 0.75 part of cold, and in 0.5 part of boiling, water, in 1 part of alcohol at 15° C. (59° F.), and in 0.5 part of boiling alcohol, and in 48 parts of ether ; it is nearly in- soluble in absolute ether, chloroform, benzol, and benzin. Its aqueous solution possesses a strongly acid taste and reaction, and, when exposed to the air, is subject to gradual and spontaneous change. When citric acid, with about three times its weight of ammo- nia-water, contained in a sealed tube, is allowed to repose for some weeks at about 100° C. (212° F.), and the solution then allowed to evaporate slowly in a shallow open vessel, it assumes a beautiful deep blue color. Citric acid forms no precipitate with potassium salts (except the tartrates), and, when sparingly added to lime-water, so that the alkaline reaction still predominates, it does not render it tur- ACID A. 145 bid (distinction from oxalic, tartaric, and racemic acids) ; when, however, the liquid is warmed and agitated, it becomes turbid, but transparent again upon cooling. Examination : In order to obtain an average sample of the crystallized acid for examination, it is advisable to reduce to powder a consider- able portion of the crystals, and to make from a small portion of the powder two solutions: an aqueous one, in the proportion of 1 part of the acid to 2 parts of water ; and an alcoholic one, in the proportion of 1 part of acid to 4 parts of alcohol. Both the solu- tions should be complete and clear. Tartaric acid is detected by the formation of a granular white precipitate, when 2 parts by measure of the above aqueous solu- tion and 1 part by measure of the alcoholic solution are mixed together, and agitated with 1 part by measure of a concentrated solution of potassium acetate. The presence of more than 1 per cent, of tartaric acid may be ascertained by the ensuing dariiening of the liquid within five minutes, when one gram of citric acid is dissolved, without heat, in 10 cubic centimeters of a cold, satu- rated solution of potassium bichromate. When many samples of the crystallized acid have to be ex- amined, the following method is also applicable : A large glass pane is placed upon blue or dark-brown paper on a horizontal table or board ; a solution of potassium hydrate in dilated alcohol (1 part of dry potassium hydrate in 20 parts of distilled water and 10 parts of strong alcoliol) is then spread over the pane as thick as will remain stationary upon it; a number of crystals and fragments of the acid are now placed from one to two inches apart, in this liquid, the crystals of each sample separate. Instead of a glass pane, small plates may be employed. Agitation being carefully avoided, the citric acid crystals, after several minutes' action of the alkaline solution, appear clearer and more transparent; if crystals of tartaric acid be present, they will be recognized by their cloudy and white appearance ; after two or three hours, the crystals of citric acid are nearly or quite dissolved, and in their stead is frequently left a small, delicate, dust-like spot (due to traces of calcium salts); if crystals of tar- taric acid be present, they will appear whitish, covered with a coat of small transparent acicular crystals, and surrounded by a deposit of small overlapping groups of similar crystals, or a thin, though broad, crystalline film (all crystals of potassium bitartrate). Metallic impurities may be detected in the aqueous solution by a dark coloration or turbidity with hydrogen sulphide ; if it be so considerable as to form a deposit, this is collected and washed upon a filter, and then dissolved in a few drops of warm nitric acid; to the obtained solution a few drops of dilute sulphuric acid are added, when a white precipitate will indicate lead; after the removal of the latter by filtration, the liquid, upon supersatura- 10 146 MANUAL OF CHEMICAL ANALYSIS. tion with ammonia-water, will assume a blue color if copper^ be present. Sulphates may be detected in the diluted aqueous solution, to which a few drops of diluted nitric acid have been added, by a white precipitate with barium nitrate. Oxalic acid will be indicated in the aqueous solution by a white precipitate, soluble in hydrochloric acid, upon the addition of a solution of calcium sulphate. Calcium salts, traces of which are usually present in the com- mercial acid, will be detected by the production of a white preci- pitate or an opalescence upon the addition of a solution of ammo- nium oxalate. Estimation : One hundred parts of citric acid neutralize 98.57 parts of dry, anhydrous potassium carbonate, 142.85 parts of potassium bicar- bonate, 204.28 parts of crystallized sodium carbonate, 120 parts of sodium bicarbonate, and 68.20 parts of magnesium carbonate. Citric acid may be estimated vol u metrically by means of a standard solution of potassium or sodium hydrate, page 87, one cubic centimeter of which, if exactly normal, corresponds to 0.07 gram of pure crystallized acid ; or 3 5 grams of the acid should require for complete neutralization 50 cubic centimeters of the standard alkali solution. The point of neutralization, as deter- mined by litmus, is, however, in the case of citric acid not clearly seen, and only approximately correct results can thus be obtained. It may be more correctly estimated by the following gravimetric process. A weighed quantity of the acid, or its aqueous solution, is carefully neutralized by ammonia-water, a slight .excess of a perfectly neutral solution of barium acetate added, and finally a volume of 95 per cent, alcohol, equal to twice the volume of the mixture. The precipitate is then collected on a filter (the weight of the ash of which has been previously determined), washed with 63 per cent, alcohol, and dried at a moderate heat. The barium citrate is .then transferred to a porcelain crucible, the burned filter added, and, after the addition of a little concentrated sulphuric acid, it is repeatedly ignited until the carbonaceous matter is removed, and the entire amount of barium citrate has become completely converted into barium sulphate. From the amount of the latter its equivalent in citric acid may be readily deter- mined ; 1 part of barium sulphate corresponding to 0.601 part of crystallized citric acid. ACIDA. 147 Table of the parts by weight of crystallized Citric Acid contained in 100 parts by weight of aqueous solutions of the acid of different specific gravities {Gerlach). Temperature 15° C. (590 F.). Specific Pel- cent, of Specific Per cent, of Specific Per cent, of gravity. citric acid. gravity. citric acid. gravity. citric acid. 1.0037 1 1.0930 23 1,1947 45 1.0074 2 . 1.0972 24 1.1998 46 1.0111 3 1.1014 25 1.2050 47 1.0149 4 1.1060 26 1.2103 48 1.0186 5 1.1106 37 1.2153 49 1.0227 6 1.1152 28 1.32041 50 1.0268 7 1.1198 29 1.2257 51 1.0309 8 1.12439 30 1.2307 52 1.03.50 9 1.1288 31 1.2359 53 1.03916 10 1.1333 32 1.2410 54 1.0431 11 1.1378 33 1.2462 55 1.0470 12 1.1422 34 1.3514 56 1.0509 13 1.1467 35 1.2572 57 1.0o49 14 1.1515 36 1.2627 58 1 0.'588 15 1.1564 37 1.2683 59 1.0632 16 1.1612 38 1.27383 60 1.0675 17 1 1661 39 1.2794 61 1.0718 18 1.17093 40 1.3849 62 1.0762 19 1.1756 41 1.2904 63 1.08052 20 1.1814 42 1.2960 64 1.0848 21 1.1851 43 1.3015 65 1.0889 22 1.1899 44 1.3071 66 ACIDUM GALLICTJM. OaUic Acid. Gar. Gallussaure ; Fr. Acide gallique ; Sp. Acido galico. C,HA + H,0 = C,H,<;gJ)^j^ + H,0; 188. Small acicular prisms or silky needles, or a crystalline powder, nearly colorless, or of a pale fawn color, and containing 1 molecule (9.57 per cent.) of water of crystallization. When heated to about 100° C. (212° F.) the acid loses its water of crystallization, at about 200° C. (392° F.) it melts, and when heated to about 215° C. (419° F.) it is resolved into carbon dioxide and pyrogallol or pyro- gallic acid, which latter sublimes in small crystalline plates ; when exposed to a strong heat, with free access of air, gallic acid burns away without residue. Gallic acid is soluble in 100 parts of cold and in 3 parts of boil- ing water ; in 4.5 parts of cold and in 1 part of boiling alcohol ; in 40 parts of absolute ether ; and is also sparingly soluble in chloroform, benzol, benzin, and glycerin. 148 MANUAL OF CHEMICAL ANALYSIS. The aqueous solution has an acidulous and astringent taste and an acid reaction, and is liable to spontaneous decomposition on exposure to the air ; it gives no precipitate with solutions of fer- rous salts, if free from ferric salt, but it gives a bluish-black pre- cipitate with solutions of ferric salts, the color of which disappears when the liquid is heated, from the reduction of the ferric to fer- rous salt, at the expense of the gallic acid. A solution of gallic acid, when dropped into lime-water, produces a white turbidity, which soon becomes blue, and passes through a greenish or violet tint to a purple color. The solution forms no precipitate with argentic nitrate, but reduces it to metallic silver, gradually at common temperatures, at once when heated. Solutions of the alkaline hydrates, as well as concentrated sul- phuric and nitric acid, when poured upon dry gallic acid, dissolve it, with a deep-red color. Examination : Tannic acid may be detected by a white precipitate, when the solution of the acid is added to a dilute solution of gelatin, or by a precipitate occasioned with solutions of alkaloid.s, albumen, antimony and potassium tartrate with ammonium chloride, and gelatinized starch. Sugar and dextrin remain behind upon solution of the acid in strong alcohol. Resinous admixtures will remain undissolved, and float npon the surface, when a small portion of the acid is dissolved in boiling water. ACIDUM HYDRIODICUM. ACIDUM HYDRIODICUM DILUTUM. Ilydriodic Acid. Diluted Hydriodic Acid. Qer. Joclwasserstoffsiiure ; Fr. Acide liydriodique ; Sp. Acido ]iidroi6dico. A clear, colorless liquid, which, when concentrated, possesses a pungent odor, a strongly acid taste and reaction, and fumes by exposure to the air. The acid, saturated at 0° C. (32° F.), has the specific gravity 1.99. Such an acid, upon warming, develops a large amount of hydrogen iodide, until the temperature of 55° C. (131° F.) is attained, and on further heating, in an atmosphere of hydrogen (to prevent oxidation and liberation of iodine), the temperature rapidly rises to 127° C. (260.6° F.), when an acid of constant composition distils over, having the specific gravity of 1.7, and containing 57.7 per cent, of hydrogen iodide. When a weak acid is subjected to distillation, it loses at first principally water, until at 127° C. (260.6° F.) an acid of constant composi- tion distils over, of the strength above mentioned. ACIDA. 149 The diluted hydriodic acid has usually a specific gravity of 1.077 at 12 to 14° C. (53.6 to 57.2° F.), corresponding to 10.15 per cent, of true hydriodic acid. Hydriodic acid in its aqueous solution rapidly undergoes oxida- tion by exposure to the air, with the liberation of iodine, the originally colorless solution assuming in consequence of the dis- solved iodine a brown coloration, and will then impart a blue color to mucilage of starch, and a red or violet one to chloroform or carbon bisulphide when agitated therewith. The dilute solution of the acid assumes upon the addition of a few drops of concen- trated nitric acid, or a little chlorine-water, a brown or yellowish- brown coloration, due to the liberated iodine, which may be recognized by its action uf)on starch,' or by agitation with a few droDs of chloroform or carbon bisulphide as above described. Hydriodic acid produces with a solution of argentic nitrate a pale yellow precipitate of argentic iodide, which becomes but slowly discolored by exposure to light, is nearly insoluble in ammo- nia-water, and quite insoluble in dilute nitric acid ; with palladium chloride it yields a black precipitate of palladium iodide, insoluble in nitric acid ; and with plumbic acetate a bright yellow precipi- tate of plumbic iodide, which is insoluble in cold, but soluble in hot water, and in a solution of potassium iodide or sodium hydrate. Examination : The acid should be colorless or nearly so, and when a portion is evaporated in a small porcelain capsule, at a gentle heat, it should leave no residue (absence of phosphoric acid or fixed impurities). Hydrochloric acid may be detected by completely precipitating a small portion of the acid with argentic nitrate, collecting the precipitate upon a filter, and digesting it with ammonia- water ; the ammoniacal solution is then filtered, and supersaturated with nitric acid, when a white precipitate will indicate hydrochloric acid. Hydrobromic acid may be detected by completely precipitating a small portion of the acid with palladium chloride, filtering the solution from the precipitate of palladium iodide, and adding thereto a little chlorine- water ; if hydrobromic acid is present bromine will be liberated, imparting a yellow color to the solution, as well as to a few drops of carbon bisulphide or chloroform, sub- sequently added and agitated with the same. Hydrogen sulphide will be recognized by a brown or blackish coloration on the addition of a solution of plumbic acetate. Estimation : The strength of aqueous hydriodic acid may be d*?termined by ascertaining its specific gravity, and reference to the subjoined table, or more accurately estimated by the following methods : I. Volumetric. — (1) About 20 grams of the acid are weighed in a beaker, diluted with a small amount of water, a few drops of 150 MANUAL OF CHEMICAL ANALYSIS. litmus solution added, and a normal solution of potassium or sodium hydrate (page 87) allowed to flow into the liquid from a burette until a permanent blue coloration is produced. One cubic cen- timeter of the normal alkali corresponding to 0.128 gram of abso- lute hjdriodic acid, HI, the percentage strength of the acid may be readily calculated. (2) The acid may be likewise estimated volumetrically by means of a standard decinormal solution of argentic nitrate, page 98 ; one cubic centimeter of the argentic nitrate solution correspond- ing to 0.0128 gram of absolute hydriodic acid, HI. II. GravimetriG. — A weighed portion of the acid is completely precipitated by a solution of argentic nitrate, the precipitate col- lected upon a filter, well washed with water, and, after drying, heated in a weighed porcelain crucible at a temperature just suf- ficient to fuse the argentic iodide. The crucible and its contents, after cooling, are again weighed, and from the weight of argentic iodide the amount of hydriodic acid is calculated ; 100 parts by weight of argentic iodide corresponding to 54.46 parts of absolute hydriodic acid, HI. Table of the parts hy weight of Hydriodic Acid contained in 100 parts by weight of aqueous acid of different specific gravities {Topsoe). Temperature 12 to 140 C. (53.6 to 57.2° F.). Specific Per cent, of Specific Per cent, of Specific Per cent, of gravity. HI gravity. HI. gravity. HI. 1.017 2.286 1.253 28.41 1.542 49.13 1.052 7.019 1.274 30.20 1.572 50.75 1.077 10.15 1.309 33.07 1.603 53.43 1.095 12.21 1 347 36.67- 1.630 53.93 1.102 13 09 1.382 38.68 1.674 56.15 1.126 15.73 1.413 40.45 1.696 57.28 1.164 19.97 1.451 43.39 1.703 57.42 1.191 22.63 1.486 45.71 1.706 57.64 1.235 25.86 1.528 48.22 1.708 57.74 ACIDUM HYDROBROMICUM. ACIDUM HYDROBROMICUM DILUTUM. Hydrobroiriic Acid. Diluted Hydrobromic Acid. Ger. Brorawasserstoffsaure ; Fr. Acide hydrobromique ; Sp. Acido liidrobr<3mico. A clear, colorless, and, when concentrated, pungent and strongly acid liquid, which does not readily undergo change by exposure to the air. When saturated at 0° 0. (32° F.), it has a specific gravity of 1.78, and contains 81 to 82 per cent, of hydrogen bro- AOrDA. 151 mide. Such an acid fumes on exposure to the air, and, wliea subjected to distillation, develops hydrobromic acid gas, until at 125 to 125.5° C. (257 to 257.9° F.) an acid of constant composition distils over, having the specific gravity of 1.49 at 14° C. (57.2° F.), and containing 48 per cent, of hydrogen bromide. When a weak aqueous acid is subjected to distillation, it loses water, until, like hydrochloric acid, at a definite temperature, 125 to 125.5 ° 0. (257 to 257.9° F.), an acid of constant composition distils over, which, however, is subject to variation in strength in accordance with the atmospheric pressure. The diluted hydrobromic acid (Acidura Hydrobromicum Dilu- tum, U. S. P.) has the specific gravity of 1.077 at 15° C. (59° F.), corresponding to 10 per cent, of absolute hydrobromic acid. Hy- drobromic acid yields with argentic nitrate a yellowish-white precipitate of argentic bromide, which becomes bu,t slowly dis- colored by exposure to the light, is insoluble in dilute nitric acid, and sparingly soluble in ammonia-water, but dissolves readily in a solution of potassium cyanide; with palladium nitrate (but not with the chloride) it affords a reddish-brown precipitate of palla- dium bromide ; and with solutions of plumbic or mercurous nitrates, white precipitates of plumbic or mercurous bromide, which are sparingly soluble in water. From a dilute solution of hydrobromic acid or a soluble bromide, no bromine is liberated on the addition of a few drops of concentrated nitric acid (distinction from hydriodic acid and iodides); chlorine-water, however, when mixed with the aqueous solution of the acid, liberates bromine, which imparts a reddish-yellow color to the liquid, and, upon subsequent agitation with a few drops of chloroform or carbon bisulphide, it is absorbed by the latter with an orange-yellow color. Examination : The acid should be colorless, and, when a portion is evaporated in a small porcelain capsule, at a gentle heat, it should leave no residue (absence of phosphoric acid or fixed impurities). Bromine. — The presence of bromine will be indicated by a yel- low o'r reddish-yellow color of the liquid, and, when shaken with a few drops of chloroform, will impart an orange-yellow color to the latter. Iodine and Hydriodic Acid. — Free iodine may be detected by agitating a small portion of the acid with a few drops of chloro- form, when the latter will assume a violet coloration. Hydriodic acid may be detected by the formation of a black precipitate of palladium iodide, on the addition of a solution of palladium chlo- ride ; or, by an ensuing turbidity, when 5 drops of the acid are mixed with 5 cubic centimeters of water and an equal volume of stronger ammonia-water, one drop of solution of argentic nitrate added, and the whole well mixed. Hydrochloric acid may bo detected by neutralizing the acid with 152 MANUAL OF CHEMICAL ANALYSIS. baryta-water, evaporating the solution to dryness, igniting the residue, and finally extracting with absolute alcohol. The barium bromide will become thereby completely dissolved ; should a residue remain, it is dissolved in water, the solution acidulated with nitric acid, and tested with solution of argentic nitrate, when a white precipitate, soluble in ammonia-water, will prove the presence of hydrochloric acid. Sulphuric acid will be recognized by a white turbidity or pre- cipitate when a dilute solution of the acid is tested with barium chloride or nitrate. Sulphurous Acid. — A small portion of the acid is added to a few fragments of pure metallic ziuc in a test-tube, and a small piece of bibulous paper, moistened with a solution of plumbic Fio. 70. acetate, placed over the mouth of the tube (Fig. 70); a discoloration or production of a black stain upon the naper will prove the presence of sulphurous acid. Metallic impurities may be detected by a dark colora- ion or a precipitate, upon saturating a dilute solution l''ii if the acid with hydrogen sulphide, or upon the subse- li [uent addition of ammonium sulphide, ill Estimation : The strength of aqueous hydrobromic acid may be letermined by ascertaining its specific gravity, and eference to the subjoined table; or more accurately stimated by the following methods : I. Volumetric. — (1) About 20 grams of the acid are ireighed in a beaker, diluted with a small amount of ijl ^■ater, a few drops of litmus solution added, and a nor- [lal solution of potassium or sodium hydrate (page 87) llowed to flow into the liquid from a burette until a permanent blue coloration is produced. One cubic entimeter of the normal alkali corresponding to 0.081 ram of absolute hydrobromic acid, HBr, the percent- ge strength of the acid may be readily calculated. To neutrahze 16.2 gram of the officinal acid should require 20 cubic centimeters of normal solution of potassium or sodium hydrate. (2) The acid ma}"- be likewise estimated volumetri- cally by means of a standard decinormal solution of argentic nitrate, page 98 ; one cubic centimeter of the argen.tic nitrate solution corresponding to 0.0081 gram of absolute hydrobromic acid, HBr. II. Gravimetric. — A weighed portion of the acid is completely precipitated by a solution of argentic nitrate, the precipitate col- lected upon a filter, well washed with water, and, after drying, heated in a weighed porcelain crucible at a temperature just suf&cient to fuse the argentic bromide. The crucible and its contents, after cooling, are again weighed, and from the weight of ACIDA. 153 argentic bromide the amount of hydrobromic acid is calculated ; 100 parts by weight of argentic bromide corresponding to 43.08 parts of absolute hydrobromic acid, HBr. Table of the parts hy weight of absolute Hydrohromic Acid contained in IQO parts by weight of aqueous acid of different specific gravities (Biel). Temperature 150 C. (59^ F.). Per cent, of Pel" cent, of Per cent, of Specific gravity. HBr. Specific gravity. HBr. Specific gravity. HBr. 1.0083 1 1.145 18 1.314 35 1.0155 2 1.154 19 1.326 36 1.0230 8 1.163 20 1.338 37 1.0305 4 1.173 31 1.350 38 1.038 5 1.181 33 1.363 39 1.046 6 1.190 33 1.375 40 1.053 7 1.300 24 1.388 41 1.061 8 1.209 25 1.401 43 1.069 9 1.219 26 1.415 43 1.077 10 1.229 27 1.429 44 1.085 11 1.239 28 1.444 45 1.093 13 1.249 29 1.459 46 1.103 13 1.260 30 1.474 47 1.110 14 1.370 31 1490 48 1.119 15 1.381 32 1.496 49 1.127 16 1.393 33 1.513 50 1.136 17 1.303 34 ACIDTJM HYDROCHLORICUM. ACIDUM MURIATICUM. Hydrochloric Acid. Muriatic Acid. Ger. Salzsaure, Chlorwasserstoffsaure ; Fr. Acide hydroclilorique ; Sp. Aoido liidroclorioo. Concentrated hydrochloric acid is a colorless fuming liquid, of a pungent and suffocating odor and corrosive acid taste ; its specific gravity depends upon the quantity of hydrogen chloride held in solution, and varies in the strong acid between 1.160 and 1.120, corresponding to 32.21 and 24.46 per cent, of absolute hydro- chloric acid. The crude commercial acid has generally a spec. grav. of from 1.160 to 1.180, containing 32.21 to 36.29 per cent, of the gas, together with various impurities, such as sulphuric and sulphurous acids, chlorine, iron, and organic matters (the two latter of which impart a yellowish color to the acid), and also frequently arsenic. Two strengths of hydrochloric acid are officinal : Acidum Hydrochloricum of the spec. grav. 1.16 (1.16 Brit. Pharm.= 32.21 percent. HCl, and 1.124 Pharm. Germ. = 25 percent. HCl), contain- 154 MANUAL OF CHEMICAL ANALYSIS. ing 32.21 per cent., and Acidum Hydrochloricum Dilutum of the spec. gray. 1.049 (1.052 Brit. Pharm.=10.6 per cent. HOI, and 1.061 Pharm. Germ. = 12.5 per cent. HCl), containing 10.19 per cent, of absolute hydrochloric acid. Hydrochloric acid may be recognized by the formation of a white, curdy precipitate on the addition of a solution of argentic nitrate ; the precipitate is insoluble in nitric acid, but soluble in ammonia- water and in solutions of potassium cyanide and sodium hyposulphite, and assumes a violet or blackish-brown color ou exposure to solar light. The acid may also be recognized by the evolution of chlorine gas, when heated in a test-tube with a little manganese dioxide. Examination : Fixed iin23urities are recognized by a residue, upon evaporation of the acid in a watch glass. To determine the nature of such a residue, whether organic or inorganic, or the possible presence of substances of both classes, it should be strongly heated on plati- num-foil or in a small porcelain crucible, when organic matters will burn entirely away, while most inorganic substances leave a permanent residue. Sulphuric acid may be detected in the acid, after dilution with at least five times its volume of water, by the formation of a white precipitate, either immediately or upon standing, on the addition of solution of barium chloride. Sulphurous acid may be detected in the filtrate of the preceding- test, after the sulphuric acid, if such be present, has been com- pletely eliminated, by mixing with it a little chlorine-water; an ensuing white turbidity would indicate sulphurous acid.* This may also be recognized or confirmed when to a little of the hydro- chloric acid, diluted with 4 or 5 parts of water, a perfectly clear and saturated solution of hydrogen sulphide in water is added; an ensuing white turbidity or opalescence, due to the separation of sulphur, will, in the absence of ferric salts, likewise indicate sulphurous acid. Another very reliable test for sulphurous acid, and which will at the same time detect the presence of arsenic, consists in adding to a portion of the acid, diluted with an equal volume of water, in a test-tube, a few fragments of pure granular zinc, and cover- ing the orifice of the tube with a small cap of bibulous paper, moistened with a solution of plumbic acetate (Fig. 71); or, if it is desired at the same time to test for arsenic, a cork provided with two strips of bibulous paper, as shown in the figure, one of which is moistened with a solution of plumbic acetate and the other with a solution of argentic nitrate, is loosely inserted in the mouth of the tube. * Chlorine and sulplinrous acids, when in contact \vith water, form hydro- chloric and sulphnric acids; therefore the presence of either one of these impurities in hydrochloric acid excludes the other one. ACIDA. 155 Pig. 71. In the presence of sulphurous acid, hydrogen sulphide will be developed, and produce a blackening of both strips of paper, whereas, if arsenic alone be present, only the one moistened with the argentic solution will become discolored. Chlorine may be detected by the occurrence of a blue coloration, when the acid, diluted with about five times its bulk of water, is mixed with a few drops of solution of potassium iodide (free from iodate) and a little mucilage of starch ; or by imparting a violet color to chloroform or carbon bisulphide, when agitated therewith, after the addition of a few drops of solution of potassium iodide. Iodine and Bromine. — About eight volumes of the acid are agitated in a test-tube with one volume of chloroform ; after subsidence, the stratum of chloroform will appear red when iodine, and yellowish when bromine, is present. If the chloroform, however, re- mains colorless, a few drops of chlorine-water are added ; when, after agitation and subse- quent subsiding, the chloroform still remains colorless, the absence of hydrobromic and of hydriodic acids is also proved. Metals are detected in the acid, diluted with at least four times its bulk of water, when tested with hydrogen sulphide: a white tur- bidity would indicate sulphurous acid or ferric chloride, a yellow one, arsenic, and a dark one, copper, lead, or tin. In order to distinguish the latter, the precipitate is collected upon a filter, washed, and then treated with a little warm ammonium sulphide; the sulphides of tin or arsenic would become thereby dissolved, and, after their removal by filtration, may be separated by again precipitating them from their solutioq by hydrochloric acid, and digest- ing the resulting precipitate with a concentrated solution of ammo- nium carbonate, when the arsenic is redissolved, and upon the addition of hydrochloric acid in excess is obtained as yellow arsenious sulphide, whilst the tin by digestion with the ammo- nium carbonate solution remains undissolved as yellow stannic sulphide. The portion of the original precipitate insoluble in ammonium sulphide is washed with water upon the filter, and dissolved in a small quantity of warm nitric acid. To this solu- tion a few drops of dilute sulphuric acid are added, when a white precipitate will indicate lead ; after the removal of the latter by filtration, if present, ammonia-water in slight excess is added, when a blue coloration will indicate copper. Iron may be detected in the acid, after its previous dilution with ft 156 MANUAL OF CHEMICAL ANALYSIS. a little water, by a blue coloration or precipitate on the addition of solution of potassium ferrocyanide, or by a red coloration on the addition of potassium sulphocyanide. A7-se7iiG. — The presence of arsenic, if sulphurous acid is absent, will have been indicated by the previously described test for the latter, page 154; it may also be recognized by the addition of a few drops of a saturated solution of stannous chloride, or a strip of pure tin-foil and a little pure concentrated sulphuric acid, to the concentrated acid, in a test-tube, and warming very gently. If arsenic be present, brown flakes will be deposited, or, if the amount be very small, only a brown coloration of the liquid will ensue. The recognition of very small quantities of arsenic may be best accomplished by the application of Marsh's test, as described on pages 33 to 36.* Estimation : The estimation of pure hydrochloric acid is most conveniently accomplished volumetrically by the process of neutralization. About 5 grams of the acid are accurately weighed in a small beaker, diluted with a small amount of water, a few drops of litmus solution added, and a normal solution of potassium or so- dium hydrate (page 87) allowed to flow into the liquid from a burette until, with constant stirring, by means of a glass rod, the liquid assumes a permanent blue tint. One cubic centimeter of normal alkali solution corresponding to 0.0865 gram HOI, cor- rected if necessary by its proper factor, the number of cubic cen- timeters employed will at once indicate by simple calculation the amount of absolute hydrochloric acid in the quantity of liquid taken, and from which its percentage strength may then be cal- culated. For the confirmation of the correctness of the result the specific gravity of the acid may be taken, and compared with the strength of that indicated in the subjoined table, page 158. Hydrochloric acid may also be estimated volumetrically by the process of precipitation. About one gram of the acid is first accurately weighed in a beaker or small flask, subsequently diluted with from 50 to 100 cubic centimeters of water, and, after exact neutralization with pure sodium carbonate, and the addition of a few drops of a solution of potassium chromate, as an indi- cator, a decinormal solution of argentic nitrate (page 98) is allowed to flow into the liquid from a burette until, with constant stirring, by means of a glass rod, a permanent red coloration is produced. One cubic centimeter of decinormal argentic nitrate * In the application of the above tests for arsenic, sulphurous acid should be excluded, as, in the first instance, it produces of itself with stannous chloride a yellowish or brown coloration, and, in the second instance, by the formation of hydrogen sulphide in contact with nascent hydrogen, the arsenic would be deposited as insoluble arsenious sulphide ; when sulphurous acid is present, it should, therefore, first be eliminated by the addition of a very small quantity of a solution of iodine iu potassium iodide, when the tests as described may be applied. ACIDA. 157 solution corresponding to 0.00365 gram HCl, this number, when multiplied by the number of cubic centimeters of silver solution employed, will represent the amount of absolute hydrochloric acid in the quantity under examination, from which the per- centage strength of the acid may be readily calculated. The estimation of hydrochloric acid may be also accomplished gravimetrically, by adding to a weighed portion, diluted, if neces- sary, with water, a solution of argentic nitrate until no further precipitate is produced, and subsequently rendering the liquid slightly acid, by the addition of a few drops of nitric acid. The precipitate of argentic chloride is collected on a tared filter, washed with water, and, after drying at 100° 0. (212° F.) until of constant weight, weighed ; or, the dried precipitate, if sufficient in amount, is brought into a small, previously weighed porcelain crucible, and ignited at a gentle heat. 100 parts of argentic chloride correspond to 25.13 parts of absolute hydrochloric acid, HCl. Rules for the dilution of Hydrochloric Acid. For the purpose of diluting a concentrated acid with water, or with a weaker acid, in order to obtain an acid of some special strength, the following simple and concise rules are applicable and convenient : — If a stronger acid (a) is to be diluted to form an acid of the strength (J) by mixing it with water, or with a weak acid (c), the difference in percentage strength is sought, on the one hand, between a and 6, and, on the other, between h and c, and a and c are then mixed in the proportion shown by the difference in the numbers. It has, however, to be taken into consideration that when the difference between a and b is greater than between h and c, less must be taken of a than of c in order to obtain b; but when the difference between a and h is less than between b and c, more must be taken of a than of c in order to obtain b. Example : I. Hydrochloric acid,, containing 29 per cent. HCl, is to be mixed with water to form an acid containing 25 per cent. HCl : («) {b) (c) 29 per cent. 25 per cent. per cent. Difference 4 25 • Accordingly 25 parts of the 29 per cent, acid are to be mixed with 4 parts of water, or 100 grams Hydrochloric Acid = 29 grams HCl 16 grams water = — 116 grams Hydrochloric Acid = 29 grams HCl or 100 grams " " = 25 grams " 158 MANUAL OF CHEMICAL ANALYSIS. II. Hydrochloric acid, containing 32 per cent. HCl, is to be mixed with an acid containing 8 per cent. HCl, to form an acid containing 14 per cent. HCl. (a) {b) (c) 39 per cent. 14 per cent. 8 per cent. 18 6 DifiFerence (3) (1) Accordingly 1 part of the 32 per cent, acid is to be mixed with 3 parts of the 8 per cent, acid, or 100 grams Hydrochloric Acid = 32 grams HCl 300 grams " " = 24 " or 400 grams Hydrochloric Acid = 56 grams HCl 100 grams " " = 14 grams " Table of the quantity by weight of Hydrochloric Acid Gas, and the cor- responding equivalent of Chlorine, contained in 100 parts by weight oj Aqueous Hydrochloric Acid of different specific gravities (^Ore). Temperature 15° C. (590 F.). Per ct. of Per cent. Per ct. of Per cent. Per ct. of Per ceut. Specific hydrochl. of Specific hydrochl. of Specific hydrochl. of gravity. acid. chlorine. gravity. acid. chlorlDe. gravity. acid. chlorine 1.2000 40.777 39.675 1.1328 36.913 36.186 1.0637 13.049 12.697 1.1982 40.369 39.378 1.1308 36.545 25.789 1.0617 12.641 13.300 1.1964 89.961 38.882 1,1387 26.098 25.892 1.0597 12.233 11.903 1.1946 39.554 38.485 1.1267 25.690 24.996 1.0577 11.825 11.506 1.1938 39.146 38.089 1.1247 25.283 34.599 1.0557 11.418 11.109 1.1910 38 738 37.693 1.1227 24.874 24.303 1.0537 11.010 10.713 1.1893 38.330 37.269 1.1206 24.466 33.805 1.0517 10.603 10.316 1.1875 37.938 36.900 1.1185 24.058 33.408 1.0497 10.194 9.919 1.1857 37.516 36.503 1.1164 23.650 33.013 1.0477 9.786 9.522 1.1846 37.108 36.107 1.1143 23.343 22.615 1.0457 9.379 9.126 1 1822 36.700 85.707 1.1133 33.834 22.218 1.0487 8.971 8.729 1.1803 36.292 35 310 1.1102 23.436 21.822 1 0417 8.563 8.333 1.1783 35.884 34.918 1.1083 22.019 21.425 1.0397 8.1,55 7.935 1.1763 35.476 34.517 1.1061 21.611 21.038 1.0377 7.747 7.538 1.1741 35.068 34.131 1.1041 21.204 20.632 1.0357 7.340 7.141 1.1731 34.660 33.724 1 1030 20.796 20.235 1.0337 6 933 6.745 1.1701 34.353 38.328 1.1000 20.388 19.8.37 1.0318 6.524 6.348 1.1681 33.845 32.931 1.0980 19.980 19.440 1.0398 6.116 5.951 1.1661 33.437 32.535 1.0960 19.572 19.044 1.0379 5.709 5.554 1.1641 33.039 33.136 1.0939 19.165 18.647 1.0359 5.301 5.158 1.1620 83.631 31.745 1.0919 18.757 18.250 1.0239 4.894 4.763 1.1599 33.213 81.343 1.0899 18.349 17 854 1.0220 4.486 4.365 1.1578 31,805 30.946 1.0879 17.941 17.457 1.0200 4.078 3.968 1.1557 31.398 80.550 1.0859 17.534 17.060 1.0180 3.670 8.571 1.1537 30.990 80.158 1.0838 17.126 16.660 1.0160 3.262 3.174 1.1515 30.582 29.757 1.0818 16 718 16.267 1.0140 2.^54 2.778 1.1494 30.174 29.361 1.0708 16.310 15.870 1.0120 2.447 3.381 1.1473 39.767 28.964 1.0778 15.903 15.474 1.0100 2.089 1.984 1.1453 29.359 28.567 1.0758 15.494 15.077 1.0080 1.681 1.588 1.1431 28.951 28.171 1.0788 15.087 14.580 1.0060 1.124 1.191 1.1410 28.544 27.773 1.0718 14.679 14.284 1.0040 0.816 0.795 1.1389 28.136 27.376 1.0697 14.271 18.887 1.0020 0.408 0.397 1.1369 37.738 26.979 1.0677 13.863 13.490 1.1349 37.331 26.583 1.0657 18.457 13.094 ACIDA. 159 The specific gravity of the aqueous acid being decreased by an increase of temperature, and increased by a decrease of temperature, the consequent change of the specific gravity amounts for each degree of the centigrade thermometer in either direction — For acids of a specific gravity of 1.1741 to those of 1.1389 to about 0.0005 " 1.1349 " 1.0980 " 0.0004 " " " 1.0939 " 1.0637 " 0.0003 For instance: An acid of a specific gravity of 1.1234 at 16° C, containing 25 per cent, of hydrochloric-acid gas, will have at 18.5° C. a specific gravity of 1.1234— (0.0004 X 2.5) = 1.1224, and at 13.5° C. a specific gravity of 1.1234 + (0.0004x2.5) = 1.1244. ACIDUM HYDROCYANICUM DILUTUM. ACIDUM HYDROCYANATUM. Diluted Hydrocyanic Acid. Prusaic Acid. Ger. Cyanwasserstoffsaure, Blausaure ; Fr. Acide hydrocyanique ; Sp. Acido hidrocianico. Pure hydrocyanic acid is a thin, colorless, and exceedingly poi- sonous, volatile, and unstable liquid. Its odor is very powerful and characteristic, resembling that of peach-blossoms or oil of bitter almonds. It mixes with water, alcohol, and ether, in all propor- tions. The officinal acid is a very dilute hydro-alcoholic solution, containing two per cent, of absolute acid. It imparts a faint eva- nescent color to litmus, and forms a white curdy precipitate with a solution of argentic nitrate. This precipitate is soluble in solu- tion of potassium cyanide, ammonia-water, and boiling nitric acid, but insoluble in dilute acids, and does not readily change color on exposure to solar light; when strongly heated it is completely decomposed into metallic silver and cyanogen gas. If the' acid is rendered slightly alkaline by potassium hydrate, a few drops of a solution of ferrous sulphate and ferric chloride added, and the mixture subsequently acidulated with hydrochloric acid, a pre- cipitate of ferric ferrocyanide or Prussian blue will be produced. Hydrocyanic acid may also be recognized by the following characteristic reactions. When neutralized with a dilute solution of potassium or sodium hydrate, a few drops of yellow ammonium sulphide added, and the mixture carefully evaporated in a porce- lain capsule to dryness, a residue is obtained which, when dis- solved in water, acidulated with hydrochloric aoid, and filtered, yields on the addition of a drop of solution of ferric chloride an intense blood-red color. When the acid is neutralized with a dilute solution of potassium or sodium hydrate, a little picric acid added, and the mixture warmed, an intense blood-red color, due to the formation of picrocyanic acid, OjHjNjOj, is produced. If a solution of mercurous nitrate is added to a solution of hydro- cyanic acid, a gray precipitate of metallic mercury is at once pro- 160 MANUAL OF CHEMICAL ANALYSIS. duced, with the simultaneous formation of mercuric cyanide, which remains in solution. Examination : A small portion of the acid, when allowed to evaporate on a watch glass, should leave no residue. Mineral acids in general may be detected by producing a per- manent red coloration with litmus, as also by causing the precipi- tation of red mercuric iodide upon the addition of a solution of the double salt of mercuric cyanide and potassium iodide, IIgK(0N)2l,* the latter being decomposed by all acids, with the exception of hydrocyanic and carbonic acids. Hydrochloric znA phosphoric acids m&y be detected by the addition of an excess of ammonia-water, and evaporating the solution in a porcelain capsule, at a gentle heat, to dryness; the residue is dis- solved in dilute nitric acid, and a portion of the filtered solution examined with argentic nitrate for hydrochloric acid, which is in- dicated by a white precipitate. '^I'o another portion of the solu- tion ammonium molybdate is added, and heated to boiling ; an ensuing yellowish precipitate indicates j:>Af?s^;Aoric acid. Formic acid, if present, will be detected by its property of reducing red oxide of mercury to gray metallic mercury, when a little of the acid is warmed and agitated with the oxide ; or by the reduction of metallic silver on the addition of a solution. of argentic nitrate, which will impart a grayish color to the precipi- tated argentic cyanide. Sulphuric acid is detected by the formation of a white precipi- tate upon the addition of a few drops of barium nitrate to the acid. Estimation of the Strength of Hydrocyanic Acid : There are two simple methods of ascertaining the quantity of absolute acid contained in hydrocyanic acid. The one depends upon the fact that one part of absolute hydrocyanic acid forms 5 parts of argentic cyanide ; that, accordingly, 100 parts of the officinal acid should yield 10 parts of argentic cyanide. The second method is the volumetric one, and depends upon the property of argentic cyanide to form a soluble double salt with alkaline cyanides. When, therefore, the officinal hydro-- cyanic acid is converted into sodium or potassium cyanide by the addition of sodium or potassium hydrate, no permanent precipi- tate will appear upon the addition of argentic nitrate until more than sufficient argentic cyanide is produced to form the soluble compound. I. Ten grams of the acid are completely precipitated by a solu- tion of argentic nitrate. Then two filters of exactly the same size and paper are cut; through the one the liquid is filtered, the pre- * Obtained by mixing hot concentrated alcoholic solutions of 3 parts of mer- curic cyanide and 2 parts of potassium iodide ; the compound crystallizes out upon cooling, and may be dissolved in water for use. ACIDA. 161 cipitate washed, and then both the empty filter and the one con- taining the argentic cyanide are dried, at a temperature not exceeding 100° C. (212° ¥.). When the weight of the latter filter remains constant, both filters are weighed, the empty one serving as a counterpoise of the one containing the precipitate ; the excess of weight of the latter is argentic cyanide, of which — ■ 1. gram represents S.015 per cent, of absolute hydrocyanic acid. 1.05 " " 2.10 " " 1.10 " " 2.20 " " II. The principle involved in the volumetric estimation of hydrocyanic acid has been fully described on page 100. 5.4 grams of the acid are accurately weighed, and diluted, in a beaker, with about 200 cubic centimeters of water. The liquid is then made slightly alkaline with a solution of potassium or sodium hydrate, a few drops of a saturated solution of sodium chloride added, and a decinormal solution of argentic nitrate (page 98) allowed to flow into the liquid from a burette until, with constant stirring, a slight permanent turbidity is produced in the solution. The number of cubic centimeters of silver solution required to produce this reac- tion with the above-mentioned quantity of acid, divided by 10, will give at once the percentage strength of the acid in hydrogen cyanide. Separation and Detection of Hydrocyanic Acid in Forensic Inves- tigations. — Hydrocyanic acid, being one of the most formidable of poisons, is sometimes the object of search in forensic investiga- tions, and the process for its isolation, and subsequent recognition and estimation will, therefore, be briefly described. The organic materials or substances to be examined are brought into a fiask, a little water added, if necessary, and the mixture slightly acidulated with tartaric acid. A preliminary test is then first made by inserting in a cork adapted to the flask containing the mixture a small strip of paper, moistened first with a little tincture of guaiac, and, after drying, with a very dilute solution of cupric sulphate,* and subsequently gently warming the mix- turfe to about 50° C. (122° F.). In the presence of the vapor of hydrocyanic acid the paper will assume a deep blue color. As, however, other substances, ammonia, nitric oxide, etc., are capable of producing a similar blue coloration, this reaction does not aSbrd unqualified proof of the presence of hydrocyanic acid ; and when thus indicated by the above reaction, or by the odor of the mix- ture under examination, the isolation and identification of the acid must in all cases be effected. * The tincture of guaiac is best freshly prepared, in the proportion of one part of the wood to ten parts of alcohol, or one part of the resin to twenty parts of alcohol ; the solution of cupric sulphate in Die proportion of one part of the salt to two thousand parts of water, by which dilution it forms a peifectly colorless solution. 11 162 MANUAL OF CHEMICAL ANALYSIS. The substance to be examiued, therefore, after acidalation with tartaric acid, and dilution, if necessary, with water, is subjected to distillation in a flask or retort, provided with a condenser, and the distillate collected in a receiver containing a little water (Fig. 72); Fig. 72. the distillation being continued until about one- quarter or one- third of the liquid has distilled over. The distillate is then examined by its odor, action upon litmus, and by the application of the previously described reactions, viz., the formation of argen- tic cyanide, Prussian blue, and ferric sulphocyanide. If a quanti- tative estimation of the acid is required, it may be converted into argentic cyanide, by the addition of solution of argentic nitrate to the distillate until a precipitate ceases to be produced, and from the argentic cyanide, dried at 100° C. (212° F.) until of constant weight, the atnount of pure hydrocyanic acid calculated : 100 parts of argentic cyanide corresponding to 20.15 parts of absolute hydrocyanic acid. As the distillate, however, may contain hydro- chloric acid in addition to hydrocyanic acid, the former should be tested for, and, when present, must be eliminated by the rectifica- tion of the distillate over a little powdered borax or precipitated calcium carbonate, previous to its precipitation with argentic nitrate; these substances serving to combine the free hydrochloric acid, but are not acted upon by hydrocyanic acid, which is thus obtained in a pure form. In view of the possibility of the occurrence of potassium ferro- cyanide in the substance under examination, which would also yield hydrocyanic acid by distillation with an acid, and of the fact that it is a non-poisonous salt, the examination should be in- variably preceded by a test for ferrocyanides, by digesting a por- ACIDA. 163 tion of the substance with water, filtering the solution, and, after acidalating with hydrochloric acid, applying the well-known reactioa with ferric chloride. For the separation of potassium ferrocyanide when associated with hydrocyanic acid, or a soluble simple cyanide, the organic materials, if not already possessing an acid reaction, should be first slightly acidulated with sulphuric acid, and then sufficient of a neutral solution of ferric chloride added to precipitate the entire amount of ferrocyanide as Prus- sian blue. After standing for some time the mixture is filtered, and the filtrate, after the addition of a sufficient quantity of neu- tral potassium tartrate to insure the complete combination of the free sulphuric acid, is subjected to distillation. By operating in this manner the distillate can only contain hydrocyanic acid when originally present as such, or in the form of potassium cyanide. ACIDUM HYPOPHOSPHOROSUM. HypopJiospTiorous Acid. Ger. TJuterpliosphorigesaure ; Fr. Acide hypophosplioreux ; Sp. Acido hipofosf6rico. /OH H3PO, = 0=P^n ; 66. ^H A dense, syrupy, strongly acid liquid, which, at low tempera- tures, forms large, colorless laminar crystals. The crystals melt at 17.4° C. (63.3° F.), and deliquesce gradually at ordinary tem- peratures. By exposure to the air it becomes slowly oxidized to phosphorous acid, and by the action of chlorine or nitric acid it is converted into phosphoric acid. Hypophosphorous acid in its aqueous solution possesses strongly reducing properties, precipitating gold and silver from solutions of their salts, and, when added to a solution of mercuric chloride, either mercurous chloride or metallic mercury is separated, ac- cording to the amount of acid present. When the acid, in excess, is gently warmed with a few drops of solution of cupric sulphate, at a temperature not exceeding 60° C. (140° F.), a reddish-brown precipitate of cupric hydride, CuH, is produced ; with an excess of the cupric solution, and upon more strongly heating, metallic copper is separated. The acid, when strongly heated, is decomposed into hydrogen phosphide and phosphoric acid : 2H3POJ = PH, + H^PO^. Examination : Lead and Calcium Salts and Phosphoric Acid. — A small portion of the acid is neutralized with ammonia-water, and is then tested, in separate portions, as follows : A dark coloration or precipitate 164 MANUAL OF CHEMICAL ANALYSIS. on the addition of ammonium sulphide' will indicate lead, a white precipitate on the addition of ammonium oxalate, calcium salts, and a white precipitate with barium chloride, phosphoric acid. Hydrogen sulphide may be recognized by a dark coloration on the addition of a solution of plumbic acetate. ACIDUM LACTICUM. Lactic Acid. Oxy -propionic Acid. 6er. Milclisaure ; Fr. Acide lactique ; Sp. Acido lactico. A limpid, odorless, syrupy liquid, colorless, or of a paleyellow- ish tint, of a sour taste, and having the specific gravity 1.212 at 15° C. (59° ]?.), corresponding to 75 per cent, of absolute lactic acid. It is miscible, in all proportions, with water, glycerin, alcohol, and ether, and also, without being colored, with cold, concentrated sulphuric acid. Lactic acid dissolves zinc and iron, with efferves- cence, and cannot be distilled without undergoing partial decom- position. Heated upon platinum-foil, it emits inflammable vapors, which burn with a pale flame, leaving a carbonaceous residue, which is completely dissipated at a red heat. When heated with a solution of potassium permanganate, lactic acid emits the odor of aldehyde. Examination : Oum, Mannite, and Glucose. — A few drops of the acid are diluted with water in a test-tube, and slightly supersaturated with sodium carbonate; to the clear liquid are added a few drops of Fehling's solution, and the whole gently warmed; a blue coagulation upon the addition of the cupric solution before warming, would indi- cate the presence of gum ; a brick-colored precipitate, after heating, indicates glucose. The presence of gum and mannite may also be recognized by the occurrence of a turbidity upon dropping the acid into a mix- ture of equal parts of alcohol and ether. (rlycerin may be detected by mixing, in a porcelain capsule, a small portion of the acid with a slight excess of zinc oxide, pre- viously triturated with a little water; the whole is then evaporated, upon a water-bath, to dryness, the residue treated with strong alcohol, and the obtained alcoholic solution evaporated upon a watch-glass ; a neutral, syrupy, sweet residue would indicate glycerin. Sarcolactic acid may be detected by an ensuing blue precipitate, when tested with a solution of cupric sulphate. ACIDA. 165 Foreign Organic Acids. — Two drops of the lactic acid are added iu a test-tube to so much litne-water that the alkaline reaction predominates ; if a turbidity takes place at once, oxalic, tartaric, or phosphoric acids are indicated ; if the turbidit}' does not ensue before the liq uid is heated to boiling, citric acid is indicated. Acetic and butyric acids are recognized by their respective odors when the acid is gently heated in a porcelain capsule. Sulphuric, hydrochloric, and phosphoric acids may be detected in the diluted aqueous solution of the acid by testing it, in separate portions, with barium chloride for the former, and with argentic nitrate for the two latter. Acid calcium phosphates or other calcium salts would be indi- cated by a white turbidity of the dilute solution of the acid when tested with ammonium oxalate. Metals are detected in the acid, when neutralized with ammonia- water, and then tested with hydrogen sulphide ; a white turbidity or precipitate would indicate zinc, a brown or blackish coloration or precipitate, copper, lead, or iron. Estimation : Ninety parts by weight of the officinal acid should be neutral- ized by not less than seventy-five parts by weight of crystallized potassium bicarbonate, corresponding to 75 per cent, of absolute lactic acid. The acid may be also estimated volumetrically by the process of neutralization, whereby 6 grams of the officinal acid should require for exact neutralization 50 cubic centimeters of a normal solution of potassium or sodium hydrate, which like- wise corresponds to 75 per cent, of absolute acid. By the employ- ment of other quaiitites of the acid than that above indicated, the calculation may be made with the consideration that 1 cubic cen- timeter of normal potassium or sodium hydrate corresponds to 0.09 gram of absolute lactic acid. ACIDUM NITRICUM. Nitric Acid. Ger. Salpetersaure ; Pr.Acide nitriqiie ; Sp. Acido iiitrico. Nitric acid, in its most concentrated form, is a colo'rless, fuming, corrosive liquid, having the spec. grav. of 1.530 at 15° 0. (59° F.). It begins to boil at 86° C. (186.8° F.), and becomes of a dark-yellow color, due to the partial decomposition of the acid into nitrogen tetroxide, oxygen, and water. When a strong acid is subjected to distillation, it loses nitric acid, and the boiling point is gradually increased until, at the temperature of 120.5° C. (248.9° F.), an acid of constant composition distils over ; a weak acid, under the same conditions, loses water until, at 120.5° C. 166 MANUAL OP CHEMICAL ANALYSIS. (248.9° F.), the boiling point remains constant. This acid having a constant boiling point has the spec. grav. of 1.414 at 15.5° C. (60° F.), and contains 68 per cent, of absolute nitric acid. The crude commercial nitric acid is of two strengths: the so- called double acid has a spec. grav. of 1.36, containing about 57 per cent, of absolute nitric acid ; and the single acid, of 1.22 spec, grav., containing about 35 per cent, of absolute acid. The officinal nitric acid has the spec. grav. of 1.420 (1.185 Pharm. Germ. = 30 per cent. HNO3), and contains 69.4 per cent, of absolute nitric acid. The Acidum Nitricum Dilutum, of 1.059 spec. grav. (1.101 Brit. Pharm. = 16.8 per cent. HNO3), contains 10 per cent, of absolute nitric acid. Mtric acid is readily decomposed, and is a powerful oxidizing agent, acting violently upon most of the metals, and upon organic compounds, converting many non-nitrogenous vegetable sub- stances into explosive bodies. From its tendency to decompose, nitric acid has frequently a yellowish color from nitrogen oxides, held in solution, which, upon dilution of the acid with water, or upon heating, cause a further decomposition and consequent dis- engagement of nitric peroxide. Nitric acid may be recognized by its property of dissolving copper-turnings to a blue solution, with the evolution of colorless nitric-oxide gas, which, however, at once unites with atmospheric oxygen, forming red fumes of nitric peroxide ; by the ready decoloration of diluted solution of indigo ; by its coloring pine-wood bright yellow ; and by deep red or brown compounds with ferrous salts. An exceedingly delicate test for nitric acid depends upon its reaction with the alkaloid brucine. A few drops of concentrated sulphuric acid, and one or two drops of a saturated aqiieous solution of brucine, are added to the solution to be tested, when a fine rose or dark-red coloration will be produced. By means of this reaction a solution containing but one part of nitric acid in 100,000 parts of water will assume a distinct pink coloration. Another excellent test, but somewhat less delicate than the preceding, depends upon the reaction of nitric acid with aniline. About 0.5 cubic centimeter (approxi- mately 5 drops) of a solution of 10 drops of aniline in 50 cubic centimeters of 15 per cent, sulphuric acid (Acid. Sulph. Dil., U. S. P., may be employed) is brought into a small porcelain capsule, and a glass rod, moistened with the liquid to be tested, is then brought in contact with the liquid. If the nitric acid be very dilute, a rose-red coloration will be produced, but, if concentrated, the entire liquid will assume a brown or dark brownish-red tint. The characteristic reaction of nitric acid with ferrous salts ex- tends also to the nitrates, when previously acted upon by strong sulphuric acid. The test is performed either by placing a crystal of ferrous sulphate in the liquid under examination, mixed with concentrated sulphuric acid. Or by mixing the liquid with a con- centrated solution of ferrous sulphate, and pouring this mixture ACrDA. 167 carefully upon ooncentrated sulphuric acid in a test-tube, so as to form in either case two layers (Fig. 73). If a large quantity of nitric acid is present, the surfaces of the crystal, or the line of contact between the liquids, become black ; if but a small quan- tity is present, they become reddish-brown or purple. Examination : Hydrochloric acid may be detected in the acid diluted with about five times its volume of water, by the formation of a white preci- pitate, when tested with argentic nitrate. Sulphuric acid is detected in the acid, previously diluted with at least five times its volume of water, hj the production of a white precipitate, either immediately or upon standing, on the addition of a solution of barium nitrate. Nitrous and hyponitric acids (nitrogen tetroxide) are detected in the diluted acid, by the addition of one or two drops of a very dilute (1 : 100) solution of potassium permanganate: their presence is indidated by decoloration. They may also be recognized by add- ing to the acid, previously diluted with about five times its volume of water, a few drops of a solution of potassium iodide, and a little mucilage of starch, when a blue coloration will be produced. Iodine and Iodic Acid. — A small portion of the acid (the con- centrated acid should be diluted with about five times its volume of water) is shaken, in a test-tube, with a few drops of chloro- form, which, after subsiding, will appear of a reddish-violet color if free iodine be contained in the acid ; when it remains colorless, or after the removal of the free iodine, if present, by agitation with chloroform, a very small quantity of an aqueous solution of hydrogen sulphide or sulphurous acid is added, drop by drop. 168 MANUAL OF CHEMICAL ANALYSIS. Fig. with gentle agitation ; if a coloration of the chloroform now takes place, iodic acid is indicated. A confirmatory test is, to mix the acid, after diUition, if strong acid is under examination, with a few drops of mucilage of starch ; a bluish coloration will take place after a while, when iodine is present ; if no reaction occurs, a few drops of solution of sulphur- ous acid may be added, diop by drop, when the blue color will appear, if iodic acid be present. Metals may be detected by saturating the diluted acid with hydrogen sulphide, when an ensuing dark coloration or precipi- tate will indicate lead or copper; the liquid is then filtered, if necessary, and supersaturated with ammonia- water ; if a dark coloration is now produced, it will indicate iron. Arsenic, in the form of arsenic acid, is detected by neutralizing a portion of the acid with solution of potassium hydrate, subse- quently adding twice its volume of a strong solution of potassium hydrate and a few fragments of pure zinc, and heating the mixture in a test-tube, provided with a cap of bibulous paper moistened with a drop of olution of argentic nitrate (Fig. 74) ; the production if a black stain upon the paper will reveal the pres- nce of arsenic. Estimation : The estimation of nitric acid is most conveniently ac- omplished volumetrically by the process of neutraliza- ion. About 5 grams of the acid, accurately weighed a a beaker, are diluted with about 50 cubic centime- tsrs of water, a few drops of litmus solution added, and normal solution of potassium or sodium hydrate page 87) allowed to flow into the liquid from a burette ntil, with constant stirring, the liquid assumes a per- lanent blue tint. One cubic centimeter of the normal Ikali solution corresponding to 0.063 gram HNO,, the amount of absolute acid in the quantity employed, nd its percentage strength, may readily be calculated. J n addition thereto the specific gravity of the acid may 1 e determined, and the result of the volumetric estima- t on compared with the percentage strength of an acid aving a corresponding specific gravity, as indicated ._^ by the subjoined table, page 170. Of the strong officinal acid 4.54 grams, and of the diluted acid 31.5 grams, are neutralized by 50 cubic centimeters of normal solution of potassium or sodium hydrate. a ACIDA. 169 Rules for the Dilution of Nitric Acid. If a strong acid, a, has to be diluted with water, or with a weaker acid, c, in order to obtain an acid of some special strength, h, the following rules are applicable : The difference in percentage strength is sought, on the one hand, between a and 6, and, on the other, between b and c, and a and c are then mixed in the proportions represented by the difference in the respective numbers. It must be observed, however, that when the difference between a and h is greater than between h and c, less of a than of c must be taken in order to obtain /;; and when the difference between a and h is less than between b and c, more of a than of c must be employed in order to obtain b; for example : I. Xitric acid, containing 29 per cent, of absolute acid, is to be mixed with water, to form an acid containing 25 per cent, of absolute acid : a. b. c. 29 per cent. 25 per cent. per cent. Difference 4 25 25 parts of 29 per cent, acid are, therefore, to be mixed with 4 parts of water, or 100 grams of nitric acid = 29 grams HNOj 16 " " water = 116 grams of nitric acid = 29 grams HNO3 or 100 " " " " = 25 " " II. Mtric acid, containing 32 per cent, of absolute acid, is to be mixed with an 8 per cent, acid, to form an acid containing l-i per cent, of absolute acid : a. b. c. 32 per cent. 14 per cent. 8 per cent. Difference 18 6 (3) (1) 1 part of 32 per cent, acid is, therefore, to be mixed with 3 parts of 8 per cent, acid, or 100 grams of nitric acid = 32 grams NIIO3 300 " " " " = 24 or 400 grams of nitric acid = 56 grams HNO3 100 " " " " = 14 " " 170 MANUAL OF CHEMICAL ANALYSIS. Table of the quantity hy weight of absolute Nitric Acid, and the cor- responding equivalent of Nitric Anhydride, contained in 100 parts by weight of Nitric Acid, of different specific gravities. Temperature 15° C. (59° F.). Specific Per cent. Per ct. Specific Per ct. Percent. Specific Per ct. Per cent. giavity. of HNO3 of gravity. of H.VOs. of NoOj. gravity. of HNOs. of N2O5. 1.530 100.00 85.71 1.435 73.00 62.57 1.298 47.18 40.44 1..530 99.84 85.57 1.432 72.39 62.05 1.395 46.64 39.97 1.530 99.72 85.47 1.429 71.24 61.06 1.384 45.00 38.57 1.529 99.52 85.30 1.423 69.96 60.00 1.374 43.53 37.31 •1.533 97.89 83 90 1.419 69.20 59.31 1.264 42.00 36.00 1.530 97 00 83.14 1.414 68.00 58.29 1.257 41.00 3.5.14 1.516 96.00 83.28 1.410 67.00 57.43 1.351 40.00 34.28 1.514 9.5.27 81.66 1.405 66.00 56.57 1.244 39.00 33.43 1.509 94.00 80.57 1.400 65.07 55.77 1.337 37.95 32.53 1.506 93.01 79.73 1.395 64.00 54.85 1.335 36.00 30.89 1.503 92.00 78.85 1.393 63.59 54.50 1.218 35.00 39.39 1.499 91.00 78.00 1.386 62.00 53.14 1.211 33.86 39.03 1.495 90.00 77.15 1.381 61.21 53.46 1.198 33.00 37.43 1.494 89.56 76.77 1.374 60.00 51.43 1.192 31.00 26.57 1.488 88.00 75.43 1.373 59.59 51.08 1.185 30.00 35.71 1.486 87.45 74.95 1.368 58.88 50.47 1.179 29.00 34.85 1.482 86.17 73.86 1.363 58.00 49.71 1.172 38.00 34.00 1.477 85.00 72.89 1.358 57.00 48.86 1.166 37.00 33.14 1.474 84.00 73.00 1.353 56.10 48.08 1.157 25.71 33.04 1.470 83.00 71.14 1.346 55.00 47.14 1.138 23.00 19.71 1.467 83.00 70.28 1.341 54.00 46.29 1.120 20.00 17.14 1.463 80.96 69 39 1.839 53.81 46.13 1.105 17.47 14.97 1.460 80.00 68.57 1.335 53.00 45.40 1.089 15.00 12.85 1.456 79.00 67.71 1.331 52.33 44.85 1.077 13.00 11.14 1.451 77.66 66.56 1.333 50.99 43.70 1.067 11.41 9.77 1.445 76.00 6.5.14 1.317 49 97 43.83 1.045 7.32 6.63 1.442 75.00 64.28 1.313 49.00 43.00 1 022 4.00 3.43 1.438 74.01 63.44 1.304 48.00 41.14 1.010 3.00 1.71 With the decrease and increase of temperature, tlie specific gravity of nitric acid suffers a corresponding increase or decrease, amounting for each degree, ol the centigrade thermometer in either direction : Foracidsof a specific gravity of 1.494 to those of 1.477 to 0.00313 in the average. 11 11 1.474 1.456 ' 0.003 " 1.456 1.435 ' 0.00186 " 1.439 1.410 ' 0.00171 " 1.405 1.381 ' 0.00155 " 1.374 1.353 ' 0.00141 " 1.346 1.317 ' 0.00138 " 1.304 1.274 ' 0.00114 " 1.374 1.237 ' 0.001 " 1.237 1.198 ' 0.00085 " 1.193 1.166 ' 00071 " 1.157 1.130 ' 0.0005 " For instance: An acid of 1.179 spec. grav. at 15° C, containing 34.85 per cent, of nitric anhydride, or 29.00 of absolute nitric acid, will have at 17.5° C. a spec. grav. of 1.179 — (0.00071 x 3.5) =1.1773, and at 13° C. a spec. grav. of 1.179+ (0.00071 X 3) = 1.1804. ACIDA. 171 ACIDUM OLEICTJM. ACIDUM OLEINICUM. Oleic Acid. Ger. Oelsaure ; Fr. Acide ol^ique ; Sp. Acido oleico. ' C,,H3P, = C.,H33-CO-OH ; 282. An oily liquid, without odor or taste, and colorless or having but a slight yellow color. It solidifies at 4° C. (39° F.) to a com- pact, white crystalline mass, and from its solution in alcohol it crystallizes in brilliant white needles, which melt at 14° C. (57° F.) to a colorless oil. Its specific gravity is 0.808 at 19° C. (66° F.). When perfectly pure, and unoxidized, it is neutral in its action upon litmus, but on exposure to the air, especially when slightly impure, it rapidly absorbs oxygen, acquiring thereby a yellow or brownish-yellow color, a rancid taste and smell, and an acid reaction. When strongly heated, it becomes decomposed, but A^ith super-heated steam it may be distilled unchanged at 250° C. (482° F.). By treatment with nitrous acid, oleic acid is converted into the solid isomeric elaidic acid, which crystallizes in laminae, melting at 44 to 45^ C. (Ill to 113^ F.). Oleic acid is insoluble in water, but freely soluble in alcohol, ether, chloroform, benzol, petroleum benzin, and the volatile and fatty oils ; it is also soluble in cold, concentrated sulphuric acid without decomposition. Examination : Stearic and palmitic acids will be indicated by a higher con- gealing point than 4° 0. (39° F.), and may be also detected by the following test: A portion of the acid is completely saponified by potassium carbonate, with the aid of a gentle heat, the result- ing soap dissolved in water, exactly neutralized with acetic acid, and the solution precipitated with plumbic acetate ; the ensuing precipitate of plumbic oleate, after being twice washed with boil- ing water, should be completely or almost completely soluble in ether; any considerable insoluble residue will indicate an undue proportion of an admixture of stearic or palmitic acids. Fixed oils, with the exception of ricinus or castor oil, may be detected by the formation of a turbid mixture or the separation of oily drops, when the acid is mixed with an equal volume of strong alcohol, and heated to 25° C. (77° F.). Lead may be detected by a brown or blackish: coloration or precipitate when the alcoholic solution of the acid is saturated with hydrogen sulphide. 172 MANUAL OF CHEMICAL ANALYSIS. ACIDUM OXALICITM. Oxalic Acid. Ger. Oxalsaure ; Fr. Acide oxalique ; Sp. Acido oxalico. CO-OH C,H,0, + 2H,0 = I + 2H,0 ; 126. CO-OH Colorless, transparent, oblique-rhombic prisms (Fig. 75), con- taining two molecules (28 per cent.) of water of crystallization, which they lose gradually upon exposure in a warm and dry atmosphere, or qiiickly upon heating at Fio- 75. 100° C. (212° F.), becoming reduced to a soft white powder. By cautiously heating at a temperature not exceeding 150° C. (302° F.), the anhydrous acid may be completely sublimed ; exposed to a strong heat it develops irritating ""^^^^^^^^^^ inflamable vapors, and is resolved, without carbonization, into carbon di- oxide, carbon monoxide, formic acid, and water, and is finally completely dissipated. Oxalic acid is soluble in 14 parts of water at 15° C. (59° F.), and in its own weight or less of boiling water, in 6 to 7 parts of 90 per cent., and 4 parts of absolute, alcohol ; it is also soluble in 7 parts of glycerin, but sparingly soluble in ether and chloroform. Its solution has a very sour taste, and a strong acid reaction ; it forms with the alkali metals soluble, with all other bases, for the most part, insoluble, salts, which, however, are soluble in dilute mineral acids. When a cold saturated aqueous solution of oxalic acid is dropped into strong alcohol, it should not produce a turbidity ; when dropped into lime-water, a copious white precipitate must ensue at once, which remains unchanged upon the addition of acetic acid, as well as of ammonium chloride, but which is readily dissolved by hydrochloric and nitric acids. Added to a solution of calcium sulphate, a precipitate is also produced after a while. "When heated with concentrated sulphuric acid, oxalic acid is resolved into water and equal volumes of carbon monoxide and carbon dioxide gases, without being charred. Examination ; Binoxalates and quadroxalates of potassium (sorrel and lemon, salts) are detected by heating a small portion of the oxalic acid in a platinum or porcelain capsule, to redness, and until no more fumes are emitted ; a white fused residue, turning red litmus- paper blue, and effervescing with a few drops of hydrochloric acid, would indicate i)0tassium or traces of calcium. The crude commercial acid mostly leaves a very small trace of ACIDA. 173 residue, too insignificant, however, to impair the quality of the acid, or to render it unfit for its common technical applications. Tartaric^ citric, and racemic acids, and their salts, as accidental admixtures in oxalic acid, may be detected by gently heating a small quantity of the acid on platinum-foil, when they will be recognized by the development of a peculiar caramel-like odor, and a voluminous carbonaceous residue ; when heated, in a test- tube, with concentrated sulphuric acid, the crystals, as well as the sulphuric acid, must not become dark-colored or blackened, otherwise the presence of one or the other of such admixtures is indicated. The acid should dissolve perfectly in water, forming a clear solution, and, when saturated with hydrogen sulphide, should afford no coloration or precipitate. Estimation : Oxalic acid may be estimated volumetrically, either by the process of neutralization with a normal alkali, or by oxidation in its warm aqueous solution, slightly acidulated with sulphuric acid, with a standard or decinormal solution of potassium permanga- nate ; it being resolved by the latter, through absorption of oxygen, into carbon dioxide and water. I. Three grams of the air-dry, but uneffloresced, acid are dis- solved in about 50 cubic centimeters of water, and, afterthe addition of a few drops of litmus solution, a normal solution of potassium or sodium hydrate (page 87) is allowed to flow into the liquid from a burette until, with constant stirring, a permanent blue coloration is produced. Oxalic acid being dibasic, each cubic centimeter of alkali solution employed, corrected if necessary by its proper factor, corresponds to 0.063 gram of crystallized acid, from which the percentage amount of pure acid in the specimen under examination may be readily determined. II. 0.2 gram of the crystallized acid are dissolved in about 200 cubic centimeters of water, in a beaker, 5 to 10 grams of dilute sulphuric acid are then added, and, after gently heating, a standard solution of potassium permanganate (page 89) is allowed to flow into the liquid from a burette until, with constant stirring, a permanent pink coloration is produced. The reaction may be expressed as follows : G^fi^ + = 200;, + HjO. One atom of oxygen thus oxidizes one molecule of oxalic acid, and the same amount of oxygen would oxidize two atoms of iron from the ferrous to the ferric state : 2FeS0j -f HjSO^ -f = FcjfSOJj + HjO. From these deductions one mole- cule of oxalic acid corresponds to two atoms (one molecule) of iron ; and placing then the molecular weight of iron (112) as the first term, the molecular weight of crystallized oxalic acid (126) as the second term, and the amount of metallic iron, expressed in grams, corresponding to the number of cubic centimeters of per- 174 MANUAL OF CHEMICAL ANALYSIS. manganate solution employed, as the third term, a simple pro- portion will determine the amount of pure crystallized oxalic acid contained in the specimen under examination. ACIDUM PHOSPHORICXTM. Phosphoric Acid. Ger. Phosphorsaure ; Pr. Acide phospliorique ; Sp. Acido fosf6rico. Metaphosphoric Acid, HPO, = 0=P^qjj; 80. Orthophosphoric Acid, H,PO, = 0=P:^OH ; 98. Monobasic or metaphosphoric acid, HPO3, when perfectly pure, forms a soft pasty mass, which, on exposure to the air, readily absorbs moisture, and deliquesces to a thick syrupy liquid. The glacial phosphoric acid (Acidum Phosphoricum Grlaciale) is an impure metaphosphoric acid, containing frequently considerable amounts of sodium or calcium phosphates, and forms colorless, transparent, glass-like, fusible masses, deliquescent, and slowly but freely soluble in water and in alcohol, yielding colorless, ino- dorous, acid solutions. The aqueous solution of metaphosphoric acid, when freshly prepared, produces white precipitates with albumen and with solutions of argentic nitrate and barium and calcium chlorides, which are soluble in an excess of the acid, while free orthophosphoric acid precipitates none of the above men- tioned reagents. When its solution is allowed to stand for some time, or by continued boiling, the monobasic acid is converted into the tribasic acid, which is contained in the medicinal Acidum Phosphoricum Dilutum. This process is accelerated by the ad- dition of a little nitric acid to the boiling solution of the mono- basic acid. Tribasic or orthophosphoric acid, HjPO^, when free from water, forms an odorless and colorless, dense, syruj)y liquid, possessing a strongly acid taste and reaction. On standing over sulphuric acid, or by exposure to cold, it crystallizes, forming six-sided prisms, terminated by six-sided pyramids, -belonging to the rhombic system, which melt at 38.6° 0. (101.5° F.), and readily become liquefied in the presence of a small amount of water. The specific gravity of the anhydrous acid is 1.88 at 15° C. (59° F.). At temperatures above 160° C. (320° F.) it loses water, and at 213° 0. (415.4" F.) it is completely converted into pyrophos- phoric acid, H^P^O, ; when heated to redness, the latter acid becomes in turn further decomposed, losing water, and metaphos- phoric acid, HPO3, is produced. ACIDA. 175 Orthopbosphoric acid, as previously stated, when in the free state, does not precipitate albumen, nor a solution of argentic nitrate or barium chloride ; when carefully neutralized by ammo- nia-water, however, it yields a white precipitate with a solu- tion of barium chloride, soluble in nitric or hydrochloric acids; with argentic nitrate a yellow precipitate of argentic phosphate, soluble in nitric acid or ammonia-water, and with test magnesium mixture, a white crystalline precipitate of ammonio-magnesium phosphate. When heated with a solution of ammonium molyb- date, acidulated with nitric acid, a yellow crystalline precipitate of ammonium phosphomolybdate is produced. Two strengths of orthophosphoric acid are officinal:* Acidum Phosphoricum, containing 50 per cent, of absolute acid, arid having a specific gravity of 1.347; and Acidum Phosphoricum Dilutunl, containing 10 per cent, of absolute acid, and having a specific gravity of 1.057. Examination of lUetaphosphoric Acid : Ammonium salts may be detected by heating a few fragments of the fused acid in a strong solution of potassium hydrate in a test-tube, when they will be recognized by the odor of ammonia, as also by the production of white fumes, when a glass rod, moist- ened with acetic acid, is held over the orifice of the tube. Calcium, mac/nesium,, and aluminium salts may be detected by dissolving a small portion of the acid in water, boiling with a few drops of nitric acid, and, after the removal of the excess of nitric acid, carefully neutralizing with ammonia- water, when the phos- phates of calcium, magnesium, and aluminium will be precipitated. If a precipitate is thus obtained, it is separated by filtration, the filtrate reserved for subsequent examination for sodium or potas- sium salts, and the precipitate further examined as follows : It is first digested with a concentrated solution of potassium or sodium hydrate, the solution filtered, and to the filtrate solution of ammo- nium chloride added, when a transparent, flocculent precipitate will indicate aluminium. The portion of the precipitate insoluble in the alkaline hydrate is then dissolved in hydrochloric acid, an excess of a solution of sodium acetate, and subsequently a little ferric chloride added, until the liquid assumes a yellowish hue, heated to boiling, and filtered ; to a portion of the filtrate solution of ammonium oxalate is added, when a white precipitate will indi- cate calcium,; to another portion of the filtrate. ammonium carbo- nate in slight excess is added, the solution filtered, and to the fil- trate ammonium phosphate and ammonia-water then added, when a white crystalline precipitate will indicate magnesium. * The phosphoric acid of the Pharmacopceia Germanica has a specific gravity of 1.120, coiTesponding to 20 per cent, of absolute acid ; and the diluted phos- phoric acid of the British Pharmacopoeia a specific gravity of 1.08, corresponding to 14 per cent, of absolute acid. 176 MANUAL OF CHEMICAL ANALYSIS. Sodium, or potassium salts may be detected in the filtrate from the precipitate produced hy ammonia-water, as above described, by the following method : The phosphoric acid is first completely precipitated by neutral plumbic acetate, the filtrate freed from lead by hydrogen sulphide, filtered, and the filtrate evaporated and ignited. If a residue is thus obtained, it will contain the sodium or potassium salts in the form of carbonates, and may be further examined or identified by the color imparted to the non- luminous flame, when tested on platinum wire. Silicic acid may be detected by evaporating a portion of the solution of the acid, to which a small quantity of hydrochloric acid has been added, to dryness, with the aid of a gentle heat ; the residue i§ then dissolved in water, slightly acidulated with hydro- chloric acid, when the silicic acid, if present, will remain behind as an insoluble granular powder. Metallic and other impurities may be detected by the methods described under orthophosphoric acid. Examination of Orthophosphoric Acid : Monobasic or metaphospJioric acid may be detected by a white precipitate on the addition of a solution of barium chloride, and by the formation of a gelatinous white precipitate when tested with solution of albumen. Phosphorous acid may be detected in the diluted acid by the addition of a few drops of a solution of argentic nitrate or mer- FiG. 76. curie chloride, and gently warming; a brown or blackish colora- tion or precipitate with the first reagent, and a grayish-colored precipitate with the latter, will indicate phosphorous acid. A dilute solution of the acid, to which one or two drops of a solution ACIDA. 177 of potassium permanganate is added, will also become readily decolorized ou warming, if phosphorous acid is present. Hydrochloric acid is detected in the diluted acid, to which a few drops of concentrated nitric acid have been added, by a white precipitate on the addition of a solution of argentic nitrate. Nitric acid is indicated by ensuing decoloration when a little of the acid is gently heated with one drop of indigo-solution. Its presence may be confirmed by mixing with the acid nearly an equal bulk of concentrated solution of ferrous sulphate, and placing this mixture upon concentrated sulphuric acid, with the precaution that the two fluids do not mix (Fig. 76); a red-brown coloration upon the line of contact between the two fluids will confirm the presence of nitric acid. Sulphuric acid is detected in the diluted acid, to which a few drops of nitric acid have been added, by a white precipitate with barium nitrate. Metals are detected by saturating the diluted acid with hydrogen sulphide, and allowing the liquid to stand for 12 hours in a corked test-tube or flask ; the occurrence of a coloration or precipitate will indicate metals;* a light-yellow, flocculeut one, arsenic; a brown or black one, copper or lead. Arsenions as well as arsenic acid, besides having been Fig. 77. detected in the test for metals with hydrogen sulphide, may be specially tested for by the application of Marsh's test, as described on pages 33 to 85, or by the follow- ing modification of the same. To a small quantity of the dilute phosphoric acid, contained in a test-tube, one drop of solution of potassium permanganate is added, and the liquid gently warmed; if decoloration takes place, the addition of solution of permanganate is continued, drop by drop, until decoloration of the reagent ceases ; dilute sulphuric acid and fragments of pure zinc (both of which should have been previously tested for arsenic) are then added, not allowing the liquid to occupy more than one-fourth of the capacity of the tube. A small cap of bibulous paper, previously moistened with a drop of solution of argentic nitrate, is then placed over the mouth of the tube (Fig. 77), and the reaction accelerated, if necessary, by gently warm- ing ; the production of a purplish-black spot on the paper, due to the reduction of metallic silver, will con- firm the presence of arsenic. Estimation : The strength of officinal phosphoric acid may be ap- proximately determined by ascertaining its specific i t H * Upon long standing, a. separation of sulphur, from the decomposition of hydrogen sulphide, may ensue, but this may be readily recognized. 12 178 MANUAL OF CHEMICAL ANALYSIS, gravity, and subsequent reference to the subjoined table (page 180). Unlike most other acids, it cannot be estimated by direct neutralization with an alkali, since the point of neutralization, as indicated by means of litmus, cannot be distinctly observed, and in connection therewith is the fact of its forming three classes of salts — NaHjPO^, which has an acid reaction, and Na^HPO^ and NajPOj, both of which possess an alkaline reaction. Among the various methods employed for the quantitative estimation of the oflBcinal or orthophosphoric acid, the two fol- lowing will be found expedient and sufBciently accurate. I. Volumetric. — This method depends upon its indirect estima- tion by the process of neutralization. A convenient quantity of the acid (about 10 grams of the officinal diluted acid, or 2 grams of the stronger acid) is accurately weighed, in a beaker, a normal solution of potassium or sodium hydrate (page 87) then allowed to flow in from a burette, nntil sufficient of the latter has been employed to insure the formation of the neutral sodium salt, Na^PO^. To the strongly alkaline liquid a solution of barium chloride is then added until no further precipitate is produced, the resulting barium phosphate Ba3(POj2, after being allowed to stand for a few hours, filtered oft', the precipitate well washed with water, and the filtrate together with the washings collected in a beaker ; after the addition of a few drops of litmus solution, a normal solution of oxalic or sulphuric acid (page 82) is allowed to flow into the liquid from a burette until, with constant stirring, a permanent pink tint is produced. The number of cubic centimeters of normal acid solution required, deducted from the number of cubic centimeters of alkali solution first employed, will give the amount of the latter required for the exact neutralization of the phos- phoric acid ; one cubic centimeter of the normal alkali corre- sponding to 0.0327 gram HjPO^, the percentage strength of the acid may be readily calculated. II. Graviriietric- — About 10 grams of the officinal diluted acid, or about 2 grams of the stronger acid, are accurately weighed, in a beaker, ammonia-water, in slight excess, then added, and subse- quently test magnesium mixture, until, after having been well stirred and allowed to stand for a short time, no further precipi- tate is produced on the addition of the reagent. Ammonia-water, in an amount equal to about one-fourth of the volume of the liquid contained in the beaker, is then added, and the latter being covered, it is allowed to stand for about twelve hours. The precipitate of ammonio-magnesium phosphate is then collected on a filter, washed with a solution consisting of 1 part of ammouia- water and 3 parts of water until the washings no longer produce a turbidity in a solution of argentic nitrate acidulated with nitric acid, dried at 100° C. (212° F.), and finally ignited in a weighed porcelain cru- cible at a 1-ow, red heat. From the weight of the resulting mag- nesium pyrophosphate, Mg^P^O,, the amount of phosphoric acid ACIDA. , 179 contained in the solution, or the percentage strength of the same, is readily calculated : 100 parts of magnesium pyrophosphate cor- responding to 88.39 parts of phosphoric acid, HjPO^, or 64.28 parts of phosphoric anhydride, P,Oj. The U. S. Pharmacopoeia directs that on pouring 5 grams of the stronger acid upon 10 grams of plumbic oxide free from plumbic carbonate and from moisture, evaporating and igniting, the obtained residue should weigh 11.81 grams ; and that 5 grams of the diluted acid with 5 grams of plumbic oxide, under the same conditions, should yield a residue weighing 5.36 grams. Rules for tlie Dilution of Phosphoric Acid. If a strong acid, a, has to be diluted with water, or with a weaker acid, c, in order to obtain an acid of some special strength, &, the following rules are applicable : The difference in percentage strength is sought on the one hand between a and I, and, on the other, between b and c, and a and c are then mixed in the proportions represented by the difference in the respective numbers. It must be considered, however, that when the difference between a and b is greater than between b and c, less of a than of c must be taken in order to obtain b; and when the difference between a and b is less than between b and c, more of a than of c must be employed in order to obtain b; for example : I. Phosphoric acid, containing 45 per cent, of absolute acid, is to be mixed with water, to form an acid containing 10 per cent, of absolute acid : a. b. c. 45 per cent. 10 per cent. per cent. Difference 85 10 10 parts of 45 per cent, acid are therefore to be mixed with 35 parts of water, or 100 grams of phosphoric acid = 45 grams HjPO^ 350 " " water = . ^ 450 grams of phosphoric acid = 45 grams H,PO^ or 100 " " " " = 10 " '' II. Phosphoric acid, containing 32 per cent, of absolute acid, is to be mixed with an 8 per cent, acid, to form an acid containing 10 per cent, of absolute acid : a. b. c. 32 per cent. 10 per cent. 8 per cent. Difference 22 2 (11) (1) 180 MANUAL OF CHEMICAL ANALYSTS. 1 part of 32 per cent, acid is therefore to be mixed with 11 parts of 8 per cent, acid, or 100 grams of phosphoric acid = 32 grams HjPO^. 1100 " " " " = 88 " 1200 grams of phosphoric acid = 120 grams HjPO^. 100 " " " " = 10 " '' Table of the quantity hy weight of Orthophosphoric Acid, and the cor- responding amount of Phosphoric Anhydride, contained in 100 parts hy weiqht of aqueous Phosphoric Acid of different specific grai'ities (Schiff). Temperature 15° C. (59° F.). Specific gravity. Per ct. of HsPO,. Per ceot. of PjOj. Specific gravity. Per ct. of H3PO4. Per cent. of P.O5. Specific gravity. Per ct. of H3PO4. Percent. of P.O5. 1.0054 1 0.786 1.1363 21 15.346 1.3731 41 39.766 1.0109 3 1.4.53 1.1339 33 15.978 1.3813 48 30.498 1.0164 3 3.178 1.1297 33 16 698 1.8894 43 31.318 1.0330 4 2,91)4 1.1465 24 17.424 1.8976 44 31.944 1.0376 5 3.630 1.1534 25 18.150 1.3059 45 33.670 1.0333 -6 4 356 1.1604 36 18.876 1.3143 46 33.496 1.0390 7 5.083 1.1674 37 19 602 1.3837 47 84.383 1.0449 8 5.808 1.1745 38 30.338 1 3813 48 84.948 1.0508 9 6.534 1.1817 39 21.054 1.3399 49 35.674 1.0567 10 7.360 1.1889 30 21.780 1.3486 50 86.400 1.0637 11 7.986 1.1962 31 22.506 1.3573 51 37.136 11.0688 13 8.713 1.3036 33 23.338 1.3661 52 37.852 1.0749 18 9.438 1.8111 33 23.958 1.3750 53 38 578 1.0811 14 10.164 1.3186 34 34.684 1.3840 54 39.304 1.0874 15 10.890 1.2363 35 35.410 1.3931 55 40.030 1.0937 16 11.616 1.3338 36 36.186 1.4033 56 40.756 1.1001 17 13.343 1.2415 37 36.863 1.4114 57 41.482 1.1065 18 18.068 1.2493 38 37.588 1.4307 58 42.208 1.1130 19 13.794 1.2573 39 38.314 1.4301 59 43.984 1.1196 20 14.530 1.2651 40 29.040 1.4395 60 43.060 "With the decrease or increase of temperature, the speciflc gravity of phos- phoric acid suffers a corresponding increase or decrease, amounting for each degree of the centigrade thermometer in eitlier direction : For acids of a specific gravity of 1.0567 to those of 1.1196 to about 0.00035 " " 1.1363 " 1.1889 " 0.00040 1.1963 " 1.2651 " 0.00058 ' 1.8731 " 1.3486 " 0.00068 " ■ " " 1.3573 " 1.4395 " 0.00083 For instance: An acid of 1.1368 spec. grav. at 15° C, containing 15.246 per cent, of phosphoric anhydride or 21 per cent, of phosphoric acid, will liave at 8O0 C. a spec. grav. of 1.1868 — (0.0004 x 5) =1.1343, and at 130 C. a spec. gray, of 1.1363 + (0.0004 X 3) = 1.137. ACIDA. 181 FiQ. 78. ACIDUM SALICYLICUM. Salicylic Acid. Ortho-oxyhenzoic Acid. Ger. Salicylsaure ; Fr. Acide salinylique ; Sp. Acido salicilico. CjUPj = C!nB:,^QQ_Qjj ; 138. Fine, light, colorless needles, or four-sided prisms (Fig. 78), odorless, or having bat a shght aromatic odor, and permanent in the air. They fuse at 156° C. (312.8° F.), and when carefully- heated may be sublimed without decomposition; when quickly or more strongly heated, they are resolved into carbon dioxide and phenol, a de- composition which takes place to a slight extent when aqueous solutions of the acid are boiled ; when strongly heated on platinum-foil they are completely dissipated. Salicylic acid is soluble in 450 parts of water, and in 2.5 parts of alcohol at 15° C. (59° F.) ; in 14 parts of boiling water, and very freely in boil- ing alcohol; in 2 parts of ether or absolute alco- hol, in 3.5 parts of amylic alcohol, and in 80 parts of chloroform ; and sparingly soluble in benzol, carbon bisulphide, glycerin, and the vol- atile and fatty oils ; it is readily soluble in solu- tions of the alkaline hydrates, forming crystal- lizable salts ; and is also soluble in cold, concen- trated sulphuric acid, without coloration, being precipitated from the latter solution unchanged on the addition of water. The solubility of the acid in water is greatly increased by the presence of various salts, such as the alkaline carbonates and acetates, borax, etc., which form with the acid readily soluble compounds. The aqueous solution of the acid has an agreeable, somewhat sweetish taste, and an acid reaction, and assumes with a trace of ferric chloride an intense violet color ; this reaction, however, is modified by the presence of alkaline hydrates, carbonates, acetates, and phosphates, as also by borax, potassium iodide, oxalic, citric, tartaric, phosphoric, and arsenic acids. With bromine-water the aqueous solution yields a white precipitate of bromo-salicylic acid, CjHjBrOj. If to an aqueous solution of salicylic acid, or pre- ferably a perfectly neutral solution of its sodium salt, a solution of cupric sulphate be added, a bright emerald-green color is pro- duced, but which is destroyed by the presence of free alkalies or acids. Examination : Fixed impurities may be recognizsed by a non-volatile residue when a small portion of the acid is strongly heated on platinum- foil. 182 _ MANUAL OF CHEMICAL ANALYSIS. Organic admixtures may be detected by the separation of car- bon when a little of the acid is heated on platinum-foil, or in a dry test-tube ; or by a dark coloration when a small portion of the acid is agitated with about fifteen times its weight of cold, concentrated sulphuric acid. Chlorides or hydrochloric acid may be detected by an ensuing white precipitate when a little of the acid, dissolved in about ten times its weight of alcohol, and acidulated with nitric acid, is tested with solution of argentic nitrate. Phenol or carbolic acid may in most instances be detected by its odor; smaller quantities may be readily recognized by agitating the acid with a small quantity of warm water, and, after being allowed to cool, and the addition of a little ammonia-water, exposing the solution to the vapor of bromine, when a deep blue coloration will be produced ; or, about 5 cubic centimeters of a saturated solution of salicylic acid are poured into a test- tube, in which 2 cubic centimeters of strong hydrochloric acid and a little granular potassium chlorate have just been mixed; some ammonia-water is then, by means of a pipette, carefully placed upon the mixture; the former will assume a reddish or brownish tint, if carbolic acid be present. Detection of Salicylic Acid in Syrups, Extracts, Articles of Food, etc: A sufficient quantity of the substance to be examined is mixed or diluted with water, if necessary, and evaporated at a gentle heat, in order to expel any alcohol which may be present. After being allowed to cool, the clear filtered liquid is strongly acidu- lated with sulphuric acid, and subsequently shaken with ether. The ether is tlien carefully separated from the aqueous liquid, allowed to evaporate spontaneously, and the residue dissolved in a little water and tested with ferric chloride ; if salicylic acid be present a deep violet coloration will be produced. ACIBUM SUCCINICUM. Succinie Acid. Ger. Bernsteinsaure ; Pr. Acide succinique ; Sp. Acido succinico. CH,-CO-OH CAO, = I ; 118. CH,-CO-OH Colorless, oblique-rhombic prisms, or rhombohedral plates, with- out odor when pure, and with a more or less strong odor when the acid is obtained from amber by sublimation, and is only imperfectly freed from the empyreumatic oils. It melts at 180" C. (356° F.), but may be sublimed at a much AOIDA. 183 lower temperature, and boils at 235° 0. (455° ¥.), at the same time undergoing decomposition into water and succinic anhydride. When heated upon platinum-foil, it emits irritating, inflammable vapors, without the separation of carbon, and is entirely dissi- pated at a red heat. Succinic acid is soluble in 18 parts of water at 17° C. (62.6° F.) and in 0.8 part of boiling water, in 10 parts of cold 90 per cent, alcohol, in 1.5 parts of boiling alcohol, and in 80 parts of pure ether, but is insoluble in carbon bisulphide, petroleum benzin, and turpentine oil (distinction from benzoic acid) ; it is also soluble in warm nitric acid, and in concentrated sulphuric acid, without de- composition, and, if perfectly pure, produces with the latter no coloration. The aqueous solution of the acid has an acid taste and reaction, and, when carefully neutralized with ammonia-water, yields on the addition of a solution of ferric chloride a reddish-brown, floc- culent precipitate of basic ferric succinate, which is dissolved upon the addition of hydrochloric acid (further distinction from benzoic acid). Examination : Fixed Admixtures. — If a residue remains when the acid is heated upon platinum-foil, a small portion of it should be com- pletely incinerated in a porcelain crucible, and the residue, when cold, tested with moist turmeric- as well as with red litmus-paper. It is then divided into two parts, one of which is mixed with a little strong alcohol, and this ignited ; a green color of the flame, especially toward the termination of the ignition, indicates horacio acid; the second portion of the residue is dissolved in a small quantity of water acidulated with a few drops of nitric acid ; effer- vescence would indicate carbonates., originally present as such, or produced by the decomposition of some organic salts, if carboniza- tion occurred upon ignition. The acid solution is then tested in separate portions, with argentic nitrate for chlorides, and with barium nitrate for sulphates, which will be indicated in either instance by an ensuing white precipitate. Ammonium salts are detected by the odor of ammonia, and by white fumes when a glass rod, moistened with acetic acid, is held over the orifice of the test-tube, when the acid is heated in solu- tion of potassium hydrate. Foreign organic acids may be detected as follows : Tartaric acid will be indicated by a white crystalline precipitate of acid ammonium tartrate, upon partial saturation of the acid with ammonia-water; or, by the production of a white crystalline precipitate of acid potassium tartrate, upon the addition of a few drops of a concentrated solution of potassium acetate to the aqueous solution of the acid. Oxalic acid will be detected in the aqueous solution of the acid, after neutralization with ammonia-water, and the addition of a 184 MANUAL OF CHEMICAL ANALYSIS. solution of calcium chloride, calcium sulphate, or lime-water, by the formation of a white precipitate, which is insoluble in acetic acid, or a solution of ammonium chloride. Citric acid will be detected by the addition of a few drops of a solution of the acid to an excess of lime-water, so that the alka- line reaction still predominates, and subsequently heating to boiling; an ensuing white precipitate will indicate citric acid. Benzoic acid may be detected by its solubility in carbon bisul- phide or warm petroleum benzin ; or by its separation, when the precipitate produced in the neutralized solution of the acid by ferric chloride is digested with a little hydrochloric acid. Sugar may be detected, in the absence of other organic acids or their salts, by a corbouaceous residue on gently heating a little of the acid on platinum-foil ; and, in the presence of other organic acids, by heating a small portion of the solution with a few drops of dilute sulphuric acid, and subsequently testing with Fehling's solution, when a red precipitate of cuprous oxide will be formed. Metallic impurities may be detected in the concentrated solution of the acid, by a dark coloration or a precipitate upon saturation with hydrogen sulphide, or upon subsequent supersaturation with ammonia-water. The following may serve as a general test for the purity of succinic acid : 1 part of the acid is dissolved in 15 parts of strong or absolute alcohol ; the solution is aided by dipping the test-tube in hot water ; when cold it is divided into two parts, one of which is mixed with an equal volume of chloroform, the other with an equal volume of ammonia- water ; a complete solution must take place in the first test, and a clear mixture in the second, otherwise one or more of the above-mentioned adulterations are present. When a crude acid, containing empyreumatic substances, has to be examined, it is first agitated and washed with a little ether, and is then dissolved in boiling water, and the solution, when cold, passed through a filter previously moistened with water. ACIDUM SULPHURICUM. Sulphuric Acid. Ger. Schwefelsaure ; Fr. Acide sulfurique ; Sp. Acido sulfiirico. H,SO, = SO,<(gg; 98. A dense, colorless, inodorous, highly corrosive liquid, of a spec, grav. of 1.842_6_at 15° C. (59° F.). When the pure acid of the above composition is heated, it is partially decomposed into water and sulphur trioxide. This dissociation increases with increase of temperature, until at 338° C. (640.4° F.) a liquid acid of con- stant composition and boiling-point distils, over without further ACIDA. 185 alteration, which contains from 98.4 to 98.8 per cent, of abso- lute acid. The commercial concentrated acid usually has a spec, grav. varying from 1.834 to 1.836 at 15° 0. (59° F.)" correspond- ing to from 93 to 94 per cent, of absolute acid. Two strengths of sulphuric acid are officinal, an acid having a spec. grav. not less than 1.840 (1.836-1.840 Pharm. Germ.; 1.843 Brit. Pharm.), and containing not leas than 96 per cent, of absolute sulphuric acid; and Acidum Sulphuricum Dilutum, spec. grav. about 1.067 (1.110-1.114 Pharm. Germ.; 1.094 Brit. Pharm.), containing 10 per cent, of absolute acid. Sulphuric acid has a strong attraction for water, absorbing it from the atmosphere, and withdrawing it or its elements from organic compounds immersed in, or mixed with, the acid; sul- phuric acid, therefore, when in contact with organic substances, or with air containing dust, gradually loses its colorless appear- ance, and becomes more or less brown, and rapidly chars and destroys most organic substances. Sulphuric acid is miscible with water, glycerin, alcohol, and other solvents, with evolution of heat, and produces, with most organic liquids, a more or less vehement decomposition ; in its relations to other compounds, it maintains the character of one of the strongest acids, its affinity for bases being so powerful as to withdraw them from most of their compounds, forming sulphates, which, with the exception of those of barium, strontium, calcium, and lead, are freely soluble in water, the latter three being very sparingly soluble, while barium sulphate is practically insoluble in both water and dilute acids. By the same powerful affinity, sulphuric acid, in its dilute condition, dissolves most of the metals (iron, zinc, magnesium, cobalt), with the evolution of hydrogen and formation of sulphate of the metal ; when concentrated it does not act in the cold upon many of the melals, but, when heated, most of them (copper, mercury, silver, lead, tin, etc.) are attacked, with the evolution of sulphur dioxide, in consequence of the reduction of the acid by the liberated hydrogen at the high temperature. In consequence of its affinity for water, a piece of pine wood dipped into concentrated sulphuric acid becomes black from sepa- ration of carbon, and when a frasment of cane-sugar is placed in ■ contact with the acid the latter will likewise assume a dark colora- tion, and upon heating develop the odor of sulphurous acid. When one drop of the acid is diluted with a test-tubeful of water, a white precipitate will be produced on the addition of a few drops of a solution of barium chloride. Examination : Fixed impurities are recognized by a residue after the complete evaporation of a small quantity of the acid in a platinum or porcelain capsule. Lead is indicated by a white turbidity taking place upon the 186 MANUAL OF CHEMICAL ANALYSIS. Fig. 79. careful admixture of one part of the acid with about four or five times its volume of alcohol. Another method of readily recognizing the presence of lead in sulphuric acid is, to about half fill a small conical cylinder with concentrated hydro- chloric acid, and then to place below the acid, .by means of a pipette, a nearly equal volume of the sulphuric acid, with care that the fluids do not mix (Fig. 79); an ensuing white tur- bidity at the j unction of the t wo fl uids would confirm the presence of lead. The presence of metallic impuri- ties in general may be detected, after the previous dilution of the acid with several times its volume of water, and warming it gently, by saturating with hydrogen sulphide. The liquid, after standing for several hours, is filtered from any precipitate which may have been formed, subsequently' supersaturated with ammonia-water, ammonium sulphide added, and, when required, further examined by the methods de- cribed in the course of analytical investigation (pages il to 59). Arsenic maybe detected in the acid, previously diluted vith about five times its volume of water, and gently v^armed, by the production of a yellow precipitate upon aturation with hydrogen sulphide, as indicated in the ireceding test. If specially sought for, it may, together vith sulphurous acid, be readily detected by heating he diluted acid, in a test-tube, with a few fragments of )ure zinc, and placing over the orifice of the tube a cap if bibulous paper moistened with a drop of solution of Tgentic nitrate (Fig. 80); the production of a black tain upon the paper will indicate either arsenious or ulphurous acids. Nitric and nitrous acids may be detected by the addi- ion of a drop of indigo solution to a small portion of he acid, and gently warming, when decoloration of the liquid will ensue ; or a crystal of ferrous sulphate is added to the acid, or a solution of the latter salt carefully poured upon it, without mixing, so as to form two dis- tinct layers (Fig. 81), when, in either case, a brown coloration of the crystal, or a brown zone at the point of contact of the two liquids, will indicate the above-mentioned impurities. . By carefully mixing the concentrated acid with about half its * ACIDA. 187 volume of a solution of 5 drops of pure aniline in 25 cubic cen- timeters of dilute sulphuric acid, so as to form at first two layers, the mixture will assume a rose-red coloration in the presence of nitric or nitrous acids. A special test for nitric acid consists in the production of a rose-red coloration on the addition of a few drops of an aqueous solution of brucine. Hydrochloric acid will be detected in the acid, diluted with twenty times its volume of water, by the production of a white, curdy precipitate on the addition of solution of argentic nitrate. Estimation : Sulphuric acid may be most conveniently estimated volu met- rically by the process of neutralization. From 2 to 3 grams of the strong acid, or a corresponding quantity of dilute acid, is accurately weighed in a beaker, about 50 cubic centimeters of water, and a few drops of litmus solution added, and a normal solution of potassium or sodium hydrate (page 87) allowed to flow into the liquid from a burette until, with constant stirring, a per- manent blue tint is produced. Sulphuric acid being dibasic, 1 cubic centimeter of the normal alkali solution corresponds to 0.0'49 gram HjSO^, which, multiplied by the number of cubic centimeters of normal alkali solution employed, will give the amount of absolute acid in the specimen under examination, and from which the percentage strength may be calculated. By deter- mining the spec. grav. of the acid, the correctness of the result may be verified by comparing it with the percentage strength of an acid of the same specific gravity, as indicated in the subjoined table, page 189. To neutralize 2.45 grams of the strong officinal acid, diluted 188 MANUAL OF CHEMICAL ANALYSIS. with about 10 volumes of water, not less than 48 cubic centimeters of normal solution of potassium or sodium hydrate should be required ; and to neutralize 9.8 grams of the officinal diluted acid should require from 19.2 to 20 cubic centimeters of normal alkali. The gravimetric estimation of sulphuric acid is readily accom- plished, although less quickly than by the preceding method, by its conversion into barium sulphate. To a weighed quantity of the acid, largely diluted with water, a few drops of hydrochloric acid are added, the mixture heated to boiling, and subsequently a solution of barium chloride added until no further precipitate is produced. After standing for some hours, the precipitate is col- lected on a filter, thoroughlj'' washed with hot water, dried, and finally ignited at a red heat. 100 parts of barium sulphate corre- spond to 42.06 parts of sulphuric acid, H^SO^, or 34.33 parts of sulphuric anhydride, SO3. Rales for the Dilution of Sulphuric Acid. If a strong acid a has to be diluted with water or with a weaker acid c, in order to obtain an acid of some special strength S, the following rules are applicable : The difference in percentage strength is sought on the one hand between a and h, and on the other between b and'c, and a and c then mixed in the proportions represented by the difi'erence in the respective numbers. It must be observed, however, that when the difference between a and b is greater than between b and c, less of a than of c must be taken in order to obtain b ; and when the difference between a and b is less than between b and c, more of a than of c must be employed in order to obtain b ; for example : I, Sulphuric acid containing 29 per cent, of absolute aciiis to be mixed with water to form an acid containing 25 per cent, of absolute acid : a. b. c. 29 per cent. 25 per cent. per cent. Difference 4 25 25 parts of 29 per cent, acid are therefore to be mixed with 4 parts of water, or 100 grams of sulphuric acid = 29 grams H SO . 16 " " water = — 116 grams of sulphuric acid = 29 grams H SO . or 100 " " " " = 25 " II. Sulphuric acid containing 32 per cent, of absolute acid is to be mixed with an 8 per cent, acid to form an acid containing 14 per cent, of absolute acid : ACIDA. 189 a. b. c. 32 per cent. 14 per cent. 8 per cent. Difference 18 6 (3) (1) 1 part of 32 per cent, acid is therefore to be mixed with 3 parts of 8 per cent, acid, or 100 grams of sulphuric acid = 32 grams HjjSO,. 300 " " '• ' " = 24 " " 400 grams of sulphuric acid = 56 grams H^SO^. or 100 " " " " = 14 Table of the quantity hy weight of Sulphuric Acid (ff^SO^), and the corresponding amount of Sulphuric Anhydride (SO^), contained in 100 parts hy weight of Aqueous Sulphuric Acid of different specific gravities ( Otto). Temperature 15° C. (59° F.). Specific gravity. Per ct. of - H2SO4. Percent, of SO3. Specific giavity. Per ct. of H.SO,. Per cent, of SO3. Specific gravity. Per ct. of H„SO,|. Percent, of SO,. 1.8426 100 81.68 1.578 66 53.87 1.339 82 26.13 1.842 99 80.81 1.557 65 53.05 1.831 81 85.30 1.8406 98 80.00 1.545 64 52.84 1.223 30 84.49 1.840 97 79.18 1.584 68 51.42 1.315 29 23 67 1.8384 96 78.36 1.523 63 50.61 1.3066 88 33.85 1.8376 95 77.55 1.513 61 49.79 1.198 27 22.03 1.8356 94 76.',3 1.501 60 48.98 1.190 86 31.32 1.834 93 75.91 1.490 59 48.16 1.183 25 30.40 1.831 93 75.10 1.480 58 47.34 1.174 24 19.58 1.827 91 74.88 1.469 57 46.58 1.167 23 18.77 1.833 90 73.47 1.4586 56 45.71 1.159 23 17.95 1.816 89 72.65 1.448 55 44.89 1.1516 31 17.14 1.809 88 71.43 1.438 54 44.07 1.144 20 16.32 1.802 87 71.02 1.438 58 43.26 1.136 19 15.51 1.794 86 70.10 1.418 58 42.45 1.189 18 14.69 1.786 85 69.38 1.408 51 41.63 1.121 17 13.87 1.777 84 68.07 1.398 50 40.81 1.1136 16 13.06 1.767 83 67.75 1.3886 49 40.00 1.106 15 13.34 1.756 82 66.94 1.379 48 39.18 1.098 14 11.42 1.745 81 66.12 1.370 47 88.36 1.091 18 10.61 1.734 80 63.30 1.361 46 87.55 1.083 18 9.79 1.722 79 64.48 1.351 45 ' 36.78 1.0756 11 8.98 1.710 78 63.67 1.343 44 35.82 1.068 10 8.16 1.698 77 63.85 1.333 43 35.15 1.061 9 7.34 1.686 76 63 04 1.824 43 34.88 1.0536 8 6.53 1.675 75 61.83 1.815 41 33.47 1.0464 7 5.71 1.663 74 60.40 1.806 40 33.65 1.039 6 4.89 1.651 73 59.59 1.3976 89 31.83 1.032 5 4.08 1.639 72 58.77 1,889 38 31.02 1.0856 4 3.26 1.637 71 57.95 1381 37 30.20 1.019 3 2.445 1.615 70 57.14 1.873 36 39.38 1.013 3 1.63 1.604 69 56.32 1.264 85 88.58 1.0064 1 0.816 1.593 68 55.59 1.356 34 27.75 ■ 1.580 67 54.69 1.2476 83 36.94 190 MANUAL OF CHEMICAL ANALYSIS. With the decrease and increase of temperature, the specific gravity of sulphuric acid suifers a corresponding increase or decrease, amounting for each degree of tlie centigrade thermometer in either direction : For acids of a specific gravity of 1.848 to those of 1.786 to about 0.0014 1.777 " 1.663 " 0.0013 1.777 1.663 " 0.0013 1.651 1.306 '■' 0.001 .1.297 1.315 '■' 0.00075 1.306 1.144 0.00045 1.130 1.C68 " 0.00047 ACIDUM STJLPHUROSUM, Sulphurous Acid. Ger. Schvreflige Saure ; Fr. Acide sulfureux ; Sp. Acido sulfuroao. A colorless liquid, possessing the characteristic suffocating odor of burning sulphur. The most concentrated acid which can be obtained by saturating water with the gas at ordinary tempera- tures contains 9.54 per cent, of sulphur dioxide, and has a specific gravity of 1.046. The officinal acid is stated to have a specific gravity of 1.022 to 1.023 (1.04 Brit. Pharm. = 9.2 per cent SO,), corresponding to about 5.7 per cent, of sulphur dioxide. It pos- sesses a very acid, sulphurous taste, and has a strongly acid reac- tion upon litmus, which it first reddens and afterwards bleaches. When heated to boiling, it loses sulphur dioxide, becoming finally completely volatilized ; and when exposed to the light it becomes gradually decomposed with the formation of peutathionic acid, H^SjOj, and in contact with the air is readily oxidized to sulphuric acid. Sulphurous acid possesses a strongly reducing action, to which are due also its bleaching properties ; it separates metallic gold, silver, and mercury from solutions of their salts, and liberates iodine from a solution of potassium iodate, whicli imparts a blue color to mucilage of starch. When hydrogen is generated by the action of dilute sulphuric acid upon a few fragmsnts of pure metal- lic zinc, contained in a test-tube, and a few drops of sulphurous acid are added, the latter will become reduced to hydrogen sul- phide, and impart a black stain to a piece of bibulous paper moist- ened with a solution of plumbic acetate, and placed over the mouth of the tube. Examination : Sulphuric acid may be detected by a white precipitate, insoluble in hydrochloric acid, upon the addition of a solution of barium chloride. The amount of sulphuric acid present should not be sufficient to produce more than a yerj slight turbidity, when to 10 cubic centimeters of sulphurous acid 1 cubic centimeter of diluted hydrochloric acid is added, and subsequently 1 cubic cen- timeter of test-solution of barium chloride. ACIDA. 191 Estimation ; The strength of an aqueous solution of sulphurous acid may be approximately determined by ascertaining its specific gravity, and subsequent reference to the subjoined table, or, more accurately, by the following method of volumetric estimation: About 2 grams of the acid, diluted with 50 cubic centimeters of water, are placed in a flask, a little mucilage of starch added, and then a decinormal solution of iodine, the exact strength of which has been previously determined, page 93, allowed to flow into the liquid from a burette until, with constant stirring, a per- manent blue coloration is produced ;* the sulphurous acid be- comes thus oxidized to sulphuric acid, according to the equation : I, + R,SO, + Rfi = H,SO, -1- 2HI. 254 82 (127) (41) From the number of cubic centimeters of iodine solution employed, the amount of sulphur dioxide or of absolute sulphurous acid may be calculated ; one cubic centimeter of the iodine solution, corrected if necessary by its proper factor, page 95, corresponding to 0.0032 gram of sulphur dioxide, SOj, or 0.0041 gram of abso- lute sulphurous acid, H^SO^. ■ The U. S. Pharmacopoeia directs that 1.28 grams of sulphurous acid, diluted with 20 volumes of water, and a little mucilage of starch added, should require the addition of at least 14 cubic cen- timeters of the volumetric solution of iodine before a permanent blue tint is developed, corresponding to at least 3.5 per cent, of sulphur dioxide. Table of the parts hy weight of Sulphur Dioxide contained in 100 parts by weight of aqueous Sulphurous Acid, of different specific gravities (Anthon"). Temperature 15° C. (59° F.). Specific gravity. Per cent, of SOj.- Specific gravity. Per cent of SOj. 1.046 1.036 1.031 1.027 1.023 9,54 8.59 7.63 6.68 5.72 1.020 1.016 1.013 1.009 1.005 4.77 3.82 2.86 1.90 0,95 * On account of the volatility of sulphurous acid, it is important that such estimations be performed as quiclily as possible, in order to prevent loss by evaporation. 192 MANUAL OF CHEMICAL ANALYSIS. ACIDTJM TANNICUM. Tannic Acid. Tannin. Ger. Gerbsaure ; Fr. Acide tannique ; Sp. Acido tanico. C H O - CeH,(OH),CO-OH ) q. 22 CeH,(OH),CO Amorphous, friable, porous, and inodorous masses, or thin shin- ing scales, of a pale greenish-yellow color, and feeble, mild odor* (mostly combined with a faint odor of ether); when heated upon platinum-foil, tannic acid fuses, swells up, and burns away without residue. Tannic acid is soluble in 6 parts of water or glycerin, in 0.6 part of alcohol, and in less than its own weight of diluted alcohol, and very freely soluble in boiling water and in boiling alcohol; it is but sparingly soluble in absolute alcohol and in commercial ether, and almost insoluble in absolute ether, chloroform, carbon bisulphide, benzol, benzin, and the fixed and volatile oils. Its aqueous solution reddens litmus-paper, and has an astringent taste, without bitterness; it becomes turbid when boiled, and gradually dark-colored and mouldy, when exposed to the air ; it suffers pre- cipitation by the alkaline salts, and by the mineral acids, and forms soluble compounds with the alkaline hydrates, sparingly soluble ones with the earthy oxides, and more or less insoluble ones with most of the metallic oxides ; its solution coagulates solutions of gelatin, albumen, and starch (distinction from gallic acid), and affords white precipitates, soluble in acetic acid, with the alka- loids ;■[ it produces no reaction with ferrous salts, if completely free from ferric salts, but it gives a bluish-black precipitate with the latter, which is soluble in oxalic and mineral acids. When solution of tannic acid is dropped into lime-water, it produces a white turbidity, which soon becomes gray and dingy green, and passes through various shades to a dark purple-brown color. If to a very dilute aqueous solution of tannic acid a small quan- tity of iodine-water be added, a colorless solution will be obtained, which, on the addition of a very little ammonia-waterj assumes a transient, fine red coloration ; if the iodine-water be added in such an amount as of itself to impart a slight reddish tint to the liquid, and lime-water, instead of ammonia, be then added, a blue colora- tion will be produced. Examination : The absence of admixtures of resinous substances^ gum,, dextrin, and of sugar, may be ascertained by the property of the acid to yield a clear or nearly clear solution with about four or five parts of warm water, which should remain so when tested in two por- tions, the one by addition of twice its volume of strong alcohol, * The color and odor are due to traces of a greenish resin, f Morphine is precipitated only from very concentrated solutions, and the precipitate is readily dissolved by a slight excess of tannic acid. ACIDA. 193 the other by dilution with water; if any such adulterations be present, they may be separated and recognized by making two solutions of the acid, one in strong alcohol, when gum, sugar, and dextrin will remain behind, and another one in boiling water, when resinous substances will remain undissolved or be separated on cooling. Estimation : In consequence of the variable nature of tannic matters as de- rived from different sources, and the impurities with which they are frequently accompanied, their exact quantitative estimation in technical products, vegetable extracts, etc., is often attended with considerable difficulty. Of the various' methods proposed, two of the less complicated will here be given, which, however, in most instances afford sufficiently accurate results. I. The substance to be examined is extracted with strong alcohol, the alcoholic liquid evaporated at a gentle heat to the consistence of a soft extract, and the residue taken up with just sufficient water to insure the complete solution of the tannic mat- ter. To the clear aqueous solution a solution of neutral plumbic acetate is then added until a precipitate ceases to be produced, the precipitate collected upon a tared filter, washed three or four times with small portions of water, dried at 100° C. (212° F.) until of constant weight, and its weight finally determined. The precipi- tate is then removed from the filter, the latter, together with a little ammonium nitrate, brought into a porcelain crucible and ignited, and afterward the precipitate added, and the whole ignited at a strong heat until the weight remains constant. The weight of the ignited plumbic oxide, subtracted from the previously determined weight of the lead precipitate, will represent the amount of tannic acid, together with other organic aeids or bitter principles precipitable by plumbic acetate, which may be contained in the substance under examination. II. This method depends upon the precipitation of the tannic acid as zinc tannate, and the estimation of the latter by means of a solution of potassium permanganate. A solution of zinc acetate in an excess of ammonia water yields with tannic acid a precipi- tate of zinc tannate, insoluble in an excess of the reagent, in water or ammonia- water, but is not precipitated by alcohol, glycerin, potassium or calcium tartrate, albumen, or by ferric and ferrous salts of the organic acids ; with gallic acid and aluminium salts it yields a precipitate, which, however, is soluble in an excess of the reagent and in ammonia- water. The solutions required in this process of estimation are: 1. A solution of zinc acetate, prepared by dissolving 10 grams of crys- tallized zinc acetate in 200 cubic centimeters of water, and the subsequent addition of 130 grams of ammonia-water, spec. grav. 0.960. 2. Diluted sulphuric acid, prepared by mixing 1 part of sulphuric acid, spec. grav. 1.84, with 5 parts of water; and 3. A 13 194 MANUAL OF CHKMICAL ANALYSIS. solution of 1.333 grams of crystallized potassium permanganate in 1 liter of water. In order to determine the oxidizing power of the permanganate solution, a solution of pure tannic acid of known strength is prepared ; for instance, 1 gram of pure tannin dis- solved in 1 liter of water. If it be found, for example, that 20 cubic centimeters of this tannin solution require the addition of 10 cubic centimeters of permanganate solution in order to pro- duce a permanent pink tint, then 1 cubic centimeter of the per- manganate solution corresponds to 0.002 gram of pure tannin. The estimation is then performed as follows,: To about 50 cubic centimeters of the liquid to be examined, a slight excess of the solution of zinc acetate above that required to completely precipi- tate the tannin is added, the mixture heated to boiling, subse- quently evaporated to about one-third of its volume, and allowed to cool. The precipitate of zinc tannate is then collected on a filter, washed with hot water, subsequently dissolved in diluted sulphuric acid, and the solution titrated with potassium perman- ganate until a permanent pink tint is produced. If, for example, 15 cubic centimeters of the potassium permanganate solution are employed, and, as by the above determination, 1 cubic centimeter of permanganate solution corresponds to 0.002 gram of tannin, consequently 15 cubic centimeters of permanganate solution cor- respond to 0.002 X 15 = 0.03 gram of tannin. As this amount is contained in 50 cubic centimeters of the liquid under examination, 100 cubic centimeters will contain 0.06 gram, or 0.06 per cent, of pure tannic acid. Table of the amount by weight of pvre Tannic Acid contained in 100 ■parts by weight of its aqueous solutions of different specific gravities {Hammer'). Temperature 15° C. (59° P.). Per cent. Per cent. Per cent. Per cent. Specific of tannic Specific of tannic Specific of tannic Specific of tannic gravity. acid. gravity. acid. gravity. acid. gravity. acid. 1.0010 0.25 1.0211 5.25 1.0416 10.35 1.0635 15.35 1.0020 0.50 1.0222 5.. 50 1.0427 10.50 1.0635 15.50 1.0030 0.75 1.0232 5.75 1.0437 10.75 1.0646 15.75 1.0040 1.00 1.0243 6.00 1.0447 11.00 1.0656 16.00 1.0050 1.35 1.0252 6.25 1.0458 11.25 1..0666 16.33 1.0060 1.50 1.0263 6.50 1.0468 11.50 1.0677 16.50 1.0070 1.75 1.0273 6.75 1.0479 11.75 1.0688 16.75 1.0080 3.00 1.0283 7.00 1.0489 12.00 1.0698 17.00 1.(090 2.25 1.0293 7.25 1.0499 13.25 1.0709 17.35 1.0100 2.. 50 1.0304 7.50 1.0510 12.50 1.0719 17.50 1.0110 2.75 1.0314 7.75 1.0520 13.75 1.0730 17.75 1.0120 3.00 1.0334 8.00 1.0530 13.00 1.0740 18.00 1.0130 3.25 1.0834 8.25 1.0541 13.35 1.0751 18.35 1.0140 3.50 1.0343 8.50 1.0551 13.50 1.0761 18.50 1.0150 3.75 1.0355 8.75 1.0562 13.75 1.0773 18.75 1.0160 4.00 1.0365 9.00 1.0573 14.00 1.0782 19.00 1.0171 4.35 1.0375 9.25 1.0583 14.35 1.0793 19.25 1.0181 4.50 1.0386 9.50 1.0593 14.50 1.0803 19.50 1.0191 4.75 1.0396 9.75 1.0604 14.75 1.0814 19.75 1.0201 5.00 1.0406 10.00 1.0614 15.00 1.0834 30.00 ACIDA. 195 ACIDUM TARTARICUM. Tartaric Acid. Ger. Weinsaure ; Fr. Acido tartarique ; Sp. Acido tartarico. CH(OH)-CO-OH C.H.O, = I ; 150. CH(OH)-CO-OH Colorless, transparent, monoclinic prisms (Fig. 82), permanent in the air ; they contain no water of crystallization, and, when cautiously heated in a glass tube, fuse at 135° C. (275° F.) to a transparent, vitreous, very delicjQescent mass of metatartaricacid, GJlfi^ ; when strongly heated, with exposure to the air, they are decomposed with the evolution of inflammable vapors of a peculiar odor, resembling that of burnt sugar, and with the separation of carbon, and are finally wholly dissipated. Tartaric acid is soluble in 0.7 part of cold, and in 0.5 part of boiling, water ; in 2.5 parts of cold, and in 0.2 part of boiling, alcohol ; in 36 parts of absolute alcohol, in 23 parts of commercial ether, or 250 parts of absolute ether ; and is nearly insoluble in chloroform, benzol, and benzin. Its solutions possess a strongly acid taste and reaction, and, when dropped into solutions of neutral potassium salts, give rise to the formation of a white granular precipitate, at once in concentrated solutions, and after a time in diluted ones. This reaction, how- ever, does not take place in solutions oontaining free mineral acids or acid salts thereof. When soluiLp.n of tartaric acid is dropped into lime-water, so that the al1ial,ine reaction predomi- nates, a white turbidity occurs (distinction from citric acid), which disappears again upon the addition of solution of ammonium chlo- ride (distinction from racemic acid), and also upon the addition of acetic acid (distinction from oxalic acid); solution of calcium sul- phate remains unchanged upon the addition of tartaric acid (addi- tional distinction from oxalic and racemic acids). Crystals of tartaric acid, when immersed in concentrated sul- phuric acid, dissolve gradually without coloration, unless warmed, when they become black, and, on more strongly heating, with the development of carbon monoxide, carbon dioxide, and sulphurous acid gas. Examination : Salts. — An admixture of salts is recognized by the addition of an equal volume of alcohol to a cold saturated aqueous solution of the acid, or by dissolving the powdered acid in 6 parts of strong 196 MANUAL OF CHEMICAL ANALYSIS. alcohol; a complete and permanent solution must ensue in either case. Sulphuric add or sulphates may be detected in the diluted solu- tion, to which a little hj'drochloric acid has been added, by a white turbidity with barium nitrate. If 10 cubic centimeters of a strong solution of tartaric acid be employed for the test, no pre- cipitate should be produced within five minutes upon the subse- quent addition of 1 cubic centimeter of test-solution of barium chloride, and an excess of hydrochloric acid. Chlorides may be detected in the diluted solution, by a white precipitate, insoluble in nitric acid, on the addition of a solution of argentic nitrate. Oxalic acid or oxalates may be detected in the concentrated aqueous solution of the acid, by a white precipitate when tested with solution of calcium sulphate. Calcium salts may be detected in the diluted solution, pre- viously nearly neutralized with ammonia-water, so that the acid reaction still predominates, by a white precipitate on the addition of ammonium oxalate. Metallic impurities (copper or lead) are detected by a brown or blackish coloration or precipitate, when a concentrated aqueous solution of the acid is saturated with hydrogen sulphide ; after filtering, if necessary, and subsequent super-saturation with am- monia-water, an ensuing dark coloration would indicate iron. Estimation : One hundred parts of tartaric acid require for exact neutraliza- tion 92.2 parts of anhydrous potassium carbonate, 133.33 parts of crystallized potassium bicarbonate, ITO.tifi parts of crystallized sodium carbonate, 112 parts of sodium bicarbonate, and 63.33 parts of magnesium carbonate. The estimation of tartaric acid may also be conveniently ac- complished volumetrically with sufficient accuracy, since, unlike citric acid, its point of neutralization as indicated by means of litmus may be distinctly observed. About 3 grams of the crystallized acid, accurately weighed, are dissolved in about 50 cubic centimeters of water, a few drops of litmus solution added, and a normal solution of potassium or sodium hydrate (page 87) allowed to flow into the liquid from a burette until, with constant stirring, a distinct blue tint is pro- duced. Tartaric acid being disbasic, one cubic centimeter of normal alkali corresponds to 0.075 gram of the crystallized acid, and from the number of cubic centimeters of alkali solution cm- ployed, the purity or percentage strength of the acid may be readily calculated. If 3.75 grams of acid, and a strictly normal solution of alkali are employed, the number of cubic centimeters of the latter required for neutralization, when multiplied by 2, will represent at once the percentage purity of the acid. Another method of estimation consists in adding to a solution ACIDA. 197 of 1 part of tartaric acid in 3 parts of cold water, a solution of 1 part of potassium acetate in 3 parts of cold water, and subse quently adding a volume of alcohol equal to that of the whole mixture ; after being allowed to stand for 2 hours, the white, crystalline precipitate of acid potassium tartrate is collected upon a tared filter, well washed with diluted alcohol, and dried at 100° C. (212° F.), when it should weigh between 1.25 and 1.26 parts. Table of the parts hy weight of crystallized Tartaric Acid contained in 100 part^ by weiglit of aqueous solutions of the acid of different specific gravities (^Gerlach). Temperature 150 C. (59° F.). SpeciJc Per cPnt. of Sppciflc Per cent, of i Specific Per cent of gravity. tartaric acid. gravity. tartaric arid. i gravity. tartaric acid. 1.0045 1 1.09693 30 1.3019 39 1.0090 3 1.1030 31 1.30785 40 1.0136 8 1 . 1073 32 1.3138 41 1.0179 4 1.1124 33 1.3198 42 1.0234 5 1.1175 34 1.2259 43 1.0273 6 1.1337 25 1.2317 44 1.0338 7 1.1283 26 1.3377 45 1.0371 8 1.1338 27 1.3441 46 1.0430 9 1.1393 38 1.3504 47 1.04693 10 1.1449 39 1.3568 48 1.0.517 11 1.15047 80 1.2633 49 1.0565 13 1.1560 81 1.26962 50 1.0013 13 1.1615 32 1.2763 51 1.0661 14 1.1670 38 1.2828 53 1.0709 15 1.1736 34 1.3894 53 1.0761 16 1.1781 35 1.2961 54 1.0813 17 1.1840 36 1.3037 55 1.0865 18 1.1900 37 1.3093 56 1.0917 19 1.1959 38 1.3169 57 ACIDUM VALERIANICUM. Valerinnio Acid. Isopropyl-acetic Acid. Ger. Valerlansaure, Baldiiansanre ; Fr. Acide valerianique ; Sp. Acido valeiiauico. C5H.0O, = (.jj' >0H-0H,-CO-OH ;* 102. Pure valerianic acid forms a thin, colorless, or nearly colorless liquid, having the persistent odor of valerian-root, and a pungent, acid taste; it reddens litmus, bleaches the skin, and burns when * Of the acids having the empirical formula C.,H|„0„ four raodifications are theoretically possible, all of which are at orfsent known : (1) Normal valerianic ucid,ClH3-CH,-CH^-aH,-C0-0H. (3) The medicinal 1H8 MANUAL OF CHEMICAL ANALYSIS. inflamed with a bright, smoky light. In contact with water, it absorbs about 20 per cent, of its weight without losing its oily con- sistence, and is itself soluble in 25 parts of water at 15° 0. (59° F.); it is miscible with ammonia-water, alcohol, and ether, in all pro- portions. Its spec. grav. is 0.934 at 15° C. (59° F.), and it boils at 175° C. (347° F.). The commercial acid is generally the hydrate GjHj^Oj + H.^O, formed as above mentioned from the absolute acid by the absorption of about 20 per cent, of its weight of water, and, with reference to the old notation, was formerly known as the trihydrated acid, C,„Hg03.3HO ; it has tjjie specific gravity 0.945, boils at 165° C. (329^ F.), and may be also distin- guished from the absolute acid by its limited solubility in carbon bisulphide. When pure concentrated valerianic acid is added to an excess of mercuric oxide, a fine red solution of basic, uncrys- tallizable valerianate is obtained; the same coloration is produced by a leas concentrated acid on warming the solution, a consider- able excess of the mercuric o.x.ide being always maintained. Examination : Inorganic salts (valerianates) may be detected by a non- volatile residue on the evaporation of a small quantity of the acid in a small porcelain capsule. Foreign fatty acids will be indicated by a higher specific gravity of the acid, and may also be recognized as follows : One gram of the acid is weighed in a tared flask, and water, of a temperature of from 12 to 15° C. (53.6 to 59° F.), is carefully added, with constant agitation, until the acid is just dissolved. The flask is weighed again, and the quantity of water required for solution must be not less than twenty-five times the weight of the acid; in this instance, not less than twenty-five grams. If the acid dis- solves in less water, it is not pure, containing admixtures (alcohol, acetic acid, and butyric acid), which by their greater solubility increase that of the valerianic acid. On the otber hand, the quan- tity of water required for solution must not exceed thirty times (30 grams) the weight of the valerianic acid, in which case it would contain less soluble or insoluble admixtures (caproic and similar monatomic acids, valeric aldehyde, etc.). The presence of valeric aldehyde, as also of amylic alcohol and amyl valerianate, acid, or isopropyl-acetic acid, qjj^ "^CH-CH^-CO-OH. (3) Trimethyl-acetic acid, J>Gnc, and for metallic impurities, is performed in the same way as with the corresponding solutions of bismuthous carbonate, described on pages 274-276. BROMUM. BROMINIUM. Bromine. Ger. Brom ; Fr. Brome ; Sp. Bromo. Br; 79.8. A heavy, dark brownish-red, very volatile liquid, of an intense and suffocating odor, somewhat resembling that of chlorine ; its spec. grav. is 2'.99 at 15° C. (59° F.). 280 MANUAL OF CHEMICAL ANALYSIS. Bromine solidifies at —24.5° C. (^12.1° F.), forming a dark- brown, brittle, crystalline mass, with a semi-metallic lustre, some- what resembling that of iodine, which at —12° C. ( -1-10.4° F.) still retains its solid condition ; when containing water it solidifies at — 7° C. (-f-19.4° F.). It is liquid and volatile at ordinary tem- peratures, and boils at 63° C. (145.4° F.), .forming yellowish-red vapors of the spec. grav. 5.54 (compared with air), which strongly irritate the organs of respiration, and impart a green color to the flame. Bromine is soluble in 33 parts of water at 15° C. (59° F.), yield- ing an orange-yellow solution, which has the odor of bromine, bleaches vegetable colors and solution of indigo, and imparts an orange-yellow color to mucilage of starch; when the solution is exposed to a temperature near the freezing-point, it forms red octahedral crystals of bromine hydrate, Br^, -f- lOH^O, which at 15° C. (59° F.) are again resolved into bromine and water. The aqueous solution of bromine, on exposure to sunlight, gradually undergoes decomposition with the formation of hj'drobromic acid, and the evolution of oxygen; it is deprived of its bromine and of its color when agitated with ether, chloroform, or carbon bisul- phide ; these solutions, however, are themselves decolorized when agitated with a solution of potassium hydrate ; but either of them, with the exception of carbon bisulphide, will/form a new solution of the bromine, and consequently regain the color, upon the addi- tion of an excess of any mineral acid. Bromine is freely soluble in alcohol and ether with a reddish- brown color, and in chloroform, benzol, and carbon bisulphide, forming solutions of a yellowish-red color; it is also soluble in sohitions of the alkaline hydrates, with the formation of bromide and bromate of the alkali, and, with an excess of alkali, yielding solutions which are colorless, or possess but a slight yellowish tinge : 3Br, -1- 6K0H = 5KBr -l- KBrOj -f 3H,0. In its chemical relations, bromine closely resembles chlorine, having a powerful affinity for hydrogen, though not quite so strong, and hence it acts with energy on many organic com- pounds, abstracting hydrogen with equivalent substitution. Examination : Water may be detected by the following method, which also admits of its quantitative estimation: To a weighed amount of the bromine, contained in a glass-stoppered bottle, about ten times its weight of water is added, and subsequently an accurately weighed amount of metallic mercury, equal to about twice the weight of bromine employed. The combined liquids are then shaken until complete decoloration ensues ; thereupon the insoluble mixture of mercurous bromide and mercury is separated by filtra- tion, dried at 100° C. (212° F.), and weighed. The difference BROMUM. 281 between the combined weight of the amount of bromine and mercury employed and the weight of the obtained dried mix- ture, will indicate the presence, and represent the amount of contained water in the bromine. Chlorine may be detected by adding to 3 grams of the bromine about ten times its weight of water, and subsequently water of ammonia, in small portions, until a perfectly colorless liquid is obtained. The liquid is then digested with an excess of barium carbonate, the solution filtered, evaporated to dryness, and the residue gently ignited. The ignited residue, which will contain all the bromine, together with any chlorine which may be present, in the form of barium bromide, or chloride, is then treated with absolute alcohol, when it should become entirely dissolved, or leave but a slight residue. The amount of insoluble residue, consist- ing of barium chloride, will bear a direct proportion to the amount of chlorine contained in the bromine, which, in the commercial product, is usually present to the extent of from 1 to 2 per cent. Iodine may be tested for by dissolving a portion of the bromine in forty times its weight of water, and the solution thus obtained, with the exception of a small reserved portion, is agitated with reduced iron or iron filings until a nearly colorless liquid is obtained, and the bromine is completely converted into ferrous bromide. The liquid is then filtered into a test-tube, a little mucilage of starch added, and subsequently a few drops of the reserved aqueous bromine solution carefully poured upon the sur- face ; if iodine be present, a blue zone will appear at the line of contact of the two liquids. The presence of iodine may also be detected by the addition of an aqueous solution of the bromine to a solution of ammonium sulpliide until no further separation of sulphur is prod^iced, the liquid then evaporated upon the water- bath to dryness, the residue dissolved in water, filtered, a few drops of a dilute solution of ferric chloride added, and the mix- ture shaken with chloroform ; if iodine be present, the chloroform will assume a violet color. Bromoform will be recognized by the development of its charac- teristic odor, when a little of the bromine is added to a solution of potassium iodide, and the liberated iodine subsequently dissolved by means of a solution of sodium hyposulphite. When present to any considerable extent, it mavbe separated by fractional distilla- tion ; its boiling-point being at 150 to 152° 0. (302 to 805.6° F.). Cyanogen or its compounds may be detected by adding about 10 grams of the bromine to be tested, very gradually, and with constant stirring, to an equal weight of iron filings, previously mixed with 4 or 5 times their weight of water. The liquid, while still warm from the reaction, is filtered into a flask, which is after- ward partially closed, and allowed to repose for one or two days ; if cyanogen or its compounds are present, a precipitate of Prussian blue will be gradually deposited. 282 MANUAL OF CHEMICAL ANALYSIS. Estimation : The quantitative estimation of free bromine, with a view to the determination of the amount of impurities present, may be most conveniently accomplished by the following volu- FiG. 103. metric method : About 0.3 gram of the bromine is accurately weighed in a small glass bulb (Kg. 103), which is afterwards opened under the sur- face of a solution of about 1 gram of potassium iodide in 10 cubic centimeters of water, and the liberated iodine estimated by means of a standard solution of sodium hyposulphite, page 94. From the amount of liberated iodine, the corresponding amount of bromine may be calculated by simple equivalent proportion ; one atom of iodine (126.6) corresponding to one atom of bromine (79.8). Should the bromine, however, contain chlorine as • an impurity, the latter will likewise liberate iodine j from the potassium iodide, and thus preclude the direct calculation of the bromine. In the latter case, the calculation may be based upon the fol- lowing consideration : H A = the amount of libe- rated iodine, as determined by titration with a solution of sodium hyposulphite, and B = the weight of employed bromine ; then the amount of chlorine, Jf, which is contained in the bromine under examination, may be ascertained in accordance with the follow- ing formula : _^_ A — 1.0875B 2.0312 and the amount of pure bromine is consequently B — -X. BRUCINA. BEUCINUM. Brucine. Brucia. Ger. Brucin ; Fr. Brucine ; Sp. Bruchia. C,3H,,N,0, + 4H,0; 466. Transparent, colorless, four-sided prisms, aggregations of stel- late needles, or a crystalline powder, with a pearly lustre, and possessing a strongly bitter taste. Brucine contains 4 molecules (15.45 per cent.) of water of crystallization, and effloresces upon exposure to the air ; it melts at 130° C. (266° F.), gradually losing its water of crystallization, and, upon further heating, may be partially sublimed without decomposition ; when strongly heated upon platinum-foil, it is decomposed with the evolution of inflam- BRDCINA. 283 mable vapors, which burn with a bright sootj'- flame, and is finally completely dissipated. Brucine is soluble in 320 parts of cold, and in 150 parts of boiling, water, very freely soluble in alcohol, amylic alcohol, chloroform, and benzol, but is sparingly soluble in ether and petroleum benzin. It neutralizes the acids, forming crystallizable salts, which possess a bitter taste, and are readily soluble in water and alcohol, but insoluble in ether. Brucine dissolves in moderately concentrated nitric acid with an intense blood-red color, which, however, soon changes to yellow- ish-red, and finallj', upon warming, to yellow. If the acid solution be subsequently slightly warmed with a little water, again allowed to cool, and a few drops of solution of stannous chloride or am- monium sulphide added, the mixture assumes a beautiful violet color. The reaction is best obtained by the employment of but little nitric acid, and is not influenced by the presence of strych- nine. If a solution of raercurous nitrate be slightly warmed in a shallow porcelain capsule on the water-bath, and an aqueous solu- tien of brucine added, a fine red coloration is gradually produced at the edges of the liquid, which, by the slow evaporation of the liquid to dryness, remains permanent. Brucine dissolves in concentrated sulphuric acid with a slight rose-red coloration, and the solution assumes, upon the addition of potassium bichromate, a transient reddish-brown color. If the brucine contains strychnine, traces of which are frequently present in the commercial alkaloid, its solution in sulphuric acid will afford, upon the addition of potas- sium bichromate, a rapidly fading blue-violet coloration. With concentrated sulphuric acid, which contains a trace of nitric acid, brucine affords an intensely red solution. Chlorine- water colors an aqueous solution of a brucine salt first violet and then red, and, upon the subsequent addition of ammo- nia-water, a yellowish-brown color is produced. Aqueous solu- tions of brucine salts are precipitated by the alkaline hydrates and carbonates, as also by most of the commonly employed alkaloidal reagents, and yield crystalline precipitates with potassium chro- mate, sulphocyanide, and ferricyanide. By the action of oxidizing agents, brucine affords several interesting products of decompo- sition. Thus upon heating with dilute sulphuric acid and man- ganese dioxide, methylic alcohol and formic acid are produced, with the development of carbonic acid gas. By treatment with concentrated nitric acid, it assumes, as previously stated, an intense red color, and is resolved into water, nitric oxide, oxalic acid, methyl nitrite, and a crystallizable base, cacoteline. C,3H,eN,O,+5HNO»=2H,O+2NO+C,H,O,+0H3NO,+C,„H,,Np, Brucine. Cacoteliue. For the separation of brucine from other alkaloids, or when associated with complex organic mixtures, see page 108. 284 MANUAL OF CHEMICAL ANALYSIS. CADMII lODIDUM. CADMIUM lODATUM. Iodide of Cadmium. Cadmium Iodide. Ger. Jodcadniiura ; Fr. lodure de cadmium ; Sp. loduro de cadmio. Cdl,; 365. Colorless, flat, micaceous crystals, or hexagonal tables, of a pearly lustre, permanent in the air, and having a specific gravity of 4.576. When heated to about 316° C. (600.8° P.), the salt melts, form- ing an amber-colored fluid, and, at a dull red heat, is decomposed with the evolution of violet colored vapors of iodine. Cadmium iodide is freely soluble in water : 100 parts of water dissolving, at 20° C. (68° F.), 92.6 parts, at 60° C. (140° F.), 107.5 parts, and at 100° C. (212° F.), 133.3 parts of the salt; it is also quite freely soluble in alcohol, and in a mixture of alcohol and ether. The aqueous solution has a slightly acid reaction upon litmus, and yields with hydrogen sulphide or ammonium sulphide a yellow precipitate, which is almost insoluble in an excess of the latter reagent (distinction from arsenic) ; with argentic nitrate it yields a pale yellow precipitate, insoluble in ammonia-water ; with mercuric chloride a bright red precipitate; and with the alkaline hydrates and carbonates white precipitates, of which that with ammonia-water is soluble, the remainder insoluble in an excess of the precipitant. If to the aqueous solution of the salt a little chlorine-water be added, drop by drop, and subsequently a little mucilage of starch, the mixture will assume a deep blue color. One hundred parts of cadmium iodide, when completely pre- cipitated by argentic nitrate, yield a precipitate of argentic iodide, which, when thorouglily washed, and dried at 100° C. (212° F.), should weigh 128.55 parts. Examination : Metallic Impurities. — The aqueous solution of the salt, acidu- lated with hydrochloric acid, is completely precipitated by hydro- gen sulphide, the resulting precipitate collected and washed upon a filter, and subsequently digested with ammonia-water, and again filtered ; the latter filtrate, when supersaturated with hydro- chloric acid, should afford no turbidity; an ensuing yellow colora- tion or precipitate will indicate the presence of arsenic. The filtrate from the original hydrogen sulphide precipitate is then supersaturated with ammonia- water ; an ensuing white precipi- tate would indicate a;nc, a black one, iron. Chlorides may be detected by completely precipitating a small portion of the aqueous solution of the salt with argentic nitrate, collecting and washing the resulting precipitate upon a filter, and CADMIUM. ' 285 subsequently digesting it with ammonia-water, and filtering; the ammoniacal filtrate is then supersaturated with nitrjc acid, when an ensuing white curdy precipitate will indicate the presence of chloride. CADMII SULPHAS. CADMIUM SULFURICUM. Sulphate of Cadmium. Cadmium Sulphate. Ger. Scliwefelsaurcs Cadmium ; Fr. Sulfate de cadmium ; Sp. Sulfate decadmio. 3CdSO,.8H,0; 767.4. Colorless, transparent, rhombic tables, having a specific gravity of about 3., and containing, for 3 molecules of the salt, 8 mole- cules (18.8 per cent.) of water of crystallization. They efHoresce slightly by exposure to the air. lose 5 molecules of water upon drying at 100° C. (212° F.), and the remaining 3 molecules at a higher temperature. Cadium sulphate is soluble in twice its weight of water at 17° 0. (62.6° F.), but insoluble in alcohol. The solution has an acid re- action upon litmus, an astringent, acidulous, and slightly austere taste, and, when diluted with six times its volume of water, may be mixed with considerable amounts of alcohol without the sepa- ration of the salt, which finally takes place in the form of thick liquid drops. The aqueous solution yields upon the addition of potassium or sodium hydrate, or ammonia- water, a white precipitate of cad- mium hydroxide, which is insoluble in an excess of the first- named reagents, but soluble in an excess of ammonia-water; with alkaline carbonates it yields a white precipitate of cadmium carbonate, insoluble in an excess of the precipitant; and with hydrogen sulphide, a yellow precipitate of cadmium sulphide, which is soluble in moderately concentrated, warm sulphuric, hydrochloric and nitric acids, and to a slight extent in a solution of ammonium sulphide' but is insoluble in diluted acids and ammonia-water (distinction, in the latter instance, from arsenious sulphide). Examination : Arsenic may be detected by completely precipitating an acidu- lated solution of the salt with hydrogen sulphide, digesting the resulting precipitate with ammonia-water, filtering, and subse- quently supersaturating the clear liquid with hydrochloric acid; the separation of a yellow precipitate will reveal the presence of arsenic. The acidulated solution of the salt, when completely precipitated by hydrogen sulphide, should yield a filtrate, which, upon evaporation to dryness, should leave no residue ; if a residue 286 MANUAL 6f chemical analysis. remains, admixtures of other salts are indicated. In the latter case, the residue should be dissolved in dilute hydrochloric acid, and examined for metallic, earthy, and alkaline oxides by the systematic method of analysis as described on pages 56 to 61. Estimation : The quantitative estimation of cadmium may be readily accom- plished by precipitating the carbonate from a boiling solution of a weighed quantity of the salt, by means of sodium carbonate ; the precipitate is thoroughly washed, dried, and, by ignition at a red heat, converted into cadmium oxide, CdO, from the weight of which the corresponding amount of anhydrous or of crystallized cadmium sulphate may be calculated : 100 parts of cadmium oxide, CdO, corresponding to 162.69 parts of anhydrous sulphate, CdSO,, or 200.31 parts of crystallized sulphate, 3CdS0^.8H,0. It may also be estimated by precipitation by hydrogen sul- phide from an acidulated solution of its salt as cadmium sulphide, CdS, which, after washing, is dried at 100° C. (212° F.), and weighed. One hundred parts of cadmium sulphide correspond to 1-1:4.56 parts of anhydrous sulphate, CdSO^, or 178 parts of crys- tallized sulphate, 3CdSO,.8H,0. CAPPEINA. COFFEINUM. Caffeine. Caffeia. Theine. Ouaranine. Methyl-theobromine. Ger. Caffein ; Fr. Cafeine ; Sp. Cafeiiia. C,H,oKp, + H,0 = C,H,(CH3)N,0, -f H,0 ; 212. Colorless, slender, and flexible, silky needles, containing one molecule (8.49 per cent.) of water of crystallization, which is lost by drying at 100° C. (212° F.). The crystals are odorless, neu- tral in their action upon litmus, and possess a slightly bitter taste. They melt at 234 to 235° C. (453.2 to 455° F.), although begin- ning to sublime at 180° C. (356° F.), and boil at 384° C. (723.2° F,); when slowly heated upon platinum foil, they are completely volatilized, without carbonizing. Caffeine, when previously deprived of its water of crystalliza- tion, is soluble in 75 parts of water at 15° C. (59° F,), in 2 parts at 70° C. (158° F.), in 8 parts of chloroform, in 50 parts of ordinary alcohol, and in 520 parts of absolute alcohol, and is still less soluble in ether and carbon bisulphide. The aqueous solution is neutral in its action upon litmus, and possesses a slightly bitter taste ; it is abundantly precipitated by tannic acid, the precipitate being readily re-dissolved upon warming, or upon the addition of an excess of the reagent, but is not precipitated by picric acid, nor CALCIUM. 287 by a dilute solution of potassio-mercuric iodide (distinction from most other alkaloids) ; it also remains unaltered, and does not as- sume a purple color, when it is exposed to the air, after the addition of a little ammonia-water (distinction from phlorizin). Caffeine enters into combination with the stronger acids, with- out neutralizing them, with, the formation of salts having an acid reaction, and which are readily decomposed ; it also forms crys- tallizable compounds with some metallic salts. From its solution in the weaker acids, it crystallizes, upon evaporation, unchanged. With concentrated sulphuric and nitric acids, caffeine suffers no change of color in the cold (additional distinction from many alka- loids, and from salicin, which, with the former acid, produces a bright red coloration. When caffeine is added to chlorine-water, in a small porcelain capsule, and evaporated to dryness, a yellow- ish-red residue is obtained, which, upon the addition of a little ammonia-water, assumes a beautiful purplish-red color. The same reaction may be obtained by the employment of a little nitric acid, instead of chlorine-water, care being taken to avoid an excess of the acid; with the application of bromine-water, instead of chlorine, the coloration, upon the addition of ammonia, is more of a violet hue. When boiled with an alcoholic solution of potassium hydrate, or with an aqueous solution of barium hydrate, caffeine is re- solved, by the absorption of water and the elimination of carbonic acid gas, into an uncrystallizable base, caffeidine, C,H,jN^O, which is very readily soluble in water and alcohol, and whose sulphate crystallizes in long, colorless needles : C,H.„NA + H,0 = O^Np + 00,. Caffeine. Caffcidiue. The decomposition of caffeine by barium hydrate is, however, not confined to the production of caffeidine, but methylamine, formic acid, and ammonia are simultaneously formed, and, by the long-continued action of the reagent, the caffeidine is itself decom- posed into the above products and sarkosine, OjHjNOj, with the evolution of carbonic acid gas. CALCII BROMIDXIM. CALCIUM BROMATUM. Bromide of Calcium. Calcium Bromide. Ger. Bromcalcium ; Fr. BrSmure de calcium ; Sp. Bromtiro de cal. OaBr^; 199.6. A white, granvilar salt, rapidly absorbing moisture on exposure to the air, and deliquescing to a syrupy liquid. Its specific grav- 288 MANUAL OF CIIEMTCAL ANALYSTS, ity is 3.32. When heated to 680° C. (1256° F.) the salt under- goes igneous fusion, and, at a higher teinperature, it is decomposed with the liberation of bromine. Calcium bromide is soluble in 0.7 part of water and in 1 part of alcohol at 15° C. (59° ¥.), and very freely soluble in boiling water and boiling alcohol. Its aqueous solution is neutral in its action upon litmus, and possesses a pungent, saline, and bitter taste; it yields a white precipitate with ammonium oxalate, soluble in hydrochloric, but insoluble in acetic acid ; and a white precipitate with argentic nitrate, which is sparingly soluble in ammonia- water. If a little chloroform or carbon bisulphide be added to a solution of the salt, and subsequently a little chlorine-water, drop by drop, and the whole agitated, the chloroform or carbon bisul- phide will acquire a yellow or yellowish brown color. One gram of the dry salt, when completely precipitated by argentic nitrate, yields a precipitate of argentic bromide which, when washed, and dried at 100^ 0. (212° F.), should weigh 1.878 grams. Examination : Brom.ate may be detected by a yellow coloration when diluted sulphuric acid is dropped upon the salt; or by adding to an aque- ous solution of the salt a few drops of diluted sulphuric acid, and subsequently a little chloroform or carbon bisulphide, and agita- ting the mixture ; if bromate be present, the chloroform or carbon bisulphide will acquire a yellow or yellowish-brown color. Iodide may be recognized in a solution of one part of the salt in about ten parts of water by the addition of a little mucilage of starch, and subsequently pouring a few drops of chlorine-water upon the surface of the liquid ; a blue coloration at the line of contact of the two liquids will reveal the presence of iodide. Chloride may be detected by completely precipitating a small portion of an aqueous solution of the salt with a,rgentic nitrate, collecting the resulting precipitate upon a filter, washing it tho- roughly with water, and subsequently digesting it with a concen- trated solution of ammonium carbonate ; the mixture is then filtered, and the filtrate supersaturated with nitric acid, when not more than afaintturbidity,insufficient toform a precipitate, should be produced ; a white, curdy precipitate would reveal the presence of more than traces of chloride. Sulphate may be detected in a solution of 1 part of the salt in about 20 parts of water by an ensuing white precipitate on the addition of a few drops of solution of barium chloride. Magnesium salts may be recognized by first adding to an aque- ous solution of the salt a little solution of ammonium chloride, and afterward solution of ammonium carbonate and ammonia- water until a precipitate ceases to be produced, and gently warm- ing ; the mixture is then filtered, and the filtrate tested with sodium phosphate, when an ensuing white, crystalline precipitate will reveal the presence of magnesium salt. CALCIUM. 289 CALCII CARBONAS PR^CIPITATUS, CALCIUM CARBONICUM PRECIPITATUM. CALCARIA CARBONICA PRECIPITATA. Precipitated Carhonate of Calcium. Precipitated Galcium Carbonate. Ger. Kohlensaurer Kalk ; Fr. Carbonate de chaux ; Sp. Carbonate de cal. CaCO,; 100. A white, light powder, without odor or taste, and permanent in the air. When obtained by precipitation from hot solutions, it is seen, when observed under the microscope, to consist of minute rhombic prisms, or, when precipitated from cold solutions, of minute rhombohedral crystals, although the crystalline form is frequently influenced by other substances which may be present in the solution. It displays a feebly alkaline reaction in contact with carefully prepared litmus ; when exposed to a red heat, par- ticularly when a current of air is passed over the surface, or, when heated upon charcoal before the blow-pipe, it loses carbonic acid gas, and is converted into calcium oxide, which possesses a strongly alkaline reaction. Calcium carbonate is almost insoluble in water, 1000 parts of water, either cold or hot, dissolving but about 0.018 part, aud is still less soluble in the presence of free ammonia or ammonium carbonate; but is more freely soluble in the presence of ammo- nium chloride or nitrate, with which, by mutual decomposition, a more readily soluble calcium salt is formed. It is also more freely soluble in water saturated with carbonic acid gas than in pure water; this solution reddens litmus, but changes the yellow color of turmeric-paper to brown ; by boiling or exposure to the air, the carbonic acid is evolved, and the calcium carbonate partially deposited; the liquid still retaining, in 1000 parts, 0.034 part of calcium carbonate in solution, and this solution does not render lime-water turbid. It is readily soluble, with effervescence, in dilute hydrochloric, nitric, and acetic acids. The solution in acetic acid is precipitated by oxalic acid, but not by a solution of calcium sulphate (distinction from barium and strontium car- bonates), nor by ammonia-water (evidence of the absence of aluminium and iron salts, and of phosphates), nor by potassium hydrate (distinction from magnesium carbonate). The solution should also afford no coloration or precipitate with hydrogen sul- phide, either when containing an excess of acid, or upon subse- quent supersaturation with ammonia-water (free from carbonate). Examination : If the calcium carbonate be agitated with a little water, and the mixture filtered, the filtrate should be perfectly neutral in its action upon litmus, and, with the exception of traces of dissolved carbonate, should leave no residue upon evaporation. Upon igni- tion, at a red heat, it should afford a perfectly white residue 19 ' 290 MANUAL OF CHEMICAL ANALYSIS. possessing a strongly alkaline reaction, without the development of any empyreumatic odor. An insufficient washing in the manufacture, or a fraudulent or accidental admixture of calcium sulphate, may be detected by agitating some of the carbonate with water, and by testing the filtrate, acidulated with one or two drops of nitric acid, in separa,te portions, with argentic nitrate for chloride, and with barium nitrate for sulphate. Magnesium carbonate may be recognized, in addition to the above-mentioned test, by adding to a neutral solution of the salt in acetic acid, first solution of ammonium chloride and then am- monium carbonate and ammonia-water until a precipitate ceases to be produced, and gently warming ; the mixture is then filtered, and the filtrate tested with sodium phosphate, when an ensuing white, crystalline precipitate will prove the presence of magnesium salt. The crude var'eties of calcium carbonate — chalk, prepared oyster-shells, and others derived from animal organisms — contain more or less of other bases (magnesium, iron, potassium, sodium, etc.) and acids (phosphoric, silicic, and sulphuric), and always, also, traces of organic substances ; they do not afford a complete solu- tion with dilute acetic or hydrochloric acid, and, although in every instance the acid solution should remain unaffected by hydrogen sulphide, yet upon subsequent supersaturation with ammonia- water a white or greenish turbidity is usually produced, depend- ent upon the presence of traces of phosphates. The estimation of the amount of carbonic acid contained in calcium carbonate may be accomplished by the method described for alkaline car- bonates, on page 86. CALCII CHLORIDUM. CALCIUM CHLORATUM. Cldoride of Calcium. Calcium Chloride. Ger. Chlorcalclum ; Fr. Chlorure de calcium ; Sp. Chloiuro de calcio. CaClj,; 110.8. A white, granular salt, or, as prepared by fusion, colorless, trans- lucent, and friable masses; it may also be obtained by crystalli- zation from its saturated solution in the form of largehexagonal prisms, having the composition CaCl, + 6HjO. The crystals melt at 29° C. (84.2° F.) in their water of crystallization, and deli- quesce rapidly by exposiire to the air, forming a thick syrupy liquid. When heated to 200° C. (392° F.), they lose 4 molecules of water, leaving a white, porous, hygroscopic mass, and, upon more strongly heating, the anhydrous salt is obtained ; the latter CALCIUM. 291 melts at a red heat, and, upon cooling, solidifies to a crystalline mass of the specific gravity 2.205, -which, in contact with a SQiall amount of water, produces a considerable elevation of temperature. Calcium chloride is soluble in 1.5 parts of water and in 8 parts of alcohol at 15° C. (59° F.), very freely soluble in boiling water, and soluble in 1.5 parts of boiling alcohol ; with alcohol it unites to form a crystallizable compound, having the composition CaClj + 4O2H5O, which is decomposed by water with the separa- tion of the alcohol; but is insoluble in ether. The aqueous solu- tion of the salt possesses a sharp saline taste, and is tieutral in its action upon litmus, unless the salt, by exposure to the heat of fusion, has undergone partial decomposition, with the loss of hy- drochloric acid, and the formation of a little calcium oxide, when it will have an alkaline reaction ; it yields white precipitates with the alkaline carbonates and phosphates, which are readily soluble in acetic acid, and, if the solution be not too dilute, a white crys- talline precipitate with sulphuric acid, which is soluble in a lai'ge amount'of water. The solution of the salt, even when very dilute, is likewise precipitated by oxalic acid and by argentic nitrate ; both precipitates being insoluble in acetic acid, and that with the latter reagent also insoluble in nitric acid, but readily soluble in ammonia-water. Anhydrous calcium chloride absorbs dry ammonia gas with great avidity, forming therewith a voluminous powder, having the com- position CaOlj + 8NH3 ; this is decomposed by exposure to the air, in contact with water, or on heating, with the loss of ammo- nia, and takes fire when thrown into chlorine gas. If a concentrated solution of calcium chloride is boiled with slaked lime, and the solution filtered while hot, a basic salt sepa- rates out on cooling, in long, white, needle-shaped crystals, having the composition ClGa-O-Oa(OH) + TSfi.' Solutions of calcium chloride of various degrees of concentra- tion Ave employed as baths for constant temperatures above 100° C. (212° P.), and the anhydrous salt, in consequence of its strong affinity for water, is largely employed as a desiccating agent, for drying gases, and for the removal of water from organic liquids. The crystallized salt, when dissolved in water, produces a consider- able diminution of temperature, and, when mixed with snow, in the proportion of 1.3 parts to 1 part of the latter, the temperature sinks to —48° 0. (—54.4° F.). Examination : Calcium sulphate may be detected by the incomplete solubility of the salt in alcohol, and may also be recognized in the aqueous solution of the salt by^an ensuing white precipitate on the addition of solution of bariiim chloride. Aluminium salts may be recognized in the aqueous solution, after the addition of a little ammonium chloride, by an ensuing white, flocculeut precipitate on the addition of ammonia-water or 292 MANUAL OF CHEMICAL ANALYSIS. ammonium sulphide; if the precipitate be brownish or black, it will indicate iron, which may also be recognized in the aqueous solution of the salt by a blue coloration or precipitate on the addition of a few drops of solution of potassium ferrocyanide. Magnesium salts may be recognized by adding to the aqueous solution, first a little solution of ammonium chloride, and subse- quently ammonium carbonate and ammonia- water until a pre- cipitate ceases to be produced, and gently warming; the mixture is then filtered, and the filtrate tested with sodium phosphate, when an ensuing white, crystalline precipitate will reveal the presence of magnesium. CALCII HYPOPHOSPHIS. CALCIUM HYPOPHOSPHOROSUM. CALCIS HYPOPHOSPHIS. SypophospJiite of Calcium. Calcium HypophospMte. Ger. Unterpliosphorigsaurer Kalk ; Fr. Hypophosphite de chaux ; Sp. Hipof6sfito de cal. Ca(H,PO,),; 170. Small, colorless, transparent, four-sided prisms, or thin, flexible scales, or a white, crystalline powder, of a pearly lustre, perma- nent in the air, and containing no water of crystallization. When strongly heated in a dry test-tube, the salt decrepitates, emitting inflammable vapors of hydrogen phosphide, and a little water, and leaving a residue, amounting to about 80 per cent, of its weight; this residue, after cooling, appears yellowish-red, and consists of a mixture of calcium pyrophosphate and metaphos- pbate, together with a little red amorphous phosphorus, resulting from the decomposition of the hydrogen phosphide. Calcium hypophosphite dissolves in six parts of cold water, and in about the same amount of boiling water, but is insoluble in alcohol (distinction from sodium hypophosphite); the aqueous solution has a slightly bitter taste, and, when largely diluted with water, suffers no change upon the addition of diluted sulphuric acid, nor with solutions of barium and calcium chlorides, nor of plumbic acetate (distinction from soluble phosphates and phos- phites); it forms, however, white precipitates with the soluble carbonates, with oxalic acid and oxalates, and with argentic nitrate, which latter precipitate, in consequence of its rapid reduc- tion to argentic phosphide and metallic silver, soon becomes black. When an aqueous solution of the salt, acidulated with hydrochloric acid, is added to an excess of solution of mercuric chloride, a white precipitate of mercurous chloride (calomel) is produced, and, on the further addition of the solution of hypo- phosphite, metallic mercury separates. CALCIUM. 293 Examination : The salt, when triturated with water, should not develop the alliaceous odor characteristic of hydrogen phosphide. Calcium sulphate will be indicated by au insoluble residue when a portion of the salt is digested with about ten times its weight of cold water, and may also be recognized in the aqueous solution, acidulated with nitric acid, by an ensuing white precipitate on the addition of a few drops of solution of barium chloride. Magnesium salts may be detected by first adding to an aqueous solution a little solution of ammonium chloride, and afterward solution of ammonium carbonate and ammonia-water until a pre- cipitate ceases to be produced, and gently warming; the mixture is then filtered, and the filtrate tested with sodium phosphate, when an ensuing white, crystalline precipitate will reveal the presence of magnesium. CALCII lODIDUM. CALCIUM lODATUM. Iodide of Calcium. Calcium Iodide. Ger. Jodcalcium ; Fr. lodure de calcium ; Sp. loduro de cal. Cal,; 293.2. A white, granular salt, or lamellar masses of a pearly lustre, rapidly absorbing moisture on exposure to the air, and deliques- cing to a syrupy liquid. When strongly heated, with access of air, it becomes decomposed, with the liljeration of iodine, and leaving a residue of calcium oxide. Calcium iodide is very freely soluble in both water and alcohol. Its aqueous solution is neutral in its action upon litmus, and pos- sesses a pungent, saline, and bitter taste ; it yields a white pre- cipitate with ammonium oxalate, soluble in hydrochloric, but insoluble in acetic acid, and a yellowish precipitate with argentic nitrate, which is nearly insoluble in ammonia-water. If a little chloroform or carbon bisulphide be added to a solution of the salt, and subsequently a little chlorine- water, drop by drop, and the whole agitated, the chloroform or carbon bisulphide will acquire a red or violet color. One gram of the dry salt, when completely precipitated by argentic nitrate, yields a precipitate of argentic iodide which, when washed, and dried at 100° 0. (212° F.), should weigh 1.59 grams. Examination : lodate may be detected in the aqueous solution of the salt by a yellowish or brown coloration on the addition of a little acetic or tartaric acid; the solution will then also impart a blue color to 294 MANUAL OF CHEMICAL ANALYSIS. muoilage of starch, and a red or violet tint to a few drops of chloro- form or carbon bisulphide, when agitated therewith, if iodate be present. Chlorides and Bromides. — To a small portion of the salt, dis- solved in water, solution of argentic nitrate is added until a precipitate ceases to be produced. The resulting precipitate is collected upon a filter, washed with water, and subsequently digested with a strong solution of ammonium carbonate, and fil- tered; the filtrate is then slightly supersaturated with nitric acid, when an ensuing turbidity, or the formation of a white, curdy precipitate, will reveal the presence of chloride. . The residue upon the filter is digested with a considerable excess of ammonia- water, filtered, and the filtrate slightly supersaturated with nitric acid, when not more than a faint turbidity should ensue ; a white, curdy precipitate will reveal the presence of bromide. Sulphate may be detected in a solution of 1 part of the salt in about 20 parts of water by an ensuing white precipitate on the addition of a few drops of solution of barium chloride. Magnesium salts may be recognized by first adding to an aque- ous solution of the salt a little solution of ammonium chloride, and afterward solution of ammonium carbonate and ammonia- water until a precipitate ceases to be produced, and gently warm- ing; the mixture is then filtered, and the filtrate tested with sodium phosphate, when an ensuing white, crystalline precipitate will reveal the presence of magnesium. CAIiCII PHOSPHAS PR.5!CIPITATUS. CALCIS PHOSPHAS. CALCIUM PHOSPHORICUM. CALCARIA. PHOSPHORICA. Precipitated Phosphate of Oalcium. Tribasie Galcium Phosphate. Normal Calcium Orthophoaphate. 6er. Neutraler Phosphorsaurer Kalk ; Fr. Phosphate de chaux precipite ; Sp. Fosfato de cal. Oa/POJ,; 310. A light, white, inodorous, and tasteless powder, which, when dried at 100° C. (212° F.), contains no water, and is perfectly amorphous. It is fusible, without decomposition, at an intense heat, and the powder, before or after ignition, assumes when moistened with a solution of argentic nitrate a straw-yellow color (distinction from acid calcium phosphate). Neutral calcium phosphate is nearly insoluble in water, but upon long boiling therewith it is decomposed with the formation of an insoluble basic salt, Caj^POJ, + Oaj(POj)OH, and a soluble acid salt which dissolves ; it is more readily soluble in water satu- rated with carbonic acid gas, as also in solutions of sodium nitrate, CALCIUM. 295 sodium chloride, amraoniaca], and other salts, and is freely soluble iu nitric, hydrochloric, and acetic acids. An acid calcium phosphate (Monohydrogen Calcium Ortho- phosphate, CaHPO^ 4- 2HjO) is officinal in the German, Austrian, and Swiss Pharmacopoeias. This salt is obtained as a crystalline powder, consisting of microscopically small, monoclinic tables or prisms, of an acid reaction, and containing two molecules (20.93 per cent.) of water of crystallization; when heated to from 150 to 200° C. (302 to 392° F.), it loses its water of crystallization, and, at a higher temperature, water of constitution is also eliminated, amounting in all to 26 per cent, of its weight. When moistened with a solution of argentic nitrate, it assumes a yellow color, which is not the case, however, after having been strongly heated upon platinum-foil, in consequence of its conversion into calcium pyrophosphate : 2CaHP0^ = H^O -f Oa^PjO,. In its relation to solvents, the characters of acid calcium phosphate are similar to those of the normal salt, as above described, but it is not readily soluble in acetic acid. Both varieties of calcium phosphate are readily and completely soluble in warm, diluted nitric acid, without effervescence. The solution., when heated with a few drops of a solution of ammonium molybdate, affords a yellow crystalline precipitate of ammonium phospho-molybdate (presence of phosphoric acid), and, after the addition of ah excess of sodium acetate, yields a copious white precipitate on the addition of a solution of oxalic acid or ammo- nium oxalate (presence of calcium). Examination : Carbonates are indicated by effervescence when a little of the calcium phosphate is first thoroughly mixed with a little water, and concentrated nitric acid afterwards added. Barium and strontium salts may be detected in the dilute nitric acid solution by a white precipitate on the addition of a solution of calcium sulphate. Chlorides are detected in the dilute nitric acid solution by a white curdy precipitate on the addition of solution of argentic nitrate, which is soluble in ammonia-water, but insoluble in nitric acid. Sulphates may be detected by agitating a little of the calcium phosphate with water for a few moments, filtering, and, after acidulating with a few drops of acetic acid, testing with solution of barium hydrate or nitrate ; a white precipitate will reveal the presence of sulphates. Magnesium Phosphate. — A portion of the salt is dissolved in hydrochloric acid, an excess of sodium acetate and a little solu- tion of ferric chloride are added, and the mixture boiled and filtered ; to the colorless filtrate a little ammonium chloride is added, and subsequently ammonium oxalate until a precipitate ceases to be produced ; after standing for a few hours, the mixture 296 MANUAL OF CHEMICAL ANALYSIS. is filtered, and to the filtrate solution of sodium phosphate and ammonia-water in slight excess are added, when an ensuing white crystalline precipitate will reveal the presence of magnesium. L'on and metallic salts are detected by first saturating the solu- tion of the calcium phosphate in dilute hydrochloric acid with hydrogen sulphide, and subsequently supersaturating the acid liquid with ammonia-water. The solution must remain perfectly unchanged with the first-named reagent, and the ensuing precipi- tate upon the addition of the latter should be perfectly white ; a black coloration would indicate iron, which would likewise be detected in the dilute acid solution of the salt by a blue colora- tion or precipitate on the addition of a few drops of solution of potassium ferrocyanide. CALX CHLORATA. CALX CHLORINA.TA. CALCARIA CHLORATA. CALCIUM HYPOCHLOROSUM. CALCARIA HYPOCHLOROSA. Chlorinated Lime. Bleaching -Powder. Oalcium Hypochlorite. Ger. Clilorkalk ; Fr Chlorure de chaux ; Sp. Hipoclilorito de cal. A homogenous, dull-white, granular powder, possessing an alkaline reaction, the odor of hypochlorous acid rather than of chlorine, and becoming moist and gradually decomposing on exposure to the air. In its composition, chlorinated lime is commonly regarded as a mixture of calcium hypochlorite and chloride, together with undecomposed hydrate, and its formation represented by the equation : 2Ca(0H), -1- 2C1, = Ca(OCl), -)- CaCl, + 2H,0. With reference, however, to the amount of available chlorine which can be obtained from a perfectly saturated product, it may be considered, with a much greater degree of probability, as con- sisting of a mixture of a basic salt (calcium hydroxy-chloride), with calcium chloride ; and its formation expressed by the equation : 3Ca(0H), -I- 201, = 2C;i<^g^j + CaCI, + 2B.fi. Calcium hydroxy- chloride. In contact with water, the calcium chloride dissolves, and the basic salt is decomposed, with the formation of calcium hypochlo- rite and hydrate, as follows: „^ /OH p„/OH ^ ^ /0Q\ CALCIUM. 297 When exposed to a gentle heat, chlorinated lime is converted, according to its composition and the temperature, into calcium chlorate and chloride, and, at a higher temperature, by de- composition of the chlorate, yields oxygen, and probably also some chlorine ; by the action of sunlight, it is partially decom- posed with the formation of calcium chlorate and chloride, and the liberation of oxygen. When well mixed with ten or more parts of water, it forms a creamy liquid, while its soluble con- stituents enter into solution, leaving behind calcium hydrate, and the insoluble impurities of the lime employed in the manufacture of bleaching-powder ; the filtered solution is colorless, and of an acrid, nauseous taste, changes red litmus for a moment into blue, and decolorizes it almost at once, and completely ; it emits the odor of chlorine with acids, and forms a white precipitate with sulphuric and oxalic acids. By the decomposition of chlorinated lime with acids the entire amount of contained chlorine is available, as shown by the follow- ing equations : (1) CaClj -1- Ca(OCl), + 4HC1 = 2C1, + 2CaCl, -f" 2H,0. (2) CaCij + Ca(OCl), + 2H,S0, = 201, -I- 2CaS0, + 2H,0. Chlorinated lime, exposed to the carbonic acid and moisture of the air, evolves hypochlorous acid, which, when free, readily breaks up into water, chlorine, and chloric acid ; the latter is also soou resolved into oxygen, water, chlorine, and perchloric acid; a deliquescent residue, consisting of calcium hydrate, carbonate, and chloride, forms the final residual product. Upon this decomposi- tion, or by the direct elimination of chlorine through the agency of stronger acids, depends the energetic chemical action of chlori- nated lime as an oxidizing agent, which, therefore, is proportionate to the percentage of calcium hypochlorite, or, in other words, of the available chlorine, which, for most pharmaceutical and thera- peutical purposes, should amount to 25, or, as the minimum, 20 per cent. In order to estimate this, and to determine the value of commercial bleaching-powder, several methods of testing are employed, among which the following two are simple and reliable : I. 1.96 parts of pure crystallized ferrous sulphate are dissolved in a capacious glass flask in a mixture of 20 parts of water and 5 parts of hydrochloric acid; 1 part of chlorinated lime is then thoroughly mixed, by trituration in a mortar, with 50 parts of water, and the mixture added at once to the solution of the fer- rous salt. The flask being then tightly closed, it is actively agitated for a few minutes, and the mortar in which the chlori- nated lime was triturated, subsequently rinsed with a little water, and this liquid added to the contents of the flask. After ^.gain agitating for a moment, the liquid should still retain the odor of chlorine, and, after filtration, when tested with a few drops of a 298 MANUAL OF CHEMICAL ANALYSIS. solutioa of potassium ferridoyanidc, should afiford no blue colora- tion or precipitate. This test, when employed with the above stated proportions of ferrous sulphate and chlorinated lime, will indicate a strength of the latter corresponding to at least 25 per cent, of available chlo- rine. With the employment of 1.57 parts of ferrous sulphate to 1 part of chlorinated lime, the application of the same test, which is based upon the oxidation of the ferrous to ferric salt through the agency of the liberated chlorine, will then indicate a strength of the chlorinated lime corresponding to at least 20 per cent, of available chlorine. The United States Pharmacopoeia directs that if 0.71 gram of chlorinated lime be mixed with a solution of 1.25 grams of potas- sium iodide in 120 cubic centimeters of water, and 9 grams of hydrochloric acid be then added, the resulting red-brown liquid should require for complete decoloration not less than 50 cubic centimeters of standard solution of sodium hyposulphite, corre- sponding to at least 25 per cent, of available chlorine. II. The following method of estimation will afford an accurate result, when not alone the minimum, but the determination of the exact percentage amount of chlorine contained in the chlorinated lime is desired. One gram of the chlorinated lime is triturated in a mortar with a small portion of water until a uniform pasty mass is obtained, which is afterwards further diluted with water, and, together with the rinsings of the vessel, transferred to a graduated cylinder, provided with a glass-stopper (Fig. 104), and the liquid finally diluted to 100 cubic centimeters. The one per cent, solution thus ob- tained, after being thoroughly mixed by agitation, is allowed to repose until it becomes perfectly clear; 50 cubic centimeters of the clear liquid are then carefully drawn off by means of .a pipette, and al- lowed to flow into a solution of 2 grams of potas- sium iodide in about 20 cubic centimeters of water, contained in a beaker. To the mixed solutions hydrochloric acid sufficient to render the mixture slightly acid is added, and the liberated iodine subsequently estimated by means of a standard solution of sodium hyposulphite, page 94. The strength of the sodium hyposulphite solution, or the amount of pure iodine corresponding to one cubic centimeter of the same, being known, the number of cubic centimeters required to produce decoloration of the liquid will indicate the amount of iodine libe- rated by the chlorine, and therefrom, by simple equivalent proportion (I, 127 = 01, 35.5), the amount of chlorine contained in the number of cubic centi- FiG. 104. CALCIUM. 299 meters of the solution of chlorinated lime employed, from which the percentage strength of the chlorinated lime in active chlorine may be readily calculated. In consequence of the facility with which chlorinated lime undergoes decomposition, particularly by exposure to the air and moisture, the amount of active chlorine contained in the commer- cial article is often found to vary from 10 to 35 per cent. CALX SULPHURATA. CALCIUM SULFURATTJM. Sulphurated Lime. Galcium Sulphide. Ger. Scliwefelkalk ; Fr. Sulfure de calcium ; Sp. Sulfuro de calcio. Pure calcium monosulphide, CaS, forms a white or yellowish - white mass, which is very sparingly soluble in water, and in moist air develops the odor of hydrogen sulphide. As prepared by the reduction of calcium sulphate with carbon, or by the ignition of a mixture of caustic lime and sulphur (Calx Sul- phurata, U. S. P.), a grayish or reddish-white mass is obtained, which is not a definite chemical compound, but consists of a mix- ture of calcium sulphide and polysulphides, with small and vari- able amounts of calcium sulphate, and carbonaceous matter or other impurities. Calcium sulphide is dissolved to but a small extent by water, and, upon boiling therewith, is partially decomposed, with the formation of calcium hydrate and sulphydrate: 2CaS -4- 2H2O = Ca(HS)2 4- Ca(0H)3. The solution is at first colorless, but, on exposure to the air, becomes decomposed, with the absorption of oxygen and carbonic acid gas, and acquires a yellowish color ; it possesses an alkaline reaction, and the odor of hydrogen sulphide, which latter gas is abundantly developed therefrom upon the addition of an acid. Calcium sulphide, when shaken with water, and the liquid fil- tered, should yield a solution which is not precipitated by solution of calcium sulphate, but affording upon the addition of solu- tion of ammonium oxalate a white precipitate, soluble in hydro- chloric, but insoluble in acetic acid. It should dissolve in dilute hydrochloric acid, with the abundant development of hydrogen sulphide, and without leaving a considerable insoluble residue. The presence of at least 86 per cent, of pure calcium sulphide in sulphurated lime may be ascertained by gradually adding 1 gram of the salt to a boiling solution of 1.25 grams of cupric sul- phate in 50 cubic centimeters of water; the mixture is then heated nearly to boiling for about ten minutes, and, when cold, filtered. The filtrate, when tested with one drop of test-solution of potassium ferrocyanide, should remain colorless. 300 MANUAL or CIIEMtCAL ANALYSIS. CAMFHORA MONOBROMATA. Monobromated Camphor. Camplwr Monobromide. Ger. Monobromcamplier ; Fr. CarapUre raonobrome ; Sp. Monobromato de alcanfor. C,„H„BrO; 230.8. Thin, colorless prisms, vrhen crystallized from alcoliol, or elon- gated, fiat prisms, whicli are perfectly transparent and hard, when crystallized from petroleum benzin. It is permanent in the air; not affected by direct sunlight ; slowly volatilized when boiled in water, and possesses an odor reminding of Borneo camphor, and a taste which is terebinthinate and scarcely bitter. It fuses at 65 C. (149° F.), and boils at 274° 0. (525.2° F.), with partial decompo- sition ; it does not sublime at ordinary temperatures, but sublimes abundantly at temperatures above its fusing-point, in the form of long, slender, colorless needles. Monobromated camphor is almost insoluble in water, and spar- ingly soluble in glycerin, but freely in alcohol, although less so than ordinary camphor, and is readil3' dissolved by ether, chloro- form, carbon bisulphide, warm petroleum benzin, and the volatile and fatty oils; it is also soluble in cold, concentrated sulphuric acid, and is precipitated unchanged upon the addition of water. In alcoholic solution, in contact with sodium amalgam or argentic nitrate, it is converted into ordinary camphor ; and, when boiled with a solution of argentic nitrate in dilute nitric acid, it is decomposed, with the formation of argentic bromide, corresponding in amount to 81.2 per cent, of the monobromated camphor employed. CANTHARIDINUM. OantJiaridin. Ger. Cantbaridin ; Pr. Cantbaridine ; Sp. Cantaridiiia. C,H„0,; 196. Bright, colorless, rhombic prisms or laminje (Fig. 105), per- manent in the air. When heated to 210° G. (410° F.) they soften, and fuse at 218° C. (424.4° F.) ; at higher Fig. 105. temperatures, by the cautious application of heat, they may be sublimed unchanged. Oautharidin is soluble in 30,000 parts of cold, and half that amount of boiling, water, and sparingly soluble in cold alco- hol and carbon bisulphide, but quite readily soluble in hot alcohol, and in chloroform, ether, acetic ether, benzol, and the volatile and fatty oils, particularly upon warming. CARBONEKM. 301 When digested for some time at about 100° C. (212° F.) with a dilute solution of potassium or sodium hydrate, it is converted, by assimilation of the elements of water, into cantliaridic acid^ C,„H,„0|5, or CjHg03, which combines with the alkali with the for- mation of well crystallizable salts. The aqueous solution of these salts possesses an alkaline reaction, and, upon the addition of a stronger acid, cantharidic acid is separated, but becomes, by the elimination of the absorbed elements of water, immediately re- solved into cantharidin. When heated with hydriodic acid of the spec. grav. 1.8, can- tharidin is gradually converted into the crystallizable, monobasic caniharic acid, which has the same composition as cantharidin ; it is soluble, however, in 120 parts of cold, and 12 parts of boil- ing, water, very soluble in alcohol, sparingly in ether, and does not produce vesication when its solution in glycerin is applied to the skin. Cantharidin is an active poison, and, when applied to the skin, exerts powerful vesicating properties, which, for the want of any distinguishing chemical tests, may be employed as a means for its identification. For the separation of cantharidin when associated with alka- loids or other organic principles, see page 106. CARBONEI BISTJLPHIDtlM. CARBONEUM SULFURATUM. ALCOHOL SULFURIS. BisulpJiide of Carton. Carbon Bisulphide. Ger. Schwefelkolilenstoff ; Fr. Sulfiire de carlione; Sp. Bisulfuro de carbon. CS,; 76. A transparent, colorless, very volatile liquid, of great refrac- tive and dispersive power, of a pungent, somewhat aromatic taste, and a peculiar odor, which, when pure, slightly resembles that of chloroform. Its spec. grav. is 1.272 at 15°'C. (59° F.), and it boils at 47° C. (116.6° F.), but does not solidify when ex- posed to a temperature of — 110° C. (—166° F.). It is highly inflammable, taking fire in the air at 149° C. (300.2° F.), and burns with a blue flame, yielding, as the products of combustion, carbon dioxide and sulphur dioxide. Its vapor, when mixed with one-third of its volume of oxygen or atmospheric air, forms an explosive gas, which detonates with great violence in contact with flame ; when mixed with nitric oxide, its vapor burns upon ignition with a very bright blue flame, which is particularly rich in chemically active rays. Carbon bisulphide is not dissolved to any appreciable extent 302 MANUAL OF CHEMICAL ANALYSIS. by water, and sinks in that liquid ; when agitated with iodine- water, it absorbs the niinute quantity of iodine dissolved in the water, and acquires a faint, purple color. Carbon bisulphide is remarkable and important on account of its extensive solvent powers; it is miscible, in all proportions, with absolute alcohol (the solubility decreasing with the decrease of strength of the alcohol), with ether, chloroform, benzol, essen- tial and fatty oils; it dissolves readily and freely, among other substances, sulphur, phosphorus, bromine, iodine, iodoform, cam- phor, caoutchouc, gutta-percha, many resins, wax, paraffin, stearin, chloral hydrate, and many alkaloids which are soluble in ether and alcohol. The vapor of carbon bisulphide is a powerful anti-putrescent, and retards fermentation, but is also an active poison when in- haled in large quantity, and is capable of producing very serious effects when inhaled for a considerable time, even in very small amount. By exposure to sunlight, carbon bisulphide becomes partially decomposed, acquiring a disagreeable odor and a yellowish color; it then contains sulphur in solution, and reddish-brown flocks of polymeric carbon monosulphide (CS)i are separated. When preserved under water, it also acquires a yellowish color, with the formation of small amounts of carbonic and sulphuric acids, and, when heated with water in a sealed tube, at 150° C. (302° F.), it is further decomposed with the formation of hydro- gen sulphide. Carbon bisulphide may be recognized, even in very minute quantities, by warming it in a closed flask with concentrated ammonia-water, or by mixing it with a little ammoniacal alcohol and gently heating ; these liquids furnish, upon evaporation on the water-bath, a residue consisting of ammonium sul- phocyanide, which, when dissolved in 'a little water, and a drop of solution of ferric chloride added, yields the characteristic blood-red color of ferric sulphocyanide. Examination : The odor of carbon bisulphide should not be re- pulsive, nor fetid ; it should not cause a dark tur- bidity or precipitate in a solution of plumbic acetate, when agitated with it (absence of hydrogen sul- phide), nor change the color of moist litmus-paper (absence of sulphurous acid), and, when allowed to evaporate spontaneously upon a watch-glass, should leave no residue (absence of free sulphur, or other impurities). An admixture of ethyl or methyl alcohol may readily be detected by the lesser specific gravity of the liquid, by its impaired property of dissolving Fig. 106. r i" CERIUM. 303 fatty oils, and by its diminution in volume when shaken, in a graduated cylinder (Fig. 106), with an equal volume of water or glycerin. CERII OXALAS. CERIUM OXALICUM. Oxalate of Cerium. Cerium Oxalate. Ger. Ceroxalat ; Fr. Oxalate de cerium ; Sp. Oxalate de cerium. Ce,(CA), + 9H,0; 708. A white, granular powder, without odor or taste, containing 9 molecules (22.88 per cent.) of water, and permanent in the air ; it is almost insoluble in water, alcohol, ether, chloroform, and solu- tions of potassium or sodium hydrate, but soluble in hydrochloric and sulphuric acids. Exposed to heat, the salt is decomposed, and at a dull red heat is completely converted into ceroso-ceric oxide, Ce,Oj, which is of a dark-red color when hot, yellowish- white when cold (a brown color would indicate the presence of didymium), and soluble without effervescence in boiling hydro- chloric acid; this solution gives, with an excess of a saturated solution of potassium sulphate, a crystalline precipitate of potas- sium-cerous sulphate, SK^SO^ -f Cej(S0j3. Cerium oxalate, when heated with a solution of potassium hydrate, filtered, and the filtrate neutralized with acetic acid, affords upon the addition of a solution, of calcium chloride a white precipitate of calcium oxalate, which is insoluble in acetic, but readily and completely soluble in hydrochloric acid. Examination : Earthy carbonates are indicated by effervescence of the salt with hydrochloric acid. Soluble salts may be readily detected by digesting the cerium oxalate with water, filtering, and evaporating the filtrate to dry- ness ; any considerable residue, upon evaporation, will reveal the presence of such impurities. Alumina or aluminium salts may be detected by boiling the oxalate of cerium with a strong solution of potassium hydrate, filtering, and adding an excess of solution of ammonium chloride, when a white, flocculent precipitate of aluminium hydrate will be formed, if such be present. Other impurities, such as metallic oxides, insoluble earthy phosphates, foreign oxalates, etc., may be sought for, when indi- cated, according to the systematic methods of analysis, as described on pages 51 to 61. 304 MANUAL OF CHEMICAL ANALYSIS. CHINOIDINUM. Ghinoidin. Quinoidin. Ger. Chhioidin ; Fr. Quinoidine ; Sp. Quinoidina. A brittle, resin-like mass, of a deep brown color, a glossy, con- choidal fracture, and a peculiar aromatic odor, and consisting principally of diquinidine, C^oH^jN^Oj, accompanied by varying amounts of qninicine, OjoHj^NjO^, cinchonicine, C^oHj^JST^O, and other amorphous bases; it becomes soft and tough, at a moderate temperature, and melts like a resin when warmed; at a stronger heat, it burns away, and leaves, upon incineration, a white ash, which should not amount to more than 0.7 per cent, of its weight. Ghinoidin is almost insoluble in water, and only partly soluble in ether, benzol, and in glycerin, but freely soluble in diluted acids, in alcohol, and in chloroform, forming dark brown solutions of an aromatic, bitter taste and odor ; the alcoholic and ethereal solutions are precipitated by water, and the acid aqueous solution becomes green when first mixed with sufficient chlorine- water to decolorize it, and subsequently with an excess of ammonia- water. Examination : Gmn- Resins. —A. small portion of the triturated chinoidin is agitated, in a test-tabe, with about 20 times its weight of water; the mixture is then heated to boiling, with constant agitation; when cool, the water must be nearly colorless, and remain so upon the addition of a few drops of a concentrated solution of potassium hydrate, and subsequent heating; if a brown colora- tion takes place, in either of these tests, gum-resins (aloes) or other soluble admixtures (liquorice, glucose, dextrin, etc.) are indicated. Resins may be detected in the chinoidin remaining undissolved in the preceding test, by dissolving it, with the aid of heat, in diluted sulphuric acid; a complete or almost complete solution must take place, otherwise an admixture of resins, insoluble in diluted acids, is indicated. As a confirmatory test for gum-resins, liquorice, glucose, etc., a few drops of the obtained solution may be allowed to fall into alcohol; they must form a clear solution; an ensuing turbidity would establish the presence of such admixtures. Inorganic admixtures are indicated by an insoluble residue when the chinoidin is dissolved in alcohol, or by a residue left upon ignition.* Copper may be specially sought for in the residue left upon * In consequence of the slow combustion of the substance, its complete ignition may be facilitated by the addition of a few drops of nitric acid to the carbonaceous residue left upon heating, and again strongly heating, when the organic matter will become completely removed. • CJILORALTJM. 305 ignition, bj dissolving it in a few drops of warm bydrochloric acid, and, after dilution with water, testing the solution in separate portions, with a drop of solution of potassium ferrocyanide, and with an excess of ammonia-water ; a reddish-brown turbidity with the first-named reagent, and a blue coloration of the liquid with the latter, will determine the presence of copper. CHLORAL. CHT.ORALI HYDRAS. CHLORALUM HYDRATUM. Chloral. Hydrate of Chloral. Chloral Hydrate. Ger. Chloralhydrat ; Fr. Hydrate de chloral ; Sp. Hidrato de cloral. C^HCljO -H H,0 = CCl3-CH^Q^ ; 165.2. Colorless, semi-transparent, needle shaped crystals, or crystal- line plates, belonging to the monoclinic system, and possessing a peculiar ethereal odor and pungent taste. Exposed in a dry test- tube to a gentle heat, by dipping the tube into hot water, chloral hydrate fuses at 58^ C. (136.4° F.), forming a clear, colorless liquid of the spec. grav. 1.575, which, at 46° C. (114.8° F.), again solidi- fies ; at 78° C. (172.4° F.), it is resolved into chloral, which boils at 99° C. (210.2° F.), and water, and, at a higher temperature, is wholly volatilized, without the evolution of inflammable vapors. Chloral hydrate is soluble in about half its weight of cold water, and freely in both alcohol and ether, but only sparingly soluble in cold chloroform, in carbon bisulphide, in benzol, benzin, and in fixed and volatile oils. Its aqueous solution possesses a faintly acid reaction, but, when slightly acidulated with diluted nitric acid, no change, or but a faint opalescence, should be produced upon the addition of solution of argentic nitrate ; upon the sub- sequent addition of a little ammonia- water, however, and heating the mixture, decomposition takes place with effervescence, and with the formation of argentic chloride and metallic silver, the latter coating the walls of the tube. When the aqueous solution is acidulated with diluted sulphuric acid, and faintly tinged with a few drops of solution of potassium permanganate, no decolora- tion should take place within a few hours. The alcoholic solution of chloral hydrate, in distinction from the aqueous, should not affect the color of moistened blue litmus-paper, and should also afford no turbidity upon the addition of a solution of argentic nitrate. Concentrated sulphuric, nitric, and hydrochloric acids dissolve chloral hydrate with decomposition, but without color, and with- out the evolution of colored vapors. Solutions of the alkaline 20 306 MANUAL OF CHEMICAL ANA"LYSIS. hydrates decompose it, when heated, into soluble forniiates and chloroform. Ammonium sulphide dissolves chloral hydrate, with the evolution of heat, forming a turbid, reddish-brown liquid ; the same reagent produces, in concentrated as well as in diluted solutions of chloral hydrate, a yellow coloration, which becomes dark brown, forming, with the separation of sulphur, a reddish- brown compound, gradually when cold, immediately upon warming. Chloral hydrate liquefies when mixed with carbolic acid or with camphor, without decomposition, and is separated again by the subsequent addition of water. Examination : Decomposition of chloral hydrate is indicated by the emission of vapors and by a pungent odor upon opening the vial, by the reddening of moistened blue litmus-paper when immersed in it, as also by a yellowish color and incomplete solubility in water, with the formation of oily drops. It is further indicated, in the aqueous solution of chloral hydrate, acidulated with a few drops of diluted nitric acid, by a white precipitate with argentic nitrate, and in another portion, acidulated with sulphuric acid, by decoloration of solution of potassium permanganate. Chloral alcoho2ate,G^BG\0+G,TL,0 = (CCIj-Ch/q^^^^ is distinguished from the hydrate by the evolution, upon strongly heating, of inflammable vapors, which burn with a yellowish, smoky flame ; by the property of being readily and freely soluble in co?5 chloroform, in carbon bisulphide, or in oil of turpentine, but less soluble in cold water than is the hydrate; and by its yielding a reddish-brown or brown solution with warm concen- trated sulphuric acid, and by the evolution Fig. 107. of red nitrous vapors with concentrated nitric acid. An admixture of the alcoholate with the hydrate may be detected by dissolving a portion of the salt in about 10 times its weight of water, in a test-tube, adding suf- ficient of a s^ -f HjO), and the specific gravity 4:.4:o4:0, and, upon gentle ignition, is completely converted into red ferric oxide, FcjOj. Ferric hydrate is slowly but wholly soluble in moderately dilute acids, even in acetic acid, without any considerable efferves- cence (a small amount of carbonic acid being absorbed by its exposure to the air) ; when dissolved in cold hydrochloric acid, the solution, after dilution with water, yields a blue precipitate with potassium ferrocyanide, but should not afford a blue coloration with potassium ferricyanide, and, upon saturation with hydrogen sulphide, but a white precipitate of sulphur should be produced. The acid solution, after complete precipitation by ammonia-water in excess, and subsequent filtration, should yield a colorless fil- trate, which affords no precipitate upon the subsequent addition of either ammonium sulphide, ammonium oxalate, or sodium phos- phate (evidence of the absence of zinc, calcium, and maynesium). Examination : Alkaline sulphates or chlorides may be detected by agitating the ferric hydrate with a little warm water, acidulating the filtrate with a few drops of nitric acid, and subsequently testing with barium chloride and argentic nitrate ; a white precipitate in either case will reveal the presence of such impurities, which may result from imperfect washing, in its preparation from ferric sulphate' or chloride. Ammonia will be detected by its odor, when a small portion of the ferric hydrate is gently heated, in a test-tube, with a concen- trated solution of potassium or sodium hydrate ; and by the for- mation of white fumes, when a glass rod, moistened with acetic acid, is held over the mouth of the tube. FERRUM. 357 Copper may be detected by a blue coloration of ammonia-water or a solution of ammonium carbonate, when agitated with the ferric hydrate, and subsequently filtered ; its presence may be confirmed or reyoguized, when the result of the preceding test is uncertain, by supersaturing the filtrate with acetic acid, and test- ing it with potassium ferrocyanide ; a reddish-brown precipitate would indicate or confirm the presence of copper. Other metallic impurities, if present, will be indicated by the above-described characters and tests, and, when required, their nature may be determined, according to the systematic method of analysis, as described on pages 51-61, PERRI PHOSPHAS.* FERRUM PHOSPHORICUM. FERRUM OXYDULA.TO-OXYDATUM PHOSPHORICUM. Phosphate of Iron. Ferrous Phosphate. Ger. Phosphorsaures Eisenoxydul ; Fr. Phosphate de fer ; Sp. Posfato de hierro. Fe3(P0,),+ H,0; 375.7. A fine, amorphous, tasteless powder, of a slate-blue color when dry, but which, upon prolonged boiling with water, assumes a greenish color. When heated in a dry test-tube, it gives off water, and leaves a black residue. Ferrous phosphate is insoluble in water, but soluble in the mineral acids ; with phosphoric acid it forms a clear, colorless solution, whilst its solution in hydrochloric acid, in consequence of the contained ferric salt, a result of superficial oxidation, pos- sesses a yellow color ; the latter solution, when largely diluted with water, consequently yields a blue precipitate with both potassitim ferricyanide and ferrocyanide, and, upon saturation with hydrogen sulphide, affords a slight white turbidity or opales- * The phosphate of iron (Ferri Phosphas) of the U. S. Pharmacopoeia is a mixture of ferric pliosphate with sodium citrate, prepared by dissolving sodium phosphate in a solution of ferric citrate, evaporating the solution to the consistence of a thick syrup, and spreading it on plates of glass, so that, on drying, the salt may be obtained in scales. It thus forms thin, transparent scales, of a bright green color, permanent in tlie air, but becoming darlc on ex- posure to the light. It is readily and completely soluble in water, but insoluble in alooliol. Its aqueous solution is neutral in its action upon litmus, yields a blue coloration with solution of potassium ferrocyanide, and, after acidulation with hydrochloric acid, a blue precipitate; when heated with an excess of a concen- trated solution of potassium hydrate, it yields a brownish-red precipitate of ferric hydrate, and the filtrate, after supersaturation with acetic acid, yields a light yellow precipitate with solution of argentic nitrate (distinction from ferric pyro- phosphate). The salt contains an amount of ferric pliosphate corresponding to about 13.5 per cent, of metallic iron. 858 MANUAL OF CHEMICAL ANALYSIS. cence, due to the separation of sulphur, but no dark coloration should be produced. When ferrous phosphate is boiled in a solution of sodium car- bonate, and filtered, a filtrate is obtained which, when exactly neutralized with dilute nitric acid, gives a yellow precipitate with argentic nitrate, and a white crystalline precipitate with magne- sium mixture, but, after acidulation with hydrochloric acid, should afford upon saturation with hydrogen sulphide, either in the cold or upon warming, no coloration or precipitate (a yellow turbidity would indicate the presence of arsenic). Examination : Sodium sulphate, left from iusufl&cient washing, may be de- tected when a little of the powder is shaken with some hot water, and the filtrate tested with barium chloride. Metals. — A strong solution of the powder in hydrochloric acid, after dilution with water, is saturated with hydrogen sulphide, and set aside for a few hours, in a closed flask, in a warm place ; Fig. 117. a slight white turbidity (sulphur) will occur ; a dark coloration would indicate copper^ a yellow one, arsenic, which latter, in con- nection with the above mentioned test, may be confirmed by the odor when a little of the salt is heated upon charcoal, before the FBRRUM. 359 blow-pipe, or by the formation of a metallic mirror, in a narrow tube (Fig. 117), upon heating the dried precipitate with about six times its weight of a mixture of equal parts of exsiccated sodium carbonate and potassium cyanide. FERRI PYROPHOSPHAS. FERRUM PYROPHOSPHORICUM. PyropliospTiate of Iron. Ferric Pyrophosphate. Ger. Pyropliosphorsauves Eisenoxyd ; Fr. Pyrophosphate de fer ; Sp. Pirofosfato de hierro. Fe,(P,0,)3 + 9H,0 ; 907.6. A white, tasteless powder, which, when heated in a dry test- tube, loses water and decreases in volume, but remains white. It is insoluble in water, bat soluble in hydrochloric acid, and in solutions of sodium pyrophosphate and of alkaline citrates; its solution in dilute hydrochloric acid has a yellowish color, and affords a blue precipitate with potassium ferrocyanide, and, upon saturation with hydrogen sulphide, a white turbidity, due to the separation of sulphur, but no dark coloration is produced. When boiled with a solution of sodium carbonate, ferric pyrophosphate assumes a reddish brown color, and yields a filtrate of the same tint, but which becomes almost decolorized upon slight super- saturation with acetic acid, and gives a dense, white precipitate with argentic nitrate (distinction from ferric orthophosphate, which gives a yellow precipitate, and from ferric metaphosphate, which gives a white gelatinous one). FERRI PYROPHOSPHAS ET SODII CITRAS. FERRUM PYROPHOSPHORICUM CUM NATRIO CITRIGO. Pyrophosphate of Iron with Citrate of Sodium. Pyrophosphate of Iron in Ger. Pyrophosphorsauves Eiseaoxyd mit citroiiensaurem Natrium ; Fr. Pyro- phosphate de fer et citrate de sonde ; Sp. Pirofosfato de hierro y citrato de sodio. Thin, apple-green, transparent scales, of a mild, acidulous, and slightly saline taste, and permanent in dry air ; by exposure to the light the scales lose their transparency and become darker iu color. The salt is freely and completely soluble in twice its weight of water, and is also soluble in glycerin, but insoluble in alcohol. 360 MANUAL OF CHEMICAL ANALYSIS. The di]ute aqueous solution is of a bright yellow color, almost tasteless, and neutral in its action upon litmus; it is not precipi- tated by ammonia-water, but assumes with the latter a brown coloration, and when heated with solution of potassium hydrate, in slight excess, yields a red-brown precipitate of ferric hydrate ; if the iron be thus completely precipitated from the solution, fil- tered, the filtrate supersaturated with acetic acid, and a few drops of solution of argentic nitrate subsequently added, a white pre- cipitate will be produced (distinction from ferric phosphate). The solution affords a blue coloration with solution of potassium ferrocyanide, and, after acidulation with hydrochloric acid, a blue precipitate is produced; when mixed with hydrogen sulphide- water, no immediate change is produced, but the mixture soon assumes a black color. The dry salt should neither produce effervescence nor a dark coloration when strewn upon cold, concentrated sulphuric acid (absence of carbonates and of foreign organic substances). It contains an amount of ferric pyrophosphate corresponding to about 11.5 per cent, of metallic iron. FERRI STJBCARBONAS. FERRUM CARBONICUM. FERRUM SUB-CARBONICUM. Oarionate of Iron. Basic Ferrous Oarbonate. Ger. Kohlensanres Eisenoxydul ; Fr. Sous-carbonate de fer; Sp. Carbouato de liieiTo. A fine, amorphous, reddish-brown powder, without odor or taste, which, in consequence of the absorption of oxygen and the elimina- tion of carbonic acid gas, consists for the most part of ferric hydrate (page 356), with small and varying amounts of ferrous carbonate. When gently heated in a dry test-tabe, it emits aqueous vapors, which condense in the cooler parts of the tube, and which, when tested with blue litmus-paper, should not alter its color ; upon more strongly heating, it is completely converted into red ferric oxide, FcjOj. Carbonate of iron is insoluble in water, but readily and freely soluble, with slight effervescence, in warm, diluted hydrochloric acid, forming a yellow solution, a few drops of which, when added to water, impart to this the property of yielding a blue precipi- tate with both potassium ferrocyanide and ferricj^anide. The solution therefore affords, with reagents, the reactions of both ferrous and ferric salts. Exammation : Ferri Subcarbonas is distinguished from Perri Oxidum Hy- dratum by its readier solubility in hydrochloric acid, accompanied FERRUM. 361 by active effervescence, and affording a yellow solution, which, when largely diluted with water, yields a blue precipitate with both potassium ferrocyanide and ferricyanide. Alkaline sulphates may be detected by agitating a small portion of the powder, in a test-tube, with a little warm water, and sub- sequently filtering ; the filtrate should leave no considerable residue upon evaporation on platinum-foil, nor, when acidulated with a few drops of nitric acid, should it yield a white turbidity upon the addition of barium chloride. Metals. — A small portion of the powder is dissolved in dilute hydrochloric acid, the solution boiled with a few drops of nitric acid, and subsequently precipitated by ammonia-water in slight ex- cess, and filtered ; a blue coloration of the filtrate will reveal the presence of copper, and a white precipitate upon the addition of a few drops of ammonium sulphide will indicate the presence of zinc. FERRI SULPHAS. FERRUM SULFURICUM. Sulphate of Iron. Ferrous Sulphate. Ger. Schwefelsaures Eisenoxydul (Eisenvitriol) ; Fr. Sulfate de fer ; Sp. Snlfato de hierro. FeSO, + 7HP; 277.9. Transparent, pale bluish-green, monoclinic prisms (Fig. 118), of the specific gravity 1.889, or, when obtained by precipitation, by means of alcohol, a pale bluish-green, crystal- line powder ( Ferri Sulphas Prsecipitatus). Fig. 118. The crystals are slowly efflorescent in dry air, and by exposure to a moist atmosphere rapidly absorb oxygen, becoming coated with a layer of brownish-yellow, basic ferric sulphate ; they contain seven molecules (45.32 per cent.) of water of crystallization, six-sevenths of which they lose at a moderate heat, leaving a green- ish or grayish white powder {Ferri Sulphas Exsiccatus). At a red heat, the seventh mole- cule of water, and also the acid is expelled, leaving behind red, anhydrous ferric oxide {Caput Mortuurri). Ferrous sulphate is soluble in 1.8 parts of water at 15° C. (59° F.), in 0.3 part of boiHng water, and is slightly soluble in diluted, but insoluble in absolute, alcohol ; its aqueous solution has a greenish-blue color, an unpleasant styptic taste, and a slightly acid reaction ; it readily absorbs oxygen, acquiring a yel- 362 MANUAL OF CHEMICAL ANALYSIS. low color, aad becomes turbid by the formation of an insoluble basic ferric sulphate, while a neutral ferric sulphate remains in solution, with the undecomposed ferrous sulphate. The solution of ferrous sulphate, when largely diluted, gives a white precipi- tate with barium chloride, a blue one with potassium ferricyanide, and, when not yet oxidized, a white one with the ferrocyanide, but, after acidulation with hydrochloric acid, affords no precipi- tate upon saturation with hydrogen sulphide. Examination : Metals. — A small portion of the salt is dissolved in about twice its weight of water, the solution acidulated with a few drops of hydrochloric acid, and subsequently saturated with hydrogen sul- phide ; no precipitate, or but a white turbidity (sulphur) should be formed ; a dark turbidity would indicate copper, and perhaps other metals. The liquid is then filtered, evaporated in a porce- lain capsule until deprived of odor, subsequently boiled with a few drops of concentrated nitric acid, and finally completely pre- cipitated by ammonia- water, in considerable excess, and filtered. The filtrate is subsequently tested with ammonium sulphide ; an ensuing white turbidity would indicate zinc, a reddish-white one, manganese. Finally, the liquid, after having been filtered, if such reactions have occurred, is tested with ammonium phosphate ; a crystalline, white precipitate, occurring after some time, would indicate magnesium. Crude commercial sulphate of iron is generally considerably contaminated with metallic and earthy salts, and not fit for medici- nal use ; it frequently contains the sulphates of zinc, aluminium, and magnesium, and generally so much sulphate of copper as to deposit a metallic cupreous film upon a bright blade of an iron knife or spatula, when immersed for some hours in the aqueous solution, acidulated with a few drops of sulphuric acid, and may also contain arsenic. Estimation : The purity of ferrous sulphate, as based upon the estimation of the equivalent percentage amount of the therein contained metallic iron, may be readily and very accurately determined volumetrically. About one gram of air-dry and uneffloresced crystals of the salt is accurately weighed, and dissolved, in a beaker, in about 200 cubic centimeters of water, the solution subsequently acidulated with dilute sulphuric acid, and a stand- ard solution of potassium permanganate (page 89) allowed to flow into the liquid from a burette until, with constant stirring, the pink tint of the liquid remains for a time unchanged. The factor of the permanganate solution having been previously ascer- tained (see pages 89-90), and the number of cubic centimeters of the solution required for the complete oxidation of the ferrous to ferric salt, as above described, being known, a simple calculation will determine the amount of iron contained in the ferrous state FERRUM. 3t)3 in the salt, or the percentage amount of pure, crystallized ferrous sulphate. Another method consists in dissolving 4.167 grams of the salt in water acidulated with diluted sulphuric acid, and allowing a standard solution of potassium bichromate (page 91) to flow into the liquid, until a drop removed by means of a glass rod, and placed on a porcelain plate, no longer gives a blue color with solution of potassium ferricyanide ; the number of cubic cen- timeters of potassium bichromate solution thus required, when multiplied by 2, will represent the percentage amount of unoxi- dized, crystallized ferrous sulphate. Table of the percentage strength of solutions of crystaUized Ferrous Sulphate (FeS0^+7H^0) of different specific gravities {Gerlacti). Tempevalure 15° C. (59= F.). Specific Per cent, of Specific Per cent, of Specific Pel" cent, of gravity. F6SO4-I-7H2O. gravity. FeSOi+71l2Q. gravity. feSO,+7H20. 1.005 1 1.077 14 1.155 37 1-011 3 1.083 15 1.161 28 1.016 8 1.088 16 1.168 39 1.031 4 1.094 17 1.174 30 1.027 5 1.100 18 1.180 31 1.032 6 1.106 19 1.187 32 1.037 7 1.113 20 1.193 33 1.043 8 1.118 31 1.200 34 1.048 9 1.125 23 1.306 35 1.054 10 1.181 28 1.213 36 1.059 11 1.137 24 1.219 37 1.065 13 1.148 25 1.236 38 1.071 13 1.149 26 I 1.333 39 PERRI VALERIANAS. FEERUM VALERIANICUM. Valerianate of Iron. Ferric Valerianate. Ger. Baldriansaures Eisenoxyd ; Fr.Valerinate de fer; Sp.Valerianato de liierro. ]?e,(C3HA)6,Fe,(OH),; 931.6. A dark, brick-red, amorphous powder, permanent in dry air, and possessing the odor of valerianic acid. When gently heated, the salt loses its acid without fusing, but when rapidly heated in a porcelain capsule, it fuses, emits inflammable vapors, and, when incinerated, leaves behind ferric oxide, which should not color moistened turmeric-paper brown, nor dissolve in warm dilute acetic acid. Ferric valerianate is insoluble in water, and is only miscible therewith after having been previously moistened with a little 364 MANUAL OF CHEMICAL ANALYSIS. alcohol; boiling water decomposes it, extracting the valerianic acid, and affording a colorless filtrate, which reddens litmus-paper, but does not become turbid upon the addition of ammonia-water, either before or after saturation with hydrogen sulphide. Acids decompose ferric valerianate, forming soluble ferric salts, and setting free the valerianic acid. The so-called soluble valerianate of iron (Ferrum valerianicum solubile) occurs in thin, reddish scales, and consists of neutral or normal ferric valerianate, Fe2(0jHgO jj + lOH^O ; it is likewise insoluble in water, but is soluble in alcohol (distinction from ferric citrate aud tartrate), and exhibits the same behavior by the action of heat or boiling water as the above-described preparation, leav- ing, however, a much less considerable residue upon ignition. Examination : Admixtures of ferric tartrate or citrate, impregnated with oil of valerian or valerianic acid, may readily he recognized by their solubility in water and insolubility in strong alcohol ; the latter dissolving the oil of valerian, or valerianic acid, if such be pres- ent, which may be readily recognized by the odor, when a portion of the alcohol is evaporated upon the warm hand, while a residue will remain, responding to the tests of ferric citrate or tartrate, as described on pages 343 and 347, if such admixtures be present. FERRUM. Iron. Ger. Eisen ; Fr. Fer ; Sp. Hierro. Fe; 55.9. The source of the medicinal preparations of iron is the refined malleable wrought iron, of whicii the piano-forte wire is among the best commercial varieties. When iron filings or turnings are employed instead of wire, care has to be taken that they are not derived from crude cast or pig iron, that they are free from rust, and that they are not contaminated with copper or brass filings from the workshops. Cast or pig iron may be recognized by the evolution of gas of a noxious odor, and by a considerable black residue, when the filings or turnings ar6 dissolved, in a test-tube, in a mixture of equal parts of concentrated hydrochloric acid and water. An admixture of copper or brass filings may be recog- nized, with approximate certainty, by close inspection, with a raagnifying-glass, and by chemical tests, as hereafter described. In the preparation of solutions of iron, which are subsequently filtered, filings of cast iron are not exactly objectionable ; iron filings or turnings, however, which may contain, or are liable to contain, copper or brass filings, ought not to be employed for FERRIIM. 365 Fig. 119. medicinal preparations, since copper is dissolved by boiling with an excess of acid, notwithstanding the predominating presence of iron. Febeum Pulvekatum. — A fine, gray powder, of a dull, metal- lic appearance, and having the specific gravity 7.78 ; when strongly heated, with exposure to the air, it becomes oxidized to black ferroso-ferric oxide, and increasing in weight, if the powder em- ployed was pure and dry. Iron powder dissolves in a mixture of equal parts of hydrochloric acid and water, evolving impure hydrogen gas, of a faij;it odor, and leaving only a small insoluble black residue ; the filtered solution has a light-green color, and affords, when largely diluted with water, a deep-blue turbidity with potassium ferricyanide, and almost white precipitates with the alkaline hydrates and carbonates, which, however, rapidly oxidize, and become green, and ultimately brown. Examination : Sulphur, phosphorus, and arsenic, may be detected, in iron pow- der, filings, turnings, or wire, by the odor of the evolved gas, when dissolved in dilute hydrochloric or sulphuric acid, and by testing the gas thus evolved, either with a strip of paper moistened with a solution of plumbic acetate and placed over the mouth of the tube, or by loosely inserting a cork pro- vided with two strips of paper, one of which is moistened with a solution of plumbic acetate, and the other with a solution of argentic nitrat>' (Fig. 119) ; the blackening of both the lead and silver paper will indicate the presence of sul- phur, whilst a blackening of the silver paper alone may arise from the presence of either phosphorus or arsenic. The presence of sulphur may be confirmed by dissolving a portion of the iron in dilute nitric acid, and testing the solution with bari- um nitrate; a white precipitate of barium sulphate will be produced if sulphur were pre- sent. The presence of arsenic, if indicated by the above test, may also be confirmed by the application of Marsh's test, as described on pages 33 to 36. Phos2'>horus may also be detected by dissolv- ing a portion of the iron in warm dilute hydro- chloric acid, boiling the solution with a few drops of concentrated nitric acid, and filtering, whereby any carbonaceous or siliceous matter will remain prin- cipally undissolved, and may be further examined. The solution is then evaporated to remove the excess of acid, diluted with water, again filtered, if necessary, and incompletely precipitated 366 MANUAL OF CHEMICAL ANALYSIS. with sodium carbonate, avoiding an excess of the latter. The pre- cipitate of ferric hydrate thus obtained (containing the phos- phoric acid) is filtered off', dried, mixed with about four times its weight of exsiccated sodium carbonate, and ignited in a small porcelain crucible. The fused mass is then digested with hot water, the solution filtered, acidulated with hydrochloric acid, and magnesium mixture subsequently added ; the formation of a white crystalline precipitate will reveal the presence of phos- phorus, which, by the above treatment, is converted into phosphoric acid. Metallic Irnpurities. — A portion of the ircfti is dissolved in dilute hydrochloric acid, the solution boiled with a few drops of con- centrated nitric acid, and subsequently completely precipitated by ammonia-water, in excess, and filtered. The filtered solution should afford no turbidity upon the addition of ammonium sul- phide ; a blue coloration of the ammoniacal liquid will reveal the presence of copper, whilst a black precipitate with the last-named reagent may indicate copper, cobalt, or nickel, a flesh-colored pi'e- cipitate, manganese, and a white precipitate, zinc. Copper, zinc, and lead may also be detected, even when pre- sent in very small amount, hj dissolving a portion of the iron in an excess of warm concentrated hydrochloric acid, filtering, if necessary, and cautiously pouring upon the acid solution a satu- rated aqueous solution of hydrogen sulphide ; the presence of copper and lead will then be indicated by a brown zone be- low the line of contact of the two liquids, and as zinc, when present, is usually contained in the form of brass, the confirma- tion of a contamination with copper would of itself render the iron objectionable. Lead may be specially sought for, when de- sired, by adding to the solution of the iron in hydrochloric acid a few drops of sulphuric acid, then ammonia-water in slight excess, agitating the mixture, and subsequently adding four or five times its volume of dilute sulphuric acid, and again agitating well ; the presence of the smallest amount of lead will thus be indicated by an opalescence, dependent upon the separation of plumbic sulphate. Black oxide of iron (ferroso-ferric oxide) and organic matter, occurring as a contamination of powdered iron, may be detected in the first instance by its much less ready solubility in a mixture of bromine and water, and, in the second instance, by the ignition of the powder in a small glass tube. Estimation : The estimation of the purity of metallic iron, when free from oxide, may be readily accomplished volu metrically, by dissolving about 0.2 gram of the substance in a small flask, so arranged as to prevent the oxidation of the iron during solution (Fig. 120), in about 20 cubic centimeters of dilute sulphuric acid, pouring the solution, when cool, together with the rinsings of the flask, into FERRUM. 367 a beaker, diluting with water to about 100 Fia. 130. cubic centimeters, and finally allowing a standard decinormal solution of potassium permanganate (page 89) to flow into the liquid from a burette until, with constant stirring, the pink tint of the liquid remains for a time unchanged. The factor of the permanganate solution having been pre- viously ascertained (see pages 89-90), and the number of cubic centimeters of the solu- tion reqiiired to produce the above result, or to effect the complete oxidation of the iron, being known, a simple calculation will deter- mine the amount of pure metallic iron con- ' tained in the specimen under examination. Feeeum Eeductum (Ferrum Hydrogenio Eeductum). — ^Iron powder, obtained by the reduction of ferric oxide or hydroxide, or ferrous oxalate, by means of hydrogen, at a strong heat, forms a very fine, gray, loose, lustreless powder, which, when strongly heated, with exposure to the air, becomes oxidized to black ferroso- ferric oxide ; when touched with a lighted taper it ignites and burns, affording likewise, as a product of combustion, black ferroso ferric oxide. Eeduced iron is readily and wholly soluble in warm diluted hydrochloric acid, with the evolution of pure hydrogen gas, which is without action upon paper moistened with a solution of plumbic acetate or argentic nitrate, and forming a solution which has the same properties and deportment with reagents as that of powdered iron. If the solution takes place without a copious evolution of gas, and has, when filtered, a yellowish appearance instead of a light- green one, the powder was more or less oxidized, or even so much so as to consist almost wholly of a mix- ture of ferrous and ferric oxides. Examination of Ferrum Reductum : In addition to the above-detailed characters, re- duced iron should respond to the following test : "When digested for half an hour, at ordinary temperatures, with 25 times its weight of a solution of ferric chlo- ride, of the specific gravity 1.3, in a glass cylinder provided with a glass stopper (Pig. 121), the mixture being repeatedly shaken, the iron should become com- pletely dissolved ; any insoluble residue (which may consist of the oxides of iron or other foreign sub- stances) will, according to its amount, determine ap- proximately the value of the specimen under exami- nation. Another test, which may be applied to the determin- FiG. 121. ml 868 MANUAL OF CHEMICAL ANALYSIS. atioii of the presence of a definite minimum amount of metallic iron in the preparation, consists in digesting for two hours, in a glass vessel, 0.5 part of ferrum reductum with a solution of 1.13 parts of iodine and 1.2 parts of potassium iodide in 25 parts of water; if the solution, at the expiration of two hours, and with the em- ployment of the above proportions, contains no free iodine, but is clear and of a pale greenish color, the presence of at least 50 per cent, of metallic iron in the preparation is assured. The same test may readily be extended in its requirements by the applica- tion, in the emploj^ment of 0.5 part of ferrum reductum, of 0.226 additional part of iodine, with the proper proportionate amount of potassium iodide, for each 10 per cent, of metallic iron to be indicated. The United States Pharmacopoeia directs that if 1 gram of reduced iron be digested with 3.5 grams of iodine, 2.5 grams of potassium iodide, and 50 cubic centimeters of distilled water, for two hours, the resulting filtrate should have a green color, and should not be rendered blue by gelatinized starch (corresponding to the presence of at least 80 per cent, of metallic iron). The further testing of ferrrum reductum for sulphur, phos- phorus, arsenic, metallic impurities, or other admixtures which may be likely to occur, or are otherwise indicated, may be per- formed according to the methods described under ferrum pul- veratum, on pages 365-366. Estimation of Ferrum Reductum : I. A convenient and simple method for the estimation of the amount of pure metallic iron in ferrum reductum, and which pro- vides for its admixture with ferroso-ferric oxide, FcjO^, but not for the other oxides or their combinations, is as follows: About 0.2 to 0.3 gram of ferrum reductum, accurately weighed, together with a little pure zinc (about 1 gram), are dissolved in about 20 cubic centimeters of dilute sulphuric acid, in a small flask, so arranged as to prevent the oxidation of the iron during solution (Fig. 120. page 367). The solution, after being allowed to cool, is transferred to a beaker, and, together with the rinsings of the flask, diluted to the measure of 100 cubic centimeters ; a standard decinormal solution of potassium permanganate (page 89) is then allowed to flow into the liquid from a burette until, with con- stant stirring, the pink tint of the liquid remains for a time unchanged. The factor of the permanganate solution having been previously ascertained (pages 89-90), the number of cubic centimeters of the solution employed will indicate, by simple cal- culation, the total amount of iron present, from which the per- centage amount of the latter may be determined. In consideration, however, that the entire amount of iron determined was not originally present as metallic iron, but associated in part with fer- roso-ferric oxide, FCgO^, which becomes reduced to ferrous salt through the agency of the nascent hydrogen, the number 72.4 FERRUM. 369 shouW be subtracted from the total percentage of iron, and the remainder divided by the decimal 0.276, which will yield, as the quotient, the percentage of pure metallic iron contained in the specimen under examination. II. Another method, which is based upon the determination of the amount of metallic copper precipitated by a definite amount of reduced iron from a solution of cupric sulphate of known strength, and which requires no correction, as in the above method, for the presence of ferrous or ferric oxides, is as follows : 1 gram of the reduced iron is digested for one hour with a solution of 5 grams of pure cupric sulphate in 25 grams of water, acidulated with 2 drops of dilute sulphuric acid ; the solution is then filtered into a previously weighed flask, the filter washed with sufficient distilled water to obtain 50 grams of filtrate, 1 gram of pure pow- dered iron (the percentage of carbon contained in it should be previously determined) added, and the whole digested until the copper contained in the solution is completely precipitated in a metallic state ; 5 grams of pure concentrated sulphuric acid are subsequently added, and the mixture gently heated until the iron is completely dissolved, when the precipitated copper will alone remain, contaminated with a little carbon. The copper is re- peatedly washed, by decantation, first with water, afterwards with alcohol, and finally with absolute alcohol and ether ; the flask is then quickly dried, by the aid of a gentle heat, weighed, and from the weight of the copper the carbon of the powdered iron (about 0.01 gram) subtracted. Since the difference between the weight of this precipitated copper and the total weight of the metallic copper (1.271 gram) contained in the 5 grams of crystallized sul- phate equals the quantity of copper which was precipitated by the metallic iron contained in 1 gram of the reduced iron, the percentage of the unoxidized metal is readily determined from the ascertained weight, and the relation between the atomic weights of copper and iron. The number of centigrams of iron, calculated from the copper which was precipitated in the first part of the process, indicates directly the percentage of metallic iron contained in the reduced iron. 24 370 MANUAL OF CHEMICAL ANALYSIS. GLYCERINUM. GLYCERINA. Glycerin. Triatomic Propenyl Alcohol. Ger. Glycerin ; Fr. Glycerine ; Sp. Glicerina. CH,-OH C,H303 = C3HXOH)3, or CH-OH ; 92. CH,-OH A colorless and odorless, tliick, viscid, neutral liquid, of an intensely sweet taste ; when anhydrous, its spec. grav. is 1.267 at 15° C. (59° F.) ; that of commercial glycerin, containing from 5 to 10 per cent, of water, is from 1.25 to 1.237. "When perfectly anhydrous, and exposed to a temperature of 0° C. (32° F.), it is capable, under certain conditions, of assuming the crystalline form; the crystals have- a specific gravity of 1.262, belong to the rhombic system, and attract moisture with great avidity, becom- ing finally liquefied at 10° C. (50° F.), while the melting-point ot the perfectly anhydrous crystals is apparently above 23° C. (73.4° F.). Glycerin is not volatile at common temperatures, but, when ex- posed in thin layers, is perceptibly volatilized at a temperature of 100° C. (212° F.), and distils unchanged in vacuo, or with aqueous vapor, under pressure ; it boils, under ordinary atmo- spheric pressure, at 290" C. (554° F.), undergoing partial decom- position, and emitting white, irritating, inflammable vapors, which, when ignited, burn with a pale blue flame, leaving no residue. Glycerin is miscible, in all proportions, with water, solutions of the alkaline hydrates, alcohol, and ether diluted with alcohol, but not with pure ether, chloroform, carbou bisulphide, or benzol ; it mixes with concentrated sulphuric acid, with the formation oi sul- 'pho-gjyceric acid, CjHjx' f)-^0 -OTT ' ^^^^^ affords soluble salts with the oxides of barium, calcium, and lead ; with concentrated nitric and hydrochloric acids, it suffers decomposition, becoming either oxidized, or forming therewith compound ethers, as in the case of the powerfully explosive, so-called nitroglycerin, C3Hj(0-N0j),. When heated with dehydrating substances (con- centrated sulphuric or phosphoric acid, or acid potassium sul- phate), glycerin is converted into the strongly irritating substance, acrolein, CjHjO, Glycerin possesses extensive powers as a solvent ; it dissolves most substances which are soluble in water, although usually in a less degree, but, in some instances, is a better solvent, as, for instance, in the ease of alum, borax, and carbolic acid ; and dis- solves reaxlilj manjr, substances which are insoluble or very spar- GLVCERINUM. 371 ingly soluble in water, such as sulphur and mercuric iodides, bro- mine, iodine, quinine, morphine, and other alkaloids, as also many- metallic oxides, and prevents the precipitation of the latter from their solutions by the alkaline hydrates. It does not mix with fatty oils, and dissolves essential oils only to a limited extent. Examination : A fatty or empyreximatic odor of glycerin is best recognized by gently warming a little of the sample on a watch-glass, or in a small porcelain capsule, or by the addition of a little dilute sul- phuric acid. Cane-sugar, glucose, and mucilages are indicated by a more or less brown coloration of the glycerin, when mixed with twice its volume of concentrated sulphuric acid, or Avhen mixed and heated with a strong solution of potassium hydrate; they will also be indicated by a considerable carbonaceous residue, when a little of the glycerin is heated to boiling, in a small platinum capsule, and the vapors ignited. Glucose may be detected by the occurrence of a brick-red pre- cipitate, when a little of the glycerin, diluted with an equal volume of water, is heated with a few drops of an alkaline solu- tion of cupric tartrate. Cane-sugar is detected by the same reaction, when the glycerin is boiled for a few minutes with an equal volume of dilute solu- tion of tartaric acid, and the hot mixture tested with Fehling's cupric solution. Mucilages of gum, dextrin, or glue are indicated by the forma- tion of a white turbidity, gelatinous or floceulent, when one volume of the glycerin is mixed with four volumes of alcohol. Metallic salts are detected by agitating one volume of the glycerin with three volumes of a saturated aqueous solution of hydrogen sulphide ; any impairment of the colorlessness or transparency of the mixture would indicate metallic impurities ; they may be dis- tinguished, as to the group of metals to which they belong, by divid- ing the liquid into two portions, and adding to the one a little hydrochloric acid, and to the other ammonia-water. Copper, lead, and tin will be indicated by the first test; iron, zinc, and alu- minium, by the second. If a precipitate appears in either case, and the nature of the impurity has to be ascertained, the test must be repeated on a larger scale, and the metallic impurity deter- mined by the methods described on pages 51 to 59. Calcium salts may be detected in the diluted glycerin, by a white turbidity when tested with ammonium oxalate. Am,monium salts, occasioned by the neutralizat on of an origi- nally slightly ac'dulous glycerin with ammonia- water, may be detected by the odor of ammonia when the glycerin is heated, in a test-tube, with an equal volume of a concentrated solution of po- tassium hydrate, and by the appearance of white fumes, when a 372 MANUAL OF CHEMICAL ANALYSIS. glass rod, moistened with acetic acid, is held over the mouth of the tube. Acids and their Salts. — When diluted with twice its volume of water, the solution must leave litmus-paper unchanged ; it is then examined in four separate portions: for hydrochloric acid and chlorides, by acidulating with nitric acid, and testing with argentic nitrate ; for sulphuric acid and sulphates, by testing the second portion, also acidulated with nitric acid, with barium nitrate ; for oxalic acid, by testing the third portion, acidulated with acetic acid, with calcium acetate or chloride ; and for nitric acid and nitrates, by adding to the fourth portion a little acetic acid and one drop of neutral indigo solution, and then warming the mix- ture by dipping the test-tube into hot water ; a decoloration of the bluish or bluish-green tint of the liquid will indicate free nitric acid ; when the color remains unaltered, a few drops of con- centrated sulphuric acid are added to the mixture while still warm ; if decoloration takes place now (and the glycerin is free from chlorates), nitrates are indicated. Another very sensitive test for nitric acid and nitrates, com- bining the test for chlorine, is to mix, in a test-tube, a little muci- lage of starch with a few drops of solution of potassium iodide (free from iodate), and a few drops of dilute sulphuric acid, and then to add a small portion of glycerin ; when mixed together with a glass rod, the liquid must remain colorless ; a blue color would indicate chlorine ; when the mixture remains colorless, a thin rod of bright zinc is immersed in the centre of the fluid, with care not to agitate the test-tube ; if traces of nitric acid or nitrates be present, a bluish coloration, issuing from the zinc, will appear. Formic acid may be detected by the formation of a black de- posit, when a mixture of the glycerin with an equal volume of diluted ammonia-water and a little solution of argentic nitrate is allowed to stand in a corked test-tube, protected from the light, for twenty-four hours. Butyric acid, and analogous fatty acids, will be indicated by an acid reaction of the glycerin, and may be extracted therefrom by agitation with ether, or may be recognized by the odor of ethyl butyrate (similar to that of artificial essence of pine-apple), when a mixture of two volumes of glycerin with one volume of a mix- ture of equal parts, by volume, of strong alcohol and concentrated sulphuric acid, is gently warmed by dipping the flask or test-tube into boiling water. Estimation of Crlycerin in Wine, Beer, etc. : The separation and approximate estimation of glycerin in wine, beer, and other similar liquids, may be accomplished by treating the residue obtained by the evaporation of a measured portion of the liquid, in a small glass flask, with a warm mixture of 1 part of ether and 3 parts of alcohol, which extracts the glycerin, together with some succinic acid and sugar. The liquid is then HYDRARGYRUM. 373 filtered, if necessary, the filtrate neutralized with milk of lime, the alcohol removed by distillation or evaporation, and the dry residue again extracted with a warm mixture of ether and alcohol, which, after filtration, is allowed to evaporate, upon the water- bath, at the lowest possible temperature. The residue of glycerin thus obtained, after being allowed to stand for tvyo days over sulphuric acid, is finally weighed. The glycerin may be subse- quently tested for its identity, if desired, by rendering it slightly alkaline with a dilute solution of sodium hydrate, and moisten- ing therevyith a fused bead of borax, contained on the looped end of a platinum-wire : if the borax bead be subsequently held in a non-luminous flame, a deep green tint will be imparted to the latter. Table of the qua.nt.ity hy weight of Water contained in lOO^aris hy weight of Glycerin of different specific gravities. Temperature 17.50 C. (63. 50 F.). SpeciQc Per cent. Specific Per ceot. Specific Per cent. Specific Per cent. gravity. of water. gravity. of wiiter. gravity. of water. gravity. of water. 1.267 1.224 13 1.185 26 1.147 39 1.264 1 1.221 14 1.183 27 1.145 40 1.260 2 1.218 l-'5 1.179 28 1.142 41 1.257 3 1.215 16 1.176 29 1.139 42 1.254 4 1.212 17 i 1.173 30 1.136 43 1.250 5 1.209 18 I.ITO 31 1.134 44 1.247 6 ! 1.206 19 1.167 33 1.131 45 1.244 7 1.203 20 1.164 33 1.138 46 1.240 8 1.200 21 1.161 34 1.136 47 1.237 9 1.197 23 1.159 35 1.123 48 1.234 10 . 1.194 23 1.156 36 1.130 49 1.231 11 1.191 24 1.153 37 1.118 50 1.228 12 1 1.188 25 1.150 38 HYDRARGYRI CHLORIDUM CORROSIVUM. HYDRA.RGYRI PERCHLORIDUM. HYnRARGYRUM BICHLORA.- TUM. HYDRARGYRUM CORROSIVUM SUBLIMATUM. Corrosim Sublimate. Corrosive chloride, Perchloride, or Bichloride of Mer- cury. Mercuric Chloride. Ger. Quecksilberclilorid ; Fr. Biolilorui-e de mercure ; Sp. Bicloi'uro de mercurio. HgCl,; 270.5. Colorless, translucent, heavy, crystalline masses, when obtained by sublimation, or small, well-developed rhombic prisms (Fig. 122), when obtained by crystallization from its solutions, and having 374 MANUAL OF CHEMICAL ANALYSIS. a speo'fic gravity of 5.403 ; they are permanent in the air, give a dull, white streak when scratched with a knife, fuse at 265° C. (509° F.), and volatilize wholly at 295° Fig. 132. C. (563° F.), forming dense, white vapors, which, on cooling, solidify in small, shin- ing- needles. Mercuric chloride is soluble in water, requiring, at 10° C. (50° F.), 15.22 parts, at 20° C. (68° ¥.), 13.53 parts, at 50° G. (122° F.j, 8.81 parts, at 80° C. (176° F.). 4.11 parts, and at 100° C. (212° F.), 1.85 parts of water for solution ; it is less soluble in glj^cerin, 100 parts of which dissolve about 7 parts of the salt, but is freelv soluble in alcohol and ether, re- quiring, at 17° C. (62.6° F.), 2.5 parts of alcohol, spec. grav. 0.830, and 4 parts of ether for solution, and is abstracted, for the most part, by the latter, when agitated with its aqueous solution. The aqueous solu- tion reddens blue litmus-paper, and has an acrid, metallic, styptic taste ; upon the evaporation of the solution, by the aid of heat, a portion of the salt becomes volatilized with the aqueous vapors. In the aqueous solution of mercuric chloride, the fixed alkaline and earthy hydrates and alkaline carbonates produce, when added in small quantity, a reddish-brown precipitate; when added in e.Nicess, a yellow one ; ammonia-water gives a white one ; argentic nitrate, a curdy white one ; iodides, when added in small quan- tity, a yellowish, and in larger quantity, a vermilion-red one, sol- uble in an excess of the precipitant ; stannous chloride, when added in small quantity, a white, and wheu added in excess, a gray pre- cipitate. When an aqueous solution of hydrogen sulphide is gradually added to a solution of mercuric chloride, the precipita- tion takes place according to the proportions of the reagent and the chloride, in progressive variation of color from white to yel- low, orange, reddish brown, and black ; an excess of the reagent produces at once a complete black precipitation. When the aque- ous solution of mercuric chloride is rubbed upon bright copper, it coats the latter with a brilliant metallic film. It forms white, insoluble or sparingly soluble compounds with many organic substances, as albumen, fibrin, gluten, etc. ; and by exposure to the light, particularly when in contact with organic substances and when possessing an alkaline reaction, it becomes gradually reduced to merourous chloride (calomel), while its decomposition is prevented or materially retarded by the presence of hydrochloric acid or alkaline chlorides. Mercuric chloride is soluble, without decomposition, in nitric, hydrochloric, and sulphuric acids ; and crystallizes from the solu- tions on cooling, if they were saturated while hot. With the alka- HYDRARGYRUM. 375 Pig. 133. line cMorides it combines to form doable salts, which are mostly well crystallizable, and more readily soluble in water than mer- curic chloride. Examination : The purity of mercuric chloride will, in most instances, be suf- ficiently established by its conformity with the above described physical properties, by its complete volatil'zation upon strongly heating, and its relation to solvents, as also by the several chemical tests. Arseriic may be readily detected by digesting the powdered mercuric chloride with ammonia-water, or precipitating its aqueous solution by the latter, subse- quently filtering, and, after ac'.dulating with dilute sulphuric acid, testing in Marsh's apparatus, page 34; or, after the concentration of the solution by evapora- tion, the several tests for arsenious acid may be ap- plied, as described under the latter, on pages 127 to 130. The presence of arsenic may also be quickly deter- mined by dissolving a small portion of the salt in hot water, and adding to the solution, contained in a long test-tube, an excess of a concentrated solu- tion of sodium hydrate, and a few fragments of alumi- nium wire or pure zinc; a cap of bibulous paper, moistened with a drop of solution of argentic nitrate, is then placed over the orifice of the tube (F.g. 123), and the mixture gently heated ; an ensuing dark coloration of the paper or the production of a dark metallic stain will reveal the presence of arsenic. Mercurous chloride (calomel) and other insoluble im- purities or admixtures, will be detected by their re- maining undissolved, when the mercuric chloride is digested or gently warmed with about twenty times its weight of water. \ I HYDRARGYRI CHLORIDXJM MITE. HYDRA.RGYRI SUBCHLOHIDUM. HYDRARGYRUM CHLORA.TUM. MERCURIUS DULCIS. Calomel. Mild cUloride, Siib- or Proto-chloride of Mercury. Mercurous Ohloride. Ger. QueoksilberchlorCir ; Pr. Protochlorure de mercure ; 8p. Protocloruro de raercurio. HgCl; 235.1. iMercurous chloride varies in the minuteness of its particles, and accordingly in its appearance and in the energy of its physio- logical action. 37t5 MANUAL OF CHEMICAL ANALYSIS. When obtained by svMimation, it forms ponderous, yellowish - white masses or cakes, of a fibrous, crystalline fracture, yielding a lemon-yellow streak when scratched with a knife, and having a specific gravity of 7.176. When reduced to a fine powder by trituration and levigation, it has a dull- white appearance with a yellowish tint; it becomes slightly yellowish when triturated with strong pressure in a porcelain mortar, and consists, when seen under the microscope, of comparatively large, transparent, crystalline fragments (Fig. 124). FtG. 124. Fig. 125. Fig. 126. 250 diam. 2S0 diam. Prepared by sublimation and by condensation of the vapor by a current of air or steam, mercurous chloride (Hydrargyri Chlo- ridura Mite vapore paratum) forms a perfectly white and less ponderous powder (specific gravity 6.56), consisting of smaller laminar particles, when seen under the microscope (Fig. 125). Prepared by jorecjpitaiwi, mercurous chloride forms a fine snow-white powder, consisting of minute, amorphous* particles (Fig. 126), which are not transparent, and are devoid of odor or taste. With regard to therapeutical action, mercurous chloride, ob- tained by sublimation and subsequent trituration and levigation. and consisting of the largest particles, has the mildest effect ; next to this comes the calomel obtained by sublimation and con- densation by air or steam ;f that obtained by precipitation, and having the minutest division of its particles, has the more power- ful physiological action. Mercurous chloride, when heated in a dry test-tube, is slowly but completely volatilized with a faint noise and without fusion. It is insoluble in the common solvents, but soluble to some extent in saliva, in the pancreatic juice, in albumen, and animal secre- * When obtained by precipitating a solution of mercuric chloride witli sul- phurous-acid gas, the resulting mercurous chloride is of a crystalline structure. f No other Idnds of taercurous chloride can as yet be considered officinal, and no others should be dispensed for internal use, unless ordered or pre- scribed, than " Calomel ma humida paratum,^^ or " Calomel precipitatione paratum." HYDRARGYRUM. 377 tions. When agitated with hot water, with alcohol, or with dilute acetic, hydrochloric, or nitric acids, it is not acted upon by any of them. "When boiled for some time with water, it suffers slow decomposition into metallic mercury and mercuric chloride ; the decomposition being greater in extent when, instead of pure water, solutions of the alkaline chlorides are employed. The fixed alkaline hydrates and carbonates, and the hydrates of the alkaline earths, reduce mercurous chloride to black oxide ; the same conversion of mercurous chloride to oxide is also occa- sioned by its exposure to light, and by contact with many organic substances. Concentrated boiling hydrochloric and sulphuric acids decompose the salt; the former producing metallic mercury and mercuric chloride, the latter mercuric sulphate and chloride. Warm concentrated nitric acid also dissolves it gradually, with the evolution of nitric oxide vapors, forming a solution of mer- curic chloride and nitrate, which solution blackens bright copper when dropped upon it, and coats it brilliantly when rubbed upon it. Mercurous chloride is also soluble in chlorine-water without acquiring a transient or permanent yellow color (distinction from mercurous bromide). Examination ; When heated in a narrow test-tube, mercurous chloride must completely sublime, without previous fusion and without emitting ammoniacal odors or yellow nitrous vapors. Mercuric chloride may be most quickly detected by placing a little of the mercurous chloride, previously moistened with water to the consistence of a thin paste, upon a piece of bright iron, and allowing the mixture to repose thereon for one or two minutes ; if mercuric chloride is present, it will become instantly decom- posed, and there will appear upon the iron, after the removal of the mixture by rinsing with a little water, a deep, dull-black stain ;* it may also be detected by triturating some of the calomel with diluted alcohol, agitating the mixture in a test-tube, and subsequently filtering through a moist double filter ; the filtrate must impart no stain to bright copper, nor yield any reaction with hydrogen sulphide or with argentic nitrate. Ammoniated mercury (white precipitate) may be detected by the development of 'the odor of ammonia, when the mercurous chloride is heated, in a test-tube, with a concentrated solution of potassium or sodium h3'drate ; or, when the mercurous chloride of the preceding test, remaining upon the filter, is rinsed with diluted acetic acid through the broken filter into a test-tube, and the mixture agitated for a few minutes and filtered. The filtrate is then tested in separate portions with hydrogen sulphide and * Pure mercurous chloride will produce under the same circumstances, by- prolonged contact witli the iron, a slight grayish film upon the latter, which, however, cannot be mistaken for the characteristic black stain produced by the mercuric salt. 378 MANUAL OF CHEMICAL ANALYSIS. argentic nitrate; a black turbidity in the first instance, and a white one in the second, would indicate ammoniated mercury. Non-volatile impurities, such as the sulphates or carbonates of the alkaline earths, may readily be detected when a little of the mercurous chloride is completely volatilized by strongly heating in a test-tube; any residue thus obtained may be further exam- ined for its identification, if desired, according to the systematic methods of analysis, as described on pages 51 to 61. HYDRARGYRI CYANIDUM. HYDRARGYRUM CYANATUM. Cyanide of Mercury. Mercuric Oyanide. Ger. Quecksilbercyanid ; Fr. Cyanure de mercure ; Sp. Cianuro de mercurio. Hg(CN),; 251.7. Colorless, anhydrous, needle-shaped crystals, or lustrous quad- ratic prisms (Fig. 127), transparent when freshly prepared, but soon assuming a white and opaque appearance ; Fig. 137. when perfectly dry, and carefully heated in a dry tube, they become decomposed into me- tallic mercury and a colorless inflammable gas (cyanogen), which burns, when ignited, with a purple flame ; when quickly heated, a black residue of paracyanogen, intermingled with globules of mercury, is left behind, which, however, upon more strongly heating, is com- pletely dissipated ; when the salt is humid, . traces of hydrocyanic acid, of carbonic acid, ^•^^ss^^^^ ^^^ °^ ammonia, are also formed and evolved. ^^^^^^ Mercuric cyanide is soluble in 12.8 parts of water and in 14.5 parts of alcohol at 15° 0.(59° F.), in 3 parts of boiling water and in 6 parts of boiling alcohol, but almost insoluble in absolute alcohol and ether ; its aqueous solu- tion possesses a disagreeable metallic taste, and is decomposed by hydrochloric acid and by hydrogen sulphide, with the liberation of hydrocyanic acid and the formation of mercuric chloride or sulphide, but is not decomposed by dilute sulphuric or nitric acid, and is not precipitated by the alkaline hydrates and carbonates, by argentic nitrate, or by albumen; stannous chlo- ride, containing free hydrochloric acid, precipitates metallic mer- cury with the evolution of hydrocyanic acid. The solution of mercuric cyanide aftbrds no mercuric stain upon bright metallic copper, unless the latter be previously moistened with hydro- chloric acid; it readily dissolves mercuric oxide, and, on evapo- HYDRARGYRUM. 379 rating the alkaline solution thus obtained, small needle-shaped crystals of an oxy-cyanide, Hg30(0N')j, are formed. Examination : Mercuric oxy-cyanide is indicated by an alkaline reaction of the solution upon turmeric-paper. Mercuric chloride and other soluble mercuric salts may be de- tected in the solution, by the occurrence of a transient turbidity upon the gradual addition of single drops of solution of potassium iodide, or by the production of a precipitate upon the addition of the alkaline hydrates or carbonates. HTDRARGYRI lODIDITM RUBRUM. HYDRARGYRUM BIIODATUM. Sed Iodide of Mercury. Biniodlde of Mercury. Mercuric Iodide. Ger. Quecksilberjodid ; Fr. Bi-iodure de mercure ; Sp. Bi-ioduro de mercurio. Hgl,; 452.9. A heavy, amorphous, scarlet-red powder, or small, brilliant, octahedral crystals, belonging to the quadratic system, and hav- ing a specific gravity of 6.3. When gently heated in a dry tube Fig. 128. 380 MANUAL OF CHEMICAL ANALYSIS. (Fig. 128) to about 150° C. (302° F.), mercuric iodide first becomes of a pure yellow color, then, wheii near the melting-point, deep orange, and finally melts at 253-254° 0. (487.4-489.2° F.) to a blood-red liquid ; at this temperature the volatilization of the iodide begins, when it sublimes undecomposed in the form of yel- low rhombic scales, which pass into the red modification of octa- hedral crystals, slowly on cooling, and at once by concussion. If the salt be heated with solution of sodium hydrate, and a little sugar of milk added, a precipitate of metallic mercury is produced ; and if heated with sulphuric acid and a little manga- nese dioxide, the vapor of iodine is evolved. Mercuric iodide is nearly insoluble in cold, and only very spar- ingly soluble in boiling, water; it is soluble in 130 parts of cold, and 15 parts of boiling, alcohol, less soluble in ether, and very little in glycerin and in oils. Concentrated acids, and the solu- tions of the alkaline hydrates, decompose it ; it is freely soluble in aqueous solutions of potassium and sodium hydrates, of potas- sium iodide and cyanide, of mercuric chloride, and of sodium chlo- ride and sodium hyposulphite ; the latter solution deposits, upon gently heating, if the solvent is not in excess, red mercuric sul- phide, while, upon boiling, black mercuric sulphide, mixed with mercurous iodide and metallic mercury, is separated. All its solutions form a black precipitate upon saturation with hydrogen sulphide, either at oncp, or upon the addition of an acid. Mercuric iodide is partly decomposed when shaken with chlo- rine-water ; the obtained filtrate, when rubbed upon bright copper, coats it with a brilliant metallic film, and, when shaken with a little chloroform, imparts to the latter a purple color. Examination : Mercuric iodide, when heated to a temperature above 150° C. (302° F.), should assume a uniform yellow color, and, at a higher temperature, should become completely volatilized ; with hot alcohol it must afford a complete and colorless solution, without acid reaction, from which, upon cooling, the larger portion of the iodide is separated in a crystalline form ; the cold filtered solu- tion, upon the subsequent addition of ammonia-water, should not assume more than a brown coloration, and afford no precipitate. When digested with cold or hot water, or with acetic acid of the spec. grav. 1.040, no appreciable amount should be dissolved. Soluble iodides or chlorides may be detected in the mercuric iodide by digesting a little, of the salt with water, filtering, and testing the filtrate with argentic nitrate; a white or yellowish- white turbidity or precipitate would indicate the presence of such admixtures. Mercuric sulphide, red oxide of lead, or other fraudulent admix- tures, will remain undissolved upon digesting the powder, either in solution of potassium iodide, or in twenty to twenty-five parts of boiling alcohol. If a residue is left, it is washed with water, and subsequently treated with warm nitric acid, and filtered ; the HYDRARGYRUM. • 381 filtrate is slightly diluted, and tested with a few drops of diluted sulphuric acid ; an ensuing Avhite precipitate indicates lead. If a red residue remains, insoluble in nitric acid, it is tested by heat- ing it upon platinum-foil to redness; if it is wholly volatile, mer- curic sulphide is recognized, and, if a residue remains, fixed ad- mixtures are indicated. HYDRARGYRI lODIDUM VIRIDE. HYDRARGYRUM lODATUM. Oreen Iodide of Mercury. Protoiodide of Mercury. Mercurous Iodide. Gcr. Quecksilberjodiir; Fr. Profoiodure de mercure ; Sp. Protoioduro de mercurio. Hgl; 326.3. A heavy powder, of a dull-green or greenish-yellow color, which sufi'ers gradual decomposition and becomes brownish on exposure to light, heat, and air. When heated in a dry tube (Fig. 128, page 379), it begins, at 70° C. (158" F.), to assume a red color, which increases in intensity until, at 200° C. (392° F.), it acquires a deep garnet-red color; at 220° C. (428° F.) it softens, and melts at 290° C. (554° F.), but begins to sublime, at 190° C. (374° F.), and by slow sublimation forms small, transparent, yellow crystals of the quadratic system, having the specific gravity of 7.6 ; when quicklj' and strongly heated, it suffers a partial decomposition into metallic mercury and mercuric iodide, which do not again combine upon cooling. Mercurous iodide is not quite insoluble in water, but wholly insoluble in alcohol and in ether ; it is decomposed by concen- trated acids, by the alkaline hydrates, and also by boiling solu- tions of the alkaline chlorides, bromides, and iodides, being converted by the latter into mercuric iodide and metallic mer- cury. When mercurous iodide is agitated in a little water to which a few drops of ammonium sulphide have been added, the liquid filtered, and the filtrate, after acidulating with hydro- chloric acid, mixed with a few drops of a solution of ferric chloride and then agitated with a little chloroform, the latter will acquire a purplish or violet-red color, due to the presence of free iodine, which will appear still more distinct "upon the subsequent addition of a little water. Examination : Mercuric iodide may be detected when 1 gram of the powder is agitated and digested with about 10 cubic centimeters of alcohol, subsequently filtered, and the filtrate dropped into water, when not more than a slight transient opalescence should be produced ; and when 5 cubic centimeters of the filtrate are evaporated from a white porcelain surface, not more than a faint red stain should 382 MANUAL OF CHEMICAL ANALYSIS. remain behind ; neither should the filtrate afford more than a very slight coloration or turbidity upon sat\Tration with hydrogen sulphide, otherwise the presence of an undue amount of biniodide or mercuric salt is indicated. Fixed impurities will remain behind upon the complete vola- tilization of the mercurous iodide in a dry tube ; such would be YQTj likely to originate from either the mercury or the iodine, and, if required, their nature may be determined by the methods described on pages 388-390 and 395-396. HYDRARGYRI OXIDUM FLAVUM. HYDRAKGYRUM OXYDATUM VIA HUMIDA PARATUM. Telloii Oxide of Mercury. Precipitated Mercuric Oxide. Ger. Gelbes Quecksilberoxyd ; Fr. Oxyde de mercure jaune ; Sp. Prot6xido de mercurio. HgO; 215.7. A heavy, orange-yellow powder, without crystalline structure when seen under the microscope, permanent in the air, and having a specific gravity of 11.3. It becomes darker on expo- sure to the light, and assumes a red color on being heated ; at a higher temperature it is decomposed with the evolution of oxygen and the separation of mercury, and is finally entirely volatilized. It is more readily acted upon by reagents than the coarser red oxide ; the latter remains unchanged when agitated with a warm solution of oxalic acid, while the yellow oxide combines with the oxalic acid, forming white mercuric oxalate ; when agitated with a hot alcoholic solution of mercuric chloride, the yellow oxide becomes at once black, in consequence of the formation of mercuric oxychloride (HgClj.2HgO), while the red oxide remains unchanged for some time. The chemical reactions of the precipitated yellow mercuric oxide, and its deportment with reagents, correspond with those of the red oxide. HYDRARGYRI OXIDUM RUBRUM. HYDRARGYRUM OXYDATUM. Bed Oxide of Mercury. Med Precipitate. Mercuric Oxide. Ger. Rothes Quecksilberoxyd; Fr. Oxyde de mercure rouge ; Sp. Deut<5xido de mercurio. HgO; 215.7. Heavy, coherent masses, consisting of bright, brick-red, crys- talline scales, which, when finely pulverized, form a dull orange- HYDRARGYRUM. 383 red powder, of a specific gravity of 11.136 ; when heated in a dry tube, red mercuric oxide first changes to a darli cinnabar-red color, and afterwards assumes a black tint, but regains its original color on coohng; at temperatures above 400° C. (752° F.) it is completely resolved into its constituents, and is entirely vola- tilized below a red heat, while at a much lower temperature it suffers a partial dissociation. Mercuric oxide is slightly soluble in water, so that, when agi- tated with boiling water, the filtrate possesses a decided metallic taste, an alkaline reaction upon litmus, and afibrds with ammo- nium sulphide a slight brown coloration ; it is insoluble in pure glycerin, in alcohol, ether, and chloroform, somewhat soluble in saliva and in albuminous animal secretions, and entirely soluble in strong and in somewhat diluted acids. The fixed alkaline and earthy hydrates and alkaline carbonates produce in solutions of mercuric oxide and its salts, when added in small quantity, a red- dish-brown, when added in excess, a yellow precipitate ; ammonia- water, a white one ; iodides (provided that the solution does not contain a large excess of acid), when added in small quantit}', a yellowish, and in a larger quantity, a vermiHon-red one, soluble in an excess of the precipitant; stannous chloride, when added in small quantity, gives a white, and, in excess, a gray precipitate. When water saturated with hydrogen sulphide is gradually added to the solution, or when the latter is slowly saturated with the gas, a precipitate is formed which appears, according to the pro- FiG. 129. portion of the reagent, successively white, yellow, orange, reddish - brown, and finally, with an excess of the precipitant, black. 384 MANUAL OF CHEMICAL ANALYSIS. Examination : Mercuric nitrate is indicated by tlie disengagement of red nitrous vapors, when the oxide is heated in a dry test-tube. As a con- firmatory test, and one permitting the detection of much smallei quantities of nitrate, about 0.5 gram of the oxide is mixed with 10 drops of water, in a test-tube, then three times its volume of concentrated sulphuric acid added, and to the mixture, after being well agitated and subsequently allowed to repose, a saturated solution of ferrous sulphate is carefully added so as to form two layers (Fig. 129) ; the occurrence of a dark-brown zone at the line of junction of the two liquids will confirm the presence of nitrate. Admixtures. — A small portion of the oxide is gently heated with about ten times its weight of dilute nitric acid, when com- plete solution should take place ; if the oxide be very old, a slight residue of reduced mercury might remain, which, when separated and heated in a porcelain capsule, should wholly volatilize. If a red or brown residue is left from the solution, an admixture of Fig. 130. mineral substances (brick-dust, mercuric sulphide, or red oxide of lead) would be indicated. If the nature of such a residue has to be ascertained, a somewhat larger quantity may be obtained, which, when washed and dried, may be heated in a reducing-tube HYDRARGYRUM. 385 (Fig. 130) ; vermilion volatilizes, forming a fine, red sublimate ; red oxide of lead fuses, atid exhibits, when cooled, a yellow vitri- fied appearance, and dissolves, when boiled in concentrated nitric acid diluted with an equal bulk of water, leaving behind silicious mineral substances, if such be present. The solution of the oxide in dilute nitric acid may also be tested with argentic ni- trate, which should afi'ord no turbidity, thus establishing the absence of chlorides. HYDRARGYRI SUBNITRAS. HYDRAEGYRUM MTRICUM OXYDULATUM. Subnitrate of Mercury. Mercurous Nitrate. Qer. Salpetersaures QueoUsilberoKydul ; Pr. Azolate mercuiieux ; Sp. Protouitrato de mercurio. HgNO,+ HP; 279.7. Colorless, transparent monoclinic tables or prisms,* containing one molecule (6.5 per cent.) of water of crystallization, which is lost on exposure to dry air or by standing over sulphuric acid ; they melt at 70° C. (158° F.), and when gradually heated in a dry tube, emit yellow nitrous vapors, become yellow, then red, and are finally resolved into metallic mercury ; the crystals become grayish-black when moistened with lime-water. Mercurous nitrate is soluble in a small amount of warm water, but, upon the addition of more water, it becomes decomposed, with the separation of a yellow basic salt, HgNOj + HgOH, while an acid nitrate remains in solution; it is, however, entirely solu- ble in water acidulated with nitric acid, forming a colorless solu- tion, which, when rubbed on bright copper, coats it with a white, metallic film, and, when largely diluted, yields a white precipi- tate with hydrochloric acid, and a black one with ammonia or lime-water. Liquor Hydrargyri Nitrici Oxydulati of German pharmacy is a solution of this salt, containing 10 per cent, of mercurous nitrate. Examination : Mercuric nitrate may be detected by completely precipitating the solution of the salt in cold dilute nitric acid with diluted hydrochloric acid, and testing the filtrate, in separate portions, with hydrogen sulphide and with stannous chloride, and warm- ing ; a black precipitate with the first reagent, and a gray one with the second, would indicate mercuric nitrate. * According to the proportion between the mercury and the nitric acid cm- ployed in the preparation, there is formed a normal or a basic mercurous nitrate, ■which correspond in their chemical and therapeutical properties, except that, when rubbed with a little sodium chloride, the normal salt remains white, while the basic salt gives a grayish-green mixture. as 386 MANUAL OF CHEMICAL ANALYSIS. HYDRARGYRI SUBSULPHAS FLAVUS. HYDRARGYRUM SULFURICUM FLAVUM. TURPETHUM MINERALE. Yellow Subsulpliate of Mercury. Basic Mercuric Sulphate. Turpeth Mineral. Ger. Basisch Schwefelsanres Qnecbsilbeioxyd ; Fr. Sous-sulfate de mercure ; Sp. Sullato basico de mercurio. HgSO, + 2HgO ; 727.1. A heavy, lemon- ^^ellow powder, of a crystalline structure when seen under the microscope, having a specific gravity of 8.3, and possessing an acrid taste. When heattd in a dry tube, it assumes a reddish-brown hue, but regains its original color on cooling ; at a higher temperature it volatilizes without fusion, yielding a white sublimate (mercuric sulphate) intermingled with gray me- tallic mercury ; it is decomposed and entirely volatilized at a red heat, evolving vapors of mercury and of sulphurous acid. Basic mercuric sulphate is almost insoluble in cold, and spar- ingly soluble in hot, water, but soluble in diluted hydrochloric and nitric acids, forming colorless solutions which, when diluted, give a white preci])itate with soluble barium salts, and which otherwise, in their deportment with reagents, resemble the solu- tions of mercuric chloride and oxide (pages 374 and 388). HYDRARGYRI SULPHIDUM RtTBRUM. HYDRARGYRUM SULFURATUM RUBRUM. CINNABARI8. lied Sulphide of Mercury. Cinnaiar. Vermilion. Mercuric Sulphide. Ger. Schwefelquecksilber, Zinnober ; Fr. Sulfiire de mercure rouge ; Sp. Deutosulfuro de mercurio. HgS; 231.7. Heavy masses, or cakes, of a specific gravity of 8.124, and of a dull blackish-red color, and a brilliant crystalline texture, yielding a red streak when scratched with a knife, and a magnificent scarlet powder, which becomes black when moistened with an ammoni- acal solution of argentic nitrate. When heated to 250° C. (482° F.), mercuric sulphide becomes brown, at a higher temperature, black, and, on cooling, reassumes its red color ; at a strong heat, with exposure to the air, it is wholly dissipated, burning with a blu- ish flame, and emitting the odor of sulphurous acid ; when gently heated in a small glass tube, it softens, and sublimes without pre- vious fusion, but undergoes partial dissociation into a black mix- ture of mercuric sulphide, mercury, and sulphur, with the evolu- tion of a little sulphurous acid; when heated in closed vessels, HYDRARGYRUM. 387 ■with exclusion of the air, it sublimes below a red heat, without decomposition, in the form of beautiful red, crystalline crusts. Mercuric sulphide is insoluble in the common solvents, nor is it acted upon by officinal hydrochloric or nitric acid, or by alka- line hydrates, at common temperatures; boiling concentrated sul- phuric acid decomposes it, with the formation of mercuric sul- phate, attended by the separation of sulphur and the evolution of sulphur dioxide ; it is also soluble in concentrated hydriodic acid in the cold, and in the dilute acid when warmed, with the evo- lution of hydrogen sulphide; nitro-hydrochloric acid (aqua regia) dissolves it readily, even in the cold, with the formation of mer- curic chloride and sulphuric acid, and the separation of sulphur, and yielding a colorless solution which, when diluted with water, gives a white precipitate with barium chloride, coats metallic copper with a film of mercury, and corresponds in its deportment with reagents to solutions of mercuric salts (pages 374 and 383). Examination : Oxides of Lead and Iron. — Such admixtures will be indicated by the incomplete volatilization of the mercuric sulphide when strongly heated in a small glass tube ; their presence may be confirmed by agitating a small portion of the salt, in a test-tube, with about five times its weight of concentrated nitric acid; the scarlet color must remain unaltered, as change to a darker tint would indicate red oxide of lead ; the mixture is then gently heated by immers- ing the test-tube in hot water, and is subsequently diluted with twice its volume of water, and filtered ; the filtrate should be colorless; a yellowish appearance would indicate red basic plumbic chromate, or mercuric chromate (chromic cinnabar); it is then tested in separate portions with hydrogen sulphide, with sulphuric acid, and with potassium iodide, for lead ; another portion is tested with potassium ferrocyanide for ferric oxide; if this be present, the yellowish color of the nitric acid, agitated with the cinnabar, may be due only to iron. Ghromates may be detected or confirmed by the occurrence of red irritating fumes of chloro-chromic anhydride (CrO^Cl^), when a small portion of the mercuric sulphide is carefully mixed and heated in a test-tube with a few small fragments of dry sodium chloride and a few drops of concentrated sulphuric acid. Mercuric Iodide, Realgar, and Antimonic Cinnabar. — A portion of the mercuric sulphide is agitated with about five times its weight of a warm concentrated solution of potassium hydrate, the liquid subsequently diluted with an equal volume of water, and filtered ; the filtrate should be colorless, should cause neither a coloration nor a turbidity when dropped into chlorine- water, and should not afford a colored precipitate when dropped into a dilute solution of plumbic acetate. A yellow or reddish coloration of the chlorine- water would indicate mercuric iodide, and a black precipitate with plumbic acetate, red arsenic sulphide (Realgar), 388 MANUAL OF CHEMICAL ANALYSIS. or antimonic oxy-sulphide (Antimonfc Cinnabar). If either of the latter two be indicated, the alkaline filtrate will give, upon supersaturation with hydrochloric acid, a yellow precipitate when the first compound is present, and an orange-red one with the second. H YD R ARGYRUM. Mercury. Quicksilver. Ger. Quecksilber ; Fr. Mercure ; Sp. Mercnrio. Hg; 199.7. A silver-white and brilliantly lustrous metal, having a specific gravity of 13.595 at 0° C. (32° F.) compared with water at 4° C. (39.2° F.), or 13.573 at 15° C. (59° F.). It is hquid at common temperatures, and easily divisible into spherical globules, but solidifies when cooled to —39.38° C. (—38.88° F.), forming at and below that temperature a ductile, malleable mass, capable of being cut with a knife, and crystallizing in octahedrons of the regular system, which have a specific gravity of 14.39 ; it boils at 357.25° C. (675.05° F.), forming a transparent, colorless vapor, but is volatile to a perceptible extent at ordinary temperatures, both in a vacuum and in air. When pure, it is unalterable by the action of the air at common temperatures, and remains bright and brilliant. Mercury is insoluble in the common solvents, in concentrated hydrochloric acid, and, at common temperatures, also in sulphuric acid ; but it is dissolved by the latter when boiled with it, and is readily dissolved without residue by nitric acid, forming a solution, which contains mercuric nitrate when heat is applied and an excess of concentrated acid, and mercurous nitrate when the metal is in excess or is acted upon by cold and diluted nitric acid. Examination : Mercury amalgamates with many metals, and, to a certain ex- tent, without change of its appearance and properties ; the most common of such metallic impurities are lead and tin, and occa- sionally zinc and bismuth; their presence in the commercial metal is indicated by a dull, tarnished appearance, and a black, powdery coating of the surfaces of the metal, and of the inside of the vessels containing it, and by lead-gray streaks upon white paper when a few globules of the metal are allowed to roll over it. Such contamination may be ascertained by agitating for a few minutes a little of the mercury, in a strong bottle, with a moder- ately dilute solution of ferric chloride (free from ferrous salt); after subsiding, the aqueous liquid is poured into a test-tube, diluted with an equal volume of water, and tested with a few HYDRARGYRUM. 389 drops of a solution of potassium ferricyanide; a blue 'turbidity will indicate the above-mentioned metallic impurities. When their nature has to be determined, the following method is practicable and simple. About 20 grams of the metal, includ- ing as much of the powdery coating on the surfaces of the metal and the bottle as can be collected, is heated and volatilized in a small porcelain crucible, in a place where the vapors are readily removed by draught; if a non-volatile residue remains, it is heated to redness. A small part of the residue is then heated in a test-tube with a few drops of concentrated hydrochloric acid; the solution is decanted from the insoluble residue, and, after the addition of a little nitric acid or chlorine-water, one drop of solu- tion of auric chloride is added.; an ensuing purple or violet-red turbidity would indicate tin. The rest of the residue in the crucible is treated with warm con- centrated nitric acid; if only partial solution takes place, and at the same' time a white precipitate is formed, this may be oxide of tin or antimony; in order to distin- guish them, the precipitate Fig. 131. is separated from the acid solution, washed with a lit- tle water, and subsequently heated upon charcoal be- fore the blow-pipe; stannous oxide remains unchanged, while antimonic oxide volatil- izes in white fumes, forming a white concentric incrusta- tion on the coal (Fig. 131). The nitric acid solution is diluted with an equal bulk of water, and part of it is tested with solution ot sodium sulphate ; a white precipitate would indicate lead; another part is poured into a large beaker full of water ; a white opalescence or turbidity of the water indicates bismuth. If lead be present, the rest of the nitric acid solution is satu- rated and completely precipitated with hydrogen sulphide, and allowed to stand in a corked test-tube for some hours ; it is then filtered and supersaturated with ammonia- water ; a white pre- cipitate would indicate zinc. If the precipitate is not quite white, and the lead has been completely removed, it might be due to traces of iron, of which metal, however, mercury can only contain traces, since it does not amalgamate with it. An efficient and satisfactory method for the purification ot mercury, when contaminated with foreign metals, consists in shaking it vigorously with an equal volume of a solution com- posed of 5 grams of potassium bichromate and 5 grams of pure 390 MANUAL OF CHEMICAL ANALYSIS. concentrated sulphuric acid in 1 liter of water. The metal is reduced to small globules, while a very small part of it is con- verted into red chromate. The agitation is continued until the red powder has disappeared and the aqueous solution has acquired a pure green color, due to the chromium sulphate formed. By means of a powerful current of water, which is passed into the flask, the gray powder upon the surface of the mercury, which is composed of the oxides of the metallic impurities, is washed away. The process of oxidation is repeated once or twice, according to the degree of impurity, until gray powdery particles are no longer formed, when the mercury is finally thoroughly washed with distilled water uatil it remains perfectly clear. HYDRARGYRUM AMMONIATUM. HYDRARGYRUM AMIDATO-BICHLORATUM. HYDRARGYRUM AMMONIATUM BICHLORATUM. HYDRARGYRUM PR^CIPI- TATUM ALBUM. Ammoniaied Mercury. White Precipitate. Mercurammonium Chloride. Ger. Quecksilberamidochlorid ; Fr. Mercure precipitd blanc ; Sp. Precipitado bianco. NHjHgCl; 251.1. White, pulverulent, friable masses, or a perfectly white, ino- dorous powder, having a specific gravity of 6.7, and developing a styptic taste when placed upon the tongue; it is decomposed and entirely volatilized, without fusion, at temperatures below a red- heat, forming calomel, ammonia, and nitrogen: 6NH,HgCl = 6HgCl + iNH, + N,. It becomes black in contact with hydrogen sulphide, gray when boiled with solution of stannous chloride, and pale yellow, with the evolution of ammonia, when heated with a solution of potas- sium or sodium hydrate. When intimately mixed and triturated, in its dry condition, with iodine, it becomes gradually decomposed with slight deflagration, and with the formation of mercuric chlo- ride and iodide, ammonium chloride, ammonia, and nitrogen gases; the reaction is facilitated by the presence of a little water, but, if alcohol be poured upon the mixture, a violent explosion ensues. Ammoniated mercury is insoluble in the common solvents, and is gradually decomposed by prolonged washing with cold water, more quickly by boiling water, into ammon urn chloride, and a heavy, yellow, insoluble powder of hydrated dimercurammoniuin chloride [Hg.^(NH)2C10] ; it is readily and wholly soluble with- out effervescence in warm hydrochloric, nitric, and acetic acids, forming colorless solutions, which, after dilution with water, HYDRARGYKUJI. 391 yield a white prec'pitate with a cold solution of potassium hy- drate and with argentic nitrate, a black one with an excess of hydrogen sulphide, and a red one with potassium iodide, and which produce a black stain upon bright, metallic copper, coating it, when rubbed thereon, with a brilliant metallic film. Examination : Mercuric chloride is detected by agitating a small portion of the powder with about ten times its weight of diluted alcohol, filter- ing, and testing the filtrate with hydrogen sulphide and witii potassium iodide ; a black precipitate with the first-named re- agent, and a red one with tlie latter, soluble in an excess of the precipitant, will indicate mercuric chloride. Merctirous chloride may be detected by a black coloration of the powder, when it is triturated with lime-water, or by dissolving a small portion of the powder in warm diluted nitric acid ; if an insoluble residue remains, it is washed by deeantation, and, when the water ceases to act on blue litmus-paper, the residue is agitated with lime-water; if rnercurous chloride, it will become black. Phimbic Carbonate and Chloride, and Calcium Carbonate.— Gslt- bonates are indicated by effervescence of the powder with acids, and plumbic chloride by its solubility in hot water (from which it separates in a crystalline form upon cooling), and by its very sparing solubilty in diluted hydrochloric and nitric acids. The presence of lead and calc'um salts may be further confirmed by dissolving a portion of the powder in warm acetic acid, filtering, and testing a little of the filtrate with sulphuric acid, when a white precipitate will indicate lead, and, if the solution is not too dilute, the possible presence also of calcium ; if a precipitate is produced, the remaining portion of the acetic acid solution is com- pletely saturated with hydrogen sulphide, subsequently filtered, and the filtrate tested with ammonium oxalate, when a white pre- cipitate will reveal the presence o^ calcium. Zinc and tnacjnesiuin oxides may be detected in the solution of the powder in hydrochloric acid, after dilution with water, by complete precipitation with hydrogen sulphide, and by subsequent neutralization of the filtrate with ammonia-water, and the addition of ammonium sulphide; a white preo pitate will indicate zinc; after the complete precipitation of the latter, and subsequent fil- tration, the solution is boiled for a few minutes, and, after being allowed to cool, is tested by the addition of a solution of sodium phosphateand a little ammonia- water, when the formation of a white crystalline precipitate will reveal the presence of magnesium. These and all other non-volatile admixtures are also indicated by remaining behind when a few grains of the ammoniated mercury are heated and volatilized, in a narrow, dry test-tube. Mercurdiamrnonium chloride. (NH3)2Hg01j, or fusible white pre- cipitate, will be indicated in this test by a partial or complete 392 MANUAL OF CHEMICAL ANALYSIS. fusion of the powder, previous to its volatilizatjoa, provided that the ammoniated mercury be free from, any fixed fusible admixture. Starch. — An admixture of starch is detected by the microscope, by the powder becoming charred when strongly heated on plati- num-foil, and also by a blue coloration, when a small portion of the powder is triturated, and subsequently heated to boiling, with a little water, and then tested with one drop of iodinized potas- sium iodide. HYOSCYAMIN.ai SULPHAS. HyOSCyAMINQM SULFURICUM. Sulphate of Hyoscyamine. Hyoscyamine Sulphate. Ger. Schwefelsanres Hyoscyamin ; Pr. Sulfate de hyoscyamine ; Sp. Sulfate de hiosciamina. (C„H,3N03),.H,SO,; 676. Small, golden-yellow, or yellowish -white scales or crystals, or a yellowish-white, amorphous powder, deliquescent on exposure to the air. When heated on platinum-foil, the salt is decomposed with the separation of carbon, and is finally completely dissipated. Hyoscyamine sulphate is very freely soluble in water and in alco- hol. Its aqueous solution is neutral in its action upon litmus, possesses a bitter and acrid taste, and yields with solution of barium chloride a white precipitate, insoluble in hydrochloric acid ; it is also precipitated by most alkaloidal reagents, potassio- mercuric iodide, iodinized potassium iodide, picric acid, etc., but not by solution of platinic chloride ; with aur:c chloride, however, it yields a precipitate, which, when recrystallized from boiling water acidulated with hydrochloric acid, is deposited, on cooling, in brilliant, lustrous, golden-yellow scales, without rendering the liquid turbid (distinction from atropine). lODOPORMUM. lODOFORMIUM. Iodoform. Teriodide of Formyl. Methenyl Iodide. Ger. Jodoform ; Fr. lodoforme ; Sp. lodoformo. CHI3; 392.8. Small, lemon-yellow, friable, six sided scales (Fig. 132), of a pearly lustre, a peculiar, penetrating, and persistent odor, and a lODUM. 393 sweetish taste, and with a somewhat anctuous Fig. 132. feel to the touch. Iodoform has a spec. grav. of 2.0, is volatile at common temperatures, and when heated in a dry tube, by immersing it in boiling water, sublimes rapidly at about 95° 0. (203° F.), solidifying in small scales, and may be distilled with aqueous vapor without decomposition ; it fuses at 120° C. (248° F.), and is decomposed above this temperature, or when quickly heated, forming violet vapors, and being resolved into iodine and hydriodic acid, with a residue of carbon, which burns away at a stronger heat. Iodoform is almost insoluble in water, glycerin, diluted acids, and aqueous solutions of the alkaline and earthy hydrates, but is soluble in 80 parts of cold, and 12 parts of boiling, alcohol, in 5.2 parts of ether, and readily in chloroform, carbon bisulphide, benzol, benzin, and in the fixed and volatile oils. Concentrated mineral acids, when cold, have do action on iodoform ; when heated, it remains unchanged with hydrochloric acid, gives a red- dish-brown solution with nitric acid, remaining limpid and brown on dilution with water ; it is freely dissolved, with a violet color, by hot sulphuric acid; upon dilution, however, the color disap- pears, and the iodoform is separated again in small yellow scales. It is not acted upon by tlie aqueous solutions of the alkaline hydrates, but their alcoholic solutions dissolve and decompose it, forming alkaline iodide and formiate. Examination : Chlorides, Iodides, and Sulphates. — A small portion of the iodo- form is agitated with a little water for a few minutes, filtered, and the filtrate, after acidulation with a few drops of nitric acid, tested in separate portions with argentic nitrate and barium chloride ; a white, curdy precipitate with the first-named reagent will indi- cate a contamination with chlorides or iodides, while a heavy white precipitate with the latter will reveal the presence of sul- phates. lODTJM. lODINUM. lODINIUM. Iodine. Ger. Jod ; Fr. lode ; Sp. lodo. I; 126.6. Heavy, brilliant, crystalline plates or scales, of an opaque bluish-black appearance and imperfect metallic lustre, which 394 MANUAL OF CHEMICAL ANALYSIS. Fig. 133. may be -obtained from their solution in hydriodic acid in well developed octahedral combinations of prisms or pyramids of the rhombic system (Fig. 133). Iodine possesses a peculiar odor, less penetrating than, although similar to, that of chlorine and bromine. Its specific gravity is 4.948 at 17° C. (62.6° F.); it melts at 114° 0. (237.2° F.), and boils at a tem- perature above 200° C. (392° F.), giving rise to fei'-''Vfe'f*'»' ^ ^ vapor which, seen by transtnitted white light, ^^^KijfN-' possesses, when chemically pure, a splendid deep ^^Sm^^W blue color, but when mixed with air, a reddish- violet color; it is, however, slowly volatile at common temperatures. When heated in a dry tube (Fig. 134), the vapors condense in the cooler parts of the tube to small, brilliant crystals. Fig. 134. Iodine is but sparingly soluble in water, requiring 4500 parts of it at 15° C. (59° F.), and imparting to it a faint brownish-yel- low tinge. It is more soluble in glycerin, 100 parts of which dissolve a little more than 1.5 parts of iodine. It is also soluble to some extent in the aqueous solutions of certain salts;, as for instance of ammonium chloride and nitrate. Aqueous solutions lODUM. 395 of hydriodic acid ani of the alkaline iodides and bromides, dis- solve iodine freely, as do also alcohol and ether, with a reddish- brown color, benzol and chloroform with a violet-red, and carbon bisulphide with a rich purple. An aqueous solution of sodium hyposulphite dissolves iodine at first without color, and afterward with a brownish-red tint. Chloroform and carbon bisulphide, when shaken with an aqueous solution of iodine, deprive it of most of the iodine, and assume, when the fluids have separated, a more or less red color, while the aqueous solution appears almost colorless. Iodine forms with starch a deep-blue compound, which offers a very delicate test for iodine in all solutions and in bodies which contain it in the free state ; the reaction is, however, impaired by the presence of certain nitrogenized organic substances, such as albumen, etc., as also by quinine and tannic acid. Examination : Moisture is indicated in iodine by its adhering to the surface of the bottles, and by a sticky coherence of the scales, as also by the separation of globules of water when the iodine is dissolved in chloroform or carbon bisulphide ; its amount may be quanti- tatively determined by triturating a weighed amount of the iodine (about 2 grams) in a small porcelain capsule (the weight of which, together with that of the pestle, has been previously deter- mined) with about double its weight of mercury and a little alcohol, suf&cient to moisten the mixture, until complete combi- nation is effected and free iodine can no longer be detected, either by the eye or by its odor; the mixture of mercurous iodide and mercury is then heated to 100° 0. (212° F.) until its weight re- mains constant, when the weight of the applied iodine and mer- cury, minus the weight of the dried mixture, will represent the amount of water contained in the iodine employed. Iodine cyanide, ICN, will be indicated by its exceedingly irri- tating odor, and may be detected by agitating the iodine with a little water for a few minutes, filtering, and adding to the filtrate sufficient of a solution of potassium hydrate to produce a colorless or nearly colorless solution ; a few drops of a solution of ferrous sulphate and ferric chloride are then added, and subsequently hydrochloric acid in slight excess, when the formation of a blue precipitate, either at once or upon standing, will confirm the presence of iodine cyanide. Chlorine and Bromine. — A small portion of the iodine is dis- solved in sulphurous acid, the colorless solution strongly super- saturated with ammonia- water, and subsequently completely precipitated by argentic nitrate, and filtered; the .filtrate, upon supersaturation with nitric acid, should not iDecome cloudy nor yield a precipitate ; a white precipitate will indicate the presence of chlorine or bromine, as also of cyanogen, in case the latter should have been confirmed by the preceding test. . 396 MANUAL OF CHEMICAL ANALYSIS. Fixed a.nd insoluble admixtures (graphite, coal, carburet of iron, metallic oxides or sulphides) are detected by remaining behind upon the volatilization of a little of the iodine in a test-tube, or upon solution of it in alcohol or in an aqueous solution of potas- s um hydrate or sodium hyposulphite. If the nature of such admixtures has to be determined, the residue is collected and washed upon a filter, and afterward treated with warm hydro- chloric acid diluted with an equal bulk of water, which dissolves Fig. 135. metallic oxides, and to some extent the sulphides, with the evolu- tion of hydrogen sulphide. The obtained solution may further be examined for metals, as described in the systematic course of analysis (pages 51 to 61). The insoluble residue left from the solution in hydrochloric acid is levigated (Fig. 135), whereby graphite and carburet of iron may be separated and distinguished from heavier mineral substances. Estimation : About 0.5 gram of the iodine, accurately weighed, is dissolved, in a small flask, in about 10 cubic centinieters of an aqueous ten per cent, solution of potassium iodide. When complete solution has taken place, a standard solution of sodium hyposulphite (page 94) is allowed to flow into the liquid from a burette, until a slight excess has been employed and complete decolorization of the liquid is effected; a little mucilage of starch being then added, the solution is subsequently titrated with a standard solu- tion of iodine (page 93), until a permanent blue coloration is pro- duced. The number of cubic centimeters of the sodium hypo- sulphite solution employed, minus that of the standard iodine solution, when multiplied by its previously accurately determined factor (page 95), will represent the amount of pure iodine in the quantity applied for the test, from which the percentage of impu- rities may readily be calculated. By the employment of 0.633 LIQUORES. 397 gram of iodine, dissolved in a solution of 1 gram of potassium iodide in 25 cubic centimeters of water, and a precisely deci- normal solution of sodium hyposulphite, the number of cubic centimeters required of the latter, when multiplied by 2, will represent, without further calculation, the exact percentage amount of pure iodine in the specimen under examination. LIQUOR AMMONII ACETATIS. LIQUOR AMMONII ACETICI Solution of Ammonium Acetate. Spirit of Mindererus. Ger. Essigsaure Ammoniumlosung; Fr. Acetate d'ammoniaque liquide ; Sp. Solucion de acetato de amoniaco. A clear, colorless liquid, without empyreumatic odor, and of a mild, saline taste; it contains about 7.6 per cent, of neutral am- monium acetate, and has a spec. grav. of 1.022 (1.032-1.034, Pharm. German., corresponding to 15 per cent, of ammonium acetate) ; it is whollj' volatile upon evaporation, and emits the odor of ammonia when heated with potassium hydrate, and that of acetic acid when heated with sulphuric acid ; it assumes a red color upon the addition of a trace of ferric chloride, and, upon heating, the entire amount of iron is precipitated as a basic salt. Examination : Metallic impurities may be detected in the solution, after acidu- lation with hydrochloric acid, by a dark coloration or precipitate upon saturation with hydrogen sulphide, and, after filtration, if necessary, and subsequent neutralization with ammonia-water, by a turbidity or precipitate on the addition of ammonium sulphide. Sulphates and chlorides may be detected by a white turbidity, when the liquid is acidulated with nitric acid and tested, in sepa- rate portions, with barium nitrate for the former salts, and with argentic nitrate for the latter. LIQUOR ANTIMONII CHLORIDL LIQUOR STIBII CHLORATL BUTYRUM ANTIMONII CHLORIDI. Solution of Trichloride of Antimony or of Antimonious Chloride. Ger. Antimonchloruilosung ; Fr. Chlorine d'antlmoine liquide ; Sp. Solucion de cloruro de antimonio. A dense, transparent, colorless or pale-yellow liquid, having a specific gravity of about 1.470. Dropped into water, it .gives a white, bulky precipitate (antimonious chloride with antimonious 398 MANUAL OF CHEMICAL ANALYSIS. oxide — AlgaroMs Powder)^ which is re-dissolved upon the addition of potassium hydrate or tartaric acid. The solution with potassium hydrate remains unchanged, or gives only a slight turbidity, with hydrogen sulphide, and yields a black precipitate with argentic nitrate; while the solution with tartaric acid gives a copious orange-red precipitate with hydrogen sulphide, and a white one with argentic nitrate. Examination : A small portion of the solution, when exposed to a moderate heat in a porcelain capsule, should be completely volatilized. Antimonic chloride is detected in the solution, diluted with an aqueous ten per cent, solution of tartaric acid, in order to avoid precipitation, by the occurrence of a brown coloration on the addition of a few drops of a solution of potassium iodide. Iron and copper may be detected in the solution, after complete precipitation with hot water and subsequent iiltration, by the addition of a few drops of solution of potassium ferrocyanide ; a blue coloration or precipitate will reveal the presence of iron, a reddish-brown one, that of copper. Lead will be indicated by the separation of a white precipitate when the solution of antimonious chloride is mixed with twice its volume of alcohol, and may be further confirmed by the following test: A small portion of the solution is diluted with water, and subsequently solution of potassium hydrate added until the trans- parency of the liquid is again restored ; it is then saturated with hydrogen sulphide, when a black coloration will reveal the pres- ence of lead, a white turbidity, that of zinc. Arsenic. — A portion of the solution is completely precipitated by hot water, filtered, and the filtrate saturated with hydrogen sulphide. The ensuing precipitate, which may consist of arsenic trisulphide, accompanied by a small amount of antimony, is col- lected upon a filter, washed with water, and digested with a con- centrated solution of ammonium carbonate. The latter solution is then filtered, and, upon evaporation to dryness, will leave the arsenic, if present, in the form of yellow arsenic trisulphide ; the latter may be further examined, if required, by fusing it with a mixture of sodium nitrate and carbonate in a small porcelain cru- cible, dissolving the fused mass in a little water, and testing it in Marsh's apparatus (F.g. 20, p. 34), or it may be mixed with a little exsiccated sodium carbonate and potassium cyanide, and heated in a small reduction-tube (Fig. 64, p. 128), when a mirror of metallic arsenic will be produced. Sulphuric and Nitric Acids. — A portion of the solution is com- pletely precipitated with water, filtered, and the filtrate tested, with barium chloride for sulphuric acid, and, in another portion, by the addition of a drop of indigo solution and heating, for nitr c acid ; the presence of the latter will be ind cated by ensuing de- coloration of the liquid. LIQUORES. 399 LIQUOR CALCIS. AQUA CALCIS. AQUA CALCARI^. Lime- Water. Solution of Oalcium Hydrate. Ger. Kalkwasser ; Fr. Eau de chaiix ; Sp. Agua de cal. A clear, colorless, and odorless liquid, consisting of a saturated solution of calcium hydrate, and having, at 15° C. (59° F.), a spe- cific gravity of 1.0015. It possesses a saline and feebly caustic taste and an alkaline reaction, and contains in solution about 0.128 per cent, of calcium oxide, or 0.17 per cent, of calcium hydrate. Lime-water readily absorbs carbonic acid from the air, forming on its surface a pellicle consisting of minute plates of cal- cium carbonate; its alkaline reaction disappears when an excess of carbonic acid gas has been passed through it, and the excess has been expelled afterward by boiling. Lime-water affords no precipitate with sulphuric acid (distinc- tion from solution of barium or strontium hydrate), but it forms white precipitates with carbonic, boracic, phosphoric, arsenious and arsenic, oxalic, and tartaric acids and their salts, and precipi- tates the solutions of those salts whose metallic oxides or hydrates are insoluble in water. The quality of lime-water is best ascertained by its property, when warmed in a test-tube, of separating nearly half the quan- tity of calcium hydrate in minute hexagonal pr.sms; upon cool- ing, the crystals redissolve, and the water becomes perfectly clear again. The presence or absence of alkalies (potassium or sodium hydrate) or alkaline carbonates may be determined by saturating the lime-water with carbonic acid gas, and subsequently' heating to boiling ; the filtered liquid must be neutral to test-paper ; an alkaline reaction would indicate the above-mentioned impurities. LIQUOR FERRI ACBTATIS. LIQUOR FERRI ACETICI.* Solution of Acetate of Iron. Solution of Ferric Acetate. Ger. Essigsaure Eisenoxydlosiing ; Fr. I.iqueuv d'acetate de fer ; Sp. Acetato de hierro liquido. A transparent, dark reddish-brown liquid, containing 33 per cent, of anhydrous ferric acetate, Fe2(CjH30j')5, corresponding, to * Liquor Ferri Acetici. of tlie Pharmacopoea Germanica, is prepared by the precipitation of 10 parts of solution of ferric chloride, of 1.28(Uo 1.283 spec grav., diluted with ."iO parts of water, with a mixture of 10 parts of ammonia-watPi-, spec. grav. 960, and 200 parts of water ; the precipitate is collected and washed 400 MANUAL OF CHEMICAL ANALYSIS. ' 7.93 per cent, of metallic iron, and haying a spec. grav. of 1.160 at 15° 0. = 59° F. (1.081 to 1.083, Pharm. Germ., corresponding to from 4.5 to 5 per cent, of metallic iron, or from 18.7 to 20.8 per cent, of anhydrous ferric acetate); it has a faint odor of acetic acid, which becomes more evident upon warming; this may also be recognized by the formation of white vapors, when a glass rod, moistened with ammonia-water, is held over the liquid. Solution of ferric acetate yields with ammonia-water a reddish- brown precipitate, and with potassium ferrocyanide, a deep-blue one ; and, when largely diluted with water, should afford with a few drops of a freshly prepared solution of potassium ferricyanide a pure greenish-brown coloration, without a blue tint (evidence of the absence of ferrous salts). If the solution be heated to boil- ing, it becomes turbid, in consequence of the separation of insoluble basic ferric acetate. Examination : A small portion of the liquid is diluted with twice its volume of water, and the iron completely precipitated by the addition of a considerable excess of ammonia-water and heating to boiling; the filtrate must be wholly volatile when a few drops of it are evaporated in a porcelain capsule or on platinum-foil ; a viscid residue, which becomes charred at a stronger heat, with the evo- lution of vapors having the odor of caramel, would indicate sugar or fruit-acids^ which, when present in considerable quantities, pre- vent the complete precipitation of the ferric solution by ammonia- water. A bluish tint of the filtrate would indicate copper^ which, with other metallic impurities, may be further determined by saturating it with hydrogen sulphide, both before and after acidu- lation with hydrochloric acid. Hydrochloric and Sulphuric Acids. — A portion of the solution, diluted with an equal volume of water, is heated until the iron has become completely precipitated, and filtered ; the filtrate, after acidulation with nitric acid, is then tested, in separate portions, with argentic nitrate for hydrochloric acid, and with barium nitrate or chloride for sulphuric acid. The verification of the proper amount of iron in the solution may be accomplished by reference to its specific gravity, and by evaporating 10 grams of the solu- tion, to which a few drops of nitric acid have been added, to dryness, in a small platinum capsule, and subsequently igniting at a red heat; the residue of ferric oxide thus obtained should weigh 1.13 grams. upon a flannel or felt filter, and afterward subjected to strong pressure. The soft, hnmid mass of ferric hydrate is then transferred to a flask, 8 parts of dilute acefic acid, spec grav. 1.041, added, and the mixture allowed to stand in a cool place, with frequent agitation, until the precipitate has become entirely dis- solved, or but a slight insoluble residue remains ; so much water is then added that the solution shall have the spec. grav. 1.081 to 1.083. LIQUORBS. 401 LIQUOR FERRI CHLORIDI. LIQUOR FERRI SESQUICHLORATL* Solution of Chloride or Perchloride of Iron. Solution of Ferric Ghloride. Ger. Eisenchloricllosung ; Fr. Clilorure de fer liquide ; Sp. Solucion de percloruro de hierro. A dark reddish-brown liquid, having a faint odor of hydro- chloric acid, an acid, strongly styptic taste, and an acid reaction. Its specific gravity is 1.405 at 15° C. (59° F.), and it contains 37.8 per cent, of anhydrous ferric chloride. It is miscible in all proportions with alcohol, water, and glycerin, and the solution after admixture with alcohol is not rendered turbid on the sub- sequent addition of ether. The diluted aqueous solution affords a brownish-red precipitate on the addition of ammonia-water, a blue one with potassium ferrocyanide, and a white one, insoluble in nitric acid, with solution of argentic nitrate. Examination ; Ferric oxy-chloride may be detected by the occurrence of a tur- bidity, when 3 parts of the solution are diluted with water to the measure of 100 parts, and subsequently heated to boiling. Ferrous chloride may be recognized in the diluted solution by an ensuing blue coloration or precipitate on the addition of a freshly prepared solution of potassium ferricyanide. A, portion of the solution, diluted with an equal volume of water, is completely precipitated by an excess of ammonia- water, filtered, and the filtrate divided into four portions, which may be employed for the following tests : Fixed alkalies or alkaline salts may be detected by a non-vola- tile residue upon evaporating a portion of the filtrate to dryness, and subsequent ignition at a gentle heat. Metallic Impurities. — -Copper will be indicated by a blue color of the ammoniacal liquid; and zinc may be detected by a white turbidity or precipitate on the addition of a few drops of ammo- nium sulphide, or, after acidulation with hydrochloric acid, by a white precipitate on the addition of solution of potassium ferro- cyanide. Sulphuric acid will be indicated in the filtrate, after supersatu- ration with nitric acid, by a white precipitate on the addition of solution of barium chloride. Nitric acid may be detected in another portion of the filtrate, concentrated by evaporation, if necessary, by the addition of a slight excess of concentrated sulphuric acid, a drop of indigo solu- tion, and gently heating; ensuing decoloration of the liquid will * Liquor Ferri sesqnichlorati, of the Pharmacopoea Germanica, lias the spec, grav. 1.380 to 1.282, and contains 29 per cent, of anhydrous ferric chloride, corresponding to 10 per cent, of metallic iron. 26 402 MANUAL OF CHEMICAL ANALYSIS. reveal the presence of nitric acid. Or, to a portion of the liquid, mixed with an excess of concentrated sulphuric acid, a crystal of ferrous sulphate is added, or a concentrated solution of the latter salt is carefull_y poured upon the liquid, so as to form two layers (Fig. 129, p. 383), when a dark coloration of the crystal, or a brown or violet-colored zone at the line of contact of the two liquids, will likewise indicate the presence of nitric acid. Estimation : The determination of the strength of liquor ferri chloridi may be readily accomplished, in addition to the verification of the proper specific gravity, by diluting 10 grams of the solution with an equal volume of water, heating to the boiling-point, and com- pletely precipitating the iron by the addition of ammonia-water in excess. The precipitate of ferric hydrate, when collected on a filter, thoroughly washed, dried, and ignited, should leave a residue of ferric oxide weighing 1.86 grams. LIQUOR FERRI CITRATIS. LIQUOR FERRI CITRICI. Solution of Citrate of Iron. Solution of Ferric Citrate. A dark brown, transparent liquid, without odor, and having a slightly ferruginous taste, and an acid reaction. It has a spec, grav. of 1.260, and contains about 35.5 per cent, of anhydrous ferric citrate, Fe/CnHjO,)^, corresponding to 8.1 per cent, of me- tallic iron. When the solution is concentrated by evaporation, at a gentle heat, and spread upon plates of glass, it forms, upon drying, transparent, garnet-red scales, which are easily detached from the glass. If 100 parts of the solution be thus treated, from 48 to 44 parts of the scaled salt should be obtained, which, when completely incinerated at a strong heat, in a small porcelain cru- cible, should leave a residue of ferric oxide, amounting to about 11 parts. Solution of ferric citrate is not precipitated, but is rendered somewhat darker, on the addition of ammonia-water ; and yields, with solution of potassium ferrocyanide, a bluish-green color or precipitate, which is rendered dark blue on the subsequent addition of hydrochloric acid. If the solution be boiled with an excess of solution of potassium hydrate, a reddi.sh-brown precipitate of ferric hydrate is produced ; the filtrate therefrom, after concentra- tion and being allowed to cool, is precipitated by solution of cal- cium chloride, and the filtrate from the latter precipitate, when heated to boiling, yields a white, granular precipitate of calcium citrate. LIQUORES. 403 LIQUOR FERRI BT QUININE CITRATIS. LIQUOR PERRI CITRICI CUM CIIININO CITRICO. Solution of Citrate of Iron and Quinine. Solution of Ferric and Quinine Gitratea. A dark greenish-yellow to yellowish brown liquid, transparent when dilated or in thin layers, without odor, and having a bitter and mildly ferruginous taste, and a slightly acid reaction. It contains 6 per cent, of quinine, which has been dried at 100° C. (212° F.). If the solution be supersaturated with a slight excess of ammo- nia-water, a white, curdy precipitate is produced, which corre- sponds to the reactions and tests of quinine, and the liquid assumes a somewhat darker color. If the mixture be then filtered, and a portion of the filtrate slightly supersaturated with hydrochloric acid, a deep blue precipitate is produced. Another portion of the filtrate, when heated with an excess of solution of potassium hydrate, yields a reddish-brown precipitate of ferric hydrate ; the filtrate therefrom, after concentration and being allowed to cool, is precipitated by solution of calcium chloride, and the filtrate from the latter precipitate, when heated to boiling, yields a white granular precipitate of calcium citrate. On heating the solution with a strong solution of potassium hydrate, vapors of ammonia are evolved. Estimation of the Quinine in Solution of Citrate of Iron and Qui- nine; Eight grams of the solution, contained in a closely fitting, glass- stoppered bottle or flask, are diluted with water to the measure of 30 cubic centimeters, an aqueous solution of 0.5 gram of tartaric acid added, and subsequently solution of sodium or potassium hy- drate, in slight excess. The mixture is then agitated with four successive portions of chloroform, of about 15 cubic centimeters each, the chloroforraic layers being removed by means of a glass separating funnel, afterward mixed, and allowed to evaporate spon- taneously in a weighed glass or porcelain capsule, and finally dried at 100° "C. (212° F.), until of constant weight. The residue of quinine thus obtained should weigh 0.48 gram, corresponding to <6 per cent, of the weight of solution employed. 404 MANUAL OF CHEMICAL ANALYSIS. LIQUOR FERRI NITRATIS. LIQUOR PERRI NITRICI. LIQUOR FERRI PERNITRATIS. Sohition of Nitrate or Pernitrate of Iron. Solution of Ferric Nitrate. Ger. Eisenoxydnitratlosung ; Fi-. Solution d'azotate de fer ; Bp. Solucion de pernitrate de laierro. A transparent amber-colored or reddish-yellow liquid, having an acid, strongly styptic taste, and an acid reaction. Its specific gravity is 1.050 at 15° C. (69° F.), and it contains about 6 per cent, of anh^rdrous ferric nitrate. Diluted with water, it gives a deep-blue precipitate with potassiuni ferrocyanide, but none with potassium ferricyanide, and yields a reddish-brown precipitate with ammonia-water ; when a few drops of a concentrated solu- tion of ferrous sulphate are added to a little of the solution of ferric nitrate, and the mixture is carefully transferred upon con- centrated sulphuric acid (Fig. 129, p. 383), a dark zone, indicating nitric acid, will ensue upon the line of contact between the two liquids. Examination : To a portion of the solution ammonia-water in slight excess is added, the liquid filtered from the precipitate of ferric hydrate, and the filtrate employed for the following tests : Metallic hnpurities. — -Copper will be indicated by a blue color of the ammoniacal liquid ; and zinc may be detected by a white turbidity or precipitate on the addition of a few drops of ammo- nium sulphide, or, after acidulating with hydrochloric acid, by a white precipitate when tested with potassium ferrocyanide. Hydrochloric and sulphuric acids may be detected in another portion of the filtrate, supersaturated with nitric acid, when tested respectively with argentic nitrate and barium nitrate or chloride. Estimation : In addition to the verification of the proper specific gravity, the strength of liquor ferri nitratis may readily be determined by completely precipitating 100 grams of the solution with ammo- nia-water. The precipitate of ferric hydrate, when collected on a filter, thoroughly washed, dried, and ignited, should leave a residue of ferric oxide weighing 2 grams. LIQUORES. 405 LIQUOR FERRI SULPHATIS. LIQUOR FERRI SULFURICI OXYDATI. Solution of Persulphate of Iron. Solution of Ferric Sulphate. Ger. Eisenoxydsulfatlosung ; Fr. Liqueur de persulfate de fer ; Sp. Solucion de persulfato de hierro. The TJ. S. Pharmaeopceia has two solutions of ferric sulphate, Liquor Ferri Sulsulphatis, having a spec. grav. of 1.555, and Liquor Ferri Tersulphatis, having a spec. grav. of 1.320. The former is a solution of basic ferric sulphate [Fe^0(S0j)5], contain- ing 43.7 per cent, of the salt; the latter, a solution of normal ferric sulphate, Fe2(SO^)3, containing 28.7 per cent, of the salt.* The Liquor Ferri Persulphatis of the British Pharmacopoeia has the spec. grav. of 1.441, and that of the Pharmaoopoea Germanica a spec, grav.'of 1.428 to 1.430. They all are transparent, red or reddish-brown liquids, without odor, of an astringent, metallic taste, aud misoible in all propor- tions, with water, alcohol, and glycerin, without decomposition. A few drops of either of them, added to water, form a mixture in which potassium ferricyanide produces no reaction, but ferro- cyanide gives a dark-blue precipitate, ammonia- water a bulky, reddish-brown one, and barium chloride a white one, the latter insoluble in hydrochloric acid. Examination ; Copper and Zinc. — A small portion of either of the above solu- tions of ferric sulphate is mixed with about an equal volume of water, heated to boiling, and the iron completely precipitated by the addition of ammonia-water in excess, and filtered. The filtrate will appear bluish, if copjper be present, and should be entirely volatilized when heated upon platinum-foil ; a fixed residue would indicate alkaline, earthy, or metallic impurities. Part of the filtrate is then saturated with hydrogen sulphide, an ensuing white pre- cipitate would indicate zinc, and a dark one, insoluble upon supersaturation with hydrochloric acid, copper. Nitric acid and nitrates may be detected in a portion of the filtrate of the preceding test, by supersaturating it with concen- trated sulphuric acid, and by subsequently adding one drop of a solution of potassium permanganate, or indigo solution, and gently warming; ensuing decoloration will indicate nitric acid or nitrates. Estimation : In addition to the verification of the proper specific gravity, the strength of solutions of ferric sulphate may be readily determined * Tlie two preparations may readily be distinguished by slowly mixing, in a beaker,, 2 volumes of tlie solution witli 1 volume of concentrated sulphuric acid ; the liquor furri subsulpliatis separates a solid white mass on standing, while the liquor ferri tersulphatis retains its fluidity. 406 MANUAL or CHEMICAL ANALYSIS. by completely precipitating 10 grams of the solution with an ex- cess of ammonia- water, collecting the precipitate of ferric hydrate on a filter, washing it thoroughly with water, and, after drying, igniting in a porcelain crucible at a red heat. Ten grams of liquor ferri subsulphatis should thus afford a residue of ferric oxide weighing 1.938 grams; and the same amount of liquor ferri tersulphatis, a residue of ferric oxide weighing 1.117 grams. LIQUOR HYDRARGYRI NITRATIS. LIQUOR HYDRARGYRI NITRICI OXYDATI. Solution of Ifiirate or Pernitrate of Mercury. Solution of Mercuric Nitrate. Ger. Salpetersaure Quecksilberoxydlosung ; Fr. Nitrate de niercure iiquide ; Sp. Solucion de pernitrato de mercurio. A dense, transparent, nearly colorless, acid liquid, having a faint odor of nitric acid, and, even when diluted, a very acid, caustic and metallic taste. It has a specific gravity of 2.100 at 15° C. (59° F.), when prepared according to the TJ. S. Pharma- copoeia, and of 2.246, when prepared according to the British Pharmacopoeia, containing, in the first instance, about 50 per cent, of mercuric nitrate in solution. When a few drops of the liquid are evaporated at a gentle heat, upon platinum-foil, they leave a white residue, which, upon in- creased heat, becomes successively yellow, red, and brown, and is finally wholly dissipated. The solution remains limpid on the addi- tion of water or of diluted hydrochloric acid (evidence of the ab- sence of mercurous nitrate) ; it gives a dull yellow precipitate with an excess of the fixed alkaline and earthy hydrates, a white one with ammonia- water, a bright red one with potassium iodide, soluble in an excess of the reagent, and a black one with an excess of hydrogen sulphide ; it deposits a brilliant metallic coat- ing on bright copper, and shares, in its deportment with reagents, the general characteristics of mercuric salts, as described under mercuric chloride and oxide (pages 371 and 383). It causes a crystal of ferrous sulphate, dropped into it, as well as the liquid around the salt, to assume a deep-brown color. When diluted with about ten times its volume of water, it should not give a turbidity when tested, in separate portions, with a few drops of solutions of argentic and of barium nitrates (absence of chlorides and sulphates). LIQUORES. 407 LIQUOR PLUMBI SUBACBTATIS. LIQUOR PLUMBI SUBACETICL ACETUM PLUMBICUM. Solution of Subacetate of Lead. Solution of Triplumbic Acetate. Ger. Bleiessig ; Fr. Sous-acetate de plorab liquids ; Sp. Subacetato de plomo liquido. A dense, clear, colorless liquid, of 1.228 spec. grav. (1.235- 1.240 Pharmacopoea Grermanica), having an alkaline reaction and a sweet, astringent taste, and becoming tarbid by absorption of atmospheric carbonic acid, and by dilution with water containing carbonates, sulphates, or carbonic acid. It is precipitated, whether diluted with water or not, by the alkaline and alkaline- earthy hydrates and carbonates, by sulphuric, hydrochloric, oxalic, tannic, and other acids and their salts, and by almost all neutral salts; it forms white, opaque, insoluble compounds with vegetable gums, mucilages, and extracts, and with vegetable and albuminous substances. Liquor plumbi subacetatis gives a yellow precipitate with potassium iodide, and a black one with hydrogen sulphide ; it forms an opaque, white jelly when mixed with mucilage of gum ; it may be recognized as containing an acetate, by evolving the odor of acetic acid, when heated with a few drops of sulphuric acid, and by affording a deep-red color, accompanied by the sepa- ration of plumbic chloride, on the addition of a few drops of a dilute solution of ferric chloride. Traces of copper are indicated by a faint greenish color of the liquid, and may be further recognized by a bluish coloration of the filtrate, when a little of the liquor plumbi subacetatis is mixed with an excess of ammonia-water. Estimation : 13.7 grams of the solution should require for complete precipi- tation 25 cubic centimeters of normal solution of oxalic acid (page 82), corresponding to 25 per cent, of basic plumbic acetate. By the employment of other quantities df the solution than that above mentioned, the calculation may also readily be made, with the consideration that 1 cubic centimeter of normal oxalic acid solution corresponds to 0.13675 gram of basic plumbic acetate, Pb,0(C,H30,), 408 MANUAL OF CHEMICAL ANALYSIS. LIQUOR POTASS^. LIQUOR POTASSII HYDRICI. LIQUOR KALII CAUSTICI. Solution of Potassa. Solution of Potassium Hydrate. Ger. Kalilauge ; Fr. Liqueur de potasse ; Sp. Solucion de potasa. A transparent, colorkss, Jimpid liquid, without odor, of an extremely acrid and caustic taste and strougly alkaline reaction, and having a soapy feel when rubbed between the fingers. It has a destructive action on many vegetable and animal sub- stances, is a powerful solvent for many organic and mineral com- pounds, and readily absorbs carbonic acid gas by exposure to the air ; when dropped into a concentrated solution of tartaric acid, a white crystalline precipitate is produced, which is re-dissolved by an excess of the alkali. The specific gravity of the solution is 1.036 at 15° C. (59° F.), and it contains about 5 per cent, of potassium hydrate.* Examination ; Carbonate is indicated by efl'ervescenoe or by the formation of gas-bubbles, when the liquor potassse is added to an excess of hydrochloric or nitric acid ; it may also be detected by the for- mation of a white precipitate when a little of the liquor potassse is mixed with an equal volume of water, and is then added to lime-water. Sodium hydrate may be detected by the following method, which is based upon the solubility of sodium bitartrate, and the insolubility of potassium bitartrate, in alcohol. A weighed por- tion of the liquor potassse is exactly neutralized with tartaric acid, and to the solution as much tartaric acid subsequently added as was previously required for neutralization. Alcohol is then added until a precipitate ceases to be produced, and the liquid filtered. The filtrate, which will contain the sodium in the form of bitartrate, will deposit the latter upon evaporation, and, upon ignition, will leave a black, strongly alkaline residue of carbon and sodium carbonate. If this residue be dissolved in water, tlie solution filtered, neutralized with dilute nitric acid, and concen- trated by evaporation, rhombohedral crystals of sodium nitrate may be obtained, which impart an intense yellow color to the non-luminous flame. Potassium chloride, sulphide, and hyposulphite may be detected by dropping a little of the liquor potassse into diluted solution of argentic nitrate ; a grayish-brown precipitate will be produced, Avhich, however, should be completely soluble upon the addition of nitric acid in excess; if the precipitate does not wholly dis- ^ Liquor Kalii caustici, of the Pharmacopoea Germanica, has a spec. gray, of from 1.142 to 1.146, and contains about 15 per cent, of potassium hydrate. LIQUORES. 409 solve, and leaves behind a white residue, chloride is indicated ; when the residue is black, sulphide or hyposulphite. Sulphate, Silicate, and Alumina. — -A little of the liquor potassre is slightly supersaturated with diluted nitric acid ; part of the solution is tested with barium nitrate for sulphate ; another part may also be tested with argentic nitrate for chloride ; the rest of the solution is evaporated, in a porcelain capsule, todrjaiess; the remaining salt must yield a limpid solution with water ; a white insoluble residue would indicate silicate; the solution, when necessary, is filtered, and then tested by the addition of a little ammonium chloride and ammonia- water for alumina, which, when present, will afford a white flocculent precipitate. Calcium salts may be detected, in the diluted liquor potasste, previously neutralized with nitric acid, by a white precipitate with ammonium oxalate, or with sodium carbonate. Metallic impurities are indicated by a dark coloration or tur- bidity when the liquor potassae is saturated with hydrogen sul- phide, either before or after supersaturation with hydrochloric acid. Estimation : . The amount of pure potassium hydrate contained in liquor potassae may readily be determined volu metrically. About 20 grams of the liquid are accurately weighed in a beaker or small flask, a few drops of litmus solution added, and subsequently a standard solution of oxalic or sulphuric acid (page 82) allowed to flow into the liquid from a burette until, with constant stir- ring, the blue tint of the liquid is just changed to a cherry-red. From the number of cubic centimeters of the acid solution thus required for exact neutralization, the amount of pure potassium hydrate may be calculated: one cubic centimeter of normal acid corresponding to 0.056 gram of potassium hydrate, KHO. By the employment of 28 grams of the officinal liquor potasste, not less than 25 cubic centimeters of the normal acid solution should be required for exact neutralization, indicating a strength of at least 5 per cent, of potassium hydrate. If the liquor potassas contain carbonate, the amount of carbon dioxide contained in a weighed portiou of the solution must be determined, as described on pages 85-86. For 1 part of carbon dioxide, 00^, 2.545 parts of potassium hydrate, KHO, are de- ducted from the amount volumetrically indicated, and the balance then calculated as pure potassium hydrate. 410 MANUAL OF CHEMICAL ANALYSIS. Table of the quantity hy weight of Potassium Oxide and Hydrate con- tained in 100 parts hy weight of solution (^Liquor Potasses) of different specific gravities (^Gerlach). Temperature 150 0. (59= F.). Per ct. of KjO or KHO. Specific gravity for K,*. Specific gravity for KHO. Per ct. otKsO or KHO. Specific gravity forKoO. Specific gravity for KHO. Per ct. ofKsO or KHO. Specific gravity for KjO. Specific gravity for KHO. 1 1.010 1.009 31 1.280 1.188 41 1.533 1.425 2 1.020 1.017 33 1.242 1.198 43 1.539 1.438 3 1.030 1.035 28 1.256 1.309 48 1.554 1.450 4 1.039 1.033 34 1.270 1.330 44 1.570 1.463 5 1.048 1.041 25 1.385 1.230 45 1.584 1.474 6 1.058 1.049 36 1.800 1.241 46 1.600 1.488 7 1.0B8 1.058 27 1.813 1.253 47 1.615 1.499 8 1.078 1.065 38 1.326 1.364 48 1.630 1.511 9 1.089 1.074 39 1.340 1.276 49 1.645 1.527 10 1.099 1.083 80 1.355 1.388 50 1.660 1.539 11 1.110 1.093 31 1.370 1.300 51 1.676 1.553 13 1.121 1.101 33 1.385 1.311 53 1.690 1.565 13 1.182 1.111 33 1.403 1.334 58 1.705 1.578 14 1.143 1.119 34 1.418 1.336 54 1.730 1.590 15 1.154 1.138 35 1.431 1.849 55 1.783 1.604 16 l.lfiG 1.137 36 1.445 1.861 56 1.746 1.618 17 1.178 1.146 37 1.460 1.374 57 1.763 1.630 18 1.190 1.155 38 1.475 1.887 58 1.780 1.641 19 1.203 1.166 89 1.490 1.400 59 1.795 1.655 "20 1.215 1.177 40 1.504 1.411 60 1.810 1.667 Witli tlie decrease and increase of temperature, the specific gravity of the solution suflfei's a corresponding increase or decrease, amounting for each degree of the centigrade thermometer in either direction — For solution of a specific gravity of 1.810 to that of 1.504 to about 0.00055 " " 1.490 " 1.355 " 0.0005 " 1.340 " 1.2.30 " 0.0004 " 1.315 " 1.010 " 0.00033 LIQUOR POTASSII ARSENITIS. LIQUOR POTASSII ARSENICOSI. LIQUOR KALII AR8ENIC0SL Solution of Potassium Arsenite. Fowler's Solution. Ger. Fowler'sche Tropfen ; Fr. Solution arsenicale de Fowler ; Sp. Solucion de arseuito de potasa. The officinal solution of potassium arsenite contains 1.656 per cent, of primary potassium arsenite, KHjAsO,, corresponding to 1 per cent, of arsenic trioxide, As^Oj;* it has a slight alkaline * Liquor Kalii arsenicosi of the Pharmacopoea Germanica is an aqueous solu- tion of potassium raetaarsenite, KAsO.^ ; and probably, also, of potassium ortho- arsenites, corresponding in amount to 1 per cent, of arsenic trioxide, ASjOj. LIQUORBS. 411 reaction, and gives, with nitrate of silver, a bright-yellow precipi- tate, soluble in ammonia-water ; this solation, when gently warmed for some time, by immersing the test-tube in hot water, suffers a reduction of the silver salt, and deposits the metal, as a brilliant coating, upon the walls of the test-tube. Hydrogen sulphide pro- duces no immediate precipitate in the solution of potassium arse- nite, but, upon the addition of hydrochloric acid, there at once appears a lemon-yellow precipitate, soluble in ammonia-water or in a concentrated solution of ammonium carbonate. Estimation : A quantitative estimation of the amount of arsenic trioxide (arsenious acid), corresponding to the amount of potassium ar- senite contained in liquor potassii arsenitis, may be made by diluting 10 grams of the solution with an equal volume of water, acidulating with hydr(.)chloric acid, and subsequently completely precipitating with hydrogen sulphide. The precipitate is col- lected and washed upon a tared filter, and, after drying at 100° C. (212° F.), is weighed. The weight of the arsenious sulphide, divided by 1.24:2, gives the quantity of arsenious acid contained in 10 grams of the solution, which should be 0.1 gram. The quantitative estimation may also be made volumetrically, by the following method: 10 grams of the solution of potassium arsenite are accurately weighed in a beaker, and the solution diluted with about twice its volume of water. 2 grams of crys- tallized sodium carbonate are then dissolved in the liquid, a little mucilage of starch added, and subsequently a decinormal solution of iodine (page 93) allowed to flow into the liquid, from a burette, until a permanent blue coloration of the liquid is jusi produced. 20.2 cubic centimeters of the iodine solution should be required to produce this reaction, as corresponding to 0.1 gram of arsenic trioxide, or, the amount of the latter may readily be calculated, with the consideration that 1 cubic centimeter of decinormal iodine solution corresponds to 0.00495 gram of arsenic trioxide, As^Oj. The United States Pharmacopoeia directs that if 24.7 grams of the solution are boiled with 0.5 grani of sodium bicarbonate, the liquid, when cold, diluted with 100 cubic centimeters of water, and some mucilage of starch added, should require from 48.5 to 50 cubic centimeters of the volumetric solution of iodine, before the blue color ceases to disappear on stirring (corresponding to 1 per cent, of arsenious acid of the required purity, or, at least, 0.97 per cent, of pure arsenious acid). ■412 MANUAL OF CHEMICAL ANALYSIS. LIQUOR SOT>JE. LIQUOR SODII HYDRICI. LIQUOR NATRII CAUSTICL Solution of Soda. Solution of Sodium Hydrate. Ger. Natroulauge ; Fr. Soude caustique liquide ; Sp. Solucioa de sosa. A transparent, colorless, limpid liquid, without odor, of an extremely acrid and caustic taste and strongly alkaline reaction, and having a soapy feel when rubbed between the fingers. It has a destructive action on many vegetable and mineral substances, is a -powerful solvent for many organic and mineral compounds, and readily absorbs carbon'c acid by exposure to the air; when dropped into a concentrated solution of tartaric acid, no precipi- tate is produced (distinction from solution of potassium hydrate); Avhen a drop of the solution, contained on the looped end of a platinum-wire, is held in the non-luminous flam^, it imparts to the latter an intense yellow color. The specific gravity of the solution is about 1.059 at 15° 0. (59° F.), and it contains about 5 per cent, of sodium hydrate.* Examination : Sodium carbonate is indicated by effervescence, or by the forma- tion of gas-bubbles, when the liquid is added to an excess of con- centrated hydrochloric or nitric acid ; it may also be detected by the formation of a white precipitate upon mixing a little of the liquid with twice its volume of lime-water. Sodium sulphate and chloride are indicated by white precipitates, when the diluted liquid is slightly supersaturated with nitric acid, and tested with barium nitrate for sulphate, and with argentic nitrate for chloride. Calcium salts may be detected by a white precipitate, when the diluted liquid, previously neutralized with nitric acid, is tested with solution of ammonium oxalate or sodium carbonate. Potassium hydrate may be recognized by a white, granular pre- cipitate, on dropping the liquid into a strong solution of tartaric acid, allowing the latter to reniain in excess. Metallic mpurities are indicated by a dark coloration or tur- biditv when the liquor sodas is saturated with hydrogen sulphide, either before or after supersaturation with hydrochloric acid. Estimation : The amount of pure sodium hydrate contained in liquor sodse may readily be determined volumetrically. About 20 grams of the liquid are accurately weighed in a beaker or small flask, a few drops of litmus solution added, and subsequently a standard solution of oxalic or sulphuric acid (page 82) allowed to flow into * Liquor Natvii caustic! of the Pliarmacopoea Germanica has a spec. grav. of from 1.159 to 1.163, and contains about 15 per cent, of sodium hydrate. LIQUORES. 413 the liquid from a burette, until, with constant stirring, the blue tint of the liquid is just changed to a cherry-red. From the number of cubic centimeters of the acid solution thus required for exact neutralization, the amount of pure sodium hydrate may be calculated : one cubic centimeter of normal acid corresponding to 0.0-iO gram of sodium hydrate, NaHO. By the employment of 20 grams of the ofiicinal liquor sodse, not less than 25 cubic centi- meters of the normal acid solution should be required for exact neutralization, indicating a strength of at least 5 per cent, of sodium hydrate. If the liquor sodse contains carbonate, the amount of carbon dioxide contained in a weighed portion of the solution must be determined, as described on pages 85-86. For 1 part of carbon dioxide, CO^, 1.818 parts of sodium hydrate, ISTaHO, are deducted from the amount volumetrically indicated, and the balance then calculated as pure sodium hydrate. Table of the quantity by weight of Sodium Oxide and Hydrate contained in 100 parts by weight of solution (^Liquor Sodce) of different specific gravities ( Gerlach'). Temperature 150 C. (590 F.). Pev ct. of Ka„0 Specific Specific Per ct. of NajO Specific Specific Per ct. of Ha.O Specific Specific 01' gravity graviiy or gravity gravity or gravity gravity NaHO. for KaaO. for NaHO. NaHO. forNajO. for NaHO. NaHO. for Ka.0. for NaHO. 1 1.015 1.013 21 1.300 1.236 41 1.570 1.447 2 1.029 1.033 23 1.H15 1.247 42 1.583 1.456 3 1.043 1.035 33 1.329 1.3.58 43 1.597 1.468 4 1.058 1.046 24 1.341 1.369 44 1.610 1.478 5 1.074 1.059 25 1.355 1.2T'J 45 1.633 1.488 fi 1.089 1.070 36 1.309 1.290 46 1.637 1.499 7 1.104 1.081 27 1.381 1 300 47 1.650 1.508 8 1.119 1.092 28 1.395 1.310 48 1.663 1.519 9 1.132 1 103 29 1.410 1.331 49 1.678 1.529 10 1.145 1.115 30 1.422 1.K33 50 1.690 1.540 11 1.160 1.126 31 1.438 1.343 51 1.705 1.550 12 1.175 1.137 32 1.450 1.351 53 1.719 1.560 13 1.190 1.148 33 1.402 1.363 53 1.730 1.570 14 1.203 1.159 ' 34 1.475 1.374 54 1.745 1.580 15 1.219 1.170 35 1.480 1.384 55 1.760 1.591 16 1.233 1.181 36 1.500 1.395 56 1.770 1.601 17 1.245 1.191 37 1.515 1.405 57 ■ 1.785 1.611 18 l.2r,8 1.302 38 1.530 1.415 58 1.800 1.632 19 1.270 1.313 39 1 . 543 1-430 59 1.815 1.033 20 1.280 1.225 40 1.558 1.437 60 1.830 1.643 With the decrease and increase of temperature, the specific gravity of the solution suffers a corresponding increase or decrease, amounting, for eacli degree of the centigrade thermometer in either direction— For solution of a specific gravity of 1.830 to that of 1.355 to about 0.00045 " 1.341 " 1.219 " 0.0004 " " " " 1.303 " 1.015 " 0.00033 414 MANUAL OF CHEMICAL ANALYSIS. LIQUOR SODiE CHLORATiE. LIQUOR SOD^ CHLORINATE. LIQUOR NATRII HYPOCHLOROSI. Sohttion of Chlorinated Soda. Solution of Sodium Hypochlorite. Ger. Unterchlorigsaure Natiiumlosung ; Fr. Eau de Labarraque ; Sp. Licor de Labariaque. A transparent liquid of a pale greenish-yellow color, having a faint odor, resembling that of chlorine, and a disagreeable aliia- line taste and alkaline reaction. Its specific gravity is 1.044 at 16° C. (59° F.), and it contains about 2 per cent, of available chlorine. Solution of clilorinated soda becomes decomposed upon heat- ing, with the formation of sodium chlorate and chloride, and, upon exposure to sunlight, liberates oxygen, with the simultaneous formation of sodium chlorate, chlorite, and chloride. It possesses oxidizing properties, and is rendered much more energetic in its action by the addition of acids, in consequence of the developed chlorine ; it rapidly decolorizes solution of indigo and other vegetable colors, and produces in the solutions of many metallic salts, such as lead, manganese, cobalt, and nickel, brown or black precipitates of the respective peroxides or perhydrates ; when added to a solution of ferrous sulphate, a copious, light-brown pre- cipitate is produced, and with solution of mercuric chloride it affords a brown precipitate of mercuric oxychloride, HgjGl^O. Examination : Calcium salts will be indicated by a white precipitate on the addition of solution of sodium carbonate. Sodium carbonate, when present in any considerable excess, will be indicated by the formation of a precipitate, when the solution of chlorinated soda is mixed with twice its volume of alcohol. Estimation : The value of solution of chlorinated soda depends upon the amount of available chlorine which it contains, which may readily be determined by the following method. 8.88 grams of the solution are mixed, in a beaker, with a solution of 2.6 grains of potassium iodide in 200 cubic centimeters of water ; 18 grams of hydrochloric acid are subsequently added to the solution, together with a few drops of mucilage' of starch, and, after being well mixed, a standard solution of sodium hyposulphite (page 94) is allowed to flow into the liquid from a burette until, with constant stirring, complete decoloration of the liquid is effected. If the solution be of the proper strength, not less than 50 cubic cen- timeters of the solution of sodium hyposulphite should be re- quired to produce this reaction, indicating at least 2 per cent, of available chlorine. By the employment of other amounts of the solution of chlori LITHIUM. 415 nated soda, or, when the proportions above indicated are observed, the exact amount of available chlorine contained in tlie solntioa may also be calculated, by the consideration that 1 cubic cen- timeter of standard sodium hyposulphite solution corresponds to 0.0035 gram of free chlorine. LITHII BENZOAS. LITHIUM BENZOICUM. Benzoate of Lithium. Lithium Bemoate. Ger. Benzoesaures Lithium ; Fr. Benzoate de lithium ; Sp. Benzoato de litina. LiC^H^O,; 128. A white powder, or small shining scales, permanent in the air, of a faint benzoin-like odor, a cooling and sweetish taste, a-nd a faintly acid reaction. On being heated, the salt first fuses, then, at a higher temperature, it chars, emitting inflammable vapors of a benzoin-like odor, and finally leaves a black residue of an alka- line reaction. A little of the salt, when heated on the looped end of a platinum wire, in the non-luminoQS flame, imparts to the latter an intense carmine-red color. Lithium benzoate is soluble in 4 parts of water and 12 parts of alcohol at 15° C. (59° F.), in 2.5 parts of boiling water and in 10 parts of boiling alcohol, but is insoluble in ether. Its aqueous solution yields on the addition of a dilute solution of ferric chloride a flesh-colored precipitate of basic ferric benzoate, and with hj'dro- chloric acid a precipitate of benzoic acid, which redissolves on the subsequent addition of alcohol. Examination : Sulphates and chlorides may be detected in the diluted aqueous solution of the salt, strongly acidulated with nitric acid, and fil- tered, if necessary, by testing it in separate portions, with barium nitrate for the former, and with argentic nitrate for the latter. Potassium and Sodium Salts. — A small portion of the salt is ignited, in a porcelain crucible, at a red heat, the ignited residue dissolved in diluted hydrochloric acid, and the solution filtered and evaporated to dryness. 1 part of this residue should be com- pletely soluble in 3 parts of absolute alcohol, forming a solution which, when ignited, burns with a crimson flame, and which is not precipitated by the subsequent addition of an equal volume of stronger ether; if the ignited residue be incompletely soluble in alcohol, the presence of salts of the alkalies will be indicated. Calcium salts may be detected in the aqueous solution of the above-described ignited residue, by the formation of a white pre- cipitate when tested with solution of ammonium oxalate. 416 MANUAL OF CHEMICAL ANALYSIS. Metallic impurities may be detected in the aqueous solution of the salt, acidulated with hydrochloric acid, and filtered, if neces- sary, by a dark coloration or a turbidity when saturated with hydrogen sulphide, or, after neutralization with ammonia-water, by the addition of ammonium sulphide. LITHII BROMIDUM. LITHIUM BROMATUM. Bromide of LitMum. Lithium Bromide. Ger. Bromlithium ; Fr. Bromnre de lithium ; Sp. Bromuro de litio. LiBr; 86.8. A white, granular salt, very delique.scent on exposure to the air,'neutral in its action upon litmus, and possessing a sharp and slightly bitter taste. On exposure to a low, red heat the salt fuses, and, at a higher temperature, it is slowly volatilized. A fragment of the salt, contained on the looped end of a platinum- wire, when brought into the non-luminous flame, imparts to the latter a carmine red color. Lithium bromide is very freely soluble in both water and alco- hol ; its aqueous solution yields on the addition of a solution of argentic nitrate a yellowish- white precipitate, which is soluble in a large excess of ammonia-water. If a little carbon bisulphide be poured upon a solution of the salt, a few drops of chlorine- water subsequently added, drop by drop, and the whole well agi- tated, the carbon bisulphide will acquire a yellowish or brownish- red color, but should show no violet tint. Examination : Alkaline bromides, iodides, and chlorides may be tested for by dissolving 0.1 gram of the dry lithium bromide in 10 cubic cen- timeters of water, adding thereto a solution of 0.2 gram of argentic nitrate in about 10 cubic centimeters of water, agitating the mix- ture, and filtering. The filtrate should not become turbid on the subsequent addition of solution of argentic nitrate, and the above- obtained precipitate should be completely soluble in a large excess of ammonia- water ; a turbidity in the first instance would indicate chloride, and incomplete solubility in the second instance, the presence of iodide. As a special test for potassium bromide, 0.1 gram of the dry lithium bromide and 0.19 gram of argentic nitrate are dissolved, separately, in small portions of water, the solutions mixed, agitated, and filtered ; the filtrate should remain clear upon the addition of a few drops of hydrochloric acid; if a pre- cipitate is thereby produced, the presence of potassium bromide or other potassium or sodium compounds will be indicated. LITHIUM. 417 Potassium and Sodium Sails. — These impurities, in addition to the above tests, will be indicated by dissolving one part of the lithium bromide in three parts of absolute alcohol ; a clear solu- tion should be formed, which should not be rendered turbid nor yield any precipitate on the subsequent addition of an equal volume of stronger ether, otherwise an admixture with salts of other alkalies will be indicated. Calcium salts may be detected in the aqueous solution of lithium bromide by a white precipitate when tested with solution of am- monium oxalate. MeUdllc impurities may be recognized in the aqueous solution of the salt, acidulated with hydrochloric acid, by a dark colora- tion or a turbidity when saturated with hydrogen sulphide, or, after neutralization with ammonia-water, by the addition of ammo- nium sulphide. LITHII CAHBONAS. LITHIUM CARBONICUM. Carbonate of Litliium. Lithium Carbonate. Ger. Kohlensaures Lithium ; Fr. Carbonate delilliium ; Sp. Carbonato clelitina. Li,C03; 74. A white, amorphous, or indistinctly crystalline powder, perma- nent in the air, odorless, of an alkaline taste and reaction, and having a specific gravity of 2.11. When a small portion of the salt is heated on the looped end of a platinum-wiro, in the non- luminous flame, it fuses to a clear, colorless bead, and imparts to the flame a bright carmine-red color. Lithium carbonate is soluble in 130 parts of water at 15° C. (59° F.), and in about the same quantity of boiling water; it is more freely soluble in solutions of ammonium salts, and is readily dissolved by dilute acids, with copious evolution of carbon di- oxide, but is insoluble in alcohol. If the solution of the salt in diluted hydrochloric acid be evaporated to dryness, the residue should be corapletelv soluble in three parts of absolute alcohol, afibrding a solution which, when ignited, burns with a crimson flame, and which is not precipitated by the addition of an equal volume of stronger ether (distinction from potassium and sodium chlorides); if the acid solution of the salt be neutralized by sodium hydrate, and a few drops of solution of sodium phosphate are subsequently added, and gently heated, a white, cr3'stalline precipitate of lithium phosphate, readily soluble in hydrochloric acid, will appear. Examination : Potassium unA Sodium Corlonnles. — The presence of these salts 27 418 MANUAL OF CHEMICAL ANALYSIS. may readily be ascertained by a greater solubility in water than that above indicated, as also by the above-described method, depending upon the solubility of lithium chloride in a mixture of alcohol and ether. Their presence may also be determined by the amount of acid required to exactly neutralize a definite amount of the salt : 0.74 part of lithium carbonate, when mixed with a warm solution of 1.26 parts of oxalic acid in 13 parts of water, should afford a clear and neutral solution ; or, 1 gram of lithium carbonate, if perfectly pure, should be exactly neutralized by 27.02 cubic centimeters of normal sulphuric acid. Potassium salts may be specially tested for, if desired, by dissolving a portion of the salt, in a test-tube, in an excess of solution of tartaric acid, and drawing a glass rod over the interior surface of thetube ; the gradual formation of a white, crystalline precipitate will reveal the presence of potas- sium salts. Sodium salts may also be further recognized by their property of imparting an intense yellow color to the non-lumi- nous flame, when a portion of the carbonate, moistened with hydrochloric acid, is heated on the looped end of a platinum-wire. Ammonhim salts may be recognized by the odor of ammonia, when a portion of the carbonate is heated, in a test-tube, with a concentrated solution of potassium or sodium hydrate. Calcium and maynesium salts, if present in the form of carbon- ates, will remain undissolved when the lithium carbonate is agi- tated with 150 times its weight of water ; they will also be indicated in the neutral solution of the salt (1: 150) in diluted hydrochloric acid by a white precipitate on the addition of an excess of sodium carbonate. The presence of calcium salts may be further detected in the aqueous solution of the lithium car- bonate, previously neutralized with hydrochloric acid, bv a white turbidity with ammonium oxalate; after filtration, if necessary, and the addition of ammonium chloride, ammonia-water, and solution of sodium phosphate, an ensuing white crystalline pre- cipitate will reveal the presence of magnesium. Sulphates and chlorides may be detected in the solution of the carbonate in diluted nitric acid, when tested, in separate portions, with barium and argentic nitrates respectively. Metallic impurities may be recognized in the solution of the salt in diluted hydrochloric acid by a dark coloration or a turbidity upon saturation with hydrogen sulphide, or, after neutralization with ammonia-water, by the subsequent addition of ammonium sulphide. LITHIUM. 419 LITHII CITRAS. LITHIUM CITRICUM. Citrate of Lithium. Litldum Citrate. Ger. Citi-onensaures Lithium ; Fr. Citrate de litliium; Sp. Citrato de litina. Li3CeHA; 210. A white, amorphous, deliquescent powder, possessing a sliglitly cooling and faintly alkaline taste, and neutral in its action upon litmus. When exposed to a red iieat, the salt chars, evolves inflammable vapors, and leaves a black residue of an alkaline reaction, which, when dissolved in a little alcohol, with one or two drops of hydrochloric acid, and ignited, imparts a crimson color to the flame. Lithium citrate is soluble in 5.5 parts of water at 15° C. (59° F.), and in 2.5 parts of boiling water, but is almost insoluble' in alcohol and ether. When the aqueous solution of the salt is completely precipitated with calcium chloride, the filtrate, when heated, will become turbid, and when filtered after cooling, and the filtrate reheated to boiling, it becomes turbid again (evidence of the presence of a citrate). Examination : The purity of lithium citrate may be approximately deter- mined by adding to 1 gram of the salt, previousl}^ dried at 120° C. (248° F.), and contained in a porcelain crucible, about 3 grams of concentrated sulphuric acid, and gently heating. After com- plete carbonization, the residue is strongly ignited at a red heat, and, after cooling, is weighed. The weight of the lithium sulphate thus obtained should not exceed 0.79 gram, and, when multiplied by 1.273, will indicate the corresponding amount of pure lithium citrate. Potassium salts are detected in the concentrated solution of the citrate, by a white, crystalline precipitate, upon the addition of a few drops of concentrated solution of sodium bitartrate. Sodium, salts are detected in the solution by a white precipitate when tested with potassium antimoniate, or by a persistent yellow color imparted to the non-luminous flame, when heated on the looped end of a platinum-wire. The presence of potassium and sodium salts may also be ascer- tained hy dissolving, in one or two drops of diluted hydrochloric acid, the residue of lithium carbonate obtained by incineration of the citrate; this solution is evaporated to dryness, and is subse- quently dissolved in a few drops of a mixture of equal parts of alcohol and ether ; a complete solution should result, as an insolu- ble residue would indicate potassiuru or sodium chlorides. Metallic impurities may be detected in the solution, acidulated -420 MANUAL OF CHEMICAL ANALYSIS. with hydrochloric acid, by a dark coloration or a turbidity upon saturation "with hydrogen sulphide, or, after neutralization with am- monia-water, by the subsequent addition of ammouium sulphide. LITHII SALICYLAS. LITHIUM SAUCY LICUM. Salicylate of Lithium. Lithium Salicylate. Gcr. Salicylsauies Litliinm ; Fr. Salicylate de litliinm ; Sp. Salicilato de litina. 2LiC,H303.H,0 ; 306. A white powder, deliquescent on exposure to the air, and con- taining, for two molecules of the salt, one molecule (5.88 per cent.) of water. When strongly heated, the salt chars, emits inflamma- ble vapors, and leaves finally a blackened residue of an alkaline reaction. A small portion of the salt, when heated on the looped end of a platinum-wire in the non-luminous flame, imparts to the latter a bright carmine-red color. Lithium salicylate is very freely soluble in both water and alco- hol. Its aqueous solution possesses a sweetish taste, and a faintly acid reaction, and yields, upon supersaturation with hydrochloric acid, a bulky white precipitate of salicylic acid, which is soluble in boiling water, and from which it recrystallizes on cooling; the precipitate is also readily soluble in alcohol and ether, and the solutions assume, on the addition of a drop of solution of ferric chloride, an intense violet color. Examination ; Organic impurities may, in most cases, be detected by agitating 1 part of the salt with about 15 parts. of concentrated sulphuric acid, when no color should be imparted to the acid within 15 minutes ; an ensuing dark coloration would indicate the presence of foreign organic substances. Carhonate will be indicated by effervescence, when a small por- tion of the salt is added to diluted hydrochloric or acetic acid. Potassium and sodium salts may be recognized by igniting a portion of the lithium salicylate at a red heat, dissolving the resi- due in diluted hydrochloric acid, and evaporating the clear, fil- tered solution to dryness. The residue of lithium chloride thus obtained should be completely soluble in 3 parts of stronger alco- hol, affording a solution, which, when ignited, burns with a crim- son flame, and the transparency of which is not disturbed by the subsequent addition of an equal volume of stronger ether; if an insoluble residue remains, the presence of potassium or sodium salts or other impurities will be indicated. Metallic ifvpurities may be detected in the aqueous solution of MAGNESIUM. 421 the salt, acidulated with hydrochloric acid, by a dark coloration or a turbidity upon saturation with hydrogen sulphide, or, after neutralization with ammonia-water, by the subsequent addition of ammonium sulphide. MAGNESIA. MAGNESIA USTA. MAGNESII OXIDUM. MAGNESIUM OXYDATUM. Magnesia. Calcined Magnesia. Magnesium Oxide. Ger. Gebrannte Magnesia ; Fr. Magaesie calciaee ; Sp. Magaesia calcinada. MgO; 40. A white, inodorous, bulky, more or less lis;ht powder,* of an earthy, but not saline taste, and a slightly alkaline reaction upon moistened red litmus-paper; when exposed to a moderate heat, it suffers no change, but at very high temperatures it is rendered more dense, loses its property of combining with water, and is much more slowly soluble in acids. Magnesia is almost insoluble in water, requiring 55,368 parts of the latter for solution, but is much more soluble in solutions of various salts, particularly the ammonium salts; it is insoluble in alcohol. If one part of magnesia be stirred, in a beaker, with 15 parts of water, and the mixture allowed to stand for about half an hour, it readily unites with the water with the formation of a gelatinous hydrate, which is of sufficient firmness to prevent it from falling out when the glass is inverted, and gradually absorbs carbonic acid by exposure to the air. When magnesia is dissolved in diluted sulphuric acid, it affords a solution which, after the addition of ammonium chloride and supersaturation with ammonia-water, yields a white, crystalline precipitate on the addi- tion of solution of sodium phosphate. Examination : When triturated with hot water, and the mixture poured into an excess of dilute sulphuric acid, magnesia must dissolve with- out effervescence (evidence of the absence o? carhonate), and must form a clear solution (evidence of the absence of calcium, barium, and strontium oxides) ; this solution may be divided into two portions, one of which is saturated with hydrogen sulphide, and after filtration, if necessary, and neutralization with ammonia- water, tested with ammonium sulphide; a dark coloration or a turbidity in either instance will indicate the presence of metallic * In the U. S. Pharmacopoeia magnesia is oScinal in two forms, as Magne- sia, or light magnesia, and Magnesia Ponderosa, or heavy magnesia, which differ in theit densities, but correspond in all their other properties and reactions. 422 MANUAL OF CHEMICAL ANALYSIS, impurities ; the remaining portion of the solution, after the addi- tion of a little ammonium chloride and ammonia-water, is tested with ammonium oxalate, when a white precipitate will reveal the presence of calcium. Another portion of the magnesia may be dissolved in dilute nitric acid, and the solution tested, in separate portions with argentic nitrate for chlorides, and with barium nitrate or chloride for sulphates. Magnesia is liable to contain the impurities of the magnesium carbonate from which it has been obtained, and may be further examined for them, if they have not been ascertained by the preceding tests for identity and purity, by the methods described on page 423. MAGNESII CARBONAS. MAGNESIUM CARBONICUM. MAGNESIA ALBA. Carbonate of ^fagnesium. Magnesium Carbonate. Ger. Basisch kohlensaures Magnesium ; Fr. Carbonate de magnesie ; Sp. Carbonato de magnesia. (MgC03X.Mg(OH),-t-6H,0;* 522. White, bulky, pulverulent masses, commonly in square cakes, or a light, white powder, smooth to the touch, and nearly insolu- ble in water, but soluble with effervescence in dilute acids, yield- ing limpid, colorless solutions ; these, after the addition of a little solution of ammonium chloride, are not precipitated upon slight supersaturation with ammonia-water, but, upon the subsequent addition of sodium phosphate, afford a white crystalline precipi- tate of ammonio-magnesium phosphate. It is also soluble in solutions of the alkaline carbonates, potassium chloride, sulphate, and nitrate, borax, and particularly in solutions of ammonium salts, with the formation of soluble double salts. Magnesium carbonate is decomposed at a red heat, and also by all acids, and by the fixed alkaline hydrates. 100 parts of it, when ignited at a red heat until the weight remains constant, should leave a residue of magnesium oxide amounting to at least 40 parts. Examination : A small portion (about 1 gram) of the powdered magnesium carbonate is mixed and agitated with about 20 times its weight of warm water, and filtered ; the filtrate is tested with turmeric paper, and, if this becomes brown, alkaline carbonates are indicated ; when * The composition of magnesium carbonate differs somewhat according to the method of preparation. Althnugli the commercial article usually corre- sponds to the above formula, the amount of water varies between 4 and 6 mole- cules. MAGNESIUM. 423 a few drops of the filtrate are evaporated upon platiaum-foil, only a very slight residue should remain. The magnesiam carbonate left on the filter is rinsed into a flask, by means of a wash-bottle, the mixture warmed, and sulphuric acid added, drop by drop, until solution is effected; a remaining slight turbidity would indicate traces of silicic, acid. The sblution is filtered, if neces- sary, and saturated with hydrogen sulphide, when a dark colora- tion or precipitate v/'ill indicate lead or copper ; after filtration, if necessary, the liquid is rendered alkaline by the addition of am- monia-water ; an ensuing black precipitate would indicate salts of iron; a light reddish one, salts of manganese ; a white one, salts of aluminium or zinc (the incidental presence of phosphates would also give a white precipitate). In order to distinguish the latter, the precipitate is washed, subsequently dissolved in a little dilute hydrochloric acid, and, after gently heating to expel the hydrogen sulphide, the solution is supersaturated witli ammonia-water; the aluminium is thereby precipitated, while zinc remains in solution, and may be recognized by re-prccipitation with hydrogen sulphide or ammonium sulphide. The ammoniacal filtrate is then tested with a few drops of ammonium oxalate; a white precipitate, insoluble upon the addi- tion of ammonium chloride, would indicate salts o^ calcium. The latter may be further specially tested for, if required, by igniting a portion of the magnesium carbonate, extracting with water and filtering, and, after the addition of a little ammonium chloride and ammonia-water, testing the filtrate with ammonium oxalate. Chlorides and sulphates may be detected, in the diluted solution of the magnesium carbonate in diluted nitric acid, by testing the same in separate portions, with barium nitrate for sulphates, and with aro;entic nitrate for chloride. MAGNESII SULPHAS. MAGNESIUM SULFURICUM. Bpsom Salt. Sulphate of Magnesium. Magnesmm Sulphate. Ger. Schwefelsaures Magnesium, Bittersalz ; Fi'. Sulfate de magnesie ; Sp. Sulfate de magnesia. MgS0,-h7H,0; 246. Colorless, transparent, four-sided rhombic prisms (Fig. 136), but usually met with in commerce as small, acicular needles ; they con- tain seven molecules (51.22 per cent.) of water of crystallization, six of which are eliminated at 120° C. (248'^ F.), while the last molecule is not expelled at temperatures below 220^ 0. (428° F.); the crystals do not effloresce at common temperatures and in ordi- '%lIt«L 424 MANUAL OF CHEMICAL ANALYSIS. nary atmospheric humidity, but they do so slowly in warm, dry air. When heated, they lose their water of crystallization with- out previously undergoing aqueous fusion, and at a red heat undergo igneous fusion, with partial decom- FiG. 136. position. *^^^^^m Magnesium sulphate is soluble in 0.8 part of ^ ^331 waterat 15° 0.(59° F.), and in 0.15 part of boil- ^J ^' ; ing water, but is insoluble in alcohol ; its aque- ous solution has a nauseous, bitter taste, and is neutral in its action upon litmus; it is decom- posed, and gives white precipitates, with the lixed alkaline hydrates and carbonates, and also with the earth}' hydrates and their soluble salts; ammonia-water and ammonium carbonate, how- ever, do not at once cause a precipitate in dilute solutions of magnesium sulphate, or, if so, but a very slight one, since ammonium salts when present, or when formed by the neutralization of acidulous solutions, act as a solv- ent for magnesium hydrate or carbonate, and thereby retard or prevent their precipitation ; but, on the subsequent addition of phosphoric acid or solutions of tri-basic phosphates, a complete precipitation takes place, which precipitate, however, is soluble in dilute acids. The crystals of magnesium sulphate are isomorphous with those of zinc sulphate, and cannot be distinguished from them by the eye ; it is easy, however, to discriminate between them, not only by the difference in taste, but also by the action of a few drops of ammonium sulphide or solution of potassium ferrocyanide on their aqueous solutions; that of magnesium sulphate remains unaffected by these reagents, whereas solution of zinc sulphate yields, in either instance, a white precipitate. Examination : Metallic im.purities may be detected in the solution of the salt, acidulated with hydrochloric acid, by the occurrence of a turbidity or precipitate upon saturation with hydrogen sulphide (an ensuing white turbidity may be due simply to sulphur, a lemon-yellow one will indicate arsenic), and, after filtration, if necessary, and neutralization with ammonia- water, by the subsequent addition of ammonium sulphide; a white precipitate with the latter re- agent would ind cate zinc; when a dark precipitate is formed, both with the hydrogen sulphide and ammonium sulphide, cop- per and iron are indicated, and may be confirmed in the slightly acidulated solution of the salt, the former by a reddish-brown pre- cipitate, the latter by a blue one, with potassium ferrocyanide. Alkaline sulphates may be detected by triturating 2 parts of the magnesium sulphate with an equal weight of dry calcium hydrate (from which any free alkali must have been previously removed by washing with water, and again drying), and adding this mix- MAGNESIUM. 425 tare to a mixture of 10 parts of alcohol and 10 parts of water. The mixture is then allowed to stand for about two hours, with frequent agitation, when 40 parts of absolute alcohol are added, and, after active agitation, the mixture poured upon a filter which has been previously moistened with alcohol. If an alkaline sul- phate be present in the magnesium sulphate, it will be contained in the alcoholic filtrate in the form of hydrate, and may then readily be detected by its action upon turmeric paper ; if litmus paper be employed, the alcoholic liquid should be mixed with a little water, and the alcohol dissipated by the aid of heat before the application of the test. Ammonium salts may be detected by the odor of ammonia, when a little of the salt is heated, in a test-tube, with a strong solution of potassium hydrate, or by the development of white fumes when a glass rod, moistened with acetic acid, is held over the orifice of the tube. Aluminium and Calcium Salts. — The former may be detected in the solution of magnesium sulphate, to which a sufficient amount of ammonium chloride has been added, by the formation of a colorless, flocculent precipitate on the addition of ammonia- water; and the latter by a white precipitate on the addition of ammonium oxalate. Chlorides may be detected in the diluted solution of the salt, acidulated with nitric acid, by a white turbidity on the addition of solution of argentic nitrate. Estimation : One hundred parts of magnesium sulphate, dissolved in boiling water, and completely precipitated by a boiling solution of sodium carbonate, yield a precipitate which, Avhen washed, dried, and ignited at a red heat, weighs 16.26 parts. The quantitative estimation of magnesium in magnesium sul- phate is, however, usually effected by its precipitation as ammonio- magnesium phosphate, and the conversion of the latter, by ignition, into magnesium pyrophosphate ; from the weight of the latter, the amount of magnesium oxide, or the corresponding amount of crystallized magnesium sulphate may readily be calculated. To the aqueous solution of a weighed amount of the salt, ammonium chloride and ammonia- water are added, and subsequently solution of sodium phosphate until no further precipitate is produced ; the mixture is allowed to stand for ten or twelve hour.?, when the precipitate is collected upon a filter, washed with a mixture of about one part of ammonia-water and three parts of water, and, when dry, completely incinerated in a porcelain crucible. Of the residue of magnesium pyrophosphate, Mg^P^O,, thus obtained, 100 parts correspond to 36.03 parts of magnesium oxide, MgO, or 221.62 parts of crystallized magnesium sulphate, MgSO^-l-7HjO. 426 MANUAL OP CHEMICAL ANALYSIS. MAGS^NESII SULPHIS. MAGNESIUM SULFUROSUM. • Sulphite of Magnesium. Magnesium Sulphite. Ger. Schwefligsauves Masnesium ; Fr. Sulfite de magnesie; Sp. Sulfite de magnesia. MgS03 + 6H,0; 212. A white, crystalline powder, containing 6 molecules (50.94 per cent.) of water of crystallization ; it is odorless, but possesses a slightly bitter, somewhat sulphurous, taste, and a neutral or slightly alkaline reaction ; on exposure to the air, it gradually absorbs oxygen, and becomes converted into magnesium sulphate. When heated to 200° C. (392° F.), the salt loses its water of crys- tallization, and becomes decomposed, being converted into mag- nesium oxide and anhydrous magnesium sulphate. Magnesium sulphite is soluble in 20 parts of water at 15° C. (59° F.), and in 19 parts of boiling water ; it is insoluble in alcohol. The aqueous solution, when mixed with solution of ammonium chloride and ammonia-water, yields, upon the subsequent addition of solution of sodium phosphate, a white crystalline precipitate, which is insoluble in water or dilute ammonia-water, but readily soluble in acids. Magnesium sulphite is also completely soluble in 4 times its weight of dilute hydrochloric acid, with the development of the odor of burning sulphur, but without producing any turbidity (distinction from magnesium hyposulphite). A 1 per cent, aque- ous solution of the salt, strongly acidulated with hydrochloric acid, should not afford more than a slight cloudiness on the ad- dition of solution of barium chloride (absence of and distinction •from magnesium sulphate). MANGANI OXIDUM NIGRUM. M.VNGANUM HYPEROXYD.VTUM. MA.NG.1NESIUM: OXYD-ITUM NATIVUM. Black Oxide of Manganese. Pyrolusite. Manganese Dioxide. Gar. Mangansuperoxyd, Bvannstein ; Fr. Oxyde de manganese ; Sp. Per6xid() de manganese. MnO^; 86. Heavy, compact masses, of a dull-black or brownish-black, earthy appearance, or masses of acicular or rhombic crystals of a black, metallic lustre, and, if pure pyrolusite, of a spec. grav. of 4.9. In commerce, it occurs usually ground, as a coarse, dull, MANGANUM. 427 black powder, consisting of manganese dioxide, sesqui-oxide, and monoxide, and is contaminated with the gangue (quartz, felspar, barytes, limestone, etc.), which frequently amounts to 40 or 50 per cent. Manganese dioxide is infusible, permanent in the air, and in- soluble in water or alcohol. When exposed to a strong red heat, it loses one-third of its oxygen, and is converted into reddish- brown mangano-manganic oxide, Mn^O^ : 3Mn02= MUjO^-f O^. It is not attacked by cold concentrated sulphuric acid, but, upon heating with the latter, it is converted into manganoua sul- phate, with the evolution of oxygen : MnO^-f H^SO^ = MnSO^-t- n,o+o. If, however, oxalic acid, or other readily oxidizable organic substances are present, manganese dioxide is also dissolved by dilute sulphuric acid, with the evolution of carbon dioxide : MnO, + H,SO, + C,H,0, = MnSO, + 2C0, + 2H,0. When heated with hydrochloric acid, it is converted into man- ganous chloride, with the development of chlorine : MnO, + 4HC1 = MnCl^ -f 2H,0 -+- 01^. The resulting brownish solution, when filtered and neutralized with ammonia-water, yields, with hydrogen sulphide or ammo- nium sulphide, a flesh-colored precipitate of manganous sulphide ; the color of this precipitate is, however, frequently rendered darker, or even brownish-black, by the presence of oxides of iron and other metals. When a small portion of manganese dioxide is mixed with about an equal weight of potassium hydrate and a little potas- sium nitrate or chlorate, and the mixture heated to redness upon platinum-foil, it yields a dark green mass, which dissolves in water with a green color, changing to purple when the soh\tion is boiled or on the addition of dilute sulphuric acid. Examination : As manganese dioxide is frequently employed in connection with potassium chlorate for the generation of oxygen gas, its per- fect freedom from organic contaminations should be conclusively established, as the latter may give rise to violent and dangerous explosions. The presence of organic impurities in general may be determined by strongly heating a little of the powdered manga- nese dioxide in a glass tube, when no combustion should take place, nor should carbonic acid gas be evolved. Black antimonious sulphide, which, by accident or through care- lessness, may become mixed with or substituted for manganese dioxide, may be readily detected hy the development of the odor of hydrogen sulphide in contact with dilute ■ hydrochloric acid, and, after boiling with the latter, and filtering, by the production of an orange-colored precipitate upon saturation with hydrogen sulphide. 428 MANUAL OF CHEMICAL ANALYSIS. Fig. 137. Since, however, the value of commercial black oxide of manga- nese or pyrolusite, for most of its applications in the arts and trades, depends less upon the nature of its imparities than upon the percentage of real manganese dioxide, an examination of the mineral is invariably required before its ap- plication, and is mainly d rected to the deter- mination of the amount of dioxide. Among the several methods of conducting the assay, the two following are simple and accurate, the one being an approximate, the other a quantitative one : I. Five grams of the finely powdered black oxide of manganese are added, in a small flask (F.'g. 137), to a solution of 21 grams of crystallized or granular ferrous sulphate in 15 grams of water and 45 grams of hy- drochloric acid, and, when mixed by gentle ag'.tation, the whole is heated for a few- minutes to boiling ; after being allowed to cool, the liquid is filtered, and the filtrate subsequently tested with potass'um ferricyanide ; if it gives no blue precipitate, the test bears evidence that the pyrolusite contains at least 66 per cent, of real manganese dioxide ; if a blue precipitate is produced, the peroxide is wanting in that strength in proportion to the amount of the precipitate. II. Three grams of the black oxide of manganese, in fine pow- der, and previously dried at about 120° C. (248° F.), are care- fully introduced into the flask K' (Fig. 138) of the little apparatus described on page 86, into which previously has been poured suf- ficient of a mixture of 1 part of concentrated sulphuric acid and 2 parts of water to fill the flask Ifl |rfl to about one-third of its capacity. ' t| ' 1 Bi "^'^^ apparatus is then brought iVk. 't^ upon the balance, and, together f^ ] 1^^ ♦ j ^ with from 8 to 9 grams of pure y* fSr ft jj '-^ ^^ crystallized oxalic acid, is accu- ^^^ TJ Hte^+Mig^ g rately weighed. The oxalic acid ^^^ is then added to the mixture, being careful to avoid any loss, the cork carrying the tubes is adjusted, and the ensuing reaction effected by gentle agitation ; the flask K is charged with a little concentrated sulphuric acid, through which the evolved carbonic acid gas has to pass, and which absorbs and retains tlie moisture; gentle heat is applied to the flask K', as long as a brisk evolution of gas takes place ; the process is completed when this action and Fig. 138. MANGANUM. 429 the passage of gas-bubbles through the sulphuric acid both cease, and the black color of the mixture has changed to a more or less brown one ; the residual gas is then driven off, by momentary ebullition, and the apparatus again weighed. Every two mole- cules of carbonic acid evolved correspond to one molecule of manganese dioxide decomposed ; the molecular weight of the latter (87) being so nearly equal to twice that of carbonic acid (44), that the loss of weight suffered by the apparatus may be taken to represent the quantity of real manganese dioxide in the 3 grams of the sample employed ; and it has only to be divided by 3 and multiplied by 100 in order to express the percentage. MANGANI SULPHAS. MANGANUM SULFUEICUM. Sulpliate of Mavganese. Manganous SulpTiate. Ger. Scliwcfelsaiires Mangan ; Fr. Sulfate do manganese ; Sp. Sulfalo dc manganeso. MnS0, + 4H,0; 222. Colorless or, pale rose-colored ])rismatic crystals, occurring in three different forms, with different quantities of water of crys- tallization: (1) Monoclinic prisms (isomorphous with ferrous sul- phate), containing seven molecules of water of crystallization, and obtained when crystallized at a temperature below 6° 0.(42.8° F.); (2) Tn'clinic prisms (somorphous with cupric sulphate), contain- ing five molecules of water of crystallization, obtained when crystallized at a temperature between 7° and 20° C. (44.6° and 68° F.); and (3) Quadratic crystals or large monoclinic prisms, containing four molecules of water of crystallization, and obtained when crystallized between 20° and 30° C. (68° and 86° F.). The latter salt is the one commonly met with. The crystals are permanent in the air, though slightly efflorescent in air that is dry and warm ; they are soluble in 0.8 part of water at 15° C. (59° F.), and in 1 part of boiling water, but insoluble in alcohol ; the aqueous solution is neutral and colorless, or has, when con- centrated, a faint rose-color ; its taste is astringent, and it affords, with the alkaline hydrates and carbonates, white precipitates, of which those with the hydrates gradually become yellow, and finally dark-brown, by oxidation; ammon ura sulphide produces a flesh-colored precipitate soluble in dilute mineral acids, and also in acetic acid (distinction from zinc) ; tannic acid or tincture of nutgall does not act upon the solution ; potassium ferrocyanide pro- duces a reddish- white prec'pitate, and potassium ferricyanide a 430 MANUAL OF CHEMICAL ANALYSIS. brown one ; with barium nitrate or chloride it yields a white pre- cipitate, insoluble in hydrochloric acid. When a fragment of a crystal of manganous sulphate is heated with one or two drops of Solution of potassium hydrate and a little potassium chlorate or nitrate, upon platinum-foil, it yields a bluish-green fuse. Examination : Ferrous and cupric sulphates are detected, in the diluted solu- tion, acidulated with hydrochloric acid, the former by a blue precipitate with potassium ferrocyanide, the latter by a reddish- brown one with the same reagent, or a black one with hydrogen sulphide. Magnesium and alkaline sulphates may be detected by com- pletely precipitating the dilute solution of the salt with ammonium sulphide, and by testing part of the filtrate with sodium phos- phate ; a white, crystalline precipitate will indicate magnesium sulphate: if no reaction has taken place, another portion of the filtrate is evaporated in a porcelain capsule, and the residue heated to redness upon platinum-foil; a fixed remainder would indicate potassium or sodium salts. MORPHINA, MORPHIUM. MORPHINUM. Morphine. Morphia. Ger. Morphin ; Fr. Morphine ; Sp. Moi'fina. C^H^NO^.H.O; 303. Small, brilliant, prismatic crystals, transparent and colorless, or a white, crystalline powder, containing one molecule (5.94 per cent.) of water of crystallization. When heated to 120° C. (248° F.), the crystals lose their water of crystallization and become opaque, and, when cautiously further heated, they melt without decom- position, assuming a crystalline form on cooling ; at temperatures above 200° C. (392° F.), they become decomposed and blackened, and, when strongly heated on platinum-foil, they burn away, leav- ing a carbonaceous residue, which is wholly dissipated at a red heat. Morphine is but sparingly Soluble in cold water, requiring at 15° C. (59° F.) 1000 parts of the latter for solution, but is soluble in 500 parts of boiling water, in 100 parts of alcohol at 15° C. (59° F.), and in 36 parts of boiling alcohol; it is very sparingly soluble in ether and chloroform, and insoluble in benzol, petroleum benzin, and carbon bisulphide (distinction from narcotine and co- deine), but is quite readily soluble in hot amylic alcohol ; it dissolves MORPHINA. 431 freely in dilute acids, in the fixed alkaline hydrates, and in lime- water, but is almost insoluble in ammonia-water ; its alkaline solu- tions gradually absorb oxygen and become decomposed, acquiring thereby a brown color. The aqueous solution of morphine, and the alcoholic solution to a still greater extent, possess a bitter taste and an alkaline reaction. A solution of morphine in acidulated water, if not too dilute, affords upon the addition of a solution of potassium or sodium hydrate, ammonia-water, sodium carbonate or bicarbonate, a white crystalline precipitate of morphine, which, however, is readily soluble in an excess of potassium or sodium hydrate, but very sparingly soluble in ammonia-water; it is not precipitated by tan- nic acid, but affords a white precipitate with potassio-mercuric iodide, and a brown one with iodinized potassium iodide. In addition to the above described characters, morphine may be recognized and distinguished from all other alkaloids by the fol- lowing specific reactions and tests : Strong sulphuric acid dissolves morphine without coloration, but if the solution be quite strongly heated, and, after being allowed to cool, a drop of diluted nitric acid added, the liquid as- sumes a deep blood-red color ; if the solution in sulphuric acid, after heating and being again allowed to cool, be diluted with water, and a fragment of potassium bichromate added, an intense ma- hogany-brown color is produced. With concentrated nitric acid, morphine produces a blood red color, which gradually changes to yellow ; this coloration, however, is not changed to violet by the addition of stannous chloride or ammonium sulphide (distinction from brucine). If morphine or its salts be intimately mixed with about four times its we.ght of cane-sugar, and the mixture added to concentrated sulphurjc acid, a dark red coloration is produced ; if the amount of alkaloid be very small, the mixture will assume a wine-red or rose-red color. If to a trace of morphine or its salts a freshly prepared solution of molybdic acid or ammonium molybdate in concentrated sulphuric ac-d be added, a fine violet color is soon produced, which afterwards changes to blue, then to a dirty-green, and finally disappears ; by the addition of water the coloration is immediately destroyed. A particularly character- istic reaction of morphine or its salts, when free from other reducing substances, consists in adding a few drops of its solution to a solution of iodic acid, whereby iodine is liberated, imparting a yellowish or brownish color to the solution; if then a few drops of chloroform or carbon bisulphide be added, and agitated with the liquid, the iodine will be absorbed, with a fine violet or purple color; and by the employment of a few drops of mucilage of starch instead of chloroform or carbon bisulphide, a fine deep blue color will be produced. If morphine or a perfectly neutral solu- tion of one of its salts be brought in contact with a few drops of a diluted neutral solution of-farrjc chloride, a blue color is produced ; 432 MANUAL OF CHEMICAL ANALYSIS. this reaction is very characteristic, as being produced by no other alisaloid, but the color is destroyed or will not be produced in the presence of free acids or alcohol. If to a diluted solution of potassium ferricyanide a drop of a solution of ferric chloride be added, and subsequently a drop of a solution of morphine or its salts, a deep blue coloration or precipitate will be produced. Examination : Narcotine is indicated by a white, crystalline residue, left upon evaporating, on a watch-glass, a little pure ether which has been agitated with a small portion of the morphine. Inorganic impurities or admixtures may be detected by a fixed residue, upon complete incineration of a little of the morphine on platinum-toil, as well as by their insolubility, when a small por- tion of morphine is dissolved in about fifty times its weight of boiling alcohol. For the separation of morphine from other alkaloids or complex organic principles with which it may be associated, see page 111. MORPHINiE ACETAS. MORPHIUM SEU MORPHINUM ACETICUM. Acetate of Morphine or Morphia. MorpMne Acetate. Ger. Essigsanres Morpliin ; Fr. Acetate de morphine ; Sp. Acctato de morfiiia. C„H„N03.C,II,0,+ 3H,0 ; 399. A white or yellowish-white, indistinctly crystalline or amor- phous powder, having a faintly acetous odor, and containing 3 molecules (13.5 per cent.) of water. It gradually loses water and acetic acid on exposure to the air, and, when heated at 100° C. (212° F.), rapidly loses the entire amount of water, and acquires a brown color; when heated upon platinum-foil, it fuses, and is wholly dissipated at a red heat. It remains colorless when moist- ened with concentrated sulphuric acid, with the evolution of vapors of acetic acid, and dissolves in concentrated nitric acid, with a scarlet-red color. Morphine acetate, when freshly prepared, is soluble in 12 parts of water, and in 68 parts of alcohol at 15° C. (59° F.); when kept for some time, however, it requires, in consequence of the loss of acetic acid, a larger amount of water for complete solution, unless a few drops of acetic acid be added. It is also soluble in 1.5 parts of boiling water, in 60 parts of chloroform, and freely soluble in diluted acids, but is insoluble in ether and petroleum benzin ; it is decomposed by the action of boiling alcohol, and, upon the sub- sequent addition of water, a precipitate of morphine is produced. MORPHINA. 433 Its saturated aqueous solution has a bitter taste, and is neutral, or possesses but a slightly acid reaction ; it is rendered turbid by tannic acid, but becomes transparent again upon the addition of an excess of the reagent (evidence of the absence of narcotine) ; it is not permanently precipitated by potassium hydrate, when added in slight excess (distinction from most alkaloids), and assumes a greenish-blue color with a dilute neutral solution of ferric chloride. In its general behavior toward reagents, mor- phine acetate corresponds to the tests for morphine, as described under the latter, on page 431. Examination : Morphine acetate should be completely soluble in 40 parts of water, leaving at most but a slight residue, which should respond to the tests for pure morphine ; and when strongly heated on pla- tinum-foil should be completely dissipated. Sulphates and chlorides may be detected in the aqueous solution of the salt, acidulated with diluted nitric acid, when tested with barium nitrate or chloride for the former, and with argentic nitrate for the latter. MORPHINES HYDROCHLORAS. MORPHIUM SEU MORPHINUM HYDROCHLORICUM. MORPHIiE MURIAS. Bydrochlorate of Morphine or Morphia. Morpliine llydrochlorate. Ger. Chloiwasseistoffsaures MoipUin ; Fr. Chlorhydrate de morphine ; Sp. Hidioclorato de raorfina. C„H„N03.HC1 + 3H,0; 375.4. White, flexible, acicular crystals, of a silky lustre, or larger transparent prisms, containing 3 molecules (14.4 per cent.) of water of crystallization, and permanent in the air. When heated to 130° C. (266° F.), the salt loses its water of crystallization, and when heated upon platinum-foil, it first fuses, and afterwards, at a higher temperature, burns away without residue. Morphine bydrochlorate is soluble in 24 parts of water and in 63 parts of alcohol at 15° C. (59° F.) ; in about 0.5 part of boiling water and 31 parts of boiling alcohol ; and is also soluble in 20 parts of glycerin, but insoluble in ether. Its aqueous solution is neutral, has a bitter taste, and assumes a yellowish-red color upon the addition of strong nitric acid, and a bluish one with a dilute neutral solution of ferric chloride ; it affords no permanent turbidity with solution of potassium hydrate, when added in slight excess, but is precipitated by ammonia-water ; with tannic acid it affords a slight turbidity, which disappears on the addition of an excess of the reagent; and with argentic nitrate it gives a white, 28 434 MANUAL OF CHEMICAL ANALYSIS. curdy precipitate, insoluble in nitric acid, but soluble in ammonia- water, which solution, when heated in a test-tube, separates metallic silver. "When a little dry morphine hydrochlorate is added to a mix- ture of two parts of concentrated sulphuric acid and one part of water, in a small test-tube, no change of color of the liquid takes place, either at common temperatures, or when gently warmed by immersing the test-tube in hot water (evidence of the absence of salicin and other bitter substances); when this liquid is divided into two portions, and one drop of strong nitric acid is added to the one part, a red coloration occurs, and on adding a trace of potassium bichromate to the other part, only a slight yellowish- green coloration takes place. Morphine hydrochlorate dissolves in chlorine-water, with a yellowish color, which becomes brown upon the addition of am- .monia-water (distinction from quinine, which yields an emerald- green color). In its general behavior toward re-agents, mor- phine hydrochlorate corresponds to the tests for morphine, as described under the latter, on page 431. MORPHIN.a! SULPHAS. MOEPHIUM SEU MORPHIZSrUM SULFUEICUM. Sulpliate of Morphine or Morphia. Morphine Sulphate. Ger. Schwefelsauies Morphin ; Fr. Sulfate de morpliine ; Sp. Sulfate de morfina. (C„H„N03),H,SO, + oH,0; 758. White, fasciculate, feathery crystals, of a silky lustre, contain- ing 5 molecules (11.87 per cent.) of water of crystallization, and permanent in the air. When heated to 130° G. (266° F.), the salt loses its water of crystallization, and, when strongly heated on platinum-foil, burns entirely away without residue. Morphine sulphate is soluble in 24 parts of water and in 702 parts of alcohol at 15° C. (59° ]?.), and in about 0.5 part of boiling water and 31 parts of boiling alcohol (distinction from quinine sulphate) ; it is almost insoluble in ether and in chloroform. Its aqueous solution is neutral and very bitter ; it gives no perma- nent precipitate with potassium hydrate when added in slight excess, but yields with ammonia-water and the alkaline carbonates and bicarbonates a white crystalline precipitate of morphine. It affords a blue color Avith a dilute, neutral solution of ferric chlo- ride, and a .white precipitate, insoluble in acids, with barium chloride. 3lQrphine sulphate, dissolves in strong sulphuric acid without MORPHINA. 435 coloration, even when gently warmed by dipping the test-tube in warm water (evidence of the absence of salicin and other bitter glucosides) ; it dissolves in concentrated nitric acid with a yellow- ish-red coloration (distinction from quinine). When dissolved in a little chlorine-water, morphine sulphate yields a greenish -yellow solution, which becomes dark-brown upon the addition of ammo- nia-water (farther distinction from quinine, which yields an emerald-green color). In its general behavior toward reagents, morphine sulphate corresponds to the tests for morphine, as de- scribed under the latter on page 431. Examination : Sodium sulphate, which has been found to occur as an adulterant of morphine sulphate, may be detected, as well as other inorganic salts, by a non-volatile residue, when a little of the morphine sulphate is strongly heated on platinum-foil. Ammonium salts may be recognized by the odor of ammonia, when a little of the salt is heated, in a test-tube, with a strong solution of potassium hydrate ; and by the formation of white fumes, when a glass rod, moistened with acetic acid, is held over the orifice of the tube. Morphiometric Assay of Opium : Since the therapeutical and commercial value of opium mainlv depends upon the quantity of morphine which it contains, an ex- amination of opium is invariably required before its introduction into the market or its application for the manufacture of the opium alkaloids, or for medication. Among the various methods for the estimation of the morphine strength of opium, the follow- ing are simple in execution, require comparatively little time, and render approximately correct results. I. Fliickiijer's Process. — Eight grams of powdered air-dry opium are digested for twelve hours, with frequent agitat'on, with 80 grams of cold water, and subsequently filtered. 42.5 grams of the filtrate (representing the soluble matter of one-half of the opium employed) are then brought into a tared flask, and to the solution 12 grams of alcohol, of about 0.820 spec, grav., and 10 grams of ether are added, whereby no turbidity should ensue ; a portion of the ether forming a colorless layer on the surface of the mixture. 1.5 grams of ammonia- water, spec. grav. 0.960, are then added, and, after thorough agitation, the mixture allowed to repose for 24 hours, when the morphine will be deposited in white crystals. The crystals of the alkaloid are afterwards col- lected on a folded double filter having a diameter of about 10 centimeters (four inches), the flask rinsed with 10 grams of a mixture of equal parts of alcohol and ether, and finally with 10 grams of pure ether, and these liquids gradually poured on the crystals of morphine in order to wash them. The crystals are subsequently cautiously pressed between the folds of the two filters, which will almost completely absorb the mother liquor 436 MAKUAL OF CHEMICAL ANALYSIS. which the crystals of morphine may still retain. The alkaloid may now readily be removed from the filter, and having been brought into the tared flask, which may still contain a few crys- tals of morphine attached to its sides, the whole is dried at 100° C. (212° F:), and its weight determined. From the weight of the alkaloid, which, at 100° C. (212° F.), corresponds to the formula C„H,gN03+H20, the percentage of morphine may be calculated. As by the above method a small amount of morphine remains dissolved in the liquid from which it has separated, the error which would thereby be occasioned may be eliminated by adding 0.088 gram to the amount of alkaloid obtained. As a test for the purity of the crystals obtained, they should,' although slowly, be completely soluble in 100 times their weight of officinal lime- water. An air-dried opium, of good quality, when submitted to the above method of examination, should yield from 0.40 to 0.48 gram of alkaloid, corresponding to from 10 to 12 per cent, of pure morphine. II. Squibb's Modification of Flucldgers Process. — Ten grams (154.32 grains) of commercial opium, in its moist or powdered condition, and representing the average quality of the specimen, are brought into a flask or wide-mouthed bottle of 120 cubic centimeters (4 fluidounces) capacity, which has been previously weighed and fitted with a good cork ; 100 cubic centimeters (3.3 fluidounces) of water are then added, and the mixture well shaken. It is then allowed to macerate over night, or for about twelve hours, with occasional shaking, and then, after shaking well, the magma is transferred to a filter of about 10 centimeters (4 inches) diameter, which has been placed in a funnel and well wetted. The solution is now filtered into a tared or marked vessel, and the residue on the filter percolated with water dropped on to the edges of the filter and the residue until the filtrate measures about 120 cubic centimeters (4 fluidounces), and this strong solution set aside. The residue is then returned to the flask or bottle by means of a very small spatula, without breaking or disturbing the filter in the funnel, 30 cubic centimeters (1 fluidounce) of water added, the mixture well shaken, and the magma returned to the filter. After being allowed to drain, the bottle is rinsed twice, each time with 10 cubic centimeters (0.33 fluidounce) of water, and the rinsings poured upon the residue. When this has passed through, the filter and residue are washed with 20 cubic centimeters (0.66 fluidounce) of water, applied drop by drop around the edges of the filter and upon the contents. This (120 + 70) 190 cubic centimeters (6.33 fluidounces) of total solu- tion will practically exhaust almost any sample of 10 grams of opium ; but occasionally a particularly rich opium, or one in coarse powder, or an originally moist opium which has by slow drying become hard and flinty, will require further exhaustion. MORPHTNA. 437 In all such cases, or cases of doubt, the residue should be again removed from the filter and shaken with 30 cubic centimeters (1 fluidounce) of water, and returned and again washed as before. The filter and residue are now dried at 100° 0. (212° F.) until they cease to lose weight ; and if any residue remains in the bot- tle, the bottle is also to be dried in an inverted position, and weighed. The weaker solution is then evaporated in a tared capsule of about 200 cubic centimeters (6.6 fluidounces) capacity, without a stirrer, on a water-bath, until reduced to about 20 grams (309 grains), the 120 cubic centimeters of stronger solution subsequently added, and the whole again evaporated to about 20 grams (309 grains). The capsule and contents are cooled, and, when cool, 5 cubic centimeters (0.17 fluidounce) of alcohol, spec, grav. 0.820, added, and the mixture stirred until a uniform solu- tion is obtained and no adhering extract remains undissolved on the capsule, If this solution should contain an appreciable pre- cipitate, it must be filtered, the filter carefully washed, and the filtrate evaporated to 25 or 30 grams. The concentrated solution from the capsule is poured into a tared flask of about 100 cubic centimeters (3.33 fluidounces) capacity, the capsule rinsed with about 5 cubic centimeters of water, used in successive portions, and the rinsings' added to the contents of the flask. If the solu- tion has not required filtering, then 5 cubic centimeters (0.17 fluidounce) more of alcohol are added; if it has been filtered and evaporated, 10 cubic centimeters (0.33 fluidounce) of alcohol are added and shaken well. Then 30 cubic centimeters (1 fluidounce) of ether are added, and again shaken well. Four cubic centi- meters (0.133 fluidounce) of ammonia-water, spec. grav. 0.960, are now added, the flask shaken vigorously until the crystals begin to separate, then set aside in a cool place for 12 hours, that the crystallization may be completed. The ethereal stratum is poured off from the flask, as closely as possible, on to a tared filter of about 10 centimeters (4: inches) diameter, which has been well wetted with ether, 20 cubic cen- timeters (0.66 fluidounce) of ether added to the contents of the flask, which is rinsed around without shaking, and the ethereal stratum again poured off as closely as possible on to the filter, keeping the funnel covered. When the ethereal solution has nearly all passed through, the edges and sides of the filter are washed with 5 cubic centimeters ("0.17 fluidounce) of ether, and the filter allowed to drain with the cover off. The remaining contents of the flask are then placed on the filter, and the funnel covered. When the liquid has nearly all passed through, the flask is rinsed twice with two portions of water of 5 cubic cen- timeters (0.17 fluidounce) each, pouring the rinsings with all the crystals that can be loosened on to the filter, the flask dried in an inverted or horizontal position, and, when thoroughly dried, weighed. The filter aud crystals are then washed with 10 cubic 438 MANUAL'.^Oi''' CHEMICAL ANALYSIS. centimeters (0.33 fluidounce) of water, applied drop hj drop to the edges of the, filter, and, when drained, the filter and con- tents removed fi-Jirh the funnel, the edges of the filter closed together, and the filter compressed gently between many folds of bibulous paper. It is then dried at 100° C. (212° F.) and weighed, the crystals of morphine removed from the filter, and the latter brushed off and reweighed, to get the tare to be subtracted. The remainder, added to the weight of the crystals in the flask, will give the total yield of morphine, in clean, distinct, small, light- brown crystals. As a test of purity for the obtained morphine, 0.1 gram of the finely powdered crystals should be completely soluble in 10 cubic centimeters of officinal lime-water. III. United States Pharmacopoeia Process. — Seven grams of opium (in any condition to be valued) are triturated, in a mortar, with 8 grams of freshly slaked lime and 20 cubic centimeters of distilled water, until a uniform mixture results, after which 50 cubic centimeters of distilled water are added, and the mixture stirred occasionally during half an hour. It is then filtered through a plaited filter, having a diameter of 75 to 90 millimeters (3 to 3.5 inches), into a wide mouthed bottle or stoppered flask (having a capacity of about 120 cubic centimeters and marked at 50 cubic centimeters) until the filtrate reaches this mark. To the filtered liquid (representing 5 grams of opium) 5 cubic centimeters of alcohol and 25 cubic centimeters of stronger -ateefeel are added, and, after shaking the mixture, 3 grams of ammonium chloride are added, the mixture again shaken well and frequently during half an hour, and then set aside for twelve hours. After coun- terpoising two small filters, one is placed within the other in a small funnel, and the ethereal layer decanted as completely as practicable upon the filter. Ten cubic centimeters of stronger ether are then added to the contents of the bottle and the mix- ture rotated, the ethereal layer again decanted upon the filter, - and the latter afterward washed with 5 cubic centimeters of stronger ether, added slowly and in small portions. The filter is now allowed to dry in the air, and the liquid in the bottle poured upon it, in portions, in such a way as to transfer the greater por- tion of the crystals to the filter. The bottle is then washed, and the remaining crystals transferred to the filter, with several small portions of distilled water, using not much more than 10 cubic centimeters in all, and distributing the portions evenly upon the filter. After allowing the filter to drain, it is dried, first by press- ing it between sheets of bibulous paper, and afterward at a tem- perature between 55 and 60° C. (131 to 140° F.). The crystals in the inner filter are now weighed, using the outer filter as a coun- terpoise. The weight of the crystals in grams, multiplied by 20, represents the percentage of morphine in the opium employed. The U. S. Pharmacopoeia directs that opium, in its normal, moist condition, should yield not less than 9 per cent, of mor- NICOTINA. 439 phine; and powdered opium not less thnui 12 nor more than 16 per cent, of morphine, when assayed by the above process. Morphiometric Assay of Tincture of Opium : When tincture of opium has to be examined for the quantity of morphine it contains, this may be ascertained by either of the folio wins; methods: I. To forty grams of the tincture (corresponding to 4 grams of powdered opium when prepared accordiug to the United States and German Pharmacopoeias), contained in a tared flask, 1.5 cubic centimeters of ammonia-water, spec. grav. 0.960, and 13 cubic centimeters of ether are added ; after being well mixed by agita- tion the mixture is allowed to repose for at least thirty-six hours, when the crystals of morphine may be collected and further treated as described under Fliickiger's morphiometric process on page 435. To the amount of alkaloid obtained from the stated amount of tincture, about 0.1 gram should be added, as representing approxi- mately the amount of morphine remaining dissolved in the liquid from which it laas been precipitated. The total weight of alka- loid should be not less than 0.48, nor more than 0.64 gram, indi- cating the employment of an opium containing not less than 12, nor more than 16 per cent, of morphine. II. One hundred and twenty cubic cantimeters (4 fluidounces) of the tincture, or other liquid preparations, are evaporated at a low temperature to 10 grams (155 grains), and the process then conducted exactly as described under SquibUs modified method of assay, on page 436, using, however, 5 cubic centimeters of alco- hol, instead of 10, and 2.5 to Scubic centimeters of ammonia-water, instead of 4 cubic centimeters. NICOTINA. NICOTINUM. Nicotine. Niootia. Ger. Niootin ; Fr. Nicotine ; Sp. Nicotina. C H "N" ■ 162 A colorless or nearly colorless, oily, and volatile liquid, having the specific gravity 1.027 at 15° 0. (59° F.), a pungent odor, re- sembling that of tobacco, and an acrid, burning taste. By expo- sure to the air, it becomes gradually brown and thick ; it begins to volatilize at 146° C. (294.8° F.), and boils in an atmosphere of hydrogen at from 240 to 242° 0. (464 to 467.6° F.); when heated on platinum-foil it volatilizes completely, forming irritating vapors, which readily take fire, and burn with a bright, sooty 440 MANUAL OF CHEMICAL ANALYSIS. flame. When dropped into concentrated sulphuric acid, it dis- solves, with a red color, and, when one drop of solution of potas- sium bichromate is added, the solution becomes brown, and subsequently green; when mixed with hydrochloric acid and cautiously warmed, a reddish-brown mixture is formed, which, by further evaporation and cooling, yields, upon the subsequent ad- dition of nitric acid, a violet coloration, gradually changing to orange. Nicotine produces white fumes with hydrochloric and acetic acids, precisely like ammonia-water ; it sinks when dropped into water (distinction from coniine, which floats), but is miscible with water in all proportions, and becomes again separated on the addition of solid potassium or sodium hydrate; it also dissolves in alcohol, ether, amylic alcohol, carbon bisulphide, chloroform, petroleum benzm, and in most of the fixed and volatile oils; its solutions have an alkaline reaction, and an acrid, burning taste ; they produce precipitates in solutions of neutral and basic plumbic acetate, cupric acetate, and many other metallic salts, and are pre- cipitated by solutions of tannic acid, potassio-mercuric iodide, iodinized potassium iodide, and auric and platinic chlorides, but the aqueous sokition aflbrds no precipitate with chlorine-water (additional distinction from coniine); the alcoholic solution should yield no turbidity with diluted sulphuric acid (evidence of the absence of ammonia). The aqueous solution of nicotine, when applied to the eye, causes the pupil alternately to dilate (mydri- asis) and to contract (stenocoriasis). By careful oxidation with concentrated nitric acid or potassium permanganate, nicotine is converted into nicotinic acid, C^H^NO^ (Pyridine-carbonic acid, CjH^N-COOH), which may be obtained from its silver salt by decomposing it with hydrogen sulphide. Nicotinic acid forms colorless, needle-shaped crystals, which are readily soluble in alcohol and in boiling water, but not in cold water or in ether; they melt at 225" C. (437° F.), and, when heated with soda-lime, yield the volatile organic base, pyridine, C,H^N. For the separation of nicotine from other alkaloids, or from complex organic mixtures with which it may be associated, see page 108. OLEUM AMYGDAL.5! iETHEREUM. OLEUM AMYGDALARUM AMARARUM ^THEREUM. Volatile Oil of Bitter Almond. Gcr. Bittevmandelol ; Fr Essence d'amaiides ameres ; Sp. Esencia de almendras araargas. A thin, colorless, or golden-yellow liquid, of great refractive power, and of the odor of bitter almonds. Exposed to the air, it OLEA. 441 rapidly absorbs oxygen, with the formation of crystals of benzoic acid ; its spec. grav. is from 1.060 to 1.070 at 15=' 0. (59° F.) ; or, after the removal of the hydrocyanic acid, 1.043 to 1.049; its boiling-point, 180° 0. (356° F.). When dropped into water, oil of bitter almonds sinks, but dis- solves upon shaking, unless too much oil has been used, about 300 parts of water being required for solution. When a few drops of solution of potassium hydrate are added to its aqueous solution, and afterward one or two drops of a solution of a ferrous and a ferric salt, and finally, after agitation, a slight excess of hydro- chloric acid, there will appear a blue coloration, and, after a while, a blue precipitate. Oil of bitter almonds is miscible, in all proportions, with alco- hol, ether, chloroform, carbon bisulphide, and essential and fatty oils; it is also soluble in concentrated nitric acid, without color, and without the evolution of nitrous fumes ; with au equal volume of concentrated sulphuric acid the mixture assumes a red color, which gradually increases in intensity, but remains limpid and clear. Oil of bitter almonds consists essentially of benz-aldehyde, or the aldehyde of benzoic acid, G„H,-COH, together with usually from 2 to 5 per cent, of hydrocyanic acid, which, in the process of distillation, combine to form a very unstable compound. From this compound the acid is gradually liberated, and becomes par- tially converted, by its decomposition, into ammonium cyanide and formic acid. The crude oil, obtained by distillation without further rectification, usually contains the largest proportion of hydrocyanic acid. Examination : Alcohol may be detected in oil of bitter almonds by agitating it with three times its volume of concentrated nitric acid, and sub- sequently warming the mixture by dipping the test-tube into hot water. No reaction takes place with pure oil ; but, if it has an admixture of more than three per cent, of alcohol, effervescence will? occur, with disengagement of yellowish nitrous vapors. Chloroform, as well as alcohol, can be detected by submitting a small portion of the oil to distillation from a water-bath, cooling the receiving test-tube in ice-water (Fig. 139). The boiling- point of the oil being at 180° C. (856° F.), only admixtures vola- tile at or below the boiling-point of water will distil, with but small traces of the constituents of the oil. The obtained distillate is mixed with a little iodine-water; if chloroform be present, and no alcohol, it will absorb the iodine, and separate, with a rose- color. The colorless, aqueous liquid is decanted, and then warmed by dipping the test-tube in warm water ; one drop of solution of iodinized potassium iodide is added, and then one drop of solu- tion of potassium hydrate, or sufficient nearly to decolorize the liquid. If alcohol be present, minute yellow crystals of iodoform 442 MANUAL OF CHEMICAL ANALYSIS. will be produced (Fig. 140), which, after subsidiog, in a conical glass, may be recognized by the examination of the sediment under the microscope. Fig. 140. Nitrohenzol may be detected by adding 10 drops of the oil to a mixture of 5 cubic centimeters of alcohol and an equal volume ol water, in a narrow test tube, closing the tube with the finger, and effecting the mix- ture by gently inverting the tube. If the oil is pure, a perfectly clear solution will at once be produced, whereas, if it contains but one per cent, of nitrohenzol, the liquid will appear turbid from the separation of oily drops, which, upon gentle agitation, aggregate, and are deposited at the bottom of the tube. Another reliable test consists in adding to a portion of the oil, in a test-tube, a few fragments of metallic zinc, and a little diluted sulphuric acid. After standing for a couple of hours, or until the evolution of gas has ceased, the aqueous liquid is filtered through a wet filter, and to the filtrate a fragment of potassium chlorate and a drop of con- centrated sulphuric acid are added ; no coloration should be thereby produced ; a violet color would indicate the presence of nitrobenzol through its reduction to aniline. Essential Oils. — Adulteration with cheaper essential oils, as well as with nitrobenzol, may be detected by the property of oil of bitter almonds to dissolve in a concentrated aqueous solution of sodium bisulphite when added drop by drop and agitated ; whereas such admixtures remain undissolved, floating upon the aqueous solution after dilution with a little tepid water. OLEA. 443 Estimation of the Available Quantity of Hydrooyauio Acid in Oil of Bitter Almonds : I. Five grams of the oil are mixed, in a beaker, with about 25 cubic centimeters of strong alcohol ; then about 200 cubic cen- timeters of water and a few drops of solution of sodium chjoride are added, and subsequently sufficient of a solution of potassium hydrate to render the liquid alkaline to test-paper. A decinormal solution of argentic nitrate (page 98) is then allowed to flow into the liquid from a burette until, with constant stirring, the pre- cipitate ceases to be re-dissolved, and therefore a slight permanent turbidity occurs. The number of cubic centimeters of argentic nitrate solution employed, multiplied by the decimal 0.0054, will represent the amount of hydrocyanic acid contained in 5 grams of the oil, and has only to be sub.sequently multiplied by 20 to express the percentage. II. Another method consists in adding to 1 gram of the oil, contained in a small flask, about five times its weight of strong- alcohol, subsequently 45 cubic centimeters of distilled water, and finally a solution of 1 gram of pure crystallized argentic nitrate in an excess of dilute ammonia-water. The mixture is well agi- tated for a few moments, and subsequently pure nitric acid added until it acquires a slight acid reaction. The precipitated argentic cyanide is then carefully collected on a tared filter, thoroughly washed, and finally dried at 100° C. (212° F.) until of constant weight. The weight of dry argentic cyanide, %vhen divided by 5, will represent the amount of hydrocyanic acid in 1 gram of the oil, and has, therefore, only to be subsequently multiplied by 100 in order to express the percentage. OLEUM SINAPIS .ffiTHEREUM. OLEUM SINAPIS VOLATILE. Volatile Oil of Mustard. Ger. JStherisches Seufol ; Fr. Hnile de moutarde ; Sp. Aceite eseiicial de mostaza. C.HjNS = (OS=N-C3H3); 99. A colorless or -pale-yellow liquid, of a most penetrating, pun- gent odor, and having the specific gravity 1.017 to 1.021 at 15° C. (59° F.) ; it boils at 148° C. (298.4° F.). When dropped into water, it sinks slowly, and dissolves in from 100 to 250 parts of it, the solubility of the oil in water apparently increasing with age ; if to the aqueous solution a few drops of solution of argentic nitrate be added, and heated, a black precipitate of argentic sul- phide will be produced. 444 MANUAL OF CHEMICAL ANALYSTS. Mustard oil is miscible witli alcohol, ether, chloroform, carbon bisulphide, and benzol, and with fatty and essential oils ; it suffers decomposition with concentrated nitric acid, with the evolution of nitrous vapors, and the formation of a resinous residue. When dropped into concentrated sulphuric acid, mustard oil dissolves, without color, and without the evolution of heat, and when mixed with concentrated sulphuric acid, in the proportion of one part of oil to three parts of acid, being careful that the mixture is kept cool, sulphurous acid is evolved, and, after twelve hours, a colorless or but slightly brown, thick liquid or crystalline mass is formed, devoid of the odor of mustard oil. If 2 parts of mustard oil, 1 part of alcohol, spec. grav. 0.830, and 7 parts of ammonia-water, spec. grav. 0.960, be digested for several hours at a temperature of about 40° C. (104° F.), and subsequently concentrated on the water-bath, it is converted into thiosinammine^ C^HgN^S : C^Hj-ONS + NH^ = C,H,N,S. The latter forma colorless and odorless, shining crystals, which possess a bitter taste, dissolve readily in water, alcohol, and ether, and fuse at 74° C. (165.2° F.). Examination : Admixtures of essential and fatty oils, carbon bisulphide, nitro- benzol, and alcohol, are indicated by becoming warm and dark- colored when about five or six drops of the oil are added to about 50 or 60 drops of concentrated sulphuric acid, in a dry test-tube ; this is particularly the case when a mixture of 3 parts of con- centrated sulphuric acid and one part of nitric acid is employed, being careful in the operation of mixing the acids to avoid eleva- tion of temperature. If an admixture of carbon bisulphide, chloroform, etc., is sus- pected, advantage may be taken of their relatively low boiling- points, and their separation from the mustard oil effected by distillation from the water-bath ; to the distillate the respective special tests of identity, as described on pages 302 and 309, may then be applied. Admixtures of alcohol, benzol, and other hydrocarbons, are also indicated when two or three drops of the oil are allowed to fall into a test-tube, about one-third filled with cold distilled water ; the oil should sink slowly to the bottom, remaining clear and transparent, until, after gently inclining the tube two or three times, it becomes opalescent. When contaminated with only a few per cent, of the above adulterations, the drops lose their transparency, and become opalescent, as soon as they fall into the water. Phenol (carbolic acid), gaultheria oil, and other similar bodies may readily be detected in the dilute alcoholic solution of the oil PHOSPHORUS. 445 by the production of a viokt color on the addition of a drop of solution of ferric chloride, whereas pure mustard oil remains unchanged. PHOSPHORUS. Plwspliorus. Ger. Phosphor ; Fr. Phosphore; Sp. F6sforo. P; 31. A translucent, slightly yellowish or nearly colorless solid, of a waxy lustre, and occurring usually in the form of cylindrical sticks. At ordinary temperatures it has about the consistence of wax, and may be easily cut with a knife, but at low temperatures is hard and brittle. It has a distinctive and disagreeable odor and taste, and the specific gravity 1.826 at 10° C. (50° F.); it melts at 44° 0. (111.2° F.), forming a colorless or slightly yellow, strongly refractive liquid, which has the specific gravity 1.764; it boils in an atmosphere free from oxygen at 290° C. (554° JF.), yielding a colorless vapor, but is slowly volatilized even at ordi- nary temperatures. Phosphorus is nearly insoluble in water, but dissolves in 350 parts of absolute alcohol at 15° C. (59° F.), in 240 parts of boiling- absolute alcohol, in 80 parts of ether, in about 50 parts of fatty oil, and very abundantly in carbon bisulphide ; the latter dis- solving twenty times its weight of the substance, forming a color- less solution, which, however, requires to be handled with the utmost caution, as a single drop of it, when allowed to fall upon paper, soon bursts into flame. When exposed to the air, phosphorus emits white fumes, which are luminous in the dark, and have an odor somewhat resembling that of garlic; it is very inflammable, and must, tlierefore, be preserved under water in a cool place. It possesses strongly re- ducing properties, separating many metals, copper, lead, silver, etc., from solutions of their salts; by the action of direct sunlight, or by heating to 250° C. (482° F.), it is principally converted into the red or amorphous modification, which, among other characters, is distinguished from ordinary phosphorus by its insolubility in carbon bisulphide and other solvents, its unalterability by expo- sure to the air at ordinary temperatures, and its non-luminous and non-poisonous properties. By treatment with nitric acid, phosphorus is converted into tri-basic or orthophosphoric acid. Examination : Arsenic and Sulphur. — Commercial phosphorus from its method of manufacture frequently contains small amounts of arsenic and 446 MANUAL OF CHEMICAL ANALYSIS. sulphur, which, however, should not be present to any consider- able extent. They may be recognized, and, if required, the amount quantitatively determined, by the following method. 1 part of phosphorus is digested with a mixture of from 6 to 8 parts of nitric acid and 6 parts of distilled water until it is completely dissolved. The solution is then evaporated until nitrous vapors cease to be evolved, subsequently diluted with water so as to weigh about 12 parts, and, being heated to about 70° C. (158° F.), hvdrogen sulphide passed through the liquid for about half an hour, and finally, after the removal of the heat, until the liquid cools. The liquid is then set as.de in a tightly corked flask for twenty-four hours, when any arsenic present, which should not be more than a trifling quantity, will become precipitated as yel- low arsenic trisulphide. If the amount of the latter is to be quantitatively determined, it may be collected on a tared filter, washed first with water, and, after drying, with pure carbon bisul- phide, in order to remove adhering sulphur, then dried at 100° C. (212° F.), and finally weighed: 100 parts of arsenic trisulphide, ASjS,, correspond to 61 parts of metallic arsenic. Or the arsenic trisulphide may be converted into arsenic acid, by treatment with hydrochloric acid and a little potassium chlorate on the water- bath, and, by the addition of test. magnesium mixture, precipitated as ammonio-magnesium arseniate; the latter, when collected on a tared filter, washed with dilute ammonia-water, and dried at 105° C.(221° F.), corresponds to the formula MgNH, AsO^ -1- IH^O, and of which 100 parts correspond to 39.47 parts of metallic arsenic. The filtrate from the original precipitate of arsenic trisulphide when tested with solution of barium chloride should not afibrd more than a slight opalescence ; a white precipitate, insoluble in hydrochloric acid, will reveal the presence of sulphur, .which, by tlie above treatment with nitric acid, becomes converted into sulphuric acid. Separation and Detection of Fhosphorus in Forensic Investiga- tions. — In consideration of the extensive application of phosphorus in the preparation of lucifer matches, and of its employment in the form of a paste for the destruction of vermin, it is occasionally the object of search in cases of accidental or criminal poisoning, and a convenient and reliable method for its isolation and detection will therefore be briefly described. The substance under examination, which may consist of some article of food, the contents of a stomach, vomited matters, etc., is first examined by its odor, which will frequently reveal the presence of phosphorus, when existing in the free state. As a preliminary test, the substance is then brought into a glass flask, provided with a tightly fitting cork, and a small strip of paper moistened with a solution of argentic nitrate suspended from the cork, so as to project slightly into the interior of the flask. Suf- PHOSPHORUS. 447 ficient water is tlien added to the mixture to form a tliin liquid, and also a little tartaric acid, in order to insure a distinctly acid reaction, after which the contents of the flask are very gently heated. If phosphorus be present, the paper moistened with the silver solution will become blackened, either immediately or after standing for a few hours, in consequence of the slight volatiliza- tion of the phosphorus and the formation of argentic phosphide. As, however, the material under exaniination might also contain putrefying matters, accompanied by the development of hydrogen sulphide, etc., which would likewise cause a blackening of the silver paper, the precaution should be observed to insert in the cork of the fiask, together with the silver paper, a small strip of paper moistened with a solution of pkimb'c acetate. If the latter remains unaffected, whilst the silver paper becomes blackened, the presence of phosphorus is rendered highly probable. In addition to the above-described preliminary test, the lumi- nosity of phosphorus in the dark affords the most striking and conclusive proof of its presence in the unoxidized state, and the substance should, therefore, invariably be further examined by the following method, which depends upon the volatilization of phosphorus with aqueous vapor, and the luminosity of the vapor when observed in the dark. The material under examination, acidulated with tartaric acid, and contained in the flask A (Fig. 141), is gradually heated to the boiling-point of the liquid, and the vapors conducted by means of the bent glass tube, h, h, into the tube, d, d, of a glass condenser, B, which is maintained in a vertical position by the stative, D. The condenser is kept cool by a current of water flowing from a through the rubber tubing into the funnel-tube, c, and passing out through the rubber tubing, e, whilst the flask, C, serves for the reception of the distillate. In the presence of ordinary phosphorus, and by conducting the distillation in a dark room, a luminous ring, which remains visible for a considerable time, will be observable in the cooled portions of the tube, d, d, while if considerable phosphorus be present, small particles of the latter will also frequently be found in the distillate. It should, however, be considered that the presence of alcohol and ether, as also of volatile oils, retard or prevent the luminosity of the vapor, but, as soon as these are volatilized, the characteristic reaction may at once be observed. If a quantita- tive determination of the phosphorus be required, the distillate, together with any particles of suspended phosphorus which it may contain, is mixed with a sufficient amount of good chlorine-water, and, after being allowed to stand for about twelve hours, evapo- rated to a small volume upon the water-bath. The phosphorous acid of the distillate is thereby converted into phosphoric acid, and, after supersaturation with ammonia-water, may be precipi- tated by test magnesium mixture as ammonio-magnesium phos- 448 MANUAL OF CHKMICAL ANALYSIS. plaate ; the latter is then collected upon a filter, washed with a little dilute ammonia-water, dried, and by ignition in a small porcelain crucible, converted into magnesium pyrophosphate. Fig. 141. MgjPjO,, and its weight finally determined : 100 parts of the latter compound correspond to 27.92 parts of phosphorus. If in the above-described method for the detection of phos- phorus it should also be necessary or desirable to take into con- sideration the possible presence of hydrocyanic acid, the same method of investigation may be pursued, reserving, however, the first portion of the distillate for examination for hydrocj'anic acid, as described on page 162, or for other readily volatile sub- stances by which it may be accompanied. The subsequent por- tion of the distillate may then be employed for the qualitative or quantitative determination of phosphorus, in the manner above described. PICROTOXINUM. 449 PHYSOSTIGMIN^ SALICYLAS. PHYSOSTIGMINUM SALICYLICUM. Salicylate of Physosiigmine. Physosiigmine Salicylate. Ger. Salicylsaurcs Pbysostigmin ; Fr. Salicylate de physostlgmine ; Sp. Salicilato de fisostigmina. 0,3H,.N3O,.C,H„O3; 413. Colorless or faintly yellowish, shining, acicular, or short colum- nar crystals, which by long exposure to air and light gradually assume a reddish color; when strongly heated on platinum-foil they are completely dissipated. Physostigmine salicylate is soluble in 130 parts of water and in 12 parts of alcohol at 15° C. (59° F.) ; in 30 parts of boiling water, and very freely in boiling alcohol. The aqueous solution is neutral in its action upon litmus, and possesses a bitter taste ; it is precipitated by the ordinary alkaloidal reagents, is rendered turbid by iodine-water, and yields with a drop of a dilute solution of ferric chloride a violet coloration ; upon exposure to diffused light for one or two days it assumes a reddish color. The solu- tion of the salt in concentrated sulphuric acid is at first colorless, but afterwards assumes a yellow color. If sodium bicarbonate be added to the aqueous solution of the salt, which is afterward shaken with ether, and the ethereal solution separated and allowed to evaporate spontaneously, an amorphous residue of physostig- mine is obtained ; the latter possesses a decidedly alkaline reaction, fuses at 45° C. (113° F.), and its aqueous solution, on exposure to the air, soon becomes red, or sometimes intensely blue, resulting from its partial decomposition; if sulphurous acid be added to such a solution, the color is discharged, but returns again on the evaporation of the acid. On concentrating the aqueous solution, which has been precipitated by sodium bicarbonate and shaken with ether, to a small volume, and supersaturating with sulphuric acid, a bulky white precipitate is obtained, which responds to the reactions of salicylic acid, page 181. A solution of physostigmine, or any of its salts, when applied to the eye, strongly contracts the pupil. PICROTOXINUM. Picrotoxin. Ger. Pikrotoxin ; Fr. Picrotoxine ; Sp. Picrotoxina. C,H,„0,; 182. Colorless, shining, prismatic crystals, which undergo no change bv exposure to the air; they are odorless, possess an intensely i!9 450 MANUAL OF CHEMICAL ANALYSIS. bitter taste, and are neutral in their action upon litmus. On being heated to about 200° C. (392° F.) the crystals melt to a yel- low liquid; when heated on platinum-foil they char, and at a strong heat are finally completely dissipated. Picrotoxin is soluble in 150 parts of water and 10 parts of alco- hol at 15° 0. (59° F.), in 25 parts of boiling water and 3 parts of boiling alcohol; the latter solution forming upon cooling a mass of silky prisms. It is also soluble in about 2.5 parts of ether, and readily in amylic alcohol and chloroform ; concentrated acetic acid likewise dissolves it, as do also the fixed alkalies and ammo- nia-water, and from the letter solutions it is precipitated unchanged on the addition of an acid. If a little picrotoxin be placed in a capsule and mixed with four or five drops of concentrated sulphuric acid, the crystals dissolve with a golden-yellow color, which changes to safi'ron-yellow ; on subsequently adding a trace of powdered potassium bichromate, a violet-green color is produced, and, upon dilution with water, a clear yellowish-green solution is formed. When a little picrotoxin is intimately mixed with 3 or 4 times its weight of potassium nitrate, and the mixture moistened with sulphuric acid, no change is observed, but on subsequently adding sufficient of a solution of potassium or sodium hydrate to impart a strongly alkaline reaction, it assumes an evanescent brick-red color. The aqueous solution of picrotoxin, to which a few drops of a dilute solution of potassium or sodium hydrate have been added, reduces an alkaline solution of cupric tartrate on warming; in this respect resembling a solution of grape-sugar and many other indifi'erent organic substances, although its reducing properties are inferior in extent. It also resembles a solution of grape- sugar in that its alkaline solution becomes decomposed on warm- ing ; the solution becoming at first yellow, and then brick-red. Picrotoxin being a perfectly neutral principle, and devoid of nitrogen, its solution is not affected by solutions of the salts of platinum, gold, and mercury, or by potassio-mercuric iodide, tan- nic acid, or other alkaloidal reagents, which thus distinguishes it from and indicates the absence of alkaloids. It is absorbed by ether from its acidulated aqueous solution, and may thus be sepa- rated from alkaloids and other complex organic principles with which it may be associated, as described on page 106. PIPERINA. 451 PILOCARPINE HTDROCHLORAS. PILOCARPINUM HYDROCHLOEICUM SEU MURIATICUM. Hydroolilorate of Pilocarpine. Pilocarpine HydrocUlorate. Ger. Salzsaures Pilocarpin ; Fr. Chlorhydrate de iDilocarpine ; Sp. Hidrocloralo de pilocarpina. C„H,„NA.HC1; 244.4. Small, colorless, deliquescent crystals, without odor, but pos- sessing a slightly bitter taste. When heated on platinum-foil they first melt, and at a strong heat are finally completely dissi- pated. Pilocarpine hydrochlorate is readily soluble in water and in alcohol, but almost insoluble in ether, chloroform, benzol, and carbon bisulphide. The aqueous solution is neutral in its action upon litmus, and possesses a slightlj^ bitter taste ; when slightly acidulated it is not precipitated by ammonia-water, and solution of sodium hydrate produces only in a concentrated solution of the salt a slight turbidity; with solution of argentic nitrate the aqueous solution yields a white precipitate, which is irisola- ble in nitric acid, but soluble in ammonia water. With concen- trated sulphuric acid the crystals of the salt yield a yellow, with nitric acid, spec. grav. 1.4, a faintly greenish-violet, and with sul- phuric acid and potassium bichromate an emerald-green color. An aqueous solution of pilocarpine, or any of its salts, when applied to the eye, strongly contracts the pupil. PIPERINA. Piperine. Ger. Piperin ; Fr. Pipeline ; Sp. Pipei-iua. C,,H„NO;,; 285. Colorless, or slightly yellowish, shining, four-sided prisms, be- longing to the rhombic system, and permanent in the air ; they ai-e neutral in their action upon litmus, odorless, and almost taste- less when first placed on the tongue, but by prolonged contact produce a sharp, biting sensation. When heated to about 128° C. (262° F.), they melt to a clear, yellowish liquid, which, on cool- ing, congeals to a resinous mass ; at a higher temperature they are decomposed, and, when strongly heated on platinum-foil, they take fire, and are finally completely dissipated. Piperine is almost insoluble in either cold or hot water ; it is .soluble in 30 parts of alcohol at 15" C. (59° F.\ in 1 part of boil- ing alcohol, and slightly soluble in ether, chloroform, benzol, and, the volatile oils. 452 MANUAL OF CHEMICAL ANALYSIS. Concentrated sulphuric acid dissolves piperine with a dark blood-red color, which disappears on dilution with water. When treated with cold concentrated nitric acid it assumes a greenish- yellow color, which rapidly changes to orange and red, and gradu- ally dissolves with a reddish color; on adding to this solution an excess of solution of potassium hydrate, the color is at first pale yellow, but, on boiling, it deepens to blood-red, while at the same time vapors of an alkaline reaction and of a peculiar odor (pipe- ridine)are given off. On heating with soda-lime, or by prolonged boiling with an alcoholic solution of potassium hydrate, piperin is converted, by the absorption of a molecule of water, inio piperi- di-ne, CjHjjN, and crystallizable piperic acid, C,jH,„0^: C„H,,NO, + H,0 = C,H„N + C„H,„0,. Piperidine is a clear colorless alkaloid, having the odor of pep- per and ammonia, and possessing strongly basic properties; it boils at 106° C. (222.8° F.), is soluble in all proportions in water and alcohol, and combines with acids to form well crystallizable salts. Piperine is a very feeble base, being almost insoluble in the dilute mineral acids, and not combining with thera, but form.s well crystallizable double salts with the chlorides of platinum, mercury, and cadmium. PLUMBI ACETAS. PLUMBUM ACETICUM. Acetate of Lead. Sv gar of Lead. Plumbic Acetate. Ger. Essigsaures Bleioxyd, Bleizuoker ; Fr. Acetate de plomb ; Sp. Acetate de plomo. Pb(C,H30,),-f3H,0; 378.5. Colorless, transparent, brilliant, monoclinic prisms or plates (F.g. 142), or, as generally met with, heavy, compact crystalline masses, somewhat resembling loaf-sugar, Fig. 142. having an acetous odor and a sweet, as- tringent, afterwards metallic taste ; they contain three molecules (14.21 per cent.) of water of crystallization, and effloresce slowly and absorb carbonic acid when exposed to the air ; they become black when in contact with gaseous or dissolved hydrogen sulphide. When heated to 40° C. (104° F.) plumbic acetate loses its water of crystallization quickly and completely ; it melts at 75° 0. (167° F.)in its water of crystallization, with the loss of water and acetic acid, and is further decomposed at a higher temperature, PLUMBUM. 453 leaving a black residae, which is reduced, at a red heat, to plum- bic oxide or to metallic .lead. Plumbic acetate is soluble in 1.8 parts of water and 8 parts of alcohol at 15° C. (59° P.), in 0.5 part of boiling water and 1 part of boiling alcohol, but insoluble in ether and in chloroform'; its solution in water has generally a slightly turbid appearance from traces of plumbic carbonate, which, however, disappears upon the addition of acetic acid ; the aqueous solution has a feeble acid reaction, forms white precipitates with the alkaline hydrates (soluble in excess of potassium and sodium hydrates), with the alkaline carbonate.s, and with sulphates and chlorides, a yellow one with iodides, and a black one with hydrogen sulphide and with sulphides. When completely precipitated by sodium chlo- ride, the colorless filtrate will assume a deep-red tint with a few drops of solution of ferric chloride. Examination : Salts of the Alkalies, Alkaline-Earths, and Zinc. — An aqueous solution of the salt is acidulated with hydrochloric acid, filtered, and the lead completely precipitated by saturation with hydrogen sulphide. The filtrate, on evaporation, should leave no residue. If a residue is obtained, it may be dissolved in water, and a por- tion of the solution tested with sodium carbonate, when a white precipitate will indicate the presence of salts of harium, calcium, magnesium, or zinc, which may be distinguished by the appro- priate tests; if the dissolved residue gives no precipitate with sodium carbonate, potassium or sodium salts will be indicated. Copper may be detected by precipitating a solution of the salt with dilute sulphuric acid, and testing the filtrate with potassium ferrocyanide, or, by subsequent supersaturation with ammonia- w.'iter, a reddish-brown precipitate in the first instance, aad a blue coloration of the liquid in the latter, will reveal the presence of copper. PLUMBI CARBONAS. PLUMBI SUB0A.RBONAS. PLUMBUM CARBONICUM. CERUSSA. Carbonate or Subcarbonate of Lead. Wliite Lead. Basic Plumbic Carbonate. Ger. Basisch kolilensaures Bleioxyd, Bleiweiss ; Ft. Carbonate de plomb ; Sp. Carboiiato de plomo. (PbG03), + Pb(OH), ; 773.5. A heavy, white, opaque, and perfectly amorphous powder, or friable lumps, which are blackened by hydrogen sulphide. Heated upon charcoal before the blow-pipe, plumbic carbonate becomes yellow, fuses, and is finally reduced to soft, malleable metallic glo- bules. It is insoluble in pure water, but somewhat soluble in 454 MANUAL OF CHEMICAL ANALYSIS. water containing much carbonic acid or alkaline bicarbonates ; it is wholly dissolved, with effervescence, by diluted acetic and nitric acids, affording colorless solutions, of a sweet, astringent taste ; these solutions yield white precipitates with dilute sul- phuric and hydrochloric acids, and with soluble sulphates and chlorides ; they also give a white precipitate with solutions of potassium or sodium hydrate, soluble in an excess of the precipi- tant, a yellow one with potassium iodide, and a black one with hydrogen sulphide. Examination : Admixtures of barium, calcium, and plumbic sxdphaies, remain behind, upon solution of the wiiite lead in dilute nitric acid. Their quantity may be ascertained by dissolving 100 parts of the sample in a sufficient quantity of warm diluted nitric acid, and collecting and washing the insoluble residue upon a tared filter ; when completely dry, the weight indicates the percentage of such admixtures. If the nature of the admixture has to be ascertained, the residue is intimately mixed with about three times its weight of anhy- drous sodium carbonate, and strongly heated in a porcelain cru- cible. After being allowed to cool, the fused mass is lixiviated with water, filtered, and the filtrate supersaturated with nitric acid and tested with barium chloride, when a white precipitate will reveal the presence oi stilphate. The residue, upon the filter, may then be dissolved in acetic acid, and tested with hydrogen sulphide for lead, when, after filtration, if necessary, the filtrd,te may be tested with potassium chromate for barium, and with ammonium oxalate for calcium. Admixtures of calcium carbonate or phosphate, barium, carbo- nate, and oxide of zinc, are also soluble in nitric acid. In order to detect and to distinguish them, the nitric-acid solution of the sample is freely diluted with water, and is subsequently saturated and completely precipitated with hydrogen sulphide ; it is then filtered, and warmed, to expel the excess of gas, and a small por- tion of the solution is supersaturated with sodium carbonate ; an ensuing white precipitate will confirm the presence of the above admixtures; in order to ascertain their nature, the remainder of the solution is nearly neutralized with a few drops of solution of potassium hydrate and then tested, in separate portions, with solu- tion of calcium sulphate for barium, with oxalic acid, after the previous addition of a little sodium acetate, for calcium, and by the addition first of sodium acetate and subsequentlj"- of ammo- nium sulphide for zinc. PLUMBUM. 455 PLUMBI lODIDUM. PLUMBUM lODATUM. Iodide of Lead. Plumbic Iodide. Ger. Jodblei ; Fr. lodure do plomb ; Sp. lodufo de plomo. Pbl^; 459.7. A. bright-yellow, heavy, inodorous powder, when obtained by precipitation ; or shining, golden-yellow, six-sided laminae or prisms of the hexagonal system, when allowed to slowly crystallize from its solutions. Its specific gravity is 6.1. When heated in a dry test-tube, plumbic iodide becomes red, and fuses to a thick reddish- brown liquid, which congeals, on cooling, to a yellow crystalline mass; at a stronger heat, it is decomposed, with the evolution of violet vapors ; and, when heated with exsiccated sodium carbo- nate, on charcoal, before the blow-pipe, it is entirely reduced to metallic globules. Plumbic iodide is soluble in 2270 parts of water at 14° 0. (57.2° F.), in 294 parts of boiling water, and also, to a slight extent, in alcohol; a hot saturated aqueous solution, on cooling, deposits the salt in brilliant yellow scales ; it is readily soluble in acetic acid, in solution of potassium or sodium hydrate, in concen- trated solutions of the alkaline or earthy iodides, in a warm solu- tion of ammonium chloride, and in solution of sodium hyposul- phite (thiosulphate), from all of which solutions hydrogen sulphide precipitates black plumbic sulphide. When shaken with chlorine- water, plumbic iodide suffers par- tial decomposition, and yields a filtrate from which chloroform or carbon bisulphide will extract iodine, with a red color. When boiled with solutions of alkaline carbonates, it is decomposed, with the formation of an alkaline iodide and plumbic carbonate. When boiled with granular or powdered zinc and water, less readily with iron, plumbic iodide is likewise decomposed, form- ing soluble zinc or ferrous iodide and metallic lead. Examination : Plumbic chromate, which, in its physical characters, bears some resemblance to plumbic iodide, may readily be distinguished from the latter by triturating 1 part of the salt with 2 parts of ammo- nium chloride, in a porcelain mortar, and subsequently adding 2 parts of water, when a complete and colorless solution should be formed. If the solution be afterwards diluted with water, and the lead completely precipitated by hydrogen sulphide, the fil- trate, on evaporation to dryness and subsequent ignition, should leave no residue, thus confirming the absence of other fixed impu- rities. 456 MANUAL OF CHEMICAL ANALYSIS. PLTTMBI NITRAS. PLUMBUM NITRICUM. Nitrate of Lead. Pbimbie Nitrate. Ger. Salpetersaiires Bleioxyd ; Fr. Azotate de plomb ; Sp. Nitrato de plomo. Pb(NO,),; 330.5. Colorless, transparent or opaque, anhydrous, octahedral crys- tals, permanent in the air. Heated in a dry test-tube, the crys- tals decrepitate, emit yellow nitrous vapors, and leave a residue of plumbic monoxide. When thrown on red-hot charcoal, the salt detonates with brilliant sparks, aud deflagrates when triturated with sulphur. Plumbic nitrate is soluble in 2 parts of water at 15° C. (59° F.), and in 0.8 part of boiling water; it is almost insoluble in alcohol. Its aqueous solution has a sweet, astringent, afterwards metallic taste, and an acid reaction ; it gives a white precipitate with sul- phuric or hydrochloric acid, and with solutions of sulphates or chlorides, a yellow one with potassium iodide, and a black one with hydrogen sulphide. When triturated with concentrated sul- phuric acid, and heated, the salt evolves red nitrous fumes. Examination : Salts of the Alkalies and Alkalive Earths. — An aqueous solution of the salt is acidulated with hydrochloric acid, filtered, and the lead completely precipitated by saturation with hydrogen sulphide. The filtrate, on evaporation, should leave no residue. If a residue is obtained, it may be dissolved in water, and a portion of the solution tested witli sodium carbonate ; an ensuing white precipi- tate would indicate the presence of SarmTO, which may be con- firmed by other tests. If the dissolved residue gives no precipi- tate with sodium carbonate, the presence of potassium or sodium salts will be indicated. Copper may be detected, in the aqueous solution of the salt, by completely precipitating it with dilute sulphuric acid, and testing the filtrate with potassium ferrocyanide, or, by subsequent super- .saturation with ammonia-water ; a reddish-brown precipitate in the first instance, and a blue coloration of the liquid in the latter, will reveal the presence of copper. PLUMBUM. 457 PLUMBI OXIDUM. PLUMBUM OXYUA.TUM FUSCUM. LITHARGYRUM. Oxide of Lead. Litharge. Plumbic Monoxide. Ger. Bleioxyd, Bleiglatte ; Fr. Litharge ; Sp. Litargirio. PbO; 222.5. A heavy, yellowish or reddish -yellow powder, or small, shining, rhombic scales of the same color, devoid of odor and taste. Its specific gravity is 9.36. It fuses at a red heat, assuming thereby a brownish-red tint, and solidifies on cooling to a crystalline mass; when heated on charcoal, before the blow-pipe, it is reduced to the metallic state. Plumbic monoxide is but sparingly soluble in water, imparting thereto a feeble alkaline reaction ; it is soluble in warm solutions of the fixed alkaline hydrates, and in diluted nitric and acetic acids,' without effervescence or residue ; it slowly absorbs carbonic acid from the atmosphere, and contains the more carbonate the longer it has been exposed to the air ; from this cause, when very old, it becomes more or less effervescent with acids. The nitric- acid solution of plumbic monoxide yields white precipitates with dilute sulphuric and hydrochloric acids, with solutions of sul- phates and chlorides, and with the alkaline hydrates, which latter, ammonia- water excepted, re-dissolve the precipitate, when added in excess ; it gives a black precipitate with hydrogen sulphide, and, when neutral, a yellow one with potassium iodide. Examination : Plumbic carbonate and red oxide are detected, when a small quantity of the litharge is triturated with a little water, and the mixture is added, drop by drop, to concentrated nitric acid, in a test-tube; carbonate is recognized by effervescence; red oxide by a brown residue, insoluble iii an excess of acid, with gentle warm- ing, but soluble upon the addition of a little oxalic acid or sugar; if this residue, however, does not dissolve, an adulteration with powdered silicates, crude ferric oxide, etc., is indicated. Silicates are also indicated by a white turbidity or a flocculent precipitate, occurring in the solution after the addition of the oxalic acid, in the preceding test. Zinc oxide and alkaline earths may be detected by saturating the dilute nitric acid solution with hydrogen sulphide, so as to completely precipitate the lead, and filtering; the filtrate, on evaporation, should leave no residue. If a residue is obtained, it may be dissolved in a little water, and a portion of the solution tested with sodium carbonate ; an ensuing white precipitate would indicate zinc, barium, or calcium oxides. In order to distinguish these, the remainder of the solution is tested, in separate portions, with ammonium sulphide for zinc, with solution of calcium sul- 458 MANUAL OF CHEMICAL ANALYSIS, phate ioT barium, and witla ammonium oxalate for calcium; an ensuing wliite precipitate in either instance will indicate the re- spective impurities. Copper may be detected by a blue coloration of the liq,uid, when the dilute nitric acid solution of the oxide is precipitated by sulphuric acid, and subsequently supersaturated with ammonia- water. Metallic lead may be detected by its remaining undissolved when the oxide is boiled for a short time with acetic acid, or when digested with a warm solution of plumbic acetate or potas- sium hydrate. It may likewise be detected by digesting a small portion of the litharge with a solution of plumbic nitrate, at a gentle heat, and with occasional agitation, for about half an hour ; a few drops of the decanted liquid are then diluted with a little water, a little mucilage of starch, and a few drops of dilute sulphuric acid and solution of potassium iodide added. If the sample contains even traces of metallic lead, this gives rise to the formation of plumbic nitrite, which will decompose the potassium iodide, with the liberation of iodine, and at once produce a blue color with the starch. PLUMBI OXIDTTM RUBRUM. PLUMBUM OXYDATUM EUBRUM. MINIUM. Bed Oxide of Lead. Minium. Triplumbic Tetroxide. Plumbic Plumbate. Ger. Rothes Bleioxyd, Meniiige ; Fr. Oxyde rouge de plomb ; 8p. Oxido rojo de plomo. PbjO,; 683.5. A heavy, orange-red, crystalline powder, which becomes dark when heated, but regains its original color on cooling ; at a red heat it loses oxygen and is converted into the monoxide. Heated upon charcoal, before the blow-pipe, it fuses, and is reduced to metallic globules. Its specific gravity varies from 8.6 to 9.1. Eed oxide of lead is almost completely soluble in twenty times its weight of warm glacial acetic acid, forming a colorless solu- tion, which is not precipitated by the addition of a mixture of ether and alcohol ; when treated with warm dilute nitric or acetic acid it only partially dissolves, leaving a brown residue of per- oxide, which is soluble, however, upon the addition of a little oxalic acid or sugar. A slight remaining turbidity, of a whitish appearance, is due to silicic acid, with which red oxide of lead is generally more or less contaminated ; any insoluble red or brown residue, however, would indicate impurities. POTASSIUM. 459 The impurities and admixtures which red oxide of lead is liable to contain, and the methods of detecting them, are the same as mentioned and described under litharge, on pages 457-458. POTASSA SULPHURATA. POTASSII SULPHURETUM. POTASSII SULPHIDUM. POTASSIUM SEU KALIUM SULPURATUM. HEPAR SULFURIS. Sulphurated Potassa. SulpJmret of Potassium. Potassium Sulphide. Ger. Scliwefelleber ; Fr. Sulfure de potasse ; Sp. Sulfuro de potasio. Solid, fused fragments, of a yellowish-brown color, when freshly- prepared or recently broken ; on exposure to the air they assume a greenish appearance, and finally become of a dirty white, in consequence of gradual decomposition by the action of atmos- pheric moisture and oxygen, the sulphides being successively converted, with the evolution of hydrogen sulphide, into hypo- sulphite (thiosulphate), sulphite, and ultimately sulphate. When moistened with acids, sulphurated potassa evolves hydrogen sul- phide. Sulphurated potassa, which is usually a variable mixture of higher potassium sulphides with hyposulphite (thiosulphate), sul- phite, and sulphate, and with undecomposed carbonate, is soluble in about 2 parts of water at 15° 0. (59° F.), and is also soluble in alcohol, leaving behind in the latter case the oxygen salts ; these solutions have an orange-yellow color, a nauseous, alkaline, bitter taste, and the odor of hydrogen sulphide, which is abundantly evolved, with the separation of sulphur, upon the addition of acids; they precipitate metallic sulphides from the solutions of most of the metallic salts. If a solution of 1 part of the salt in 20 parts of water be boiled with an excess of acetic acid until hydrogen sulphide ceases to be evolved, the solutioQ filtered, and to the cold filtrate an excess of tartaric acid added, a white, crys- talline precipitate will be produced. The value of sulphurated potassa, when free from an undue proportion of carbonate, may be approximately estimated by the amount of crystallized cupric sulphate which is required to decompose it : CuS0,.5H,0 -f K,S3 = CuS -f S, -f K,SO, + bllf). In consideration of the amount of admissible foreign salts, the preparation should respond to the following test : 10 grams of the sulphurated potassa are triturated with 12.69 grams of crystallized cupric sulphate and 60 grams of water, and subsequently filtered; 460 MANUAL OF CHEMICAL ANALYSIS. the filtrate should be colorless, and afford no coloration or tur- bidity upon saturation with' hydrogen sulphide (indicating the presence of at least 56 per cent, of true potassium sulphide). FOTASSII ACETAS. POTASSIUM SEU KALIUjM: aceticum. Acetate of Potassium. Potassium Acetate. Ger. Essigsaures Kalium ; Fr. Acetate de potasse ; Sp. Aoetato de potasa. KC,H30,; 98. A snow- white, very deliquescent salt, of a foliaceous or fibrovis satiny appearance, or a white granular powder, unctuous to the touch, and of a warm, pungent, saline taste, and possessing a neu- tral or faintly alkaline reaction ; it fuses at 292" 0. (557.6° F.) without change, solidifying upon cooling to a crystalline mass, but is decomposed at a higher temperature with the evolution of empyreumatic, inflammable vapors, leaving behind a mixture of carbon and potassium carbonate. Potassium acetate is soluble in 0.4 part of water, in 2.5 parts of alcohol, and in 3 parts of glycerin at 15° 0. (59° F.) ; its dilute aqueous solution assumes a deep red color with one or two drops of solution of ferric chloride, and yields a white granular precipi- tate with a concentrated solution of sodium bitartrate or of tar- taric acid. Potassium acetate disengages the vapor of acetic acid with concentrated sulphuric acid, and the vapor of acetic ether when heated with a mixture consisting of eqaal parts of alcohol and sulphuric acid. Examination : Metals are detected in the aqueous solution, previously acidu- lated with hydrochloric acid, by a dark coloration or precipitate with hydrogen sulphide, or, after neutrali25ation with ammonia- water, by the addition of ammonium sulphide ; if a precipitate is produced by these reagents, a portion of the acidulated solution of the salt may then be tested with potassium ferrooyanide ; cop- per will be indicated by a reddish-brown coloration, iron by a blue one. Tartrates, sulphates, and chlorides are indicated by the occur- rence of a turbidity when a concentrated aqueous solution of the salt is dropped into strong or absolute alcohol ; the latter two are also recognized in the diluted solution, acidulated with nitric acid, by white precipitates when tested in separate portions with argentic nitrate and barium nitrate respectively. Carbonates, silica, and alkaline earths may be detected by dis- solving a portion of the salt in water acidulated with hydrochloric POTASSIUM. 461 acid ; effervescence will indicate carbonates ; upon evaporating the resulting solution to dryness, and treating the residue with water, the silica will remain undissolved ; and the solution, after iiltration, and the addition of sodium carbonate in slight excess, will yield a white precipitate, if alkaline earths be present. Organic impurities will be indicated by a dark coloration when a little of the salt is strewn upon colorless concentrated sulphuric acid. Estimation : About 5 grams of the salt are accurately weighed, and ignited, at a strong heat, in a porcelain crucible, until inflammable vapors cease to be evolved ; the residue is then dissolved in water, and the solution, contained in a beaker, after the addition of a few drops of a solution of litmus, is titrated with a standard solution of oxalic or sulphuric acid (page 82) until, with the application of a gentle heat to effect the complete removal of the disengaged carbonic acid gas, a slight excess of acid has been employed, and the liquid assumes a bright cherry-red color. The excess of acid is then inversely titrated with a standard solution of potassium or sodium hydrate (page 87) until a decided blue coloration of the liquid is just produced, when the number of cubic centimeters of alkali solution, subtracted from that of the acid first eniployed, will give the amount of the latter required for the exact neu- tralization of the salt. One cubic centimeter of the normal acid solution corresponding to 0.069 gram of potassium carbonate, or, as its equivalent, 0.098 gram of potassium acetate, the latter deci- mal, multiplied by the number of cubic centimeters of the normal acid solution employed for neutralization, will represent the amount of pure potassium acetate in the quantity under esti- mation. By the employment of 4.9 grams of potassium acetate, and a strictly normal solution of oxalic or sulphuric acid, the number of cubic centimeters of acid required for the exact neutralization of the salt, after the above treatment, when multiplied by 2, will represent without further calculation the percentage purity of the salt under examination. The United States Pharmacopoeia requires that if 4.9 grams of potassium acetate are ignited until gases cease to be evolved, the alkaline residue should require, for complete neutralization, not less than 49 cubic centimeters of the volumetric solution of oxalic acid (corresponding to at least 98 per cent, of absolute potassium acetate). 462 MANUAL OF CHEMICAL ANALYSIS. POTASSII BICARBONAS. POTASSIUM SEU KALIUM BICARBONICUM Bicarbonate of Potassium. Potassium Bicarbonate. Hydrogen Potassium Carionate. Ger. Zweifach kohlensanrea Kiilium ; Fr. Bicarbonate de potasse ; Sp. Bicarbonato de potasa. KHOO3; 100. Transparent, colorless, prismatic crystals, belonging to tlie mono- clinic system, and having the specific gravity 2.153 ; they are per- manent in dry air, odorless, of a saline and slightly alkaline taste, and a feebly alkaline reaction ; when exposed to a red heat, they lose, in consequence of the elimination of water and carbonic acid gas, 81 per cent, of their weight, and are converted into the normal or neutral carbonate : 2KHCO3 = K^jCO, + B.f) + CO^. Potassium bicarbonate is soluble in 3.2 parts of water at 15° C. (59° F.), forming a slightly alkaline solution which effervesces with acids and evolves carbonic acid gas when heated to boiling; it gives a white granular precipitate with excess of tartaric acid, but no precipitate with magnesium sulphate unless when heated. It is almost insoluble in alcohol. Examination : Normal potassium or sodium carbonates will be indicated by a strongly alkaline reaction of the salt to test-paper, and may be detected in the cold aqueous solution by testing it, in separate portions, with a solution of magnesium sulphate and with mercuric chloride ; a white precipitate with the first-named reagent, solu- ble upon the addition of ammonium chloride, and a brick-red one with the second, would indicate neutral carbonate. They may also be detected by carefully mixing, without agitation, equal volumes of a solution of 1 part of potassium bicarbonate in 200 parts of water with a solution of 1.22 parts of crystallized barium chloride in 200 parts of water; the immediate formation of a white pre- cipitate will likewise reveal the presence of neutral carbonate. Other Impurities. — The aqueous solution is slightly supersatu- rated with diluted nitric acid, evaporated to dryness, and the dried mass re-dissolved in water ; a white insoluble residue would indi- cate silicates; the solution, if necessary, is -filtered, and tested in separate portions with argentic nitrate for chloride, and with barium nitrate for sulphate; a white turbidity with argentic nitrate, gradually turning dark, would indicate potassium hypo- sulphite (thiosulphate) ; in this case, as a confirmatory test, a small portion of the potassium bicarbonate may be dissolved in about five times its weight of water, the solution slightly supersatu- rated with acetic acid, and then a few drops of mucilage 01 starch, and subsequently of solution of iodinized potassium iodide are added, drop by drop ; the first drops of the latter reagent should POTASSIUM. 463 at once produce the blue coloration which will not take place immediately if potassium hyposulphite be present in the salt. Nitrates may be detected by dissolving a portion of the salt in cold concentrated sulphuric acid, and, after effervescence has ceased, carefully adding to the solution a concentrated solution of ferrous sulphate, so as to form two layers (Fig. 143); a dark Fig. 143. coloration at the surface of contact of the two liquids will reveal the presence of nitrates. Metals are detected by saturating a solution of the salt, pre- viously acidulated with hydrochloric acid, with hydrogen sul- phide, and, after the separation of any precipitate which may be thus formed, by the subsequent addition of ammonia-water and ammonium sulphide ; a dark coloration or precipitate in either instance would indicate the presence of metallic impurities, which may be further examined as to their character by the methods of systematic analysis, as described on pages 51 to 61. Estimation : One hundred parts of potassium bicarbonate require for exact neutralization 70 parts of citric, or 75 parts of tartaric, aoid. The quantitative estimation of the salt may, however, be more conveniently accomplished volumetrically, by dissolving 5 grams of the salt in a ■small quantity of water, and titrating the solution, contained in a beaker, after the addition of a few drops of litmus solution, with a standard solution of oxalic or sulphuric acid (page 82). The liquid, during the addition of the acid, should be gently warmed, in order to completely expel the disengaged carbonic acid gas, and a slight excess of acid employed, which will be evi- dent by the bright cherry-red tint of the liquid ; the excess of 464 MANUAL OF CHEMICAL ANALYSIS. acid being subsequently inversely titrated by means of a standard alkali solution (page 87). The number of cubic centimeters of normal acid which are thus required for the exact neutralization of 5 grams of the salt, when multiplied by 2, will represent the percentage purity of the salt under examination : One cubic centi- meter of the normal acid corresponding to 0.1 gram of pure crys- tallized potassium bicarbonate. FOTASSII BICHROMAS. POTASSIUM SEU KALIUM BICHKOMICUM. KALIUM CHROMIC UM KUBRUM. Bichromate of Potassium. Potassium Bichromate. Ger. Doppelt cliromsattres Kaliiim ; Fr. Bichromate de potasse ; Sp. Biciomato de potasa. K,Crp, 294.8. Pig. 144. Large, transparent, orange-red, prismatic, or tabular crystals, belonging to the triclinic system (Fig. 144), and having the spe- cific gravity 2.692 at 4° 0. (39.2° F.). They are anhydrous, and permanent in the air; ex- posed to heat, they fuse below redness, forming a dark-brown liquid, which solidifies on cooling to a crystalline mass, and are decomposed at a red heat with the evolution of oxygen, leaving a residue consisting of green chromic oxide and yellow potassium chromate, which may be separated by the ready solubility of the latter in water. Potassium bichromate is soluble in 10 parts of water at 15° C. (59° F.), and in 1.5 parts of boiling water, yielding an intensely orange- yellow solution, with a cooling, bitter, metallic taste, and an acid reaction ; it is insoluble in alcohol. The aque- ous solution becomes lemon-yellow with the alkaline hydrates and carbonates, and green or almost colorless, with the formation of a brown precipitate, when heated with reducing agents; it forms insoluble, colored bichromates and chromates with the solutions of most metallic salts. When the powdered salt is heated with hydrochloric acid, vapors of chlorine are evolved, and when heated with concentrated hydrochloric or sulphuric acid and a little alcohol, a vehement reduction takes place, and the liquid acquires a deep green color. A concentrated solution of the salt gives a white, granular precipitate with a concentrated solution of sodium bitartrate. POTASSIUM. 465 Examination ; Sulphate may be detected by heating to boiling a mixture of the aqueoas solution with an equal volume of concentrated hydro- chloric acid and a few drops of alcohol ; when subsequently diluted with water and tested with barium chloride, a white precipitate will ensue if sulphate be present. Chloride may be detected when the aqueous solution of the salt is mixed with about one-third of its volume of concentrated sul phuric acid, and when afterward a little alcohol is added; the mixture will become green, with spontaneous ebullition ; it is then heated, and subsequently diluted with water, and tested with argentic nitrate for chloride. POTASSIl BITARTRAS. POTASSIUM SEU KALIUM BITARTARICUM. TARTARUS DEPURATUS. .CREMOR TARTARI. Bitariraie of Potassium. Cream of Tartar. Potassium Bitartrate. Ger. Sanres weinsaures Kalium, Weinstein ; Fr. Tartrate acide de potasse ; Sp. Bitartrato de potasa KHC HO- CH(On)-CO-OK CH(OH)-CO-OH' ■^^"• White, semi-transparent, hard, prismatic crystals, belonging to the rhombic system, or aggregated groups of crystals, or a white, somewhat gritty powder, permaaent in the air, and having a spec, grav. of 1.967, a sour taste, and an acid reaction. When exposed to heat, in a porcelain crucible, potassium bitartrate is decom- posed, with the evolution of empyreumatic, inflammable vapors, leaving a black residue of carbon and pure potassium carbonate ; this residue, when dissolved in a little water, gives a filtrate which effervesces with acids, and forms a white, granular precipitate with an excess of tartaric acid. Potassium bitartrate is soluble in 210 parts of water at 15° C. (59° F.), and in 15 parts of boiling water, but is very sparingly soluble in alcohol, and insoluble in absolute alcohol and ether; it dissolves wholly and readily in mineral acids, as also in solu- tions of citric and oxalic acids, in dilute solutions of the alkaline hydrates and carbonates, of boracic acid, and of sodium biborate. If the aqueous solution of the salt be exactly neutralized with a solution of potassium hydrate, and a few drops of solution of argentic nitrate added, a white precipitate is produced, which becomes black on boiling. 30 466 MANUAL OF CHEMICAL ANALYSIS. Exanunation : Insolvhle admixtures (such as terra alia or white clay, and similar crude adulteranis) are indicated by a residue left when small samples of the powder are dissolved separately in a warm, diluted solution of potassium hydrate, and in dilute hydrochloric acid. Sulphates and chlorides are detected by agitating a small por- tion of the salt with about ten times its weight of warm water, and by testing portions of the clear liquid, when cool, and after the addition of a few drops of nitric acid, with barium nitrate for sulphates, and with argentic nitrate for chlorides. Alum.— An adulteration of powdered cream of tartar with alum is at once indicated by a greater solubility of the salt in water, by its intumescence upon incineration, and by the incom- plete solubility of the fused residue in water, as also by the odor of ammonia, and the production of white fumes from a glass rod, moistened with acetic acid, when the powder is heated with a solution of potassium, hydrate, and by the formation of a white precipitate, when a few drops of this alkaline solution are allowed to fall into a dilute solution of ammonium chloride. / Metallic impurities may be detected in the solution of the salt in ammonia-water, by a dark coloration or precipitate upon the addition of. ammonium sulphide. Calcium salts may be best detected when 1 gram of the salt is repeatedly agitated with 5 grams of acetic acid, at the ordinary temperature, during half an hour, the solution subsequently di- luted with 25 grams of water, filtered, and 8 drops of solution of ammonium oxalate are added ; a white turbidity, occurring either at once or within half a minute, will indicate the presence of more than 0.3 per cent, of such impurities. Estimation : The quantitative estimation of potassium bitartrate may readily be accomplished by its conversion into carbonate, and the estima- tion of the latter by means of a normal acid. 4.70 grams of the salt are ignited in a porcelain crucible, at a red heat, until gases cease to be evolved, and the residue subse- quently dissolved in water, and filtered; the solution, together with the washings from the filter, contained in a beaker, after the addition of a few drops of litmus solution, is then titrated with a standard solution of oxalic or sulphuric acid (page 82) until, with the application of a gentle heat to expel the disengaged carbonic acid gas, a slight excess of acid has been employed, and the liquid assumes a bright cherry-red tint ; the excess of acid is then in- versely titrated with a standard solution of potassium or sodium hydrate (page 87) until the liquid just assumes a permanent blue color. If the salt be perfectly pure, 25 cubic centimeters of the normal acid solution will be required for the exact neutraliza- tion of the quantity indicated, or, the percentage purity of the poTASsroM. 467 salt will be determined, when, for the neutralization of the above stated amount, the number of cubic centimeters of normal acid employed are multiplied by 4; one cubic centimeter of the nor- mal acid solution corresponding to 0.069 gram of potassium car- bonate, or, as its equivalent, 0.188 gram of potassium bitartrate. POTASSII BROMIDUM. POTASSIUM SEU KALIUM BROMATUM. Bromide of Potassium. Potassium Bromide. Ger. Bromkalium ; Fr. Brdmure de potassium ; Sp. Bromuro de potasio. KBr; 118.8. Anhydrous, colorless, semi-transparent, cubical crystals, some- times elongated into prisms, or flattened to plates, permanent in the air, and of a spec. grav. of 2.69 at 4° C. (39.2° F.) ; when ex- posed to heat, they decrepitate, and fuse at a little below a red heat, without decomposition. When a few grains are triturated and subsequently heated, in a dry tube, with a little potassium bisulphate, yellowish-red vapors of bromine are evolved. Potassium bromide is soluble in 1.6 parts of water and in 200 parts of alcohol at 15° C. (59° F.), in 1 part of boiling water, and in 16 parts of boiling alcohol ; its aqueous solution has a strong- saline taste, is neutral in its action upon litmus, and, when dropped into a very dilute solution of argentic nitrate, causes a yellowish- white, curdy precipitate, which is insoluble in dilute nitric acid, but soluble in a large excess of ammonia-water (distinction, in the latter instance, from argentic iodide); when dropped into a very dilute solution of mercuric chloride, no reaction takes place (addi- tional distinction from potassium iodide): it gives a white, granu- lar precipitate with a saturated solution of sodium bitartrate. Potassium bromide and its solution may also be distinguished from the iodide by adding to the solution a little mucilage of starch, and subsequently a few drops of chlorine-water ; the solu- tion of the bromide becomes light yellow ; that of the iodide will at once assume a deep-blue color. Examination : Moisture which may be contained in the crystals, as well as in the granular form of the salt, is recognized, and may be deter- mined, by the loss of weight when the salt is dried at 100° 0. (212° F.). Potassium carlonate is detected by a white turbidity occurring upon the addition of a little of the concentrated solution of the salt to lime-water, as also by a decided alkaline reaction, when a few fragments of the salt are placed upon moistened red litmus- paper. 468 MANUAL OF CHEMICAL ANALYSIS. Sulphates may be detected, in the aqueous solution, acidulated with a few drops of diluted nitric acid, by a white precipitate with barium nitrate. Potassium hrom.ate is detected by placing a little of the pow- dered salt upon a piece of white porcelain, and subsequently add- ing one drop of dilute sulphuric acid ; a yellow coloration of the moistened surface of the salt, or the developed odor of bromine, will reveal the presence of bromate. The presence of the latter, in an aqueous solution of the salt, may also be detected by the liberation of bromine upon the addition of a few drops of dilute sulphuric acid, imparting a yellow color, which, upon subsequent agitation of the solution with a few drops of carbon bisulphide, will be absorbed by the latter. Potassium and sodium chlorides are distinguished from potas- sium bromide, and may be recognized by adding a few drops of chlorine-water to the aqueous solution of the salt; if this is bro- mide, the mixture assumes at once a yellow color, which, how- ever, will be completely abstracted from the aqueous solution by chloroform, ether, or carbon bisulphide, when agitated therewith. This reaction does not take place with potassium or sodium chloride. If an admixture of potassium chloride, or other salts, be sus- pected, the purity of the sample may be ascertained by preparing a solution of 1 gram of the dry, crystallized salt in about 10 times its weight of water, acidulated with a few drops of diluted nitric acid, and completely precipitating it with a solution of argentic nitrate ; the precipitate is collected upon a moist, tared filter, is washed, dried, and, when completely dry, weighed. If the salt was pure potassium bromide, the obtained argentic bromide should weigh 1.58 grams; if it contained potassium or sodium chloride, the weight, provided the salt is free from other impuri- ties, will be greater in proportion to the amount of those admix- tures, since their molecular weights are lower; 1 gram of potas- sium chloride, for instance, would give 1.92 grams of argentic chloride. The same test may also be used to indicate the purity of the bromide, by ascertaining the quantity of argentic nitrate required to precipitate completely a certain weight of potassium bromide, 1 gram of which requires 1.-13 grams of argentic nitrate for pre- cipitation. The following additional methods for the detection of an ad- mixture of chlorides ma.j also be employed. A portion of the salt, dissolved in water, is completely precipitated by argentic nitrate, the washed and still moist precipitate digested for some time with a cold, saturated solution of ammonium carbonate, sub- sequently filtered, and the filtrate supersaturated with nitric acid ; the production of a white, curdy precipitate will reveal the pres- ence of chloride. POTASSIUM. 469 The presence of much smaller amounts of chloride, and less than that admitted in the officinal salt, may be detected as fol- lows: 5 grams of the powdered and well-dried salt, together with 6 grams of pure powdered potassium bichromate, are introduced into a small flask, and 15 grams of concentrated sulphuric acid are added. The mixture is then submitted to distillation at a gentle heat, and the distillate collected in a receiver or flask con- taining a small quantity of ammonia-water (¥'.g. 145). Bromine Fig. 145. distils over, and is dissolved by the ammonia- water without color; but, if chlorides are present, chlorochromic anhydride, CrOjClj, is produced, distils over, and forms ammonium ohromate, which imparts a yellowish color to the distillate ; by subsequently heat- ing the latter with a little hydrochloric acid and alcohol, the bright green color of the chromic salt will be produced. Nitrates may readily be detected, if the salt be free from bro- raate, by an ensuing intense yellow coloration, when a solution of a few fragments of the powdered salt in twenty times their weight of dilute sulphuric acid is heated to boiling. In the presence of bromate, nitrates will be indicated by the development of the odor of ammonia, when the salt, together with an equal weight of iron filings, zinc filings, and solid sodium or potassium hydrate, is gently heated, in a test-tube, with an equal volume of water. If, however, ammonium salts be originally present as an admixture, the ammonia must first be completely expelled, by heating a por- tion of the salt with a strong solution of potassium hydrate, after which, the iron and zinc filings may be added, and the test subse- quently performed for nitrates, as above described. Estimation : The estimation of potassium bromide, or the amount of chloride which may be contained therein, is most readily accomplished 470 MANUAL OF CHEMICAL ANALYSIS. volumetrically. Two grams of the potassium bromide, previously reduced to powder and carefully dried, are dissolved in water to the measure of 100 cubic centimeters. 10 cubic centimeters of this solution, corresponding to 0.2 gram of potassium bromide, are then brought into a beaiver, diluted with about 50 cubic centimeters of water, and, after the addition of a few drops of a solution of potas- sium chromate, the solution is titrated with a decinormal solution of argentic nitrate (page 98) until a permanent reddish-brown col- oration is produced. If the salt is pure potassium bromide, 16.8 cubic centimeters of the silver solution will be required to pro- duce this effect, as containing 0.2856 gram of argentic nitrate, which corresponds to 0.2 gram of potassium bromide, according to the equation AgNOj : KBr = 0.2856 : 0.2. If the salt was 170 119 pure potas.sium chloride, 26.84 cubic centimeters of the silver solution would be required for its complete precipitation, in ac- cordance with a similar proportion ; the difference in the amount of silver solution, required for 0.2 gram of the two salts, would therefore be 26.84 — 16.80 = 10.04 cubic centimeters ; from vrhich it follows, that for each 0.1004 cubic centimeter silver solution required in excess of 16.8 cubic centimeters, in order to effect complete precipitation, 1 per cent, of potassium chloride will be represented, as — ^-r- ~ 0-1004. It is evident, that the presence of potassium iodide, or other alkaline chlorides or bromides, Avould influence the result in proportion to the quantity of the admixture. The United States Pharmacopoeia directs that if 3 grams of the well-dried salt be dissolved in distilled water to make 100 cubic centimeters, and 10 cubic centimeters of this solution be treated with a few drops of test-solution of potassium bichromate, and then volumetric solution of argentic nitrate be added, not more than 25.7 cubic centimeters of the latter should be consumed before the red color ceases to disappear on stirring (indicating the absence of more than 3 per cent, of chloride). POTASSII CARBONAS CRUDUS. POTASSIUM SEU KALIUM CARBONICUM CRUDUM. Crude CarhonaU of Potassium. Pearlash. Ger. Uohes koUlensaures Kalium, Pottasche ; Fr. Potasse impure ; Sp. Potasa ordinaria. Wliite, bluish-white, or reddish-white masses (the color being dependent upon the presence of small amounts of potassium man- ganate or ferric oxide), or a coar.se granular powder intermingled POTASSIUM. 471 with smaller lumps, somewhat deliquescent, and of a burning, alkaline taste and strong alkaline reaction. Water extracts from pearlash the potassium carbonate and hydrate, and the soluble impurities, the greater part of the impurities remaining behind (sulphates, chlorides, silicates, phosphates, and carbonates of calcium and aluminium) ; the filtered solution effervesces with acids, and yields a white, granular precipitate with an excess of tartaric acid. The examination of pearlash consists in the determination of the quantity of soluble potassium carbonate aiad hydrate, or the available potassium oxide. Approximate Estimatioa : One hundred parts of commercial pearlash, when successively exhausted with about ten times its weight of Avarm water, afibrd a solution which should neutralize at least 58 parts of sulphuric acid of 1.843 spec. grav. Volumetric Estimation : The estimation of the amount of pure potassium carbonate in pearlash, when free from alkaline hydrates and sodium carbonate, is readily accomplished as follows. 34.5 grams of the pearlash are dissolved in water to the measure of 500 cubic centimeters. Of this solution, after the insoluble impurities have subsided and the liquid has become perfectly clear, 100 cubic centimeters (cor- responding to 6.9 grams of the pearlash) are brought into a beaker or small flask, and a few drops of litmus solution are added. A standard solution of oxalic or sulphuric acid (page 82) is then allowed to flow into the liquid from a burette, until an ex- cess of the acid has been employed, and the liquid, after being heated to boiling, in order to completely expel the liberated carbonic acid gas, assumes a cherry-red color. The excess of acid is then inversely titrated with a standard solution of potassium or sodium hydrate (page 87) until a permanent blue coloration of the liquid is pro- duced. From the amount of acid required for the exact neutral- ization of the quantity of pearlash employed, the amount of pure })otassium carbonate may be calculated : one cubic centimeter ot the normal acid solution corresponding to 0.0692 gram of potas- sium carbonate; or, the number of cubic centimeters of the acid solution, if strictly normal, which is required for the neutraliza- tion of the above amount of the salt, will indicate at once its per- centage purity iu potassium carbonate. If the pearlash contains potassium hydrate in addition to po- tassium carbonate, which will be indicated by an alkaline reaction of the solution of the salt after its complete precipitation by barium chloride and subsequent filtration, the hydrate will also be neutralized by the aoid, and the estimation of the amount of carbonate would therefore be incorrect. In the latter case, the amount of potassium hydrate and carbonate may be separately estimated according to the following method: 100 cubic centi- 472 MANUAL OF CHEMICAL ANALYSIS. meters of the above solution (corresponding to 6.9 grams of the pearlash) are mixed with an excess of a solution of barium chlo- ride, and to the unfiltered solution, containing the deposited barium carbonate, normal nitric acid is added from a burette, until a drop of the mixture no longer produces a brown stain upon turmeric paper. The number of cubic centimeters of the acid solution which are required to produce this reaction cor- responds to the amount of potassium hydrate in the pearlash: one- cubic centimeter of the normal nitric acid corresponding to 0.056 gram of potassium hydrate. Tlie entire mixture, after the addition of a few drops of litmus solution, is then titrated, with the aid of heat, with an excess of normal nitric acid, until a cherry-red tint of the liquid is produced, and subsequently in- versely titrated with a normal alkali until the red tint of the liquid is just changed to a permanent blue. The number of cubic centimeters of the normal nitric acid which are required in the. last operation, after the deduction of the normal alkali solution subsequently em ployed, will correspond to the amount of potassium carbonate present in the salt: one cubic centimeter of normal nitric acid corresponding to 0.069 gram of pure potassium carbonate. If sodium carbonate be also present in the pearlash, the results of the above methods of estimation will be influenced in proportion to its amount, and their correctness accordingly impaired. The estimation of the amount of sodium carbonate may also be quite readily accomplished by the following method : 10 grams of the pearlash are dissolved in 10 grams of hot water, the solution fil- tered, the filter with its contents of insoluble matter subsequently washed with 5 grams of water, and the entire filtrate finally supersaturated with acetic acid. The solution is then evaporated upon the water-bath to dryness, and the residue heated with 40 cubic centimeters of alcohol, of the spec. grav. 0.830, whereby the acetates of potassium and sodium pass into solution, and the sul- phates, chlorides, phosphates, and silicates remain undissolved. To the solution thus obtained, a solution of 21 grams of tartaric acid in 20 parts of hot water is added until, after standing for some hours, no further precipitate of potassium bitartrate is pro- duced. The mixture is then filtered, and the precipitate, con- tained upon the filter, washed with alcohol, until a few drops of the filtrate, after active agitation with a little potassium acetate, remain perfectly clear. The filtrate is subsequently evaporated to dryness, and gently ignited ; a few drops of M^ater are then added, and the operation repeated until, upon ignition, the mass becomes completely incinerated. The ignited mass is then dis- solved in water, neutralized with hydrochloric acid, and again evaporated. The sodium chloride thus obtained is dissolved in a small amount of water, a little ammonium carbonate added, and again evaporated to dryness, in order to remove the iron and aluminium, as also traces of calcium and magnesium which may POTASSIUM. 473 be present. The dried residue is then extracted with warm water, and the solution, wh'ch now contains pure sodium chlo- ride, filtered, evaporated to dryness, ignited in a covered platinum crucible, and its weight finally determined. From the weight of the sodium chloride the amount of anhydrous sodium carbonate may readily be calculated : 100 parts of the former corresponding to 90.6 parts of the latter. When the pearlash contains both potassium and sodium car- bonates, and a determination of the relative amount of each is required, an estimation of the amount of carbonic acid contained in a weighed portion (about 2 grams) of the ignited soluble salt must be made, as described on page 86. From the total amount of carbonic acid, the amount corresponding to that of the sodium carbonate present in the salt may be deducted, when the remain- der will correspond to the percentage of potassium carbonate, and should conform with the results of the volumetric estimation. POTASSII CARBONAS DBPURATUS. POTASSIUM SEU KA.LIDM CARBONICUM DEPURA.TUM. Purified Carbonate of Potassium. Purified Pearlash. Ger. Gereiiiigtes kohlensaures Kalium ; Fr. Potasse purifiee ; Sp. Potasa refinada. 2K,C03.3H,0; 330. A white, crystalline, or granular powder, permanent in a dry atmosphere, but deliquescent in a moist one, and possessing a strongly alkaline taste and reaction ; when heated, on platinum wire, in the non-luminous flame, it communicates to the latter a violet color. Purified pearlash is soluble in 1 part of water at 15° C. (59° F.), and in 0.7 part of boiling water, forming a strongly alkaline solu- tion which frequently appears slightly turbid, and deposits gradu- ally a flocculent or gelatinous sediment of silicic acid ; it is insolu- ble in alcohol. Its aqueous solution is decomposed by acids, with effervescence, yields a white, amorphous precipitate with magne- sium sulphate, and a white, crystalline one with an excess of tar- taric acid. Purified pearlash contains about 80 per cent, of potassium car- bonate, and not more than 15 to 18 per cent, of water, which latter is lost by exposure to a red heat. Examination : Potassium hydrate is indicated in the solution of the salt, by an alkaline reaction after its complete precipitation with an excess of barium chloride, and subsequent filtration ; its amount may be approximately estimated by agitating a few grams of the salt with absolute alcohol, filtering the solution, and evaporating the 474 MANUAL OF CHEMICAL ANALYSIS. filtrate, together with the alcoliolic washings therefrom, to com- plete dryness, in a tared porcelain capsule ; the weight of the dried residue will indicate approxin>atelj the proportion of potas- sium hydrate contained in the salt. Foreign Salts. — A small portion of the purified potassium car- bonate is dissolved in an equal weight of water, in a test-tube ; the solution should be complete. and limpid, or nearly so; it is diluted with an equal volume of water, filtered, and supersatu- rated with hydrochloric acid ; a gelatinous precipitate after a time would indicate silicic acid; the liquid is then filtered, and part of the filtrate supersaturated with ammonia-water, when a white tur- bidity would indicate aluminium salts; the other part of the fil- trate is tested with barium chloride for sulphate. Chloride and phosphate may be detected in the diluted solution of the salt, supersaturated with nitric acid, by testing it in two portions, with argentic nitrate for chloride, and by supersatura- tion with ammonia-water, and the subsequent addition of test magnesium mixture, for phosphate. Sulphite and hyposulphite are detected in the filtered solution of the salt, slightly supersaturated with acetic acid, by adding a few drops of mucilage of starch, and subsequently two or three drops of diluted solution of iodinized potassium iodide ; the first drop of the latter solution should produce a blue coloration at once, which will not occur before the addition of several drops, if the above impurities are contained in the salt. Sodium carbonate may be detected by a white, crystalline pre- cipitate, occurring at once or after some time, when a hot diluted solution of the potassium carbonate is nearly neutralized with acetic acid, and subsequently tested with potassium antimoniate. Metallic impurities are detected in the filtered solution of the salt, by dividing it into two parts, one of which is supersaturated with hydrochloric acid; both are then saturated with hydrogen sulphide, when any coloration or precipitate in either of the liquids would indicate the presence of foreign metals. Estimation : Wafer.— The percentage of water contained in the salt may be determined by its loss of weight, upon ignition in a small porce- lain crucible, at a red heat. Potassium Carbonate. — ^About 3 grams of the salt, accurately weighed, and previously deprived of water, by ignition at a strong heat in a small porcelain crucible, are dissolved in about 20 cubic centimeters of water, in a beaker or small flask, and a few drops of litmus solution added ; the solution having been heated to boil- ing, a standard solution of oxalic or sulphuric acid (page 82) is allowed to flow into the liquid from a burette until, with the con- tinuance of the heat to expel the liberated carbonic acid gas, a slight excess of acid has been employed, and the liquid assumes a bright cherry-red tint ; the excess of acid is then inversely titrated POTASSIUM. 475 with a standard solution of potassium or sodium hydrate (page 87), until the red tint of the liquid is just changed to a permanent blue. From the number of cubic centimeters of acid solution required for the exact neutralization of the salt, the amount of pure potassium carbonate contained therein may be calculated : one cubic centimeter of the normal acid solution corresponding to 0.0692 gram of anhydrous, or 0.0825 gram of crystallized potas- sium carbonate, 2K..,G0 ^.SKfi. If alkaline hydrates or sodium carbonate be present in the salt, the above method of estimation must be modified, as described in the preceding article, on pages 471 to 473. Table of the amount of dry Potassium Carbonate contained in solutions of the salt of different specific gravities. Temperature 15° C. (59° F.). Per cpnt. Spociflc Per CPnt. Speoiao Pev cent. Speoiio Per cent. Specific ofKiCOj. gravity. of KoCOs. grAvity. of K.COa. gravity. of K2CO3. gravity. 1 1.00914 14 i 1.13199 37 1.36787 40 1.41870 3 1.01830 15 1.14179 28 1.37893 41 1.43104 3 1.02743 16 1.15200 29 1.28999 43 1.44338 4 1.03658 17 1.16333 30 1.30105 43 1.4.5573 n 1.04o73 18 1.17243 31 1.31361 44 1.46H07 6 1.05r)13 19 1.18365, 33 l.:i3417 45 1.48041 7 1.06454 20 1.19386 33 1.. 33573 46 1.49314 8 1.07396 21 1.30344 34 l.,S4T29 47 1.. 50588 9 1.08337 23 1.31403 35 1.3.5885 48 1.. 51 861 10 1.093T8 23 1.23459 36 1.37083 49 1.53135 11 1 .103.58 24 1.23517 37 1.38379 50 1., 544 08 13 1.11338 35 1.24.575 38 1.39476 51 1.55728 13 1.12219 26 1.35681 89 1.40673 53 1.57048 POTASSII CARBONAS PURUS. POTASSIUM SEU KALIUM CARBONICUM PURUM. Pure Carbonate of Potassium. Salt of Tartar. Potassium Garbonate. Ger. Kohlensaures Kalium ; Fr. Carbonate de potaase ; Sp. Carbonato de potasa puro. KjCO^; 138. A white, deliquescent, granular powder, wholly soluble in an equal weight of water, forming a limpid alkaline liquid, which effervesces with acids, and gives a white, crystalline precipitate with an excess of tartaric acid. When exposed to a red heat, dry potassium carbonate loses about 16 per cent, of its weight. One hundred parts of the dry anhydrous carbonate require for com- plete neutralization 113 parts of citric, and 108.7 parts of tartaric, acid. 476 MANUAL OF CHEMICAL ANALYSIS. Examination : Bicarbonate. — A small portion of the salt is dissolved in an equal weight of water, aided by dipping the test-tube in hot water ; the solution should be clear and complete, and remain so after cooling ; the separation of a crystalline deposit would indicate potassium bicarbonate. The presence of the latter will also be indicated in a solution of one part of the salt in three parts of water, by the evolution of carbonic acid gas upon heating the solution to boiling. Purified Pearlash. — A portion of the above-obtained 'solution is slightly supersaturated with diluted nitric acid, and allowed to stand in a corked test-tube for several hours ; an ensuing gela- tinous precipitate would indicate silicic acid; the solution, after filtering, if necessary, is then tested in separate portions, with argentic nitrate for chloride, and with barium nitrate for sulphate, which impurities would indicate the admixture or substitution of purified pearlash. Metals. — Another portion of the above-obtained aqueous solu- tion of the salt is tested with hydrogen sulphide in two test-tubes, the one after supersaturation with diluted hydrochloric acid. An ensuing dark coloration or precipitate in either of the fluids would indicate metallic impurities. Potassium Nitrate. — The remainder of the concentrated solu- tion of the salt is supersaturated with diluted sulphuric acid ; the clear solution is decanted after a while, and divided into two parts, one of which is mixed with a little ferrous sulphate and then transferred, by means of a pipette, upon concentrated sul- phuric acid in a test-tube (Fig. 146) ; an ensuing purple or brown POTASSIUM. 477 coloration, at the junction of the two strata of the liquids, would indicate nitrate; tlie other part is tinged slightly blue with solu- tion of indigo, strongly acidulated with sulphuric acid, and heated ; ensuing decoloration would confirm the presence of nitrate. Nitrites may be detected by mixing a little of the aqueous solu- tion of the salt with an excess of dilute sulphuric acid, and subse- quently adding a few drops of a sokition of potassium iodide and a little mucilage of starch; a blue coloration will reveal the pres- ence of nitrite. Potassium cyanide may be detected in the solution of the salt, by the addition of a few drops of a solution of ferrous sulphate and ferric chloride, gently warming, and subsequently slightly supersaturating the liquid with hydrochloric acid; the immediate or gradual formation of a precipitate of Prussian blue will con- firm the presence of alkaline cyanide. Calcium and maynesvam salts, when present in the form of carbonates, will remain undissolved when the potassium carbonate is treated with twenty times its weight of water ; they may be otherwise detected in the aqueous solution, previously neutralized with hydrochloric ac'd, by the addition of ammonia- water, ammo- nium chloride, and ammonium oxalate; a white precipitate will indicate the presence of calcium ; the filtrate from the latter, or the clear liquid if no precipitate was produced, is then tested with sodium phosphate, when the formation of a while, crystalline pre- cipitate will reveal the presence of magnesium. Sodium salts will be indicated, by their property of imparting a persistent yellow color to the non-luminous flame; the carbonate may be specially tested for by supersaturating the aqueous solu- tion of the salt with acetic acid, evaporating to dryness, and extracting the residue with absolute alcohol ; the filtered alcoholic liquid is then evaporated to dryness, the residue dissolved in water, and a solution of potassium meta-antimoniate added ; if sodium carbonate were present, a white, crystalline precipitate of sodium meta-antimoniate will be produced. Estimation : The estimation of pure potassium carbonate may readily be ac- complished by the method described under purified pearlash, on pages 474-475. The United States Pharmacopoeia directs that to neutralize 3.45 grams of potassium carbonate should require not less than 40.5 cubic centimeters of the volumetric solution of oxalic acid (corresponding to at least 81 per cent, of pure, anhydrous potas- sium carbonate). 478 MANUAL OF CHE-MICAL ANALYSIS. POTASSII CHLORAS. POTASSIUM SEU KALIUM CHLORICUM. Chlorate of Potassium. Potassium Chlorate. Ger. Chlorsaures Kalium ; Fr. Chlorate de potasse; Sp. Clorato de potasa. KCIO^; 122.4. Colorless, transparent, monoclinic prisms or tables (Fig. 147), of a pearly lustre, anhydrous, and permanent in the air, and of a spec. grav. of 2.36 at 17.5° C. (63.5° F.); ^'°- ^^'^- when thrown upon burning charcoal they ~^ deflagrate, as they also do more or less violently when triturated or heated with readily combustible substances, as sul- phvir, carbon, phosphorus, etc. Potassium chlorate melts at 334° C. (633.2° F.) with- out decomposition ; at 352° 0. (665.6° F.) it .begins to decompose with the evolu- tion of oxygen, and at 400° C. (752° F.) the entire amount of oxygen (39.2 per cent, by weight) is liberated, leaving be- hind a neutral residue of potassium chloride (60.8 per cent.), which is wholly soluble in water. The aqueous solution of this residue 3'ields a white, crystalline precipitate with a coacentrated solution of sodium bitartrate, and a white, curdy precipitate, soluble in ammonia-water, with argentic nitrate. When a little sulphuric acid is dropped on the crystals of the chlorate, they become first yellow and then orange-red; with concentrated hydro- chloric acid the salt becomes likewise decomposed, with the libera- tion of chlorine and chlorine dioxide; the Jatter, in contact with an excess of acid, becoming subsequently decomposed into chlo- rine and water. Potassium chlorate is soluble in 16.5 parts of water at 15° C. (59° F.), in 2 parts of boiling water, and in 120 parts of alcohol of 0.835 spec. grav. Its saturated aqueous solution has a cooling, saline, slightly acerb taste, and, when mixed with concentrated hydrochloric acid, produces a deep greenish-yellow coloration, with, the evolution of chlorine gas. When a few drops of a con- centrated solution of potassium chlorate, and subsequently a little concentrated sulphuric acid, are added to a little of a dilute solu- tion of aniline sulphate, upon a watch-glass, the mixture assumes a brilliant deep-violet color. With solution of tartaric acid, the concentrated solution of potassium chlorate give a white granular precipitate. Examination : Potassium Nitrate. — A little of the powdered salt is heated in a porcelain crucible to a full red heat; the residue, when cool, is POTASSIUM. 479 dissolved in a few drops of water, and the solution tested with turmeric-paper; a brown discoloration of the paper would indi- cate an admixture of potassium nitrate. As a confirmatory test, a few drops of the solution of the residue may be added to a solu- tion of mercuric chloride; an ensuing yellow precipitate will confirm the presence of nitrate. The presence of nitrate may also readily be detected by first heating a small portion of the salt, in a test-tube, with about twice its weight of solid potassium or sodium hydrate, and a little water, in order to ascertain the absence of ammonium salts, and subse- quently adding a few iron and zinc filings, and again heating ; if ammonium salts were found to be absent, or have been com- pletely eliminated by the previous heating with caustic alkali, the odor of ammonia, developed upon the addition of the zinc and iron, will confirm the presence of nitrate. Potassium chloride and sul2:)hate are detected in the aqueous solution, acidulated with a few drops ofdiluted nitric acid, by the occurrence of a white precipitate, in the case of the former with argentic nitrate, of the latter with barium nitrate. Most commercial potassium chlorate occasions a slight cloudi- ness with argentic nitrate. Calcium salts may be detected in the dilute aqueous solution of the salt, by a white precipitate upon the addition of a few drops of a solution of ammonium oxalate. Sodium chlorate will be indicated in the salt by its property of imparting a persistent yellow color to the non-luminous flame, as also by its much greater solubility in water and warm alcoliol. It may be extracted by treating a portion of the salt with boiling alcohol, filtering, and adding to the filtrate a concentrated solu- tion of tartaric acid ; the potassium will thereby be precipitated, and, after its complete deposition, the filtrate may be further examined for sodium. Metallic impurities may be detected in the aqueous solution of the salt, acidulated with hydrochloric acid, by a dark coloration or precipitate upon saturation with hydrogen sulphide, or, after neutralization with ammonia-water, by the addition of ammonium sulphide. POTASSII CITRAS. POTASSIUM SEU KALIUM CITRICUM. Citrate of Potasiium. Potassium Giirate. Ger. Citronensanres Kalium ; Fr. Citrate de polasse ; Sp. Citrato de potasa. K,C„H,0, + H,0; 324. A white, granular powder, or transparent prismatic crystals, containing one molecule (5.55 per cent.) of water; it is deliques- 480 MANUAL OF CHEMICAL ANALYSIS. cent upon exposure to the air, odorless, of a slightly cooling and faintly alkaline- taste, and neutral in its action upon litmus. When moderately heated, the salt loses its water, at a higher tempera- ture it chars, and at a red heat becomes completely decomposed, with the evolution of empyreumatic, inflammable vapors, leaving a black residue, consisting of potassium carbonate and carbon, which strongly effervesces with acids. Potassium citrate is soluble in 0.6 part of water at 15° C. (59° F.), and is very soluble in boiling water ; it is very sparingly soluble in alcohol. Its aqueous solution yields a white, crystal- line precipitate upon the addition of a concentrated solution of sodium bitartrate; upon the addition of a cold solution of cal- cium chloride the liquid remains clear, but, upon boiling, a white, granular precipitate is produced, which redissolves for the most part upon cooling. Examination : Potassium tartrate will be indicated by the separation of a white, crystalline precipitate, upon the addition of acetic acid to a concentrated aqueous solution of the salt. Carbonates, Sulphates, and Chlorides. — The aqueous solution of the salt is slightly acidulated with nitric acid, when effervescence will indicate carbonates; the acidulated solution is then subse- quently tested, in separate portions, with barium chloride for sulphates and with argentic nitrate for chlorides, when an ensuing white precipitate in either instance will reveal the presence of such impurities. Metallic impurities may be detected in an aqueous solution of the salt, acidulated with hydrochloric acid, by a dark coloration or precipitate upon saturation with hydrogen sulphide, or, after supersaturation with ammonia-water, by the addition of ammo- nium sulphide. Estimation : Potassium citrate may be estimated volumetrically by its con- version into potassium carbonate, and the neutralization of the latter by means of a normal or standard acid. 5.4 grams of the salt are ignited in a porcelain crucible, at a red heat, until gases cease to be evolved ; the soluble matter of the residue is then completely extracted with hot water, the solution filtered into a beaker or small flask, a few drops of litmus solution added, and a standard solution of oxalic or sulphuric acid (page 82) allowed to flow into the liquid from a burette until, after being heated to boil- ing, in ofder to completely expel the liberated carbonic acid gas, the liquid assumes a bright cherry-red tint. The excess of acid is then inversely titrated with a standard solution of potassium or sodium hydrate (page 87) until the red tint of the liquid is just changed to a permanent blue. If the above amount of the salt is employed, the number of cubic centimeters of normal acid which POTASSIUM. 481 is required for its neutralization, when multiplied by 2, will rep- resent without further calculation its percentage purit3^ With the employment of other quantities of the salt than that above indicated, the calculation maybe made with the consideration that one cubic centimeter of normal acid corresponds to 0.10^ gram of potassium citrate, KjC^HjOj + H^O. POTASSII CYANIDTJM. POTASSIUM SEU KALIUM CYANATUM. Cyanide of Potassium. Potassium Cyanide. Ger. Cyankalium ; Fr. Cyanure de potassium ; Sp. Cianuro de potasio. KCN; 65. White, opaque, amorphous masses, or a white, granular, deli- quescent powder, having a sharp, somewhat alkaline taste, and a strongly alkaline reaction. It is odorless when perfectly dry, but emits the odor of hydrocyanic acid upon exposure to a moist atmosphere, in consequence of the absorption of water and car- bonic acid gas, and the liberation of h^^drogen cyanide. When exposed to a low red heat, with exclusion of the air, the salt is readily fusible without decomposition, and, upon slowly cooling, solidifies in the form of cubical crystals; when heated with exposure to the air, it absorbs oxygen, and becomes partially converted into potassium cyanate. It is decomposed by all acids, with the disengagement of hydrocyanic acid. Commercial potassium cyanide is soluble in 2 parts of water at 15° C. (59° F.), and in its own weight of boiling water; it is but sparingly soluble in strong alcohol, but is quite freely soluble iu boiling diluted alcohol, and crystallizes from the latter solution upon cooling. The aqueous solution has an alkaline reaction, exhales the odor of hydroc3'anic acid, and becomes gradually decomposed by exposure to the air; upon boiling, it is rapidly decomposed, with the evolution of ammonia, and the formation of potassium formiate. The aqugous solution of potas.sium cya- nide yields a white, crystalline precipitate upon the addition of a concentrated solution of sodiiim bitartrate ; with argentic nitrate, it yields a white precipitate, which is soluble in an excess of potas- sium cyanide or of ammonia-water ; and with a few drops of a solution of a ferrous and ferric salt, and the subsequent addition of hydrochloric acid in slight excess, a precipitate of Prussian blue is produced. It produces precipitates in solutions of the salts of most of the heavy metals, which, however, for the most part, are soluble in an excess of potassium cyanide, with the formation of crystallizable double salts, 31 482 MANUAL OF CHEMICAL ANALYSIS. The detection and isolation of potassium cyanide in subjects of forensic investigation depends upon the elimination of hydrocyanic acid in contact with stronger acids, and the same method is there- fore to be pursued, and the same precautions observed, as described in detail under hydrocyanic acid, on pages 161 to 163. Examination : Potassium carlonate, which is usually present in small amount, will be indicated in the aqueous solution of the salt by efferves- cence upon the addition of dilute hydrochloric acid. The acidu- lated solution thus obtained may subsequently be tested with a drop of a solution of ferric chloride ; a blue precipitate will indi- cate /errocyamJcZe, a deep blood-red coloration, stdphocyanide. Estimation : Since commercial potassium cyanide always contains a greater or less amount of impurities, and as its value depends upon the percentage amount of pure cyanide, the determination of the latter becomes necessary, and may be readily accomplished volumetri- ■ cally by the following method, the principles of which have been explained on pages 100-101. 0.65 gram of the salt is dissolved iu about 100 cubic centime- ters of water, in a beaker, a few drops of a solution of potassium hydrate added, or sufficient to impart to the liquid a distinct alka- line reaction, and subsequently a few drops of a saturated solution of sodium chloride. A decinormal solution of argentic nitrate (page 98) is then allowed to flow into the liquid i'rom a burette until, with constant stirring, a permanent cloudiness of the liquid is just produced. The number of cubic centimeters of silver solu- tion which is required to produce this effect, with the employ- ment of the above-stated amount of potassium cyanide, when multiplied by 2, will represent the percentage purity of the salt. With the employment of other amounts of the salt than that above stated, the calculation may be made with the consideration that one cubic centimeter of the decinormal silver solution, in accordance with the described process, corresponds to 0.013 gram of pure potassium cyanide. The United States Pharmacopoeia directs that if 0.65 gram of potassium cyanide be dissolved in 12 cubic centimeters of water, and volumetric solution of argentic nitrate be gradually added, the precipitate first formed should dissolve on stirring, aud a per- manent precipitate should not appear until at least 45 cubic centi- meters of the volumetric solution have been used (corresponding to at lea^t 90 per cent, of pure potassium cyanide). POTASSIUM. 483 POTASSII BT SODII TARTHAS. POTASSIUM ET TARTARICUM. NATUS. BocJielle Salt. SODIUM SODIUM TARTARICUM. TARTARATUM. NATRIO - KALIUM TARTARUS NATRO- Seignette Salt. Potassium and Sodium Tartrate. Ger. Weinsaures Kaliiim-Natrium ; Fr. Tartrate de potasse et de sonde ; Sp. Tartrate de potasa y sosa. CI-I(OH)-CO-OK KNaCTLO, + 4H,0 = + 4H,0 ; 282. Fio. 148. CH(OH)-CO-ONa Large, colorless, transparent, prismatic crystals, belonging to the rhombic system, the faces of which are unequally developed (Fig. 148) ; they contain four molecules (25.53 per cent.) of water of crystallization, and are slightly efflorescent in dry air. The salt occurs in commerce generally ground, as a snow-wliite powder. When quickly heated to about 75° 0. (167° F.), it melts in its water of crystallization, and at 100° C. (212° F.) loses 3 molecules of water, the remaining molecule of water being elimi- nated at 130° C. (266° F.), at which tempera- ture the salt begins to decompose ; at a higher temperature it chars and is decomposed, with the evolution of inflammable vapors and the odor of burnt sugar, and, on moderate ignition, leaves a blackened residue, which consists of a mixture of potas- sium and sodium carbonates with carbon, and which colors tur- meric-paper brown, effervesces with acids, and imparts a yellow color to the non-luminous flame when heated upon the looped end of a platinum wire (distinction from potassium tartrate). Potassium and sodium tartrate is soluble in 2.5 parts of water at 15° C. (59° F.), and in much less than its own weight of boil- ing water, but is insoluble in alcohol; its aqueous solution is neutral, has a mild, cooling, saline taste, and forms a white, gran- ular precipitate with acids and with solutions of acidulous salts. When dissolved in 8 parts of water, and dilute acetic acid is added to the liquid, a white, crystalline precipitate is gradually produced (distinction from sodium tartrate); with argentic nitrate it yields a white precipitate, which becomes black on boiling. Examination : A portion of the salt is dissolved in three times its weight of warm water; the solution should be clear and complete, and remain so after cooling; it should not act upon litmus-paper, nor effervesce upon the addition of hydrochloric acid (evidence of the ab.sence of sodium carbonate or bicarbonate). 484 MANUAL OF CHEMICAL ANALYSIS. Chlorides and sulphates may be detected by a white precipitate when the diluted solution of the salt, acidulated with nitric acid, is tested in separate portions, with argentic nitrate for the former, and with barium nitrate for the latter. In case the solution sepa- rates granular potassium bitartrate upon the addition of the acid, sufficient hot Avater is added to redissolve the precipitate before adding the reagent. Calcium salts are detected in the diluted solution, by means of ammonium oxalate. Ammonium salts may be detected by the odor of ammonia, when the salt is heated, in a test-tube, with a solution of potas- sium or sodium hydrate, and by the development of white fumes, when a glass rod, moistened with acetic acid, is held over the mouth of the tube. Metallic impurities are detected in the concentrated solution of the salt, acidulated with hydrochloric acid, and filtered, if neces- sary, by a dark coloration or precipitate upon saturation with hydrogen sulphide, or, after neutralization with ammonia-water, by the addition of ammonium sulphide. Crystallized potassium and sodium tartrate, being in appearance somewhat similar to crystallized borax and alum, and therefore liable to incidental mistake, may readily be distinguished from either of these substances, in addition to its physical characters, by its taste, by its neutral reaction — alum being acid, borax alka- line, and by the black alkaline fuse upon incineration, while both borax and alum swell up to a porous mass, and yield a white or colorless fuse. Estimation : 3.525 grams of the salt are ignited in a porcelain crucible, afc a red heat, until gases cease to be evolved ; the alkaline residue is then extracted with warm water, the solution filtered into a beaker, a few drops of litmus solution added, and titrated, by the aid of heat, with a standard solution of oxalic or sulphuric acid (page 82), as described under potassium carbonate, on page 474. The num- ber of cubic centimeters of the nornjal acid solution which is thus required for the exact neutralization of the liquid, when multiplied by 4, will indicate, without further calculation, the percentage purity of the salt. By the employment of other quan- tities of the salt than precisely that above stated, the calculation may also readily be made with the consideration that one cubic centimeter of the normal acid solution corresponds to 0.141 gram of pure crystallized potassium and sodium tartrate. POTASSIUM. 485 POTASSII FERROCYANIDUM. POTASSIUM SEU KALIUM FERROCYANATUM. Ferrocyanide of Potassium. Yellow Prusiiate of Potassium. Potassium Ferrocyanide. Ger. Ferrooyankaliura ; Fr. Cyanure de fer et de potassium ; Sp. FeiTocianuro de potasio. K,Fe(CN)„ + 3HP; 421.9. Large, trausluceat, yellow, tabular crystals, derived from an octahedron with a square base (Fig. 149) ; they cleave with facility in a direction parallel to the base of the octa- hedron, have a peculiar toughness and flexi- ^"'" ■^'^^• bility, and the specific gravity 1.83. The crystals contain three molecules (12.79 per cent.) of water of crystallization, and undergo no alteration in pure air at ordinary tempera- tures, but when heated to 60° C. (140° F.) they begin to lose their water of crystalliza- tion, which is completely eliminated at 100° C. (212° F.), leaving the anhydrous salt in the form of a white powder; the laiter, upon exposure to a red heat, is decomposed with the evolution of nitrogen, leaving a residue consisting of ferric carbide and potas- sium cyanide. When heated with dilute sulphuric acid, hydro- cyanic acid is evolved. Potassium ferrocyanide is soluble in 4 parts of water at 15° 0. (59° F.), and in 2 parts of boiling water ; it is insoluble in alcohol. Its aqueous solution has a mild saline taste, gives a white, granu- lar precipitate with a saturated solution of sodium bitartrate, and, when diluted, a blue one with ferric, a brick-red one with cupric, and a white one with ferrous and with plumbic salts; it is not. acted upon by hydrogen sulphide or ammonium sulphide, by tan- nic acid, nor by the alkaline hydrates and carbonates. When the. solution is exposed for some time to the action of light, Prussian blue is deposited, and, by long-continued boiling, with exposure to the air, ammonia is given off, and the liquid becomes alkaline. Examination : Foreign salts are indicated when the potassium ferrocyanide does not yield a complete and clear solution with four parts of water. Carbonate is indicated by effervescence of the concentrated solu- tion upon the addition of acetic acid, or upon placing fragments of a crystal in diluted sulphuric acid. Sulphate is detected, in the diluted solution, acidulated with nitric acid, by a white turbidity with barium nitrate. Chloride may be detected, when a mixture of 1 part of the ex- siccated salt with 3 parts of potassium nitrate (free from chloride) 486 MANUAL OF CHEMICAL ANALYSIS. and 10 parts of anhydrous sodium carbonate is heated nearly to redness iii a porcelain crucible ; when cool, the whole is dissolved in water, the filtered solution supersaturated with nitric acid, and tested with argentic nitrate, which will indicate chloride by a white precipitate. POTASSII HYDRAS. POTASSA. POTASSIUM SEU KALIUM HYDRICUM PURUM. KALI CAUSTICUM. • Pure Oaustie Potash. Potassa. Potassium Hydrate. Ger. Kaliumhydroxyd, Aetzkali ; Fr. Potasse caustique ; Sp. Hidrato de potasa. KOH; 56. A white, opaque, granular powder, or, when fused, white, semi- transparent plates or cylindrical sticks, of a fibrous fracture ; exposed to the air, it absorbs water and carbonic acid, and grad- ually deliquesces. It melts below a red heat to a clear oily liquid, and volatilizes unchanged, in the form of white vapors, when more strongly ignited; when introduced into the non-luminous flame, it imparts to the latter a violet color. Potassium hydrate is soluble in 0.5 part of water and in 2 parts of alcohol at 15° 0. (59° F.), with the evolution of heat, and is slightly soluble in ether; when the concentrated aqueous solution is cooled, the hydrate, KOHh-21-120, is deposited in transparent, colorless, acute rhombohedral crystals. Its aqueous solution has a soapy feel, a burning, corrosive taste, and a strong alkaline re- action ; it gives a grayish-brown precipitate with argentic nitrate, soluble in ammonia-water, and precipitates from their solutions most metallic oxides, several of which are redissolved by an excess of the potassium hydrate; when dropped into solution of tartaric acid, it produces a white, crystalline precipitate, which is redissolved by an excess of the alkali ; it decomposes ammonium salts with the evolution of ammonia. Examination : Potassium hydrate must afford a clear and nearly complete solution when treated with about five times it weight of alcohol ; the insoluble residue will be in proportion to the amount of foreign salts present. Sodium hydrate, although usually present in small amount, may be detected when contained in any considerable proportion by the following method. A weighed amount of potassium hydrate is dissolved in ten times its weight of water, the solution exactly neutralized with tartaric acid, and subsequently as much tartaric acid again added as was required for the neutralization of the POTASSIUM. 487 alkali ; the solution is then diluted with alcohol until the separa- tion of potassium bitartrate no longer ensues, and finally filtered. The solution, wiiich will contain the sodium in the form of bitar- trate, is evaporated to dryness, the residue ignited, and the ignited mass, consisting of sodium carbonate and carbon, dissolved in water, and filtered. The filtered solution, after neutralization with nitric acid, will then afford upon evaporation rhombohedral crystals of sodium nitrate, which impart a yellow color to the non-luminoQS flame. The amount of sodium hydrate may also be quantitatively determined, by the neutralization of a definite amount of the sodium bitartrate .solution with a normal solution of potassium or sodium hydrate (page 82). The number of cabio centimeters of normal alkali solution which is required for this purpose will be in direct proportion to the amount of sodium hydrate contained in the solution under examination. Silicates, as also many foreign salts, will be indicated by a pre- cipitate, or by the separation of a heavy aqueous layer, when a solution of the potassium hydrate in two parts of water is dropped into alcohol. Carbonate may be detected when portions of a concentrated aqueous solution of the hydrate are dropped severally into acetic acid and into lime-water ; effervescence with the acid, and a white turbidity with the lime-water, would indicate carbonate. Nitrate is indicated by ensuing decoloration of the liquid when a little of the aqueous solution which has been mixed with an excess of dilute sulphuric acid, and tinted blue with one drop of indigo-solution, is gently heated. Chloride and sulphate are detected in the diluted solution, super- saturated with dilute nitric acid, by testing it, in separate por- tions, with argentic nitrate for chloride, and with barium nitrate for sulphate. Aluminium salts and phosphoric acid may be detected in the diluted solution, after supersaturation with hydrochloric acid, by the addition of ammonia- water in slight exces.s, and after filtering, if a precipitate be formed, by the subsequent addition of test mag- nesium mixture; a white, gelatinous precipitate with the ammo- nia-water would indicate aluminium salts, and a white, crystalline one with the latter reagent, occurring at once or after several hours, phosphoric acid. Metallic impurities are detected by a dark coloration or tur- bidity of the solution, when saturated with hydrogen sulphide, and, in another portion of the solution, after previous supersatu- ration with hydrochloric acid. Estimation : 2.8 grams of dry potassium hydrate are dissolved in about 20 cubic centimeters of water, in a beaker, a few drops of litmus solution added, and a standard solution of oxalic or sulphuric acid (page 82) allowed to flow into the liquid from a burette, 488 MANUAL OF CHEMICAL ANALYSIS. until the blue tint of the liquid is just changed to a permanent pink. The number of cubic centimeters of normal acid solu- tion which is thus required for the exact neutralization of the above- amount of potassium hydrate, when multiplied by 2, will represent, without further calculation, its percentage purity. By the employment of other amounts of the hydrate, the calcula- tion may readily be made, with the consideration that one cubic centimeter of the normal acid solution corresponds to 0.056 gram of pure potassium hydrate. if the potassium hydrate contains carbonate, the above estima- tion will only be strictly correct, when in a weighed amount of the hydrate the amount of carbonic acid is determined, as de- scribed on pages 85-86 ; for 1 part of carbonic acid, 2.545 parts of potassium hydrate are deducted from the found amount of the latter, and the remainder then calculated as pure potassium hydrate. For the determination of the strength of aqueous solutions of potassium hydrate, as based upon the specific gravity of the latter, see Liquor Potassas, page 410. POTASSII HYDRAS CRUDUS. POTASSIUM SEU KALIUM HYDRICUM CRUDUM. Crude Potash. Ger. Rohes Aetzkali; Fr. Potasse caustique impure ; Sp. Hidrato de potasa ordinaria. Fused, heavy, compact masses, of a stony appearance, fracture, and hardness, of a soapy feel, burning, corrosive taste, and a destructive action on vegetable and animal matters ; its color is mostly greenish or brownish-gray; it is deliquescent, and rapidly absorbs -water and carbonic acid. Heated to redness, it fuses, but remains unchanged ; at a very high' heat it is volatile. Crude potash dissolves, for the most part, in water and in alco- hol, with evolution of heat, leaving a more or less considerable residue of impurities ; the decanted solution gives a grayish-brown precipitate with argentic nitrate, soluble upon the addition of ammonia-water. The insoluble impurities of crude potash consist chiefly of car- bonates, sulphates, silicates, chlorides, and ferric and manganic oxides. Examination : In order to ascertain the nature of the impurities, a portion of the crude potash i.s. triturated and dissolved in twice its weight of tepid water, and the whole is allowed to subside iu a conical POTASSIUM. 489 glass vessel ; the clear solution is then mixed with twice its volume of strong alcohol, and the mixture allowed to stand for several hours; the solution is then decanted from the precipitate, as far as practicable, and the latter dissolved in hot water ; when cool, this solution is filtered, and the insoluble residue washed with a little water, and preserved upon the filter for further examination. The obtained aqueous solution may be examined as follows: Carbonate and silicate are recognized on dropping a little of the solution into a test-tube containing a mixture of equal parts of water and concentrated nitric acid ; the former will be indicated by effervescence, the latter by a white, gelatinous turbidity, ensu- ing at once or after some hours. Sulphate and chloride may be detected, in separate portions of the solution, by supersaturating it with nitric acid, and subse- quently testing with barium nitrate for sulphate, and with argentic nitrate for chloride. Sulphite and hyposulphite are indicated by the occurrence of an insoluble residue, when a portion of the solution is precipitated with argentic nitrate, and the precipitate is treated with ammonia- water. Nitrate is detected, m a portion of the solution, after the ad- dition of an excess of dilute sulphuric acid and one drop of solu- tion of indigo; the blue tint will disappear upon warming, if nitrate be present. Phosphate may be detected by a white, crystalline precipitate, when the solution is supersaturated with hydrochloric acid, then mixed with an equal volume of ammonia-water, and subsequently tested with magnesium sulphate. Metallic impurities are recognized by a dark coloration or pre- cipitate, when both the alcoholic solution and the aqueous solu- tion of the residue from the alcoholic one are tested separately with hydrogen sulphide, as also after having been previously supersaturated with hydrochloric acid. The residue remaining from the solution in alcohol, and pre- served upon the filter, is washed with a few drops of alcohol, then dissolved upon the filter in diluted hydrochloric acid, and subse- quently neutralized with am monia- water ; this solution is then tested, in separate portions, with ammonium oxalate for calcium, and with barium chloride and a few drops of hydrochloric acid for sulphate. The estimation of crude potash may be accomplished volu- metrically by the method described for pure potassium hydrate, on pages 487-488. 490 MANUAL OF CHEMICAL ANALYSIS. POTASSII HYPOPHOSPHIS. POTASSIUM SEU KALIUM HYPOPHOSPHOROSUM. Hypophosphile of Potassium. Potassium Mypophosphite. Ger. Unterpliosphorigsaures Kalium ; Fr. Hypophosphile de potasse ; Sp. Hipofosfito de potasa. KH,PO,; 104. White, opaque, crystalline masses, or hexagonal tables, or a ■white granular powder, very deliquescent, and neutral in its action upon litmus; when heated in a perfectly dry test-tube, the salt first loses adhering moisture, then evolves spontaneously inflammable hydrogen phosphide, and burns with a bright yellow flame ; when evaporated to dryness, in contact with nitric acid, it detonates violently. Potassium hypophosphite is soluble in 0.6 part of water, and in 7.3 parts of alcohol at 15° 0. (59° F.) ; in 0.3 part of boiling water, and in 3.6 parts of boiling alcohol ; but is insoluble in ether. The aqueous solution possesses a sharp, saline, and slightly bitter taste, and yields a white, crystalline precipitate on the addition of a concentrated solution of sodiuni bitartrate ; with argentic nitrate it yields a white precipitate, which rapidly turns brown and black with the separation of metallic silver; when acidulated with hydrochloric acid, and added to excess of solution of mer- curic chloride, it first produces a white precipitate of mercurous chloride (calomel), and, on further addition, metallic mercury is separated. Examination : Calcium salts will be detected by an ensuing white precipitate on the addition of ammonium oxalate to an aqueous solution of the salt. Carbonates will be detected by effervescence of the solution on the addition of an acid. Chlorides and sulphates will be detected in the aqueous solution of the salt, acidulated with nitric acid, by a white precipitate when tested, in separate portions, with argentic nitrate and barium chloride. Phosphates will be indicated in the aqueous solution of the salt by the formation of a white crystalline precipitate, either at once or upon standing, on the addition of test magnesium mixture. POTASSIUM. 491 POTASSII lODIDTJM. POTASSIUM SEU KALIUM lODATUM. Iodide of Potassium. Potassium Iodide. ' Ger. Jodkalium ; Fr. lodure de potassium ; Sp. loduro de potasio. KI; 165.6. Colorless, anhydrous, semi-trausparent, or opaque crystals, cubical, or sometimes elongated in form, permanent in dry, but slightly deliquescent in moist, air, and having a spec. grav. of 2.97. When exposed to heat, potassium iodide decrepitates, and fuses below a red heat; on cooling, it solidifies into a crystalline, pearly mass, without loss of weight, except humidity ; at a full red heat, it is slowly volatilized, without decomposition. When a few fragments of the salt are heated in concentrated sulphuric acid, or, in a dry test-tube, with a little potassium bisulphate, violet-colored vapors of iodine are evolved ; and when dissolved in a little water, a few drops of chlorine-water added, and the mixture subsequently shaken with half its volume of chloroform or carbon bisulphide, these will acquire a purple or violet color. Potassium iodide is soluble in 0.8 part of water, in 18 parts of alcohol, of 0.835 spec, grav., and in 40 parts of absolute alcohol at 15° C. (59° F.), in 0.5 part of boiling water, and in 6 parts of boiling alcohol, and is also very freely soluble in warm anhydrous glycerin. The aqueous solution possesses a pungent, saline taste, a neutral or feebly alkaline reaction, and gives, with an excess of tartaric acid, a white, granular precipitate; with argentic nitrate, a yellowish one, which is insoluble in diluted nitric acid, and almost insoluble in ammonia-water, but becomes white with the latter ; and a vermilion-red precipitate with mercuric chloride, soluble in an excess of either the solution or the reagent ; it gives a violet-blue color with a little mucilage of starch, upon the sub- sequent addition of a few drops of chlorine-water (distinction from potassium bromide and chloride), and a white, crystalline precipitate with a saturated solution of sodium bitartrate. Examination : Water.! which may be contained as interstitial moisture in the crystals, is recognized, and may be quantitatively determined, by the loss of weight upon drying a known weight of the powdered salt at 100° C. (212° P.). Impurities and Adviixtures. — In order to obtain for examina- tion an average representation of the iodide, several grams of smaller and larger crystals are selected from the bulk of the salt, and triturated to a granular powder, part of which may serve for the following tests : One gram of it is dissolved in an equal weight of water ; the solution formed must be clear and complete, and remain so after the addition of several times its volume of strong 492 MANUAL OF CHEMICAL ANALYSIS. or absolute alcohol ; an ensuing turbidity or crystalline deposit would indicate foreign salts (carbonate, sulphate, iodate, nitrate); if this precipitate is considerable, it may be collected upon a filter, washed with a few drops of alcohol, and then dissolved in a few drops of warm water ; the obtained solution may be tested for carbonate with turmeric-paper, or by allowing one or two drops of it to fall into concentrated hydrochloric acid ; a brown colora- tion of the paper, and effervescence with the acid, will indicate the presence of carbonate ; the rest of the solution is acidulated with a few drops of hydrochloric acid, and tested for sulphate with one drop of barium chloride, and subsequently, for nitrate, by the addition of a little sulphuric acid and a drop of indigo solution, and heating. Potassium iodate may be detected in the aqueous solution of the salt, by adding a few drops of mucilage of starch, and then a few drops of a concentrated solution of tartaric acid, insufficient to cause a precipitate ; if iodate be contained in the salt, a violet coloration of the liquid will occur at once. Or the aqueous solu- tion, mixed with a few drops of concentrated solution of tartaric acid, may be shaken with a little chloroform, which will assume a fed color when iodate is present. Iodate may also be recognized in potassium iodide by dropping a crystal of tartaric acid into a strong solution of the iodide in previously boiled, distilled water, and allowing it to remain at rest for several minutes ; if iodate be present, the crystal will be enveloped after that time in a yellowish-white zone. Carbonate may be detected by a white turbidity when the aqueous solution of the potassium iodide is mixed with twice its volume of lime-water, and will also be indicated by a strongly alkaline reaction, when a few fragments of the salt are placed upon moistened red litmus paper. Sulphate may be detected in the diluted solution of the iodide, previously acidulated with hydrochloric acid, by a white precipi- tate with barium chloride. Nitrate may be detected in the aqueous solution, if the salt be free from iodate, by the addition of a few drops of mucilage of starch, and subsequently adding a little of this liquid to a mix- ture of zinc and dilute hydrochloric acid, in which the develop- ment of hydrogen is activel}'- taking place; if any nitrate be pre- sent, the liquid will gradually assume a reddish-violet or blue color. If iodate be present, the presence of nitrate may also be determined by completely precipitating a solution of the salt with argentic sulphate, filtering, and adding to the filtrate, in a test- tube, a concentrated solution of ferrous sulphate, and afterwards concentrated sulphuric acid, so as to form two layers (Fig. 146, p. 476) ; a dark-brown coloration at the line of contact of the two liquids will then reveal the presence of nitrate. Chloride and bromide are detected by dissolving 1 gram of the salt in 10 grams of ammonia-water, and agitating the solution POTASSIUM. 493 with a solution of 1.1 grams of argentic nitrate in 20 grams of water ; the mixture is then filtered, and the filtrate super- saturated with 8 grams of strong nitric acid; since ammonia- water dissolves only traces of argentic iodide, the transparency of the liquid must be not at all, or only slightly, impaired; a white turbidity, subsiding to a precipitate, would indicate the presence of more than about 0.5 per cent, of chloride or bromide. In order to distinguish these, the precipitate is collected upon a filter and washed with a little water, until this ceases to redden blue litmus- paper ; the filter is then pierced by a glass rod, and the precipi- tate rinsed into a test-tube; after subsidence, the water is, as far as possible, decanted, and chlorine-water added and agitated with the precipitate ; since chlorine decomposes argentic bromide, dis- solving the disengaged bromine with a yellow color, bromide will be recognized by a more or less deep yellow color of the fluid, while argentic chloride remains unchanged. When chloroform or ether is then added to the fluid and agitated, it will absorb the bromine and the yellow color from the water. A confirmatory test for the recognition of bromide is, to add to a solution of the salt an excess of solution of cupric sulphate, and subsequently so much of a saturated solution of sulphurous acid as to impart its strong odor to the mixture, and until the brownish color of the mixture has disappeared ; the liquid is then filtered, a little chloroform added, and subsequently chlo- rine-water in very slight excess, in order to effect the oxidation of the sulphurous acid, and the mixture well agitated; after sub- sidence has taken place, a yellow color will have been imparted to the chloroform if bromide is contained in the salt. Iron and zinc may be detected in the aqueous solution of the salt by the addition of a few drops of a solution of potassium ferrocyanide ; a blue coloration will reveal the presence of iron, and a white precipitate that of zinc. Estimation : A quantitative estimation of the purity of potassium iodide may be made by dissolving 1 gram of the salt in 10 grams of ammonia-water, and adding to the solution a solution of not less than 1.1 grams of argentic nitrate in 20 grams of water ; the mix- ture is then well agitated, filtered, and the precipitate of argentic iodide well washed with water, and finally dried at 100° 0. (212° F.) until of constant weight. If the potassium iodide was pure, 1.415 grams of argentic iodide should be obtained, or, 100 parts of argentic iodide correspond to 70.65 parts of potassium iodide. The estimation of the purity of potassium iodide may also be accomplished volumetrically by the following method: This is based upon the fact that mercuric chloride precipitates from a solution of potassium iodide, red mercuric iodide, which is soluble in an excess of a solution of potassium iodide with the formation of a soluble double salt, and the solution of the latter again yields 494 MANUAL OF CHEMICAL ANALYSIS. upon the subsequent addition of mercuric chloride a precipitate of mercuric iodide. 2KI + HgCl, = Hgl, + 2KC1 Hgl, + 2KI = HgKJ, or 4KI + HgCl, = HgKJ, + 2KC1. 664 271 (5) (2.03) 2.03 grams of mercuric chloride are dissolved in water to the measure of 100 cubic centimeters, and 5 grams of the potassium iodide under examination are likewise dissolved in water to the measure of 100 cubic centimeters;* 10 cubic centimeters of the po- tassium iodide solution are then brought into a beaker, which is placed upon a sheet of white paper, and the above solutionof mer- curic chloride allowed to flow into the liquid from a burette until, with constant stirring, a permanent precipitate of mercuric iodide is just produced. The number of cubic centimeters of the mer- curic chloride solution which are required to produce this reac- tion, when multiplied by 10, will represent the percentage amount of pure potassium iodide contained in the salt. The accuracv of the result of the estimation by the above method is not influenced by the presence of chloride or of considerable amounts of bromide. POTASSII NITRAS. POTASSIUM SEU KALIUM NITRICUM. Nitrate of PotasHum. Saltpetre. Nitre. Potassium Nitrate. Ger. Salpetersaures Kalium, Salpeter ; Fr. Azotate de potasse ; Sp. Nitrato de potasa. KNO,; 101. Long, striated, six-sided, prismatic crystals, belonging to the rhombic system (Fig. 150), colorless and transparent, and of a spec. grav. of 2.0 : or a white, granular powder, permanent in the air. It melts at about 340° C. (642.2° F.) without decomposition, and solidifies on cooling to a white, opaque, crystalline mass ; at a red heat, it is decomposed with the evolution of oxygen and nitrogen gases, and leaving a residue consisting principally of po- tassium nitrate, oxide, and dioxide, which emits nitrous vapors on the addition of sulphuric acid. When thrown upon burning coals, * The i-psnlts attained by this method are rendered. more accurate when, in- stead of dissolving the mercuric chloride and potassium iodide in water, alcohol of 17.5 per cent, by volume is employed. From the formula x = " in n which n represents the percentage strength of the alcohol to be diluted, the vol- ume of alcohol maybe calculated which must be added to the water in order to obtain 100 paits of alcohol of 17.5 per cent, by volume. POTASSIUM. 495 Fig. 150. I A it deflagrates with bright scintillations, leaving an alkaline resi- due, which, when heated upon the looped end of a platinLim-wire, imparts a violet color to the non-luminous flame. Potassium nitrate is soluble in 3.8 parts of water at 15° 0. (59° F.), and in 0.4 part of boiling water ; it is far less soluble in glycerin, and almost insolu- ble in alcohol; its aqueous solution is neutral, has a cooling, saline taste, and forms a white, granular precipitate with a concentrated solution of sodium bitartrate ; a few drops of it mixed with a solution of ferrous sulphate, and carefully placed upon con- centrated sulphuric acid (Fig. 146, page 476), give rise to the formation of a dark coloration upon the lino of contact between the two fluids. Examination : Chloride and sulphate are detected in the diluted solution of the salt, acidulated with nitric acid, by ensuing white precipitates when tested in two separate portions, with argentic nitrate for chloride, and with barium nitrate for sulphate. Chlorate is indicated by a yellow coloration, and the evolution of chlorine, when a concentrated solution of the potassium nitrate is mixed and gently warmed with an equal volume of concentrated hydrochloric acid. Calcium and magnesium salts are detected by a white turbidity when the diluted solution is warmed with dilute solution of sodium carbonate ; they may be distinguished by adding a little ammo- nium chloride and ammonia-water to the dilute solution of the salt, and testing it, in separate portions, with ammonium oxalate for calcium, and, after filtration, if necessary, with sodium phos- phate for magnesium. Potassium nitrite may be detected by a violet or blue colora- tion, when to a solution of the salt a little mucilage of starch, a few drops of a solution of pure potassium iodide, and subsequently dilute sulphuric acid are added. Sodium salts will be indicated by their property of imparting a persistent yellow color to the non-luminous flame, as also by a white, crystalline precipitate, occurring either at once or after several hours,- when a concentrated cold solution of the salt is tested with a few drops of solution of potassium antimoniate. When thus indicated, the extent of such a contamination may be determined by repeatedly extracting a weighed amount of the powdered salt with boiling alcohol of the spec. gray. 0.890 ; the filtered liquid will then leave, upon evaporation, a residue, con- sisting principally of sodium nitrate with a little potassium nitrate. The residue is then dissolved in a little water, acidulated with hydrochloric acid, and the potassium completely precipitated by the addition of platinic chloride and a little alcohol ; the liquid is subsequently filtered from the precipitate of potassio-platinic 496 MANUAL OF CHEMICAL ANALYSIS. chloride, the excess of platinum removed by saturation with hydrogen sulphide, and, after filtration, evaporated to dryness, ignited at a gentle heat, and the residue finally weighed as sodium chloride: 100 parts of which correspond to 145.3 parts of sodium nitrate. If potassium nitrate contains even a few per cent, of sodium nitrate, it will have a moist appearance, arising from the deli- quescent character of the latter salt. Metallic impurities will be indicated by a dark coloration or precipitate, wiien a solution of the salt, acidulated with hydro- chloric acid, is tested with hydrogen sulphide, and, after filtration, if necessary, and neutralization with ammonia-water, by the sub- sequent addition of ammonium sulphide. Estimation : The proper amount of nitric acid contained in the salt may be conveniently determined by its ignition in a small porcelain cru- cible, at a red heat, with an equal weight of concentrated sulphuric acid, until it ceases to lose weight. One gram of the salt, if per- fectly pure, will thus aflford a residue of potassium sulphate, weighing 0.86 gram. The determination of the proper amount of potassium in the salt, when free from sodium, may also readily be accomplished, as follows. A weighed amount (about 5 grams) of the potassium nitratC; contained in a porcelain capsule, is repeatedly evaporated with a solution of about 8 grams of oxalic acid to dryness, or until completely converted into potassium oxalate. The latter is then, by ignition, converted into potassium carbonate,, which is dissolved in water, and, after the addition of a few drops of litmus solution, titrated with a standard solution of oxalic or sulphuric acid (page 82), as described under potassium carbonate, on page 474. The calculation may then be made with the consideration that one cubic centimeter of normal ac'd corresponds to 0.069 gram of potassium carbonate, or, as its equivalent, 0.101 gram of pure potassium nitrate. Table of the percentage strength of solutions of Potassium Nitrate of different specific gravities. Temperature 15° C. (59° F.). Per cent. Specific , Pel- cent. Specific Per cent. Specific of KSO3. gravity. ■ of KXO.. gravity. of KKO3 gravity. 1 1.00641 8 1.05197 15 1.09977 3 1. 01283 9 1.05861 16 1.10701 3 1.01924 1 10 1.06524 17 1.11426 4 1.0256B \ 11 1.07215 18 1.12150 5 1.03307 12 1.07905 19 1.12875 6 1.03870 13 1.08596 20 1.13599 7 1.0453t 14 1.09286 21 1.14361 POTASSIUM. 497 Fig. 151. POTASSII PERMANGANAS. POTASSIUM SEU KALIUM PERMANGANICUM SEU HYPERMANGANICUM. Permanganate of Potassium. Potassium Permanganate. Ger. Uebermangansaures Kalium ; Fr. Permanganate de potasse ; Sp. PermangaDato cle potasa. K,Mn,0,; 314. Slender, dark-purple, prismatic crystals, belonging to the rhom- bic system (Fig. 151), of a metallic lustre, permanent in the air, and having a specific gravity of 2.71 ; they decrepitate when thrown upon burning coals, or when sud- denly heated, and when mixed with sulphur or phosphorus, a mixture is obtained which takes fire or explodes violently on percussion or by heating ; on exposure to a red heat, the salt gives off' oxygen, and leaves a black residue of an alkaline reaction. Potassium permanganate is soluble, with the ex- ception of a slight brown residue, in 20 parts of water at 15° C. (59° F.), and in 3 parts of boiling water ; it is insoluble in alcohol, and is slowly de- composed in contact therewith. Its concentrated solution has a deep violet-red color, when highly diluted, a rose color, a sweet, astringent taste, is neutral, and becomes yellowish-brown when mixed and heated with alcohol. Since permanganic acid is readily reduced, the solution of the salt is decomposed and decolorized by most organic substances, and by inorganic reducing agents — e. g., sulphurous and oxalic acids, hydrogen sulphide, and all metallic subsalts. Potassium permanganate is, therefore, a pow- erful oxidizer, causing more or less violent reactions with many substances, and the combustion of inflammable bodies. Examination : The purity of the salt may readily be determined by the fol- lowing simple test: 0.314 gram of the potassium permanganate is dissolved in water to the measure of one liter; another solution is then prepared by dissolving 0.63 gram of pure, crj'stallized oxalic acid in water, acidulated with sulphuric acid, to the measure of a liter ; if the potassium permanganate is pure, one cubic centi- meter of the above permanganate solution will require for com- plete decoloration an equal volume, or exactly one cubic centimeter of the oxalic acid solution, and the amount of the latter, which is required to produce this reaction, will be, therefore, in direct pro- portion to the purity of the salt. 32 498 MANUAL OF CHEMICAIi ANALYSIS. Nitrate and Chloride. — A portion of the decolorized liquid, as obtained by the preceding test, is carefully poured upon a cold solution of ferrous sulphate in strong sulphuric acid, when a dark- colored zone at the line of contact of the two liquids will indicate the presence of nitrate: another portion of the decolorized liquid is tested with a few drops of a solution of argentic chloride, when a permanent white turbidity or precipitate will reveal the presence of chloride. Sulphate may be detected by boiling an aqueous solution of the salt with an excess of ammonia-water, until all the manganese is precipitated as hydrated oxide; the liquid is then filtered, and the colorless filtrate subsequently tested with barium chloride, when an ensuing white precipitate will reveal the presence of sulphate. The United States Pharmacopoeia directs that if 0.785 gram of the salt be dissolved in 50 cubic centimeters of boiling, distilled water, and 5 cubic centimeters of sulphuric acid be cautiously p,dded, the solution so formed should require for complete decolora- tion not less than 24.7 cubic centimeters of the volumetric solu- tion of oxalic acid (corresponding to at least 98.8 per cent, of pure potassium permanganate). POTASSII SULPHAS. POTASSIUM set; kalium sulfuricum. Sulpliate of Potassium. Potassium Sulphate. Ger. Schwefelsaures Kalium ; Fr. Sulfate de potasse ; Sp. Sulfate de potasa. K,SO,; 174. Hard, colorless, transparent, short, six-sided prisms, or pjTa- mids, belonging to the rhombic system (Fig. 152), or a white, •granular powder, anhydrous, and permanent Fig. 152. in the air, and having a spec. grav. of 2.648 ; when heated, the crystals decrepitate strongly, and at a strong, red heat they fuse, without de- composition, solidifying again on cooling to a crystalline mass ; at a white heat, they are to a slight extent volatilized. The salt, when heated on the looped end of a platinum-wire, imparts a violet color to the non-luminous flame. Potassium sulphate is soluble in 9 parts of water at 15° C. (59° P.), in 4 parts of boiling water, sparingly soluble in glycerin, and in- soluble in strong alcohol, and solution of potas- sium hydrate of the spec. grav. 1.35. Its aqueous solution has a saline bitter taste, is neutral, and forms white precipitates with POTASSIUM. 499 tartaric acid or sodium bitartrate, and with solutions of salts of calcium, barium, or lead. Examination : Potassium, hisulphate will be indicated by an acid reaction of the solution of the salt, and also by the loss of weight, when the salt, previously dried at 110° C."(230°F.), is heated nearly to redness in a covered porcelain crucible. Sodium sulphate is indicated by the property of imparting a persistent yellow color to the non-luminous flame, and by a greater degree of solubility in cold water than that above stated; one part of the powdered salt, when dissolved in eight parts of boil- ing water, must, on cooling, give a crystalline deposit ; otherwise sodium sulphate, or an admixture of more soluble salts, is indi- cated ; in this case the solution may be tested with potassium metantimoniate for sodium, and, in another portion, after dilution with water and acidulation with nitric acid, by means of argentic nitrate for chloride. Nitrate will be detected in the aqueous solu- tion of the salt, after the addition of a drop of indigo solution and a little concentrated sulphuric acid, by decoloration of the liquid upon heating. Calcium and Ma'jnesium Salts.— The aqueous solution of the salt is tested with .ammonium oxalate, when a white precipitate will reveal the presence o^ calcium; after the removal of the latter, if present, by filtration, solution of ammonium chloride, ammonia-water, and sodium phosphate are added, when the forma- tion of a white, crystalline precipitate will reveal the presence of magnesium. Metallic impurities are detected in the warm aqueous solution, after acidulation with hydrochloric acid, by a dark coloration or turbidity upon saturation with hydrogen sulphide, or, after filtra- tion, if necessary, and neutralization with ammonia- water, by the addition of ammonium sulphide. Potassium ferrocyanide should cause neither a blue {iron) nor a reddish (co^jser) coloration in the slightly acidulated solution. POTASSII SULPHIS. POTASSIUM SEU KALIUM SULFUROSUM. Sulphite of Potassium. Potassium Sulphite. Ger. Schwefligsaures Kalinm ; Fr. Sulfite de potasse ; Sp. Sulfite de potasa. K SO3 -f 2H,0 ; 194. Colorles.s, opaque, obliquely rhombic, octohedral crystals, or a white, crystalline powder, odorless, and somewhat deliquescent on exposure to a moist atmosphere ; it contains two molecules (18.55 £00 MANUAL OF CHEMICAL ANALYSIS. per cent.) of water of crystallization, which are lost by drying at a moderate heat; at a red heat it is decomposed, leaving an alka- 1 ne residue consisting of potassium sulphate, sulphide, and oxide, which imparts a brown color to moistened turmeric paper, and, on the addition of an acid, develops the odor of hydrogen sul- phide. Potassium sulphite is soluble in 4 parts of water at 15° C. (59° F.), and in 5 parts of boiling water, but is very sparingly soluble in alcohol. The aqueous solution possesses a bitter, saline, and sulphurous taste, a slightly alkaline reaction, and yields a white crystalline precipitate on the addition of a concentrated solution of sodium bitartrate; with argentic nitrate it yields a white precipitate, which becomes blackened on heating. On the addition of dilute hydrochloric or sulphuric acid to the solution of the salt, sulphur dioxide is liberated, which may be recognized by the odor of burning sulphur, but no turbidity is thereby pro- duced in the liquid (distinction from hyposulphite). Examination : Sulphate may be detected in the dilute solution of the salt, strongly acidulated with hydrochloric acid, by a white precipitate on the addition of barium chloride. Estimation : About 0.3 gram of the salt is dissolved in 25 cubic centimeters of water, in a beaker, a little mucilage of starch added, and sub- sequently a decinormal solution of iodine (page 93) allowed to flow into the liquid from a burette until, with constant stirring, a permanent blue coloration of the liquid is just produced. The number of cubic centimeters of iodine solution required to pro- duce this reaction, when multiplied by the decimal 0.0097, will represent the amount of pure, crystallized potassium sulphite, K2SO3-I-2H2O, in the quantity employed, and therefrom its per- centage purity may readily be calculated. The United States Pharmacopoeia directs that if 0.485 gram of the salt be dissolved in 25 cubic centimeters of water, and a little gelatinized starch added, at least 45 cubic centimeters of the volumetric solution of iodine should be required, until a per- manent blue tint appears after stirring (corresponding to at least 90 per cent, of pure potassium sulphite). POTASSIUM. , 501 POTASSII TARTRAS. POTASSIUM SEU KALIUM TARTARICUM. Tartrate of PotaHsium. Potassium Tartrate. Ger. "Weinsaures Kalium ; Fr. Tartrate de potasse ; Sp. Tartrate de potasa. CH(OH)-CO-OK K.C.H.O, + iH,0 _ tH(OI-I)-00-OK-^i'=-°^ ^^°- Colorless, semi-transparent, irregular, six-sided prisms, with dihedral summits, belonging to the monoclinie system, or a white, granular powder, of the specific gravity 1.96, and slightly deli- quescent oil exposure to a moist atmosphere. The salt contains one-half molecule (3.83 per cent.) of water of crystallization ; when moderately heated, it malts, and, at a higher temperature, becomes charred and decomposed, with the evolution of empy- reumatic vapors having the odor of burnt sugar ; when strongly ignited at a red heat, it leaves a blackened alkaline residue, con- sisting of a mixture of carbon and potassium carbonate, which effervesces with acids, and imparts a violet color to the non-lumi- nous flame. Potassium tartrate is soluble in 0.7 part of water at 15"' 0. (59° F.), and in 0.5 part of boiling water, yielding a neutral solution, of a mild saline taste ; it is but sparingly soluble in alcohol ; its aqueous solution is decomposed by most acids and acidulous salts, forming, if not too dilute, a white, granular deposit of bitartrate, and yields with argentic nitrate a white precipitate, which be- comes blackened on heating ; the concentrated solution also pro- duces with calcium, barium, and lead salts, white precipitates, which are soluble in dilute nitric acid. Examination -. Potassium and Sodium Tartrate. — One part of the salt when shaken with an equal weight of water must aflibrd a clear and complete solution; an incomplete solution may ind'cate an ad- mixture of Rochelle salt. Such an admixture will also be indi- cated by a greater loss of weight on drying the salt at 100° C. (212° F.), pure Rochelle salt losing at this temperature 19.1 per cent, of its weight; and may be further ascertained by reducing a portion of the potassium tartrate, by ignition in a porcelain crucible, to carbonate, and -then testing the res due in the non- luminous flame, when a persistent bright-yellow color will reveal the presence of sodium ; the filtered solution of the residue may afterwards be tested by mixing it with an equal volume of solu- tion of potassium metantimoniate ; the occurrence of a white, crystalline deposit, at once or after several hours' standing, would indicate an adulteration with potassium and sodium tartrate. Bicarbonate, carbonate, and bitarlrate are recognized in the solu- 502 MANUAL OF CHEMICAL ANALYSIS. tion of the salt, the two former by effervescence on the addition of an acid, and by an alkaline reaction upon turmeric-paper ; the latter by its relatively sparing solubility in cold water, and by an acid reaction upon blue litmus-paper. Ammonium sails will be recognized by the development of the odor of ammonia, when a portion of the salt is heated, in a test- tube, with a strong solution of potassium or sodium hydrate, and by the development of white fumes, when a glass rod, moistened with acetic acid, is held over the mouth of the tube. Calcium salts will be indicated in the solution by a white pre- cipitate on the addition of solution of ammonium oxalate. Sulphate and chloride may be detected in the dilute solution of the salt, when it is slightly acidulated with diluted nitric acid, and then tested, in separate portions, with argentic nitrate for chloride, and with barium nitrate for sulphate. Metallic impurities are recognized in the concentrated solution of the salt, after acidulation with hydrochloric acid and subse- quent filtration, by a dark coloration or turbidity upon saturation with hydrogen sulphide; or, after filtration, if necessary, by sub- sequent neutralization with ammonia-water, and the addition of ammonium sulphide. Estimation : 2.938 grams of the salt are ignited in a porcelain crucible, at a red heat, until gases cease to be evolved; the alkaline residue is then extracted with warm water, the solution filtered into a beaker, a few drops of litmus solution added, and titrated, with the aid of a gentle heat, with a standard solution of oxalic or sul- phuric acid (page 82), as described under potassium carbonate, on pnge 474. The number of cubic centimeters of normal acid solution which is thus required for the exact neutralization of the liquid, when multiplied by 4, will indicate, without further calculation, the percentage purity of the salt. By the employ- ment of other quantities of the salt than precisely that above stated, the calculation may also readily be made, with the consid- eration that one cubic centimeter of the normal acid solution cor- responds to 0.117 gram of pure crystallized potassium tartrate. QUINIDINA. CHINIDINUM SEU CONCHININUM. Quinidine, Quinidia, or Conquinia. Ger. CliinicUn (Concbinin) ; Fr. Quiuidine ; Sp. Quinidiua. C.„H,A03+2H,0; 360. Large, colorless, shining, four-sided prisms, containing 2 mole- cules (10 per cent.) of water of crystallization, and possessing a QUINIDtNA. 50B very bitter taste and a slightly allcaline reaction ; when heated to i20^ C. (248° F.), they lose their water of crystallization, and, when thus deprived of "water, melt at 163° G'. (33i.4° F.), to a colorless liquid, which solidifies in a crystalline form upon cool- ing; at a higher temperature they are decomposed, and when strongly heated on platinum-foil, burn slowly away, leaving no residue. Quinidine is soluble in 2000 parts of water at 15° C. (59° F.), and in 750 parts of boiling water, in 26 parts of alcohol, and 22 parts of ether at 20° 0. (6S° F.), and is also soluble in chloroform, carbon bisulphide, and benzol ; it is freely soluble in water acidu- lated with sulphuric acid, and the solution displays a blue • fluorescence. It neutralizes the acids, with the formation of neutral and acid salts, which are mostly well crystallizable. When exactly neutralized with diluted sulphuric acid, quinidine yields a solution which affords the same reactions as quinidine sulphate, and should respond to the tests for quality and purity, as described under the latter, on pages 503-504. QUINIDIN.ai SULPHAS. CHINIDINUM SEU CONCHININUM SULFURICUM. Sulphate of Quinidine, Quinidia, or Conquinia. Quinidine Sulphate. Ger. Soliwefelsaures Cliinidin ; Fr. Sulfate de quinidine ; Sp. Sulfate de quinidinii. (C,„H,AOAH,SO, + 211,0; 782. White, silky, prismatic needles or tufts, permanent in the air, and containing two molecules (4.6 per cent.) of water of crystalli- zation, which are completely eliminated at 120° C. (248° F.) ; when strongly heated, they burn slowly away, leaving no residue. Quinidine sulphate is soluble in 100 parts of water, and in 8 parts of alcohol at 15° 0. (59° F.) ; in 7 parts of boiling water, and very soluble in boiling alcohol; it is freely soluble in acidu- lated water, and in 20 parts of chloroform at 15° C. (59° F.), but is almost insoluble in ether. The aqueous solution is neutral in its action upon litmus, possesses an intensely bitter taste, and, when acidulated with sulphuric acid, displays a blue fluorescence; with barium chloride it yields a white precipitate, insoluble in hydrochloric or nitric acid, and with chlorine water, followed by the addition of ammonia- water in slight excess, an emerald-green coloration is produced ; if the addition of ammonia- water be pre- ceded by a few drops of a solution of potassium ferrocyanide, the solution assumes a bright-red color. When to a solution of qui- nidine sulphate ammonia-water is added, a white precipitate of 504 MANUAL OF CHEMICAL ANALYSIS. quinidine is produced, which is soluble in a considerable excess of the reagent, and in about thirty times its weight of ether. The neutral aqueous solution of quinidine sulphate yields upon the addition of a concentrated solution of potassium iodide a white granular precipitate of quinidine hydriodate, OjjH^^NjO^.HI, which is very sparingly soluble in water and in alcohol. Examination : Quinine, Ginchonine, and Ginchonidine. — These associate alka- loids of quinidine may readily be detected by the following sim- ple test : 0.5 gram of the quinidine sulphate, together with an equal weight of neutral potassium iodide, is agitated with 10 cubic centimeters of water at about 60° C. (140° F.), the mixture allowed to cool, and stand for an hour, with frequent agitation, . and filtered ; to the filtrate one or two drops of ammonia-water are then added, when not more than a slight turbidity should be produced ; a decided precipitate would reveal the presence of an undue proportion of the above-mentioned associate alkaloids. In consequence of the previously existing confusion in the ap- plication of names, quinidine sulphate is liable to be confounded with the less valuable alkaloid cinchonidine. The admixture or substitution of the latter should therefore be the subject of a special test. It may be detected by its sparing solubility in chloroform, whereas quinidine sulphate is freely soluble in this liquid, and also by the following test: 0.5 gram of the salt is agitated for about half a minute with '60 cubic centimeters of water at 15° C. (59° F.), and immediately filtered ; to the filtrate two or three cubic centimeters of a saturated solution of potas- sium and sodium tartrate (Eochelle salt) are added, when, if any considerable proportion of cinchonidine be present, a white, gran- ular precipitate of cinchonidine tartrate, (CjgH2j]Sr20)2C4H|i05, will gradually be formed. Foreign Alkaloids or Neutral Principles. — An accidental admix- ture or substitution of foreign alkaloids, such as morphine, bru- cine, etc., or of neutral principles, such as salicin, may in most instances be detected by a coloration with concentrated sulphuric or nitric acid, whereas pure quinidine sulphate dissolves without color, or with the production of but a faint yellowish tint. Inorganic impurities may be detected by a non- volatile residue when a little of the salt is ignited upon platinum-foil; or by an insoluble residue, when 0.5 gram of the salt is dissolved in a mixture of 3 cubic centimeters of chloroform and 2 cubic centi- meters of absolute alcohol. QUININA. 505 QUININA. CHININUM. CHINIUM. Quinine. Quinia. Ger. Chinin; Fr. Quinine ; Sp. Quinina. C,„H,A0. + 3H,0; 378. A snow-white, flaky, indistinctly cr3rstalline powder, or minute, needle-lil^e crystals, containing 3 molecules (14.28 per cent.) of water of crystallization, efflorescent on exposure to the air, and possessing an alkaline reaction. It melts at 57° C. (134.6° F.), and on the water-bath retains about 5.25 per cent, (about 1 mole- cule) of water of crystallization, which is completely expelled at 125° 0. (257° ¥.) ; the anhydrous alkaloid then melts at 177° 0. (350.6° F.), dissolves in hot water without previously fusing, and, on cooling, separates in needles ; while the alkaloid, containing water of crystallization, first fuses in boiling water, and, on cool- ing, does not crystallize. When strongly heated on platinum- foil, it becomes charred and decomposed, and is finally completely dissipated. Quinine is soluble in about 1600 parts of water at 15° 0. (59° F.), in 700 parts of boiling water, in 6 parts of cold, or 2 parts of boiling, alcohol, in 22.7 parts of ether,* in about 5 parts of chloroform, and in 200 parts of glycerin ; and is also soluble in carbon bisulphide, benzol, benzin, and ammonia-water; its solutions have a bitter taste, and a feebly alkaline reaction, and neutralize acids, with the formation of crystallizable salts. Qui- nine is free\j soluble in diluted acids, forming solutions which exhibit an azure-blue fluorescence, caused by a change of re- frangibility of the invisible chemical rays ; this property is not displayed, however, by its solution in hydrochloric, hydriodic, or hydrobromic acids, and does not appear in such solutions by the subsequent addition of sulphuric acid; the fluorescence may like- wise be made to disappear in solutions in which it has previously been produced, by the addition of the above-named acids, as also by solutions of chlorides, bromides, and iodides, with the excep- tion of mercuric chloride and bromide. Concentrated sulphuric and nitric acids dissolve quinine without color, or with the pro- duction of but a slight yellowish tint. Solutions of quinine and its salts are precipitated by the alka- line hydrates, carbonates, and bicarbonates, by calcium hydrate, * The solubility of quinine in ether differs according to the form of the alka- loid : requiring less when in the anhydrous or amorphous condition, as when freshly precipitated from its solution in acidulated water by ammonia- water, and directly shaken with ether, than in the crystalline or hydrated form, which it assumes when the precipitate is allowed to stand for several hours, previous to the addition of the ether. 506 MANUAL OF CHEMICAL ANALYSIS. by tannic and picric acids, by potassium ferrocyanide, potassio- mercuric iodide, iodinized potassium iodide, and most alkaloidal reagents; the precipitates with calcium, potassium, and sodium hydrates, and ammonia-water, are redissolved by a large excess of the precipitant. Solutions of quinine and its salts, when mixed with chlorine- water, and afterwards with an excess of water of ammonia, assume a bright emerald-green color (thalleiochin) ; the green color passes into red upon the subsequent addition of potassium ferrocyanide ; this characteristic reaction is most strikingly exhibited when, to the solution of quinine in chlorine-water, the solution of potassium ferrocyanide is first added, and subsequently the ammonia- water. When a solution of quinine or its salts in acidulated water is precipitated with ammonia- water, and the turbid mixture is then divided into three portions in as man}' test-tubes, and these shaken severally with a little ether, chloroform, and benzol, the precipi- tate will be dissolved, and the liquids subside into two clear, col- orless strata in each test-tube. Examination ; The identity of quinine may be conclusively established by the above described physical characters, and its beliavior towards re- agents and solvents ; it is also distinguished from many other alka- loids and crystallizable neutral principles, by affording no special coloration in contact with cold concentrated sulphuric or nitric acid. Quinidine, Ginchonine, and Oinchonidine. — 1 gram of the quinine is triturated in a mortar with 0.5 gram of ammonium sulphate and 5 cubic centimeters of distilled water, and the mixture thor- oughly dried ■ on the water-bath ; the residue (which- should be neutral to test-paper) is agitated with 10 cubic centimeters of dis- tilled water, this mixture macerated at 15° C. (59° F.) for half an hour, then filtered, and to 5 cubic centimeters of the filtrate, in a test-tube, 7 cubic centimeters of ammonid- water, spec. grav. 0.960, are added, without shaking ; on gently turning the test-tube, there should be formed, either at once, or after a short time, a clear liquid ; an ensuing permanent precipitate would indicate an admixture of more than about 1 per cent, of cinohonidine and quinidine, and of more than traces of cinchonine. If the temperature during mace- ration was 16° 0. (60.8° F.), 7.5 cubic centimeters of ammonia- water may be added, and if 17° G. (62.6° F.), 8 cubic centimeters may be employed. Inorganic impurities may readily be detected by a non-volatile residue, when a small portion of the quinine is strongly heated on platinum-foil. When dissolved in dilute sulphuric acid, quinine sliould respond to the tests of purity for quinine sulphate, as described under the latter, on pages 521-523. QUININA. 507 Fig. 153. Estimation of the Alkaloids in Cinchona-Barks : The therapeutical value of the cinchona-barks is due to the alka- loids contained in the bark, of which the principal ones are qui- nine, quinidine, cinchonine, and cinchonidine. The estimation of the oomraeroial value, therefore, depends upon the determination of the quantity of these alkaloids, and in particular of the first one, in a known weight of the bark. Of the numerous methods employed for this purpose, the following ones are simple, expe- ditious, and reliable : I. Fliiokiger's Process : From a large number of pieces of the bark, small fragments are cut and reduced to a fine powder, so as to represent as nearly as possible an average specimen of the bark to be examined ; 20 grams of the powder, contained in a porcelain capsule, are moist- ened with ammonia-water, and, after standing for an hour, mixed with 80 grams of hot water ; it is then allowed to cool, subsequently intimately mixed with milkof lime(prepared by triturating 5 grams of dry caustic lime with 50 grams of water), and the mixture evapo- rated upon the water -bath until it is uniformly converted into small, somewhat moist, crumb-like particles. This is then transferred to a cylindrical glass tube (Fig. 153), which at A is 2.5 centimeters (1 inch) wide, and from A to B IQ centimeters ((5.4 inches) long. At B a small brass sieve is insserted, upon which a disk of filtering paper is secured by means of a bunch of loose cotton. The powder having been quite com- pactly adjusted upon the cotton, it is again covered at A, as in B, with a little cotton ; the latter having been previously employed for removing the last traces of the powdered bark from the capsule. At JS, a tightly fitting cork is inserted, which is pene- trated by the tube R, and connected with an inverted small glass condenser. The lower end of the appa- ratus, C, is tightly connected by means of 9. cork with the flask JT, containing about 100 cubic centi- meters of ether. The flask is then heated by means of a constant water-bath ; and in the same degree as the vapors of ether are expelled through B, the}'- become again condensed in the condenser, drop through the tube /? upon the powder at A, penetrate the entire column of powder A B, and flow at C, saturated with alkaloid, into the flask K. To effect the complete exhaustion of the bark by the ether, the operation of displacement should be continued for nearly a day, but when once in progress it requires but little attention. In order to determine whether the bark is completely exhausted, a few drops of the ether, falling at C, are collected in a small test-tube, and tested with potassio-mercuric 508 MANUAL OF CHEMICAL ANALYSIS. iodide ; which should afford no turbidity if the process of extrac- tion has been sufficiently long continued. When this is accom- plished, 36 cubic centimeters of one-tenth normal hj-^drochloric acid (3.65 grams HOI in 1 liter) are added to the ether in the flask K, the ether distilled off", and subsequently so much hydrochloric acid added as may be required to impart to the liquid an acid reaction. The liquid is then filtered from the separated mixture of fat, chinovin, and chlorophyll, and, after having become thoroughly cooled, 40 cubic centimeters of one-tenth normal sodium hydrate solution (4 grams NaOH in 1 liter) are added, and the whole allowed to repose until the precipitate has sub- sided, and the supernatant liquid has become perfectly clear. Sodium hydrate is then gradually added to the liquid as long as a precipitate continues to be produced, for which purpose a solution of the spec. grav. 1.3 is the most serviceable. The precipitated alkaloids are afterwards collected on a filter, and gradually washed with a little cold water until a few drops of the washings, when allowed to flow on the surface of a cold, saturated, neutral, aqueous solution of quinine sulphate, cease to produce a turbidity. The drained precipitate, contained on the filter, is then gently pressed between bibulous paper, and dried by exposure to the air ; it may afterwards readily be removed from the paper without loss, and, after thoroughly drying upon a watch-glass over sulphuric acid, is finally dried at 100° C. (212° F.), and weighed ; the weight of the precipitate, multiplied by 5, will give the total percentage of mixed alkaloids in the bark. If it be de- sired to establish the presence of quinine in the precipitate, a small portion of it may be dissolved in acidulated water, and sub- sequently tested with chlorine- water and amfnonia, as described on page 506. Separation of the Alkaloids. When the separation and quantitative estimation of the re- spective alkaloids are required, the following method of De Vrij may be employed. The powdered mixed alkaloids are treated with ten times their weight of ether, and, after agitation, left at rest till the next day. By this operation the alkaloids are sepa- rated into two parts, viz., one (A) soluble in ether, and another (B) insoluble in that liquid. The part soluble in ether contains the quinine and the amorphous alkaloid, together with traces of quinidine, while the insoluble part contains the cinchonine, cin- chonidine, and quinidine. These two parts are separated by filtration, the insoluble portion washed with a little ether, and the ethereal solution either directly evaporated, or the ether recov- ered by distillation. A. Part Soluble in Ether. — The ether having been evaporated, and the residue dried at 100° C. (212° F.), this may in many QUININA. 509 cases be practically considered as consisting simply of quinine. If, however, the estimation of the quinidine and amorphous alka- loid is required, the residue is dissolved in sufficient acetic acid to afford a neutral solution, and an alcoholic solution of potassium iodide added, which will produce a sandy precipitate of quinidine hydriodate,* C^oHj^NjOj.HI. One part of this hydriodate, when dried at 100° C. (212° F.), represents 0.717 part of anhydrous qui-- nidine. To the warmed filtrate from the latter precipitate ammo- nia-water is added until it ceases to produce a precipitate; the mixture is then shaken at once with ether, the ethereal solution allowed to evaporate, and the residue dried at 100° 0. (212° F.). This residue will consist principally of quinine, accompanied pos- sibly by amorphous alkaloid and quinamine. In order to exclude the latter bases, which are always only present in very small amount, the ethereal residue is dissolved in 10 parts of diluted alcohol, spec. grav. 0.915, the solution exactly neutralized with alcoholic sulphuric acid, and as much of the latter afterwards added as was required for neutralization. To this solution an alcoholic solution of iodine is carefully added until a precipitate ceases to be formed. If a considerable amount of quinine is present, there will appear immediately a black precipitate of quinine iodo-sulphate or herapathite, but if the amount of quinine is only very small, it may happen that no precipitate will be formed at once, and in the latter case only a small amount of iodine should be added, and the liquid, after having been well stirred with a glass rod, is left at rest till the next day. If qui- nine is really present, it will then be precipitated in the form of herapathite, which may be collected on a filter, washed with strong alcohol, and first dried upon bibulous paper and afterwards at 100° C. (212° F.). One part of the herapathite, when thus dried, represents, in accordance with the formula (CjoH^^N^Oj)^ -f 3H2SO^-f-2HI-|-4I, 0.55 part of pure quinine. To the liquid separated from the herapathite, a few drops of sulphurous acid are added, whereby the iodo-sulphate of amor- phous alkaloid is converted into hydriodate, and the reddish- brown color of the solution disappears. The solution is then carefully neutralized with sodium hydrate, heated on the water- bath to expel the alcohol, and a solution of sodium hydrate in slight excess subsequently added, by which the amorphous alka- loid will be precipitated, including quinamine if present. B. Part Insoluble in Ether. — This is converted into neutral acetate by the addition of a sufficient quantity of acetic acid, and to the solution potassium and sodium tartrate (Eochelle salt) in slight excess is subsequently added. After stirring with a glass * If only traces of quinidine be present, as is usually the case, no precipitate will be formed; but simply white strise on the surfaces of the glass which have come in contact with the glass rod. 510 MANUAL OF CHEMICAL ANALYSIS. rod, the solution is left at rest for a day, when, if cinch ouidine is present in appreciable quantity, its tartrate will be separated in a crystalline form, while the other tartrates remain dissolved. The cinchonidine tartrate is collected on a filter, washed with a little cold water, and, after first drying upon bibulous paper, is finally dried at 100° C. (212° F.), and weighed. One part of cin- chonidine tartrate represents, in accordance with the formula (C,oH22N20)2.0,B[„05, 0.796 part of pure cinchonidine. To the filtrate from the latter precipitate, a solution of poias- sium iodide is added, and the whole well stirred with a glass rod. The quinidine will thus be precipitated as hydriodate, in the form of a sandy crystalline powder ; it is collected on a filter, washed with a little cold water, and. after first drying on bibulous paper, is finally dried at 100° C. (212° F.), and weighed. One part of this hydriodate represents 0.717 part of pure anhydrous quinidine. The filtrate from the quinidine hydriodate is finally precipitated with sodium hydrate, whereby the cinchonine is obtained ; this is collected on a filter, washed with a little cold water, and, after first drying between laibulous paper, is finally dried at 100° C. (212° F.), and weighed. II. Squibb's Process : To 1.25 grams (19.29 grains) of well-burnt lime, contained in a lO-centimeter (4-inch) capsule, 30 cubic centimeters (1 fluidounce) of hot water are added, and, when the lime is slaked, the mixture is stirred, and 5 grams (77.16 grains) of the powdered cinchona are added, the mixture very thoroughly stirred, and digested in a warm place for a few hours, or over night. The mixture is then dried at a low temperature on a water-bath, rubbed to powder in the capsule, and transferred to a flask of 100 cubic centimeters (3.3 fluidounces) capacity, and 25 cubic centimeters (0.8 fluidounce) of amylic alcohol added. The flask is afterward corked, and digested in a water-bath at a boiling temperature and with fre- quent, vigorous shaking for four hours. It is then allowed to cool, and 60 cubic centimeters (2 fluidounces) of stronger ether, spec. grav. 0.728, added, and again shaken vigorously and fre- quently! during an hour or more. The liquid is now filtered through a double filter of 10 centimeters (4 inches) diameter into a flask of 150 cubic centimeters (5 fluidounces) capacity, and the residue transferred to the filter. The flask is rinsed and the rinsings brought on to the filter with a mixture of 10 volumes of amylic alcohol and 40 volumes of stronger ether, and the residue on the filter percolated witli 15 cubic centimeters CO. 5 fluidounce) of the same mixture, added drop by drop from a pipette to the edges of the filter and surface of the residue. The residue is afterward returned to the flask from whence it came, 30 cubic centimeters (1 fluidounce) of the amylic alcohol and ether mix- ture added, shaken vigorously for five minutes or more, and the QniNINA. 511 whole returned to the filter, and the residue again percolated with 15 cubic centimeters of the menstruum, applied drop by drop from a pipette, as before. The filter and residue are now put aside in order that it may be afterward tested in regard to the degree of exhaustion. The ether is now boiled off from the filtrate in the flask by means of a water-bath, taking great care to avoid the ignition of the ether vapor, and also to avoid explosive boiling, by having a long wire in the flask. When boiled down as far as practicable in the flask, the remainder is transferred to a tared capsule of 10 centimeters (4 inches) diameter, and the evaporation continued on a water-bath until the contents are reduced to about 6 gramvS (92 grains). This is transferred to a flask of 100 cubic centimeters (3,3 fluidounces) capacity, rinsing the capsule with not more than 4 cubic centimeters (64 minims) of amy lie alcohol, and adding the same to the contents of the flask. 6 cubic centimeters (96 minims) of water and 4 cubic centimeters (64 minims) of normal solution of oxalic acid are then added, and the mixture shaken vigor- •ously and frequently during half an hour. The mixture, while intimately well mixed, is poured on to a well-wetted double filter of 12 centimeters (4.76 inches) diameter, and the aqueous solution filtered from the aiiiylic alcohol into a tared capsule of 10 cen- timeters (4 inches) diameter. The filter and contents are washed with 5 cubic centimeters (80 minims) of water, applied drop by drop from a pipette to the edges of the filter and surface of the amylic alcohol. The amylic alcohol is then poured back into the flask over the edge of the filter and funnel, rinsing the last por- tion in with a few drops of water. 10 cubic centimeters (160 minims) of water and 1 cubic centimeter (16 minims) of normal solution of oxalic acid are now added, again shaken vigorously for a minute or two, and the whole returned to the wetted filter, and the aqueous portion filtered off into the capsule with the first portion. The amylic alcohol is again returned to the flask, and the washings repeated with the same quantities of water and nor- mal oxalic acid solution. When this has drained through, the filter and contents are washed with 5 cubic centimeters (80 minims) of water, applied drop by drop from a pipette. The total filtrate in the capsule is evaporated on a water-bath, at a low tem- perature, until it is reduced to about 15 grams (241 grains) and this transferred to a flask of 100 cubic centimeters (3.3 fluidounces) capacity, rinsing the capsule with 5 cubic centimeters (80 minims) of water, and adding this to the contents of the flask. 20 cubic centimeters (0.66 fluidounce) of purified chloroform are now first added, and then 6.1 cubic centimeters (98 minims) of normal solu- tion of sodium hydrate, and shaken vigorously for five minutes or more. While still intimately mixed by the shaking, the mix- ture is poured upon a filter of 12 centimeters (4.75 inches) diam- eter, well wetted with water. When the aqueous solution has 512 MANUAL OF CHEMICAL ANALYSIS. passed throngli, leaving the chloroform on the filter, the filter and chloroform are washed with 5 cubic centimeters (80 minims) of water, applied drop by drop. The chloroform solution is then, by making a pin-hole in the point of the filter, transferred to another filter of 10 centimeters (4 inches) diameter, well wetted with chloroform, and placed over a tared flask of 100 cubic cen- timeters (3.3 fluidounces) capacity. The watery filter is washed through into the chloroform-wet filter with 5 cubic centimeters (80 minims) of purified chloroform, and, when this has passed through into the flask, the chloroform-wet filter is also washed with 5 cubic centimeters (80 minims) of chloroform, applied drop by drop to the edges of the filter. When the whole chloroform solution of alkaloids is collected in a flask, the chloroform is boiled off to dryness in a water-bath, when the alkaloids will be left in warty groups of radiating crystals, adhering over the bot- tom and sides of the flask. The flask is then placed on its side in a drying-oven, and dried at 100° C. (212° JF.) to a constant weight. The Aveight of the contents, multiplied by 20, gives the percentage of the total alkaloids of the cinchona in an anhydrous condition, to within 0.1 or 0.2 per cent., if the process has been well managed. Estimation of Quinine. Into the flask containing the total alkaloids, after these have been weighed, are placed 5 grams (78 grains) of glass, which has been ground up in a mortar to a mixture of coarse and fine powder, and 5 cubic centimeters (80 minims) of stronger ether added. The flask is then corked, and shaken vigorously until, by means of the glass, all the alkaloids have been detached from the flask and ground up in the presence of the ether into fine particles. In this way the definite quantity of ether which is large enough to dissolve all the quinine that could possibly be present, becomes entirely saturated with alkaloids in the propor- tion of their solubility, and the solution will necessarily embrace all the very soluble ones as the quinine. Two test-tubes are now marked at the capacity of 10 cubic centimeters (160 minims each), and a funnel and filter of 7 centi- meters (2.8 inches) diameter placed over one of them. The filter is well wetted with ether, and the mixture of alkaloids, ether, and glass poured on to it from the flask. The flask is rinsed out two or three times on to the filter with fresh ether, the filter then washed, and the glass percolated with fresh ether, applied drop by drop from a pipette, until the liquid in the test-tube reaches the 10-cubic- centimeter (160-miniin) mark. The funnel is then changed to the other test-tube, and the washing and percolation with ether continued until the mark on the second test-tube is QUININA. 513 reached by the filtrate. The contents of the two test-tubes are poured into two small tared capsules, evaporated to a constant weight, and weighed. The first capsule will contain what may be called the ether-soluble alkaloids, and if from the weight of these the weight of the residue in the second capsule be sub- tracted, the remainder will be the approximate weight of the quinine extracted from the 5 grams of bark. These weights, multiplied by 20, will give the percentage of ether-soluble alka- loids and of quinine. III. Process of the United States Pharmacopoeia : 1. For Total Alkaloids. Twenty grams of the cinchona, in very fine powder, and fully dried at 100° C. (212° F.), are thoroughly mixed with 5 grams of lime which has previously been made into a milk with 50 cubic centimeters of distilled water, and the mixture completely dried at a temperature not above 80° C. (176° F.). The dried mixture is digested with 200 cubic centimeters of alcohol, in a flask, near the temperature of boiling, for one hour, and, when cool, the mixture poured upon a filter of about 15 centimeters (6 inches) diameter. The flask is rinsed and the filter washed with 200 cubic centimeters of alcohol, used in several portions, and allowing the filter to drain after the use of each portion. To the filtered liquid enough diluted sulphuric acid is added to render the liquid acid to test-paper, any resulting precipitate (calcium sulphate) allowed to subside, the liquid decanted, in portions, upon a very small filter, and the residue and filter washed with small portions of alcohol. The filtrate is then distilled or evapo- rated to expel all the alcohol, allowed to cool, passed through a small filter, and the latter washed with distilled water slightly acidulated with diluted sulphuric acid, until the washings are no longer made turbid by solution of sodium hydrate. To the fil- tered liquid, concentrated to the volume of about 50 cubic centi- meters, when nearly cool, enough solution of sodium hydrate is added to render it strongly alkaline. The precipitate is col- lected on a wetted filter^ allowed to drain, and washed with small portions of distilled water (using as little as possible), until the washings give but a slight turbidity with test solution of barium chloride, and the filter drained by laying it upon blotting or filter papers until it is nearly dry. The precipitate is then carefully detached from the filter, and transferred to a weighed capsule; the filter is washed with dis- tilled water acidulated with diluted sulphuric acid, the filtrate made alkaline with solution of sodium hydrate, and, if a precipi- tate results, this is washed on a very small filter, allowed to drain well, and also transferred to the capsule. The contents of the latter are now dried at 100° 0. (212° F.) to a constant weight, 33 514 MANUAL OF CHEMICAL ANALYSIS. cooled in a desiccator, and ■weighed. The number of grains, mul- tiplied by 0, equals the percentage of total alkaloids in the cin- chona. 2. For Quinine. To the total alkaloids from 20 grams of cinchona, previously weighed, distilled water acidulated with diluted sulphuric acid is added, until the mixture remains for 10 or 15 minutes after diges- tion just distinctly acid to test-paper. It is then transferred to a weighed beaker, rinsing with distilled water, and adding of this enough to make the whole weigh 70 times the weight of the alka- loids. Solution of sodium hydrate, previously well diluted with distilled water, is now added, in drops, until the mixture is exactly neutral to test-paper, digested at 60° C. (140° F.), for 5 minutes, then cooled to 15° G. (59° F.), and maintained at this temperature for half an hour. If crystals do not appear in the glass vessel, the total alkaloids do not contain over 8 per cent, of their weight of quinine (corresponding to 9 per cent, of crystallized sulphate of quinine). If crystals appear in the mixture, the latter is passed through a filter not larger than necessary, prepared by drying two filter papers of 5 to 9 centimeters (2 to 3.5 inches) diameter, trimming them to an equal weight, folding them separately, and placing one within the other so as to make a plain filter four-fold on each side. When the liquid has drained away, the filter and contents are washed with distilled water of a temperature of 15° C. (59° F.), added in small portions, until the entire filtered liquid weighs 90 times the weight of the alkaloids taken. The filter is then dried, without separating its folds, at 60° C. (140° F.), to a constant weight, allowed to cool, and the inner filter and contents weighed, taking the outer filter for a counter-weight. To the weight of effloresced quinine sulphate so obtained, 11.5 per cent, of its amount is added (for water of crystallization"), and 0.12 per cent, of the weight of the entire filtered liquid added (for solubility of the crystals at 15° C, or 59° F.). The sum in grams, multiplied by 5, equals the percentage of crystallized quinine sulphate equiva- lent to the quinine in the cinchona. IV. Process of the Fharmacopoea Germanioa : Twenty grams of the finely powdered bark are repeatedly and actively agitated with a mixture of 10 grams of ammonia-water, spec. grav. 0.960, 20 grams of alcohol, spec. grav. 0.830 to 0.834, and 170 grams of ether, spec. grav. 0.724 to 0.728, and, after standing for a day, 120 grams of the liquid are poured off". After the addition of 3 cubic centimeters of normal hydrochloric acid ^containing 36.5 grams HCl in 1 liter), the ether is removed by distillation or evaporation, and, if necessary, so much hydrochloric acid added as is required to acidulate the solution.* This is then * In consequence of the small amount of liquid obtained after the removal of the alcohol and ether, Prof. Fliickiger suggests that the solution be evaporated QUININA. 515 filtered, and the cooled liquid mixed with 3.5 cubic centimeters of normal solution of potassium hydrate (page 87). After the alka- loids have separated, solution of potassium hydrate is added to the clear supernatant liquid, until no further precipitate is pro- duced. The entire precipitate is finally collected upon a filter, and gradually washed with a little water until the drops of liquid escaping from the filter, when allowed to fall upon the surface of a saturated neutral solution of quinine sulphate in cold water, no longer produce a turbidity. After being allowed to drain, the alkaloids are gently pressed between bibulous paper, then dried by exposure to the air sufficiently to admit of bringing them into a glass capsule, in which they are placed over sulphuric acid, and finally completely dried in a water-bath. QXTININiE HTDROBROMAS. CHININUM SEU CHINITIM HYDROBROMICUM SEU H YDROBROMAT UM. Sydrobromate of Quinine or Quinia. Quinine Hydroir ornate. Ger. Bromwasserstoffsaures Chinin ; Fr. Hydrobromate de quinine ; Sp. Hromhidrato de quinina. C,„H,,NA-HBr -f 2H,0 ; 440.8. Colorless, lustrous, prismatic, or needle-shaped cr^'stals, con- taining two molecules (8.16 per cent.) of water of crystallization ; they are permanent in ordinary air, but efflorescent in a warm atmosphere; when exposed to a moderate heat the salt fuses, and, when strongly heated, burns slowly away, leaving no residue. Quinine hydrobromate is soluble in about 16 parts of water, and in 3 parts of alcohol at 15° 0. (59° F.); in 1 part of boiling water, and in less than 1 part of boiling alcohol ; in 6 parts of ether, in 12 parts of chloroform, and moderately soluble in glyce- rine. The aqueous solution possesses a very bitter taste, is neu- tral in its action upon litmus, and, when acidulated with sulphuric acid, displays a blue fluorescence ; if chlorine- water be added to the solution, and subsequently ammonia-water in excess, a bright emerald-green coloration is produced. The aqueous soltition of quinine hydrobromate, if not too dilute, yields with ammonia-water a white precipitate of quinine, which is readily dissolved by an excess of the precipitant, or when to dryness, and the hydroclilorates of the alkaloids again taken up with 30 cubic centimeters of warm water, or, preferably, to apply originally 30 cubic centi- meters of decinormal hydrochloric acid, and by distilling off the alcohol and ether to concentrate (he liquid to 30 cubic centimeters In all cases the alcohol and ethei- should be completely removed before the addition of the potassa solution. 516 MANUAL OF CHEMICAL ANALYSIS. mixed and agitated with ether; with argentic nitrate it yields a white precipitate of argentic bromide, which, when collected, and washed with a little water, is insoluble in diluted nitric acid, or in a solution of ammonium carbonate. Examination ; With reference to its mode of preparation, quinine hydrobro- mate should be examined for its possible contamination with qui- nine sulphate, or with barium bromide, by acidulating its aqueous solution with nitric acid, and subsequently testing, in separate portions, with barium chloride for the former, and with diluted sulphuric acid for the latter. If either of these impurities are found, it will, of course, exclude the presence of the other. Water.- — The presence of free water may be ascertained by the determination of the- loss of weight upon drying 1 gram of the salt at the temperature of 100" C. (212° F.) until its weight remains constant. When dried at this temperature the residue should weigh not less than 0.918 gram, otherwise an undue per- centage of water is indicated. Quinidine, Cinchonine, and Ginchonidine. — One and one-half grams of the salt are dissolved in 15 cubic centimeters of hot dis- tilled water, the solution stirred with 0.6 gram of crystallized sodium sulphate in powder, the mixture maintained at 15° C. (59° F.) for half an hour, and then drained through a filter just sufficiently large to contain it until 5 cubic centimeters of filtrate are obtained. Upon proceeding further, as directed under Qui- nina, on page 506, the results there stated should be obtained. The further examination of quinine hydrobromate for other foreign organic or inorganic substances or alkaloids is the same as described under Quininm Sulphas, on pages 522, 523. QUININiE BISULFHAS. CHININUM BISULFURICUM. CHININUM SEU CHINIUM SULPURICUM ACIDUM. Bisulphate of Quinine or Quinia. Acid Sulphate of Quinine. Quinine Biaulpliate. Ger. Sauies Schwefelsauros Clilnin ; Fr. Sulfate acide de quinine ; Sp. Bisulfato de quinina. C,„H,,N,0,.H,S0,+7H,0; 548. Colorless, transparent, prismatic crystals, belonging to the rhom- bic system, or small needles, efflorescent, and assuming an opaque whiteness on exposure to the air. The salt contains 7 molecules (22.99 per cent.) of water of crystallization, which are lost by drying at 100° 0. (212° F.); when thus deprived of water, and heated in a small porcelain capsule, it melts at 135° C. (275° F.), QUININA. 517 and is converted into quinicine bisulphate ; at a higher tempera- ture, it becomes yellow, then red, and is finally carbonized with the evolution of reddish vapors ; when strongly heated on plati- num-foil, it burns slowly away, leaving no residue. Quinine bisulphate is soluble in about 10 parts of water and in 32 parts of alcohol at 15° C. (59^ F.), and very freely soluble in boiling water and in boiling alcohol. Its aqueous solution pos- sesses an intensely bitter taste and an acid reaction, and displays a vivid blue fluorescence; with barium chloride it gives a white precipitate, insoluble in hydrochloric acid, and with chlorine- water followed by the addition of ammonia, a bright emarald- green color is produced ; when ammonia-water is added to the solution, a precipitate is produced which is readily soluble in an excess of the precipitant, as also when mixed and agitated with ether. If to a solution of 1 part of quinine bisulphate in 20 parts of acetic acid and 5 parts of alcohol, a few drops of a saturated alco- holic solution of iodine are added, a precipitate of quinine iodo- sulphate, (C^^Hsj^N^Oj)^-!- 3HjSO^-f-2HI + 4I, or herapathite, will be produced ; this compound forms thin laminar crystals or groups of stellate needles, of a bright green color and metallic lustre, and is very sparingly soluble in water and in alcohol. Examination : Water. — The presence of free water may be ascertained by the determination of the loss of weight upon drying 1 gram of the salt at the temperature of 100° C. (212° F.) until its weight re- mains constant. "When dried at this temperature, the residue of anhydrous quinine bisulphate so obtained should weigh not less than 0.77 gram, otherwise an undue percentage of water is indi- cated. Quinidine, Cinchonine, and Ginchonidine. — One gram of quinine bisulphate, previously dried at 100° C. (212° F.), is agitated with 8 cubic centimeters of distilled water, the mixture made exactly neutral to test-paper by the cautious addition of ammonia-water, and the volume of liquid increased to the measure of 10 cubic centimeters by the addition of distilled water. The mixture is then macerated at 15° C. (59° F.) for half an hour, when, upon proceeding further as directed under Quinina^i on page 506, the results there stated should be obtained. The further examination of quinine bisulphate for other foreign organic or inorganic substances or alkaloids is the same as de- scribed under Quininx Sulphas, on pages 522, 523. 518 MANUAL OF CHEMICAL ANALYSIS, QUININE HyDROCHLORAS. QUINI^ MURIAS. CHININUM SEU CHINIUM HYDROCHLORICUM SEU HYDROCHLORATUM Mydroehlorate of Quinine or Quinia. Quinine Hydrochlorate. Ger. Chlorwassei'stoflFsaurea Chiniii ; Fr Hydrochlorate de quinine ; Sp. Clorliidrato de quiuina. C,„H,,NA-HC1 + 2H,0; 396.4. White, silky needles, or a crystalline powder, containing two molecules (9.08 per cent.) of water of crystallization ; it is perma- nent at ordinary temperatures, but slightly efflorescent in a warm atmosphere; when heated to from 100 to 110° C. (212 to 230° F.) it loses its water of crystallization, fuses at a higher temperature, and, when strongly heated on platinum-foil, burns slowly away, leaving no residue. Quinine hydrochlorate is soluble in 34 parts of water and in 3 parts of alcohol at 15° C. (59° F.) ; in 1 part of boiling water, and very soluble in boiling alcohol ; and also soluble in 9 parts of chloroform, in the latter instance accompanied by the separation of water ; if, however, the salt be previouslj' rendered anhydrous by gently heating, it requires but its own weight of chloroform for solution. The salt is also freely soluble in acidulated water, and in diluted as well as in concentrated acids, without change of color ; its aqueous solution is neutral, possesses a bitter taste, and, when sufE-ciently diluted, displays a slight blue fluorescence on the addition of dilute sulphuric acid ; with chlorine-water, fol- lowed by the addition of ammonia-water in excess, it affords a bright emerald green coloration, and if the ammonia-water is preceded by the addition of a few drops of a solution of potas- sium ferrocyanide, a red color is produced ; the aqueous solution, acidulated with nitric acid, yields a white, curdy precipitate with argentic nitrate, soluble in an excess of ammonia-water, and a white precipitate with ammonia-water, which, however, is dis- solved by ether, alcohol, chloroform, or benzol, when added and agitated with the liquid. Examination : Water. — The presence of free water may be ascertained by the determination of the loss of weight upon drying 1 gram of the salt at the temperature of 100° C. (212° F.) until its weight re- mains constant. When dried at this temperature, the residue should weigh not less than 0.91 gram, otherwise an undue per- centage of water is indicated. Quinidine, Cinchonine, and Ginchonidine. — These associate alka- loids of quinine may readily be detected by Hesse's test, as de- scribed under Quininse Sulphas, on page 521. In the application of the test, 0.5 gram of quinine hydrochlorate and 0.25 gram of QIIININA. 519 crystallized sodium sulphate are added lo 10 cubic oeotitneters of water at 50-60° C. (122-140° F.), contained in a test-tube ; the mixture is well shaken several times, and, after standing for ten minutes, 5 cubic centimeters of the clear filtered solution are introduced into a graduated tube (Fig. 154, page 521), 1 cubic centimeter of ether is added, and subsequently 5 drops of ammo- nia-water, spec. grav. 0.960. The tube is now closed with a cork, is agitated gently, and allowed to stand for several hours. If the ethereal layer is now examined with a lens, it should show no evidence of crystals; the separation of crystals being evidence of the presence of more than traces of the above-mentioned associate alkaloids. The detection of an admixture of the above-mentioned alka- loids may also be accomplished by the following method: 0.3 gram of the quinine hydrochlorate is agitated with 6 cubic centi- meters of distilled water, the mixture macerated at 15° C. (59° F.) for half an hour, and filtered ; 4 cubic centimeters of the fil- trate are then diluted with 100 cubic centimeters of distilled water, and of the diluted solution 5 cubic centimeters are taken in a test-tube, and 7 cubic centimeters of ammonia-water, spec, grav. 0.960,- added, without shaking; on gently turning the tube, closed by the finger, there should be formed, either at once, or after a short time, a clear liquid ; an ensuing turbidity would indicate an admixture with the above-mentioned associate alka- loids of quinine. In consequence of the occasional occurrence of an accidental admixture or substitution of morphine hydrochlorate, the latter salt may also be tested for. It may readily be detected in the aqueous solution of the salt, by agitating it with a few drops of a solution of iodic acid, when, if morphine be present, iodine will be liberated, and upon subsequent agitation with a few drops of chloroform or carbon bisulphide, the characteristic violet color will be imparted to these liquids. The same reducing action may also be shown, by adding to the solution of the salt a few drops of a solution of potassium ferricyanide and ferric chloride, and subsequently hydrochloric acid in slight excess, when, in the' pre- sence of morphine, a deep-blue coloration or precipitate will be produced. The presence of morphine, as also of many other foreign alka- loids or neutral principles, will likewise be indicated by a red or dark coloration in contact with concentrated nitric or sulphuric acid, whereas pure quinine hydrochlorate affords no coloration, or but a pale yellowish tint is produced. With reference to the method of its preparation, its aqueous solution needs, moreover, to be examined for contamination with quinine sulphate or with barium chloride, by acidulation with nitric acid, and subsequent testing, in separate portions, with barium nitrate for the former, and with diluted sulphuric acid 520 MANTTAL OF CHKMICAL ANALYSIS. for the latter. Either of these impurities, of course, excludes the presence of the other, without impairiug the solubility of the salt. The further examination of quinine hydrochlorate for quality and purity is the same as that of quinine sulphate, as described on pages 522, 523. QUININiE SULPHAS. CHININUM SEU CHINIUM SULPURICUM. Sulpliate of Quinine or Quinia. Quinine Sulphate. Ger. Scliwefclsauies Chinin ; Fr. Sulfate de quinine ; Sp. Sulfate de quinina. (C,„H,A0,)AS0,-|-7H,0; 872. Fine, silky, slightly flexible, snow-white needles, interlaced among one another, or grouped in small, star-like tufts ; the crys- tals contain seven molecules (14.45 per cent.) of water of crystal- lization, five of which (corresponding to 9.85 per cent.) are lost by long exposure to a warm and dry atmosphere, or more readily at a temperature of 50 to 60° C. (122 to 140° F.), while the re- maining two molecules (4.6 per cent.) are slowly expelled at a temperature of 100 to 115° C. (212 to 239° F.), and are again rapidly absorbed by exposure to the air; at a higher tempera- ture, crystallized quinine sulphate melts without decomposition, and, when strongly heated, becomes red, with the evolution of reddish vapors, becoming finally, upon ignition with access of air, slowly but wholly dissipated. Quinine sulphate is soluble in 740 parts of water and in 65 parts of alcohol at 15° G. (59° F.) ; in about 30 parts of boiling water, and in about 3 parts of boiling alcohol ; in 40 parts of glycerin, in 1000 parts of chloroform, and very sparingly soluble in ether; it is very freely soluble in dilute or strong acids, form- ing colorless, bitter solutions, and its solution in sulphuric acid, when diluted, exhibits a bright blue fluorescence. Solutions of quinine sulphate are precipitated by the alkaline hydrates, carbonates, and bicarbonates, by lime-water, by tannic and picric acids, by potassium ferrocyanide, and by potassio-rner- curic iodide. The precipitates with calcium hydrate and with the alkaline hydrates are soluble in an abundance of the precipi- tant. Its solution in dilute hydrochloric acid gives, upon the addition of a solution of barium chloride, a white precipitate of barium sulphate, insoluble in nitric or hydrochloric acids. Like all quinine salts, quinine sulphate affords an emerald- green color, Avhen to its dilute solution chlorine-water, and subsequently ammonia-water, in slight excess, are added ; if the addition of ammonia-water be preceded by a few drops of a solu- tion of potassium ferrocyanide, a red color will be produced. QUININA. 521 Fia. 154. n I 1 If, to a solution of 5 parts of quinine sulphate in 250 parts of warm alcohol, 2 parts of dilute sulphuric acid, and subsequently a solution of 2 parts of iodine in 20 parts of alcohol are gradu- ally added, a precipitate of quinine iodo-sulphate, or herapathite, (C;H,,N,0,), + 3H,S0, + 2HH-4I + 3H,0, will be produced. This compound is almost insoluble in water or cold alcohol, and, when crystallized from boiling alcohol, forms small laminse, with a green, metallic lustre. » Examination : Water. — An undue proportion of water, with which the salt may have been moistened for the purpose of increasing its weight, ma}'' be detected by determining the loss of weight when dried at 100° C. (212° P.). One gram of the well-mixed salt, when dried at this temperature until the weight remains constant, should afford a residue weighing not less than 0.838 gram ; a greater loss of weight will indicate the presence of more than 8 molecules of water. Quinidine, Ginchonine, and Cinchonidme Sul- phates. — These associate alkaloids of quinine may readily be detected by the application of Hesse's test, which is based upon the fact that water at 50-60° 0. (122-140° F.) dissolves quinine sul- phate but sparingly, while the sulphates of the other alkaloids are readily dissolved, and also that when the cooled solution, after supersaturation with ammonia-water, is shaken with a quantity of ether which is sufficient to dissolve all the qui- nine present, this quantity of ether is not sufficient to dissolve the other alkaloids if they exceed cer- tain limits. For executing this test a simple test-tube of the size represented in Fig. 154 may be employed. The internal diameter of the tube is about 1 centi- meter, and its height 12 centimeters. It is pro- vided with the marks B and 0. The space below B (to A in the figure) has the capacity of 5 cubic centimeters, and the space between the lines B and the capacity of 1 cubic centimeter. The application of the test is as follows : 0.5 gram of quinine sulphate and 10 cubic cen- timeters of water at 50-60^ C. (122-140° F.) are shaken together in a test-tube several times. After standing for ten minutes, 5 cubic centimeters of the cooled and clear filtered solution are introduced into the graduated tube, 1 cubic centimeter of ether is added, and subsequently 5 drops of I 1 J V^./, 522 MANUAL OF CHEMICAL ANALYSIS. ammonia- water, spec. grav. 0.960. The tube is now closed with a tightly-fitting cork, is agitated gently, and allowed to stand for several hours ; if the ethereal layer is now examined with a lens, it should show no evidence of crystals. The absence of crystals under the conditions named is evidence, of sufficient purity ; but the salt may still contain 0.25 per cent, of cinchonine sulphate, 0.5 per cent, of quinidine sulphate, and about 1 per cent, of cinchonidine or homocinchonidine sulphates. If these alkaloids are present in larger quantities, crystals will separate in the ethereal layer, which are granular in the case of homocinchonidine or cinchonidine, and concentrically grouped needles if cinchonine or quinidine. The two former, homocin- chonidine and cinchonidine, are most likely to be present in com- mercial quinine sulphate that is not intentionally adulterated, because of their liability to crystallize out along with the quinine in the course of manufacture, but they should not be present in an amount exceeding the above-named limits. If the above-mentioned associate alkaloids are present in the free state, they will remain for the most part undissolved when the quinine sulphate is treated with thirty times its weight of boiling water, and will also be indicated by a strong alkaline re- action of the hot aqueous solution with litmus-paper, whereas pure quinine sulphate is neutral in its action upon litmus. Mineral admixhires are detected by a residue left after igniting a little of the salt upon platinum-foil, or after dissolving a small portion of the salt in ten times its weight of boiling alcohol. Ammonium salts are recognized by the odor of ammonia, and by the formation of white vapors from a glass rod moistened with acetic acid, when held in the orifice of a test-tube, wherein a small portion of the quinine sulphate is heated with a strong solution of potassium hydrate. Chlorides and hydrochloraies may be recognized in the dilute solution of the salt in water, acidulated with nitric acid, by a white, curdy precipitate with argentic nitrate. Stearic acid may be detected in the above-described alcoholic solution, by adding an equal volume of water ; the liquid becomes turbid, but, on warming it gently, by dipping the test-tube in hot water, it becomes transparent again ; the appearance of an oily layer on the surface would indicate the above fatty acid. Salicin, sugar, and mannite may be detected in the solution of the preceding test, if free from fatty substances, by mixing it, in a porcelain capsule, with an amount of barium carbonate equal to that of the quinine sulphate employed, and evaporating the whole to dryness with constant stifring ; the residue is triturated with a little water, and transferred upon a moist filter ; the obtained filtrate is evaporated at a gentle heat, upon a watch-glass, and must leave no residue, or only a very small one ; if a residue remains, it is divided, and placed upon two watch-glasses, with one drop QUININA. 523 Fig. 155. of water upon each, and is again allowed to evaporate at a gentle heat ; then, upon the one glass, a small drop of concentrated sul- phuric acid is allowed to fall from a glass rod or from a small pipette (Fig. 155) ; a red color will be produced if salicin is present, a black one if sugar; mannite remains un- changed, and may be detected on the second watch-glass, by a few drops of alcohol, which dissolve the mannite, and leave it behind in small, acicular crys- tals upon spontaneous evaporation. Since quinine sulphate dissolves with- out apparent change in strong sulphuric acid, even when gently warmed, this test may be directly applied for the de- tection of admixtures of sugar, mannite, or fatty acids, which will produce a black coloration ; a red coloration might be indicative of the presence of salicin, but, since many other compounds produce a similar reaction, the following addi- tional test may be employed for salicin : A small portion of the quinine sul- phate is dissolved, in a test-tube, in about ten times its weight of water, acidulated with a few drops of concentrated hydrochloric acid ; the solution is boiled for a few minutes, when, if salicin be present, a white turbidity caused by the formation of saliretin will take place. QUININ.ffi TANNAS. CHININUM SEU CHINIUM TANNIC UM. Tannate of Quinine or Quinia. Quinine Tannate. Ger. Gerbsaures Cliinin ; Pr. Tannate de quinine ; Sp. Tanato de quinina. C.A,N,0,(C,,H,„0,)3-t-8Hp ; 1449. A yellowish- white, amorphous powder, which, when heated, becomes brown, fuses, and at a strong heat is wholly dissipated ; it is only sparingly soluble in cold water, requiring 480 parts of it, but dissolves in about 50 parts of boiling water, forming a clear solution, which becomes turbid on cooling ; the addition of acids increases the solubility to some extent ; it is also quite sparingly soluble in boiling alcohol, ether, and chloroform, but quite readily soluble in warm glycerin; the alcoholic solution, when diluted with water, displays a slight blue fluorescence. The aqueous solution 524 MANUAL OF CHEMICAL ANALYSIS. of quinine tannate has an astringent, bitter taste, and a feebly acid reaction ; it is precipitated by metallic salts, and assumes a bluish-black color upon the addition of a few drops of solution of ferric chloride. In contact with the alkaline hydrates, quinine tannate assumes a fine red color, accompanied by the separation of quinine; when treated with chlorine- water and ammonia, it does not afford directly the characteristic green color, which is produced by most quinine salts, but, in consequence of the tannic acid, yields a transient red color. Examination : In consequence of the capability of tannic acid of forming very variable compounds with quinine, according to the proportion or manner in which it is employed, an examination of the salt should be made with reference to the amount- of contained quinine, and its freedom from any appreciable amount of the associate alka- loids, quinidine, cinchonine, and cinchonidine. One gram of the quinine tannate is intimately mixed with twice its weight of caustic lime and sufB.cient water to form a stiff paste, and the mixture dried upon the water-bath ; the residue is then powdered, repeat- edly extracted with hot chloroform, and the ohloroformic solution evaporated in a tared beaker, dried at 120° C. (248° F.), and weighed. The residue should weigh not less than 0.22 gram. In order to determine the purity of the alkaloid thus obtained, the contents of the beaker are dissolved in a little water acidulated with a few drops of dilute sulphuric acid, filtered if necessary, and then shaken with 3 to 4 cubic centimeters of ether, and ammo- nia-water in excess. The two layers of liquid will remain clear if only quinine is present, while a greater or less turbidity is evi- denced in the presence of the other alkaloids. The residue from the chloroformic solution is also adapted to the qualitative deter- mination of quini'ne, by dissolving a small portion in chlorine- water, and subsequently adding a few drops of ammonia-water, when the characteristic emerald-green coloration will be produced ; if the addition of ammonia-water be preceded by a few drops of a solution of potassium ferrocyanide, it assumes a bright red color. Admixtures of tannic or gallic acid, sugar, mannite, or dextrin may be recognized by their ready solubility in cold water in com- parison with that of quinine tannate. Starch is detected by a blue color, when one drop of solution of iodinized potassium iodide is added to a little of the quinine tannate shaken with some boiling water, and subsequently allowed to cool. QUININA. 525 QUININE VALERIANAS. CHININUM SEU CHINIUM VALERIANICUM. Valerianate of Quinine or Quinia. Quinine Valerianate. Ger. Baldriansanres Chinin ; Fr. Valerianate de quinine ; Sp. Valerianato de quinina. C,„H,,NA.C,H,A+H,0; 444. Thin, colorless, crystalline plates, of a pearly lustre, belonging to the triclinic system, having a faint odor of valerianic acid, and containing one molecule (4.04 per cent.) of water of crystalli- zation ; they are permanent in the air, fuse at about 90° 0. (194° F.) to a colorless liquid, and lose their water of crystalli- zation at 100° C. (212° F.), becoming thereby partially decom- posed and incompletely soluble in water ; when strongly heated, they are entirely dissipated, emitting white, inflammable vapors. Quinine valerianate is soluble in about 100 parts of water at 15° C. (59° F.), and in 40 parts of boiling water; in 5 parts of cold, and 1 part of boiling, alcohol, but only sparingly in ether ; diluted acids dissolve it freely, and strong sulphuric acid does so without color, if heat is not applied. The aqueous solution of the salt pos- sesses a bitter taste, is neutral in its action upon litmus, and, when acidulated with sulph uric acid, displays a blue fluorescence with the development of the odor of valerianic acid; with ammonia- water it yields a white precipitate of quinine, which dissolves in a con- siderable excess of the reagent, as also readily upon agitation with ether. If chlorine-water be added to the solution, and subse- quently ammonia-water in slight excess, an emerald-green coior is produced; if the addition of ammonia-water is preceded by a few drops of a solution of potassium ferrocyanide, it assumes a bright red color. Examination : Stearic acid, sugar, and salicinare detected by agitating some of the quinine valerianate with strong sulphuric acid, in a test-tube ; a black coloration would indicate one or both of the two former ; a red one, salicin. In the case of a black coloration, a special test for salicin has to be made ; a little of the valerianate is agitated with cold water, the filtrate is then evaporated at a gentle heat to a small volume, and this is strongly acidulated with a few drops of concentrated hydrochloric acid, and heated; a white turbidity, taking place after a while, would indicate salicin. Quinine hydrochlorate and sulphate may be detected, in the fil- tered aqueous solution of the salt, acidulated with a few drops of nitric acid, by testing portions of it with argentic nitrate for the former, and with barium nitrate for the latter. They will be in- dicated by a white precipitate with the respective reagent. 526 MANUAL OF CHEMICAL ANALYSIS. Zinc Valerianate or Acetate. — The absence of these or any other mineral salts, not readily volatilizable, may be ascertained by ex- posing the salt to a red heat, upon platinum-foil, whereby the or- ganic matter is completely dissipated, leaving metallic oxides or carbonates behind, if such be present ; if a residue remains which, appears straw-yellow while hot and white when cold, it may be examined for zinc oxide by dissolving it, in a test-tube, in a few drops of diluted hydrochloric acid, supersaturating the solution with ammonia- water, and subsequently adding a little ammonium sulphide ; an ensuing white precipitate will confirm the presence of zinc. RESORCINUM. Sesorcin. Meta-dioxybenzol. Ger. Resorcin ; Fr. Resorcine ; Sp. Resorciua. CAO.= CeH,(OII),; 110. A crystalline powder, or short, thick prisms of the rhombic system (Fig. 156), odorless and colorless when perfectly pure, but on exposure to the air assuming a pinkish Fig. 156. color. It melts at 104° C. (219.2° F.), and boils at 271° C. (519.8° F.), but becomes par- tialh'^ volatilized at a much lower tempera- ture ; when heated on platinum-foil, it burns with a bright flame, and is finally completely dissipated. Resorcin is very readily soluble in water, alcohol, and ether, but is insoluble in chloro- form and carbon bisulphide. Its aqueous solution is neutral in its action on litmus, pos- sesses an intensely and disagreeably sweet ~ taste, and assumes a dark violet color on the addition of ferric chloride, which disappears on the subsequent ad- dition of ammonia; chlorinated lime also produces a transient violet coloration. Its solution with ammonia-water by exposure to the air becomes rose-red, then brown, by evaporation at a gentle heat, green, finally dark blue, and, on the addition of an acid, again dark red. Resorcin reduces an ammoniacal solution of argentic nitrate and an alkaline cupric solution on boiling ; upon the addition of bro- mine-water to its aqueous solution until a permanent turbidity is produced, small colorless needles of tribromresorcin, CjHBr3(OH)2, are separated, which are sparingly soluble in cold water, more readily in hot water, and freely soluble in alcohol. With acetyl, benzol, and succinyl chlorides, resorcin combines to form ether- SALiciNnn. 527 like compounds, in wliich the hydrogen atoms of the hydroxyl are replaced by acetyl, benzoyl, and succinyl groups, as, e.g., C.H/O-C.HjO),, CX(0-C,H,-CO)„ etc. When heated with phthalic anhydride at 195° 0.(383° F.), the phthalein of resorcin, or fluorescein, is produced, as follows : Resoiciu. Phthalic Fluorescein, anhydride. From the solution of the melted mass in alcohol it is precipi- tated in white flakes by water, and crystallizes from alcohol in small, dark brown, ctystalline crusts, which dissolve in ammonia- water, forming a red solution, and displaying an intense green fluorescence. From the fluorescein, by the action of bromine, tetra-brom fluorescein is produced, the potassium salt of which, eosin, CjoHjKjBr^Oj, is remarkable for the rose-red color of its aqueous solution, accompanied by a green, or, when the solution is very dilute, yellow fluorescence. By the action of pure nitro- gen tetroxide on resorcin in ethereal solution, diazo-resorcin is produced : 30^^ + K,0, = ^_^,„NA + 4H,0. Resorcin. Diazo-resoicin. The latter forms brown, granular crystals, having a green metallic lustre, which are dissolved by alkalies with a magnificent blue-violet color. A very characteristic test of resorcin is aftbrded by dissolving a small portion in fuming, sulphuric acid ; an orange-red solution is formed, which gradually darkens, and changes after a time, first to greenish-black, and then to pure blue, becoming purple- red on gently warming. SALICINUM. Salicin. Ger. Salicin ; Fr. Saliciue; Sp. Saliciiia. 0,3H,A; 286. Small, colorless, needle-shaped crystals or laminae, of a pearly lustre, without odor, but having a very bitter taste. When heated to 198° 0. (888.4° F.) they melt to a colorless liquid, which, upon further heating, becomes yellow, with the development of white vapors having the odor of salicylous acid, and becomes finally carbonized; when strongly heated on platinum-foil they burn entirely away, leaving no residue. 528 MANUAL OF CHEMICAL ANALYSIS. Salicin is soluble in 28 parts of water and in 80 parts of alcohol at 15° C. (59° F.), in 0.7 part of boiling water, and in 2 parts of boiling alcohol, and is quite freely soluble in aqueous solutions of the alkaline hydrates and in acetic acid, but insoluble in ether and chloroform. The aqueous solution is neutral in its action upon litmus, possesses a bitter taste, and is precipitated by none of the ordinary reagents. With cold concentrated sulphuric acid, salicin affords a solution having a fine red color ; upon the subsequent addition of water the solution becomes colorless, and deposits a dark red powder, insoluble in water and in alcohol; when cautiously heated with diluted sulphuric or hydrochloric acid, it is decomposed by absorp- tion of water into glucose and salUjenin: C,3H,,0, + H,0 = 0,H,A + C^H^O,. V ^ ' V y 1 Salicin. Saligenin. The latter is a handsomely crystallizable substance, readily soluble in hot water, alcohol, and ether, and its aqueous solution assumes, on the addition of a drop of a solution of ferric chloride, an indigo-blue color. By long-continued heating with dilute acids, saligenin is converted, by the elimination of a molecule of water, into saliretin, CjHjO, a white or yellowish, resinous body, which is insoluble in water, but soluble in concentrated acetic acid, alco- hol, and ether, and is dissolved by concentrated sulphuric acid with a red color. The purity of salicin may be sufficiently determined, in connec- tion with the aVjove described reactions, by its leaving no residue upon ignition, and by affording a clear, colorless solution when 1 gram of the salicin is agitated with a mixture of 22 parts of water and 5 parts of solution of potassium hj^drate. It is also distin- guished from the alkaloids, by its aqueous solution affording no turbidity or precipitate with tannic or picric acids, potassio-mer- curic iodide, or an ammoniacal solution of argentic nitrate. SANTONINUM. Santonin. Ger. Santonin ; Fr. Santonine ; Sp. Santonina. C,3H„0; 246. Small, flat, rhombic prisms, transparent, without odor or color, and of a slightly bitter taste ; they fuse at 170'^ C. (338° F.), and solidify on cooling to an amorphous mass, which, however, in contact with a minute quantity of any of its simple solvents, again assumes the crystalline form ; at a stronger heat, they vola- tilize in dense, white, irritating, inflammable vapors, which con- SANTONINUM. 529 dense in part unaltered on cooling, forming a white crystalline sublimate ; at a red heat, with free access of air, they burn away without residue. Santonin is permanent in the air, and assumes a straw-yellow color when exposed to solar light, without, however, undergoing any chemical change. When moistened with concentrated sul- phuric acid, it remains unchanged and colorless for a while (evi- dence of the absence of salicin, which at once assumes a deep red color); the mixture does not assume a bluish color upon the addi- tion of a little powdered potassium bichromate (evidence of the absence of strychnine*), nor does it afford any coloration with concentrated nitric acid. When a few drops of a mixture con- sisting of equal volumes of a very dilute solution of ferric chloride and concentrated sulphuric acid are added to a crystal of santonin, and the whole gently warmed, a fine red color is developed, which changes to purple and finally to violet. Santonin is almost insoluble in cold water, requiring 5000 parts of the latter for solution, and is not much more freely soluble in acidulated water or in dilute acids; when agitated with the latter and filtered, the filtered liquid has only a feebly bitter taste, and affords no precipitate with tannic acid, potassio-rnercuric iodide, or with trinitrophenol (picric acid), either before or after the addi- tion of a little solution of sodium acetate (further cv denue of the absence of salicin, and of cinchonine, and other bitter alkaloids). Boiling water dissolves j^oth part of santonin. It is, however, readily soluble in diluted solutions of the alkaline liydrates, but is reprecipitated upon supersaturation with an acid, or upon the addition of acidulous salts. Santonin is also soluble in 40 parts of cold, and in 3 parts of boiling, alcohol, in 160 parts of cold, or 42 parts of boiling ether, in 4 parts of chloroform (distinction from cinchonine, which is almost insoluble in chloroform), and more or less freely in benzol, and in essential and fatty oils. The alcoholic solution possesses an intensely bitter taste, is neutral in its action upon litmus, and burns with a pale yellow flame (evidence of the absence of an adulteration with boric acid); it becomes transiently carmine- red upon the addition of a few drops of a concentrated solution of potassium hydrate. Santonin is the anhydride of santoninic acid, G,Jl..fiO^, forming with the alkalies soluble, and, in part, well crystalJizable salts. * Santonin and stryclinhie have some similarity in their appearance, and this fact has repeatedly been the cause of incidental mistakes and sad accidenls. They may, however, at once be distinguished, besides their difference in taste, by the solubilily of strychnine in diluted acids, by its insolubility in ether and in solution of potassium hydrate, and by its reaction with concentrated sul- phuiic acid, in which it dissolves without color, but produces, upon the addi- tion of a minute crystal of potassium bichromate, a bluish-violet color, which successively changes to violet, to red, and finally to yellow. 34 530 MANUAL OF CHEMICAL ANALYSIS. From the sodium salt, by the addition of dilute hj-drocliloric acid, and direct agitation with ether, the free santoninic acid may be obtained ; it forms white, rhombic crystals, unalterable by expo- sure to light, and sparingly soluble in cold water, but readily soluble in alcohol, and which, at 120° C. (248° F.), are decom- posed into santonin and water. The same decomposition takes place upon the addition of sulphuric acid to the aqueous solution of the salt, or when the latter is warmed with dilute hydrochloric acid. The purity of santonin may, in most instances, be sufficiently determined hj the above described physical characters, and its deportment with the siinple solvents. An admixture of stearic acid, or other crystallizable fatty acids, may be detected by their lower fusing po:nts, and by the production of a greasy stain, when a little of the santonin is warmed upon a piece of glazed paper at a temperature not exceeding 100° C. (212° F.). Fig. 157. SODII ACETAS. SODIUM SEU NATRIUM ACETICUM. Acetate of Sodium. Sodium Acetate. Ger. Essigsaures Natrium ; Fr. Acetate de soude ; Sp. Acetato de sosa. NaG,H30,-f 3H,0; 136. Large, colorless, transparent, monoclinic prisms (Fig. 157), con- taining three molecules (39.70 per cent.) of water of crystallization ; they are efflorescent in a drv, warm atmos- phere, liquefv at 75° 0. (167° F.), and lose their water of crystallization at 123° C. (253.4° F.), leaving the anhydrous salt as a white powder. The anhydrous salt melts at about 800° C. (572° F.), without decomposition, and solidifies on cooling in a crystalline form ; at tempera- tures above 315° 0. (599° F.) it is decomposed, with the evolution of empyreumatic, inflam- mable fumes, leaving a black residue of carbon and sodium carbonate, which imparts to the flame a yellow color, changes moistened red lit- mus-paper to blue, and effervesces with acids. Sodium acetate is soluble in 3 parts of water and in 30 parts of alcohol at 15° C. (59° F.), and in 1 part of boiling water and 2 parts of boiling alcohol; its aqueous solution is neutral or nearly so, has a cooling, saline taste, is not precipitated when dropped into strong alcohol, nor when mixed with a diluted solution of sodium carbonate, or with a SODIUM. 531 concentrated solution of sodium bitartrate ; it assumes a red color upon the addition of a few drops of solution of a ferric salt, evolves the vapor of acetic acid, when warmed with coQcentrated sulphuric acid, and that of acetic ether, when heated with a mix- ture of alcohol and sulphuric acid. Examination : Sodium chloride and sulphate are detected, in the solution of sodium acetate, acidulated with a few drops of diluted nitric acid, by testing it, in separate portions, with argentic nitrate and barium nitrate; a white precipitate with the first reagent would indicate chloride, and with the second one, sulphate. Carbonates, silica, and alkaline earths may be detected by dis- solving a portion of the salt in water acidulated with hydrochloric acid; effervescence will indicate carbonates; upon evaporating the resulting solution to dryness, and treating the residue with water, the silica will remain undissolved; and the solution, after filtration, and the addition of sodium carbonate in slight excess, will yield a white precipitate if alkaline earths be present. Organic impurities will be indicated by a dark coloration when a little of the salt is strewn upon colorless concentrated sulphuric acid. Metallic impurities may be detected in the aqueous solution ot the salt, acidulated with hydrochloric acid, by a dark coloration or precipitate upon saturation with hydrogen sulphide, or, after neutralization with ammonia water, by the addition of ammonium sulphide. Estimation : About 5 grams of the dry but unefEloresced crystals of the salt are accurately weighed and ignited at a strong heat, in a porcelain crucible, until inflammable vapors cease to be evolved; the resi- due is then dissolved in water, and the solution, contained in a beaker, after the addition of a few drops of solution of litmus, is titrated with a standard solution of oxalic or sulphuric acid (page 82) until, with the application of a gentle heat to effect the com- plete removal of the disengaged carbonic acid gas, a slight excess of acid has been employed, and the liquid assumes a bright cherry-red color. The excess of acid is then inversely titrated with a standard alkali solution (page 87) until a decided blue coloration of the liquid is just produced, when the number of cubic centimeters of alkali solution, subtracted from that of the acid first employed, will give the amount of the latter required for the exact neutralization of the salt. One cubic centimeter of the normal acid solution corresponding to 0.053 gram of sodiunr carbonate, or, as its equivalent, 0.136 gram of crystallized sodium acetate, the latter decimal, multiplied by the number of cubic centimeters of normal ac.d solution employed for neutralization, will represent the amount of pure sodium acetate in the quan- tity under estimation. 532 MANUAL OF CHEMICAL ANALYSIS. By the employment of 6.8 grams of crystaHized^ sodium ace- tate, and a strictly normal solution of oxalic or sulphuric acid, the number of cubic centimeters of acid required for the exact neutralization of the salt after the above treatment, when multi- plied by 2, will represent without further calculation the percent- age purity of lhe salt under examination. SODII ARSENIAS. SODIUM SETJ NATRIUM ARSENICUM. Arseniateof Sodium. Sodium Ameniate. Ger. A reensaures Natiinm ; Fr. Arsfiniate de soude; Sp. Arseuiato de sosa. ]SraHAsO,-f7H,0; 311.9. Colorless, transparent, monoclinic prisms (Fig. 158), containing seven molecules* (40.38 per cent.) of water of crystallization ; they effloresce slightly in a dry atmos- Fio. 158. phere, and, when gently heated, lose 5 ~ molecules (28.84 per cent.) of water, be- y'^"' .:..rf'" Sli.. coming converted into a white powder, which still contains two molecules (11.54: per cent.) of water ; these, however, are expelled at 148° C. (299.4° F.), when the salt fuses. Sodium arseniate is soluble in 4 parts of water at 15° C. (59° F.), but is very spar- ingly soluble in cold alcohol : it is very «.^ 1 T ■BfflBKw freely soluble in boiling water, and in 60 ^fehL ^i M BB^^ parts of boiling alcohol. Its aqueous solu- ^'^C^^^^ tion possesses a mild, feebly saline taste, and a si ghtly alkal ne reaction; it gives white prec'pitates with barium and calcium salts, and with mag- nesium and zinc sulphates, and a brick-red one with argentic nitrate, all of which are soluble in nitric acid ; it suffers no im- mediate alteration by hydrogen sulphide, either n its alkaline solution or when this is acidulated with acids; the latter mix- ture, however, becomes turbid upon warming, separating white sulphur first, and subsequently yellow arsenic tri sulphide. Fused upon charcoal, before the blow-pipe, sodium arseniate gives the garlic-like odor of arsenic, and imparts a yellow color to the flame ; heated, in a narrow tube, with a little potassium cyanide, it forms a metallic mirror. * When crystallized from a cold solution, the salt contains 12 molecules of water of crystallization, but readily loses 5 molecules of water at ordinary tem- peratures, becoming converted, without change of form, into a salt of the above composition. SODIUM. 533 SODII BSNZOAS. SODIUM SEU NATRIUM BENZOIOUM. Bemoate of Sodmm. Sodium, Benzoate. Ger. Benzoesaures Natrium ; Fr. Benzoate de sonde ; Sp. Benzoato de sosa. NaC,Hp, + H,0 = CjH.-CO-ONa + H,0 ; 162. Colorless, needle-sbaped crystals, or a white, semi-crystalline powder, containing one molecule (11.11 per cent.) of water of crystallizatioQ, and efflorescent on exposure to the air. The salt is odorless, or possesses but a faint odor of benzoin ; on being- heated, it first melts, with the evolution of irritating, inflammable vapors, then chars, and finally leaves a blackened residue of an alkaline reaction, which effervesces with acids and imparts an intense yellow color to the non-luminous flame. Sodium benzoate is soluble in 1.8 parts of water and in io parts of alcohol at 15° C. (59° F.), in 1.3 parts of boiling water, and in 20 parts of boiling alcohol. The aqueous solution possesses a sweetly astringent taste, and is neutral in its action upon litmus; on the addition of a few drops of a dilute solution of ferric chloride, a flesh-colored precipitate of basic ferric benzoate is produced, and with hydrochloric acid it yields a crystalline precipitate of benzoic acid, which, upon subsequent agitation with ether or chloroform, becomes readily dissolved. Examination : Sulphates and chlorides may readily be detected in the diluted aqueous.solution of the salt, acidulated with nitric acid, by testing it, in separate portions, with barium chloride for the former, and with argentic nitrate for the latter ; a white precipitate with either of these reagents, insoluble in nitric acid, will reveal the presence of such impurities. Ghloro-henzoic acid may be detected by the addition of hydro- chloric acid to a concentrated solution of the salt, washing the precipitated benzoic acid thoroughly with water, and subse- quently heating a small portion of it, together with a little re- cently ignited and moistened cupric oxide, on the looped end of a platinum wire in the non-luminous flame; if a green or bluish- green color is imparted to the oxide, the presence of chloro-ben- zoic acid will be indicated. The presence of the latter impurity, in case other chlorides are absent, may also be detected by mixing 1 gram of the salt with a few drops of a solution of sodium hydrate, allowing the mixture to dry slowly, and subsequently igniting; the residual mass is then extracted with water, filtered, and the filtrate, after super- saturation with nitric acid, tested with argentic nitrate, when a white, curdy precipitate will indicate an admixture or substitution of sodium chloro-benzoate. 534 MANUAL OF CHEMICAL ANALYSIS. Organic impurities will in many instances be indicated by a dark coloration when a little of the salt is added to concentrated sulphuric acid ; the mixture may subsequently be diluted with twice its volume of water, a small crystal of potassium bichro- mate added, and gently heated, when neither a green color nor the development of the odor of bitter almonds should be pro- duced ; in the latter case the presence of cinnamio acid will be indicated. SODII BICARBONAS. SODIUM SEU NATRIUM BICARBONIOUM. Bicarbonate, of Sodium. Sodium Bicarbonate. 6er. Doppelt kohlensaures Natrium ; Fr. Bicarbonate de soude ; Sp. Bicarbonato de sosa. NaHOO,; 84. White, opaque masses, or crystalline crusts, consisting of mono- clinic tables, or a snow-white powder, permanent in dry air, and having the specific gravity 2.22. "When heated to 100^ G. (212° F.), the salt rapidly loses water and carbonic acid gas, amounting to 36.9 per cent, of its weight, and leaves a strongly alkaline residue of normal sodiiim carbonate, which melts at a red heat: 21SraHG03 = Na,CO, + H,0 + CO,. Sodium bicarbonate is soluble in 11.3 parts of water at 15° C. (59° F.), and is insoluble in alcohol. The solution possesses a mild alkaline taste and reaction, but does not change the color of turmeric paper ; when heated, effervescence takes place, and at the boiling-point of the solution the salt is completely converted into normal sodium carbonate, KajCO^. Solution of sodium bi- carbonate affords no precipitate upon the admixture of a concen- trated solution of sodium bitartrate, of tartaric acid, or of mag- nesium sulphate. Examination : Normal sodium carbonate will be indicated by a strongly alka- line reaction of tlie salt to test-paper, and may be recognized in the cold aqueous solution by the production of a white precipi- tate on the addition of a solution of magnes um sulphate, as also by the following simple tests. 2 grams of the salt are dissolved with as little agitation as possible, in a closed vessel, in 30 parts of cold water, and the solution added at once to 5 grams of a cold solution of 1 part of mercuric chloride in 20 parts of water ; after standing for three minutes, only a slight white turbidity should have occurred; a reddish-brown turbidity or a reddish deposit will indicate the presence of more than 4 per cent, of normal car- bonate. By the employment of 6 grams of the mercuric chloride soDiuii. 535 solution, the occurrence of a reddish -brown turbidity within three minutes will indicate 3 per cent., with 6.5 grains, 2 per cent., with 7 grams, 1 per cent., and with 7.5 grams, 0.16 per cent, respectively of normal sodium carbonate. To insure the accuracy of the above test, however, the absence of sodium chlo- ride must be previously established, as the latter has the property of dissolving the red mercuric oxychloride, and its precipitation would thereby be prevented. Another method for determining the presence of normal car- bonate in bicarbonate depends upon the conversion of calomel in a concentrated solution of sodium carbonate into black mercurous oxide, whereas it is not afifected by a solution of bicarbonate. About 0.5 gram of calomel, 1 gram of the sodium bicarbonate, and 1.5 grams of water are mixed, in a test-tube, and the mixture well agitated for one minute ; if the bicarbonate be free from normal carbonate, the calomel will remain white, even after standing for twenty-four hours, whereas, with an admixture of 0.25 per cent, of carbonate, a slight grayish coating will be ob- served within about twenty minutes, with 0.5 per cent, of car- bonate it will appear gray within fifteen minutes, and' with one per cent, will become whitish -gray in a few minutes, and gradu- ally increase in intensity of color. Sodium chloride and sulphate are detected in the solut'on of the salt, when supersaturated with diluted nitric acid, by testing it in separate portions, with argentic nitrate for chloride, and with barium nitrate for sulphate. Sodium sulphite and hyposulphite (thiosulphate) may be detected in the aqueous solution of the salt, supersaturated with sulphuric acid, by warming with a little potassium bichromate, when a green coloration will be produced. The hyposulphite m-ay also be specially tested for, by supersaturating the solution of bicar- bonate with acetic acid, and subsequently adding a little solution of argentic nitrate; a white precipitate, gradually changing to brown, will indicate hyposulphite : if chlorides also be present, the resulting precipitate may be digested with ammonia-water, when the argentic chloride will become dissolved, leaving brown argentic sulphide if hyposulphite were present. Ammonium salts may be detected hy the odor of ammonia, when a little of the salt is heated, in a test-tuba, with a concen- trated solution of potassium hydrate, and by the formation of white fumes, when a glass rod, moistened with acetic acid, is held over the mouth of the tube. Calcium and Magnesium Salts. — A small portion of the salt is dissolved in diluted acetic acid, and subsequently tested with ammonium oxalate, when a white precipitate will reveal the presence oi calcium; to the filtrate, ammonium chloride, ammonia- water, in slight excess, and solution of ammonium phosphate are 538 MANUAL OF CHEMICAL ANALYSIS. then successively added, when the formation of a white, crystal- line precipitate will indicate maynesium. Silica, Metallic Impurities, etc. — -A small portion of the salt is dissolved in an excess of diluted hydrochloric acid, the solution evaporated to drjj-ness, and the dry mass treated with water acidu- lated with hydrochloric acid ; a white insoluble residue will indi- cate silica. The acid solution is then tested for metals, copper, iron, aluminium, etc., by saturating with hydrogen sulphide, and, after filtration, if necessary, by supersaturation with ammonia- water, and the addition of ammonium sulphide ; a dark coloration or a precipitate with these reagents would indicate one or the other of the above-mentioned impurities, which may be further examined as to its nature by the methods of systematic analysis, as described on pages 51 to 59. Estimation : One hundred parts of sodium bicarbonate require for exact neu- tralization 83.33 parts of citric, or 89.29 parts of tartaric, acid. The quantitative estimation of the salt may, however, be more conveniently and accurately accomplished by igniting a weighed portion, and determining its loss of weight, which, if the salt be pure, will amount to 36.9 per cent. The residue may then be dissolved in water, and the amount of pure sodium carbonate estimated volumetrically by means of a standard solution of oxalic or sulphuric acid (page 82), as described under sodium carbonate, on page 545 ; one cubic centimeter of the normal acid corre- sponding to 0.053 gram of anhydrous sodium carbonate, or, as its equivalent, 0.084 gram of sodium bicarbonate. If desired, the accuracy of the result of the above estimation may be verified by determining the amount of carbonic acid contained in a weighed portion of the salt, as described on page 86 ; 100 parts of carbon dioxide, CO^, corresponding to 190.9 parts of pure sodium bicar- bonate. The U. S. Pharmacopoeia directs that to neutralize 4.2 grams of sodium bicarbonate should require not less than 49.5 cubic centi- meters of the volumetric solution of oxalic acid, and to neutralize the same amount of the commercial salt, should require not less than 47.5 cubic centimeters of the volumetric solution of oxalic acid; corresponding, in the first instance, to at least 99 per cent., and, in the second instance, to at least 95 per cent., of pure sodium bicarbonate. SODIUM. 537 SODII BISULPHIS. SODIUM SEU NATRIUM BISULFUROSUM. Bisulphite of Sodium. Sodium Bisulphite. Acid Sodium Sulphite. Ger. Doppelt scliwefligsauies Natrium ; Fr. Bisulfite de soude ; Sp. Bisiilfito de sosa. NaHSO^; 104. Small, opaque, prismatic crystals, having the odor of sulphurous acid, an unpleasant, sulphurous taste, and an acid reaction. On exposure to the air, the salt readily loses sulphur dioxide, and becomes converted into sodium sulphate; when strongly heated, it decrepitates, and is resolved into sulphur and sodium sulphate ; and when introduced, on a platinum-wire, into the non-luminous flame, it imparts to the latter a persistent yellow color. Sodium bisulphite is soluble in 4 parts of water and in 72 parts of alcohol at 15^ C. (59° F.), in 2 parts of boiling water and in 49 parts of boiling alcohol. If hydrochloric acid be added to the aqueous solution of the salt, it is decomposed, with the* evolution of vapors of sulphur dioxide, but without the separation of sul- phur (distinction from hyposulphite). Examination : The dilute aqueous solution of the salt, acidulated with hydro- chloric acid, should not afford more than a slight cloudiness upon the addition of a few drops of solution of barium chloride; a white precipitate would indicate the presence of an undue amount of sulphate. Estimation : About 0.2 gram of the salt is dissolved in a small portion of water, in a beaker, a little mucilage of starch added, and subse- quently a decinormal solution of iodine (page 93) allowed to How into the liquid from a burette until, with constant stirring, a per- manent blue tint is just produced. One cubic centimeter of the decinormal iodine solution corresponding to 0.0052 gram of sodium bisulphite, NaHSOj, the number of cubic centimeters of iodine solution required to produce this reaction will indicate, by simple calculation, the amount of the pure salt in the specimen under examination. The United States Pharmacopoeia directs that if 0.26 gram of the salt be dissolved in 10 cubic centimeters of water, and a little gelatinized starch added, at least 45 cubic centimeters of the volumetric solution of iodine should be required before a per- manent blue tint appears after stirring (corresponding to at least 90 per cent, of pure .sodium bisulphite). 538 MANUAL OF CHiSMICAL ANALYSIS. SODII BORAS. SODIUM SEU NATRIUM BORICUM SEU BIBORICUM. Borate or Biborate of Sodium. Borax. Sodium Borate. Sodium Pyroborate. Ger. Borax ; Fr. Borate de soude ; Sp Borate de sosa. Na,Bp, + 10Hp; 382. Colorless, transparent, hard, raonoclinic prisms (Fig. 159), hav- ing a specific gravity of 1.72, and containing 10 molecules (47.12 per cent.) of water of crystallization ; they are ordinarily permanent, but slightly efflo- rescent in dry and warm air ; when heated, they undergo aqueous fusion with intume- cence and the elimination of the water of rystallization, and form a white porous lass, which fuses at a red heat into a glass, which is a powerful solvent for the metallic oxidfes, forming colored fluxes. When pow- dered borax is mixed in a porcelain cap- sule with diluted sulphuric acid and subse- quently with alcohol, and the mixture ignited, the alcohol burns with a greenish — flame. Borax is soluble in 16 parts of water at 15° C. (59° F.), in half its weight of boiling water, and, at 80° C. (176° F.), in its own weight of glycerin, bat insoluble in alcohol ; its aqueous solution has an alkaline, sv/eetish taste, and an alka- line reaction upon litmus and especially upon turmeric paper; it forms precipitates of insoluble or sparingly soluble borates with the solutions of most earthy and metallic salts, and acts upon salts of gold, silver, mercury, and others, almost like potassium hydrate, precipitating their oxides. When added to mucilage of gum-arabic or Iceland-moss, or to other similar vegetable mucilages, solution of borax thickens them considerably, unless they contain an addition of grape or cane-sugar. Examination : A portion of the powdered borax, when dissolved in twenty times its weight of warm water, should yield a complete and clear solution, remaining so after cooling; this solution may serve for the following tests : Sodium carbonate is indicated by effervescence, or the rise of gas-bubbles, when a portion of the solution is added to concen- trated hydrochloric acid. Calcium and aluminium salts (alum) will be indicated by a white precipitate with solution of sodium carbonate. The presence of alum may further be confirmed, when tested with ammonium SODIUM. 539 sulphide, by the production of a white precipitate of aluminium hydrate, soluble in a solution of potassium hydrate. Chloride and sulphate may be detected in the solution, after dilution with three times its volume of water and acidulation with diluted nitric acid, by the formation of white precipitates when tested, in separate portions, with argentic nitrate for chloride, and with bariutn nitrate for sulphate. Phosphate may be detected by a white granular precipitate, upon the addition of test magnesium mixture. In order to ascertain the absence of arsenic acid or an arseniate, which would afford the same reaction with test magnesium mix- ture, the precipitate may be collected, washed, and dried, and then tested by heating a portion of it, mixed with a little exsiccated sodium carbonate, upon charcoal, and another portion, with a little potassium cyanide, in a narrow glass tube; a garlic-like odor in the first test, and a metallic mirror in the second, would indicate an incidental contamination with an arseniate. The presence of phosphate may also be definitely determined by heating the solution of borax with a solution of ammonium molybdate, acidulated with nitric acid, when a yellow, crystalline precipitate of ammonium phospho-molybdate will be produced. Nitrate will be indicated in the solution, strongly acidulated with sulphuric acid, and tinged slightly blue with indigo solution, by ensuing decoloration upon heating. Metallic impurities may be detected in the solution of the salt, acidulated with a few drops of hydrochloric acid, by a coloration or turbidity upon saturation with hydrogen sulphide, or, after filtration, if necessary, and supersaturatiou with ammonia-water, by the addition of ammonium sulphide. SODII BROMIDTJM. SODIUM SEU NATRIUM BROMATUM. Bromide of Sodium. Sodium Bromide. Ger. Bromnatrium ; Fr. Br&mure de sodium ; Sp. Bromuro de sodio. KaBr; 102.8. Small, colorless or white, anhydrous, cubical crystals, or a crys- talline powder, permanent in dry air. On exposure to a dull-red heat, the salt melts without losing weight, and, at a full red heat, it is slowly volatilized without decomposition. A fragment of the salt imparts an intense yellow color to the non-luminous flame. Sodium bromide is soluble in 1.2 parts of water and in 13 parts of alcohol, at 15° 0. (59° F.), in 0.5 part of boiling water, and in 11 parts of boiling alcohol. The aqueous solution possesses a saline, 5-iO MANUAL OF CHEMICAL ANALYSIS. faintly bitter taste, and a neutral or slightly alkaline reaction; with argentic nitrate it yields a yellowish-white, curdy precipi- tate of argentic bromide, which is insoluble in nitric acid, but soluble in a large excess of ammonia-water (distinction from argentic iodide); when dropped into a very dilute solution of mercuric chloride, no reaction takes place (additional distinction from sodium iodide), nor does it afford any precipitate on the addition of a concentrated solution of tartaric acid or sodium bitartrate (distinction from potassium bromide). Sodium bromide may also be distinguished from the iodide by adding to the solution a little mucilage of starch, and subsequently a few drops of chlorine-water ; the solution of the bromide be- comes yellow or yellowish-brown, while that of the iodide assumes a deep blue color. If oarboa disulphide be poured upon a solu- tion of the salt, then chlorine- water added, drop by drop, and the whole agitated, the disulphide should acquire a yellow or yellow- ish-brown color, without a violet tint. Examination : Moisture, which may be contained in the crystals, as well as in the granular form of the salt, is recognisied, and may be quantita- tively determined by ascertaining the loss of weight upon drying at 100° C. (212° F.). Sodium carbonate will be indicated by a strongly alkaline reac- tion, when a few fragments of the salt are placed upon moistened red litmus-paper, and may be recognized by the occurrence of a white turbidity, when a little of the concentrated solution of the salt is added to lime-water. Sulphates may be detected, in the dilute aqueous solution, acidulated with a few drops of nitric acid, by a white precipitate on the addition of a few drops of solution of barium nitrate or chloride. Bromate is detected by placing a little of the powdered salt upon a piece of white porcelain, knd subsequently adding one drop of dilute sulphuric acid ; a yellow coloration of the moist- ened surface of the salt, or the developed odor of bromine, will reveal the presence of bromate. The presence of the latter, in an aqueous solution of the salt, may also be detected by the libera- tion of bromine upon the addition of a few drops of dilute sul- phuric acid, imparting a yellow color, which, upon subsequent agitation of the solution with a few drops of carbon bisulphide, will be absorbed by the latter. Chlorides may be detected, in the solution of the salt, bv com- pletely precipitating it with argentic nitrate, digesting the washed and still moist precipitate for some time with a cold, saturated solution of ammonium carbonate, subsequently filtering, and supersaturating the filtrate with nitric acid ; the production of a white, curdy precipitate will reveal the presence of chloride. The presence of smaller amounts of chloride, and less than that SODIUM. 541 admitted in the officinal salt, may be detected as follows. 5 grams of the powdered and well-dried salt, together with 6 grams of pure powdered potassium bichromate, are introduced into a small flask, and 15 grams of concentrated sulphuric acid are added. The mixture is then submitted to distillation at a gentle heat, and the distillate collected in a receiver or flask, containing a small quantity of arntnonia-water (F.g. 160). Bromine distils over, and Fig. 100. is dissolved by the ammonia-water without color; but, if chlo- rides are present, chloro-chromic anhydride, CrO^CI^, is produced, distils over, and forms ammonium chromate, which imparts a yellowish color to the distillate; by subsequently heating the latter with a little hydrochloric acid and alcohol, the bright green color of the chromic salt will be produced. If sodium chloride or other salts are indicated by the above tests, the extent of such an admixture may be approximately ascertained by preparing a solution of 1 gram of the di'y, cryftallized salt in about 10 times its weight of water, acidulated with a few drops of diluted nitric acid, and completely precipitating it with a solution of argentic nitrate ; the precipitate is collected upon a moist, tared filter, is washed, dried, and, when completely dry, weighed. If the salt was pure sodium bromide, the obtained argentic bromide should weigh 1.824 grams; if it contained sodium or potassium chloride, the weight will be greater in proportion to the amount of the admixture, since their molecular weights are lower; 1 gram of sodium chloride, for instance, would give 2.45 grams of argentic chloride. The same test may also be employed to indicate the purity of the bromide, by ascertaining the quantity of argentic nitrate 542 MANUAL OF CHEMICAL ANALYSIS. required to completely precipitate a definite weight of sodium bromide; 1 gram of which requires 1.65 grams of argentic nitrate for precipitation. Nitrates may readily be detected, if the salt be free from bro- mate, by an ensuing intense yellow coloration, when a solution of a few fragments of the powdered salt in twenty times their weight of dilute sulphuric acid is heated to boiling. In the presence of bromate, nitrates will be indicated by the development of the odor of ammonia, when the salt, together with an equal weight of iron and zinc filings, and solid potassium or sodium hydrate, is gently heated, in a test-tube, with an equal volume of water. If, however, ammonium salts be originally present as an ad- mixture, the ammonia must first be completely expelled, by heat- ing a portion of- the salt with a strong solution of potassium hydrate, after which the iron and zinc filings may be added, and the test subsequently performed for nitrates, as above described. Estimation : The estimation of sodium bromide, or the amount of chloride which may be contained therein, is most readily accomplished volumetrically. Two grams of sodium bromide, previously re- duced to powder and carefully dried, are dissolved in water to the measure of 100 cubic centimeters. 10 cubic centimeters of this solution, corresponding to 0.2 gram of sodium bromide, are then brought into a beaker, diluted with about 50 cubic centi- meters of water, and, after the addition of a few drops of a solu- tion of potassium chromate, a decinormal solution of argentic nitrate (page 9ei) is allowed to flow into the liquid from a burette until, with constant stirring, a permanent reddish-brown colora- tion is produced. If the salt is pure sodium bromide, 19.4 cubic centimeters of the silver solution will be required to produce this effect, as containing 0.33 gram of argentic nitrate, which corre- sponds to 0.2 gram of sodium bromide, according to the equation AgNOj : NaBr = 0.33 : 0.2. If the salt was pure sodium chloride, 170 103 34.18 cubic centimeters of the silver solution would be required for its complete precipitation, in accordance with a similar pro- portion ; the difference in the amount of silver solution, required for 0.2 gram of the two salts, would therefore be 84.18 — 19.4 = 14.78 cubic centimeters; from which it follows, that for each 0.1478 cubic centimeter of silver solution required in excess of 19.4 cubic centimeters, in order to effect complete precipitation, 1 per cent, of sodium chloride will be represented, as ^-^j'/ = 0.1478. It is evident that the presence of sodium iodide, or other alkaline chlorides or bromides, would influence the result in proportion to the extent of the admixture. The United States Pliarmacopoeia directs that if 3 grams of the well-dried salt be dissolved in distilled water to the measure SODIUM. 543 of 100 cubic centimeters, and 10 cubic centimeters of this solu- tion be treated with a few drops of test-solution of potassium bi- chromate, and then volumetric solution of argentic nitrate be added, not more than 29.8 cubic centimeters of the latter should be consumed before the red color ceases to disappear on stirring (indicating the absence of more than 3 per cent, of chloride). Fio. 161. SODII CARBONAS. SODIUM SEU NATRIUM CARBONICUM. Carhonate of Sodium. Sodium Carbonate. Ger. Kohlensaures Natriam ; Fr. Carbonate de soude ; Sp. Carbonato de sosa. Na.COj-l-lOHP; 286. Large, colorless, transparent, monoclinic prisms (Fig. 161), having the specific gravity 1.440, and containing 10 molecules (62.85 per cent.) of water of crystallization ; they effloresce in dry air, losing readily 5 molecules of water, and falling into a white powder, which, when heated to about 45° C. (113° F.), suffers a further loss of water, and is converted into a salt of the composition Na^COj-flljO {Sod ■' Carlonas Exsiccatus); the latter salt, when heat- ed to about 80° 0.(176°F.), loses the remainin.^ molecule of water, and becomes anhydrou.-^. The crystals, when heated, undergo aqueou- fusion at 34° C. (98.2° F.), and, after the evapo- ration of the water, the anhydrous salt fuses ai a red heat, without undergoing further change. Crystallized sodium carbonate is soluble in t 1.6 parts of water at 15° 0. (59° F.), and in 0.25 part of boiling water ; or in other words, 100 parts of water dis- solve, at 14° 0. (57.2° F.), 60.4 parts, at 36° C. (96.8°) 833 parts, and at 104° 0. = 219.2° F. (the boiling-point of the saturated solution), 445 parts, of crystallized sodium carbonate.* The salt is insoluble in alcohol. Its aqueous solution has a strong alka- line taste and reaction ; dropped into solution of tartaric acid, it produces no precipitation ; it effervesces with acids and acidulous salts, and decomposes the soluble salts of the earthy and heavy metals, forming, with most of them, insoluble or sparingly soluble * Sodium carbonate, with ten molecules of water of crystallization, is altered in its solution, at near the boiling-point, into a salt with only one molecule of water of crystallization, which is'less soluble, and gives rise to the anomaly in the solubility of sodium carbonate. A similar instance is met with in sodium sulphate and several other salts. 544 MANUAL OF CHEMICAL ANALYSIS. carbonates or hydrates. The salt imparts an intense yellow color to the non-luminous flame. Examination : Sodium hydrate is indicated in the solution of the salt by an alkaline reaction after complete precipitation with a slight excess of barium chloride, and subsequent filtration ; it maybe approxi- mately estimated by agitating a few grams of the salt with abso- lute alcohol, filtering the solution, and evaporating the filtrate, together with the alcoholic washings therefrom, to complete dry- ness in a tared porcelain capsule ; the weight of the dried residue will indicate approximately the amount of sodium hydrate con- tained in the salt. Chloride and sulphate are readily detected in the solution of the salt, slightly supersaturated with nitric acid, by testing it, in sepa- rate portions, with argentic nitrate for the fornier and with barium nitrate for the latter ; a white precipitate in either case will re- veal the presence of such impurities. Sodium sulphide will be indicated by a black precipitate, when a solution of the. salt ig tested with plumbic acetate or argentic nitrate, and may also be recognized by the development of the odor of hydrogen sulphide upon the addition of a little hydro- chloric acid. Sodium sulphite and hyposulphite (thiosulphate) may be detected in the aqueous solution of the salt, supersaturated with sulphuric acid, by warming with a little potassium bichromate, when a green coloration will be produced. The hyposulphite may also be specially tested for, by supersaturating the solution of the car- bonate with acetic acid, and subsequently adding a few drops of solution of argentic nitrate ; a white precipitate, gradually changing to brown, will indicate hj'posulphite ; if chlorides also be present, the resulting precipitate may be digested with ammonia-water, when the argentic chloride will become dissolved, leaving brown argentic sulphide if hyposulphite were present. Sodium sulphocyanide and ferrocyanide will be detected in the solution of the salt, slightly supersaturated with hydrochloric acid, by the addition of a few drops of solution of ferric chloride ; a blood-red coloration will indicate sulphocyanide, a blue colora- tion or precipitate, the presence of ferrocyanide. Calcium and Magnesium Salts. — A small portion of the salt is dissolved in acetic acid, and subsequently tested with ammonium oxalate, when a white precipitate will reveal the presence of cal- cium; to the filtrate, ammonium chloride, ammonia-water, in slight excess, and solution of ammonium phosphate are then succes- sively added, when the formation of a white, crystalline precipi- tate will indicate magnesium.. Silica, Iron, and Alumina. — A small portion of the salt is dis- solved in an excess of diluted' hydrochloric acid, the solution evaporated to dryness, and the dry mass treated with water acidu- SODIUM. 545 lated with hydrochloric acid ; a white insoluble residue will indi- cate silica. The slightly acid solution may then be tested for iron by the addition of a few drops of solution of potassium ferro- cyanide, and, after supersaturation with ammonia-water, an ensuing white, flocculent precipitate will indicate the presence of alumina. Arsenic. — A small quantity of the crystallized salt is dissolved in about four times its weight of water, the solution is slightly supersaturated with hydrochloric acid, filtered, if necessary, and then warmed to about 60 to 70= C. (140 to 158° F.) ; while still warm, hydrogen sulphide is allowed to pass into the solution until it is nearly cooled, the flask is then corked, and allowed to stand for twelve hours, when a flocculent, yellow precipitate would indi- cate the presence of arseniate. Estimation : One hundred parts of crystallized sodium carbonate require for exact saturation 48.95 parts of citric, or 52.44 parts of tartaric, acid. The quantitative estimation of the salt may, however, be more conveniently and accurately accomplished volu metrically, as follows. 26.5 grams of the crystallized salt are dissolved in water to the rheasure of 500 cubic centimeters. Of this solution, after the insoluble impurities have subsided and the liquid has become perfectly clear, 100 cubic centimeters (corresponding to 5.3 grams of anhydrous sodium carbonate)are brought into a beaker or small flask, and a few drops of litmus solution are added. A standard solution of oxalic or sulphuric acid (page 82) is then allowed to flow into the liquid from a burette, until an excess of the acid has been employed, and the liquid, after being heated to boiling, in order to completely expel the liberated carbonic acid gas, assumes a cherry-red color. The excess of acid is then in- versely titrated with a standard alkali solution (page 87) until a permanant blue coloration of the liquid is produced. From the amount of acid required for the exact neutralization of the solu- tion of sodium carbonate employed, the amount of the pure salt contained therein may be calculated :• one cubic centimeter of the normal acid solution corresponding to 0.053 gram of anhydrous, or 0.143 gram of crystallized sodium carbonate. If desired, the accuracy of the above result may be verified by determining the amount of carbonic acid contained in the salt, according to the method described on page 86, from which the equivalent amount of anhydrous or crystallized salt may readily be calculated : 100 parts of carbon dioxide corresponding to 240.91 parts of anhydrous, or 650 parts of crystallized, sodium car- bonate. The United States Pharmacopoeia directs that to neutralize 7.15 grams of sodium carbonate should require not less than 49 cubic centimeters of the volumetric solution of oxalic acid (cor- responding to at least 98 per cent, of pure, crystallized sodium 35 5i6 MANUAL OF CHEMICAL ANALYSIS. carbonate ; and to neutralize 2.65 grams of dried sodium car- bonate {Sodii Carlonas Exsiccatiis) should require not less than 86.3 cubic centimeters of the volumetric solution of oxalic acid (corresponding to at least 72.6 per cent, of anhydrous sodium carbonate). Table of the amount of crystallized and anhydrous Sodium Carbonate contained in 100 parts of the solution of the salt of different specific gravities (Schiff). SpeciSo Per cent, of Per cent, of Specific Per cent, of Percent, of gravity. NasCOj+lOHtO. NasCOj. gravity. NajCOa+lOH.O. Na.COs. 1.0038 1 0.370 1.1035 36 9.635 1.0076 3 0.741 1.1076 27 10.005 1.0114 3 1.112 1.1117 28 10.376 1.0153 4 1.482 1.1158 29 10.746 1.0193 5 1.853 1.1200 SO 11.118 1.0331 6 3-223 1.1243 31 11.488 1.0270 7 3.594 1.1284 32 11.859 1.0309 8 2.f65 1.1326 33 12.280 1.0348 9 3.335 I 1.1868 34 12.600 1.0388 10 3.706 1.1410 35 12.971 1.0428 11 4.076 1.1452 36 13.341 1.0468 13 4.447 1.1494 37 13.712 1.0508 13 4.817 1.1536 38 14.082 1.0548 14 5.188 1.1578 89 14.453 1.0588 15 5.558 1.1620 40 14.824 1.0628 16 5.929 1.1662 41 15.195 1.0668 17 6.299 1.1704 42 15.566 1.0708 18 6.670 1.1746 43 15.936 1.0748 19 7.041 1.17f-8 44 16.307 1.0789 20 7.412 1.1838 45 16.677 1 . 0830 21 7.783 1.1873 46 17.048 1 0871 22 8.153 1.1916 47 17.418 1,0912 23 8.523 1.1959 48 17.789 1.0953 24 8.894 1.2002 49 18.159 1.0994 25 9.264 1.2045 50 18.530 SODII CHLORAS. SODIUM SEU NATEIUM CHLORICUM. GMorate of Sodium. Sodium Chlorate. Ger. CUorsaures Natrium ; Fr. Chlorate de soude ; Sp. Clorato de sosa. NaOlO,; 106.4. Colorless, transparent crystals of the regular system, presenting the form of a cube with dodecahedral and tetrahedral surfaces (Fig. 162), and deviating the plane of jjolarization either to the right (a), or to the left {b). They are anhydrous, and permanent in dry air; when thrown upon burning charcoal they deflagrate, and when triturated or heated with readily oxidizable or combus- SODIUM. 547 tible substances, such as sugar, sulphur, etc., a more or less violent explosion ensues. On being heated the salt melts, and afterwards gives off oxygen, leaving finally, when strongly heated, a neutral residue of sodium chloride, amounting to 54.88 per cent, of its Fig. 162. weight, and completely soluble in water; this residue imparts an intense yellow color to the non-luminous flame, and its aqueous solution yields with argentic nitrate a white, curdy precipitate, insoluble in nitric acid, but readily soluble in ammonia-water. Sodium chlorate is soluble in 1.1 parts of water and in 40 parts of alcohol at 15° 0. (59° F.), in 0.5 part of boiling water, and in 43 parts of boiling alcohol. Its aqueous solution possesses a cool- ing, saline taste, and is neutral in its action upon litmus ; when mixed with concentrated hydrochloric acid, a deep greenish-yellow color is produced, and the odor of chlorine is evolved. Examination : Potassium chlorate, when present as an admixture or substitu- tion, will remain principally undissolved when the salt is treated with three times its weight of cold water, and may be detected in the saturated aqueous solution of the salt, by the formation of a white, crystalline precipitate on the addition of a concentrated solution of tartaric acid or sodium bitartrate. Nitrates may be detected by first heating a portion of the salt, in a test-tube, with about twice its weight of solid potassium or sodium hydrate, and a little water, in order to ascertain the ab- sence of ammonium salts, and subsequently adding a few iron and zinc filings, and again heating; if ammonium salts were found to be absent, or, if present, have been completely eliminated by the previous heating with caustic alkali, the odor of ammonia, developed upon the addition of the zinc and iron, will confirm' the presence of nitrates. Chlorides and sulphates are detected in the aqueous solution of the salt, acidulated with nitric acid, by white precipitates, when tested with argentic nitrate for the former, and with barium chlo- ride for the latter. Calcium salts may be detected in the dilute aqueous solution of 548 MANUAL OF CHEMICAL ANALYSIS. the salt, by an ensuing white precipitate on the addition of a few drops of solution of ammonium oxalate. Metallic impurities will be recognized in the aqueous solution of the salt, acidulated with hj'drochloric acid, by a dark coloration or precipitate upon saturation with hydrogen sulphide, or, after filtration, if necessary, and neutralization with ammonia-water, by the subsequent addition of ammonium sulphide. SODII CHLORIDUM. SODIUM SED NATRIUM CHLORATUM. Chloride of Sodium. Common Salt. Sodium Chloride. Ger. Chlornatrium, Kocbsalz ; Pr. Chlorure de sodium ; Sp. Cloruro de sodio. NaCl; 58.4.' Anhydrous, colorless, transparent, cubical crystals, often agglo- merated into hollow, quadrangular pyramids, or a white, granular powder, having a spec. grav. of 2.15 ; the salt is permanent in the air, but slightly deliquescent when containing traces of magnesium and calcium chlorides. When exposed to heat, sodium chloride decrepitates, from the presence of interstitial moisture, melts at a red heat, and volatilizes with partial decomposition at a high temperature. It imparts a yellow color to the flame, and evolves vapors of hydrochloric acid, when heated with strong sulphuric acid. Sodium chloride is almost equally soluble in water at all tem- peratures : 100 parts of water dissolve at 0° C. (32° F.) 35.52 parts, at 14° C. (57.2° F.) 35.87 parts, at 25° C. (77° F.) 36.13 parts, at 40° C. (104° F.) 36.64 parts, at 80° C. (176° F.) 38.22 parts, at 100° C. (212° F.) 39.61 parts, and at 110° C. (230° F.), the boiling-point of the saturated solution, 40.35 parts, of the salt; it is also soluble in glycerin, but not perceptibly soluble in abso- lute alcohol, in ether, or in chloroform, but its solubility in alco- hol increases with the quantity of water contained therein. Its aqueous solution is neutral, and remains colorless upon the ad- dition of chlorine-water (distinction from the alkaline bromides and iodides) ; it forms white precipitates with the solutions of those metallic salts whose chlorides are quite or almost insoluble in water — for instance, with the salts of silver, bismuth, and lead, and with the subsalts of mercury. Examination : Water. — The amount of water, which may be present as inter- stitial moisture, is readily determined by drying a small portion of the salt at 150° C. (302° F.) until its weight remains constant. Potassium chloride will be indicated in the concentrated aque- ous solution of the salt, from Avhich a portion of the sodium chlo- SODIUM. 649 ride has been separated by crystallization, by the fornaation of a yellow crystalline precipitate with an excess of solution of plati- num chloride, and the sabsequent addition of one-fifth of its volume of alcohol; with the employment of a weighed quantity of the salt, the precipitate of potassio-platinic chloride thus ob- tained, after washing upon a filter with a mixture of alcohol and ether, and drying at 100° 0. (212° F.) until of constant weight, may be finally weighed, and therefrom the amount of potassium chloride calculated : 100 parts of potassio platinic chloride, K^PtCl,,, corresponding to 30.50 parts of potassium chloride. Nitrates. — To a little of the solution of the salt, contained in a test-tube, a drop of solution of indigo is added, so as to impart to the liquid a bluish tint, subsequently a few drops of concentrated sulphuric acid, and the mixture gently heated ; if nitrates be pres- ent, decoloration of the liquid will ensue. A confirmatory and still more sensitive test is to dip a bright zinc rod into a test-tube, or to suspend it in a small beaker (Fig. 163), containing a little di- luted sulphuric acid, to which a Fig. 163. few drops of a solution of pure po- tassium iodide, a little mucilage of starch, and subsequently twice the volarae of the liquid of a solution of the salt, has been added ; if nitrate be present, a bluish coloration, ema- nating from the zinc, will be pro- duced in the liquid. Iodides and Bromides. — A portion of the finely powdered salt is digested with about ten times its weight of warm alcohol, and the liquid, after being allowed to cool, is filtered, and evaporated to dryness at a gentle heat. The residue thus obtained is dis- solved in a little water, a little mucilage of starch added, and subsequently chlorine-water, drop by drop, the liquid being gently stirred with a glass rod. The presence of even minute traces of iodide will cause a bluish coloration of the fluid ; when iodide alone is present, the blue color will gradually become purple upon the continued addition of the chlorine-water, and decrease, until it finally disappears; but, when bromide also is present, the blue color will not change to purple, but become successively brownish, then orange, and finally yellow. Alkaline and earthy sulphates are recognized in the dilute solu- tion, acidulated with hydrochloric acid, by a white precipitate with barium chloride. Magnesium and calcium chlorides are detected in the solution of sodium chloride by a white turbidity taking place upon the addi- tion of a diluted solution of sodium carbonate. They may be distinguished and separated from each other by adding to a solu- tion of the salt, ammonium chloride, ammonia- water, and solution 550 MANUAL OF CHEMICAL ANALYSIS. of ammonium oxalate, when an ensuing white precipitate will indicate calcium ; the liquid is then filtered, and to the filtrate a solution of ammonium or sodium phosphate is added, when the formation of a white, crystalline precipitate will reveal the presence of magnesium. Metallic impurities may be detected by the occurrence of a dark coloration or precipitate, when the solution of the salt, acidulated with hydrochloric acid, is saturated with hydrogen sulphide, or, after filtration, if necessary, and neutralization with ammonia- water, by the subsequent addition of ammonium sulphide. Estimation : One gram of the powdered and dried salt yields, when com- pletely precipitated by argentic nitrate, 2.450 grams of argentic chloride. Its purity, when free from other chlorides, may also be conveniently and accurately determined volumetrically, by dis- solving 0.2 gram of the powdered and dried salt, in a beaker, in about 20 cubic centimeters of water, and, after the addition of a few drops of a solution of potassium chromate, allowing a deci- normal solution of argentic nitrate (page 98) to flow into the liquid from a burette until, with constant stirring, the red coloration of argentic chromate remains permanent. The number of cubic cen- timeters of the silver solution required to produce this effect, when multiplied by the decimal 0.00584, will represent the amount of pure sodium chloride in the quantity under estimation. By the employment of exactly 0.292 gram of the salt, and pro- ceeding as above, the number of cubic centimeters of- the silver solution required to effect complete precipitation, when multiplied by 2, will indicate at once the percentage amount of pure sodium chloride. SODII HYDRAS. SODA. SODIUM SEU NATRIUM HYDRICUM. NATRIUM CAUSTICUM. Gausiic Soda. Soda. Sodium Hydrate. Ger. Natriumhydroxyd, Aetznatron ; Fr. Soude caustique ; Sp. Sosa causlica. NaOH; 40. Hard, white, fusible masses, in flat, tabular fragments or sticks, of a fibrous fracture, or a coarse, white powder ; it is very deli- quescent in moist air, but afterwards becomes dry in consequence of the absorption of carbonic acid gas, and the formation of sodium carbonate. It melts below a red heat to a clear, oily liquid, and at a strong red heat it is slowly volatilized unchanged. Heated upon the looped end of a platinum-wire, it imparts to the non- luminous flame an intense yellow color. SODIUM. 551 Sodium hydrate is soluble in 1.7 parts of water at 15° C. (59° F.), and in 0.8 part of boiling water, with the evolution of heat, and is also freely soluble in alcohol; when the concentrated aqueous solution is cooled to— 8° 0.(17.6° F.), the hydrate, 2NaOH + 7Hp, is deposited in large, transparent, monoclinic tables, which melt at 6° C. (42.8° F.). The solutions of sodium hydrate are highly alkaline and caustic, and act destructively upon animal tissues; when dropped into a diluted solution of plumbic acetate, it causes a white turbidity, which disappears again upon continued addi- tion of the caustic solution, without leaving a black residue (evi- dence of the absence of sodium sulphide). When the concentrated aqueous solution is dropped into strong alcohol, no precipitate should take place, as its appearance would indicate the presence of sodium carbonate, sulphate, chloride, or other salts, less soluble in alcohol. Sodium hydrate may readily be distinguished from potassium hydrate, by dropping concentrated solutions of the salts into solu- tion of tartaric acid, care being taken that the acid reaction of the solution predominates; sodium hydrate will yield no precipitate unless containing potassium hydrate to a considerable extent, while potassium hydrate forms a white, granular precipitate. Examination : Sodium carbonate may be detected in the solution of the hydrate by effervescence, or by the formation of gas-bubbles, on the addi- tion of a little acetic acid, and by the occurrence of a white tur- bidity upon the admixture of an equal volume of lime-water with the aqueous solution of the hydrate. Chloride and sulphate are detected in the diluted solution, super- saturated with diluted nitric acid, by ensuing white precipitates when tested, in separate portions, with argentic nitrate for the former, and with barium nitrate for the latter. Nitrate may be detected in the solution, supersaturated and strongly acidulated with sulphuric acid, by the addition of a drop of indigo solution, and gently heating ; if nitrate be present, de- coloration of the liquid will ensue. Cyanide may be detected in the dilute solution of the salt, after the addition of a few drops of a solution of a ferrous and a ferric salt, and subsequent supersaturation with hydrochloric acid, by the formation of a precipitate of Prussian blue. Silica and aluminium salts may be detected by supersatu- rating the dilute solution of sodium hydrate with an excess of nitric acid, and subsequently evaporating to dryness ; the residue is treated with warm water, and should be wholly soluble ; an insoluble residue would indicate silica ; the solution is filtered, and the filtrate tested with ammonia-water, when the forma- tion of a white, gelatinous precipitate would indicate aluminium salts. Metallic impurities are detected by a dark coloration or turbidity 552 MANUAL OF CHEMICAL ANALYSIS. of the solution, when saturated with hydrogen sulphide, and, in another portion of the solution, after previous supersaturation with hydrochloric acid. Estimation : 2 grams of the dry sodium hydrate are dissolved in about 20 cubic centimeters of water, in a beaker, a few drops of litmus solution added, and a standard solution of oxalic or sulphuric acid (page 82) allowed to flow into the liquid from a burette until, with constant stirring, the blue tint of the liquid is just changed to a permanent pink. The number of cubic centimeters of normal acid solution thus required for the exact neutralization of the above amount of sodium hydrate, when multiplied by 2, will represent, without further calculation, its percentage purity. By the employ- ment of other amounts of the hydrate, the calculation may readily be made, with the consideration that one cubic centimeter of the normal acid solution corresponds to 0.04 gram of pure sodium hydrate. If the sodium hydrate contains carbonate, the above estimation will only be strictly cftrrect when, in a weighed amount of the hydrate, the amount of carbonic acid contained therein is deter- mined, as described on page 86; for 1 part of carbonic acid, 1.818 parts of sodium hydrate are deducted from the found amount of the latter, and the remainder then calculated as pure sodium hydrate. The United States Pharmacopoeia directs that to neutralize 2 grams of soda should require not less than 45 cubic centimeters of the volumetric solution of oxalic acid (corresponding to at least 90 per cent, of absolute sodium hydrate). For the determination of the strength of aqueous solutions of sodium hydrate, as based upon the specific gravity of the latter, see Liquor Sodae, page 413. SODII HYPOPHOSPHIS. SODIUiM SEU NATRIUM HYPOPHOSPHOROSUM. Hypophosphite of Sodium. Sodium Hypopho.iphite. Ger. Uuterpliospliorigsaures Natrium ; Fr. HypophospUite de sonde ; Sp. Hipot6sfito de sosa. NaH,PO,-»-H,0; 106. Small, colorless, transparent, rectangular tables, of a pearly lus- tre, or a white, granular powder, containing one molecule (17 per cent.) of water of crystallization, and deliquescent on exposure to the air. When heated in a dry test-tube, the salt first loses its water of crystallization, and afterwards evolves spontaneously inflammable hydrogen phosphide, burning with a bright light ; a SODIUM. , 553 residue of sodium pyrophosphate, containing traces of red amor- phous phosphorus, is left behind, which imparts an intense yellow- color to the non-luminous flame. Sodium hypophosphite is soluble in 1 part of water, and in 30 parts of alcohol at 15° C. (59° F.), in 0.12 part of boiling water, and in 1 part of boiling alcohol (distinction from barium and cal- cium hypophosphites and sodium phosphate, which are insoluble in alcohol) ; it is insoluble in pure ether. Its aqueous solution has a sweetish, saline taste, a slightly alkaline reaction, and is gradually oxidized on exposure, especially when warm ; it affords, when much diluted, a white precipitate with argentic nitrate, which quickly turns brown, and is converted into metallic silver; when acidulated with hydrochloric acid and added to an excess of solution of mercuric chloride, it first produces a white precipitate of mercurous chloride (calomel), and, on further addition, metallic mercury is separated. Examination : Carbonates may be detected in the aqueous solution of the salt by effervescence on the addition of an acid, and by the production of a white precipitate when added to lime-water. Soluble phosphates and phosphites will be indicated in the aque- ous solution by a white precipitate on the addition of a few drops of solution of calcium chloride; the presence of phosphates may also be recognized by adding to the solution a little test mag- nesium mixture, when a white, crystalline precipitate will be produced. Sulphates and chlorides may be detected in the aqueous solu- tion, acidulated with nitric acid, by testing it, in separate portions, with barium chloride for the former, and with argentic nitrate for the latter ; a white precipitate in either instance will reveal the presence of such impurities. Calcium and Potassium Salts. — The former will be indicated by a white precipitate on the addition of a few drops of solution ot ammonium oxalate, and the latter by a white, crystalline precipi- tate on the addition of a concentrated solution of tartaric acid or sodium bitartrate. Metallic impurities may be detected in the solution of the salt, acidulated with hydrochloric acid, by a dark coloration or a pre- cipitate with hydrogen sulphide: or, after filtration, if necessary, and supersaturation with ammonia-water, by the addition of am- monium sulphide. 554: MANUAL OF CHEMICAL ANALYSIS. SODII HYPOSULPHIS. SODIUM SEU NATRIUM HYPOSULFUROSUM SEU SUBSULFUROSUM SEU THIOBULPURICUM. Hyposulpliite of Sodium. Sodium Hyposulphite. Sodium TMosulpliate. * Ger. UnterscUwefligsaui-es Natruim, Tliioscliwefelsaures Natrium ; Fr. Hypo- sulfite de soude ; Sp. Hiposulfito de sosa. Na,S,03 + 5Hp = SO,<^g^^%5H,0; 248. Large, colorless, transparent, monoclinic prisms or tables (Fig. 164), having the specific gravity 1.736, and containing five mole- cules (36.3 per cent.) of water of ciystalliza- FiG. 164. tion ; tbey are permanent at ordinary tem- peratures, but efilorescent in dry and warm air ; when quickly heated to about 48° C. (118.4° F.), the salt melts in its water of crys- tallization, and, after becoming eflSoresced by exposure to a gentle heat, and subsequently heating to 100° C. (212° F.), the entire amount of water of crystallization is ex- pelled; at a higher temperature it is decom- posed, with the evolution of vapors of sul- phurous acid and sulphur, which take fire, and burn away, leaving behind a reddish-yellow residue of neutral sodium sulphate, containing a little sulphide. Sodium hyposulphite is soluble in 1.5 parts of water at 15° C. (59° F.), and in half its weight of boiling water, in the latter case attended by partial decomposition of the salt ; it is also soluble in oil of turpentine, and causes the odor of the latter to disap- pear, but is insoluble in alcohol. The aqueous solution has a cooling and afterward a bitter taste, and a feebly alkaline reac- tion ; on exposure to the air, it is gradually decomposed, the hyposulphite being converted into sulphur and sodium sulphite, which latter salt, on exposure of the solution to the air, is further decomposed into sulphur and sodium sulphate ; when dropped into diluted hydrochloric, nitric, or sulphuric acid, solution of sodium hyposulphite gradually becomes turbid, sulphur being precipitated, and sulphurous acid disengaged. With solution of barium chloride, a concentrated solution of sodium hyposulphite forms a white precipitate, which dissolves, * Since the discovery of the acid HjSO.^, the appellation of sodium hyposul- phite has been transferred to a salt of the composition NaHSO.j, while the acid entering into the composition of the above salt may be considered as sul- phuric acid, in which an oxygen atom is replaced by sulphur, or, as thiosul- phuric acid. The salt is therefore, scientifically, more correctly designated as sodium thiosulphalc SODIUM. 555 however, upon sufficient dilution with water (evidence of the absence of sodium sulphate) ; when dropped into a dilute solution of argentic nitrate, a white precipitate is formed, which soon be- comes yellow, and finally black ; when, however, on the other hand, the argentic solution is dropped into the solution of sodium hypo- sulphite, the ensuing white precipitate of argentic hyposulphite is redissolved upon agitation, and the solution remains clear as long as sodium hyposulphite is in excess. With solution of ferric chloride, a transient violet coloration is produced, with the for- mation of sodium tetrathionate, while the ferric salt becomes re- duced to the ferrous state : Fe,01,-»-2]Sra,S,O3 = 2FeOI,-l-]Sra,Sp,-|-2NaCl. "When iodine, either alone or dissolved in alcohol, is added to solution of sodium hyposulphite, it is immediately decolorized, sodium iodide and tetrathionate being formed : 2Na,S,03.5H,0 4- I, = 2N'aI -1- Na,S,0, -f lOH.O. 496 253.2 (248) (126.6) This reaction takes place in the proportion, approximately, of one part (126 6) of iodine to two parts (248) of crystallized sodium hyposulphite ; a solution in these proportions dissolves iodine readily, with a brown color, but it is decolorized again upon the restoration of the above proportions by the addition of sodium hyposulphite. Solution of sodium hyposulphite is a solvent for several otherwise insoluble compounds, as argentic oxide, argentic iodide, bromide, and chloride, plumbic iodide, plumbic and calcium sul- phates, etc. Examination : Sodium sulphate is detected by the occurrence of a white pre- cipitate, when a solution of 1 part of the s^lt in 80 parts of water is tested with barium nitrate. Sodium carbonate is indicated by effervescence, when a concen- trated solution of the salt. is dropped into diluted acetic or hydro- chloric acid. Chloride may be detected by fusing the salt with twice its weight of pure potassium nitrate, dissolving the fused mass in water, and, after acidulating with nitric acid, testing with ar- gentic nitrate ; a white curdy precipitate will reveal the presence of chloride. Sodium sulphide will be indicated in the aqueous solution of the salt by the formation of a white precipitate with zinc acetate, a black precipitate with an ammoniacal solution of argentic ni- trate, and a violet-red coloration on the addition of sodium nitro- prusside. 556 MANUAL OF CHEMICAL ANALYSIS. Sodium sulphite will be indicated by its more sparing solu- bility in water, and may be recognized in the aqueous solution by the production of a brown-red color with sodium nitro-prus- side ; if sodium sulphide is also present, the latter must first be removed by precipitation with zinc acetate before the application of the above test. Calcium salts may be detected in the aqueous solution of the salt by the formation of a white precipitate when tested with ammonium oxalate. Estimation : The estimation of the salt may be readily and accurately ac- complished volumetrically by the following process, which is based upon its property of combining with iodine, with the for- mation of sodium iodide and tetrathionate, as above described. 1 gram of crystallized sodium hyposulphite is dissolved, in a beaker, in 10 cubic centimeters of water, a little mucilage of starch is then added, and subsequently a decinormal solution of iodine (page 93) allowed to flow into the liquid from a burette until, with constant stirring, a permanent blue tint is produced. If the salt is perfectly pure, 40.32 cubic centimeters of the iodine solution will be thus required ; if a smaller amount of the iodine solution effects a blue coloration of the liquid, the salt is impure, and the calculation may readily be made with the consideration that 1 cubic centimeter of the decinormal iodine solution corre- sponds to 0.0248 gram of pure crystallized sodium hyposulphite, NajS^Oj-t-SH^O. If the salt should have been found to contain sodium sulphide as an impurity, the latter must first be removed from the solution by precipitation with zinc acetate, and filtered, before being subjected to estimation with the solution of iodine. The United States Pharmacopoeia directs that a solution of 2 grams of the salt in 10 grams of water, agitated for a short time with 1 gram of iodine, should yield a colorless liquid, with at most only a faint, white opalescence (corresponding to about 98 per cent, of pure sodium hyposulphite). SODII lODIDUM. SODIUM SEU NATRIUM lODATUM. Iodide of Sodium. Sodium Iodide. Ger. Jodnatrium ; Fr. lodure de sodium ; Sp. loduro de sodio. Nal; 149.6. A white, granular powder, or minute, colorless, cubical crys- tals, anhydrous when crystallized at temperatures above 40°' C. (104° F.), or monoclinic prisms, containing two molecules (19.35 SODIUM. 557 per cent.) of water of crystallization, when crystallized at ordi- nary temperatures. The salt is deliquescent on exposure to the air, and in a moist atmosphere becomes gradually decomposed, with the liberation of iodine and absorption of carbonic acid, ac- qiiiring thereby a reddish color ; when exposed to heat, the salt fuses with the liberation of iodine and absorption of oxygen, and at a full red heat it is slowly volatilized. When a little of the salt is heated, in a test-tube, either in concentrated sulphuric acid, or with a little potassium bisulphate, violet-colored vapors of iodine are evolved ; and when dissolved in a little water, a few drops of chlorine-water added, and the mixture subsequently shaken with a little chloroform or carbon bisulphide, a fine pur- ple or violet color will be imparted to the latter. A fragment of the salt, when heated upon the looped end of a platinum-wire in the non-luminous flame, imparts to the latter an intense yellow color. Sodium iodide is soluble in 0.6 part of water and in 1.8 parts of alcohol at 15° C. (59° F.), in 0.3 part of boiling water and in 1.4 parts of boiling alcohol, and is also freely soluble in glycerin. The aqueous solution possesses a saline, slightly bitter taste, and a neutral or feebly alkaline reaction; it gives no precipitate with tartaric acid, with sodium bi tartrate, or with sodium carbonate, but forms a yellowish one with argentic nitrate, insoluble in diluted nitric acid or ammonia-water, and a vermilion-red one with mercuric chloride, soluble in an excess of either reagent. Examination : Impurities and admixtures, less soluble in alcohol, are indicated hy a white turbidity or granular deposit, when a saturated aque- ous solution of the salt is dropped into an excess of strong alcohol. Potassium salts are indicated by a white, crystalline precipitate in the concentrated aqueous solution, when added to a strong solution of sodium bitartrate. Chloride and bromide may be detected by dissolving 1 gram of the salt in 10 cubic centimeters of ammonia- water, and agitating the solution with a solution of 1.2 grams of argentic nitrate in 20 cubic centimeters of water; the mixture is then filtered, and the filtrate supersaturated with 7 cubic centimeters of concentrated nitric acid, when no immediate cloudiness of the liquid should be produced ; a white turbidity or precipitate would indicate the prese^ice of more than about 0.5 per cent, of chloride or bromide. If a precipitate is formed, it may be collected upon a filter, washed, and subsequently transferred to a test-tube, and agitated with chlorine-water ; if argentic chloride, it remains unchanged ; if bromide, the chlorine-water will assume a yellowish or reddish color, which, on agitation with chloroform, will be transferred to the latter. Carbonate may be detected, in the aqueous solution, by a white 558 MANUAL OF CHKMICAL ANALYSIS. turbidity when mixed with twice or thrice its volume of lime- water, and will also be indicated by a strongly alkaline reaction, when a few fragments of the salt are placed upon moistened red litmus-paper. Sulphate may be detected in the diluted solution of the iodide, previously acidulated with hydrochloric acid, by a white precipi- tate with barium chloride. lodate may be detected in the aqueous solution of the salt, by adding a few drops of mucilage of starch, and then a few drops of a concentrated solution of tartaric acid ; if iodate be present, a violet or bluish coloration will ensue. Or, the aqueous solution, mixed with a few drops of a concentrated solution of tartaric acid, may be agitated with a little chloroform or carbon bisul- phide, when the latter will assume a red or violet color if iodate be present. Sodium nitrate may be detected in the aqueous solution, if the salt be free from iodate, by the addition of a few drops of muci- lage of starch, and subsequently adding a little of this liquid to a mixture of zinc and diluted hydrochloric acid, in which the de- velopment of hydrogen is actively taking place ; if any nitrate be present, the liquid will gradually assume a reddish-violet or blue color. If iodate be present, the presence of nitrate may also be determined by completely precipitating a solution of the salt with argentic sulphate, filtering, and adding to the filtrate, in a test- tube, a concentrated solution of ferrous sulphate, and afterwards concentrated sulphuric acid, so as to form two layers (Fig. 165); a dark-brown coloration at the line of contact of the two liquids will reveal the presence of nitrate. SODIUM. 559 Estimation : A quantitative estimation of the purity of sodium iodide may- be made by dissolving 1 gram of the salt in 10 grams of ammo- nia-water, and adding to the solution a solution of argentic nitrate until a precipitate ceases to be produced ; the precipitate of argen- tic iodide is then collected upon a filter, well washed with water, and finally dried at 100° C. (212° F.) until of constant weight. It the sodium iodide is pure, 1.566 grams of argentic iodide should be obtained, or 100 parts of argentic iodide correspond to 63.83 parts of sodium iodide. The estimation of the purity of sodium iodide may also be accomplished volumetrically by the foUov/ing method. This is based upon the fact that mercuric chloride precipitates from a solution of sodium iodide, red mercuric iodide, which is soluble in an excess of a solution of sodium iodide with the formation of a soluble double salt, and the solution of the latter again yields upon the addition of mercuric chloride a precipitate of mercuric iodide : 2NaI + HgCl, = Hgl, + 2NaCl. Hgl, + 2NaI = I-IgNa,I„ or 4NaI -f HgOl, = HgNaJ, + 2NaCl. 598.4 271 (5) (2.26) 2.26 grams of mercuric chloride are dissolved in water to the measure of 100 cubic centimeters, and 5 grams of the sodium iodide under examination are likewise dissolved in water to the measure of 100 cubic centimeters.* 10 cubic centimeters of the sodium iodide solution are then brought into a beaker, which is placed upon a sheet of white paper, and to the solution is added, from a burette, the above solution of mercuric chloride until, with constant stirring, a permanent precipitate of mercuric iodide is just produced. The number of cubic centimeters of the mer- curic chloi'ide solution required to produce this reaction, when multiplied by 10, will represent the percentage amount of pure sodium iodide contained in the salt. The accuracy of the result of the estimation by the above method is not influenced by the presence of chloride or of considerable amounts of bromide. * Tlie roFults attained by this method are rendered more accurate, when, instead of dissolving the mercuric chloride and sodium iodide in water, alcohol 17 5 100 of 17.5 per cent, by volume is employed. From the formula x= — '' ' , in n ■which n represents the percentage strength of the alcohol to be diluted, the volume of alcohol may be calculated which must be added to the water in order to obtain 100 parts of alcohol of 17.5 per cent, by volume. 560 MANUAL OF CHEMICAL ANALYSIS. SODII NITRAS. SODIUM SEU NATRIUM NITRICUM. Nitrate of Sodium. Chili Saltpetre. Sodium Nitrate. Ger. Salpetersaures Natrium ; Fr. Azotate de soude ; Sp. Nitrato de sosa. NaNO^; 85. Anhydrous, colorless, transparent, obtuse-rhombohedral crys- tals of the hexagonal system (Fig. 166), having a specific gravity of 2.26 ; they are deliquescent in damp Fig. 166. air, and generally of a moist appearance. ^ The salt melts at 312" 0. (594° F.) with- ^' out decomposition, but, on further heating, V becomes decomposed, with the evolution of k oxygen, and leaves a residue which emits P^ nitrous vapors on the addition of sulphuric -» acid ; when thrown upon burning coals, ^^ the salt deflagrates, although not so vio- lently as potassium nitrate, and imparts an intense yellow color to tbe non-luminous flame. Sodium nitrate is soluble in 1.5 parts of water at 15° C. (59° F.), and in 0.6 part of boiling water ; it is but sparingly soluble in cold alcohol, but Soluble in 40 parts of boiling alcohol. The aqueous solution has a sharp, cooling, saline, and slightly bitter taste, and is neutral in its action upon litmus ; when heated with potassium chloride or carbonate, it is decomposed, with the forma- tion of potassium nitrate and sodium chloride or carbonate. Its concentrated solution may readily be distinguished from that of potassium nitrate by not being acted upon by a solution of sodium bitartrate, which gives a white, granular precipitate with potassium nitrate. Examination : Chlorides and sulphates are detected in the diluted solution, after acidulation with diluted nitric acid, by white precipitates when tested, in separate portions, with argentic nitrate for chlo- ride, and with barium nitrate for sulphate. Sodium Iodide and lodate. — To a solution of the salt a few drops of an aqueous solution of hydrogen sulphide are added, then a little mucilage of starch, and finally a few drops of chlorine- water allowed to flow upon the surface of the liquid ; if either iodide or iodate is present, a blue zone will appear at the line of contact of the two liquids. If iodide and iodate are simultane- ously present, the solution of the salt will also afford, on the simple addition of a few drops of diluted sulphuric acid, a yellow or brownish -yellow color, due to the elimination of free, iodine, which, upon agitation with a little carbon bisulphide, will impart to the latter a violet-red color. SODIUM. 561 lodate may be specially tested for, if desired, by dissolving a little of the salt in ten times its weight of water, acidulated with diluted sulphuric acid, adding to the solution a few drops of mucilage of starch, and subsequently a strip of pure metallic zinc ; if iodate be present, a violet or bluish coloration of the liquid will be produced. Calcium and magnesium salts are indicated in the warm solution of the salt by a white turbidity on the addition of a solution of sodium carbonate ; they may be distinguished by adding a little ammonium chloride and ammonia-water to the dilute solution of the salt, and testing it with ammonium oxalate for calcium, and, after filtration, if necessary, by the addition of sodium phosphate for magnesium. Metallic impiirities will be indicated by a dark coloration or precipitate, when a solution of the salt, acidulated with hydro- chloric acid, is saturated with hydrogen sulphide, or after filtra- tion, if necessary, and neutralization with ammonia- water, by the subsequent addition of ammonium sulphide. Estimation : The proper amount of nitric acid contained in the salt ma}' readily be determined by igniting it, at a red heat, in a small porcelain crucible, with an equal weight of concentrated sulphuric acid, until it ceases to lose weight. One gram of the salt, if per- fectly pure, will thus afltbrd a residue of sodium sulphate, weigh.- ing 0.835 gram. The determination of the proper amount of sodium in tlie salt, when free from potassium, may also readily be accomplished as follows. About 5 grams of the dry sodium nitrate, contained in a porcelain capsule, are repeatedly evaporated with a solution of about 8 grams of oxalic acid to dryness, until completely converted into sodium oxalate. The latter is then, by ignition, converted into sodium carbonate, which is dissolved in water, and, after the addition of a few drops of litmus solution, titrated with a standard solution of oxalic or sulphuric acid (page 82), as described under sodium carbonate, on page 545. The cal- culation may then be made with the consideration that one cubic centimeter of normal acid corresponds to 0.053 gram of sodium carbonate, or, as its equivalent, 0.085 gram of pure sodium nitrate. SODII PHOSFHAS. i SODIUM SEU NATRIUM PHOSPHORICUM. Phosphate of Sodium. Tribasic Sodium Phosphate. Di-sodium Hydrogen Orthophosphate. Ger. Phosphorsaures Natrium ; Fr. Phosphate de soude ; Sp. Fosfato de sosa. Na,HP0,-fl2H,0; 358. Large, colorless, transparent, monoclinic prisms (Fig. 167), con- taining 12 molecules (60.3 per cent.) of water of crystallization; 36 562 MANUAL OF CHEMICAL ANALYSIS. Fig. 167. thry readily effloresce and become opaque on exposure to the air, losing thereby, at common temperatures, 5 molecules (25.1 per cent.) of water, and become converted into a salt of the composition Na^HPO^ + TH^O, which may also be obtained from solutions of the ordinary salt, in a crystalline form, at temperatures above 33° C. (91.4° F.); on continued heating to 100=^ C. (212° F.), the salt loses the entire amount (60.3 per cent.) of water of crystallization. When heated to about 40° 0. (104° F.), sodium phosphate first undergoes aqueous fusion, and after- Ward melts at a red heat into a limpid glass of sodium pyrophosphate, which becomes opaque on cooling. Sodium phosphate is soluble in 6 parts of water at 15° C. (59° F.), and in 2 parts of boiling water, but is insoluble in alco- hol. Its solution has a cooling, saline taste, a faintly alkaline reac- tion, affords no effervescence upon the addition of an acid, and gives with solution of argentic nitrate, a bright-yellow precipitate, soluble in both ammonia- water and nitric acid ; the amraoniacal solution remains unchanged, when the test-tube, wherein it is con- tained, is immersed in boiling water (distinction from the similar argentic arsenite, whose ammoniacal solution deposits metallic sil- ver upon the walls of the test-tube upon warming). With test magnesium mixture, sodium phosphate gives a white crystalline precipitate, insoluble in an excess of the salt as well as of the reagent. Examination : Sodium carionate is detected by effervescence, upon the addition of hydrochloric acid to the concentrated solution of the salt. Sulphates and chlorides are detected in the diluted solution, strongly acidulated with nitric acid, when tested in separate por- tions, with barium chloride for sulpiiate, and with argentic nitrate for chloride. Calcium and ma^jnesium salts will be indicated in the solution by a white precipitate on the addition of ammonia-water: They may be distinguished, by adding to the solution of the salt a few drops of a solution of ammonium oxalate, when a white precipi- tate will indicate calcium, and, after filtration, if necessary, and tiie addition of ammonia-water, an ensuing white, crystalline pre- cipitate will reveal tlie presence of magnesium. Metallic Impurities. — About 20 grams of the salt are dissolved in the requisite quantity of water, a few drops of hydrochloric acid added, and the solution, after beiilg heated to boiling, is satu- rated with hydrogen sulphide; the flask is then corked and allowed to stand in a warm place for about twelve hours. A yelr SODIUM. 563 Fig. 168. low precipitate would indicate arsenic, a dark one, the presence of other metallic impurities. The solution, after filtration, if neces- sary, may be neutralized with amraonia-water, and tested with ammonium sulphide, when an ensuing dark coloration or precipi- tate will likewise reveal the presence of metallic impurities. As a confirmatory test, or if the presence of other metals requires a special test for arsenic, about 15 grams of the sodium phosphate are dissolved in a little more than an equal weight of pure, concentrated hydrochloric acid in a wide test tube, the solu- tion being effected by dipping the tube into hot water and by agitation; a strip or roll of bright copper-foil is then completely immersed in the liquid, the tube again dipped into boiling water, and allowed to stand therein for half an hour. The copper must remain bright; a grayish or grayish-black coating of the copper would be evidence of the presence of arseyiic. Another simple test for arsenic consists in dissolving a little of the salt in dilute sulphuric acid, in a test-tube, adding thereto a few fragments of pure metallic zinc, and placing over the mouth of the tube a disk of white bibulous paper, previously moistened with a drop of solution of argentic nitrate (Fig. 168); if arsenic be present, a dark metallic stain will be pro- duced upon the paper. Estimation : The purity of sodium phosphate may be quantita- tively determined by dissolving 1 gram of the salt in about ten times its weight of water, and adding to the solution test magnesium mixture, until a precipitate ceases to be produced; the mixture is then allowed to stand for several hours, the precipitate collected upon a filter, washed with a mixture of one part of ammonia- water and three parts of water, and, after being allowed to dry, is brought into a weighed porcelain crucible, and strongly ignited at a red heat. If the salt be pure, the residue of magnesium pyrophosphate thus obta.ned will weigh 0.31 gram, or 100 parts of magnesium pyro- phosphate correspond to 322.52 parts of crystallized sodium phosphate, NaJ-IPO^-f- I2H2O. TJie puritv of the salt, in the absence of other sodium salts, may also be determined by the estiniation of the amount of contained sodium. 0.5 gram ot the salt is dissolved in a little water, a solution of plumbic acetate added until a precipitate ceases to be produced, and subsequently filtered; the filtrate is then saturated with hydrogen sulphide, filtered from the precipitate of plumbic sulphide, and, after acidulation with hydro- chloric acid, evaporated to dryness on the water-bath. The residue of sodium chloride is then brough* into a weighed porcelain cru- cible, dried first at about 110° C. (230° F.), and finally gently \ 564 MANUAL OF CHEMICAL ANALYSIS. ignited, and weighed. From the weight of the residue thus obtained the amount of phosphate may be calculated: 100 parts of sodium chloride corresponding to 3*05.98 parts of crystallized sodium phosphate, Na^HPOj + lSHjO. SODII PYROPHOSPHAS. SODIUM SEU NATRIUM PYROPHOSPHORICUM. Pyrophosphate of Sodium. Sodium Pyro- or Tetraphosphate. Ger. Pyrophosphorsaures Natrimn ; Fr. Pyrophosphate de soude ; Sp. Pirofosfato de sosa. ]Sra,PA+10H,O; 446. Colorless, transparent, brilliant, monoclinic prisms, or a white granular powder, containing ten molecules (40.36 per cent.) of water of crystallization, and permanent in the air; when exposed to heat, the salt gives off its water of crystallization, without pre- viously undergoing aqueous fusion (distinction from sodium phos- phate), fuses at a higher temperature, and, on cooling, concretes to a crystalline semi-transparent mass. Sodium pyrophosphate is soluble in 12 parts of water at 15° C. (59° F.), and in 1.1 parts of boiling water, but is insoluble in alcohol. Its aqueous solution possesses a saline taste and an alkaline reaction ; it yields with a slight excess of a neutral solu- tion of argentic nitrate a white precipitate of argentic pyrophos- phate, and the filtrate therefrom is neutral in its action upon test- paper (additional distinction from sodium phosphate). The solution of sodium pyrophosphate remains unchanged upon boiling, but if heated after the addition of a little nitric acid, it is gradually converted into the tribasic phosphate, and then affords the reactions of the latter, as described on page 562. Examination : Sodium phosphate will be indicated, when heated in a small glass tube, by the fusion of the salt previous to the elimination of the water ; and also by the formation of a yellow precipitate with a neutral solution of argentic nitrate. Carbonate is detected in the solution of the salt, b}' effervescence upon the addition of a little hydrochloric acid. Sulphate and chloride may be detected in the diluted solution, after strongly acidulating with nitric acid, by white precipitates when tested in separate portions, with barium nitrate or chloride for the former, and with argentic nitrate for the latter. Metallic impurities are detected in the warm aqueous solution, acidulated with hydrochloric acid, by saturation with hydrogen sulphide, and, after filtration, if necessary, and subsequent neu- tralization with ammonia- water, by, a daris coloration or precipi- tate with ammonium sulphide. SODIUM. 665 SODII SALICTLAS. SODIUM SEII NATRIUM SAI.ICYLICUM. Balicylate of Sodium. Sodium Salicylate. Ger. Sallcylsaures Natrium ; Fr. Salicylate de soude ; Sp. Salicilato de sosa. 2NaC,HA+H,0 = aO.H /gJ_Q^^ + H,0; 338. Small, white, crystalline plates, with a pearly lustre, or a crys- talline powder, permanent in the air, and containing, for two molecules of the salt, one molecule (5.82 per cent.) of water of crystallization. When strongly heated, the salt becomes decom- posed, with the evolution of inflammable vapors, and leaves a residue of sodium carbonate, amounting to between 30 and 31 per cent, of its original weight; this residue possesses a strongly alkaline reaction, effervesces with acids, and imparts an intense yellow color to the non-luminous flame. Sodium salicylate is soluble in 1.5 parts of water and in 6 parts of alcohol at 15° 0. (59° F.), and very soluble in boiling water and boiling alcohol ; it is also freely soluble in glycerin, but very sparingly soluble in ether. The aqueous solution possesses a sweet- ish, saline, mildly alkaline taste, and a slight alkaline reaction, and affords a reddish-brown precipitate on the addition of a solu- tion of ferric chloride. When the aqueous solution of the salt is supersaturated with hydrochloric or sulphuric acid, a voluminous white precipitate of salicylic acid is produced, which is readily soluble in boiling water, crystallizing out upon cooling ; it is also freely soluble in ether, and assumes an intense violet color on the addition of a few drops of a solution of ferric chloride. Examination : The aqueous solution of sodium salicylate should be colorless and odorless, and its transparency should not be disturbed by the addition of an equal volume of alcohol. Carbonates may be recognized in the solution of the salt by effervescence on the addition of dilute hydrochloric acid. Ghhrides and suljjhates may be detected in a solution of 1 part of the salt in a mixture of 50 parts of alcohol and 25 parts of water, acidulated with nitric acid, and filtered, by testing it, in separate portions, with argentic nitrate for chlorides, and with barium chloride or nitrate for sulphates. Organic impurities will be indicated by a brown or blackish coloration, when 1 part of the salt is agitated with about 15 parts of cold concentrated sulphuric acid. 566 MANUAL OF CHEMICAL ANALYSIS. SODII SANTONINAS. SODIUM SEU NATRIUM SANTONINICUM. Sanioninate of Sodium. Sodium Santoninate. Ger. SaDtoninsaureB Natrium ; Fr. Santoninate de sonde ; Sp. Sant6nlnato de sosa. 2NaC„H,,0, + 7H,0; 698. Colorless, transparent, tabular crystals, belonging to the rhom- bic system, which by exposure to sunlight slowJy acquire a yel- lowish color; they contain, for 2 molecules of the salt, 7 molecules (18.05 per cent.) of water of crystallization, and effloresce slightly on the surface on exposure to dry air. When heated to 100° C. (212° F.), the salt loses its water of crystallization, and melts at 142° C. (287.6° F.), assuming thereby a iine red co]or, without, however, undergoing decomposition; at a higher temperature it chars, with the evolution of inflammable vapors, which burn with a very smoky flame, and finally leaves a strongly alkaline residue, which imparts an intense yellow color to the non-luminous flame. Sodium santoninate is soluble in 3 parts of water and in 12 parts of alcohol at 15° C. (59° F.), in 0.5 part of boiling water and in '6A parts of boiling alcohol. The aqueous solution possesses a mildly saline, slightly bitter taste, and a feebly alkaline reaction ; with diluted acids it yields a white, crystalline precipitate of santoninic acid, which, however, becomes rapidly converted into santonin, is readily dissolved by agitation with chloroform or ether, and yields, with an alcoholic solution of potassium hydrate, a scarlet-red liquid, which gradually becomes colorless. Examination : The cold aqueous solution of sodium santoninate should be colorless, should not effervesce on the addition of acids, and should afford no turbidity when mixed with an equal volume of alcohol. Alkaline earths may be detected in a solution of 1 part of the salt in 20 parts of water, by a white turbidity or precipitate on the addition of a solution of sodium carbonate. Sulphates and chlorides may be detected by dissolving a little of the salt in an equal weight of warm water, subsequently adding diluted nitric acid until a precipitate ceases to be produced, and, after filtration, testing the liquid, in separate portions, with barium chloride for sulphates, and with argentic nitrate for chlorides. • Alkaloids, which, by accident, have occasionally been found to occur in santonin, may be sought for in sodium santoninate by testing the acidulated aqueous solution of the salt with potassio- mercuric iodide, iodinized potassium iodide, picric or tannic acids ; no turbidity or precipitate should be produced by either of these reagents. SODIUM. 607 SODII SULPHAS. SODIUM SEU NATRIUM SULFURICUM. Sulphate of Sadhim. Glauber's Salt. Sodium Sulphate. Ger. Schwefelsaures Natrium, Glaubersalz ; Fr. Sulfate de soude ; Sp. Sulfate de sosa. Na,SO, + 10H,O; 322. Large, colorless, transparent, monoclinic prisms (Fig. 169), having the specific gravity of 1.481, and containing ten molecules (55.9 per cent.) of water of crystallization ; they effloresce rapidly on exposure to the air. Fig. 169. losing all the water of crystallization, and crumbling to a white powder. When heated to 33° C. (91.4° F.), the salt undergoes aque- ous fusion, and at a higher temperature loses its water of crystallization, leaving an an- hydrous residue, which melts at a red heat without decomposition. A fragment of the salt imparts an intense yellow color to the non-luininous flame. Sodium sulphate is verv soluble in water; 100 parts of water at 0° 0. (32'^ F.) dissolve "12.17 parts, at 18° C. (64.4= F.) 48.28 parts, at 25° C. (77° F.) 99.48 parts, and at 33° C. (91.4° F.) 322.12 parts, of the crystallized salt; above that temperature the salt passes into the anhydrous state, in which it is less soluble, and the solution then separates the anhydrous salt in the form of small rhombic octohedrons. The solution saturated at 33° C. (91.4° F.) affords no crystals upon cooling to the ordinary temperature, but remains supersaturated; if, however, a fragment of the crystal- lized salt be added to the solution, it immediately solidifies, accom- panied by a considerable rise of temperature. The supersaturated solution apparentljr contains a salt with 7 molecules of water of crystallization. Sodium sulphate is also soluble in glycerin, but is insoluble iu alcohol. The aqueous solution of the salt possesses a saline and feebly bitter taste, is neutral, remains unaltered with sodium car- bonate as well as with sodium bitartrate, and gives a granular white precipitate with lime-water, and a copious white one with solutions of both barium and lead salts, which latter precipitates are insoluble in diluted acids. If 1 gram of crystallized sodium sulphate be dissolved in a little water, the solution acidulated with hydrochloric acid, and completely precipitated by barium chloride, a precipitate of barium sulphate is produced, which, when collected upon a filter, washed, dried, and ignited, should weigh 0.723 gram. Examination : A solution of one part of the crystallized salt in four parts of 568 MANUAL OF CHEMtCAL ANALYSIS. water, tested with blue and with red litmus-paper, should not change the color of either. Chloride may be detected in the diluted solution, acidulated with nitric acid, by a white turbidity or precipitate with argentic nitrate. ■Carbonate may be detected in the solution of the salt by effer- vescence on the addition of an acid. Ammonium sulphate may be recognized by the odor as well as by the rise of white vapors, when a little of the triturated salt is heated in a strong solution of potassium hydrate, and a glass rod, moistened with acetic acid, is held in the orifice of the test-tube. Magnesium, and calcium salts are detected in the solution by a white precipitate with sodium carbonate ; a reddish or brownish appearance of the precipitate would indicate metallic impurities (iron and manganese); the presence of inanganese salts may be confirmed by a brown precipitate upon the addition of a solution of chlorinated lime to the solution of the sodium sulphate, that of iron by a blue turbidity, when the solution of the salt is acidulated with hydrochloric acid and tested with potassium ferrocyanide. Metals may further be detected in the diluted solution by add- ing a little ammonium- sulphide, and allowing the mixture to stand for a few hours ; a white turbidity would indi- FiG. 170. ^,2XQ zinc, and a brownish -black one, copper; a green- C^^~^ ish-black one would confirm the presence of iron, and ^*^ -*> a pale-reddish one, that o£ manganese. If a test for arsenic is required, about 2 grams of the crystallized sodium sulphate are dissolved in an equal weight of warm waxer in a wide test-tube ; an amount of concentrated hydrochloric acid equal to about ten times the weight of the salt is then added, and a strip or roll of bright copper-foil completely immersed in the fluid; the tube is then dipped into boiling water and allowed to stand in the water for half an hour. The copper must remain bright; a grayish-black coating I 1t| would indicate arsenic. The presence of arsenic may I 4 also readily be determined by adding to a solution of [ l' the salt, in a test-tube, a strong solution of potassium I ^ hydrate, subsequently a few fragments of pure metal- lic zinc, and placing over the mouth of the tube a cap of bibulous paper moistened with a drop of a solution of argentic nitrate (Fig. 170), and gently heating ; if arsenic be present, a dark metallic stain will be pro- duced on the paper. Sulphite and hyposulphite may be detected in a solu- ^__^ tion of one part of the salt in three parts of water, by mixing it, in a test-tube, with one-third of its volume of concentrated hydrochloric acid, and heating it gently with a few fragments of granular zinc ; the presence of either of the above salts SODIUM. 569 will give rise to the formation of hydrogen sulphide, which may be recognized by placing a small bunch of cotton, moistened with solu- tion of plumbic acetate, in the orifice of the tube, or by closing it with bibulous paper moistened with the plumbic solution (Fig. 170). A black coloration of the cotton or a dark stain upon the paper would indicate the presence of either or both of the above salts. SODII STJLPHIS. SODIUM SEU NATRIUM SULFUROSUM. Sulphite of Sodium, Sodium SulplUte. Ger. Schwefligaaures Natrium ; Fr. Sulfite de aoude ; Sp. Sulfite de sosa. ]Sra,S03+7H,0; 252. Colorless, transparent, monoclinic prisms, containing seven mole- cules (50 per cent.) of water of crystallization ; on exposure to the air, they effloresce somewhat, and the salt is gradually converted into sulphate, emitting a feeble odor of sulphur dioxide. This liability to decomposition is retarded, and the salt made more per- manent, by exsiccating it at a gentle heat, when it undergoes aque- ous fusion, loses its water of crystallization, and becomes white. It is this granular form in which sodium sulphite is now frequently met with. When this salt is exposed to a strong red heat, it fuses to a dirty yellowish mass, consisting of sodium sulphate and sul- phide ; these may be separated by extracting the cold re.sid,ue with strong alcohol, which dissolves the sulphide, but not the sulphate. Crystallized sodium sulphite is soluble in 4 parts of water at 15° C. (59° F.), and in 0.9 part of boiling water, but only spar- ingly in alcohol ; its aqueous solution has a feeble alkaline reac- tion, and becomes turbid upon heating, but transparent again on cooling ; on exposure of the solution to the air, the sulphite is gradually converted into sulphate with the separation of sulphur, as it is also by treatment with oxidizing agents, such as chlorine, hypochlorous acid, nitrous acid, etc. When acidulated, solution of sodium sulphite acts as a powerful reducing agent ; it emits sulphur dioxide upon the addition of strong acids, slowly when cold, freely on warming, and, in the latter instance, with the sepa- ration of sulphur; when this test is performed with hydrochloric or sulphuric acid, and with the addition of a little zinc, hydrogen sulphide is evolved. With barium chloride or nitrate, solution of sodium sulphite forms white precipitates, soluble in diluted hydrochloric acid. Examination : Sodium sulphate may be detected in a solution of 1 part of the salt in 100 parts of water, strongly acidulated with hydrochloric 570 MANUAL OF CHEMICAL ANALYSIS. acid, by a white precipitate on the addition of a few drops of solu- tion of barium chloride. Estimation : About 0.5 gram of the salt is dissolved in a small portion of water, a little mucilage of starch added, and subsequently a deci- normal solution of iodine (page 93) allowed to flow into the liquid from a burette until, with constant stirring, a permanent blue coloration of the liquid is just produced. The number of cubic centimeters of iodine solution, which are required to produce this reaction, when multiplied by the decimal 0.0126, will represent the amount of pure, crystallized sodium sulphite in the specimen under examination, and therefrom its percentage purity may readily be calculated. The United States Pharmacopoeia directs that if 0.63 gram of the salt be dissolved in 25 cubic centimeters of water, and a little gelatinized starch added, at least 45 cubic centimeters of the volu- metric solution of iodine should be required, before a permanent blue tint appears after stirring (corresponding to at least 90 per cent, of pure sodium sulphite).' SODII SULPHOCARBOLAS. SODIUM SEU NATRIUM SULFOCARBOLICUM SEU SULFOPHBNOLICUM. Sulpliocarbolate of Sodium. Sodium Sulphocariolate or Sulphophenolaie. Ger. Plienolsulfosaures Natrium ; Fr. Sulfocarbolate de soude ; Sp. 8ulf(icarb61ato de sosa. NaC,H,S0,-f-2H,0 = 0„H,<(gH q^^_^2H,0 ; 232. Colorless, transparent, rhombic prisms, containing two mole- cules (15.51 per cent.) of water of crvstallization, and permanent in the air. When heated to 100° G."(212° F.), the salt loses its water of crystallization, and becomes converted into a white pow- der ; at a higher temperature it is decomposed, with the evolution of inflammable vapors, having the odor of phenol (carbolic acid), and leaving a white residue, amounting to 36 per cent, of the original weight ; if this residue be dissolved in water, the solution filtered, acidulated with hydrochloric acid, and tested with a few drops of solution of barium chloride, a white precipitate of barium sulphate will be produced, insoluble in nitric or hydrochloric acid. A fragment of the salt, when heated in the non-luminous flame, imparts to the ktter an intense yellow color. Sodium sulphocarbolate is soluble in 5 parts of water and in 132 parts of alcohol at 15° 0. (59° F.), in 0.7 part of boiling water SPIRITUS. 571 and in 10 parts of boiling alcohol. The aqueous solution pos- sesses a cooling, saline, slightly bitter taste, and is neutral in its action upon litmus; it yields, even when highly diluted, a deep violet color on the addition of a few drops of a solution of ferric chloride. Examination : Sulphate may be detected in a solution of 1 part of the salt in 100 parts of water by an immediate white turbidity or precipitate on the addition of a solution of barium chloride. Barium and calcium salts may be detected in the aqueous solu- tion, when tested in separate portions, with magnesium sulphate for the former, and with ammonium oxalate for the latter. Metallic impurities will be indicated in the solution of the salt, either before or after acidulation with hydrochloric acid, by a turbidity or precipitate when saturated with hydrogen sulphide ; the occurrence of a white precipitate with the latter reagent in the neutral solution of the salt would indicate the presence of zinc. SPIRITUS .aiTHBRIS NITROSI. SPIRITUS NITROSO-^THEREUS. SPIRITUS NITRI DULCIS. Spirit of Kitrous Ether. Bweet Spirit of Nitre. Alcoholic Solution of Ethyl Nitrite. Ger. Versiisster Salpetergeist ; Fr. Etlier azoteux alcoolis6 ; Sp. Espiritu de nitro dulce. A colorless or pale-yellow, volatile liquid, of a fragrant, ethe- real odor, and sharp, aromatic, sweetish taste ; its spec. grav. is 0.823 to 0.825 U.S. Pharm. (0.845 Brit. Pharm., and 0.840-0.850 Pharra. Germ.), and it should contain between 4 and 5 percent, of ethyl nitrite. It is inflammable, reddens blue litmus-paper not at all or only faintly, and assumes a dark color upon the addition of a few drops of' a solution of ferrous chloride or sulphate. When added to a dilute solution of potassium iodide, to which a few drops of djlute sulphuric acid and a little mucilage of starch have previously been added, a blue coloration will be produced. Spirit of nitrous ether is miscible with water, alcohol, chloro- form, ether, carbon bisulphide, benzol, and essential and fatty oils. A portion of the spirit, in a test-tube half filled with it, plunged into water heated to 63° 0. (145.4° F.), and held there until it has acquired that temperature, will boil distinctly on the addition of a few small pieces of glass. Examination : Aldehyde is indicated by a brow^n coloration of the spirit when agitated in a test-tube with a few fragments of fused potassium hydrate. 572 MANUAL OF CHEMICAL ANALYSIS. Acids. — Spirit of nitrous ether containing so much of free acid as to have a perceptible sour taste and an acid reaction upon blue litmus-paper, and to cause the rise of gas-bubbles from a few crystals of potassium bicarbonate when dropped into it, cannot be considered admissible for medicinal use. -Ethyl chloride may be detected by burning away a small quan- tity of the spirit upon a little water in a porcelain capsule, and by subsequently testing the water, after acidulation with a few drops of nitric acid, with a few drops of solution of argentic ni- trate ; the occurrence of a white turbidity would indicate the presence of ethyl chloride. Methylic Alcohol. — About 30 cubic centimeters of the spirit are shaken with 2 to 3 grams of anhydrous (exsiccated) potassium carbonate ; after subsiding, the supernatant spirit is decanted ; about 15 cubic centimeters of this dehydrated spirit is introduced into a small flask, or a test-tube of a proper size (Fig. 171), 10 Fig. 171. grams of anhydrous calcium chloride in powder are added, and, after thoroughly mixing, the flask is connected with a bent glass tube or a condenser, and is then placed in a water-bath for distillation ; this distillation is continued until about 5 cubic centimeters of distillate have been obtained. The test-tube is then removed from the water- bath, and, when cool, 5 cubic centimeters of water are added, and the distillation once more resumed until a little more than 2 cubic centimeters of distillate are obtained. The latter distillate is mixed v/ith 15 cubic centimeters of water, wherein 2 grams of potassium bichromate and 80 drops of concentrated sulphur. c acid have been dissolved. After having allowed the mixture to stand for a quarter of an hour, it also is submitted to distillation, until 15 cubic cen- timeters of distillate are obtained; to this 2 grams of crystallized sodium carbonate are added, in a porcelain capsule, and tlie whole BPIRITUS. 573 evaporated to lialf its volume; it is then slight!}'- supersaturated with acetic acid, filtered into a test-tube, and about 30 drops ot solution of argentic nitrate added, and the whole gently boiled for about two minutes. If the spirit is free from methylic alcohol, the solution darkens, and often assumes transiently a purplish tinge, but continues quite transparent, and the test-tube, after being rinsed out and fi.lled with water, appears clean. But, if the spirit contains even traces of metlndic alcohol, the liquid becomes at first brown, then almost black and opaque, and a film of silver is deposited on the tube, which appears brown by trans- mitted light. When only 3 to 4 per cent, of methylic alcohol is present, the film is sufficiently thick to form a brilliant metallic mirror. Estimation of the Quantity of Ethyl Nitrite : Ten grams of the spirit of nitrous ether are digested in a strong glass-stoppered vial for about half an hour, on the water-bath, with about three times its volume of an alcoholic solution of pure potassium hydrate. The ethereal odor will then have disappeared, and the contents of the vial are transferred to a beaker, a little water added, and gently heated on the water-bath until the alco- hol has evaporated. The remaining solution is then diluted to the measure of about 200 cubic centimeters, acidulated with dilute sulphuric acid, and a decinormal solution of potas.sium per- manganate (page 89) allowed to flow into the liquid from a burette until, with constant stirring, the red color imparted to the liquid ceases to be discharged within a few minutes. The exact strength of the potassium permanganate solution having been previously determined by means of metallic iron, as described on page 89, the amount of potassium permanganate, expressed in grams, contained in the volume of the solution em- ployed, may readily be calculated ; this number, when multiplied by 1.18, will represent the amount of pure ethyl nitrite in 10 grams of the spirit, and requires simply to be multiplied by 10 in order to express the percentage. The reactions involved in the above operation may be repre- sented by the following equations : (a) 5C,H.-NO,-|-5KOH = oO,H,-OH + 5KNO, 375 (3) 5KNO,+3H,SO,+K,Mnp=5KN03+K,SO,+2MnSO,+3H,0. 316 Therefore |^|-=1.18, and accordingly a:K,Mn20,Xl.l8=a;C,K,-]SrO, The United States Pharmacopoeia directs that if 10 grams of spirit of nitrous ether be macerated with 1.5 grams of potassiijm hydrate for twelve hours, with occasional agitation, the mixture then diluted in a beaker with an equal volume of water, and set 574 MANUAL OF CHEMICAL ANALYSIS. aside until the odor of alcohol has disappeared, then slightly acidu- lated with diluted sulphuric acid, and a solution of 0.335 gram of potassium permanganate gradually added, the color of the whole of this solution should be discharged (corresponding to the pres- ence of at least 4 per cent, of pure ethyl nitrite). STRYCHNINA. STRYCHNmUM. STRTCHNIUM. Strychnine. Strychnia. Ger. Strychnin ; Fr. Strychnine ; Sp. Estricnina. 0„H..NA; 334. Small, brilliant, octahedral crystals, or four-sided prisms of the rhombic system, colorless and transparent, or a white, crystalline powder, permanent in the air. When the crystals are very care- fully heated, in small amount, they melt without decomposition, and may also to a slight extent be sublimed ; when heated upon platinum-foil, they spread over the foil like melted resin and become decomposed, leaving a charred residue, which, at a stronger heat, is wholly dissipated (evidence of the absence of fixed ad- mixtures). Strychnine is soluble in 6700 parts of water and in 110 parts of alcohol at 15° C. (59° F.); in 2500 parts of boiling water and in 12 parts of boiling alcohol. It is also soluble in 6 parts of chloro- ibrm, 170 parts of benzol, 185 parts of amy lie alcohol, 300 parts of glycerin, and 485 parts of carbon bisulphide, but is almost insoluble in ether, absolute alco- hol, and petroleum benzin; dilute acids dissolve it freely and without color. The saturated alcoholic or aqueous solution possesses an alkaline reaction and an intensely bitter taste, which is still per- ceptible when diluted to such an extent that 700,000 parts of the solution con- tain but 1 part of the alkaloid. When a few drops of cold concen trated nitric acid are added, by means of a glass rod or a small pipette"(Fig. 172), to a little strychnine, or its salts, on a watch-glass or porcelain plate, it dis- solves without any color, or with only a pale-greenish or yellow tint (distinction irom brucine and morphine, and their Fig. 172. STRYOHNINA. 575 salts, which give intensely red solutions). Strong sulphuric acid also dissolves strychnine and its salts without color (distinction from brucine, veratrine, and sali'cin, which yield red or purple colorations); but, when a minute fragment of a crystal or one drop of a solution of potassium bichromate or permanganate is added, the solution assumes at once a deep- violet or blue color, which successively changes from violet to red, and finally to green or yellow.* When a cold, saturated alcoholic solution of strychnine is mixed with about an equal volume of an alcoholic solution of ammonium sulphide, and the mixture is allowed to stand for twelve hours, long, brilhant, orange- red needles are formed, having the composition (C5,,H25N20,)2S„H2, which are insoluble in water, alcohol, ether, and carbon bisulphide, and are decolorized and decomposed when treated.with concentrated sulphuric acid, with the formation of strychnine sulphate, and of an oily compound of a penetrating odor, which, in contact with water, is resolved into sulphur and hydrogen sulpjiide. Strychnine only is known to produce this reaction. When a little strychnine is agitated with a small amount of warm water, insufficient to dissolve it, it will dissolve readily upon the subsequent addition of a few drops of diluted sulpliuric acid; this solution, when tested in separate portions, will yield precipi- tates with tannic acid, with potassio-mercuric iodide, and with iodinized potassium iodide; it will remain unaltered with potas-. sium bicarbonate (distinction from the cinchona alkaloids), but it will yield a white j^recipitate with the alkaline hydrates, insoluble in an excess of the precipitant (further distinction from mor- phine), and also but sparingly soluble when agitated with ether, but readily soluble in chloroform. Examination : Incidental or fraudulent admixtures of other alkaloids are recog- nized by the above-described characteristics and reactions of strychnine. Brucine and salicin are indicated by a red coloration with either concentrated nitric or sulphuric acid. Brucine may also be recognized by its ready solubility in abso- lute alcohol (wherein strychnine is almost insoluble), and by ,the reaction of its solution in nitric acid with stannous chloride or ammonium sulphide (page 283). While pure strychnine affords a pale-green or yellowish solution with strong nitric acid, this will appear more or less red, if brucine be present, and will assume, after the addition of a little water and evaporation of the excess of acid, a deep violet color upon the subsequent addition of solu- * Only aniline iind its snlts are Isnown to afford, willi tlie same reagent, a similar reaction, whicli, however, is less of a violet and more of a blue tliil thronghoul, and wliicli does not nppear immedialely. 576 MANUAL OF CHEMICAL ANALYSIS. tion of stannous chloride, or ammonium sulphide ; if the latter reagent has been employed, a white turbidity from the separation of sulphur may occur. Santonin is recognized by its insolubility in dilute acids, and by its property of assuming a lemon-yellow color when the sam- ple, covered with a sheet of thin white paper, is exposed to solar light for one or two days. Cinchona alkaloids may be detected by a white precipitate, when a solution of the strychnine in dilute sulphuric acid is tested with solution of potassium bicarbonate. Ginchonine may also be recognized by its insolubility in chloro- form, remaining behind when a little powdered strychnine is exhausted with that solvent ; its identity may then be ascertained by its properties, described on page 316. For the separation of strychnine from other alkaloids with which it may be associated, or from complex organic mixtures, advan- tage may be taken of the sparing solubility of the crystalline chromate or picrate, as precipitated by a solution of potassium bichromate or picric acid, or the method described on page 108 may be employed. The chromate is specially adapted for obtain- ing its most characteristic reaction, which is produced by simple contact of the latter salt with a few drops of concentrated sulphu- ric acid. The picrate, although a yellow salt, forms a colorless solution with concentrated sulphuric acid, and is likewise admira- bly adapted for obtaining the reaction with potassium bichromate. STRYCHNINiB NITRAS. STRYCHNINUM SEU STRYCHNIUM NITRIOUM. Nitrate of Strychnine or Strychnia. Strychnine Nitrate. Ger. Salpetersaures Strychnin; Fr. Azotate de strychnine ; Sp. Nitrato de estricnina. C,,H,,NA-HN03; 397. Colorless, transparent, flexible needles, of a silky lustre, perma- nent in the air. When gently heated on platinum-foil they assume at first a yellowish color, and, at a higher temperature, deflagrate slightly, leaving a carbonaceous residue, which, at a red heat, is wholly dissipated (evidence of the absence of fixed admixtures). Strychnine nitrate is soluble in 90 parts of water and in 70 parts of alcohol at 15° C. (59° F.), in 3 parts of boiling water and 5 parts of boiling alcohol, but insoluble in ether and carbon bisul- phide. Its, solutions are neutral, and have an intensely bitter taste. They yield, on the addition of solution of potassium hydrate, a white STRYCHNINA. 577 precipitate of strychnine, which is insoluble in an excess of the precipitant. Strychnine nitrate answers to all the reactions of strychnine, and may be recognized by the characteristic coloration with strong sulphuric acid and potassium bichromate or permanganate, as described on page 576. In distinction from strychnine, it is fur- tliermore specially characterized by heating a crystal of the salt, or a little of the solution with concentrated hydrochloric acid, to boil- ing, when a bright red color is produced. The evidence of being a nitrate is not readily obtained by the direct application of the ordinary tests, and in performing this reaction the strychnine should first be precipitated from the solution of the salt by the addition of a slight excess of potassium or sodium hydrate; the filtrate may then be tested by supersaturating it with hydrochloric acid, adding a drop of solution of indigo, and heating to boiling, when decoloration of the liquid will ensue ; or, to the filtrate, con- centrated sulphuric acid, in slight excess, may be added, and sub- sequently a saturated solution of ferrous sulphate allowed to flow upon the surface of the liquid by means of a pipette, so as to form two layers (Fig. 173) ; a dark-brown coloration will take place at the junction of the two liquids. Fig. 173. The methods for testing the purity of strychnine nitrate are the same as described with strychnine on pages 575, 576. It needs only to be added that the salt should not emit a,mmoniacal odors, when heated with a strong solution of potassium hydrate, nor, upon heating with the latter, should it cause the ri.se of white vapors, when a glass rod, moistened with acetic acid, is held over the orifice of the test-tube. 578 MANUAL OF CHEMICAL ANALYSIS. STRYCHNINE SULPHAS. STRYCHNINUM SEU STRYCHNIDM SULFURICUM. Sulphate of Strychnine or Strychnia. Strychnine Sulphate. Ger. Schwefelsaures Strychnin ; Fr. Sulfate de strychnine ; Sp. Sulfate de estricnina. (C,,H,,NA)..H,S0,+6H,0; 874. Fine, colorless, and transparent prismatic crystals, containing six molecules (12.24 per cent.) of water of crystallization, and slightly efflorescent on exposure to dry air. When heated lo about 185° C. (365° F.) they lose the water of crystallization, without previously fusing; at a higher temperature they become charred and decomposed, and, at a red heat, they burn away with- out residue (evidence of the absence of fixed admixtures). Strychnine sulphate is soluble in 42 parts of water and in 60 parts of alcohol at 15° C. (59° F.), in 2 parts of boiling water and in 2 parts of boiling alcohol. It is also soluble in 26 parts of glycerin, but is insoluble in ether. Its solutions are intensely bitter; their deportment with reagents answers to that of strych- nine, and they also afford the characteristic reaction with sul- phuric acid and potassium bichromate or permanganate; the evidence of being a sulphate may be obtained by the white prei- cipitate, insoluble in hydrochloric acid, which barium nitrate yields with a solution of strychnine sulphate in dilute nitric acid. The solution of the salt yields on the addition of solution of potas- sium hydrate a white precipitate of strychnine, which is insoluble in an excess of the precipitant. When heated with solution of potassium hydrate, the salt should not emit ammoniacal odors, nor should it cause the rise of white vapors when a glass rod, moistened with acetic acid, is held over the orifice of the test- tube. The purity of the salt may be ascertained by the same tests as described with pure strj^chnine, on pages 575, 576. SULPHUR PRffiCIPITATUM. LAC SULFUBIS. Precipitated Sulphur. Lac SulpJmr. Ger, Gefallter Schwefel, Schwefelmilch ; Fr. Soufre pr^cipit^; Sp. Azufre precipitado. S; 32. A fine, slightly coherent powder, of a pale yellowish or grayish color, without taste or smell, and free from grittiness, consisting, when seen under the microscope, of minute, opaque globules, without any admixture of crystalline matter. When thrown SUIiPHITR. 579 upon bnrning coal, or heated in an open vessel, precipitated sul- phur first emits a little hydrogen sulphide, then fuses, and burns wholly away at a stronger heat. Precipitated sulphur is insoluble in the common solvents, but is readily and wholly soluble in carbon bisulphide, and in strong, boiling solutions of potassium and sodium hydrates, and also more or less in benzol, in hot oil of turpentine, and other essential and fatty oils. Examination : Fixed admixtures are indicated by a white ash or a non-volatile residue when a small portion of the sulphur is strongly heated in an open porcelain crucible. Calcium Sulphate. — A small portion of the sulphur is triturated with about ten times its weight of tepid water, and the mixture agitated for a few minutes until cold, when it is filtered ; the fil- trate must not act upon test-paper, as an acid reaction would indicate long exposure to the air ; nor must it leave any residue upon evaporation upon a watch-glass, which would indicate either insufficient washing, or an admixture of a soluble fixed compound ; a white precipitate of the filtrate, when tested with ammonium oxalate in one portion, and with a few drops of nitric acid and barium nitrate in another portion, would indicate calcium sul- phate. Earthy Carbonates or Phosphates.— When the sulphur leaves a residue on incineration, or on solution in carbon bisulphide, a small portion of it is digested for several hours, with occasional agitation, with about ten times its weight of a mixture consisting of equal parts of concentrated hydrochloric acid and water; effer- vescence upon the addition of the acid would indicate the presence of carbonates. The mixture is then filtered, and one portion of the filtrate supersaturated with sodium carbonate; an ensuing white precipitate would indicate the presence of the above ad- mixtures; the other portion is heated with a few drops of solution of ammonium molybdate; a yellow coloration of the liquid, and, after a while, a yellow crystalline deposit, would indicate phos- phates (if the sulphur be free from arsenic). Any admixture, except poivdered resin or pitch, which are recog- nized'by a sooty flame when ignited, and by their solubility in strong alcohol or ether, may be quantitatively determined by re- maining undissolved upon digesting a known quantity of the sulphur with carbon bisulphide, or, when calcium sulphate is the only admixture, by complete incineration of a weighed quantity of the sulphur in a tared porcelain crucible ; the weight of the remaining anhydrous calcium sulphate, with one-fourth thereof added to compensate for the loss of the water of crystallization, gives the amount of crystalline calcium sulphate present in the quantity of sulphur under examination. Arsenic may be detected by triturating a portion of the sulphur 580 MANUAL OF CHEMICAL ANALYSIS. with about ten times its weight of ammonia-water or a saturated solution of ammonium carbonate, and subsequently digesting the mixture in a corked test-tube, for about one hour, with occasional agitation ; the liquid is then filtered, and a portion of the filtrate supersaturated with hydrochloric acid ; the formation of a yellow precipitate, either at once or upon subsequent saturation of the liquid with hydrogen sulphide, would indicate arsenic; the rest of the filtrate is evaporated to dryness in a small porcelain cap- sule ; if a residue remains, it is detached by triturating it with a little powdered magnesite, or pumice-stone, a little potassium cyanide is then added, and the mixture, after being introduced into a reduction-tube (Fig. 174), is first gently heated in order Fig. 174. to expel moisture, which may be removed by means of a strip of bibulous paper, and the contents of the tube subsequently strongly heated; whereupon, the formation of a metallic mirror and the evolution of a garlic-like odor would further indicate arsenic. An admixture of starch may be recognized by examination of the precipitated sulphur under the microscope, or by boiling a small portion of it with about ten times its weight of water, and testing the cooled liquid with one drop of solution of iodinized potassium iodide. The occurrence of a blue coloration would show such an adulteration. SULPHUR. 581 SXJIiPHITR SUBLIMATUM. FLORES SULFITRIS. Sublimed Sulphur. Flowers of Sulphur. Ger. Sublimirter Schwefel, SohwefelbUimeii ; Fr. Soufre sublimfi ;- Sp. Azufre sublimado. S; 32. A gritty, yellow, tasteless, and odorless powder, consisting, when seen under the microscope, of a mixture of minute, smooth globules, and of rhombic-octahedral crystals. When hea,ted in a dry tube, sulphur fuses at 115° C. (239° F.), farming an amber- colored fluid, which, when heated to from 220 to 250° C. (428 to 482° P.), becomes more and more thick and tenacious, and as- sumes a deep brownish-red color ; at a temperature approaching the boiling-point, 448° C. (818° F.), it becomes thin and liquid again, and volatilizes in colorless vapors, which condense on cool- ing; when heated with free access of air, sulphur takes fire at about 270° 0. (518° F.), and slowly burns away with a pale-blue flame, forming sulphurous-acid gas. Sublimed sulphur is insoluble in water, and almost insoluble in alcohol and in ether; it dissolves to some extent in chloro- form, and for the most part in carbon bisulphide,* in benzol, and in warm or boiling essential and fatty oils; it is wholly soluble in a hot concentrated solution of potassium or sodium hydrate. Commercial sublimed sulphur has generally an acid reaction upon moist test-paper, and contains traces of oxygen acids of sul- phur, occasionally also of selenium, and frequently of sulphides of arsenic, all which impurities have to be eliminated from such sulphur as is intended for medicinal use (Sulphur lotum, Sul- phur depuratum) ; this is effected by digesting the crude sub- limed sulphur for a few days with very dilute ammonia- water, or with a solution of ammonium carbonate, and by subsequent tho- rough washing with water, and drying. Examination : Washed sulphur should not redden moist blue litmus-paper, nor aflect the color of water which has been slightly blued with litmus-tincture, when agitated with a little of the sulphur. Warm * Both the amorphoun (spec. grav. 1.95) and tlie monocUnio (spec. grav. 1.96, fusing-point 120° C, 248° F. ) modifications of sulphur are almost insolu- ble in carbon bisulphide, while the rhombic form (spec. grav. 2.05, fusing- point 1150 C, 3390 F.) is readily soluble therein. Both the former varieties pass into the rhombic form, slowly at ordinary temperatures, and more rapidly at higher ones. Therefore, the older sublimed sulphur is, tlie more soluble it is in carbon bisulphide. There are, however, minor varieties of both the amorphous and the crystal- line modifications of sulphur, which appear to differ in tlieir deportment with solvents, and thereby also to alter the solubility of sublimed sulphur in carbon bisulphide. 582 MANUAL OF CHEMICAL ANALYSIS. water, when rubbed with the sulphur in a mortar, should yield a filtrate which leaves no residue upon evaporation on platinum-foil or on a watch-glass. Mineral and fixed admixtures are recognized by a non-volatile residue, either upon connplete dissipation of the sulphur in a por- celain crucible, or upon dissolving a small portion of the sulphur in a strong boiling solution of potassium or sodium hydrate. Arsenic may be detected by digesting the sublimed sulphur for several hours, with about four times its weight of a concentrated solution of ammonium carbonate. This dissolves only the arsenic sulphides or arsenious acid ; the former may be recognized by a yellow precipitate, either at once or after a while, when a portion of the filtrate is supersaturated with hydrochloric acid, and by a yellow res. due upon evaporation of the filtrate on a water-bath, as also by the formation of a metallic mirror when this residue is heated in a dry reduction-tube with potassium cyanide (Fig. 174, page 58.0); the arsenic present in the form of arsenious acid may be detected in a portion of the above obtained acid filtrate by the formation of a yellow precipitate upon saturation with hydrogen sulphide. Selenium may be detected by heating to boiling a mixture con- sisting of about two parts of the sulphur, and a solution of one part of potassium cyanide in twenty parts of water ; when cool, this mixture is filtered, and the filtrate supersaturated with con- centrated hydrochloric acid — taking care not to inhale the vapors of the evolved hydrocyanic acid; the solution is allowed to stand in a corked vial for about twenty-four hours. A reddish tur- bidity or deposit would indicate selenium. If the sulphur con- tains arsenic sulphides, they will give rise to the simultaneous formation of a yellow precipitate, which, however, will appear more or less reddish in hue when selenium is contained in the sulphur. Another method consists in digesting the sulphur with a neu- tral, saturated solution of potassium sulphite ; the liquid is then filtered, and subsequently supersaturated with hydrochloric acid, when, if selenium be present, a flocculent precipitate of a reddish color will be produced. The precipitate, after drying, may be fur- ther tested for its identity, if required, by the development of the charactei'istic and exceedingly unpleasant odor upon heating. THYMOL. 583 SULPHURIS lODIDUM. SULFUR lODIDUM. SULFUR lODATUM. Iodide of Sulphur. Sulphur Iodide. Ger. Jodschwefel ; Fr. loduie de soufre ; Sp. loduro de azufre. A grayish-black solid, usually occurring in pieces of a radiated crystalline appearance externally, and having the characteristic odor of iodine, a slightly acid taste, and a faintly acid reaction. Sulphur iodide is an unstable compound, and is readily decom- posed ; on exposure to the air it gradually loses iodine; it is also decomposed by boiling water with the volatilization of the iodine, and, when heated in the air, the iodine passes off in vapor, and is wholly expelled, leaving a residue of sulphur, which burns away at a strong heat with a pale blue flame. Sulphur iodide is insoluble in water, but this takes up a trace of iodine ; it is soluble in carbon bisulphide and also in about 60 parts of glycerin ; alcohol and ether, as well as strong solutions of potassium iodide, or of potassium hydrate, deprive it completely of the iodine, leaving the sulphur behind ; in this way, sulphur iodide may be examined, by exhausting 50 parts of it with alco- hol, when only 10 parts of sulphur should remain behind; and, when this is divided into two portions, one of them should burn away at a strong heat, with the odor of sulphurous acid, and the other must be completely soluble in carbon bisulphide. THYMOL. THYMOLUM. Thymol. Methyl-propyl-phenol. Ger. Thymol ; Fr. Thymol ; Sp. Timol. prr C,„H.,0 = CeH3/c3H;; 150. Large, transparent, colorless crystals, belonging to the hexago- nal system, having an aromatic thyme-like odor, a pungent, aromatic taste, and neutral in their action upon litmus. In the crystalline condition thymol has the specific gravity of 1.028, but, when liquefied, it is lighter than water and swims upon the sur- face; it melts at from 50 to 52° 0. (122 to 125.6° F.), remaining liquid at lower temperatures, and boils at from 228 to 230° C. (442.4 to 446° F.); at the temperature of the water-bath, or when heated on platinum-foil, it is rapidly volatilized, leaving no residue. 58J: MANUAL OF CHEMICAL ANALYSIS. Thymol is soluble in about 1200 parts of "water at 15° C. (59° F.), and in 900 parts of boiling water; in 1.5 parts of alcohol, in 120 parts of glycerin, and very freely soluble in ether, chloro- form, carbon bisulphide, benzol, benzin, glacial acetic acid, the fixed and volatile oils, and solutions of potassium and sodium hydrate, especially upon warming; it forms a colorless, syrupy liquid when triturated with an equal weight of camphor. The aqueous and alcoholic solutions are neutral in their action upon litmus, and afford no coloration on the addition of a few drops of solution of ferric chloride (distinction from and absence of car- bolic acid). If thymol be dissolved in about half its weight of glacial acetic acid, an equal volume of sulphuric acid subsequently added, and the mixture gently warmed, a beautiful reddish-violet color is produced, which is very permanent, and is not destroyed by an excess of acid or by boiling. When fused thymol is gradually mixed with an equal volume of concentrated sulphuric acid, and the mixture maintained at a temperature of 60° C. (140° F.) for about one hour, it solidi- iies on cooling to a crystalline mass of thymol-sulphonic acid, r SO,H prr . If this be dissolved in water, and the solution sub- LCaHr sequently poured into ten times its volume of water, and digested with an excess of lead or barium carbonate, and filtered, the fil- trate will assume, on the addition of a trace of ferric chloride, a beautiful violet-blue color. CA^ VERATRINA. VERATRINUM. VERATRIUM. Veratrine. Veratria. Ger. Veratrin ; Fr. Veratrine ; Sp. Veratrina. A white or grayish-white, coherent powder, or, more rarely, minute, efflorescent, prismatic crystals, without smell, but exciting violent sneezing when admitted into the nostrils. Heated upon platinum-foil, veratrine fuses into a yellow liquid, which, on cool- ing, solidifies to a transparent yellow mass; at a stronger heat, it is charred, and burns wholly away. Yeratrine is soluble in 3 parts of alcohol at 15° C. (59° F.), and more freely in boiling alcohol ; also soluble in 6 parts of ether, 2 parts of chloroform, 96 parts of glycerin, and 56 parts of olive oil; it is almost insoluble in cold, and very sparingly soluble in boiling, water, requiring of the latter 1560 parts for solution, but VERATRINA. 585 imparts to it an acrid taste and a feebly alkaline reaction ; dilute acids dissolve it freely with the formation of mostly uncrystal- lizable, gum-like salts. The solution in diluted acids has a per- sistent acrid, though not bitter, taste, causing a sensation of tin- gling, with numbness of the tongue. It gives a white precipitate with tannic acid and with potassio-mercuric iodide, a brown one with iodinized solution of potassium iodide, and a white one with the alkaline hydrates, soluble in a large excess of the precipitant, and more readily in alcohol, ether, and chloroform. Concentrated sulphuric acid dissolves veratrine with a yellow color, which successively becomes orange, purple, and deep red or violet ; gentle heat accelerates this reaction, and, if to the freshly prepared acid solution a few drops of bromine- water be added, the liquid assumes at once a purple-red color. On triturating vera- trine with sulphuric acid in a glass mortar, the yellow or yellow- ish-red solution exhibits, in reflected light, a fine greenish-yellow fluorescence, which becomes more intense on adding more sul- phuric acid. If a little cane-sugar be strewn upon the surface of the solution of veratrine in concentrated sulphuric acid, or if the alkaloid, previously triturated with about five times its weight of cane-sugar, be brought into concentrated sulphuric acid, the mix- ture assumes successively a yellowish, then a green, and finally a beautiful blue color, afterwards slowly changing to red and gray. Concentrated hydrochloric acid dissolves veratrine in the cold without coloration, but, upon gently heating, the solution assumes a permanent dark red color. Concentrated nitric acid does not effect any coloration with veratrine ; nor does concentrated sul- phuric acid, when diluted with one-third its bulk of water, produce any coloration, unless heated. When heated with caustic alkalies, veratrine is resolved into a new base, verine, C^H^jNO,, and dimethyl-protocatechuic or veralric f /OCH3 -. V. \COOH-/ Examination : Mineral or other insoluble admixtures may readily be detected by their insolubility in chloroform and in alcohol, or by leaving a non-volatile residue when heated upon platinum-foil. Foreign alkaloids may in many instances be detected by their greater solubility in hot water, and may subsequently be recog- nized in the solution by means of the appropriate reagents. Brucine remains undissolved when digested with ether ;* it may also be confirmed or recognized by dissolving a little of the ve- ratrine in concentrated nitric acid, diluted with an equal part of water; veratrine yields a colorless solution, which, however, will * The solubility of commercial veratrine in etlier varies, some kinds being less readily soluble, and tlie crystalline more so tlian the amorphous. 586 MANUAL OF CHEMICAL ANALYSTS. appear red -when bracine is present; the red solution changes to yellow upon heating, and, by the subsequent addition of a few- drops of a solution of stannous chloride or ammonium sulphide, a violet color will be produced. None of these color reactions will take place with pure veratrine. For the separation of veratrine from other alkaloids, or from complex organic mixtures with which it may be associated, see page 108. ZINCI ACETAS. ZINCUM ACETICUM. Acetate of Zinc. Zinc Acetate. Ger. Essigsaurcs ZinUoxyd ; Fr. Acetate de zinc ; Sp. Acetato de zinc. Zn(C,HA),+ 3H,0; 236.9. Colorless, translucent, six-sided tablets or scales, belonging to the monoclinic system, of a pearly, unctuous lustre, flexible, and with a faint odor of acetic acid, which is freely evolved when the crystals are treated with sulphuric acid; they contain three molecules (22.88 per cent.) of water of crystallization, and are ordinarily permanent in the air, but efflorescent in air that is dry and warm. When heated upon charcoal, before the blow-pipe, zinc acetate undergoes aqueous fusion, solidifies again, after the evaporation of the water of crystallization, and emits vapors of acetic acid, and the products of decomposition of the latter ; finally zinc oxide is left behind, which is yellow while hot, and white when cold. When this residue is moistened with one drop of solution of cobaltous nitrate, and heated to redness, it will appear green, after cooling. Zinc acetate is soluble in 3 parts of water and in 30 parts of alcohol at 15° C. (59° F.); in 1.5 parts of boiling water and in 3 parts of boiling alcohol. The aqueous solution has an astrin- gent, metallic taste, and a slightly acid reaction ; it gives a white precipitate of zinc sulphide with hydrogen sulphide or ammo- nium sulphide, and a white precipitate of zinc ferrocyanide with potassium ferrocyanide; it also forms white precipitates with the alkaline hydrates and carbonates, of which those with the hy- drates, and with ammonium carbonate, are redissolved by an excess of the precipitant, but these solutions are precipitated again, by boiling, if not too concentrated. Solution of zinc acetate acquires a red color, upon the addition of a few drops of a dilute solution of a ferric salt. Exairiination : If a solution of one part of the salt in ten parts of water be ziNOUM. 587 completely precipitated by hydrogen siilpliide, and filtered, the filtrate should leave no residue upon evaporation. Metallic impurities will be indicated by a dark coloration or a precipitate, when a solution of the salt, acidulated with hydro- chloric acid, is saturated with hydrogen sulphide. Iron, aluminium, and alkaline earths will be indicated in the solution of the salt by a brownish coloration or an insoluble pre- cipitate upon the addition of an excess of .solution of ammonium carbonate ; if to the clear filtrate a white precipitate be pro- duced upon the subsequent addition of a few drops of solution of sodium phosphate, magnesium salts will be indicated. Alkaline salts may be recognized by a strongly alkaline reaction, when a small portion of the salt is completely reduced upon char- coal, before the blow-pipe, and the residue tested with moist blue litmus-paper ; or, a solution of the salt is completely precipitated by ammonium sulphide and filtered ; the filtrate evaporated to dryness, and subsequently ignited ; a fixed residjie, having a strongly alkaline reaction, will indicate the above-mentioned impurity. ZINCI BROMIDUM. ZINCUM BROMATUM. Bromide of Zinc. Zinc Bromide. Ger. Bromzink ; Fr. Biomure de zinc ; Sp. Bromuio de zinc. ZnBr,; 224.5. A white, or nearly white, granular powder, very deliquescent, having a sharp saline and metallic taste, and neutral in its action upon litmus. When strongly heated, it fuses, and, at a higher temperature, may be sublimed in the form of white, prismatic needles. Zinc bromide is very freely soluble in water and in alcohol. Its aqueous solution yields white precipitates wnth potassium ferrocyanide and ammonium sulphide, and a yellowish-white one with argentic nitrate, soluble in a large excess of ammonia- water ; it also forms white precipitates with the alkaline hydrates and carbonates, of which those with the hydrates, and with ammo- nium carbonate, are redissolved by an excess of the precipitant, but these solutions are precipitated again, by boiling, if not too concentrated. If to the solution a few drops of carbon bisulphide be added, and subsequently chlorine- water, drop by drop, and the mixture agitated, the carbon bisulphide will assume a yellowish or brownish-red color. One gram of the dry salt, when completely precipitated by 588 MANUAL OF CHEMICAL ANALYSIS. argentic nitrate, yields a precipitate of argentic bromide, which, when washed and dried, should weigh 1.67 grams. Examination : Metallic impurities will be indicated in the solution of the salt, acidulated with hydrochloric acid, by a dark coloration or a pre- cipitate upon saturation with hydrogen sulphide. Iron, aluminium, and alkaline earths will be indicated in the solution of the salt by a brownish coloration or an insoluble pre- cipitate upon the addition of solution of ammonium carbonate in excess; if to the clear filtrate a white precipitate be produced upon the subsequent addition of a few drops of solution of sodium phosphate, inagnesi^im salts will be indicated. Alkalies and alkaline earths may be recognized by completely precipitating a solution of the salt with ammonium sulphide, fiftering, evaporating the filtrate to dryness, and subsequently igniting; a fixed residue, having a strongly alkaline reaction to test-paper, will reveal the above-mentioned impurities. ZINCI CARBONAS PR.aEiCIPITATUS. ZINCUM CARBONIC CM PR^CIPITATUM. Precipitated Carbonate of Zinc. Precipitated Zinc Carbonate. Ger. Basisch kohlensaures Zinkoxyd; Fr. Carbonate de zinc ; Sp. Carbonato de zinc. 2(ZuC03) + 3Zn(OH),; 546.5. An impalpable white powder, permanent in the air, and without odor or taste. When strongly heated in a small porcelain cru- cible, or when heated on charcoal before the blow-pipe, it loses water and carbonic acid gas, and leaves a residue of zinc oxide, which is yellow while hot and white when cold. Precipitated zinc carbonate is insoluble in both water and alco- hol, but dissolves readily in acetic and the dilute mineral acids, with the liberation of carbonic acid gas. When the salt, in slight excess, is digested with dilute hjj-drochloric acid, and the solution subsequently filtered, the filtrate should afford the reactions and correspond to the tests of purity described under zinc chloride, on pages 589, 590 ; when digested with a small amount of water, and filtered, the filtrate should leave no residue on evaporation, indi- cating the absence of soluble salts. ZINCTJM. 589 ZINCI CHLORIDUM. ZINCUM CHLORATUM. ZINCUM MURIATICUM. Chloride of Zinc. Zinc Chloride. Ger. Chlorzink ; Fr. Chlorure de zinc; Sp. Cloruro de zinc. ZnCl^; 135.7. A colorless, coherent, granular powder, or colorless, opaque rods or fragments, very deliquescent and caustic. When heated to about 115° C. (239° P.), zinc chloride fuses to a clear liquid, which, on cooling, congeals to a white or grayish-white mass ; at a higher temperature it volatilizes with partial decomposition, emitting dense white vapors, which condense on cooling in the form of needle-shaped crystals, and leaving behind a slight residue, which is yellow while hot and white when cold. Zinc chloride is soluble in water, glycerin, alcohol, and ether, giving more or less turbid, and slightly acid, solutions, which, however, become clear upon the addition of hydrochloric acid ; the aqueous solution yields white precipitates with potassium ferrocyanide, ammonium sulphide, and with the alkaline hydrates and ^carbonates, of which those with the alkaline hydrates and ammonium carbonate are readily soluble in an excess of the pre- cipitant; the latter solutions may be again precipitated either by hydrogen sulphide or by boiling. The solution of zinc chloride, acidulated with nitric acid, yields, when diluted with water, a curdy white precipitate with argentic nitrate, soluble in ammonia- water, and it occasions white precipitates with liquids containing albumen or gluten. One gram of the dried salt, when completely precipitated with argentic nitrate, yields a precipitate of argentic chloride, which, when washed and dried, should weigh 2.11 grams. Examination : Metallic impurities (arsenic, cadmium, copper, lead) may be de- tected in the solution of the salt, acidulated with hydrochloric acid, by a dark coloration or a precipitate upon saturation with hydrogen sulphide. If a black precipitate is produced, it may indicate either lead or copper ; these may be distinguished by the addition of ammonia-water in excess to a little of the original solution, when a blue coloration of the liquid will reveal the pres- ence of copper. If a yellow precipitate is produced in the acidu- lated solution by hydrogen sulphide, it will indicate either arsenic or cadmium ; these may be distinguished or separated from each other by digesting the precipitate with ammonium sulphide, in which arsenious sulphide is soluble ; or, a small portion of the zinc chloride, dissolved in concentrated hydrochloric acid, is heated to boiling with a few drops of solution of stannous chloride or a fragment of pure tin-foil, when an ensuing brown precipitate will 590 MANUAL OF CHEMICAL ANALYSIS. reveal the presence of arsenic. The presence of cadmium will likewise be farther indicated in a solution of the salt by the addi- tion of potassium or sodium hydrate in excess, in which the precipitated cadmium hydrate is insoluble. Cakium and Magnesium Chlorides, Alkalies and their Salts. — A solution of the salt is completely precipitated by ammonium sul- phide, filtered, and the filtrate tested with ammonium oxalate; a white precipitate will reveal the presence of calcium; the fil- trate from the latter, if present, is subsequently tested with ammo- nium phosphate, when an ensuing white crystalline precipitate will indicate magnesium. The final filtrate from the preceding test, when evaporated to dryness, and ignited at a gentle heat, should leave no residue, otherwise an admixture of alkalies or their salts will be indicated. Ammonium chloride (ammonio-zinc chloride) may be detected by an ammoniacal odor, and by white vapors when a glass rod, moistened with acetic acid, is held in the orifice of the test-tube, wherein a small portion of the salt is heated with a strong solu- tion of potassium hydrate. Sulphate may be recognized in the diluted solution, acidulated with hydrochloric acid, by an ensuing white precipitate on test- ing with barium chloride. ZINCI lODIDUM. ZmCUM lODATUM. Iodide of Zinc. Zinc Iodide. 6er. Jodzink ; Fr. lodure de zinc ; Sp. loduro de zinc. Znl,: 318.1. A white, or nearly white, granular powder, which, when ex- posed to the air, first absorbs water and deliquesces, and after- wards takes up oxygen with the liberation of iodine. When strongly heated, it readily fuses to a colorless liquid, and, at a higher temperature, sublimes in the form of quadratic prisms or needles. Zinc iodide is very freely soluble in both water and alcohol, yielding solutions which possess a sharp saline and metallic taste and an acid reaction. The aqueous solution yields white precipi- tates with potassium ferrocyanide, ammonium sulphide, and the alkaline hydrates and carbonates, of which those with the alka- line hydrates and ammonium carbonate are readily soluble in an excess of the precipitant; the latter solutions may again be pre- cipitated by hydrogen sulphide or by boiling. The aqueous solu- tion also yields a yellow precipitate with solution of plumbic ace- tate, and a red one with mercuric chloride ; the latter precipitate being soluble in an excess of the precipitant. If to a solution of zrNCUM. 591 the salt a little chlorine-water be added, and the mixture subse- quently agitated with a few drops of chloroform or carbon bisul- phide, the latter will acquire a reddish or violet color. One gram of the dried salt, when completely precipitated by argentic nitrate, yields a precipitate of argentic iodide, which, when washed and dried at 100° C. (212° ¥'.), should weigh 1.47 grams. Examination : Zinc or ammonium chlorides (ammonio-zinc chloride) may be detected by completely precipitating a solution of the salt with argentic nitrate, collecting the precipitate on a filter, and, after washing with water, digesting it with ammonia-water; the mix- ture is then filtered, and the filtrate supersaturated with nitric acid, when an ensuing white precipitate will reveal the presence of chloride. Metallic and other impurities may be detected by the same tests and method of examination, as described under zinc chloride, on pages 589, 590. ZINCI OXIDUM. ZINCUM OXYDATUM. FLORES ZINCI. Oxide of Zinc. Zinc Oxide. Ger. Zinkoxyd, Zinkweiss; Fr. Oxyde de zinc ; Sp. Oxido de zinc. ZnO; 80.9. A soft, white powder, having occasionally a pale yellowish tint, inodorous and tasteless, and not becoming discolored in contact with hydrogen sulphide. When heated in a dry tube or a porce- lain crucible, it neither fuses nor volatilizes, but assumes a lemon- yellow color, which disappears again on cooling; when the oxide is subsequently heated with a mixture of equal parts of acetic acid and water, it dissolves wholly and without efi'ervescence. When moistened with one drop of solution of cobaltous nitrate, and heated in the flame of the blow-pipe, zinc oxide assumes a • green color. Zinc oxide is insoluble in water, glycerin, and alcohol, but solu- ble in diluted acids, forming colorless solutions, which, with the exception of the solution in acetic acid, are not affected by hydro- gen sulphide, and the latter solution should afford with this reagent a purely white precipitate ; the neutral solutions, with the exception of the acetate, are only incompletely precipitated by hydrogen sulphide, but completely by ammonium sulphide; when alkaline, they are wholly precipitated by both reagents. The solutions of zinc oxide form white precipitates with the alka- line hydrates and carbonates, of which those with the former, and 592 MANUAL OF CHEMICAL ANALYSIS. with amnioaium carbonate, are soluble in an excess of the precipi- tant, but the}'' are reprecipitated from these solutions, if not too concentrated, by boiling. Zinc oxide is, therefore, soluble in con- centrated solutions of the alkaline hydrates (when free from car- bonates), and of ammonium carbonate. Zinc oxide absorbs carbonic acid slowly from the atmosphere. Examination : Sulphates and Chlorides. — A small portion of the zinc oxide is agitated for a few minutes with about ten times its weight of boil- ing water, and subsequently filtered; a few drops of the filtrate, evaporated upon platinum-foil, should leave no residue ; nor should the filtrate, after the addition of a few drops of nitric acid, give any reaction with barium nitrate or with argentic nitrate. Garhonate, Sulphates and Phosphates of the Alkaline- Earths, and Alumina. — The oxide left on the filter in the preceding test is dis- solved, with the aid of heat, in a small amount of acetic acid diluted with an equal volume of water; effervescence would indicate car- bonates, and an insoluble residue, calcium or barium sulphates (zinc oxide prepared in the dry way generally leaves a small gray resi- due, consisting of minute particles of metallic zinc, readily soluble in hydrochloric or nitric acid); the solution is filtered, if neces- sary, and is then supersaturated with ammonia-water ; the ensuing white turbidity must disappear upon the addition of an excess of the reagent ; a permanent turbidity would indicate earthy phos- phates or alumina. Metallic Impurities (copper, lead, arsenic, and cadmium). — A portion of the zinc oxide is dissolved in dilute hydrochloric acid, the solution diluted with a little water, and subsequently satu- rated with hydrogen sulphide ; an ensuing black precipitate would indicate either copper or lead. The former will have been indicated in the preceding test by a blue coloration of the liquid upon supersaturating the acid solution of the oxide with ammo- nia-water ; it may also be detected in the dilute acid solution by a brown coloration on the addition of a few drops of solution of potassium ferrocyanide. Lead may be specially tested for, if required, by dissolving a small portion of the zinc oxide in 10 times its weight of warm diluted acetic acid, and to the clear solution subsequently adding a few drops of solution of potassium, iodide ; an ensuing yellow coloration or precipitate would reveal the presence of lead. If a yellow precipitate has been produced in the acid solution by hydrogen sulphide, it will indicate either arsenic or cadmium. These may be distinguished as follows: The precipitate is col- lected on a filter, washed with water, and digested with a concen- trated solution of ammonium carbonate ; arsenious sulphide is thereby dissolved, and may be confirmed by the application of Fleitmann's test, as described on pages 36, 37, or, if the solution ZINCUM. 593 Fig. 175. be not too dilute, it may be reprecipitated by subsequent super- saturation with hydrochloric acid. Cadmium sulphide is insolu- ble in ammonium carbon- ate, and may be recognized by a red-brown coating of the coal, when heated with a little exsiccated sodium carbonate upon charcoal be- fore the blow-pipe (Fig. 175). As a confirmatory test for arsenic, or to detect a minute quantity of it, a small portion of the oxide may be dissolved in about ten times its weight of con- centrated hydrochloric acid, and, after the addition of a few drops of concentrated solution of stannous chloride or a fragment of pure tin-foil, heated to boiling ; a brown turbidity would con- firm the presence of arsenic. Iron, Calcium, and Magnesium. — The acid solution, after satu- ration with hydrogen sulphide, as described in the preceding test, is neutralized with ammonia-water, and completely precipitated by ammonium sulphide ; a purely wiiite precipitate should ensue ; a black coloration would indicate iron. -The filtrate from the latter precipitate is heated to boiling, filtered', and the filtrate tested with ammonium oxalate, when a white precipitate will reveal the presence of calcium ; the filtrate from the latter pre- cipitate is subsequently tested with ammonium phosphate, when a white, crystalline precipitate will indicate magnesium. ZINCI PHOSPHIDITM. ZINCUM PHOSPHORATUM. P7wsphide of Zinc. Zinc Phosphide. Ger. Phospliorzink ; Fr. Phosphure de zinc ; Sp. Fosfido de zinc. Zn^P,; 256.7. A grayish powder, or minutely crystalline, friable fragments, having a bright, metallic, bismuth-like lustre. It possesses a faint odor, and the taste of phosphorus, and is permanent in the air. When strongly heated, with exclusion of air, zinc phosphide fuses and is completely volatilized ; if heated with access of air it is principally converted into zinc phosphate. Zinc phosphide is insoluble in water or alcohol, but is readily 38 594 MANUAL OF CHEMICAL ANALYSIS. and completely soluble in dilute hydrochloric and sulphuric acids, with the evolution of spontaneously inflammable hydrogen phosphide. When dissolved in dilute hydrochloric acid, with the employment of a slight excess of the salt, filtered, and subse- quently heated to expel the hydrogen phosphide, a solution is obtained which yields white precipitates with potassium ferro- cyanide, ammonium sulphide, and with the alkaline hydrates and carbonates ; of these, the precipitates produced by the alka- line hj'drates and ammonium carbonate are readily soluble in an excess of the precipitant. Examination : Zinc phosphate, traces of which are usually contained in the phosphide, may be extracted by digestion with a cold sohition of ammonium chloride, and may subsequently be recognized by an ensuing white crystalline precipitate on the addition of ammonia- water and solution of magnesium sulphate. Metallic and other impurities may be detected in the solution of zinc phosphide in diluted hydrochloric acid by the same tests and methods of examination as described under Zinc Chloride, on pages 589, 590. ZINCI SULPHAS. ZINCUM SULFUEICUM. Sulphate of Zinc. White Vitriol. Zinc Sulphate. Ger. Sch-wefelsaures Zinkoxyd, Weisser Vitriol ; Fr, Sulfate de zinc ; Sp. Sulfate de zinc. ZnSO,4-7HjO; 286.9. Colorless, transparent rhombic prisms (Figs. 176 and 177) or acicular needles, containing 7 molecules (43.89 per cent.) of water Fig. 176. Fio. 177. illln-i -^ llpnV- /^ 14 'J of crystallization, and efflorescing slowly on exposure to the air. When heated at 100° C. (212° F.) they lose 6 molecules (37.6 per cent.) of water, the remaining molecule of water being eliminated ziNCUM. 595 only at a temperature of from 230 to 240° C. (446 to 464° F.) ; at a stronger heat, the salt is decomposed, sulphur dioxide and oxygen being evolved, while a basic salt remains behind; at a white heat, it is completely decomposed, leaving a residue of zinc oxide, which, when moistened with one drop of solution of co- baltous nitrate, and heated again to redness, assumes a green color (magnesium sulphate, when similarly treated, gives a reddish coloration, alum a blue one). Zinc sulphate is readily soluble in water, 100 parts of which dissolve at 10° 0. (50° F.) 138 parts, at 20= 0. (68° F.) 161.5 parts, and at 100° C. (212° F.) 653.5 parts, of the crystallized salt; it is soluble in about 3 parts of glj^cerin, and in an excess of the solutions of the alkaline hydrates, but it is little soluble in strong, and not at all in absolute, alcohol ; the aqueous solution reddens blue litmus-paper and has a metallic styptic taste, remains color- less with solution of tannic acid, and gives a copious white pre- cipitate with highly diluted solution of barium chloride. Its deportment with reagents is the same as described under Zinc Oxide, on pages 591, 592. Examination : Metallic Impurities. — A concentrated solution of zinc sulphate is slightly acidulated with a few drops of diluted hydrochloric acid, and subsequently saturated with hydrogen sulphide ; no tur- bidity or coloration should ensue ; a dark or yellowish coloration or precipitate would indicate copper, lead, cadmium, or arsenic. The filtered liquid, upon subsequent supersaturation with ammonia- water, should yield a perfectly white precipitate ; a dark coloration would indicate the presence of iron. The same test may serve to distinguish at once magnesium sul- phate from zinc sulphate ; these substances, being isomorphous and of a similar appearance, are liable to be taken one for the other ; solution of magnesium sulphate is not acted upon by hydrogen sulphide, ammonium sulphide, or potassium ferrocy- anide, and the precipitate produced by solutions of potassium or sodium hydrate are insoluble in an excess of the precipitant. Magnesium and aluminium sulphates are further indicated by the following tests : To a solution of the zinc sulphate a little ammonium chloride is added, and subsequently ammonia-water in considerable excess ; the precipitate first formed should become completely dissolved; an insoluble flocculent precipitate would indicate aluminium. The filtered liquid is subsequently tested with ammonium phosphate, when the immediate or gradual forma- tion of a white, crystalline precipitate will indicate magnesium. Potassium and sodium sulphates may be detected by adding to a solution of the zinc sulphate a solution of plumbic acetate until a precipitate ceases to be produced, filtering, and subsequently completely precipitating the zinc and excess of lead by hydrogen sulphide; the filtered liquid upon evaporation to dryness should 596 MANUAL OF CHEMICAL ANALYSIS. leave no residue; a non-volatile residue, imparting a brown color to moistened turmeric paper, would indicate the above-mentioned impurities. Ammonium salts may be recognized by the odor of ammonia, and by the development of white fumes, when a glass rod, moist- ened with acetic acid, is held over the orifice of the test tube in which a little zinc sulphate has been heated with a strong solu- tion of potassium hydrate. Chlorides may be detected in a dilute solution of the salt, acidu- lated with nitric acid, by a white precipitate on the addition of solution of argentic nitrate. Nitrates may be detected by ensuing decoloration of the liquid, when a solution of the salt, tinted with a drop of indigo solution, Pig. 178. is gently heated with a few drops of concentrated sulphuric acid ; or, a crystal of ferrous sulphate is dissolved in a solution of the salt, and the liquid carefully poured upon a little concentrated sulphuric acid, in a test-tube, so as to form, two layers (Fig. 178); a violet or brown coloration at the line of contact of the two liquids will reveal the presence of nitrates. ziNcuM. 597 ZINCI SULFHOCARBOLAS. ZINCUM SULFOCARBOLICUM. ZINCUM SULFOPHENYLICUM. Sulphocarbolate or Sulphoplienylate of Zinc. Zinc Sulphocarbolate. Ger. Phenolsulfosaures Zinkoxyd ; Fr. SnUbcarbolate de zinc; Sp. Sulfocarbolato de zinc. Za(C6li,.OH.S03), + 8H,0; 554.9. Colorless, transparent, rhombic prisms or plates, or a white, crystalline powder, odorless, or possessing but a slight odor of phenol, and readily efflorescing on exposure to dry air. The salt contains 8 molecules (26 per cent.) of water of crystallization, which are expelled at a temperature of 130° C. (266° F.) ; when more strongly heated, the salt is decomposed, with the liberation of sulphur dioxide and phenol, and leaving a residue of carbon and zinc sulphate, which, at a strong red heat, is completely con- verted into zinc oxide. Zinc sulphocarbolate is soluble in 2 parts of water and 5 parts of alcohol at 15° C. (59° F.), yielding slightly acid solutions, which, when diluted, aftbrd a deep violet color on the addition of a few drops of solution of ferric chloride, and a white precipitate upon saturation with hydrogen sulphide; it also yields white precipitates with potassium ferrocyanide, ammonium sulphide, and with the alkaline hydrates and carbonates, of which those with the alkaline hydrates and ammonium carbonate are readily soluble in an excess of the precipitant. One hundred parts of the salt, when strongly ignited at a red heat, leave a residue of zinc oxide, weighing 14.58 parts. Examination : Zinc sulphate may be detected by the incomplete solubility of the salt in alcohol, or by the occurrence of a turbidity or precipi- tate when a concentrated aqueous solution of the salt is dropped into alcohol, as also by the formation of a white precipitate when the dilute aqueous solution of the salt is tested with barium chloride. Metallic impurities may be detected by a dark coloration or a precipitate when the aqueous solution of the salt, acidulated with hydrochloric acid, is saturated with hydrogen sulphide. Salts of the Alkalies and Alkaline- Earths. — A portion of the salt is dissolved in ten times its weight of water, and to the solution ammonia-water in slight excess is added, until th6 precipitate at first produced is redissolved ; an incomplete solution would indi- cate the presence of aluminium and magnesium. The clear liquid is subsequently saturated with hydrogen sulphide until the zinc has become completely precipitated, filtered, and the filtrate tested with ammonium carbonate; a white precipitate would indicate barium or calcium; the filtrate from the latter precipitate, should 598 MANUAL OF CHEMICAL ANALYSIS. such have been produced, is evaporated to dryness, and subse- quently ignited in a small porcelain crucible, when a non-volatile residue will indicate salts of the alkalies. ZINCI VALERIANAS. ZINCUM VALERIANICUM. Yalerianate of Zinc. Zinc Valerianate. 6er. Baldi'iansaures Zinkoxyd ; Fr. Valerianate de zinc ; Sp. Valerianate de zinc. Zn(C,HgO,),4-H,0; 284.9. White, pearly, lamellar crystals, or a white, scaly, crystalline powder, permanent in the air, somewhat unctuous to the touch, and with a feeble odor of valerianic acid. It contains 1 molecule (6.3 per cent.) of water of crystallization, which is eliminated at a temperature of 100° 0. (212° F.), and is not again absorbed by subsequent exposure to the air; at a higher temperature (about 146° C. = 284° F.) the salt fuses, with partial decomposition, to a clear, thick liquid, and solidifies again upon cooling in a crystal- line form ; when strongly heated, it evolves white, inflammable vapors, leaving a residue of zinc oxide, which, when moistened with a drop of a solution of cobaltous nitrate, and reheated to redness, becomes green. Zinc valerianate is soluble in 100 parts of water and in 40 parts of alcohol at 15° C. (59° F.), and is also soluble in glycerin, and in an excess of ammonia-water, but only sparingly in ether or chloroform. Its solutions redden blue litmus-paper, and become turbid upon gently warming, but clear again on cooling ; by pro- longed boiling, an insoluble basic salt is deposited, having the composition Zxi{G^gO^^-\-27in[0'S.\. The salt is also readily soluble in diluted acids, but with decomposition, and consequent turbidity from the elimination of the valerianic acid, which grad- ually collects as an oily stratum upon the surface of the aqueous solution ; an addition of ammonia-water at first increases the tur- bidity, but, when added in excess, forms a clear solution, which yields a white precipitate with ammonium sulphide. The deportment of solutions of zinc valerianate with reagents, after the elimination of the acid by hydrochloric or sulphuric acid, is the same as described under Zinc Oxide, on pages 591, 592. One gram of the salt, when moistened with nitric acid, evapo- rated to dryness, and ignited at a red heat, should leave a residue of zinc oxide weighing 0.283 gram ; or, when the anhydrous salt has been employed, the residue should weigh 0.308 gram. Examination : Zinc acetate may be detected by agitating a little of the tritu- rated zinc valerianate, in a test-tube, with about four times its ZrNCUM. 599 weight of cold water, and adding to the filtrate one or two drops of ferric chloride ; the liquid, if necessary, is filtered again, and must appear almost colorless ; a reddish tint would indicate acetic acid. Tartaric and Oxalic Acids. — The undissolved valerianate of the preceding test is rinsed through the broken filter into a test-tube, and is agitated with a sufficient quantity of ammonia- water ; a complete solution must take place, which should retain its trans- parency on the addition of a few drops of solution of calcium chloride ; a white turbidity or precipitate would indicate the above-mentioned acids or their respective salts. Zinc butyrate may be detected by the occurrence of a turbidity or precipitate when a cold, concentrated solution of the salt is mixed with a concentrated solution of cupric acetate; or, about 6 grams of the salt are triturated, and added, in a small flask, to a mixture consisting of 10 grams of concentrated sulphuric acid and 10 grams of water ; the mixture is submitted to distillation at a gentle heat (Fig. 179), until about 2 grams of distillate are ob- FiG. 179. tained ; this is agitated with a little concentrated solution of cupric acetate, which should not immediately affect the transparency of the liquid, but it forms, after a while, oily drops of anhydrous cupric valerianate, which, after from 5 to 20 minutes, pass into a greenish-blue crystalline deposit of hydrated cupric valerianate. If, however, the salt consists mainly or wholly of butyrate, the transparency of the liquid would at once be impaired by the formation of a crystalline precipitate. The presence of butyrate, if the amount be not too small, will likewise be indicated by dissolving the salt in the smallest pos- sible amount of warm, absolute alcohol, saturating with hydrogen sulphide, and, after filtration, allowing the filtrate to evaporate spontaneously; if the residual acid consists of ordinary butyric 600 MANUAL OF CHEMICAL ANALYSIS. acid,, it will be miscible in all proportions with water, whereas valerianic acid requires 25 parts of water for solution. Boric acid may be detected by triturating a little of the salt with a few drops of alcohol, and by igniting and burning the mix- ture, with stirring ; a green coloration of the flame, especially toward the termination of the ignition, would indicate boric acid. Sulphates and chlorides may be detected in the aqueous solution of the salt by acidulating with nitric acid, heating, in order to expel the liberated valerianic acid, and subsequently testing the filtered liquid, in separate portions, with barium chloride for sul- phates, and with argentic nitrate for chlorides ; a white precipitate in either instance would reveal the presence of such impurities. Salts of the Alkalies and Alkaline Earths. — -A portion of the salt is agitated with a sufficient quantity of ammonia-water to form a complete solution ; an insoluble residue would indicate aluminium or magnesium. The ammoniacal liquid is subsequently com- pletely precipitated by hydrogen sulphide or ammonium sulphide, filtered, and the filtrate tested with ammonium carbonate ; an ensuing white precipitate would indicate barium, or calcium; the filtrate from the latter precipitate, if such has been produced, is evaporated to dryness, and subsequently ignited in a small porce- lain crucible, when a non-volatile residue will indicate salts of the alkalies. rv TABLES AKD INDEX. TABLES TABLE OF ELEMENTARY BODIES, WITH THEIR SYMBOLS AND ATOMIC WEIGHTS. Name. Aluminium . . . . Antimony . . . . Arsenic Barium Beryllium (Glucinum) Bismuth Boron Bromine Cadmium . . . . Caesium Calcium Carbon Cerium Chlorine Chromium Cobalt Copper Didyniium . . . . Erbium Fluorine Gallium Gold Hydrogen .... Indium Iodine Iridium Iron Lanthanum .... Lead Lithium Magnesium .... Manganese .... Mercury Sym- bol. Al Sb As Ba Be Bi B Br Cd Cs Ca C Ce CI Cr Co Cu Di E Fl G Au H In I Ir Fe La Pb Li Mg Mn H- Atomic Weight. 27 120 74.9 136.8 9 210 11 79.8 111.8 132.6 40 12 141 35.4 52.4 58.9 63.2 144.6 165.9 19 68.8 196.2 1 113.4 126.6 19-.^.7 55.9 138.5 206.5 7 24 54 199.7 I^ame. Molybdenum Nickel . Niobium . Nitrogen. Osmium . Oxygen . Palladium Phosphorus Platinum Potassium Rhodium Rubidium Ruthenium Scandium Selenium Silicon . Silver. Sodium . Strontium Sulphur . Tantalum Tellurium Thallium Thorium . Tin . . Titanium Tungsten Uranium. Vanadium Ytterbium Yttrium . Zinc . . Zirconium Syra- liol. Atomic Weight. Mo 95.5 Ni 58 Nb 94 N 14 Os 198.5 16 Pd 105.7 p 31 Pt 194.4 K 39 Rh 104.1 Rb 85.3 Ru 104.2 Sc 44 Se 78.8 Si 28 Ag 107.7 Na 23 Sr 87.4 S 32 Ta 182 Te 128 Tl 203.7 Th 233 Sn 117.7 Ti 48 W 183.6 U 238.5 V 51.3 Yb 172.7 Y 89.8 Zn 64.9 Zr 90 604 TABLES. TABLE OF THERMOMETRIO EQUIVALENTS According to the Centigrade and Falirenheit Scales. Cent. Fahr. Cent. Fahr. Cent. Fahr. Cent. Fahr. O O O O O O O —40 —40.0 +16 -f60.8 + 73 +161.6 +138 +868.4 39 38.3 17 63.6 73 163.4 129 364.3 38 36.4 18 64.4 74 165.3 130 366.0 37 34.6 19 66.3 75 107.0 131 307.8 - 36 33.8 30 68.0 76 168.8 133 369.6 35 31.0 81 69.8 77 170.6 183 371.4 34 39.3 83 71.6 78 173.4 134 878.3 33 37.4 83 73.4 79 174.8 185 875.0 33 35.6 34 75.8 80 176.0 136 370.8 31 33.8 25 77.0 81 177.8 137 378.0 30 33.0 86 78.8 82 179.6 138 380.4 39 30.3 37 80.0 83 181.4 139 388.3 38 18.4 88 83.4 84 183.3 140 384.0 37 16.6 39 84.3 85 185.0 141 385.8 36 14.8 30 86.0 86 186.8 148 387.6 35 13.0 31 87.8 87 188.0 143 289.4 34 11.3 33 89.6 88 190.4 144 391.8 33 9.4 33 91.4 89 193.3 145 393.0 S3 7.6 34 98.3 90 194.0 146 394.8 31 5.8 35 95.0 91 195.8 147 396.6 30 4.0 36 96.8 93 197.6 148 398.4 19 3.3 37 98.6 93 199.4 149 300.3 18 0.4 38 100.4 94 301.3 150 303.0 17 + 1-4 39 103.8 95 303.0 151 303.8 16 3.3 40 104.0 96 804.8 158 305.6 15 5.0 41 105.8 97 306.6 153 307.4 14 6.8 43 107.6 98 308.4 154 309.3 13 8.6 43 109.4 99 310.8 155 311.0 18 10.4 44 111.3 100 318.0 156 818.8 11 13.3 45 113.0 101 313.8 157 814.0 10 14.0 46 114.8 103 315.6 158 316.4 9 15.8 47 116.6 103 317.4 159 318.3 8 17.6 48 118.4 104 319.3 160 330.0 7 19.4 49 130.^ 105 831.0 161 331.8 6 31.3 50 133.0 106 883.8 103 883.0 5 38.0 51 133.8 107 334.6 168 335.4 4 34.8 53 185.6 108 336.4 164 837.8 3 36.6 58 137.4 109 888.8 165 839.0 3 38.4 54 189.3 110 830.0 166 330.8 1 30.3 55 181.0 111 331.8 167 338.6 38.0 56 138.8 113 333.6 168 334.4 +1 33.8 57 134.6 113 335.4 169 386.3 3 35.6 58 130.4 114 837.3 170 338.0 3 37.4 59 138.3 115 839.0 171 339.8 4 39.3 60 140.0 116 340.8 178 341.6 5 41-0 01 141.8 117 342.6 178 343.4 6 43.8 63 143.6 118 344.4 174 345.3 7 44.6 63 145.4 119 846.2 175 347.0 8 46.4 64 147.8 180 348.0 176 348.8 9 48.3 65 149.0 181 349.8 177 350.6 10 50.0 66 150.8 183 351.6 178 353.4 11 51.8 67 153.6 183 358.4 179 354.3 13 53.6 68 154.4 184 355.3 180 356.0 13 55.4 69 156.3 135 357.0 181 357.8 14 57.8 70 158.0 136 358.8 183 359.6 15 59.0 71 159.8 187 360.6 183 361.4 TABLES. 605 TABLE OF THERMOMETRIC EQUIVALENTS — Oontinued. Cent. Fahr. Cent. Falir. Cent. Fahv. Cent. Fiihr. O O o O O o O +184 +363.2 +221 + 429.8 +258 +496.4 +395 +563.0 185 365.0 332 431.6 359 498.2 296 564.8 186 366.8 323 433.4 360 500.0 297 566.6 187 368.6 224 435.2 261 501.8 398 568.4 188 370.4 335 437.0 263 503.6 299 570-3 ' 189 372.2 226 438.8 263 503.4 300 572.0 190 374.0 227 440.6 264 507.2 301 573.8 191 375.8 228 442.4 265 509.0 302 575.6 192 377.6 229 444.2 266 510.8 303 577.4 193 379.4 230 446-0 267 512.6 304 579.2 194 381.2 231 447.8 368 514.4 305 581.0 195 383.0 333 449.6 369 516.2 306 582.8 196 384.8 233 451.4 270 518.0 307 584.6 197 386.6 234 453.3 271 519.8 308 586.4 198 388.4 235 455.0 273 521.6 309 588.2 199 390.3 336 456.8 273 523.4 310 590.0 200 392.0 337 458.6 374 525.2 311 591.8 201 393.8 238 460.4 275 537.0 313 593.6 302 395.6 239 462.2 376 528.8 313 595.4 203 397.4 240 464.0 377 530.6 314 697.2 204 399.2 241 465.8 278 533.4 315 599.0 205 401.0 242 467.6 379 534.2 316 600.8 206 403.8 243 469.4 280 .136.0 317 603.6 207 404.6 244 471.2 381 537.8 318 604.4 208 406.4 845 473.0 383 539.6 319 606.2 209 408.2 346 474.8 283 541.4 330 608.0 210 410.0 247 476.6 284 543.2 330 626.0 211 411.8 248 478.4 285 545.0 340 644.0 213 413.6 249 480.2 28fi 546.8 350 663.0 213 415.4 250 483.0 287 548.6 360 680.0 314 417.2 251 483.8 288 550.4 370 698.0 215 419.0 252 485.6 289 553.2 380 716.0 216 420.8 253 487.4 290 554.0 390 734.0 217' 423.6 254 489.2 291 555.8 400 753.0 218 424.4 255 491 392 557.6 410 770.0 219 426.3 256 493.8 293 5.59.4 430 788.0 320 428.0 257 494.6 294 561.3 430 806.0 Formula, for converting degrees of the Centigrade scale into those of Fahrenheit (D representing the degree to be converted). D If above the freezina point of water, 33^ F. (0° C.) X9 + 32. If below freezing, but above o F. (— 17.77'3 C.) 32 —(- x o). If below OO F. (— 17.770 0. ) — /":? \_ 33. FormulcB for converting degrees of the Fahrenheit scale into those of Centigrade. If above the freezing point of water, 330 F. (0° C.) iEzi^ x 5. If below freezing, but above 0= F. (— 17.77° C.) — '^^~-°) x 5. If below OOF. (—17.770 c.) _(^+33) — g— X5. 606 TABLES. TABLE FOR CONVERTING METRIC MEASURES OP CAPACITY INTO UNITED STATES FLUID MEASURES. Cubic centi- Minims. Cubic centi- Fluid Fluid Miuims. Cubic ceuti- Fluid Fluid Minims meters. meters. ounces. dr'hms. meters. ounces. dr'hms. 0.01 0.16 0.65 10.55 46 1 4 36.40 0.02 0.32 0.70 11.36 47 1 4 42.60 0.03 0.49 0.75 13.17 48 1 4 58.80 0.04 0.65 0.80 13.98 49 1 5 15.00 0.05 0.81 0.85 13.80 50 1 5 31.80 0.06 0.97 0.90 14.61 60 3 14.40 0.07 1.14 0.95 15.42 70 3 3 56.40 0.08 1.30 1 16.23 80 3 5 36.60 0.09 1.46 3 33-46 90 3 31.00 0.10 1.63 3 48-69 100 3 3 3 60 0.11 1.79 4 "i 4.80 110 3 5 46.30 0.13 1.95 5 1 31.00 130 4 28.20 0.13 3.11 6 1 37.30 130 4 3 8.40 0.14 2.37 7 1 53.40 140 4 5 52.80 0.15 2.43 8 3 9.60 150 5 35.40 0.16 3.60 9 3 35.80 160 5 3 18.00 0.17 3.76 10 2 43.60 170 5 6 0.18 3.92 11 3 58.83 180 6 40.30 0.19 3.08 13 3 15.06 190 6 3 84.60 0.20 3.35 13 3 81.39 200 6 6 7.20 0.21 3.41 14 3 57-40 335 7 4 52.85 0.22 3.57 15 4 13.60 350 8 3 39.00 0.23 3.74 16 4 19.80 375 9 3 34.65 0.24 3.90 17 4 36.00 300 10 1 10.80 0.25 4.06 18 4 53.30 335 10 7 56.40 0.26 4.32 19 5 8.40 350 11 6 42.60 0.27 4.39 20 5 24.60 375 13 5 28.20 0.38 4.55 31 ! .. 5 40.83 400 13 4 14.40 0.29 4.71 22 5 57.06 435 14 3 0.30 4.87 23 6 13.39 450 15 1 46.20 0.31 5.03 24 6 29.40 475 16 , , 31.80 0.32 5.19 25 6 45.60 500 16 7 18.00 0.33 5.36 26 7 1.80 525 17 6 3.60 0.34 5.53 37 7 18.00 550 18 4 49.80 0.35 5.68 28 7 34.20 575 19 8 35.40 0.36 5.84 29 7 50.40 600 30 3 21.60 0.37 6.01 30 1 4.80 635 31 1 17.20 0.38 6.17 31 1 31.03 650 31 7 53.40 0.39 6.33 33 1 37.36 675 32 6 49.00 0.40 6.49 33 1 53.49 700 23 5 25.30 0.41 6.65 34 1 i 9.60 735 24 4 10.80 0.42 6.81 35 1 1 35.80 750 25 3 57.00 0.43 6.98 36 1 1 42.00 775 26 1 48.60 0.44 7.14 37 1 1 58.30 800 27 28.80 0.45 7.30 38 1 2 14.40 835 37 7 14.40 0.46 7.46 39 1 2 30.60 850 38 6 0.60 0.47 7.63 40 1 3 49.30 875 29 4 46.30 0.48 7.79 41 1 3 5.43 900 30 3 32.40 0.49 7.95 42 1 3 21.66 935 31 3 18.00 0.50 8.12 43 1 3 37.89 950 33 1 4.20 0.55 8.93 44 1 3 54.00 975 33 7 49.80 0.60 9.74 45 1 4 10.30 1000 33 6 36.00 TABLES. 607 TABLE FOR CONVERTING UNITED STATES FLUID MEASURES INTO METRIC MEASURES OF CAPACITY. Cubic _,. Fluid Cubic J?luid Cubic Minima. centimeters. ""' ms. dnichms. centimeters. ounces. centimeters. 1 O.OG 4 B 2.64 3 88.67 2 0.12 4 4 2.71 4 118.24 3 0.18 4 5 2.77 5 147.81 4 0.25 4 6 2.83 6 177.39 5 0.31 4 7 2.89 7 206.96 6 0.37 4 8 2.95 8 236.58 7 0.43 4 9 3.01 9 266.10 8 0.49 5 3.08 10 295.68 9 0.55 5 5 3.39 11 325.25 10 0.62 6 3.70 12 354.82 11 0.68 6 5 4.01 13 384.40 12 0.74 7 4.31 14 413.97 13 0.80 7 5 4.62 15 443.54 14 0.86 8 4.93 16 473.11 15 0.92 8 5 5.24 17 502.69 16 0.!)9 9 5.54 18 532.26 17 1.05 9 5 5.85 19 561.93 18 1.11 10 6.16 20 591.50 19 1.17 11 i 6.78 21 621.08 20 1.23 12 1 7.89 22 650.65 21 1.29 3 11.09 23 680.22 22 1.36 4 14.79 24 709.80 23 1.42 J 5 18.48 25 739.37 24 1.48 . 1 6 22.18 26 768.94 25 1.54 7 25.88 27 798.51 26 1.60 8 29.57 28 828.09 27 1.66 9 33.27 29 857.66 28 1.73 10 36.97 30 887.23 29 1.79 11 40.66 31 916.80 30 1.85 12 44.36 32 946.38 31 1.91 13 48.06 40 1183.00 32 1.97 14 51.75 45 1830.81 38 2.03 i 15 55.45 48 1419.53 34 2.10 16 59.10 50 1478.74 35 2.16 17 62.85 55 1626.55 36 2.22 18 66.54 60 1774.46 37 2.28 19 70.24 64 1892.75 38 2..S4 20 73.94 80 2366.00 39 2.40 21 77.63 96 2839.11 40 2.46 22 81.33 112 8312.22 41 2.52 23 85.03 128 3785.51 42 2.58 256 7571.02 608 TABLES. TABLE FOR CONVERTING METRIC WEIGHTS INTO TROY WEIGHTS. eqiiiva- leucs in 0.1543 0.3086 0.4630 0.6173 0.7717 0.9260 1.0803 1-2347 1.3890 1.543 3.086 4.630 6.173 7.716 9.259 10.803 12.346 13.889 15.432 30.865 46.397 61.729 77-162 93.594 108.026 123.459 138.891 154.323 169.756 Appruximate equivalents in Troy weights. 1 J 6 TT _7_ 1 H n 3 4| 6^ 7.1 9i lOJ 121 14 15^ 104 6^ If 17-1 12| 8 9! 13.0 13.0 14.0 15.0 16.0 17.0 18.0 19.0 20.0 31.0 33.0 23.0 34.0 25.0 26.0 27.0 28.0 29.0 30.0 31.0 83.0 40.6 45.0 50.0 60.0 70:0 80.0 90.0 100.0 equiva- lents in 185.188 200.621 316.053 331.485 246.918 362.350 Approximate equivalents in Troy weights. 277.783 293.315 308.647 334.079 339.513 354.944 370.376 385.809 401-241 416.673 432.106 447.538 463.970 478.403 493.835 617.394 694.456 771.617 935.941 1080.264 1334.588 1888.911 1543.235 3 m 8| 1 4iV 1 19i 3 15 10| 1 5J 3 n- 3 165 12i'o 1 n 2 3 3 181 13J .. 17A 1 m 2 HE 1' 6 -• i 1 14| 9 3 H TABLES. 609 TABLE FOR CONVERTING TROY WEIGHTS INTO METRIC • WEIGHTS. Gi-ains. Grams. Grains. Gi-ams. Grains. Grams. Grains. Grams. 1 0.0648 30 1.944 59 3.833 88 5.703 2 0.1396 31 8.009 60 3.888 89 5.706 3 0.1944 33 3.073 ,61 3.953 90 5.831 4 0.3593 83 3.138 63 4.017 91 5.896 5 0,3340 34 3.303 63 4.083 93 5.901 6 0.3838 35 2. 363 64 4.147 98 6.036 7 0.4536 36 3.333 65 4.311 94 0.090 8 0.5184 37 3.397 66 4.376 95 6.155 9 0.5833 88 3.463 67 4.341 96 0.330 10 0.6480 39 3.537 68 4.400 97 0.385 11 0.7180 40 3.593 69 4.471 98 0.350 13 0.7776 41 3.656 70 4.535 99 6.414 13 0.8434 43 3.731 71 4.600 100 6.479 14 0.9073 43 3.780 73 4.065 120 7.776 15 0.973 44 3.851 73 4.730 150 9.719 16 1.037 45 3.916 74 4.795 180 11.664 17 1.103 40 3.980 75 4.859 800 12.958 18 1.166 47 3.045 76 4.924 340 15.553 19 1.331 48 8.110 i 77 4.989 300 19.440 20 1.296 49 3.175 78 5.054 360 33.338 31 1.361 50 3.334 79 5.118 400 35.930 23 1.436 51 8.304 80 5.183 480 31.103 23 1.490 53 3.369 81 5.348 500 33.396 24 1.555 53 3.434 83 5.318 600 38.875 25 1.630 54 3.499 83 5.378 700 45.354 36 1.685 55 3.564 84 5.443 800 51.838 27 1.749 56 3 638 85 5.507 900 58.313 28 1.814 57 3.693 86 5.572 960 63.307 29 1.869 58 3.758 87 5.637 1000 64.793 39 INDEX. (The Latin aaaies are in Italics.) ACETATE of ammonium, solution 397 copper, 326 ethyl, 204 iron, solution of, 399 lead, 452 morphine, 432 potassium, 460 sodium, 530 zinc, 586 Acetic acid, 122 ether, 204 Acetum. 117 plumbicum, 407 Acid, acetic, 122 arsenious, 126 benzoic, 135 benzol-carbonic, 135 boraoic, 137 boric, 137 carbolic, 139 chromic, 142 chrysophanic, 312 citiic, 144 gallic, 147 hippurio, 136 hydriodic, 148 hydrobromic, 150 hydrochloric, 153 hydrocyanic, 159 hydrosulphuric (as j-eagent), 37 hypophosphorous, 163 isopropyl-acetio, 197 lactic, 164 metaphosphorio, 174 muriatic, 153 nitric, 165 oleic, 171 ortho-boric, 137 ortho-oxybenzoic, 181 ortho-phosphoric, 174 oxalic, 172 phenic, 139 phenyl-formio, 135 phosphoric, 174 of, Acid — picric (as reagent), 29 Balicylic, 181 succinic, 182 sulphuric, 184 sulphurous. 190 tannic. 192 tartaric, 195 valerianic, 197 Acids, examination for, fil volumetric estimation of, Aciduni aceticum, 122 arsenicosujn, 126 arsenic sum, 126_ benzoicum, 135 boricum, 137 carboUcicm, 130 ehroviicum^ 142 ciiricum, 1 44 goliicam, 147 ht/driodicum, 148 kydrobromicuni, 150 kydroehloricum, 153 hijdrocyanicum, 159 hypophosphorosum, K>3 lacticum, 164 muriaticum, 153 nUricum, 165 ohicum, 171 oleinicum, 171 oxalicum, 172 phenylicum, 139 phosphoricum, 174 salieylicum^ 181 succinicum, 182 svlfuricum, 184 sulfurosum, 190 tannicum, 102 tartaricum, 195 valerianicum, 197 Aconitina, 109, 200 Aco7ii(inum, 200 .iEruffo, 328 .mher, 201 aceiicus, 204 612 INDKX, Albumen (as reagent), 30 Alcohol, 206 atnylic, 210 ethylic, 206 plienylic, 139 Alcohol amylicum, 210 sitlf'wia, 301 AlgiU-oth's powder, 236, 398 Alkalies, volumetric estimatioa of, 80 Alkaloids, 102 Alkanet-paper, 42 Almonds, ethereal oil of, 440 water of bitter, 249 Aloin, 211 Aloimcm., 211 Alum, 212 iron, 346 Alumen, 212 Alumina hydrata^ 214 Aluminii et Ammonii Sulphas, 212 et Potassii Sulphas, 212 Hydras, 214 Sulphas, 216 Aluminium hydrate, 214 sulphate, 216 Aluminium hydratum, 214 sulfalum, 216 Ammonia, solution of, 245 water, 245 Ammoniated cupric sulphate, 332 ferric chloride, 344 mercury, 390 sulphate of copper. 332 Ammonii Acetat.is, Liquor, 397 Benzons, 217 liromidvm, 217 Carbonas, 221 Chloridum, 223 lodidum, 225 Murias, 223 Nilras, 226 Phosphas, 227 Sulphas, 228 Valerianas, 229 Amnionio-chloride of iron, 344 • cupric sulphate, 332 -ferric chloride, 344 -ferric citrate, 345 -ferric sulphate, 346 -ferric tartrate, 346 -mercuric chloride, 390 Ammonium acetate, solution of, 397 benzoate, 217 bromide, 217 carbonate, 221 chloride, 223 hydrate, solution of, 245 iodide, 225 molybdate (as reagent), 31 nitrate, 226 oxalate (as reagent), 31 phosphate, 227 Ammonium — sesqui-oarbonate, 221 sulphate, 228 sulphydrate (as reagent), 31 sulphide (as reagent), 31 valerianate, 229 Ammonium benzoicum, 217 bromaium, 217 carbonicum, 221 chloralum, 223 /erratum, 344 iodatum, 225 viurialicum, 223 marliaium, 344 nitricum, 226 phosphoricum, 227 valerianieum, 229 Amyl Nitris, 230 Amyl nitrite, 230 Amyliether nitrosus, 230 Amylic alcohol, 210 Amylium nitrosum, 230 Analysis, volumetric, 70 Anhydride, chromic, 142 Aniline sulphate (as reagent), 31 Antimoniate of potassium (as reagent), 40 Antimonic sulphide, 240 Aniimonii Chloridi, Liquor. 397 et Potassii Tartras, 232 Oxidum, 235 Oxy- sulphuretum, 242 Sulphidum, 237 aurantiacum, 240 Sulphuretum, 287 Antimonious chloride, solution of, 397 oxide, 235 oxy-chloride, 236 oxy-sulphide, 242 sulphide, 237 trioxide, 235 Antimonium et potassium tartaricum, 232 oxydatum, 235 sulfuratum aurantiacum, 240 nigrum, 237 rubeum, 242 sulfuratum, 242 tartaricum, 232 Antimony, butter of, 397 chloride, solution of, 397 oxide of, 235 oxy-chloride of, 236 oxy-sulphide of, 237 pentasulphide of, 240 sulphide of, 237 trioxide, 235 trisulpbide of, 237 Apomorphinse Hydrochloras, 245 Apomorphine hydrochlorate, 245 Apomorphinum hydrochloricum, 'lib Aqua Ammonias, 245 Amygdalse amarae, 249 Calcis, 399 INDEX. tU3 Aqua — C/ilori, 251 Destillata, 254 Argenii Cyanidum, 256 lodidum, 257 Nilras, 258 Oxidum, 261 Argentic cyanide, 256 iodlJe, 257 nitras, 258 volumetric solution of, 98 oxide, 261 sulphate (as reagent), 31 Argenlum cyanaium, 256 iodatum, 257 nitricum, 258 oxy datum, 261 Arseniate of iron, 339 sodium, 532 Arsenic, white, 126 detection in wall-paper and fabrics, 134 estimation in forensic investigation, 132 test for, Bettendorf's, 130 Fieitmann'a, 36 Marsh's, 33, 129 Reinsoh's, 129 tribromide, 262 triiodide, 263 Arsenicum album, 126 bromatttm, 262 iodatum, 263 Arscnii Bromidum, 262 lodidum, 268 Arsenious acid, 126 bromide, 262 iodide, 263 Arsenite of potassium, solution of, 410 Atomic weights of elementary bodies, 603 Alropina, 109, 263 Atropinse Sulphas, 265 Atropine sulphate, 265 Atropiuum, 109, 263 sulfuricum, 265 Auri et Sodii Ohloridum, 26G Auric chloride (as reagent), 31 AuTO-Nalrium chloralum, 266 BARBALOIN, 211 Baric chloride, 268 hydrate (as reagent), 31 nitrate (as reagent), 31 Barii Chloridum, 268 Baryta muriatica, 268 Baryum chloratum, 268 Bases, examination for, 40 Basic bismulhons carbonate, 273 nitrate, 276 valerianate, 277 ferrous carbonate, 360 Basic — mercuric sulphate, 386 plumbic carbonate, 453 Beer, estimation of glycerin in, 372 Bending of glass tubes, 25 Benzine, 32, 269 Benzinum, 269 Benzoate of ammonium, 217 lithium, 415 sodium, 533 Benzoic acid, 135 Bettendorf's test for arsenic, 130 Biborate of sodium, 358 Bicarbonate of potassium, 462 sodium, 534 Bichloride of mercury, 373 Bichromate of potassium. 464 Biniodide of mercury, 379 Bismuth and ammonium citrate, 272 carbonate, 273 nitrate, 276 valerianate, 277 Bismulfii et Ammonii Cilra^i, 272 Subcarhonas, 273 Subnilras, 276 Valerianas, 377 Bismuthous carbonate, 273 nitrate, 276 valerianate, 277 Bismutum carbonicum, 273 ct ammonium atricum, 272 nitricum, 276 valerianicuni, 277 Bisulphate of quinine, 516 Bisulphide of carbon, 301 Bisulphite of sodium. 537 Bisulphuret of carbon, 301 Bitartrate of potassium, 465 Bitter-almond oil, ethereal, 440 water, 249 Black oxide of manganese, 426 Bleaching powder, 296 Blue, Prussian, 350 vitriol, 330 Bohlig's reagent, 39 Boiling point, determination of, 23 Boracic acid, 137 Borate of sodium, 538 Borax, 538 Bread, detection of alum in, 214 Bromide of ammonium, 217 arsenic, 262 calcium, 287 lithium, 416 potassium, 467 sodium. 539 Bromine, 279 water (as reagent), 32 Brominium, 279 Bromum, 279 Brucina, 109, 282 Bruclne, 109, 262 614 INDEX. Brudnum, 1 09, 282 Burettes, 73 Butyl-chloral hydrate, 308 Butylo-chloralum hydraium, 308 Jiutyrum antimonii. 246 /lADMIJ lodidum, 284 ^ Sulphas, 285 Cadmium iodide, 284 sulphate, 285 Cadmium iodatunt. 284 su/furicum, 285 Caffeina, 286 Catfeine, 286 Calcaria carbonica praicipiiata, 289 chlorala, 296 hypochloTosa, 296 phosphorica, 294 Calcii Brmr.idum, 287 Carbonas, 289 Chloridum, 290 Hypophosphis, 292 lodidum, 293 ii?"!"-, 399 Phosphas, 294 Calcined magnesia, 421 Calcium bromatum, 287 carhonicum, 289 chloratum, 290 hypochlorosum, 296 hypophoaphorosum, 292 iodutum, 293 phoiphoricum, 294 sulfuraium, 299 Calcium bromide, 287 carbonate, 289 chloride, 290 hypochlorite, 296 hypopho'phite, 292 iodide, 293 orthophosphate, 294 phosphate, 294 sulphate (as reagent), 32 sulphide, 299 Calomel. 375 Ca/a: cldnrala, 296 chlorinata, 296 eulfurata, 299 Camphor, monobromide of, 300 Camphora monobromata, 300 C.ine-sujrar, volumetric estimation of, 98 Cantharidin, 107, 300 Caviharidinum, 300 Caput moriuum. 361 Carbolic acid, 139 Carbon bisulphide, 301 bisulphuret of, 301 Carbonate of ammonium, 221 bismuth, 273 calcium, 289 iron, 360 Carbonate — iron, saccharated, 340 .lead, 453 lithium, 417 magnesium, 422 potassium, crude, 470 pure, 475 purified, 473 sodium, 543 zinc, 688 Carbonei Bisulphidum, 301 Carboneum suifuratum^ 301 Caustic potash, 486 soda, 550 Centimeter, 79 Cerii Oxalas, 303 Cerium oxalate, 303 Cerium oxalalum, 303 Cerussa, 453 Cliaik, precipitated, 289 Chili saltpetre, 660 Chinidimim, 502 sulfuricum, 503] Chininum, 605 Chinium, 605 bisulfuricum, 516 ferro- cilricum, 348 hydrobromatum, 515 hydrobromicum, 515 hydrochloratum, 518 hydrochloricum, 518 sulfuricum. 520 acidum, 616 tannicum, 523 . valeriamcum, 525 Chinoidin, 304 Chinoidinum, 304 Chloral, 305 alcoholate, 306 hydrate, 305 Chlorali Hydras, 305 Chloralum butylicum, 308 hydratuvi, 305 Chlorate of potassium, 478 sodium, 546 Chloride of ammonium, 223 antimony, solution of, 897 barium, 268 calcium, 290 gold and sodium, 266 iron, 34] platinum (as reagent), 40 sodium, 648 tin (as reagent), 41 zinc, 589 Chlorinated lime, 296 Chlorine water, 251 Chloroform, 308 Chloroformium, 308 Chromic acid, 142 Chromium trioxide, 142 Chrysarobin, 312 INDEX. 615 Chrysarobhmm, 312 Clirysoph.vnic acid, 312 Oinclioua baiks, estinmtion of alkaloids, 507 Cinchonia, 315 sulphate, 317 Chichonidina, 313 Cinchonidinse Sulphas, 314 Cinchonidine, 313 sulphate, 314 Cinchonidinvm, 313 mlfuricum, 314 Cinchonina, 315 Cinc/ioninx Sulphas, 317 Cinchoninum, 315 sulfnrieum, 317 Cinnabar, 386 Cinnabaris, 386 Citrate of bismuth, 270 and ammonium, 272 iron, 343 and ammonium, 345 and quinine, 348 solution of, 403 solution of, 402 and strychnine, 349 litliium, 419 potassium, 479 Citric acid, 144 Cloudiness, 18 Cobaltous nitrate (as reasent), 32 Cochineal (as indicator), 78 Codeia, 318 Codeine, 109, 318 Codeinum, 318 Coffeina, 286 Colfeine, 286 Coffei?ium, 286 Colchicina, 320 •Colchicine, 107, 320 Colchicinum, 320 Common salt, 548 Conchininum, 502 sulfuricum, 503 Conia, 322 Coniina, 322 Coniine, 322 Coniinum, 322 Conquinina, 502 Copper, acetate of, 328 ammonio-sulphate of, 332 oxide of, 329 subacetute of, 328 sulphate of, 330 Corrosive sublimate, 373 Cream of tartar, 465 Creasote, 324 Cremor iariari, 465 Cieosol, 325 Creosote, 324 Creosoium, 324 Cresol, 325 Crela prsenpilata, 289 Cubic centimeter, 79 Cfupri Acetas, 328 Oxidum, 329 Subarelas, 328 Sulphas, 330 Cupric acetate, 328 oxide, 329 sulphate, 330 Otiprum aceticum, 328 ammonialum, 332 oxi^datum, 329 sulfuricum, 332 ammoniatum, 332 Curarina, 333 Curarine, 112, 333 Ciirarinum, 833 Cyanide of mercury, 378 poiassitim, 481 silver, 256 DEC.\NTATION, 18 Determination of boiling-point, 23 melting-point, 23 Dextrose, volumetric estimation of, 97 Diammonio-hydric phosphate, -27 Digitaline. 107, 334 Digitalinvm^ 334 Dinitrosulpliide of iron (as reagent), 32 Distilled water, 2-)4 Disulphide of carbon, 301 Drying precipitates, 21 ELATERINE, 337 Elalerinum, 337 Elementary bodies, their symbols and atomic weights, 603 Emclina, 338 Kmetine, 338 Emelinum, 338 Epsom salt, 423 Ether, 201 acetic, 204 ethylic, 201 nitrous, 571 Ethyl acetate, 204 nitrite, solution of, 571 oxide, 201 Ethylic alcohol, 206 ether, 201 Examination for acids, 61 for bases, 49 preliminary, 44 F ACRICS, examination for arsenic, 134 Fehling's solution (as reagent), 32 Ferri Acetatis, Liquor, 399 Arsenias, 339 Carbonas, 340 saccharatus, 340 616 INDEX. Ferri — C/iloridvm, 341 Cfitras, 343 solution of, 402 et Ammonii Chloridum, 344 ei Ammonii Ciiros, 345 et Ammomi Sulphas, 346 el Ammomi Tartras, 346 et Potassii Tariraa, 347 et Quininx Citras, 348 solution of, 848 et Strychnivfe Citras, 349 ferroci/anidum. 350 Hypophosphis. 352 Jodidum, 352 Lactas, 353 Oxalas, 355 Oxidum hydratnm.^ 356 Perchloridum-, 341 PernitTaiis, Liquor, 404 Peroxidum hydralitm, 356 Phosphas, 357 - Pyrophosphas, 359 e/ SoAV CViros, 359 Suhcarhonas, 360 Sulphas, 361 Sulphatis, Liquor, 405 Valerianas, 363 Ferric acetate, solution of, 399 arseniate, 339 chloride, 341 citrate, 343 solution of, 402 dinitrosulpbide (iis reagent), 32 ferrocyanide, 350 hydrate, 356 hypophosphite, 352 nitrate, solution of, 404 pyrophosphate, 359 sulphate, solution of, 405 valei'ianate, 363 Ferrioyanide of potassium (as reagent), 40 Ferrocyanide of iron, 350 of potassium, 485 Ferroso-ferric arseniate, 339 Ferrous cai-bonate, 340 sacoharated, 340 iodide, 352 lactate, 353 oxalate, 355 sulphate, 301 Ferrum, 364 arsenicum, 339 carbonicum, 360 sttccharatum, 340 chloriduTn, 341 citricum, 348 ammoniatum, 345 et ammonium chloratum, 344 et ammonium citricum, 345 et ammonium sulfuricum, 346 et ammonium tartaricum, 346 Ferrum — et chininum citricum, 348 et potassium tartaricum, 347 et strychninum citricum, 349 ferrocyanatum, 350 hypophosphoTosum, 352 iodatum, 352 lacticum, 353 ozy datum hydricum fuscum, 356 oxydulato-oxydatumphosplioricum,S67 phosphoricum, 357 pulveralum, 365 pyrophosphoricum, 359 CW7W natrio ciirico, 359 reductum, 368 sesqui-chloratum, 341 snbcarbonicum, 360 sulfuiicum, 361 tartaricum ammoniatum, 346 valerianicum, 363 Filtration, 18 Fleitmann's test for arsenic, 36 Float, Erdmann's, 74 Flares bemoes. 1 35 sulfuris, 581 zi'nci, 591 Flour, detection of alum in, 214 Flowers of sulphur, 581 Fluid measures, conversion of United States, into metric, 606 Fusel oil, 210 GALLIC acid, 147 Gelatin (as reagent), 33 Gelatinized starch (as reagent), 41 Glacial acetic acid, 122 phosphoric acid, 174 Glass tubing, bending of, 25 Glauber's salt, 567 Glucose, volumetric estimation of, 97 Glycerin, 370 Glycerina, 370 Gtycerivum, 370 GlycocoU, 136 Golden sulphur, 240 Grape-sugar, volumetric estimation of, 97 Green iodide of mercury, 381 Guaiacol, 325 Guaranine, 286 TJEPAR sulfuris, 459 Uydrargyri Bichloridum, 373 Chloridum corrosivum, 373 mite, 875 Cyanidum, 878 lodidum- rubrum, 379 viride, 381 Oxidum flavum, 382 rubrum, 382 Perchloridum, 373 INDEX. 617 Eyirargyri — Subchloridum, 375 Subnitras, 385 Subsufphas Jlavus, 386 Hydrargyrum, 388 amidato-bichloraium, 390 ammoniaiitm bichlorutuiit, 390 bickloraliim, 373 biiodaium, 379 cidoratum, 375 corrosivtim svbUmalum, 373 cyanatttm, 378 iodaluni, 381 rubrum, 379 miricuin oxydulatum, 385 oxy datum flavam, 382 rubrum, 382 prsecipitatum album, 390 sulfuratam rubrum, 386 sulfuricuvi fiavum, 236 Hydnite of aluminium, 214 nmmonium, solution of, 215 barium (.as reagent), 31 calcium, solution of, 399 chloral, 305 oxide of iron, 356 potassium, 486 sodium, 412 Hydviodic acid, 148 Hjdrobromate of quinine, 515 Hydrobromio acid, 150 Ilydrochloriite of apomovpliine, 245 morphine. 433 quinine, 518 Hydrochloric acid, 153 Hydrocyanic acid, 159 detection in forensic research,! 61 estimation of, in ethereal oil or bitter almonds, 443 Hydrogen (nascent), 33 sulphide, 37 water of (as reagent), 38 sulphuretted (as reagent), 38 I/yoscyamin:£ Sulphas, 392 Hyoscyamine sulphate, 392 Hyoscyaminum suljuricum, 392 Hypochlorite of calcium, 296 Hypophosphite of calcium, 292 iron, 252 lime, 292 potassium, 490 sodium, 552 Hypophosphorous acid, 163 Hyposulphite of sodium, 554 INDIGO solution (as reagent), 39 Iodide of ammonium, 225 arsenic, 263 cadmium, 284 calcium, 293 Iodide of — iron, 352 lead, 455 mercury, green, 379 red, 381 potassium, 491 silver, 257 sodium, 556 sulphur, 583 zinc, 590 Iodine, 393 water (as reagent), 39 lodinized potassium iodide (as reagent), 39 lodinxim, 393 Iodoform, 392 lodoformium, 392 Iron, 364 acetate of, solution of, 399 alum, 346 and ammonium chloride, 344 and ammonium citrate, 34S and ammonium sulphate, 346 and ammonium tartrate, 346 and potas.sium tartrate, 347 and quinine citrate, 348 and strychnine citrate, 349 arseniate of. 339 carbonate of, 340 chloride of, 341 citrate of, 343 ferrocyanide of, 350 hydrated oxide of, 356 bypophosphite of, 352 iodide of, 352 lactate of, 353 nitrate of, solution of, 404 oxalate of, 355 phosphate of, 357 powdered, 365 pyrophosphate of, 357 with sodium citrate, 359 saccharated carbonate of, 340 subcarbonate of, 360 sulphate of, 361 valerianate of, 363 K ALIXJM aceticum., 460 bicarbonicum, 462 bichromicum, 464 bitartaricum, 466 bromalum, 467 carbonicum crudum. 470 depuratum, 473 pur am, 475 causticum^ 486 chloricum, 478 diTOTiiicum rubrum^ 462 cyanafum, 481 feiTOcyanatum^ 485 618 INDEX. Kaliwm — kydricum, 486 hypermanganicum, 497 hypophospkorosum, 490 zodatum, 491 niiricum^ 494 sulfuricuin, 498 sulfurosum, 499 tarlaricuvi, 501 Kermes mineraie, 242 Kreosotum, 374 7" AC sulfuris, 578 -'-' Liio sulphur, 578 Lactate of iron, 535 Liiotic acid, 164 Lactose, volumetric estimsition of, 97 Lead, acetate of, 452 carbonate of, 453 iodide of, 455 nitrate of, 456 oxide of, 457 red oxide of, 458 subacetate of, solution of, 407 sugar of, 452 white, 453 Lime, carbonate of, 289 chlorinated, 290 hypophosphite of, 292 iodide of, 293 phosphate of, 294 water, 399 Liquor Ammoniie, 245 Anwionii acetatis, 397 caustici, 245 Dzondii, 246 Antimonii ckloridi, 397 C'alcis, 399 Clilori, 251 Ferri aeetici, 399 chlorati, 401 ckloridi, 401 citratis, 402 et Quininie citratis, 403 et Quimnse citratis, 403 nitralis, 404 pernitratis, 404 sesquiclilorati, 401 sulfurici oxydati, 405 sulphalis, 405 Hydrargyri niiraiis, 400 nitrici oxydati, 406 oxydulali, 385 JBTaZu arsenicosi, 410 caustici, 408 Natrii caustici, 412 hypochlorosi, 414 Potasxie, 408 Potassii arseniiis, 410 hydratis, 408 ;S'orfa;, 412 Liquor Sodse — chloratx, 414 chlorinatse, 414 Sorf?Y hydratis, 4 1 2 S/j'Sm chlorati, 397 Liter fiasks and jars, 71 Litharge, 457 Lithargyrum, 457 LHhii Benzoas, 415 Bromidum, 410 Carbonas, 417 Ci^ras, 419 Salicylas, 420 Lithium benzoate, 415 bromide, 416 carbonate, 417 citrate, 419 salicylate. 420 Lithium benzoicum, 415 bromatum, 416 carbonicum, 417 citricum, 419 salicylicum, 420 Litmus papers, 42 solution of (as reagent), 41 Lunar caustic, 258 MAGNESIA, 421 calcined, 421 Magnesia alba, 422 carlonica, 422 M.ite, 421 Magnesii Carbonas, 422 UxiduTii, 421 Sulphas, 423 SuZpAw, 426 Magnei>ium carbonate, 422 mixture (as reagent), 39 oxide, 421 sulphate, 423 sulphite, 426 Magnesiinn carbonicum, 422 oxydatum, 421 sulfuricum, 423 sulfurosum, 426 Manganese, black oxide of, 426 dioxide of,' 426 Mangani Oxidum nigrum, 426 Sulphas, 429 Mangaiious sulphate. 429 Manganam htjperoxydatum, 426 oxydatum nativum, 426 sulfuricum, 429 Melting point, determination of, 23 Mercur-ammonium chloride, 390 Mercuric chloride, 373 cyanide, 378 iodide, 379 with' potassium iodide (as re- agent), 40 nitrate, solution of, 406 INDEX. 619 Mercuric — oxide, 382 oxycliloride (as reagent), 39 sulphide, 386 Mfrmriiis dulcis^ 375 Mercurous chloride, 375 iodide, 381 nitrate, 385 Mercury, 388 ammoniated, 390 ammonio-chloride of, 390 biniodide of, 379 cyanide of, 378 oxide of, 382 perchloride of, 373 pernitrate, solution of, 406 protoiodide of, 381 subchloride of, 379 subnitrate of, 385 sulphide of, 230 Meta-dioxybenzol, 526 Meta-phosphoric acid, 174 Methenyl iodide, 392 Methyl-propyl-phenol, 583 Methyl-theobromine, 286 Metric measures of capacity, conversion into United States fiuid measures, 606 weights, conversion into troy weights, 61)8 Jlild chloride of mercury, 375 Milk, sugar of, volumetric estimation of,97 of sulphur, 578 Mineral kermes, 242 Minium, 458 Molybdate of sodium (as reagent), 41 Monobromated camphor, 300 Morphia, 111, 430 Morphina, 430 Morphinx Aceias, 432 Jlydrockloras, 433 Murias, 433 Sulphas. 434 Morphine, 111,430 acetate, 432 estimation of, in opium, 435 in tincture of opium, 439 hydrochlorate, 433 sulphate, 434 Morphium, 430 aceticum, 432 hyfirochloricum^ 433 su/furicum, 434 Mucilage of starch (as reagent), 41 Muriatic acid, 153 Mustard, ethereal oil of, 443 NARCEINE, 111 Narcotine, 110 Natnloin, 211 Natrio kalium tartaricum, 483 Natrium aceticum. 530 arsenicum, 532 bcnzoicum, 533 biboricum^ 538 biearbonicum, 534 bisulfurosum, 537 bromatum, 539 carbonicum, 543 causticum, 550 chlorulum, 548 chloricum, 546 hydricum, 550 hypophosphorosum^ 552 hyposulfurosum, 554 iodatum, 556 nitricum, 560 pkospkoricum, 561 pyrophosphoricum, oG4 salicylicum^ 565 santoninicum, 566 subsulfurosum, 554 sulfocarboUcum, 570 sulfopbenoliauu, 570 sul/uriciim, 567 sulfurosum, 569 Nessler's rengent, 40 Neutralization, volumetric analysis by, 80 Nicotina, 439 Nicotine, 109, 439 Nicolinum, 439 Nitrate of ammonium, 226 bismuth, 276 iron, solution of, 404 lead, 456 mercury, 385, 406 potassium, 494 silver, 258 sodium, 560 strychnine, 576 Nitre, 494 sweet spirit of, 571 Nitric acid, 165 Nitrite of amyl, 230 OIL of bitter almonds, 440 mustard, 443 Oleic acid, 171 Oleum amygdaliB lethereum, 410 sinapis lelhereum, 443 Opalescence, 18 Opium, morphioraetric assay of, 435 Ortho-oxybenzoic acid, 181 Ortho-phosphoric acid, 174 Oxalate of cerium, 303 iron, 355 Oxalic acid, 172 standard solution of, 82 Oxidation, volumetric analysis by, 88 Oxide of antimony, 235 copper, 329 iron, 356 620 INDEX. Oxide of — lead, 457 magnesium, 421 mjingaTiese, 426 mercury, 382 silver, 261 zinc, 591 Oxyohlorlde of mercury (as reagent), 39 Oxy-propionio acid, 164 PAPAVERINE, 110 Paper, alkanet, 42 litmus, 42 plumbic acetate, 42 turmeric, 42 Pearlash, 470 purified, 473 Pentasulphide of antimony, 240 Perobloride of iron, 841 solution of, 401 of mercury, 373 Permanganate of potassium, 497 Pernitrate of iron, solution of, 404 mercury, solution of, 406 Peroxyhydrate of iron, 356 Persulphate of iron, solution of, 405 Petroleum ether, 269 Phenio acid, 139 Phenolphtalein (as indicator), 78 Phenylic alcohol, 139 Phosphate of ammonium, 227 calcium, 294 iron, 357 lime, 294 sodium, 561 Phosphide of zinc, 593 Phosphoric acid, 174 Phosphorous salt (as reagent), 39 Phosphorus, 445 Physostigfninse Salicylas, 44.9 Physostigmine, 110 salicylate of, 449 Physosiigminum saticylicunij 449 Picrotoxin, 107, 449 Picrotoxinum, 449 Pilocarpinae Hydrochloras, 451 Pilocarpine hyurochlorate, 451 Pilocarpinum hydrochloricum, 451 Piperina, 451 Piperine, 451 Pipettes, 71 Platinic chloride (as reagent), 40 Plumbi Acetas, 452 Carhonas, 453 lodidum, 455 Nitras, 456 Oxidum, Abl ruhrwn, 458 Subacetatis, Liquor, 407 Subcarbonas, 453 Plumbic acetate, 452 Plumbic — carbonate, 453 iodide, 455 monoxide, 457 nitrate, 456 plumbate, 458 subacetate, solution of, 407 subcarbonate, 453 Plumbum aceticum, 452 carbonicum, 453 iodatum, 455 nitricum, 456 oxydatum fuscum, 457 rubrum, 458 Potash, crude, 470 pure, 475 purified, 473 Potassa, 486 solution of, 408 sulphurata, 459 Potassii Acetas, 460 Biearbonas, 462 Bichromas, 464 Bilartras, 465 Bromidum, 467 Carbonas crudus, 470 depuratus, 473 purus, 475 Chloras, 478 Cyanidum, 481 FerrocyaniduTn, 485 Hydras crudus, 488 purus, 486 Hypopliosphis, 490 lodidum, 491 Nitras, 494 Permanganas, 497 et Sodii Tartras, 483 Sulphas, 498 Sulphidum, 459 Sulphis, 499 Sulphuretum, 459 Tartras, 501 Potassio-antimonious tartrate, 232 Potassio-ferric tartrate, 347 Potassio-raei'curic iodide (as reagent), 40 Potassium acetate, 460 and sodium tartrate, 483 antimoniate (as reagent), 40 arsenite, solution of, 410 bicarbonate, 462 bichromate, 464 standard solution of, 91 bitartrate, 464 bromide, 467 carbonate, crude, 470 pure, 475 purified, 473 chlorate, 478 cyanide, 481 ferricyanide (aa reagent), 40 ferrooyanide, 485 INDEX. 621 Potassium — hydrate, 486 standard solution of, 87 hypophosphite, 490 iodide, 491 mercuric iodide (as reagent), 40 nitrate, 494 permanganate, 497 standard solution of, 89 prussiate, 485 sulphate, 498 sulphide, 459 sulphite, 499 sulphuret, 459 sulpho-cyanide (as reagent), 41 tartrate, 501 Precipitated carbonate of lime, 289 carbonate of zinc, 588 oxide of mercury, 382 phosphate of lime, 294 sulphur, 578 Precipitates, 19, 22 Precipitation, 18 volumetric estimation by, 98 Preliminary examination, 44 Prussic acid, 159 Pyroborate of sodium, 538 Pyrolusite, 426 Pyrophosphate of iron, 359 in scales, 359 with citrate of sodium, 359 of sodium, 564 QUICKSILVER, 388 Quinia, 505 Quinidia, 502 Quinidina, 502 Quinidinse Sulphas, 503 Quinidine, 502 sulphate, 503 Quinina, 505 Quininse Bisulphas, 516 Hydrobromas, 5 1 5 BijdrochloraSj 518 Murias, 518 Sulphas, 520 Tannas, 523 Vahrianas, 525 Quinine, 505 bisulphate, 516 ferric citrate, 348 hydrobromate, 515 hydrochlorate, 618 muriate, 518 sulphate, 520 tannate, 523 valerianate, 525 Quinoiiline, 304 Quinoidinum, 304 REAGENTS and reactions, 26 for alkaloids, 103 Red iodide of mercury, 379 oxide of lead, 458 of mercury, 382 precipitate, 382 sulphide of mercury, 386 Reduction, volumetric analysis by, 1 Reinsch's test for arsenic, 129 Removing precipitates, 20 Resorcin, 526 Resorcinum, 526 Rochelle salt, 483 s ACCHARATED carbonate of iron, 340 Saccharose, volumetric estimation of, 98 23 Sal ammoniacum tartari, 475 Salicin, 527 Salichitin, 527 Salicylate of lithium, 420 physostigmine, 449 sodium, 505 Salicylic acid, 181 Salt, common, 548 of tartar, 475 Saltpetre, 490 Chili, 560 Santonin, 528 Santoninate of sodium, 566 Santoninum, 528 Seignette salt, 483 Sesqui-carbonate of ammonium, 221 Silver, cyanide of, 256 iodide of, 257 nitrate of, 258 oxide of, 261 Sooaloin, 213 Soda, 550 solution of, 412 Soda-lime (as reagent), 41 Soda Acetas, 530 Arsenias, 532 Bemoas, 533 Bicarbonas, 534 Btsulphis, 537 Boras, 538 Bromidum, 539 Carbonas, 543 Ohloras, 546 Chloridum, 548 Hi/dras, 550 Hi/pophosphis, 553 llyposulphis, 554 lodidum, 556 Nitras, 560 I'lwsphas, 561 Phosphis, 561 Fyrophosphas, 564 Salicylas, 565 G22 INDEX. Sodii — Santoninas, 566 Sulpkas, 567 SulphiSy 569 Sulphocarbolas, 570 Sodium acetate, 530 arseniate, 582 benzoate, 533 bicarbonate, 534 bromide, 539 carbonate, 543 chlorate, 546 chlor-aurate, 266 chloride, 548 hydrate, 550 solution of, 412 liypochlorite, 414 hypopbosphite, 552 hyposulphite, 554 standard solution of, 94 iodide, 556 molybdate (as reagent), 41 nitrate, 560 phosphate, 561 phosphite, 561 pyrophosphate, 564 salicylate, 565 santoninate, 566 sulphate, 567 sulphite, 569 sulphooarbolate, 570 tetraphosphate, 564 thiosulphate, 554 Sodium tartaraium, 583 Solution, 17 alcoholic, of ammonia, 246 of ethyl nitrite, 571 ammonium acetate, 397 hydrate, 245 antimonious chloride, 397 calcium hydrate, 399 chloride of iron, 401 chlorinated soda, 414 chlorine, 251 citrate of iron, 402 and quinine, 403 Fehling's (as reagent), 32 ferric acetate, 399 chloride, 401 citrate, 402 and quinine citrate, 403 nitrate, 404 sulphate, 405 indigo (as reagent), 39 litmus (as reagent), 41 mercuric nitrate, 406 mercurous nitrate, 385 pernitrate of iron, 404 of mercury, 406 persulphate of iron, 405 potassa, 408 potassium arsenite, 410 Solution — potassium hydrate, 408 soda, 412 sodium hydrate, 412 hypochlorite, 414 solid bodies, 48 subacetate of lead, 407 triplumbic acetate, 407 Spirit of Mindererus, 397 of nitrous ether, 571 Spiritus, 206 ^theris nitrosi, 571 Ammonii, 246 Nitri dulcis, 571 tiitroso- xthereus, 571 Stannous chloride (as reagent), 41 Stibii chlorati, Liquor, 397 Stibium oxydatum, 235 sulfuraium aurantiacum, 240 nigrum, 237 rubeum, 242 Sti'ychnia, 574 Strychnina, 574 Strychninae Nitras, 576 Sulphas, 578 Strychnine, 109, 574 ferric citrate, 349 nitrate of, 576 sulphate of, 578 StrycJinium, 574 ferro-citricum, 349 nitricum, 576 sulfuricum, 578 Subacetate of copper, 328 lead, 407 Subcarbonate of bismuth, 273 lead, 453 Subchloride of mercury, 375 Sublimed sulphur, 581 Subnitrate of bismuth, 276 mercury, 385 Subsulphate of mercury, 386 Succinic acid, 182 Sugar of lead, 452 Sugars, volumetric estimation of, 9f Sulphate of aluminium, 216 ammonium, 228 atropine, 265 cadmium, 285 cinchonidine, 314 cinchonine, 317 conquinine, 503 copper, 330 hyoscyamine, 392 iron, 361 and ammonium, 346 magnesium, 423 manganese, 429 mercury, 386 morphine, 434 potassium, 498 quiuidine, 503 INDEX. 623 Sulphate of— quinine, 520 sodium, 567 strychnine, 578 zinc, 594 Sulphide of antimony, 237 hydrogen, 37 mercury, 386 potassium, 459 ■Sulphite of magnesium, 426 potassium, 499 sodium, 569 Sulphocarbolate of sodium, 570 zinc, 597 Sulphocyanide of potassium (as reagent), 41 Sulphophenylate of sodium, 570 zinc, 597 Sulphur, flowers of, 581 golden, 240 iodide of, 583 precipitated, 578 sublimed, 581 Sulphur auratum aniimonii, 240 depuratum, 581 iodatum, 583 latum, 581 prsecipitatum, 578 sublimatum, 581 Sulphurated antimony, 242 lime, 299 potassa, 459 Sulphuret of potassium, 459 Sulphuretted hydrogen, 37 Sulphuric acid, 184 Sulphurous acid, 190 Sweet spirit of nitre, 571 Syrupus Ferri iodidi, 353 11ANNATE of quinine, 523 Tannic acid, 192 Tannin, 192 Tartar, cream of, 4C5 emetic, 232 Tartarated antimony, 232 Tartaric acid, 195 Tartarus depuratus, 465 natronalus, 483 stibiatus, 232 Tartrate of antimony and potassium, 232 iron and ammonium, 346 and potassium, 347 potassium, 501 and antimony, 232 and sodium, 483 Teriodide of formyl, 392 Tersulphate of iron, solution of, 405 Test, bettendorf's, for arsenic, 130 Fleitmann's, for arsenic, 36 Marsh's, for arsenic. 33, 129 Reinsoh's, for arsenic, 129 Test-papers, 41 Test-solutions, 29 Tests, chemical, 43 Thebaine. 110 Theine, 286 Thermometric tables, 604 Thiosulphate of sodium, 554 Thymol, 583 T/ti/molum, 583 Tincture of opium, morphiometrio assay of, 439 Triatomic propenyl alcohol, 370 Tribasic ammonium phosphate, 227 calcium phosphate, 294 sodium phosphate, 561 Triplumbio tetroxide, 458 Trisulphide of antimony, 237 Troy weights, 79 conversion of, into metric weights, 608 Turbidity, 18 Turmeric paper, 42 solution (as reagent), 42 Turpethum minerale, 386 VALERIANATE of ammonium, 229 bismuth, 277 iron, 363 quinine, 525 zinc, 598 Valerianic acid, 197 Veratria, 584 V'eratrijia, 584 Veratrine, 109, 584 Verdigris, 328 Vermilion, 386 Vinegar, 117 Vitriol, blue, 330 white, 594 Volatile oil of bitter almonds, 440 mustard, 443 Volumetric analysis, 30 WALL-PAPER, examination for arse- nic, 134 Washing bottle, 19 precipitates, 19 Water, bromine (as reagent), 32 chlorine, 251 distilled, 254 lime, 399 of ammonia, 245 of bitter almonds, 249 Weighing, precipitates, 22 Weights, conversion of metric into troy, 608 conversion of troy into metric, 609 table of atomic, 603 White arsenic, 126 lead, 453 precipitate, 390 624 INDEX. White- vitriol, 594 Wine, estimation of glycerin in, 372 Wood-tar creasote, 324 YELLOW iodide of mercury, 381 oxide of mercury, 382 prussiiite of potassium, 485 subsulphate of mercury, 386 ZINC ncetate, 586 bromide, 587 carbonate, 588 chloride, 589 iodide, 590 oxide, 591 phosphide, 593 sulphate, 594 sulphocarbolate, 597 sulphophenylate, 597 valerianate, 598 Zinci Acelas, 586 Bromidum, 587 Carbonas prsecipitalus, 58 Chloridum, 589 lodidum, 590 Oxidutn, 591 Phosphidum, 593 Sidphas, 594 Sulphocarbolas, 697 Sulphophenylas, 597 ValerianaSf 598 Zincufn aceticuvij 586 bromatum, 587 carbonicum, 588 chloratum^ 589 iodatum^ 590 oxy datum, 591 phosphoratum, 593 sulfocarbolicum, 597 sul/ophenylicum, 597 sulfuricum, 594 valeriaiiicwu, 598 THE END. LEA BROTHERS & CO.'S {Late HENRY C. LEA'S SON & CO.) CLASSIFIED CATALOGUE OF MEDICAL AND SURGICAL PUBLICATIONS. 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Where access to bookstores is not convenient, books will be sent by mail postpaid on receipt of the price, and as the limit of mailable weight has been removed, no difficulty will be experienced in obtaining through the post-office any work in this cata- logue. No risks, however, are assumed either on the money or on the books, and no pub- lications but our own are supplied, so that gentlemen wiU in most cases find it more con- venient to deal with the nearest bookseller. LEA BKOTHEES & CO. Nob. 706 and 708 Sausom St., Philadelphia, September, 1885. PROSPECTUS FOR 3.88S. A WEEKLY MEDICAL JOURNAL. SUBSCRIPTION" RATES. The MedicaIj Nkws . . . . . . . FiveDollars. The Ambeican Joitbnal op the Medical Sciencbs . FiveDollars. COMMUTATION RATES. The Medical News 1 Nine Dollars per The American Joubkal op the Medicai Sciences j annum, in advance. THE MEDICAL NEWS. •A National Weekly Medical Periodical, containing 38 to 32 Quarto Pag-es of Reading Matter in Each Issue. The Medical News endeavors to render efficient assistance in the daily work of the practising physician, surgeon and specialist. Every department of medical science finds adequate representation in its columns, and its plan and arrangement are well calculated to suit the convenience and secure the comfort of its readers. In the 2 Lea Brothers & Co.'s Periodicals — Medical Jfews, Am. Journal. THE MEDICAL NEWS-WEEKLY. (Continued from first pj.g3.) Original Department its columns are replete with articles of the highest practical value ; its Hospital Eeports reflect the modes of treatment adopted in the most celebrated hospitals of the globe, and its Department of Progress contains judicious excerpts and translations from all the leading medical periodicals of the world. The Editorial Articles are from the pens of a large and able Editorial Staff, and are everywhere conceded to be the most instructive and scholarly productions of their class in the country. Maintaining a large corps of qualified correspondents in all the medical centres of both hemispheres. The News is in early receipt, by cable, telegraph and mail, of intelligence from all quarters. It thus unites the energy of a newspaper with the elaboration of a scientific magazine. Its reputation for enterprise in the past is the best guarantee for the future that nothing will be left undone to render it a faith- ful counsellor and indispensable assistant to every professional man in active practice. THE AMERICAN JOURNAL of the MEDICAL SCIENCES, Edited by I. MINIS HAYS, A. M., M. D., Is published Quarterly, on the first days of January, April, July and October, each Number containing' over Three Hundred Octavo Pages, fully Illustrated. In his contribution to "A Century of American Medicine,'' published in 1876, Dr. John S. Billings, U. S. A., Librarian of the National Medical Library, Washington, thus graphically outlines the character and services of The Americait Joubnai/ — "The ninety-seven volumes of this Journal need no eulogy. They contain many original papers of the highest value ; nearly all the real criticisms and reviews which we possess ; and such carefully prepared summaries of the progress of medical science, and abstracts and notices of foreign works, that from this file alone, were all other productions of the press for the last fifty years destroyed, it would be possible to reproduce the great majority of the real contributions of the world to medical science during that period." This opinion of a man pre-eminently qualified to judge is corroborated by the great circle of readers of the Journal, which includes the thinkers of the profession in all parts of the world. During the coming year the features of the Journal which have given unalloyed satisfaction to two generations of medical men, will be maintained in their vigorous maturity. The Original Department will consist of elaborate and richly illustrated articles from the pens of the most eminent members of the profession in all parts of the country and England. The Review Department will maintain its well-earned reputation for discernment and impartiality, and will contain elaborate reviews of new works and topics of the day, and numerous analytical and bibliographical notices by competent writers. Following these comes the Quarterly Summary of Improvements and Dis- coveries in the Medical Sciences, which, being a classified and arranged condensation of important articles appearing in the chief nledical journals of the world, furnishes a compact digest of medical progress abroad and at home. 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Lea Brothers & Co.'s Publications — Period., Compends, Manuals. 3 ■ The safest mode of remittance is by bank check or postal money order, drawn to the order of the undersigned ; where these are not accessible, remittances for subscrip- tions may be made at the risk of the publishers by forwarding in registered letters. Address, Lea Beothers & Co., Nos. 706 and 708 Sansom St., Philadelphia. *^* Communications to both these periodicals are invited irom gentlemen in all parts of the country. Original articles contributed exclusively to either periodical are liberally paid for upon publication. When necessary to elucidate the text, illustrations wiU. be fur- nished without cost to the author. All letters pertaining to the Editorial Department of The Medical News and The American Jotirnal oe the Medical Sciences should be addressed to the Editorial Offices, 1004 Walnut Street, Philadelphia. AH letters pertaining to the Business Department of these journals should be addressed excbmvely to Lea Brothers & Co., 706 and 708 Sansom Street, Philadelphia. SAMTSSOItlVIl, MENJRY, A. M., M. D., LL. D., Lately Professor of Hygiene in the University of Pennsylvania. A Conspectus of the Medical Sciences ; Containing Handbooks on Anatomy, Physiology, (Siemistry, Materia Medica, Practice of Medicine, Surgery and Obstetrics. Second edition, thoroughly revised and greatly improved. In one large royal 12mo. volume of 1028 pages, with 477 illustrations. Ooth, $4.25 ; leather, |5.00. The object of this manual is to afford a conven- ient work of reference to students during the brief moments at their command while in attendance upon medical lectures. It is a favorable sign that it has been found necessary, in a short space of time, to issue a new and carefully revised edition. The illustrations are very numerous and unusu- ally clear, and each part seems to have received its due share of attention. Vfe can conceive such a work to be useful, not only to students, but to practitioners as well. It reflects credit upon the industry and energy of its able editor. — Boston Medical arid Surqical Journalf Sept. 3. 1874. "We can say, with the strictest truth, that it is the best work of the kind with which we are acquaint- ed. It embodies in a condensed form all recent contributions to practical medicine, and is there- fore useful to every busy practitioner throughout our country, besides being admirably adapted to the use of students of medicine. The book Is faithftilly and ably executed. — Charleston Medical Journal, April, 1875. SIVDMNTS' SBJRIES OF MANTfALS. A Series of Fifteen Manuals, for the use of Students and Practitioners of Medicine and Surgery, written by eminent Teachers or Examiners, and issued in pocket-size 12mo. volumes of 300-540 pages, richly illustrated and at a low price. The following vol- umes are now ready: Bell's Gmwparative Physiology and Anatomy, Gould's Surgical Diagnosis, Kobertson's Physiological Physics, Brtjcb's Materia Medica and Therapeutics, Pov?er's Human Physiology, Clarke and Lockwood's Dissectorsf Manual, Kalpb's Clinical Chemistry, Treves' Surgical Applied Anatomy, Pepper's Surgical Pathology, and Kleiu's Elements of Histology. The following are in press : Bellamy's Operative Surgery, Pepper's Forensic Medicine, and Cuenow's Medical Applied Anatomy. For separate notices see index on laat page. SERIES OF CLINICAL MAJffUALS. In arranging for this Series it has been the design of the publishers to provide the profession with a collection of authoritative monographs on important clinical subjects in a cheap and portable form. The volumes will contain about 550 pages and will be freely illustrated by chromo-lithographs and woodcuts. The following volumes are just ready: Btjtlin on the Tongue; Treves on Intestinal Obstruction; and Savage on Imanity and Allied Neuroses; The following are in active preparation: Hutchinson on Syphilis; Bryant on the Breast; Morris on Surgical Diseases of the Kidney; Broadbent on the Pulse; Owen on Surgical Diseases of Children; Lucas on Diseases of the Urethra; Marsh on Diseases of the Joints, Pick on Fractures and Dislocations, and Ball on the Rectum cmd Anus. For separate notices see index on last page. NEILL, JOHN, M. D., cmd SMITH, F. C, M. D., Late Swrgeon to the Perma. Hospital. Prof, of the Institutes of Med. in the Vrniv. of Prnna. An Analytical Compendium of the Various Branches of Medical Science, for the use and examination of Students. A new edition, revised and improved. In onelarge royal 12mo. volume of 974 pages, with 374 woodcuts. Cloth, $4 ; leather, $4.75. LUDLOW, J. L., M. H., Consulting Physician to the Philadel/phia Hospital, etc A Manual of Examinations upon Anatomy, Physiol^, Surgery, Practice of Medicine, Obstetrics, Materia Medica, Chemistry, Pharmacy and Therapeutics. To which is added a Medical Formulary. 3d edition, thoroughly revised, and greatly enlarged. In one 12mo. volume of 816 pages, with 370 illustrations. Cloth, $3.25 ; leather, $3.75. The arrangement of this volume in the form of question and answer renders it espe- cially suitable for the office examination of students, and for those preparing for graduation. Lea Brothers & Co.'s Publications — jL»it;i,iuu»j.ico. jyUNGLISON, ROBLBY, M.D., Late Professor of Institutes of Medicine in the Jefferson Medical College of Philadelphia. MUDICAL LEXICOK; A Dictionary of Medical Science : Containing a concise Explanation of the various Subjects and Terms of Anatomy, Physiology, Pathol- ogy, Hygiene, Therapeutics, Pharmacology, Pharmacy, Surgery, Obstetrics, Medical Juris- prudence and Dentistry, Notices of Climate and of Mineral Waters, Formulae for Officinal, Empirical and Dietetic Preparations, with the Accentuation and Etymology of the Terms, and the French and other Synonymes, so as to constitute a French as well as an English Medical Lexicon. Edited by Kichaud J. Ditnglison, M. D. In one very large and handsome royal octavo volume of 1139 pages. Cloth, $6.60; leather, raised bands, $7.50; very handsome half Bussia, raised bands, $8. The object of the author, from the outset, has not been to make the work a mere leii- con or dictionary of terms, but to afford under each word a condensed view of its various medical relations, and thus to render the work an epitome of the existing condition of medical science. Starting with this view, the immense demand which has existed for the work has enabled him, in repeated revisions, to augment its completeness and usefulness, until at length it has attained the position of a recognized and standard authority wherever the language is spoken. Special pains have been taken in the preparation of the present edition to maintain this enviable reputation. The additions to the vocabulary are more numerous than in any previous revision, and particular attention has been bestowed on the accentuation, which will be found marked on every word. The typographical arrangement has been greatly improved, rendering reference much more easy, and every care has been taken with the mechanical execution. The volume now contains the matter of at least four ordinary octavos. A book of which every American ought to be proud. When the learned author of the work passed away, probably all of us feared lest the book should not maintain its place in the advancing science whose terms it defines. Fortunately, Dr. Bichard J. Dunglison, having assisted his father in the revision of several editions of the work, and having been, therefore, trained in the methods and imbued with the spirit of the book, has been able to edit it as a work of the kind should be edited — to carry it on steadily, without jar or inter- ruption, along the grooves of thought it has trav- elled during it-s lifetime. To show the magnitude of the task which Br. Dunglison has assumed and carried through, it is only necessary to state that more than six thousand new subjects have been added in the present edition. — Philadelphia Medical Times^ Jan. 3, 1874. About the first book purchased by the medical student is the Medical Dictionary. The lexicon explanatory of technical terms is simply a sine qua non. In a science so extensive and with such col- laterals as medicine, it Is as much a necessity also to the practising physician. To meet the wants of students and most physicians the dictionary must be condensed while comprehensive, and practical while perspicacious. It was because Dunglison's met these indications that it became at once the dictionary of general use wherever medicine was studied m the English language. In no former revision have the alterations and additions been so great. The chief terms have been set in black letter, while the derivatives follow in small caps; an arrangement which greatly facilitates reference. — Cincinnati I^ancet ana Clinic^ Jan. 10, 1874. As a standard work of reference Dunglison's work has been well known for about forty years, and needs no words of praise on our part to recom- mend it to the members of the medical, and like- wise of the pharmaceutical, profession. The latter especially are in need of a work which gives ready and reliable information on thousands of subjects and terms which they are liable to encounter in pursuing their daily vocations, but with which they cannot be expected to be familiar. The work before us fully supplies this want. — American Jour- nal of Pharmacy t Feb. 1874. Particular care has been devoted to derivation and accentuation of terms. With regard to the latter, indeed, the present edition may be consid- ered a complete "Pronouncing Dictionary of Medical Science." It is perhaps the most reliable work published for the busy practitioner, as it con- tains information upon every medical subject, in a form for ready access, and with a brevity as ad- mirable as it is pTactic2kL— Southern Medical Record. Feb. 1874. A valuable dictionary of the terms employed in medicine and the allied sciences, and of the relar tions of the subjects treated under each head. It well deserves the authority and popularity it has obtained.— £n(i5A Med, Jour.^ Oct. 31, 1874. Few works of this class exhibit a grander monu- ment of patient research and of scientific lore.— London Lancet^ May 13, 1875. Dunglison's Dictionary is incalculably valuable, and indispensable to every practitioner of medi- cine, pharmacist and dentist. — Western Lancet March, 1874. It has the rare merit that it certainly has no rival in the English language for accuracy and extent of references. — London Medical Gazette. HOBLYW, BICMAMJD It., M. D. A Dictionary of the Terms Used in Medicine and the Collateral Sciences. Eevised, with numerous additions, by Isaac BLays, M. B., late editor of The American Journal of the Medical Sciences. In one large royal 12mo. volume of 520 double-columned pages. Cloth, $1.50 ; leather, $2.00. It is the best book of definitions we have, and ought always to be upon the student's table— Southern Medical and Surgical Journal. BODWBLL, G. F., F. B. A. 8., F. C. S., Lecturer on Natural Sciejice at Clifton College, England. A Dictionary of Science : Comprising Astronomy, Chemistry, Dynamics, Elec- tricity, Heat, Hydrodynamics, Hydrostatics, Light, Magnetism, Mechanics, Meteorology, Pneumatics, Sound and Statics. Contributed by J. T. Bottomley, M. A., F. C. S William Crookes, F.K.S., F.C.S., Frederick Guthrie, B.A., Ph.D., E. A. Proctor, B.A., F.R.A.S., G. F. Eodwell, Editor, Charles Tomlinson, F.E.S., F.C.S., and Eichard Wornell, M.A., B.Sc. Preceded by an Essay on the History of the Physical Sciences. In one handsome octavo volume of 702 pages, with 14.^ illnstrations. Cloth. So.OO. Lea Beothers & Co.'s Publications — Anatomy. GMAY, HBNBT, F. JB. S., Lecturer on Anatomy at St. George's Hospital, London. Anatomy, Descriptive and Surgical. • The Drawings bjH. V. Caster, M. D., and Dr. Westmacott. The dissections jointly by the Author and Dr. Carter. With an Introduction on General Anatomy and Development by T. Holmes, M. A., Surgeon lo St. George's Hospital. Edited by T. Pickering Pick, F. E. C. S., Surgeon to and Lecturer on Anatomy at St. George's Hospital, London, Examiner in Anatomy, Eoyal College of Surgeons of England. A new American from the tenth enlarged and improved London edition. To which is added the second American from the latest English edition ot Landmarks, Medical and Surgical, by Luther Holden, F. R. U.S., author of " Human Osteology," " A Manual of Dissections," etc. In one imperial octavo volume of 1023 pages, with 564 large and elaborate engravings on wood. Cloth, $6.00 ; leather, $7.00 ; very handsome half Eussia, raised bands, $7.50. This work covers a more extended range of subjects than is customary in the ordinary text-boolcs, giving not only the details necessary for the student, but also the application to those details to the practice of medicine and surgery. It thus forms both a guide for the learner and an admirable work of reference for the active practitioner. The engravings form a special feature in the work, many of them being the size of nature, nearly all original, and having the names of the various parts printed on the body of the cut, in place of figures of reference with descriptions at the foot. They thus form a complete and splendid series, which will greatly assist the student in forming a clear idea of Anatomy, and will also serve to refresh the memory of those who may find in the exigencies of practice the necessity of recalling the details c^ the dissecting-room. Combining, as it does, a complete Atlas of Anatomy with a thorough treatise on systematic, descriptive and applied Anatomy, the work will be found of great service to all physicians who receive students in their offices, relieving both preceptor and pupil of much labor in laying the groundwork of a thorough medical education. Landmarks, Medical and SurgicaZ, by the distinguished Anatomist, Mr. Luther Holden, has been appended to the present edition as it was to the previous one. This work gives in a clear, condensed and systematic way all the information by which the practitioner can determine from the external surface of the body the position of internal parts. Thus complete, the work, it is believed, will furnish all the assistance that can be rendered by type and illustration in anatomical study. This well-known work comes to us as the latest American from the tenth English edition. As its title indicates, it has passed through many hands and has received many additions and revisions. The work is not susceptible of more improvement. Taking it all in all, its size, manner of make-up, its character and illustrations, its general accur- acy of description, its practical aim, and its per- spicuity of style, it is the Anatomy best adapted to the wants of the student and practitioner. — Medical Record, Sept. 15, 18S3. There is probably no work used so universally by physicians and medical students as this one. It is deserving of the confidence that they repose in it. If the present edition is compared with that issued two yeara ago, one will readily see how much it has been improved in that time. Many pages have been added to the text, especially in those parts that treat of histology, and many new cuts liave been introduced and old ones modified. — Journal of the American Medical Association, Sept. 1, 1883. Also tor sale sepabate — HOLDEW, LTJTHBB, F. B. C. S., Surgeon to St. Bartholomew's and the Foundling Hospitals, London. Landmarks, Medical and Surgical. Second American from the latest Tevised English edition, with additions by W. W. Keen, M. D., Professor of Artistic Anatomy in the Pennsylvania Academy of the Fine Arts, formerly Lecturer on Anatomy in the Phila- delphia School of Anatomy. In one handsome 12mo. voliune of 148 pages. Cloth, $1.00. This little book is all that ean be desired within its scope, and its contents will be found simply in- valuable to the young surgeon or physician, since they bring before hin:i such data as he requires at every examination of a patient. It is written in language so clear and concise that one ought almost to learn it by heart. It teaches diagnosis by external examination, ocular and palpable, of the body, with such anatomical and physiological facts as directly bear on the subject. It is eminently the student's and young practitioner's book. — Fhy- sician and Surgeon, Nov. 18S1. WIZSOIf, ERASMUS, I. JR. 8. A System of Human Anatomy, General and Special. Edited by W. H. GoBRECHT, M. D., Professor of General and Surgical Anatomy in the Medical College of Ohio. In one large and handsome octavo volume of 616 pages, with 397 illustrations. Cloth, $4.00; leather, $5.00. SMITH, M. S., M. D., and SOBNEIt, WM. M., M.I)., Emerit^is Prof, of Surgery in the Univ. of Penna., etc. Late Prof, of Anat. in the Univ. of Penna. An Anatomical Atlas, Illustrative of the Structure of the Human Body. In one large imperial octavo volume of 200 pages, with 634 beautiful figures. Cloth, $4,50. CLFLAND, JOHN, M. D., F. JR. S., Professor of Anatomy and Physiology in Queen^s College, Galway. A Directory for the Dissection of the Human Body. In one 12mo. volume of 178 pages. Cloth, $1.25. 6 Lea Brotheks & Co.'s Publications — Anatomy. AZLHW, SAMRI80N, M. D., Professor q/ Physiology in the University of Pennsylvania. A System of Human Anatomy, Including Its Medical and Surgical Relations. For the use of Practitioners and Students of Medicine. With an Intro- ductory Section on Histology. By E. O. Shakespeaee, M. D., Ophthalmologist to the Philadelphia Hospital. Comprising 813 double-columned quarto pages, with 380 illustrations on 109 fidl page lithographic plates, many of which are in colors, and 241 engravings in the text. In sis Sections, each in a portfolio. Section I. Histology. Section II. Bones and Joints. Section HI. Muscles and Fasci.*;. Section IV. Akteries, Veins and Lymphatics. Section V. Neevous System. Section VI. Organs op Sense, of Digestion and Genito-Ueinaby Oegans, Embetology, Development, Teratology, SuPERnciAL Anatomy, Post-Mortem Examinations, AND General and Clinical Indexes. Price per Section, each in a handsome portfolio, ; $3.50 ; also bound in one volume, cloth 123.00 ; very handsome half Russia, raised bands and open back, $25.00. Far sale by subscription only. Apply to the Publishers. Extract from Introduction. It is the design of this book to present the facts of human anatomy in the manner best suited to the requirements of the student and the practitioner of medicine. The author believes that such a book is needed, inasmuch as no treatise, as far as he knows, contains, in addition to the text descriptive of the subject, a systematic presentation of such anatomical facts as can be applied to practice. A. book which will be at once accurate in statement and concise in terms ; which will be an acceptable expression of the present state of the science of anatomy ; which will exclude nothing that can be made applicable to the medical art, and which will thus embrace all of surgical importance, while omitting nothing of value to clinical medicine, — would appear to have an excuse for existence in a country where most surgeons are general practitioners, and where there are few general practitioners who have no interest in surgery. care, and are simply superb. There is as much of practical application of anatomical points to the every-day wants of the medical clinician as to those of the operating surgeon. In fact, few It is to be considered a study of applied anatomy in its widest sense — a systematic presentation of such anatomical facts as can be applied to the practice of medicine as well as of surgery. Our author is concise, accurate and practical in his statements, and succeeds admirably in infusing an interest into the study of what is generally con- sidered a dry subject. The department of Histol- ogy is treated in a masterly manner, and the ground is travelled over by one thoroughly famil- iar with it. The illustrations are made with great general practitioners will read the work without a feeling of surprised gratification that so many noints, concerning which they may never have thought before are so well presented for their con- sideration. It is a work which is destined to be the best of its kind in any language. — Medical Secord, Nov. 25, 1882. CJjARKJE,W.B.,F.B.C.S. & LOCKWOOJD,C.B.,F.B.C.8. Demonstrators of Anatomy at St. Bartholomew's Hospital Medical School, London. The Dissector's Manual. In one pocket-size 12mo. volume of 396 pages, with 49 illustrations. Limp cloth, red edges, |1.50. Jibst ready. See Stitden^ Series of This isa very excellent manual for the use of the student who desires to learn anatomy. The meth- ods of demonstration seem to us very satisfactory. There are many woodcuts which, for the most part, are good and instructive. The book is neat and convenient. We are glad to recommend it. — Boston Medical amd Surgical Jowrnal^ Jan. 17, 1884. TBBVBS, FBBDEBICK, F. B. C. S., Senior Demonstrator of An/itomy and Assista/nt Surgeon at the London HospitaL Surgical Applied Anatomy. In one pocket-size 12mo. volume of 540 pages, with 61 illustrations. Limp cloth, red edges, $2.00. Just ready. See Students' Series of Manuals, page 3. quickened by daily use as a teacher and practi- tioner, has enabled our author to prepare a work which it would be a most difficult task to excel.— The American Practitioner Feb. 1884. He has produced a work which will command a larger circle of readers than the class for which it was written. This union of a thorough, practical acquaintance with these fundamental branches, CVBNOW, JOSN, M. n., F. B. C. P., Professor of Anatomy at King's College, Physician at King's College Hospital. Medical Applied Anatomy. In one pocket-size 12mo. volume. See Students' Series of Mcmuals, page 3. Preparing. BFBLAMT, BDWABD, F. B. C. S., Senior Assistani^Swgeon to the Chariruj-Oross Hospital, London. The Student's Guide to Surgical Anatomy : Being a Description of the most Important Surgical Eegions of the Human Body, and intended as an Introduction to operative Surgery. In one 12mo. volume of 300 pages, with 50 illustrations. Cloth, $2.25. HABTSHOENB'S HANDBOOK OF ANATOMY AND PHYSIOLOGY. Second edition, revised. In one royal I2mo. volume of 310 pages, with 220 woodcuts. Cloth, $1.76. HORNER'S SPECIAL ANATOMY AND HISTOL- OGY. Eighth edition, extensively revised and modified. In two octavo volumes of 1007 pages, with 320 woodcuts. Cloth, $C.OO. juEA xiKUTMBKB ., Professor of Chemistry and Toxicology m the College of Physicians and Surgeons, Baltimore, and Professor of Chemistry m the Maryland College of Pharmacy. Manual of Chemistry. A Guide to Lectures and Laboratory work for Beginners in Chemistry. A Text-book, specially adapted for Students of Pharmacy and Medicine. In one 8vo. vol. of 410 pp., with 16 woodcuts and 7 plates, mostly of actual deposits, with colors illustrating 56 of the most important chemical reactions. Cloth, $3.00; also without plates, cloth, $2.50. Just ready. This book supplies a want long felt by students of medicine and pharmacy, and is a concise but thorough treatise on the subject. The long expe- rience of the author as a teacher in schools of medicine and pharmacy is conspicuous in the perfect adaptation of the work to the special needs of the student of these branches. The colored plates, beautifully executed, illustrating precipi- tates of various reactions, form a novel and valu- able feature of the book, and cannot fail to be ap- preciated by both student and teacher as a help over the hard places of the science. — Maryland Medical Journal, Nov. 22, 1884. bbmsen; iba, m. d., fji. d., Professor of Chemistry in the Johns Hopkins University, Baltimore. Principles of Theoretical Chemistryj with special reference to the Constitu- tion of Chemical Compounds. Second and revised edition. In one handsome royal 12mo. volume of 240 pages. Cloth, $1.75. Just i The book is a valuable contribution to the chemi- cal literature of instruction. That in so few years a second edition has been called for indicates that many chemical teachers have been found ready to endorse its plan and to adopt its methods. In this edition a considerable proportion of the book has been rewritten, much new matter has been added and the whole has been brought up to date. We earnestly commend this book to every student of chemistry. The high reputation of the author assures its accuracy in all matters of fact, and its judicious conservatism in matters of theory, com- bined with the fulness with which, in a smaU compass, the present attitude of chemical science towards the constitution of compounds is con- sidered, gives it a value much beyond thataccorded to the average text-books of the day. — Am&rican Jowrnal of Science, March, 1884. 10 Lea Beothers & Co.'s Publications — Chemistry. CHARLES, T. CMANSTOUW, M. D., F. C. S., M. S., Formerly Asst. Prof, and D&monst. of Chemistry and Chemical Physics^ Queen^s College, Belfast. The Elements of Physiological and Pathological Chemistry, A Handbook for Medical Students and Practitioners. Containing a general account of Nutrition, Foods and Digestion, and the Chemistry of the Tissues, Organs, Secretions and Excretions of the Body in Health and in Disease. Together with the methods for pre- paring or separating their chief constituents, as also for their examination in detail, and an outline syllabus of a practical course of instruction for students. In one handsome octavo volume of 463 pages, with 38 woodcuts and 1 colored plate. Cloth, $3.50. The work is thoroughly trustworthy;, and in- formed throughout by a genuine scientific spirit. The author deals with the chemistry of the diges- tive secretions in a systematic manner, which leaves nothing to be desired, and in reality sup- plies a want in English literature. The book ap- pears to us to be at once full and systematic, and to show a just appreciation of the relative import- ance of the various subjects dealt with. — British Medical Journal^ November 29, 1884. Dr. Charles'. manual admirably fulfils its inten- tion of giving his readers on the one hand a sum- mary, comprehensive but remarkably compact, of the mass of facts in the sciences which have be- come indispensable to the physician ; and, on the other hand, of a system of practical directions so minute that analyses often considered formida,bIe may be pursued by any intelligent person.— Archives of Medicine, Dec. 1884. MOFFMANW, F., A.M.,JPh.JD., & FOWFB F.B., Fh.D., Public Analyst to the State of New York. Prof, of Anal. Chem. in the Phil. Coll. of Pharmacy. ' A Manual of Chemical Analysis, as applied to the Examination of Medicinal Chemicals and their Preparations. Being a Guide for the Determination of their Identity and Quality, and for the Detection of Impurities and Adulterations. For the use of Pharmacists, Physicians, Druggists and Manufacturing Chemists, and Pharmaceutical and Medical Students. Third edition, entirely rewritten and much enlarged. In one very handsome octavo volume of 621 pages, with 179 illustra.tions. Cloth, $4.25. We congratulate the author on the appearance of the third edition of this work, published for the first time in this country also. It is admirable and the information it undertakes to supply is both extensive and trustworthy. The selection of pro- cesses for determining the purity of the substan- ces of which it treats is excellent and the descrip- tion of them singularly explicit. Moreover, it is exceptionally free from typographical errors. We have no hesitation in recommending it to those who are engaged either in the manufacture or the testing of medicinal chemicals. — London Pharma- ceutical Journal and Transactions, 1883. CLOWFS, FBAJVS:, D. Sc, London, Senior Scienc&- Master at the High School, Newcastle-wnder-Lyme, etc. An Elementary Treatise on Practical Chemistry and Qualitative Inorganic Analysis. Specially adapted for use in the Laboratories of Schools and Colleges and by Beginners. Third American from the fourth and revised English edition. In one very handsome royal 12mo. volume of about 400 pages, with about 50 illustrations. Cloth, $2,50. In a few da/ys. The, 9tyle is clear, the language terse and vigor- ous. Beginning with a list of apparatus necessary for chemical work, he gradually' unfolds the subr ject from its simpler to its more complex divisions. It is the most readable book of the kind we have yet seen, and is without doubt a systematic, intelligible and fully equipped laboratory guide and text book. — Medical Record, July IS, 1885. We may simply repeat the favorable opinion which we expressed after the examination of the previous edition of this work. It is practical in its aims, and accurate and concise in its statements. — American Journal of Pharmacy, August, 1885. BALFE, CHARLES H, M. D., F. R. C. P., Assistant Physician at the London Hospital. Clinical jDhemistry. ^ In one pocket-size 12nio. volume of 314 pages, with 16 illustrations. Limp cloth, red edges, §1.50. This is one of the most instructive little works that we have met with in a long time. The author is a physician and physiologist, as well as a chem- ist, consequently the book is unqualiiiedly prac- tical, telling the physician just what he ought to know, of the applications of chemistry in medi- See Students' Series of Manuals, page 3. cine. Dr. Balfe is thoroughly acquainted with the latest contributions to his science, and it is quite refreshing to find the subject dealt with so clearly and simply, yet in such evident harmony with the modem scientific methods and spirit. — Medical Becordj February 2, 1884. CLASSEN, ALEXANDER, Professor in the Royal Polytechnic School, Aix-la-ChapeUe. Elementary Quantitative Analysis. Translated, with notes and additions, by Edgah F. Smith, Ph. D., Assistant Professor of Chemistry in the Towns Scientific School, University of Penna. In one 12mo. volume of 324 pages, with 36 illust. Cloth, $2.00. and then advancing to the analysis of minerals and such products as are met with in applied chemis- try. It is an indispensable book for students in chemistry. — Boston Jou/rnal of Chemistry, Oct. 1878. It is probably the best manual of an elementary nature extant insomuch as its methods are the best.i*frlt teaches by examples, commencing with single determinations, followed by separations, GREENE, WILLIAM H., M. D., Demonstrator qf Chemistry in the Medical Depa/rtment of the Univ&rsit^ of Pen/nsylvania. A Manual of Medical Chemistry. For the use of Students. Based upon Bow- man's Medical Chemistry. In one 12mo. volume of 310 pages, with 74 illus. Cloth, $1.75. It is a concise manual of three hundred pages, the recognition of compounds due to pathological giving an excellent summary of the best methods conditions. The detection of poisons is treated of analyzing the liquids and solids of the body, both with sufficient fulness for the purpose of thestn- forthe estimation of their normal constituents and dent or practitioner. — Boston JL of C/iem., June, '80. Lea Brothers & Co.'s Publications — Pharm., Mat. Med., Therap. 11 BMUJSTTOI^, T. LAUDJEB, M.D., D.Sc, F.li.8., F.B.C.P., Lectvr&r on Materia Medica and Therapeutics at St. Bartholomew* s Sospital, London^ etc. A Text-book of Pharmacology, Therapeutics and Materia Medica; Including the Pharmacy, the Physiological Action and the Therapeutical Uses of Drugs. In one handsome octavo volume of about 1000 pages, with 188 illustrations. Cloth, $5.50 ; leather, $6.50. In press. It is with peculiar pleasure that the early appearance of this long expected work is announced by the publishers. "Written by the foremost authority on its subject in Eng- land, it forms a compendious treatise on materia medica, pharmacology, pharmacy, and the practical use of medicines in the treatment of disease. Space has been devoted to the fundamental sciences of chemistry, physiology and pathology, wherever it seemed necessary to elucidate the proper subject-matter of the book. A general index, an index of diseases and remedies, and an index of bibliography close a volume which will undoubtedly be of the highest value to the student, practitioner and pharmacist. It is a aeientific treatise worthy to be ranked with the highest productions in physiology, either in our own or any other language. Everything is practical, the dry, hard facts of physiology being pressed into service and applied to the treatment of the commonest complaints. The information is so systematically arranged that it is available for immediate use. The index is so carefully compiled that a reference to any special point is at once obtainable. Dr. Brunton is never satisfied with vague generalities, but gives clear and pre- cise directions for prescribing the various drugs and preparations. We congratulate students on being at last placed in possession of a scientific treatise of enormous practical importance.— J%8 Lancet, June 27, 1885. PARBISS, EDWAItJD, Late Professor of the TJieory and Practice of Pha/i^macy in the Philadelphia College of Pha/rmacy. A Treatise on Pharmacy : designed as a Text-book for the Student, and as a Guide for the Physician and Pharmaceutist. With many Formulae and Prescriptions. Fifth edition, thoroughly revised, by Thomas S. Wxegand, Ph. G. In one handsome octavo volume of 1093 pages, with 256 illustrations. Cloth, $5 ; leather, $6. No thoroughgoing pharmacist will fail to possess himself of so useful a guide to practice, and no physician who properly estimates the value of an accurate knowledge of the remedial agents em- ployed by him in daily practice, so far as their miscibility, com;patibility and mosteffective meth- ods of combination are concerned, can afford to leave this work out of the list of their works of reference. The country practitioner, who must ^ways be in a measure his own pharmacist, will find it indispensable. — Louisville Medical News, March 29, 1884. This well-known work presents itself now based upon the recently revised new Pharmacopoeia. Each page bears evidence of the care bestowed upon it, and conveys valuable Information from the rich store of the editor's experience. In fact, all that relates to practical pharmacy— apparatus, processes and dispensing— has been arranged and described with clearness in its various aspects, so as to aflFord aid and advice alike to the student and to the practical pharmacist. The work is judi- ciously illustrated with good woodcuts^^mericoTi Joti/mal of Pharmacy, January, 1884. There is nothing to equal Parrish's Pha/rmacy in this or any other language. ceutical Journal. -London Pharma- SERMAJSIW, Dr. L., Professor of Physiology in the University of Zwrich. Experimental Pharmacology. A Handbook of Methods for Determining the Physiological Actions of Drugs. Translated, with the Author's permission, and with extensive additions, by Koebet Meade Smith, M. D., Demonstrator of Physiology in the University of Pennsylvania. In one handsome 12mo. volume of 199 pages, with 32 illustrations. Cloth, |1.50. MAISCM, JOMNM., Phar. D., Professor of Materia Medica and Botany in the Philadelphia College of Pharmacy. A Manual of Organic Materia Medica; Being a Gruide to Materia Medica of the Vegetable and Animal Kingdoms. For the use of Students, Druggists, Pharmacists and Physicians. New (second) edition. In one handsome royal 12mo. volume of 550 pages, with 242 illtistrations. Cloth, $3.00. Just ready. This work contains the substance, — t\iQ practical "kernel of the nut" picked out, so that the stu- dent has no superfluous labor. He can confidently accept what this work places before him, without any fear that the gist of the matter is not in it. Another merit Is that the drugs are placed before him in such a manner as to aimplii^ very much the study of them, enabling the mind to grasp them more readily. The illustrations are most excellent, being very true to nature, and are alone worth the price of the book to the student. To the practical physician and pharmacist it is a valuable work for handy reference and for keeping fresh in the memory the knowledge of materia medica and botany already acquired. We can and do heartily recommend it. — Medical and Surgical Re- porter, Feb. 14, 1885. BBUCB, J. MITCSELL, M. D., F. JR. C. T., Physician and Lecturer on Materia Medica and Therapeutics at Charing Gross Hospital^ London, Materia Medica and Therapeutics. An Introduction to Kational Treat- ment. In one pocket-size 12mo. volume of 555 pages. Limp cloth, $1.50. Jitst ready. See Student^ Series of Manuals, page 3. GRIFFITH, ROBERT EGLESFIELD, M. D. A Universal Formulary, containing the Methods of Preparing and Aduainis- tering Officinal and other Medicines. The whole adapted to Physicians and Pharmaceut- ists. Third edition, thoroughly revised, with numerous additions, by John M. Maisoh, Phar. D., Professor of Materia Medica and Botany in the Philadelphia College of Pharmacy. In one octavo volume of 775 pages, with 38 illustrations. Cloth, $4.50 ; leather, $5.50. 12 Lea Brothers & Co.'s Publications — iYiar. luea., xnerap. > 8TILLE, A., M. D., LL. D., & MAI8CM, J. M., JPhar. D., Professor Emeritus of thf Theory and Prac- Prof, of Mat. Med. avA Botany in Phila. tice of Medicine and ^ ' Clinical Medicine College of Pharmacy, See'yto the Ameri- in the University of Pennsylvania. can PharTnaceuUeal Association. The National Dispensatory: Containing the Natural History, Chemistry, Phar- macy, Actions and Uses of Medicines, including those recognized in the Pharmacopoeias of the United States, Great Britain and Germany, with numerous references to the French Codex. Third edition, thoroughly revised and greatly enlarged. In one magnificent imperial octavo volume of 1767 pages, with Sll' 'fine engravings. Cloth, $7.25 ; leather, $8.00; half Eussia, open back, $9.00. With Denison's " Eeady Reference Index " $1.00 in addition to price in any of above styles of binding. Just ready. In the present revision the authors have labored incessantly with the view of making the third edition of The National Dispensatoey an even more completerepresen- tative of the pharmaceutical and therapeutic science of 1884 than its first edition was of that of 1879. For this, ample material has been afforded not only by the new United States Pharmacopoeia, but by those of Germany and France, which have recently appeared and have been incorporated in the Dispensatory, together with a large number of new non- officinal remedies. It is thus rendered the representative of the most advanced state of American, Eijglish, French and German pharmacology and therapeutics. The vast amount of new and important material thus introduced may be gathered from the fact that the additions to this edition amount in themselves to the matter of an ordinary full- sized octavo volume, rendering the work larger by twenty-five per cent, than the last edition. The Therapeutic Index (a feature peculiar to this work), so suggestive and convenient to the practitioner, contains 1600 more references than the last edition — the General Index 3700 more, making the total number of references 22,390, while the list of illustration* has been increased by 80. Every effort has been made to prevent undue enlargement of the volume by having in it nothing that could be regarded as superfluous, yet care has been taken that nothing should be omitted which a pharmacist or physician could expect to find in it. The appearance of the work has been delayed by nearly a year in consequence of the determination of the authors that it should attain as near an approach to absolute ac- curacy as is humanly possible. With this view, an elaborate and laborious series of examinations and tests have been made to verify or correct the statements of the Pharma- copoeia, and very numerous corrections have been found necessary. It has thus been ren- dered indispensable to all who consult the Pharmacopoeia. The work is therefore presented in the full expectation that it will maintain the position universally accorded to it as the standard authority in all matters pertainllig to its subject, as registering the furthest advance of the science of the day, and. as embody- ing in a shape for convenient reference the recorded results of human experience in the laboratory, in the dispensing room, and at the bed-side. up to date. The work has been Tery well done, a large number of extrarpharmacopoeial remedies having been added to those mentioned in previous editions. — London Lancet, Nov. 22, 1884. Its completeness as to subjects, the comprehen- siveness of its descriptive language, the thorough- ness of the treatment of the topics, its brevity not sacrificing the desirable ' features of information for which such a work is needed, make this vol- ume a marvel of excellence. — Pha/rmaceuiical lie- cord, Aug. 15, 1884. of its kind extant. — Louisville Medical News, Dec. 6, 1884. We have much pleasure in recording the appear- ance of a third edition of this excellent work of reference. It is an admirable abstract of all that relates to chemistry, pharmacy, materia medica, pharmacology and therapeutics. It may be re- garded as embodying the Pharmacopreias of the civilized nations of the world, all being brought FAMQUSABSOW, MOBFBT, M. D., Lectwrer on Materia Medica at St. Mary^s Hospital Medical School. A Gruide to Therapeutics and Materia Medica. Third American edition, specially revised by the Author. Enlarged and adapted to the U. S. Pharmacopoeia by Fbank Woodbury, M. D. In one handsome 12mo. volume of 524 pages. Cloth, |2.25. Dr. Farquharaon's Therapeutics is constructed upon a plan which brings before the reader all the essential points with reference to the properties of drugs. It impresses these upon him in such a way as to enable him to take a clear view of the actions of medicines and the disordered conditions in which they must prove useful. The double-col- umned pages — one side containing the recognized physiological action of the medicine, and the other the disease in which observers (who are nearly al- t good r suits — make a very good arrangement. The early- ways mentioned) have obtained from it i chapter containing rules for prescribing is excel- lent. — Canada Med. and Surg. JournaL, Dec. 1882. STILLB, ALFRED, M. D., LL. D., Professor of Theory and Practice. of Med. and of Clinical Med. m the Umv. ofPemiit. Therapeutics and Materia Medica. A Systematic Treatise on the Action and Uses of Medicinal Agents, including their Description and History. Fourth edition, revised and enlarged. In two large and handsome octavo volumes, containing 1936 pages. Cloth, 110.00; leather, ^12.00; very handsome halt Eussia, raised bands, $13.00. We can hardly admit that it has a rival in the in pharmacodynamics, but as by far the most com- multitude of its citations and the fulness of its plete treatise upon the clinical and practical side reseai'ch into clinical histories, and wemustassign of the question. — Boston Medical andSurgical Jov/r- Lt a place in the physician's library ; not, indeed, nal, Nov. 6, 1874. ns ftilly representiD g the present state of knowledge liEA Brothers & Uo.'s Publications — Pathol., Uistol. 13 COATS, JOSJEPH, 31. D., F. F. P. 8., Pathologist to the Qlaagovo We&t&m Injirmary. A Treatise on Pathology. In one very handsome octavo volume of 829 pages, with 339 beautiful illustratione. Cloth, $5.50; leather, $6.50. The work before us treats the subject of Path- ology more extensively than it is usually treated in similar works. Medical students as ■well as physicians, who desire a work for study or refer- ence, that treats the subjects in the various de- partments in a very thorough manner, but without prolixity, will certainly give this one the prefer- ence to any with which we are acquainted. It sets forth the most recent discoveries, exhibits, in an interesting manner, the changes from a normal condition effected in structures by disease, and points out the characteristics of various morbid agencies, so that they can be easily recognized. But, not limited to morbia anatomy,it explains fully how the functions of organs are disturbed by abnormal conditions. There is nothing belonging to its de- partment of medicine that is not as fully elucidated as our present knowledge will admit.— Otncinnaii Medical News, Oct. 1883. GBBEW, T. JBTFIVHT, M. JD., Lecturer on Pathology and Morbid Anatomy at Charing-Oross Hospital Medical School, London. Pathology and Morbid Anatomy. Fifth American irom the sixth revised and enlarged English edition. In one very handsome octavo volume of 482 pages, with 150 line engravings. Cloth, $2.50. The fact that this well-known treatise has so rapidly reached its sixth edition is a strong evi- dence of its popularity. The author is to bg con- fratulated upon the thoroughness with which he as prepared this work. It Is thoroughly abreast with all the most recent advances in pathology. No work in the English language is so admirably adapted to the wants of the student and practi- tioner as this, and we would recommend it most earnestly to every one. — Nashville Journal of Medi- cine and Surgery, Nov. 1884. WOOnHFAD, G. SIMS, M. D., F. B. C. P. E., Demonstrator of Pathology in the University of Edinburgh. Practical Pathology. A Manual for Students and Practitioners. In one beau- tiful octavo volume of 497 pages, with 136 exquisitely colored illustrations. Cloth, $6.00. The author merits all praise for having produced a valuable work. — Medical Record^ May 31, 1884, It is manifestly the product of one who has him- self travelled over the whole field and who is skilled not merely in the art of histology, but in the obser- vation and interpretation of morbid changes. The work is sure to command a wide circulation. It _ It forms a real guide for the student and jiracti- tioner who is thoroughly In earnest in his en- deavor to see for himself and do for himself. To the laboratory student it will be a helpful com- panion, and all those who may wish to familiarize themselves with modem methods of examining morbid tissues are strongly urged to provide themselves with this manual. The numerous drawings are not fancied pictures, or merely schematic diagrams, but they represent faithfully the actual images seen under the microscope. should do much to encourage the pursuit of path- ology, since such advantages in histological study have never before been offered. — TAe JCcmcei, Jan. 5, 1884. SCHAFBB, BJDWAHJ) A., F. M. S., Assistant Professor of Physiology in University College, London. The Essentials of Histology. In one octavo volume of 246 pages, with 281 illustrations. Cloth, $2.25. ShorUy. COJRJVIL, v., a/nd HAJVTIFIt, L., Prof, in the Faculty of Med. of Paris. Prof, in the College of Prance. A Manual of Pathological Histology. Translated, with notes and additions, by E. O. Shakespeake, M. D., Pathologist and Ophthalmic Surgeon to Philadelphia Hospital, and by J. Henry C. Simes, M. D., Demonstrator of Pathological Histology iu the University of Pennsylvania. In one very handsome octavo volume of 800 pages, with 360 illustrations. Cloth, $5.50 ; leather, $6.50 ; half Eussia, raised bands, $7. KIjFIJSr, F., M. J)., F. B. S., Joint Lectv/rer on General Anat. and Phys. in the Med. School of St. Bartholomew's Hosp., London. Elements of Histology. In one pocket-size 12mo. volume of 360 pages, with 181, illus. Limp cloth, red edges, |1.50. See Student^ Series of Manuals, page 3. Although an elementary work, it is by no means The illustrations are numerous and ezcellent. We superficial or incomplete, for the author presents commend Dr. Klein's Elements most heartily to in conciselanguagenearlyallthefundamental facts the student. — Medical Record, Dec. 1, 1883. regarding the microscopic structure of tissues. PFJPPFB, A. J., M. B., M. S., F. B. C. S., Surgeon and Lecturer at St. Mary's Hospital, London. Surgical Pathology. In one pocket-size 12mo. volume of 511 pages, with 81 illustrations. Limp cloth, red edges, $2.00. See Student^ Series of Manuals, page 3. It is not pretentious, but it will serve exceed- ingly well as a book of reference. It embodies a treat deal of matter, extending over the whole eld of surgical pathology. Its form is practical, its language is clear, and the information set forth is well-arranged, well-indexed and well- illustrated. The student will iind in it nothing that is unnecessary. The list of subjects covers the whole range of surgery. The book supplies a very manifest want and should meet with suc- cess.— if «w York Medical Journal, May 31, 1884. SOHAFEK'S PEACTIOAL HISTOLOGY. In one OGY. Translated by Joseph Leidt, M. D. In one handsome royal 12mo. volume of 308 pages, with I volume, very large , imperial quarto, with 320 40 illustrations. I copper-plate figures, plain and colored and des- GLUGE'S ATLAS OF PATHOLOGICAL HISTOL- 1 cnptive letter-press. Cloth, J4.00 14 Lea Brothers & Co.'s Publications — Practice of Med. FLINT, AUSTIN, M. D., Traf, of the Principles and Practice of Med. and of Clin. Med. in Bellevue Hospital Medical CollegCj N. Y. A Treatise on the Principles and Practice of Medicine. Designed for tlie use of Students and Practitioners of Medicine. With an Appendix on the Researches of Koch, and their bearing on the Etiology, Pathology, Diagnosis and Treatment of Phthisis. Fifth edition, revised and largely rewritten In one large and closely-printed octavo volume of 1160 pages. Cloth, |5.50 ; leather, $6.50 ; half Russia, |7. Koch's discovery of the bacillus of tubercle gives promise of being the greatest boon ever conferred by science on humanity, surpassing even vaccination in its benefits to mankind. In the appendix to his work, Professor Flint deals with the subject from a practical standpoint, discussing its bearings on the etiology, pathology, diagnosis, prog- nosis and treatment of pulmonary phthisis. Thus enlarged and completed, this standard work will be more than ever a necessity to the physician who duly- appreciates the re- sponsibility of his calling. A well-known writer and lecturer on medicine recently expressed an opinion, in the highest de- g:ee complimentary of me admirable treatise of r. Flint, and in eulogizing it, he described it ac- curately as "readable and reliable." No text-book is more calculated to enchain the interest of the student, and none better classifies the, multitudi- nous subjects included in it. It has already so far won its way in England, that no inconsiderable number of men use it alone in the study of pure medicine ; and we can say of it that it is in evei-y way adapted to serve, not only as a com plete guide, but also as aij. ample instructor in the science and practice of medicine. The style of Dr. Flint is always polished and engaging. The work abounds in perspicuous explanation, and is a most valuable text-book of medicine. — London Medical News. This work is so widely known and accepted as the best American text-book of the practice of medicine that it would seem hardly worth while to give this, the fifth edition, anything more than a passing notice. But even the most cursory exami- nation shows that it is, practically, much more than a revised edition | it is, in fact, rather a new work throughout. This treatise will undoubtedly continue to hold the first place in the estimation of American physicians and students. No one of our medical writers approaches Professor Flint in clearness of diction, breadth of view, and, what we regard of transcendent importance, rational esti- mate of the value of remedial agents. It is thor- oughly practical, therefore pre-eminently the book for American readers. — St. Louis Clin. Rec., Mar. '81. MAItTSMOItinE, HENMY, M. I)., LL. D., Lately Professor of Hygiene in the University of Pennsylvania. Essentials of the Principles and Practice of Medicine. A Handbook for Students and Practitioners. Fifth edition, thoroughly revised and rewritten. In one royal 12mo. volume of 669 pages, with 144 illustrations. Cloth, $2.75 ; half bound, $3.00. this one ; and probably not one writer in our day had & better opportunity than Dr. Hartshorne for condensing all the views of eminent jjractitioners into a 12mo". The numerous illustrations will be very useful to students especially. These essen- tials, as the name suggests, are not intended to Within the compass of 600 pages it treats of the history of medicine, general pathology, general symptomatology, and physical diagnosis (including laiyngoscope, ophthalmoscope, etc.), general ther- apeutics, nosology, and special pathology and prac- tice. There is a wonderful amount of information contained in this work, and it is one of the best of its kind that we have seen. — Glasgow Medical Jov/rnal, Nov. 1882. An indispensable book. No work ever exhibited a better average of actual practical treatment than supersede the text-books of Flint and Bartholow, but they are the most valuable in affording the means to see at a glance the whole literature of any disease, and the most valuable treatment. — Chicago Medical Journal ., F. B. C. F., Physician to and Lecturer on Medicine at St. Mary's Hospital. The Pulse. In one 12mo. volume. See Series of Clinical Mcmuala, page 3. 8CHBEIBEB, DB. JOSFFH. A Manual of Treatment by Massage and Methodical Muscle Ex- ercise. Translated by Waiter Mendelson, M. D., of New York. In one handsome octavo volume of about 300 pages, with about 125 fine engravings. Preparing. IINLAYSON, JAMBS, M. D., Editor, Physician and Lecturer on Clmical Medicine vn the Glasgow Western Infvrmary, etc. Clinical Diagnosis. A Handbook for Students and Practitioners of Medicine. With Chapters by Prof. Gairdner on the Physiognomy of Disease ; Prof. Stephens on Diseases of the Female Organs; Dr. Eobertson on Insanity; Dr. Gemmell on Physical Diagnosis ; Dr. Coats on Laryngoscopy and Post-Mortem Examinations, and by the Editor on Case-taking, Family History and Symptoms of Disorder in the Various Systems. In one handsome 12mo. volume of 546 pages, with 84 illustrations. Cloth, $2.63. FMNWICK, SAMUEL, M. D., Assistant Physician to the London Motpvtal. The Student's Guide to Medical Diagnosis. Prom the third revised and enlarged English edition. In one very handsome royal 12mo. volume of 328 pages, with 87 illustrations on wood. Cloth, $2.25. TAJVWEB, THOMAS SAWJKES, M. B. A Manual of Clinical Medicine and Physical Diagnosis. Third American from the second London edition. Eevised and enlarged by Tilbxtry Fox, M. D. In one small 12mo. volume of 362 pages, with illustrations. Cloth, $1.50. FOTSFBGILL, J. M., M. I)., Edim., M. B. C. F., Lond., Physician to the City of London Hospital for Diseases of the Chest. The Practitioner's Handbook of Treatment; Or, The Principles of Thera- peutics. New edition. In one octavo volume. Preparing. STURGES' INTRODUCTION TO THE STUDY OP CLINICAL MEDICINE. Being a Guide to the Investigation of Disease. In one handsome Vimo. Tolutne of 127 pages. Cloth, $1.26. DAVIS' CLINICAL LECTURES ON VARIOUS IMPORTANT DISEASES. By N. S. Davis, M. D. Edited by Frank H. Davis, M. D. Second edition. 12mo. 287 pages. Cloth, 81.75. Lea Brothers & Co.'s Publications — Hygiene, Electr., Pract. 17 BICHARpSOJSr, B. W., M.A., M.D., LL. D., F.B.S., F.8.A. Fellow of the Royal College of Physicians, London. Preventive Medicine. In one octavo volume of 729 pages. Cloth, $4 ; leather, $5 ; very handsome half Russia, raised bands, $5.50. Dr. Bichardaon has succeeded in producing a work which is elevated in conception, comprehen- sive in scope, scientific in character, systematic in arrangement, and which is written in a clear, con- cise and pleasant manner. He evinces the happy faculty or extracting the pith of what is known on the subject, and of presenting it in a most simple, intelligent and practical form. There is perhaps no similar work written foT the general public thatcontains auch a complete, reliable and instruc- tive collection of data upon the diseases common to the race, their origins, causes, and the measures for their prevention. The descriptions of diseases are clear, chaste and scholarly ; the discussion of the question of disease is comprehensive, masterljy and fully abreast with the latest and best knowl- edge on the subject, and the preventive measures advised are accurate, explicit and reliable.— T/ie American Journal of the Medical Sciences, April, 1884. This is a book that will surely find a place on the table of every progressive physician. To the medical profession, whose duty is quite as much to prevent as to cure disease, the book will be a boon. — Boston Medical and Surgical Journal, Mar. 6, 1884. The treatise contains a "vast amount of solid, valu- able hygienic information. — Medical and Surgical Reporter, Feb. 23, 1884. BARTMOLOW, BOBBBTS, A. M., M. D., LL. B., Prof, of Materia Medica and General Therapeutics in the Jefferson Med. Coll. ofPhila., etc. Medical Electricity. A Practical Treatise on the Applications of Electricity to Medicine and Surgery. Second edition, pages, with 109 illustrations. Cloth, ^2.50. The second edition of this work following so soon upon the first would in itself appear to be a sufficient announcement; nevertheless, the text has been so considerably revised and condensed, and so much enlarged by the addition of new mat- ter, that we cannot fail to recognize a vast improve- ment upon the former work. The author has pre- pared his work for students and practitioners — for those who have never acquainted themselves with the subject, or, having done so, find that after a time their knowledge needs refreshing. We think he has accomplished this object. The book is not too voluminous, but is thoroughly practical, sim- ple, complete and comprehensible. It is, more- over, replete with numerous illustrations of instru- ments, appliances, etc. — Medical Record, November 15, 1882. In one very handsome octavo volume of 292 A most excellent work, addressed by a practi- tioner to his fellow-practitioners, and therefore thoroughly practical. The work now before us has the exceptional merit of clearly pointing out where the benefits to be derived from electricity must come. It contains all and everything that the practitioner needs in order to understand in- telligently the nature and laws of the agent he is makmg use of, and for its proper application in practice. In a condensed, practical lorm, it pre- sents to the physician all that he would wish to rememberafterperusinga whole library on medical electricity, including the results of the latest in- vestigations. It is the book for the practitioner, and the necessity for a second edition proves that it has been appreciated by the profession. — Physi- cian and Surgeon, Dec. 1882. THB YBAB-BOOK OF TBBATMENT. A Comprehensive and Critical Review for Practitioners of Medi- cine. In one 12mo. volume of 320 pages, bound in limp cloth, with red edges, $1.25. This work presents to the practitioner not only a complete classified account of all the more important advances made in the treatment of Disease during the year ending Sept. 30, 1884, but also a critical estimate of the same by a competent authority. Each department of practice has been fully and concisely treated, and into the consideration of «ach subject enter such allusions to recent pathological and clinical work as bear directly upon treatment. As the medical literature of all countries has been placed under contri- bution, the references given throughout the work, together with the separate indexes of subjects and authors, will serve as a guide for those who desire to investigate any thera- peutical topic at greater length. In a few momenta the busy practitioner can re- fresh his mind as to the principal advances in treatment for a year past. This kind of work is peculiarly useful at the present tim e, when current literature is teeming '" '"* ' '"' """ th< ■ with innumerable so-called ■advances, of which ttie practitioner has not time to determine the value. Here he has, collected from many sources, a rtsumt of the theories and facts which are new, either entirely or in part, the decision as to their novelty being made by those who by wide reading and long experience are fully competent to render such a verdict.— Ameri- can Jov/maL of the Medical Sciences, April, 1885. It is a complete account of the more important advances made in the treatment of disease. Ex- treme pains have been taken to explain clearly in the fewest possible words the views of each writerj and the details of each subject. One of the principle points about the book is its practical, yet concise language. Bach editor has well per- formed his duty, and we can say with truth that it is a volume well worth buying for frequent use, — Virginm Medical Monthly, March, 1885, HABEBSMON, 8. O., M. B., Senior Physician to and late Leet. on Principles and Practice of Med. at Quy^s Hospital, London. On the Diseases of the Abdomen ; Comprising those of the Stomach, and other parts of the Alimentary Canal, (Esophagus, CsBCum, Intestines and Peritoneum. Second American from third enlarged and revised English edition. In one handsome octavo volume of 554 pages, with illustrations. Cloth, $3,50. PAVY'S TREATISE ON THE FUNCTION OF DI- GESTION; its Disorders and their Treatment, From the second London edition. In one octavo volume of 238 pages. Cloth, $2.00. CHAMBERS' MANUAL OF DIET AND RE&IMBN IN HEALTH AND SICKNESS. In one hand- some octavo volume of 302 pp. Cloth, $2,76, BARLOWS MANUAL OP THE PRACTICE OF MEDICINE, With additions by D, F, Conmii, M. D. 1 vol, 8vo,, pp, 603, Cloth, $2,60, TODD'S CLINICAL LECTURES ON CERTAIN ACUTE DISEASES, In one octavo volume of 320 pages. Cloth, $2,60, HOLLAND'S MEDICAL NOTES AND REFLEC- TIONS, 1 vol, 8vo,, pp. 493. Cloth, $3,60. 18 Lea Brothers & Co.'s Publications — Throat, Lungs, Heart. COHBN, J. SOLIS, M. I)., Lecturer on Laryngoscopy and Diseases of the Throat arid Chest in the Jeferson Medical College. Diseases of the Throat and Nasal Passages. A Guide to the Diagnosis and Treatment of Affections of the Pharynx, (Esophagus, Trachea, Larynx and Nares. Third edition, thoroughly revised and rewritten, with a large number of new illustrations. In one very handsome octavo volume. Preparing. SUILJEIt, CAUL, M. D., Lecturer on Laryngoscopy m the University of Permsylva/nia. A Handbook of Diagnosis and Treatment of Diseases of the Throat, Nose and Naso-Pharynx, Second edition. In one handsome royal 12mo. volume of 294 pages, with 77 illustrations. Cloth, $1.75. It is one of the best of the practical textbooks on this subject with which we are acquainted. The present edition has been increased in size, but its eminently practical character has been main- tained. Many new illustrations have also been introduced, a case-record sheet has been added, and there are a valuable bibliography and a good index of the whole. For any one who wishes to make himself familiar with the practical manage- ment of cases of throat and nose disease, the book will be found of great value. — New York Medical Journal, June 9, 1883. The work before us is a concise handbook upon the essentials of diagnosis and treatment in dis- eases of the throat and nose. The art of laryngos- copy, the anatomy of the throat and nose and the pathology of the mucous membrane are discussed with Qonciseness and ability. The work is pro- fusely illustrated, excels in many essential feat- ures, and deserves a place in the office of the practitioner who would inform himself as to the nature, diagnosis and treatment of a class of dis- eases almost inseparable ' from general medical gractice. With advanced students the book must e very popular on account of its condensed style. —Louisville Medical News, June 26, 1883. BUOWJVU, LMNNOX, F. M. C. S., Bdin., Senior Surgeon to the Central London Throat and Ea/r Hospital^ etc. The Throat and its Diseases. Second American from the second English edi- tion, thoroughly revised. With 100 typical illustrations in colors and 50 wood engravings, designed and executed by the Author. In one very handsome imperial octavo volume of about 350 pages. Preparing. FLIJSrT, AJJSTIJf, M.D., Professor of the Principles and Practice of Medicine in Bellevue Hospital Medical College, N. 7. A Manual of Auscultation and Percussion ; Of the Physical Diagnosis of Diseases of the Lungs and Heart, and of Thoracic Aneurism. Third edition. In one hand- some royal 12mo. volume of 240 pages. Cloth, $1.63. the results of his careful study and ample ex- perience In such wise that the young will find it the best source of instruction, and the old the most pleasant means of reviving and complementing their knowledge. — American Practitioner, June, 1883. It is safe to say that there is 'not in the English language, or any other, the equal amount of clear, exact ana comprehensible information touching the physical exploration of the chest, in an equal number of words. Professor Flint's language is precise and simple, conveying without dubiety JBT THE SAME AUTHOR. Physical Exploration of the Iiungs by Means of Auscultation and Percussion. Three lectures delivered before the Philadelphia County Medical Society, 1882-83. In one handsome small 12mo. volume of 83 pages. Cloth, $1.00. A Practical Treatise on the Physical Exploration of the Chest and the Diagnosis of Diseases Affecting the Respiratory Organs. Second and revised edition. In one handsome octavo volume of 591 pages. Cloth, $4.50. Phthisis: Its Morbid Anatomy, Etiology, Symptomatic Events and Complications, Fatality and Prognosis, Treatment and Physical Diag- nosis ; In a series of Clinical Studies. In one handsome octavo volume of 442 pages. Cloth, $3.50. A Practical Treatise on the Diagnosis, Pathology and Treatment of Diseases of the Heart. Second revised and enlarged edition. In one octavo volume of 550 pages, with a plate. Cloth, $4. GROSS, S. D., M.D., LL.J)., JD.C.L. Oxon., Xi.J>. Cantab. A Practical Treatise on Foreign Bodies in the Air-passages. In one octavo volume of 452 pages, with 59 illustrations. Cloth, $2.75. POLLER ON DISEASES OP THE LUNGS AND AIB-PASSAGBS. Their Pathology, Physical Di- agnosis, Symptoms and Treatment. From the second and revised English edition. In one octavo volume of 475 pages. Cloth, $3.60. SLADE ON DIPHTHERIA; its Nature and Treats ment, with an account of the History of its Pre- valence in various Countries. Second and revised edition. In one 12mo. vol., pp. 158. Cloth, $1.25. WAL8HE ON THE DISEASES OP THE HEART AND GREAT VESSELS. Third American edi- tion. In 1 vol. 8vo., 416 pp. Cloth, $3.00. SMITH ON CONSUMPTION! its Early and Reme- diable Stages. 1 vol. 8vo., pp. 253. Cloth, $2.25. LA ROCHE ON PNEUMONIA. 1 vol. 8vo. of 490 pages. Cloth, $3.00. WILLIAMS ON PULMONARY CONSUMPTION; its Nature, Varieties and Treatment. With an analysis of one thousand cases to exemplify Its duration. In one 8vo. vol. of 303 pp. Cloth, $2.50. JONES' CLINICAL OBSERVATIONS ON FUNC- TIONAL NERVOUS DISORDERS. Second Am- erican edition. In one handsome octavo volume of 340 pages. Cloth, $3.26. Lea Brothers & Co.'s Publications — Nerv. and Ment. Dis., etc, 19 MITCHELL, S. WEIB, M. B., Physician to Orthopoedic hospital and the Injvrmaryfor Diseases of the Nervous System, Phila., etc. Leotures on Diseases of the W'ervous System; Especially in Women. Second edition. In one 12mo. volume of 288 pages. Clothj $1.75. Just ready. We feel sure that the new edition of Dr. Mitch elVs admirable lectures will be received on this side of the Atlantic with inore than ordinary at- tention. His subject, the nervous disorders of women, is one that interests every practitioner, and his views on treatment are graduafly receiving general acceptance.— iondon Medical Times arwi Gazette, July 4, 1885. BOSS, JAMBS, M.n., F.B. C.P., LJL. D., Senior Assistant FhysiGian to the Manchester Royal Infirmary, A Text-Book on Diseases of the Nervous System. In one handsome octavo volume of 600 pages, fully illustrated. Shortly. HAMILTON, ALLAW McLAJSTE, M. D., Attemding Physician at the Hospital for Epileptics and Paralytics, BlackwelVs Island, N. Y. Nervous Diseases ; Their Description and Treatment. Second edition, thoroughly revised and rewritten. In one octavo volume of 598 pages, with 72 illustrations. Cloth, $4. When the first edition of this good book appeared we gave it our emphatic endorsement, and the present edition enhances our appreciation of the book and its author as a safe guide to students of clinical neurology. One of the best and most critical of English neurological journals, Brain, has characterized this book as the best of its kind in any language, which is a handsome endorsement from an exalted source. The improvements in the new edition, and the additions to it, will justify its purchase even by those who possess the old. — Alienist and Neu/rologist, April, 1882. TJJKB, DAJSriEL MACK, M. JD., Joint Author of The Manual of Psychological Medicine, etc. Illustrations of the Influence of the Mind upon the Body in Health and Disease. Designed to elucidate the Action of the Imagination. New edition. Thoroughly revised and rewritten. In one handsome octavo volume of 467 pages, with two colored plates. Cloth, $3.00. It is impossible to peruse these interesting chap- ters without being convinced of the author's per- fect sincerity, impartiality, and thorough mental grasp. Dr. Tuke has exhibited the requisite amount of scientific address on all occasions, and the more intricate the phenomena the more firmly has he adhered to a physiological and rational method of interpretation. Guided by an enlight- ened deduction, the author has reclaimed for science a most interesting domain in psychology, previously abandoned to charlatans and empirics. This book, well conceived and well written, must commend itself to every thoughtful understand- ing. — New York Medical JowrnaU September 6, 1884. CLOUSTOW, THOMAS S., M. J)., F. JR. C. P., L. B. C. S., Lecturer on Mental Diseases in the University of Edinbwrgh. Clinical Lectures on Mental Diseases. With an Appendix, containing an Abstract of the Statutes of the United States and of the Several States and Territories re- lating to the Custody of the Insane. By Chables F. Folsom, M. D., Assistant Professor of Mental Diseases, Medical Department of Harvard University. In one handsome octavo volume of 541 pages, illustrated with eight lithographic plates, four of which are beautifully colored. Cloth, $4. The practitioner as well as the student will ac- cept the plain, practical teaching of the author as a forwsffd step in the literature of insanity. It is refreshing to find a physician of Dr. Olouston's experience and high reputation giving the bed- aide notes upon which his experience has been founded and his mature judgment established. Such clinical observations cannot but be useful to the general practitioner in guiding him to a diag- nosis and indicating the treatment, especially m many obscure and doubtful cases of mental dis- ease. To the American reader Dr. Folsom's Ap- pendix adds greatly to the value of the work, and will make it a desirable addition to every library. — American Psychological Journal, July, 1884. 108 pages. '. Folsom's Abstract may also be obtained separately in one octavo volume of Cloth, $1.50. SAVAGE, GEOBGB S., Jf. J>., Lecturw on Mental Diseases at Ouy's Hospital, London. Insanity and Allied Neuroses, Practical and Clinical. In one 12mo. vol- ume of 551 pages, with 18 typical illustrations. Cloth, $2.00. Just ready. See Series of Clinical Manuals, page 3. As a handbook, a guide to practitioners and stu- common sense is everywhere apparent. We re- dents, the book fulms an admirable purpose. The peat that Dr. Savage na many forms of insanity are described with char- acteristic clearness, the illustrative oases are care- fully selected, and as regards treatment, sound that Dr. Savage nas written an excellent manual for the practitioner and student.— .ilm- erican Journal of Insanity, April, 1885. PLATFAIB, W. 8., M. D., F. B. C. F., The Systematic Treatment of Nerve Prostration and Hysteria. one handsome small 12mo. volume of 97 pages. Cloth, $1.00. In Blandford on Insanity and its Treatment: Lectures on the Treatment, Medical and Legal, of Insane Patients. In one very handsome octavo volume. 20 Lea Brothers & Co.'s Publications — Surg-ery. Cantab*, Emeritus Professor ofSierg&ry in the Jefferson Medical College of PkUadelpkia. A System of Surgery : Pathological, Diagnostic, Therapeutic and Operative. Sixth edition, thoroughly revised and greatly improved. In two large and beautifully- printed imperial octavo volumes containing 2382 pages, illustrated by 1623 engravings. Strongly bound in leather, raised bands, $15; half Eussia, raised bands, $16. Dr. Gross' System of Surgery has long been the standard work on that subject for students and practitioners. — London Lancet, May 10, 1884. The work as a whole needs no commendation. Many years ago it earned for itself the enviable rep- utation of the leading American work on surgeiy, and it is still capable of maintaining that standard. The reason for this need only be mentioned to be appreciated. The author has always been calm and judicious in his statements, has based his con- clusions on much study and personal experience, has been able to grasp his subject in its entirety, and, above all, has conscientiously adhered to truth and fact, weighing the evidence, pro and con, accordingly. A considerable amount of new material has been introduced, and altogether the distinguished author has reason to be satisfied that he has placed the work fully abreast of the state of our knowledge. — Med. Record, Nov. 18, 1882. His System of Surgery, which, since its first edi- tion ■ in 1859, has been a standard work in this country as well as in America, in "the whole domain of surgery," tells how earnest and labori- ous and wise a surgeon he was, how thoroughly he appreciated the work done by men in other countries, and how much he contributed to pro- mote the science and practice of surgery in his own. There has been no man to whom America is so much indebted in this respect as the Nestor of surgery. — British Medical Journal, May 10, 1884. A8SSUBST, JOMW, Jr., M. B., Professor of Clinical Surgery, Umv. of Petma., Surgeon to the Episcopal Hospital, Philadelphia. The Principles and Practice of Surgery. Fourth edition, enlarged and revised. In one large and handsome octavo volume of about 1100 pages, with about 575 illustrations. Shortly. GOULD, A. PEARCE, M. 8., M. B., F. It. C. S„ Assistant Sturgeon to Middlesex Hospital. Elements of Surgical Diagnosis. In one pocket-size 12mo. volume of 589 pages. Cloth, $2.00. Just ready. See Students^ Series of Manuals^ page 3. The student and practitioner will find the principles of surgical diagnosis very satisfactorily set forth with all unnecessary verbiage elimi- nated. Every medical student attending lectures should have a copy to study during the intervals. and if practitioners would devote a portion of their leisure to the study of it, they would receive immense benefit in the way of refreshing their knowledge and bringing it up to the present state of progress. — Cincinnati Medical News, Jan., 1885. GIBWEY, r. P., M. B., Surgeon to the Orthopcedic Sospital, New York, etc. Orthopsedic Surgery. For the use of Practitioners and Students. In one hand- some octavo volume, profusely illustrated. MOBEBTS, jrOBOST B., A. M., M. D., Lecturer on Anatomy and on Operative Surgery at the Philadelphia School of Anatomy. The Principles and Practice of Surgery. For the use of Students and Practitioners of Medicine and Surgery. In one very handsome octavo volume of about 500 pages, with many illustrations. Preparing. BELBA3IT, EBWABB, F. B. C. 8., Surgeon and Lecturer on Surgery at Charing Cross Hospital, London. Operative Surgery. Shortly.. See Students' Series of Manuals, page 3. 8TI3I80J!f, LEWI8 A., B. A., M. I)., Prof, of Pathol. Anat. at the Univ. of the City of New York, Surgeon and Curator to Belleme Hosp. A Manual of Operative Surgery. New (second) edition. In one very hand- some royal 12mo. volume of about 500 pages, with about 350 illustrations. Cloth, $2.50. Shortly. A notice of the previous edition is appended. every student should possess one. JThis volume is devoted entirely to operative sur- gery, and is Intended to familiarize the student with the details of operations and the different modes of performing them. The work is hand- somely illustrated, and the descriptions are clear and well-drawn. It is a clever and useful volume ; This work does away with the necessity of pondering over larger works on surgery for descriptions of opera- tions, as it presents in a nutshell what is wanted by the surgeon without an elaborate search to find it. — Maryland Medical Journal, August, 1878. SARGENT ON BANDAGING and OTHER OPERA- TIONS OF MINOR SURGERY. New edition, with a Chapter on military surgery. One 12mo. volume of 383 pages, with 187 cuts. Cloth, $1.76. MILLER'S PRINCIPLES OF SURGERY. Fourth Amerioanfrom the third Edinburgh edition. In one 8vo. vol. of 638 pages, with 34.0 illustrations. Cloth, $3.75. MILLER'S PRACTICE OF SURGERY. Fourth and revised American from the last Edinburgh edition. In one large 8vo. vol. of 682 pages, with 3«4 illustrations. Cloth, 88.75. PIRRIE'S PRINCIPLES AND PRACTICE OP SURGERY. Edited by Johs Neill, M. D. In one 8vo. vol. of 784 pp. with 316 illus. Cloth, 83.76. COOPER'S LECTURES ON THE PRINCIPLES AND PRACTICE OF SURGERY. In one Svo.vol. of 767 pages. Cloth, $2.00. SKEY'S OPERATIVE SURGERY. In o»e vol. 8vo. of 661 pages, with 81 woodcuts. Cloth, $3.26. GIBSON'S INSTITUTES AND PRACTICE OF SURGERY. Eighth edition. In two octavo vols. of 965 pages, with 34 plates. Leather $6.60, Lea JiROTHEBs & Co.'s Publications — Surgery. 21 JSBicMSJEJsr, josjsr e., f. m. s., f. b. a s., Professor of Surgery in University College, London, etc. The Science and Art of Surgery ; Being a Treatise on Surgical Injuries, Dis- eases and Operations. From the eighth and enlarged English edition. In two large and beautiful octavo volumes of 2316 pages, illustrated with 984 engravings on wood. Cloth, $9; leather, raised bands, |11 ; half Russia, raised bands, |12. Just ready. After the profession has placed its approval upon a work to the extentof purchasing seven editions, it does not need to be introduced. Simultaneous with the appearance of this edition a translation is being made into Italian and Spanish. Thus this favorite text-book on surgery holds its own in spite of numerous rivals at the end of thirty years. It is a grand book, worthy of the art in the interest ©f which it is written. — Detroit Lancet, Jan. 10,18S5. After being before the profession, for thirty years and maintaining during that period a re- putation as a leading work on surgery, there is not mufh to be said in the way of comment or criti- cism. That it still holds its own goes without say- ing. The author infuses into it his large experi- ence and ripe judgment. Wedded to no school, committed to no theory, biassed b^ no hobby, he imparts an honest personality in his observations, and his teachings are the rulings of an impartial judge. Such men are always safe guides, and their works stand the tests of time and experience. Such an author is Erichsen, and such a work is his Surgery.— Medical Record, Feb. 21, 1885. BMYAlfT, TMOMAS, F. B. C. S., Surgeon and Lecturer on Surgery at Guy^s Hospital, London. The Practice of Surgery. Fourth American from the fourth and revised Eng- lish edition. In one large and very handsome imperial octavo volume of 1040 pages, with 727 illustrations. Cloth, $6.50 ; leather, $7.50 ; half Russia, $8.00. Just ready. This most magnificent work upon surgery has The treatise takes in the whole field of surgery, that of the eye, the ear, the female organs, ortho- psedics, venereal diseases, and military surgery, as well as more common and general topics. All of these are treated with clearness and with sufficient fulness to suit all practical purposes. The illustrations are numerous and well printed. We do not doubt that this new edition will con- tinue to maintain the popularity of this standard work. — Medical a/nd Surgical H^orter, Feb. 14, '85. reached a fourth edition in this country, showing the high appreciation in which it is held by the American profession. It comes fresh from the pen of the author. That it is the very best work on surgery for medical students we think there can be no doubt. The author seems to have understood just what a student needs, and has prepared the work accordingly.— Oincinnaii Medical News, January, 1885. By the same Author. Diseases of the Breast. In one 12mo, volume. Preparing. See Series of Clinical ManualSj page 3. BUTZIJSr, ELENBY T., F. B. C. S., Assistant Sargeon to St, Bartholomew's Hospital^ London. Diseases of the Tongue. In one 12mo. volume of 456 pages, with 8 colored plates and 3 woodcuts. Cloth, $3.50. Just ready. See Series of Clinical Manuals, page 3. ESMABCH, Dr. FBIEDBICB, Professor of Swrgery at the University of Kiel, etc. Early Aid in Injuries and Accidents. Five Ambulance Lectures. Trans- lated by H. E. H. Pbinckss Christian. In one handsome small 12mo. volume of 109 pages, with 24 illustrations. Cloth, 75 cents. The course of instruction is divided into five sections or lectures. The first, or introductory lecture, gives a brief account of the structure and organization of the human body, illustrated by clear, suitable diagrams. The second teaches how to give judicious help in ordinary injuries — contu- sions, wounds, haemorrhage and poisoned wounds. The third treats of first aid in cases of fracture and of dislocations, in sprains and in burns. Next, the methods of affording first treatment in cases of frost-bite, of drowning, of suflfocation, of loss of consciousness and of poisoning are described; and the fifth lecture teaches how injured persons may be most safely and easily transported to their homes, to a medical man, or to a hospital. The illustrations in the book are cleared good. — Medi- cal Times and Gazette, Nov. 4, 1882. TBEVES, FBEDEBICK, F. B. C. S., Assistant Surgeon to and Lectwer on Surgery at the London Hospital. Intestinal Obstruction. In one pocket-size 12mo. volume of 522 pages, with < illustrations. Limp cloth, blue edges, $2.00. page 3. A standard work on a subject that has not been so comprehensively treated by any contemporary English writer. Its completeness renders a full review difficult, since every chapter deserves mi- nute attention, and it is impossible to do thorough Just ready. See Series of Clinical Manuals, justice to the author in a few paragraphs. Intes- tinal Obstruction is a work that will prove of equal value to the practitioner, the student, the pathologist, the physician and the operating sur- geon. — British Medical Journal, Jan. 31, 1885. BALL, CMABLES B., M. Ch., Dub., F. B. C. S. E., Surgeon and Teacher at Sir P. Sun's Sospital, Dublin. Diseases of the Keetum and Anus. In one 12mo. volume of 550 pages. Preparing. See Series of Clinical Manuals, page 3. DBUITT, BOBEBT, M. B. C. S., etc. The Principles and Practice of Modern Surgery. From the eighth london edition. In one 8vo. volume of 687 pages, with 432 illus. Cloth, $4 ; leather, ?5. 22 Lea Brothers & Co.'s Publications — Surgery. MOLMBS, TIMOTSY, M. A., Sv/rgeon and Lecturer on Sv/rg&ry at St. Georges Hospital, London. A System of Surgery ; Theoretical and Practical. IN TEEATISES BY VAEIOUS ATJTHOBS. American edition, thoroughly revised and ee-edited by John H. Packard, M. D., Surgeon to the Episcopal and St. Joseph's Hospitals, Philadelphia, assisted by a corps of thirty-three of the most eminent American surgeons. In three large and very handsome imperial octavo volumes containing 3137 double- columned pages, with 979 illustrations on wood and 13 lithographic plates, beautifully colored. Price per volume, cloth, $6.00 ; leather, $7.00 ; half Eussia, $7.50. Per set, cloth, $18.00 ; leather, $21.00 ; half Eussia, $22.50. Sold only by subscription. Volume I. contains General Pathology, Morbid Processes, Injuries in Gen- eral, Complications of Injuries and Injuries op Eegions. V OLUME II. contains Diseases op Organs op Special Sense, Circulatory Sys- tem, Digestive Tract and Genito-Ueinary Organs. Volume III. contains Diseases op the Eespibatoby Organs, Bones, Joints and Muscles, Diseases op the Nervous System, Gunshot Wounds, Operative and Minor Surgery, and Miscellaneous Subjects (including an essay on Hospitals). This great work, issued some years since in England, has won such universal confi- dence wherever the language is ,_spoken that its republication here, in a form more thoroughly adapted to the wants oi the American practitioner, has seemed to be a duty owing to the profession. To accomplish this, each article has been placed in the hands of a gentleman specially competent to treat its subject, and no labor has been spared to bring each one up to the foremost level of the times, and to adapt it thoroughly to the practice of the country. In certain cases this has rendered necessary the substitution of an entirely new essay for the original, as in the case of the articles on Skin Diseases, on Diseases of the Absorbent System, and on Anaesthetics, in the use of which American practice difiers from that of England. The same careful and conscientious revision has been pursued throughout, leading to an increase of nearly one-fourth in matter, while the series of illustrations has been nearly trebled, and the whole is presented as a complete exponent of British and American Surgery, adapted to the daily needs of the working practitioner. In order to bring it within the reach of every member of the profession, the five vol- umes of the original have been compressed into three by employing a double-columned royal octavo page, and in this improved form it is offered at less than one-half the price of the original. It is printed and bound to match in every detail with Eeyuolds' System of Medi- cine. The work will be sold by subscription only, and in due time every member of the profession will be called upon and offered an opportunity to subscribe. The authors of the original English edition are men of the front rank in England, and Dr. Packard has been fortunate in securing as his American coadjutors such men as Bartholow, Hyde, Hunt, Conner, Stimson, Morton, Hodgen, tfewell and their colleagues. As a whole, the work will be fiolid and substantial, and a valuable addition to the libraiy of any medical man. It is more wieldly and more useful than the English edition, and with its companion work — "Reynolds' System of Medi- cine " — will well represent the present state of our science. One who is familiar with those two works will be fairly well furnished head-wise and hand- wise.— TAe Medical News, Jan. 7, 1882. STIMSOJS^, LEWIS A., B. A., M. I)., Pr&fesBor of Pathological Anatomy at the (TniversiU/ of the City of New York, Sturgeon and Owrator to Bellevue Wospital, Sv/rgeon to the Presbyteriim Hospital^ New York, etc. A Practical Treatise on Fractures. In one very handsome octavo volume of 598 pages, with 360 beautiful illustrations. Cloth, $4.75 ; leather, $5.75. The author has givGii to the medical profession ■in this treatise on fractures what is likely to be- come a standard work on the subject. It is certainly not surpassed by any work written in the English, or, for that matter, any other language. The au- thor tells us in a short, concise and comprehensive- manner, all that is known about his subject. There is nothing scanty or superficial about it, as in most other treatises ; on the contrary, everything is thor- ough. The chapters on repair of fractures and their treatment show him not only to be a profound stu- dent, but likewise a practical surgeon and patholo- gist. His mode of treatment of the different fract- ures is eminently sound and practical. We consider this work one of the best on fractures ; and it will ■be welcomed not only as a text-book, but also by the surgeon in full practice. — N. O. Medical and Sv^gical Jov/mal, March, 1883. The author gives in clear language all that the practical surgeon need know of the science of fractures, their etiology, symptoms, processes of union, and treatment, according to the latest de- velopments. On the basis of mechanical analysis the author accurately and clearly explains the clinical features of fractures, and by the same method arrives at the proper diagnosis snd rational treatment. A thorough explanation of the patho- logical anatomy and a careful description of the various methods of procedure make the book full of value for every practitioner. — Centralblatt filr Chirurgie, May 19, 1883. ' MABSH. MOWABD, F. B. C. 8., Senior Assistant Stirgeon to and Lecturer on Anatomy at St. Bartholomew's Hospital, London. Diseases of the Joints. In one 12mo. volume. Preparing. See Seriea of CUmcal Majnuak, page 3. PICK, T. PICKEBING, F. B. C. 8., Swrgeon to ami Lectweir on Swrgery at St. George's Hospital, London. Praetures and Dislocations. In one 12mo. volume. Preparimg. See Series •of OUnical Manuals, page 3. Lea Bbothers & Co.'s Publications — Frac, Disloc, Ophthal. 23 HAMILTON, FMANKH., M. D., LJL. D., Surgeon to Bellevue Hospital, New Yorh. A Practical Treatise on Fractures and Dislocations, Seventh edition, thoroughly revised and much improved. In one very handsome octavo volume of 998 pages, with 379 ilUistrations. Cloth, $5.50; leather, |6.50j very handsome half Bussia, open back, $7.00. Jiist ready. HamiHon's ^reat experience and wide acquaint- ance with the hterature of the subject have enabled him to complete the labors of Malgaigne and to place the reader in possession of the advances made during thirty years. The editions have fol- lowed each other rapidly, and they introduce us to the methods of practice, often so wise, of his American colleagues. More practical than Mal- e^igne's work, it will serve as a valuable guide to the practitioner in the numerous and emoarrass- ing cases which come under his observation. — Archives Qtn^rales de MHecine, Paris, Nov. 1884. This work, which, since its first appearance twenty-five years ago, has gone through many editions, and been much enlarged, may now be fairly regarded as the authoritative book of refer- ence on the subjects of fractures and dislocations. Bach successive edition has been rendered of greater value through the addition of more re- cent work, and especially of the recorded re- searches and improvements made hy the author himself and his countrymen. — British Medical Journal, May 9, 1885. With its first appearance in 1859, this work took rank among the classics in medical literature, and has ever since been quoted by surgeons the world over as an authority u_pon the topics of which it treats. The surgeon, if one can be found who does not already know the work, will find it scientific, forcible and scholarly in text, exhaustive in detail, and ever marked by a spirit of wise con- servatism. — Louisville Medical News, Jan. 10, 1885. For a c[uarter of a century the author has been elaborating and perfecting his work, so that it now stands as the best of its kind in any lan- guage. As a textrbook and as a book of reference and guidance for practitioners it is simply invalu- able. — New Orleans Med. and Sm'g. Journ'l, Nov. 1884. JULMM, MEJI^MY U., F. M. C. S., Senior Ass^t Su/rgeon, Royal Westmimter Ophthalmic Hosp.; late Clinical AssH, Moorfields, London, A Handbook of Ophthalmic Science and Practice. In one handsome octavo volume of 460 pages, with 125 woodcuts, 27 colored plates, and selections from the Test-types of Jaej^cr and Snellen. Cloth, $4.50; leather, $5.50. Jitst ready. This work is distinguished by the great num- ber of colored plates which appear in it for illus- trating various pathological conditions. They are very oeautiful in appearance, and have been executed with great care as to accuracy. An ex- amination of the work shows it to be one of high standing, one that will be regarded as an authority among ophthalmologistf. The treatment recom- mended is such as the author has learned from actual experience to be the best. — Cincinnati Medi- cal News, Dec. 1884. It presents to the student concise descriptions and typical illu-sitrations of all important eye affections, placed in juxtaposition, so as to be § rasped at a glance. Beyond a doubt it is the est illustrated handbook of ophthalmic science which has ever appeared. Then, what is still better, these illustrations are nearly all original. We have examined this entire work with great care, and it represents the commonly accepted views of advanced ophthalmologists. We can most his book to all medical stu- heartily commend tl dents, practitioners Lancet, Jan. 1885, and specialists. — Detroit WMLLS, J. SOFLBBMG, F. M. C. S., Professor of Ophthalmology in King's College Hospital^ London, etc. A Treatise on Diseases of the Eye. Fourth American from the third London edition. Thoroughly revised, with copious additions, by Charles S. Buiii;, M. D., Surgeon and Pathologist to the New York Eye and Ear Infirmary. In one large octavo volume of 822 pages, with 257 illustrations on wood, six colored plates, and selections from the Test- types of Jaeger and Snellen. Cloth, |5.00 ; leather, $6.00 ; half Russia, $6.50. The present edition appears in less than three years since the publication of the last American edition, and yet, from the numerous recent inves- tigations that have been made in this branch of medicine, many changes and additions have been required to mpet the present scope of knowledge upon this subject. A critical examination at once shows the fidelity and thoroughness with which the editor has accomplished his part of the work. The illustrations throughout are good. This edi- tion can be recommended to all as a complete treatise on diseases of the eye, than which proba- bly none better exists. — Medical Record, Aug. 18, '83. NBTTLFSMIF, BDWAItJy, F. It. C. S., Ophtlmlmic Surg, and Led. on Ophth. Swrg. at St. Thomas' Hospital, Lmdon. The Student's Guide to Diseases of the Eye. Second edition. With a chap- ter on the Detection of Color-Blindness, by William Thomson, M. D., Ophthalmologist to the Jefferson Medical College. In one royal 12mo. volume of 416 pages, with 138 iUustrations. Cloth, $2.00. This admirable guide bids fair to become tlie favorite text-book on ophthalmic surgery with stu- dents and general practitioners. It bears through- out the imprint of sound judgment combined with vast experience. The illustrations are numerous and well chosen. This book, within the short com- pass of about400 pages, contains a lucid exposition of the modem aspect of ophthalmic science. — Medical Record^ June 23, 1883. BBOWNF, BUG AH A., Surgeon to the Liverpool Bye ami Ear Infirmary and to the Dispensary for Skin Diseases. How to Use the Ophthalmoscope. Being Elementary Instructions in Oph- thalmoscopy, arranged for the use of Students. In one small royal 12mo. volume of 116 pages, with 35 illustrations. Cloth, $1.00. LAWSON ON INJURIES TO THE EYE, DEBIT titioners. Second edition. In one octavo vol- AND EYELIDS : Their Immediate and Eemote ume of 227 pages, with 66 illust. Cloth, $2.76. Effects. 8 vo., 404 pp., 92 illus. Cloth, «3.60. CARTEE'S PEACTICAL TREATISE ON DISEAS- LAUEENCE AND MOON'S HANDY BOOK OF ES OP THE EYE. Edited by John Geeen, M. D. OPHTHALMIC SURGERY, for the use of Prao- In one handsome octavo volume. 24 Lea Brothers & Co.'s Publications — Otol., Urin, Dis., Dent. BUBJSrjETT, CMAULES M., A. M., M. JD., Professor of Otology in the Philadelphia Polyclinic; PreBident of the AmeHcam Otological Society, The Ear, Its Anatomy, Physiology and Diseases. A Practical Treatise for tlie use of Medical Students and Practitioners. New (second) edition. In one handsome octavo volume of 580 pages, with 107 illustrations. Cloth, $4.00 ; leather, 15.00. Justreajdy* carried out, and much new matter added. Dr. We note with pleasure the appearance of a second edition of this valuable work. When it first came out ifc was accepted by the profession as one of the standard works on modern aural surgery; in the English language; and in his second edition Dr. Burnett has fully maintained his reputation, for the book is replete with valuable information and suggestions. The revision has been carefully Burnett's work must be regarded as a very valua- ble contribution to aural surgery, not only on account of its comprehensiveness, but because it contains the results of the careful personal observa- tion and experience of this eminentaural surgeon. — London Lancet, Feb. 21, 1885. POLITZEB, AID AM, Imperial- Royal Prof, of Aural Therap. in the Univ. of Vienna. A Text-Book of the Ear and its Diseases. Translated, at the Author's re- quest, by James Patterson Cassells, M. D., M. K. C. S. In one handsome octavo vol- ume of 800 pages, with 257 original illustrations. Cloth, $5.50. The work itself we do not hesitate to pronounce the best upon the subject of aural diseases which has ever appeared, systematic without beitig too diffuse on obsolete subjects, and eminently prac- tical in every sense. The anatomical descriptions of each separate division of the ear are admirable, and profusely illustrated by woodcuts. They are followed immediately by the physiology of the section, and this again by the pathological physi- ology, an arrangement which serves to keep up the interest of the student by showing the direct ap- plication of what has preceded to the study of dis- ease. The whole worK can be recommended as a reliable guide to the student, and an efficient aid to the practitioner in his treatment. — Boston Med- ical ana Surgical Journal, June 7, 1883. JEtOBEBTS, WILLIAM, M. I)., Lecturer on Medicine in the Manchester School of Medicine, etc. A Practical Treatise on Urinary and B.enal Diseases, including Uri- nary Deposits. Fourth American from the fourth London edition. In one hand- some octavo volume of 609 pages, with 81 illustrations. Cloth, $3.50, Jitst r.eady. The peculiar value and finish of the book are derived from its resolute maintenance of a clinical and practical character. This volume is an un- rivalled exposition of everything which relates directly or indirectly to the diagnosis, prognosis and treatment of urinary diseases, and possesses a completeness not found elsewhere in our laa- gna.ge.-~The Medical Chronicle, July, 1885. q. GBOSS, 8. D., M. n., LL. !>., D. C. L., etc. A Practical Treatise on the Diseases, Injuries and Malformations of the Urinary Bladder, the Prostate Gland and the Urethra. Third edition, thoroughly revised by Samuel W. Gross, M. D., Professor of the Principles of Surgery and of Clinical Surgery in the Jefferson Medical College, Philadelphia. In one octavo volume of 574 pages, with 170 illustrations. Cloth, $4.50. MOBBI8, MBNBY, M. B., F. B. C. S., Surgeon to and Lecturer on Surgery at Middlesex Hospital, London. Surgical Diseases of the Kidney. In one 12mo. volume. Preparing. See Series of Clinical Manuals, page 3. LUCAS, CLEMBWT, M. B., B. S., F. B. C. S., Senior Assistant Su/rgeon to Guy^s Hospital, London. Diseases of the Urethra. In one 12mo. volume. Prepanng. See Series of Clinical Maniuds, page 3. THOMPSON, SIB MENBT, Surgeon and Professor of Clinical Surgery to University College Hospital, London. Lectures on Diseases of the Urinary Organs. Second American from the third English edition. In one 8vo. volume of 203 pp., with 25 illustrations. Cloth, $2.25. By the Same Author. On the Pathology and Treatment of Stricture of the Urethra and Urinary Fistulse. From the third English edition. In one octavo volume of 359 pages, with 47 cuts and 3 plates. Cloth, $3.50. COLEMAJf, A., L. B. C. B., F. B. C. S., Fxam. L. D. S., Senior Dent. Surg, and Lect. on. Dent. Surg, at St. Bartholomew's Hosp. and the Dent. Hosp., London. A Manual of Dental Surgery and Pathology. Thoroughly revised and adapted to the use of American Students, by Thomas C. Stbllwagen, M. A., M. D., D. V. S., Prof, of Physiology at the Philadelphia Dental College. In one handsome octavo volume of 412 pages, with 331 illustrations. Cloth, $3.25. BASHAM ON RENAL DISEASES : A Clinical I one 12mo. Yol. of 304 pages, with 21 illustratlom. Guide to their Diagnosis and Treatment. In | Cloth, $2.00. Lea Brothers & Co.'s Fublicaiions — Veuereal, Imiiotence. 25 BVM8TEAD, F. J., M. D., LL. D., Late Professor of Venereal Diseases at the College of Physicians and Surgeons, New York, etc. and TAYLOB, B. W., A. M., M. D., J Surgeon to Oiarity Hospital, New York, Prof, of Venereal and Skin Diseases in the University of Vermont, Pres. of the Am. Dermatological Ass^n. The Pathologjr and Treatment of Venereal Diseases, Including the results of recent investigations upon the subject. Fifth edition, revised and largely re- written, by Dr. Taylor. In one large and handsome octavo volume of 898 pages with 139 illustrations, and thirteen chromo-lithographic figures. Cloth, $4.75 ; leather, $5.75 ; very handsome half Eussia, $6.25. It is a splendid record of honest labor, wide research, just comparison, careful scrutiny and original experience, which will always be held as a high credit to American medical literature. This is not only the best work in the English language upon the subjects of which it treats, but also one which has no equa. in other tongues for its clear, comprehensive and practical handling of its themes. — American Journal of the Medical Sciences, Jan, 1884. It is certainly the best single treatise on vene- real in our own, and probably the best in any lan- guage. — Boston Medical and Surgical JournaL April 3, 1884. The character of this standard work is so well known that it would be superfluous here to pass in review its general or special points of excellence. The verdict of the profession has been passed; it has been accepted as the most thorough and com- plete exposition of the pathology and treatment of venereal diseases in the language. Admirable as a model of clear description, an exponent of sound pathological doctrine, and a guide for rational and successful treatment, itisanornamenttothemedi- cal literature of this country. The additions made to the present edition are eminently judicious, from the standpointof practical utility. — Journal oj Cutaneous and Venereal Diseases, Jan. 1884. COBNIL, v., Professor to the Faculty of Medicine of Paris, and Physician to the Lourcine Hospital. Syphilis, its Morbid Anatomy, Diagnosis and Treatment. Specially revised by the Author, and translated with notes and additions by J. Henky C. Simes, M. D., Demonstrator of Pathological Histology in the University of Pennsylvania, and J. WiiiiiAM White, M. D., Lecturer on Venereal Diseases and Demonstrator of Surgery in the University <5f Pennsylvania. In one handsome octavo volume of 461 pages, with 84 very beautiful illustrations. Cloth, $3.75. The anatomical and histological characters of the hard and soft sore are admirably described. The multiform cutaneous manifestations of the disease are dealt with histologically in a masterly way, as we should indeed expect them to be, and the accompanying illustratipns are executed carefully and well. The various nervous lesions which are the recognized outcome of the syphilitic dyscrasia are treated with care and consideration. Syphilitic epilepsy, paralysis, cerebral syphilis and locomotor ataxia are subjects full of interest ; and nowhere in the whole volume is the clinical experience of the author or the wide acquaintance of the translators with medical literature more evident. The anat- omy, the histology, the pathology and the clinical features of syphilis are represented in this work in their best, most practical and most instructive form, and no one will rise from its perusal without the feeling that his grasp of the wide and impor- tant subject on which it treats is a stronger and surer one. — The London Practitioner, Jan. 1882. HUTCSIWSOJSr, JOJS^AIJIAJS^, F. B. S., F. B. C. S., Consulting Surgeon to the London Hospital, Syphilis. In one 12mo. volume. Preparing. See Series of Clinical Manualsy page 3. GBOSS, SAJMUEL W., A. M., M. D., Professor of the Principles of Surgery and of Clinical Su/rgery in the Jefferson Medical College. A Practical Treatise on Impotence, Sterility, and Allied Disorders of the Male Sexual Organs, Second edition, thoroughly revised. In one very hand- some octavo volume of 168 pages, with 16 illustrations. Cloth, $1.50. This work will derive value from the high stand- The author of this monograph is a man of posi- tive convictions and vigorous style. This is justi- fied by his experience and by his study, which has gone hand in hand with his experience. In regard to the various organic and functional disorders of the male generative apparatus, he has had ex- ceptional opportunities for observation, and his book shows that he has not neglected to compare his own views with those of other authors. The result is a work which can be safely recommended to both physicians and surgeons as a guide in the treatment of the disturbances it refers to. It is the best treatise on the subject with which we are acquainted.— r^e Medical News, Sept. 1, 1883. ing of its author, aside from the fact of its passing so rapidly into its second edition. This is, indeed^ a book that every physician will be glad to place in his library, to be read with profit to himself, and with incalculable benefit to his patient. Be- sides the subjects embraced in the title, which are treated of in their various forms and degrees, spermatorrhoea and prostatorrhcea are also fully considered. The work is thoroughly practical in character, and will be especiany useful to the general practitioner. — Medical Mecord, Aug. 18^ 1883. CVLLBRIEn, A., & BVM8TEAD, F. J., M.I)., LL.n., Swrge&n to the Sdpiial du Midi. Late Profes8(yr of Venereal Diseases in the College of Physicians avd Swrgeons^Neno York. An Atlas of Venereal Diseases. Translated and edited by Fbeeman J. Bum- stead, M. D. In one imperial 4to. volume of 328 pages, double-columns, with 26 plates, containing about 150 figures, beautifully colored, many of them the size of life. Strongly bound in cloth, $17.00. A specimen of the plates and text sent by mail, on receipt of 25 cts. HILL ON SYPHILIS AND LOCAL CONTAGIOUS I FORMS OF LOCAL DISEASE AFFECTING DISORDERS. In one SvoYOl. of 479 p. Cloth. $3.25. PRINCIPALLY THE ORGANS OP GENERA- LEE'S LECTURES ON SYPHILIS AND SOME | TION. In one 8to. vol. of 246 pages. Cloth, $2.26. Missing Page Missing Page 28 Lea Brothers & Co.'s PaBLioATioNs — Dis. of Women, Midwty. EMMET, THOMAS ADIUS, M. D., LL. I)., Surgeon to the Woman^s Hospital, New York, etc. The Principles and Practice of Gynsecology ; For the use of Students and Practitioners of Medicine. New (third) edition, thoroughly revised. In one large and very handsome octavo volume of 880 pages, with 150 illustrations. Cloth, $5 ; leather, $6. {Just ready.) We are in doubt whether to congratulate the author moi'e than the profession upon the appear- ance of the third edition of this well-known work. Embodying, as it does, the life-long experience of one who has conspicuously distinguished himself as a bold and successful operator, and who has devoted so much attention to the specialty, we feel sure the profession will not fail to appreciate the privilege thus offered them of perusing the views and practice of the author. His earnestness of purpose and conscientiousness are manifest. He gives not only his individual experience but endeavors to represent the actual state of gynse- cological science and art. — British Medical Jour- nal, May 16, 1885. No jot or tittle of the high praise bestoiigsd upon the first edition is abated, It is still a book of marked personality, one based upon large clinical experience, containing large and valuable ad- ditions to our knowledge, evidently written not only with honesty of purpose, but with a conscien- tious sense of responsibility, and a book that is at once a credit to its author and to American med- ical literature. We repeat that it is a book to be studied, and one thac is indispensable to every prjictitioner giving any attention to gynsecology.^ American Journal of the Medical Sciences, April, 1885, The time has passed when Emmet's Gynascology was to be regarded as a book for a single country or for a single generation. It has always been his aim to popularize gyuEecology, to bring it within easy reach of the general practitioner. The orig- inality of the ideas, aside from the perfect con- fidence which we feel in the author's statements, compels our admiration and respect. We may well take an honest pride in Dr. Emmet's work and feel that his book can hold its own against the criticism of two continents. It represents all that is most earnest and most thoughtiul in American gyneecology. Emmet's work will continue to reflect the individuality, the sterling integrity and the kindly heart of its honored author long after smaller books have been forgotten. — American Journal of Obstetrics, May, 1885. Any work on gynfflcalogy by Emmet must always have especial interest and value. He has for many years" been an exceedingly bpsy prac- titioner in this department. Few men have had his experience and opportunities. As a guide either for the general practitioner or specialist, it is second to none other. No one can read Emmet without pleasure, instruction and profit. — Cincinnati Lancet and Clinic, Jan 31, 1885. DVJ^CAW, J. MATTBEWS, M.D., LL. D., F. B. S. JEJ., etc. Clinical Lectures on the Diseases of Women ; Delivered in Saint Bar- tholomew's Hospital. In one handsome octavo volume of 175 pages. Cloth, $1.50. They are in every way worthy of their author ; indeed, we look upon them as among the most valuable of his contributions. They are all upon matters of great interest to the general practitioner. Some of them deal with subjects that are not, as a rule, adequately handled in the text-books; others of them, while bearing upon topics that are usually treated of at length in such works, yet bear such a stamp of Individuality that, if widely read, as they certainly deserve to be, they cannot fail to exert a wholesome restraint upon the undue eagerness with which many young physicians seem bent upon following the wild teachings which so infest the gynsecology of the present day. — N. Y. Medical Journal, Marcii, 1880. MAT, C SABLES H., M. D. Late House Surgeon to Mount Smai Hospital, New Yerk. A Manual of the Diseases of Women. Containing a concise and systematic exposition of theory and practice. In one 12mo. volume of about 350 pages. In press. MODGE, jaUGSE., M. D., Emeritus Professor of Obstetrics, etc., in the University of Pennsylvania. On Diseases Peculiar to Women; Including Displacements of the Uterus. Second edition, revised and enlarged. In one beautifully printed octavo volume of 519 pages, with original illustrations. Cloth, $4.50. By the Same Author. The Principles and Practice of Obstetrics. Illustrated with large litho- graphic plates containing 159 figures from original photographs, and with numerous wood- cuts. In one large quarto volume of 542 double-columned pages. Strongly bound in cloth, $14.00. * ^* Specimens of the plates and letter-press will be forwarded to any address, free by mail, on receipt of six cents in postage stamps. BAMSBOTHAM, EBAJSTCIS JET., M. D. The Principles and Practice of Obstetric Medicine and Surgery; In reference to the Process of Parturition. A new and enlarged edition, thoroughly revised by the Author. With additions by W. V. Keating, M. D., Professor of Obstetrics, etc., in the Jefferson Medical College of Philadelphia. In one large and handsome imperial octavo volume of 640 pages, with 64 full-page plates and 43 woodcuts in the text, contain- ing in all nearly 200 beautiful figures. Strongly bound in leather, with raised bands, $7. ASHWELL'S PRACTICAL TREATISE ON THE DISEASES PECULIAR TO WOMEN. Third Americau from the third and revised London edition. In one 8vo. vol., pp. 620. Clotii. $^.60. CHURCHILL ON THE PUERPERAL FEVER AND OTHER DISEASES PECULIAR TO WO- MEN. In one 8vo. vol. of 464 pases. Cloth, 82.60. MEIGS ON THE NATURE, SIGNS AND TREAT- MENT OF CHILDBED FEVER. In one 8vo. volume of 346 pages. Cloth, $2.00. Lba BaoTHEEs & Co.'s Publications — Mldwifei-y. 29 JPLAYFAIB, W. 8., 31. D., F. B. C. P., iVo/esfior of Obstetric Medicine in King's College^ London, etc A Treatise on the Science and Practice of Midwifery. New (fourth) American, from the fifth English edition. Edited, with additions, by Egbert P. Har- ris, M. D. In one handsome octavo volume of 654 pages, with 3 plates and 201 engrav- ings Cloth, $4 ; leather, $5 ; half Eussia, $5.50. Just ready. This excellent work needs no commendation. For many years it has maintained a deservedly high reputation among teachers as a text book, and in the profession as a guide to the practical experiences which attend the obstetrician. The present edition, under the supervision of Dr. Har- ris, has been carefully revised, and many portions rewritten, and the whole work has been adapted to the wants and circumstances of this continent. — By^alo Medical and Surgical Journal, Aug. 1885. q. In the short time that this excellent and highly esteemed work has been before the profession it has reached a fourth edition in this country and a fifth one in England. This fact alone speaks in high praise of it, and it seems to us that scarcely more need be said of it in the way of endorsement of its value. As a text book for students and for the uses of the general practitioner there is no work on obstetrics superior to the work of Dr. Playfair. Its teachings are practical, written in plain language, and aitord a correct understanding of the art of midwifery. No one can be disap- pointed in it. — CH,ncinnati Medical News, June, 1885. BABNMS, BOBEBT, M.J)., and FAWCOUBT, M. JD., Phys. to the General Lying-in Hoap.y Land. Obstetric Phys. to St. Thomas' Kosp., Lond. A System of Obstetric Medicine and Surgery, Theoretical and Clin- ical. For the Student and the Practitioner. The Section on Embryology contributed by Prof. Milnes Marshall. In one handsome octavo volume of about 1000 pages, profusely illustrated. Clbth, ?5 ; leather, $6. In a few days. BABKFB, FOBDYCF, A. M., M. D., LL. D. Fdin., Clinical Professor of Midwifery and the Diseases of Women in the Bellevue Hospital Medical Oollege, New York., Honorary Fellow of the Obstetrical Societies of London and Edinburgh, etc., etc. Obstetrical and Clinical Essays. In one handsome 12mo. volume of about 300 pages. Preparing. KIWG, A. F. A., M. J)., Professor of Obstetrics and Diseases of Women m the Medical Department of the Columbian Univer- sity, Washington, D. C, arid in the University of Ve/rmont, etc. A Manual of Obstetrics. Second edition. In one very handsome 12mo. volume of 331 pages, with 59 illustrations. Cloth, $2.00. It must be acknowledged that this is just what it pretends to be — a sound guide, a portable epit- ome, a work in which only indispensable matter has been presented, leaving out all fiadding and chaff, and one in which the student will find pure wheat or condensed nutriment. — New Orleans Med- ical and Surgical Journal, May, 1884. In a series of short paragraphs and by a con- densed style of composition, the writer has pre- sented a great deal of what it is well that every obstetrician should know and be ready to practice or prescribe. The fact that the demand for the volume has been such as to exhaust the first edition in a little over a year and a half speaks well for its popularity. — American Journal of the Medical Sciences, April, 1884. LANDIS, HFNBY G., A. M., M. J)., Professor of Obstetrics and the Diseases of Women in Starling Medical College, Columbus, 0. The Management of Labor. In one handsome 12mo. volume of about 300 pages, with 30 illustrations. Shortly. BABNES, FAJSrCOUBT, M. D., Obstetric PhysicAam to St. Thomas'' Hospital, London. A Manual of Midwifery for Midwives and Medical Students. In one royal 12mo. volume of 197 pages, with 50 illustrations. Cloth, $1.25. FABnJSr, TMEOFMILTIS, M. D., LL. It., Professor of Obstetrics and the Diseases of Wom^n and Children in the Jefferson Medical College. A Treatise on Midwifery. In one very handsome octavo volume of about 550 pages, with numerous illustratipns. In press. PABBT, JOSW S., M. D., Obstetrician to the Philadelphia Bospital, Vice-President of the Obstet. Society of Philadelphia. Extra - Uterine Pregnancy: Its Clinical History, Diagnosis, Prognosis and Treatment. In one handsome octavo volume of 272 pages. Cloth, |2.50. lAJfNFB, TSOMAS SAWKFS, M. D. On the Signs and Diseases of Pregnancy. First American from the second English edition. Octavo, 490 pages, with 4 colored plates and 16 woodcuts. Cloth, |4.25. WINCKFL, F. A Complete Treatise on the Pathology and Treatment of Childbed, For Students and Practitioners. Translated, with |the consent of the Author, from the second German edition, by J. E. Chadwick, M. D. | Octavo 484 pages. Cloth, $4.00. 30 Lea Brothers & Co.'s Publications — Midwfy., Dis. CWldii. LEISHMAJS^, WILLIAM, M. D., Regms Professor of Midwifery in the University of Glasgow, etc. A System of Midwifery, Including the Diseases of Pregnancy and the Puerperal State. Third American edition, revised by the Author, with additions by John S. Paeby, M. D., Obstetrician to the Philadelphia Hospital, etc. In one large and very handsome octavo volume of 740 pages, with 205 illustrations. Cloth, $4.50 ; leather, $5.50 ; very handsome half Kussia, raised bands, $6.00. The author is broad in his teachings, and dis- cusses briefly the comparative anatomy of the pel- vis and the mobility of the pelvic articulations. The second chapter is devoted especially to the siudy of the pelvis, while in the third the female organs or generation are introduced. The structure and development of the ovum are admirably described. Then follow chapters upon the various subjects embracedin the study of mid- wifery. The descriptions throughout the work are plain and pleasing. It is sufficient to state that in this, the last edition of this well-known work, every recent advancement in this field has been brought forward — Physician and Surgeon, Jan, 1880. We gladly welcome the new edition of t^iis ex- cellent text-book of midwifery. The former edi- tions have been most favorably received by the profession on both sides of the Atlantic. In the preparation of the present edition the author has made such alterations as the progress of obstetri- cal science seems to require, and we catmot but admire the ability with which the tagk has been performed. We consider it an admirable text- book for students during their attendance upon lectures, and have, great pleasure in recommend- ing it. As an exponent of the midwifery of the present day it has no superior in the English lan- guage. — Canada Lancet, Jan. 1880. To the American student the work before us must prove admirably adapted. Complete in all its Sarts, essentially modern m its teachings, and with emonatrations noted for clearness and precision, it will gain in favor and be recognized as a work of standard merit. The work cannot fail to be popular and is cordially recommended. — N. O. Med. and Sii/rg. Jowrn., March, 1880. SMITM, J. LEWIS, M. D., Clinical Professor of Diseases of Children in the Bellevue Hospital Medical College, N. T, A Complete Practical Treatise on the Diseases of Children. Fifth edition, thoroughly revised and rewritten. In one handsome octavo volume of 836 pages, with illustrations. Cloth, $4.50 ; leather, $5.60 ; very handsome half Eussia, raised bands, $6. This is one of the best books on the subject with which we have met and one that has given us satisfaction on every occasion on which we have consulted itj either as to diagnosis or treatment. It is now in its fifth edition and in its present form is a very adequate representation of the subject it treats of as at present understood. The important subject of infant hygiene is fully dealt with in the early portion of the Dook. The great bulk of the work is appropriately devoted to the diseases of infancy and childhood. We would recommend any one in need of Information on the subject to procure the work and form his own opinion on it, which we venture to say will be a favorable one. — Dublin Journal of Medical Science, March, 1883. There is no book published on the subjects of which this one treats that is its equal in value to the physician. While he has said just enough to impart the information desired by general practi- tioners on such questions a& etiology, pathology, prognosis, etc., he has devoted more attention to the diagnosis and treatment of the ailments which he so accurately^ describes ; and such information is exactly what is wanted by the vast majority of " family physicians." — Va. Med. Monthly, Feb. 1882. In KMATING, JOMNM., M. ID., Lectwr&r on the Diseases vf Children at the University of Pennsylvania^ etc. The Mother's Guide in the Management and Feeding of Infants. one handsome 12mo. volume of 118 pages. Cloth, $1.00, the employment of a wet-nurse, about the proper food for a nursing mother, about the tonic eifects of a bath, about the perambulator versus the nurses, arms, and on many other subjects concerning which the critic might say, "surely this is obvf Works like this one will aid the physician im- mensely, for it saves the time he is constantly giv- ing his patients in instructing them on the sub- jects here dwelt upon so thoroughly and prac- tically. Dr. Keating has written a practical book, has carefully avoided unnecessary repetition, and successfully instructed the mother in such details of the treatment of her child as devolve upon her. He has studiously omitted giving prescriptions, and instructs the mother when to call upon the doctor, as his duties are totally distinct from hers. — American Jov/mal of Obstetrics, October, 1881. Dr. Keating has kept clear of the common fault of works of this sort, viz., mixing the duties of the mother with those proper to the doctor. There Is the ring of common sense in the remarks about ous," but which experience teaches us are exactly the things needed to be insisted upon, with the rich as well as the poor. — London Lancet, January, 28 1882. A book small in size, written in pleasant style, in language which can be readily understood by any mother, and eminently practical and safe; in fact a book for which we have been waiting a long time, and which we can most heartily recommend to mothers as the book on this subject.— iVew Y servation and experience. A careful examjnatiod of the work convinces us that he has accomplishen his task with painstaking fidelity and with a cred- itable result. — Journal <^ Cutaneous and Venereal Diseases, June, 1883. FOX, T., M.jy., F.M. C. P., and FOX, T. C, B.A., M.B. C.8., Physician to the Depa/rtment for Skin IHseases, Physician for Ifiseases of the Skin to the University College Hospital, London. Westminster Hospital, London. An Epitome of Skin Diseases. With Formnlse. For Students and Prac- titioners. Third edition, revised and enlarged. In one very handsome 12mo. volume of 238 pages. Cloth, $] .25. The third edition of this convenient handbook calls for notice owing to the revision and expansion which it has undergone. The arrangement of skin diseases in alphabetical order, which is the method of classification adopted in this work, becomes a positive advantage to the student. ■ The book is one which we can strongly recommend, not only to students but also to practitioners who require a compendious summary of the present state of dermatology. — British Medical Jowrnal, July 2, 1883. We cordially recommend Fox's B>pitome to those whose time is limited and who wish a handy manual to lie upon the table for instant reference. Its alphabetical arrangement is suited to this use, for all one has to know is the name of the disease, and here are its description and the appropriate treatment at hand and ready for instant applica- tion. The present edition has been very careftilly revised and a number of new diseases are de- scribed, while most of the recent additions to dermal therapeutics find mention, and the formu- lary at the end of the book has been considerably augmented.— T/ie Medical News, December, 1883. MOBBIS, MALCOLM, M. I)., Joint Lecturer on Dermatology at St. Mary's Hospital Medical School, London. Skin Diseases ; Including their Definitions, Symptoms, Diagnosis, Prognosis, Mor- bid Anatomy and Treatment. A Manual for Students and Practitioners. In one 12mo. volume of 316 pages, with illustrations. Cloth, $1.76. To physicians who wouldlike to know something about skin diseases, so that when a patient pre- sents himself for relief they can make a correct diagnosis and prescribe a rational treatment, we unhesitatingly recommend this little book oi Dr. Morris. The affections of the skin are described in a terse, lucid manner, and their several charac- teristics so plainly set forth that diagnosis will be easy. The treatment in each case is such as the experience of the mosteminent dermatologists ad- vises. — Cincinnati Medical News, April, 1880. This is emphatically a learner's book; for we can safely say, that in the whole range of medical literature there is no book of a like scope which for clearness of expression and methodical ar- rangement is better adapted to promote a rational conception of dermatology — a branch confessedly difiicult and perplexing to the beginner. — St. Louis Cov/ri&r of Medicine, April, 1880. The writer has certainly given in a small compass a large amount of well-compiled information, and his little book compares favorably with any other which has emanated from England, while in many points he has emancipated himself from the stub- bornly adhered to errors of others of his country- men. There is certainly excellent material in the book which will well repay perusal. — Boston Med. and Surg. Jowrn., March, 1880. WILSON, FBASMUS, F. B. S. The Student's Book of Cutaneous Medicine and Diseases of the Skin. In one handsome small octavo volume of 535 pages. Cloth, $3.50. MILLIEB, THOMAS, M. !>., Physician to the Shin I>epa/rtment of University College, London. Handbook of Skin Diseases; for Students and Practitioners. Second Ameri- can edition. In one 12mo. volume of 353 pages, with plates. Cloth, $2.25. Lea Brothers & Co.'s Publications — Dis. of Women. 27 AJif AMEBICAJSr SYSTEM OF GYJS^MCOLOGT. A. System of GynsBcology, in Treatises by Various Authors. Edited by Matthew D. Mann, M. D., Professor of Obstetrics and Gynjecology in the -Uni- versity of Buffalo, N. Y. In two handsome octavo volumes, richly illustrated. In active preparation. LIST OF CONTRIBUTORS. WILLIAM H. BAKER, M. D., FORDYCE BARKER, M. D., ROBERT BATTEY, M. D., SAMUEL C. BUSBY, M. D., HENRY P. CAMPBELL, M. D., HENRY 0. COB, M. D., E. C. DUDLEY, M. D., GEORGE J. ENGELMANN, M. D., HENRY P. GARRIGUES, M. D., WILLIAM GOODELL, M. D., EGBERT H. GRANDIN, M. D., SAMUEL W. GROSS, M. D., JAMES B. HUNTER, M. D., A. REEVES JACKSON, M. D., EDWARD W. JENKS, M. D., WILLIAM T. LUSK, M. D., MATTHEW D. MANN, M. D., ROBERT B. MAURY, M. D., PAUL F. MUNDB, M. D., C. D. PALMER, M. D., WILLIAM M. POLK, M. D., THADDEUS A. BEAMY, M. D., A. D. ROCKWELL, M. D., ALEX. J. C. SKENE, M. D., R. STANSBURY SUTTON, A. M., M. D., T. GAILLARD THOMAS, M. D., ELI VAN DE WALKER, M. D., W. GILL WYLIE, M. D. THOMAS, T. aAILLABD, M. ID., Professor of Diseases of Women in the College of Physicians and Swrgeons, N. 7, ^ A Practical Treatise on the Diseases of Women- Fifth edition, thoroughly- revised and rewritten. In one large and handsome octavo volume of 810 pages, with 266 illustrations. Cloth, |5.00 ; leather, $6.00 ; very handsome half Russia, raised bands, |6.50. The words which follow " fifth edition" are in this case no mere formal announcement. The alterations and additions which have been made are both numerous and important. The attraction and the permanent character of this book lie in the clearness and truth of the clinical descriptions of diseases; the fertility of the author in thera- peutic resources and the fulness with which the details of treatment are described; the definite character of the teaching ; and last, but not least, the evident candor which pervades it. We would also particularize the fulness with which the his- tory of the subject is gone into, which makes the book additionally interesting and gives it value as a work of reference. — London Medical Times and Gazette, July 30, 1881. The determination of the author to keep his book foremost in the rank of works on gyneecology is most gratifying. Recognizing the fact that this can only be accomplished by frequent and thor- ough revision, he has spared no pains to make the present edition more desirable even than the pre- vious one. As a book of reference for the busy practitioner it is unequalled. — Boston Medical any Surgical Journal, April 7, 1880. It has been enlarged and carefully revised. It is a condensed encycTopsedia of gynfficological medi- cine. The style of arrangement, the masterly manner in which each subject is treated, and the honest convictions derived from probably the largest clinical experience in that specialty of any in this country, all serve to commend it in the highest terms to the practitioner. — Nashville Jow. of Med. and Surg., Jan. 1881. That the previous editions of the treatise of Dr. Thomas were thought worthy of translation into German, French, Italian and Spanish, is enough to give it the stamp of genuine merit. At home it has made its way into the library of every obstet- rician and gynsecologist as a safe guide to practice. No small number of additions have been made to the present edition to make it correspond to re- cent improvements in treatment. — Pacific Medical and Surgical Journal, Jan. 1881. EltlS, AMTJETCfB W., M. D., Lond., F.R. C.JP., M.R. C.S., Assist. Obstetric Physician to Middlesex Hospital, late Physician to British Lying-in Hospital. The Diseases of Women. Including their Pathology, Causation, Symptoms, Diagnosis and Treatment. A Manual for Students and Practitioners. In one handsome octavo volume of 576 pages, with 148 illustrations. Cloth, $3.00 ; leather, $4.00, It is a pleasure to read a book so thoroughly good as this one. The special qualities which are conspicuous are thoroughness in covering the whole ground, clearness of description and con- ciseness of statement. Another marked feature of the book is the attention paid to the details of many minor surgical operations and procedures, as, for instance, the use of tents, application of leeches, and use of hot water injections. These are among the more common methods of treat- ment, and yet very little is said about them in many of the textrbooks. The book is one to be warmly recommended especially to students and generaJ practitioners, who need a concise but com- plete r^suTHi of the whole subject. Specialists, too, will find many useful hints in its pages. — Boston M&i. and Swrg. Jowrn., March 2, 1882. The greatest pains have been taken with the sections relating to treatment. A liberal selection of remedies is given for each morbid condition, the strength, mode of application and other details being fully explained. The descriptions of gynte- cological manipulations and operations are full, clear and practical. Much care has also been be- stowed on the parts of the book which deal with diagnosis — we note especially the pages dealing with the differentiation, one from another, of the different kinds of abdominal tumors. The prac- titioner will therefore find in this book the Kind of knowledge he most needs in his daily work, and he will be pleased with the clearness and fulness of the information there given. — The Practitioner, Feb. 1882. BABJV^S, ROBERT, M. D., F. B. C. P., Obstetric Physician to St. Thomas^ Hospital^ London, etc. A Clinical Exposition of the Medical and Surgical Diseases of Women. In one handsome octavo volume, with numerous illustrations. New edition. Preparing. WEST, CHARLES, M. D. Lectures on the Diseases of Women. Third American from the third Lon- don edition. In one octavo volume of 543 pages. Cloth, $3.75 ; leather, $4.75.